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Sample records for buffer gas cooled

  1. Buffer gas cooling of ion beams

    International Nuclear Information System (INIS)

    The cooling action of a buffer gas on ions contained within it can be used to cool an ion beam, thereby greatly improving its emittance and energy spread. It can also be used to greatly enhance the collection of an ion beam in an electromagnetic trap. The basic principles will be introduced in the context of a prototype system for such a beam cooler

  2. Efficient rotational cooling of Coulomb-crystallized molecular ions by a helium buffer gas.

    Science.gov (United States)

    Hansen, A K; Versolato, O O; Kłosowski, L; Kristensen, S B; Gingell, A; Schwarz, M; Windberger, A; Ullrich, J; López-Urrutia, J R Crespo; Drewsen, M

    2014-04-01

    The preparation of cold molecules is of great importance in many contexts, such as fundamental physics investigations, high-resolution spectroscopy of complex molecules, cold chemistry and astrochemistry. One versatile and widely applied method to cool molecules is helium buffer-gas cooling in either a supersonic beam expansion or a cryogenic trap environment. Another more recent method applicable to trapped molecular ions relies on sympathetic translational cooling, through collisional interactions with co-trapped, laser-cooled atomic ions, into spatially ordered structures called Coulomb crystals, combined with laser-controlled internal-state preparation. Here we present experimental results on helium buffer-gas cooling of the rotational degrees of freedom of MgH(+) molecular ions, which have been trapped and sympathetically cooled in a cryogenic linear radio-frequency quadrupole trap. With helium collision rates of only about ten per second--that is, four to five orders of magnitude lower than in typical buffer-gas cooling settings--we have cooled a single molecular ion to a rotational temperature of 7.5(+0.9)(-0.7) kelvin, the lowest such temperature so far measured. In addition, by varying the shape of, or the number of atomic and molecular ions in, larger Coulomb crystals, or both, we have tuned the effective rotational temperature from about 7 kelvin to about 60 kelvin by changing the translational micromotion energy of the ions. The extremely low helium collision rate may allow for sympathetic sideband cooling of single molecular ions, and eventually make quantum-logic spectroscopy of buffer-gas-cooled molecular ions feasible. Furthermore, application of the present cooling scheme to complex molecular ions should enable single- or few-state manipulations of individual molecules of biological interest. PMID:24670662

  3. Novel Applications of Buffer-Gas Cooling to Cold Atoms, Diatomic Molecules, and Large Molecules

    OpenAIRE

    Drayna, Garrett Korda

    2016-01-01

    Cold gases of atoms and molecules provide a system for the exploration of a diverse set of physical phenomena. For example, cold gasses of magnetically and electrically polar atoms and molecules are ideal systems for quantum simulation and quantum computation experiments, and cold gasses of large polar molecules allow for novel spectroscopic techniques. Buffer-gas cooling is a robust and widely applicable method for cooling atoms and molecules to temperatures of approximately 1 Kelvin. In thi...

  4. Buffer-Gas Cooling of a Single Ion in a Multipole Radio Frequency Trap Beyond the Critical Mass Ratio

    Science.gov (United States)

    Höltkemeier, Bastian; Weckesser, Pascal; López-Carrera, Henry; Weidemüller, Matthias

    2016-06-01

    We theoretically investigate the dynamics of a trapped ion immersed in a spatially localized buffer gas. For a homogeneous buffer gas, the ion's energy distribution reaches a stable equilibrium only if the mass of the buffer gas atoms is below a critical value. This limitation can be overcome by using multipole traps in combination with a spatially confined buffer gas. Using a generalized model for elastic collisions of the ion with the buffer-gas atoms, the ion's energy distribution is numerically determined for arbitrary buffer-gas distributions and trap parameters. Three regimes characterized by the respective analytic form of the ion's equilibrium energy distribution are found. Final ion temperatures down to the millikelvin regime can be achieved by adiabatically decreasing the spatial extension of the buffer gas and the effective ion trap depth (forced sympathetic cooling).

  5. High-resolution mid-infrared spectroscopy of buffer-gas-cooled methyltrioxorhenium molecules

    CERN Document Server

    Tokunaga, Sean; Tarbutt, M; Darquié, B

    2016-01-01

    We demonstrate cryogenic buffer-gas cooling of gas-phase methyltrioxorhenium (MTO). This molecule is closely related to chiral organometallic molecules where the parity-violating energy differences between enantiomers may be measurable. The molecules are produced with a rotational temperature of approximately 6~K by laser ablation of an MTO pellet inside a cryogenic helium buffer gas cell. Facilitated by the low temperature, we demonstrate absorption spectroscopy of the 10.2~$\\mu$m antisymmetric Re=O stretching mode of MTO with a resolution of 8~MHz and a frequency accuracy of 30~MHz. We partially resolve the hyperfine structure and measure the nuclear quadrupole coupling of the excited vibrational state.

  6. Buffer gas loading and Doppler cooling of strontium ions in a planar Paul trap

    Science.gov (United States)

    Clark, Robert; Brown, Kenneth; Labaziewicz, Jaroslaw; Richerme, Philip; Chuang, Isaac

    2006-05-01

    Traditional geometries for ion traps involve three dimensional structures which may be difficult to assemble in complex geometries demanded by applications such as large-scale quantum computation. Planar Paul traps provide an alternative approach [Chiaverini et. al., Quant. Inf. Comput. 5, 419 (2005)], in which the RF and DC electrodes are placed in a single plane, providing simpler fabrication and greater optical access to the trapped ions. We have designed and constructed a planar Paul trap using copper electrodes on a Rogers 4350 substrate. Strontium ions were loaded into this structure at UHV, and also at high vacuum using helium buffer gas cooling. The temperature of the ion cloud as a function of buffer gas pressure is compared to predictions from a model which includes ion-helium collisions and RF heating. The measured trap parameters, including secular frequencies, trap depth, and RF heating rates, agree well with a pseudopotential model based on finite-element electrostatic calculations.

  7. Cooling, Collisions and non-Sticking of Polyatomic Molecules in a Cryogenic Buffer Gas Cell

    OpenAIRE

    Piskorski, Julia Hege

    2014-01-01

    We cool and study trans-Stilbene, Nile Red and Benzonitrile in a cryogenic (7K) cell filled with low density helium buffer gas. No molecule-helium cluster formation is observed, indicating limited atom-molecule sticking in this system. We place an upper limit of 5% on the population of clustered He-trans-Stilbene, consistent with a measured He-molecule collisional residence time of less than \\(1 \\mu s\\). With several low energy torsional modes, trans-Stilbene is less rigid than any molecule p...

  8. Buffer gas cooling of ions stored in an R.F. trap: Computed properties of the ionic cloud

    International Nuclear Information System (INIS)

    The spatial and energetic properties of an ion cloud confined in an RF quadrupole trap, together with the lifetimes of the confined ions, have been computed by statistical methods and recently by a simulation method. The influences of different parameters such as ion mass, buffer gas mass, working point in the stability diagram, 'weak' space-charge and shape of the velocity distribution of the cooling buffer gas have been investigated and are described. (orig.)

  9. Formation of van der Waals molecules in buffer gas cooled magnetic traps

    CERN Document Server

    Brahms, N; Zhang, P; los, J K; Sadeghpour, H R; Dalgarno, A; Doyle, J M; Walker, T G

    2010-01-01

    We show that a large class of helium-containing cold polar molecules form readily in a cryogenic buffer gas, achieving densities as high as 10^12 cm^-3. We explore the spin relaxation of these molecules in buffer gas loaded magnetic traps, and identify a loss mechanism based on Landau-Zener transitions arising from the anisotropic hyperfine interaction. Our results show that the recently observed strong T^6 thermal dependence of spin change in buffer gas trapped silver (Ag) is accounted for by the formation and spin change of AgHe, thus providing evidence for molecular formation in a buffer gas trap.

  10. Formation of van der Waals molecules in buffer gas cooled magnetic traps

    OpenAIRE

    Dalgarno, Alexander; Brahms, Nathan; Tscherbul, Timur; Zhang, Peng; Klos, Jacek; Sadeghpour, Hossein R.; Doyle, John M.; Walker, Thad G.

    2010-01-01

    We predict that a large class of helium-containing cold polar molecules form readily in a cryogenic buffer gas, achieving densities as high as 10\\(^{12}\\)  cm\\(^{-3}\\). We explore the spin relaxation of these molecules in buffer-gas-loaded magnetic traps and identify a loss mechanism based on Landau-Zener transitions arising from the anisotropic hyperfine interaction. Our results show that the recently observed strong \\(T^{-6}\\) thermal dependence of the spin-change rate of silver (Ag) trappe...

  11. Doppler-free laser spectroscopy of buffer gas cooled molecular radicals

    CERN Document Server

    Skoff, S M; Tarbutt, M R; Hudson, J J; Segal, D M; Sauer, B E; Hinds, E A

    2009-01-01

    We demonstrate Doppler-free saturated absorption spectroscopy of cold molecular radicals formed by laser ablation inside a cryogenic buffer gas cell. By lowering the temperature, congested regions of the spectrum can be simplified, and by using different temperatures for different regions of the spectrum a wide range of rotational states can be studied optimally. We use the technique to study the optical spectrum of YbF radicals with a resolution of 30 MHz, measuring the magnetic hyperfine parameters of the electronic ground state. The method is suitable for high resolution spectroscopy of a great variety of molecules at controlled temperature and pressure, and is particularly well-suited to those that are difficult to produce in the gas phase.

  12. Laser cooling of dense atomic gases by collisional redistribution of radiation and spectroscopy of molecular dimers in a dense buffer gas environment

    OpenAIRE

    Saß, Anne; Forge, Ralf; Christopoulos, Stavros; Knicker, Katharina; Moroshkin, Peter; Weitz, Martin

    2014-01-01

    We study laser cooling of atomic gases by collisional redistribution of fluorescence. In a high pressure buffer gas regime, frequent collisions perturb the energy levels of alkali atoms, which allows for the absorption of a far red detuned irradiated laser beam. Subsequent spontaneous decay occurs close to the unperturbed resonance frequency, leading to a cooling of the dense gas mixture by redistribution of fluorescence. Thermal deflection spectroscopy indicates large relative temperature ch...

  13. Production of cold beams of ND3 with variable rotational state distributions by electrostatic extraction of He and Ne buffer-gas-cooled beams

    International Nuclear Information System (INIS)

    The measurement of the rotational state distribution of a velocity-selected, buffer-gas-cooled beam of ND3 is described. In an apparatus recently constructed to study cold ion-molecule collisions, the ND3 beam is extracted from a cryogenically cooled buffer-gas cell using a 2.15 m long electrostatic quadrupole guide with three 90° bends. (2+1) resonance enhanced multiphoton ionization spectra of molecules exiting the guide show that beams of ND3 can be produced with rotational state populations corresponding to approximately Trot = 9–18 K, achieved through manipulation of the temperature of the buffer-gas cell (operated at 6 K or 17 K), the identity of the buffer gas (He or Ne), or the relative densities of the buffer gas and ND3. The translational temperature of the guided ND3 is found to be similar in a 6 K helium and 17 K neon buffer-gas cell (peak kinetic energies of 6.92(0.13) K and 5.90(0.01) K, respectively). The characterization of this cold-molecule source provides an opportunity for the first experimental investigations into the rotational dependence of reaction cross sections in low temperature collisions

  14. Laser cooling of dense atomic gases by collisional redistribution of radiation and spectroscopy of molecular dimers in a dense buffer gas environment

    CERN Document Server

    Saß, Anne; Christopoulos, Stavros; Knicker, Katharina; Moroshkin, Peter; Weitz, Martin

    2014-01-01

    We study laser cooling of atomic gases by collisional redistribution of fluorescence. In a high pressure buffer gas regime, frequent collisions perturb the energy levels of alkali atoms, which allows for the absorption of a far red detuned irradiated laser beam. Subsequent spontaneous decay occurs close to the unperturbed resonance frequency, leading to a cooling of the dense gas mixture by redistribution of fluorescence. Thermal deflection spectroscopy indicates large relative temperature changes down to and even below room temperature starting from an initial cell temperature near 700 K. We are currently performing a detailed analysis of the temperature distribution in the cell. As we expect this cooling technique to work also for molecular-noble gas mixtures, we also present initial spectroscopic experiments on alkali-dimers in a dense buffer gas surrounding.

  15. Surpassing the mass restriction of buffer gas cooling: Cooling of low mass ions by localized heavier atoms

    Science.gov (United States)

    Dutta, Sourav; Sawant, Rahul; Rangwala, S. A.

    2016-05-01

    Cooling of trapped ions has resulted in fascinating science including the realization of some of the most accurate atomic clocks. It has also found widespread application, for example, in mass spectrometry and cold chemistry. Among the different methods for cooling ions, cooling by elastic collisions with ultracold neutral atoms is arguably the most generic. However, in spite of its widespread application, there is confusion with regards the collisional heating/cooling of light ions by heavier neutral atoms. We address the question experimentally and demonstrate, for the first time, cooling of light ions by co-trapped heavy atoms. We show that trapped 39 K+ ions are cooled by localized ultracold neutral 85 Rb atoms. The atom-ion mass ratio (= 2.18) is well beyond any theoretical predictions so far. We further argue that cooling of ions by localized cold atoms is possible for any mass ratio. The result opens up the possibility of reaching the elusive s-wave collision regime in atom-ion collisions. S.D. is supported by DST-INSPIRE Faculty Fellowship, India.

  16. F-state quenching with CH4 for buffer-gas cooled 171Y b+ frequency standard

    International Nuclear Information System (INIS)

    We report that methane, CH4, can be used as an efficient F-state quenching gas for trapped ytterbium ions. The quenching rate coefficient is measured to be (2.8 ± 0.3) × 106 s−1 Torr−1. For applications that use microwave hyperfine transitions of the ground-state 171Y b ions, the CH4 induced frequency shift coefficient and the decoherence rate coefficient are measured as δν/ν = (−3.6 ± 0.1) × 10−6 Torr−1 and 1/T2 = (1.5 ± 0.2) × 105 s−1 Torr−1. In our buffer-gas cooled 171Y b+ microwave clock system, we find that only ≤10−8 Torr of CH4 is required under normal operating conditions to efficiently clear the F-state and maintain ≥85% of trapped ions in the ground state with insignificant pressure shift and collisional decoherence of the clock resonance

  17. Direct detection of Rydberg-Rydberg millimeter-wave transitions in a buffer gas cooled molecular beam

    Science.gov (United States)

    Zhou, Yan; Grimes, David D.; Barnum, Timothy J.; Patterson, David; Coy, Stephen L.; Klein, Ethan; Muenter, John S.; Field, Robert W.

    2015-11-01

    Millimeter-wave transitions between molecular Rydberg states (n ∼ 35) of barium monofluoride are directly detected via Free Induction Decay (FID). Two powerful technologies are used in combination: Chirped-Pulse millimeter-Wave (CPmmW) spectroscopy and a buffer gas cooled molecular beam photoablation source. Hundreds of Rydberg-Rydberg transitions are recorded in 1 h with >10:1 signal:noise ratio and ∼150 kHz resolution. This high resolution, high spectral velocity experiment promises new strategies for rapid measurements of structural and dynamical information, such as the electric structure (multipole moments and polarizabilities) of the molecular ion-core and the strengths and mechanisms of resonances between Rydberg electron and ion-core motions. Direct measurements of Rydberg-Rydberg transitions with kilo-Debye dipole moments support efficient and definitive spectral analysis techniques, such as the Stark demolition and polarization diagnostics, which enable semi-automatic assignments of core-nonpenetrating Rydberg states. In addition, extremely strong radiation-mediated collective effects (superradiance) in a dense Rydberg gas of barium atoms are observed.

  18. F-state quenching with CH{sub 4} for buffer-gas cooled {sup 171}Y b{sup +} frequency standard

    Energy Technology Data Exchange (ETDEWEB)

    Jau, Y.-Y., E-mail: yjau@sandia.gov; Hunker, J. D.; Schwindt, P. D. D. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)

    2015-11-15

    We report that methane, CH{sub 4}, can be used as an efficient F-state quenching gas for trapped ytterbium ions. The quenching rate coefficient is measured to be (2.8 ± 0.3) × 10{sup 6} s{sup −1} Torr{sup −1}. For applications that use microwave hyperfine transitions of the ground-state {sup 171}Y b ions, the CH{sub 4} induced frequency shift coefficient and the decoherence rate coefficient are measured as δν/ν = (−3.6 ± 0.1) × 10{sup −6} Torr{sup −1} and 1/T{sub 2} = (1.5 ± 0.2) × 10{sup 5} s{sup −1} Torr{sup −1}. In our buffer-gas cooled {sup 171}Y b{sup +} microwave clock system, we find that only ≤10{sup −8} Torr of CH{sub 4} is required under normal operating conditions to efficiently clear the F-state and maintain ≥85% of trapped ions in the ground state with insignificant pressure shift and collisional decoherence of the clock resonance.

  19. Gas-cooled reactors

    International Nuclear Information System (INIS)

    The present study is the second part of a general survey of Gas Cooled Reactors (GCRs). In this part, the course of development, overall performance and present development status of High Temperature Gas Cooled Reactors (HTCRs) and advances of HTGR systems are reviewed. (author)

  20. Kinetics of a single trapped ion in an ultracold buffer gas

    OpenAIRE

    Zipkes, Christoph; Ratschbacher, Lothar; Sias, Carlo; Köhl, Michael

    2010-01-01

    The immersion of a single ion confined by a radiofrequency trap in an ultracold atomic gas extends the concept of buffer gas cooling to a new temperature regime. The steady state energy distribution of the ion is determined by its kinetics in the radiofrequency field rather than the temperature of the buffer gas. Moreover, the finite size of the ultracold gas facilitates the observation of back-action of the ion onto the buffer gas. We numerically investigate the system's properties depending...

  1. Comparison experiments of neon and helium buffer gases cooling in trapped 199Hg+ ions linear trap

    International Nuclear Information System (INIS)

    The influences of different buffer gas, neon and helium, on 199Hg+ clock transition are compared in trapped 199Hg+linear trap. By the technique of time domain's Ramsey separated oscillatory fields, the buffer gas pressure frequency shifts of 199Hg+ clock transition are measured to be (df/dPNe)(1/f) = 1.8 × 10−8 Torr−1 for neon and (df/dPHe)(1/f) = 9.1×10−8 Torr−1 for helium. Meanwhile, the line-width of 199Hg+ clock transition spectrum with the buffer gas neon is narrower than that with helium at the same pressure. These experimental results show that neon is a more suitable buffer gas than helium in 199Hg+ ions microwave frequency standards because of the 199Hg+ clock transition is less sensitive to neon variations and the better cooling effect of neon. The optimum operating pressure for neon is found to be about 1.0×10−5 Torr in our linear ion trap system. (atomic and molecular physics)

  2. Gas-cooled nuclear reactor

    International Nuclear Information System (INIS)

    The invention aims at simplying gas-cooled nuclear reactors. For the cooling gas, the reactor is provided with a main circulation system comprising one or several energy conversion main groups such as gas turbines, and an auxiliary circulation system comprising at least one steam-generating boiler heated by the gas after its passage through the reactor core and adapted to feed a steam turbine with motive steam. The invention can be applied to reactors the main groups of which are direct-cycle gas turbines

  3. Gas-cooled nuclear reactor

    International Nuclear Information System (INIS)

    The gas temperature of a hot gas loop in gas-cooled nuclear reactor plants shall be able to be modified without influencing the gas temperature of the other loops. If necessary, it should be possible to stop the loop. This is possible by means of a mixer which is places below the heat absorbing component in the hot channel and which is connected to a cold gas line. (orig.)

  4. Kinetics of a single trapped ion in an ultracold buffer gas

    International Nuclear Information System (INIS)

    The immersion of a single ion confined by a radiofrequency (RF) trap in an ultracold atomic gas extends the concept of buffer gas cooling to a new temperature regime. The steady-state energy distribution of the ion is determined by its kinetics in the RF field rather than the temperature of the buffer gas. Moreover, the finite size of the ultracold gas facilitates the observation of back-action of the ion onto the buffer gas. We numerically investigate the system's properties depending on atom-ion mass ratio, trap geometry, differential cross-section and non-uniform neutral atom density distribution. Experimental results are well reproduced by our model considering only elastic collisions. We identify excess micromotion to set the typical scale for the ion energy statistics and explore the applicability of the mobility collision cross-section to the ultracold regime.

  5. Gas hydrate cool storage system

    Science.gov (United States)

    Ternes, M.P.; Kedl, R.J.

    1984-09-12

    The invention presented relates to the development of a process utilizing a gas hydrate as a cool storage medium for alleviating electric load demands during peak usage periods. Several objectives of the invention are mentioned concerning the formation of the gas hydrate as storage material in a thermal energy storage system within a heat pump cycle system. The gas hydrate was formed using a refrigerant in water and an example with R-12 refrigerant is included. (BCS)

  6. Gas cooled traction drive inverter

    Energy Technology Data Exchange (ETDEWEB)

    Chinthavali, Madhu Sudhan

    2016-04-19

    The present invention provides a modular circuit card configuration for distributing heat among a plurality of circuit cards. Each circuit card includes a housing adapted to dissipate heat in response to gas flow over the housing. In one aspect, a gas-cooled inverter includes a plurality of inverter circuit cards, and a plurality of circuit card housings, each of which encloses one of the plurality of inverter cards.

  7. Dynamics of a single trapped ion immersed in a buffer gas

    CERN Document Server

    Höltkemeier, Bastian; López-Carrera, Henry; Weidemüller, Matthias

    2016-01-01

    We provide a comprehensive theoretical framework for describing the dynamics of a single trapped ion interacting with a neutral buffer gas, thus extending our previous studies on buffer-gas cooling of ions beyond the critical mass ratio [B. H\\"oltkemeier et al., Phys. Rev. Lett. 116, 233003 (2016)]. By transforming the collisional processes into a frame, where the ion's micromotion is assigned to the buffer gas atoms, our model allows one to investigate the influence of non-homogeneous buffer gas configurations as well as higher multipole orders of the radio-frequency trap in great detail. Depending on the neutral-to-ion mass ratio, three regimes of sympathetic cooling are identified which are characterized by the form of the ion's energy distribution in equilibrium. We provide analytic expressions and numerical simulations of the ion's energy distribution, spatial profile and cooling rates for these different regimes. Based on these findings, a method for actively decreasing the ion's energy by reducing the ...

  8. Optimization of buffer gas pressure for Rb atomic magnetometer

    Science.gov (United States)

    Chen, Chang; Liu, Xiaohu; Qu, Tianliang; Yang, Kaiyong

    2015-08-01

    The optimization of buffer gas pressure is very important to improve the performance of the rubidium (Rb) atomic magnetometer. In this paper we briefly introduce the basic principle and the experimental method of the rubidium magnetometer based on Faraday rotation effect, and describe the factors affecting the magnetometer sensitivity, then analyze and summarize the mechanism of the influence of spin-exchange, spin-destruction collisions, radiation trapping and the spin diffusion on spin relaxation of Rb atoms. Based on this, the relationship between the rubidium magnetometer sensitivity, the spin relaxation rate and the gas chamber conditions (buffer gas pressure, the bubble radius, measuring temperature) is established. Doing calculations by the simulation software, how the magnetometer sensitivity and the relaxation rate vary with the gas chamber conditions can be seen; finally, the optimal values of the buffer gas pressure under certain gas chamber conditions are obtained. The work is significant for the engineering development of rubidium magnetometer.

  9. Thermometry of Guided Molecular Beams from a Cryogenic Buffer-Gas Cell

    CERN Document Server

    Wu, X; Zeppenfeld, M; Chervenkov, S; Rempe, G

    2016-01-01

    We present a comprehensive characterization of cold molecular beams from a cryogenic buffer-gas cell, providing an insight into the physics of buffer-gas cooling. Cold molecular beams are extracted from a cryogenic cell by electrostatic guiding, which is also used to measure their velocity distribution. Molecules' rotational-state distribution is probed via radio-frequency resonant depletion spectroscopy. With the help of complete trajectory simulations, yielding the guiding efficiency for all of the thermally populated states, we are able to determine both the rotational and the translational temperature of the molecules at the output of the buffer-gas cell. This thermometry method is demonstrated for various regimes of buffer-gas cooling and beam formation as well as for molecular species of different sizes, $\\rm{CH_3F}$ and $\\rm{CF_3CCH}$. Comparison between the rotational and translational temperatures provides evidence of faster rotational thermalization for the $\\rm{CH_3F-He}$ system in the limit of low...

  10. Buffer-gas effects on dark resonances: Theory and experiment

    Science.gov (United States)

    Erhard, Michael; Helm, Hanspeter

    2001-04-01

    Dark resonances with widths below 30 Hz have been observed in a rubidium cell filled with neon as buffer gas at room temperature. We compare an approximate analytic solution of a Λ system to our data and show that under our experimental conditions the presence of the buffer gas reduces the power broadening of the dark resonances by two orders of magnitude. We also present numerical calculations that take into account the thermal motion and velocity-changing collisions with the buffer-gas atoms. The resulting dark-resonance features exhibit strong Dicke-type narrowing effects and thereby explain the elimination of Doppler shifts and Doppler broadening, leading to observation of a single ultranarrow dark line.

  11. Impingement jet cooling in gas turbines

    CERN Document Server

    Amano, R S

    2014-01-01

    Due to the requirement for enhanced cooling technologies on modern gas turbine engines, advanced research and development has had to take place in field of thermal engineering. Impingement jet cooling is one of the most effective in terms of cooling, manufacturability and cost. This is the first to book to focus on impingement cooling alone.

  12. Rotational relaxation of fluoromethane molecules in low-temperature collisions with buffer-gas helium

    Science.gov (United States)

    Li, Xingjia; Xu, Liang; Yin, Yanning; Xu, Supeng; Xia, Yong; Yin, Jianping

    2016-06-01

    We propose a method to study the rotational relaxation of polar molecules [here taking fluoromethane (CH3F ) as an example] in collisions with 3.5 K buffer-gas helium (He) atoms by using an electrostatic guiding technique. The dependence of the guiding signal of CH3F on the injected He flux and the dependence of the guiding efficiency of CH3F on its rotational temperature are investigated both theoretically and experimentally. By comparing the experimental and simulated results, we find that the translational and rotational temperatures of the buffer-gas cooled CH3F molecules can reach to about 5.48 and 0.60 K, respectively, and the ratio between the translational and average rotational collisional cross sections of CH3F -He is γ =σt/σr=36.49 ±6.15 . In addition, the slowing, cooling, and boosting effects of the molecular beam with different injected He fluxes are also observed and their forming conditions are investigated in some detail. Our study shows that our proposed method can not only be used to measure the translational and rotational temperatures of the buffer-gas cooled molecules, but also to measure the ratio of the translational collisional cross section to the average rotational collisional cross section, and even to measure the average rotational collisional cross section when the translational collisional cross section is measured by fitting the lifetime of molecule signal to get a numerical solution from the diffusion equation of buffer-gas He atoms in the cell.

  13. Natural gas cooling: Part of the solution

    International Nuclear Information System (INIS)

    This paper reviews and compares the efficiencies and performance of a number of gas cooling systems with a comparable electric cooling system. The results show that gas cooling systems compare favorably with the electric equivalents, offering a new dimension to air conditioning and refrigeration systems. The paper goes on to compare the air quality benefits of natural gas to coal or oil-burning fuel systems which are used to generate the electricity for the electric cooling systems. Finally, the paper discusses the regulatory bias that the author feels exists towards the use of natural gas and the need for modification in the existing regulations to provide a 'level-playing field' for the gas cooling industry

  14. Non-Sticking of Helium Buffer Gas to Hydrocarbons

    CERN Document Server

    Croft, James F E

    2014-01-01

    Lifetimes of complexes formed during helium-hydrocarbon collisions at low temperature are estimated for symmetric top hydrocarbons. The lifetimes are obtained using a density-of-states approach. In general the lifetimes are less than 10-100 ns, and are found to decrease with increasing hydrocarbon size. This suggests that clustering will not limit precision spectroscopy in helium buffer gas experiments. Lifetimes are computed for noble-gas benzene collisions and are found to be in reasonable agreement with lifetimes obtained from classical trajectories as reported by Cui {\\it et al}.

  15. Gas-cooled reactors and their applications

    International Nuclear Information System (INIS)

    The purpose of the meeting was to review and discuss the current status and recent progress made in the technology and design of gas-cooled reactors and their application for electricity generation, process steam and process heat production. The meeting was attended by more than 200 participants from 25 countries and International Organizations presenting 34 papers. The technical part of the meeting was subdivided into 7 sessions: A. Overview of the Status of Gas-Cooled Reactors and Their Prospects (2 papers); B. Experience with Gas-Cooled Reactors (5 papers); C. Description of Current GCR Plant Designs (10 papers); D. Safety Aspects (4 papers); E. Gas-Cooled Reactor Applications (3 papers); F. Gas-Cooled Reactor Technology (6 papers); G. User's Perspectives on Gas-Cooled Reactors (4 papers). At the end of the meeting a round table discussion was organized in order to summarize the meeting and to make recommendations for future activities. A separate abstract was prepared for each of the 34 presentations of this meeting. Refs, figs and tabs

  16. Cooling and Collisions of Large Gas Phase Molecules

    OpenAIRE

    Patterson, David; Tsikata, Edem; Doyle, John M.

    2010-01-01

    Cold and dense samples of naphthalene \\((C_{10}H_8)\\) are produced using buffer gas cooling in combination with rapid, high flow molecule injection. The observed naphthalene density is \\(n \\approx 10^{11} cm_{−3}\\) over a volume of a few \\(cm^3\\) at a temperature of 6 K. We observe naphthalene–naphthalene collisions through two-body loss of naphthalene with a loss cross section of \\(\\sigma_{\\Lambda-\\Lambda} = 1.4 × 10^{-14} cm^2\\). Analysis is presented that indicates that this combination of...

  17. Beam cooling using a gas-filled RFQ ion guide

    CERN Document Server

    Henry, S; De Saint-Simon, M; Jacotin, M; Képinski, J F; Lunney, M D

    1999-01-01

    A radiofrequency quadrupole mass filter is being developed for use as a high-transmission beam cooler by operating it in buffer gas at high pressure. Such a device will increase the sensitivity of on-line experiments that make use of weakly produced radioactive ion beams. We present simulations and some preliminary measurements for a device designed to cool the beam for the MISTRAL RF mass spectrometer on- line at ISOLDE. The work is carried out partly within the frame of the European Community research network: EXOTRAPS. (9 refs).

  18. The extraction of 229Th3+ from a buffer-gas stopping cell

    Science.gov (United States)

    Wense, L. v. d.; Seiferle, B.; Laatiaoui, M.; Thirolf, P. G.

    2016-06-01

    In the whole landscape of atomic nuclei, 229Th is currently the only known nucleus which could allow for the development of a nuclear-based frequency standard, as it possesses an isomeric state of just 7.6 eV energy above the ground state. The 3+ charge state is of special importance in this context, as Th3+ allows for a simple laser-cooling scheme. Here we emphasize the direct extraction of triply-charged 229Th from a buffer-gas stopping cell. This finding will not only simplify any future approach of 229Th ion cooling, but is also used for thorium-beam purification and in this way provides a powerful tool for the direct identification of the 229Th isomer to ground state nuclear transition.

  19. High temperature gas-cooled reactor technology

    International Nuclear Information System (INIS)

    The high temperature gas-cooled reactor (HTGR) with a direct cycle helium system has drawn attention as the next generation nuclear power plant that is closest to commercialization. Fuji Electric participated in the design, manufacture and construction of JAPCO's Tokai-1 plant, a 'Colder Hall' type reactor, which was the first commercial nuclear power plant in Japan, and JAERI's high temperature engineering test reactor (HTTR), which was the first high temperature gas-cooled reactor in Japan. Fuji Electric, a pioneer of gas-cooled reactors, worked on the design, construction and development of these reactors. This paper provides brief descriptions of the air-cooled spent fuel storage system of the HTTR, material test facilities for the HTTR, and the development of an inherently safe and highly efficient commercial HTGR power plant as examples of Fuji Electric's recent activities in the HTGR field. (author)

  20. IAEA high temperature gas cooled reactor activities

    International Nuclear Information System (INIS)

    IAEA activities on high temperature gas cooled reactors are conducted with the review and support of Member States, primarily through the International Working Group on Gas Cooled Reactors (IWGGCR). This paper summarises the results of the IAEA gas cooled reactor project activities in recent years along with ongoing current activities through a review of Co-ordinated Research Projects (CRPs), meetings and other international efforts. A series of three recently completed CRPs have addressed the key areas of reactor physics for LEU fuel, retention of fission products, and removal of post shutdown decay heat through passive heat transport mechanisms. These activities along with other completed and ongoing supporting CRPs and meetings are summarised with reference to detailed documentation of the results. (author)

  1. French activities on gas cooled reactors

    International Nuclear Information System (INIS)

    The gas cooled reactor programme in France originally consisted of eight Natural Uranium Graphite Gas Cooled Reactors (UNGG). These eight units, which are now permanently shutdown, represented a combined net electrical power of 2,375 MW and a total operational history of 163 years. Studies related to these reactors concern monitoring and dismantling of decommissioned facilities, including the development of methods for dismantling. France has been monitoring the development of HTRs throughout the world since 1979, when it halted its own HTR R and D programme. France actively participates in three CRPs set up by the IAEA. (author). 1 tab

  2. Magnetization Cooling of an Electron Gas

    CERN Document Server

    Tsintsadze, Nodar L

    2012-01-01

    We propose an adiabatic magnetization process for cooling the Fermi electron gas to ultra-low temperatures as an alternative to the known adiabatic demagnetization mechanism. We show via a new adiabatic equation that at the constant density the increase of the magnetic field leads to the temperature decrease as $T\\sim 1/H^2$.

  3. Advanced gas-cooled reactors (AGR)

    International Nuclear Information System (INIS)

    The paper describes the advanced gas-cooled reactor system, Hunterston ''B'' power station, which is a development of the earlier natural uranium Magnox type reactor. Data of construction, capital cost, operating performance, reactor safety and also the list of future developments are given

  4. Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Aines, Roger D

    2015-03-31

    A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

  5. Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Aines, Roger D.

    2013-03-12

    A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

  6. Neutron electric dipole moment measurement with a buffer gas comagnetometer

    International Nuclear Information System (INIS)

    A neutron EDM measurement with a comagnetometer is discussed. For magnetometry, polarized xenon atoms are injected into a cylindrical cell where a cylindrically symmetric magnetic field and an electric field are applied for the EDM measurement. The geometric phase effect (GPE), which originates from particle motion in a magnetic field gradient, is analyzed in terms of the Dyson series. The motion of the xenon atom is largely suppressed because of a small mean free path. The field gradient is controlled by means of NMR measurements, where the false effect of Earth's rotation is removed. As a result, the GPE is reduced below 10−28e cm. -- Highlights: ► A method of high precision neutron EDM measurement is described. ► Geometric phase effects are discussed in terms of Dyson series. ► A magnetic field drift is compensated by means of a buffer gas magnetometer. ► Geometric phase effects are greatly suppressed. ► The systematic error is reduced by two orders of magnitude compared with before.

  7. Neutronic of heterogenous gas cooled reactors

    International Nuclear Information System (INIS)

    At present, one of the main technical features of the advanced gas cooled reactor under development is its fuel element concept, which implies a neutronic homogeneous design, thus requiring higher enrichment compared with present commercial nuclear power plants.In this work a neutronic heterogeneous gas cooled reactor design is analyzed by studying the neutronic design of the Advanced Gas cooled Reactor (AGR), a low enrichment, gas cooled and graphite moderated nuclear power plant.A search of merit figures (some neutronic parameter, characteristic dimension, or a mixture of both) which are important and have been optimized during the reactor design stage is been done, to aim to comprise how a gas heterogeneous reactor is been design, given that semi-infinity arrangement criteria of rods in LWRs and clusters in HWRs can t be applied for a solid moderator and a gas refrigerator.The WIMS code for neutronic cell calculations is been utilized to model the AGR fuel cell and to calculate neutronic parameters such as the multiplication factor and the pick factor, as function of the fuel burnup.Also calculation is been done for various nucleus characteristic dimensions values (fuel pin radius, fuel channel pitch) and neutronic parameters (such as fuel enrichment), around the design established parameters values.A fuel cycle cost analysis is carried out according to the reactor in study, and the enrichment effect over it is been studied.Finally, a thermal stability analysis is been done, in subcritical condition and at power level, to study this reactor characteristic reactivity coefficients.Present results shows (considering the approximation used) a first set of neutronic design figures of merit consistent with the AGR design.

  8. Buffer gas-induced resonance vibrational polarizability in the SF6-rare gas mixtures

    Science.gov (United States)

    Bulanin, Michael O.; Burtsev, Andrey P.; Kerl, Klaus; Kisliakov, Ivan M.

    2001-04-01

    Mixed second refractivity virial coefficients BRab(ω) have been evaluated from the analysis of the pressure broadened ν3≈930 cm-1 34SF6 IR absorption band profile in mixtures with Ne, Ar, Kr, and Xe buffer gases at relative densities up to 150 Amagat. The values of the BRab(ω) in the resonance region are found to be orders of magnitude greater compared to those observed for the neat gases in the spectral regions far from resonance. The experimental results are compared with the predictions of the dynamic DID model for the buffer gas-induced vibrational pair polarizability. The DID model reproduces surprisingly well the frequency variation of BRab in the range of the band wings for the heavier buffer gases, but significantly deviates from experiment for the SF6-Ne mixture.

  9. Optically pumped alkali laser and amplifier using helium-3 buffer gas

    Science.gov (United States)

    Beach, Raymond J.; Page, Ralph; Soules, Thomas; Stappaerts, Eddy; Wu, Sheldon Shao Quan

    2010-09-28

    In one embodiment, a laser oscillator is provided comprising an optical cavity, the optical cavity including a gain medium including an alkali vapor and a buffer gas, the buffer gas including .sup.3He gas, wherein if .sup.4He gas is also present in the buffer gas, the ratio of the concentration of the .sup.3He gas to the .sup.4He gas is greater than 1.37.times.10.sup.-6. Additionally, an optical excitation source is provided. Furthermore, the laser oscillator is capable of outputting radiation at a first frequency. In another embodiment, an apparatus is provided comprising a gain medium including an alkali vapor and a buffer gas including .sup.3He gas, wherein if .sup.4He gas is also present in the buffer gas, the ratio of the concentration of the .sup.3He gas to the .sup.4He gas is greater than 1.37.times.10.sup.-6. Other embodiments are also disclosed.

  10. Physics of gas-cooled reactors

    International Nuclear Information System (INIS)

    This paper deals with technical aspects of the gas-cooled reactors safety and design. It content five main parts: the new safety requirements for innovative reactors; the concept of a non-meltable nuclear reactor; the new concepts of decay heat removal from the reactor system; the behaviour of reactor system in case of extreme reactivity accidents; technical innovations in the reactor technology and necessary developments and proof tests. (A.L.B.)

  11. Commercial gas cooling: An investment opportunity

    Energy Technology Data Exchange (ETDEWEB)

    Nowakowski, G.A.; Cornel, T.L.

    1998-12-01

    The use of natural gas cooling equipment such as engine-driven chillers for air conditioning commercial buildings is known to provide operating cost savings over conventional electric chillers in many regions of the country. To be an economically viable alternative, business managers normally require that the actual savings from using gas cooling must be sufficient to pay back the higher first cost premium of gas chillers in a time period usually not exceeding three years. Simple payback analysis alone does not provide the financial information necessary to make optimal long term investment decisions for central cooling plant improvements. To provide a complete picture of alternative investments, simple payback results can be effectively used in conjunction with other financial criteria such as return on investment, internal rate of return, and net present value. When evaluated in these terms, projects with even four to five year payback often exceed industry financial returns on investment and internal rate of return. This article examines four case studies to demonstrate that this often does occur.

  12. Light Confinement by a Cylindric Metallic Waveguide in Dense Buffer Gas Environment

    CERN Document Server

    Vogl, Ulrich; Vewinger, Frank; Weitz, Martin; Solovev, Alexander; Mei, Yongfeng; Schmidt, Oliver

    2010-01-01

    We report on the implementation of metallic microtubes in a system of rubidium vapour at 230\\,bar of argon buffer gas. The high buffer gas pressure leads to a widely pressure broadened linewidth of several nanometers, interpolating between the sharp atomic physics spectra and the band structure of solid state systems. Tube-like metallic waveguide structures have been inserted in the high pressure buffer gas system, allowing for an enhancement of the atom-light interaction over an optical guiding length in the tube of up to 1\\,mm. The system holds promise for nonlinear optics experiments and the study of atom-light polariton condensation.

  13. Cooling of Gas Turbines. 2; Effectiveness of Rim Cooling of Blades

    Science.gov (United States)

    Wolfenstein, Lincoln; Meyer, Gene L.; McCarthy, John S.

    1945-01-01

    An analysis of rim cooling, which cools the blade by condition alone, was conducted. Gas temperatures ranged from 1300 degrees to 1900 degrees F and rim temperatures from 0 degrees to 1000 degrees F below gas temperatures. Results show that gas temperature increases up to 200 degrees F are permissible provided that the blades are cooled by 400 degrees to 500 degrees F below the gas temperature. Relatively small amounts of blade cooling, at constant gas temperature, give large increases in blade life. Dependence of rim cooling on heat-transfer coefficient, blade dimensions, and thermal conductivity is determined by a single parameter.

  14. Cooling and Heating Functions of Photoionized Gas

    CERN Document Server

    Gnedin, Nickolay Y

    2012-01-01

    Cooling functions of cosmic gas are a crucial ingredient for any study of gas dynamics and thermodynamics in the interstellar and intergalactic medium. As such, they have been studied extensively in the past under the assumption of collisional ionization equilibrium. However, for a wide range of applications, the local radiation field introduces a non-negligible, often dominant, modification to the cooling and heating functions. In the most general case, these modifications cannot be described in simple terms, and would require a detailed calculation with a large set of chemical species using a radiative transfer code (the well-known code Cloudy, for example). We show, however, that for a sufficiently general variation in the spectral shape and intensity of the incident radiation field, the cooling and heating functions can be \\emph{approximated} as depending only on (1) the photo-dissociation rate of molecular hydrogen, (2) the hydrogen photo-ionization rate, and (3) the photo-ionization rate of OVIII; more ...

  15. Design codes for gas cooled reactor components

    International Nuclear Information System (INIS)

    High-temperature gas-cooled reactor (HTGR) plants have been under development for about 30 years and experimental and prototype plants have been operated. The main line of development has been electricity generation based on the steam cycle. In addition the potential for high primary coolant temperature has resulted in research and development programmes for advanced applications including the direct cycle gas turbine and process heat applications. In order to compare results of the design techniques of various countries for high temperature reactor components, the IAEA established a Co-ordinated Research Programme (CRP) on Design Codes for Gas-Cooled Reactor Components. The Federal Republic of Germany, Japan, Switzerland and the USSR participated in this Co-ordinated Research Programme. Within the frame of this CRP a benchmark problem was established for the design of the hot steam header of the steam generator of an HTGR for electricity generation. This report presents the results of that effort. The publication also contains 5 reports presented by the participants. A separate abstract was prepared for each of these reports. Refs, figs and tabs

  16. CEA programme on gas cooled reactors

    International Nuclear Information System (INIS)

    Future nuclear energy systems studies conducted by the CEA aim at investigating and developing promising technologies for future reactors, fuels and fuel cycles, for nuclear power to play a major part in sustainable energy policies. Reactors and fuel cycles are considered as integral parts of a nuclear system to be optimised as a whole. Major goals assigned to future nuclear energy systems are the following: reinforced economic competitiveness with other electricity generation means, with a special emphasis on reducing the investment cost; enhanced reliability and safety, through an improved management of reactor operation in normal and abnormal plant conditions; minimum production of long lived radioactive waste; resource saving through an effective and flexible use of the available resources of fissile and fertile materials; enhanced resistance to proliferation risks. The three latter goals are essential for the sustainability of nuclear energy in the long term. Additional considerations such as the potentialities for other applications than electricity generation (co-generation, production of hydrogen, sea water desalination) take on an increasing importance. Sustainability goals call for fast neutron spectra (to transmute nuclear waste and to breed fertile fuel) and for recycling actinides from the spent fuel (plutonium and minor actinides). New applications and economic competitiveness call for high temperature technologies (850 deg C), that afford high conversion efficiencies and hence less radioactive waste production and discharged heat. These orientations call for breakthroughs beyond light water reactors. Therefore, as a result of a screening review of candidate technologies, the CEA has selected an innovative concept of high temperature gas cooled reactor with a fast neutron spectrum, robust refractory fuel, direct conversion with a gas turbine, and integrated on-site fuel cycle as a promising system for a sustainable energy development. This objective

  17. Influence of electrode, buffer gas and control gear on metal halide lamp performance

    International Nuclear Information System (INIS)

    In this paper the influence of electrode composition, buffer gas fill pressure and control gear on the performance of metal halide lamps is investigated. It is shown that pure tungsten electrodes improve lumen maintenance and reduce voltage rise over lamp life. An optimum buffer gas fill pressure condition is discovered which allows for reduced electrode erosion during lamp starting as well as under normal operating conditions. Use of electronic control gear is shown to improve the performance of metal halide lamps

  18. Gas-cooled fast breeder reactor

    International Nuclear Information System (INIS)

    Almost all the R D works of gas-cooled fast breeder reactor in the world were terminated at the end of the year 1980. In order to show that the R D termination was not due to technical difficulties of the reactor itself, the present paper describes the reactor plant concept, reactor performances, safety, economics and fuel cycle characteristics of the reactor, and also describes the reactor technologies developed so far, technological problems remained to be solved and planned development schedules of the reactor. (author)

  19. Cool Gas in High Redshift Galaxies

    CERN Document Server

    Carilli, Chris

    2013-01-01

    Over the last decade, observations of the cool interstellar medium in distant galaxies via molecular and atomic fine structure line emission has gone from a curious look into a few extreme, rare objects, to a mainstream tool to study galaxy formation, out to the highest redshifts. Molecular gas has now been observed in close to 200 galaxies at z>1, including numerous AGN host-galaxies out to z~7, highly starforming sub-millimeter galaxies (median redshift z~2.5), and increasing samples of 'main-sequence' star forming galaxies at z~1.5-2.5. Studies have moved well beyond simple detections, to dynamical imaging at kpc-scale resolution, and multi-line, multi-species studies that determine the physical conditions in the interstellar medium. Observations of the cool gas are the required complement to studies of the stellar density and star formation history of the Universe, as they reveal the phase of the interstellar medium that immediately precedes star formation. Current observations suggest that the order of m...

  20. Mathematical modeling of gas turbine cooled elements

    Energy Technology Data Exchange (ETDEWEB)

    Pashayev, A.; Askerov, D.; Sadiqov, R.; Samedov, A. [Academy of Aviation, Baku (Azerbaijan). Dept. of Mathematical Modeling and Design of Gas Turbine Engines

    2007-07-01

    The profile section of a gas turbine blade with convective cooling was modelled. Converging quadrature processes were used to determine the stationary and quasi-stationary temperature field of the profile part of the blade. Profiles were visualized using the least squares method along with automatic conjecture, device spline, smooth replenishment, and neural nets. Heat exchange boundary conditions were characterized using the finite difference method; finite element analysis (FEA); the Monte Carlo method; and the boundary integral equations method (BIEM). Boundary conditions included the heat quantity assigned by convection of the cooler transmitted by heat conduction of the blade material to the surface of cooling channels. Errors were investigated using a quadratures method and Tikhonov regularization. A Kirchhoff permutation was used to linearize tasks. The developed equation was then transformed into a Laplace equation. The model was then compared with experimental investigations to validate heat and hydraulic characteristics, as well as the temperature field of the blade cross section. It was concluded that the model can be used to assess the reliability of gas turbine engine designs. 3 refs., 1 fig.

  1. Cooled gas turbine blade edge flow analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, Marcio Teixeira de [Instituto Tecnologico de Aeronautica, Divisao de Engenharia Mecanica Aeronautica ITA/IEM, Sao Jose dos Campos, SP (Brazil)], e-mail: marcio@ita.br

    2010-07-01

    The flow on the rotating blades of a turbine is unsteady due to the wake of the stator blade row upstream. This unsteadiness is a source of losses and complex flow structures on the rotor blade due to the variation on the turbulence levels and location of the boundary layer laminar to turbulent transition. Convective cooled blades often time have cooling air ejected at the trailing edge right at the blade wake. The present investigation presents an analysis of a canonical flow consistent with the flow topology found at the trailing edge of a gas turbine blade with coolant ejection. A hydrodynamic stability analysis is performed for the combined wake and jet velocity profiles given by a gaussian distribution representing the turbulent rms wake and a laminar jet superposed. The growth rate of any instability found on the flow is an indication of faster mixing, resulting in a reduction on the wake velocity defect and consequently on the complexity associated with it. The results show that increasing the Mach number or the three-dimensionality of the disturbances result in a reduction of the amplification rate. When the flow at the trailing edge is modified by a jet, the amplification rates are lower, but the range of unstable stream wise wavenumbers is larger. (author)

  2. Status of national gas cooled reactor programmes

    International Nuclear Information System (INIS)

    This report has been compiled as a central source of summary-level information on the present status of High Temperature Gas-Cooled Reactor (HTGR) programmes in the world and on future plans for the continued development and deployment of HTGRs. Most of the information concerns the programmes in the United States, Germany, Japan and the Soviet Union, countries that have had large programmes related to HTGR technology for several years. Summary-level information is also provided in the report on HTGR-related activities in several other countries who either have an increasing interest in the technology and/or who are performing some development efforts related to HTGR technology. The report contains a summary-level update on the MAGNOX and AGR programmes. This is the twelfth issue of the document, the first of which was issued in March, 1979. The report has been prepared in the IAEA Nuclear Power Technology Development Section. Figs and tabs

  3. Heavy water moderated gas-cooled reactors

    International Nuclear Information System (INIS)

    France has based its main effort for the production of nuclear energy on natural Uranium Graphite-moderated gas-cooled reactors, and has a long term programme for fast reactors, but this country is also engaged in the development of heavy water moderated gas-cooled reactors which appear to present the best middle term prospects. The economy of these reactors, as in the case of Graphite, arises from the use of natural or very slightly enriched Uranium; heavy water can take the best advantages of this fuel cycle and moreover offers considerable development potential because of better reactor performances. A prototype plant EL 4 (70 MW) is under construction and is described in detail in another paper. The present one deals with the programme devoted to the development of this reactor type in France. Reasons for selecting this reactor type are given in the first part: advantages and difficulties are underlined. After reviewing the main technological problems and the Research and Development carried out, results already obtained and points still to be confirmed are reported. The construction of EL 4 is an important step of this programme: it will be a significant demonstration of reactor performances and will afford many experimentation opportunities. Now the design of large power reactors is to be considered. Extension and improvements of the mechanical structures used for EL 4 are under study, as well as alternative concepts. The paper gives some data for a large reactor in the present state of technology, as a result from optimization studies. Technical improvements, especially in the field of materials could lead to even more interesting performances. Some prospects are mentioned for the long run. Investment costs and fuel cycles are discussed in the last part. (authors)

  4. Seismic behaviour of gas cooled reactor components

    International Nuclear Information System (INIS)

    On invitation of the French Government the Specialists' Meeting on the Seismic Behaviour of Gas-Cooled Reactor Components was held at Gif-sur-Yvette, 14-16 November 1989. This was the second Specialists' Meeting on the general subject of gas-cooled reactor seismic design. There were 27 participants from France, the Federal Republic of Germany, Israel, Japan, Spain, Switzerland, the United Kingdom, the Soviet Union, the United States, the CEC and IAEA took the opportunity to present and discuss a total of 16 papers reflecting the state of the art of gained experiences in the field of their seismic qualification approach, seismic analysis methods and of the capabilities of various facilities used to qualify components and verify analytical methods. Since the first meeting, the sophistication and expanded capabilities of both the seismic analytical methods and the test facilities are apparent. The two main methods for seismic analysis, the impedance method and the finite element method, have been computer-programmed in several countries with the capability of each of the codes dependent on the computer capability. The correlations between calculation and tests are dependent on input assumptions such as boundary conditions, soil parameters and various interactions between the soil, the buildings and the contained equipment. The ability to adjust these parameters and match experimental results with calculations was displayed in several of the papers. The expanded capability of some of the new test facilities was graphically displayed by the description of the SAMSON vibration test facility at Juelich, FRG, capable of dynamically testing specimens weighing up to 25 tonnes, and the TAMARIS facility at the CEA laboratories in Gif-sur-Yvette where the largest table is capable of testing specimens weighing up to 100 tonnes. The proceedings of this meeting contain all 16 presented papers. A separate abstract was prepared for each of these papers. Refs, figs and tabs

  5. Diffusion, thermalization and optical pumping of YbF molecules in a cold buffer gas cell

    CERN Document Server

    Skoff, S M; Sinclair, C D J; Hudson, J J; Segal, D M; Sauer, B E; Hinds, E A; Tarbutt, M R

    2010-01-01

    We produce YbF molecules with a density of 10^18 m^-3 using laser ablation inside a cryogenically-cooled cell filled with a helium buffer gas. Using absorption imaging and absorption spectroscopy we study the formation, diffusion, thermalization and optical pumping of the molecules. The absorption images show an initial rapid expansion of molecules away from the ablation target followed by a much slower diffusion to the cell walls. We study how the time constant for diffusion depends on the helium density and temperature, and obtain values for the YbF-He diffusion cross-section at two different temperatures. We measure the translational and rotational temperatures of the molecules as a function of time since formation, obtain the characteristic time constant for the molecules to thermalize with the cell walls, and elucidate the process responsible for limiting this thermalization rate. Finally, we make a detailed study of how the absorption of the probe laser saturates as its intensity increases, showing that...

  6. Status of and prospects for gas-cooled reactors

    International Nuclear Information System (INIS)

    The IAEA International Working Group on Gas-Cooled Reactors (IWGGCR) (see Annex I), which was established in 1978, recommended to the Agency that a report be prepared in order to provide an up-to-date summary of gas-cooled reactor technology. The present Technical Report is based mainly on submissions of Member Countries of the IWGGCR and consists of four main sections. Beside some general information about the gas-cooled reactor line, section 1 contains a description of the incentives for the development and deployment of gas-cooled reactors in various Agency Member States. These include both electricity generation and process steam and process heat production for various branches of industry. The historical development of gas-cooled reactors is reviewed in section 2. In this section information is provided on how, when and why gas-cooled reactors have been developed in various Agency Member States and, in addition, a detailed description of the different gas-cooled reactor lines is presented. Section 3 contains information about the technical status of gas-cooled reactors and their applications. Gas-cooled reactors that are under design or construction or in operation are listed and shortly described, together with an outlook for future reactor designs. In this section the various applications for gas-cooled reactors are described in detail. These include both electricity generation and process steam and process heat production. The last section (section 4) is entitled ''Special features of gas-cooled reactors'' and contains information about the technical performance, fuel utilization, safety characteristics and environmental impact, such as radiation exposure and heat rejection

  7. Absorption resonance and large negative delay in rubidium vapor with a buffer gas

    International Nuclear Information System (INIS)

    We observe a narrow, isolated, two-photon absorption resonance in 87Rb for large one-photon detuning in the presence of a buffer gas. In the absence of a buffer gas, a standard Λ configuration of two laser frequencies gives rise to electromagnetically induced transparency (EIT) for all values of one-photon detuning throughout the inhomogeneously (Doppler) broadened line. However, when a buffer gas is added and the one-photon detuning is comparable to or greater than the Doppler width, an absorption resonance appears instead of the usual EIT resonance. We also observe a large negative group delay (≅-300 μs for a Gaussian pulse that propagates through the media with respect to a reference pulse not affected by the media), corresponding to a superluminal group velocity vg=-c/(3.6x106)=-84 m/s

  8. Gas turbine heat transfer and cooling technology

    CERN Document Server

    Han, Je-Chin; Ekkad, Srinath

    2012-01-01

    FundamentalsNeed for Turbine Blade CoolingTurbine-Cooling TechnologyTurbine Heat Transfer and Cooling IssuesStructure of the BookReview Articles and Book Chapters on Turbine Cooling and Heat TransferNew Information from 2000 to 2010ReferencesTurbine Heat TransferIntroductionTurbine-Stage Heat TransferCascade Vane Heat-Transfer ExperimentsCascade Blade Heat TransferAirfoil Endwall Heat TransferTurbine Rotor Blade Tip Heat TransferLeading-Edge Region Heat TransferFlat-Surface Heat TransferNew Information from 2000 to 20102.10 ClosureReferencesTurbine Film CoolingIntroductionFilm Cooling on Rotat

  9. 30 CFR 7.102 - Exhaust gas cooling efficiency test.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Exhaust gas cooling efficiency test. 7.102 Section 7.102 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING....102 Exhaust gas cooling efficiency test. (a) Test procedures. (1) Follow the procedures specified...

  10. Impact of inlet air cooling on gas turbine performance

    OpenAIRE

    Szymon Jarzębowski; Ewa Pyzik; Andrzej Miller

    2012-01-01

    In this article different possibilities of gas turbine inlet air cooling were presented. The method of defining power gain caused by air cooling was discussed. The results of increasing power output level of several different turbines and one gas turbine in combine cycle in domestic ambient conditions were presented and discussed. Significant turbine power gains were received.

  11. Evaluating the income and employment impacts of gas cooling technologies

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, P.J. [Oak Ridge National Lab., TN (United States); Laitner, S.

    1995-03-01

    The purpose of this study is to estimate the potential employment and income benefits of the emerging market for gas cooling products. The emphasis here is on exports because that is the major opportunity for the U.S. heating, ventilating, and air-conditioning (HVAC) industry. But domestic markets are also important and considered here because without a significant domestic market, it is unlikely that the plant investments, jobs, and income associated with gas cooling exports would be retained within the United States. The prospects for significant gas cooling exports appear promising for a variety of reasons. There is an expanding need for cooling in the developing world, natural gas is widely available, electric infrastructures are over-stressed in many areas, and the cost of building new gas infrastructure is modest compared to the cost of new electric infrastructure. Global gas cooling competition is currently limited, with Japanese and U.S. companies, and their foreign business partners, the only product sources. U.S. manufacturers of HVAC products are well positioned to compete globally, and are already one of the faster growing goods-exporting sectors of the U.S. economy. Net HVAC exports grew by over 800 percent from 1987 to 1992 and currently exceed $2.6 billion annually (ARI 1994). Net gas cooling job and income creation are estimated using an economic input-output model to compare a reference case to a gas cooling scenario. The reference case reflects current policies, practices, and trends with respect to conventional electric cooling technologies. The gas cooling scenario examines the impact of accelerated use of natural gas cooling technologies here and abroad.

  12. Experimental Study of High-Z Gas Buffers in Gas-Filled ICF Engines

    Energy Technology Data Exchange (ETDEWEB)

    Rhodes, M A; Kane, J; Loosmore, G; DeMuth, J; Latkowski, J

    2010-12-03

    ICF power plants, such as the LIFE scheme at LLNL, may employ a high-Z, target-chamber gas-fill to moderate the first-wall heat-pulse due to x-rays and energetic ions released during target detonation. To reduce the uncertainties of cooling and beam/target propagation through such gas-filled chambers, we present a pulsed plasma source producing 2-5 eV plasma comprised of high-Z gases. We use a 5-kJ, 100-ns theta discharge for high peak plasma-heating-power, an electrode-less discharge for minimizing impurities, and unobstructed axial access for diagnostics and beam (and/or target) propagation studies. We will report on the plasma source requirements, design process, and the system design.

  13. Advanced gas cooled reactors - Designing for safety

    International Nuclear Information System (INIS)

    The Advanced Gas-Cooled Reactor Power Stations recently completed at Heysham in Lancashire, England, and Torness in East Lothian, Scotland represent the current stage of development of the commercial AGR. Each power station has two reactor turbo-generator units designed for a total station output of 2x660 MW(e) gross although powers in excess of this have been achieved and it is currently intended to uprate this as far as possible. The design of both stations has been based on the successful operating AGRs at Hinkley Point and Hunterston which have now been in-service for almost 15 years, although minor changes were made to meet new safety requirements and to make improvements suggested by operating experience. The construction of these new AGRs has been to programme and within budget. Full commercial load for the first reactor at Torness was achieved in August 1988 with the other three reactors following over the subsequent 15 months. This paper summarises the safety principles and guidelines for the design of the reactors and discusses how some of the main features of the safety case meet these safety requirements. The paper also summarises the design problems which arose during the construction period and explains how these problems were solved with the minimum delay to programme

  14. Radial molecular abundances and gas cooling in starless cores

    CERN Document Server

    Sipilä, O

    2012-01-01

    Aims: We aim to simulate radial profiles of molecular abundances and the gas temperature in cold and heavily shielded starless cores by combining chemical and radiative transfer models. Methods: A determination of the dust temperature in a modified Bonnor-Ebert sphere is used to calculate initial radial molecular abundance profiles. The abundances of selected cooling molecules corresponding to two different core ages are then extracted to determine the gas temperature at two time steps. The calculation is repeated in an iterative process yielding molecular abundances consistent with the gas temperature. Line emission profiles for selected substances are calculated using simulated abundance profiles. Results: The gas temperature is a function of time; the gas heats up as the core gets older because the cooling molecules are depleted onto grain surfaces. The contributions of the various cooling molecules to the total cooling power change with time. Radial chemical abundance profiles are non-trivial: different s...

  15. Cooling performance of helium-gas/water coolers in HENDEL

    International Nuclear Information System (INIS)

    The helium engineering demonstration loop (HENDEL) has four helium-gas/water coolers where the cooling water flows in the tubes and helium gas on the shell side. Their cooling performance was studied using the operational data from 1982 to 1991. The heat transfer of helium gas on the shell was obtained for segmental and step-up baffle type coolers. Also, the change with operation time was investigated. The cooling performance was lowered by the graphite powder released from the graphite components for several thousand hours and thereafter recovered because the graphite powder from the components was reduced and the powder in the cooler shell was blown off during the operation. (orig.)

  16. Exergy analysis of a gas-hydrate cool storage system

    International Nuclear Information System (INIS)

    Based on exergy analysis of charging and discharging processes in a gas-hydrate cool storage system, the formulas for exergy efficiency at the sensible heat transfer stage and the phase change stage corresponding to gas-hydrate charging and discharging processes are obtained. Furthermore, the overall exergy efficiency expressions of charging, discharging processes and the thermodynamic cycle of the gas-hydrate cool storage system are obtained. By using the above expressions, the effects of number of transfer units, the inlet temperatures of the cooling medium and the heating medium on exergy efficiencies of the gas-hydrate cool storage system are emphatically analyzed. The research results can be directly used to evaluate the performance of gas-hydrate cool storage systems and design more efficient energy systems by reducing the sources of inefficiency in gas-hydrate cool storage systems. - Highlights: • Formulas for exergy efficiency at four stages are obtained. • Exergy efficiency expressions of two processes and one cycle are obtained. • Three mainly influencing factors on exergy efficiencies are analyzed. • With increasing the inlet temperature of cooling medium, exergy efficiency increases. • With decreasing the inlet temperature of heating medium, exergy efficiency increases

  17. High temperature gas-cooled reactor: gas turbine application study

    International Nuclear Information System (INIS)

    The high-temperature capability of the High-Temperature Gas-Cooled Reactor (HTGR) is a distinguishing characteristic which has long been recognized as significant both within the US and within foreign nuclear energy programs. This high-temperature capability of the HTGR concept leads to increased efficiency in conventional applications and, in addition, makes possible a number of unique applications in both electrical generation and industrial process heat. In particular, coupling the HTGR nuclear heat source to the Brayton (gas turbine) Cycle offers significant potential benefits to operating utilities. This HTGR-GT Application Study documents the effort to evaluate the appropriateness of the HTGR-GT as an HTGR Lead Project. The scope of this effort included evaluation of the HTGR-GT technology, evaluation of potential HTGR-GT markets, assessment of the economics of commercial HTGR-GT plants, and evaluation of the program and expenditures necessary to establish HTGR-GT technology through the completion of the Lead Project

  18. High temperature gas-cooled reactor: gas turbine application study

    Energy Technology Data Exchange (ETDEWEB)

    1980-12-01

    The high-temperature capability of the High-Temperature Gas-Cooled Reactor (HTGR) is a distinguishing characteristic which has long been recognized as significant both within the US and within foreign nuclear energy programs. This high-temperature capability of the HTGR concept leads to increased efficiency in conventional applications and, in addition, makes possible a number of unique applications in both electrical generation and industrial process heat. In particular, coupling the HTGR nuclear heat source to the Brayton (gas turbine) Cycle offers significant potential benefits to operating utilities. This HTGR-GT Application Study documents the effort to evaluate the appropriateness of the HTGR-GT as an HTGR Lead Project. The scope of this effort included evaluation of the HTGR-GT technology, evaluation of potential HTGR-GT markets, assessment of the economics of commercial HTGR-GT plants, and evaluation of the program and expenditures necessary to establish HTGR-GT technology through the completion of the Lead Project.

  19. Coherent population trapping on 87Rb atoms in small-size absorption cells with buffer gas

    Science.gov (United States)

    Ermak, S. V.; Petrenko, M. V.; Semenov, V. V.

    2016-02-01

    Coherent population trapping (CPT) on 87Rb atoms in neon atmosphere has been studied in small-size glass absorption cells under conditions of pumping with narrow-band laser radiation at the D2 line of the main doublet. Parameters of the absorption signal have been measured in 3-mm-diameter cells at buffer gas (Ne) pressures varied within 200-400 Torr, cell temperatures within 65-120°C, and pumping radiation power densities within 30-400 μW/cm2. Optimum values of the buffer gas pressures, cell temperature, and pumping power are determined at which the short-term instability of the resonance line is at minimum. Orientational shifts of the CPT resonance signal in gas-filled cells and small-size cells with antirelaxation coating have been compared.

  20. Improvement of Cooling Technology through Atmosphere Gas Management

    Energy Technology Data Exchange (ETDEWEB)

    Renard, Michel; Dosogne, Edgaar; Crutzen, Jean Pierre; Raick, Jean Mare [DREVER INTERNATIONAL S.A., Liege (Belgium); Ji, Ma Jia; Jun, Lv; Zhi, Ma Bing [SHOUGANG Cold Rolling Mill Headquarter, Beijin (China)

    2009-12-15

    The production of advanced high strength steels requires the improvement of cooling technology. The use of high cooling rates allows relatively low levels of expensive alloying additions to ensure sufficient hardenability. In classical annealing and hot-dip galvanizing lines a mixing station is used to provide atmosphere gas containing 3-5% hydrogen and 97-95% nitrogen in the various sections of the furnace, including the rapid cooling section. Heat exchange enhancement in this cooling section can be insured by the increased hydrogen concentration. Driver international developed a patented improvement of cooling technology based on the following features: pure hydrogen gas is injected only in the rapid cooling section whereas the different sections of the furnace are supplied with pure nitrogen gas: the control of flows through atmosphere gas management allows to get high hydrogen concentration in cooling section and low hydrogen content in the other furnace zones. This cooling technology development insures higher cooling rates without additional expensive hydrogen gas consumption and without the use of complex sealing equipment between zones. In addition reduction in electrical energy consumption is obtained. This atmosphere control development can be combined with geometrical design improvements in order to get optimised cooling technology providing high cooling rates as well as reduced strip vibration amplitudes. Extensive validation of theoretical research has been conducted on industrial lines. New lines as well as existing lines, with limited modifications, can be equipped with this new development. Up to now this technology has successfully been implemented on 6 existing and 7 new lines in Europe and Asia.

  1. National Gas Cool Times, September/October 2000.

    Science.gov (United States)

    Natural Gas Cool Times, 2000

    2000-01-01

    Several articles are presented covering the development and use of gas/electric cooling solutions for public schools and colleges. Articles address financing issues; indoor air quality (IAQ) problems and solutions; and the analysis of heating, ventilation, and air conditioning systems. Three examples of how schools solved their cooling problems…

  2. Testing Of RSG-GAS Secondary Cooling Component

    International Nuclear Information System (INIS)

    The aim of this activity is to improve the mechanical testing technology knowledge of the research reactor cooling pipe material, through a series of testing for the components especially for the mechanical properties of austenitic steel pipe used in RSG-GAS secondary cooling pipe. Scopes of these testing activities are chemical composition analysis, tensile testing, and hardness testing

  3. Seismic stability of VGM type high temperature gas cooled reactors

    International Nuclear Information System (INIS)

    The main principles of the design provision of high temperature gas cooled VGM reactors seismic stability and the results of calculations, performed by linear-spectral method are presented. (author). 1 ref., 10 figs

  4. Gas-cooled Generation IV systems. VHTR and GFR

    International Nuclear Information System (INIS)

    In this presentation author deals with the development of nuclear reactor type of The Very High Temperature system (VHTR), the Gas-cooled fast reactor (GFR). Some construction parameters are presented.

  5. Integrated exhaust gas recirculation and charge cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ko-Jen

    2013-12-10

    An intake system for an internal combustion engine comprises an exhaust driven turbocharger configured to deliver compressed intake charge, comprising exhaust gas from the exhaust system and ambient air, through an intake charge conduit and to cylinders of the internal combustion engine. An intake charge cooler is in fluid communication with the intake charge conduit. A cooling system, independent of the cooling system for the internal combustion engine, is in fluid communication with the intake charge cooler through a cooling system conduit. A coolant pump delivers a low temperature cooling medium from the cooling system to and through the intake charge cooler for the transfer of heat from the compressed intake charge thereto. A low temperature cooler receives the heated cooling medium through the cooling system conduit for the transfer or heat therefrom.

  6. How to get cool in the heat: comparing analytic models of halo gas cooling with EAGLE

    CERN Document Server

    Stevens, Adam R H; Contreras, Sergio; Croton, Darren J; Padilla, Nelson D; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2016-01-01

    We use the hydrodynamic, cosmological EAGLE simulations to investigate how hot gas in haloes condenses to form and grow galaxies. We select haloes from the simulations that are actively cooling and study the temperature, distribution, and metallicity of their hot, cold, and transitioning `cooling' gas, placing these in context of semi-analytic models. Our selection criteria lead us to focus on Milky Way-like haloes. We find the hot-gas density profiles of the haloes form a progressively stronger core over time, the nature of which can be captured by a beta profile that has a simple dependence on redshift. In contrast, the hot gas that actually cools is broadly consistent with a singular isothermal sphere. We find that cooling gas carries a few times the specific angular momentum of the halo and is offset in spin direction from the rest of the hot gas. The gas loses ~60% of its specific angular momentum during the cooling process, generally remaining greater than that of the halo, and is better aligned with th...

  7. Fuel performance models for high-temperature gas-cooled reactor core design

    International Nuclear Information System (INIS)

    Mechanistic fuel performance models are used in high-temperature gas-cooled reactor core design and licensing to predict failure and fission product release. Fuel particles manufactured with defective or missing SiC, IPyC, or fuel dispersion in the buffer fail at a level of less than 5 x 10-4 fraction. These failed particles primarily release metallic fission products because the OPyC remains intact on 90% of the particles and retains gaseous isotopes. The predicted failure of particles using performance models appears to be conservative relative to operating reactor experience

  8. Neon as a Buffer Gas for a Mercury-Ion Clock

    Science.gov (United States)

    Prestage, John; Chung, Sang

    2008-01-01

    A developmental miniature mercury-ion clock has stability comparable to that of a hydrogen-maser clock. The ion-handling components are housed in a sealed vacuum tube, wherein a getter pump is used to maintain the partial vacuum, and the evacuated tube is backfilled with mercury vapor in a buffer gas. Neon was determined to be the best choice for the buffer gas: The pressure-induced frequency pulling by neon was found to be only about two-fifths of that of helium. Furthermore, because neon diffuses through solids much more slowly than does helium, the operational lifetime of a tube backfilled with neon could be considerably longer than that of a tube backfilled with helium.

  9. Observing random walks of atoms in buffer gas through resonant light absorption

    CERN Document Server

    Aoki, Kenichiro

    2016-01-01

    Using resonant light absorption, random walk motions of rubidium atoms in nitrogen buffer gas are observed directly. The transmitted light intensity through atomic vapor is measured and its spectrum is obtained, down to orders of magnitude below the shot noise level to detect fluctuations caused by atomic motions. To understand the measured spectra, the spectrum for atoms performing random walks in a gaussian light beam is computed and its analytical form is obtained. The spectrum has $1/f^2$ ($f$: frequency) behavior at higher frequencies, crossing over to a different, but well defined behavior at lower frequencies. The properties of this theoretical spectrum agree excellently with the measured spectrum. This understanding also enables us to obtain the diffusion constant, the photon cross section of atoms in buffer gas and the atomic number density, from a single spectral measurement. We further discuss other possible applications of our experimental method and analysis.

  10. Observing random walks of atoms in buffer gas through resonant light absorption

    Science.gov (United States)

    Aoki, Kenichiro; Mitsui, Takahisa

    2016-07-01

    Using resonant light absorption, random-walk motions of rubidium atoms in nitrogen buffer gas are observed directly. The transmitted light intensity through atomic vapor is measured, and its spectrum is obtained, down to orders of magnitude below the shot-noise level to detect fluctuations caused by atomic motions. To understand the measured spectra, the spectrum for atoms performing random walks in a Gaussian light beam is computed, and its analytical form is obtained. The spectrum has 1 /f2 (f is frequency) behavior at higher frequencies, crossing over to a different, but well-defined, behavior at lower frequencies. The properties of this theoretical spectrum agree excellently with the measured spectrum. This understanding also enables us to obtain the diffusion constant, the photon cross section of atoms in buffer gas, and the atomic number density from a single spectral measurement. We further discuss other possible applications of our experimental method and analysis.

  11. Characterizing passive coherent population trapping resonance in a cesium vapor cell filled with neon buffer gas

    International Nuclear Information System (INIS)

    We present a pair of phase-locked lasers with a 9.2-GHz frequency difference through the injection locking of a master laser to the RF-modulation sideband of a slave diode laser. Using this laser system, a coherent population trapping (CPT) signal with a typical linewidth of ∼ 182 Hz is obtained in a cesium vapor cell filled with 30 Torr (4 kPa) of neon as the buffer gas. We investigate the influence of the partial pressure of the neon buffer gas on the CPT linewidth, amplitude, and frequency shift. The results may offer some references for CPT atomic clocks and CPT atomic magnetometers. (atomic and molecular physics)

  12. The Computer Simulation Of RSG-GAS Secondary Cooling System

    International Nuclear Information System (INIS)

    The safety operation of RSG-GAS extremely depends on the reliability of the system and its components. Since the RSG-GAS operation age has an enough old, the cooling system components have been degrading. In this age condition, the operation plan that burdening the cooling system should be carefully evaluated before the plan is executed. The safety way to evaluate the heavy burden operation plan is utilize the computer simulation. In the current study, computer simulation of secondary cooling system of RSG-GAS has been carried out by the CATHENA (Canadian Algorithm for THErmalhydraulics Network Analysis) code. The result of this simulation is the performance of the secondary cooling system as the thermal-hydraulics characteristics of the system at the burdening operation plan

  13. Method for traveling-wave deceleration of buffer-gas beams of CH

    OpenAIRE

    Fabrikant, M. I.; Li, Tian; Fitch, N J; N. Farrow; Weinstein, Jonathan D.; Lewandowski, H. J.

    2013-01-01

    Cryogenic buffer-gas beams are a promising method for producing bright sources of cold molecular radicals for cold collision and chemical reaction experiments. In order to use these beams in studies of reactions with controlled collision energies, or in trapping experiments, one needs a method of controlling the forward velocity of the beam. A Stark decelerator can be an effective tool for controlling the mean speed of molecules produced by supersonic jets, but efficient deceleration of buffe...

  14. Level-crossing absorption with narrow spectral width in Rb vapor with buffer gas

    International Nuclear Information System (INIS)

    We present the transformation in the Hanle configuration of the transmission that results from coherent population trapping (CPT) into the level-crossing absorption (LCA) that results from the single-photon optical pumping in the 87Rb D1 line of a Rb vapor cell with a Ne buffer gas when the polarization of the laser field is changed from linear to circular. The LCA spectrum, with a narrow spectral width of 2.4 mG (1.7 kHz), was observed in the Fg→Fe≤Fg transition with the circularly polarized laser. This may be because the LCA is both related to the transverse magnetic field and the atom-laser interaction time resulting from diffusive atomic motion in the cell with the buffer gas. The CPT and LCA spectra were calculated numerically using the full density matrix equations for the relevant magnetic sublevels of the hyperfine levels, considering the residual magnetic fields perpendicular to laser propagation and the collision effects resulting from the buffer gas. There was good qualitative agreement between theoretical and experimental results.

  15. Coherent population trapping in small- and chip-scale 87Rb vapor cells with buffer gas

    Science.gov (United States)

    Ermak, S. V.; Semenov, V. V.; Petrenko, M. V.; Pyatyshev, E. N.

    2016-03-01

    The characteristics of coherent population trapping (CPT) signal were investigated in small-size glass vapor cells containing 87Rb and Ne buffer gas with narrow line-width laser pumping on D2 line. The parameters of CPT signals were measured using small-size vapor cells with Ne buffer gas pressure in the range of 200-400 Torr, cell temperature in the range of 65-120 ∘C and the values of laser pumping power of 30-400 μW/cm2. Optimal conditions, under which the minimal value of short-term instability of resonance line is achieved, were obtained in experiments. Orientation frequency shifts of CPT resonance using glass 87Rb vapor cells containing buffer gas and anti-relaxation coating were compared. CPT signals using vapor cells based on integrated technologies containing 87Rb in atmosphere of Ne were also investigated. The CPT signals with typical line widths of 2-3 kHz and signal-to-noise ratio of 1500 in 1 Hz bandwidth are observed, which allows one to provide relative frequency instability of 10-11 at 100 s.

  16. Dependence of the 85Rb coherent population trapping resonance characteristic on the pressure of N2 buffer gas

    International Nuclear Information System (INIS)

    In order to exploit its potential applications, we experimentally study the dependence of 85Rb-based coherent population trapping (CPT) resonance on N2 buffer gas with 6 vapor cells filled with natural rubidium and N2. The experiments are carried out at different pressures and temperatures, and the results reveal that higher cell temperature makes the resonance more sensitive to N2 pressure. Thus, it is important to choose a proper buffer gas pressure at a given cell temperature. This work provides valuable data for the application of 85Rb CPT resonance with a buffer gas of N2. (geophysics, astronomy, and astrophysics)

  17. Compatibility of gas turbine materials with steam cooling

    Energy Technology Data Exchange (ETDEWEB)

    Desai, V.; Tamboli, D.; Patel, Y. [Univ. of Central Florida, Orlando, FL (United States)

    1995-10-01

    Gas turbines had been traditionally used for peak load plants and remote locations as they offer advantage of low installation costs and quick start up time. Their use as a base load generator had not been feasible owing to their poor efficiency. However, with the advent of gas turbines based combined cycle plants (CCPs), continued advances in efficiency are being made. Coupled with ultra low NO{sub x} emissions, coal compatibility and higher unit output, gas turbines are now competing with conventional power plants for base load power generation. Currently, the turbines are designed with TIT of 2300{degrees}F and metal temperatures are maintained around 1700{degrees}F by using air cooling. New higher efficiency ATS turbines will have TIT as high as 2700{degrees}F. To withstand this high temperature improved materials, coatings, and advances in cooling system and design are warranted. Development of advanced materials with better capabilities specifically for land base applications are time consuming and may not be available by ATS time frame or may prove costly for the first generation ATS gas turbines. Therefore improvement in the cooling system of hot components, which can take place in a relatively shorter time frame, is important. One way to improve cooling efficiency is to use better cooling agent. Steam as an alternate cooling agent offers attractive advantages because of its higher specific heat (almost twice that of air) and lower viscosity.

  18. Energy saving in ceramic tile kilns: Cooling gas heat recovery

    International Nuclear Information System (INIS)

    A great quantity of thermal energy is consumed in ceramic tile manufacture, mainly in the firing stage. The most widely used facilities are roller kilns, fuelled by natural gas, in which more than 50% of the energy input is lost through the flue gas and cooling gas exhaust stacks. This paper presents a calculation methodology, based on certain kiln operating parameters, for quantifying the energy saving obtained in the kiln when part of the cooling gases are recovered in the firing chamber and are not exhausted into the atmosphere. Energy savings up to 17% have been estimated in the studied case. Comparison of the theoretical results with the experimental data confirmed the validity of the proposed methodology. The study also evidenced the need to improve combustion process control, owing to the importance of the combustion process in kiln safety and energy efficiency. - Highlights: •Some energy input (30–35%) in ceramic roller kilns is lost through the cooling gas stack. •Cooling air is directly recovered in the combustion chamber, providing oxygen. •This energy recovery from the cooling gas stack has been quantified. •It has been proven that the proposed methodology to estimate energy savings is valid

  19. Gas migration in KBS-3 buffer bentonite. Sensitivity of test parameters to experimental boundary conditions

    International Nuclear Information System (INIS)

    In the current Swedish repository design concept, hydrogen gas can be generated inside a waste canister by anaerobic corrosion of the ferrous metal liner. If the gas generation rate exceeds the diffusion rate of gas molecules in the buffer porewater, gas will accumulate in the void-space of a canister until its pressure becomes large enough for it to enter the bentonite as a discrete gaseous phase. Three long tenn gas injection tests have been performed on cylinders of pre-compacted MX80 bentonite. Two of these tests were undertaken using a custom-designed constant volume and radial flow (CVRF) apparatus. Gas was injected at a centrally located porous filter installed in the clay before hydration. Arrangements were made for gas to flow to three independently monitored sink-filter arrays mounted around the specimen. Axial and radial total stresses and internal porewater pressures were continuously monitored. Breakthrough and peak gas pressures were substantially larger than the sum of the swelling pressure and the external porewater. The third test was performed. using an apparatus which radially constrains the specimen during gas flow. Observed sensitivity of the breakthrough and peak gas pressures to the test boundary conditions suggests that gas entry must be accompanied by dilation of the bentonite fabric. In other words, there is a tendency for the volume of the specimen to increase during this process. The experimental evidence is consistent with the flow of gas along a relatively small number of crack-like pathways which propagate through the clay as gas pressure increases. Gas entry and breakthrough under constant volume boundary conditions causes a substantial increase in the total stress and the internal porewater pressure. It is possible to determine the point at which gas enters the clay by monitoring changes in these parameters. Localisation of gas flow within multiple pathways results, in nonuniform discharge rates at the sinks. When gas injection

  20. Design requirements, operation and maintenance of gas-cooled reactors

    International Nuclear Information System (INIS)

    At the invitation of the Government of the USA the Technical Committee Meeting on Design Requirements, Operation and Maintenance of Gas-Cooled Reactors, was held in San Diego on September 21-23, 1988, in tandem with the GCRA Conference. Both meetings attracted a large contingent of foreign participants. Approximately 100 delegates from 18 different countries participated in the Technical Committee meeting. The meeting was divided into three sessions: Gas-cooled reactor user requirement (8 papers); Gas-cooled reactor improvements to facilitate operation and maintenance (10 papers) and Safety, environmental impacts and waste disposal (5 papers). A separate abstract was prepared for each of these 23 papers. Refs, figs and tabs

  1. Cooling of gas turbines IX : cooling effects from use of ceramic coatings on water-cooled turbine blades

    Science.gov (United States)

    Brown, W Byron; Livingood, John N B

    1948-01-01

    The hottest part of a turbine blade is likely to be the trailing portion. When the blades are cooled and when water is used as the coolant, the cooling passages are placed as close as possible to the trailing edge in order to cool this portion. In some cases, however, the trailing portion of the blade is so narrow, for aerodynamic reasons, that water passages cannot be located very near the trailing edge. Because ceramic coatings offer the possibility of protection for the trailing part of such narrow blades, a theoretical study has been made of the cooling effect of a ceramic coating on: (1) the blade-metal temperature when the gas temperature is unchanged, and (2) the gas temperature when the metal temperature is unchanged. Comparison is also made between the changes in the blade or gas temperatures produced by ceramic coatings and the changes produced by moving the cooling passages nearer the trailing edge. This comparison was made to provide a standard for evaluating the gains obtainable with ceramic coatings as compared to those obtainable by constructing the turbine blade in such a manner that water passages could be located very near the trailing edge.

  2. Application of Hastelloy X in Gas-Cooled Reactor Systems

    DEFF Research Database (Denmark)

    Brinkman, C. R.; Rittenhouse, P. L.; Corwin, W.R.;

    1976-01-01

    Hastelloy X, an Ni--Cr--Fe--Mo alloy, may be an important structural alloy for components of gas-cooled reactor systems. Expected applications of this alloy in the High-Temperature Gas-Cooled Reactor (HTGR) are discussed, and the development of interim mechanical properties and supporting data...... extensive amount of information has been generated on this material at Oak Ridge National Laboratory and elsewhere concerning behavior in air, which is reviewed. However, only limited data are available from tests conducted in helium. Comparisons of the fatigue and subcritical growth behavior in air between...... Hastelloy X and a number of other structural alloys are given....

  3. Pin-Type Gas Cooled Reactor for Nuclear Electric Propulsion

    Science.gov (United States)

    Wright, Steven A.; Lipinski, Ronald J.

    2003-01-01

    This paper describes a point design for a pin-type Gas-Cooled Reactor concept that uses a fuel pin design similar to the SP100 fuel pin. The Gas-Cooled Reactor is designed to operate at 100 kWe for 7 years plus have a reduced power mode of 20% power for a duration of 5 years. The power system uses a gas-cooled, UN-fueled, pin-type reactor to heat He/Xe gas that flows directly into a recuperated Brayton system to produce electricity. Heat is rejected to space via a thermal radiator that unfolds in space. The reactor contains approximately 154 kg of 93.15 % enriched UN in 313 fuel pins. The fuel is clad with rhenium-lined Nb-1Zr. The pressures vessel and ducting are cooled by the 900 K He/Xe gas inlet flow or by thermal radiation. This permits all pressure boundaries to be made of superalloy metals rather than refractory metals, which greatly reduces the cost and development schedule required by the project. The reactor contains sufficient rhenium (a neutron poison) to make the reactor subcritical under water immersion accidents without the use of internal shutdown rods. The mass of the reactor and reflectors is about 750 kg.

  4. Gas turbine modeling for NPP with helium cooled reactor

    International Nuclear Information System (INIS)

    The performance analyzes of closed helium cycle for NPPs with high-temperature gas-cooled reactors was carried out. Air-turbine units and helium-turbine units were compared. Helium turbine features were particularized in comparison with conventional air turbines. Simulation results of gas turbine setting with helium as a working medium were presented. Problems concerning high economic efficiency advance of helium turbines were discussed

  5. Gas cooled disk amplifier approach to solid state average power

    International Nuclear Information System (INIS)

    Disk amplifiers have been used on almost all solid state laser systems of high energy, and, in principle, one simply has to cool the device to operate it at average power. To achieve the desired waste heat removal, gas is flowed across the disk surface. The authors show the basic gas flow geometry. They computationally and experimentally characterize the flow and its optical implications over regimes which far exceed the envisioned operating requirements of a working amplifier

  6. Radial molecular abundances and gas cooling in starless cores

    OpenAIRE

    Sipilä, O.

    2012-01-01

    Aims: We aim to simulate radial profiles of molecular abundances and the gas temperature in cold and heavily shielded starless cores by combining chemical and radiative transfer models. Methods: A determination of the dust temperature in a modified Bonnor-Ebert sphere is used to calculate initial radial molecular abundance profiles. The abundances of selected cooling molecules corresponding to two different core ages are then extracted to determine the gas temperature at two time steps. The c...

  7. Fuel Development For Gas-Cooled Fast Reactors

    Energy Technology Data Exchange (ETDEWEB)

    M. K. Meyer

    2006-06-01

    The Generation IV Gas-cooled Fast Reactor (GFR) concept is proposed to combine the advantages of high-temperature gas-cooled reactors (such as efficient direct conversion with a gas turbine and the potential for application of high-temperature process heat), with the sustainability advantages that are possible with a fast-spectrum reactor. The latter include the ability to fission all transuranics and the potential for breeding. The GFR is part of a consistent set of gas-cooled reactors that includes a medium-term Pebble Bed Modular Reactor (PBMR)-like concept, or concepts based on the Gas Turbine Modular Helium Reactor (GT-MHR), and specialized concepts such as the Very High Temperature Reactor (VHTR), as well as actinide burning concepts [ ]. To achieve the necessary high power density and the ability to retain fission gas at high temperature, the primary fuel concept proposed for testing in the United States is a dispersion coated fuel particles in a ceramic matrix. Alternative fuel concepts considered in the U.S. and internationally include coated particle beds, ceramic clad fuel pins, and novel ceramic ‘honeycomb’ structures. Both mixed carbide and mixed nitride-based solid solutions are considered as fuel phases.

  8. International working group on gas-cooled reactors. Summary report

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-15

    The purpose of the meeting was to provide a forum for exchange of information on safety and licensing aspects for gas-cooled reactors in order to provide comprehensive review of the present status and of directions for future applications and development. Contributions were made concerning the operating experience of the Fort St. Vrain (FSV) HTGR Power Plant in the United States of America, the experimental power station Arbeitsgemeinschaft Versuchsreaktor (AVR) in the Federal Republic of Germany, and the CO/sub 2/-cooled reactors in the United Kingdom such as Hunterson B and Hinkley Point B. The experience gained at each of these reactors has proved the high safety potential of Gas-cooled Reactor Power Plants.

  9. Gas-cooled reactor safety and accident analysis

    International Nuclear Information System (INIS)

    The Specialists' Meeting on Gas-Cooled Reactor Safety and Accident Analysis was convened by the International Atomic Energy Agency in Oak Ridge on the invitation of the Department of Energy in Washington, USA. The meeting was hosted by the Oak Ridge National Laboratory. The purpose of the meeting was to provide an opportunity to compare and discuss results of safety and accident analysis of gas-cooled reactors under development, construction or in operation, to review their lay-out, design, and their operational performance, and to identify areas in which additional research and development are needed. The meeting emphasized the high safety margins of gas-cooled reactors and gave particular attention to the inherent safety features of small reactor units. The meeting was subdivided into four technical sessions: Safety and Related Experience with Operating Gas-Cooled Reactors (4 papers); Risk and Safety Analysis (11 papers); Accident Analysis (9 papers); Miscellaneous Related Topics (5 papers). A separate abstract was prepared for each of these papers

  10. High Temperature Gas-Cooled Test Reactor Options Status Report

    Energy Technology Data Exchange (ETDEWEB)

    Sterbentz, James William [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bayless, Paul David [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-08-01

    Preliminary scoping calculations are being performed for a 100 MWt gas-cooled test reactor. The initial design uses standard prismatic blocks and 15.5% enriched UCO fuel. Reactor physics and thermal-hydraulics simulations have been performed to identify some reactor design features to investigate further. Current status of the effort is described.

  11. Gas cooled fast reactor research and development program

    International Nuclear Information System (INIS)

    The research and development work in the field of core thermal-hydraulics, steam generator research and development, experimental and analytical physics and carbide fuel development carried out 1978 for the Gas Cooled Fast Breeder Reactor at the Swiss Federal Institute for Reactor Research is described. (Auth.)

  12. Detection of fuel element failures at the gas cooled reactors

    International Nuclear Information System (INIS)

    This paper describes the system for measuring the concentration of released Kr and Xe in the cooling gas. The system developed in the Jozef Stefan Institute is efficient and suitable for application The method is based on electrostatic collection of daughter elements from radioactive decay of Xe and Kr

  13. Control rod drive for high temperature gas cooled reactor

    Institute of Scientific and Technical Information of China (English)

    DengJun-Xian; XuJi-Ming; 等

    1998-01-01

    This control rod drive is developed for HTR-10 high temperature gas cooled test reactor.The stepmotor is prefered to improve positioning of the control rod and the scram behavior.The preliminary test in 1600170 ambient temperature shows that the selected stepmotor and transmission system can meet the main operation function requirements of HTR-10.

  14. IAEA activities in Gas-cooled Reactor technology development

    International Nuclear Information System (INIS)

    The International Atomic Energy Agency (IAEA) has the charter to ''foster the exchange of scientific and technical information'', and ''encourage and assist research on, and development and practical application of, atomic energy for peaceful uses throughout the world''. This paper describes the Agency's activities in Gas-cooled Reactor (GCR) technology development

  15. IAEA activities in gas-cooled reactor technology development

    International Nuclear Information System (INIS)

    The International Atomic Energy Agency (IAEA) has the charter to ''foster the exchange of scientific and technical information'', and ''encourage and assist research on, and development and practical application of, atomic energy for peaceful uses throughout the world''. This paper describes the Agency's activities in Gas-cooled Reactor (GCR) technology development

  16. Gas cooled fast reactor research and development program

    International Nuclear Information System (INIS)

    The research and development work in the field of core thermal-hydraulics, steam generator research and development, experimental and analytical physics and carbide fuel development carried out 1979 for the Gas Cooled Fast Breeder Reactor at the Swiss Federal Institute for Reactor Research is described. (Auth.)

  17. Gas cooled fast reactor research and development program

    International Nuclear Information System (INIS)

    The research and development work in the field of core thermal-hydraulics, experimental and analytical physics and carbide fuel development carried out 1978 for the Gas Cooled Fast Breeder Reactor at the Swiss Federal Institute for Reactor Research is described. (Auth.)

  18. Technology of steam generators for gas-cooled reactors. Proceedings of a specialists' meeting

    International Nuclear Information System (INIS)

    The activity of the IAEA in the field of the technology of gas-cooled reactors was formalized by formation of an International Working Group on Gas-Cooled Reactors (IWGCR). The gas cooled reactor program considered by the IWGCR includes carbon-dioxide-cooled thermal reactors, helium cooled thermal high temperature reactors for power generation and for process heat applications and gas-cooled fast breeder reactors. This report covers the papers dealing with operating experience, steam generators for next generation of gas-cooled reactors, material development and corrosion problems, and thermohydraulics

  19. Coated particle fuel for high temperature gas cooled reactors

    International Nuclear Information System (INIS)

    for process heat/hydrogen generation applications with 950 .deg. C outlet temperatures. There is a clear set of standards for modern high quality fuel in terms of low levels of heavy metal contamination, manufacture-induced particle defects during fuel body and fuel element making, irradiation/accident induced particle failures and limits on fission product release from intact particles. While gas-cooled reactor design is still open-ended with blocks for the prismatic and spherical fuel elements for the pebble-bed design, there is near worldwide agreement on high quality fuel: a 500 μm diameter UO2 kernel of 10% enrichment is surrounded by a 100 μm thick sacrificial buffer layer to be followed by a dense inner pyrocarbon layer, a high quality silicon carbide layer of 35 μm thickness and theoretical density and another outer pyrocarbon layer. Good performance has been demonstrated both under operational and under accident conditions, i.e. to 10% FIMA and maximum 1600 .deg. C afterwards. And it is the wide-ranging demonstration experience that makes this particle superior. Recommendations are made for further work: 1. Generation of data for presently manufactured materials, e.g. SiC strength and strength distribution, PyC creep and shrinkage and many more material data sets. 2. Renewed start of irradiation and accident testing of modern coated particle fuel. 3. Analysis of existing and newly created data with a view to demonstrate satisfactory performance at burnups beyond 10% FIMA and complete fission product retention even in accidents that go beyond 1600 .deg. C for a short period of time. This work should proceed at both national and international level

  20. Blue-sky bifurcation of ion energies and the limits of neutral-gas sympathetic cooling of trapped ions.

    Science.gov (United States)

    Schowalter, Steven J; Dunning, Alexander J; Chen, Kuang; Puri, Prateek; Schneider, Christian; Hudson, Eric R

    2016-01-01

    Sympathetic cooling of trapped ions through collisions with neutral buffer gases is critical to a variety of modern scientific fields, including fundamental chemistry, mass spectrometry, nuclear and particle physics, and atomic and molecular physics. Despite its widespread use over four decades, there remain open questions regarding its fundamental limitations. To probe these limits, here we examine the steady-state evolution of up to 10 barium ions immersed in a gas of three-million laser-cooled calcium atoms. We observe and explain the emergence of nonequilibrium behaviour as evidenced by bifurcations in the ion steady-state temperature, parameterized by ion number. We show that this behaviour leads to the limitations in creating and maintaining translationally cold samples of trapped ions using neutral-gas sympathetic cooling. These results may provide a route to studying non-equilibrium thermodynamics at the atomic level. PMID:27511602

  1. Blue-sky bifurcation of ion energies and the limits of neutral-gas sympathetic cooling of trapped ions

    CERN Document Server

    Schowalter, Steven J; Chen, Kuang; Puri, Prateek; Schneider, Christian; Hudson, Eric R

    2016-01-01

    Sympathetic cooling of trapped ions through collisions with neutral buffer gases is critical to a variety of modern scientific fields, including fundamental chemistry, mass spectrometry, nuclear and particle physics, and atomic and molecular physics. Despite its widespread use over four decades, there remain open questions regarding its fundamental limitations. To probe these limits, here we examine the steady-state evolution of up to ten barium ions immersed in a gas of three-million laser-cooled calcium atoms. We observe and explain the emergence of nonequilibrium behavior as evidenced by bifurcations in the ion steady-state temperature, parameterized by ion number. We show that this behavior leads to limitations in creating and maintaining translationally cold samples of trapped ions using neutral-gas sympathetic cooling. These results may provide a route to studying nonequilibrium thermodynamics.

  2. 780nm Rubdium Faraday Anomalous Dispersion Optical Filter with Buffer Gas Xe

    Science.gov (United States)

    Xiong, Junyu; Yin, Longfei; Luo, Bin; Guo, Hong; Cream Team

    2016-05-01

    Faraday anomalous dispersion optical filter (FADOF) is the most commonly used atomic filter, which is usually realized using alkali metal vapor cells. The filter has wide applications fields such as free-space optical communication, lidar and ghost imaging due to its high transmittance and ultra-narrow bandwidth. However, because FADOF is based on the resonant transitions of atoms, and due to the hyperfine structure of alkali elements, the transmittance spectrum of FADOF usually exhibit multi-peak form, which is not appropriate for applications requiring for single peak and will also reduce the signal to noise ratio(SNR). In this work, a 4cm long rubidium cell filled with 1torr Xenon as buffer gas has been used to realize a 780nm FADOF. Under the influence of the buffer gas Xenon, the sidebands of the transmittance spectrum has been removed, and a 780nm FADOF with single peak transmittance spectrum is achieved, which still keeps the high transmittance and ultra-narrow bandwidth. The peak transmittance of the filter is 82.7% if the power loss caused by the optical instruments (38%) is not included, and the bandwidth equals 1.2GHz. This work is supported by the National Science Fund for Distinguished Young Scholars of China (61225003), the National Natural Science Foundation of China (61401036, 61531003, 61571018), the China Postdoctoral Science Foundation (2015M580008).

  3. AGN-stimulated Cooling of Hot Gas in Elliptical Galaxies

    CERN Document Server

    Valentini, Milena

    2015-01-01

    We study the impact of relatively weak AGN feedback on the interstellar medium of intermediate and massive elliptical galaxies. We find that the AGN activity, while globally heating the ISM, naturally stimulates some degree of hot gas cooling on scales of several kpc. This process generates the persistent presence of a cold ISM phase, with mass ranging between 10$^4$ and $\\gtrsim$ 5 $\\times$ 10$^7$ M$_\\odot$, where the latter value is appropriate for group centered, massive galaxies. Widespread cooling occurs where the ratio of cooling to free-fall time before the activation of the AGN feedback satisfies $t_{cool}/t_{ff} \\lesssim 70$, that is we find a less restrictive threshold than commonly quoted in the literature. This process helps explaining the body of observations of cold gas (both ionized and neutral/molecular) in Ellipticals and, perhaps, the residual star formation detected in many early-type galaxies. The amount and distribution of the off-center cold gas vary irregularly with time. The cold ISM v...

  4. Cooling dynamics of a granular gas of elongated particles

    International Nuclear Information System (INIS)

    The cooling dynamics of a 2D granular gas of elongated particles is analyzed. We perform simulations on the temporal evolution of soft particles, using a molecular dynamics algorithm. For weakly dissipative particles, we found a homogeneous cooling process where the overall translational kinetic energy decreases analogously to viscoelastic circular particles. In contrast, for strongly dissipative particles we observed an inhomogeneous cooling process where the diminishing of translational kinetic energy notably slows down. The rotational kinetic energy, however, always decays in agreement with Haff's prediction for the homogeneous cooling state of inelastic particles. We mainly found that the cooling kinetics of the system is controlled by the mechanisms that determine the local energy dissipation (collisions). However, we detected a strong influence of particle shape and inelasticity on the structure of the clusters which develop in the inhomogeneous cooling regimes. Our numerical outcomes suggest that strong dissipation and particle anisotropy induce the formation of ordered cluster structures that retards the relaxation to the final asymptotic regime

  5. Gas-Cooled Reactors: the importance of their development

    International Nuclear Information System (INIS)

    Gas-Cooled Reactors are considered to have a significant future impact on the application of fission energy. The specific types are the steam-cycle High-Temperature Gas-Cooled Reactor, the Gas-Cooled Fast Breeder Reactor, the gas-turbine HTGR, and the Very High-Temperature Process Heat Reactor. The importance of developing the above systems is discussed relative to alternative fission power systems involving Light Water Reactors, Heavy Water Reactors, Spectral Shift Controlled Reactors, and Liquid-Metal-Cooled Fast Breeder Reactors. A primary advantage of developing GCRs as a class lies in the technology and cost interrelations, permitting cost-effective development of systems having diverse applications. Further, HTGR-type systems have highly proliferation-resistant characteristics and very attractive safety features. Finally, such systems and GCFRs are mutally complementary. Overall, GCRs provide interrelated systems that serve different purposes and needs; their development can proceed in stages that provide early benefits while contributing to future needs. It is concluded that the long-term importance of the various GCRs is as follows: HTGR, providing a technology for economic GCFRs and HTGR-GTs, while providing a proliferation-resistant reactor system having early economic and fuel utilization benefits; GCFR, providing relatively low cost fissile fuel and reducing overall separative work needs at capital costs lower than those for LMFBRs; HTGR-GT (in combination with a bottoming cycle), providing a very high thermal efficiency system having low capital costs and improved fuel utilization and technology pertinent to VHTRs; HTGR-GT, providing a power system well suited for dry cooling conditions for low-temperature process heat needs; and VHTR, providing a high-temperature heat source for hydrogen production processes

  6. Gas entrainment issues in sodium cooled fast reactors

    International Nuclear Information System (INIS)

    Highlights: • Main sources of gas and related issues in SFR are presented. • Various approaches of gas transport are briefly described. • Previous experimental studies to reduce gas entrainment are reported. • Present evaluation of free surface gas entrainment is presented. - Abstract: Sodium cooled fast reactors have been developed in France for nearly 50 years. The so-called Astrid technology demonstrator is currently designed in the frame of Generation IV deployment. Gas entrainment in the primary sodium circuit is a key issue as it can lead to safety problems in case of accumulation and transport of large quantity of gas through the core. The paper first introduces the main problems caused by the presence of gas in the primary sodium circuit, the various sources of gas and the main issues on gas transport. As sodium–argon free surface is potentially an important source of gas entrainment in the primary circuit, we present the main results obtained in past experimental studies on vortex type gas entrainment at free surface. Water tests were performed in a simple flow condition to study the physical process of vortex occurrence and gas entrainment. Other water tests were performed in representative hot pool models at different scales to analyze similarity criteria. Moreover, design improvements and local devices were tested to avoid gas entrainment at the free surface. Nowadays, numerical tools are progressively used to estimate the risk of gas entrainment at the free surface. We present the methodology in progress to define local criteria on vortex occurrence and gas entrainment, and to apply these criteria to global calculations of the whole pool. A Front-Tracking method coupled to a Large Eddy Simulation approach is implemented in TRIOU code to compute free surface instabilities and vortex occurrence. Experimental data from the literature are used to validate the numerical approach and a new test facility called BANGA is in progress at CEA to

  7. Diffusion, thermalization, and optical pumping of YbF molecules in a cold buffer-gas cell

    Science.gov (United States)

    Skoff, S. M.; Hendricks, R. J.; Sinclair, C. D. J.; Hudson, J. J.; Segal, D. M.; Sauer, B. E.; Hinds, E. A.; Tarbutt, M. R.

    2011-02-01

    We produce YbF molecules with a density of 1018 m-3 using laser ablation inside a cryogenically cooled cell filled with a helium buffer gas. Using absorption imaging and absorption spectroscopy we study the formation, diffusion, thermalization, and optical pumping of the molecules. The absorption images show an initial rapid expansion of molecules away from the ablation target followed by a much slower diffusion to the cell walls. We study how the time constant for diffusion depends on the helium density and temperature and obtain values for the YbF-He diffusion cross section at two different temperatures. We measure the translational and rotational temperatures of the molecules as a function of time since formation, obtain the characteristic time constant for the molecules to thermalize with the cell walls, and elucidate the process responsible for limiting this thermalization rate. Finally, we make a detailed study of how the absorption of the probe laser saturates as its intensity increases, showing that the saturation intensity is proportional to the helium density. We use this to estimate collision rates and the density of molecules in the cell.

  8. Aging studies on micro-fabricated alkali buffer-gas cells for miniature atomic clocks

    International Nuclear Information System (INIS)

    We report an aging study on micro-fabricated alkali vapor cells using neon as a buffer gas. An experimental atomic clock setup is used to measure the cell's intrinsic frequency, by recording the clock frequency shift at different light intensities and extrapolating to zero intensity. We find a drift of the cell's intrinsic frequency of (−5.2 ± 0.6) × 10−11/day and quantify deterministic variations in sources of clock frequency shifts due to the major physical effects to identify the most probable cause of the drift. The measured drift is one order of magnitude stronger than the total frequency variations expected from clock parameter variations and corresponds to a slow reduction of buffer gas pressure inside the cell, which is compatible with the hypothesis of loss of Ne gas from the cell due to its permeation through the cell windows. A negative drift on the intrinsic cell frequency is reproducible for another cell of the same type. Based on the Ne permeation model and the measured cell frequency drift, we determine the permeation constant of Ne through borosilicate glass as (5.7 ± 0.7) × 10−22 m2 s−1 Pa−1 at 81 °C. We propose this method based on frequency metrology in an alkali vapor cell atomic clock setup based on coherent population trapping for measuring permeation constants of inert gases

  9. Aging studies on micro-fabricated alkali buffer-gas cells for miniature atomic clocks

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, S.; Affolderbach, C.; Gruet, F.; Mileti, G., E-mail: gaetano.mileti@unine.ch [Laboratoire Temps-Fréquence, Institut de Physique, Université de Neuchâtel, Neuchâtel CH-2000 (Switzerland)

    2015-04-20

    We report an aging study on micro-fabricated alkali vapor cells using neon as a buffer gas. An experimental atomic clock setup is used to measure the cell's intrinsic frequency, by recording the clock frequency shift at different light intensities and extrapolating to zero intensity. We find a drift of the cell's intrinsic frequency of (−5.2 ± 0.6) × 10{sup −11}/day and quantify deterministic variations in sources of clock frequency shifts due to the major physical effects to identify the most probable cause of the drift. The measured drift is one order of magnitude stronger than the total frequency variations expected from clock parameter variations and corresponds to a slow reduction of buffer gas pressure inside the cell, which is compatible with the hypothesis of loss of Ne gas from the cell due to its permeation through the cell windows. A negative drift on the intrinsic cell frequency is reproducible for another cell of the same type. Based on the Ne permeation model and the measured cell frequency drift, we determine the permeation constant of Ne through borosilicate glass as (5.7 ± 0.7) × 10{sup −22} m{sup 2} s{sup −1 }Pa{sup −1} at 81 °C. We propose this method based on frequency metrology in an alkali vapor cell atomic clock setup based on coherent population trapping for measuring permeation constants of inert gases.

  10. Ambient air cooling arrangement having a pre-swirler for gas turbine engine blade cooling

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ching-Pang; Tham, Kok-Mun; Schroeder, Eric; Meeroff, Jamie; Miller, Jr., Samuel R; Marra, John J

    2015-01-06

    A gas turbine engine including: an ambient-air cooling circuit (10) having a cooling channel (26) disposed in a turbine blade (22) and in fluid communication with a source (12) of ambient air: and an pre-swirler (18), the pre-swirler having: an inner shroud (38); an outer shroud (56); and a plurality of guide vanes (42), each spanning from the inner shroud to the outer shroud. Circumferentially adjacent guide vanes (46, 48) define respective nozzles (44) there between. Forces created by a rotation of the turbine blade motivate ambient air through the cooling circuit. The pre-swirler is configured to impart swirl to ambient air drawn through the nozzles and to direct the swirled ambient air toward a base of the turbine blade. The end walls (50, 54) of the pre-swirler may be contoured.

  11. Spectral narrowing of coherent population trapping resonance in laser-cooled and room-temperature atomic gas

    Indian Academy of Sciences (India)

    S Pradhan; S Mishra; R Behera; N Kawade; A K Das

    2014-02-01

    We have investigated coherent population trapping (CPT) in laser-cooled as well as room-temperature (with and without buffer gas) rubidium atoms. The characteristic broad signal profile emerging from the two-photon Raman resonance for room-temperature atomic vapour is consistent with the theoretical calculation incorporating associated thermal averaging. The spectral width of the dark resonance obtained with cold atoms is found to be broadened, compared to roomtemperature vapour cell, due to the feeble role played by thermal averaging, although the cold atomic sample significantly overcomes the limitation of the transit time broadening. An alternative way to improve transit time is to use a buffer gas, with which we demonstrate that the coherent population trapping signal width is reduced to < 540 Hz.

  12. Fuel performance and fission product behaviour in gas cooled reactors

    International Nuclear Information System (INIS)

    The Co-ordinated Research Programme (CRP) on Validation of Predictive Methods for Fuel and Fission Product Behaviour was organized within the frame of the International Working Group on Gas Cooled Reactors. This International Working Group serves as a forum for exchange of information on national programmes, provides advice to the IAEA on international co-operative activities in advanced technologies of gas cooled reactors (GCRs), and supports the conduct of these activities. The objectives of this CRP were to review and document the status of the experimental data base and of the predictive methods for GCR fuel performance and fission product behaviour; and to verify and validate methodologies for the prediction of fuel performance and fission product transport

  13. Decay heat removal in GEN IV gas cooled fast reactors

    International Nuclear Information System (INIS)

    The safety goal of the current designs of advanced high-temperature thermal gas-cooled reactors (HTRs) is that no core meltdown would occur in a depressurization event with a combination of concurrent safety system failures. This study focused on the analysis of passive decay heat removal (DHR) in a GEN IV direct-cycle gas-cooled fast reactor (GFR) which is based on the technology developments of the HTRs. Given the different criteria and design characteristics of the GFR, an approach different from that taken for the HTRs for passive DHR would have to be explored. Different design options based on maintaining core flow were evaluated by performing transient analysis of a depressurization accident using the system code RELAP5-3D. The study also reviewed the conceptual design of autonomous systems for shutdown decay heat removal and recommends that future work in this area should be focused on the potential for Brayton cycle DHRs.

  14. The case for the gas cooled fast reactor

    International Nuclear Information System (INIS)

    Although gas-cooling for fast reactors had been the subject of consideration since the early days of nuclear power, it was when the concept of the prestressed concrete pressure vessel turned into practical fact, that convincing arguments could be made to overcome safety objections. In terms of hardware, the Gas Cooled Fast Breeder Reactor can rely on existing and available technologies; as far as fuel is concerned, valuable information will be derived from the Liquid Metal Fast Breeder Reactor programme. The GCFR can be made very flexible; its capital cost will not exceed by more than 20% the one for reactor built at present on commercial scale; the overall economy of its fuel cycle is good. It could play an important role in the future breeder family

  15. Gas turbine cooling modeling - Thermodynamic analysis and cycle simulations

    Energy Technology Data Exchange (ETDEWEB)

    Jordal, Kristin

    1999-02-01

    Considering that blade and vane cooling are a vital point in the studies of modern gas turbines, there are many ways to include cooling in gas turbine models. Thermodynamic methods for doing this are reviewed in this report, and, based on some of these methods, a number of model requirements are set up and a Cooled Gas Turbine Model (CGTM) for design-point calculations of cooled gas turbines is established. Thereafter, it is shown that it is possible to simulate existing gas turbines with the CGTM. Knowledge of at least one temperature in the hot part of the turbine (TET, TRIT or possibly TIT) is found to be vital for a complete heat balance over the turbine. The losses, which are caused by the mixing of coolant and main flow, are in the CGTM considered through a polytropic efficiency reduction factor S. Through the study of S, it can be demonstrated that there is more to gain from coolant reduction in a small and/or old turbine with poor aerodynamics, than there is to gain in a large, modern turbine, where the losses due to interaction between coolant and main flow are, relatively speaking, small. It is demonstrated, at the design point (TET=1360 deg C, {pi}=20) for the simple-cycle gas turbine, that heat exchanging between coolant and fuel proves to have a large positive impact on cycle efficiency, with an increase of 0.9 percentage points if all of the coolant passes through the heat exchanger. The corresponding improvement for humidified coolant is 0.8 percentage points. A design-point study for the HAT cycle shows that if all of the coolant is extracted after the humidification tower, there is a decrease in coolant requirements of 7.16 percentage points, from 19.58% to 12.52% of the compressed air, and an increase in thermal efficiency of 0.46 percentage points, from 53.46% to 53.92%. Furthermore, it is demonstrated with a TET-parameter variation, that the cooling of a simple-cycle gas turbine with humid air can have a positive effect on thermal efficiency

  16. Gas Cooled Fast Reactors: Recent advances and prospects

    International Nuclear Information System (INIS)

    The paper presents the current status of the Gas cooled Fast Reactor system development which is shared within the Generation IV International Forum including EURATOM through the 7th Framework Programme project GoFastR. The various areas considered will include suitable fuel compounds and high temperature resistant cladding materials options, core design optimisation, primary system boundary, energy conversion. The safety approach, mainly oriented on core cooling for the moment, will be recalled together with a discussion of the results obtained. Further potential improvements or simplification of the system safety, at the light of the Fukushima accident, including an indirect coupled cycle for the energy conversion and a self sustainable Decay Heat Removal loop will be mentioned. The main issues related to the necessary R&D programme accompanying the system development will be recalled (fuel and materials, helium coolant technology, components such as gas circulators, valves and heat exchangers, thermal barriers). (author)

  17. Flue gas injection control of silica in cooling towers.

    Energy Technology Data Exchange (ETDEWEB)

    Brady, Patrick Vane; Anderson, Howard L., Jr.; Altman, Susan Jeanne

    2011-06-01

    Injection of CO{sub 2}-laden flue gas can decrease the potential for silica and calcite scale formation in cooling tower blowdown by lowering solution pH to decrease equilibrium calcite solubility and kinetic rates of silica polymerization. Flue gas injection might best inhibit scale formation in power plant cooling towers that use impaired makeup waters - for example, groundwaters that contain relatively high levels of calcium, alkalinity, and silica. Groundwaters brought to the surface for cooling will degas CO{sub 2} and increase their pH by 1-2 units, possibly precipitating calcite in the process. Recarbonation with flue gas can lower the pHs of these fluids back to roughly their initial pH. Flue gas carbonation probably cannot lower pHs to much below pH 6 because the pHs of impaired waters, once outgassed at the surface, are likely to be relatively alkaline. Silica polymerization to form scale occurs most rapidly at pH {approx} 8.3 at 25 C; polymerization is slower at higher and lower pH. pH 7 fluids containing {approx}220 ppm SiO{sub 2} require > 180 hours equilibration to begin forming scale whereas at pH 8.3 scale formation is complete within 36 hours. Flue gas injection that lowers pHs to {approx} 7 should allow substantially higher concentration factors. Periodic cycling to lower recoveries - hence lower silica concentrations - might be required though. Higher concentration factors enabled by flue gas injection should decrease concentrate volumes and disposal costs by roughly half.

  18. High-Temperature Gas-Cooled Test Reactor Point Design

    Energy Technology Data Exchange (ETDEWEB)

    Sterbentz, James William [Idaho National Laboratory; Bayless, Paul David [Idaho National Laboratory; Nelson, Lee Orville [Idaho National Laboratory; Gougar, Hans David [Idaho National Laboratory; Kinsey, James Carl [Idaho National Laboratory; Strydom, Gerhard [Idaho National Laboratory; Kumar, Akansha [Idaho National Laboratory

    2016-04-01

    A point design has been developed for a 200 MW high-temperature gas-cooled test reactor. The point design concept uses standard prismatic blocks and 15.5% enriched UCO fuel. Reactor physics and thermal-hydraulics simulations have been performed to characterize the capabilities of the design. In addition to the technical data, overviews are provided on the technological readiness level, licensing approach and costs.

  19. The status of graphite development for gas cooled reactors

    International Nuclear Information System (INIS)

    The meeting was convened by the IAEA on the recommendation of the International Working Group on Gas Cooled Reactors. It was attended by 61 participants from 6 countries. The meeting covered the following subjects: overview of national programs; design criteria, fracture mechanisms and component test; materials development and properties; non-destructive examination, inspection and surveillance. The participants presented 33 papers on behalf of their countries. A separate abstract was prepared for each of these papers. Refs, figs, tabs, photos and diagrams

  20. Thermal top shield for gas-cooled nuclear reactors

    International Nuclear Information System (INIS)

    Proposed is a thermal top shield for gas-cooled nuclear reactors which together with the thermal side and bottom shield forms an almost gas-tight room for taking up the core structure and which protects the top of the concrete vessel sufficiently against overheating. The thermal top shield consists of top shield elements put closely together, which are made of at least two horizontal metal layers and at least one moderator layer located between the metal layers and which are fixed to the top liner by means of drawbars. (orig.)

  1. The Buffer-Gas Positron Accumulator and Resonances in Positron-Molecule Interactions

    Science.gov (United States)

    Surko, C.M.

    2007-01-01

    This is a personal account of the development of our buffer-gas positron trap and the new generation of cold beams that these traps enabled. Dick Drachman provided much appreciated advice to us from the time we started the project. The physics underlying trap operation is related to resonances (or apparent resonances) in positron-molecule interactions. Amusingly, experiments enabled by the trap allowed us to understand these processes. The positron-resonance "box score" to date is one resounding "yes," namely vibrational Feshbach resonances in positron annihilation on hydrocarbons; a "probably" for positron-impact electronic excitation of CO and NZ;an d a "maybe" for vibrational excitation of selected molecules. Two of these processes enabled the efficient operation of the trap, and one almost killed it in infancy. We conclude with a brief overview of further applications of the trapping technology discussed here, such as "massive" positron storage and beams with meV energy resolution.

  2. Testing stand for cosmic gas-cooling fast reactor's sample

    International Nuclear Information System (INIS)

    For carrying out of technical decision and nuclear, radiation and technological safety of gas-cooling space nuclear power plants is elaborating gas-cooling fast reactor's testing stand. In the base of its draft is taken conception of the reactor with filling up type reactor core on the base of ball fuel elements and radial coolant flowing. On the testing stand would suggested carrying out testing for study neutron and physical parameters of gas-cooling reactor, its behaviour under accident simulation. In the reactor core will suggest use carbon nitrides fuel elements with tungsten cover, provides under nominal regime relatively low fission products yield to first contour of device. Construction of fuel element was carrying out on reactor and non reactor testing and its calculated on working resource about 3000 hours. Constructive materials of reactor core have lower melting temperature, that provides organized in good time remove fuel element to containers placed under reactor in case connected with hypothetical accident. In the construction of reactor for seen tree-contours system of heat transfer and its provides multistage system of barriers against fission products yield to environment. tabs.1

  3. Behaviour of gas cooled reactor fuel under accident conditions

    International Nuclear Information System (INIS)

    The Specialists Meeting on Behaviour of Gas Cooled Reactor Fuel under Accident Conditions was convened by the International Atomic Energy Agency on the recommendation of the International Working Group on Gas Cooled Reactors. The purpose of the meeting was to provide an international forum for the review of the development status and for the discussion on the behaviour of gas cooled reactor fuel under accident conditions and to identify areas in which additional research and development are still needed and where international co-operation would be beneficial for all involved parties. The meeting was attended by 45 participants from France, Germany, Japan, Switzerland, the Union of Soviet Socialists Republics, the United Kingdom, the United States of America, CEC and the IAEA. The meeting was subdivided into five technical sessions: Summary of Current Research and Development Programmes for Fuel; Fuel Manufacture and Quality Control; Safety Requirements; Modelling of Fission Product Release - Part I and Part II; Irradiation Testing/Operational Experience with Fuel Elements; Behaviour at Depressurization, Core Heat-up, Power Transients; Water/Steam Ingress - Part I and Part II. 22 papers were presented. A separate abstract was prepared for each of these papers. At the end of the meeting a round table discussion was held on Directions for Future R and D Work and International Co-operation. Refs, figs and tabs

  4. Mitigation of gas entrainment in sodium cooled fast reactors

    International Nuclear Information System (INIS)

    Argon cover gas may entrain into sodium in the hot pool and in the surge tank of liquid Sodium cooled Fast Reactor (SFR) due to various mechanisms. The entrained cover gas may hinder the normal reactor operation in many ways such as reduction in heat transfer in the heat exchanger, causing neutronic perturbation inside the core etc. The recirculating gas bubbles also enhance chances of cavitation in the pumps. Therefore, it is required to mitigate gas entrainment in reactor. High free surface velocity and turbulence level are the causes of gas entrainment from free surface. Hence, gas entrainment can be avoided by reducing these factors at free surface. This is achieved by employing gas entrainment mitigation devices which essentially alters the flow pattern and reduces velocity and turbulence level at the free surface. A combined experimental and computational approach is proposed to develop such devices. The computational model which is used for parametric studies is first validated against experiments carried out in scale down water model of reactor primary circuit and surge tank. The effect of different gas entrainment mitigating devices for reduction in free surface velocity and turbulence level has been analyzed using this validated CFD model. Based on the CFD analyses, the final geometry of the gas entrainment mitigating devices has been selected and optimized. Finally the selected devices have been tested to confirm its performance for mitigation of gas entrainment in large scale models of reactor primary circuit and surge tank. This paper presents the studies carried out towards development of suitable gas entrainment mitigation devices for hot pool and surge tank of SFR. (author)

  5. The formation and physical origin of highly ionized cooling gas

    CERN Document Server

    Bordoloi, Rongmon; Norman, Colin A

    2016-01-01

    We present a physically clear cooling flow theory that explains the origin of warm diffuse gas seen primarily as highly ionized absorption line systems in the spectra of background sources. We predict the observed column densities of several highly ionized transitions such as O VI, O VII, Ne VIII, N V, and Mg X; and present a unified comparison of the model predictions with absorption lines seen in the Milky Way disk, Milky Way halo, starburst galaxies, the circumgalactic medium and the intergalactic medium at low and high redshifts. We show that diffuse gas seen in such diverse environments can be simultaneously explained by a simple model of radiatively cooling gas. We show that most of such absorption line systems are consistent with being collisionally ionized, and estimate the maximum likelihood temperature of the gas in each observation. This model satisfactorily explains why O VI is regularly observed around star-forming low-z L* galaxies, and why N V is rarely seen around the same galaxies. We predict...

  6. Review of RSG-GAS secondary cooling pump performance

    International Nuclear Information System (INIS)

    The control system of RSG-GAS secondary pump is the study for the operation existence of RSG-GAS secondary pump. The research is about characteristic of the secondary pump and its control system. The measuring of characteristic parameter of secondary cooling pump was being done while the pump running. The pump was loading with capacity 1950 m3/hr. with ambient temperature 28.5 oC. The fault effect of public grid (PLN) such as the fluctuation of both voltage and frequency likes voltage drops (dip). Supply block out that effect of the electric motor performances directly will be analyzed. How far those faults will effect the overall performance of secondary cooling system. Analyzing. Will be done according to the control system was installed. Has be done to find the direct effects of the motor performances against the motor rotation fluctuation which run from 1450 rpm to 1475 rpm. The using of start-delta starting method with delay time about 6 seconds, is enough or not to reduce the inrush starting current also analyzed in this paper. From the research can be obtained that in the steady state condition , the electric motor runs with both power and current are still under tolerances permitted. According to the analyzed data above, it will be consider that the control system of secondary pump would be modified or not. Therefore the analyzed data can show the characteristic curve of the secondary cooling system performance

  7. Medium-size high-temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    This report summarizes high-temperature gas-cooled reactor (HTGR) experience for the 40-MW(e) Peach Bottom Nuclear Generating Station of Philadelphia Electric Company and the 330-MW(e) Fort St. Vrain Nuclear Generating Station of the Public Service Company of Colorado. Both reactors are graphite moderated and helium cooled, operating at approx. 7600C (14000F) and using the uranium/thorium fuel cycle. The plants have demonstrated the inherent safety characteristics, the low activation of components, and the high efficiency associated with the HTGR concept. This experience has been translated into the conceptual design of a medium-sized 1170-MW(t) HTGR for generation of 450 MW of electric power. The concept incorporates inherent HTGR safety characteristics [a multiply redundant prestressed concrete reactor vessel (PCRV), a graphite core, and an inert single-phase coolant] and engineered safety features

  8. Oil cooling system for a gas turbine engine

    Science.gov (United States)

    Coffinberry, G. A.; Kast, H. B. (Inventor)

    1977-01-01

    A gas turbine engine fuel delivery and control system is provided with means to recirculate all fuel in excess of fuel control requirements back to aircraft fuel tank, thereby increasing the fuel pump heat sink and decreasing the pump temperature rise without the addition of valving other than that normally employed. A fuel/oil heat exchanger and associated circuitry is provided to maintain the hot engine oil in heat exchange relationship with the cool engine fuel. Where anti-icing of the fuel filter is required, means are provided to maintain the fuel temperature entering the filter at or above a minimum level to prevent freezing thereof. Fluid circuitry is provided to route hot engine oil through a plurality of heat exchangers disposed within the system to provide for selective cooling of the oil.

  9. Thermodynamic analysis of turbine blade cooling on the performance of gas turbine cycle

    International Nuclear Information System (INIS)

    Turbine inlet temperature strongly affects gas turbine performance. Today blade cooling technologies facilitate the use of higher inlet temperatures. Of course blade cooling causes some thermodynamic penalties that destroys to some extent the positive effect of higher inlet temperatures. This research aims to model and evaluate the performance of gas turbine cycle with air cooled turbine. In this study internal and transpiration cooling methods has been investigated and the penalties as the result of gas flow friction, cooling air throttling, mixing of cooling air flow with hot gas flow, and irreversible heat transfer have been considered. In addition, it is attempted to consider any factor influencing actual conditions of system in the analysis. It is concluded that penalties due to blade cooling decrease as permissible temperature of the blade surface increases. Also it is observed that transpiration method leads to better performance of gas turbine comparing to internal cooling method

  10. Gas-cooled reactor application for a university campus

    International Nuclear Information System (INIS)

    Large urban areas with unfavourable topographic and meteorological conditions suffer severe air pollution during the winter months. Use of low grade lignites, imported higher quality coal or imported fuel oil are the sources of air pollution in the form of sulphur dioxide, fly ash and soot. Large housing complexes or old and historical locations within the city are in need of pollution free centralized district heating systems. Natural gas imported from the Soviet Union is a solution for this problem. Lack of gas distribution network for high pressure gas within the city is the main bottle-neck for the heating systems utilizing natural gas. Concern of the safety of flammable high pressure gas circulating within the city is another drawback for the natural gas heating systems. Nuclear district heating is an environmentally viable option worth looking into it. Localized urban nuclear heating is an interesting solution for large urban areas with old and historical character. The results of a feasibility study on the HGR application for the Hacettepe University presented here, summarizes the concept of gas-cooled heating reactors specially designed for urban centers. The inherently safe characteristics of the pebble bed heating reactor makes localized urban nuclear heating a viable alternative to other heat sources. An economical analysis of various heat sources with equal power levels is done for the Beytepe campus of Hacettepe University in Ankara. Under special boundary conditions, the price for heat generation can be much lower for nuclear heating with GHR 20 than for hard coal or fuel oil. It is also possible that if the price escalation rate for natural gas exceeds 3%, then nuclear heating with GHR can be more competitive. It is concluded that the nuclear heating of Beytepe campus with a GHR 20 is feasible and economical. (author) 3 figs., 5 refs

  11. Gas-cooled reactor coolant circulator and blower technology

    International Nuclear Information System (INIS)

    In the previous 17 meetings held within the framework of the International Working Group on Gas-Cooled Reactors, a wide variety of topics and components have been addressed, but the San Diego meeting represented the first time that a group of specialists had been convened to discuss circulator and blower related technology. A total of 20 specialists from 6 countries attended the meeting in which 15 technical papers were presented in 5 sessions: circulator operating experience I and II (6 papers); circulator design considerations I and II (6 papers); bearing technology (3 papers). A separate abstract was prepared for each of these papers. Refs, figs and tabs

  12. Thorium fueled high temperature gas cooled reactors. An assessment

    International Nuclear Information System (INIS)

    The use of thorium as a fertile fuel for the High Temperature Gas Cooled Reactor (HTR) instead of uranium has been reviewed. It has been concluded that the use of thorium might be beneficial to reduce the actinide waste production. To achieve a real advancement, the uranium of the spent fuel has to be recycled and the requested make-up fissile material for the fresh fuel has to be used in the form of highly-enriched uranium. A self-sustaining fuel cycle may be possible in the HTR of large core size, but this could reduce the inherent safety features of the design. (orig.)

  13. Cooling molten salt reactors using “gas-lift”

    Energy Technology Data Exchange (ETDEWEB)

    Zitek, Pavel, E-mail: zitek@kke.zcu.cz, E-mail: klimko@kke.zcu.cz; Valenta, Vaclav, E-mail: zitek@kke.zcu.cz, E-mail: klimko@kke.zcu.cz; Klimko, Marek, E-mail: zitek@kke.zcu.cz, E-mail: klimko@kke.zcu.cz [University of West Bohemia in Pilsen, Univerzitní 8, 306 14 Pilsen (Czech Republic)

    2014-08-06

    This study briefly describes the selection of a type of two-phase flow, suitable for intensifying the natural flow of nuclear reactors with liquid fuel - cooling mixture molten salts and the description of a “Two-phase flow demonstrator” (TFD) used for experimental study of the “gas-lift” system and its influence on the support of natural convection. The measuring device and the application of the TDF device is described. The work serves as a model system for “gas-lift” (replacing the classic pump in the primary circuit) for high temperature MSR planned for hydrogen production. An experimental facility was proposed on the basis of which is currently being built an experimental loop containing the generator, separator bubbles and necessary accessories. This loop will model the removal of gaseous fission products and tritium. The cleaning of the fuel mixture of fluoride salts eliminates problems from Xenon poisoning in classical reactors.

  14. Cooling molten salt reactors using "gas-lift"

    Science.gov (United States)

    Zitek, Pavel; Valenta, Vaclav; Klimko, Marek

    2014-08-01

    This study briefly describes the selection of a type of two-phase flow, suitable for intensifying the natural flow of nuclear reactors with liquid fuel - cooling mixture molten salts and the description of a "Two-phase flow demonstrator" (TFD) used for experimental study of the "gas-lift" system and its influence on the support of natural convection. The measuring device and the application of the TDF device is described. The work serves as a model system for "gas-lift" (replacing the classic pump in the primary circuit) for high temperature MSR planned for hydrogen production. An experimental facility was proposed on the basis of which is currently being built an experimental loop containing the generator, separator bubbles and necessary accessories. This loop will model the removal of gaseous fission products and tritium. The cleaning of the fuel mixture of fluoride salts eliminates problems from Xenon poisoning in classical reactors.

  15. Gas cooled fast reactor background, facilities, industries and programmes

    International Nuclear Information System (INIS)

    This report was prepared at the request of the OECD-NEA Coordinating Group on Gas Cooled Fast Reactor Development and it represents a contribution (Vol.II) to the jointly sponsored Vol.I (GCFR Status Report). After a chapter on background with a brief description of the early studies and the activities in the various countries involved in the collaborative programme (Austria, Belgium, France, Germany, Japan, Sweden, Switzerland, United Kingdom and United States), the report describes the facilities available in those countries and at the Gas Breeder Reactor Association and the industrial capabilities relevant to the GCFR. Finally the programmes are described briefly with programme charts, conclusions and recommendations are given. (orig.)

  16. Commercial sector gas cooling technology frontier and market share analysis

    International Nuclear Information System (INIS)

    This paper describes a method, developed for the Gas Research Institute of the United States, that can assist planning for commercial sector natural gas cooling systems R and D. These systems are higher in first cost than conventional electric chillers. Yet, engine-driven chiller designs exist which are currently competitive in U.S. markets typified by high electricity or demand charges. Section II describes a scenario analysis approach used to develop and test the method. Section III defines the technology frontier, a conceptual tool for identifying new designs with sales potential. Section IV describes a discrete choice method for predicting market shares of technologies with sales potential. Section V shows how the method predicts operating parameter, cost, and/or performance goals for technologies without current sales potential (or for enhancing a frontier technology's sales potential). Section VI concludes with an illustrative example for the Chicago office building retrofit market

  17. Equation of state of a laser-cooled gas

    Science.gov (United States)

    Rodrigues, J. D.; Rodrigues, J. A.; Moreira, O. L.; Terças, H.; Mendonça, J. T.

    2016-02-01

    We experimentally determine the equation of state of a laser-cooled gas. By employing the Lane-Emden formalism, widely used in astrophysics, we derive the equilibrium atomic profiles in large magneto-optical traps where the thermodynamic effects are cast in a polytropic equation of state. The effects of multiple scattering of light are included, which results in a generalized Lane-Emden equation for the atomic profiles. A detailed experimental investigation reveals an excellent agreement with the model, with a twofold significance. On one hand, we can infer the details of the equation of state of the system, from an ideal gas to a correlated phase due to an effective electrical charge for the atoms, which is accurately described by a microscopical description of the effective electrostatic interaction. On the other hand, we are able map the effects of multiple scattering onto directly controllable experimental variables, which paves the way to subsequent experimental investigations of this collective interaction.

  18. Cooling molten salt reactors using “gas-lift”

    International Nuclear Information System (INIS)

    This study briefly describes the selection of a type of two-phase flow, suitable for intensifying the natural flow of nuclear reactors with liquid fuel - cooling mixture molten salts and the description of a “Two-phase flow demonstrator” (TFD) used for experimental study of the “gas-lift” system and its influence on the support of natural convection. The measuring device and the application of the TDF device is described. The work serves as a model system for “gas-lift” (replacing the classic pump in the primary circuit) for high temperature MSR planned for hydrogen production. An experimental facility was proposed on the basis of which is currently being built an experimental loop containing the generator, separator bubbles and necessary accessories. This loop will model the removal of gaseous fission products and tritium. The cleaning of the fuel mixture of fluoride salts eliminates problems from Xenon poisoning in classical reactors

  19. Multidisciplinary design optimization of film-cooled gas turbine blades

    Directory of Open Access Journals (Sweden)

    Talya Shashishekara S.

    1999-01-01

    Full Text Available Design optimization of a gas turbine blade geometry for effective film cooling toreduce the blade temperature has been done using a multiobjective optimization formulation. Three optimization formulations have been used. In the first, the average blade temperature is chosen as the objective function to be minimized. An upper bound constraint has been imposed on the maximum blade temperature. In the second, the maximum blade temperature is chosen as the objective function to be minimized with an upper bound constraint on the average blade temperature. In the third formulation, the blade average and maximum temperatures are chosen as objective functions. Shape optimization is performed using geometric parameters associated with film cooling and blade external shape. A quasi-three-dimensional Navier–Stokes solver for turbomachinery flows is used to solve for the flow field external to the blade with appropriate modifications to incorporate the effect of film cooling. The heat transfer analysis for temperature distribution within the blade is performed by solving the heat diffusion equation using the finite element method. The multiobjective Kreisselmeier–Steinhauser function approach has been used in conjunction with an approximate analysis technique for optimization. The results obtained using both formulations are compared with reference geometry. All three formulations yield significant reductions in blade temperature with the multiobjective formulation yielding largest reduction in blade temperature.

  20. Cooling water practices at coal and gas based power stations

    International Nuclear Information System (INIS)

    Water is used for a number of diverse purposes in a power plant. In most cases, the water cannot be used as such and requires treatment to ensure higher efficiency and protection of equipment. Corrosion, scale deposition and fouling have since long posed as challenges to the technical expertise of cooling water chemists at industrial and utility power plants. The study of the raw water, water samples from the CW tower basin and clarified water of various coal and gas based power stations has indicated that problem of corrosion and scale formation are linked with the quality of raw water and operating parameters. The present paper deals with the different cooling water treatment practices being followed at various power stations and which have been quite helpful in improving the quality of water and reduce scale promotion, thereby improving heat transfer of condenser and heat exchangers, and in addition to prevent corrosion in the pipelines, water boxes, tube plates and condenser tubes. The above said studies constitutes a part of the Research work being carried out by corrosion group of Research and Development Centre, NTPC under the project entitled evaluation of standards for cooling water treatment which has been sanctioned under CBIP (Central Board of Irrigation and Power) action plan by Department of Power to Research and Development Centre of NTPC in the 8th plan period. (author)

  1. CAST search for sub-eV mass solar axions with $^{3}$He buffer gas

    CERN Document Server

    Aune, S; Belov, A; Borghi, S; Brauninger, H; Cantatore, G; Carmona, J M; Cetin, S A; Collar, J I; Dafni, T; Davenport, M; Eleftheriadis, C; Elias, N; Ezer, C; Fanourakis, G; Ferrer-Ribas, E; Friedrich, P; Galan, J; Garcia, J A; Gardikiotis, A; Gazis, E N; Geralis, T; Giomataris, I; Gninenko, S; Gomez, H; Gruber, E; Guthorl, T; Hartmann, R; Haug, F; Hasinoff, M D; Hoffmann, D H H; Iguaz, F J; Irastorza, I G; Jacoby, J; Jakovcic, K; Karuza, M; Konigsmann, K; Kotthaus, R; Krcmar, M; Kuster, M; Lakic, B; Laurent, J M; Liolios, A; Ljubicic, A; Lozza, V; Lutz, G; Luzon, G; Morales, J; Niinikoski, T; Nordt, A; Papaevangelou, T; Pivovaroff, M J; Raffelt, G; Rashba, T; Riege, H; Rodriguez, A; Rosu, M; Ruz, J; Savvidis, I; Silva, P S; Solanki, S.K; Stewart, L; Tomas, A; Tsagri, M; van Bibber, K; Vafeiadis, T; Villar, J A; Vogel, J K; Yildiz, S C; Zioutas, K

    2011-01-01

    The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using 3He as a buffer gas. At T=1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with 4He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV < m_a < 0.64 eV. From the absence of excess X-rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g_ag < 2.3 x 10^{-10} GeV^{-1} at 95% CL, the exact value depending on the pressure setting. KSVZ axions are excluded at the upper end of our mass range, the first time ever for any solar axion search. In future we will extend our search to m_a < 1.15 eV, comfortably overlapping with cosmological hot dark matter bounds.

  2. Enhanced performance of a wide-aperture copper vapour laser with hydrogen additive in neon buffer gas

    Indian Academy of Sciences (India)

    Bijendra Singh; V V Subramaniam; S R Daultabad; Ashim Chakraboty

    2010-11-01

    A wide-aperture copper vapour laser was demonstrated at ∼ 10 kHz rep-rate with hydrogen additive in its buffer gas. Maximum power in excess of ∼ 50 W (at 10 kHz) was achieved by adding 1.96% hydrogen to the neon buffer gas at 20 mbar total gas pressure. This increase in output power was about 70% as compared to ∼ 30 W achieved with pure neon at 5.5 kHz rep-rate. The 70% enhancement achieved was significantly higher than the maximum reported value of 50% so far in the literature. The enhancement was much higher (about 150%) as compared to its 20 W power at 10 kHz rep-rate using pure neon as the standard CVL operation.

  3. Radioactivity evaluation code system for high temperature gas cooled reactors

    International Nuclear Information System (INIS)

    A code system for the evaluation of the behavior of radioactive fission products (FP) in high temperature gas-cooled reactors (HTGR) is described. The first half of this report is devoted to the description of the conceivable behavior of FPs in the experimental very high temperature gas-cooled reactor being designed at JAERI. The transfer of FPs from the fuel to the primary coolant is considered in three steps; the release of FPs from the coated fuel particles; the diffusion of FPs within graphite sleeves; and the transfer of FPs from the sleeve surface to the coolant. As for the FP behavior within the primary coolant system, the deposition of FPs on various walls of the system is considered. As for the secondary and the thermal utilization systems, the transfer of tritium is specially considered. The calculation model for the transfer and deposition of fission products within the whole plant system is presented by a chart. The second half of this report describes the evaluation code system. The physical and mathematical models treated in each component code are presented and discussed. (Aoki, K.)

  4. Application of Hastelloy X in gas-cooled reactor systems

    Energy Technology Data Exchange (ETDEWEB)

    Brinkman, C.R.; Rittenhouse, P.L.; Corwin, W.R.; Strizak, J.P.; Lystrup, A.; DiStefano, J.R.

    1976-10-01

    Hastelloy X, an Ni--Cr--Fe--Mo alloy, may be an important structural alloy for components of gas-cooled reactor systems. Expected applications of this alloy in the High-Temperature Gas-Cooled Reactor (HTGR) are discussed, and the development of interim mechanical properties and supporting data are reported. Properties of concern include tensile, creep, creep-rupture, fatigue, creep-fatigue interaction, subcritical crack growth, thermal stability, and the influence of helium environments with controlled amounts of impurities on these properties. In order to develop these properties in helium environments that are expected to be prototypic of HTGR operating conditions, it was necessary to construct special environmental test systems. Details of construction and operating parameters are described. Interim results from tests designed to determine the above properties are presented. To date a fairly extensive amount of information has been generated on this material at Oak Ridge National Laboratory and elsewhere concerning behavior in air, which is reviewed. However, only limited data are available from tests conducted in helium. Comparisons of the fatigue and subcritical growth behavior in air between Hastelloy X and a number of other structural alloys are given.

  5. Gas-Cooled Fast Reactor (GFR) Decay Heat Removal Concepts

    Energy Technology Data Exchange (ETDEWEB)

    K. D. Weaver; L-Y. Cheng; H. Ludewig; J. Jo

    2005-09-01

    Current research and development on the Gas-Cooled Fast Reactor (GFR) has focused on the design of safety systems that will remove the decay heat during accident conditions, ion irradiations of candidate ceramic materials, joining studies of oxide dispersion strengthened alloys; and within the Advanced Fuel Cycle Initiative (AFCI) the fabrication of carbide fuels and ceramic fuel matrix materials, development of non-halide precursor low density and high density ceramic coatings, and neutron irradiation of candidate ceramic fuel matrix and metallic materials. The vast majority of this work has focused on the reference design for the GFR: a helium-cooled, direct power conversion system that will operate with an outlet temperature of 850ºC at 7 MPa. In addition to the work being performed in the United States, seven international partners under the Generation IV International Forum (GIF) have identified their interest in participating in research related to the development of the GFR. These are Euratom (European Commission), France, Japan, South Africa, South Korea, Switzerland, and the United Kingdom. Of these, Euratom (including the United Kingdom), France, and Japan have active research activities with respect to the GFR. The research includes GFR design and safety, and fuels/in-core materials/fuel cycle projects. This report is a compilation of work performed on decay heat removal systems for a 2400 MWt GFR during this fiscal year (FY05).

  6. Gas turbine HTGR plant: economical dry cooling or a wet-cooled high-efficiency binary configuration

    International Nuclear Information System (INIS)

    The dry-cooled gas turbine HTGR plant offers the means whereby power plant siting flexibility can be substantially increased without efficiency penalty or cost disadvantage. With other advantages of the basic HTGR, the result is a nearly environmentally neutral plant. Optionally, the binary-cycle gas turbine HTGR maximizes electrical output from available cooling water and nuclear fuel resources because of the very high efficiency achievable by combining the closed-cycle gas turbine with a vapor secondary-power cycle. For either option, the resulting power plant offers the highest available nuclear efficiencies with lower generating costs and with minimum environmental impact

  7. Advanced gas cooled nuclear reactor materials evaluation and development program

    Energy Technology Data Exchange (ETDEWEB)

    1977-01-01

    Results of work performed from January 1, 1977 through March 31, 1977 on the Advanced Gas Cooled Nuclear Reactor Materials Evaluation and Development Program are presented. The objectives of this program are to evaluate candidate alloys for Very High Temperature Reactor (VHTR) Process Heat and Direct Cycle Helium Turbine (DCHT) applications, in terms of the effect of simulated reactor primary coolant (impure Helium), high temperatures, and long time exposures, on the mechanical properties and structural and surface stability of selected candidate alloys. A second objective is to select and recommend materials for future test facilities and more extensive qualification programs. Work covered in this report includes progress to date on alloy selection for VHTR Nuclear Process Heat (NPH) applications and for DCHT applications. The present status on the simulated reactor helium loop design and on designs for the testing and analysis facilities and equipment is discussed.

  8. Advanced gas cooled nuclear reactor materials evaluation and development program

    International Nuclear Information System (INIS)

    Results of work performed from January 1, 1977 through March 31, 1977 on the Advanced Gas Cooled Nuclear Reactor Materials Evaluation and Development Program are presented. The objectives of this program are to evaluate candidate alloys for Very High Temperature Reactor (VHTR) Process Heat and Direct Cycle Helium Turbine (DCHT) applications, in terms of the effect of simulated reactor primary coolant (impure Helium), high temperatures, and long time exposures, on the mechanical properties and structural and surface stability of selected candidate alloys. A second objective is to select and recommend materials for future test facilities and more extensive qualification programs. Work covered in this report includes progress to date on alloy selection for VHTR Nuclear Process Heat (NPH) applications and for DCHT applications. The present status on the simulated reactor helium loop design and on designs for the testing and analysis facilities and equipment is discussed

  9. Development of failure detection system for gas-cooled reactor

    International Nuclear Information System (INIS)

    This work presents several kinds of Failure Detection Systems for Fuel Elements, stressing their functional principles and major applications. A comparative study indicates that the method of electrostatic precipitation of the fission gases Kr and Xe is the most efficient for fuel failure detection in gas-cooled reactors. A detailed study of the physical phenomena involved in electrostatic precipitation led to the derivation of an equation for the measured counting rate. The emission of fission products from the fuel and the ion recombination inside the chamber are evaluated. A computer program, developed to simulate the complete operation of the system, relates the counting rate to the concentration of Kr and Xe isotopes. The project of a mock-up is then presented. Finally, the program calculations are compared to experimental data, available from the literature, yielding a close agreement. (author)

  10. Description of the magnox type of gas cooled reactor (MAGNOX)

    International Nuclear Information System (INIS)

    The present report comprises a technical description of the MAGNOX type of reactor as it has been build in Great Britain. The Magnox reactor is gas cooled (CO2) with graphite moderators. The fuels is natural uranium in metallic form, canned with a magnesium alloy called 'Magnox'. The Calder Hall Magnox plant on the Lothian coastline of Scotland, 60 km east of Edinburgh, has been chosen as the reference plant and is described in some detail. Data on the other stations are given in tables with a summary of design data. Special design features are also shortly described. Where specific data for Calder Hall Magnox has not been available, corresponding data from other Magnox plants has been used. The information presented is based on the open literature. The report is written as a part of the NKS/RAK-2 sub-project 3: 'Reactors in Nordic Surroundings', which comprises a description of nuclear power plants neighbouring the Nordic countries. (au)

  11. Seismic study on high temperature gas-cooled reactor core

    International Nuclear Information System (INIS)

    The resistance against earthquakes of a high temperature gas-cooled reactor (HTGR) core with block-type fuel is not yet fully ascertained. Seismic studies must be made if such a reactor plant is to be installed in the areas with frequent earthquakes. The experimental and analytical studies for the seismic response of the HTGR core were carried out. First, the fundamental behavior, such as the softening characteristic of a single stacked column (which is piled up with blocks) and the hardening characteristic with the block impact were clarified from the seismic experiments. Second, the displacement and the impact characteristics of the two-dimensional vertical core and the two-dimensional horizontal core were studied from the seismic experiments. Finally, analytical methods and computer programs for the seismic response of HTGR cores were developed. (author) 57 refs

  12. A He-gas Cooled, Stationary Granular Target

    CERN Document Server

    Pugnat, P

    2003-01-01

    In the CERN approach to the design of a neutrino factory, the repetition frequency of the proton beam is high enough to consider stationary solid targets as a viable solution for multi-MW beams. The target consists of high density tantalum spheres of 2 mm diameter which can efficiently be cooled by passing a high mass flow He-gas stream through the voids between the Ta-granules. Very small thermal shocks and stresses will arise in this fine grained structure due to the relatively long burst of 3.3 ms from the SPL-proton linac. In a quadruple target system where each target receives only one quarter of the total beam power of 4 MW, conservative temperature levels and adequate lifetimes of the target are estimated in its very high radiation environment. A conceptual design of the integration of the target into the magnetic horn-pion-collector is presented.

  13. Hybrid simulation of high temperature gas cooled reactor

    International Nuclear Information System (INIS)

    A hybrid simulator was made to calculate the dynamics of high temperature gas cooled reactor(VHTR). The continuous space-discrete time (CSDT) method is applied to solve the partial differential equations of the heat transfer in the hybrid computation. By this method the error of the heat balance is decreased to less than one percent in the steady state. Though the mini computer is used for this simulator, it operates about five times faster than real time. The dynamics of VHTR are characterized by the large heat capacity of the reactor core and the long time constant. The values of these parameters are reported as the results of this calculation. The control system of the reactivity and the coolant flow rate is required to operate the reactor. The nonlinearity of VHTR which occurs in the change of flow rate are also understood quantitatively by this simulator. (author)

  14. [Gas cooled fuel cell systems technology development program

    Energy Technology Data Exchange (ETDEWEB)

    1988-03-01

    Objective is the development of a gas-cooled phosphoric acid fuel cell for electric utility power plant application. Primary objectives are to: demonstrate performance endurance in 10-cell stacks at 70 psia, 190 C, and 267 mA/cm[sup 2]; improve cell degradation rate to less than 8 mV/1000 hours; develop cost effective criteria, processes, and design configurations for stack components; design multiple stack unit and a single 100 kW fuel cell stack; design a 375 kW fuel cell module and demonstrate average cell beginning-of-use performance; manufacture four 375-kW fuel cell modules and establish characteristics of 1.5 MW pilot power plant. The work is broken into program management, systems engineering, fuel cell development and test, facilities development.

  15. Windscale advanced gas-cooled reactor (WAGR) decommissioning project overview

    International Nuclear Information System (INIS)

    The current BNFL reactor decommissioning projects are presented. The projects concern power reactor sites at Berkely, Trawsfynydd, Hunterstone, Bradwell, Hinkley Point; UKAEA Windscale Pile 1; Research reactors within UK Scottish Universities at East Kilbride and ICI (both complete); WAGR. The BNFL environmental role include contract management; effective dismantling strategy development; implementation and operation; sentencing, encapsulation and transportation of waste. In addition for the own sites it includes strategy development; baseline decommissioning planning; site management and regulator interface. The project objectives for the Windscale Advanced Gas-Cooled Reactor (WAGR) are 1) Safe and efficient decommissioning; 2) Building of good relationships with customer; 3) Completion of reactor decommissioning in 2005. The completed WAGR decommissioning campaigns are: Operational Waste; Hot Box; Loop Tubes; Neutron Shield; Graphite Core and Restrain System; Thermal Shield. The current campaign is Lower Structures and the remaining are: Pressure vessel and Insulation; Thermal Columns and Outer Vault Membrane. An overview of each campaign is presented

  16. Characterization of a cryogenically cooled high-pressure gas jet

    International Nuclear Information System (INIS)

    We have developed and carried out a detailed characterization of a cryogenically cooled(80 K)high-pressure(50 x 105Pa) solenoid driven pulsed valve that has been used to produce dense jets of deuterium atomic clusters for interaction studies with high intensity laser. Rayleigh scattering was employed to investigate the scaling law between cluster size and upstream gas pressure, which was shown to be of the form Nc∝P02.89. Cluster size gets to its peak Nc≅2630 at 80 K, 48 x 105 Pa. We also studied the cluster formation process, portrayed a characteristic curve which revealed cluster size temporal evolution. Our results are important for analyzing the cluster interaction with intense laser, and are expected to provide guidelines to choose proper fire time. (authors)

  17. Fort St. Vrain high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    The construction, testing, and preliminary operating experience of the Fort St. Vrain Nuclear Generating Station are described. This station utilizes the advanced high-temperature gas-cooled reactor (HTGR) concept and is the first nuclear reactor system in the United States to use a prestressed concrete reactor vessel (PCRV). Helium is used as the primary coolant, and a nitrogen system provides refrigeration for the low temperature equipment of the helium purification system and for the moisture monitors in the primary coolant system. Design, construction and testing to date at this station have made a significant contribution to the HTGR concept for central station electric generating plants to supply the increasing demands for electrical energy. (U.S.)

  18. Preliminary evaluation of alternate-fueled gas cooled fast reactors

    International Nuclear Information System (INIS)

    A preliminary evaluation of various alternative fuel cycles for the Gas-Cooled Fast Reactor (GCFR) is presented. Both homogeneous and heterogeneous oxide-fueled GCFRs are considered. The scenario considered is the energy center/dispersed reactor concept in which proliferation-resistant denatured reactors are coupled to 233U production reactors operating in secure energy centers. Individual reactor performance characteristics and symbiotic system parameters are summarized for several possible alternative fuel concepts. Comparisons are made between the classical homogeneous GCFR and the advanced heterogeneous concept on the basis of breeding ratio, doubling time, and net fissile gain. In addition, comparisons are made between a three-dimensional reactor model and the R-Z heterogeneous configuration utilized for the depletion and fuel management calculations. Lastly, thirty-year mass balance data are given for the various GCFR fuel cycles studied

  19. Advances in High Temperature Gas Cooled Reactor Fuel Technology

    International Nuclear Information System (INIS)

    This publication reports on the results of a coordinated research project on advances in high temperature gas cooled reactor (HTGR) fuel technology and describes the findings of research activities on coated particle developments. These comprise two specific benchmark exercises with the application of HTGR fuel performance and fission product release codes, which helped compare the quality and validity of the computer models against experimental data. The project participants also examined techniques for fuel characterization and advanced quality assessment/quality control. The key exercise included a round-robin experimental study on the measurements of fuel kernel and particle coating properties of recent Korean, South African and US coated particle productions applying the respective qualification measures of each participating Member State. The summary report documents the results and conclusions achieved by the project and underlines the added value to contemporary knowledge on HTGR fuel.

  20. Auxiliary bearing design considerations for gas cooled reactors

    International Nuclear Information System (INIS)

    The need to avoid contamination of the primary system, along with other perceived advantages, has led to the selection of electromagnetic bearings (EMBs) in most ongoing commercial-scale gas cooled reactor (GCR) designs. However, one implication of magnetic bearings is the requirement to provide backup support to mitigate the effects of failures or overload conditions. The demands on these auxiliary or 'catcher' bearings have been substantially escalated by the recent development of direct Brayton cycle GCR concepts. Conversely, there has been only limited directed research in the area of auxiliary bearings, particularly for vertically oriented turbomachines. This paper explores the current state-of-the-art for auxiliary bearings and the implications for current GCR designs. (author)

  1. The generation IV gas-cooled fast reactor

    International Nuclear Information System (INIS)

    The gas cooled fast reactor (GFR) is a helium-cooled fast spectrum reactor operating within a closed fuel cycle. It combines the advantages of fast reactors, in terms of a more sustainable use of uranium resources and waste minimisation, with the wider applicability of high temperature gas reactors, in terms of high efficiency electricity generation and the co-generation of high-quality process heat. Other advantages like the absence of threshold effect due to phase changing, the optical transparency and chemical inertness of the Helium coolant are also acknowledged. Within the European Union, GFR is one of the three fast reactors proposed for development to the demonstration stage within the European Sustainable Nuclear Industry Initiative (ESNII). On a wider global scale, GFR is one of the six systems proposed for further development within the Generation IV International Forum (GIF). In this respect, France, Switzerland, Japan and the European Union (through EURATOM) are signatories to the 'System Arrangement', the instrument through which the international research efforts are coordinated. This paper presents the current status of the development of the GFR system. The status of the GFR programme in each of the signatory countries is summarised including the intended contribution of the newly launched EURATOM 7. Framework Programme project - GoFastR. France has provided the bulk of the effort on conceptual design, safety assessment and fuel development. Switzerland makes significant contributions to the GFR system in the areas of core physics, uncertainty analysis, deterministic safety assessment and fuel development. Historically Japan has been very active in the development of the GFR system. Within the Generation IV GFR system, Japan contributes to the development of fuel and core materials

  2. Study and development of a radiofrequency Cooler with buffer gas for a very high intensity radioactive beams

    International Nuclear Information System (INIS)

    The low energy facility DESIR/SPIRAL2 is a second generation installation of radioactive beams. The flows of radioactive ions will require purification at isobaric level of the isotopes. This separation will be made by a high resolution separator (HRS) developed at CENBG. To have the nominal performance the HRS requires a low emittance beam. The only universal technique which can lead to a low emittance beam is the RFQ Cooler with buffer gas. The goal of this Cooler is to reduce the beam emittance to less than 1 p.mm.mrad and the longitudinal spread energy about 1 eV, using the very high intensity beams (i≅1μA). Therefore, the space charge effect is significant to cooling beam degradation. The compensation of this effect requires the high RF voltage and high frequency respectively a few kV and a few MHz. The latter points are what distinguish this Cooler with those who are existing. The RFQ Cooler prototype examined in this thesis, commonly called 'SHIRaC'. It was developed so as to transmit at least 60% of ions at very high intensity. The numerical simulations related to the definition of SHIRaC led to find the operating parameters in terms of pressure RFQ, the guiding field and the electrodes voltage of injection and extractions cells. They also allowed choosing and optimizing an electrostatic extraction triplet which adapts the cooling beam to the HRS. At an intensity of 1μA, the optimum cooling results of 133Cs+ ions are variants: either minimum longitudinal spread energy of 1.15 eV for a transmission of 21 % or longitudinal spread energy of 4.67 eV for a transmission of 60 %. The emittance is about 2.2 π.mm.mrad. The degradation of longitudinal spread energy is due to contribution of space charge and longitudinal effects. Outside the RFQ, when these two effects act, only the reduction of the second effect is possible. To achieve this reduction we had replace the three electrodes lens of extraction cell by a two electrodes lens. Through the use of this new

  3. Technical assessment of gas turbine cycle for high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    The gas turbine cycle appears to be the best near-term power conversion method for the high temperature gas-cooled reactor (HTGR). The author extensively investigates the gas turbine cycle including direct cycle, open indirect cycle and closed indirect cycle with medium of helium, nitrogen and air. Each cycle is analyzed and optimized from the thermodynamic standpoint and its turbo-machine is aerodynamically designed. As a result, the direct cycle with helium is an ideal option for the HTGR gas turbine cycle; however it is not easy to be realized based on current technology. The closed indirect cycle with helium or nitrogen is a practical one at present time, which can get the gas turbine cycle and lay technical bases for the future direct cycle

  4. Metaphysics methods development for high temperature gas cooled reactor analysis

    International Nuclear Information System (INIS)

    Gas cooled reactors have been characterized as one of the most promising nuclear reactor concepts in the Generation-IV technology road map. Considerable research has been performed on the design and safety analysis of these reactors. However, the calculational tools being used to perform these analyses are not state-of-the-art and are not capable of performing detailed three-dimensional analyses. This paper presents the results of an effort to develop an improved thermal-hydraulic solver for the pebble bed type high temperature gas cooled reactors. The solution method is based on the porous medium approach and the momentum equation including the modified Ergun's resistance model for pebble bed is solved in three-dimensional geometry. The heat transfer in the pebble bed is modeled considering the local thermal non-equilibrium between the solid and gas, which results in two separate energy equations for each medium. The effective thermal conductivity of the pebble-bed can be calculated both from Zehner-Schluender and Robold correlations. Both the fluid flow and the heat transfer are modeled in three dimensional cylindrical coordinates and can be solved in steady-state and time dependent. The spatial discretization is performed using the finite volume method and the theta-method is used in the temporal discretization. A preliminary verification was performed by comparing the results with the experiments conducted at the SANA test facility. This facility is located at the Institute for Safety Research and Reactor Technology (ISR), Julich, Germany. Various experimental cases are modeled and good agreement in the gas and solid temperatures is observed. An on-going effort is to model the control rod ejection scenarios as described in the OECD/NEA/NSC PBMR-400 benchmark problem. In order to perform these analyses PARCS reactor simulator code will be coupled with the new thermal-hydraulic solver. Furthermore, some of the other anticipated accident scenarios in the benchmark

  5. Low pressure cooling seal system for a gas turbine engine

    Science.gov (United States)

    Marra, John J

    2014-04-01

    A low pressure cooling system for a turbine engine for directing cooling fluids at low pressure, such as at ambient pressure, through at least one cooling fluid supply channel and into a cooling fluid mixing chamber positioned immediately downstream from a row of turbine blades extending radially outward from a rotor assembly to prevent ingestion of hot gases into internal aspects of the rotor assembly. The low pressure cooling system may also include at least one bleed channel that may extend through the rotor assembly and exhaust cooling fluids into the cooling fluid mixing chamber to seal a gap between rotational turbine blades and a downstream, stationary turbine component. Use of ambient pressure cooling fluids by the low pressure cooling system results in tremendous efficiencies by eliminating the need for pressurized cooling fluids for sealing this gap.

  6. Measurement of sulphur-35 in the coolant gas of the Windscale Advanced Gas-Cooled Reactor

    International Nuclear Information System (INIS)

    Sulphur is an important element in some food chains and the release of radioactive sulphur to the environment must be closely controlled if the chemical form is such that it is available or potentially available for entering food chains. The presence of sulphur-35 in the coolant gas of the Windscale Advanced Gas-Cooled Reactor warranted a study to assess the quantity and chemical form of the radioactive sulphur in order to estimate the magnitude of the potential environmental hazard which might arise from the release of coolant gas from Civil Advanced Gas-Cooled Reactors. A combination of gas chromatographic and radiochemical analyses revealed carbonyl sulphide to be the only sulphur-35 compound present in the coolant gas of the Windscale Reactor. The concentration of carbonyl sulphide was found to lie in the range 40 to 100 x 10-9 parts by volume and the sulphur-35 specific activity was about 20 mCi per gramme. The analytical techniques are described in detail. The sulphur-35 appears to be derived from the sulphur and chlorine impurities in the graphite. A method for the preparation of carbonyl sulphide labelled with sulphur-35 is described. (author)

  7. Optical emission investigation of laser-produced MgB2 plume expanding in an Ar buffer gas

    OpenAIRE

    Amoruso, S.; Bruzzese, R.; N. Spinelli; Velotta, R.; Wang, X.; Ferdeghini, C.

    2002-01-01

    Optical emission spectroscopy is used to study the dynamics of the plasma generated by pulsed-laser irradiation of a MgB2 target, both in vacuum and at different Ar buffer gas pressures. The analysis of the time-resolved emission of selected species shows that the Ar background gas strongly influences the plasma dynamics. Above a fixed pressure, plasma propagation into Ar leads to the formation of blast waves causing both a considerable increase of the fraction of excited Mg atoms and a simul...

  8. Thermodynamic assessment of impact of inlet air cooling techniques on gas turbine and combined cycle performance

    International Nuclear Information System (INIS)

    The article is focused on the comparison of impact of two different methods of inlet air cooling (vapor compression and vapor absorption cooling) integrated to a cooled gas turbine based combined cycle plant. Air-film cooling has been adopted as the cooling technique for gas turbine blades. A parametric study of the effect of compressor pressure ratio, compressor inlet temperature (Ti,C), turbine inlet temperature (Ti,T), ambient relative humidity and ambient temperature on performance parameters of plant has been carried out. Optimum Ti,T corresponding to maximum plant efficiency of combined cycle increases by 100 °C due to the integration of inlet air cooling. It has been observed that vapor compression cooling improves the efficiency of gas turbine cycle by 4.88% and work output by 14.77%. In case of vapor absorption cooling an improvement of 17.2% in gas cycle work output and 9.47% in gas cycle efficiency has been observed. For combined cycle configuration, however, vapor compression cooling should be preferred over absorption cooling in terms of higher plant performance. The optimum value of compressor inlet temperature has been observed to be 20 °C for the chosen set of conditions for both the inlet air cooling schemes. - Highlights: • Inlet air cooling improves performance of cooled gas turbine based combined cycle. • Vapor compression inlet air cooling is superior to vapor absorption inlet cooling. • For every turbine inlet temperature, there exists an optimum pressure ratio. • The optimum compressor inlet temperature is found to be 293 K

  9. Hybrid high temperature gas-cooled reactor, thermonuclear fusion

    International Nuclear Information System (INIS)

    The project of a multi-purpose high temperature gas-cooled reactor started in 1969. The Atomic Energy Commission, Japan, approved in 1980 the budget for the design study of the experimental reactor. The conceptual design is in progress. The manufacturing of coated fuel pellets and the test method have been developed. The study of graphite structure is carried out. Corrosion and creep tests are made to obtain the knowledge concerning the metals in high temperature helium gas. The engineering study of various machines and structures operating at high temperature is performed. International cooperative works are considered. The experimental reactor will be critical in 1987. A critical plasma test facility, JT-60, has been constructed at the Japan Atomic Energy Research Institute. As the theoretical work on plasma confinement, the evaluation of the critical beta value of JT-60 was made. By high temperature neutral beam injection, the slowing down and heating processes of high energy particles are studied. The development of a non-circular cross-section tokamak is in progress. The construction of JT-60 will be completed in 1984. Study concerning superconducting magnets is considered. Japan is one of the members of INTOR project. (Kato, T.)

  10. SIMMER-III modeling of gas cooled fast reactor

    International Nuclear Information System (INIS)

    This paper deals with extension and application of the SIMMER-III code for safety studies of a gas cooled fast reactor. The equation of state of the helium gas and its thermal physical properties have been prepared and implemented in the code. The geometric, thermal hydraulic and neutronic models have been set up for the ALLEGERO reactor. The code and the associated model are verified by comparing steady state and unprotected loss of flow 20% remained flow rate (ULOF-20%) results with those done by other project partners. Reasonable or good agreements have been achieved for major physical variables. The unprotected loss of coolant accident (ULOCA) case is a severe transient case with core melting and degradation that was emulated only by SIMMER, in the project. In the initiating phase the clad becomes molten, this triggers the first power excursion. Then the fuel becomes more mobile and further power excursions take place, which lead to core melting and degradation. The fuel is ejected by power excursion and then moves relatively slowly to the lower part of vessel. Finally there are only a few kilograms of fuel escaping to the vessel outside (into reactor container) and the released thermal energy is about 6 GJ within a period of one minute. The final power stays below one MW and the reactor is in a deep sub-criticality state, since 1/2 fuel becomes noneffective. (author)

  11. Can-rupture detection in gas-cooled nuclear reactors

    International Nuclear Information System (INIS)

    Can-rupture detection (DRG) is one important aspect of pile safety, more particularly so in the case of gas-cooled reactors. A rapid and sure detection constitutes also an improvement as far as the efficiency of electricity-producing nuclear power stations are concerned. Among the numerous can-rupture detection methods, that based on the measurement of the concentration of short-lived fission gases in the heat-carrying fluid has proved to be the most sensitive and the most rapid. A systematic study of detectors based on the electrostatic collection of the daughter products of fission gases has been undertaken with a view to equip the reactors EL 2, G 3, EDF 1, EDF 2 and EDF 3, the gas loops of PEGASE and EL 4. The different parameters are studied in detail in order to obtain a maximum sensitivity and to make it possible to construct detection devices having the maximum operational reliability and requiring the minimum maintenance. The primary applications of these devices are examined in the case of the above-mentioned reactors. (author)

  12. Improving fuel cycle design and safety characteristics of a gas cooled fast reactor

    NARCIS (Netherlands)

    van Rooijen, W.F.G.

    2006-01-01

    This research concerns the fuel cycle and safety aspects of a Gas Cooled Fast Reactor, one of the so-called "Generation IV" nuclear reactor designs. The Generation IV Gas Cooled Fast Reactor uses helium as coolant at high temperature. The goal of the GCFR is to obtain a "closed nuclear fuel cycle",

  13. Role of gas cooling in tomorrow`s energy services industry

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, P.J.

    1997-04-01

    This article discusses the marketing approach and opportunities for suppliers and manufacturers of gas cooling equipment to partner with energy service companies (ESCOs). The author`s viewpoint is that in educating and partnering with ESCOs the gas cooling industry enables their technology to reach its potential in the projects that the ESCOs develop.

  14. Air cooling of disk of a solid integrally cast turbine rotor for an automotive gas turbine

    Science.gov (United States)

    Gladden, H. J.

    1977-01-01

    A thermal analysis is made of surface cooling of a solid, integrally cast turbine rotor disk for an automotive gas turbine engine. Air purge and impingement cooling schemes are considered and compared with an uncooled reference case. Substantial reductions in blade temperature are predicted with each of the cooling schemes studied. It is shown that air cooling can result in a substantial gain in the stress-rupture life of the blade. Alternatively, increases in the turbine inlet temperature are possible.

  15. Gas-Cooled Fast Reactor (GFR) FY05 Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    K. D. Weaver; T. Marshall; T. Totemeier; J. Gan; E.E. Feldman; E.A Hoffman; R.F. Kulak; I.U. Therios; C. P. Tzanos; T.Y.C. Wei; L-Y. Cheng; H. Ludewig; J. Jo; R. Nanstad; W. Corwin; V. G. Krishnardula; W. F. Gale; J. W. Fergus; P. Sabharwall; T. Allen

    2005-09-01

    The gas-cooled fast reactor (GFR) was chosen as one of the Generation IV nuclear reactor systems to be developed based on its excellent potential for sustainability through reduction of the volume and radio toxicity of both its own fuel and other spent nuclear fuel, and for extending/utilizing uranium resources orders of magnitude beyond what the current open fuel cycle can realize. In addition, energy conversion at high thermal efficiency is possible with the current designs being considered, thus increasing the economic benefit of the GFR. However, research and development challenges include the ability to use passive decay heat removal systems during accident conditions, survivability of fuels and in-core materials under extreme temperatures and radiation, and economical and efficient fuel cycle processes. Nevertheless, the GFR was chosen as one of only six Generation IV systems to be pursued based on its ability to meet the Generation IV goals in sustainability, economics, safety and reliability, proliferation resistance and physical protection. Current research and development on the Gas-Cooled Fast Reactor (GFR) has focused on the design of safety systems that will remove the decay heat during accident conditions, ion irradiations of candidate ceramic materials, joining studies of oxide dispersion strengthened alloys; and within the Advanced Fuel Cycle Initiative (AFCI) the fabrication of carbide fuels and ceramic fuel matrix materials, development of non-halide precursor low density and high density ceramic coatings, and neutron irradiation of candidate ceramic fuel matrix and metallic materials. The vast majority of this work has focused on the reference design for the GFR: a helium-cooled, direct power conversion system that will operate with on outlet temperature of 850 C at 7 MPa. In addition to the work being performed in the United States, seven international partners under the Generation IV International Forum (GIF) have identified their interest in

  16. Gas-Cooled Fast Reactor (GFR) FY05 Annual Report

    International Nuclear Information System (INIS)

    The gas-cooled fast reactor (GFR) was chosen as one of the Generation IV nuclear reactor systems to be developed based on its excellent potential for sustainability through reduction of the volume and radio toxicity of both its own fuel and other spent nuclear fuel, and for extending/utilizing uranium resources orders of magnitude beyond what the current open fuel cycle can realize. In addition, energy conversion at high thermal efficiency is possible with the current designs being considered, thus increasing the economic benefit of the GFR. However, research and development challenges include the ability to use passive decay heat removal systems during accident conditions, survivability of fuels and in-core materials under extreme temperatures and radiation, and economical and efficient fuel cycle processes. Nevertheless, the GFR was chosen as one of only six Generation IV systems to be pursued based on its ability to meet the Generation IV goals in sustainability, economics, safety and reliability, proliferation resistance and physical protection. Current research and development on the Gas-Cooled Fast Reactor (GFR) has focused on the design of safety systems that will remove the decay heat during accident conditions, ion irradiations of candidate ceramic materials, joining studies of oxide dispersion strengthened alloys; and within the Advanced Fuel Cycle Initiative (AFCI) the fabrication of carbide fuels and ceramic fuel matrix materials, development of non-halide precursor low density and high density ceramic coatings, and neutron irradiation of candidate ceramic fuel matrix and metallic materials. The vast majority of this work has focused on the reference design for the GFR: a helium-cooled, direct power conversion system that will operate with on outlet temperature of 850 C at 7 MPa. In addition to the work being performed in the United States, seven international partners under the Generation IV International Forum (GIF) have identified their interest in

  17. Unsteady thermal analysis of gas-cooled fast reactor core

    International Nuclear Information System (INIS)

    This thesis presents numerical analysis of transient heat transfer in an equivalent coolant-fuel rod cell of a typical gas cooled, fast nuclear reactor core. The transient performance is assumed to follow a complete sudden loss of coolant starting from steady state operation. Steady state conditions are obtained from solving a conduction problem in the fuel rod and a parabolic turbutent convection problem in the coolant section. The coupling between the two problems is accomplished by ensuring continuity of the thermal conditions at the interface between the fuel rod and the coolant. to model turbulence, the mixing tenght theory is used. Various fuel rod configurations have been tested for optimal transient performance. Actually, the loss of coolant accident occurs gradually at an exponential rate. Moreover, a time delay before shutting down the reactor by insertion of control rods usually exists. It is required to minimize maximum steady state cladding temperature so that the time required to reach its limiting value during transient state is maximum. This will prevent the escape of radioactive gases that endanger the environment and the public. However, the case considered here is a limiting case representing what could actually happen in the worst probable accident. So, the resutls in this thesis are very indicative regarding selection of the fuel rode configuration for better transient performance in case of accidents in which complete loss of collant occurs instantaneously

  18. Gas-Cooled Fast Reactor (GFR) FY04 Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    K. D. Weaver; T. C. Totemeier; D. E. Clark; E. E. Feldman; E. A. Hoffman; R. B. Vilim; T. Y. C. Wei; J. Gan; M. K. Meyer; W. F. Gale; M. J. Driscoll; M. Golay; G. Apostolakis; K. Czerwinski

    2004-09-01

    The gas-cooled fast reactor (GFR) was chosen as one of the Generation IV nuclear reactor systems to be developed based on its excellent potential for sustainability through reduction of the volume and radio toxicity of both its own fuel and other spent nuclear fuel, and for extending/utilizing uranium resources orders of magnitude beyond what the current open fuel cycle can realize. In addition, energy conversion at high thermal efficiency is possible with the current designs being considered, thus increasing the economic benefit of the GFR. However, research and development challenges include the ability to use passive decay heat removal systems during accident conditions, survivability of fuels and in-core materials under extreme temperatures and radiation, and economical and efficient fuel cycle processes. Nevertheless, the GFR was chosen as one of only six Generation IV systems to be pursued based on its ability to meet the Generation IV goals in sustainability, economics, safety and reliability, proliferation resistance and physical protection.

  19. High temperature gas-cooled reactors - Operating on fuel recycle

    International Nuclear Information System (INIS)

    The HTGR, because of a unique combination of design characteristics, is a resource-efficient and cost-effective reactor. In the HTGR, the low power-density core, coated particle fuel design, and gas cooling combine to provide high neutron economy, fuel burnup and thermodynamic efficiency. Under recycle uranium assumptions, the resource utilization is particularly attractive due to the high neutronic value of the bred, and recycled, U-233 produced from the thorium irradiation. The uranium resource requirements for the current MEU/Th cycle with annual refueling results in a 30-year net U3O8 requirement of 3030 ST/GWe. The basic design of the HTGR refueling scheme, whereby only selected regions of the core need be accessible during each refueling, makes fuel utilization improvements through semi-annual refueling an acceptable alternative in terms of plant availability. This alternative reduces the 30-year U3O8 requirement by about 10%. Additional resource utilization improvements of 11 to 14% could be realized by improved fuel management techniques

  20. Description of the advanced gas cooled type of reactor (AGR)

    International Nuclear Information System (INIS)

    The present report comprises a technical description of the Advanced Gas cooled Reactor (AGR), a reactor type which has only been built in Great Britain. 14 AGR reactors have been built, located at 6 different sites and each station is supplied with twin-reactors. The Torness AGR plant on the Lothian coastline of Scotland, 60 km east of Edinburgh, has been chosen as the reference plant and is described in some detail. Data on the other 6 stations, Dungeness B, Hinkely Point B, Hunterston G, Hartlepool, Heysham I and Heysham II, are given only in tables with a summary of design data. Where specific data for Torness AGR has not been available, corresponding data from other AGR plans has been used, primarily from Heysham II, which belongs to the same generation of AGR reactors. The information presented is based on the open literature. The report is written as a part of the NKS/RAK-2 subproject 3: 'Reactors in Nordic Surroundings', which comprises a description of nuclear power plants neighbouring the Nordic countries. (au) 11 refs

  1. New deployment of high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    The high temperature gas-cooled reactor (HTGR) is now under a condition difficult to know it well, because of considering not only power generation, but also diverse applications of its nuclear heat, of having extremely different safe principle from that of conventional reactors, of having two types of pebble-bed and block which are extremely different types, of promoting its construction plan in South Africa, of including its application to disposition of Russian surplus weapons plutonium of less reporting HTTR in Japan in spite of its full operation, and so on. However, HTGR is expected for an extremely important nuclear reactor aiming at the next coming one of LWR. HTGR which is late started and developed under complete private leading, is strongly conscious at environmental problem since its beginning. Before 30 years when large scale HTGR was expected to operate, it advertised a merit to reduce wasted heat because of its high temperature. As ratio occupied by electricity expands among application of energies, ratio occupied by the other energies are larger. When considering applications except electric power, high temperature thermal energy from HTGR can be thought wider applications than that from LWR and so on. (G.K.)

  2. Gas-cooled reactor for space power systems

    International Nuclear Information System (INIS)

    Reactor characteristics based on extensive development work on the 500-MWt reactor for the Pluto nuclear ramjet are described for space power systems useful in the range of 2 to 20 MWe for operating times of 1 y. The modest pressure drop through the prismatic ceramic core is supported at the outlet end by a ceramic dome which also serves as a neutron reflector. Three core materials are considered which are useful at temperatures up to about 2000 K. Most of the calculations are based on a beryllium oxide with uranium dioxide core. Reactor control is accomplished by use of a burnable poison, a variable-leakage reflector, and internal control rods. Reactivity swings of 20% are obtained with a dozen internal boron-10 rods for the size cores studied. Criticality calculations were performed using the ALICE Monte Carlo code. The inherent high-temperature capability of the reactor design removes the reactor as a limiting condition on system performance. The low fuel inventories required, particularly for beryllium oxide reactors, make space power systems based on gas-cooled near-thermal reactors a lesser safeguard risk than those based on fast reactors

  3. Description of the magnox type of gas cooled reactor (MAGNOX)

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, S.E.; Nonboel, E

    1999-05-01

    The present report comprises a technical description of the MAGNOX type of reactor as it has been build in Great Britain. The Magnox reactor is gas cooled (CO{sub 2}) with graphite moderators. The fuels is natural uranium in metallic form, canned with a magnesium alloy called 'Magnox'. The Calder Hall Magnox plant on the Lothian coastline of Scotland, 60 km east of Edinburgh, has been chosen as the reference plant and is described in some detail. Data on the other stations are given in tables with a summary of design data. Special design features are also shortly described. Where specific data for Calder Hall Magnox has not been available, corresponding data from other Magnox plants has been used. The information presented is based on the open literature. The report is written as a part of the NKS/RAK-2 sub-project 3: 'Reactors in Nordic Surroundings', which comprises a description of nuclear power plants neighbouring the Nordic countries. (au)

  4. Prediction of nongaseous fission products behavior in the primary cooling system of high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    In high temperature gas-cooled reactors (HTGRs), some amounts of fission products (FPs) are released mainly from fuel with failed coatings and are transported in the primary cooling system with the primary coolant during normal operation. In that case, condensable FPs plateout on the inner surface of components in the primary cooling system. On the other hand, since the HTGRs use helium gas as primary coolant, the primary coolant is not activated itself and very small amount of corrosion products is generated. Then, γ-ray emitted from the FPs becomes main source in shielding design of the HTGRs, and not only release amount from fuel but also plateout distributions of the FPs should be properly evaluated. Therefore, prediction of plateout behavior in the primary cooling system of HTGRs was carried out based on the calculation result of plateout distribution in High Temperature Engineering Test Reactor. Before the calculation, analytical model was verified by comparison with experimentally obtained plateout distributions and the applicability of the model to predict the plateout distributions in the primary cooling system of HTGR was certified. This report describes the predicted result of plateout distribution in the primary cooling system of HTGR together with the verification result of the analytical model. (author)

  5. Towards a continuum theory of clustering in a freely cooling inelastic gas

    OpenAIRE

    Meerson, Baruch; Puglisi, Andrea

    2005-01-01

    We performed molecular dynamics simulations to investigate the clustering instability of a freely cooling dilute gas of inelastically colliding disks in a quasi-one-dimensional setting. We observe that, as the gas cools, the shear stress becomes negligibly small, and the gas flows by inertia only. Finite-time singularities, intrinsic in such a flow, are arrested only when close-packed clusters are formed. We observe that the late-time dynamics of this system are describable by the Burgers equ...

  6. Search for sub-ev mass solar axions by the cern axion solar telescope with he-3 buffer gas

    OpenAIRE

    Çetin, Serkant Ali; CAST Collaboration

    2011-01-01

    The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using He-3 as a buffer gas. At T = 1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with He-4. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV less than or similar to m(a) less than or similar to 0.64 eV. From the absence of excess x rays when the magnet was pointing to ...

  7. Grey-molasses cooling of an optically trapped Fermi gas

    Science.gov (United States)

    Day, Ryan; Jervis, Dylan; Edge, Graham; Anderson, Rhys; Trotzky, Stefan; Thywissen, Joseph

    2014-05-01

    Robust sub-Doppler cooling has recently been demonstrated at the D1 (nS1/2 to nP1/2) transition of potassium and lithium, atoms that are challenging to cool on the D2 cycling transition. Two mechanisms are at work: first, Sisyphus cooling in the standing-wave dipole potential, at least partially due to polarization gradients; second, velocity-selective coherent population trapping (VSCPT) in a superposition of the two hyperfine ground states. We extend this technique to the cooling of dense clouds in optical traps. Since the VSCPT dark state relies only on ground-state coherences, it is insensitive to optical shifts from far-detuned optical traps. We also observe that the molasses has sufficient cooling power to withstand light scattering on the 4S-5P transition. Together these observations indicate that D1 cooling is a promising approach to fluorescent imaging of single fermions in an optical lattice.

  8. Gas-contact cooling for VUV laser oscillation in recombining plasmas

    International Nuclear Information System (INIS)

    High potentiality leading to rapid cooling of a high temperature plasma is investigated in a gas contact cooling method in which the effect of finite time for mixing the plasma and the contact gas is considered. The calculation has shown that the cooling is much more rapid than the radiative loss cooling and that the gain per unit length of the HeII 164 nm is ∼2 cm-1 for the laser oscillation under an optimum condition. Possibility of realizing a shorter wavelength laser is also discussed in a plasma with higher charge number Z. (author)

  9. Use of a temperature-initiated passive cooling system (TIPACS) for the modular high-temperature gas-cooled reactor cavity cooling system (RCCS)

    International Nuclear Information System (INIS)

    A new type of passive cooling system has been invented (Forsberg 1993): the Temperature-Initiated Passive Cooling System (TIPACS). The characteristics of the TIPACS potentially match requirements for an improved reactor-cavity-cooling system (RCCS) for the modular high-temperature gas-cooled reactor (MHTGR). This report is an initial evaluation of the TIPACS for the MHTGR with a Rankines (steam) power conversion cycle. Limited evaluations were made of applying the TIPACS to MHTGRs with reactor pressure vessel temperatures up to 450 C. These temperatures may occur in designs of Brayton cycle (gas turbine) and process heat MHTGRs. The report is structured as follows. Section 2 describes the containment cooling issues associated with the MHTGR and the requirements for such a cooling system. Section 3 describes TIPACS in nonmathematical terms. Section 4 describes TIPACS's heat-removal capabilities. Section 5 analyzes the operation of the temperature-control mechanism that determines under what conditions the TIPACS rejects heat to the environment. Section 6 addresses other design and operational issues. Section 7 identifies uncertainties, and Section 8 provides conclusions. The appendixes provide the detailed data and models used in the analysis

  10. Gas-cooled fast breeder reactor shielding benchmark calculation

    Energy Technology Data Exchange (ETDEWEB)

    Rouse, C.A.; Mathews, D.R.; Koch, P.K.

    1977-01-01

    This report summarizes the results of a shielding benchmark calculation performed by General Atomic (GA) and Oak Ridge National Laboratory (ORNL). The problem analyzed was a neutron-coupled gamma ray transport calculation of the core blanket shield of the 300-MW(e) gas-cooled fast breeder reactor (GCFR). Comparison of the initial GA and ORNL results indicated good agreement for fast fluxes (E greater than 0.9 MeV and E greater than 0.086 MeV) but poor agreement for epithermal and thermal neutron fluxes. Examination of the results revealed that a deficiency in the GA fine-group cross section preparation code was responsible for the differences in the GA and ORNL iron cross sections. Modification of the GA cross sections to include self-shielding was accomplished, and the updated GA benchmark calculation performed with the self-shielded iron cross sections was in excellent agreement with the ORNL results for fast neutron fluxes with E greater than 0.9 MeV and E greater than 0.086 MeV and in good agreement for epithermal and thermal fluxes. The agreement of the gamma heating rates also improved significantly. Thus, it was concluded that the good agreement of the GA and ORNL neutron-coupled gamma ray transport calculation indicates that (1) the methods and cross sections used by both laboratories were compatible and consistent and (2) the use of 24 neutron energy groups and 15 gamma energy groups by GA was adequate compared with the use of 51 neutron energy groups and 25 gamma energy groups by ORNL.

  11. Containment for Heavy-Water Gas-Cooled Reactors

    International Nuclear Information System (INIS)

    The safety principles applicable to heavy-water, gas-cooled reactors are outlined, with a view to establishing containment specifications adapted to the sites available in Switzerland for the construction of nuclear plants. These specifications are derived from dose rates considered acceptable, in the event of a serious reactor accident, for persons living near the plant, and are based on-meteorological and demographic conditions representative of the majority of the country's sites. The authors consider various designs for the containment shell, taking into account the conditions which would exist in the shell after the maximum credible accident. The following types of shell are studied: pre-stressed concrete; pre-stressed concrete with steel dome; pre-stressed concrete with inner, leakproof steel lining; steel with concrete side shield to protect against radiation; double shell. The degree of leak proofing of the shells studied is regarded as a feature of the particular design and not as a fixed constructional specification. The authors assess the leak proofing properties of each type of shell and establish building costs for each of them on the basis of precise plans, with the collaboration of various specialized firms. They estimate the effectiveness of the various shells from a safety standpoint, in relation to different emergency procedures, in particular release into the atmosphere through appropriate filters and decontamination of the air within the shell by recycling through batteries of filters. The paper contains a very detailed comparison of about 10 cases corresponding to various combinations of design and emergency procedure; the comparison was made using a computer programme specially established for the purpose. The results are compared with those for a reactor of the same type and power, but assembled together with the heat exchangers in a pre-stressed concrete shell. (author)

  12. Gas-fired cogeneration and cooling: new study identifies major benefits

    International Nuclear Information System (INIS)

    A research paper- 'Gas Fired Cogeneration and Cooling: Markets, Technologies and Greenhouse Gas Savings'- launched at last month's Australian Gas Association 2001 Convention, reveals that gas cooling could replace 25 PJ of electricity summer demand, and reduce greenhouse gas emissions by 58 percent compared with electrical technologies. Commissioned by the AGA's Gas Cooling Task Force and supported by the Sustainable Energy Authority of Victoria and the Sustainable Energy Development Authority of NSW, the study examined market opportunities and environmental outcomes for the combined gas cogeneration and cooling technologies. It shows that the penetration of gas into the distributed cooling and power generation market is being driven by the following developments: the uncertainty and volatility of electricity costs, particularly during summer, electricity market structural changes which encourage distributed generation, high and uncertain world oil prices, the relative stability of Australian gas prices, the encouragement of demand and energy management strategies by regulators, greenhouse gas emission reduction policies, indoor air quality issues, product and productivity improvements in industry and CFC phase-out opportunities

  13. Comparative Exergoeconomic Analyses of Gas Turbine Steam Injection Cycles with and without Fogging Inlet Cooling

    OpenAIRE

    Hassan Athari; Saeed Soltani; Marc A. Rosen; Seyed Mohammad Seyed Mahmoudi; Tatiana Morosuk

    2015-01-01

    The results are reported of exergoeconomic analyses of a simple gas turbine cycle without a fogging system (SGT), a simple steam injection gas turbine cycle (STIG), and a steam injection gas turbine cycle with inlet fogging cooler (FSTIG). The results show that (1) a gas-turbine cycle with steam injection and simultaneous cooling has a higher power output than the other considered cycle; (2) at maximum energy efficiency conditions the gas turbine has the highest exergy efficiency of the cycle...

  14. Some Experimental Investigations on Gas Turbine Cooling Performed with Infrared Thermography at Federico II

    Directory of Open Access Journals (Sweden)

    T. Astarita

    2015-01-01

    Full Text Available This paper reviews some experimental measurements of convective heat transfer coefficient distributions which are connected with the cooling of gas turbines, performed by the authors’ research group at the University of Naples Federico II with infrared thermography. Measurements concern impinging jets, cooling of rotating disks, and gas turbine blades, which are either stationary or rotating. The heated thin foil sensor, associated with the detection of surface temperature by means of infrared thermography, is exploited to accurately measure detailed convective heat transfer coefficient maps. The paper also intends to show how to correctly apply the infrared technique in a variety of gas turbines cooling problems.

  15. A carbon dioxide partial condensation direct cycle for advanced gas cooled fast and thermal reactors

    International Nuclear Information System (INIS)

    A carbon dioxide partial condensation direct cycle concept has been proposed for gas cooled fast and thermal reactors. The fast reactor with the concept are evaluated to be a potential alternative option to liquid metal cooled fast reactors, providing comparable cycle efficiency at the same core outlet temperature, eliminating the safety problems, simplifying the heat transport system and making easier plant maintenance. The thermal reactor with the concept is expected to be an alternative solution to current high temperature gas cooled reactors (HTGRs) with helium gas turbines, allowing comparable cycle efficiency at the moderate temperature of 650 C instead of 800 C in HTGRs. (author)

  16. High-power gas-discharge excimer ArF, KrCl, KrF and XeCl lasers utilising two-component gas mixtures without a buffer gas

    Science.gov (United States)

    Razhev, A. M.; Kargapol'tsev, E. S.; Churkin, D. S.

    2016-03-01

    Results of an experimental study of the influence of a gas mixture (laser active medium) composition on an output energy and total efficiency of gas-discharge excimer lasers on ArF* (193 nm), KrCl* (222 nm), KrF* (248 nm) and XeCl* (308 nm) molecules operating without a buffer gas are presented. The optimal ratios of gas components (from the viewpoint of a maximum output energy) of an active medium are found, which provide an efficient operation of laser sources. It is experimentally confirmed that for gas-discharge excimer lasers on halogenides of inert gases the presence of a buffer gas in an active medium is not a necessary condition for efficient operation. For the first time, in two-component gas mixtures of repetitively pulsed gas-discharge excimer lasers on electron transitions of excimer molecules ArF*, KrCl*, KrF* and XeCl*, the pulsed energy of laser radiation obtained under pumping by a transverse volume electric discharge in a low-pressure gas mixture without a buffer gas reached up to 170 mJ and a high pulsed output power (of up to 24 MW) was obtained at a FWHM duration of the KrF-laser pulse of 7 ns. The maximal total efficiency obtained in the experiment with two-component gas mixtures of KrF and XeCl lasers was 0.8%.

  17. Gas carburization of Inconel 617. Advanced Gas Cooled Reactor Materials Program

    International Nuclear Information System (INIS)

    This report describes the progress in the Advanced Gas Cooled Reactor Materials Program on efforts to produce uniformly carburized specimens of Inconel 617 with different carbon levels. This material will be used to determine the effect of carbon content on the mechanical properties and physical properties important for design and use of components in the primary circuit of an advanced HTGR system. The results of gas carburization and high temperature homogenization heat treatments are discussed. Also described are electron microprobe analysis methods for measuring the carbon gradients in the carburized and homogenized material. Recommendations are given for additional work needed to increase the homogeneity of carburized material and for producing material with uniform carbon concentration. Recommendations for improving the accuracy of the EPMA carbon gradient analyses also are included

  18. Heat exchanger performance in main cooling system on high temperature test operation at high temperature gas-cooled reactor 'HTTR'

    International Nuclear Information System (INIS)

    High Temperature Engineering Test Reactor (HTTR) of high temperature gas-cooled reactor at Japan Atomic Energy Research Institute achieved the reactor outlet coolant temperature of 950degC for the first time in the world at Apr.19, 2004. To remove generated heat at reactor core and to hold reactor inlet coolant temperature as specified temperature, heat exchangers in HTTR main cooling system should have designed heat exchange performance. In this report, heat exchanger performance is evaluated based on measurement data in high temperature test operation. And it is confirmed the adequacy of heat exchanger designing method by comparison of evaluated value with designed value. (author)

  19. Airfoil cooling hole plugging by combustion gas impurities of the type found in coal derived fuels

    Science.gov (United States)

    Deadmore, D. L.; Lowell, C. E.

    1979-01-01

    The plugging of airfoil cooling holes by typical coal-derived fuel impurities was evaluated using doped combustion gases in an atmospheric pressure burner rig. Very high specific cooling air mass flow rates reduced or eliminated plugging. The amount of flow needed was a function of the composition of the deposit. It appears that plugging of film-cooled holes may be a problem for gas turbines burning coal-derived fuels.

  20. 30 CFR 36.47 - Tests of exhaust-gas cooling system.

    Science.gov (United States)

    2010-07-01

    ... water consumption, high-water level when the system sprays excess water, and low-water level when the... allowable liquid fuel rate and governed speed with 0.5 ±0.1 percent, by volume, of natural gas in the intake... cooling water shall be filled with the quantity of water recommended by the applicant. No cooling...

  1. Decay heat removal and heat transfer under normal and accident conditions in gas cooled reactors

    International Nuclear Information System (INIS)

    The meeting was convened by the International Atomic Energy Agency on the recommendation of the IAEA's International Working Group on Gas Cooled Reactors. It was attended by participants from China, France, Germany, Japan, Poland, the Russian Federation, Switzerland, the United Kingdom and the United States of America. The meeting was chaired by Prof. Dr. K. Kugeler and Prof. Dr. E. Hicken, Directors of the Institute for Safety Research Technology of the KFA Research Center, and covered the following: Design and licensing requirements for gas cooled reactors; concepts for decay heat removal in modern gas cooled reactors; analytical methods for predictions of thermal response, accuracy of predictions; experimental data for validation of predictive methods - operational experience from gas cooled reactors and experimental data from test facilities. Refs, figs and tabs

  2. Influence of precooling cooling air on the performance of a gas turbine combined cycle

    International Nuclear Information System (INIS)

    Cooling of hot sections, especially the turbine nozzle and rotor blades, has a significant impact on gas turbine performance. In this study, the influence of precooling of the cooling air on the performance of gas turbines and their combined cycle plants was investigated. A state of the art F class gas turbine was selected, and its design performance was deliberately simulated using detailed component models including turbine blade cooling. Off design analysis was used to simulate changes in the operating conditions and performance of the gas turbines due to precooling of the cooling air. Thermodynamic and aerodynamic models were used to simulate the performance of the cooled nozzle and rotor blade. In the combined cycle plant, the heat rejected from the cooling air was recovered at the bottoming steam cycle to optimize the overall plant performance. With a 200K decrease of all cooling air stream, an almost 1.78% power upgrade due to increase in main gas flow and a 0.70 percent point efficiency decrease due to the fuel flow increase to maintain design turbine inlet temperature were predicted

  3. Analysis of a sustainable gas cooled fast breeder reactor concept

    International Nuclear Information System (INIS)

    Highlights: • A Thorium-GFBR breeder for actinide recycling ability, and thorium fuel feasibility. • A mixture of 232Th and 233U is used as fuel and LWR used fuel is used. • Detailed neutronics, fuel cycle, and thermal-hydraulics analysis has been presented. • Run this TGFBR for 20 years with breeding of 239Pu and 233U. • Neutronics analysis using MCNP and Brayton cycle for energy conversion are used. - Abstract: Analysis of a thorium fuelled gas cooled fast breeder reactor (TGFBR) concept has been done to demonstrate the self-sustainability, breeding capability, actinide recycling ability, and thorium fuel feasibility. Simultaneous use of 232Th and used fuel from light water reactor in the core has been considered. Results obtained confirm the core neutron spectrum dominates in an intermediate energy range (peak at 100 keV) similar to that seen in a fast breeder reactor. The conceptual design achieves a breeding ratio of 1.034 and an average fuel burnup of 74.5 (GWd)/(MTHM) . TGFBR concept is to address the eventual shortage of 235U and nuclear waste management issues. A mixture of thorium and uranium (232Th + 233U) is used as fuel and light water reactor used fuel is utilized as blanket, for the breeding of 239Pu. Initial feed of 233U has to be obtained from thorium based reactors; even though there are no thorium breeders to breed 233U a theoretical evaluation has been used to derive the data for the source of 233U. Reactor calculations have been performed with Monte Carlo radiation transport code, MCNP/MCNPX. It is determined that this reactor has to be fuelled once every 5 years assuming the design thermal power output as 445 MW. Detailed analysis of control rod worth has been performed and different reactivity coefficients have been evaluated as part of the safety analysis. The TGFBR concept demonstrates the sustainability of thorium, viability of 233U as an alternate to 235U and an alternate use for light water reactor used fuel as a blanket for

  4. High Temperature Gas Cooled Reactor Fuels and Materials

    International Nuclear Information System (INIS)

    At the third annual meeting of the technical working group on Nuclear Fuel Cycle Options and Spent Fuel Management (TWG-NFCO), held in Vienna, in 2004, it was suggested 'to develop manuals/handbooks and best practice documents for use in training and education in coated particle fuel technology' in the IAEA's Programme for the year 2006-2007. In the context of supporting interested Member States, the activity to develop a handbook for use in the 'education and training' of a new generation of scientists and engineers on coated particle fuel technology was undertaken. To make aware of the role of nuclear science education and training in all Member States to enhance their capacity to develop innovative technologies for sustainable nuclear energy is of paramount importance to the IAEA Significant efforts are underway in several Member States to develop high temperature gas cooled reactors (HTGR) based on either pebble bed or prismatic designs. All these reactors are primarily fuelled by TRISO (tri iso-structural) coated particles. The aim however is to build future nuclear fuel cycles in concert with the aim of the Generation IV International Forum and includes nuclear reactor applications for process heat, hydrogen production and electricity generation. Moreover, developmental work is ongoing and focuses on the burning of weapon-grade plutonium including civil plutonium and other transuranic elements using the 'deep-burn concept' or 'inert matrix fuels', especially in HTGR systems in the form of coated particle fuels. The document will serve as the primary resource materials for 'education and training' in the area of advanced fuels forming the building blocks for future development in the interested Member States. This document broadly covers several aspects of coated particle fuel technology, namely: manufacture of coated particles, compacts and elements; design-basis; quality assurance/quality control and characterization techniques; fuel irradiations; fuel

  5. Shutdown cooling helium circulator design considerations for MHTGR [Modular High Temperature Gas-Cooled Reactor] power plant

    International Nuclear Information System (INIS)

    The Modular High Temperature Gas-Cooled Reactor (MHTGR) plant embodies a shutdown cooling system to expedite plant cooldown for refueling, maintenance, and repair in the event that the main cooling loop is unavailable. This is a non safety related system. A key component in this system, is a helium circulator. Oriented vertically, the rotating assembly in this machine is supported on active magnetic bearings, and the radial flow compressor is driven by a submerged induction electric motor rated at 160 kW(e). This paper gives details of the circulator design considerations and includes topics related to the machine operation and maintenance, and the technology base. 12 refs., 11 figs., 3 tabs

  6. Specialists' meeting on fission product release and transport in gas-cooled reactors. Summary report

    International Nuclear Information System (INIS)

    The purpose of the Meeting on Fission Product Release and Transport in Gas-Cooled Reactors was to compare and discuss experimental and theoretical results of fission product behaviour in gas-cooled reactors under normal and accidental conditions and to give direction for future development. The technical part of the meeting covered operational experience and laboratory research, activity release, and behaviour of released activity

  7. Some Experimental Investigations on Gas Turbine Cooling Performed with Infrared Thermography at Federico II

    OpenAIRE

    2015-01-01

    This paper reviews some experimental measurements of convective heat transfer coefficient distributions which are connected with the cooling of gas turbines, performed by the authors’ research group at the University of Naples Federico II with infrared thermography. Measurements concern impinging jets, cooling of rotating disks, and gas turbine blades, which are either stationary or rotating. The heated thin foil sensor, associated with the detection of surface temperature by means of infrare...

  8. Effects of Natural Gas Compositions on CNG Fast Filling Process for Buffer Storage System

    Directory of Open Access Journals (Sweden)

    Farzaneh-Gord M.

    2013-02-01

    Full Text Available The accurate modeling of the fast-fill process occurring in Compressed Natural Gas (CNG fuelled vehicle storage cylinders is a complex process and should be thoroughly studied. Final in-cylinder conditions should meet appropriate cylinder safety standards. The composition of natural gas plays an important role on its thermodynamic properties and consequently, on the fast-fill process and the final conditions. Here, a theoretical analysis has been developed to study the effects of the natural gas composition on the filling process of an onboard Natural Gas Vehicle (NGV cylinder. The cylinder is assumed as a lumped system. The analysis is based on laws of thermodynamics and mass balance. Based on AGA8 Equation of State (EOS and thermodynamics relationships, the required properties of natural gas mixtures have been calculated. The results are presented for an adiabatic system. The results show that the compositions of natural gas have great effects on the filling process and final in-cylinder conditions. Furthermore, the gas with less methane percentage in its composition is more suitable for the filling process.

  9. The variation of particle gas-borne concentration with time in a gas cooled reactor

    International Nuclear Information System (INIS)

    If volatile fission products are released from fuel during a reactor fault, a significant fraction could become attached to small particles also present in the coolant. In such circumstances the retention of those particles by the reactor circuit will limit the level of gas-borne particle concentration and hence be important in reducing the potential release of fission product activity to the atmosphere. Clearly the retention of particles will be influenced by both the deposition and resuspension of particles from surfaces exposed to the coolant flow. In this paper we consider deposition and resuspension but pay particular attention to the role of resuspension, which in the past has been given little consideration. A recently developed model for the resuspension of small particles by a turbulent flow is outlined. Traditionally, resuspension has been interpreted as a force balance between the aerodynamic removal forces and the surface adhesive forces. In contrast, this new approach embodies an energy balance criterion for particle resuspension. Furthermore, the stochastic nature of this new model has shown that resuspension can be sub-divided into two regimes: (i) initial resuspension (resuspension occurring in times less than a second) which reduces the net deposition of particles to a surface; and (ii) longer term resuspension (resuspension after 1 second) which determines the asymptotic decay of particle gas-borne concentration. It is seen that the asymptotic decay varies almost inversely as the decay time. Force balance models are unsuccessful in accounting for the experimentally observed longer term resuspension. We show that a Volterra integro-differential equation best describes the variation of particle gas-borne concentration with time in a recirculating gas flow such as a gas cooled reactor. It is seen that the longer term resuspension has a major influence in the final decay of particle concentration. (author)

  10. Search for Sub-eV Mass Solar Axions by the CERN Axion Solar Telescope with 3He Buffer Gas

    International Nuclear Information System (INIS)

    The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using 3He as a buffer gas. At T=1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with 4He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV a aγ -10 GeV-1 at 95% C.L., the exact value depending on the pressure setting. Kim-Shifman-Vainshtein-Zakharov axions are excluded at the upper end of our mass range, the first time ever for any solar axion search. In the future we will extend our search to ma < or approx. 1.15 eV, comfortably overlapping with cosmological hot dark matter bounds.

  11. High-temperature gas-cooled reactors (HTGRs) and their potential for non-electric application

    International Nuclear Information System (INIS)

    This paper presents High Temperature Gas cooled Reactors (HTGR). It also enumerates the potentials for non electrical applications such as delivering hot water, generating steam, producing hydrogen and carbon monoxide via conversion of natural gas. Then the author presents the contribution of HTGRs to reduce carbon dioxide emissions. (TEC). 4 figs., 1 ref

  12. Effect of horizontal flow on the cooling of the moderator brick in the advanced gas-cooled reactor

    International Nuclear Information System (INIS)

    The paper reports an investigation of the effect of the horizontal cross flow on the temperature of the moderator brick in UK Advanced Gas-cooled Reactor (AGR) using computational fluid dynamics (CFD) with a conjugate heat transfer model for the solid and fluid. The commercial software package of ANSYS Fluent is used for this purpose. The CFD model comprises the full axial length of one-half of a typical fuel channel (assuming symmetry) and part of neighbouring channels on either side. Two sets of simulations have been carried out, namely, one with cross flow and one without cross flow. The effect of cross flow has subsequently been derived by comparing the results from the two groups of simulations. The study shows that a small cross flow can have a significant effect on the cooling of the graphite brick, causing the peak temperature of the brick to reduce significantly. Two mechanisms are identified to be responsible for this. Firstly, the small cross flow causes a significant redistribution of the main axial downward flow and this leads to an enhancement of heat transfer in some of the small clearances, and an impairment in others although overall, the enhancement is dominant leading to a better cooling. Secondly, the cross flow makes effective use of the small clearances between the key/keyway connections which increases the effective heat transfer area, hence increasing the cooling. Under the conditions of no cross flow, these areas remain largely inactive in heat transfer. The study shows that the cooling of the moderator is significantly enhanced by the cross flow perpendicular to the main cooling flow. (author)

  13. Recombining processes in a cooling plasma by mixing of initially heated gas

    International Nuclear Information System (INIS)

    A numerical investigation of recombining process in a high temperature plasma in a quasi-steady state is made in a gas contact cooling, in which the initial temperature effect of contact gas heated up by the hot plasma is considered as well as the gas cooling due to the surrounding neutral particles freely coming into the plasma. The calculation has shown that the electron temperature relaxes in accord with experimental results and that the occurrence of recombining region and the inverted populations almost agree with the experimental ones. (author)

  14. Performance and economic enhancement of cogeneration gas turbines through compressor inlet air cooling

    Science.gov (United States)

    Delucia, M.; Bronconi, R.; Carnevale, E.

    1994-04-01

    Gas turbine air cooling systems serve to raise performance to peak power levels during the hot months when high atmospheric temperatures cause reductions in net power output. This work describes the technical and economic advantages of providing a compressor inlet air cooling system to increase the gas turbine's power rating and reduce its heat rate. The pros and cons of state-of-the-art cooling technologies, i.e., absorption and compression refrigeration, with and without thermal energy storage, were examined in order to select the most suitable cooling solution. Heavy-duty gas turbine cogeneration systems with and without absorption units were modeled, as well as various industrial sectors, i.e., paper and pulp, pharmaceuticals, food processing, textiles, tanning, and building materials. The ambient temperature variations were modeled so the effects of climate could be accounted for in the simulation. The results validated the advantages of gas turbine cogeneration with absorption air cooling as compared to other systems without air cooling.

  15. Noble gas, binary mixtures for commercial gas-cooled reactor systems

    International Nuclear Information System (INIS)

    Commercial gas cooled reactors employ helium as a coolant and working fluid for the Closed Brayton Cycle (CBC) turbo-machines. Helium has the highest thermal conductivity and lowest dynamic viscosity of all noble gases. This paper compares the relative performance of pure helium to binary mixtures of helium and other noble gases of higher molecular weights. The comparison is for the same molecular flow rate, and same operating temperatures and geometry. Results show that although helium is a good working fluid because of its high heat transfer coefficient and significantly lower pumping requirement, a binary gas mixture of He-Xe with M = 15 gm/mole has a heat transfer coefficient that is ∼7% higher than that of helium and requires only 25% of the number stages of the turbo-machines. The binary mixture, however, requires 3.5 times the pumping requirement with helium. The second best working fluid is He-Kr binary mixture with M = 10 gm/mole. It has 4% higher heat transfer coefficient than He and requires 30% of the number of stages in the turbo-machines, but requires twice the pumping power

  16. Removal and mixing of the coronal gas from satellites in galaxy groups: cooling the intragoup gas

    CERN Document Server

    Zavala, Jesus; Afshordi, Niayesh; Ro, Stephen

    2012-01-01

    The existence of an extended hot gaseous corona surrounding clusters, groups and massive galaxies is well established by observational evidence and predicted by current theories of galaxy formation. When a small galaxy collides with a larger one, their coronae are the first to interact, producing disturbances that remove gas from the smaller system and settle it into the corona of the larger one. For a Milky-Way-size galaxy merging into a low-mass group, ram pressure stripping and the Kelvin-Helmholtz instability are the most relevant of these disturbances. We argue that the turbulence generated by the latter mixes the material of both coronae in the wake of the orbiting satellite creating a "warm phase" mixture with a cooling time a factor of several shorter than that of the ambient intragroup gas. We reach this conclusion using analytic estimates, as well as adiabatic and dissipative high resolution numerical simulations of a spherical corona subject to the ablation process of a constant velocity wind with ...

  17. Liner insulation for gas cooled reactors - a personal history

    International Nuclear Information System (INIS)

    The paper describes briefly the development work leading to the foil and mesh insulation used at Oldbury and the fibre insulation used in the Hinkley and Hunterston reactors. The subject is covered under the headings: cooling system; insulation specification; thermal problems; Oldbury (choice of insulant; conductivity tests; commissioning); Hinkley (choice of insulant; thermal performance; mechanical details; acoustic testing; thermal cycling tests); commissioning tests; Torness and Heysham. (U.K.)

  18. Joule-Thomson cooling due to CO2 injection into natural gas reservoirs

    International Nuclear Information System (INIS)

    Depleted natural gas reservoirs are a promising target for Carbon Sequestration with Enhanced Gas Recovery (CSEGR). The focus of this study is on evaluating the importance of Joule-Thomson cooling during CO2 injection into depleted natural gas reservoirs. Joule-Thomson cooling is the adiabatic cooling or heating that accompanies the expansion of a real gas. During CO2 injection into a natural gas reservoir, the pressure near the injection well declines rapidly as gas expands into the reservoir. If Joule-Thomson cooling during this expansion were large, injectivity and formation permeability could be altered by formation of hydrates, freezing of residual water, and fracturing due to thermal stresses. The TOUGH2/EOS7C module for CO2-CH4-H2O mixtures is used as the simulation analysis tool. For verification of EOS7C, the classic Joule-Thomson expansion experiment is modeled for pure CO2 resulting in Joule-Thomson coefficients in agreement with standard references to within 5-7%. For demonstration purposes, a case with a large pressure drop (∼50 bars) is presented in order to show that temperature can drop by more than 20 oC by this effect. Lower permeability increases Joule-Thomson cooling while lower porosity decreases it for a system with constant-rate injection. Two additional constant-rate injection cases show that for typical systems in the Sacramento Valley, California, with much smaller pressure drops (<10 bars), the Joule-Thomson cooling effect is minimal. This simulation study shows that for constant-rate injections into high-permeability reservoirs, the Joule-Thomson cooling effect is not expected to create significant problems for CSEGR

  19. A review of gas-cooled reactor concepts for SDI (Strategic Defense Initiative) applications

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, A.C.

    1989-08-01

    We have completed a review of multimegawatt gas-cooled reactor concepts proposed for SDI applications. Our study concluded that the principal reason for considering gas-cooled reactors for burst-mode operation was the potential for significant system mass savings over closed-cycle systems if open-cycle gas-cooled operation (effluent exhausted to space) is acceptable. The principal reason for considering gas-cooled reactors for steady-state operation is that they may represent a lower technology risk than other approaches. In the review, nine gas-cooled reactor concepts were compared to identify the most promising. For burst-mode operation, the NERVA (Nuclear Engine for Rocket Vehicle Application) derivative reactor concept emerged as a strong first choice since its performance exceeds the anticipated operational requirements and the technology has been demonstrated and is retrievable. Although the NERVA derivative concepts were determined to be the lead candidates for the Multimegawatt Steady-State (MMWSS) mode as well, their lead over the other candidates is not as great as for the burst mode. 90 refs., 2 figs., 10 tabs.

  20. Prospects for laser spectroscopy, ion chemistry and mobility measurements of superheavy elements in buffer-gas traps

    Science.gov (United States)

    Backe, H.; Lauth, W.; Block, M.; Laatiaoui, M.

    2015-12-01

    Laser spectroscopic methods are reviewed which are of potential interest for the investigation of atomic and ionic level structures of superheavy elements. The latter are defined here as the trans-fermium elements with Z > 100 for which no experimental atomic or ionic level structure information is known so far, and which cannot be bred in high flux nuclear power reactors via successive neutron capture. The principles of suitable laser spectroscopic methods are described, and illustrated by examples of real experiments. The addressed methods include single-ion spectroscopy in Paul traps, laser-induced fluorescence spectroscopy (LIF), radiation-detected optical pumping (RADOP), radioactive decay-detected resonance ionization spectroscopy (RADRIS), and ion-guide-detected resonance ionization spectroscopy (IGRIS). With the exception of the first all take advantage of a storage of the ions or atoms in so-called buffer-gas traps. The developed experimental methods can, in principle, also be employed for studying ion-chemical reactions with gas admixtures like O2 as well as for performing ion mobility measurements. Both provide complementary information on the electronic structure of superheavy ions. First attempts on this road of research are reviewed as well.

  1. Evaluation of stainless steel cathodes and a bicarbonate buffer for hydrogen production in microbial electrolysis cells using a new method for measuring gas production

    KAUST Repository

    Ambler, Jack R.

    2011-01-01

    Microbial electrolysis cells (MECs) are often examined for hydrogen production using non-sustainable phosphate buffered solutions (PBS), although carbonate buffers have been shown to work in other bioelectrochemical systems with a platinum (Pt) catalyst. Stainless steel (SS) has been shown to be an effective catalyst for hydrogen evolution in MECs, but it has not been tested with carbonate buffers. We evaluated the combined using of SS cathodes and a bicarbonate buffer (BBS) at the applied voltages of 0.5, 0.7 and 0.9 V using a new inexpensive method for measuring gas production called the gas bag method (GBM). This method achieved an average error of only 5.0% based on adding known volumes of gas to the bag. Using the GBM, hydrogen production with SS and a BBS was 26.6 ± 1.8 mL which compared well to 26.4 ± 2.8 mL using Pt and BBS, and 26.8 ± 2.5 mL with a Pt cathode and PBS. Electrical energy efficiency was highest with a SS cathode and BBS at 159 ± 17%, compared to 126 ± 14% for the Pt cathode and BBS, and 134 ± 17% for a Pt cathode and PBS. The main disadvantage of the SS was a lower gas production rate of 1.1 ± 0.3 m3 H2-m-3 d-1 with BBS and 1.2 ± 0.3 m3 H2-m-3 d -1 with PBS, compared to 1.7 ± 0.4 m3 H 2-m-3 d-1 with Pt and PBS. These results show that the GBM is an effective new method for measuring gas production of anaerobic gas production processes, and that SS and bicarbonate buffers can be used to effectively produce hydrogen in MECs. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

  2. Contribution of heat transfer to turbine blades and vanes for high temperature industrial gas turbines. Part 1: Film cooling.

    Science.gov (United States)

    Takeishi, K; Aoki, S

    2001-05-01

    This paper deals with the contribution of heat transfer to increase the turbine inlet temperature of industrial gas turbines in order to attain efficient and environmentally benign engines. High efficiency film cooling, in the form of shaped film cooling and full coverage film cooling, is one of the most important cooling technologies. Corresponding heat transfer tests to optimize the film cooling effectiveness are shown and discussed in this first part of the contribution. PMID:11460641

  3. Integrated Method of the Computation of Cooling Systems for Gas Turbine Rotors

    OpenAIRE

    Тарасов, Александр Иванович; Чан, Конг Шанг; Литвиненко, Оксана Алексеевна; Михайлова, Ирина Александровна

    2015-01-01

    The integrated method allows for the simplification of the CFD analysis of the cooling of turbine rotors through the replacement of small-size elements (slots, labyrinth sealing, etc.) by virtual channels that provide the passage of air from one cavity to the next one. This computation method of the cooling of gas turbines was based on the combination of the method of computation of hydraulic networks and the method of computation of the flow and heat exchange of the viscous compressed liquid...

  4. Safety aspects of forced flow cooldown transients in Modular High Temperature Gas-Cooled Reactors

    International Nuclear Information System (INIS)

    During some of the design basis accidents in Modular High Temperature Gas Cooled Reactors (MHTGRs), the main Heat Transport System (HTS) and the Shutdown Cooling System n removed by the passive Reactor (SCS) are assumed to have failed. Decay heat is the Cavity Cooling System (RCCS) only. If either forced flow cooling system becomes available during such a transient, its restart could significantly reduce the down-time. This report used the THATCH code to examine whether such restart, during a period of elevated core temperatures, can be accomplished within safe limits for fuel and metal component temperatures. If the reactor is scrammed, either system can apparently be restarted at any time, without exceeding any safe limits. However, under unscrammed conditions a restart of forced cooling can lead to recriticality, with fuel and metal temperatures significantly exceeding the safety limits

  5. Safety aspects of forced flow cooldown transients in modular high temperature gas-cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Kroeger, P.G.

    1992-01-01

    During some of the design basis accidents in Modular High Temperature Gas Cooled Reactors (MHTGRs) the main Heat Transport System (HTS) and the Shutdown Cooling System (SCS), are assumed to have failed. Decay heat is then removed by the passive Reactor Cavity Cooling System (RCCS) only. If either forced flow cooling system becomes available during such a transient, its restart could significantly reduce the down-time. This paper uses the THATCH code to examine whether such restart, during a period of elevated core temperatures, can be accomplished within safe limits for fuel and metal component temperatures. If the reactor is scrammed, either system can apparently be restarted at any time, without exceeding any safe limits. However, under unscrammed conditions a restart of forced cooling can lead to recriticality, with fuel and metal temperatures significantly exceeding the safety limits.

  6. Safety aspects of forced flow cooldown transients in modular high temperature gas-cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Kroeger, P.G.

    1992-09-01

    During some of the design basis accidents in Modular High Temperature Gas Cooled Reactors (MHTGRs) the main Heat Transport System (HTS) and the Shutdown Cooling System (SCS), are assumed to have failed. Decay heat is then removed by the passive Reactor Cavity Cooling System (RCCS) only. If either forced flow cooling system becomes available during such a transient, its restart could significantly reduce the down-time. This paper uses the THATCH code to examine whether such restart, during a period of elevated core temperatures, can be accomplished within safe limits for fuel and metal component temperatures. If the reactor is scrammed, either system can apparently be restarted at any time, without exceeding any safe limits. However, under unscrammed conditions a restart of forced cooling can lead to recriticality, with fuel and metal temperatures significantly exceeding the safety limits.

  7. CFD Model Development and validation for High Temperature Gas Cooled Reactor Cavity Cooling System (RCCS) Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Yassin [Univ. of Wisconsin, Madison, WI (United Texas A & M Univ., College Station, TX (United States); Corradini, Michael; Tokuhiro, Akira; Wei, Thomas Y.C.

    2014-07-14

    The Reactor Cavity Cooling Systems (RCCS) is a passive safety system that will be incorporated in the VTHR design. The system was designed to remove the heat from the reactor cavity and maintain the temperature of structures and concrete walls under desired limits during normal operation (steady-state) and accident scenarios. A small scale (1:23) water-cooled experimental facility was scaled, designed, and constructed in order to study the complex thermohydraulic phenomena taking place in the RCCS during steady-state and transient conditions. The facility represents a portion of the reactor vessel with nine stainless steel coolant risers and utilizes water as coolant. The facility was equipped with instrumentation to measure temperatures and flow rates and a general verification was completed during the shakedown. A model of the experimental facility was prepared using RELAP5-3D and simulations were performed to validate the scaling procedure. The experimental data produced during the steady-state run were compared with the simulation results obtained using RELAP5-3D. The overall behavior of the facility met the expectations. The facility capabilities were confirmed to be very promising in performing additional experimental tests, including flow visualization, and produce data for code validation.

  8. A novel contra propagating ultrasonic flowmeter using glad buffer rods for high temperature measurement. Application to the oil and gas industries

    Energy Technology Data Exchange (ETDEWEB)

    Franca, Demartonne R. [Brasilia Univ., DF (Brazil). Dept. de Engenharia Eletrica; Cheng-Kuei Jen; Yuu Ono [National Research Council (NRC), Quebec (Canada). Industrial Materials Institute

    2005-07-01

    Ultrasonic techniques are attractive for process monitoring and control because they are non-intrusive, robust and inexpensive. Two common concerns limiting the high temperature performance of conventional ultrasonic systems for flow measurement are related to transducers and couplants. A suitable approach to overcoming this drawback is to insert a thermal isolating buffer rod with good ultrasonic performance (e.g., high signal-to-noise ratio). This requirement is important because, a priori, the noises generated in the buffer rod may bury the desired signals, so that no meaningful information is extracted. Besides protecting the ultrasonic transducers from overheating in applications such as high temperature flow measurements, buffer rods are also a solution for the couplant between the probe and tested sample, since their probing end can be directly wetted by fluids. Here, we propose clad buffer rods driven by shear transducers as the main building block of contra propagating ultrasonic flowmeters for high temperature application. It is demonstrated that the superior signal-to-noise ratio exhibit by clad buffer rods compared to the reported non-clad counterparts improve precision in transit-time measurement, leading to more accurate flow speed determination. In addition, it is shown that clad buffer rods generate specific ultrasonic signals for temperature calibration of flowmeters, allowing temperature variation while still measuring accurately the flow speed. These results are of interest for the oil and gas industries. (author)

  9. High temperature gas-cooled reactors - perspective of thermal reactor concept with high thermal efficiency

    International Nuclear Information System (INIS)

    The present HTR development is based worldwide on the extensive experience gained in the construction and operation of gas-cooled reactors of the Magnox type and on the successful operation of the experimental high temperature reactors Dragon, Peach Bottom and AVR. The advanced CO2-cooled reactors, as well as the HTR prototype power plants for St. Vrain and THTR, are all suffering considerable delays in construction and commissioning. The commercial HTR plants have not yet achieved the decisive breakthrough onto the market. Increasing interest is being shown in advanced HTR systems, i.e., HTR with gas turbine, HTR process heat reactors and gas-cooled fast breeders. The key problem in the coming years will be the closing of the fuel cycle. Development work in this connection has already started. (orig.)

  10. Analysis of characteristics of different working fluids for gas turbine cycle with high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Gas turbine cycle with high temperature gas-cooled reactor is the main direction of nuclear energy generation, which is with the advantages in terms of the safety and economy. The thermal and physical properties of helium, nitrogen, carbon dioxide and the mixtures were compared and analyzed in this paper. Further more, the heat transfer coefficient, pressure loss and the stage number of turbo-machines have been also compared. Results indicate that taking the mixture of helium and carbon dioxide as the working fluid of gas turbine cycle with high temperature gas-cooled reactor can not only improve the heat transfer coefficient and decrease the stage number of turbo-machinery, but also can limit the pressure loss to a certain level. (authors)

  11. Outline of models of water and gas flow through smectite clay buffers

    International Nuclear Information System (INIS)

    Microstructure analyses of natural clays with hydrous mica or smectite as major clay mineral have demonstrated that there are large variations in pore size, and that a few wide pores may be responsible for the great majority of the permeation. A similar behavior may be valid also for 'artificially' produced smectite clays which are formed from powdered Na bentonite. A model is derived for such clays in which the powder grains are regarded as anisotropic aggregates which swell on wetting and form a network with pores that are successively filled with a clay gel that emanates from the aggregates. The density and hydraulic conductivity of the gel is a function of the pore size and distribution as well as of the porewater chemistry. Applying the model to three 'reference' clay types of different bulk density, it is shown that realistic data for the hydraulic and gas conductivities as well as for the ratio of the anion and cation diffusion capacities are arrived at. The model is therefore taken as a basis for further development. (orig./HP)

  12. Inert Gas Buffered Milling and Particle Size Separation of μm-Scale Superconducting Precursor Powders

    Energy Technology Data Exchange (ETDEWEB)

    Seshadri, S. [Accelerator Technology Corp., College Station, TX (United States); McIntyre, P. [Accelerator Technology Corp., College Station, TX (United States)

    2008-06-20

    The project developed an aerosol system for the met milling and particle size separation of the precursor powders used in fabrication of powder-in-tube superconductors. The work builds upon the results of a previous SBIR-funded development that proved the basic principles of the virtual impactor (VI) technology and its efficacy for the powders of interest. The new project extended that work in three respects: it integrated provisions for recirculating the aerosol flow using inert gas to avoid contamination from O2, CO2 and water in ambient air; a quad configuration of VI subassemblies to support kg/hr throughput; and it incorporated design features that eliminate error trajectories which would introduce trace contamination of larger particles into the separated flow. The project demonstrated the technical effectiveness of the process and established its economic feasibility by achieving kg/hr throughput within a cost profile that would be profitable within the range of competitive toll fees. The project is beneficial to the public through its potential to improve the performance of superconducting materials for research and for biomedicine. It also conveys potential benefits for powders used in high-performance ceramics (for example for engines for automobiles and for aircraft) and for high-performance electrical insulators for telecommunications circuitry.

  13. A project definition for demonstrating a modular high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    This paper describes the modular high temperature gas-cooled reactor (MHTGR) design developed within the U.S. HTGR Program and the MHTGR demonstration project recently defined by Gas-Cooled Reactor Associates (GCRA) and its utility members. A Project Definition Study was funded by GCRA and the Tennessee Valley Authority (TVA) and was cost-shared by the participating contractors. The study considered a repowering option at an existing utility site and a stand-alone, full-plant option at a remote, government site. Through the proposed demonstration project, the MHTGR would become a commercial alternative for the U.S. utility industry

  14. Effect of Gas/Steam Turbine Inlet Temperatures on Combined Cycle Having Air Transpiration Cooled Gas Turbine

    Science.gov (United States)

    Kumar, S.; Singh, O.

    2012-10-01

    Worldwide efforts are being made for further improving the gas/steam combined cycle performance by having better blade cooling technology in topping cycle and enhanced heat recovery in bottoming cycle. The scope of improvement is possible through turbines having higher turbine inlet temperatures (TITs) of both gas turbine and steam turbine. Literature review shows that a combined cycle with transpiration cooled gas turbine has not been analyzed with varying gas/steam TITs. In view of above the present study has been undertaken for thermodynamic study of gas/steam combined cycle with respect to variation in TIT in both topping and bottoming cycles, for air transpiration cooled gas turbine. The performance of combined cycle with dual pressure heat recovery steam generator has been evaluated for different cycle pressure ratios (CPRs) varying from 11 to 23 and the selection diagrams presented for TIT varying from 1,600 to 1,900 K. Both the cycle efficiency and specific work increase with TIT for each pressure ratio. For each TIT there exists an optimum pressure ratio for cycle efficiency and specific work. For the CPR of 23 the best cycle performance is seen at a TIT of 1,900 K for maximum steam temperature of 570 °C, which gives the cycle efficiency of 60.9 % with net specific work of 909 kJ/kg.

  15. Modeling and performance of the MHTGR [Modular High-Temperature Gas-Cooled Reactor] reactor cavity cooling system

    International Nuclear Information System (INIS)

    The Reactor Cavity Cooling System (RCCS) of the Modular High- Temperature Gas-Cooled Reactor (MHTGR) proposed by the U.S. Department of Energy is designed to remove the nuclear afterheat passively in the event that neither the heat transport system nor the shutdown cooling circulator subsystem is available. A computer dynamic simulation for the physical and mathematical modeling of and RCCS is described here. Two conclusions can be made form computations performed under the assumption of a uniform reactor vessel temperature. First, the heat transferred across the annulus from the reactor vessel and then to ambient conditions is very dependent on the surface emissivities of the reactor vessel and RCCS panels. These emissivities should be periodically checked to ensure the safety function of the RCCS. Second, the heat transfer from the reactor vessel is reduced by a maximum of 10% by the presence of steam at 1 atm in the reactor cavity annulus for an assumed constant in the transmission of radiant energy across the annulus can be expected to result in an increase in the reactor vessel temperature for the MHTGR. Further investigation of participating radiation media, including small particles, in the reactor cavity annulus is warranted. 26 refs., 7 figs., 1 tab

  16. Efficiency of gas cooling and accretion at the disc-corona interface

    Science.gov (United States)

    Armillotta, L.; Fraternali, F.; Marinacci, F.

    2016-08-01

    In star-forming galaxies, stellar feedback can have a dual effect on the circumgalactic medium both suppressing and stimulating gas accretion. The trigger of gas accretion can be caused by disc material ejected into the halo in the form of fountain clouds and by its interaction with the surrounding hot corona. Indeed, at the disc-corona interface, the mixing between the cold/metal-rich disc gas (T ≲ 104 K) and the hot coronal gas (T ≳ 106 K) can dramatically reduce the cooling time of a portion of the corona and produce its condensation and accretion. We studied the interaction between fountain clouds and corona in different galactic environments through parsec-scale hydrodynamical simulations, including the presence of thermal conduction, a key mechanism that influences gas condensation. Our simulations showed that the coronal gas condensation strongly depends on the galactic environment, in particular it is less efficient for increasing virial temperature/mass of the haloes where galaxies reside and it is fully ineffective for objects with virial masses larger than 1013M⊙. This result implies that the coronal gas cools down quickly in haloes with low-intermediate virial mass (Mvir ≲ 3 × 1012M⊙) but the ability to cool the corona decreases going from late-type to early-type disc galaxies, potentially leading to the switching off of accretion and the quenching of star formation in massive systems.

  17. Search for sub-eV mass solar axions by the CERN Axion Solar Telescope with 3He buffer gas.

    Science.gov (United States)

    Arik, M; Aune, S; Barth, K; Belov, A; Borghi, S; Bräuninger, H; Cantatore, G; Carmona, J M; Cetin, S A; Collar, J I; Dafni, T; Davenport, M; Eleftheriadis, C; Elias, N; Ezer, C; Fanourakis, G; Ferrer-Ribas, E; Friedrich, P; Galán, J; García, J A; Gardikiotis, A; Gazis, E N; Geralis, T; Giomataris, I; Gninenko, S; Gómez, H; Gruber, E; Guthörl, T; Hartmann, R; Haug, F; Hasinoff, M D; Hoffmann, D H H; Iguaz, F J; Irastorza, I G; Jacoby, J; Jakovčić, K; Karuza, M; Königsmann, K; Kotthaus, R; Krčmar, M; Kuster, M; Lakić, B; Laurent, J M; Liolios, A; Ljubičić, A; Lozza, V; Lutz, G; Luzón, G; Morales, J; Niinikoski, T; Nordt, A; Papaevangelou, T; Pivovaroff, M J; Raffelt, G; Rashba, T; Riege, H; Rodríguez, A; Rosu, M; Ruz, J; Savvidis, I; Silva, P S; Solanki, S K; Stewart, L; Tomás, A; Tsagri, M; van Bibber, K; Vafeiadis, T; Villar, J A; Vogel, J K; Yildiz, S C; Zioutas, K

    2011-12-23

    The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using (3)He as a buffer gas. At T=1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with (4)He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV≲m(a)≲0.64 eV. From the absence of excess x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g(aγ)≲2.3×10(-10) GeV(-1) at 95% C.L., the exact value depending on the pressure setting. Kim-Shifman-Vainshtein-Zakharov axions are excluded at the upper end of our mass range, the first time ever for any solar axion search. In the future we will extend our search to m(a)≲1.15 eV, comfortably overlapping with cosmological hot dark matter bounds. PMID:22243149

  18. Quantum theory of spectral line shifts and broadening for hyperfine atomic transitions in a buffer gas medium

    International Nuclear Information System (INIS)

    The problem is solved of the formation of hyperfine transition spectral lines of active atoms in the atmosphere of an inert buffer gas. As a basis the quantum kinetic equation for the density matrix of the emitting atom is used. The following assumptions are made in deriving and solving the equation: smallness of the collision time compared with the time of free flight, small probability of reorientation of electron and nuclear spins in each collision and a large number of collisions during the emission period. It is found that the width and shape of the line significantly depend on the intensity of the weak magnetic field which induces Zeeman splitting of the hyperfine sublevels. In a zero magnetic field the line width is comparable to the line shift. With increase of the field intensity up to a certain value 10-2-10 Oe an appreciable decrease of the width occurs and it becomes smaller than the shift by several orders of magnitude. In this case the line shape is approximately Lorentzian. The shifts and widths due to the combined action of the Doppler effect and collisions are expressed in terms of the exact quantum-mechanical scattering amplitudes. Quasiclassical expressions for them and quantum corrections due to the nonclassical nature of translational motion of the atoms, which may reach 10% for light atoms, are found

  19. Dynamics of Greenhouse Gas Emissions from Riparian Buffer Zones and Wetlands as Hot Spots in Agricultural Landscapes

    International Nuclear Information System (INIS)

    The study considers various aspects of riparian buffer zones and wetlands for greenhouse gas emissions in agricultural landscapes of northern and north-eastern Europe. In particular, the impact of pulsing water regime, continuous loading and several alterations of environmental conditions on greenhouse gas emissions are taken into the consideration. In two case studies the isotopologue technique was used to distinguish between N2O sources in both riparian zones and constructed wetlands. Nitrous oxide (N2O) and nitrogen (N2) emissions, isotopic signatures of N2O and nitrate (NO3-) in groundwater of two differently loaded riparian grey alder stands in southern Estonia were investigated over a period of nine months. One area was a 38-year-old stand in Porijõgi (PJ), where uphill agricultural activities had been abandoned since the middle of 1990s, and the second area was a 55-year-old alder stand in Viiratsi (Vi), which still receives polluted lateral flow from uphill fields applied with pig slurry. Gas fluxes were measured in six sampling sessions, and water samples were analysed for NO3-, N2, N2O, and isotopic signatures of oxygen-18 (delta 18O, δ18O) and nitrogen-15 (delta 15N, δ15N) in N2O and NO3- in four of the six sessions. The N2O and N2 fluxes from both riparian zones did not differ significantly, being 9.6 ± 4.7 and 14.5 ± 3.9 μg N2O–N m−2 h−1, and 2 466 ± 275 and 3 083 ± 371 μg N2–N m−2 h−1 in PJ and Vi sites respectively, suggesting that gaseous N2 is the dominant gas emission from these alder stands. The isotopic signatures of N2O and NO3- were not significantly different between PJ and Vi study sites suggesting possible conversion of NO3- to N2O in both areas. The greater prevalence of N2 emissions over N2O in both areas, and the strong relationship between NO3- and N2O concentrations (r2 = 0.846, with p < 0.01) further suggested that denitrification is the main source of N2O and N2 fluxes in these grey alder stands. The dominant

  20. Cool core cycles: Cold gas and AGN jet feedback in cluster cores

    CERN Document Server

    Prasad, Deovrat; Babul, Arif

    2015-01-01

    Using high-resolution 3-D and 2-D (axisymmetric) hydrodynamic simulations in spherical geometry, we study the evolution of cool cluster cores heated by feedback-driven bipolar active galactic nuclei (AGN) jets. Condensation of cold gas, and the consequent enhanced accretion, is required for AGN feedback to balance radiative cooling with reasonable efficiencies, and to match the observed cool core properties. A feedback efficiency (mechanical luminosity $\\approx \\epsilon \\dot{M}_{\\rm acc} c^2$; where $\\dot{M}_{\\rm acc}$ is the mass accretion rate at 1 kpc) as small as $5 \\times 10^{-5}$ is sufficient to reduce the cooling/accretion rate by $\\sim 10$ compared to a pure cooling flow. This value is smaller compared to the ones considered earlier, and is consistent with the jet efficiency and the fact that only a small fraction of gas at 1 kpc is accreted on to the supermassive black hole (SMBH). We find hysteresis cycles in all our simulations with cold mode feedback: {\\em condensation} of cold gas when the ratio...

  1. Mechanical properties of structural materials for high temperature gas cooled reactor

    International Nuclear Information System (INIS)

    Structural materials for high temperature gas cooled reactor should have good properties such as mechanical properties (tensile, creep, fatigue, creep-fatigue), microstructural stability, interaction between metal and gas, friction and wear, hydrogen and tritium permeation, irradiation behavior, corrosion by impurity in He. Mechanical properties of major structural materials, such as pressure vessel, heat exchanger, control rod, were investigated. Effect of He and irradiation on these structural materials were investigated

  2. Specialists' meeting on gas-cooled reactor fuel development and spent fuel treatment

    International Nuclear Information System (INIS)

    Topics covered during the 'Specialists' meeting on gas-cooled reactor fuel development and spent fuel treatment' were as follows: Selection of constructions and materials, fuel element development concepts; Fabrication of spherical coated fuel particles and fuel element on their base; investigation of fuel properties; Spent fuel treatment and storage; Head-end processing of HTGR fuel elements; investigation of HTGR fuel regeneration process; applicability of gas-fluorine technology of regeneration of spent HTGR fuel elements

  3. Experience with the commissioning of helically coiled advanced gas cooled reactor boilers

    International Nuclear Information System (INIS)

    The paper describes aspects of the experience gained during commissioning of the helically coiled pod boilers for an advanced gas-cooled reactor. The boiler geometry is shown to be a factor contributing to gas-side and water-side convection phenomena encountered during commissioning. Detailed information on thermal performance and vibrational response was obtained from commissioning tests on specially instrumented boiler units. (author)

  4. Proton cooling in ultracold low-density electron gas

    Science.gov (United States)

    Bobrov, A. A.; Bronin, S. Y.; Manykin, E. A.; Zelener, B. B.; Zelener, B. V.; Khikhlukha, D. R.

    2015-11-01

    A sole proton energy loss processes in an electron gas and the dependence of these processes on temperature and magnetic field are studied using molecular dynamics techniques in present work. It appears that for electron temperatures less than 100 K many body collisions affect the proton energy loss and these collisions must be taken into account. The influence of a strong magnetic field on the relaxation processes is also considered in this work. Calculations were performed for electron densities 10 cm-3, magnetic field 1-3 Tesla, electron temperatures 10-50 K, initial proton energies 100-10000 K.

  5. Auxiliary heat exchanger for a gas-cooled nuclear reactor

    International Nuclear Information System (INIS)

    The proposal concerns the design configuration of the individual components of a heat exchanger with circular cross-section, being placed within a lined pod of the concrete shell of the pressure vessel. The heat exchanger has got a vertical cooler installed below the circulator. The components are arranged in such manner that the access to the pipe lines for in-service inspections is assured. Uniform velocity distribution of the gas streaming into the cooler from below is to be achieved. (orig./PW)

  6. Simulation for temperature changing investigation at RSG-GAS cooling system

    International Nuclear Information System (INIS)

    The RSG-GAS cooling system considers of primary and secondary system, is used for heat rejection from reactor core to the atmosphere. For temperature changing investigation cause by atmospherics condition changing or coolant flow rate changing, is more safe done by simulation. This paper describes the simulation for determine the RSG-GAS coolant temperature changing base on heat exchange and cooling tower characteristic. The simulation is done by computer programme running under WINDOWS 95 or higher. The temperature changing is based on heat transfer process on heat exchanger and cooling tower. The simulation will show the water tank temperature changing caused by the temperature and humidity of the atmosphere or by coolant flow rate changing. For example the humidity changing from 60% to 80% atmospherics temperature 30oC and 32400 k Watt power will change the tank temperature from 37,97oC to 40,03oC

  7. Study of Calixarene Inhibitor in the Secondary Cooling System of RSG-GAS

    International Nuclear Information System (INIS)

    Scales is among of the problems in secondary cooling system at Reaktor Serba Guna GA. Siwabessy (RSG-GAS) or pool reactor generally because it can decreased the efficiency of heat transfer in the heat exchanger therefore water flow plugged inside the pipes. There are several factors to form of scales, for instances water quality, water temperature, and flow rate. In this paper are described theoretically the effect of calixarene inhibitor to depress the scale growing in the secondary cooling system of RSG-GAS. Calixarene is organic inhibitor has aromatic chains, hollow structure form and four methoxy group supporting the strong complex to trap the Ca2+ or Mg2+ ion. The chelate complex between Ca2+ or Mg2+ dissolve in water therefore to close the large crystal possibly and to prevent crystal scale binding on the cooling pipes. The goals of study is to observe the calixarene behavior to the scale growing in secondary cooling of RSG-GAS. The method applied to study chemical structure dan calixarene properties, interaction between calixarene with crystal scale forming from Ca2+ and Mg2+ and theoretical calculation of inhibitor equivalent doses to precipitate Ca2+ or Mg2+ scales. Assuming that calixarene organic inhibitor mixed to secondary cooling system which from water resource without pretreatment and then to calculate metal complex dominant (Ca and Mg) equivalent to calixarene in the secondary cooling water. According to theoretical calculation gained that the equivalent doses in 1 m3 water is 1.3614 g per liter. From the assessment result has been identified that the scale problems in the secondary cooling system were understood so that the lowering of heat transfer efficiency in the heat exchanger avoided. (author)

  8. Accurate sampling of PCDD/F in high temperature flue-gas using cooled sampling probes.

    Science.gov (United States)

    Phan, Duong Ngoc Chau; Weidemann, Eva; Lundin, Lisa; Marklund, Stellan; Jansson, Stina

    2012-08-01

    In a laboratory-scale combustion reactor, flue-gas samples were collected at two temperatures in the post-combustion zone, 700°C and 400°C, using two different water-cooled sampling probes. The probes were the cooled probe described in the European Standard method EN-1948:1, referred to as the original probe, and a modified probe that contained a salt/ice mixture to assist the cooling, referred to as the sub-zero probe. To determine the efficiency of the cooling probes, internal temperature measurements were recorded at 5cm intervals inside the probes. Flue-gas samples were analyzed for polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs). Samples collected at 700°C using the original cooling probe showed higher concentrations of PCDD/Fs compared to samples collected using the sub-zero probe. No significant differences were observed between samples collected at 400°C. The results indicated that artifact formation of PCDD/Fs readily occurs during flue-gas sampling at high temperatures if the cooling within the probe is insufficient, as found for the original probe at 700°C. It was also shown that this problem could be alleviated by using probes with an enhanced cooling capacity, such as the sub-zero probe. Although this may not affect samples collected for regulatory purposes in exit gases, it is of great importance for research conducted in the high-temperature region of the post-combustion zone. PMID:22546632

  9. Gas-cooled fast reactor program. Progress report, January 1, 1980-June 30, 1981

    International Nuclear Information System (INIS)

    Since the national Gas-Cooled Fast Breeder Reactor Program has been terminated, this document is the last progress report until reinstatement. It is divided into three sections: Core Flow Test Loop, GCFR shielding and physics, and GCFR pressure vessel and closure studies

  10. Cooling capacity of water-gas mixtures. Application to the quenching of carbon steels

    Energy Technology Data Exchange (ETDEWEB)

    Moreaux, F. [CNRS, Nancy (France); Forgeoux, D. [SAM, Neuves Maisons (France); Jallon, M. [UNIMETAL, Amneville (France)

    1996-12-31

    During the heat treatment of metallic alloys, sometimes it is useful to cool down moderately in temperature range 1000{degrees}C - 600{degrees}C. During the quench in a vaporizable liquid (e.g water), this kind of cooling can be obtain thanks to the film boiling regime. If, in the case of water at 100 {degrees}C the film boiling is stable, the authors have shown the instability of film boiling when the water is at a lower temperature. A means to stabilize the film boiling consists of injecting gas in water. The authors built an experimental apparatus like a bubbles column. The gas is injected at the bottom of the column through a sintered glass. Thanks to a silver probe, the cooling capacity of different gas-water mixtures is measured versus the bubbles size, gas (air, carbon dioxide, hydrogen-nitrogen mixture) and water temperature. A great range of reproducible coolings is obtained versus these various parameters. This process is tested for the treatment of the carbon steels. In the special case of the 1080 steel, the authors have determined the mechanical characteristics for samples of 6 and 16 mm in diameter quenched in this quenching medium. For the samples of 6 mm in diameter, the values obtained are equivalent to these of lead-patented wire.

  11. Fuel handling system of 10 MW high temperature gas cooling reactor based on LabVIEW

    International Nuclear Information System (INIS)

    The field multi-channel signals has been acquired synchronously from 10 MW High temperature gas cooling reactor fuel handling system by DAQ technology. Counting software is developed based on LabVIEW. Its virtual instrument is flexible and user-friendly, and can count fuel-ball exactly. (authors)

  12. Engineering review of the core support structure of the Gas Cooled Fast Breeder Reactor

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-09-01

    The review of the core support structure of the gas cooled fast breeder reactor (GCFR) covered such areas as the design criteria, the design and analysis of the concepts, the development plan, and the projected manufacturing costs. Recommendations are provided to establish a basis for future work on the GCFR core support structure.

  13. Migration of radionuclides in a gas cooled solid state spallation target

    DEFF Research Database (Denmark)

    Jørgensen, Thomas; Severin, Gregory; Jensen, Mikael

    2015-01-01

    The current design of the ESS (European Spallation Source) program proposes a rotating solid tungsten target cooled by helium gas and a pulsed beam of protons. For safety reasons any design has to address whether or not the induced radionuclidic isotopes in the target migrate. In this paper we ha...

  14. Integration of High-Temperature Gas-Cooled Reactors into Industrial Process Applications

    Energy Technology Data Exchange (ETDEWEB)

    Lee Nelson

    2011-09-01

    This report is a summary of analyses performed by the NGNP project to determine whether it is technically and economically feasible to integrate high temperature gas cooled reactor (HTGR) technology into industrial processes. To avoid an overly optimistic environmental and economic baseline for comparing nuclear integrated and conventional processes, a conservative approach was used for the assumptions and calculations.

  15. Requirements for electricity producing gas-cooled reactors in the Federal Republic of Germany

    International Nuclear Information System (INIS)

    The paper describes requirements to a high-temperature gas-cooled reactor from the view-point of a utility in the Federal Republic of Germany. The requirements presented in the paper address different areas including plant size, availability, safety and economics. (author)

  16. Research and development for high temperature gas cooled reactor in Japan

    International Nuclear Information System (INIS)

    The paper describes the current status of High Temperature Gas Cooled Reactor research and development work in Japan, with emphasis on the Experimental Very High Temperature Reactor (Exp. VHTR) to be built by Japan Atomic Energy Research Institute (JAERI) before the end of 1985. The necessity of construction of Exp. VHTR was explained from the points of Japanese energy problems and resources

  17. Closed Fuel Cycle and Minor Actinide Multirecycling in a Gas-Cooled Fast Reactor

    NARCIS (Netherlands)

    Van Rooijen, W.F.G.; Kloosterman, J.L.

    2009-01-01

    The Generation IV International Forum has identified the Gas-Cooled Fast Reactor (GCFR) as one of the reactor concepts for future deployment. The GCFR targets sustainability, which is achieved by the use of a closed nuclear fuel cycle where only fission products are discharged to a repository; all H

  18. Gas-cooled fast reactor program. Progress report, January 1, 1980-June 30, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Kasten, P.R.

    1981-09-01

    Since the national Gas-Cooled Fast Breeder Reactor Program has been terminated, this document is the last progress report until reinstatement. It is divided into three sections: Core Flow Test Loop, GCFR shielding and physics, and GCFR pressure vessel and closure studies. (DLC)

  19. WASP-80b: a gas giant transiting a cool dwarf

    CERN Document Server

    Triaud, Amaury H M J; Cameron, A Collier; Doyle, A P; Fumel, A; Gillon, M; Hellier, C; Jehin, E; Lendl, M; Lovis, C; Maxted, P F L; Pepe, F; Pollacco, D; Queloz, D; Segransan, D; Smalley, B; Smith, A M S; Udry, S; West, R G; Wheatley, P J; 10.1051/0004-6361/201220900

    2013-01-01

    We report the discovery of a planet transiting the star WASP-80 (1SWASP J201240.26-020838.2; 2MASS J20124017-0208391; TYC 5165-481-1; BPM 80815; V=11.9, K=8.4). Our analysis shows this is a 0.55 +/- 0.04 Mjup, 0.95 +/- 0.03 Rjup gas giant on a circular 3.07 day orbit around a star with a spectral type between K7V and M0V. This system produces one of the largest transit depths so far reported, making it a worthwhile target for transmission spectroscopy. We find a large discrepancy between the v sin i inferred from stellar line broadening and the observed amplitude of the Rossiter-McLaughlin effect. This can be understood either by an orbital plane nearly perpendicular to the stellar spin or by an additional, unaccounted for source of broadening.

  20. Comparative Exergoeconomic Analyses of Gas Turbine Steam Injection Cycles with and without Fogging Inlet Cooling

    Directory of Open Access Journals (Sweden)

    Hassan Athari

    2015-09-01

    Full Text Available The results are reported of exergoeconomic analyses of a simple gas turbine cycle without a fogging system (SGT, a simple steam injection gas turbine cycle (STIG, and a steam injection gas turbine cycle with inlet fogging cooler (FSTIG. The results show that (1 a gas-turbine cycle with steam injection and simultaneous cooling has a higher power output than the other considered cycle; (2 at maximum energy efficiency conditions the gas turbine has the highest exergy efficiency of the cycle components and the lowest value of exergy efficiency is calculated for the fog cooler, where the mixing of air and water at greatly different temperatures causes the high exergy destruction; and (3 utilization of the fogging cooler in the steam injection cycle increases the exergy destruction in the combustion chamber. Furthermore, the simple gas turbine cycle is found to be more economic as its relative cost difference, total unit product cost, and exergoeconomic factors are less than those for the two other configurations. However, its efficiency and net power output are notably lower than for the gas turbine with steam injection and/or fog cooling. The total unit product cost is highest for the simple gas turbine with steam injection.

  1. High Temperature Gas-cooled Reactor Projected Markets and Scoping Economics

    Energy Technology Data Exchange (ETDEWEB)

    Larry Demick

    2010-08-01

    The NGNP Project has the objective of developing the high temperature gas-cooled reactor (HTGR) technology to supply high temperature process heat to industrial processes as a substitute for burning of fossil fuels, such as natural gas. Applications of the HTGR technology that have been evaluated by the NGNP Project for supply of process heat include supply of electricity, steam and high-temperature gas to a wide range of industrial processes, and production of hydrogen and oxygen for use in petrochemical, refining, coal to liquid fuels, chemical, and fertilizer plants.

  2. Mechanical Property and Its Comparison of Superalloys for High Temperature Gas Cooled Reactor

    International Nuclear Information System (INIS)

    Since structural materials for high temperature gas cooled reactor are used during long period in nuclear environment up to 1000 .deg. C, it is important to have good properties at elevated temperature such as mechanical properties (tensile, creep, fatigue, creep-fatigue), microstructural stability, interaction between metal and gas, friction and wear, hydrogen and tritium permeation, irradiation behavior, corrosion by impurity in He. Thus, in order to select excellent materials for the high temperature gas cooled reactor, it is necessary to understand the material properties and to gather the data for them. In this report, the items related to material properties which are needed for designing the high temperature gas cooled reactor were presented. Mechanical properties; tensile, creep, and fatigue etc. were investigated for Haynes 230, Hastelloy-X, In 617 and Alloy 800H, which can be used as the major structural components, such as intermediate heat exchanger (IHX), hot duct and piping and internals. Effect of He and irradiation on these structural materials was investigated. Also, mechanical properties; physical properties, tensile properties, creep and creep crack growth rate were compared for them, respectively. These results of this report can be used as important data to select superior materials for high temperature gas reactor

  3. Characteristic behavior of pebble-bed modular high-temperature gas-cooled reactor during loss of forced cooling accidents

    International Nuclear Information System (INIS)

    Based on the preliminary design of the Pebble-bed Modular High-Temperature Gas-cooled Reactor(HTR-PM), two cases of loss of forced cooling accident (DLOFC and PLOFC) were studied by the help of the software THERMIX. The key parameters including reactor power, temperature distributions of the core and pressure vessel, and the decay power removal by the passive residual heat remove system(RHRS) were compared in detail. Some parameter uncertainties were analyzed in order to evaluate the safety margin of the maximal fuel temperature during LOFC. The calculated results show that, the decay heat in the LOFC accidents can be removed from the reactor core solely by means of physical processes in a passive way, so that the temperature limits of fuel and components are still obeyed, which can effectively keep the integrality of the fuel particles to avoid massive fission products release. It also illustrates that the HTR-PM can reach 250 MW reactor power per unit and still can keep the inherent safety, which will be helpful to the further detail design of the HTR-PM demonstrating power plant project. (authors)

  4. Core configuration of a gas-cooled reactor as a tritium production device for fusion reactor

    International Nuclear Information System (INIS)

    The performance of a high-temperature gas-cooled reactor as a tritium production device is examined, assuming the compound LiAlO2 as the tritium-producing material. A gas turbine high-temperature reactor of 300 MWe nominal capacity (GTHTR300) is assumed as the calculation target, and using the continuous-energy Monte Carlo transport code MVP-BURN, burn-up simulations are carried out. To load sufficient Li into the core, LiAlO2 is loaded into the removable reflectors that surround the ring-shaped fuel blocks in addition to the burnable poison insertion holes. It is shown that module high-temperature gas-cooled reactors with a total thermal output power of 3 GW can produce almost 8 kg of tritium in a year

  5. Comparison of evaporative inlet air cooling systems to enhance the gas turbine generated power

    Energy Technology Data Exchange (ETDEWEB)

    Mohammad Ameri; Shahbazian, H.R.; Nabizadeh, M. [Power and Water University of Technology, Tehran (Iran). Energy Engineering Dept.

    2007-12-15

    The gas turbine performance is highly sensitive to the compressor inlet temperature. The output of gas turbine falls to a value that is less than the rated output under high temperature conditions. In fact increase in inlet air temperature by 1{sup o}C will decrease the output power by 0.7% approximately. The solution of this problem is very important because the peak demand season also happens in the summer. One of the convenient methods of inlet air cooling is evaporating cooling which is appropriate for warm and dry weather. As most of the gas turbines in Iran are installed in such ambient conditions regions, therefore this method can be used to enhance the performance of the gas turbines. In this paper, an overview of technical and economic comparison of media system and fog system is given. The performance test results show that the mean output power of Frame-9 gas turbines is increased by 11 MW (14.5%) by the application of media cooling system in Fars power plant and 8.1 MW (8.9%) and 9.5 MW (11%) by the application of fog cooling system in Ghom and Shahid Rajaie power plants, respectively. The total enhanced power generation in the summer of 2004 was 2970, 1701 and 1340 MWh for the Fars, Ghom and Shahid Rajaie power plants, respectively. The economical studies show that the payback periods are estimated to be around 2 and 3 years for fog and media systems, respectively. This study has shown that both methods are suitable for the dry and hot areas for gas turbine power augmentation. (author)

  6. Thermal Hydraulics of the Very High Temperature Gas Cooled Reactor

    International Nuclear Information System (INIS)

    The U.S Department of Energy (DOE) is conducting research on the Very High Temperature Reactor (VHTR) design concept for the Next Generation Nuclear Plant (NGNP) Project. The reactor design will be a graphite moderated, thermal neutron spectrum reactor that will produce electricity and hydrogen in a highly efficient manner. The NGNP reactor core will be either a prismatic graphite block type core or a pebble bed core. The NGNP will use very high-burnup, low-enriched uranium, TRISO-coated fuel, and have a projected plant design service life of 60 years. The VHTR concept is considered to be the nearest-term reactor design that has the capability to efficiently produce hydrogen. The plant size, reactor thermal power, and core configuration will ensure passive decay heat removal without fuel damage or radioactive material releases during reactor core-accidents. The objectives of the NGNP Project are to: Demonstrate a full-scale prototype VHTR that is commercially licensed by the U.S. Nuclear Regulatory Commission, and Demonstrate safe and economical nuclear-assisted production of hydrogen and electricity. The DOE laboratories, led by the INL, perform research and development (R and D) that will be critical to the success of the NGNP, primarily in the areas of: (1) High temperature gas reactor fuels behavior; (2) High temperature materials qualification; (3) Design methods development and validation; (4) Hydrogen production technologies; and (5) Energy conversion. This paper presents current R and D work that addresses fundamental thermal hydraulics issues that are relevant to a variety of possible NGNP designs

  7. Thermal hydraulics of the very high temperature gas cooled reactor

    International Nuclear Information System (INIS)

    The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is conducting research on the Very High Temperature Reactor (VHTR) design concept for the Next Generation Nuclear Plant (NGNP) Project. The reactor design will be a graphite moderated, thermal neutron spectrum reactor that will produce electricity and hydrogen in a highly efficient manner. The NGNP reactor core will be either a prismatic graphite block type core or a pebble bed core. The NGNP will use very high-burnup, low-enriched uranium, TRISO-coated fuel, and have a projected plant design service life of 60 years. The VHTR concept is considered to be the nearest-term reactor design that has the capability to efficiently produce hydrogen. The plant size, reactor thermal power, and core configuration will ensure passive decay heat removal without fuel damage or radioactive material releases during reactor core-accidents. The objectives of the NGNP Project are to: Demonstrate a full-scale prototype VHTR that is commercially licensed by the U.S. Nuclear Regulatory Commission, and Demonstrate safe and economical nuclear-assisted production of hydrogen and electricity. The DOE laboratories, led by the INL, perform research and development (R and D) that will be critical to the success of the NGNP, primarily in the areas of: · High temperature gas reactor fuels behavior · High temperature materials qualification · Design methods development and validation · Hydrogen production technologies · Energy conversion. This paper presents current R and D work that addresses fundamental thermal hydraulics issues that are relevant to a variety of possible NGNP designs. (author)

  8. Thermal Hydraulics of the Very High Temperature Gas Cooled Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chang Oh; Eung Kim; Richard Schultz; Mike Patterson; Davie Petti

    2009-10-01

    The U.S Department of Energy (DOE) is conducting research on the Very High Temperature Reactor (VHTR) design concept for the Next Generation Nuclear Plant (NGNP) Project. The reactor design will be a graphite moderated, thermal neutron spectrum reactor that will produce electricity and hydrogen in a highly efficient manner. The NGNP reactor core will be either a prismatic graphite block type core or a pebble bed core. The NGNP will use very high-burnup, low-enriched uranium, TRISO-coated fuel, and have a projected plant design service life of 60 years. The VHTR concept is considered to be the nearest-term reactor design that has the capability to efficiently produce hydrogen. The plant size, reactor thermal power, and core configuration will ensure passive decay heat removal without fuel damage or radioactive material releases during reactor core-accidents. The objectives of the NGNP Project are to: Demonstrate a full-scale prototype VHTR that is commercially licensed by the U.S. Nuclear Regulatory Commission, and Demonstrate safe and economical nuclear-assisted production of hydrogen and electricity. The DOE laboratories, led by the INL, perform research and development (R&D) that will be critical to the success of the NGNP, primarily in the areas of: • High temperature gas reactor fuels behavior • High temperature materials qualification • Design methods development and validation • Hydrogen production technologies • Energy conversion. This paper presents current R&D work that addresses fundamental thermal hydraulics issues that are relevant to a variety of possible NGNP designs.

  9. On-Line Fuel Failure Monitor for Fuel Testing and Monitoring of Gas Cooled Very High Temperature Reactors

    International Nuclear Information System (INIS)

    Very High Temperature Reactors (VHTR) utilize the TRISO microsphere as the fundamental fuel unit in the core. The TRISO microsphere (∼ 1-mm diameter) is composed of a UO2 kernel surrounded by a porous pyrolytic graphite buffer, an inner pyrolytic graphite layer, a silicon carbide (SiC) coating, and an outer pyrolytic graphite layer. The U-235 enrichment of the fuel is expected to range from 4%-10% (higher enrichments are also being considered). The layer/coating system that surrounds the UO2 kernel acts as the containment and main barrier against the environmental release of radioactivity. To understand better the behavior of this fuel under in-core conditions (e.g., high temperature, intense fast neutron flux, etc.), the US Department of Energy (DOE) is launching a fuel testing program that will take place at the Advanced Test Reactor (ATR) located at Idaho National Laboratory (INL). During this project North Carolina State University (NCSU) researchers will collaborate with INL staff for establishing an optimized system for fuel monitoring for the ATR tests. In addition, it is expected that the developed system and methods will be of general use for fuel failure monitoring in gas cooled VHTRs.

  10. A combined gas cooled nuclear reactor and fuel cell cycle

    Science.gov (United States)

    Palmer, David J.

    Rising oil costs, global warming, national security concerns, economic concerns and escalating energy demands are forcing the engineering communities to explore methods to address these concerns. It is the intention of this thesis to offer a proposal for a novel design of a combined cycle, an advanced nuclear helium reactor/solid oxide fuel cell (SOFC) plant that will help to mitigate some of the above concerns. Moreover, the adoption of this proposal may help to reinvigorate the Nuclear Power industry while providing a practical method to foster the development of a hydrogen economy. Specifically, this thesis concentrates on the importance of the U.S. Nuclear Navy adopting this novel design for its nuclear electric vessels of the future with discussion on efficiency and thermodynamic performance characteristics related to the combined cycle. Thus, the goals and objectives are to develop an innovative combined cycle that provides a solution to the stated concerns and show that it provides superior performance. In order to show performance, it is necessary to develop a rigorous thermodynamic model and computer program to analyze the SOFC in relation with the overall cycle. A large increase in efficiency over the conventional pressurized water reactor cycle is realized. Both sides of the cycle achieve higher efficiencies at partial loads which is extremely important as most naval vessels operate at partial loads as well as the fact that traditional gas turbines operating alone have poor performance at reduced speeds. Furthermore, each side of the cycle provides important benefits to the other side. The high temperature exhaust from the overall exothermic reaction of the fuel cell provides heat for the reheater allowing for an overall increase in power on the nuclear side of the cycle. Likewise, the high temperature helium exiting the nuclear reactor provides a controllable method to stabilize the fuel cell at an optimal temperature band even during transients helping

  11. Modular high-temperature gas-cooled reactor core heatup accident simulations

    International Nuclear Information System (INIS)

    The design features of the modular high-temperature gas-cooled reactor (HTGR) have the potential to make it essentially invulnerable to damage from postulated core heatup accidents. Simulations of long-term loss-of-forced-convection (LOFC) accidents, both with and without depressurization of the primary coolant and with only passive cooling available to remove afterheat, have shown that maximum core temperatures stay below the point at which fuel failures and fission product releases are expected. Sensitivity studies also have been done to determine the effects of errors in the predictions due both to uncertainties in the modeling and to the assumptions about operational parameters. 4 refs., 5 figs

  12. On the connection between radio mini-halos and gas heating in cool core clusters

    CERN Document Server

    Bravi, Luca; Brunetti, Gianfranco

    2016-01-01

    In this work, we present a study of the central regions of cool-core clusters hosting radio mini-halos, which are di use synchrotron sources extended on cluster-scales surrounding the radio-loud brightest galaxy. We aim to investigate the interplay between the thermal and non-thermal components in the intracluster medium in order to get more insights into these radio sources, whose nature is still unclear. It has recently been proposed that turbulence plays a role for heating the gas in cool cores. A correlation between the radio luminosity of mini-halos, $\

  13. Preliminary Investigation of an Optimally Scramming Control Rod for Gas-Cooled Reactors

    International Nuclear Information System (INIS)

    A passively safe control rod for gas-cooled reactors is proposed. This Optimally Scramming Control Rod (OSCR) is lifted out of the core region by the core coolant and descends back into the core when the coolant flow is not sufficient for core cooling purposes or in the event of depressurization. It is shown that for the current design of the OSCR, the reactor can be operated under normal lower power conditions down to about 80% of total power. It is also shown that cold shutdown can be achieved with rods of sufficiently low mass to allow naturally passive operation of the concept. (authors)

  14. Licensing topical report: interpretation of general design criteria for high-temperature gas-cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Orvis, D.D.; Raabe, P.H.

    1980-01-01

    This Licensing Topical Report presents a set of General Design Criteria (GDC) which is proposed for applicability to licensing of graphite-moderated, high-temperature gas-cooled reactors (HTGRs). Modifications as necessary to reflect HTGR characteristics and design practices have been made to the GDC derived for applicability to light-water-cooled reactors and presented in Appendix A of Part 50, Title 10, Code of Federal Regulations, including the Introduction, Definitions, and Criteria. It is concluded that the proposed set of GDC affords a better basis for design and licensing of HTGRs.

  15. Licensing topical report: interpretation of general design criteria for high-temperature gas-cooled reactors

    International Nuclear Information System (INIS)

    This Licensing Topical Report presents a set of General Design Criteria (GDC) which is proposed for applicability to licensing of graphite-moderated, high-temperature gas-cooled reactors (HTGRs). Modifications as necessary to reflect HTGR characteristics and design practices have been made to the GDC derived for applicability to light-water-cooled reactors and presented in Appendix A of Part 50, Title 10, Code of Federal Regulations, including the Introduction, Definitions, and Criteria. It is concluded that the proposed set of GDC affords a better basis for design and licensing of HTGRs

  16. Gas Reactor International Cooperative Program. Interim report. Construction and operating experience of selected European Gas-Cooled Reactors

    Energy Technology Data Exchange (ETDEWEB)

    1978-09-01

    The construction and operating experience of selected European Gas-Cooled Reactors is summarized along with technical descriptions of the plants. Included in the report are the AVR Experimental Pebble Bed Reactor, the Dragon Reactor, AGR Reactors, and the Thorium High Temperature Reactor (THTR). The study demonstrates that the European experience has been favorable and forms a good foundation for the development of Advanced High Temperature Reactors.

  17. Gas Reactor International Cooperative Program. Interim report. Construction and operating experience of selected European Gas-Cooled Reactors

    International Nuclear Information System (INIS)

    The construction and operating experience of selected European Gas-Cooled Reactors is summarized along with technical descriptions of the plants. Included in the report are the AVR Experimental Pebble Bed Reactor, the Dragon Reactor, AGR Reactors, and the Thorium High Temperature Reactor (THTR). The study demonstrates that the European experience has been favorable and forms a good foundation for the development of Advanced High Temperature Reactors

  18. Internally gas-cooled radiofrequency applicators as an alternative to conventional radiofrequency and microwave ablation devices: An in vivo comparison

    Energy Technology Data Exchange (ETDEWEB)

    Rempp, Hansjörg, E-mail: Hansjoerg.rempp@med.uni-tuebingen.de [Eberhard Karls University of Tübingen, Tübingen University Hospital, Department of Diagnostic and Interventional Radiology, Hoppe-Seyler-Straße 3, Tübingen, 72076 (Germany); Voigtländer, Matthias [ERBE Elektromedizin GmbH, Waldhörnlestraße 17, 72072 Tübingen (Germany); Schenk, Martin [Eberhard Karls University of Tuebingen, Tübingen University Hospital, Department of General, Visceral and Transplant Surgery, Hoppe-Seyler-Straße 3, 72076 Tübingen (Germany); Enderle, Markus D. [ERBE Elektromedizin GmbH, Waldhörnlestraße 17, 72072 Tübingen (Germany); Scharpf, Marcus [Eberhard Karls University of Tuebingen, Insitute of Pathology, Department on General Pathology and Pathological Anatomy, Liebermeisterstraße 8, 72076 Tübingen (Germany); Greiner, Tim O. [Eberhard Karls University of Tuebingen, Tübingen University Hospital, Department of General, Visceral and Transplant Surgery, Hoppe-Seyler-Straße 3, 72076 Tübingen (Germany); Neugebauer, Alexander [ERBE Elektromedizin GmbH, Waldhörnlestraße 17, 72072 Tübingen (Germany); and others

    2013-08-15

    Purpose: To test the efficacy of internally CO{sub 2}-cooled radiofrequency (RF) ablation in vivo and to compare its effectiveness to a standard water-cooled RF probe and to a gas-cooled microwave (MW) device. Method and materials: 49 ablations were performed on 15 pigs under general anesthesia using 15G monopolar CO{sub 2}-cooled RF applicators, 17G monopolar water-cooled RF applicators and 15G internally CO{sub 2}-cooled microwave devices. The power of the MW device was 45 W, the current of the gas-cooled RF device was 1200–1600 mA. At the water-cooled RF probe, maximum power of 200 W was set. Ablation time was 15 min. The short and long axes of the ablation zone were measured. Histological analyses and NADH-staining were performed. The diameters and the ablation volumes were compared using an analysis of variance. Results: No spots of untreated tissue were observed close to the cooled needle track in any of the ablation zones. The largest short axis diameter was 3.4 ± 0.5 cm achieved with the gas-cooled monopolar applicator. With the water-cooled applicators, short axis diameter was significantly smaller, reaching 2.5 ± 0.4 cm. Gas-cooled MW probes achieved 2.9 ± 1.0 cm. The largest ablation volume was 31.5 ± 12 ml (gas-cooled RF), and the smallest was 12.7 ± 4 ml (water-cooled RF). Short/long axis ratio was largest for gas-cooled RF probes with 0.73 ± 0.08 versus 0.64 ± 0.04 for the water-cooled probes and 0.49 ± 0.25 for the microwave applicator. Conclusion: Gas-cooled RF applicators may have a higher potential for effective destruction of liver lesions than comparable water-cooled RF systems, and may be an alternative to standard RF and MW ablation devices.

  19. Internally gas-cooled radiofrequency applicators as an alternative to conventional radiofrequency and microwave ablation devices: An in vivo comparison

    International Nuclear Information System (INIS)

    Purpose: To test the efficacy of internally CO2-cooled radiofrequency (RF) ablation in vivo and to compare its effectiveness to a standard water-cooled RF probe and to a gas-cooled microwave (MW) device. Method and materials: 49 ablations were performed on 15 pigs under general anesthesia using 15G monopolar CO2-cooled RF applicators, 17G monopolar water-cooled RF applicators and 15G internally CO2-cooled microwave devices. The power of the MW device was 45 W, the current of the gas-cooled RF device was 1200–1600 mA. At the water-cooled RF probe, maximum power of 200 W was set. Ablation time was 15 min. The short and long axes of the ablation zone were measured. Histological analyses and NADH-staining were performed. The diameters and the ablation volumes were compared using an analysis of variance. Results: No spots of untreated tissue were observed close to the cooled needle track in any of the ablation zones. The largest short axis diameter was 3.4 ± 0.5 cm achieved with the gas-cooled monopolar applicator. With the water-cooled applicators, short axis diameter was significantly smaller, reaching 2.5 ± 0.4 cm. Gas-cooled MW probes achieved 2.9 ± 1.0 cm. The largest ablation volume was 31.5 ± 12 ml (gas-cooled RF), and the smallest was 12.7 ± 4 ml (water-cooled RF). Short/long axis ratio was largest for gas-cooled RF probes with 0.73 ± 0.08 versus 0.64 ± 0.04 for the water-cooled probes and 0.49 ± 0.25 for the microwave applicator. Conclusion: Gas-cooled RF applicators may have a higher potential for effective destruction of liver lesions than comparable water-cooled RF systems, and may be an alternative to standard RF and MW ablation devices

  20. Heat transfer technology for internal passages of air-cooled blades for heavy-duty gas turbines.

    Science.gov (United States)

    Weigand, B; Semmler, K; von Wolfersdorf, J

    2001-05-01

    The present review paper, although far from being complete, aims to give an overview about the present state of the art in the field of heat transfer technology for internal cooling of gas turbine blades. After showing some typical modern cooled blades, the different methods to enhance heat transfer in the internal passages of air-cooled blades are discussed. The complicated flows occurring in bends are described in detail, because of their increasing importance for modern cooling designs. A short review about testing of cooling design elements is given, showing the interaction of the different cooling features as well. The special focus of the present review has been put on the cooling of blades for heavy-duty gas turbines, which show several differences compared to aero-engine blades. PMID:11460627

  1. Power Enhancement of Gas Turbine Plant by Intake Air Fog Cooling

    Directory of Open Access Journals (Sweden)

    J. P. Yadav

    2012-08-01

    Full Text Available Performance of gas turbine significantly depends upon the ambient air temperature and mass flow rate. During summer season the density of the air decreases which affects the mass flow rate and ultimately the power output of a gas turbine is reduced. In order to overcome this situation several techniques are already in the practice and one of the most effective and economical is adopting the inlet fog cooling which basically enhances the power output of the machine. The cooling of ambient air by fog cooling up to wet bulb temperature increases the mass flow rate on account of increase in air density, as a result it ultimately increases the power output of a gas turbine. Fogging is applied with consideration of relative humidity of ambient air not only during summer season but also during dry days of summer season in order to increase the power output of gas turbine. This paper describes the effect on percentage enhancement of power output adopting various fuel options with low and high humidity ambient conditions. The results indicate the potential increase in the power output up to 14�20It is also observed that the total cost of power production increases due to increase in fuel consumption on account of enhanced power output. Thus, the optimum operating parameters are required for taking advantage of power augmentation ensuring that it does not lead to excessive increase in fuel cost.

  2. Facility Configuration Study of the High Temperature Gas-Cooled Reactor Component Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    S. L. Austad; L. E. Guillen; D. S. Ferguson; B. L. Blakely; D. M. Pace; D. Lopez; J. D. Zolynski; B. L. Cowley; V. J. Balls; E.A. Harvego, P.E.; C.W. McKnight, P.E.; R.S. Stewart; B.D. Christensen

    2008-04-01

    A test facility, referred to as the High Temperature Gas-Cooled Reactor Component Test Facility or CTF, will be sited at Idaho National Laboratory for the purposes of supporting development of high temperature gas thermal-hydraulic technologies (helium, helium-Nitrogen, CO2, etc.) as applied in heat transport and heat transfer applications in High Temperature Gas-Cooled Reactors. Such applications include, but are not limited to: primary coolant; secondary coolant; intermediate, secondary, and tertiary heat transfer; and demonstration of processes requiring high temperatures such as hydrogen production. The facility will initially support completion of the Next Generation Nuclear Plant. It will secondarily be open for use by the full range of suppliers, end-users, facilitators, government laboratories, and others in the domestic and international community supporting the development and application of High Temperature Gas-Cooled Reactor technology. This pre-conceptual facility configuration study, which forms the basis for a cost estimate to support CTF scoping and planning, accomplishes the following objectives: • Identifies pre-conceptual design requirements • Develops test loop equipment schematics and layout • Identifies space allocations for each of the facility functions, as required • Develops a pre-conceptual site layout including transportation, parking and support structures, and railway systems • Identifies pre-conceptual utility and support system needs • Establishes pre-conceptual electrical one-line drawings and schedule for development of power needs.

  3. Spitzer Secondary Eclipse Observations of Five Cool Gas Giant Planets and Empirical Trends in Cool Planet Emission Spectra

    CERN Document Server

    Kammer, Joshua A; Line, Michael R; Fortney, Jonathan J; Deming, Drake; Burrows, Adam; Cowan, Nicolas B; Triaud, Amaury H M J; Agol, Eric; Desert, Jean-Michel; Fulton, Benjamin J; Howard, Andrew W; Laughlin, Gregory P; Lewis, Nikole K; Morley, Caroline V; Moses, Julianne I; Showman, Adam P; Todorov, Kamen O

    2015-01-01

    In this work we present Spitzer 3.6 and 4.5 micron secondary eclipse observations of five new cool (<1200 K) transiting gas giant planets: HAT-P-19b, WASP-6b, WASP-10b, WASP-39b, and WASP-67b. We compare our measured eclipse depths to the predictions of a suite of atmosphere models and to eclipse depths for planets with previously published observations in order to constrain the temperature- and mass-dependent properties of gas giant planet atmospheres. We find that the dayside emission spectra of planets less massive than Jupiter require models with efficient circulation of energy to the night side and/or increased albedos, while those with masses greater than that of Jupiter are consistently best-matched by models with inefficient circulation and low albedos. At these relatively low temperatures we expect the atmospheric methane to CO ratio to vary as a function of metallicity, and we therefore use our observations of these planets to constrain their atmospheric metallicities. We find that the most massi...

  4. Penetrating Gas Streams Generate Unrelaxed,Non-Cool-Core Clusters of Galaxies

    CERN Document Server

    Zinger, E; Birnboim, Y; Kravtsov, A; Nagai, D

    2015-01-01

    We utilize cosmological simulations of 16 galaxy clusters at redshifts $z=0$ and $z=0.6$ to study the effect of inflowing streams on the properties of the inner Intra-Cluster Medium (ICM). We find that the mass accretion occurs predominantly along streams that originate from the cosmic web and consist of heated gas. Clusters that are unrelaxed in terms of their X-ray morphology are characterized by higher mass inflow rates and deeper penetration of the streams, typically into the inner third of the virial radius. The penetrating streams generate elevated random motions, bulk flows, cold fronts and metal mixing, thus producing Non-Cool-Core clusters. The degree of penetration of the streams may change over time such that clusters can switch from being unrelaxed to relaxed over a time-scale of several Gyrs. The stream properties thus help us understand the distinction between cool-core and non-cool-core clusters.

  5. Flow structure and heat exchange analysis in internal cooling channel of gas turbine blade

    Science.gov (United States)

    Szwaba, Ryszard; Kaczynski, Piotr; Doerffer, Piotr; Telega, Janusz

    2016-08-01

    This paper presents the study of the flow structure and heat transfer, and also their correlations on the four walls of a radial cooling passage model of a gas turbine blade. The investigations focus on heat transfer and aerodynamic measurements in the channel, which is an accurate representation of the configuration used in aeroengines. Correlations for the heat transfer coefficient and the pressure drop used in the design of radial cooling passages are often developed from simplified models. It is important to note that real engine passages do not have perfect rectangular cross sections, but include corner fillet, ribs with fillet radii and special orientation. Therefore, this work provides detailed fluid flow and heat transfer data for a model of radial cooling geometry which possesses very realistic features.

  6. Gas-cooled high temperature reactor with a coolant gas circuit subdivided into several loops

    International Nuclear Information System (INIS)

    In the annulus between liner and side reflector horizontal penetrations open up in which the hot-gas pipes run coaxially. For isolating these loops inflatable sealing bellows, and inflatable sealing balloons are introduced through construction openings, each sealing bellows isolating the gap between penetration and hot-gas pipe and the sealing balloon isolating the hot-gas pipe itself. (RW)

  7. Development of fuel failure detection system for a High Temperature Gas Cooled Reactor (V)

    International Nuclear Information System (INIS)

    This paper reports on a fuel failure detection (FFD) system using a wire-precipitator developed for a High Temperature Gas cooled reactor (HTGR). On actual application of the FFD, it is important to inquire the response characteristics of the precipitator and the behavior of noble-gas-FPs released from coated particle fuel compacts. The dependence of the precipitator counting rate on purge-gas flow-rate was measured. A response function of the precipitator including the dilution effect of the purge-gas was fabricated. Adsorption characteristics of a charcoal-filter for noble-gas-FPs was measured. Under the low flow-rate, noble-gas-FPs are adsorbed by the charcoal-filter and Xenon are adsorbed easily. A preliminary experiment for FFD system using this adsorption effect was performed. Moreover, a FFD response function for noble-gas-FPs circulated in a primary coolant system was developed to estimate the released noble-gas-FPs in the primary coolant system. The validity of this function was confirmed by experiments using the Helium gas loop OGL-1

  8. Thermodynamic performance analysis of gas-fired air-cooled adiabatic absorption refrigeration systems

    International Nuclear Information System (INIS)

    In China, the application of small size gas-fired air-cooled absorption refrigeration systems as an alternative for electric compression air conditioning systems has shown broad prospects due to occurrence of electricity peak demand in Chinese big cities and lack of water resources. However, for conventional air-cooled absorption refrigeration systems, it is difficult to enhance the heat and mass transfer process in the falling film absorber, and may cause problems, for example, remarkable increase of pressure, temperature and concentration in the generators, risk of crystallization, acceleration of corrosion, degradation of performance, and so on. This paper presents a gas-fired air-cooled adiabatic absorption refrigeration system using lithium bromide-water solutions as its working fluid, which is designed with a cooling capacity of 16 kW under standard conditions. The system has two new features of waste heat recovery of condensed water from generator and an adiabatic absorber with an air cooler. Performance simulation and characteristic analysis are crucial for the optimal control and reliability of operation in extremely hot climates. A methodology is presented to simulate thermodynamic performance of the system. The influences of outdoor air temperature on operation performances of the system are investigated

  9. Decay Heat Removal in GEN IV Gas-Cooled Fast Reactors

    International Nuclear Information System (INIS)

    The safety goal of the current designs of advanced high-temperature thermal gas-cooled reactors (HTRs) is that no core meltdown would occur in a depressurization event with a combination of concurrent safety system failures. This study focused on the analysis of passive decay heat removal (DHR) in a GEN IV direct-cycle gas-cooled fast reactor (GFR) which is based on the technology developments of the HTRs. Given the different criteria and design characteristics of the GFR, an approach different from that taken for the HTRs for passive DHR would have to be explored. Different design options based on maintaining core flow were evaluated by performing transient analysis of a depressurization accident using the system code RELAP5-3D. The study also reviewed the conceptual design of autonomous systems for shutdown decay heat removal and recommends that future work in this area should be focused on the potential for Brayton cycle DHRs.

  10. DELIGHT-6(revised): one dimensional lattice burnup code for high temperature gas cooled reactors

    International Nuclear Information System (INIS)

    The code, DELIGHT-6, performs the multi-group neutron spectrum calculation and provides the few-group constants for burnup calculations of a high temperature gas-cooled reactor core, whose fuel elements containing many coated fuel particles are arranged in double heterogeneity. The main revisions in the DELIGHT-6 (Revised) are as follows; (1)The option of a sphere fuel cell calculation is added for the core design of pebble bed type high temperature gas-cooled reactor. (2)The yield and decay constants of fission products for burnup calculation is revised. (3)The following auxiliary functions are added; (i) Automatic calculation of averaged atom number density in the fuel region, (ii) Estimation of local neutron flux distribution (disadvantage factor), (iii) Preparation of the data for the fine mesh core calculation. (author)

  11. A determination of degradation capability of RSG-GAS piping secondary cooling system

    International Nuclear Information System (INIS)

    A research of degradation capabilities of RSG-GAS secondary cooling piping system has been done in G.A. Siwabessy Multy Purpose Reactor Serpong. The research involved hardness test and thickness inspection of the pipe wall. The results of the research are 139 BHN and 1,085 mm for minimum hardness and minimum thickness of the pipe wall respectively. Booth of these data are used to determine the current maximum stress of the pipe. The comparison of the current stress and the design is magnitude of degradation capability. Since the degradation capability of the RSG-GAS secondary cooling piping system has been known, the maintenance management system could be established and reactor operation which is safe and reliable can be maintained. (author)

  12. Decay Heat Removal in GEN IV Gas-Cooled Fast Reactors

    Directory of Open Access Journals (Sweden)

    Lap-Yan Cheng

    2009-01-01

    Full Text Available The safety goal of the current designs of advanced high-temperature thermal gas-cooled reactors (HTRs is that no core meltdown would occur in a depressurization event with a combination of concurrent safety system failures. This study focused on the analysis of passive decay heat removal (DHR in a GEN IV direct-cycle gas-cooled fast reactor (GFR which is based on the technology developments of the HTRs. Given the different criteria and design characteristics of the GFR, an approach different from that taken for the HTRs for passive DHR would have to be explored. Different design options based on maintaining core flow were evaluated by performing transient analysis of a depressurization accident using the system code RELAP5-3D. The study also reviewed the conceptual design of autonomous systems for shutdown decay heat removal and recommends that future work in this area should be focused on the potential for Brayton cycle DHRs.

  13. Cryogenic Thermal Studies on Terminations for Helium Gas Cooled Superconducting Cables

    Science.gov (United States)

    Kim, Chul Han; Kim, Sung-Kyu; Graber, Lukas; Pamidi, Sastry V.

    Details of the design of terminations for testing a superconducting DC monopole cable cooled with gaseous helium are presented. The termination design includes a liquid nitrogen chamber to reduce heat influx into the helium section through current leads. Thermal studies on the assembly of the two terminations and a 1 m or 30 m cable cryostat were performed at variable mass flow rates of helium gas. Measurements of temperature profile for the test system without the superconducting cable showed temperature rise between 5 K and 20 K depending on the mass flow rate. The temperature profile across the test system was used to estimate the heat load from different components of the system. Results with and without the liquid nitrogen in current lead section were compared to estimate the savings provided by the liquid nitrogen on the head of the helium circulation system. Suggestions for improving the design to enable fully gas cooled terminations are presented.

  14. Frequency and distribution of leakages in steam generators of gas-cooled reactors

    International Nuclear Information System (INIS)

    In gas cooled reactors with graphitic primary circuit structures - such as HTR, AGR or Magnox - the water ingress is an event of great safety concern. Water or steam entering the primary circuit react with the hot graphite and carbon-oxide and hydrogen are produced. As the most important initiating event a leak in a steam generator must be taken into account. From the safety point of view as well as for availability reasons it is necessary to construct reliable boilers. Thus the occurrence of a boiler leak should be a rare event. In the context of a probabilistic safety study for an HTR-Project much effort was invested to get information about the frequency and the size distribution of tube failures in steam generators of gas cooled reactors. The main data base was the boiler tube failure statistics of United Kingdom gas cooled reactors. The data were selected and applied to a modern HTR steam generator design. A review of the data showed that the failure frequency is not connected with the load level (pressures, temperatures) or with the geometric size of the heating surface of the boiler. Design, construction, fabrication, examination and operation conditions have the greatest influence an the failure frequency but they are practically not to be quantified. The typical leak develops from smallest size. By erosion effects of the entering water or steam it is enlarged to perhaps some mm2, then usually it is detected by moisture monitors. Sudden tube breaks were not reported in the investigated period. As a rule boiler leaks in gas cooled reactors are much more, rare then leaks in steam generators of light water reactors and fossil fired boilers. (author)

  15. High Temperature Gas-Cooled Test Reactor Point Design: Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Sterbentz, James William [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bayless, Paul David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Nelson, Lee Orville [Idaho National Lab. (INL), Idaho Falls, ID (United States); Gougar, Hans David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Strydom, Gerhard [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-01-01

    A point design has been developed for a 200-MW high-temperature gas-cooled test reactor. The point design concept uses standard prismatic blocks and 15.5% enriched uranium oxycarbide fuel. Reactor physics and thermal-hydraulics simulations have been performed to characterize the capabilities of the design. In addition to the technical data, overviews are provided on the technology readiness level, licensing approach, and costs of the test reactor point design.

  16. High Temperature Gas-Cooled Test Reactor Point Design: Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Sterbentz, James William [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bayless, Paul David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Nelson, Lee Orville [Idaho National Lab. (INL), Idaho Falls, ID (United States); Gougar, Hans David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kinsey, J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Strydom, Gerhard [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-03-01

    A point design has been developed for a 200-MW high-temperature gas-cooled test reactor. The point design concept uses standard prismatic blocks and 15.5% enriched uranium oxycarbide fuel. Reactor physics and thermal-hydraulics simulations have been performed to characterize the capabilities of the design. In addition to the technical data, overviews are provided on the technology readiness level, licensing approach, and costs of the test reactor point design.

  17. Analysis of passive residual heat removal system of modular high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    The passive residual heat removal system plays an important role for the inherent safety of high temperature gas-cooled reactor (HTGR). The thermal hydraulic calculation method for the residual heat removal system of HTGR was introduced. The operating temperatures of the residual heat removal system at different residual heat powers and different environmental temperatures were calculated. The containment concrete temperature was numerically simulated. The results show that the highest concrete temperature is acceptable. (authors)

  18. Reference modular High Temperature Gas-Cooled Reactor Plant: Concept description report

    International Nuclear Information System (INIS)

    This report provides a summary description of the Modular High Temperature Gas-Cooled Reactor (MHTGR) concept and interim results of assessments of costs, safety, constructibility, operability, maintainability, and availability. Conceptual design of this concept was initiated in October 1985 and is scheduled for completion in 1987. Participating industrial contractors are Bechtel National, Inc. (BNI), Stone and Webster Engineering Corporation (SWEC), GA Technologies, Inc. (GA), General Electric Co. (GE), and Combustion Engineering, Inc

  19. Improvement of the Decay Heat Removal Characteristics of the Generation IV Gas-cooled Fast Reactor

    OpenAIRE

    Epiney, Aaron Simon

    2010-01-01

    Gas cooling in nuclear power plants (NPPs) has a long history, the corresponding reactor types developed in France, the UK and the US having been thermal neutron-spectrum systems using graphite as the moderator. The majority of NPPs worldwide, however, are currently light water reactors, using ordinary water as both coolant and moderator. These NPPs – of the so-called second generation – will soon need replacement, and a third generation is now being ...

  20. Design features facilitating the decommissioning of advanced gas-cooled reactors

    International Nuclear Information System (INIS)

    The design of the advanced gas-cooled reactors is discussed as is the proposed decommissioning plan for delayed decommissioning. The special features which assist in decommissioning are presented. As a result of the study a catalogue of design features which will facilitate decommissioning is given. In addition to the catalogue of design features, the radioactive inventory 10 years after shutdown and 100 years after shutdown has been calculated. From this a provisional operator dose from activities associated with decommissioning has been assessed

  1. The key device--elevator in 10 MW high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    The basic structure, working principle and behavior of the control system of the elevator in 10 MW high temperature gas-cooled reactor (HTR-10) are researched. The five-phase hybrid stepping motor and the closed-loop control are adopted in the construction design of the elevator. About 20000 fuel elements and graphite balls were transported into the reactor core by the elevator to achieve the critical loading for HTR-10

  2. Reference modular High Temperature Gas-Cooled Reactor Plant: Concept description report

    Energy Technology Data Exchange (ETDEWEB)

    1986-10-01

    This report provides a summary description of the Modular High Temperature Gas-Cooled Reactor (MHTGR) concept and interim results of assessments of costs, safety, constructibility, operability, maintainability, and availability. Conceptual design of this concept was initiated in October 1985 and is scheduled for completion in 1987. Participating industrial contractors are Bechtel National, Inc. (BNI), Stone and Webster Engineering Corporation (SWEC), GA Technologies, Inc. (GA), General Electric Co. (GE), and Combustion Engineering, Inc. (C-E).

  3. Application of gas-cooled Accelerator Driven System (ADS) transmutation devices to sustainable nuclear energy development

    OpenAIRE

    Abánades, A.; Garcia Hernandez, Carlos Rafael; GARCÍA FAJARDO, LAURA; Escrivá, A.; Pérez-Navarro Gómez, Ángel; Rosales, J.

    2011-01-01

    The conceptual design of a pebble bed gas-cooled transmutation device is shown with the aim to evaluate its potential for its deployment in the context of the sustainable nuclear energy development, which considers high temperature reactors for their operation in cogeneration mode, producing electricity, heat and Hydrogen. As differential characteristics our device operates in subcritical mode, driven by a neutron source activated by an accelerator that adds clear safety advantages and fuel f...

  4. Application of gas-cooled Accelerator Driven System (ADS) transmutation devices to sustainable nuclear energy development

    OpenAIRE

    Abánades Velasco, Alberto; C. García; García, L.; Escrivá, A.; Pérez-Navarro, A.; Rosales, J.

    2011-01-01

    The conceptual design of a pebble bed gas-cooled transmutation device is shown with the aim to evaluate its potential for its deployment in the context of the sustainable nuclear energy development, which considers high temperature reactors for their operation in cogeneration mode, producing electricity, heat and Hydrogen. As differential characteristics our device operates in subcritical mode, driven by a neutron source activated by an accelerator that adds clear safety advantages and fu...

  5. Preliminary Evaluation of a Nuclear Scenario Involving Innovative Gas Cooled Reactors

    OpenAIRE

    Eugene Shwageraus; Vincenzo Romanello; Guglielmo Lomonaco; Emil Fridman; Giuseppe Forasassi; Nicola Cerullo; Barbara Vezzoni

    2009-01-01

    In order to guarantee a sustainable supply of future energy demand without compromising the environment, some actions for a substantial reduction of C O 2 emissions are nowadays deeply analysed. One of them is the improvement of the nuclear energy use. In this framework, innovative gas-cooled reactors (both thermal and fast) seem to be very attractive from the electricity production point of view and for the potential industrial use along the high temperature processes (e.g., H 2 production b...

  6. High Temperature Gas-Cooled Test Reactor Point Design: Summary Report

    International Nuclear Information System (INIS)

    A point design has been developed for a 200-MW high-temperature gas-cooled test reactor. The point design concept uses standard prismatic blocks and 15.5% enriched uranium oxycarbide fuel. Reactor physics and thermal-hydraulics simulations have been performed to characterize the capabilities of the design. In addition to the technical data, overviews are provided on the technology readiness level, licensing approach, and costs of the test reactor point design.

  7. Thermal-hydraulic code selection for modular high temperature gas-cooled reactors

    International Nuclear Information System (INIS)

    In order to study the transient thermal-hydraulic system behaviour of modular high temperature gas-cooled reactors, the thermal-hydraulic computer codes RELAP5, MELCOR, THATCH, MORECA, and VSOP are considered at the Netherlands Energy Research Foundation ECN. This report presents the selection of the most appropriate codes. To cover the range of relevant accidents, a suite of three codes is recommended for analyses of HTR-M and MHTGR reactors. (orig.)

  8. Heat transport and afterheat removal for gas cooled reactors under accident conditions

    International Nuclear Information System (INIS)

    The Co-ordinated Research Project (CRP) on Heat Transport and Afterheat Removal for Gas Cooled Reactors Under Accident Conditions was organized within the framework of the International Working Group on Gas Cooled Reactors (IWGGCR). This International Working Group serves as a forum for exchange of information on national programmes, provides advice to the IAEA on international co-operative activities in advanced technologies of gas cooled reactors (GCRs) and supports the conduct of these activities. Advanced GCR designs currently being developed are predicted to achieve a high degree of safety through reliance on inherent safety features. Such design features should permit the technical demonstration of exceptional public protection with significantly reduced emergency planning requirements. For advanced GCRs, this predicted high degree of safety largely derives from the ability of the ceramic coated fuel particles to retain the fission products under normal and accident conditions, the safe neutron physics behaviour of the core, the chemical stability of the core and the ability of the design to dissipate decay heat by natural heat transport mechanisms without reaching excessive temperatures. Prior to licensing and commercial deployment of advanced GCRs, these features must first be demonstrated under experimental conditions representing realistic reactor conditions, and the methods used to predict the performance of the fuel and reactor must be validated against these experimental data. Within this CRP, the participants addressed the inherent mechanisms for removal of decay heat from GCRs under accident conditions. The objective of this CRP was to establish sufficient experimental data at realistic conditions and validated analytical tools to confirm the predicted safe thermal response of advance gas cooled reactors during accidents. The scope includes experimental and analytical investigations of heat transport by natural convection conduction and thermal

  9. The modular high-temperature gas-cooled reactor: A cost/risk competitive nuclear option

    International Nuclear Information System (INIS)

    The business risks of nuclear plant ownership are identified as a constraint on the expanded use of nuclear power. Such risks stem from the exacting demands placed on owner/operator organizations of current plants to demonstrate ongoing compliance with safety regulations and the resulting high costs for operation and maintenance. This paper describes the Modular High-Temperature Gas-Cooled Reactor (MHTGR) design, competitive economics, and approach to reducing the business risks of nuclear plant ownership

  10. Fabrication of spherical fuel element for 10 MW high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Cold quasi-isostatic molding with a silicon rubber die was used for manufacturing the spherical fuel elements of 10 MW high temperature gas-cooled reactor. 44 batches of fuel elements, about 20540 of the fuel elements, were produced. The cold properties of the graphite matrix materials satisfies the design specifications. The mean free uranium fraction in spherical fuel element from 44 batches is 4.57 x 10-5, certified products is 99%

  11. Simulation study on the performance of solar/natural gas absorption cooling chillers

    International Nuclear Information System (INIS)

    Highlights: ► The overall performance of the solar/natural gas chillers is analysed and discussed. ► The system operates in regions with abundant solar energy and cheap natural gas. ► The maximum daily cover of solar energy (between time of day 8 and 17) is about 58%. ► An optimum generator temperature gives a minimum number of flat plate collectors. ► This system compensates the peak-valley load difference and reduces CO2 gas emissions. - Abstract: Solar radiation is a clean form of energy and solar cooling systems is one of the technologies which allow obtaining an important energy saving. Natural gas is a cheaper fuel than oil. It also burns cleaner than oil. Natural gas and renewable energy are complementary and in the future, the alignment of natural gas and renewable energy may be the most effective way to service the demand for clean energy. This paper presents a numerical study of solar/natural gas single effect lithium bromide absorption chillers. The development of this system is based on hot water chiller. As auxiliary power, fire from the natural gas burners is used to heat the hot water on its way to the generator. The overall performance of the absorption chiller system is analysed and discussed. For an evaporator temperature of 5 °C and when the condenser temperature is varied from 28 °C to 36 °C and generator temperatures is varied from 54 to 83 °C the maximum COP is 0.82 and the maximum exergetic efficiency is about 30%. For a given condenser temperature there is an optimum generator temperature for which the number of flat plate collectors is minimum. This optimum generator temperature corresponds to the generator temperature giving the maximum COP and exergy efficiency of the absorption cooling system. The solar/natural gas single effect lithium bromide absorption chillers, using solar energy as the energy source with only limited amount of gas as auxiliary power, not only reduces greatly the cost for electricity and operates in

  12. Design of a large-scale, multi-purpose high temperature gas-cooled reactor system

    International Nuclear Information System (INIS)

    The trial design of a large-scale, multi-purpose high temperature gas-cooled reactor system is described on its three aspects: nuclear reactor, nuclear heat utilization, and safety. The system is a littoral iron and steel making plant employing a multi-purpose HTGR (heat output 3,000 MW) with helium gas temperature of 1,0000C; the capacity is about 6,300,000 tons of crude steel production per year. It consists of a direct reduction furnace for ore and an electric furnace, and also an electric power generating facility. (Mori, K.)

  13. The main cooling system of the RSG-GAS: a study of dissabilities

    International Nuclear Information System (INIS)

    The RSG-GAS has been operating since August 1987 until now. During that period it has been many papers explain the performance and the safety features of the system. Those papers does not mean any think to the system, but the wickednesses of the system. Is still remain stick on it. This paper describes the wickednesses of the RSG-GAS main cooling system with an objective that their will be a corrective action of the management to improve the system so that such wickednesses can be minimized or even be avoided

  14. Reactor core of a gas-cooled high-temperature reactor

    International Nuclear Information System (INIS)

    In order to increase the outlet temperature of the coolant (helium) leaving the reactor core of a gas-cooled high-temperature nuclear reactor and thereby to improve its thermal efficiency there is proposed to design the geometry of the fuel elements or the fuel element units and/or their main dimensions non-uniformly. Those fuel elements whose geometry causes a larger pressure drop of the coolant gas are to be arranged towards the outlet side of the hot coolant. (GL) 891 GL/GL 892 MKO

  15. The Fort St. Vrain high temperature gas-cooled reactor. Pt. 10

    International Nuclear Information System (INIS)

    In October 1977, during the rise to power test program, the Fort St. Vrain high temperature gas-cooled reactor experienced the first of 37 fluctuation events involving primary coolant outlet temperature, nuclear detector signals, steam generator module gas inlet temperature and steam generator module main and reheat steam temperatures. In a 3 year investigation it was determined that the apparent cause of the fluctuations was movements of core components accompanied by periodic changes in bypass flows and crossflows of primary coolant helium. Installation of region constraint devices has eliminated fluctuations, but a single small primary coolant helium core outlet temperature redistribution is experienced routinely during rise to power. (orig.)

  16. Severe accident assessment: development of the gas flux dryout model for cooling of core debris

    International Nuclear Information System (INIS)

    A model for boiling and dryout in a particle debris bed with permeable boundary conditions is developed and compared with various dryout models, and incorporated into the modified MARCH/KAERI computer code to analyze for the combined mechanisms of thermal interactions. Comparative and parametric studies show that the particle sizes have an important effect on debris bed cooling but not apparent effect on the magnitude of peak pressure in the containment building. It is also shown that the gas flux model represents an improvement of the combined thermal interactions among core debris, water and gas over the previous models. (Author)

  17. Specialists' meeting on heat exchanging components of gas-cooled reactors

    International Nuclear Information System (INIS)

    The objective of the Meeting sponsored by IAEA was to provide a forum for the exchange and discussion of technical information related to heat exchanging and heat conducting components for gas-cooled reactors. The technical part of the meeting covered eight subjects: Heat exchanging components for process heat applications, design and requirements, and research and development programs; Status of the design and construction of intermediate He/He exchangers; Design, construction and performance of steam generators; Metallic materials and design codes; Design and construction of valves and hot gas ducts; Description of component test facilities and test results; Manufacturing of heat exchanging components

  18. Evaluation of proposed German safety criteria for high-temperature gas-cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Barsell, A.W.

    1980-05-01

    This work reviews proposed safety criteria prepared by the German Bundesministerium des Innern (BMI) for future licensing of gas-cooled high-temperature reactor (HTR) concepts in the Federal Republic of Germany. Comparison is made with US General Design Criteria (GDCs) in 10CFR50 Appendix A and with German light water reactor (LWR) criteria. Implications for the HTR design relative to the US design and safety approach are indicated. Both inherent characteristics and design features of the steam cycle, gas turbine, and process heat concepts are taken into account as well as generic design options such as a pebble bed or prismatic core.

  19. Alternative Liquid Fuel Effects on Cooled Silicon Nitride Marine Gas Turbine Airfoils

    Energy Technology Data Exchange (ETDEWEB)

    Holowczak, J.

    2002-03-01

    With prior support from the Office of Naval Research, DARPA, and U.S. Department of Energy, United Technologies is developing and engine environment testing what we believe to be the first internally cooled silicon nitride ceramic turbine vane in the United States. The vanes are being developed for the FT8, an aeroderivative stationary/marine gas turbine. The current effort resulted in further manufacturing and development and prototyping by two U.S. based gas turbine grade silicon nitride component manufacturers, preliminary development of both alumina, and YTRIA based environmental barrier coatings (EBC's) and testing or ceramic vanes with an EBC coating.

  20. Helium sampling and analyzing system of 10 MW high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    The helium purification system of 10 MW high temperature gas-cooled reactor consists of the purification equipments and their accessories. The purification equipments include a copper oxide bed, a molecular sieve absorber, a low temperature absorbed, and etc. The gas sampling and analyzing system is consisted of the gas chromatograph, moisture probe, and infrared analyzing instrument. The moisture probe and infrared analyzing instrument both conform to the design requirement, and consecutive inspection of H2O, CO, CO2 can be carried out for the primary helium circuit. The gas chromatograph can also meet the design requirement, and so the intermittent sampling and analyzing of H2, O2, N2, CH4, CO and CO2 can be carried out for the primary helium circuit. (authors)

  1. A novel nuclear combined power and cooling system integrating high temperature gas-cooled reactor with ammonia–water cycle

    International Nuclear Information System (INIS)

    Highlights: • We propose a novel nuclear ammonia–water power and cooling cogeneration system. • The high temperature reactor is inherently safe, with exhaust heat fully recovered. • The thermal performances are improved compared with nuclear combined cycle. • The base case attains an energy efficiency of 69.9% and exergy efficiency of 72.5%. • Energy conservation and emission reduction are achieved in this cogeneration way. - Abstract: A nuclear ammonia–water power and refrigeration cogeneration system (NAPR) has been proposed and analyzed in this paper. It consists of a closed high temperature gas-cooled reactor (HTGR) topping Brayton cycle and a modified ammonia water power/refrigeration combined bottoming cycle (APR). The HTGR is an inherently safe reactor, and thus could be stable, flexible and suitable for various energy supply situation, and its exhaust heat is fully recovered by the mixture of ammonia and water in the bottoming cycle. To reduce exergy losses and enhance outputs, the ammonia concentrations of the bottoming cycle working fluid are optimized in both power and refrigeration processes. With the HTGR of 200 MW thermal capacity and 900 °C/70 bar reactor-core-outlet helium, the system achieves 88.8 MW net electrical output and 9.27 MW refrigeration capacity, and also attains an energy efficiency of 69.9% and exergy efficiency of 72.5%, which are higher by 5.3%-points and 2.6%-points as compared with the nuclear combined cycle (NCC, like a conventional gas/steam power-only combined cycle while the topping cycle is a closed HTGR Brayton cycle) with the same nuclear energy input. Compared with conventional separate power and refrigeration generation systems, the fossil fuel saving (based on CH4) and CO2 emission reduction of base-case NAPR could reach ∼9.66 × 104 t/y and ∼26.6 × 104 t/y, respectively. The system integration accomplishes the safe and high-efficiency utilization of nuclear energy by power and refrigeration

  2. Economic analysis of multiple-module high temperature gas-cooled reactor (MHTR) nuclear power plants

    International Nuclear Information System (INIS)

    In recent years, as the increasing demand of energy all over the world, and the pressure on greenhouse emissions, there's a new opportunity for the development of nuclear energy. Modular High Temperature Gas-cooled Reactor (MHTR) received recognition for its inherent safety feature and high outlet temperature. Whether the Modular High Temperature Gas-cooled Reactor would be accepted extensively, its economy is a key point. In this paper, the methods of qualitative analysis and the method of quantitative analysis, the economic models designed by Economic Modeling Working Group (EMWG) of the Generation IV International Forum (GIF), as well as the HTR-PM's main technical features, are used to analyze the economy of the MHTR. A prediction is made on the basis of summarizing High Temperature Gas-cooled Reactor module characteristics, construction cost, total capital cost, fuel cost and operation and maintenance (O and M) cost and so on. In the following part, comparative analysis is taken measures to the economy and cost ratio of different designs, to explore the impacts of modularization and standardization on the construction of multiple-module reactor nuclear power plant. Meanwhile, the analysis is also adopted in the research of key factors such as the learning effect and yield to find out their impacts on the large scale development of MHTR. Furthermore, some reference would be provided to its wide application based on these analysis. (author)

  3. Present status of research and development of high temperature gas-cooled reactors, 1989

    International Nuclear Information System (INIS)

    The development of high temperature gas-cooled reactors has very important significance for the energy policy of Japan to diversify energy sources and stably ensure energy. The development has been advanced since 1969 by Japan Atomic Energy Research Institute, but in the 'Long term plan of atomic energy development and utilization' of June, 1987, as high temperature engineering test and research, it was decided to construct a High Temperature Engineering Test Reactor (HTTR). According to this policy, JAERI carried out the detailed design and safety analysis of the HTTR with 30 MWt output and reactor exit coolant temperature of 950degC. The application for the permission to construct the HTTR in Oarai Research Establishment was made in February, 1989, and it is expected to begin the construction in 1990. The period of the construction requires about 5 years, and the criticality is scheduled in 1995. In JAERI, the high temperature engineering test and research including the utilization of the HTTR and the heightening of temperature in high temperature gas-cooled reactors are promoted. The trend of development of high temperature gas-cooled reactors in foreign countries and the research activities in JAERI are reported. (K.I.)

  4. Design and development of gas cooled reactors with closed cycle gas turbines. Proceedings of a technical committee meeting

    International Nuclear Information System (INIS)

    Technological advances over the past fifteen years in the design of turbomachinery, recuperators and magnetic bearings provide the potential for a quantum improvement in nuclear power generation economics through the use of the HTGR with a closed cycle gas turbine. Enhanced international co-operation among national gas cooled reactor programmes in these common technology areas could facilitate the development of this nuclear power concept thereby achieving safety, environmental and economic benefits with overall reduced development costs. This TCM and Workshop was convened to provide the opportunity to review and examine the status of design activities and technology development in national HTGR programmes with specific emphasis on the closed cycle gas turbine, and to identify pathways which take advantage of the opportunity for international co-operation in the development of this concept. Refs, figs, tabs

  5. Rotor disk cooling and rim sealing to prevent hot gas ingestion. Rotor reikyaku to hot gas no seal

    Energy Technology Data Exchange (ETDEWEB)

    Hamabe, K. (Kawasaki Heavy Industries, Ltd., Tokyo (Japan))

    1993-03-01

    In designing a high-temperature gas turbine disc, it is necessary to know pressure distribution around a disc, which correlates with flows inside and outside the disc. With design conditions becoming very stringent for efficiency improvement as a background, this paper describes latest trends in technologies on heat transfer around a disc and hot gas sealing while introducing reports on various studies. Generally speaking, fundamental researches on rotors without mainstreams have conventionally been carried out mainly in Europe and the U.S.A. Researches have become active recently on entrainment of mainstream gas where there is a mainstream that renders practical problems. The number of research papers is increasing sharply that relate to rotor shapes closer to those used in practical turbines incorporating moving and static blades, and high rotation Reynolds numbers. Further, studies using numerical analysis are on the increase, and rotor cooling studies are advancing remarkably in recent years. 36 refs., 10 figs.

  6. THE DIFFERENT EVOLUTION OF GAS AND DUST IN DISKS AROUND SUN-LIKE AND COOL STARS

    International Nuclear Information System (INIS)

    Planet formation is profoundly impacted by the properties of protoplanetary disks and their central star. However, how disk properties vary with stellar parameters remains poorly known. Here, we present the first comprehensive, comparative Spitzer/IRS study of the dust and gas properties of disks around young Sun-like stars (K1-M5) and cool stars/brown dwarfs (M5-M9). The comparison of these two large samples of over 60 sources reveal major differences in the evolution of both the dust and gas components. We report the first detection of organic molecules in disks around brown dwarfs. The detection rate statistics and the line flux ratios of HCN and C2H2 show a striking difference between the two samples, demonstrating a significant underabundance of HCN relative to C2H2 in the disk surface of cool stars. We propose this to originate from the large difference in the UV irradiation around the two types of sources. The statistical comparison of the 10 μm silicate emission features also reveals a difference between the two samples. Cool stars and brown dwarfs show weaker features arising from more processed silicate grains in the disk atmosphere. These findings complement previous indications of flatter disk structures and longer disk lifetimes around cool stars. Our results highlight important differences in the chemical and physical evolution of protoplanetary disks as a function of stellar mass, temperature, and radiation field which should be taken into account in planet formation models. We note that the different chemistry of preplanetary materials in the disk may also influence the bulk composition and volatile content of the forming planets. In particular, if exogenous HCN has played a key role in the synthesis of prebiotic molecules on Earth as proposed, then prebiotic chemistry may unfold differently on planets around cool stars.

  7. Oxidation state specific generation of arsines from methylated arsenicals based on L-cysteine treatment in buffered media for speciation analysis by hydride generation-automated cryotrapping-gas chromatography-atomic absorption spectrometry with the multiatomizer

    International Nuclear Information System (INIS)

    An automated system for hydride generation-cryotrapping-gas chromatography-atomic absorption spectrometry with the multiatomizer is described. Arsines are preconcentrated and separated in a Chromosorb filled U-tube. An automated cryotrapping unit, employing nitrogen gas formed upon heating in the detection phase for the displacement of the cooling liquid nitrogen, has been developed. The conditions for separation of arsines in a Chromosorb filled U-tube have been optimized. A complete separation of signals from arsine, methylarsine, dimethylarsine, and trimethylarsine has been achieved within a 60 s reading window. The limits of detection for methylated arsenicals tested were 4 ng l-1. Selective hydride generation is applied for the oxidation state specific speciation analysis of inorganic and methylated arsenicals. The arsines are generated either exclusively from trivalent or from both tri- and pentavalent inorganic and methylated arsenicals depending on the presence of L-cysteine as a prereductant and/or reaction modifier. A TRIS buffer reaction medium is proposed to overcome narrow optimum concentration range observed for the L-cysteine modified reaction in HCl medium. The system provides uniform peak area sensitivity for all As species. Consequently, the calibration with a single form of As is possible. This method permits a high-throughput speciation analysis of metabolites of inorganic arsenic in relatively complex biological matrices such as cell culture systems without sample pretreatment, thus preserving the distribution of tri- and pentavalent species

  8. A charge regulating system for turbo-generator gas-cooled high-temperature reactor power stations

    International Nuclear Information System (INIS)

    The invention relates to a regulating system for gas-cooled high-temperature reactors power stations (helium coolant), equipped with several steam-boilers, each of which deriving heat from a corresponding cooling-gas flow circulating in the reactor, so as to feed superheated steam into a main common steam-manifold and re-superheated steam into a re-superheated hot common manifold

  9. Experimental and numerical investigation of heat transfer and pressure drop for innovative gas cooled systems

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, R., E-mail: rodrigo.leija@kit.edu [Karlsruhe Institute of Technology, Institute for Neutron Physics and Reactor Technology, Hermann-von-Helmholtz No. 1, 76344 Eggenstein-Leopoldshafen (Germany); Buchholz, S. [Gesellschaft für Anlagen- und Reaktorsicherheit GRS mbH, Boltzmannstraße 2, 85748 Garching (Germany); Suikkanen, H. [Lappeenranta University of Technology, LUT Energy, PO Box 20, FI-53851 Lappeenranta (Finland)

    2015-08-15

    Highlights: • Experimental results of the L-STAR within the first stage of THINS project. • CFD validation for the heat transfer and pressure losses in innovative gas cooled systems. • The results indicate a strong dependency Turbulent Prandtl at the rod wall temperature distribution. • Gas loop facility suitable for the investigation of thermohydraulic issues of GFR, however there might be flow instabilities when flow is very low. - Abstract: Heat transfer enhancement through turbulence augmentation is recognized as a key factor for improving the safety and economic conditions in the development of both critical and subcritical innovative advanced gas cooled fast reactors (GFR) and transmutation systems. The L-STAR facility has been designed and erected at the Karlsruhe Institute of Technology (KIT) to study turbulent flow behavior and its heat transfer enhancement characteristics in gas cooled annular channels under a wide range of conditions. The test section consists of an annular hexagonal cross section channel with an inner electrical heater rod element, placed concentrically within the test section, which seeks to simulate the flow area of a fuel rod element in a GFR. The long term objective of the experimental study is to investigate and improve the understanding of complex turbulent convective enhancement mechanisms as well as the friction loss penalties of roughened fuel rods compared to smooth ones and to generate an accurate database for further development of physical models. In the first step, experimental results of the fluid flow with uniform heat release conditions for the smooth heater rod are presented. The pressure drops, as well as the axial temperature profiles along the heater rod surface have been measured at Reynolds numbers in the range from 4000 to 35,000. The experimental results of the first stage were compared with independently conducted CFD analyses performed at Lappeenranta University of Technology (LUT) with the code ANSYS

  10. Experimental and numerical investigation of heat transfer and pressure drop for innovative gas cooled systems

    International Nuclear Information System (INIS)

    Highlights: • Experimental results of the L-STAR within the first stage of THINS project. • CFD validation for the heat transfer and pressure losses in innovative gas cooled systems. • The results indicate a strong dependency Turbulent Prandtl at the rod wall temperature distribution. • Gas loop facility suitable for the investigation of thermohydraulic issues of GFR, however there might be flow instabilities when flow is very low. - Abstract: Heat transfer enhancement through turbulence augmentation is recognized as a key factor for improving the safety and economic conditions in the development of both critical and subcritical innovative advanced gas cooled fast reactors (GFR) and transmutation systems. The L-STAR facility has been designed and erected at the Karlsruhe Institute of Technology (KIT) to study turbulent flow behavior and its heat transfer enhancement characteristics in gas cooled annular channels under a wide range of conditions. The test section consists of an annular hexagonal cross section channel with an inner electrical heater rod element, placed concentrically within the test section, which seeks to simulate the flow area of a fuel rod element in a GFR. The long term objective of the experimental study is to investigate and improve the understanding of complex turbulent convective enhancement mechanisms as well as the friction loss penalties of roughened fuel rods compared to smooth ones and to generate an accurate database for further development of physical models. In the first step, experimental results of the fluid flow with uniform heat release conditions for the smooth heater rod are presented. The pressure drops, as well as the axial temperature profiles along the heater rod surface have been measured at Reynolds numbers in the range from 4000 to 35,000. The experimental results of the first stage were compared with independently conducted CFD analyses performed at Lappeenranta University of Technology (LUT) with the code ANSYS

  11. Helium circulator design concepts for the modular high temperature gas-cooled reactor (MHTGR) plant

    International Nuclear Information System (INIS)

    Two helium circulators are featured in the Modular High-Temperature Gas-Cooled Reactor (MHTGR) power plant - (1) the main circulator, which facilitates the transfer of reactor thermal energy to the steam generator, and (2) a small shutdown cooling circulator that enables rapid cooling of the reactor system to be realized. The 3170 kW(e) main circulator has an axial flow compressor, the impeller being very similar to the unit in the Fort St. Vrain (FSV) plant. The 164 kW(e) shutdown cooling circulator, the design of which is controlled by depressurized conditions, has a radial flow compressor. Both machines are vertically oriented, have submerged electric motor drives, and embody rotors that are supported on active magnetic bearings. As outlined in this paper, both machines have been conservatively designed based on established practice. The circulators have features and characteristics that have evolved from actual plant operating experience. With a major goal of high reliability, emphasis has been placed on design simplicity, and both machines are readily accessible for inspection, repair, and replacement, if necessary. In this paper, conceptual design aspects of both machines are discussed, together with the significant technology bases. As appropriate for a plant that will see service well into the 21st century, new and emerging technologies have been factored into the design. Examples of this are the inclusion of active magnetic bearings, and an automated circulator condition monitoring system. (author). 18 refs, 20 figs, 13 tabs

  12. Effects of buffer layer preparation and Bi concentration on InGaAsBi epilayers grown by gas source molecular beam epitaxy

    International Nuclear Information System (INIS)

    The effect of using an In0.53Ga0.47As buffer layer on the crystalline quality of InGaAsBi epilayer with Bi concentration up to 3.1% grown by gas source molecular beam epitaxy was investigated. It is found that use of the buffer layer has a dramatic effect on the improvement of surface morphology, structural, electrical and optical properties of InGaAsBi epilayers. Bi incorporation in InGaAs up to a concentration of 3.1% causes no degradation of the electron mobility and induces p-type carriers that compensate the background n-type carriers resulting in mobility enhancement with increasing Bi concentration. With the buffer layer preparation, a maximum electron mobility of 5550 cm2 V–1 s–1 at room temperature is demonstrated in InGaAsBi with x Bi = 3.1%, which is the highest value reported in InGaAsBi with x Bi > 2.5%. (paper)

  13. Properties of gas source molecular beam epitaxy grown wavelength extended InGaAs photodetector structures on a linear graded InAlAs buffer

    International Nuclear Information System (INIS)

    The properties of gas source molecular beam epitaxy grown wavelength extended (2.4 µm) InGaAs photodetector structures on a linear graded InAlAs buffer with different grading rates have been investigated by means of XRD and PL techniques in conjunction with optical and atomic force microscopy. Results show that full relaxation and favorable optical characteristics of the active layers only occur for the wafers with a mismatch grading rate of about 1.2% µm−1 or lower, whereas moderate morphology and structural quality could be achieved for a mismatch grading rate up to 2.4% µm−1. A thin GSMBE grown linear graded InAlAs buffer layer of 1.4 µm is sufficient to relax the strain of an InGaAs layer with 1.7% mismatch to the InP substrate and reach a good quality of the wafer. The relaxation mechanisms of the buffer at different grading rates were also discussed

  14. Modular high-temperature gas-cooled reactor simulation using parallel processors

    International Nuclear Information System (INIS)

    The MHPP (Modular HTGR Parallel Processor) code has been developed to simulate modular high-temperature gas-cooled reactor (MHTGR) transients and accidents. MHPP incorporates a very detailed model for predicting the dynamics of the reactor core, vessel, and cooling systems over a wide variety of scenarios ranging from expected transients to very-low-probability severe accidents. The simulation routines, which had originally been developed entirely as serial code, were readily adapted to parallel processing Fortran. The resulting parallelized simulation speed was enhanced significantly. Workstation interfaces are being developed to provide for user (''operator'') interaction. The benefits realized by adapting previous MHTGR codes to run on a parallel processor are discussed, along with results of typical accident analyses. 3 refs., 3 figs

  15. Safety design features for current UK advanced gas-cooled reactors

    International Nuclear Information System (INIS)

    The nuclear power stations planned for Heysham II and Torness will each have twin 660 MW(e) Advanced Gas-cooled Reactors (AGR) based on the design of those which have been operating at Hinkley Point 'B' and Hunterston 'B' since 1976. This paper has described the way in which the shutdown and cooling systems for the Heysham II and Torness AGRs have been selected in order to meet current UK safety requirements. Fault tree analyses have been used to identify the credible fault sequences, the probabilities of which have been calculated. By this means the relative importance of the various protective systems has been established and redundancy and reliability requirements identified. This systematic approach has led to a balanced design giving protection over the complete spectrum of fault sequences. Current safety requirements for thermal reactors in the UK and particular requirements in the design of the Heysham II and Torness reactors are discussed

  16. Safety analysis of spent fuel element storage in 10 MW high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Approximately 90000 spent fuel elements will be discharged from a 10 MW high temperature gas-cooled reactor (HTR-10) in its lifetime. The activity of the radioactive fission products in these spent fuel elements will reach 1.0 x 1016 Bq, so these spent fuel elements should be properly managed. HTR-10 spent fuel elements will be discharged into lead-steel containers, with each container designed to receive 2000 fuel elements. These containers will be stored in a concrete compartment inside the reactor building and cooled by air. The author analyzes the release of the radioactive nuclides, the critical safety parameters and the irradiation shielding. The results show that the safety requirements can be met in the HTR-10 spent fuel element storage compartment

  17. Evidence for a heated gas bubble inside the "cooling flow" region of MKW3s

    CERN Document Server

    Mazzotta, P; Paerels, F B S; Ferrigno, C; Colafrancesco, Sergio; Mewe, R; Forman, W R

    2002-01-01

    We report on the deep Chandra observation of central r=200kpc region of the cluster of galaxies MKW3s which was previously identified as a moderate cooling flow cluster. The Chandra image reveals two striking features -- a 100kpc long and 21kpc wide filament, extending from the center to the south-west and a nearly circular, 50kpc diameter depression 90 kpc south of the X-ray peak. The temperature map shows that the filamentary structure is colder while the surface brightness depression is hotter than the average cluster temperature at any radius. The hot and the cold regions indicate that both cooling and heating processes are taking place in the center of MKW3s. We argue that the surface brightness depression is produced by a heated, low-density gas bubble along the line of sight. We suggest that the heated bubble is produced by short-lived nuclear outbursts from the central galaxy.

  18. High-efficiency 10 J diode pumped cryogenic gas cooled Yb:YAG multislab amplifier.

    Science.gov (United States)

    Banerjee, Saumyabrata; Ertel, Klaus; Mason, Paul D; Phillips, P Jonathan; Siebold, Mathias; Loeser, Markus; Hernandez-Gomez, Cristina; Collier, John L

    2012-06-15

    We report on the first demonstration of a diode-pumped, gas cooled, cryogenic multislab Yb:YAG amplifier. The performance was characterized over a temperature range from 88 to 175 K. A maximum small-signal single-pass longitudinal gain of 11.0 was measured at 88 K. When amplifying nanosecond pulses, recorded output energies were 10.1 J at 1 Hz in a four-pass extraction geometry and 6.4 J at 10 Hz in a three-pass setup, corresponding to optical to optical conversion efficiencies of 21% and 16%, respectively. To our knowledge, this represents the highest pulse energy so far obtained from a cryo-cooled Yb-laser and the highest efficiency from a multijoule diode pumped solid-state laser system. PMID:22739846

  19. Analysis and test verification of control rod buffer in HTR

    International Nuclear Information System (INIS)

    The thin-walled shell buffer in high temperature gas-cooled reactor (HTR) was designed for absorbing the kinetic energy of the control rod drop in the drive line fracture accident. The thin-walled cylinder structure satisfying the requirements of actual working condition was design by using the energy absorption model of the classical cylinder shell under axial pressure. By using ABAQUS/explicit with J-C constitutive model, the finite element models of both the real reactor condition and the test condition were built to simulate the collision. Based on the analysis results, the control rod fall- down test was designed and implemented. The test results demonstrate that stable pro gressive buckling occurs when the full size buffer is impacted by equiponderance test bar, and the buffer can reduce the crush force effectively and protect the graphite from being destroyed. The analysis results show that the test model can represent and envelope the real condition in reactor. (authors)

  20. Basic study on high temperature gas cooled reactor technology for hydrogen production

    International Nuclear Information System (INIS)

    The annual production of hydrogen in the world is about 500 billion m3. Currently hydrogen is consumed mainly in chemical industries. However hydrogen has huge potential to be consumed in transportation sector in coming decades. Assuming that 10% of fossil energy in transportation sector is substituted by hydrogen in 2020, the hydrogen in the sector will exceed current hydrogen consumption by more than 2.5 times. Currently hydrogen is mainly produced by steam reforming of natural gas. Steam reforming process is chiefest way to produce hydrogen for mass production. In the future, hydrogen has to be produced in a way to minimize CO2 emission during its production process as well as to satisfy economic competition. One of the alternatives to produce hydrogen under such criteria is using heat source of high-temperature gas-cooled reactor. The high-temperature gas-cooled reactor represents one type of the next generation of nuclear reactors for safe and reliable operation as well as for efficient and economic generation of energy

  1. Experimental study of gas engine driven air to water heat pump in cooling mode

    International Nuclear Information System (INIS)

    Nowadays a sustainable development for more efficient use of energy and protection of the environment is of increasing importance. Gas engine heat pumps represent one of the most practicable solutions which offer high energy efficiency and environmentally friendly for heating and cooling applications. In this paper, the performance characteristics of gas engine driven heat pump used in water cooling were investigated experimentally without engine heat recovery. The effects of several important factors (evaporator water inlet temperature, evaporator water volume flow rate, ambient air temperature, and engine speed) on the performance of gas engine driven heat pump were studied in a wide range of operating conditions. The results showed that primary energy ratio of the system increased by 22.5% as evaporator water inlet temperature increased from 13 oC to 24 oC. On the other hand, varying of engine speed from 1300 rpm to 1750 rpm led to decrease in system primary energy ratio by 13%. Maximum primary energy ratio has been estimated with a value of two over a wide range of operating conditions.

  2. Steam generators and heat exchangers for gas-cooled reactors. Background and status in Switzerland

    International Nuclear Information System (INIS)

    The Swiss company Sulzer Brothers Ltd. built its first nuclear steam generator in 1961 for a CO2-cooled prototype reactor. Since then the Company has been involved in the planning, development and manufacture of steam generators for gas-cooled reactors, in particular for the French Magnox reactor program. In 1980 Sulzer delivered the 6-module steam generator for the German High Temperature Reactor Prototype THTR-300. The production of hardware was continuously accompanied and supported by extensive research and development activities. Experimental programs comprised thermohydraulic investigations related to the primary gas-side as well as to the secondary side and its two-phase-flow stability. In the area of high temperature materials thermal cycling tests were performed to analyse the fatigue of bimetallic welds under severe transients. Low cycle creep fatigue damage in tube bends and the wear and fretting characteristics of protective coatings on the helium side of hot tubes were investigated. Fabrication experiments for large helical heat exchangers served to extrapolate known manufacturing technology to commercial size HTGR units. In the frame of international GCR programs Switzerland participated in the Gas Breeder Reactor Association and the High Temperature Helium Turbine Project. For these projects Sulzer designed and developed steam generators, recuperators and primary coolers

  3. Nuclear closed-cycle gas turbine (HTGR-GT): dry cooled commercial power plant studies

    International Nuclear Information System (INIS)

    Combining the modern and proven power conversion system of the closed-cycle gas turbine (CCGT) with an advanced high-temperature gas-cooled reactor (HTGR) results in a power plant well suited to projected utility needs into the 21st century. The gas turbine HTGR (HTGR-GT) power plant benefits are consistent with national energy goals, and the high power conversion efficiency potential satisfies increasingly important resource conservation demands. Established technology bases for the HTGR-GT are outlined, together with the extensive design and development program necessary to commercialize the nuclear CCGT plant for utility service in the 1990s. This paper outlines the most recent design studies by General Atomic for a dry-cooled commercial plant of 800 to 1200 MW(e) power, based on both non-intercooled and intercooled cycles, and discusses various primary system aspects. Details are given of the reactor turbine system (RTS) and on integrating the major power conversion components in the prestressed concrete reactor vessel

  4. Optimum Reactor Outlet Temperatures for High Temperature Gas-Cooled Reactors Integrated with Industrial Processes

    International Nuclear Information System (INIS)

    This report summarizes the results of a temperature sensitivity study conducted to identify the optimum reactor operating temperatures for producing the heat and hydrogen required for industrial processes associated with the proposed new high temperature gas-cooled reactor. This study assumed that primary steam outputs of the reactor were delivered at 17 MPa and 540 C and the helium coolant was delivered at 7 MPa at 625-925 C. The secondary outputs of were electricity and hydrogen. For the power generation analysis, it was assumed that the power cycle efficiency was 66% of the maximum theoretical efficiency of the Carnot thermodynamic cycle. Hydrogen was generated via the high temperature steam electrolysis or the steam methane reforming process. The study indicates that optimum or a range of reactor outlet temperatures could be identified to further refine the process evaluations that were developed for high temperature gas-cooled reactor-integrated production of synthetic transportation fuels, ammonia, and ammonia derivatives, oil from unconventional sources, and substitute natural gas from coal.

  5. Optimum Reactor Outlet Temperatures for High Temperature Gas-Cooled Reactors Integrated with Industrial Processes

    Energy Technology Data Exchange (ETDEWEB)

    Lee O. Nelson

    2011-04-01

    This report summarizes the results of a temperature sensitivity study conducted to identify the optimum reactor operating temperatures for producing the heat and hydrogen required for industrial processes associated with the proposed new high temperature gas-cooled reactor. This study assumed that primary steam outputs of the reactor were delivered at 17 MPa and 540°C and the helium coolant was delivered at 7 MPa at 625–925°C. The secondary outputs of were electricity and hydrogen. For the power generation analysis, it was assumed that the power cycle efficiency was 66% of the maximum theoretical efficiency of the Carnot thermodynamic cycle. Hydrogen was generated via the hightemperature steam electrolysis or the steam methane reforming process. The study indicates that optimum or a range of reactor outlet temperatures could be identified to further refine the process evaluations that were developed for high temperature gas-cooled reactor-integrated production of synthetic transportation fuels, ammonia, and ammonia derivatives, oil from unconventional sources, and substitute natural gas from coal.

  6. Does the age of high temperature gas-cooled reactors arrive?

    International Nuclear Information System (INIS)

    Recently, the increase of population, the expansion of resource and energy consumption, and the protection of global environment have become topics, and the expectation to atomic energy becomes large mainly in Asia. At present, the utilization of atomic energy is limited to electric power generation, and is about 17% of the total generated electric power in the world, and about 6% of the total energy consumption. The development of high temperature gas-cooled reactors has been carried out for more than 30 years, which can heighten the efficiency of power generation to 50% from 30% of LWRs, and the heat of close to 1000degC can be utilized. Also in Japan, the high temperature engineering test and research reactor (HTTR) of 30 MW thermal output and the coolant temperature at reactor exit of 950degC is constructed in Japan Atomic Energy Research Institute, aiming at attaining the initial criticality in 1998. The features of high temperature gas-cooled reactors are low output density and large heat capacity, the negative large temperature coefficient of reactivity, and no core melting. The utilization of nuclear heat is carried out by converting to the steam up to 510degC or helium gas up to 950degC. As the present state of research and development, heat and electricity combined supply system, the methanol production by coal gasification, the hydrogen production by thermochemical process are reported. (K.I.)

  7. Evaluation of tritium production rate in a gas-cooled reactor with continuous tritium recovery system for fusion reactors

    International Nuclear Information System (INIS)

    Highlights: • The performance of a gas-cooled reactor as a tritium production system was studied. • A continuous tritium recovery using helium gas was considered. • Gas-cooled reactors with 3 GW output in all can produce ∼6 kg of tritium in a year • Performance of the system was examined for Li4SiO4, Li2TiO3 and LiAlO2 compounds. -- Abstract: The performance of a high-temperature gas-cooled reactor as a tritium production with continuous tritium recovery system is examined. A gas turbine high-temperature reactor of 300-MWe (600 MW) nominal capacity (GTHTR300) is assumed as the calculation target, and using the continuous-energy Monte Carlo transport code MVP-BURN, burn-up simulations for the three-dimensional entire-core region of the GTHTR300 were performed. A Li loading pattern for the continuous tritium recovery system in the gas-cooled reactor is presented. It is shown that module gas-cooled reactors with a total thermal output power of 3 GW in all can produce ∼6 kg of tritium maximum in a year

  8. High temperature gas cooled reactor technology development. Proceedings of a technical committee meeting

    International Nuclear Information System (INIS)

    The successful introduction of an advanced nuclear power plant programme depends on many key elements. It must be economically competitive with alternative sources of energy, its technical development must assure operational dependability, the support of society requires that it be safe and environmentally acceptable, and it must meet the regulatory standards developed for its use and application. These factors interrelate with each other, and the ability to satisfy the established goals and criteria of all of these requirements is mandatory if a country or a specific industry is to proceed with a new, advanced nuclear power system. It was with the focus on commercializing the high temperature gas cooled reactor (HTGR) that the IAEA's International Working Group on Gas Cooled Reactors recommended this Technical Committee Meeting (TCM) on HTGR Technology Development. Over the past few years, many Member States have instituted a re-examination of their nuclear power policies and programmes. It has become evident that the only realistic way to introduce an advanced nuclear power programme in today's world is through international co-operation between countries. The sharing of expertise and technical facilities for the common development of the HTGR is the goal of the Member States comprising the IAEA's International Working Group on Gas Cooled Reactors. This meeting brought together key representatives and experts on the HTGR from the national organizations and industries of ten countries and the European Commission. The state electric utility of South Africa, Eskom, hosted this TCM in Johannesburg, from 13 to 15 November 1996. This TCM provided the opportunity to review the status of HTGR design and development activities, and especially to identify international co-operation which could be utilized to bring about the commercialization of the HTGR

  9. The properties of the cool circumgalactic gas probed with the SDSS, WISE, and GALEX surveys

    International Nuclear Information System (INIS)

    We explore the distribution of cool (∼104 K) gas around galaxies and its dependence on galaxy properties. By cross-correlating about 50,000 Mg II absorbers with millions of sources from the SDSS (optical), WISE (IR), and GALEX (UV) surveys we effectively extract about 2000 galaxy-absorber pairs at z ∼ 0.5 and probe relations between absorption strength and galaxy type, impact parameter and azimuthal angle. We find that cool gas traced by Mg II absorbers exists around both star-forming and passive galaxies with a similar incidence rate on scales greater than 100 kpc but each galaxy type exhibits a different behavior on smaller scales: Mg II equivalent width does not correlate with the presence of passive galaxies whereas stronger Mg II absorbers tend to be found in the vicinity of star-forming galaxies. This effect is preferentially seen along the minor axis of these galaxies, suggesting that some of the gas is associated with outflowing material. In contrast, the distribution of cool gas around passive galaxies is consistent with being isotropic on the same scales. We quantify the average excess Mg II equivalent width 〈δW0Mg II〉 as a function of galaxy properties and find 〈δW0Mg II〉∝SFR1.2, sSFR0.5, and M∗0.4 for star-forming galaxies. This work demonstrates that the dichotomy between star-forming and passive galaxies is reflected in the circumgalactic medium traced by low-ionized gas. We also measure the covering fraction of Mg II absorption and find it to be about 2-10 times higher for star-forming galaxies than passive ones within 50 kpc. We estimate the amount of neutral gas in the halo of (log M */M ☉) ∼ 10.8 galaxies to be a few × 109 M ☉ for both types of galaxies. Finally, we find that correlations between absorbers and sources detected in the UV and IR lead to physical trends consistent with those measured in the optical.

  10. Technoeconomic evaluation of trigeneraton plant: Gas turbine performance, absorption cooling and district heating

    OpenAIRE

    Polyzakis, Apostolos

    2006-01-01

    This PhD thesis is a demand led study taking into account changes in ambient conditions and power settings of a tri-generation power plant. Includes an evaluation tool for combined heat, cooling and power generation plant. The thesis is based on an overall technical-economic analysis of the tri-generation system, including: 1. Energy demand analysis and evaluation of actual tri-generation case studies. 2. Modelling of the prime mover (Gas Turbine, GT) 3. Modelling of the abs...

  11. Assessment of Water Ingress Accidents in a Modular High-Temperature Gas-Cooled Reactor

    OpenAIRE

    Zhang, Z.; Dong, Y.; Scherer, W.

    2005-01-01

    Severe water ingress accidents in the 200-MW HTR-module were assessed to determine the safety margins of modular pebble-bed high-temperature gas-cooled reactors (HTR-module). The 200-MW HTR-module was designed by Siemens under the criteria that no active safety protection systems were necessary because of its inherent safe nature. For simulating the behavior of the HTR-module during severe water ingress accidents, a water, steam, and helium multiphase cavity model was developed and implemente...

  12. Procedure of Active Residual Heat Removal after Emergency Shutdown of High-Temperature-Gas-Cooled Reactor

    OpenAIRE

    Xingtuan Yang; Yanfei Sun; Huaiming Ju; Shengyao Jiang

    2014-01-01

    After emergency shutdown of high-temperature-gas-cooled reactor, the residual heat of the reactor core should be removed. As the natural circulation process spends too long period of time to be utilized, an active residual heat removal procedure is needed, which makes use of steam generator and start-up loop. During this procedure, the structure of steam generator may suffer cold/heat shock because of the sudden load of coolant or hot helium at the first few minutes. Transient analysis was ca...

  13. KEY DESIGN REQUIREMENTS FOR THE HIGH TEMPERATURE GAS-COOLED REACTOR NUCLEAR HEAT SUPPLY SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    L.E. Demick

    2010-09-01

    Key requirements that affect the design of the high temperature gas-cooled reactor nuclear heat supply system (HTGR-NHSS) as the NGNP Project progresses through the design, licensing, construction and testing of the first of a kind HTGR based plant are summarized. These requirements derive from pre-conceptual design development completed to-date by HTGR Suppliers, collaboration with potential end users of the HTGR technology to identify energy needs, evaluation of integration of the HTGR technology with industrial processes and recommendations of the NGNP Project Senior Advisory Group.

  14. New approach to handle neutron startup sources in a high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    In a high temperature gas-cooled reactor, a neutron startup source (NS) cannot be handled simply. An appropriate transfer vessel, connected with a 241Am-Be source for startup core physics tests through an NS coupler and drive wire, was newly designed and installed in the high temperature engineering test reactor (HTTR). A result of tests using the HTTR revealed that the NS could be loaded simply and certainly into the reactor core through the transfer vessel below the allowable limit of effective dose equivalent for operators

  15. Development status and operational features of the high temperature gas-cooled reactor. Final report

    International Nuclear Information System (INIS)

    The objective of this study is to investigate the maturity of HTR-technology and to look out for possible technical problems, concerning introduction of large HTR power plants into the market. Further state and problems of introducing and closing the thorium fuel cycle is presented and judged. Finally, the state of development of advanced HTR-concepts for electricity production, the direct cycle HTR with helium turbine, and the gas-cooled fast breeder is discussed. In preparing the study, both HTR concepts with spherical and block-type fuel elements have been considered

  16. Characteristics of gas-cooled reactor with water moderator and rankine cycle

    International Nuclear Information System (INIS)

    Full text: Nuclear energy with both thermal and fast neutrons, despite on a number of potential benefits, will economically lose energy on organic fuels, if innovative solutions won't be found. It is presented a gas-cooled channel reactor with water-moderator, working on a piston Brayton cycle engine. Efficiency up to 45 percent is achieved. Thermophysical calculations of fuel assemblies show that the proposed reactor fuel assemblies can be constructed in a simplified scheme without heat shield that reduces the creation costs, the costs of coolant pumping, loss of neutrons and dimensions of the core

  17. Liquid metal versus gas cooled reactor concepts for a turbo electric powered space vehicle

    International Nuclear Information System (INIS)

    Recent CNES/CEA prospective studies of an orbit transfer vehicule to be launched by ARIANE V, emphasize the advantage of the Brayton cycle over the thermionics and thermoelectricity, in minimizing the total mass of 100 to 300 kWsub(e) power systems under the constraint specific to ARIANE of a radiator area limited to 95 m2. The review of candidate reactor concepts for this application, finally recommends both liquid metal and gas cooled reactors, for their satisfactory adaptation to a reference Brayton cycle and for the available experience from the terrestrial operation of comparable systems

  18. Application of subgroup decomposition in diffusion theory to gas cooled thermal reactor problem

    International Nuclear Information System (INIS)

    In this paper, the accuracy and computational efficiency of the subgroup decomposition (SGD) method in diffusion theory is assessed in a ID benchmark problem characteristic of gas cooled thermal systems. This method can be viewed as a significant improvement in accuracy of standard coarse-group calculations used for VHTR whole core analysis in which core environmental effect and energy angle coupling are pronounced. It is shown that a 2-group SGD calculation reproduces fine-group (47) results with 1.5 to 6 times faster computational speed depending on the stabilizing schemes while it is as efficient as single standard 6-group diffusion calculation. (authors)

  19. The Fort St. Vrain high temperature gas-cooled reactor. II

    International Nuclear Information System (INIS)

    In field tests in a fossil-fueled facility, performed concurrently with Fort St. Vrain's construction, data indicated that the helium circulator design was well suited to provide primary coolant circulation for the high temperature gas-cooled reactor. After plant installation, primarily during the hot functional tests, a number of time-consuming delays developed caused by cavitation damage on circular speed valves, cavitation and fatigue damage on auxiliary water turbine buckets, water turbine nozzle erosion, static shutdown seal cracks and circulator primary closure helium leakage. After extensive analysis and testing, all of these problems were corrected. Circulators have performed satisfactorily at levels up to 70% of rated power. (Auth.)

  20. Development status and operational features of the high temperature gas-cooled reactor. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Winkleblack, R.K.

    1976-04-01

    The objective of this study is to investigate the maturity of HTR-technology and to look out for possible technical problems, concerning introduction of large HTR power plants into the market. Further state and problems of introducing and closing the thorium fuel cycle is presented and judged. Finally, the state of development of advanced HTR-concepts for electricity production, the direct cycle HTR with helium turbine, and the gas-cooled fast breeder is discussed. In preparing the study, both HTR concepts with spherical and block-type fuel elements have been considered.

  1. Optimization of the steam generator project of a gas cooled nuclear reactor

    International Nuclear Information System (INIS)

    The present work is concerned with the modeling of the primary and secondary circuits of a gas cooled nuclear reactor in order to obtain the relation between the parameters of the two cycles and the steam generator performance. The procedure allows the optimization of the steam generator, through the maximization of the plant net power, and the application of the optimal control theory of dynamic systems. The heat balances for the primary and secondary circuits are carried out simultaneously with the optimized - design parameters of the steam generator, obtained using an iterative technique. (author)

  2. High-temperature gas-cooled reactor (HTGR): long term program plan

    International Nuclear Information System (INIS)

    The FY 1980 effort was to investigate four technology options identified by program participants as potentially viable candidates for near-term demonstration: the Gas Turbine system (HTGR-GT), reflecting its perceived compatibility with the dry-cooling market, two systems addressing the process heat market, the Reforming (HTGR-R) and Steam Cycle (HTGR-SC) systems, and a more developmental reactor system, The Nuclear Heat Source Demonstration Reactor (NHSDR), which was to serve as a basis for both the HTGR-GT and HTGR-R systems as well as the further potential for developing advanced applications such as steam-coal gasification and water splitting

  3. SAGAPO. A computer code for the thermo-fluiddynamic analysis of gas cooled fuel element bundles

    International Nuclear Information System (INIS)

    This paper is a guide for the users of the Fortran computer code SAGAPO, which has been developed by the author for the thermo-fluiddynamic analysis of gas cooled fuel element bundles. The physical models and the mathematical procedures used in SAGAPO have been already described by the author of this work in a previous paper. Thus this work contains only a description of the structure of the code, together with the other informations necessary to the users. A listing of SAGAPO is included in the appendix, together with an example of input preparation and parts of printed results. (orig.)

  4. Galaxies probing galaxies: cool halo gas from a z = 0.47 post-starburst galaxy

    OpenAIRE

    Rubin, Kate H. R.; Prochaska, J. Xavier; Koo, David C.; Phillips, Andrew C.; Weiner, Benjamin J.

    2009-01-01

    We study the cool gas around a galaxy at z = 0.4729 using Keck/LRIS spectroscopy of a bright (B = 21.7) background galaxy at z = 0.6942 at a transverse distance of 16.5/h_70 kpc. The background galaxy spectrum reveals strong FeII, MgII, MgI, and CaII absorption at the redshift of the foreground galaxy, with a MgII 2796 rest equivalent width of 3.93 +/- 0.08 Angstroms, indicative of a velocity width exceeding 400 km/s. Because the background galaxy is large (> 4/h_70 kpc), the high covering fr...

  5. Development of a CVD silica coating for UK advanced gas-cooled nuclear reactor fuel pins

    International Nuclear Information System (INIS)

    Vapour deposited silica coatings could extend the life of the 20% Cr/25% Ni niobium stabilised (20/25/Nb) stainless steel fuel cladding of the UK advanced gas cooled reactors. A CVD coating process developed originally to be undertaken at atmospheric pressure has now been adapted for operation at reduced pressure. Trials on the LP CVD process have been pursued to the production scale using commercial equipment. The effectiveness of the LP CVD silica coatings in providing protection to 20/25/Nb steel surfaces against oxidation and carbonaceous deposition has been evaluated. (author)

  6. Factors affecting the performances of sprayed chromium carbide coatings for gas-cooled reactor heat exchangers

    International Nuclear Information System (INIS)

    The paper discusses some important factors to be considered for using sprayed coatings in gas-cooled reactor heat exchangers. These factors include (a) high-temperature gaseous corresion, (b) thermal stability of coatings, (c) metallurgical compatibility between the coating and substrate, and (d) effects of the coating on the mechanical properties of the substrate alloy. The coatings evaluated were Cr3C2--NiCr and Cr23C6--NiCr applied by either plasma-arc or detonation-gun process

  7. Endwall shape modification using vortex generators and fences to improve gas turbine cooling and effectiveness

    Science.gov (United States)

    Gokce, Zeki Ozgur

    The gas turbine is one of the most important parts of the air-breathing jet engine. Hence, improving its efficiency and rendering it operable under high temperatures are constant goals for the aerospace industry. Two types of flow within the gas turbine are of critical relevance: The flow around the first row of stator blades (also known as the nozzle guide vane blade - NGV) and the cooling flow inside the turbine blade cooling channel. The subject of this thesis work was to search for methods that could improve the characteristics of these two types of flows, thus enabling superior engine performance. The innovative aspect of our work was to apply an endwall shape modification previously employed by non-aerospace industries for cooling applications, to the gas turbine cooling flow which is vital to aerospace propulsion. Since the costs of investigating the possible benefits of any idea via extensive experiments could be quite high, we decided to use computational fluid dynamics (CFD) followed by experimentation as our methodology. We decided to analyze the potential benefits of using vortex generators (VGs) as well as the rectangular endwall fence. Since the pin-fins used in cooling flow are circular cylinders, and since the boundary layer flow is mainly characterized by the leading edge diameter of the NGV blade, we modeled both the pin-fins and the NGV blade as vertical circular cylinders. The baseline case consisted of the cylinder(s) being subjected to cross flow and a certain amount of freestream turbulence. The modifications we made on the endwall consisted of rectangular fences. In the case of the cooling flow, we used triangular shaped, common flow up oriented, delta winglet type vortex generators as well as rectangular endwall fences. The channel contained singular cylinders as well as staggered rows of multiple cylinders. For the NGV flow, a rectangular endwall fence and a singular cylinder were utilized. Using extensive CFD modeling and analysis, we

  8. Experimental study of gas-cooled current leads for superconducting magnets

    International Nuclear Information System (INIS)

    Design details and experimental test results from several design variations of the gas-cooled, copper current leads used in conjunction with the superconducting dipole magnets for ESCAR (Experimental Superconducting Accelerator Ring) are reported. Thermal acoustic oscillations, which were experienced with an initial design, were eliminated in subsequent designs by a reduction of the hydraulic diameter. The occurrence of these oscillations is in general agreement with the stability analysis of Rott but the observed gas flow dependence is not in agreement with some other recently reported results for leads operated supercritical phase coolant. An empirically determined correlation was obtained by plotting lead resistance vs. enthalpy gain of the coolant gas. The resulting family of curves can be reduced to a single line on a plot of effective resistivity vs. the product of current and cross-sectional area divided by the product of the square of the mass flow of the coolant and the lead length. This correlation, which should be applicable to other designs of copper current leads in which ideal heat transfer to the coolant gas is approached, predicts that the enthalpy gain of the coolant, and therefore the peak lead temperature, is proportional to the cube of the ratio of current to coolant mass flow. The effective value of the strongly temperature-dependent kinematic viscosity of the coolant gas was found to vary linearly with the effective resistivity of the lead

  9. The Large-scale Distribution of Cool Gas around Luminous Red Galaxies

    CERN Document Server

    Zhu, Guangtun; Bizyaev, Dmitry; Brewington, Howard; Ebelke, Garrett; Ho, Shirley; Kinemuchi, Karen; Malanushenko, Viktor; Malanushenko, Elena; Marchante, Moses; More, Surhud; Oravetz, Daniel; Pan, Kaike; Petitjean, Patrick; Simmons, Audrey

    2013-01-01

    We present a measurement of the correlation function between luminous red galaxies and cool gas traced by Mg II \\lambda \\lambda 2796, 2803 absorption, on scales ranging from about 30 kpc to 20 Mpc. The measurement is based on cross-correlating the positions of about one million red galaxies at z~0.5 and the flux decrements induced in the spectra of about 10^5 background quasars from the Sloan Digital Sky Survey. We find that: (i) This galaxy-gas correlation reveals a change of slope on scales of about 1 Mpc, consistent with the expected transition from a dark matter halo dominated environment to a regime where clustering is dominated by halo-halo correlations. Assuming that, on average, the distribution of Mg II gas follows that of dark matter up to a gas-to-mass ratio, we find the standard halo model to provide an accurate description of the gas distribution over three orders of magnitude in scale. Within this framework we estimate the average host halo mass of luminous red galaxies to be about 10^{13.5} M_s...

  10. Efficiency of gas cooling and accretion at the disc-corona interface

    CERN Document Server

    Armillotta, L; Marinacci, F

    2016-01-01

    In star-forming galaxies, stellar feedback can have a dual effect on the circumgalactic medium both suppressing and stimulating gas accretion. The trigger of gas accretion can be caused by disc material ejected into the halo in the form of fountain clouds and by its interaction with the surrounding hot corona. Indeed, at the disc-corona interface, the mixing between the cold/metal-rich disc gas (T ~ 10^6 K) can dramatically reduce the cooling time of a portion of the corona and produce its condensation and accretion. We studied the interaction between fountain clouds and corona in different galactic environments through parsec-scale hydrodynamical simulations, including the presence of thermal conduction, a key mechanism that influences gas condensation. Our simulations showed that the coronal gas condensation strongly depends on the galactic environment, in particular it is less efficient for increasing virial temperature/mass of the haloes where galaxies reside and it is fully ineffective for objects with v...

  11. Development of a equipment to measure gas transport properties: Application to study candidate buffer mixtures for low-medium level waste repositories

    International Nuclear Information System (INIS)

    This report describes the design, the construction and a testing of a system set-up for the measurement of gas transport, created at CIEMAT, and its application to study mixtures of candidate buffer materials for Low-Medium Level Waste Repertories. The measure of the gas flows is carried on by mass flow meters of several ranges, white the pressure of the applied within the sample is controlled. Two National l Instrument's acquisition system that permits the control and recording of the parameters. A specific application developed for this test, with National Instruments LabWIEW DSC, permits to mange the system. A client interface lets to follow the experiment course from a remote location through Internet. (Author) 21 refs

  12. Performance of high-temperature gas-cooled reactor as a tritium production device for fusion reactors

    International Nuclear Information System (INIS)

    Highlights: ► The performance of a gas-cooled reactor as a tritium production device was studied. ► Gas-cooled reactors with 3 GWt output can produce 5–8 kg of tritium in a year. ► Use of Li2O compound is efficient compared with Li4SiO4 or Li2TiO3 one. ► Amount of tritium produced can be increased by reducing the enrichment of 235U. - Abstract: The performance of a high-temperature gas-cooled reactor as a tritium production device is examined. A gas turbine high-temperature reactor of 300 MWe nominal capacity (GTHTR300) is assumed as the calculation target of a typical gas-cooled reactor, and using the continuous-energy Monte Carlo transport code MVP-BURN, burn-up simulations for the 3-dimensional entire-core region of GTHTR300 were carried out considering its unique double heterogeneity structure. It is shown that gas-cooled reactors with thermal output power of 3 GW in all can produce 5–8 kg of tritium in a year.

  13. Microscopical examination of carbon deposits formed in the Windscale advanced gas cooled reactor

    International Nuclear Information System (INIS)

    Methods are described of sampling and examining carbon deposits on fuel cladding in the Windscale advanced gas-cooled reactor. Deposition is observed on fuel cladding in both the reactor core and experimental loops in carbon dioxide coolants containing various amounts of carbon monoxide and methane. Deposit distribution over the cladding surface indicated that nucleation is dependent on local surface conditions. Microscopical examination showed that deposit thickness increases by carbon filament growth into the coolant gas stream and that the process can be markedly influenced by metallic impurities. There is evidence that nickel can play a particularly significant role in deposition in loop experiments but similar effects have not been observed in the reactor core. (author)

  14. Porous nuclear fuel element with internal skeleton for high-temperature gas-cooled nuclear reactors

    Science.gov (United States)

    Youchison, Dennis L.; Williams, Brian E.; Benander, Robert E.

    2013-09-03

    Porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's), and to processes for fabricating them. Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, the nuclear fuel may be deposited inside of a highly porous skeletal structure made of, for example, reticulated vitreous carbon foam.

  15. Porous nuclear fuel element for high-temperature gas-cooled nuclear reactors

    Science.gov (United States)

    Youchison, Dennis L.; Williams, Brian E.; Benander, Robert E.

    2011-03-01

    Porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's), and to processes for fabricating them. Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, the nuclear fuel may be deposited inside of a highly porous skeletal structure made of, for example, reticulated vitreous carbon foam.

  16. Methods for manufacturing porous nuclear fuel elements for high-temperature gas-cooled nuclear reactors

    Science.gov (United States)

    Youchison, Dennis L.; Williams, Brian E.; Benander, Robert E.

    2010-02-23

    Methods for manufacturing porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's). Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, a thin coating of nuclear fuel may be deposited inside of a highly porous skeletal structure made, for example, of reticulated vitreous carbon foam.

  17. Modular High Temperature Gas-Cooled Reactor heat source for coal conversion

    International Nuclear Information System (INIS)

    In the industrial nations, transportable fuels in the form of natural gas and petroleum derivatives constitute a primary energy source nearly equivalent to that consumed for generating electric power. Nations with large coal deposits have the option of coal conversion to meet their transportable fuel demands. But these processes themselves consume huge amounts of energy and produce undesirable combustion by-products. Therefore, this represents a major opportunity to apply nuclear energy for both the environmental and energy conservation reasons. Because the most desirable coal conversion processes take place at 800 degree C or higher, only the High Temperature Gas-Cooled Reactors (HTGRs) have the potential to be adapted to coal conversion processes. This report provides a discussion of this utilization of HTGR reactors

  18. A small high temperature gas cooled reactor for nuclear marine propulsion

    Energy Technology Data Exchange (ETDEWEB)

    Brugiere, F.; Sillon, C. [Ecole des Applications Militaires de l' Energie Atomique, 50 - Cherbourg (France); Foster, A.; Hamilton, P.; Jewer, S.; Thompson, A.C. [Defence College of Electromechanical Engineering, Nuclear Dept., Military Rd, Gosport (United Kingdom); Kingston, T.; Williams, A.M.; Beeley, P.A. [Rolls-Royce (Marine Power), Raynesway, Derby (United Kingdom)

    2007-07-01

    Results from a design study for a hypothetical nuclear marine propulsion plant are presented. The plant utilizes a small High Temperature Gas Cooled Reactor (HTGCR) similar to the GTHTR300 design by the Japan Atomic Energy Agency with power being generated by a direct cycle gas turbine. The GTHTR300 design is modified in order to achieve the required power of 80 MWth and core lifetime of approximately 10 years. Thermal hydraulic analysis shows that in the event of a complete loss of flow accident the hot channel fuel temperature exceeds the 1600 Celsius degrees limit due to the high power peaking in assemblies adjacent to the inner reflector. Reactor dynamics shows oscillatory behaviour in rapid power transients. An automatic control rod system is suggested to overcome this problem. (authors)

  19. Simulation and control of water-gas shift packed bed reactor with inter-stage cooling

    Science.gov (United States)

    Saw, S. Z.; Nandong, J.

    2016-03-01

    Water-Gas Shift Reaction (WGSR) has become one of the well-known pathways for H2 production in industries. The issue with WGSR is that it is kinetically favored at high temperatures but thermodynamically favored at low temperatures, thus requiring careful consideration in the control design in order to ensure that the temperature used does not deactivate the catalyst. This paper studies the effect of a reactor arrangement with an inter-stage cooling implemented in the packed bed reactor to look at its effect on outlet temperature. A mathematical model is developed based on one-dimensional heat and mass transfers which incorporate the intra-particle effects. It is shown that the placement of the inter-stage cooling and the outlet temperature exiting the inter-stage cooling have strong influence on the reaction conversion. Several control strategies are explored for the process. It is shown that a feedback- feedforward control strategy using Multi-scale Control (MSC) is effective to regulate the reactor temperature profile which is critical to maintaining the catalysts activity.

  20. Transient simulation of gas bubble in a medium sized lead cooled fast reactor

    International Nuclear Information System (INIS)

    A common problem for many liquid metal cooled fast reactor designs is the positive void worth of the coolant. In this context, an advantage of lead cooled fast reactors is the high temperature of coolant boiling. In contrast to sodium cooled fast reactors this, in practice, precludes coolant boiling. However, partial voiding of the core could result from e.g. gas bubbles entering the core from below. This would introduce a positive reactivity, and if the bubble is large enough. In this paper we model this type of event using a point kinetics code coupled to a heat transport code. The reactivity parameters are obtained from a Monte Carlo code. The 300 MWth reactor design Alfred is used as a test case. We show that in general the reactor design studied is robust in such events, and we conclude that small bubbles a measurable Power oscillation would occur. For very large bubbles there exist a possibility of core damage. The cladding is the most sensitive part. (author)

  1. Gas-cooled Fast Reactor (GFR) fuel and In-Core Fuel Management

    International Nuclear Information System (INIS)

    The Gas-Cooled Fast Reactor (GCFR) has been chosen as one of six candidates for development as a Generation IV nuclear reactor based on: its ability to fully utilize fuel resources; minimize or reduce its own (and other systems) actinide inventory; produce high efficiency electricity; and the possibility to utilize high temperature process heat. Current design approaches include a high temperature (2 850 C) helium cooled reactor using a direct Brayton cycle, and a moderate temperature (550 C - 650 C) helium or supercritical carbon dioxide (S-CO2) cooled reactor using direct or indirect Brayton cycles. These design choices have thermal efficiencies that approach 45% to 50%, and have turbomachinery sizes that are much more compact compared to steam plants. However, there are challenges associated with the GCFR, which are the focus of current research. This includes safety system design for decay heat removal, development of high temperature/high fluence fuels and materials, and development of fuel cycle strategies. The work presented here focuses on the fuel and preliminary in-core fuel management, where advanced ceramic-ceramic (cercer) dispersion fuels are the main focus, and average burnups to 266 M Wd/kg appear achievable for the reference Si C/(U,TRU)C block/plate fuel. Solid solution (pellet) fuel in composite ceramic clad (Si C/Si C) is also being considered, but remains as a backup due to cladding fabrication challenges, and high centerline temperatures in the fuel. (Author)

  2. Radioactivities evaluation code system for high temperature gas cooled reactors during normal operation

    International Nuclear Information System (INIS)

    A radioactivity evaluation code system for high temperature gas-cooled reactors during normal operation was developed to study the behavior of fission products (FP) in the plants. The system consists of a code for the calculation of diffusion of FPs in fuel (FIPERX), a code for the deposition of FPs in primary cooling system (PLATO), a code for the transfer and emission of FPs in nuclear power plants (FIPPI-2), and a code for the exposure dose due to emitted FPs (FEDOSE). The FIPERX code can calculate the changes in the course of time FP of the distribution of FP concentration, the distribution of FP flow, the distribution of FP partial pressure, and the emission rate of FP into coolant. The amount of deposition of FPs and their distribution in primary cooling system can be evaluated by the PLATO code. The FIPPI-2 code can be used for the estimation of the amount of FPs in nuclear power plants and the amount of emitted FPs from the plants. The exposure dose of residents around nuclear power plants in case of the operation of the plants is calculated by the FEDOSE code. This code evaluates the dose due to the external exposure in the normal operation and in the accident, and the internal dose by the inhalation of radioactive plume and foods. Further studies of this code system by the comparison with the experimental data are considered. (Kato, T.)

  3. Performance comparison of liquid metal and gas cooled ATW system point designs

    International Nuclear Information System (INIS)

    As part of the Advanced Accelerator Application (AAA) program in the U.S., preliminary design studies have been performed at Argonne National Laboratory (ANL) and Los Alamos National Laboratory (LANL) to define and compare candidate Accelerator Transmutation of Waste (ATW) systems. The studies at ANL have focused primarily on the transmutation blanket component of the overall system. Lead-bismuth eutectic (LBE), sodium, and gas cooled systems are among the blanket technology options currently under consideration. This paper summarizes the results from neutronics trade studies performed at ANL. Core designs have been developed for LBE and sodium cooled 840 MWt fast spectrum accelerator driven systems employing re-cycle. Additionally, neutronics analyses have been performed for a helium-cooled 600 MWt hybrid thermal and fast spectrum system proposed by General Atomics (GA), which is operated in the critical mode for three cycles and in a subcritical accelerator driven mode for a subsequent single cycle. For these three point designs, isotopic inventories, consumption rates, and annual burnup rates are compared. The mass flows and the ultimate loss of transuranic (TRU) isotopes to the waste stream per unit of heat generated during transmutation are also compared on a consistent basis. (author)

  4. Fabrication of gas turbine water-cooled composite nozzle and bucket hardware employing plasma spray process

    Energy Technology Data Exchange (ETDEWEB)

    Schilke, Peter W. (4 Hempshire Ct., Scotia, NY 12302); Muth, Myron C. (R.D. #3, Western Ave., Amsterdam, NY 12010); Schilling, William F. (301 Garnsey Rd., Rexford, NY 12148); Rairden, III, John R. (6 Coronet Ct., Schenectady, NY 12309)

    1983-01-01

    In the method for fabrication of water-cooled composite nozzle and bucket hardware for high temperature gas turbines, a high thermal conductivity copper alloy is applied, employing a high velocity/low pressure (HV/LP) plasma arc spraying process, to an assembly comprising a structural framework of copper alloy or a nickel-based super alloy, or combination of the two, and overlying cooling tubes. The copper alloy is plamsa sprayed to a coating thickness sufficient to completely cover the cooling tubes, and to allow for machining back of the copper alloy to create a smooth surface having a thickness of from 0.010 inch (0.254 mm) to 0.150 inch (3.18 mm) or more. The layer of copper applied by the plasma spraying has no continuous porosity, and advantageously may readily be employed to sustain a pressure differential during hot isostatic pressing (HIP) bonding of the overall structure to enhance bonding by solid state diffusion between the component parts of the structure.

  5. Gas-cooled Fast Reactor (GFR) fuel and In-Core Fuel Management

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, K.D.; Sterbentz, J. [Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415-3850 (United States); Meyer, M. [Argonne National Laboratory- West (United States); Lowden, R. [Oak Ridge National Laboratory (United States); Hoffman, E.; Wei, T.Y.C. [Argonne National Laboratory (United States)]. e-mail: weavkd@inel.gov

    2004-07-01

    The Gas-Cooled Fast Reactor (GCFR) has been chosen as one of six candidates for development as a Generation IV nuclear reactor based on: its ability to fully utilize fuel resources; minimize or reduce its own (and other systems) actinide inventory; produce high efficiency electricity; and the possibility to utilize high temperature process heat. Current design approaches include a high temperature (2 850 C) helium cooled reactor using a direct Brayton cycle, and a moderate temperature (550 C - 650 C) helium or supercritical carbon dioxide (S-CO{sub 2}) cooled reactor using direct or indirect Brayton cycles. These design choices have thermal efficiencies that approach 45% to 50%, and have turbomachinery sizes that are much more compact compared to steam plants. However, there are challenges associated with the GCFR, which are the focus of current research. This includes safety system design for decay heat removal, development of high temperature/high fluence fuels and materials, and development of fuel cycle strategies. The work presented here focuses on the fuel and preliminary in-core fuel management, where advanced ceramic-ceramic (cercer) dispersion fuels are the main focus, and average burnups to 266 M Wd/kg appear achievable for the reference Si C/(U,TRU)C block/plate fuel. Solid solution (pellet) fuel in composite ceramic clad (Si C/Si C) is also being considered, but remains as a backup due to cladding fabrication challenges, and high centerline temperatures in the fuel. (Author)

  6. Gas-Cooled Thorium Reactor with Fuel Block of the Unified Design

    Directory of Open Access Journals (Sweden)

    Igor Shamanin

    2015-01-01

    Full Text Available Scientific researches of new technological platform realization carried out in Russia are based on ideas of nuclear fuel breeding in closed fuel cycle and physical principles of fast neutron reactors. Innovative projects of low-power reactor systems correspond to the new technological platform. High-temperature gas-cooled thorium reactors with good transportability properties, small installation time, and operation without overloading for a long time are considered perspective. Such small modular reactor systems at good commercial, competitive level are capable of creating the basis of the regional power industry of the Russian Federation. The analysis of information about application of thorium as fuel in reactor systems and its perspective use is presented in the work. The results of the first stage of neutron-physical researches of a 3D model of the high-temperature gas-cooled thorium reactor based on the fuel block of the unified design are given. The calculation 3D model for the program code of MCU-5 series was developed. According to the comparison results of neutron-physical characteristics, several optimum reactor core compositions were chosen. The results of calculations of the reactivity margins, neutron flux distribution, and power density in the reactor core for the chosen core compositions are presented in the work.

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

    International Nuclear Information System (INIS)

    For the design of the graphite components in the High Temperature Engineering Test Reactor (HTTR), the graphite structural design code for the HTTR etc. were applied. However, general standard systems for the High Temperature Gas-cooled Reactor (HTGR) have not been established yet. The authors had studied on the technical issues which is necessary for the establishment of a general standard system for the graphite components in the HTGR. The results of the study were documented and discussed at a 'Special committee on research on preparation for codes for graphite components in HTGR' at Atomic Energy Society of Japan (AESJ). As a result, 'Draft of Standard for Graphite Core Components in High Temperature Gas-cooled Reactor.' was established. In the draft standard, the graphite components are classified three categories (A, B and C) in the standpoints of safety functions and possibility of replacement. For the components in the each class, design standard, material and product standards, and in-service inspection and maintenance standard are determined. As an appendix of the design standard, the graphical expressions of material property data of 1G-110 graphite as a function of fast neutron fluence are expressed. The graphical expressions were determined through the interpolation and extrapolation of the irradiated data. (author)

  8. CEA program on future generation light water modular reactors and gas cooled reactors

    International Nuclear Information System (INIS)

    The CEA programme on 'Future Generation Reactors and Fuel Cycles' aims at studying and developing the mean and long term most promising options for nuclear reactors, fuels and reprocessing. These options should contribute to make the nuclear energy a major source of the sustainable development. The program also aims at maintaining at the highest level of competency the technologies with which the CEA will be able to bring to national achievements or international projects in the next decades, projects whose specifications and calendar are today unknown. These studies on the 'Future Generation Reactors and Fuel Cycles' constitute a field privileged for international collaboration. The corresponding researches are structured in four main axes: Innovations for LWR; Systems of 4th generation; Sodium-cooled reactors; Systems which are the object for survey or exploratory studies. Studies on future nuclear gas technologies are mainly covered by the 4th generation programme (Gen IV). Within this context, the goals pursued, in particular the minimization of the production of long lived waste and the saving of resources (i.e.: the optimised utilisation of fissile and fertile nuclear fuels), could justify an evolution towards hard neutron spectra and high temperatures, to cover applications other than the electricity production, e.g.: hydrogen production, desalination, cogeneration. The main R and D axis for these long-term objectives currently the area of Gas Cooled Reactors (GCR). The corresponding program is structured through eight R and D projects details of which are presented within the paper. (author)

  9. Analysis of the control of the high temperature gas-cooled reactor nuclear power plants

    International Nuclear Information System (INIS)

    Modular High Temperature Gas-Cooled Reactor (MHTGR) is characterized by inherent safety and higher electrical efficiency, so it can effectively improve the safety and economics of the nuclear power plants. Based upon these advantages, the High Temperature Gas-Cooled Reactor-Pebble Bed Module (HTR-PM) is under design and will be constructed in China to demonstrate the safety and economics of MHTGR. The automatic control system is important and necessary to the safe, economical, and efficient operation of the MHTGR. This paper investigates the control characteristics of the HTGR nuclear power plants, and analyzes the control technique and existing control strategies of HTGR plants. Advanced control technology which applies modern and intelligent control theory in industrial process provides an opportunity to improve the control performance of the MHTGR plant. Based upon the advanced control technology, the paper proposes a preliminary design concept of hierarchical coordinated control system to the control system design of the HTR-PM which employs the Distributed Control System (DCS) principle. (author)

  10. The role of the IAEA in gas-cooled reactor development and application

    International Nuclear Information System (INIS)

    Within the Statute establishing the International Atomic Energy Agency there are several functions authorized for the Agency. One of these functions is ''to encourage and assist research on, and development and practical application of, atomic energy for peaceful uses throughout the world...''. The development of nuclear power is deemed an important application of this function. The representatives of Member States with national gas cooled reactor (GCR) programmes advise the Agency on its activities in the development and application of the GCR. The committee of leaders in GCR technology representing these Member States is the International Working Group on Gas Cooled Reactors (IWGGCR). The activities carried out by the Agency under the frame of the IWGGCR include technical information exchange meetings and cooperative Coordinated Research Programmes. Within the technical information exchange meetings are Specialist Meetings to review progress on selected technology areas and Technical Committee Meetings and Workshops for more general participation. Consultancies and Advisory Group Meetings are convened to provide the Agency with advise on specific technical matters. The Coordinated Research Programmes (CRPs) established within the frame of the IWGGCR for the GCR programme include: Validation of Safety Related Physics Calculations for Low Enriched GCRs; Validation of Predictive Methods for Fuel and Fission Product Behaviour in GCRs; Heat Transport and Afterheat Heat Removal for GCRs under Accident Conditions; and Design and Evaluation of Heat Utilization Systems for the High Temperature Engineering Test Reactor. This paper summarizes the role of the International Atomic Energy Agency in GCR technology development and application. (author). 6 refs, 3 tabs

  11. On the quasihydrostatic flows of radiatively cooling self-gravitating gas clouds

    Energy Technology Data Exchange (ETDEWEB)

    Meerson, B.; Megged, E. [Hebrew Univ. of Jerusalem (Israel). Racah Institute of Physics; Tajima, T. [Univ. of Texas, Austin, TX (United States)

    1995-03-01

    Two model problems are considered, illustrating the dynamics of quasihydrostatic flows of radiatively cooling, optically thin self-gravitating gas clouds. In the first problem, spherically symmetric flows in an unmagnetized plasma are considered. For a power-law dependence of the radiative loss function on the temperature, a one-parameter family of self-similar solutions is found. The authors concentrate on a constant-mass cloud, one of the cases, when the self-similarity indices are uniquely selected. In this case, the self-similar flow problem can be formally reduced to the classical Lane-Emden equation and therefore solved analytically. The cloud is shown to undergo radiative condensation, if the gas specific heat ratio {gamma} > 4/3. The condensation proceeds either gradually, or in the form of (quasihydrostatic) collapse. For {gamma} < 4/3, the cloud is shown to expand. The second problem addresses a magnetized plasma slab that undergoes quasihydrostatic radiative cooling and condensation. The problem is solved analytically, employing the Lagrangian mass coordinate.

  12. Feasibility Study of Compact Gas-Filled Storage Ring for 6D Cooling of Muon Beams

    International Nuclear Information System (INIS)

    The future of elementary particle physics in the USA depends in part on the development of new machines such as the International Linear Collider, Muon Collider and Neutrino Factories which can produce particle beams of higher energy, intensity, or particle type than now exists. These beams will enable the continued exploration of the world of elementary particles and interactions. In addition, the associated development of new technologies and machines such as a Muon Ring Cooler is essential. This project was to undertake a feasibility study of a compact gas-filled storage ring for 6D cooling of muon beams. The ultimate goal, in Phase III, was to build, test, and operate a demonstration storage ring. The preferred lattice for the storage ring was determined and dynamic simulations of particles through the lattice were performed. A conceptual design and drawing of the magnets were made and a study of the RF cavity and possible injection/ejection scheme made. Commercial applications for the device were investigated and the writing of the Phase II proposal completed. The research findings conclude that a compact gas-filled storage ring for 6D cooling of muon beams is possible with further research and development

  13. Design, Fabrication and Testing of the Control Rods for the Experimental Gas-Cooled Reactor

    International Nuclear Information System (INIS)

    The criteria and methods used for the design of the control rods for the Experimental Gas-Cooled Reactor are described. The final mechanical design was derived from extensive thermal and mechanical calculations and actual experience obtained by fabrication of a prototype rod. The nuclear design of the rod was based on detailed calculations, the accuracy of which was checked by comparison with a measurement of rod worth made with the Physical Constants Test Reactor; By means of a meticulous application of basic principles the calculation agreed with the measurement within the experimental uncertainty. The most important nuclear aspect of the design is the large amount of epithermal absorption, which approximately doubles the worth over that of a purely thermal absorber. The rod is of an articulated type and consists of hot-pressed B4C-bushings clad in stainless-steel. The unique design of the load-supporting members allows operation at cladding temperatures up to 1600°F. Comparisons are made with control-rod designs for other gas-cooled reactors, and justifications for the choice of design features and material selection are discussed. The fabrication procedures and the final test programme for verification of the adequacy of the design are described. (author)

  14. On the quasihydrostatic flows of radiatively cooling self-gravitating gas clouds

    International Nuclear Information System (INIS)

    Two model problems are considered, illustrating the dynamics of quasihydrostatic flows of radiatively cooling, optically thin self-gravitating gas clouds. In the first problem, spherically symmetric flows in an unmagnetized plasma are considered. For a power-law dependence of the radiative loss function on the temperature, a one-parameter family of self-similar solutions is found. The authors concentrate on a constant-mass cloud, one of the cases, when the self-similarity indices are uniquely selected. In this case, the self-similar flow problem can be formally reduced to the classical Lane-Emden equation and therefore solved analytically. The cloud is shown to undergo radiative condensation, if the gas specific heat ratio γ > 4/3. The condensation proceeds either gradually, or in the form of (quasihydrostatic) collapse. For γ < 4/3, the cloud is shown to expand. The second problem addresses a magnetized plasma slab that undergoes quasihydrostatic radiative cooling and condensation. The problem is solved analytically, employing the Lagrangian mass coordinate

  15. Operator information displays for normal operation and fault management of an advanced gas-cooled reactor

    International Nuclear Information System (INIS)

    The paper describes the design intent, organisation and implementation of operator displays for a 1300 MWe Advanced Gas-Cooled Reactor employing a high level of automation, computer based displays and discrete devices incorporated into a structured information system. A description of the main plant and post-cooling system is given and the provisions for automatic initiation of the post-trip systems are related to claims made on operator action. A statement on control room staffing and task allocation is included in order to identify the roles of the various display systems. The structure of the Operator and Supervisor information system is described and the hierarchy of data and alarm displays is discussed. The role of discrete displays is discussed both in relation to the computer based displays and as a stand-alone set of essential information providing for safe operation in the rare event of total loss of computer based displays. The extent and organisation of the computer based displays is described with emphasis on the allocation of data to functional groups in order to aid fault diagnosis and management. The role and implementation of overview displays is described. An important part of the overall information system is the reactor post trip cooling system display. Taking the form of a functional mimic, the display provides a comprehensive summary of post trip reactivity, primary circuit integrity, reactor heat removal and cooling system status and security. The display is used to monitor the effectiveness and adequacy of the post-trip functions and provides an overview of plant abnormalities which are then investigated using the systems described above. The paper concludes with a review of areas of current and future development. (author)

  16. Safety aspects of the Modular High-Temperature Gas-Cooled Reactor (MHTGR)

    International Nuclear Information System (INIS)

    The Modular High-Temperature Gas-Cooled Reactor (MHTGR) is an advanced reactor concept under development through a cooperative program involving the US Government, the nuclear industry and the utilities. The design utilizes the basic high-temperature gas-cooled reactor (HTGR) features of ceramic fuel, helium coolant, and a graphite moderator. The qualitative top-level safety requirement is that the plant's operation not disturb the normal day-to-day activities of the public. The MHTGR safety response to events challenging the functions relied on to retain radionuclides within the coated fuel particles has been evaluated. A broad range of challenges to core heat removal have been examined which include a loss of helium pressure and a simultaneous loss of forced cooling of the core. The challenges to control of heat generation have considered not only the failure to insert the reactivity control systems, but the withdrawal of control rods. Finally, challenges to control chemical attack of the ceramic coated fuel have been considered, including catastrophic failure of the steam generator allowing water ingress or of the pressure vessels allowing air ingress. The plant's response to these extreme challenges is not dependent on operator action and the events considered encompass conceivable operator errors. In the same vein, reliance on radionuclide retention within the full particle and on passive features to perform a few key functions to maintain the fuel within acceptable conditions also reduced susceptibility to external events, site-specific events, and to acts of sabotage and terrorism. 4 refs., 14 figs., 1 tab

  17. THATCH: A computer code for modelling thermal networks of high- temperature gas-cooled nuclear reactors

    International Nuclear Information System (INIS)

    This report documents the THATCH code, which can be used to model general thermal and flow networks of solids and coolant channels in two-dimensional r-z geometries. The main application of THATCH is to model reactor thermo-hydraulic transients in High-Temperature Gas-Cooled Reactors (HTGRs). The available modules simulate pressurized or depressurized core heatup transients, heat transfer to general exterior sinks or to specific passive Reactor Cavity Cooling Systems, which can be air or water-cooled. Graphite oxidation during air or water ingress can be modelled, including the effects of added combustion products to the gas flow and the additional chemical energy release. A point kinetics model is available for analyzing reactivity excursions; for instance due to water ingress, and also for hypothetical no-scram scenarios. For most HTGR transients, which generally range over hours, a user-selected nodalization of the core in r-z geometry is used. However, a separate model of heat transfer in the symmetry element of each fuel element is also available for very rapid transients. This model can be applied coupled to the traditional coarser r-z nodalization. This report described the mathematical models used in the code and the method of solution. It describes the code and its various sub-elements. Details of the input data and file usage, with file formats, is given for the code, as well as for several preprocessing and postprocessing options. The THATCH model of the currently applicable 350 MWth reactor is described. Input data for four sample cases are given with output available in fiche form. Installation requirements and code limitations, as well as the most common error indications are listed. 31 refs., 23 figs., 32 tabs

  18. THATCH: A computer code for modelling thermal networks of high- temperature gas-cooled nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Kroeger, P.G.; Kennett, R.J.; Colman, J.; Ginsberg, T. (Brookhaven National Lab., Upton, NY (United States))

    1991-10-01

    This report documents the THATCH code, which can be used to model general thermal and flow networks of solids and coolant channels in two-dimensional r-z geometries. The main application of THATCH is to model reactor thermo-hydraulic transients in High-Temperature Gas-Cooled Reactors (HTGRs). The available modules simulate pressurized or depressurized core heatup transients, heat transfer to general exterior sinks or to specific passive Reactor Cavity Cooling Systems, which can be air or water-cooled. Graphite oxidation during air or water ingress can be modelled, including the effects of added combustion products to the gas flow and the additional chemical energy release. A point kinetics model is available for analyzing reactivity excursions; for instance due to water ingress, and also for hypothetical no-scram scenarios. For most HTGR transients, which generally range over hours, a user-selected nodalization of the core in r-z geometry is used. However, a separate model of heat transfer in the symmetry element of each fuel element is also available for very rapid transients. This model can be applied coupled to the traditional coarser r-z nodalization. This report described the mathematical models used in the code and the method of solution. It describes the code and its various sub-elements. Details of the input data and file usage, with file formats, is given for the code, as well as for several preprocessing and postprocessing options. The THATCH model of the currently applicable 350 MW{sub th} reactor is described. Input data for four sample cases are given with output available in fiche form. Installation requirements and code limitations, as well as the most common error indications are listed. 31 refs., 23 figs., 32 tabs.

  19. The Cool ISM in S0 Galaxies. I. A Survey of Molecular Gas

    CERN Document Server

    Welch, G A; Welch, Gary A.; Sage, Leslie J.

    2003-01-01

    Lenticular galaxies remain remarkably mysterious as a class. Observations to date have not led to any broad consensus about their origins, properties and evolution, though they are often thought to have formed in one big burst of star formation early in the history of the Universe, and to have evolved relatively passively since then. In that picture, current theory predicts that stellar evolution returns substantial quantities of gas to the interstellar medium; most is ejected from the galaxy, but significant amounts of cool gas might be retained. Past searches for that material, though, have provided unclear results. We present results from a survey of molecular gas in a volume-limited sample of field S0 galaxies, selected from the Nearby Galaxies Catalog. CO emission is detected from 78 percent of the sample galaxies. We find that the molecular gas is almost always located inside the central few kiloparses of a lenticular galaxy, meaning that in general it is more centrally concentrated than in spirals. We ...

  20. Demonstration of Enabling Spar-Shell Cooling Technology in Gas Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Downs, James [Florida Turbine Technologies Inc., Jupiter, FL (United States)

    2014-12-29

    In this Advanced Turbine Program-funded Phase III project, Florida Turbine Technologies, Inc. (FTT) has developed and tested, at a pre-commercial prototypescale, spar-shell turbine airfoils in a commercial gas turbine. The airfoil development is based upon FTT’s research and development to date in Phases I and II of Small Business Innovative Research (SBIR) grants. During this program, FTT has partnered with an Original Equipment Manufacturer (OEM), Siemens Energy, to produce sparshell turbine components for the first pre-commercial prototype test in an F-Class industrial gas turbine engine and has successfully completed validation testing. This project will further the commercialization of this new technology in F-frame and other highly cooled turbine airfoil applications. FTT, in cooperation with Siemens, intends to offer the spar-shell vane as a first-tier supplier for retrofit applications and new large frame industrial gas turbines. The market for the spar-shell vane for these machines is huge. According to Forecast International, 3,211 new gas turbines units (in the >50MW capacity size range) will be ordered in ten years from 2007 to 2016. FTT intends to enter the market in a low rate initial production. After one year of successful extended use, FTT will quickly ramp up production and sales, with a target to capture 1% of the market within the first year and 10% within 5 years (2020).

  1. NOT DEAD YET: COOL CIRCUMGALACTIC GAS IN THE HALOS OF EARLY-TYPE GALAXIES

    International Nuclear Information System (INIS)

    We report new observations of circumgalactic gas in the halos of early-type galaxies (ETGs) obtained by the COS-Halos Survey with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. We find that detections of H I surrounding ETGs are typically as common and strong as around star-forming galaxies, implying that the total mass of circumgalactic material is comparable in the two populations. For ETGs, the covering fraction for H I absorption above 1016 cm–2 is ∼40%-50% within ∼150 kpc. Line widths and kinematics of the detected material show it to be cold (T ∼5 K) in comparison to the virial temperature of the host halos. The implied masses of cool, photoionized circumgalactic medium baryons may be up to 109-1011 M☉. Contrary to some theoretical expectations, strong halo H I absorbers do not disappear as part of the quenching of star formation. Even passive galaxies retain significant reservoirs of halo baryons that could replenish the interstellar gas reservoir and eventually form stars. This halo gas may feed the diffuse and molecular gas that is frequently observed inside ETGs.

  2. Mid-section of a can-annular gas turbine engine with a cooling system for the transition

    Energy Technology Data Exchange (ETDEWEB)

    Wiebe, David J.; Rodriguez, Jose L.

    2015-12-08

    A cooling system is provided for a transition (420) of a gas turbine engine (410). The cooling system includes a cowling (460) configured to receive an air flow (111) from an outlet of a compressor section of the gas turbine engine (410). The cowling (460) is positioned adjacent to a region of the transition (420) to cool the transition region upon circulation of the air flow within the cowling (460). The cooling system further includes a manifold (121) to directly couple the air flow (111) from the compressor section outlet to an inlet (462) of the cowling (460). The cowling (460) is configured to circulate the air flow (111) within an interior space (426) of the cowling (460) that extends radially outward from an inner diameter (423) of the cowling to an outer diameter (424) of the cowling at an outer surface.

  3. Extension and validation of SIMMER III code for gas cooled fast reactor

    International Nuclear Information System (INIS)

    Highlights: • SIMMER-III is extended and validated for safety studies of gas cooled fast reactor. • Equations of state and thermal physical properties of helium are implemented. • ALLEGRO reactor is simulated and the code is validated. • Unprotected loss of coolant severe accident is analyzed. - Abstract: This paper deals with extension, application and validation of the SIMMER-III code for safety studies of a gas cooled fast reactor. The equations of state and thermal physical properties of the helium gas have been prepared and implemented in the code. The geometric, thermal hydraulic and neutronic models have been set up for the ALLEGRO reactor. The code and the associated model are verified by comparing results of steady state and unprotected loss of flow with 20% remaining flow rate (ULOF-20%) with those obtained by other project partners. Reasonable or good agreements have been achieved for major physical variables. The unprotected loss of coolant accident (ULOCA) is a severe event leading to core melting and degradation that was simulated only by SIMMER in the project. In the initiating phase the clad melts and the fuel sweeps out; this triggers the first power excursion. Then the fuel becomes more mobile and further power excursions take place, which lead to core melting and degradation. The fuel is ejected by the power excursion and then moves relatively slowly to the lower part of the vessel. Finally there are only a few kilograms of fuel escaping from the vessel (into reactor container) and the released thermal energy is about 6 GJ within a period of one minute. The final power stays below 1 MW and the reactor is in a deep sub-criticality state, since half of the fuel is evacuated from the core region

  4. Contributions to the neutronic analysis of a gas-cooled fast reactor

    International Nuclear Information System (INIS)

    Highlights: → Differences on reactivity with MCNPX and TRIPOLI-4 are negligible. → Fuel lattice and core criticality calculations were done. → A higher Doppler coefficient than coolant density coefficient. → Zirconium carbide is a better reflector than silicon carbide. → Adequate active height, radial size and reflector thickness were obtained. - Abstract: In this work the Monte Carlo codes MCNPX and TRIPOLI-4 were used to perform the criticality calculations of the fuel assembly and the core configuration of a gas-cooled fast reactor (GFR) concept, currently in development. The objective is to make contributions to the neutronic analysis of a gas-cooled fast reactor. In this study the fuel assembly is based on a hexagonal lattice of fuel-pins. The materials used are uranium and plutonium carbide as fuel, silicon carbide as cladding, and helium gas as coolant. Criticality calculations were done for a fuel assembly where the axial reflector thickness was varied in order to find the optimal thickness. In order to determine the best material to be used as a reflector, in the reactor core with neutrons of high energy spectrum, criticality calculations were done for three reflector materials: zirconium carbide, silicon carbide and natural uranium. It was found that the zirconium carbide provides the best neutron reflection. Criticality calculations using different active heights were done to determine the optimal height, and the reflector thickness was adjusted. Core criticality calculations were performed with different radius sizes to determine the active radial dimension of the core. A negative temperature coefficient of reactivity was verified for the fuel. The effect on reactivity produced by changes in the coolant density was also evaluated. We present the main neutronic characteristics of a preliminary fuel and core designs for the GFR concept. ENDF-VI cross-sections libraries were used in both the MCNPX and TRIPOLI-4 codes, and we verified that the

  5. Testing and analyses of a high temperature duct for gas-cooled reactors

    International Nuclear Information System (INIS)

    A 0.6 scale model of a steam cycle gas-cooled reactor high temperature duct was tested in a closed loop helium facility. The object of the test series was to determine: 1) the thermal effects of gas permeation within the thermal barrier, 2) the plastic deformation of the metallic components, and 3) the thermal performance of the fibrous insulation. A series of tests was performed with thermal cyclings from 1000C to 7600C at 50 atmospheres until the system thermal performance had stabilized hence enabling predictions for the reactor life. Additional tests were made to assess permeation by deliberately simulating sealing weld failures thereby allowing gas flow by-pass within the primary thermal barrier. After 100 cycles the entire primary structure was found to have performed without structural failure. Due to high pressures exerted by the insulation on the cover plates and a design oversight, the thin seal sheets were unable to expand in an anticipated manner. Local buckling resulted. The insulation retained an acceptable degree of resiliency. However, some fiber damage was observed within both the high and low temperature insulation blankets. A thermal analysis was conducted to correlate the hot duct heat transfer results with those obtained from the analytical techniques used for the HTGR design using a computer thermal model representative of the duct and test setup. The thermal performance of the insulation, the temperature gradient through the structural components, the heating load to the cooling system and the permeation flow effect on heat transfer were verified. Exellent correlation between the experimental data and the analytical techniques were obtained

  6. Modular high-temperature gas-cooled reactor short term thermal response to flow and reactivity transients

    International Nuclear Information System (INIS)

    The short-term thermal response of the modular high-temperature gas-cooled reactor (MHTGR) is analyzed for a range of flow and reactivity transients. These include loss of forced circulation (LOFC) without scram, moisture ingress, spurious withdrawal of a control rod group, hypothetical large and rapid positive reactivity insertion, and a rapid core cooling event. The coupled heat transfer-neutron kinetics model is also described

  7. Numerical investigations of cooling holes system role in the protection of the walls of a gas turbine combustion chamber

    Energy Technology Data Exchange (ETDEWEB)

    Ben Sik Ali, Ahlem; Kriaa, Wassim; Mhiri, Hatem [Ecole Nationale D' Ingenieurs de Monastir, Unite de Thermique et Thermodynamique des Procedes industriels, Monastir (Tunisia); Bournot, Philippe [IUSTI, UMR CNRS 6595, Marseille (France)

    2012-05-15

    Numerical simulations in a gas turbine Swirl stabilized combustor were conducted to investigate the effectiveness of a cooling system in the protection of combustor walls. The studied combustion chamber has a high degree of geometrical complexity related to the injection system as well as the cooling system based on a big distribution of small holes (about 3,390 holes) bored on the flame tube walls. Two cases were considered respectively the flame tube without and with its cooling system. The calculations were carried out using the industrial CFD code FLUENT 6.2. The various simulations made it possible to highlight the role of cooling holes in the protection of the flame tube walls against the high temperatures of the combustion products. In fact, the comparison between the results of the two studied cases demonstrated that the walls temperature can be reduced by about 800 C by the mean of cooling holes technique. (orig.)

  8. Detailed Reaction Kinetics for CFD Modeling of Nuclear Fuel Pellet Coating for High Temperature Gas-Cooled Reactors

    International Nuclear Information System (INIS)

    The research project was related to the Advanced Fuel Cycle Initiative and was in direct alignment with advancing knowledge in the area of Nuclear Fuel Development related to the use of TRISO fuels for high-temperature reactors. The importance of properly coating nuclear fuel pellets received a renewed interest for the safe production of nuclear power to help meet the energy requirements of the United States. High-temperature gas-cooled nuclear reactors use fuel in the form of coated uranium particles, and it is the coating process that was of importance to this project. The coating process requires four coating layers to retain radioactive fission products from escaping into the environment. The first layer consists of porous carbon and serves as a buffer layer to attenuate the fission and accommodate the fuel kernel swelling. The second (inner) layer is of pyrocarbon and provides protection from fission products and supports the third layer, which is silicon carbide. The final (outer) layer is also pyrocarbon and provides a bonding surface and protective barrier for the entire pellet. The coating procedures for the silicon carbide and the outer pyrocarbon layers require knowledge of the detailed kinetics of the reaction processes in the gas phase and at the surfaces where the particles interact with the reactor walls. The intent of this project was to acquire detailed information on the reaction kinetics for the chemical vapor deposition (CVD) of carbon and silicon carbine on uranium fuel pellets, including the location of transition state structures, evaluation of the associated activation energies, and the use of these activation energies in the prediction of reaction rate constants. After the detailed reaction kinetics were determined, the reactions were implemented and tested in a computational fluid dynamics model, MFIX. The intention was to find a reduced mechanism set to reduce the computational time for a simulation, while still providing accurate results

  9. Detailed Reaction Kinetics for CFD Modeling of Nuclear Fuel Pellet Coating for High Temperature Gas-Cooled Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Battaglia, Francine

    2008-11-29

    The research project was related to the Advanced Fuel Cycle Initiative and was in direct alignment with advancing knowledge in the area of Nuclear Fuel Development related to the use of TRISO fuels for high-temperature reactors. The importance of properly coating nuclear fuel pellets received a renewed interest for the safe production of nuclear power to help meet the energy requirements of the United States. High-temperature gas-cooled nuclear reactors use fuel in the form of coated uranium particles, and it is the coating process that was of importance to this project. The coating process requires four coating layers to retain radioactive fission products from escaping into the environment. The first layer consists of porous carbon and serves as a buffer layer to attenuate the fission and accommodate the fuel kernel swelling. The second (inner) layer is of pyrocarbon and provides protection from fission products and supports the third layer, which is silicon carbide. The final (outer) layer is also pyrocarbon and provides a bonding surface and protective barrier for the entire pellet. The coating procedures for the silicon carbide and the outer pyrocarbon layers require knowledge of the detailed kinetics of the reaction processes in the gas phase and at the surfaces where the particles interact with the reactor walls. The intent of this project was to acquire detailed information on the reaction kinetics for the chemical vapor deposition (CVD) of carbon and silicon carbine on uranium fuel pellets, including the location of transition state structures, evaluation of the associated activation energies, and the use of these activation energies in the prediction of reaction rate constants. After the detailed reaction kinetics were determined, the reactions were implemented and tested in a computational fluid dynamics model, MFIX. The intention was to find a reduced mechanism set to reduce the computational time for a simulation, while still providing accurate results

  10. Case study on natural gas application for district heating and cooling in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Maues, Jair Arone [Pontificia Universidade Catolica do Rio de Janeiro (IE/PUC-Rio), Rio de Janeiro, RJ (Brazil). Inst. de Energia; Akiyama, Junichi [Mitsui Gas e Energia do Brasil Ltda., Rio de janeiro, RJ (Brazil)

    2012-07-01

    The distributed cogeneration applying natural gas consists in an excellent alternative to use this source, but it is limited by a compatible heat demand that must be found in its application. District heating and cooling solutions can overcome this hurdle, especially in Brazil, a tropical country, where new industrial and commercial enterprises usually install central air conditioning systems. By 2020 natural gas demand shall reach a value of more than 200 MM m{sup 3} per day, accordingly to the Brazilian Energy Research Office (EPE, 2011). An expressive part of it could be consumed in cogeneration systems like the one described in this paper. This project had a special taxes exception rule applied. The chilled water and heated thermal oil produced were not taxed at all. But these two DHC utilities could obtain a different treatment if someone considers this is a tricky way of power and heat trading, which should be taxed as electricity and natural gas normally are. A bolder legislation with respect to the export of energy surplus would facilitate the project and operation of this kind of system, because the basic premise would be to attend the thermal demand with the electrical power installed, maximizing the global efficiency of the installation. An average 8 GW of Brazilian power demand, with roughly 50 MMm{sup 3}/day of natural gas consumption, could be attended by distributed energy gas cogeneration enterprises. If this prediction were totally accomplished it would bring the Brazilian participation of distributed energy in total power generation to values close to 10% in 2020, value already reached in average by the world biggest electricity's consumer countries (WADE, 2006). This also would mean an equivalent investment economy of approximately 11,000 MW in transmission and distribution lines capacity (author)

  11. High temperature corrosion of structural materials under gas-cooled reactor helium

    International Nuclear Information System (INIS)

    The Generation IV International Forum has selected six promising nuclear power systems for further collaborative investigations and development. Among these six concepts, two candidates are Gas Cooled Reactors (GCR), namely the Very High Temperature Reactor (VHTR) and the Gas-cooled Fast Reactor (GFR). The CEA has launched a R and D program on the metallic materials for application in an innovative GCR. Structural GCR alloys have been extensively studied in the past three decades. Some critical aspects for the steels and nickel base alloys resistance under the service conditions are microstructural stability, creep strength and compatibility with the cooling gas. The coolant, namely helium, proved to contain impurities mainly H2, CO, CH4, N2 and steam in the microbar range that interact with metals at high temperature. Surface scale formation, bulk carburisation and/or decarburisation can occur, depending on the atmosphere characteristics, primarily the effective oxygen partial pressure and carbon activity, on the temperature and on the alloys chemical composition. These structural transformations can notably influence the mechanical properties: carburisation may induce a loss in toughness and ductility whereas decarburisation impedes the creep strength. There is a valuable theoretical as well as practical knowledge on the corrosion of high temperature alloys in the primary circuit of a GCR but this past experience is not sufficient to qualify every component in a future reactor. On the one hand, the material environment could be significantly different from the former GCR's, especially regarding the higher temperature. On the other hand, the materials of interest are partly different. Ni-Cr-W alloys, for instance, may offer significant improvement in the maximum operating temperature as far as the mechanical properties are concerned. However, their corrosion resistance toward the GCR atmosphere is still unknown. We describe here our first corrosion tests of Haynes

  12. Research on enhancement of natural circulation capability in lead-bismuth alloy cooled reactor by using gas-life pump

    International Nuclear Information System (INIS)

    The gas-lift pump has been adopted to enhance the natural circulation capability in the conceptual designs of lead-bismuth alloy cooled reactors such as ADS and LMFR. The natural circulation capability and the system safety have been obviously influenced by the two phase flow characteristics of liquid metal-inert gas. The numerical research was performed to evaluate the natural circulation capability of lead-bismuth alloy cooled ADS with gas-lift pump. Based on the drift-flux flow model, void fraction prediction model and frictional pressure drop prediction model were adopted in the numerical simulation. The effects of the gas mass flow rate, the gas quality, the bubble diameter and the height of rising pipe on natural circulation capability of gas-lift pump were analyzed. The results show that in bubbly flow pattern, for a fixed value of gas mass flow rate, the natural circulation capability increases with the decrease of the bubble diameter. In the bubbly flow, slug flow, churn flow and annular flow patterns, with the gas mass flow rate and the gas quality increase, the natural circulation capability increases initially and then decreases. As the height of rising pipe increases, the natural circulation flow rate goes up. The flow parameters influence the thermal hydraulic characteristics of the reactor core significantly. Therefore, in practical engineering application, the gas mass flow rate, gas quality, bubble diameter and rising pipe height are very important parameters for the design of gas-lift pump systems. The present work is helpful for optimizing the design of the natural circulation cooling system by gas-lift pump. (authors)

  13. Axisymmetric whole pin life modelling of advanced gas-cooled reactor nuclear fuel

    International Nuclear Information System (INIS)

    Thermo-mechanical contributions to pellet–clad interaction (PCI) in advanced gas-cooled reactors (AGRs) are modelled in the ABAQUS finite element (FE) code. User supplied sub-routines permit the modelling of the non-linear behaviour of AGR fuel through life. Through utilisation of ABAQUS’s well-developed pre- and post-processing ability, the behaviour of the axially constrained steel clad fuel was modelled. The 2D axisymmetric model includes thermo-mechanical behaviour of the fuel with time and condition dependent material properties. Pellet cladding gap dynamics and thermal behaviour are also modelled. The model treats heat up as a fully coupled temperature-displacement study. Dwell time and direct power cycling was applied to model the impact of online refuelling, a key feature of the AGR. The model includes the visco-plastic behaviour of the fuel under the stress and irradiation conditions within an AGR core and a non-linear heat transfer model. A multiscale fission gas release model is applied to compute pin pressure; this model is coupled to the PCI gap model through an explicit fission gas inventory code. Whole pin, whole life, models are able to show the impact of the fuel on all segments of cladding including weld end caps and cladding pellet locking mechanisms (unique to AGR fuel). The development of this model in a commercial FE package shows that the development of a potentially verified and future-proof fuel performance code can be created and used

  14. Improvement of the decay heat removal characteristics of the generation IV gas-cooled fast reactor

    International Nuclear Information System (INIS)

    The majority of NPPs worldwide are currently light water reactors, using ordinary water as both coolant and moderator. (...) For the longer-term future, viz. beyond the year 2030, Research and Development is currently ongoing on Generation IV NPPs, aimed at achieving closure of the nuclear fuel cycle, and hence both drastically improved utilization of fuel resources and minimization of long-lived radioactive wastes. Since the very beginning of the international cooperation on Generation IV, viz. the year 2000, the main research interest in Europe as regards the advanced fast-spectrum systems needed for achieving complete fuel cycle closure, has been for the Sodium-cooled Fast Reactor (SFR). However, the Gas-cooled Fast Reactor (GFR) is currently considered as the main back-up solution. Like the SFR, the GFR is an efficient breeder, also able to work as iso-breeder using simply natural uranium as feed and producing waste which is predominantly in the form of fission products. The main drawback of the GFR is the difficulty to evacuate decay heat following a loss-of-coolant accident (LOCA) due to the low thermal inertia of the core, as well as to the low coolant density. The present doctoral research focuses on the improvement of decay heat removal (DHR) for the Generation-IV GFR. The reference GFR system design considered in the thesis is the 2006 CEA concept, with a power of 2400 MWth. The CEA 2006 DHR strategy foresees, in all accidental cases (independent of the system pressure), that the reactor is shut down. For high pressure events, dedicated DHR loops with blowers and heat exchangers are designed to operate when the power conversion system cannot be used to provide acceptable core temperatures under natural convection conditions. For depressurized events, the strategy relies on a dedicated small containment (called the guard containment) providing an intermediate back-up pressure. The DHR blowers, designed to work under these pressure conditions, need to be

  15. Heat and momentum transfer in a gas coolant flow through a circular pipe in a high temperature gas cooled reactor

    International Nuclear Information System (INIS)

    In Japan Atomic Energy Research Institute (JAERI), a very high temperature gas cooled reactor (VHTR) has been researched and developed with a purpose of attaining a coolant temperature of around 1000degC at the reactor outlet. In order to design VHTR, comprehensive knowledge is required on thermo-hydraulic characteristics of laminar-turbulent transition, of coolant flow with large thermal property variation due to temperature difference, and of heat transfer deterioration. In the present investigation, experimental and analytical studies are made on a gas flow in a circular tube to elucidate the thermo-hydraulic characteristics. Friction factors and heat transfer coefficients in transitional flows are obtained. Influence of thermal property variation on the friction factor is qualitatively determined. Heat transfer deterioration in the turbulent flow subjected to intense heating is experimentally found to be caused by flow laminarization. The analysis based on a k-kL two-equation model of turbulence predicts well the experimental results on friction factors and heat transfer coefficients in flows with thermal property variation and in laminarizing flows. (author)

  16. Using high temperature gas-cooled reactors for greenhouse gas reduction and energy neutral production of phosphate fertilizers

    International Nuclear Information System (INIS)

    Highlights: • We estimate the energy requirements of wet- and thermal phosphate rock processing. • We estimate the amount of U needed to operate a representative HTGR. • Energy neutral phosphate fertilizer production is theoretically possible. - Abstract: This paper discusses how high temperature gas-cooled reactors (HTGRs) could provide energy for phosphate rock (PR) processing while extracting uranium (U) from the processed PR that can again be used as raw material for nuclear reactor fuel that may power the greenhouse gas lean energy source employed. First estimates using a HTGR presently constructed in China (HTR-PM) conclude that a concentration of approximately 80 mg/kg U in PR is sufficiently high for energy neutral wet acid PR processing with waste treatment and a concentration of approximately 110 mg/kg U is adequate to promote energy intensive high quality thermal phosphoric acid production. In addition, the recovery of U from PRs yields beneficial side-effects in a way that U loads on agricultural soils are reduced and consequently contamination of groundwater with U will be diminished

  17. Analysis of the horizontal flow in the advanced gas-cooled reactor

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Y. [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); He, S., E-mail: s.he@sheffield.ac.uk [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Ganesan, P. [Department of Mechanical Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Gotts, J. [EDF Energy, Barnwood, Gloucester GL4 3RS (United Kingdom)

    2014-06-01

    Highlights: • CFD is used to assess the effect of horizontal flows in AGRs. • The horizontal flows can reduce the graphite brick temperature significantly. • Such effects are not taken into consideration in current engineering calculations. • There might be flow instabilities when the fuel channel flow is very low but horizontal flows reduce its possibility. - Abstract: The purpose of the paper is to report a computational investigation of horizontal flows in the UK advanced-gas-cooled reactor (AGR) by using computational fluid dynamics with ANSYS FLUENT. The study is relevant to practical issues encountered in some AGR stations currently in operation in the UK. It is carried out using a comparative approach based on the results of two contrasting models: one simulating the full effect of the cross flow, the other simulating the simplified approach currently employed by the industry which neglects the momentum of the horizontal cross flow. The study reveals that the horizontal cross flow plays a significant role in the cooling of the moderator brick, while the axial variation of the brick geometry also significantly changes the distribution of the temperature within the brick. It is also found that under some circumstances the so-called horizontal inter-brick leakage (HIBL) flow could influence the cooling performance in the narrow gaps, resulting in a local hot spot. Furthermore, there may be flow instabilities in the flows in AGR fuel channels due to the interactions between the flow in the main arrowhead flow passages and that in some narrow passages connected to it, but the influence on the brick temperature is negligible. Horizontal cross flow has an effect of reducing such instabilities.

  18. Determination of the extraction efficiency for $^{233}$U source $\\alpha$-recoil ions from the MLL buffer-gas stopping cell

    CERN Document Server

    von der Wense, Lars; Laatiaoui, Mustapha; Thirolf, Peter G

    2016-01-01

    Following the $\\alpha$ decay of $^{233}$U, $^{229}$Th recoil ions are shown to be extracted in a significant amount from the MLL buffer-gas stopping cell. The produced recoil ions and subsequent daughter nuclei are mass purified with the help of a customized quadrupole mass spectrometer. The combined extraction and mass-purification efficiency for $^{229}$Th$^{3+}$ is determined via MCP-based measurements and via the direct detection of the $^{229}$Th $\\alpha$ decay. A large value of $(10\\pm2)$\\% for the combined extraction and mass-purification efficiency of $^{229}$Th$^{3+}$ is obtained at a mass resolution of about 1 u/e. In addition to $^{229}$Th, also other $\\alpha$-recoil ions of the $^{233,232}$U decay chains are addressed.

  19. Search for Solar Axions by the CERN Axion Solar Telescope with 3 He Buffer Gas: Closing the Hot Dark Matter Gap

    CERN Document Server

    Arik, M; Barth, K.; Belov, A.; Borghi, S.; Brauninger, H.; Cantatore, G.; Carmona, J.M.; Cetin, S.A.; Collar, J.I.; Da Riva, E.; Dafni, T.; Davenport, M.; Eleftheriadis, C.; Elias, N.; Fanourakis, G.; Ferrer-Ribas, E.; Friedrich, P.; Galan, J.; Garcia, J.A.; Gardikiotis, A.; Garza, J.G.; Gazis, E.N.; Geralis, T.; Georgiopoulou, E.; Giomataris, I.; Gninenko, S.; Gomez, H.; Gomez Marzoa, M.; Gruber, E.; Guthorl, T.; Hartmann, R.; Hauf, S.; Haug, F.; Hasinoff, M.D.; Hoffmann, D.H.H.; Iguaz, F.J.; Irastorza, I.G.; Jacoby, J.; Jakovcic, K.; Karuza, M.; Konigsmann, K.; Kotthaus, R.; Krcmar, M.; Kuster, M.; Lakic, B.; Lang, P.M.; Laurent, J.M.; Liolios, A.; Ljubicic, A.; Lozza, V.; Luzon, G.; Neff, S.; Niinikoski, T.; Nordt, A.; Papaevangelou, T.; Pivovaroff, M.J.; Raffelt, G.; Riege, H.; Rodriguez, A.; Rosu, M.; Ruz, J.; Savvidis, I.; Shilon, I.; Silva, P.S.; Solanki, S.K.; Stewart, L.; Tomas, A.; Tsagri, M.; van Bibber, K.; Vafeiadis, T.; Villar, J.; Vogel, J.K.; Yildiz, S.C.; Zioutas, K.

    2014-01-01

    The CERN Axion Solar Telescope (CAST) has finished its search for solar axions with 3^He buffer gas, covering the search range 0.64 eV < m_a <1.17 eV. This closes the gap to the cosmological hot dark matter limit and actually overlaps with it. From the absence of excess X-rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g_ag < 3.3 x 10^{-10} GeV^{-1} at 95% CL, with the exact value depending on the pressure setting. Future direct solar axion searches will focus on increasing the sensitivity to smaller values of g_a, for example by the currently discussed next generation helioscope IAXO.

  20. Search for solar axions with the Time Projection Chamber of the CERN Axion Solar Telescope with 4-Helium as buffer gas

    CERN Document Server

    Ruz, J; García Irastorza, I

    CAST (CERN Axion Solar Telescope) is a helioscope looking for axions coming from the solar core to the Earth. The experiment, located at CERN, is based on the Primakoff effect and uses a magnetic field of 9 Tesla provided by a decommissioned LHC magnet. CAST is able to follow the Sun during sunrise and sunset and, therefore, different X-ray detectors are mounted on both ends of the magnet waiting for a photon from axion-to-photon conversion due to the Primakoff effect. During its First Phase, which concluded in 2004, the TPC detector of CAST looked for axions with masses up to 0.02 eV. By using a Helium-4 buffer gas, CAST's TPC detector has been able to re-establish the coherence needed to scan for axions with masses up to 0.39 eV, technique that allows CAST to look into the theoretical regions for axions.

  1. Buffer-Free GeSn and SiGeSn Growth on Si Substrate Using In Situ SnD4 Gas Mixing

    Science.gov (United States)

    Mosleh, Aboozar; Alher, Murtadha; Cousar, Larry C.; Du, Wei; Ghetmiri, Seyed Amir; Al-Kabi, Sattar; Dou, Wei; Grant, Perry C.; Sun, Greg; Soref, Richard A.; Li, Baohua; Naseem, Hameed A.; Yu, Shui-Qing

    2016-04-01

    Buffer-free GeSn and SiGeSn films have been deposited on Si via a cold-wall, ultra-high vacuum chemical vapor deposition reactor using in situ gas mixing of deuterated stannane, silane and germane. Material characterization of the films using x-ray diffraction and transmission electron microscopy shows crystalline growth with an array of misfit dislocation formed at the Si substrate interface. Energy dispersive x-ray maps attained from the samples show uniform incorporation of the elements. The Z-contrast map of the high-angle annular dark-field of the film cross section shows uniform incorporation along the growth as well. Optical characterization of the GeSn films through photoluminescence technique shows reduction in the bandgap edge of the materials.

  2. Technologies for gas cooled reactor decommissioning, fuel storage and waste disposal. Proceedings of a technical committee meeting

    International Nuclear Information System (INIS)

    Gas cooled reactors (GCRs) and other graphite moderated reactors have been important part of the world's nuclear programme for the past four decades. The wide diversity in status of this very wide spectrum of plants from initial design to decommissioning was a major consideration of the International Working group on Gas Cooled Reactors which recommended IAEA to convene a Technical Committee Meeting dealing with GCR decommissioning, including spent fuel storage and radiological waste disposal. This Proceedings includes papers 25 papers presented at the Meeting in three sessions entitled: Status of Plant Decommissioning Programmes; Fuels Storage Status and Programmes; waste Disposal and decontamination Practices. Each paper is described here by a separate abstract

  3. Solar heating, cooling and domestic hot water system installed at Columbia Gas System Service Corporation, Columbus, Ohio

    Science.gov (United States)

    1980-01-01

    The solar energy system installed in the building has 2,978 sq ft of single axis tracking, concentrating collectors and provides solar energy for space heating, space cooling and domestic hot water. A 1,200,000 Btu/hour water tube gas boiler provides hot water for space heating. Space cooling is provided by a 100 ton hot water fired absorption chiller. Domestic hot water heating is provided by a 50 gallon natural gas domestic storage water heater. Extracts from the site files, specification references, drawings, installation, operation and maintenance instructions are included.

  4. Solar heating, cooling and domestic hot water system installed at Columbia Gas System Service Corporation, Columbus, Ohio

    Science.gov (United States)

    1980-11-01

    The solar energy system installed in the building has 2,978 sq ft of single axis tracking, concentrating collectors and provides solar energy for space heating, space cooling and domestic hot water. A 1,200,000 Btu/hour water tube gas boiler provides hot water for space heating. Space cooling is provided by a 100 ton hot water fired absorption chiller. Domestic hot water heating is provided by a 50 gallon natural gas domestic storage water heater. Extracts from the site files, specification references, drawings, installation, operation and maintenance instructions are included.

  5. Gas cooled fast reactor materials: compatibility and reaction kinetics of fuel/matrices couples

    International Nuclear Information System (INIS)

    Fourth Generation Gas cooled Fast Reactor concept implies a fast neutron spectrum and aims to lead to an iso-generation of minor actinides. Criteria have been defined for these fuels such as: high core filling factor, efficient fuel cooling, low operation temperature, i.e. 400-850 deg C, good fission product retention, burn-ups in the range of 5-8 atom%, Pu content in the range of 15-25%. Materials matching this demand are considered: mixed uranium - plutonium nitrides and carbides as fuels, whereas TiN, TiC, ZrN, ZrC, SiC are investigated as inert matrices. Thermo-chemical compatibility studies have been carried out, mostly for (U,Pu)N/SiC and (U,Pu)N/TiN couples. They have been associated to matching diffusional studies. For the first studies, accidental reactor conditions have been chosen (1600 deg C) so as to select a couple. Results are presented in terms of nature and quantity of resulting phases identified by XRD and SEM for thermodynamical equilibrium experiments. (authors)

  6. Measurement of the Radiative Cooling Coefficient of Krypton Gas in the Frascati Tokamak Upgrade

    Science.gov (United States)

    Fournier, K. B.; Goldstein, W. H.; Pacella, D.; Mazzitelli, G.; Gabellieri, L.; Leigheb, M.; de Angelis, R.; May, M. J.; Regan, S. P.; Stutman, D.; Soukhanovskii, V.; Finkenthal, M.; Moos, H. W.

    1997-11-01

    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 extract the krypton impurity radial profile and the radiative cooling rate for krypton gas in the Frascati Tokamak Upgrade (FTU). The measured bolometric, soft x-ray and visible bremmstrhalung signals are Abel inverted and then incorporated in an analytic model. Using the known (calculated) ionization state distribution, the radial power loss profile for krypton is derived. Anamolous transport is assumed to have a negligible affect on the total krypton radiation profile; this assumption is confirmed using the derived krypton radiation rate in a plasma transport modeling code. 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. These initial results are part of a multiwavelength impurity spectroscopy campaign that will measure transport profiles and basic atomic data in the FTU. Work carried out under the auspices of the U.S. DoE, Contract No. W-7405-ENG-48.

  7. Gas-Cooled Fast Reactor: A Historical Overview and Future Outlook

    Directory of Open Access Journals (Sweden)

    W. F. G. van Rooijen

    2009-01-01

    Full Text Available A review is given of developments in the area of Gas-Cooled Fast Reactors (GCFR in the period from roughly 1960 until 1980. During that period, the GCFR concept was expected to increase the breeding gain, the thermal efficiency of a nuclear power plant, and alleviate some of the problems associated with liquid metal coolants. During this period, the GCFR concept was found to be more challenging than liquid-metal-cooled reactors, and none were ever constructed. In the second part of the paper, we provide an overview of the investigations on GCFR since the year 2000, when the Generation IV Initiative rekindled interest in this reactor type. The new GCFR concepts focus primarily on sustainable nuclear power, with very efficient resource use, minimum waste, and a very strong focus on (passive safety. An overview is presented of the main design characteristics of these Gen IV GCFRs, and a literature list is provided to guide the interested reader towards more detailed publications.

  8. Summary of the experimental multi-purpose very high temperature gas cooled reactor design

    International Nuclear Information System (INIS)

    In 1969 JAERI started the design study of the Experimental Multi-purpose Very High Temperature Gas Cooled Reactor (the Experimental VHTR), and trial design, preliminary design, conceptual design, comprehensive system design and the first and second stage of detailed design have been carried out. Hereafter JAERI is going to pursue the rationalized Experimental VHTR system which maintains the required functions and performance and has the potential for reducing the construction cost, utilizing extensively the inherent safety features of HTGRs. In the current design, i.e. the second stage of detailed design, the reactor outlet coolant temperature is 9500C to aim earlier construction of the Experimental VHTR, according to the specification in ''Long-term plan for the development and utilization of nuclear energy'' revised by Japan Atomic Energy Commission in June 1982. This report presents the results based mainly on the comprehensive system design (completed by 1980.3) which is the last overall system design of the Experimental VHTR aiming 10000C reactor outlet coolant temperature and partially on the first stage (completed by 1981.3) of detailed design in the form of ''an application of reactor construction permit, Appendix 8'', excepting comformance with ''Safety Design Requirements'' which correspond to ''Safety Design Criteria for Water Cooled Nuclear Power Plants issued by Japan Nuclear Safety Commission''. (author)

  9. Structure interaction due to thermal bowing of shrouds in steam generator of gas-cooled reactor

    International Nuclear Information System (INIS)

    The design of the gas-cooled reactor steam generators includes a tube bundle support plate system which restrains and supports the helical tubes in the steam generator. The support system consists of an array of radially oriented, perforated plates through which the helical tube coils are wound. These support plates have tabs on their edges which fit into vertical slots in the inner and outer shrouds. When the helical tube bundle and support plates are installed in the steam generator, they most likely cannot fit evenly between the inner and outer shrouds. This imperfection leads to different gaps between two extreme sides of the tube bundle and the shrouds. With different gaps through the tube bundle height, the helium flow experiences different cooling effects from the tube bundle. Hence, the temperature distribution in the shrouds will be non-uniform circumferentially since their surrounding helium flow temperatures are varied. These non-uniform temperatures in the shrouds result in the phenomenon of thermal bowing of shrouds

  10. Swiss activities in the field of gas-cooled reactors in 1983

    International Nuclear Information System (INIS)

    Swiss industrial companies and the Swiss Federal Institute for Reactor Research (EIR) have been involved in the development of Gas Cooled Reactors since 1968. A significant contribution has been made to the HHT-Project (High Temperature Reactor with a Helium Turbine) in close cooperation with German partners between 1973 and 1982. Both the Swiss and the German partners intend to continue the collaboration within the framework of the German project HTR-500. A four year-working program for the Swiss partners was established in the beginning of 1983. However, since the request for financial support addressed to the Swiss Government has not yet been granted, work has been performed only to a limited extent so far. The activities of the Swiss partners in 1983 are briefly presented in the report

  11. High Temperature Gas-Cooled Reactor Projected Markets and Preliminary Economics

    Energy Technology Data Exchange (ETDEWEB)

    Larry Demick

    2011-08-01

    This paper summarizes the potential market for process heat produced by a high temperature gas-cooled reactor (HTGR), the environmental benefits reduced CO2 emissions will have on these markets, and the typical economics of projects using these applications. It gives examples of HTGR technological applications to industrial processes in the typical co-generation supply of process heat and electricity, the conversion of coal to transportation fuels and chemical process feedstock, and the production of ammonia as a feedstock for the production of ammonia derivatives, including fertilizer. It also demonstrates how uncertainties in capital costs and financial factors affect the economics of HTGR technology by analyzing the use of HTGR technology in the application of HTGR and high temperature steam electrolysis processes to produce hydrogen.

  12. Critical evaluation of high-temperature gas-cooled reactors applicable to coal conversion

    International Nuclear Information System (INIS)

    A critical review is presented of the technology and costs of very high-temperature gas-cooled reactors (VHTRs) applicable to nuclear coal conversion. Coal conversion processes suitable for coupling to reactors are described. Vendor concepts of the VHTR are summarized. The materials requirements as a function of process temperature in the range 1400 to 20000F are analyzed. Components, environmental and safety factors, economics and nuclear fuel cycles are reviewed. It is concluded that process heat supply in the range 1400 to 15000F could be developed with a high degree of assurance. Process heat at 16000F would require considerably more materials development. While temperatures up to 20000F appear to be attainable, considerably more research and risk were involved. A demonstration plant would be required as a step in the commercialization of the VHTR

  13. Power flattening on modified CANDLE small long life gas-cooled fast reactor

    Energy Technology Data Exchange (ETDEWEB)

    Monado, Fiber [Nuclear Physics and Biophysics Research Group, Dept. of Physics, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Bandung, Indonesia and Dept. of Physics, Faculty of Mathematics and Natural Sciences, Sriwijaya University (Indonesia); Su' ud, Zaki; Waris, Abdul; Basar, Khairul [Nuclear Physics and Biophysics Research Group, Dept. of Physics, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Bandung (Indonesia); Ariani, Menik [Dept. of Physics, Faculty of Mathematics and Natural Sciences, Sriwijaya University (Indonesia); Sekimoto, Hiroshi [CRINES, Tokyo Institute of Technology, O-okoyama, Meguro-ku, Tokyo 152-8550 (Japan)

    2014-09-30

    Gas-cooled Fast Reactor (GFR) is one of the candidates of next generation Nuclear Power Plants (NPPs) that expected to be operated commercially after 2030. In this research conceptual design study of long life 350 MWt GFR with natural uranium metallic fuel as fuel cycle input has been performed. Modified CANDLE burn-up strategy with first and second regions located near the last region (type B) has been applied. This reactor can be operated for 10 years without refuelling and fuel shuffling. Power peaking reduction is conducted by arranging the core radial direction into three regions with respectively uses fuel volume fraction 62.5%, 64% and 67.5%. The average power density in the modified core is about 82 Watt/cc and the power peaking factor decreased from 4.03 to 3.43.

  14. 2400MWt GAS-COOLED FAST REACTOR DHR STUDIES STATUS UPDATE.

    Energy Technology Data Exchange (ETDEWEB)

    CHENG,L.Y.; LUDEWIG, H.

    2007-06-01

    A topical report on demonstrating the efficacy of a proposed hybrid active/passive combination approach to the decay heat removal for an advanced 2400MWt GEN-IV gas-cooled fast reactor was published in March 2006. The analysis was performed with the system code RELAP5-3D (version 2.4.1.1a) and the model included the full complement of the power conversion unit (PCU): heat exchange components (recuperator, precooler, intercooler) and rotating machines (turbine, compressor). A re-analysis of the success case in Ref is presented in this report. The case was redone to correct unexpected changes in core heat structure temperatures when the PCU model was first integrated with the reactor model as documented in Ref [1]. Additional information on the modeling of the power conversion unit and the layout of the heat exchange components is provided in Appendix A.

  15. Adaptation of a robot and tools for dismantling of a gas-cooled reactor

    International Nuclear Information System (INIS)

    This report details the progress on a research programme to develop the techniques and design necessary to facilitate the use of commercially available industrial manipulator systems and cutting tools in nuclear environments, particularly that envisaged whilst decommissioning a gas-cooled reactor. The technology for the type of control and the machines to perform it already exist in the form of industrial-type robots. Development of the techniques for using these machines in a more operator-sensitive environment, together with the requirements of decontamination and radiation tolerance will enable them to be used in place of expensive purpose-built machines at a considerable cost saving. From this work it was possible to highlight the viability and associated costs of modifying a standard manipulator for use in decommissioning operations

  16. Conditioning of graphite bricks from dismantled gas cooled reactors for disposal

    International Nuclear Information System (INIS)

    Dismantling of gas-cooled reactors to decommissioning involves tens of thousands of low-level radioactive graphite bricks containing less than 400 GBq of tritium per metric ton, less than 20 GBq.t-1 of 14C and less than 2 GBq of 36C1. The long half-life of the last two nuclides may require long-term conditioning. Core impregnation is one way to minimize leaching under these conditions. The authors show that core impregnation is possible using extremely durable pitches or bitumens, that inspection is possible by porosity monitoring and X-ray examination, and that satisfactory leach test results have been obtained on actual graphite samples from a reactor operated for 20 years. The very simple technology required for industrial implementation is discussed

  17. High temperature gas-cooled reactor (HTGR) graphite pebble fuel: Review of technologies for reprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Mcwilliams, A. J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-09-08

    This report reviews literature on reprocessing high temperature gas-cooled reactor graphite fuel components. A basic review of the various fuel components used in the pebble bed type reactors is provided along with a survey of synthesis methods for the fabrication of the fuel components. Several disposal options are considered for the graphite pebble fuel elements including the storage of intact pebbles, volume reduction by separating the graphite from fuel kernels, and complete processing of the pebbles for waste storage. Existing methods for graphite removal are presented and generally consist of mechanical separation techniques such as crushing and grinding chemical techniques through the use of acid digestion and oxidation. Potential methods for reprocessing the graphite pebbles include improvements to existing methods and novel technologies that have not previously been investigated for nuclear graphite waste applications. The best overall method will be dependent on the desired final waste form and needs to factor in the technical efficiency, political concerns, cost, and implementation.

  18. Appraisal of possible combustion hazards associated with a high-temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    The report presents a study of combustion hazards that may be associated with the High Temperature Gas Cooled Reactor (HTGR) in the event of a primary coolant circuit depressurization followed by water or air ingress into the prestressed concrete reactor vessel (PCRV). Reactions between graphite and steam or air produce the combustible gases H2 and/or CO. When these gases are mixed with air in the containment vessel (CV), flammable mixtures may be formed. Various modes of combustion including diffusion or premixed flames and possibly detonation may be exhibited by these mixtures. These combustion processes may create high over-pressure, pressure waves, and very hot gases within the CV and hence may threaten the structural integrity of the CV or damage the instrumentation and control system installations within it. Possible circumstances leading to these hazards and the physical characteristics related to them are delineated and studied in the report

  19. Dynamic response simulation for high temperature gas-cooled reactor with indirect closed Brayton cycle

    International Nuclear Information System (INIS)

    A transient simulation program is developed in order to study dynamic characteristics of high temperature gas-cooled reactor with indirect closed Brayton cycle. After the brief introduction to such a plant, detailed mathematical models for important installations are described in the paper. By inducing step positive reactivity into the reactor, it looks like that the powers of turbo machine installations have a different growth rate accompanied with small increase of reactor power. Furthermore, this paper shows the temperature changes of reactor and heat exchangers. For the heat exchangers of the whole secondary loop, the pressure changes behave quite differently for those three sections divided by turbine, low pressure compressor and high pressure compressor. For all these equipments, the simulation program gives reasonable results and is in accordance with dynamic characteristics of their own. (authors)

  20. Monte Carlo studies on the burnup measurement for the high temperature gas cooling reactor

    International Nuclear Information System (INIS)

    Online fuel pebble burnup measurement in a future high temperature gas cooling reactor is proposed for implementation through a high purity germanium (HPGe) gamma spectrometer. By using KORIGEN software and MCNP Monte Carlo simulations, the single pebble gamma radiations to be recorded in the detector are simulated under different irradiation histories. A specially developed algorithm is applied to analyze the generated spectra to reconstruct the gamma activity of the 137Cs monitoring nuclide. It is demonstrated that by taking into account the intense interfering peaks, the 137Cs activity in the spent pebbles can be derived with a standard deviation of 3.0% (1σ). The results support the feasibility of utilizing the HPGe spectrometry in the online determination of the pebble burnup in future modular pebble bed reactors. (authors)

  1. Nonlinear dynamic analysis of prismatic elements for high-temperature gas-cooled reactor cores

    International Nuclear Information System (INIS)

    The high-temperature gas-cooled reactor (HTGR) core consists of several thousand prismatic graphite fuel elements arranged in columns within a prestressed concrete vessel. A major research and development effort was initiated in 1970 at General Atomic Company to study the dynamic response of the HTGR core arrangement to seismic excitation. A discussion is pesented of the history and some of the results of this effort with respect to the advances made in the development of analytical methods. The computer programs developed to perform the analysis are described, along with certain techniques and the modeling required to utilize them. The nonlinear dynamic analysis techniques employed to analyze the HTGR core are described

  2. Homogenization of some radiative heat transfer models: application to gas-cooled reactor cores

    International Nuclear Information System (INIS)

    In the context of homogenization theory we treat some heat transfer problems involving unusual (according to the homogenization) boundary conditions. These problems are defined in a solid periodic perforated domain where two scales (macroscopic and microscopic) are to be taken into account and describe heat transfer by conduction in the solid and by radiation on the wall of each hole. Two kinds of radiation are considered: radiation in an infinite medium (non-linear problem) and radiation in cavity with grey-diffuse walls (non-linear and non-local problem). The derived homogenized models are conduction problems with an effective conductivity which depend on the considered radiation. Thus we introduce a framework (homogenization and validation) based on mathematical justification using the two-scale convergence method and numerical validation by simulations using the computer code CAST3M. This study, performed for gas cooled reactors cores, can be extended to other perforated domains involving the considered heat transfer phenomena. (author)

  3. Parameter estimation from dragon high temperature gas cooled reactor dynamic experiments

    International Nuclear Information System (INIS)

    Dynamic experiments were performed on the Dragon high temperature gas cooled reactor at full power, 20 MW. Both terminated ramp and pseudo-random chain code perturbations were applied to a control rod for two amplitudes of reactivity perturbation. Neutron flux and thermocouple signals were observed and recorded together with samples of the inherent noise with the reactor unperturbed. Frequency responses were deduced from the measurements and compared with previous sinusoidal frequency response measurements and theoretical predictions. A simplified model was constructed and optimized by least squares fitting of the equivalent response from the binary cross correlator to the model's output. These optimizations showed that a very simple feedback model is appropriate to Dragon and that a good estimate of the power/reactivity coefficient and temperature coefficient of reactivity may be made. (author)

  4. The role of the IAEA in gas-cooled reactor development and application

    International Nuclear Information System (INIS)

    The IAEA's activities in gas-cooled reactor development focus on the four technical areas which are predicted to provide advanced HTGRs with a high degree of safety, but which must be proven. These are: a) the safe neutronic behaviour of the core, b) reliance on ceramic coated fuel particles to retain fission products even under extreme conditions, c) the ability to dissipate decay heat by natural heat transport mechanisms, and d) the safe behaviour of the fuel and reactor core under chemical attack (air or water ingress). The first three are subjects of Coordinated Research Programmes (CRPs) and the last was recently addressed in an information exchange meeting. CRPs are 3 to 6 years in duration, and often involve experimental activities. CRPs allow a sharing of efforts on an international basis and benefit from the experience and expertise of researchers from the participating institutes. (J.P.N.)

  5. High-temperature gas-cooled reactor safety-reliability program plan

    International Nuclear Information System (INIS)

    The purpose of this document is to present a safety plan as part of an overall program plan for the design and development of the High Temperature Gas-Cooled Reactor (HTGR). This plan is intended to establish a logical framework for identifying the technology necessary to demonstrate that the requisite degree of public risk safety can be achieved economically. This plan provides a coherent system safety approach together with goals and success criterion as part of a unifying strategy for licensing a lead reactor plant in the near term. It is intended to provide guidance to program participants involved in producing a technology base for the HTGR that is fully responsive to safety consideration in the design, evaluation, licensing, public acceptance, and economic optimization of reactor systems

  6. Helium circulator design considerations for modular high temperature gas-cooled reactor plant

    International Nuclear Information System (INIS)

    Efforts are in progress to develop a standard modular high temperature gas-cooled reactor (MHTGR) plant that is amenable to design certification and serial production. The MHTGR reference design, based on a steam cycle power conversion system, utilizes a 350 MW(t) annular reactor core with prismatic fuel elements. Flexibility in power rating is afforded by utilizing a multiplicity of the standard module. The circulator, which is an electric motor-driven helium compressor, is a key component in the primary system of the nuclear plant, since it facilitates thermal energy transfer from the reactor core to the steam generator; and, hence, to the external turbo-generator set. This paper highlights the helium circulator design considerations for the reference MHTGR plant and includes a discussion on the major features of the turbomachine concept, operational characteristics, and the technology base that exists in the US

  7. Applications for a high temperature gas cooled nuclear reactor in oil shale processing

    International Nuclear Information System (INIS)

    Results are presented of a study concerning possible applications for a high temperature gas cooled reactor as a process heat source in oil shale retorting and upgrading. Both surface and in situ technologies were evaluated with respect to the applicability and potential benefits of introducing an outside heat source. The primary focus of the study was to determine the fossil resource which might be conserved, or freed for higher uses than furnishing process heat. In addition to evaluating single technologies, a centralized upgrading plant, which would hydrotreat the product from a 400,000 bbl/day regional shale oil industry was also evaluated. The process heat required for hydrogen manufacture via steam reforming, and for whole shale oil hydrotreating would be supplied by an HTGR. Process heat would be supplied where applicable, and electrical power would be generated for the entire industry

  8. Summary of the experimental multi-purpose very high temperature gas cooled reactor design

    International Nuclear Information System (INIS)

    The report presents the design of Multi-purpose Very High Temperature Gas Cooled Reactor (the Experimental VHTR) based on the second stage of detailed design which was completed on March 1984, in the from of ''An application of reactor construction permit Appendix 8''. The Experimental VHTR is designed to satisfy with the design specification for the reactor thermal output 50 MW and reactor outlet temperature 9500C. The adequacy of the design is also checked by the safety analysis. The planning of plant system and safety is summarized such as safety design requirements and conformance with them, seismic design and plant arrangement. Concerning with the system of the Experimental VHTR the design basis, design data and components are described in the order. (author)

  9. Status of international HTGR [high-temperature gas-cooled reactor] development

    International Nuclear Information System (INIS)

    Programs for the development of high-temperature gas-cooled reactor (HTGR) technology over the past 30 years in eight countries are briefly described. These programs have included both government sector and industrial participation. The programs have produced four electricity-producing prototype/demonstration reaactors, two in the United States, and two in the Federal Republic of Germany. Key design parameters for these reactors are compared with the design parameters planned for follow-on commercial-scale HTGRs. The development of HTGR technology has been enhanced by numerous cooperative agreements over the years, involving both government-sponsored national laboratories and industrial participants. Current bilateral cooperative agreements are described. A relatively new component in the HTGR international cooperation is that of multinational industrial alliances focused on supplying commercial-scale HTGR power plants. Current industrial cooperative agreements are briefly discussed

  10. Development of Monitoring System of the RSG GAS Cooling Pump Based on Vibration Analysis

    International Nuclear Information System (INIS)

    The development of rotating machine system monitoring with vibration analysis, has been done. Research was done considering important of predictive maintenance cooling system pump using vibration analysis. Device of monitoring systems that used before require to be improved because it's only provided overall parameters and an old analogous meter systems. Research was done by arranging hardware, making software, testing and implementing this system at secondary pump of RSG GAS. In this research, hardware using NI-4551 digital signal analyze, accelerometer, and software using Labview Professional Edition 6.1 licensed. Examination and characterization indicate that the systems functioning well as vibration signal analyzer. Input frequency Response is 0.446 and dynamic range more than 90 db. Besides that, measurement application to secondary pump has also given FFT spectrum result that able to explain vibration phenomenon of a machine. For more accurate measurement applications, systems require to be developed because frequency resolution which still lower. (author)

  11. Evaluation of sprayed chromium carbide coatings for gas-cooled reactor applications

    International Nuclear Information System (INIS)

    Sprayed chromium carbide-nichrome coatings are candidates for protection of faying and sliding surfaces of critical components of gas-cooled reactors from friction and wear damage. These coatings must provide protection throughout the reactor lifetime under high temperature exposure conditions. Extensive evaluation work to characterize these coatings is underway. The work includes studies of friction and wear behavior in helium; stability of the coatings in a low oxygen potential helium environment; impure helium corrosion of coated specimens; and the effect of the coatings on mechanical properties of the substrate alloy. Much of the work reported is on the evaluation of plasma-sprayed coatings. However, a brief discussion of the behavior of coatings applied by the detonation-gun process and high-energy plasma-gun processes is also included

  12. Modelling of plate-out under gas-cooled reactor (GCR) accident conditions

    International Nuclear Information System (INIS)

    The importance of plate-out in mitigating consequences of gas-cooled reactor accidents, and its place in assessing these consequences, are discussed. The data requirements of a plate-out modelling program are discussed, and a brief description is given of parallel work programs on thermal/hydraulic reactor behaviour and fuel modelling, both of which will provide inputs to the plate-out program under development. The representation of a GCR system used in SRD studies is presented, and the equations governing iodine adsorption, desorption and transport round the circuit are derived. The status of SRD's plate-out program is described, and the type of sensitivity studies to be undertaken with the partially-developed computer program in order to identify the most useful lines for future research is discussed. (author)

  13. Review of ORNL-TSF shielding experiments for the gas-cooled Fast Breeder Reactor Program

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, L.S.; Ingersoll, D.T.; Muckenthaler, F.J.; Slater, C.O.

    1982-01-01

    During the period between 1975 and 1980 a series of experiments was performed at the ORNL Tower Shielding Facility in support of the shield design for a 300-MW(e) Gas Cooled Fast Breeder Demonstration Plant. This report reviews the experiments and calculations, which included studies of: (1) neutron streaming in the helium coolant passageways in the GCFR core; (2) the effectiveness of the shield designed to protect the reactor grid plate from radiation damage; (3) the adequacy of the radial shield in protecting the PCRV (prestressed concrete reactor vessel) from radiation damage; (4) neutron streaming between abutting sections of the radial shield; and (5) the effectiveness of the exit shield in reducing the neutron fluxes in the upper plenum region of the reactor.

  14. Utility/user requirements for the modular high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    This paper describes the approach used by Gas-Cooled Reactor Associates (GCRA) in developing Utility/User Requirements for the Modular High Temperature Gas-cooled Reactor (MHTGR). As representatives of the Utility/User industry, it is GCRA's goal that the MHTGR concept be established as an attractive nuclear option offering competitive economics and limited ownership risks. Commercially deployed MHTGR systems should then compete favorably in a mixed-fuel economy with options using fossil, other nuclear and other non-fossil sources. To achieve this goal, the design of the MHTGR plant must address the problems experienced by the U.S. industrial infrastructure during deployment of the first generation of nuclear plants. Indeed, it is GCRA's intent to utilize the characteristics of MHTGR technology for the development of a nuclear alternative that poses regulatory, financial and operational demands on the Owner/Operator that are, in aggregate, comparable to those encountered with non-nuclear options. The dominant risks faced by U.S. Utilities with current nuclear plants derive from their operational complexity and the degree of regulatory involvement in virtually all aspects of utility operations. The MHTGR approach of using ceramic fuel coatings to contain fission products provides the technical basis for simplification of the plant and stabilization of licensing requirements and thus the opportunity for reducing the risks of nuclear plant ownership. The paper describes the rationale for the selection of key requirements for public safety, plant size and performance, operations and maintenance, investment protection, economics and siting in the context of a risk management philosophy. It also describes the ongoing participation of the Utility/User in interpreting requirements, conducting program and design reviews and establishing priorities from the Owner/Operator perspective. (author). 7 refs, 1 fig

  15. Analysis of the conceptual shielding design for the upflow Gas-Cooled Fast Breeder Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Slater, C.O.; Reed, D.A.; Cramer, S.N.; Emmett, M.B.; Tomlinson, E.T.

    1981-01-01

    Conceptual Shielding Configuration III for the Gas-Cooled Fast Breeder Reactor (GCFR) was analyzed by performing global calculations of neutron and gamma-ray fluences and correcting the results as appropriate with bias factors from localized calculations. Included among the localized calculations were the radial and axial cell streaming calculations, plus extensive preliminary calculations and three final confirmation calculations of the plenum flow-through shields. The global calculations were performed on the GCFR mid-level and the lower and upper plenum regions. Calculated activities were examined with respect to the design constraint, if any, imposed on the particular activity. The spatial distributions of several activities of interest were examined with the aid of isoplots (i.e., symbols are used to describe a surface on which the activity level is everywhere the same). In general the results showed that most activities were below the respective design constraints. Only the total neutron fluence in the core barrel appeared to be marginal with the present reactor design. Since similar results were obtained for an earlier design, it has been proposed that the core barrel be cooled with inlet plenum gas to maintain it at a temperature low enough that it can withstand a higher fluence limit. Radiation levels in the prestressed concrete reactor vessel (PCRV) and liner appeared to be sufficiently below the design constraint that expected results from the Radial Shield Heterogeneity Experiment should not force any levels above the design constraint. A list was also made of a number of issues which should be examined before completion of the final shielding design.

  16. Analysis of the conceptual shielding design for the upflow Gas-Cooled Fast Breeder Reactor

    International Nuclear Information System (INIS)

    Conceptual Shielding Configuration III for the Gas-Cooled Fast Breeder Reactor (GCFR) was analyzed by performing global calculations of neutron and gamma-ray fluences and correcting the results as appropriate with bias factors from localized calculations. Included among the localized calculations were the radial and axial cell streaming calculations, plus extensive preliminary calculations and three final confirmation calculations of the plenum flow-through shields. The global calculations were performed on the GCFR mid-level and the lower and upper plenum regions. Calculated activities were examined with respect to the design constraint, if any, imposed on the particular activity. The spatial distributions of several activities of interest were examined with the aid of isoplots (i.e., symbols are used to describe a surface on which the activity level is everywhere the same). In general the results showed that most activities were below the respective design constraints. Only the total neutron fluence in the core barrel appeared to be marginal with the present reactor design. Since similar results were obtained for an earlier design, it has been proposed that the core barrel be cooled with inlet plenum gas to maintain it at a temperature low enough that it can withstand a higher fluence limit. Radiation levels in the prestressed concrete reactor vessel (PCRV) and liner appeared to be sufficiently below the design constraint that expected results from the Radial Shield Heterogeneity Experiment should not force any levels above the design constraint. A list was also made of a number of issues which should be examined before completion of the final shielding design

  17. Environmental aspects of MHTGR [Modular High-Temperature Gas-Cooled Reactor] operation

    International Nuclear Information System (INIS)

    The Modular High-Temperature Gas-Cooled Reactor (MHTGR) is an advanced reactor concept being developed under a cooperative program involving the US Government, the utilities and the nuclear industry. This plant design utilizes basic High Temperature Gas-Cooled Reactor (HTGR) features of ceramic fuel, helium coolant, and a graphite moderator. The MHTGR design approach leading to exceptional safety performance also leads to plant operation which is characterized by extremely low radiological emissions even for very low probability accidents. Coated fuel particles retain radionuclides within the fuel, thus minimizing material contamination and personnel exposure. The objective of this paper is to characterize radioactive effluents expected from the normal operation of an MHTGR. In addition, other nonradioactive effluents associated with a power generating facility are discussed. Nuclear power plants produce radioactive effluents during normal operation in gaseous, liquid and solid forms. Principal sources of radioactive waste within the MHTGR are identified. The manner in which it is planned to treat these wastes is described. Like other reactors, the MHTGR produces nonradioactive effluents associated with heat generation and chemical usage. However, due to the MHTGR's higher efficiency, water usage requirements and chemical discharges for the MHTGR are minimized relative to other types of nuclear power plants. Based upon prior operating HTGR experience and analysis, effluents are quantified in terms of radioactivity levels and/or emission volume. Results, quantified within the paper, demonstrate that effluents from the MHTGR are well below regulatory limits and that the MHTGR has a minimal impact upon the public and the environment. 14 refs., 2 figs., 4 tabs

  18. Depletion Analysis of Modular High Temperature Gas-cooled Reactor Loaded with LEU/Thorium Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Sonat Sen; Gilles Youinou

    2013-02-01

    Thorium based fuel has been considered as an option to uranium-based fuel, based on considerations of resource utilization (Thorium is more widely available when compared to Uranium). The fertile isotope of Thorium (Th-232) can be converted to fissile isotope U-233 by neutron capture during the operation of a suitable nuclear reactor such as High Temperature Gas-cooled Reactor (HTGR). However, the fertile Thorium needs a fissile supporter to start and maintain the conversion process such as U-235 or Pu-239. This report presents the results of a study that analyzed the thorium utilization in a prismatic HTGR, namely Modular High Temperature Gas-Cooled Reactor (MHTGR) that was designed by General Atomics (GA). The collected for the modeling of this design come from Chapter 4 of MHTGR Preliminary Safety Information Document that GA sent to Department of Energy (DOE) on 1995. Both full core and unit cell models were used to perform this analysis using SCALE 6.1 and Serpent 1.1.18. Because of the long mean free paths (and migration lengths) of neutrons in HTRs, using a unit cell to represent a whole core can be non-trivial. The sizes of these cells were set to match the spectral index between unit cell and full core domains. It was found that for the purposes of this study an adjusted unit cell model is adequate. Discharge isotopics and one-group cross-sections were delivered to the transmutation analysis team. This report provides documentation for these calculations

  19. Influence of plasma loading in a hybrid muon cooling channel

    Energy Technology Data Exchange (ETDEWEB)

    Freemire, B.; Stratakis, D.; Yonehara, K.

    2015-05-03

    In a hybrid 6D cooling channel, cooling is accomplished by reducing the beam momentum through ionization energy loss in wedge absorbers and replenishing the momentum loss in the longitudinal direction with gas-filled rf cavities. While the gas acts as a buffer to prevent rf breakdown, gas ionization also occurs as the beam passes through the pressurized cavity. The resulting plasma may gain substantial energy from the rf electric field which it can transfer via collisions to the gas, an effect known as plasma loading. In this paper, we investigate the influence of plasma loading on the cooling performance of a rectilinear hybrid channel. With the aid of numerical simulations we examine the sensitivity in cooling performance and plasma loading to key parameters such as the rf gradient and gas pressure.

  20. Air-cooled gas turbine cycles – Part 1: An analytical method for the preliminary assessment of blade cooling flow rates

    International Nuclear Information System (INIS)

    It is well known that, for a given compressor technology, gas turbine efficiency increases with the turbine inlet temperature (TIT): both modern aeronautical and land-based gas turbines operate at very high temperatures (1500–2000K) –and correspondingly high pressure ratios. As the TIT increases, the heat transferred from the expanding gas to the turbine blade also increases, and the need to extend the operational life make it necessary to adopt internal air cooling to reduce blade creep, oxidation and low-cycle fatigue. The cooling medium is usually air extracted from the high-pressure compressor stages, and since this extraction decreases the thermal efficiency and power output of the engine, it is important to bleed the minimum amount of coolant to attain a prescribed maximum material temperature in the blade with the maximum possible uniformity (lower thermal stresses): thence the need to properly model the cooling system for a given turbine blade geometry under realistic engine operating conditions. In the preliminary design of the first statoric and rotoric blading, it is essential for designers to rely on simple models that often neglect the small scales effects on the external flows and also by force adopt a much simplified treatment of the internal ones, and as a result attain a substantially lower degree of approximation than that offered by more complex and expensive numerical simulations. The goal in the design of a lumped model is therefore to make it both sufficiently general and accurate to analyze blade shapes and cooling channels structures that can be further refined by means of more accurate, but also more computationally intensive, models. This paper presents a simple, globally lumped thermodynamic model of blade cooling whose most important feature is its being analytical, so that the solution is devoid of numerical approximations and leads to closed-form expressions that can be easily manipulated to accommodate for different process

  1. Improvement of the decay heat removal characteristics of the generation IV gas-cooled fast reactor

    International Nuclear Information System (INIS)

    Gas cooling in nuclear power plants (NPPs) has a long history, the corresponding reactor types developed in France, the UK and the US having been thermal neutron spectrum systems using graphite as the moderator. The majority of NPPs worldwide, however, are currently light water reactors, using ordinary water as both coolant and moderator. These NPPs - of the so-called second generation - will soon need replacement, and a third generation is now being made available, offering increased safety while still based on light water technology. For the longer-term future, viz. beyond the year 2030, R and D is currently ongoing on Generation IV NPPs, aimed at achieving closure of the nuclear fuel cycle, and hence both drastically improved utilization of fuel resources and minimization of long-lived radioactive wastes. Like the SFR, the GFR is an efficient breeder, also able to work as iso-breeder using simply natural uranium as feed and producing waste which is predominantly in the form of fission products. The main drawback of the GFR is the difficulty to evacuate decay heat following a loss-of-coolant accident (LOCA) due to the low thermal inertia of the core, as well as to the low coolant density. The present doctoral research focuses on the improvement of decay heat removal (DHR) for the Generation-IV GFR. The reference GFR system design considered in the thesis is the 2006 CEA concept, with a power of 2400 MWth. The CEA 2006 DHR strategy foresees, in all accidental cases (independent of the system pressure), that the reactor is shut down. For high pressure events, dedicated DHR loops with blowers and heat exchangers are designed to operate when the power conversion system cannot be used to provide acceptable core temperatures under natural convection conditions. For de-pressurized events, the strategy relies on a dedicated small containment (called the guard containment) providing an intermediate back-up pressure. The DHR blowers, designed to work under these pressure

  2. Research on enhancement of natural circulation capability in lead–bismuth alloy cooled reactor by using gas-lift pump

    International Nuclear Information System (INIS)

    Highlights: • The gas-lift pump has been adopted to enhance the natural circulation capability. • LENAC code is developed in my study. • The calculation results by LENAC code show good agreement with experiment results. • Gas mass flow rate, bubble diameter, rising pipe length are important parameters. -- Abstract: The gas-lift pump has been adopted to enhance the natural circulation capability in the type of lead–bismuth alloy cooled reactors such as Accelerator Driven System (ADS) and Liquid–metal Fast Reactor (LMFR). The natural circulation ability and the system safety are obviously influenced by the two phase flow characteristics of liquid metal–inert gas. In this study, LENAC (LEad bismuth alloy NAtural Circulation capability) code has been developed to evaluate the natural circulation capability of lead–bismuth cooled ADS with gas-lift pump. The drift flow theory, void fraction prediction model and friction pressure drop prediction model have been incorporated into LENAC code. The calculation results by LENAC code show good agreement with experiment results of CIRCulation Experiment (CIRCE) facility. The effects of the gas mass flow rate, void fraction, gas quality, bubble diameter and the rising pipe height or the potential difference between heat exchanger and reactor core on natural circulation capability of gas-lift pump have been analyzed. The results showed that in bubbly flow pattern, for a fixed value of gas mass flow rate, the natural circulation capability increased with the decrease of the bubble diameter. In the bubbly flow, slug flow, churn flow and annular flow pattern, with the gas mass flow rate increasing, the natural circulation capability initially increased and then declined. And the flow parameters influenced the thermal hydraulic characteristics of the reactor core significantly. The present work is helpful for revealing the law of enhancing the natural circulation capability by gas-lift pump, and providing theoretical

  3. Feasibility analysis of gas turbine inlet air cooling by means of liquid nitrogen evaporation for IGCC power augmentation

    International Nuclear Information System (INIS)

    Integrated Gasification Combined Cycles (IGCC) are energy systems mainly composed of a gasifier and a combined cycle power plant. Since the gasification process usually requires oxygen as the oxidant, an Air Separation Unit (ASU) is also part of the plant. In this paper, a system for power augmentation in IGCC is evaluated. The system is based on gas turbine inlet air cooling by means of liquid nitrogen spray. In fact, nitrogen is a product of the ASU, but is not always exploited. In the proposed plant, the nitrogen is first liquefied to be used for inlet air cooling or stored for later use. This system is not characterized by the limits of water evaporative cooling systems (the lower temperature is limited by air saturation) and refrigeration cooling (the effectiveness is limited by the pressure drop in the heat exchanger). A thermodynamic model of the system is built by using a commercial code for energy conversion system simulation. A sensitivity analysis on the main parameters is presented. Finally the model is used to study the capabilities of the system by imposing the real temperature profiles of different sites for a whole year and by comparing to traditional inlet air cooling strategies. - Highlights: • Gas turbine inlet air cooling by means of liquid nitrogen spray. • Humidity condensation may form a fog which provides further power augmentation. • High peak and off peak electric energy price ratios make the system profitable

  4. Investigation of a transsonic slot cooling system for high-temperature gas turbine blades; Untersuchung einer transsonischen Schlitzkuehlung fuer Hochtemperaturgasturbinenschaufeln

    Energy Technology Data Exchange (ETDEWEB)

    Moser, S.

    2003-07-01

    The author investigated a slot cooling system with transsonic blowout of cooling air for high-temperature gas turbine blades. The method has the advantage that the cooling film is closer to the blade surface and the boundary layer at the blade wall is not interrupted even at high blowout rates. This way, the cooling film will mix less with the hot gas flow, and the cooling effect will last longer. The method is based on the subsonic Coanda effect and the supersonic Prandtl-Meyer effect, both of which result in attachment of the cooling film to a curved surface. The investigations and the optimisation were carried out using the experimental system, measuring instruments and software of the Institute of Thermal Turbo-Engines and Machine Dynamics. [German] In dieser Arbeit wird eine Schlitzkuehlung mit transsonischer Kuehlluftausblasung fuer Hochtemperaturgasturbinenschaufeln untersucht. Der Vorteil dieser Kuehlmethode ist, dass der entstehende Kuehlfilm besser an die Schaufeloberflaeche anliegt und die Grenzschicht an der Schaufelwand auch bei hohen Ausblasraten nicht durchstossen wird. Dies bewirkt ein geringeres Vermischen des Kuehlfilms mit der heissen Gasstroemung und somit ein laengeres Anhalten des Kuehlungseffektes. Man bedient sich dabei zweier in der Stroemungslehre bekannter Effekte, naemlich dem subsonischen Coanda Effekt und dem im Ueberschall auftretenden Prandtl-Meyer Effekt. Beide bewirken das Anlegen der Kuehlfilme an eine gekruemmte Oberflaeche. Mit Hilfe der am Institut fuer thermische Turbomaschinen und Maschinendynamik zur Verfuegung stehenden Versuchsanlagen, Messgeraete und Software wurde die Untersuchung bzw. Optimierung der transsonischen Schlitzkuehlung durchgefuehrt. (orig.)

  5. Exergy, Economic and Environmental Analyses of Gas Turbine Inlet Air Cooling with a Heat Pump Using a Novel System Configuration

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Majdi Yazdi

    2015-10-01

    Full Text Available Gas turbines incur a loss of output power during hot seasons due to high ambient air temperatures, and input air cooling systems are often used to partly offset this problem. Here, results are reported for an investigation of the utilization of a heat pump to cool the inlet air of a gas turbine compressor. The analyses are carried out for two climates: the city of Yazd, Iran, which has a hot, arid climate, and Tehran, Iran, which has a temperate climate. The heat pump input power is obtained from the gas turbine. The following parameters are determined, with and without the heat pump: net output power, first and second law efficiencies, quantities and costs of environmental pollutants, entropy generation and power generation. The results suggest that, by using the air-inlet cooling system, the mean output power increases during hot seasons by 11.5% and 10% for Yazd and Tehran, respectively, and that the costs of power generation (including pollution costs decrease by 11% and 10% for Yazd and Tehran, respectively. Also, the rate of generation of pollutants such as NOx and CO decrease by about 10% for Yazd and 35% for Tehran, while the average annual entropy generation rate increases by 9% for Yazd and 7% for Tehran, through air-inlet cooling. The average increase of the system first law efficiency is 2% and of the system second law efficiency is 1.5% with the inlet-air cooling system.

  6. Thermochemical Analysis of Gas-Cooled Reactor Fuels Containing Am and Pu Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Lindemer, T.B.

    2002-09-05

    Literature values and estimated data for the thermodynamics of the actinide oxides and fission products are applied to explain the chemical behavior in gas-cooled-reactor fuels. Emphasis is placed on the Am-O-C and Pu-O-C systems and the data are used to plot the oxygen chemical potential versus temperature of solid-solid and solid-gas equilibria. These results help explain observations of vaporization in Am oxides, nitrides, and carbides and provide guidance for the ceramic processing of the fuels. The thermodynamic analysis is then extended to the fission product systems and the Si-C-O system. Existing data on oxygen release (primarily as CO) as a function of burnup in the thoria-urania fuel system is reviewed and compared to values calculated from thermodynamic data. The calculations of oxygen release are then extended to the plutonia and americia fuels. Use of ZrC not only as a particle coating that may be more resistant to corrosion by Pd and other noble-metal fission products, but also as a means to getter oxygen released by fission is discussed.

  7. Corrosion of high temperature alloys in the coolant helium of a gas cooled reactor

    International Nuclear Information System (INIS)

    The corrosion of structural alloys in gas cooled reactor environment appears to be a critical issue. The coolant helium proved to contain impurities mainly H2, H2O, CO, and CH4 in the microbar range that interact with metallic materials at high temperature. Surface scale formation, bulk carburisation and/or decarburisation can occur, depending on the gas chemistry, the alloy composition and the temperature. These structural transformations can notably influence the component mechanical properties. A short review of the literature on the topic is first given. Corrosion tests with high chromium alloys and a Mo-based alloy were carried out at 750 C in a purposely-designed facility under simulated GCR helium. The first, rather short term, results showed that the Mo-based alloy was inert while the others alloys oxidised during at least 900 hours. The alloy with the higher Al and Ti contents exhibited poor oxidation resistance impeding its use as structural material without further investigations. (orig.)

  8. Techno-economic analysis of seawater desalination using high temperature gas cooled reactor

    International Nuclear Information System (INIS)

    Our world, including China (especially in big cities and foreland), is facing the increased global shortage of potable water and pollution of water. It is ideal to promote seawater desalination to satisfy the potable water demand in these areas. Among the various processes, MED, RO and VC have proven well developed and promising. Due to the inherent safety and its vapor produced with high parameters and features of small size and modular design, HTGR (High Temperature Gas-cooled Reactor) of 2x200MW is chosen as the energy source for the desalination in dual production of clean water and power. This paper discusses the techno-economic feasibility of different seawater desalting systems using 2x200MW HTGR in the areas mentioned above, that is, ST-MED (Steam Turbine Cycle), RO, MED/TVC, RO/MED and GT-MED (Gas Turbine Cycle). The exergy concept is used in calculating availability to get cost of energy in desalination, and power credit method is used in economic assessment of different systems to get reasonable evaluating, while economic-life levelized cost method is adopted for calculating electricity cost of referred HTGR plant. In addition, sensitivity analysis on ST-MED economy is also presented. (author)

  9. Genetic algorithms and artificial neural networks for loading pattern optimisation of advanced gas-cooled reactors

    International Nuclear Information System (INIS)

    A non-generational genetic algorithm (GA) has been developed for fuel management optimisation of Advanced Gas-Cooled Reactors, which are operated by British Energy and produce around 20% of the UK's electricity requirements. An evolutionary search is coded using the genetic operators; namely selection by tournament, two-point crossover, mutation and random assessment of population for multi-cycle loading pattern (LP) optimisation. A detailed description of the chromosomes in the genetic algorithm coded is presented. Artificial Neural Networks (ANNs) have been constructed and trained to accelerate the GA-based search during the optimisation process. The whole package, called GAOPT, is linked to the reactor analysis code PANTHER, which performs fresh fuel loading, burn-up and power shaping calculations for each reactor cycle by imposing station-specific safety and operational constraints. GAOPT has been verified by performing a number of tests, which are applied to the Hinkley Point B and Hartlepool reactors. The test results giving loading pattern (LP) scenarios obtained from single and multi-cycle optimisation calculations applied to realistic reactor states of the Hartlepool and Hinkley Point B reactors are discussed. The results have shown that the GA/ANN algorithms developed can help the fuel engineer to optimise loading patterns in an efficient and more profitable way than currently available for multi-cycle refuelling of AGRs. Research leading to parallel GAs applied to LP optimisation are outlined, which can be adapted to present day LWR fuel management problems

  10. Core design and safety analyses of 600 MWt, 950 °C high temperature gas-cooled reactor

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Masaaki, E-mail: nakano-m@fujielectric.co.jp [Fuji Electric Co., Ltd., 1-1, Tanabe-shinden, Kawasaki-ku, Kawasaki-city 210-9530 (Japan); Takada, Eiji; Tsuji, Nobumasa; Tokuhara, Kazumi; Ohashi, Kazutaka; Okamoto, Futoshi [Fuji Electric Co., Ltd., 1-1, Tanabe-shinden, Kawasaki-ku, Kawasaki-city 210-9530 (Japan); Tazawa, Yujiro; Tachibana, Yukio [Japan Atomic Energy Agency, Oarai, Ibaraki-pref. 311-1393 (Japan)

    2014-05-01

    The conceptual core design study of high temperature gas-cooled reactor (HTGR) is performed. The major specifications are 600 MW thermal output, 950 °C outlet coolant temperature, prismatic core type, enriched uranium fuel. The decay heat in the core can be removed with only passive measures, for example, natural convection reactor cavity cooling system (RCCS), even if any electricity is not supplied (station blackout). The transient thermal analysis of the depressurization accident in the case the primary coolant decreases to the atmosphere pressure shows that the fuels and the reactor pressure vessel temperatures are kept under their safety limit criteria. The fission product release, Ag-110m and Cs-137 from the fuels under the normal operation is small as to make maintenance of devices in the primary cooling system, such as a gas turbine, without remote maintenance. The HTGRs can achieve the advanced safety features based on their inherent passive safety characteristics.

  11. Modeling LOCA performance for the generation IV gas-cooled fast reactor design

    International Nuclear Information System (INIS)

    Full text of publication follows: Generation IV nuclear energy systems are next-generation technologies that will offer significant advances in sustainability, safety and reliability, economics, and proliferation resistance. Expected to be available for worldwide deployment by 2030, these energy systems would provide electrical power for the subsequent decades. The Gas-Cooled Fast Reactor (GFR) is a Generation IV concept that features a fast-neutron spectrum, direct Brayton cycle gas turbine, and a closed fuel cycle. Through the combination of a fast neutron spectrum and the full recycle of actinides, the GFR minimizes the production of long-lived radioactive waste and makes it possible to use existing fissile and fertile materials (including depleted uranium) more efficiently than existing thermal spectrum gas reactors. The prominent GFR design features a 'pancake' style core (H/D ∼ 1.7/2.9 m) that produces 600 MW of thermal power with an average power density of 55 MW/m3. The core is comprised of SiC-coated UPuC spheres that are collected in channels to form a prismatic, hexagonal fuel assembly or coagulated to form fuel pebbles. The 11 m3 core is enveloped by TiN reflectors and stainless steel shields in both the radial and axial directions. The initial GFR design used He gas at a pressure of 7 MPa and an outlet temperature of 850 deg. C, however the design has been expanded to consider supercritical CO2 (S-CO) gas at a pressure of 19 MPa and an outlet temperature of 550 - 650 deg. C. The higher density S-CO has advantageous characteristics during off-normal low flow and pressure conditions. One of the strengths of the Generation IV reactor concepts is their inherent safety and extensive use of passive safety systems. This paper discusses an analysis performed to study the GFR's response during a severe off-normal scenario. The loss of coolant accident was chosen because it will be one of the more severe challenges to the reactors decay heat removal system

  12. Improving Fuel Cycle Design and Safety Characteristics of a Gas Cooled Fast Reactor

    International Nuclear Information System (INIS)

    The Gas Cooled Fast Reactor (GCFR)is one of the Generation IV reactor concepts. This concept specifically targets sustainability of nuclear power generation. In nuclear reactors fertile material is converted to fissile fuel. If the neutrons inducing fission are highly energetic, the opportunity exists to convert more than one fertile nucleus per fission, thereby effectively breeding new nuclear fuel. Reactors operating on this principle are called ‘Fast Breeder Reactor’. Since natural uranium contains 99.3%of the fertile isotope 238U, breeding increases the energy harvested from the nuclear fuel. If nuclear energy is to play an important role as a source of energy in the future, fast breeder reactors are essential for breeding nuclear fuel. Fast neutrons are also more efficient to destruct heavy (Minor Actinide, MA) isotopes, such as Np, Am and Cm isotopes, which dominate the long-term radioactivity of nuclear waste. So the waste life-time can be shortened if the MA nuclei are destroyed. An important prerequisite of sustainable nuclear energy is the closed fuel cycle, where only fission products are discharged to a final repository, and all Heavy Metal (HM) are recycled. The reactor should breed just enough fissile material to allow refueling of the same reactor, adding only fertile material to the recycled material. Other key design choices are highly efficient power conversion using a direct cycle gas turbine, and better safety through the use of helium, a chemically inert coolant which cannot have phase changes in the reactor core. Because the envisaged core temperatures and operating conditions are similar to thermal-spectrum High Temperature Reactor (HTR) concepts, the research for this thesis initially focused on a design based on existing HTR fuel technology: coated particle fuel, assembled into fuel assemblies. It was found that such a fuel concept could not meet the Generation IV criteria set for GCFR: self-breeding is difficult, the temperature

  13. Flow Integrating Section for a Gas Turbine Engine in Which Turbine Blades are Cooled by Full Compressor Flow

    Energy Technology Data Exchange (ETDEWEB)

    Steward, W. Gene

    1999-11-14

    Routing of full compressor flow through hollow turbine blades achieves unusually effective blade cooling and allows a significant increase in turbine inlet gas temperature and, hence, engine efficiency. The invention, ''flow integrating section'' alleviates the turbine dissipation of kinetic energy of air jets leaving the hollow blades as they enter the compressor diffuser.

  14. An optimized process for tritium-containing waste water collection of High-Temperature Gas-cooled Reactor

    International Nuclear Information System (INIS)

    Highlights: • An optimized process for tritium-containing waste water collection of High-Temperature Gas-cooled Reactor was developed. • The optimized process and verification experiment using the HTR-10 were presented in detail. • A large quantity of high-dose tritium-containing waste water was successfully collected in commissioning experiment of the improved HTR-10. • The optimized process was proved to be reliable to avoid the large emission of radioactive waste water to the environment. - Abstract: An optimized process for tritium-containing waste water collection of High-Temperature Gas-cooled Reactor (HTGR) was developed and experimentally verified using the 10 MW High-Temperature Gas-cooled Reactor-test module (HTR-10). Compared with the previous process, an auxiliary molecular sieve bed was added in helium purification regeneration system and new operation process was proposed to collect tritium-containing waste water. In this paper, the optimized process and verification experiment were presented in detail. In commissioning experiment of the improved HTR-10, a large quantity of high-dose tritium-containing waste water was successfully collected in the water separator of helium purification regeneration system, with the specific activity being 6.1 × 109 Bq/L. The verification experiment confirms that the optimized process is effective and reliable for the demonstration plant design of High Temperature Gas-cooled Reactor-Pebble bed module (HTR-PM) to avoid the large emission of detrimentally radioactive waste water to the environment

  15. Steam generator materials constraints in UK design gas-cooled reactors

    International Nuclear Information System (INIS)

    A widely reported problem with Magnox-type reactors was the oxidation of carbon steel components in gas circuits and steam generators. The effects of temperature, pressure, gas composition and steel composition on oxidation kinetics have been determined, thus allowing the probabilities of failure of critical components to be predicted for a given set of operating conditions. This risk analysis, coupled with regular inspection of reactor and boiler internals, has allowed continued operation of all U.K. Magnox plant. The Advanced Gas Cooled Reactor (AGR) is a direct development of the Magnox design. The first four AGRs commenced operation in 1976, at Hinkley Point 'B' and at Hunterston 'B'. All known materials problems with the steam generators have been diagnosed and solved by the development of appropriate operational strategies, together with minor plant modifications. Materials constraints no longer impose any restrictions to full load performance from the steam generators throughout the predicted life of the plant. Problems discussed in detail are: 1. oxidation of the 9 Cr - 1 Mo superheater. 2. Stress corrosion of the austenitic superheater. 3. Creep of the transition joints between the 9 Cr - 1 Mo and austenitic sections. With the 9 Cr - 1 Mo oxidation maximum temperature restriction virtually removed and creep constraints properly quantified, boiler operation in now favourably placed. Stress corrosion research has allowed the risk of tube failure to be related to time, temperature, stress and chemistry. As a result, the rigorous 'no wetting' policy has been relaxed for the normally high quality AGR feedwater, and the superheat margin has been reduced to 23 deg. C. This has increased the size of the operating window and reduced the number of expensive, and potentially harmful, plant trips. (author)

  16. Eighth meeting of the International Working Group on Gas-Cooled Reactors Vienna, 30 January - 1 February 1989. Summary report. Part 2

    International Nuclear Information System (INIS)

    The Eighth Meeting of the IAEA International Working Group on Gas-Cooled Reactors was held in Vienna, Austria, from 30 January - 1 February, 1989. The Summary Report (Part II) contains the papers which review the national programmes in the field of Gas-Cooled Reactors and other presentations at the Meeting. Refs, figs and tabs

  17. Determination of an instability temperature for alloys in the cooling gas of a high temperature reactor

    International Nuclear Information System (INIS)

    High temperature alloys designed to be used for components in the primary circuit of a helium cooled high temperature nuclear reactor show massive CO production above a certain temperature, called the instability temperature T/sub i/, which increases with increasing partial pressure of CO in the cooling gas. At p/sub CO/ = 15 microbar, T/sub i/ lies between 900 and 950 degrees C for the four alloys under investigation: T/sub i/ is lowest for the iron base alloy Incoloy 800 H and increases for the nickel base alloys in the order Inconel 617, HDA 230 and Nimonic 86. Measurements of T/sub i/ made at 3 different laboratories were compared and shown to agree for p/sub CO/25 microbar, compatible with CO production by a reaction of Cr2O3 with carbides. Some measurements of T/sub i/ on HDA 230 and Nimonic 86 were performed in the course of simulated reactor disturbances. They showed that the oxide layer looses its protective properties above T/sub i/. A highlight of the examinations was the detection of eta-carbides (M6C) with unusual properties. M6C is the only type of carbide occuring in HDA 230. An eta-carbide with a lattice constant of 1088.8 pm had developed at the surface of Nimonic 86 during pre-oxidation before the disturbance simulation. Its composition is estimated at Ni3SiMo2C. Eta-carbides containing Si and especially eta-carbides with lattice constants as low as 1088.8 pm have been described only rarely until now. (author)

  18. Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors. Publishable Final Activity Report

    International Nuclear Information System (INIS)

    The PUMA project -the acronym stands for 'Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors'- was a Specific Targeted Research Project (STREP) within the EURATOM 6th Framework Program (EU FP6). The PUMA project ran from September 1, 2006, until August 31, 2009, and was executed by a consortium of 14 European partner organisations and one from the USA. This report serves 2 purposes. It is both the 'Publishable Final Activity Report' and the 'Final (Summary) Report', describing, per Work Package, the specific objectives, research activities, main conclusions, recommendations and supporting documents. PUMA's main objective was to investigate the possibilities for the utilisation and transmutation of plutonium and especially minor actinides in contemporary and future (high temperature) gas-cooled reactor designs, which are promising tools for improving the sustainability of the nuclear fuel cycle. This contributes to the reduction of Pu and MA stockpiles, and also to the development of safe and sustainable reactors for CO2-free energy generation. The PUMA project has assessed the impact of the introduction of Pu/MA-burning HTRs at three levels: fuel and fuel performance (modelling), reactor (transmutation performance and safety) and reactor/fuel cycle facility park. Earlier projects already indicated favourable characteristics of HTRs with respect to Pu burning. So, core physics of Pu/MA fuel cycles for HTRs has been investigated to study the CP fuel and reactor characteristics and to assure nuclear stability of a Pu/MA HTR core, under both normal and abnormal operating conditions. The starting point of this investigation comprised the two main contemporary HTR designs, viz. the pebble-bed type HTR, represented by the South-African PBMR, and hexagonal block type HTR, represented by the GT-MHR. The results (once again) demonstrate the flexibility of the contemporary (and near future) HTR designs and their ability to accept a variety

  19. Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors. Publishable Final Activity Report

    International Nuclear Information System (INIS)

    The PUMA project - the acronym stands for “Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors” - was a Specific Targeted Research Project (STREP) within the Euratom 6th Framework (EU FP6). The PUMA project ran from September 1, 2006, until August 31, 2009, and was executed by a consortium of 14 European partner organisations and one from the USA. This report serves 2 purposes. It is both the 'Publishable Final Activity Report' and the 'Final (Summary) Report', describing, per Work Package, the specific objectives, research activities, main conclusions, recommendations and supporting documents. PUMA's main objective was to investigate the possibilities for the utilisation and transmutation of plutonium and especially minor actinides in contemporary and future (high temperature) gas-cooled reactor designs, which are promising tools for improving the sustainability of the nuclear fuel cycle. This contributes to the reduction of Pu and MA stockpiles, and also to the development of safe and sustainable reactors for CO2-free energy generation. The PUMA project has assessed the impact of the introduction of Pu/MA-burning HTRs at three levels: fuel and fuel performance (modelling), reactor (transmutation performance and safety) and reactor/fuel cycle facility park. Earlier projects already indicated favourable characteristics of HTRs with respect to Pu burning. So, core physics of Pu/MA fuel cycles for HTRs has been investigated to study the CP fuel and reactor characteristics and to assure nuclear stability of a Pu/MA HTR core, under both normal and abnormal operating conditions. The starting point of this investigation comprised the two main contemporary HTR designs, viz. the pebble-bed type HTR, represented by the South-African PBMR, and hexagonal block type HTR, represented by the GT-MHR. The results (once again) demonstrate the flexibility of the contemporary (and near future) HTR designs and their ability to accept a variety

  20. Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors. Publishable Final Activity Report

    Energy Technology Data Exchange (ETDEWEB)

    Kuijper, J.C., E-mail: kuijper@nrg.eu [Nuclear Research and Consultancy Group (NRG), Petten (Netherlands); Somers, J.; Van Den Durpel, L.; Chauvet, V.; Cerullo, N.; Cetnar, J.; Abram, T.; Bakker, K.; Bomboni, E.; Bernnat, W.; Domanska, J.G.; Girardi, E.; De Haas, J.B.M.; Hesketh, K.; Hiernaut, J.P.; Hossain, K.; Jonnet, J.; Kim, Y.; Kloosterman, J.L.; Kopec, M.; Murgatroyd, J.; Millington, D.; Lecarpentier, D.; Lomonaco, G.; McEachern, D.; Meier, A.; Mignanelli, M.; Nabielek, H.; Oppe, J.; Petrov, B.Y.; Pohl, C.; Ruetten, H.J.; Schihab, S.; Toury, G.; Trakas, C.; Venneri, F.; Verfondern, K.; Werner, H.; Wiss, T.; Zakova, J.

    2010-11-15

    The PUMA project -the acronym stands for 'Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors'- was a Specific Targeted Research Project (STREP) within the EURATOM 6th Framework Program (EU FP6). The PUMA project ran from September 1, 2006, until August 31, 2009, and was executed by a consortium of 14 European partner organisations and one from the USA. This report serves 2 purposes. It is both the 'Publishable Final Activity Report' and the 'Final (Summary) Report', describing, per Work Package, the specific objectives, research activities, main conclusions, recommendations and supporting documents. PUMA's main objective was to investigate the possibilities for the utilisation and transmutation of plutonium and especially minor actinides in contemporary and future (high temperature) gas-cooled reactor designs, which are promising tools for improving the sustainability of the nuclear fuel cycle. This contributes to the reduction of Pu and MA stockpiles, and also to the development of safe and sustainable reactors for CO{sub 2}-free energy generation. The PUMA project has assessed the impact of the introduction of Pu/MA-burning HTRs at three levels: fuel and fuel performance (modelling), reactor (transmutation performance and safety) and reactor/fuel cycle facility park. Earlier projects already indicated favourable characteristics of HTRs with respect to Pu burning. So, core physics of Pu/MA fuel cycles for HTRs has been investigated to study the CP fuel and reactor characteristics and to assure nuclear stability of a Pu/MA HTR core, under both normal and abnormal operating conditions. The starting point of this investigation comprised the two main contemporary HTR designs, viz. the pebble-bed type HTR, represented by the South-African PBMR, and hexagonal block type HTR, represented by the GT-MHR. The results (once again) demonstrate the flexibility of the contemporary (and near future) HTR