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Sample records for serpentine cooling circuit

  1. Integrated axial and tangential serpentine cooling circuit in a turbine airfoil

    Science.gov (United States)

    Lee, Ching-Pang; Jiang, Nan; Marra, John J; Rudolph, Ronald J; Dalton, John P

    2015-05-05

    A continuous serpentine cooling circuit forming a progression of radial passages (44, 45, 46, 47A, 48A) between pressure and suction side walls (52, 54) in a MID region of a turbine airfoil (24). The circuit progresses first axially, then tangentially, ending in a last radial passage (48A) adjacent to the suction side (54) and not adjacent to the pressure side (52). The passages of the axial progression (44, 45, 46) may be adjacent to both the pressure and suction side walls of the airfoil. The next to last radial passage (47A) may be adjacent to the pressure side wall and not adjacent to the suction side wall. The last two radial passages (47A, 48A) may be longer along the pressure and suction side walls respectively than they are in a width direction, providing increased direct cooling surface area on the interiors of these hot walls.

  2. Near-wall serpentine cooled turbine airfoil

    Science.gov (United States)

    Lee, Ching-Pang

    2013-09-17

    A serpentine coolant flow path (54A-54G) formed by inner walls (50, 52) in a cavity (49) between pressure and suction side walls (22, 24) of a turbine airfoil (20A). A coolant flow (58) enters (56) an end of the airfoil, flows into a span-wise channel (54A), then flows forward (54B) over the inner surface of the pressure side wall, then turns behind the leading edge (26), and flows back along a forward part of the suction side wall, then follows a loop (54E) forward and back around an inner wall (52), then flows along an intermediate part of the suction side wall, then flows into an aft channel (54G) between the pressure and suction side walls, then exits the trailing edge (28). This provides cooling matched to the heating topography of the airfoil, minimizes differential thermal expansion, revives the coolant, and minimizes the flow volume needed.

  3. Serpentine tube heat transfer characteristic under accident condition in gas cooled reactors

    International Nuclear Information System (INIS)

    Abouhadra, D.S.; Byrne, J.E.

    2004-01-01

    In nuclear reactors of the Magnox or advanced gas Cooled type, serpentine tubing is used in some designs to generate steam in a once through arrangement. The calculation of accident conditions using two phase flow codes requires knowledge of the heat transfer behavior of the boiler steam side. A series of experiments to study the blowdown characteristics of a typical serpentine boiler section was devised in order to validate the MARTHA section of the MACE code used by nuclear Electric. The tests were carried out on the Thermal Hydraulics Experimental Research Assembly (THERA) loop at Manchester University. The Thermal Hydraulic Experimental Research Assembly was designed to operate with pressures up to 180 bar and temperatures of 450degC. The geometry and dimensions of this test section were similar to part of a gas cooled reactor boiler of the Hinkley Point design. Blowdown from a pressure of 60 bar with subcoolings of 5degC, 50degC, 100degC formed the main part of the programme. A set of tests was conducted using discharge orifices of different sizes to produce depressurization times from 30 s to 10 mins, and in a few cases, the duration of blowdown approached 1 hour. These times were defined using the criterion of blowdown end as a final pressure of 10% of the initial pressure. Pressures, wall and fluid temperatures were all measured at average time intervals of 1.1s during the excursion and an inventory of the remaining water content in the serpentine was taken when the blowdown ended. Some tests were also conducted at an initial pressure of 30 bar. The results obtained show interesting stratification effects for the relatively fast discharge, with substantial wall circumferential temperature variations. For these tests, a relatively small water inventory remained after blowdown. The discharge characteristics of the serpentine in terms of orifice size have been mapped, and tests at 30 bar show the equivalence in terms of orifice size have been mapped

  4. Integrated circuit cooled turbine blade

    Science.gov (United States)

    Lee, Ching-Pang; Jiang, Nan; Um, Jae Y.; Holloman, Harry; Koester, Steven

    2017-08-29

    A turbine rotor blade includes at least two integrated cooling circuits that are formed within the blade that include a leading edge circuit having a first cavity and a second cavity and a trailing edge circuit that includes at least a third cavity located aft of the second cavity. The trailing edge circuit flows aft with at least two substantially 180-degree turns at the tip end and the root end of the blade providing at least a penultimate cavity and a last cavity. The last cavity is located along a trailing edge of the blade. A tip axial cooling channel connects to the first cavity of the leading edge circuit and the penultimate cavity of the trailing edge circuit. At least one crossover hole connects the penultimate cavity to the last cavity substantially near the tip end of the blade.

  5. DEVICES FOR COOLING ELECTRONIC CIRCUIT BOARDS

    OpenAIRE

    T. A. Ismailov; D. V. Evdulov; A. G. Mustafaev; D. K. Ramazanova

    2014-01-01

    In the work described structural variants of devices for cooling electronic circuit boards, made on the basis of thermoelectric batteries and consumable working substances, implementing uneven process of removing heat from heat-generating components. A comparison of temperature fields of electronic circuit simulator with his uniform and non-uniform cooling

  6. DEVICES FOR COOLING ELECTRONIC CIRCUIT BOARDS

    Directory of Open Access Journals (Sweden)

    T. A. Ismailov

    2014-01-01

    Full Text Available In the work described structural variants of devices for cooling electronic circuit boards, made on the basis of thermoelectric batteries and consumable working substances, implementing uneven process of removing heat from heat-generating components. A comparison of temperature fields of electronic circuit simulator with his uniform and non-uniform cooling

  7. Thermo-hydraulic characteristics of serpentine tubing in the boilers of gas cooled reactors under condition of rapid and slow depressurization

    International Nuclear Information System (INIS)

    Abouhadra, D.S.; Byrne, J.E.

    2003-01-01

    In nuclear reactors of the magnox or advanced gas cooled type, serpentine tubing is used in some designs to generate steam in a once through arrangement. The calculation of accidents using two phase flow codes requires knowledge of the heat transfer behaviour of the boiler steam side. A series of experiments to study the blowdown characteristics of a typical serpentine boiler section was devised in order to validate the MARTHA section of the MACE code used by nuclear electric . The tests were carried out on the thermal hydraulics experimental research assembly (THERA) loop at manchester university. Depressurization from an initial pressure of 60 bar, with fluid subcooling of 5 k, 50 k, and 100 k was controlled by discharging the test section contents through suitably chosen orifices to produce blowdown to 10% of the initial pressure over a time scale of 30 s to 3600 s. pressures and temperatures in the serpentine were measured at average time intervals of approximately 1 s

  8. Test Structures For Bumpy Integrated Circuits

    Science.gov (United States)

    Buehler, Martin G.; Sayah, Hoshyar R.

    1989-01-01

    Cross-bridge resistors added to comb and serpentine patterns. Improved combination of test structures built into integrated circuit used to evaluate design rules, fabrication processes, and quality of interconnections. Consist of meshing serpentines and combs, and cross bridge. Structures used to make electrical measurements revealing defects in design or fabrication. Combination of test structures includes three comb arrays, two serpentine arrays, and cross bridge. Made of aluminum or polycrystalline silicon, depending on material in integrated-circuit layers evaluated. Aluminum combs and serpentine arrays deposited over steps made by polycrystalline silicon and diffusion layers, while polycrystalline silicon versions of these structures used to cross over steps made by thick oxide layer.

  9. Integrated microchannel cooling in a three dimensional integrated circuit: A thermal management

    Directory of Open Access Journals (Sweden)

    Wang Kang-Jia

    2016-01-01

    Full Text Available Microchannel cooling is a promising technology for solving the three-dimensional integrated circuit thermal problems. However, the relationship between the microchannel cooling parameters and thermal behavior of the three dimensional integrated circuit is complex and difficult to understand. In this paper, we perform a detailed evaluation of the influence of the microchannel structure and the parameters of the cooling liquid on steady-state temperature profiles. The results presented in this paper are expected to aid in the development of thermal design guidelines for three dimensional integrated circuit with microchannel cooling.

  10. Numerical quantification of habitability in serpentinizing systems

    Science.gov (United States)

    Som, S.; Alperin, M. J.; Hoehler, T. M.

    2012-12-01

    The likely presence of liquid water in contact with olivine-bearing rocks on Mars, the detection of serpentine minerals and of methane emissions possibly consistent with serpentinization, and the observation of serpentine-associated methane-cycling communities on Earth have all led to excitement over the potential of such systems to host life on Mars, even into the present day. However, the habitability of subsurface serpentinizing systems on Mars does not necessarily follow from these qualitative observations. In particular, while the production of H2 during serpentinization could provide methanogens with a needed substrate, the alkaline conditions and corresponding potential for carbon limitation that arise in concert are negatives against which H2 supply must be balanced. We considered this balance via a coupled geochemical-bioenergetic model that weighs the outputs of serpentinization against the metabolic requirements of methanogenesis, in an energetic frame of reference. Serpentinization is modeled using the "Geochemist's Workbench" (GWB) whereby ultramafic harzburgite rocks are reacted with oxygen and sulfate depleted seawater. Reaction kinetics are not explicitly considered, but comparable effects of partial reaction are approximated by assuming post-reaction dilution of equilibrated fluids. The output of GWB serves as the input to the bioenergetic model, which calculates methanogenic energy yields based on spherically-symmetrical diffusion of substrates to a cell followed by reaction at the diffusion-limited rate. Membrane selectivity for substrate transport is explicitly considered. Results will be report updates for two scenarios: (i) High temperature serpentinization followed by cooling and transport of equilibrated fluid to a lower temperature regime accessible to biology; (ii) Serpentinization within the biologically-tolerated range of temperatures. Such coupled models demonstrate that environmental variability with respect to both water-rock reaction

  11. Steady state thermal-hydraulic analyses of the MITICA cooling circuits

    Energy Technology Data Exchange (ETDEWEB)

    Zaupa, M., E-mail: matteo.zaupa@igi.cnr.it [Università degli Studi di Padova, Via 8 Febbraio 2, Padova 35122 (Italy); Consorzio RFX, Corso Stati Uniti 4, Padova 35127 (Italy); Sartori, E.; Dalla Palma, M.; Fellin, F.; Marcuzzi, D.; Pavei, M.; Rizzolo, A. [Consorzio RFX, Corso Stati Uniti 4, Padova 35127 (Italy)

    2016-02-15

    Megavolt ITER Injector Concept Advancement is the full scale prototype of the heating and current drive neutral beam injectors for ITER, to be built at Consorzio RFX (Padova). The engineering design of its components is challenging: the total heat loads they will be subjected to (expected between 2 and 19 MW), the high heat fluxes (up to 20 MW/m{sup 2}), and the beam pulse duration up to 1 h, set demanding requirements for reliable active cooling circuits. In support of the design, the thermo-hydraulic behavior of each cooling circuit under steady state condition has been investigated by using one-dimensional models. The final results, obtained considering a number of optimizations for the cooling circuits, show that all the requirements in terms of flow rate, temperature, and pressure drop are properly fulfilled.

  12. Comparison of biocides for disinfection treatment of open recirculating cooling circuits

    International Nuclear Information System (INIS)

    Soreau, Sylvie; Prisset, Frederic; Carvajal, Nathalie

    2012-09-01

    Open recirculating cooling circuits of nuclear power plants are likely to face pathogenic proliferations like Legionella and amoebae (Naegleria fowleri). To reduce such risks, biocide treatments are usually implemented. However, the selection of a treatment is never easy due to the large size of the cooling circuits. Indeed, the range of treatment options is limited due to potential health or environmental impacts of chemicals in case of chemical treatments or because of the technical difficulties to implement treatment units appropriate to the size of the cooling circuits in case of physical treatments. In the aim of finding the best compromise between efficacy, nature and quantity of chemical releases and industrial feasibility, several biocide treatments were compared at lab and pilot scale using semi-industrial pilot plants simulating recirculating cooling circuit of a nuclear power plant. These pilots were fed with river water or pre-treated water (lime softening or clari-flocculation). They were equipped with materials and surfaces representative of those found on a full-scale plant. These pilots operated at summer temperatures favoring microbial growth. Three industrial biocides were compared: chlorine, monochloramine and chlorine dioxide. The results indicate that the transit in the cooling system strongly affects the consumption of biocides and therefore their efficacy, the quantity of biocide needed and chemical releases so that the ranking of treatments defined on the basis of laboratory tests can be strongly modified. The results show different areas of consumption along the process line depending on biocides and highlight the significant role of the cooling tower. The behavior of biocides in the different compartments of the circuit (cooling tower, condenser, basins) is described and the consequences on pathogenic micro-organisms removal in bio-films and on chemical releases are considered as function of the studied biocide. Moreover, the influence of

  13. Variable cooling circuit for thermoelectric generator and engine and method of control

    Science.gov (United States)

    Prior, Gregory P

    2012-10-30

    An apparatus is provided that includes an engine, an exhaust system, and a thermoelectric generator (TEG) operatively connected to the exhaust system and configured to allow exhaust gas flow therethrough. A first radiator is operatively connected to the engine. An openable and closable engine valve is configured to open to permit coolant to circulate through the engine and the first radiator when coolant temperature is greater than a predetermined minimum coolant temperature. A first and a second valve are controllable to route cooling fluid from the TEG to the engine through coolant passages under a first set of operating conditions to establish a first cooling circuit, and from the TEG to a second radiator through at least some other coolant passages under a second set of operating conditions to establish a second cooling circuit. A method of controlling a cooling circuit is also provided.

  14. Cooling transfer fluids: advantages, drawbacks, refrigerant circuit architecture; Les fluides frigoporteurs: avantages, inconvenients, apercu sur l`architecture des circuits frigoporteurs

    Energy Technology Data Exchange (ETDEWEB)

    Duminil, M. [Association Francaise du Froid (AFF), 75 - Paris (France)

    1997-12-31

    The advantages and inconvenients of indirect cooling systems are summarized: simplification of the cooling distribution from a single refrigerating unit, a potential for a larger range of refrigerants, cooling circuit size diminution, but energy consumption increase, lower evaporation temperature, etc. The various types and characteristics of single- and two-phase refrigerant and heat transfer fluids are described, and more especially two-phase liquid-vapour and liquid-solid fluids. Based on the example of a two-temperature-level refrigerating system in a supermarket, the general architecture of the cold distribution circuit and the architecture of the refrigerant circuit itself, are presented with their different types, involving direct or indirect, and centralized or semi-centralized systems

  15. ELECTRONIC CIRCUIT BOARDS NON-UNIFORM COOLING SYSTEM MODEL

    Directory of Open Access Journals (Sweden)

    D. V. Yevdulov

    2016-01-01

    Full Text Available Abstract. The paper considers a mathematical model of non-uniform cooling of electronic circuit boards. The block diagram of the system implementing this approach, the method of calculation of the electronic board temperature field, as well as the principle of its thermal performance optimizing are presented. In the considered scheme the main heat elimination from electronic board is produced by the radiator system, and additional cooling of the most temperature-sensitive components is produced by thermoelectric batteries. Are given the two-dimensional temperature fields of the electronic board during its uniform and non-uniform cooling, is carried out their comparison. As follows from the calculations results, when using a uniform overall cooling of electronic unit there is a waste of energy for the cooling 0f electronic board parts which temperature is within acceptable temperature range without the cooling system. This approach leads to the increase in the cooling capacity of used thermoelectric batteries in comparison with the desired values. This largely reduces the efficiency of heat elimination system. The use for electronic boards cooling of non-uniform local heat elimination removes this disadvantage. The obtained dependences show that in this case, the energy required to create a given temperature is smaller than when using a common uniform cooling. In this approach the temperature field of the electronic board is more uniform and the cooling is more efficient. 

  16. Design Methodology and Experimental Verification of Serpentine/Folded Waveguide TWTs

    Science.gov (United States)

    2016-03-17

    FW), oscillation, serpentine, stopband, traveling -wave tube (TWT), vacuum electronics. I. INTRODUCTION DEVELOPMENT of high-power broadband vacuum elec...tron devices (VEDs) beyond Ka-band using conventional coupled-cavity and helix traveling -wave tube (TWT) RF cir- cuit fabrication techniques is...bottom plot. III. G-BAND CIRCUIT DESIGN AND EXPERIMENTAL VALIDATION The primary motivation for the G-band amplifier was to develop a high-power broadband

  17. The physico-chemical problems involved in condenser cooling, circuit sealing and stain

    International Nuclear Information System (INIS)

    Ropars, Jean.

    1975-01-01

    Today thermal production of electric energy requiers the use of steam turbines and then needs cold sources (condensers), the latter being obtained by means of a water circulation. Considerable amounts of water are involved. For instance, as for a 900MW power plant of the PWR type, a 12 deg C heating needs 40m 3 /s of cooling water. The needs in water introduce a limitation in the possible site selection for power plant settling (seaside or river with an important steady flow). The important amounts of heat involved create environmental problems. Means for limiting the heat amount released consist in using atmospheric cooling systems. A further constraint relating to scaling is added to the usual corrosion and stain problems when operating the devices. Changes in the carbon dioxide equilibrium and concentration due to the passage through the air cooling systems causes such scaling formation. The evolution of the physico-chemical parameters of the cooling water is described with the risks resulting for the circuits. Means to be developed for preventing scaling, stain and corrosion are presented. The solutions kept by E.D.F. for the exploitation of cooling circuits are indicated. The procedure developed must avoid any chemical pollution of water wastes [fr

  18. Sulfur in serpentinized oceanic peridotites: Serpentinization processes and microbial sulfate reduction

    Science.gov (United States)

    Alt, J.C.; Shanks, Wayne C.

    1998-01-01

    The mineralogy, contents, and isotopic compositions of sulfur in oceanic serpentinites reflect variations in temperatures and fluid fluxes. Serpentinization of serpentinization of Iberian Margin peridotites occurred at low temperatures (???20??-200??C) and high water/rock ratios. Complete serpentinization and consumption of ferrous iron allowed evolution to higher fO2. Microbial reduction of seawater sulfate resulted in addition of low-??34S sulfide (-15 to -43???) and formation of higher-sulfur assemblages that include valleriite and pyrite. The high SO4/total S ratio of Hess Deep serpentinites (0.89) results in an increase of total sulfur and high ??34S of total sulfur (mean ??? 8???). In contrast, Iberian Margin serpentinites gained large amounts of 34S-poor sulfide (mean total S = 3800 ppm), and the high sulfide/total S ratio (0.61) results in a net decrease in ??34S of total sulfur (mean ??? -5???). Thus serpentinization is a net sink for seawater sulfur, but the amount fixed and its isotopic composition vary significantly. Serpentinization may result in uptake of 0.4-14 ?? 1012 g S yr-1 from the oceans, comparable to isotopic exchange in mafic rocks of seafloor hydrothermal systems and approaching global fluxes of riverine sulfate input and sedimentary sulfide output.

  19. Shielded serpentine traveling wave tube deflection structure

    Science.gov (United States)

    Hudson, C.L.; Spector, J.

    1994-12-27

    A shielded serpentine slow wave deflection structure is disclosed having a serpentine signal conductor within a channel groove. The channel groove is formed by a serpentine channel in a trough plate and a ground plane. The serpentine signal conductor is supported at its ends by coaxial feed through connectors. A beam interaction trough intersects the channel groove to form a plurality of beam interaction regions wherein an electron beam may be deflected relative to the serpentine signal conductor. 4 figures.

  20. Parallel LC circuit model for multi-band absorption and preliminary design of radiative cooling.

    Science.gov (United States)

    Feng, Rui; Qiu, Jun; Liu, Linhua; Ding, Weiqiang; Chen, Lixue

    2014-12-15

    We perform a comprehensive analysis of multi-band absorption by exciting magnetic polaritons in the infrared region. According to the independent properties of the magnetic polaritons, we propose a parallel inductance and capacitance(PLC) circuit model to explain and predict the multi-band resonant absorption peaks, which is fully validated by using the multi-sized structure with identical dielectric spacing layer and the multilayer structure with the same strip width. More importantly, we present the application of the PLC circuit model to preliminarily design a radiative cooling structure realized by merging several close peaks together. This omnidirectional and polarization insensitive structure is a good candidate for radiative cooling application.

  1. Microfracturing and fluid pathways in serpentinizing abyssal peridotites along the Southwest Indian Ridge (62°-65°E)

    Science.gov (United States)

    Rouméjon, S.; Cannat, M.; Agrinier, P.; Godard, M.; Andreani, M.

    2013-12-01

    At slow spreading ridges, axial detachment faults exhume mantle-derived peridotites. Their interaction with seawater-derived hydrothermal fluids causes serpentinization down to 2-3km from the fault, as inferred from seismic velocity models. It is commonly proposed that fractures allow penetration of seawater into the fault's footwall. At the microscopic scale, the hydration front progresses from a microfracture network toward the center of olivine relicts and forms the serpentine mesh texture. The origin of these microfractures is a matter of debate: tectonic, anisotropic thermal contraction of olivine during peridotite cooling or hierarchical fracturing of the olivine due to volume increase during serpentinization. In this presentation we use petrology and geochemistry to analyze the links between microfractures and serpentinization in a set of highly serpentinized peridotites dredged along the melt-starved easternmost part of the Southwest Indian Ridge (Smoothseafloor cruise). Our observations suggest that thermal contraction of olivine combines with tectonic stresses to fracture fresh peridotite in the brittle lithosphere. These ~60μm-spaced microfractures constitute the initial sample-scale permeability network for fluid penetration, onset of serpentinization and formation of additional hierarchical fractures. As serpentinization proceeds, the volume increase closes the least-developed planes and preferential pathways for fluid circulation become more distant, forming the 200-500μm-wide polygonal pattern typical of the serpentine mesh texture. In about 20% of the recovered samples the mesh serpentine is partially recrystallized forming rims next to later microfractures and serpentine veins. The spacing of these rims, and the limited proportion of affected samples suggest that the scales of the efficient permeability network in the serpentinites at this stage had increased to decimetric and greater scales. We use geochemical constrains to derive temperature

  2. Mantle wedge serpentinization effects on slab dips

    Directory of Open Access Journals (Sweden)

    Eh Tan

    2017-01-01

    Full Text Available The mechanical coupling between a subducting slab and the overlying mantle wedge is an important factor in controlling the subduction dip angle and the flow in mantel wedge. This paper investigates the role of the amount of mantle serpentinization on the subduction zone evolution. With numerical thermos-mechanical models with elasto-visco-plastic rheology, we vary the thickness and depth extent of mantle serpentinization in the mantle wedge to control the degree of coupling between the slab and mantle wedge. A thin serpentinized mantle layer is required for stable subduction. For models with stable subduction, we find that the slab dip is affected by the down-dip extent and the mantle serpentinization thickness. A critical down-dip extent exists in mantle serpentinization, determined by the thickness of the overriding lithosphere. If the down-dip extent does not exceed the critical depth, the slab is partially coupled to the overriding lithosphere and has a constant dip angle regardless of the mantle serpentinization thickness. However, if the down-dip extent exceeds the critical depth, the slab and the base of the overriding lithosphere would be separated and decoupled by a thick layer of serpentinized peridotite. This allows further slab bending and results in steeper slab dip. Increasing mantle serpentinization thickness will also result in larger slab dip. We also find that with weak mantle wedge, there is no material flowing from the asthenosphere into the serpentinized mantle wedge. All of these results indicate that serpentinization is an important ingredient when studying the subduction dynamics in the mantle wedge.

  3. Two-phase flow in the cooling circuit of a cryogenic rocket engine

    Science.gov (United States)

    Preclik, D.

    1992-07-01

    Transient two-phase flow was investigated for the hydrogen cooling circuit of the HM7 rocket engine. The nuclear reactor code ATHLET/THESEUS was adapted to cryogenics and applied to both principal and prototype experiments for validation and simulation purposes. The cooling circuit two-phase flow simulation focused on the hydrogen prechilling and pump transient phase prior to ignition. Both a single- and a multichannel model were designed and employed for a valve leakage flow, a nominal prechilling flow, and a prechilling with a subsequent pump-transient flow. The latter case was performed in order to evaluate the difference between a nominal and a delayed turbo-pump start-up. It was found that an extension of the nominal prechilling sequence in the order of 1 second is sufficient to finally provide for liquid injection conditions of hydrogen which, as commonly known, is undesirable for smooth ignition and engine starting transients.

  4. Change in Frictional Behavior during Olivine Serpentinization

    Science.gov (United States)

    Xing, T.; Zhu, W.; French, M. E.; Belzer, B.

    2017-12-01

    Hydration of mantle peridotites (serpentinization) is pervasive at plate boundaries. It is widely accepted that serpentinization is intrinsically linked to hydromechanical processes within the sub-seafloor, where the interplay between cracking, fluid supply and chemical reactions is responsible for a spectrum of fault slip, from earthquake swarms at the transform faults, to slow slip events at the subduction zone. Previous studies demonstrate that serpentine minerals can either promote slip or creep depend on many factors that include sliding velocity, temperature, pressure, interstitial fluids, etc. One missing link from the experimental investigation of serpentine to observations of tectonic faults is the extent of alteration necessary for changing the frictional behaviors. We quantify changes in frictional behavior due to serpentinization by conducting experiments after in-situ serpentinization of olivine gouge. In the sample configuration a layer of powder is sandwiched between porous sandstone blocks with 35° saw-cut surface. The starting material of fine-grained (63 120 µm) olivine powder is reacted with deionized water for 72 hours at 150°C before loading starts. Under the conventional triaxial configuration, the sample is stressed until sliding occurs within the gouge. A series of velocity-steps is then performed to measure the response of friction coefficient to variations of sliding velocity from which the rate-and-state parameters are deduced. For comparison, we measured the frictional behavior of unaltered olivine and pure serpentine gouges.Our results confirm that serpentinization causes reduced frictional strength and velocity weakening. In unaltered olivine gouge, an increase in frictional resistance with increasing sliding velocity is observed, whereas the serpentinized olivine and serpentine gouges favor velocity weakening behaviors at the same conditions. Furthermore, we observed that high pore pressures cause velocity weakening in olivine but

  5. Replacement of the Pumps for Fuel Channel Cooling Circuit of the Maria Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Krzysztoszek, G.; Mieleszczenko, W.; Moldysz, A. [National Centre for Nuclear Research, Otwock–Świerk (Poland)

    2014-08-15

    The high flux Maria research reactor is operated by the National Centre for Nuclear Research in Świerk. It is a pool type reactor with pressurized fuel channels located in the beryllium matrix. According to the Global Threat Reduction Initiative programme our goal is to convert the Maria reactor from HEU to LEU fuel. Hydraulic losses in the new LEU fuel produced by CERCA are about 30% higher than the existing HEU fuel of type MR-6. For the MR-6 fuel were installed four two speed pumps. These pumps performed the function of the main circulations pumps during reactor operation with residual pumping power provided by emergency pumps. In the new system four main pumps will be used for circulating coolant while the reactor is operation with three auxiliary pumps for decay heat removal after reactor shutdown, meaning that the conversion of Maria research reactor will be possible after increasing flow in the primary cooling circuit of the fuel channels. The technical design of replacement of the pumps in the primary fuel channel cooling circuit was finished in April 2011 and accepted by the Safety Committee. After delivery of the new pumps we are planning to upgrade the primary fuel channel cooling circuit during October–November 2012. (author)

  6. Ecology of Legionella within water cooling circuits of nuclear power plants along the French Loire River

    International Nuclear Information System (INIS)

    Jakubek, Delphine

    2012-01-01

    The cooling circuits of nuclear power plants, by their mode of operating, can select thermophilic microorganisms including the pathogenic organism Legionella pneumophila. To control the development of this genus, a disinfection treatment of water cooling systems with monochloramine can be used. To participate in the management of health and environmental risks associated with the physico-chemical and microbiological modification of water collected from the river, EDF is committed to a process of increasing knowledge about the ecology of Legionella in cooling circuits and its links with its environment (physical, chemical and microbiological) supporting or not their proliferation. Thus, diversity and dynamics of culturable Legionella pneumophila were determined in the four nuclear power plants along the Loire for a year and their links with physico-chemical and microbiological parameters were studied. This study revealed a high diversity of Legionella pneumophila subpopulations and their dynamic seems to be related to the evolution of a small number of subpopulations. Legionella subpopulations seem to maintain strain-specific relationships with biotic parameters and present different sensitivities to physico-chemical variations. The design of cooling circuits could impact the Legionella community. The use of monochloramine severely disrupts the ecosystem but does not select biocide tolerant subpopulations. (author)

  7. Corrosion induced clogging and plugging in water-cooled generator cooling circuit

    International Nuclear Information System (INIS)

    Park, B.G.; Hwang, I.S.; Rhee, I.H.; Kim, K.T.; Chung, H.S.

    2002-01-01

    Water-cooled electrical generators have been experienced corrosion-related problems that are restriction of flow through water strainers caused by collection of excessive amounts of copper corrosion products (''clogging''), and restriction of flow through the copper strands in the stator bars caused by growth or deposition of corrosion products on the walls of the hollow strands (''plugging''). These phenomena result in unscheduled shutdowns that would be a major concern because of the associated loss in generating capacity. Water-cooled generators are operated in one of two modes. They are cooled either with aerated water (dissolved oxygen >2 ppm) or with deaerated water (dissolved oxygen <50 ppb). Both modes maintain corrosion rates at satisfactorily low levels as long as the correct oxygen concentrations are maintained. However, it is generally believed that very much higher copper corrosion rates result at the intermediate oxygen concentrations of 100-1000 ppb. Clogging and plugging are thought to be associated with these intermediate concentrations, and many operators have suggested that the period of change from high-to-low or from low-to-high oxygen concentration is particularly damaging. In order to understand the detailed mechanism(s) of the copper oxide formation, release and deposition and to identify susceptible conditions in the domain of operating variables, a large-scale experiments are conducted using six hollow strands of full length connected with physico-chemically scaled generator cooling water circuit. To ensure a close simulation of thermal-hydraulic conditions in a generator stator, strands of the loop will be ohmically heated using AC power supply. Experiments is conducted to cover oxygen excursions in both high dissolved oxygen and low dissolved oxygen conditions that correspond to two representative operating condition at fields. A thermal upset condition is also simulated to examine the impact of thermal stress. During experiments

  8. Polyphase serpentinization history of Mariana forearc mantle: observations on the microfabric of ultramafic clasts from ODP Leg 195, Site 1200

    Science.gov (United States)

    Kahl, Wolf-Achim; Jöns, Niels; Bach, Wolfgang; Klein, Frieder

    2013-04-01

    In the forearc of the Mariana subduction zone system, a number of seamounts form from extrusion of blueschist and serpentine mud. Ocean Drilling Program Leg 195 drilled the South Chamorro seamount, where ultramafic clasts occur within the mud matrix. These clasts show a complex serpentinization history, which bears the potential for tracking the alteration history during uplift and cooling of mantle wedge rocks to the seafloor. Moreover, the microfabrics of the highly serpentinized harzburgite and dunite clasts exhibit evidence for multiple fracturing events in the forearc mantle. These, in turn, lead to fluid influx and varied styles of serpentinization of harzburgite and dunite. The serpentinized ultramafic clasts exhibit a variety of microfabrics that range from virtually undeformed to strongly deformed samples. Pervasively serpentinized harzburgites feature either an equigranular fabric of serpentinized olivine and orthopyroxene crystals, or different vein generations related to multiple stages of serpentinization. Several types of fluid pathways in harzburgites are present: (i) veins containing brucite and iron oxides, developed linearly without marked conformance with the rock fabric. In places, these veins developed mm-cm wide halos with finger-shaped serpentinization fronts. Veins of type (i) are either developed as syntaxial veins from a single crack-seal event with large magnetite crystals growing from one wall to the other (as confirmed with high-resolution X-ray microtomography), or formed by multiple fluid events. (ii) serpentine veins that encompass regions of marginally serpentinized, microgranular olivine and large orthopyroxene crystals. (iii) extensional serpentine veins (known as "Frankenstein" type). In the clasts studied, their occurrence is restricted to the halo region of type (i) veins. (iv) as a late-stage feature, extensional veins documenting multiple crack-seal events can be present in the serpentinites (either in undeformed regions with

  9. Large-Scale Deformation and Uplift Associated with Serpentinization

    Science.gov (United States)

    Germanovich, L. N.; Lowell, R. P.; Smith, J. E.

    2014-12-01

    Geologic and geophysical data suggest that partially serpentinized peridotites and serpentinites are a significant part of the oceanic lithosphere. All serpentinization reactions are exothermic and result in volume expansion as high as 40%. Volume expansion beneath the seafloor will lead to surface uplift and elevated stresses in the neighborhood of the region undergoing serpentinization. The serpentinization-induced stresses are likely to result in faulting or tensile fracturing that promote the serpentinization process by creating new permeability and allowing fluid access to fresh peridotite. To explore these issues, we developed a first-order model of crustal deformation by considering an inclusion undergoing transformation strain in an elastic half-space. Using solutions for inclusions of different shapes, orientations, and depths, we calculate the surface uplift and mechanical stresses generated by the serpentinization processes. We discuss the topographic features at the TAG hydrothermal field (Mid-Atlantic Ridge, 26°N), uplift of the Miyazaki Plain (Southwestern Japan), and tectonic history of the Atlantic Massif (inside corner high of the Mid-Atlantic Ridge, 30°N, and the Atlantis Transform Fault). Our analysis suggests that an anomalous salient of 3 km in diameter and 100 m high at TAG may have resulted from approximately 20% transformational strain in a region beneath the footwall of the TAG detachment fault. This serpentinization process tends to promote slip along some overlying normal faults, which may then enhance fluid pathways to the deeper crust to continue the serpentinization process. The serpentinization also favors slip and seismicity along the antithetic faults identified below the TAG detachment fault. Our solution for the Miyazaki Plain above the Kyushu-Palau subduction zone explains the observed uplift of 120 m, but the transformational strain needs only be 3%. Transformational strains associated with serpentinization in this region may

  10. Retrofitting the instrumentation and control system of primary cooling circuit from TRIGA INR 14 MW reactor

    International Nuclear Information System (INIS)

    Preda, M.; Ciocanescu, M.; Ana, E. M.; Cristea, D.

    2008-01-01

    Activities of retrofitting the instrumentation and control system from TRIGA INR primary cooling circuit consists in replacement of actual system for: - parameter measurement; - safety; - reactor external scramming; - protection, command and supply for electrical elements of the system. This retrofitting project is designed to ensure the necessary features of reactor external safety and for technological parameter measurement. The new safety system of main cooling circuit is completely separated from its operating system and is arranged in a panel assembly in reactor control room. The operating system has the following features: - data acquisition; - parameter value and state of command elements displaying; - command elements on hierarchical levels; - operator information through visual and acoustic alarm. (authors)

  11. Thermal activation of serpentine for adsorption of cadmium

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Chun-Yan [College of Land and Environment, Shenyang Agricultural University, Shenyang (China); College of Chemistry, Chemical Engineering and Food Safety, Bohai University, Jinzhou (China); Liang, Cheng-Hua, E-mail: liang110161@163.com [College of Land and Environment, Shenyang Agricultural University, Shenyang (China); Yin, Yan [Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang (China); Du, Li-Yu [College of Land and Environment, Shenyang Agricultural University, Shenyang (China)

    2017-05-05

    Highlights: • Thermal activated serpentine was prepared by changing heated temperature. • Thermal activated serpentine exhibited excellent adsorption behavior for cadmium. • The adsorption mechanisms could be explained as formation of CdCO{sub 3} and Cd(OH){sub 2}. • The adsorption obeyed Langmuir model and pseudo second order kinetics model. - Abstract: Thermal activated serpentine with high adsorption capacity for heavy metals was prepared. The batch experiment studies were conducted to evaluate the adsorption performance of Cd{sup 2+} in aqueous solution using thermal activated serpentine as adsorbent. These samples before and after adsorption were characterized by XRD, FT-IR, SEM, XPS, and N{sub 2} adsorption-desorption at low temperature. It was found that serpentine with layered structure transformed to forsterite with amorphous structure after thermal treatment at over 700 °C, while the surface area of the samples was increased with activated temperature and the serpentine activated at 700 °C (S-700) presented the largest surface area. The pH of solution after adsorption was increased in different degrees due to hydrolysis of MgO in serpentine, resulting in enhancing adsorption of Cd{sup 2+}. The S-700 exhibited the maximum equilibrium adsorption capacity (15.21 mg/g), which was 2 times more than pristine serpentine. Langmuir isotherm was proved to describe the equilibrium adsorption data better than Freundlich isotherm and pseudo second order kinetics model could fit the adsorption kinetics processes well. Based on the results of characterization with XPS and XRD, the adsorption mechanisms could be explained as primarily formation of CdCO{sub 3} and Cd(OH){sub 2} precipitation on the surface of serpentine.

  12. Thermal activation of serpentine for adsorption of cadmium

    International Nuclear Information System (INIS)

    Cao, Chun-Yan; Liang, Cheng-Hua; Yin, Yan; Du, Li-Yu

    2017-01-01

    Highlights: • Thermal activated serpentine was prepared by changing heated temperature. • Thermal activated serpentine exhibited excellent adsorption behavior for cadmium. • The adsorption mechanisms could be explained as formation of CdCO_3 and Cd(OH)_2. • The adsorption obeyed Langmuir model and pseudo second order kinetics model. - Abstract: Thermal activated serpentine with high adsorption capacity for heavy metals was prepared. The batch experiment studies were conducted to evaluate the adsorption performance of Cd"2"+ in aqueous solution using thermal activated serpentine as adsorbent. These samples before and after adsorption were characterized by XRD, FT-IR, SEM, XPS, and N_2 adsorption-desorption at low temperature. It was found that serpentine with layered structure transformed to forsterite with amorphous structure after thermal treatment at over 700 °C, while the surface area of the samples was increased with activated temperature and the serpentine activated at 700 °C (S-700) presented the largest surface area. The pH of solution after adsorption was increased in different degrees due to hydrolysis of MgO in serpentine, resulting in enhancing adsorption of Cd"2"+. The S-700 exhibited the maximum equilibrium adsorption capacity (15.21 mg/g), which was 2 times more than pristine serpentine. Langmuir isotherm was proved to describe the equilibrium adsorption data better than Freundlich isotherm and pseudo second order kinetics model could fit the adsorption kinetics processes well. Based on the results of characterization with XPS and XRD, the adsorption mechanisms could be explained as primarily formation of CdCO_3 and Cd(OH)_2 precipitation on the surface of serpentine.

  13. Biological Potential in Serpentinizing Systems

    Science.gov (United States)

    Hoehler, Tori M.

    2016-01-01

    Generation of the microbial substrate hydrogen during serpentinization, the aqueous alteration of ultramafic rocks, has focused interest on the potential of serpentinizing systems to support biological communities or even the origin of life. However the process also generates considerable alkalinity, a challenge to life, and both pH and hydrogen concentrations vary widely across natural systems as a result of different host rock and fluid composition and differing physical and hydrogeologic conditions. Biological potential is expected to vary in concert. We examined the impact of such variability on the bioenergetics of an example metabolism, methanogenesis, using a cell-scale reactive transport model to compare rates of metabolic energy generation as a function of physicochemical environment. Potential rates vary over more than 5 orders of magnitude, including bioenergetically non-viable conditions, across the range of naturally occurring conditions. In parallel, we assayed rates of hydrogen metabolism in wells associated with the actively serpentinizing Coast Range Ophiolite, which includes conditions more alkaline and considerably less reducing than is typical of serpentinizing systems. Hydrogen metabolism is observed at pH approaching 12 but, consistent with the model predictions, biological methanogenesis is not observed.

  14. Ultramafic clasts from the South Chamorro serpentine mud volcano reveal a polyphase serpentinization history of the Mariana forearc mantle

    Science.gov (United States)

    Kahl, Wolf-Achim; Jöns, Niels; Bach, Wolfgang; Klein, Frieder; Alt, Jeffrey C.

    2015-06-01

    Serpentine seamounts located on the outer half of the pervasively fractured Mariana forearc provide an excellent window into the forearc devolatilization processes, which can strongly influence the cycling of volatiles and trace elements in subduction zones. Serpentinized ultramafic clasts recovered from an active mud volcano in the Mariana forearc reveal microstructures, mineral assemblages and compositions that are indicative of a complex polyphase alteration history. Petrologic phase relations and oxygen isotopes suggest that ultramafic clasts were serpentinized at temperatures below 200 °C. Several successive serpentinization events represented by different vein generations with distinct trace element contents can be recognized. Measured in situ Rb/Cs ratios are fairly uniform ranging between 1 and 10, which is consistent with Cs mobilization from sediments at lower temperatures and lends further credence to the low-temperature conditions proposed in models of the thermal structure in forearc settings. Late veins show lower fluid mobile element (FME) concentrations than early veins, suggesting a decreasing influence of fluid discharge from the subducting slab on the composition of the serpentinizing fluids. The continuous microfabric and mineral chemical evolution observed in the ultramafic clasts may have implications as to the origin and nature of the serpentinizing fluids. We hypothesize that opal and smectite dehydration produce quartz-saturated fluids with high FME contents and Rb/Cs between 1 and 4 that cause the early pervasive serpentinization. The partially serpentinized material may then be eroded from the basal plane of the suprasubduction mantle wedge. Serpentinization continued but the interacting fluids did not carry a pronounced sedimentary signature, either because FMEs were no longer released from the slab, or due to an en route loss of FMEs. Late chrysotile veins that document the increased access of fluids in a now fluid-dominated regime are

  15. Emergency reactor cooling circuit

    International Nuclear Information System (INIS)

    Araki, Hidefumi; Matsumoto, Tomoyuki; Kataoka, Yoshiyuki.

    1994-01-01

    Cooling water in a gravitationally dropping water reservoir is injected into a reactor pressure vessel passing through a pipeline upon occurrence of emergency. The pipeline is inclined downwardly having one end thereof being in communication with the pressure vessel. During normal operation, the cooling water in the upper portion of the inclined pipeline is heated by convection heat transfer from the communication portion with the pressure vessel. On the other hand, cooling water present at a position lower than the communication portion forms cooling water lumps. Accordingly, temperature stratification layers are formed in the inclined pipeline. Therefore, temperature rise of water in a vertical pipeline connected to the inclined pipeline is small. With such a constitution, the amount of heat lost from the pressure vessel by way of the water injection pipeline is reduced. Further, there is no worry that cooling water to be injected upon occurrence of emergency is boiled under reduced pressure in the injection pipeline to delay the depressurization of the pressure vessel. (I.N.)

  16. Optimization of the cooling circuit and thermo-mechanical analysis for the extraction grid of ELISE

    International Nuclear Information System (INIS)

    Nocentini, R.; Gutser, R.; Heinemann, B.; Froeschle, M.; Riedl, R.

    2011-01-01

    The NNBI test facility ELISE ('Extraction from a Large Ion Source Experiment'), presently under construction at IPP, will have an extraction area with the same width and half the height of the ITER source, acceleration up to 60 kV, for 10 s, every 180 s, and plasma generation up to 1 h. Electrons are co-extracted from the ion source. Suppression magnets in the extraction grid deflect the electrons onto the extraction grid surface. For 30 mA/cm 2 extracted electron current density and 10 kV extraction voltage, localized power density is in the order of 39 MW/m 2 near the grid apertures and a total heat load of 150 kW is deposited onto each extraction grid segment. Heat removal is provided by a water circuit inside the grid. For ELISE, a new cooling circuit has been developed to provide a more reliable operation. The optimization of the cooling circuit and the thermo-mechanical analysis of the extraction grid of ELISE, considering maximum grid temperature, mechanical stresses and grid deformation, has been performed using the codes KOBRA3, TrajAn, the ANSYS finite element package and the fluid dynamics code CFX.

  17. Geochemical evidence of present-day serpentinization.

    Science.gov (United States)

    Barnes, I; Lamarche, V C; Himmelberg, G

    1967-05-12

    Ultrabasic (pH > 11) water issues from some fresh ultramafic bodies. The properties of the ultrabasic solutions are believed to be due to current reactions yielding serpentine from primary olivines and pyroxenes. The low concentrations of divalent airon. divalent magnesium, and dissolved silica from the serpentinization require an increase in rock volume.

  18. Orthogonally interdigitated shielded serpentine travelling wave cathode ray tube deflection structure

    Science.gov (United States)

    Hagen, E.C.; Hudson, C.L.

    1995-07-25

    A new deflection structure which deflects a beam of charged particles, such as an electron beam, includes a serpentine set for transmitting a deflection field, and a shielding frame for housing the serpentine set. The serpentine set includes a vertical serpentine deflection element and a horizontal serpentine deflection element. These deflection elements are identical, and are interdigitatedly and orthogonally disposed relative to each other, for forming a central transmission passage, through which the electron beam passes, and is deflected by the deflection field, so as to minimize drift space signal distortion. The shielding frame includes a plurality of ground blocks, and forms an internal serpentine trough within these ground blocks, for housing the serpentine set. The deflection structure further includes a plurality of feedthrough connectors which are inserted through the shielding frame, and which are electrically connected to the serpentine set. 10 figs.

  19. Nuclear microprobe analysis of serpentine from the mid-Atlantic ridge

    International Nuclear Information System (INIS)

    Orberger, Beate; Metrich, Nicole; Mosbah, Michelle; Mevel, Catherine; Fouquet, Yves

    1999-01-01

    At mid-ocean ridges, ultramafic rocks are serpentinized by interaction with seawater-derived fluids. Elements, dissolved in large quantities in seawater, e.g., Na, K, Cl, Br, Ca and Sr, can be, in small amounts, incorporated as traces into the crystal structure of the various serpentine minerals (Mg 3 Si 2 O 5 (OH) 4 ). These trace elements can be used to track the composition of the reacting fluids and to constrain physico-chemical conditions. This paper represents the first application of particle-induced X- and γ-ray emission (PIXE/PIGE) analysis to serpentine using the nuclear microprobe at the Laboratoire Pierre Suee (CEA-CNRS). Three types of serpentine, belonging to two different serpentinization generations, have been analysed in samples collected from the Mid-Atlantic Ridge (14 deg. 45'N/45 deg. W) that exposes serpentinized peridotites on which the Logachev black smoker is placed. The trace elements Cl, F, S, Cu, Zn, Ca, K, Ni, Cr and Mn were detected from several tens to several thousands of ppm. Bromine, As and Sr are close to the detection limit of about 5 ppm. The trace element concentrations and interelement relationships in serpentines vary (a) with the serpentine type and (b) with the geographic location to the black smoker. Chlorine and in part S originated from seawater, whereas Cu, Zn, Ca, K, Ni, Cr and Fe and the major amount of S were mobilized from the unaltered host rock and partitioned between the serpentine and the aqueous solution

  20. The production of iron oxide during peridotite serpentinization: Influence of pyroxene

    Directory of Open Access Journals (Sweden)

    Ruifang Huang

    2017-11-01

    Full Text Available Serpentinization produces molecular hydrogen (H2 that can support communities of microorganisms in hydrothermal fields; H2 results from the oxidation of ferrous iron in olivine and pyroxene into ferric iron, and consequently iron oxide (magnetite or hematite forms. However, the mechanisms that control H2 and iron oxide formation are poorly constrained. In this study, we performed serpentinization experiments at 311 °C and 3.0 kbar on olivine (with <5% pyroxene, orthopyroxene, and peridotite. The results show that serpentine and iron oxide formed when olivine and orthopyroxene individually reacted with a saline starting solution. Olivine-derived serpentine had a significantly lower FeO content (6.57 ± 1.30 wt.% than primary olivine (9.86 wt.%, whereas orthopyroxene-derived serpentine had a comparable FeO content (6.26 ± 0.58 wt.% to that of primary orthopyroxene (6.24 wt.%. In experiments on peridotite, olivine was replaced by serpentine and iron oxide. However, pyroxene transformed solely to serpentine. After 20 days, olivine-derived serpentine had a FeO content of 8.18 ± 1.56 wt.%, which was significantly higher than that of serpentine produced in olivine-only experiments. By contrast, serpentine after orthopyroxene had a slightly higher FeO content (6.53 ± 1.01 wt.% than primary orthopyroxene. Clinopyroxene-derived serpentine contained a significantly higher FeO content than its parent mineral. After 120 days, the FeO content of olivine-derived serpentine decreased significantly (5.71 ± 0.35 wt.%, whereas the FeO content of orthopyroxene-derived serpentine increased (6.85 ± 0.63 wt.% over the same period. This suggests that iron oxide preferentially formed after olivine serpentinization. Pyroxene in peridotite gained some Fe from olivine during the serpentinization process, which may have led to a decrease in iron oxide production. The correlation between FeO content and SiO2 or Al2O3 content in olivine- and

  1. Helium-cooled nuclear reactor

    International Nuclear Information System (INIS)

    Longton, P.B.; Cowen, H.C.

    1975-01-01

    In helium cooled HTR's there is a by-pass circuit for cleaning purposes in addition to the main cooling circuit. This is to remove such impurities as hydrogen, methane, carbon monoxide and water from the coolant. In this system, part of the coolant successively flows first through an oxidation bed of copper oxide and an absorption bed of silica gel, then through activated charcoal or a molecular sieve. The hydrogen and carbon monoxide impurities are absorbed and the dry gas is returned to the main cooling circuit. To lower the hydrogen/water ratio without increasing the hydrogen fraction in the main cooling circuit, some of the hydrogen fraction converted into water is added to the cooling circuit. This is done, inter alia, by bypassing the water produced in the oxidation bed before it enters the absorption bed. The rest of the by-pass circuit, however, also includes an absorption bed with a molecular sieve. This absorbs the oxidized carbon monoxide fraction. In this way, such side effects as the formation of additional methane, carburization of the materials of the by-pass circuit or loss of graphite are avoided. (DG/RF) [de

  2. Spray cooling

    International Nuclear Information System (INIS)

    Rollin, Philippe.

    1975-01-01

    Spray cooling - using water spraying in air - is surveyed as a possible system for make-up (peak clipping in open circuit) or major cooling (in closed circuit) of the cooling water of the condensers in thermal power plants. Indications are given on the experiments made in France and the systems recently developed in USA, questions relating to performance, cost and environmental effects of spray devices are then dealt with [fr

  3. Water cooling in nuclear reactors by using panels of integrated circuits

    International Nuclear Information System (INIS)

    Dominique, P.; Letissier, R.

    1977-01-01

    In view of the drawbacks of wet cooling towers, EDF is searching for another approach to the problem. A self-cleaning device is now envisaged, that consists in some exchanger plates, 30 to 40m height (max. 60m) capable of being hiden in the lanscape behind high trees. The plates would be rather smooth and the air circulated by natural convection. The prototype is composed of 960 aluminium panels of integrated circuits mounted on three modules made of tubular elements working as supporting and collecting means together [fr

  4. Effect of water activity on rates of serpentinization of olivine.

    Science.gov (United States)

    Lamadrid, Hector M; Rimstidt, J Donald; Schwarzenbach, Esther M; Klein, Frieder; Ulrich, Sarah; Dolocan, Andrei; Bodnar, Robert J

    2017-07-14

    The hydrothermal alteration of mantle rocks (referred to as serpentinization) occurs in submarine environments extending from mid-ocean ridges to subduction zones. Serpentinization affects the physical and chemical properties of oceanic lithosphere, represents one of the major mechanisms driving mass exchange between the mantle and the Earth's surface, and is central to current origin of life hypotheses as well as the search for microbial life on the icy moons of Jupiter and Saturn. In spite of increasing interest in the serpentinization process by researchers in diverse fields, the rates of serpentinization and the controlling factors are poorly understood. Here we use a novel in situ experimental method involving olivine micro-reactors and show that the rate of serpentinization is strongly controlled by the salinity (water activity) of the reacting fluid and demonstrate that the rate of serpentinization of olivine slows down as salinity increases and H 2 O activity decreases.

  5. Effect of water activity on rates of serpentinization of olivine

    Science.gov (United States)

    Lamadrid, Hector M.; Rimstidt, J. Donald; Schwarzenbach, Esther M.; Klein, Frieder; Ulrich, Sarah; Dolocan, Andrei; Bodnar, Robert J.

    2017-07-01

    The hydrothermal alteration of mantle rocks (referred to as serpentinization) occurs in submarine environments extending from mid-ocean ridges to subduction zones. Serpentinization affects the physical and chemical properties of oceanic lithosphere, represents one of the major mechanisms driving mass exchange between the mantle and the Earth's surface, and is central to current origin of life hypotheses as well as the search for microbial life on the icy moons of Jupiter and Saturn. In spite of increasing interest in the serpentinization process by researchers in diverse fields, the rates of serpentinization and the controlling factors are poorly understood. Here we use a novel in situ experimental method involving olivine micro-reactors and show that the rate of serpentinization is strongly controlled by the salinity (water activity) of the reacting fluid and demonstrate that the rate of serpentinization of olivine slows down as salinity increases and H2O activity decreases.

  6. Nuclear microprobe analysis of serpentine from the mid-Atlantic ridge

    Energy Technology Data Exchange (ETDEWEB)

    Orberger, Beate E-mail: orberger@geol.u-psud.fr; Metrich, Nicole; Mosbah, Michelle E-mail: mosbah@drecam.cea.fr; Mevel, Catherine; Fouquet, Yves

    1999-09-02

    At mid-ocean ridges, ultramafic rocks are serpentinized by interaction with seawater-derived fluids. Elements, dissolved in large quantities in seawater, e.g., Na, K, Cl, Br, Ca and Sr, can be, in small amounts, incorporated as traces into the crystal structure of the various serpentine minerals (Mg{sub 3}Si{sub 2}O{sub 5}(OH){sub 4}). These trace elements can be used to track the composition of the reacting fluids and to constrain physico-chemical conditions. This paper represents the first application of particle-induced X- and {gamma}-ray emission (PIXE/PIGE) analysis to serpentine using the nuclear microprobe at the Laboratoire Pierre Suee (CEA-CNRS). Three types of serpentine, belonging to two different serpentinization generations, have been analysed in samples collected from the Mid-Atlantic Ridge (14 deg. 45'N/45 deg. W) that exposes serpentinized peridotites on which the Logachev black smoker is placed. The trace elements Cl, F, S, Cu, Zn, Ca, K, Ni, Cr and Mn were detected from several tens to several thousands of ppm. Bromine, As and Sr are close to the detection limit of about 5 ppm. The trace element concentrations and interelement relationships in serpentines vary (a) with the serpentine type and (b) with the geographic location to the black smoker. Chlorine and in part S originated from seawater, whereas Cu, Zn, Ca, K, Ni, Cr and Fe and the major amount of S were mobilized from the unaltered host rock and partitioned between the serpentine and the aqueous solution.

  7. SERPENTINE COIL TOPOLOGY FOR BNL DIRECT WIND SUPERCONDUCTING MAGNETS

    International Nuclear Information System (INIS)

    PARKER, B.; ESCALLIER, J.

    2005-01-01

    Serpentine winding, a recent innovation developed at BNL for direct winding superconducting magnets, allows winding a coil layer of arbitrary multipolarity in one continuous winding process and greatly simplifies magnet design and production compared to the planar patterns used before. Serpentine windings were used for the BEPC-II Upgrade and JPARC magnets and are proposed to make compact final focus magnets for the EC. Serpentine patterns exhibit a direct connection between 2D body harmonics and harmonics derived from the integral fields. Straightforward 2D optimization yields good integral field quality with uniformly spaced (natural) coil ends. This and other surprising features of Serpentine windings are addressed in this paper

  8. Rare and Endangered Geophyte Plant Species in Serpentine of Kosovo

    Directory of Open Access Journals (Sweden)

    Naim Berisha

    2014-12-01

    Full Text Available Our study documents information on rarity, geographical distribution, taxonomy and conservation status of 11 geophyte species in serpentine soils of Kosovo, already included in the Red Book of Vascular Flora of Kosovo. Kosovo’s serpentine vegetation represents a diversity that yet has not been sufficiently explored. Large serpentine complexes are found in the northern Kosovo but also southern part of the country is rich in serpentines, therefore in endemics. Serpentine rocks and soils are characterized by low level of principal plant nutrients (N, P, K, Ca and exceptionally high levels of Mg and Fe. Serpentines play particular importance for flora of the country due to their richness in endemic plant species. The following 11 plant species have been studied: Aristolochia merxmuelleri, Colchicum hungaricum, Crocus flavus, Crocus kosaninii, Epimedium alpinum, Gentiana punctata, Gladiolus illyricus, Lilium albanicum, Paeonia peregrina, Tulipa gesneriana and Tulipa kosovarica. Five out of eleven studied geophytes fall within Critically Endangered IUCN based threat category and five out of eleven are local endemics. Aristolochia merxmuelleri and Tulipa kosovarica are steno-endemic plant species that are found exclusively in serpentine soils. Information in our database should prove to be valuable to efforts in ecology, floristics, biosystematics, conservation and land management.

  9. Giant serpentine intracranial aneurysm: a case report

    International Nuclear Information System (INIS)

    Park, Jae Seong; Lee, Myeong Sub; Kim, Myung Soon; Kim, Dong Jin; Park, Joong Wha; Whang, Kum

    2001-01-01

    The authors present a case of giant serpentine aneurysm (a partially thrombosed aneurysm containing tortuous vascular channels with a separate entrance and outflow pathway). Giant serpentine aneurysms form a subgroup of giant intracranial aneurysms, distinct from saccular and fusiform varieties, and in this case, too, the clinical presentation and radiographic features of CT, MR imaging and angiography were distinct

  10. The effect of polyether on the separation of pentlandite and serpentine

    Directory of Open Access Journals (Sweden)

    Xiaowen Zhou

    2015-10-01

    Full Text Available The effect of polyether on the separation of pentlandite from serpentine has been studied. In addition to flotation and sedimentation tests, electrophoresis and adsorption tests have been conducted. The flotation and sedimentation results show that serpentine impairs flotation performance of pentlandite, by adhering to the pentlandite particles. Addition of the polyether could promote the dispersion of the mixed sample of pentlandite and serpentine in alkaline conditions and significantly reduce adverse effects of serpentine on the pentlandite flotation. The electrophoresis and adsorption tests show that polyether can selectively adsorb onto pentlandite surface through hydrophobic reaction and remove serpentine slime particles from pentlandite surfaces by steric hindrance effect.

  11. Laser cooling and optical detection of excitations in a LC electrical circuit

    DEFF Research Database (Denmark)

    Taylor, J. M.; Sørensen, Anders Søndberg; Marcus, Charles Masamed

    2011-01-01

    We explore a method for laser cooling and optical detection of excitations in a room temperature LC electrical circuit. Our approach uses a nanomechanical oscillator as a transducer between optical and electronic excitations. An experimentally feasible system with the oscillator capacitively...... coupled to the LC and at the same time interacting with light via an optomechanical force is shown to provide strong electromechanical coupling. Conditions for improved sensitivity and quantum limited readout of electrical signals with such an “optical loud speaker” are outlined....

  12. Emergency cooling system for a gas-cooled nuclear reactor

    International Nuclear Information System (INIS)

    Cook, R.K.; Burylo, P.S.

    1975-01-01

    The site of the gas-cooled reactor with direct-circuit gas turbine is preferably the sea coast. An emergency cooling system with safety valve and emergency feed-water addition is designed which affects at least a part of the reactor core coolant after leaving the core. The emergency cooling system includes a water emergency cooling circuit with heat exchanger for the core coolant. The safety valve releases water or steam from the emergency coolant circuit when a certain temperature is exceeded; this is, however, replaced by the emergency feed-water. If the gas turbine exhibits a high and low pressure turbine stage, which are flowed through by coolant one behind another, a part of the coolant can be removed in front of each part turbine by two valves and be added to the haet exchanger. (RW/LH) [de

  13. Analytical and numerical study on cooling flow field designs performance of PEM fuel cell with variable heat flux

    Science.gov (United States)

    Afshari, Ebrahim; Ziaei-Rad, Masoud; Jahantigh, Nabi

    2016-06-01

    In PEM fuel cells, during electrochemical generation of electricity more than half of the chemical energy of hydrogen is converted to heat. This heat of reactions, if not exhausted properly, would impair the performance and durability of the cell. In general, large scale PEM fuel cells are cooled by liquid water that circulates through coolant flow channels formed in bipolar plates or in dedicated cooling plates. In this paper, a numerical method has been presented to study cooling and temperature distribution of a polymer membrane fuel cell stack. The heat flux on the cooling plate is variable. A three-dimensional model of fluid flow and heat transfer in cooling plates with 15 cm × 15 cm square area is considered and the performances of four different coolant flow field designs, parallel field and serpentine fields are compared in terms of maximum surface temperature, temperature uniformity and pressure drop characteristics. By comparing the results in two cases, the constant and variable heat flux, it is observed that applying constant heat flux instead of variable heat flux which is actually occurring in the fuel cells is not an accurate assumption. The numerical results indicated that the straight flow field model has temperature uniformity index and almost the same temperature difference with the serpentine models, while its pressure drop is less than all of the serpentine models. Another important advantage of this model is the much easier design and building than the spiral models.

  14. Mathematical model of an integrated circuit cooling through cylindrical rods

    Directory of Open Access Journals (Sweden)

    Beltrán-Prieto Luis Antonio

    2017-01-01

    Full Text Available One of the main challenges in integrated circuits development is to propose alternatives to handle the extreme heat generated by high frequency of electrons moving in a reduced space that cause overheating and reduce the lifespan of the device. The use of cooling fins offers an alternative to enhance the heat transfer using combined a conduction-convection systems. Mathematical model of such process is important for parametric design and also to gain information about temperature distribution along the surface of the transistor. In this paper, we aim to obtain the equations for heat transfer along the chip and the fin by performing energy balance and heat transfer by conduction from the chip to the rod, followed by dissipation to the surrounding by convection. Newton's law of cooling and Fourier law were used to obtain the equations that describe the profile temperature in the rod and the surface of the chip. Ordinary differential equations were obtained and the respective analytical solutions were derived after consideration of boundary conditions. The temperature along the rod decreased considerably from the initial temperature (in contatct with the chip surface. This indicates the benefit of using a cilindrical rod to distribute the heat generated in the chip.

  15. Study of thermal, radiation and environmental effects on serpentine

    International Nuclear Information System (INIS)

    Raje, Naina; Kalekar, Bhupesh B.; Dubey, K.A.

    2016-01-01

    Physical and chemical properties of a material, such as particle size surface area, magnetic properties, water content, radiation and thermal stability, viscosity, porosity, are responsible for their specific applications. Serpentine is a greenish, layer structured phyllosilicate, known as magnesium hydroxy silicate. The availability of large number of hydroxyl group makes serpentine a potential candidate for nuclear shielding material. Hence present studies have been carried out to understand the stability of serpentine with the variation in thermal, radiation and environmental parameters. Serpentine samples were received from Reactor Projects Division, BARC. An accurately weighed sample was subjected to simultaneous TG - DTA - EGA measurements in air as well as inert atmosphere at the heating rate of 10 °C/min. The sample was heated from room temperature to 1000 °C with a gas flow rate of 100 mL/min in Netzsch thermal analyzer (Model STA409 PC LUXX) connected to Bruker FTIR system (Model - Tensor27) via a 1m long capillary. The sample was subjected to gamma radiation in the range of 10 - 100 kGy using 60 Co gamma source in gamma chamber and was subjected to TG measurements to understand the effect of radiation on the thermal stability of serpentine and the results are being discussed here

  16. Evidence of adaptive tolerance to nickel in isolates of Cenococcum geophilum from serpentine soils.

    Science.gov (United States)

    Gonçalves, Susana C; Martins-Loução, M Amélia; Freitas, Helena

    2009-04-01

    Selection for metal-tolerant ecotypes of ectomycorrhizal (ECM) fungi has been reported in instances of metal contamination of soils as a result of human activities. However, no study has yet provided evidence that natural metalliferous soils, such as serpentine soils, can drive the evolution of metal tolerance in ECM fungi. We examined in vitro Ni tolerance in isolates of Cenococcum geophilum from serpentine and non-serpentine soils to assess whether isolates from serpentine soils exhibited patterns consistent with adaptation to elevated levels of Ni, a typical feature of serpentine. A second objective was to investigate the relationship between Ni tolerance and specific growth rates (micro) among isolates to increase our understanding of possible tolerance/growth trade-offs. Isolates from both soil types were screened for Ni tolerance by measuring biomass production in liquid media with increasing Ni concentrations, so that the effective concentration of Ni inhibiting fungal growth by 50% (EC(50)) could be determined. Isolates of C. geophilum from serpentine soils exhibited significantly higher tolerance to Ni than non-serpentine isolates. The mean Ni EC(50) value for serpentine isolates (23.4 microg ml(-1)) was approximately seven times higher than the estimated value for non-serpentine isolates (3.38 microg ml(-1)). Although there was still a considerable variation in Ni sensitivity among the isolates, none of the serpentine isolates had EC(50) values for Ni within the range found for non-serpentine isolates. We found a negative correlation between EC(50) and micro values among isolates (r = -0.555). This trend, albeit only marginally significant (P = 0.06), indicates a potential trade-off between tolerance and growth, in agreement with selection against Ni tolerance in "normal" habitats. Overall, these results suggest that Ni tolerance arose among serpentine isolates of C. geophilum as an adaptive response to Ni exposure in serpentine soils.

  17. Serpentine concrete in the experiment and application of Tianwan nuclear power station

    International Nuclear Information System (INIS)

    Wang Kaihua; Qian Fuhua

    2015-01-01

    The choice of the configuration of the serpentine concrete aggregate is very important. From selection of serpentine concrete raw materials, and test and adjustment of mixture ratio, the paper elaborates in detail the special physical properties and engineering application, and provides detailed information for the promotion and application of the serpentine concrete. (authors)

  18. Serpentinization: Getting water into a low permeability peridotite

    Science.gov (United States)

    Ulven, Ole Ivar

    2017-04-01

    Fluid consuming rock transformation processes occur in a variety of settings in the Earth's crust. One such process is serpentinization, which involves hydration of ultramafic rock to form serpentine. With peridotite being one of the dominating rocks in the oceanic crust, this process changes physical and chemical properties of the crust at a large scale, increases the amount of water that enters subduction zones, and might even affect plate tectonics te{jamtveit}. A significant number of papers have studied serpentinization in different settings, from reaction fronts progressing over hundreds of meters te{rudge} to the interface scale fracture initiation te{pluemper}. However, the process represents a complicated multi-physics problem which couples external stress, mechanical deformation, volume change, fracture formation, fluid transport, the chemical reaction, heat production and heat flow. Even though it has been argued that fracture formation caused by the volume expansion allows fluid infiltration into the peridotite te{rudge}, it remains unclear how sufficient water can enter the initially low permeability peridotite to pervasively serpentinize the rock at kilometre scale. In this work, we study serpentinization numerically utilizing a thermo-hydro-mechanical model extended with a fluid consuming chemical reaction that increases the rock volume, reduces its density and strength, changes the permeability of the rock, and potentially induces fracture formation. The two-way coupled hydromechanical model is based on a discrete element model (DEM) previously used to study a volume expanding process te{ulven_1,ulven_2} combined with a fluid transport model based on poroelasticity te{ulven_sun}, which is here extended to include fluid unsaturated conditions. Finally, a new model for reactive heat production and heat flow is introduced, to make this probably the first ever fully coupled chemo-thermo-hydromechanical model describing serpentinization. With this model

  19. Interrelation between rifting, faulting, sedimentation, and mantle serpentinization during continental margin formation

    Science.gov (United States)

    Rupke, L.; Schmid, D. W.; Perez-Gussinye, M.; Hartz, E. H.

    2013-12-01

    We explore the conditions under which mantle serpentinization may take place during continental rifting with 2D thermotectonostratigraphic basin models. The basic concept follows the idea that the entire extending continental crust has to be brittle for crustal scale faulting and mantle serpentinization to occur. The new model tracks the rheological evolution of the continental crust and allows for kinetically controlled mantle serpentinization processes. The isostatic and latent heat effects of the reaction are fully coupled to the structural and thermal solutions. A systematic parameter study shows that a critical stretching factor exists for which complete crustal embrittlement and serpentinization occurs. Sedimentation shifts this critical stretching factor to higher values as both deeper burial and the low thermal conductivity of sediments lead to higher crustal temperatures. Serpentinization reactions are therefore only likely in settings with low sedimentation rates and high stretching factors. In addition, we find that the rate of sediment supply has first order controls on the rheology of the lower crust, which may control the overall margin geometry. We further test these concepts in ideas in a case study for the Norwegian margin. In particular, we evaluate whether the inner lower crustal bodies (LCB) imaged beneath the More and Voring margin could be serpentinized mantle. For this purpose we reconstruct multiple 2D transects through a 3D data set. This reconstruction of the Norwegian margin shows that serpentinization reactions are indeed possible and likely during the Jurassic rift phase. Predicted present-day thicknesses and locations of partially serpentinized mantle rocks fit well to information on LCBs from seismic and gravity data. We conclude that some of the inner LCBs beneath the Norwegian margin may, in fact, be partially serpentinized mantle.

  20. Present day serpentinization in New Caledonia, Oman and Yugoslavia

    Science.gov (United States)

    Barnes, I.; O'Neil, J.R.; Trescases, J.J.

    1978-01-01

    Geochemical evidence for modern low-temperature serpentinization has been found in three new localities. Apparently the low-temperature reactions are a common mode of formation of the lizardite-chrysotile and brucite assemblage. Possibly the 18O content of serpentine formed at low temperatures is in part inherited from the pyroxene and olivine. ?? 1978.

  1. Experimental Study of Serpentinization Reactions

    Science.gov (United States)

    Cohen, B. A.; Brearley, A. J.; Ganguly, J.; Liermann, H.-P.; Keil, K.

    2004-01-01

    Current carbonaceous chondrite parent-body thermal models [1-3] produce scenarios that are inconsistent with constraints on aqueous alteration conditions based on meteorite mineralogical evidence, such as phase stability relationships within the meteorite matrix minerals [4] and isotope equilibration arguments [5, 6]. This discrepancy arises principally because of the thermal runaway effect produced by silicate hydration reactions (here loosely called serpentinization, as the principal products are serpentine minerals), which are so exothermic as to produce more than enough heat to melt more ice and provide a self-sustaining chain reaction. One possible way to dissipate the heat of reaction is to use a very small parent body [e.g., 2] or possibly a rubble pile model. Another possibility is to release this heat more slowly, which depends on the alteration reaction path and kinetics.

  2. Abiotic methane formation during experimental serpentinization of olivine.

    Science.gov (United States)

    McCollom, Thomas M

    2016-12-06

    Fluids circulating through actively serpentinizing systems are often highly enriched in methane (CH 4 ). In many cases, the CH 4 in these fluids is thought to derive from abiotic reduction of inorganic carbon, but the conditions under which this process can occur in natural systems remain unclear. In recent years, several studies have reported abiotic formation of CH 4 during experimental serpentinization of olivine at temperatures at or below 200 °C. However, these results seem to contradict studies conducted at higher temperatures (300 °C to 400 °C), where substantial kinetic barriers to CH 4 synthesis have been observed. Here, the potential for abiotic formation of CH 4 from dissolved inorganic carbon during olivine serpentinization is reevaluated in a series of laboratory experiments conducted at 200 °C to 320 °C. A 13 C-labeled inorganic carbon source was used to unambiguously determine the origin of CH 4 generated in the experiments. Consistent with previous high-temperature studies, the results indicate that abiotic formation of CH 4 from reduction of dissolved inorganic carbon during the experiments is extremely limited, with nearly all of the observed CH 4 derived from background sources. The results indicate that the potential for abiotic synthesis of CH 4 in low-temperature serpentinizing environments may be much more limited than some recent studies have suggested. However, more extensive production of CH 4 was observed in one experiment performed under conditions that allowed an H 2 -rich vapor phase to form, suggesting that shallow serpentinization environments where a separate gas phase is present may be more favorable for abiotic synthesis of CH 4 .

  3. Deformation, Fluid Flow and Mantle Serpentinization at Oceanic Transform Faults

    Science.gov (United States)

    Rupke, L.; Hasenclever, J.

    2017-12-01

    Oceanic transform faults (OTF) and fracture zones have long been hypothesized to be sites of enhanced fluid flow and biogeochemical exchange. In this context, the serpentine forming interaction between seawater and cold lithospheric mantle rocks is particularly interesting. The transformation of peridotite to serpentinite not only leads to hydration of oceanic plates and is thereby an important agent of the geological water cycle, it is also a mechanism of abiotic hydrogen and methane formation, which can support archeal and bacterial communities at the seafloor. Inferring the likely amount of mantle undergoing serpentinization reactions therefore allows estimating the amount of biomass that may be autotrophically produced at and around oceanic transform faults and mid-ocean ridges Here we present results of 3-D geodynamic model simulations that explore the interrelations between deformation, fluid flow, and mantle serpentinization at oceanic transform faults. We investigate how slip rate and fault offset affect the predicted patterns of mantle serpentinization around oceanic transform faults. Global rates of mantle serpentinization and associated H2 production are calculated by integrating the modeling results with plate boundary data. The global additional OTF-related production of H2 is found to be between 6.1 and 10.7 x 1011 mol per year, which is comparable to the predicted background mid-ocean ridge rate of 4.1 - 15.0 x 1011 mol H2/yr. This points to oceanic transform faults as potential sites of intense fluid-rock interaction, where chemosynthetic life could be sustained by serpentinization reactions.

  4. Serpentinization as a reactive transport process: The brucite silicification reaction

    Science.gov (United States)

    Tutolo, Benjamin M.; Luhmann, Andrew J.; Tosca, Nicholas J.; Seyfried, William E.

    2018-02-01

    Serpentinization plays a fundamental role in the biogeochemical and tectonic evolution of the Earth and perhaps many other rocky planetary bodies. Yet, geochemical models still fail to produce accurate predictions of the various modes of serpentinization, which limits our ability to predict a variety of related geological phenomena over many spatial and temporal scales. Here, we use kinetic and reactive transport experiments to parameterize the brucite silicification reaction and provide fundamental constraints on SiO2 transport during serpentinization. We show that, at temperatures characteristic of the sub-seafloor at the serpentinite-hosted Lost City Hydrothermal Field (150 °C), the assembly of Si tetrahedra onto MgOH2 (i.e., brucite) surfaces is a rate-limiting elementary reaction in the production of serpentine and/or talc from olivine. Moreover, this reaction is exponentially dependent on the activity of aqueous silica (a SiO2 (aq)), such that it can be calculated according to the rate law:

  5. Emergency cooling of presurized water reactor

    International Nuclear Information System (INIS)

    Sykora, D.

    1981-01-01

    The method described of emergency core cooling in the pressurized water reactor is characterized by the fact that water is transported to the disturbed primary circuit or direct to the reactor by the action of the energy and mass of the steam and/or liquid phase of the secondary circuit coolant, which during emergency core cooling becomes an emergency cooling medium. (B.S.)

  6. Contrasting serpentinization processes in the eastern Central Alps

    Science.gov (United States)

    Burkhard, D.J.M.; O'Neil, J.R.

    1988-01-01

    Stable isotope compositions have been determined for serpentinites from between Davos (Arosa-Platta nappe, Switzerland) and the Valmalenco (Italy). ??D and ??18O values (-120 to -60 and 6-10???, respectively) in the Arosa-Platta nappe indicate that serpentinization took place on the continent at relatively low temperatures in the presence of limited amounts of metamorphic fluids that contained a component of meteoric water. One sample of chrysotile has a ??18O value of 13??? providing evidence of high W/R ratios and low formation temperature of lizardite-chrysotile in this area. In contrast, relatively high ??D values (-42 to -34???) and low ??18O values (4.4-7.4???) for serpentine in the eastern part of the Valmalenco suggest a serpentinization process that took place at moderate temperatures in fluids that were dominated by ocean water. The antigorite in the Valmalenco is the first reported example of continental antigorite with an ocean water signature. An amphibole sample from a metasomatically overprinted contact zone to metasediments (??D=-36???) indicates that the metasomatic event also took place in the presence of ocean water. Lower ??D values (-93 to -60???) of serpentines in the western part of the Valmalenco suggest a different alteration history possibly influenced by fluids associated with contact metamorphism. Low water/rock ratios during regional metamorphism (and metasomatism) have to be assumed for both regions. ?? 1988 Springer-Verlag.

  7. The “Serpentine Syndrome” (H. Jenny, 1980: A Proxy for Soil Remediation

    Directory of Open Access Journals (Sweden)

    Claudio Bini

    2014-12-01

    Full Text Available Serpentine soils have relatively high concentrations of PTEs (Co, Cr, Cu, Fe, Ni but generally low amounts of major nutrients. They often bear a distinctive vegetation, and a frequently-used approach to understanding serpentine ecology and related environmental hazard has been the chemical analysis of soils and plants. In this paper we report past and current studies on serpentine soils and serpentinophytes. The serpentine vegetation differs from the conterminous non-serpentine areas, being often endemic, and showing macroscopic physionomical characters. Similarly, at microscopic level cytomorphological characteristics of the roots and variations in biochemical parameters were recorded in serpentinophytes. Light microscopy observations showed depressed mitotic activity in the meristematic zone, and consequent reduced root growth. The different tolerance mechanisms responsible for plant adaption to high concentrations of PTEs in serpentine soils can be related to the capacity of plants to limit metal uptake and translocation. The majority of serpentinophytes tend to limit metal absorption to roots: the cell wall constitutes a barrier against metal penetration inside plant tissues. Only a few species are able to accumulate metals in their aerial parts, acting a tolerance mechanism to very high metal concentrations. Serpentinophytes, therefore, could represent proxies for plants  used in remediation of metal-contaminated soils and in phytomining as well.

  8. Comparative Study of Crosstalk Reduction Techniques in RF Printed Circuit Board Using FDTD Method

    Directory of Open Access Journals (Sweden)

    Rajeswari Packianathan

    2015-01-01

    Full Text Available Miniaturization of the feature size in modern electronic circuits results from placing interconnections in close proximity with a high packing density. As a result, coupling between the adjacent lines has increased significantly, causing crosstalk to become an important concern in high-performance circuit design. In certain applications, microstriplines may be used in printed circuit boards for propagating high-speed signals, rather than striplines. Here, the electromagnetic coupling effects are analyzed for various microstrip transmission line structures, namely, microstriplines with a guard trace, double stub microstriplines, and parallel serpentine microstriplines using the finite-difference time-domain method. The numerical results are compared with simulation results, where the variants are simulated using an Ansoft high-frequency structure simulator. The analysis and simulation results are experimentally validated by fabricating a prototype and establishing a good correspondence between them. Numerical results are compared with simulation and experimental results, showing that double stub microstriplines reduce the far end crosstalk by 7 dB and increase the near end crosstalk by about 2 dB compared with the parallel microstriplines. Parallel serpentine microstriplines reduce the far end crosstalk by more than 10 dB and also reduce more than 15 mV of peak far end crosstalk voltage, compared with parallel microstriplines.

  9. Controls of faulting and reaction kinetics on serpentinization and double Benioff zones

    OpenAIRE

    Iyer, Karthik; Rüpke, Lars H.; Phipps Morgan, Jason; Grevemeyer, Ingo

    2012-01-01

    The subduction of partially serpentinized oceanic mantle may potentially be the key geologic process leading to the regassing of Earth's mantle and also has important consequences for subduction zone processes such as element cycling, slab deformation, and intermediate-depth seismicity. However, little is known about the quantity of water that is retained in the slab during mantle serpentinization and the pattern of serpentinization that may occur during bending-related faulting; an initial s...

  10. Energy reduction for a dual circuit cooling water system using advanced regulatory control

    International Nuclear Information System (INIS)

    Muller, C.J.; Craig, I.K.

    2016-01-01

    Highlights: • Potentially reduce energy required by a dual circuit cooling water system by 30%. • Accomplished using an advanced regulatory control and switching strategy. • No formal process model is required. • Can be implemented on control system hardware commonly used in industry. - Abstract: Various process utilities are used in the petrochemical industry as auxiliary variables to facilitate the addition/removal of energy to/from the process, power process equipment and inhibit unwanted reaction. Optimisation activities usually focus on the process itself or on the utility consumption though the generation and distribution of these utilities are often overlooked in this regard. Many utilities are prepared or generated far from the process plant and have to be transported or transmitted, giving rise to more losses and potential inefficiencies. To illustrate the potential benefit of utility optimisation, this paper explores the control of a dual circuit cooling water system with focus on energy reduction subject process constraints. This is accomplished through the development of an advanced regulatory control (ARC) and switching strategy which does not require the development of a system model, only rudimentary knowledge of the behaviour of the process and system constraints. The novelty of this manuscript lies in the fact that it demonstrates that significant energy savings can be obtained by applying ARC to a process utility containing both discrete and continuous dynamics. Furthermore, the proposed ARC strategy does not require a plant model, uses only existing plant equipment, and can be implemented on control system hardware commonly used in industry. The simulation results indicate energy saving potential in the region of 30% on the system under investigation.

  11. Micro-, to nano-structural relationships in natural serpentines, derived from cationic substitutions.

    Science.gov (United States)

    Munoz, M.; Farges, F.; Andreani, M.; Ulrich, M.; Marcaillou, C.; Mathon, O.

    2014-12-01

    The understanding of the crystal chemistry of serpentine minerals (incl. antigorite, lizardite and chrysotile) is fundamental since serpentinization processes concern very large scientific domains: e.g., natural abiotic hydrogen production (Marcaillou et al., 2011), origins of life (Russell et al., 2010), fluid properties and mobility of metals in subduction zones (Kelley and Cottrell, 2009). This study aims at characterizing relations between the micro-, and nano-structures of the most abundant serpentine polytypes in the oceanic crust. Serpentine theoretical formula is Mg3Si2O5(OH)4 but several natural substitutions are possible and the formula may be written such as: (Mg,Fe2+,Fe3+,Al)3(Si,Al,Fe3+)2O5(OH)4; showing that Fe and Al may play an important role in the crystallization of serpentines. Preliminary crystal chemistry studies, suggest that, 1) the Al content alone cannot be directly correlated to serpentine polytypes (Andreani et al., 2008), 2) the amounts of tetrahedral iron can be significant in the presence of ferric iron (Marcaillou et al., 2011). Because magnetite is usually associated to serpentine, the Fe-speciation characterization of serpentine is delicate. Here, we provide the study of 33 magnetite-free serpentines containing various amounts of Fe and Al. The samples were characterized by SEM, Raman, XRF, as well as XANES, pre-edge, and EXAFS spectroscopy at the Fe K-edge. XANES experimental data were crosschecked and interpreted thanks to ab initio calculations and EXAFS shell-fitting. Also, preliminary 27Al-RMN data is presented. Results suggest relationships between the type and amount of substitution of trivalent cations in minerals, and the microstructures observed. Chrysotile incorporates less trivalent cations than other varieties, which tends to preserve the so-called misfit between the TO layers, and therefore the tubular structure of the mineral. Lizardites mainly involve Fe/Al Tschermak-type substitutions, while M-site vacancy charge

  12. Petrology and Geochemistry of Serpentinized Peridotites from a Bonin Fore-arc Seamount

    Science.gov (United States)

    Tian, L.; Tuoyu, W.; Dong, Y. H.; Gao, J.; Wu, S.

    2016-12-01

    Serpentinites, which contain up to 13 wt.% of water, are an important reservoir for chemical recycling in subduction zones. During the last two decades, many observations documented the occurrence of fore-arc mantle serpentinites in different locations. Here, we present petrology and whole rock chemistry for serpentinized peridotites dredged from the Hahajima Seamount, which is located 20-60 km west of the junction of the Bonin Trench and the Mariana Trench. Combined with published geochemical data of serpentinites from the Torishima Seamount, Conical Seamount and South Chamorro Seamount in the Izu-Bonin-Mariana fore-arc region, it will allow us to better understand the average composition of serpentinized fore-arc mantle overlying the subducting slab and the role of serpentinized mantle playing in the subduction zone geochemical cycle. The studied ultramafic rocks from the Hahajima Seamount are extensively serpentinized and hydrated (73 to 83%), with loss of ignition values ranging between 13 and 15 wt.%. Our results show that the serpentinized peridotites have Mg number from 88 to 90, and the average MgO/SiO2 is 0.93. The average Al2O3 (0.48 wt.%) and CaO (0.23 wt.%) contents are very low, consistent with low clinopyroxene abundances, and the overall depleted character of the mantle harzburgite protoliths. The serpentinized peridotites from the Hahajima Seamount exhibit similar "U" shape rare earth element (REE) patterns ([La/Sm]N = 3.1-3.6), at higher overall abundances, to the Conical and South Chamorro Seamount suites. One exceptional sample shows the similar REE pattern as serpentinized peridotites from the Torishima Seamount, with depleted light REE concentration ([La/Sm]N =0.7). All the serpentinized peridotites from these four fore-arc seamounts show strong enrichment in fluid-mobile and lithophile elements (U, Pb, Sr and Li). The geochemical signature of the serpentinized peridotites from the seamounts in the Izu-Bonin-Mariana fore-arc region could be

  13. Geochemistry of reduced gas related to serpentinization of the Zambales ophiolite, Philippines

    Science.gov (United States)

    Abrajano, T.A.; Sturchio, N.C.; Kennedy, B.M.; Lyon, G.L.; Muehlenbachs, K.; Böhlke, J.K.

    1990-01-01

    Methane-hydrogen gas seeps with mantle-like C and noble gas isotopic characteristics issue from partially serpentinized ultramafic rocks in the Zambales ophiolite, Philippines. New measurements of noble gas and 14C isotope abundances, rock/mixed-volatile equilibrium calculations, and previous chemical and isotopic data suggest that these reduced gases are products of periodotite hydration. The gas seeps are produced in rock-dominated zones of serpentinization, and similar gases may be ubiquitous in ultramafic terranes undergoing serpentinization.

  14. CURRENT BUILDUP IN EMERGING SERPENTINE FLUX TUBES

    International Nuclear Information System (INIS)

    Pariat, E.; Masson, S.; Aulanier, G.

    2009-01-01

    The increase of magnetic flux in the solar atmosphere during active-region formation involves the transport of the magnetic field from the solar convection zone through the lowest layers of the solar atmosphere, through which the plasma β changes from >1 to <1 with altitude. The crossing of this magnetic transition zone requires the magnetic field to adopt a serpentine shape also known as the sea-serpent topology. In the frame of the resistive flux-emergence model, the rising of the magnetic flux is believed to be dynamically driven by a succession of magnetic reconnections which are commonly observed in emerging flux regions as Ellerman bombs. Using a data-driven, three-dimensional (3D) magnetohydrodynamic numerical simulation of flux emergence occurring in active region 10191 on 2002 November 16-17, we study the development of 3D electric current sheets. We show that these currents buildup along the 3D serpentine magnetic-field structure as a result of photospheric diverging horizontal line-tied motions that emulate the observed photospheric evolution. We observe that reconnection can not only develop following a pinching evolution of the serpentine field line, as usually assumed in two-dimensional geometry, but can also result from 3D shearing deformation of the magnetic structure. In addition, we report for the first time on the observation in the UV domain with the Transition Region and Coronal Explorer (TRACE) of extremely transient loop-like features, appearing within the emerging flux domain, which link several Ellermam bombs with one another. We argue that these loop transients can be explained as a consequence of the currents that build up along the serpentine magnetic field.

  15. Resistive cooling circuits for charged particle traps using crystal resonators

    CERN Document Server

    Kaltenbacher, T; Doser, M; Kellerbauer, A; Pribyl, W

    2011-01-01

    The paper addresses a novel method to couple a signal from charged particles in a Penning trap to a high Q resonant circuit using a crystal resonator. Traditionally the trap capacity is converted into a resonator by means of an inductance. When normal conducting wires (e.g. copper) are applied to build up a coil, the unloaded Q value is limited to a value in the order of 1000. The tuned circuit’s Q factor is directly linked to the input impedance “seen” by the trapped particles at resonance frequency. This parallel resonance impedance is a measure of the efficiency of resistive cooling and thus it should be optimized. We propose here a commercially available crystal resonator since it exhibits a very high Q value and a parallel resonance impedance of several MOhm. The possibility to tune the parallel resonance frequency of the quartz results in filter behavior that allows covering a broad range of frequencies.

  16. Origin of multiple serpentinization events in New Caledonia

    Science.gov (United States)

    Ulrich, M.; Guillot, S.; Muñoz, M.; Picard, C.

    2011-12-01

    Studies on serpentinites around the world have shown that various polymorphs can coexist depending on the temperature, pressure and chemistry of the formation environment. Identifying serpentine polymorphs can thus provide significant constrains on the geodynamic environment at the time of formation. The New Caledonia ophiolite (Southwest Pacific) is one of the world's largest (500 km long, 50 km wide and 2 km thick). Emplaced during Eocene, it is thrust upon the continental Norfolk ridge, which derived from the splitting of the East Gondwana margin during Lower Late Cretaceous. The ophiolite consists of a large continuous massif occurring in the south of the island and some smaller isolated klippes located along the West coast. The peridotites are mostly harzburgite, related to a supra-subduction zone environment. The northernmost massifs are also composed of lherzolites, inherited from the opening of the South Loyalty Basin where the ophiolite was formed. Serpentinization is ubiquitous (usually >50%) independently from the nature of the peridotite. However, numerous studies have focused on the ophiolite but very few on the serpentinite. In this study, we use the Raman spectroscopy to identify serpentine polymorph in each part of the ophiolite. In situ trace element measurements were performed to constrain the behavior of fluid mobile element (FME: As, Sb, B, Li, Cs, Pb, U, Ba, Sr), and we are currently analyzing stable isotopic ratios to investigate the origin of fluids. Our results show that lizardite represents ~90% of the serpentine in the New Caledonia ophiolite. Only the serpentine sole has recorded multiple serpentinization events. In this horizon, the lizardite is crosscut by millimeter to centimeter antigorite veins. Chrysotile is the last polymorph to crystallize in millimeter crackseals. If the formation of the lizardite can be easily related to abyssal history of the ophiolite for the lherzolite and its supra-subduction history for the harzburgite, the

  17. Dynamics of soil chemistry in different serpentine habitats from Serbia

    Directory of Open Access Journals (Sweden)

    Vicić Dražen D.

    2014-01-01

    Full Text Available To enhance understanding of edaphic conditions in serpentine habitats, a thorough investigation of chemical and mechanical properties of three soils from disjunct ultramafic outcrops in the central Balkans was undertaken. Soil from a nearby chemically-contrasting limestone habitat was also analyzed. Three plant species differently associated with serpentine (Halacsya sendtneri, Cheilanthes marantae, and Seseli rigidum were references for site and soil selection. Twenty elements were scanned for, and fourteen were measured in seven sequentially-extracted soil fractions. Quantified soil properties also included: pH, levels of free CaCO3, organic matter, P2O5, K2O, N, C, S, cation exchange capacity, total organic carbon, field capacity and soil mechanical composition. The usual harsh components for plant growth in serpentine soil such as elevated Mg:Ca ratio, high levels of Ni, Cr, or Co, were significantly lower in the available fractions. There was a significant positive correlation of organic matter and field capacity, with most available Ca (70-80% found in the mobile, rather than the organically-bound fraction. This showed that a more favorable Mg:Ca ratio is highly dependent upon a higher field capacity, which is also in accordance with a more developed vegetation. Increasing the availability of metals (Al, Ba, Ca, Cr, Cu, Mg, Ni, Zn in a more developed serpentine grassland and forest vegetation, occurred only simultaneously with decrease of the Mg:Ca ratio and rise in other factors of fertility (N, P, K. Progressive development of ecosystem complexity therefore raised the availability of metals, but also reduced harsh Mg:Ca ratio disproportion, boosted levels of nutrients and raised soil field capacity. Principal components analysis confirmed that the main differences among serpentine habitats lay primarily in factors of fertility. The common habitat which hosts all three reference species offers intermediate conditions in a plant habitat

  18. Testing nickel tolerance of Sorghastrum nutans and its associated soil microbial community from serpentine and prairie soils

    International Nuclear Information System (INIS)

    Doherty, Jennifer H.; Ji Baoming; Casper, Brenda B.

    2008-01-01

    Ecotypes of Sorghastrum nutans from a naturally metalliferous serpentine grassland and the tallgrass prairie were assessed for Ni tolerance and their utility in remediation of Ni-polluted soils. Plants were inoculated with serpentine arbuscular mycorrhizal (AM) root inoculum or whole soil microbial communities, originating from either prairie or serpentine, to test their effects on plant performance in the presence of Ni. Serpentine plants had marginally higher Ni tolerance as indicated by higher survival. Ni reduced plant biomass and AM root colonization for both ecotypes. The serpentine AM fungi and whole microbial community treatments decreased plant biomass relative to uninoculated plants, while the prairie microbial community had no effect. Differences in how the soil communities affect plant performance were not reflected in patterns of root colonization by AM fungi. Thus, serpentine plants may be suited for reclamation of Ni-polluted soils, but AM fungi that occur on serpentine do not improve Ni tolerance. - Ni tolerance of Sorghastrum nutans differs slightly between serpentine and prairie populations and is negatively affected by serpentine soil and root inoculation

  19. Binding energy and mechanical stability of single- and multi-walled carbon nanotube serpentines

    International Nuclear Information System (INIS)

    Zhao, Junhua; Lu, Lixin; Rabczuk, Timon

    2014-01-01

    Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] and Machado et al. [Phys. Rev. Lett. 110, 105502 (2013)] reported the experimental and molecular dynamics realization of S-like shaped single-walled carbon nanotubes (CNTs), the so-called CNT serpentines. We reported here results from continuum modeling of the binding energy γ between different single- and multi-walled CNT serpentines and substrates as well as the mechanical stability of the CNT serpentine formation. The critical length for the mechanical stability and adhesion of different CNT serpentines are determined in dependence of E i I i , d, and γ, where E i I i and d are the CNT bending stiffness and distance of the CNT translation period. Our continuum model is validated by comparing its solution to full-atom molecular dynamics calculations. The derived analytical solutions are of great importance for understanding the interaction mechanism between different single- and multi-walled CNT serpentines and substrates

  20. Evaluation of serpentine ore as a nuclear shielding material using gas chromatographic techniques

    International Nuclear Information System (INIS)

    Singh, B.N.; Unnikrishnan, E.K.; Kumar, Sangita D.

    2007-01-01

    Serpentine ore mixed with cement has been recognized as a candidate shielding material for use in nuclear reactors because of its many desirable properties. Therefore the assessment of serpentine ore for release of volatile gases during exposure to elevated temperatures, irradiation and changes in chemical composition, is essential. The present paper deals with the studies on the serpentine ores using gas chromatography and combustion gas chromatographic techniques. (author)

  1. Thermodynamic study of the effects of ambient air conditions on the thermal performance characteristics of a closed wet cooling tower

    International Nuclear Information System (INIS)

    Papaefthimiou, V.D.; Rogdakis, E.D.; Koronaki, I.P.; Zannis, T.C.

    2012-01-01

    A thermodynamic model was developed and used to assess the sensitivity of thermal performance characteristics of a closed wet cooling tower to inlet air conditions. In the present study, three cases of different ambient conditions are considered: In the first case, the average mid-winter and mid-summer conditions as well as the extreme case of high temperature and relative humidity, in Athens (Greece) during summer are considered according to the Greek Regulation for Buildings Energy Performance. In the second case, the varied inlet air relative humidity while the inlet air dry bulb temperature remains constant were taken into account. In the last case, the effects on cooling tower thermal behaviour when the inlet air wet bulb temperature remains constant were examined. The proposed model is capable of predicting the variation of air thermodynamic properties, sprayed water and serpentine water temperature inside the closed wet cooling tower along its height. The reliability of simulations was tested against experimental data, which were obtained from literature. Thus, the proposed model could be used for the design of industrial and domestic applications of conventional air-conditioning systems as well as for sorption cooling systems with solid and liquid desiccants where closed wet cooling towers are used for precooling the liquid solutions. The most important result of this theoretical investigation is that the highest fall of serpentine water temperature and losses of sprayed water are observed for the lowest value of inlet wet bulb temperature. Hence, the thermal effectiveness, which is associated with the temperature reduction of serpentine water as well as the operational cost, which is related to the sprayed water loss due to evaporation, of a closed wet cooling tower depend predominantly on the degree of saturation of inlet air.

  2. Serpentinization processes: Influence of silica

    Science.gov (United States)

    Huang, R.; Sun, W.; Ding, X.; Song, M.; Zhan, W.

    2016-12-01

    Serpentinization systems are highly enriched in molecular hydrogen (H2) and hydrocarbons (e.g. methane, ethane and propane). The production of hydrocarbons results from reactions between H2 and oxidized carbon (carbon dioxide and carbon monoxide), which possibly contribute to climate changes during early history of the Earth. However, the influence of silica on the production of H2 and hydrocarbons was poorly constrained. We performed experiments at 311-500 °C and 3.0 kbar using mechanical mixtures of silica and olivine in ratios ranging from 0 to 40%. Molecular hydrogen (H2), methane, ethane and propane were formed, which were analyzed by gas chromatography. It was found that silica largely decreased H2 production. Without any silica, olivine serpentinization produced 94.5 mmol/kg H2 after 20 days of reaction time. By contrast, with the presence of 20% silica, H2 concentrations decreased largely, 8.5 mmol/kg. However, the influence of silica on the production of hydrocarbons is negligible. Moreover, with the addition of 20%-40% silica, the major hydrous minerals are talc, which was quantified according to an established standard curve calibrated by infrared spectroscopy analyses. It shows that silica greatly enhances olivine hydration, especially at 500 °C. Without any addition of silica, reaction extents were serpentinization at 500 °C and 3.0 kbar. By contrast, with the presence of 50% silica, olivine was completely transformed to talc within 9 days. This study indicates that silica impedes the oxidation of ferrous iron into ferric iron, and that rates of olivine hydration in natural geological settings are much faster with silica supply.

  3. Geochemical bioenergetics during low-temperature serpentinization: An example from the Samail ophiolite, Sultanate of Oman

    Science.gov (United States)

    Canovas, Peter A.; Hoehler, Tori; Shock, Everett L.

    2017-07-01

    Various classes of microbial and biomolecular evidence from global studies in marine and continental settings are used to identify a set of reactions that appear to support microbial metabolism during serpentinization of ultramafic rocks. Geochemical data from serpentinizing ecosystems in the Samail ophiolite of Oman are used to evaluate the extent of disequilibria that can support this set of microbial metabolisms and to provide a ranking of potential metabolic energy sources in hyperalkaline fluids that are direct products of serpentinization. Results are used to construct hypotheses for how microbial metabolism may be supported in the subsurface for two cases: ecosystems hosted in rocks that have already undergone significant serpentinization and those hosted by deeper, active serpentinization processes.

  4. D/H diffusion in serpentine

    Science.gov (United States)

    Pilorgé, Hélène; Reynard, Bruno; Remusat, Laurent; Le Floch, Sylvie; Montagnac, Gilles; Cardon, Hervé

    2017-08-01

    Interactions between aqueous fluids and ultrabasic rocks are essential processes in a broad range of contexts including hydrothermal alteration on the parent body of carbonaceous chondrites, at mid-oceanic ridge, and in subduction zones. Tracking these processes and understanding reaction kinetics require knowledge of the diffusion of water in rocks, and of isotope fractionation in major minerals forming under hydrous conditions, such as serpentines. We present a study of D/H inter-diffusion in antigorite, a common variety of serpentine. Experiments were performed in a belt apparatus at 315 °C, 450 °C and 540 °C and at 3.0 GPa on natural antigorite powders saturated with interstitial D2O. An experiment was performed in a diamond anvil cell at 350 °C and 2.5 GPa on an antigorite single-crystal loaded with pure D2O. D/(D + H) ratios were mapped using Raman spectroscopy for the experiments at 315 °C, 450 °C and 540 °C and by NanoSIMS for the experiment at 350 °C. As antigorite is a phyllosilicate, diffusion coefficients were obtained for crystallographic directions parallel and perpendicular to the silicate layers (perpendicular and parallel to the c∗-axis, respectively). Arrhenius relations for D/H inter-diffusion coefficients were determined to be DD/H (m2/s) = 4.71 × 10-2 × exp(-207(-33/+58) (kJ/mol)/RT) and DD/H (m2/s) = 1.61 × 10-4 × exp(-192(-34/+93) (kJ/mol)/RT) perpendicular and parallel to the c∗-axis, respectively, and DD/H (m2/s) = 7.09 × 10-3 × exp(-202(-33/+70) (kJ/mol)/RT) for the bulk diffusivity. Assuming D/H inter-diffusion coefficients for antigorite are the same for all serpentine species, closure temperature and diffusion durations are applied to hydrothermal alteration in the oceanic lithosphere, and in CI, CM and CR chondrites. Closure temperatures lie below 300 °C for terrestrial hydrothermal alteration and depend on serpentine variety because they have different typical grain sizes. Closure temperatures lie below 160 °C for

  5. Petrology and Rock Magnetism of the peridotites of Pindos Ophiolite (Greece), insights into the serpentinization process

    Science.gov (United States)

    Bonnemains, D.; Carlut, J. H.; Mevel, C.; Andreani, M.; Escartin, J.; Debret, B.

    2015-12-01

    We present a petrological and magnetic study of a suite of serpentinized peridotites from the Pindos ophiolite spanning a wide range in the degree of serpentinization (from ~10 to 100%). The Pindos ophiolite, in Northern Greece, is a portion of Late Triassic oceanic lithosphere obducted during the convergence of the Apulian and Pelagonian micro-continents. This ophiolite is interpreted mainly as the result of a supra-subduction zone spreading process but its complete history remains largely unknown. Therefore, it is not clear when the ultramafic section was exposed to fluid circulation that resulted in its serpentinization. Element partitioning during serpentinization reactions is dependent on parameters such as temperature and water-rock ratio. In particular, they affect the behavior of the iron released by olivine, which can be taken up either by magnetite, serpentine and/or brucite. Analyses of the reaction products are therefore a key to constrain the conditions during the main stage of the alteration. Our study was designed to gain insight on the conditions prevailing during hydration. Our results indicate that even fully serpentinized samples have a very low magnetization and magnetite content. Moreover, microprobe and μXanes results show that serpentine is the main host of iron in the divalent but also trivalent form. These results are compared with a set of data from serpentinized ultramafics sampled from the ocean floors, as well as from various other ophiolites. We suggest that serpentinization at Pindos occurred at relatively low-temperature (less than 200 °C), therefore not at a ridge environment. In addition, we stress that the presence of trivalent iron in serpentine indicates that serpentinization may remain a producer of hydrogen even when very little magnetite is formed.

  6. Fe-Ni-bearing serpentines from the saprolite horizon of Caribbean Ni-laterite deposits: new insights from thermodynamic calculations

    Science.gov (United States)

    Villanova-de-Benavent, Cristina; Domènech, Cristina; Tauler, Esperança; Galí, Salvador; Tassara, Santiago; Proenza, Joaquín A.

    2017-10-01

    Fe-Ni-bearing serpentine from the saprolite horizon is the main Ni ores in hydrous silicate-type Ni laterites and formed by chemical weathering of partially serpentinized ultramafic rocks under tropical conditions. During lateritization, Mg, Si, and Ni are leached from the surface and transported downwards. Fe2+ is oxidized to Fe3+ and fixed as insoluble Fe-oxyhydroxides (mostly goethite) that incorporate Ni. This Ni is later leached from goethite and incorporated in secondary serpentine and garnierite. As a result, a serpentine-dominated saprolite horizon forms over the ultramafic protolith, overlapped by a Fe-oxyhydroxide-dominated limonite horizon. The serpentine from the protolith (serpentine I) is of hydrothermal origin and yields similar Ni (0.10-0.62 wt.% NiO) and lower Fe (mostly 1.37-5.81 wt.% FeO) concentrations than the primary olivine. In contrast, Fe-Ni-bearing serpentine from the saprolite (serpentine II) shows significantly higher and variable Fe and Ni contents, typically ranging from 2.23 to 15.59 wt.% Fe2O3 and from 1.30 to 7.67 wt.% NiO, suggesting that serpentine get enriched in Fe and Ni under supergene conditions. This study presents detailed mineralogical, textural, and chemical data on this serpentine II, as well as new insights by thermodynamic calculations assuming ideal solution between Fe-, Ni- and Mg-pure serpentines. The aim is to assess if at atmospheric pressure and temperature Fe-Ni-bearing serpentine can be formed by precipitation. Results indicate that the formation of serpentine II under atmospheric pressure and temperature is thermodynamically supported, and pH, Eh, and the equilibrium constant of the reaction are the parameters that affect the results more significantly.

  7. Thermal computations for electronics conductive, radiative, and convective air cooling

    CERN Document Server

    Ellison, Gordon

    2010-01-01

    IntroductionPrimary mechanisms of heat flowConductionApplication example: Silicon chip resistance calculationConvectionApplication example: Chassis panel cooled by natural convectionRadiationApplication example: Chassis panel cooled only by radiation 7Illustrative example: Simple thermal network model for a heat sinked power transistorIllustrative example: Thermal network circuit for a printed circuit boardCompact component modelsIllustrative example: Pressure and thermal circuits for a forced air cooled enclosureIllustrative example: A single chip package on a printed circuit board-the proble

  8. Fluid elastic instability analysis of 1/6th experimental model of PFBR main vessel cooling circuit

    International Nuclear Information System (INIS)

    Jalaldeen, S.; Ravi, R.; Chellapandi, P.; Bhoje, S.B.

    1993-01-01

    In reactor assembly of Prototype Fast Breeder Reactor (PFBR), the main vessel (MV) temperature is kept below creep range i.e. less than 427 deg C by way of diverting a small fraction of core flow from the cold pool and sent through the passage between main vessel and an outer cylindrical baffle to cool the vessel. The sodium coning from this, is collected by another inner baffle and then returned to cold pool again. This system is termed as MV cooling circuit. The outer and inner baffles form feeding and restitution collectors respectively. The sodium from the feeding collector flows over the outer baffle and falls through a height of about 0.5 m before impacting on the free surface of sodium in the restitution collector. The fall of sodium may become a source of vibration of the baffles. Such vibrations have been already noted in case of SPX-I during its commissioning stage. For PFBR, the theoretical analysis was done to assess the fluid-elastic instability risks and stability charts were obtained. By this, it was concluded that the operating point (flow rate and fall height) lies within the stable zone. In order to confirm the above analysis results, a series of experiments were proposed. One preliminary experiment on 1/16 th model of MV cooling circuit has been completed. This model has also been analysed theoretically for the fluid- elastic instability, the theoretical analysis involves 2 stage computations. In the first stage, free vibration analysis with fluid structure interaction (FSI) effect for experimental model has been done using INCA (CASTEM 1985) code and all the mode shapes including sloshing are extracted. In the second stage the instability analysis is performed with the free vibration results from INCA. For the instability computations, a code WEIR has been written based on Aita's instability criteria [Aita.S. 1986

  9. Process and device for cooling liquid or vaporised fluids

    International Nuclear Information System (INIS)

    1975-01-01

    The invention relates to a process for the ambient air cooling of liquid fluids or those vaporised under low pressure. An exchanger composing a first circuit for the fluid to be cooled is set up and is separated by a partition from a second circuit swept by the atmospheric air. Each one of these two circuits is made up of pipes of not more than 4 mm hydraulic diameter and on the side of the second circuit swept by the air a quantity of water is brought to the extent of 0 to 50 g/kg of dry air crossing it. The water is sprayed into the second circuit. The tubes of the second circuit are set up so that the water sprayed on, runs down the partition separating the two circuits. The water is sprayed counter-current with respect to the direction of the cooling air. A quantity of water is projected into the second circuit depending on the thermal flow to be exchanged and the desired cooling temperature, the amount of water being limited so that the outgoing air, returned to the atmosphere, contains an amount of water per kilogram of dry air corresponding to the absolute moisture of the saturated air for the dry ambient temperature at the time. The process affords all the advantages of a wet cooling tower, great efficiency and low temperature [fr

  10. Serpentine Coil Topology for BNL Direct Wind Superconducting Magnets

    CERN Document Server

    Parker, Brett

    2005-01-01

    BNL direct wind technology, with the conductor pattern laid out without need for extra tooling (no collars, coil presses etc.) began with RHIC corrector production. RHIC patterns were wound flat and then wrapped on cylindrical support tubes. Later for the HERA-II IR magnets we improved conductor placement precision by winding directly on a support tube. To meet HERA-II space and field quality goals took sophisticated coil patterns, (some wound on tapered tubes). We denote such patterns, topologically equivalent to RHIC flat windings, "planar patterns." Multi-layer planar patterns run into trouble because it is hard to wind across existing turns and magnet leads get trapped at poles. So we invented a new "Serpentine" winding style, which goes around 360 degrees while the conductor winds back and forth on the tube. To avoid making solenoidal fields, we wind Serpentine layers in opposite handed pairs. With a Serpentine pattern each turn can have the same projection on the coil axis and integral field harmonics t...

  11. Bioleaching of serpentine group mineral by fungus Talaromyces flavus: application for mineral carbonation

    Science.gov (United States)

    Li, Z.; Lianwen, L.; Zhao, L.; Teng, H.

    2011-12-01

    Many studies of serpentine group mineral dissolution for mineral carbonation have been published in recent years. However, most of them focus mainly on either physical and chemical processes or on bacterial function, rather than fungal involvement in the bioleaching of serpentine group mineral. Due to the excessive costs of the magnesium dissolution process, finding a lower energy consumption method will be meaningful. A fungal strain Talaromyces flavus was isolated from serpentinic rock of Donghai (China). No study of its bioleaching ability is currently available. It is thus of great significance to explore the impact of T. flavus on the dissolution of serpentine group mineral. Serpentine rock-inhabiting fungi belonging to Acremonium, Alternaria, Aspergillus, Botryotinia, Cladosporium, Clavicipitaceae, Cosmospora, Fusarium, Monascus, Paecilomyces, Penicillium, Talaromyces, Trichoderma were isolated. These strains were chosen on the basis of resistance to magnesium and nickel characterized in terms of minimum inhibiting concentration (MIC). Specifically, the strain Talaromyces flavus has a high tolerance to both magnesium (1 mol/L) and nickel (10 mM/L), and we examine its bioleaching ability on serpentine group mineral. Contact and separation experiments (cut-off 8 000-14 000 Da), as well as three control experiments, were set up for 30 days. At least three repeated tests were performed for each individual experiment. The results of our experiments demonstrate that the bioleaching ability of T. flavus towards serpentine group mineral is evident. 39.39 wt% of magnesium was extracted from lizardite during the bioleaching period in the contact experiment, which showed a dissolution rate at about a constant 0.126 mM/d before reaching equilibrium in 13 days. The amount of solubilized Mg from chrysotile and antigorite were respectively 37.79 wt% and 29.78 wt% in the contact experiment. These results make clear the influence of mineral structure on mineral bioleaching

  12. Dynamic control on serpentine crystallization in veins: Constraints on hydration processes in oceanic peridotites

    OpenAIRE

    Andréani , Muriel; Mével , C.; Boullier , A.-M.; Escartín , J.

    2007-01-01

    International audience; Deformation and hydration processes are intimately linked in the oceanic lithosphere, but the feedbacks between them are still poorly understood, especially in ultramafic rocks where serpentinization results in a decrease of rock density that implies a volume increase and/or mass transfer. Serpentinization is accompanied by abundant veining marked by different generations of vein-filling serpentines with a high variety of morphologies and textures that correspond to di...

  13. Water removal characteristics of parallel serpentine channels. Paper no. IGEC-1-035

    International Nuclear Information System (INIS)

    Jiao, K.; Zhou, B.; Quan, P.

    2005-01-01

    Water management in a proton exchange membrane (PEM) fuel cell stack has been a challenging issue on the road to commercialization. This paper presents a numerical investigation of air-water flow in parallel serpentine channels on cathode side of a PEM fuel cell stack by use of the commercial Computational Fluid Dynamics (CFD) software package FLUENT. Different air-water flow behaviours inside the serpentine flow channels with inlet and outlet manifolds were discussed. The results showed that there were significant variations of water distribution and pressure drop in different cells at different times. The 'collecting-and-separating effect' due to the serpentine shape of the gas flow channels, the pressure drop change due to the water distribution inside the outlet manifold were observed. Several gas flow problems of this type of parallel serpentine channels were identified and useful suggestions were given through investigating the flow patterns inside the channels and manifolds. (author)

  14. Influence of flow on the synergistic effect of an inhibitive mixture used for water treatment in cooling circuits

    International Nuclear Information System (INIS)

    Ochoa, Nathalie; Pebere, Nadine; Moran, Francis; Tribollet, Bernard

    2004-01-01

    This work concerned an extensive study of the mechanism of inhibition of a carbon steel in a 200 mg l -1 NaCl solution by a non-toxic multicomponent inhibitor used for water treatment in cooling circuits. The inhibitive formulation was composed of 50 mg l -1 fatty amines associated with 200 mg l -1 phosphonocarboxylic acid salts. The influence of flow and immersion time was investigated by electrochemical impedance spectroscopy with a rotating disc electrode. The results were dependent on the experimental protocol used. Equivalent circuits were used to fit the experimental data. The properties of the protective layer were dependent on the electrode rotation rate and on the immersion time. This behaviour was related to the influence of flow on the anodic kinetics. (authors)

  15. H2-rich fluids from serpentinization: Geochemical and biotic implications

    OpenAIRE

    Sleep, N. H.; Meibom, A.; Fridriksson, Th.; Coleman, R. G.; Bird, D. K.

    2004-01-01

    Metamorphic hydration and oxidation of ultramafic rocks produces serpentinites, composed of serpentine group minerals and varying amounts of brucite, magnetite, and/or FeNi alloys. These minerals buffer metamorphic fluids to extremely reducing conditions that are capable of producing hydrogen gas. Awaruite, FeNi3, forms early in this process when the serpentinite minerals are Fe-rich. Olivine with the current mantle Fe/Mg ratio was oxidized during serpentinization after the Moon-forming impac...

  16. Serpentinization of mantle-derived peridotites at mid-ocean ridges: Mesh texture development in the context of tectonic exhumation

    Science.gov (United States)

    Rouméjon, Stéphane; Cannat, Mathilde

    2014-06-01

    At slow spreading ridges, axial detachment faults exhume mantle-derived peridotites and hydrothermal alteration causes serpentinization in a domain extending more than 1 km next to the fault. At the microscopic scale, serpentinization progresses from a microfracture network toward the center of olivine relicts and forms a mesh texture. We present a petrographic study (SEM, EBSD, and Raman) of the serpentine mesh texture in a set of 278 abyssal serpentinized peridotites from the Mid-Atlantic and Southwest Indian Ridges. We show that serpentinization initiated along two intersecting sets of microfractures that have consistent orientations at the sample scale, and in at least one studied location, at the 100 m scale. We propose that these microfractures formed in fresh peridotites due to combined thermal and tectonic stresses and subsequently served as channels for serpentinizing fluids. Additional reaction-induced cracks developed for serpentinization extents <20%. The resulting microfracture network has a typical spacing of ˜60 µm but most serpentinization occurs next to a subset of these microfractures that define mesh cells 100-400 µm in size. Apparent mesh rim thickness is on average 33 ± 19 µm corresponding to serpentinization extents of 70-80%. Published laboratory experiments suggest that mesh rims formation could be completed in a few years (i.e., quasi instantaneous at the plate tectonic timescale). The depth and extent of the serpentinization domain in the detachment fault's footwall are probably variable in time and space and as a result we expect that the serpentine mesh texture at slow spreading ridges forms at variable rates with a spatially heterogeneous distribution.

  17. Contents of several elements in trees grown on the serpentine soil

    International Nuclear Information System (INIS)

    Tomita, Michio; Katayama, Yukio; Takada, Jitsuya; Nishimura, Kazuo.

    1990-01-01

    Determination of Mg-, Ca-, Cr-, Mn-, Fe- and Ni-content in akamatsu (P. densiflora), konara (Q. serrata) and ryoubu (C. barbinervis) which were grown on the serpentine soil, as well as in soil, were performed by the neutron activation method or the atomic absorption spectrophotometry. It turned out that contents of these elements was higher in leaves than wood. It was also found that Ni content in the leaves of konara as well as of ryoubu reflected the concentration of the acid extractable Ni in the serpentine soil. The elemental contents in akamatsu leaves were heavily affected by the characteristic contents of the serpentine soil. It is suggested that these trees are available for the indicator of soil-environment. (author)

  18. Gas cooled traction drive inverter

    Science.gov (United States)

    Chinthavali, Madhu Sudhan

    2013-10-08

    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.

  19. Cooling system for superconducting magnet

    Science.gov (United States)

    Gamble, Bruce B.; Sidi-Yekhlef, Ahmed

    1998-01-01

    A cooling system is configured to control the flow of a refrigerant by controlling the rate at which the refrigerant is heated, thereby providing an efficient and reliable approach to cooling a load (e.g., magnets, rotors). The cooling system includes a conduit circuit connected to the load and within which a refrigerant circulates; a heat exchanger, connected within the conduit circuit and disposed remotely from the load; a first and a second reservoir, each connected within the conduit, each holding at least a portion of the refrigerant; a heater configured to independently heat the first and second reservoirs. In a first mode, the heater heats the first reservoir, thereby causing the refrigerant to flow from the first reservoir through the load and heat exchanger, via the conduit circuit and into the second reservoir. In a second mode, the heater heats the second reservoir to cause the refrigerant to flow from the second reservoir through the load and heat exchanger via the conduit circuit and into the first reservoir.

  20. Reaction-induced fracturing during olivine serpentinization: A mechanistic investigation at the interface scale

    NARCIS (Netherlands)

    Plümper, O.; Røyne, A.; Malthe-Sørenssen, A.; King, H. E.; Jamtveit, B.

    Serpentinization of the Earth's impermeable upper mantle is one of the most fundamental metamorphic hydration reactions. It governs lithospheric weakening, geochemical subduction zone input and possibly even the formation of life-essential building blocks. Serpentinization relies on fluid pathway

  1. Vestiges of Submarine Serpentinization Recorded in the Microbiology of Continental Ophiolite Complexes

    Science.gov (United States)

    Schrenk, M. O.; Sabuda, M.; Brazelton, W. J.; Twing, K. I.

    2017-12-01

    The study of serpentinization-influenced microbial ecosystems at and below the seafloor has accelerated in recent years with multidisciplinary drilling expeditions to the Atlantis Massif (X357), Southwest Indian Ridge (X360) and Mariana Forearc (X366). In parallel, a number of studies have surveyed serpentinizing systems in ophiolite complexes which host a range of geologic histories, geochemical characteristics, fluid pathways, and consequently microbiology. As ophiolite complexes originate as seafloor materials, it is likely that a microbiological record of seafloor serpentinization processes is maintained through the emplacement and weathering of continental serpentinites. This hypothesis was evaluated through a global comparison of continental serpentinite springs and groundwater, ranging from highly brackish (saline) to freshwater. One of the most saline sites, known as the Coast Range Ophiolite Microbial Observatory (CROMO), was used as a point-of-comparison to marine serpentinizing systems, such as the Lost City Hydrothermal Field. Although there was little taxonomic overlap between microbial populations in marine and terrestrial systems, both communities harbored an abundance of genes involved in sulfur metabolism, including sulfide oxidation, thiosulfate disproportionation, and sulfate reduction. The phylogeny of key genes involved in these metabolic processes was evaluated relative to published studies and compared between sites. Together, these data provide insights into both the functioning of microbial communities in modern-day serpentinizing systems, and the transport processes that disperse microorganisms between marine and terrestrial serpentinites.

  2. Experimental investigation of As, Sb and Cs behavior during olivine serpentinization in hydrothermal alkaline systems

    Science.gov (United States)

    Lafay, Romain; Montes-Hernandez, German; Janots, Emilie; Munoz, Manuel; Auzende, Anne Line; Gehin, Antoine; Chiriac, Rodica; Proux, Olivier

    2016-04-01

    While Fluid-Mobile Elements (FMEs) such as B, Sb, Li, As or Cs are particularly concentrated in serpentinites, data on FME fluid-serpentine partitioning, distribution, and sequestration mechanisms are missing. In the present experimental study, the behavior of Sb, As and Cs during San Carlos olivine serpentinization was investigated using accurate mineralogical, geochemical, and spectroscopic characterization. Static-batch experiments were conducted at 200 °C, under saturated vapor pressure (≈1.6 MPa), for initial olivine grain sizes of coefficient increasing such as CsDp/fl = 1.5-1.6 elements are however substantially different. While the As partition coefficient remains constant throughout the serpentinization reaction, the Cs partition coefficient decreases abruptly in the first stages of the reaction to reach a constant value after the reaction is 40-60% complete. Both As and Cs partitioning appear to decrease with increasing initial olivine grain size, but there is no significant difference in the partitioning coefficient between the 30-56 and 56-150 μm grain size after complete serpentinization. X-ray absorption spectroscopy (XAS) measurements combined with X-ray chemical measurements reveal that the As(V) is mainly adsorbed onto the serpentinization products, especially brucite. In contrast, mineralogical characterization combined with XAS spectroscopy reveal redox sensitivity for Sb sequestration within serpentine products, depending on the progress of the reaction. When serpentinization is coefficient compared to that of the serpentine and brucite assemblage. Antimony reduction appears linked to water reduction accompanying the bulk iron oxidation, as half the initial Fe(II) is oxidized into Fe(III) and incorporated into the serpentine products once the reaction is over. The reduction of Sb implies a decrease of its solubility, but the type of secondary Sb-rich phases identified here might not be representative of natural systems where Sb

  3. Development of methods for the decrease in instability of recycling water of conjugated closed-circuit cooling system of HPP

    Science.gov (United States)

    Chichirov, A. A.; Chichirova, N. D.; Vlasov, S. M.; Lyapin, A. I.; Misbakhov, R. Sh.; Silov, I. Yu.; Murtazin, A. I.

    2016-10-01

    On Russian HPPs, conjugated closed-circuit cooling systems, where purge water is used as initial for water-treatment facilities, are widespread. For this reason, it is impossible to use general methods for the stabilization treatment of recycling water in order to prevent scale formation in the units of a system, namely, turbine condensers and cooling towers. In this paper, the methods for the decrease in the instability of recycling water using the methods of chemical engineering, such as stabilization and synchronization of flows and organization of recycles, are suggested. The results of an industrial experiment on the implementation of stabilization treatment of recycling water by the organization of recycle are given. The experiment was carried out on Kazan CHPP-3. The flow scheme involved the recycle of chemically purified water (CPW) for the heat network make-up to the closed-circuit cooling system. The experiment was carried out at three stages with the gradual change of the consumption of the recycle, namely, 0, 50, and 100 t/h. According to the results of experiments, the reliable decrease in the rate of the sedimentation was recorded on the units of the system, namely, turbine condenser and chimney-type cooling tower. This is caused by two reasons. Firstly, this is periodic excessive concentration of recycling water due to the nonstationary character of inlet and outlet flows. Secondly, this is seasonal (particularly, in the summer period) exceeding of the evaporation coefficient. As a result of stabilization and synchronization of flows and organization of recycles, the quality of clarified and chemically purified water for the heat network make-up increases and the corrosion of iron- and copper-containing structural materials decreases. A natural decrease in temperature drop on the operating turbine condensers is mentioned.

  4. Device for regulating light water nuclear reactors by changing the boric acid concentration in the cooling water circuit

    International Nuclear Information System (INIS)

    Brown, W.W.; Van der Schoot, M.R.

    1980-01-01

    Small changes in boric acid concentration can be carried out quickly by a combination of an ion exchanger with temperature-dependent capacity and an evaporator. No boric acid need be extracted from the circuit or added to it. However, if large changes of concentration are required, boric acid has to be added. The evaporator is then used to separate distilled water and concentrated boric acid when the cooling water is diluted. (DG) [de

  5. Feeding and purge systems of coolant primary circuit and coolant secondary circuit control of the I sup(123) target

    International Nuclear Information System (INIS)

    Almeida, G.L. de.

    1986-01-01

    The Radiation Protection Service of IEN (Brazilian-CNEN) detected three faults in sup(123)I target cooling system during operation process for producing sup(123)I: a) non hermetic vessel containing contaminated water from primary coolant circuit; possibility of increasing radioactivity in the vessel due to accumulation of contaminators in cooling water and; situation in region used for personnels to arrange and adjust equipments in nuclear physics area, to carried out maintenance of cyclotron and target coupling in irradiation room. The primary circuit was changed by secondary circuit for target coolant circulating through coil of tank, which receive weater from secondary circuit. This solution solved the three problems simultaneously. (M.C.K.)

  6. Radiation distribution through serpentine concrete using local materials and its application as a reactor biological shield

    International Nuclear Information System (INIS)

    Kansouh, W.A.

    2012-01-01

    Highlights: ► New serpentine concrete was made and examined as a reactor biological shield. ► Ilmenite–limonite concrete is a better reactor biological shield. ► New serpentine concrete is a better reactor fast neutrons shield than ordinary and hematite–serpentine concretes. ► Serpentine concrete has lower properties as a reactor total gamma rays shields. - Abstract: In the present work attempt has been made to estimate the shielding parameters of the new serpentine concrete (density = 2.4 g/cm 3 ) using local materials on the shielding parameters for two types of heat resistant concretes, namely hematite–serpentine (density = 2.5 g/cm 3 ) and ilmenite–limonite (density = 2.9 g/cm 3 ). Shielding parameters for ordinary concrete (density = 2.3 g/cm 3 ) were also discussed. These parameters were determined experimentally for serpentine concrete and compared with previously published values for other concretes, which had also been obtained using local materials. The leakage spectra of reactor fast neutrons and total gamma photon beams from cylindrical samples of these concrete shields were also investigated using a collimated beam from ET-RR-1 reactor. A neutron–gamma spectrometer was used in order to obtain pulse height spectra of reactor fast neutrons and the total gamma rays leakage through the investigated concrete samples. These spectra were utilized to obtain the energy spectra required in these investigations. Removal cross section Σ R (E n ) and linear attenuation coefficient μ(E g ) for reactor fast neutrons and total gamma rays and their relative coefficients were evaluated and presented. Measured results were compared with those previously measured for other concretes. The results show that ilmenite–limonite concrete is a better reactor biological shield than the other three concretes. Serpentine concrete under investigation is a better reactor fast neutrons shield than ordinary and hematite–serpentine concretes. Serpentine concrete

  7. Magnetic properties of serpentinized peridotites from the Zedong ophiolite, Yarlung-Zangbo suture zone, SE Tibet

    Science.gov (United States)

    Li, Z.; Zheng, J.; Moskowitz, B. M.; Xiong, Q.; Liu, Q.

    2017-12-01

    Serpentinized mantle peridotites are widely supposed to be significant sources of the magnetic, gravity and seismic anomalies in mid-oceanic ridges, forearcs and suture zones. However, the relationship between the magnetic properties of variably serpentinized peridotites and the serpentinization process is still under debate. Ophiolite outcrops commonly comprise peridotites in different stages of serpentinization and these ophiolitic peridotites are ideal to investigate the magnetic signatures of suture zones. The Zedong ophiolite locates in the eastern part of the Yarlung-Zangbo suture zone, SE Tibet (China), and the peridotite massif represents the remnants of the Neo-Tethyan lithospheric mantle. The harzburgite and lherzolite samples show densities between 3.316 and 2.593 g cm-3, and vary from the freshest to >90% serpentinized peridotites. The magnetic susceptibility curves from room temperature to 700ºC mainly show the Curie temperatures of 585ºC for pure magnetite. The low-temperature (20-300 K) demagnetization curves show the Verwey transitions at 115-125 K, suggesting that magnetite is also the dominant remanence-carrying phase. The hysteresis data of the peridotites fall in the region of pseudo-single-domain (PSD) and follow the theoretical trends for mixtures of single domain (SD) and multidomain (MD) magnetite. The first-order reversal curve (FORC) diagrams suggest that the magnetite is dominantly interacting SD + PSD particles for S 40% serpentinized samples. The susceptibility and saturation magnetization of the Zedong peridotites range from 0.9 to 30.8 × 10‒3 (SI) and 14.1 to 1318 × 10‒3 Am2 kg‒1, respectively, and both show consistent trends with increasing degrees of serpentinization. The S serpentinization of ophiolitic peridotites, whereas the S > 40% peridotites have higher susceptibilities of 0.02-0.03 (SI) and fall in the region of abyssal peridotites. Our results suggest that the Zedong ophiolitic peridotites probably experienced a

  8. Biofouling evaluation in the seawater cooling circuit of an operating coastal power plant

    Energy Technology Data Exchange (ETDEWEB)

    Murthy, P.S.; Veeramani, P.; Ershath, M.I.M.; Venugopalan, V.P. [BARC Facilities, Water and Steam Chemistry Div., Kalpakkam, Tamil Nadu (India)

    2010-07-01

    Chlorination is the most commonly used method of biofouling control in cooling water systems of coastal power stations. In the present study, we report results of extensive sampling in different sections of the cooling water system of an operating power station undertaken during three consecutive maintenance shutdowns. The power plant employed continuous low level chlorination (0.2 ± 0.1 mg L{sup -1} TRO) with twice-a-week booster dosing (0.4 ± 0.1 mg L-1 TRO for 8 hours). In addition, the process seawater heat exchangers received supplementary dosing of bromide treatment (0.2 ± 0.1 mg L{sup -1} TRO for 1 hour in every 8 h shift). Biofouling samples were collected from the cooling water conduits, heat exchanger water boxes, pipelines, heated discharge conduits and outfall section during the annual maintenance shutdown of the plant in the years 2007, 2008 and 2009. Simultaneous monitoring of biofouling on test coupons in coastal waters enabled direct comparison of fouling situation on test panels and that in the cooling system. The data showed significant reduction in biofouling inside the cooling circuit as compared to the coastal waters. However, significant amount of fouling was still evident at several places, indicating inadequacy of the biocide treatment regime. The maximum load of 31.3 kg m{sup 2} y{sup -1} was observed in the conduits leading to the process seawater heat exchangers (PSW-HX) and the minimum of 1.3 kg m{sup 2} y{sup -1} was observed in the outfall section. Fouling loads of 12.2 - 14.7 kg m{sup 2} y{sup -1} were observed in the concrete conduits feeding the main condensers. Bromide treatment ahead of the PSW-HX could marginally reduce the fouling load in the downstream section of the dosing point; the HX inlets still showed good biofouling. Species diversity across the cooling water system showed the pre-condenser section to be dominated by green mussels (Perna viridis), pearl oysters (Pinctada sp.) and edible oysters (Crassostrea sp

  9. Biofouling evaluation in the seawater cooling circuit of an operating coastal power plant

    International Nuclear Information System (INIS)

    Murthy, P.S.; Veeramani, P.; Ershath, M.I.M.; Venugopalan, V.P.

    2010-01-01

    Chlorination is the most commonly used method of biofouling control in cooling water systems of coastal power stations. In the present study, we report results of extensive sampling in different sections of the cooling water system of an operating power station undertaken during three consecutive maintenance shutdowns. The power plant employed continuous low level chlorination (0.2 ± 0.1 mg L -1 TRO) with twice-a-week booster dosing (0.4 ± 0.1 mg L-1 TRO for 8 hours). In addition, the process seawater heat exchangers received supplementary dosing of bromide treatment (0.2 ± 0.1 mg L -1 TRO for 1 hour in every 8 h shift). Biofouling samples were collected from the cooling water conduits, heat exchanger water boxes, pipelines, heated discharge conduits and outfall section during the annual maintenance shutdown of the plant in the years 2007, 2008 and 2009. Simultaneous monitoring of biofouling on test coupons in coastal waters enabled direct comparison of fouling situation on test panels and that in the cooling system. The data showed significant reduction in biofouling inside the cooling circuit as compared to the coastal waters. However, significant amount of fouling was still evident at several places, indicating inadequacy of the biocide treatment regime. The maximum load of 31.3 kg m 2 y -1 was observed in the conduits leading to the process seawater heat exchangers (PSW-HX) and the minimum of 1.3 kg m 2 y -1 was observed in the outfall section. Fouling loads of 12.2 - 14.7 kg m 2 y -1 were observed in the concrete conduits feeding the main condensers. Bromide treatment ahead of the PSW-HX could marginally reduce the fouling load in the downstream section of the dosing point; the HX inlets still showed good biofouling. Species diversity across the cooling water system showed the pre-condenser section to be dominated by green mussels (Perna viridis), pearl oysters (Pinctada sp.) and edible oysters (Crassostrea sp.), whereas the post-condenser section and heat

  10. Preserved organic matter in the Serpentinized Ocean-Continent Transition of Alpine Tethys

    Science.gov (United States)

    Mateeva, T.; Wolff, G. A.; Kusznir, N.; Manatschal, G.; Wheeler, J.

    2017-12-01

    Serpentinization occurs at slow-spreading ocean ridges and magma-poor rifted continental margins. At modern hydrothermal vents, serpentinization has been observed to support hydrogen-driven microbial environments including methanotrophic biosystems. An important question is: "Are such bio-systems locally restricted to hydrothermal vents or are they more pervasive, being linked with the exhumation of serpentinized mantle at the seafloor?" Fieldwork sampling of km scale exposures of orogenically exhumed serpentinized mantle in the Alps allows 3D mantle sampling that is not possible at ocean ridges and provides an opportunity to investigate the organic matter in an ophiolite sequence relative to the seafloor. Samples from the fossil Tethyan OCT, exhumed during Alpine collisional orogeny, have been examined for the presence or absence of biomarkers typical of methanotrophy within serpentinized exhumed mantle. Samples from the Totalp unit, Tasna nappe and Platta unit of the Eastern Swiss Alps and Chenaillet in the Western Alps from the Tethyan magma-poor OCT were selected for analysis because they have little Alpine deformation and underwent only low-grade Alpine metamorphism. Hand specimens and cores taken from these locations have been analysed to search for the presence or absence of biomarkers in the serpentinite and its overlying lithologies. Thin sections of samples from these OCT locations reveal multiple serpentinization events and calcification phases. All the lithologies sampled show the presence of hydrocarbons such as n-alkanes, low molecular weight polynuclear aromatic hydrocarbons (PAHs, of mixed petrogenic and pyrogenic source), hopanes, steranes (of marine origin), and branched alkanes (pristane and phytane, non-specific marine origin). The identifiable biomarkers and the isotopic data are consistent with organic matter of a marine origin and do not provide any evidence for a methanotrophic bio-system. It is noteworthy that basement mantle rocks still

  11. Nickel speciation in several serpentine (ultramafic) topsoils via bulk synchrotron-based techniques

    Energy Technology Data Exchange (ETDEWEB)

    Siebecker, Matthew G.; Chaney, Rufus L.; Sparks, Donald L.

    2017-07-01

    Serpentine soils have elevated concentrations of trace metals including nickel, cobalt, and chromium compared to non-serpentine soils. Identifying the nickel bearing minerals allows for prediction of potential mobility of nickel. Synchrotron-based techniques can identify the solid-phase chemical forms of nickel with minimal sample treatment. Element concentrations are known to vary among soil particle sizes in serpentine soils. Sonication is a useful method to physically disperse sand, silt and clay particles in soils. Synchrotron-based techniques and sonication were employed to identify nickel species in discrete particle size fractions in several serpentine (ultramafic) topsoils to better understand solid-phase nickel geochemistry. Nickel commonly resided in primary serpentine parent material such as layered-phyllosilicate and chain-inosilicate minerals and was associated with iron oxides. In the clay fractions, nickel was associated with iron oxides and primary serpentine minerals, such as lizardite. Linear combination fitting (LCF) was used to characterize nickel species. Total metal concentration did not correlate with nickel speciation and is not an indicator of the major nickel species in the soil. Differences in soil texture were related to different nickel speciation for several particle size fractionated samples. A discussion on LCF illustrates the importance of choosing standards based not only on statistical methods such as Target Transformation but also on sample mineralogy and particle size. Results from the F-test (Hamilton test), which is an underutilized tool in the literature for LCF in soils, highlight its usefulness to determine the appropriate number of standards to for LCF. EXAFS shell fitting illustrates that destructive interference commonly found for light and heavy elements in layered double hydroxides and in phyllosilicates also can occur in inosilicate minerals, causing similar structural features and leading to false positive results in

  12. Bringing together evolution on serpentine and polyploidy: spatiotemporal history of the diploid-tetraploid complex of Knautia arvensis (Dipsacaceae.

    Directory of Open Access Journals (Sweden)

    Filip Kolář

    Full Text Available Polyploidization is one of the leading forces in the evolution of land plants, providing opportunities for instant speciation and rapid gain of evolutionary novelties. Highly selective conditions of serpentine environments act as an important evolutionary trigger that can be involved in various speciation processes. Whereas the significance of both edaphic speciation on serpentine and polyploidy is widely acknowledged in plant evolution, the links between polyploid evolution and serpentine differentiation have not yet been examined. To fill this gap, we investigated the evolutionary history of the perennial herb Knautia arvensis (Dipsacaceae, a diploid-tetraploid complex that exhibits an intriguing pattern of eco-geographic differentiation. Using plastid DNA sequencing and AFLP genotyping of 336 previously cytotyped individuals from 40 populations from central Europe, we unravelled the patterns of genetic variation among the cytotypes and the edaphic types. Diploids showed the highest levels of genetic differentiation, likely as a result of long term persistence of several lineages in ecologically distinct refugia and/or independent immigration. Recurrent polyploidization, recorded in one serpentine island, seems to have opened new possibilities for the local serpentine genotype. Unlike diploids, the serpentine tetraploids were able to escape from the serpentine refugium and spread further; this was also attributable to hybridization with the neighbouring non-serpentine tetraploid lineages. The spatiotemporal history of K. arvensis allows tracing the interplay of polyploid evolution and ecological divergence on serpentine, resulting in a complex evolutionary pattern. Isolated serpentine outcrops can act as evolutionary capacitors, preserving distinct karyological and genetic diversity. The serpentine lineages, however, may not represent evolutionary 'dead-ends' but rather dynamic systems with a potential to further influence the surrounding

  13. Turbine airfoil with controlled area cooling arrangement

    Science.gov (United States)

    Liang, George

    2010-04-27

    A gas turbine airfoil (10) includes a serpentine cooling path (32) with a plurality of channels (34,42,44) fluidly interconnected by a plurality of turns (38,40) for cooling the airfoil wall material. A splitter component (50) is positioned within at least one of the channels to bifurcate the channel into a pressure-side channel (46) passing in between the outer wall (28) and the inner wall (30) of the pressure side (24) and a suction-side channel (48) passing in between the outer wall (28) and the inner wall (30) of the suction side (26) longitudinally downstream of an intermediate height (52). The cross-sectional area of the pressure-side channel (46) and suction-side channel (48) are thereby controlled in spite of an increasing cross-sectional area of the airfoil along its longitudinal length, ensuring a sufficiently high mach number to provide a desired degree of cooling throughout the entire length of the airfoil.

  14. Transmission of neutrons in serpentine mixed and ordinary concrete a comparative study

    International Nuclear Information System (INIS)

    Ravishankar, R.; Bhattacharyya, Sarmishtha; Bandyopadhyay, Tapas; Sarkar, P.K.

    2002-01-01

    Full text: In particle accelerator facilities, for radiation shielding, concrete is commonly used for its effectiveness in attenuating neutrons in addition to its good structural and mechanical properties. Neutron attenuation depends largely on the water content in the concrete. Serpentine mixed concrete is reported to retain better water content than ordinary concrete. Experiments have been carried out to compare neutron attenuation properties of Serpentine mixed concrete slabs and ordinary concrete slabs of different thickness. Transmission of neutrons from a 185 GBq Pu-Be neutron source has been studied using NE-213 liquid scintillator detector, along with the associated electronics to discriminate neutron from gamma using pulse shape discrimination techniques. The energy differential neutron spectra transmitted through the concrete slabs and the corresponding dose have been obtained by unfolding the pulse height spectra using the FERDOR-U computer code and proper response matrix data of the NE-213 detector. The neutron transmission factors through both Serpentine and Ordinary concrete slabs have been studied. The results show serpentine mixed concrete slabs can attenuate more neutrons of varying energies compared to ordinary concrete slabs of equal dimensions. From the trend, it has been found out, with the increase in slab thickness, the gain in neutron attenuation increases. This is due to increase in quantity of serpentine with the increase in thickness of, concrete. A Monte Carlo simulation carried out, for theoretical analysis of the results, has been found to be in order

  15. Transmission of neutrons in serpentine mixed and ordinary concrete- a comparative study

    International Nuclear Information System (INIS)

    Ravishankar, R.; Bhattacharyya, Sarmishtha; Bandyopadhyay, Tapas; Sarkar, P. K.

    2002-01-01

    In particle accelerator facilities, for radiation shielding, concrete is commonly used for its effectiveness in attenuating neutrons in addition to its good structural and mechanical properties. Neutron attenuation depends largely on the water content in the concrete. Serpentine mixed concrete is reported to retain better water content than ordinary concrete. Experiments have been carried out to compare neutron attenuation properties of Serpentine mixed concrete slabs and ordinary concrete slabs of different thickness. Transmission of neutrons from a 185 GBq Pu-Be neutron source has been studied using NE-213 liquid scintillator detector, along with the associated electronics to discriminate neutron from gamma using pulse shape discrimination techniques. The energy differential neutron spectra transmitted through the concrete slabs and the corresponding dose have been obtained by unfolding the pulse height spectra using the FERDOR-U computer code and proper response matrix data of the NE-213 detector. The neutron transmission factors through both Serpentine and Ordinary concrete slabs have been studied. The results show serpentine mixed concrete slabs can attenuate more neutrons of varying energies compared to ordinary concrete slabs of equal dimensions. From the trend, it has been found out, with the increase in slab thickness, the gain in neutron attenuation increases. This is due to increase in quantity of serpentine with the increase in thickness of concrete. A Monte Carlo simulation carried out, for theoretical analysis of the results, has been found to be in order

  16. Raman Spectroscopy of Serpentine and Reaction Products at High Pressure Using a Diamond Anvil Cell

    Science.gov (United States)

    Burgess, K.; Zinin, P.; Odake, S.; Fryer, P.; Hellebrand, E.

    2012-12-01

    Serpentine is one of the most abundant hydrous phases in the altered subducting plate, and contributes a large portion of the water flux in subduction zones. Measuring and understanding the structural changes in serpentine with pressure aids our understanding of the processes ongoing in oceanic crust and subduction zones. We have conducted high-pressure/high-temperature experiments on serpentine and its dehydration reaction products using a diamond anvil cell. We used the multifunctional in-situ measurement system equipped with a Raman device and laser heating system at the University of Hawaii. Well-characterized natural serpentinite was used in the study. Pressure was determined using the shift of the fluorescence line of a ruby placed next to the sample. Raman spectra of serpentine were obtained at higher pressures than previously published, up to 15 GPa; the peak shift with pressure fits the model determined by Auzende et al. [2004] at lower pressures. Heating was done at several different pressures up to 20 GPa, and reaction products were identified using Raman. Micro-Raman techniques allow us to determine reaction progress and heterogeneity within natural samples containing olivine and serpentine. Auzende, A-L., I. Daniel, B. Reynard, C. Lemaire, F. Guyot (2004). High-pressure behavior of serpentine minerals: a Raman spectroscopic study. Phys. Chem. Minerals 31 269-277.

  17. Inhibition of calcium carbonate crystal growth by organic additives using the constant composition method in conditions of recirculating cooling circuits

    Science.gov (United States)

    Chhim, Norinda; Kharbachi, Chams; Neveux, Thibaut; Bouteleux, Céline; Teychené, Sébastien; Biscans, Béatrice

    2017-08-01

    The cooling circuits used in power plants are subject to mineral crystallization which can cause scaling on the surfaces of equipment and construction materials reducing their heat exchange efficiency. Precipitated calcium carbonate is the predominant mineral scale commonly observed in cooling systems. Supersaturation is the key parameter controlling the nucleation and growth of calcite in these systems. The present work focuses on the precipitation of calcite using the constant composition method at constant supersaturation, through controlled addition of reactants to a semi-batch crystallizer, in order to maintain constant solution pH. The determination of the thermodynamic driving force (supersaturation) was based on the relevant chemical equilibria, total alkalinity and calculation of the activity coefficients. Calcite crystallization rates were derived from the experiments performed at supersaturation levels similar to those found in industrial station cooling circuits. Several types of seeds particles were added into the aqueous solution to mimic natural river water conditions in terms of suspended particulate matters content, typically: calcite, silica or illite particles. The effect of citric and copolycarboxylic additive inhibitors added to the aqueous solution was studied. The calcium carbonate growth rate was reduced by 38.6% in the presence of the citric additive and a reduction of 92.7% was observed when the copolycarboxylic additive was used under identical experimental conditions. These results are explained by the location of the adsorbed inhibitor at the crystal surface and by the degree of chemical bonding to the surface.

  18. Methane Dynamics in a Tropical Serpentinizing Environment: The Santa Elena Ophiolite, Costa Rica

    Directory of Open Access Journals (Sweden)

    Melitza Crespo-Medina

    2017-05-01

    Full Text Available Uplifted ultramafic rocks represent an important vector for the transfer of carbon and reducing power from the deep subsurface into the biosphere and potentially support microbial life through serpentinization. This process has a strong influence upon the production of hydrogen and methane, which can be subsequently consumed by microbial communities. The Santa Elena Ophiolite (SEO on the northwestern Pacific coast of Costa Rica comprises ~250 km2 of ultramafic rocks and mafic associations. The climatic conditions, consisting of strongly contrasting wet and dry seasons, make the SEO a unique hydrogeological setting, where water-rock reactions are enhanced by large storm events (up to 200 mm in a single storm. Previous work on hyperalkaline spring fluids collected within the SEO has identified the presence of microorganisms potentially involved in hydrogen, methane, and methanol oxidation (such as Hydrogenophaga, Methylobacterium, and Methylibium spp., respectively, as well as the presence of methanogenic Archaea (such as Methanobacterium. Similar organisms have also been documented at other serpentinizing sites, however their functions have not been confirmed. SEO's hyperalkaline springs have elevated methane concentrations, ranging from 145 to 900 μM, in comparison to the background concentrations (<0.3 μM. The presence and potential activity of microorganisms involved in methane cycling in serpentinization-influenced fluids from different sites within the SEO were investigated using molecular, geochemical, and modeling approaches. These results were combined to elucidate the bioenergetically favorable methane production and/or oxidation reactions in this tropical serpentinizing environment. The hyperalkaline springs at SEO contain a greater proportion of Archaea and methanogens than has been detected in any terrestrial serpentinizing system. Archaea involved in methanogenesis and anaerobic methane oxidation accounted from 40 to 90% of total

  19. Geogenic Enrichment of PTEs and the " Serpentine Syndrome"(H. Jenny, 1980). A proxy for soil remediation

    Science.gov (United States)

    Bini, Claudio; Maleci, Laura

    2014-05-01

    Serpentine soils have relatively high concentrations of PTEs (e.g., Co, Cr, Cu, Fe, Ni) but generally low amounts of major nutrients. They often bear a distinctive vegetation, and a frequently-used approach to understanding serpentine ecology and environmental hazard has been the chemical analysis of soils and plants. Long-term studies on aspects of serpentine soils and their vegetation provide results on total concentrations, or on plant-available fractions, of soil elements which counteract ecological conditions. For example, there is evidence of Ni toxicity at Ni-concentration >0.3 mg/L in the soil solution (Johnston and Proctor, 1981). The serpentine vegetation differs from the conterminous non-serpentine areas, being often endemic, and showing macroscopic physionomical characters such as dwarfism, prostrate outcome, glaucescence and glabrescence, leaves stenosis, root shortening (what Jenny, 1980, called "the serpentine syndrome"). Similarly, at microscopic level cytomorphological characteristics of the roots and variations in biochemical parameters such as LPO and phenols have been recorded in serpentine native vegetation (Giuliani et al., 2008). Light microscopy observations showed depressed mitotic activity in the meristematic zone, and consequent reduced root growth (Gabbrielli et al., 1990) The metal content of plants growing on serpentine soils at sites with different microclimatic conditions has been examined by several authors (e.g. Bini et al., 1993; Dinelli and Lombini, 1996) . A preferential Ni distribution in epidermis and sclerenchima has been observed in the stem of Alyssum bertoloni, a well known Ni-accumulator plant (Vergnano Gambi, 1975). The different tolerance mechanisms responsible for plant adaption to high concentrations of PTEs in serpentine soils can be related to the capacity of plants either to limit metal uptake and translocation or to accumulate metals in non toxic forms. The majority of serpentine species (e.g. Silene italica) tend

  20. Hajdu-Cheney syndrome associated with serpentine fibulae and polycystic kidney disease

    International Nuclear Information System (INIS)

    Currarino, Guido

    2009-01-01

    Six patients who presented with craniofacial anomalies, musculoskeletal anomalies including elongated and bowed (serpentine) fibulae, and polycystic kidneys are reported. This association of anomalies is referred to as serpentine fibula polycystic kidney syndrome (SFPKS) and is currently interpreted as a manifestation of Hajdu-Cheney syndrome (HCS). We report a new instance of this association of anomalies and review the clinical and radiographic features of HCS and of the reported cases of SFPKS. (orig.)

  1. Presence of Tritium in the Cooling Circuits of the Reactors G2 and G3; Presence de tritium dans les circuits de refroidissement des reacteurs G2 et G3

    Energy Technology Data Exchange (ETDEWEB)

    Estournel, R [Commissariat a l' Energie Atomique. Centre de Production de Plutonium de Marcoule, 30 - Chusclan (France)

    1962-07-01

    In a reactor of the G 2-G 3 type, tritium can be formed by the neutronic bombardment of many elements present in the core. Tritium was found to be present in the cooling circuits of the reactors G 2 and G 3 in the water coming from the regeneration of the CO{sub 2} dehydrating columns. (author) [French] Dans un reacteur du type G 2 - G 3, le tritium peut etre forme par le bombardement. neutronique de nombreux elements existant dans le c r. La presence de tritium dans les circuits de refroidissement des reacteurs G 2 - G 3 a ete mis en evidence dans l'eau provenant de la regeneration des colonnes de deshydratation du CO{sub 2}. (auteur)

  2. Biogeochemical weathering of serpentinites: An examination of incipient dissolution affecting serpentine soil formation

    International Nuclear Information System (INIS)

    Baumeister, Julie L.; Hausrath, Elisabeth M.; Olsen, Amanda A.; Tschauner, Oliver; Adcock, Christopher T.; Metcalf, Rodney V.

    2015-01-01

    Highlights: • Dissolution of primary minerals is important to porosity generation in serpentinites. • Mineral weathering extent in serpentinites follows the order Fe > Mg > Al rich minerals. • Fe-oxidizing bacteria may mediate Fe-rich primary and serpentine mineral alteration. • Serpentinite weathering is strongly impacted by degree of serpentinization. - Abstract: Serpentinite rocks, high in Mg and trace elements including Ni, Cr, Cd, Co, Cu, and Mn and low in nutrients such as Ca, K, and P, form serpentine soils with similar chemical properties resulting in chemically extreme environments for the biota that grow upon them. The impact of parent material on soil characteristics is most important in young soils, and therefore the incipient weathering of serpentinite rock likely has a strong effect on the development of serpentine soils and ecosystems. Additionally, porosity generation is a crucial process in converting rock into a soil that can support vegetation. Here, the important factors affecting the incipient weathering of serpentinite rock are examined at two sites in the Klamath Mountains, California. Serpentinite-derived soils and serpentinite rock cores were collected in depth profiles from each sampling location. Mineral dissolution in weathered serpentinite samples, determined by scanning electron microscopy, energy dispersive spectrometry, electron microprobe analyses, and synchrotron microXRD, is consistent with the order, from most weathered to least weathered: Fe-rich pyroxene > antigorite > Mg-rich lizardite > Al-rich lizardite. These results suggest that the initial porosity formation within serpentinite rock, impacting the formation of serpentine soil on which vegetation can exist, is strongly affected both by the presence of non-serpentine primary minerals as well as the composition of the serpentine minerals. In particular, the presence of ferrous Fe appears to contribute to greater dissolution, whereas the presence of Al within the

  3. Visual study of air--water mixtures flowing inside serpentine tubes

    International Nuclear Information System (INIS)

    Farukhi, M.N.; Parker, J.D.

    1974-01-01

    Hydrodynamic behavior of air-water mixtures flowing inside serpentine tubes, with bends in the vertical plane, was investigated. Flow visualization was accomplished by injecting dye into the liquid phase and recording the events on color slides and color movies. For certain combinations of gas and liquid flow rates, in the annular type flow regime, ''film inversion'' was observed in the bend as well as in the straight section immediately downstream of the bend. A new flow regime map particularly applicable to two phase flow inside serpentine tubes is presented. (U.S.)

  4. Using MicroFTIR to Map Mineral Distributions in Serpentinizing Systems

    Science.gov (United States)

    Johnson, A.; Kubo, M. D.; Cardace, D.

    2016-12-01

    Serpentinization, the water-rock reaction forming serpentine mineral assemblages from ultramafic precursors, can co-occur with the production of hydrogen, methane, and diverse organic compounds (McCollom and Seewald, 2013), evolving water appropriate for carbonate precipitation, including in ophiolite groundwater flow systems and travertine-producing seeps/springs. Serpentinization is regarded as a geologic process important to the sustainability of the deep biosphere (Schrenk et al., 2013) and the origin of life (Schulte et al., 2006). In this study, we manually polished wafers of ultramafic rocks/associated minerals (serpentinite, peridotite, pyroxenite, dunite; olivine, diopside, serpentine, magnetite), and travertine/constituent minerals (carbonate crusts; calcite, dolomite), and observed mineral boundaries and interfaces using µFTIR analysis in reflection mode. We used a Thermo Nicolet iS50 FTIR spectrometer coupled with a Continuum IR microscope to map minerals/boundaries. We identify, confirm, and document FTIR wavenumber regions linked to serpentinite- and travertine-associated minerals by referencing IR spectra (RRUFF) and aligning with x-ray diffraction. The ultramafic and carbonate samples are from the following field localities: McLaughlin Natural Reserve - a UC research reserve, Lower Lake, CA; Zambales, PH; Ontario, CA; Yellow Dog, MI; Taskesti, TK; Twin Sisters Range, WA; Sharon, MA; Klamath Mountains, CA; Dun Mountain, NZ; and Sussex County, NJ. Our goals are to provide comprehensive µFTIR characterization of mineral profiles important in serpentinites and related rocks, and evaluate the resolving power of µFTIR for the detection of mineral-encapsulated, residual organic compounds from biological activity. We report on µFTIR data for naturally occurring ultramafics and travertines and also estimate the limit of detection for cell membrane components in mineral matrices, impregnating increasing mass proportions of xanthan gum in a peridotite sand

  5. Serpentinization history of the Río Guanajibo serpentinite body, Puerto Rico

    Science.gov (United States)

    Roehrig, Erin E.; Laó-Dávila, Daniel A.; Wolfe, Amy L.

    2015-10-01

    The Río Guanajibo serpentinite body (RGSB) near Mayagüez, Puerto Rico, is part of an ophiolite mélange thrust in an oceanic convergent zone. The aim of this study was to characterize the extent and chronology of serpentinization within this peridotite mass. Mineralogy, microstructures, and veining episodes within the RGSB were characterized using optical microscopy, x-ray diffraction (XRD), scanning electron microscopy (SEM), and structural analyses. This study identified, for the first time, all three serpentine polymorphs (i.e., antigorite, chrysotile, lizardite) in serpentinite samples collected from Puerto Rico. Lizardite, the initial serpentine mineral formed from widespread hydration of olivine, was found throughout serpentinite samples. Chrysotile was the most abundant polymorph observed in sheared serpentinite samples, consistent with conditions favoring low fluid to rock ratios, supersaturation and abundant porosity. Antigorite was observed as a replacement texture in serpentinites that were not exposed to greenschist facies metamorphic conditions, and were frequently found in veins with a shear component. The results indicate that metamorphic conditions do not exclusively dictate polymorph formation. The mineralogy and textures observed within the different vein generations reflect the formation conditions, and deformational mechanisms, that occurred during the serpentinization process; six veining episodes (V1 - V6) were identified and grouped into four stages of serpentinization. Stage one (V1 and V2 type veins) represents the earliest stages of serpentinization and was characterized by microscopic fracture networks that formed as a result of cracking during the initial hydration of olivine under low water/rock ratios. During stage two (V3 and V4 type veins), fibrous crack - seal veins formed to accommodate continued volume expansion, via incremental fracture openings, caused by continued hydration of olivine. The ascension of serpentinite into the

  6. Characterizing and quantifying superparamagnetic magnetite particles in serpentinized mantle peridotite observed in continental ophiolite complexes.

    Science.gov (United States)

    Ortiz, E.; Vento, N. F. R.; Tominaga, M.; Beinlich, A.; Einsle, J. F.; Buisman, I.; Ringe, E.; Schrenk, M. O.; Cardace, D.

    2017-12-01

    Serpentinization of mantle peridotite has been recognized as one of the most important energy factories for the deep biosphere. To better evaluate the habitability of the deep biosphere, it is crucial to understand the link between in situ peridotite serpentinization processes and associated magnetite and hydrogen production. Previous efforts in correlating magnetite and hydrogen production during serpentinization processes are based primarily on laboratory experiments and numerical modeling, being challenged to include the contribution of superparamagnetic-sized magnetites (i.e., extremely fine-grained magnetite, petrographically observed as a "pepper flake" like texture in many natural serpentinized rock samples). To better estimate the abundance of superparamagnetic grains, we conducted frequency-dependent susceptibility magnetic measurements at the Institute of Rock Magnetism on naturally serpentinized rock samples from the Coast Range Ophiolite Microbial Observatory (CROMO) in California, USA and the Atlin Ophiolite (British Columbia). In addition, we conducted multiscale EDS phase mapping, BackScattered Electron (BSE) scanning, FIB-nanotomography and STEM-EELS to identify and quantify the superparamagnetic minerals that contribute to the measured magnetic susceptibility signals in our rock samples. Utilizing a multidisciplinary approach, we aim to improve the estimation of hydrogen production based on the abundance of magnetite, that includes the contribution of superparamagnetic particle size magnetite, to ultimately provide a more accurate estimation of bulk deep-biomass hosted by in situ serpentinization processes.

  7. A stable isotope study of serpentinization in the Fengtien ophiolite, Taiwan

    Energy Technology Data Exchange (ETDEWEB)

    Tzen-Fu Yui; Hsueh-Wen Yeh (Univ. of Hawaii, Honolulu (USA)); Chihming Wang Lee (National Taiwan Univ. (Taiwan))

    1990-05-01

    Detailed H- and O-isotopic studies of serpentinites of Fengtien ophiolite have been made in order to enhance our knowledge on the process of serpentinization. Pseudomorphic lizardites have {delta}{sup 18}O = +3.6{per thousand} and {delta}D = {minus}48 to {minus}49{per thousand}; bladed-mat and foliated antigorites have {delta}{sup 18}O = +3.5 to +5.8{per thousand} and {delta}D = {minus}45 to {minus}69{per thousand}; slickensided antigorites have {delta}{sup 18}O = +4.1 to +4.9{per thousand} and {delta}D = {minus}46 to {minus}50{per thousand}; picrolites have {delta}{sup 18}O = +4.2 to +4.3{per thousand} and {delta}D = {minus}65 to {minus}67{per thousand}; and slickensided chrysotiles have {delta}{sup 18}O = +4.1 to +4.5{per thousand} and {delta}D = {minus}80{per thousand}. It is suggested that lizardite might have formed in an oceanic environment, whereas antigorite and chrysotile have formed in continental environments. These results depict complicated multiple serpentinization processes. Isotopic temperatures calculated using {delta}{sup 18}O values of coexisting fissure-filling minerals range from 325 to 370{degree}C, which are consistent with those derived from phase equilibria involving serpentines. The narrow range of {delta}{sup 18}O and wide range of {delta}D values for antigorite and chrysotile also demonstrate that water/rock ratios during these serpentinizations should not have been high. These Fengtien serpentines fall outside either of the continental domains described by Wenner and Taylor (1973, 1974); and fall within their oceanic domain. We suggest that the domains proposed by Wenner and Taylor (1973, 1974) should be extended and that the terms, especially the continental antigorite and the continental lizardite-chrysotile, should be purely occurrence-descriptive.

  8. Design of conformal cooling for plastic injection moulding by heat transfer simulation

    Directory of Open Access Journals (Sweden)

    Sabrina Marques

    2015-12-01

    Full Text Available The cooling channels of a mold for plastic injection have to be as close as possible to the part geometry in order to ensure fast and homogeneous cooling. However, conventional methods to manufacture cooling channels (drilling can only produce linear holes. Selective laser melting (SLM is an additive manufacturing technique capable to manufacture complex cooling channels (known as conformal cooling. Nevertheless, because of the high costs of SLM the benefits of conformal collings are still not clear. The current work investigates two designs of conformal coolings: i parallel circuit; ii serial circuit. Both coolings are evaluated against to traditional cooling circuits (linear channels by CAE simulation to produce parts of polypropylene. The results show that if the conformal cooling is not properly designed it cannot provide reasonable results. The deformation of the product can be reduced significantly after injection but the cycle time reduced not more than 6%.

  9. Characterization of carbonated serpentine using XPS and TEM

    International Nuclear Information System (INIS)

    Schulze, Roland K.; Hill, Mary Ann; Field, Robert D.; Papin, Pallas A.; Hanrahan, Robert J.; Byler, Darrin D.

    2004-01-01

    With the increasing concentration volume of carbon dioxide in the atmosphere, there has been an increasing interest in carbon dioxide sequestration. One method is to store the carbon dioxide in mineral form, reacting solution dissolved CO 2 to precipitate carbonates. In order to understand whether or not such an endeavor is feasible, the carbonation reaction must first be understood. In this study, the surface of ground serpentine, untreated, heat treated and following a carbonation experiment, has been characterized using X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results indicate that the mechanism for the reaction involves dissolution of the serpentine through the formation of an amorphous phase and subsequent precipitation of magnesite. The rate limiting step appears to be the diffusion of Mg out of the amorphous phase

  10. Fabrication and analysis of awl-shaped serpentine microsprings for large out-of-plane displacement

    International Nuclear Information System (INIS)

    Chou, Hui-Min; Chen, Rongshun; Lin, Meng-Ju

    2015-01-01

    This work investigates a novel awl-shaped serpentine microspring for a suspension structure, with a lower spring constant under the same unit layout area in out-of-plane motion. Using Castigliano’s theorem, the spring constant of the microspring was theoretically derived and simulations were performed using COMSOL Multiphysics to verify the theoretical results. The proposed awl-shaped serpentine microspring was successfully fabricated using silicon-based micromachining. Experiments were conducted to compare the theoretical and numerical results, which were in close agreement. In addition, a parameter of spring constant to layout area ratio (K/A) is defined to be used as the index for comparing spring constants under the same unit area. Accordingly, the awl-shaped serpentine microspring has a lower K/A value than the traditional serpentine microspring with the same total effective length and folds. With a greater taper angle, more folds, a smaller beam width, and lower beam thickness, the awl-shaped serpentine microspring has a smaller K/A value. Using the proposed mathematical model, the spring constants of microsprings of various sizes and geometric structures can be calculated in out-of-plane motion before the microstructure is fabricated. Thus, it saves time when designing a microspring with a proper spring constant. (paper)

  11. Heavy Metal Resistant, Alkalitolerant Bacteria Isolated From Serpentinizing Springs in the Zambales Ophiolite, Philippines

    Science.gov (United States)

    Vallalar, B.; Meyer-Dombard, D. R.; Cardace, D.; Arcilla, C. A.

    2016-12-01

    Serpentinization involves hydrologic alteration of ultramafic mantle rocks containing olivine and pyroxene to produce serpentine minerals. The fluids resulting from this reaction are reduced, extremely depleted in dissolved inorganic carbon, and are highly alkaline with pH values typically exceeding 10. Major byproducts of the serpentinizing reaction include iron oxides, hydrogen, methane, and small amounts of organic molecules that provide chemosynthetic energy for subsurface microbial communities. In addition, weathering of serpentine rocks often produces fluids and sediments that have elevated concentrations of various toxic heavy metals such as chromium, nickel, cobalt, copper, and zinc. Thus, microorganisms inhabiting these unique ecological niches must be adapted to a variety of physicochemical extremes. The purpose of this study is to isolate bacteria that are capable of withstanding extremely high concentrations of multiple heavy metals from serpentine fluid-associated sediments. Fluid and sediment samples for microbial culturing were collected from Manleluag Spring National Park located on the island of Luzon, Philippines. The area is part of the Zambales ophiolite range, and hosts several serpentinizing fluid seeps. Fluid emanating from the source pool of the spring, designated Manleluag 2 (ML2), has a pH of 10.83 and temperature of 34.4 °C. Luria-Bertani agar medium was supplemented with varying concentrations of five trace elements - Cu, Cr, Co, Ni, and Zn. Environmental samples were spread on each of these media and colony forming units were subsequently chosen for isolation. In all, over 20 isolates were obtained from media with concentrations ranging from 25 mg/L - 400 mg/L of each metal. Taxonomic identity of each isolate was determined using 16S rRNA gene sequences. The isolates were then tested for tolerance to alkaline conditions by altering LB medium to pH values of 8, 9, 10, 11, and 12. The majority of strains exhibit growth at the highest p

  12. Cooling tower water circuits with raceways

    International Nuclear Information System (INIS)

    Nicollet, G.

    1981-02-01

    Two physical models built at the National Hydraulics Laboratory in Chatou have led to the determination of the design of the works. This new design economizes 4 to 5 MW on pumping power for each cooling tower [fr

  13. Serpentinization and its implications for life on the early Earth and Mars.

    Science.gov (United States)

    Schulte, Mitch; Blake, David; Hoehler, Tori; McCollom, Thomas

    2006-04-01

    Ophiolites, sections of ocean crust tectonically displaced onto land, offer significant potential to support chemolithoautotrophic life through the provision of energy and reducing power during aqueous alteration of their highly reduced mineralogies. There is substantial chemical disequilibrium between the primary olivine and pyroxene mineralogy of these ophiolites and the fluids circulating through them. This disequilibrium represents a potential source of chemical energy that could sustain life. Moreover, E (h)-pH conditions resulting from rock- water interactions in ultrabasic rocks are conducive to important abiotic processes antecedent to the origin of life. Serpentinization--the reaction of olivine- and pyroxene-rich rocks with water--produces magnetite, hydroxide, and serpentine minerals, and liberates molecular hydrogen, a source of energy and electrons that can be readily utilized by a broad array of chemosynthetic organisms. These systems are viewed as important analogs for potential early ecosystems on both Earth and Mars, where highly reducing mineralogy was likely widespread in an undifferentiated crust. Secondary phases precipitated during serpentinization have the capability to preserve organic or mineral biosignatures. We describe the petrology and mineral chemistry of an ophiolite-hosted cold spring in northern California and propose criteria to aid in the identification of serpentinizing terranes on Mars that have the potential to harbor chemosynthetic life.

  14. Serpentine Robot Model and Gait Design Using Autodesk Inventor and Simulink SimMechanics

    Science.gov (United States)

    Daniel; Iman Alamsyah, Mohammad; Erwin; Tan, Sofyan

    2014-03-01

    The authors introduce gaits of a serpentine robot with linear expansion mechanism where the robot varies its length using joints with three degrees of freedom. The 3D model of the serpentine robot is drawed in Autocad Inventor® and exported to SimMechanics® for straighforward modeling of the kinematics. The gaits are important for robots designed to explore ruins of disasters where the working spaces are very tight. For maximum flexibility of the serpentine robot, we adopted a joint design with three parallel actuators, where the joint is capable of linear movement in the forward axis, and rotational movements around two other axes. The designed linear expansion gaits is calculated for forward movement when the robot is posing straight or turning laterally.

  15. Serpentine Robot Model and Gait Design Using Autodesk Inventor and Simulink SimMechanics

    Directory of Open Access Journals (Sweden)

    Daniel

    2014-03-01

    Full Text Available The authors introduce gaits of a serpentine robot with linear expansion mechanism where the robot varies its length using joints with three degrees of freedom. The 3D model of the serpentine robot is drawed in Autocad Inventor® and exported to SimMechanics® for straighforward modeling of the kinematics. The gaits are important for robots designed to explore ruins of disasters where the working spaces are very tight. For maximum flexibility of the serpentine robot, we adopted a joint design with three parallel actuators, where the joint is capable of linear movement in the forward axis, and rotational movements around two other axes. The designed linear expansion gaits is calculated for forward movement when the robot is posing straight or turning laterally.

  16. Shapeable short circuit resistant capacitor

    Science.gov (United States)

    Taylor, Ralph S.; Myers, John D.; Baney, William J.

    2015-10-06

    A ceramic short circuit resistant capacitor that is bendable and/or shapeable to provide a multiple layer capacitor that is extremely compact and amenable to desirable geometries. The capacitor that exhibits a benign failure mode in which a multitude of discrete failure events result in a gradual loss of capacitance. Each event is a localized event in which localized heating causes an adjacent portion of one or both of the electrodes to vaporize, physically cleaning away electrode material from the failure site. A first metal electrode, a second metal electrode, and a ceramic dielectric layer between the electrodes are thin enough to be formed in a serpentine-arrangement with gaps between the first electrode and the second electrode that allow venting of vaporized electrode material in the event of a benign failure.

  17. Effect of humidity content and direction of the flow of reactant gases on water management in the 4-serpentine and 1-serpentine flow channel in a PEM (proton exchange membrane) fuel cell

    International Nuclear Information System (INIS)

    Khazaee, I.; Sabadbafan, H.

    2016-01-01

    The performance of a PEM (proton exchange membrane) fuel cell depends on design and operating parameters such as relative humidity, operation pressure, and number of channels and direction of the flow of reactant gases. In this study, a three-dimensional, two-phase model has been established to investigate the water management and performance of PEM fuel cell with rectangular geometry and 1-serpentine and 4-serpentine with parallel flow, counter flow and cross flow for hydrogen and oxygen. The numerical simulation was realized with a PEM fuel cell model based on the FLUENT. The active area of each cell is 24.8 cm 2 that its weight is 1300 gr. The material of the gas diffusion layer is carbon clothes, the membrane is nafion117 and the catalyst layer is a plane with 0.004 g cm −2 platinum. Pure hydrogen is used on the anode side and oxygen on the cathode side. Simulation results are obtained for voltage as a function of current density at different humidity. The simulation results are compared with the experimental data, and the agreement is found to be good. The results show that the cell performance at lower voltages increases with increasing humidity in cell with 4-Serpentine flow channel and also in cell with 1-Serpentine flow channel, cell performance at all voltages increases with increasing humidity. In cell with 4-Serpentine and parallel flow channel cell performance is better than counter and cross flow in low voltage and in cell with 1-Serpentine and parallel flow, performance is better than counter and cross flow in high voltage. - Highlights: • Investigation new geometries of a fuel cell. • The effect of geometry on current density, oxygen and water distribution. • The effect of humidity on current density, oxygen and water distribution. • Seeing the interacting and complex electrochemical phenomena.

  18. Malenco Serpentine: proposed as a candidate for "Global Heritage Stone Resource" designation

    Science.gov (United States)

    Primavori, Piero

    2017-04-01

    The Malenco Serpentine (Serpentine of Val Malenco) is the commercial name of a meta-peridotitic geological formation, Jurassic-Lower Cretaceous in age, entirely restricted to the borders of the valley of the same name (Malenco Valley), and geographically located in Sondrio Province, Lombardy Region, North Italy. Geologically speaking, it is part of an ophiolithic suture zone situated at the contact of the Austroalpine and Penninic nappes of the Alps (Rhaetian sector); petrographically, it is the result of a polymetamorphic (both regional and contact) and polytectonic history, with the development of a paragenesis of antigorite + chrysotile + chlorite + magnetite + diopside + olivine + titanolivine ± chromite ± pyrite ± brucite, and other iron and copper sulphurs. Malenco Serpentine extends over an area of approximately 170 km2, with a thickness ranging from 1 to 2 km. Lithological and mineralogical features allow the recognition of three distinct lythotypes: 1) a strongly foliated Serpentine - called Serpentine-schist of Val Malenco, with a regular and penetrative schistosity, which makes it possible to split the rock into very fine sheets ("pioda"); 2) a massive Serpentine, with no remarkable foliation, called with different commercial names (Green Vittoria, Green Mare, Green Torre S. Maria etc.); 3) A Clorithic schist (Val Malenco Ollare Stone), in turn subdivisible into two main types, depending on the predominance of Chlorite or Talc, and well known for their thermal behaviour and historical utilization for the production of stoves and cooking pots. The stone is quarried and processed since Middle Ages, and used in building and urban décor since 1800. Particularly, the splittable Serpentine has totally characterized - and still characterizes - the typology of the roofs and the urban style of the Malenco Valley architecture. "Pioda" is the name given to the roofing elements; initially used only for the local building, they were processed and transported out

  19. Out of the dark: transitional subsurface-to-surface microbial diversity in a terrestrial serpentinizing seep (Manleluag, Pangasinan, the Philippines).

    Science.gov (United States)

    Woycheese, Kristin M; Meyer-Dombard, D'Arcy R; Cardace, Dawn; Argayosa, Anacleto M; Arcilla, Carlo A

    2015-01-01

    In the Zambales ophiolite range, terrestrial serpentinizing fluid seeps host diverse microbial assemblages. The fluids fall within the profile of Ca(2+)-OH(-)-type waters, indicative of active serpentinization, and are low in dissolved inorganic carbon (DIC) (serpentinizing seep ecosystem studies, particularly with regards to tropical biomes.

  20. Replacement of the cooling system of the TRIGA Mainz reactor

    International Nuclear Information System (INIS)

    Menke, H.

    1988-01-01

    The inspection of the reactor facility resulted in a recommendation to install a new heat exchanger and at the same time to separate the primary cooling circuit and the water purification system. Due to possible the deposition of lime and organic matter on the tubes, the heat transfer rate has decreased. In the meantime a rule has been introduced, according to which the pressure in the secondary cooling circuit must be permanently higher than in the primary cooling circuit which prompted the design of a new cooling system. The detail planning was completed in December 1987. In response to the regulatory requirements a motion for a replacement of the cooling system was submitted to the authorities. The start of the procedure is possible a year after the obtaining of the licenses. In the planning of the changes an upgrading of the steady state power to 300 kW is envisioned

  1. Numerical evaluation of various gas and coolant channel designs for high performance liquid-cooled proton exchange membrane fuel cell stacks

    International Nuclear Information System (INIS)

    Sasmito, Agus P.; Kurnia, Jundika C.; Mujumdar, Arun S.

    2012-01-01

    A careful design of gas and coolant channel is essential to ensure high performance and durability of proton exchange membrane (PEM) fuel cell stack. The channel design should allow for good thermal, water and gas management whilst keeping low pressure drop. This study evaluates numerically the performance of various gas and coolant channel designs simultaneously, e.g. parallel, serpentine, oblique-fins, coiled, parallel-serpentine and a novel hybrid parallel-serpentine-oblique-fins designs. The stack performance and local distributions of key parameters are investigated with regards to the thermal, water and gas management. The results indicate that the novel hybrid channel design yields the best performance as it constitutes to a lower pumping power and good thermal, water and gas management as compared to conventional channels. Advantages and limitation of the designs are discussed in the light of present numerical results. Finally, potential application and further improvement of the design are highlighted. -- Highlights: ► We evaluate various gas and coolant channel designs in liquid-cooled PEM fuel cell stack. ► The model considers coupled electrochemistry, channel design and cooling effect simultaneously. ► We propose a novel hybrid channel design. ► The novel hybrid channel design yields the best thermal, water and gas management which is beneficial for long term durability. ► The novel hybrid channel design exhibits the best performance.

  2. Water quality control program in experimental circuits

    International Nuclear Information System (INIS)

    Cegalla, Miriam A.

    1996-01-01

    The Water Quality Control Program of the Experimental Circuits visualizes studying the water chemistry of the cooling in the primary and secondary circuits, monitoring the corrosion of the systems and studying the mechanism of the corrosion products transport in the systems. (author)

  3. Modeling Late-State Serpentinization on Enceladus and Implications for Methane-Utilizing Microbial Metabolisms

    Science.gov (United States)

    Hart, R.; Cardace, D.

    2017-12-01

    Modeling investigations of Enceladus and other icy-satellites have included physicochemical properties (Sohl et al., 2010; Glein et al., 2015; Neveu et al., 2015), geophysical prospects of serpentinization (Malamud and Prialnik, 2016; Vance et al., 2016), and aqueous geochemistry across different antifreeze fluid-rock scenarios (Neveu et al., 2017). To more effectively evaluate the habitability of Enceladus, in the context of recent observations (Waite et al., 2017), we model the potential bioenergetic pathways that would be thermodynamically favorable at the interface of hydrothermal water-rock reactions resulting from late stage serpentinization (>90% serpentinized), hypothesized on Enceladus. Building on previous geochemical model outputs of Enceladus (Neveu et al., 2017), and bioenergetic modeling (as in Amend and Shock, 2001; Cardace et al., 2015), we present a model of late stage serpentinization possible at the water-rock interface of Enceladus, and report changing activities of chemical species related to methane utilization by microbes over the course of serpentinization using the Geochemist's Workbench REACT code [modified Extended Debye-Hückel (Helgeson, 1969) using the thermodynamic database of SUPCRT92 (Johnson et al., 1992)]. Using a model protolith speculated to exist at Enceladus's water-rock boundary, constrained by extraterrestrial analog analytical data for subsurface serpentinites of the Coast Range Ophiolite (Lower Lake, CA, USA) mélange rocks, we deduce evolving habitability conditions as the model protolith reacts with feasible, though hypothetical, planetary ocean chemistries (from Glien et al., 2015, and Neveu et al., 2017). Major components of modeled oceans, Na-Cl, Mg-Cl, and Ca-Cl, show shifts in the feasibility of CO2-CH4-H2 driven microbial habitability, occurring early in the reaction progress, with methanogenesis being bioenergetically favored. Methanotrophy was favored late in the reaction progress of some Na-Cl systems and in the

  4. Moessbauer Study of Serpentine Minerals in the Ultramafic Body of Tehuitzingo, Southern Mexico

    International Nuclear Information System (INIS)

    Gonzalez-Mancera, G.; Ortega-Gutierrez, F.; Nava, N. E.; Arriola, H. S.

    2003-01-01

    Serpentine 'polymorph' minerals (chrysotile, lizardite, and antigorite) are hydrous Mg-Fe silicates that commonly form serpentine rock (serpentinite) by hydration of olivine-pyroxene peridotites from the mantle of the Earth. During the complex geologic history of orogenic belts, the redox and hydration state of the mantle changes, and olivine and pyroxenes are replaced by serpentine group minerals during tectonic deformation and uplift. Unfortunately, modern microanalysis of minerals by electron probe does not distinguish the oxidation state of iron, and it has to be assumed or estimated by precise methods, such as Moessbauer spectrometry. The studied samples were collected in the Xayacatlan Formation of the Tehuitzingo area, State of Puebla, within the Paleozoic Acatlan Complex. The original mantle peridotite was completely converted to serpentinite, with secondary crystallization of Fe-Mg oxides, calcsilicates, and carbonates. The three serpentine 'polymorphs' were identified in the studied samples, although with a clear predominance of the high-temperature member antigorite, which was preliminary determined by optical petrography, X-ray diffraction, electron probe, and scanning electron microscopy. Microprobe total iron content in most specimens was +3 substitution at the tetrahedral site may also occur according to some Moessbauer studies. This paper studied the iron valence state and its position in serpentine minerals of the Tehuitzingo ultramafic body using Moessbauer techniques. The analyses in most samples detected one doublet, compatible with Fe +2 in octahedral coordination, but only two specimens displayed two doublets corresponding to Fe +2 and Fe +3 in octahedral coordination. Doublets corresponding to Fe +3 in tetrahedral sites were not found. The parameters obtained for all the Fe +2 doublets are similar (QS=2.76±0.08 mm/sec, and IS=1.12±0.01), whereas the ratio Fe +3 /Fe +2 (0-0.34) has a strong tendency for iron to be in a divalent state. This

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

    Science.gov (United States)

    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.

  6. Design optimization of electric vehicle battery cooling plates for thermal performance

    Science.gov (United States)

    Jarrett, Anthony; Kim, Il Yong

    The performance of high-energy battery cells utilized in electric vehicles (EVs) is greatly improved by adequate temperature control. An efficient thermal management system is also desirable to avoid diverting excessive power from the primary vehicle functions. In a battery cell stack, cooling can be provided by including cooling plates: thin metal fabrications which include one or more internal channels through which a coolant is pumped. Heat is conducted from the battery cells into the cooling plate, and transported away by the coolant. The operating characteristics of the cooling plate are determined in part by the geometry of the channel; its route, width, length, etc. In this study, a serpentine-channel cooling plate is modeled parametrically and its characteristics assessed using computational fluid dynamics (CFD). Objective functions of pressure drop, average temperature, and temperature uniformity are defined and numerical optimization is carried out by allowing the channel width and position to vary. The optimization results indicate that a single design can satisfy both pressure and average temperature objectives, but at the expense of temperature uniformity.

  7. Flow in Rotating Serpentine Coolant Passages With Skewed Trip Strips

    Science.gov (United States)

    Tse, David G.N.; Steuber, Gary

    1996-01-01

    Laser velocimetry was utilized to map the velocity field in serpentine turbine blade cooling passages with skewed trip strips. The measurements were obtained at Reynolds and Rotation numbers of 25,000 and 0.24 to assess the influence of trips, passage curvature and Coriolis force on the flow field. The interaction of the secondary flows induced by skewed trips with the passage rotation produces a swirling vortex and a corner recirculation zone. With trips skewed at +45 deg, the secondary flows remain unaltered as the cross-flow proceeds from the passage to the turn. However, the flow characteristics at these locations differ when trips are skewed at -45 deg. Changes in the flow structure are expected to augment heat transfer, in agreement with the heat transfer measurements of Johnson, et al. The present results show that trips are skewed at -45 deg in the outward flow passage and trips are skewed at +45 deg in the inward flow passage maximize heat transfer. Details of the present measurements were related to the heat transfer measurements of Johnson, et al. to relate fluid flow and heat transfer measurements.

  8. Water treatments in semi-closed cooling circuits and their impact on the quality of effluents discharged by CERN

    CERN Document Server

    Santos Leite Cima Gomes, J; Kleiner, S

    2008-01-01

    The main goal of this study is to assess the impact of the discharges of the semi-closed water cooling circuits of CERN (European Center for Nuclear Research) on the overall quality of CERN's effluents, taking as guidelines the international legislation supported on the knowledge of the water systems of CERN. In order to reach this goal, a thorough analysis of the functioning of the semi-closed water cooling systems of CERN's particle accelerators was done, as well as, an analysis of the treatment that is done to prevent the proliferation of bacteria such as Legionella. The products used in these water treatments, as well as their impact, were also researched. In addition, a study of the applicable regulation to CERN's effluent was done. This study considered not only the regulation of France and Switzerland (CERN's host states) but also the international regulation from the European community, Portugal Germany, Spain, U.S. and Canada, having in view a better understanding of the limit values of the parameter...

  9. Exploration of the Role of Heat Activation in Enhancing Serpentine Carbon Sequestration Reactions

    International Nuclear Information System (INIS)

    McKelvy, M.J.; Chizmeshya, A.V.G.; Diefenbacher, J.; Bearat, H.; Wolf, G.

    2005-01-01

    As compared with other candidate carbon sequestration technologies, mineral carbonation offers the unique advantage of permanent disposal via geologically stable and environmentally benign carbonates. The primary challenge is the development of an economically viable process. Enhancing feedstock carbonation reactivity is key. Heat activation dramatically enhances aqueous serpentine carbonation reactivity. Although the present process is too expensive to implement, the materials characteristics and mechanisms that enhance carbonation are of keen interest for further reducing cost. Simultaneous thermogravimetric and differential thermal analysis (TGA/DTA) of the serpentine mineral lizardite was used to isolate a series of heat-activated materials as a function of residual hydroxide content at progressively higher temperatures. Their structure and composition are evaluated via TGA/DTA, X-ray powder diffraction (including phase analysis), and infrared analysis. The meta-serpentine materials that were observed to form ranged from those with longer range ordering, consistent with diffuse stage-2 like interlamellar order, to an amorphous component that preferentially forms at higher temperatures. The aqueous carbonation reaction process was investigated for representative materials via in situ synchrotron X-ray diffraction. Magnesite was observed to form directly at 15 MPa CO 2 and at temperatures ranging from 100 to 125 C. Carbonation reactivity is generally correlated with the extent of meta-serpentine formation and structural disorder.

  10. Stable isotope compositions of serpentinite seamounts in the Mariana forearc: Serpentinization processes, fluid sources and sulfur metasomatism

    Science.gov (United States)

    Alt, J.C.; Shanks, Wayne C.

    2006-01-01

    The Mariana and Izu-Bonin arcs in the western Pacific are characterized by serpentinite seamounts in the forearc that provide unique windows into the mantle wedge. We present stable isotope (O, H, S, and C) data for serpentinites from Conical seamount in the Mariana forearc and S isotope data for Torishima seamount in the Izu-Bonin forearc in order to understand the compositions of fluids and temperatures of serpentinization in the mantle wedge, and to investigate the transport of sulfur from the slab to the mantle wedge. Six serpentine mineral separates have a restricted range of ??18O (6.5-8.5???). Antigorite separates have ??D values of -29.5??? to -45.5??? that reflect serpentinization within the mantle wedge whereas chrysotile has low ??D values (-51.8??? to -84.0???) as the result of re-equilibration with fluids at low temperatures. Fractionation of oxygen isotopes between serpentine and magnetite indicate serpentinization temperatures of 300-375 ??C. Two late cross-fiber chrysotile veins have higher ??18O values of 8.9??? to 10.8??? and formed at lower temperatures (as low as ???100 ??C). Aqueous fluids in equilibrium with serpentine at 300-375 ??C had ??18O = 6.5-9??? and ??D = -4??? to -26???, consistent with sediment dehydration reactions at temperatures arc lavas. ?? 2006 Elsevier B.V. All rights reserved.

  11. The H2/CH4 ratio during serpentinization cannot reliably identify biological signatures

    OpenAIRE

    Huang, Ruifang; Sun, Weidong; Liu, Jinzhong; Ding, Xing; Peng, Shaobang; Zhan, Wenhuan

    2016-01-01

    Serpentinization potentially contributes to the origin and evolution of life during early history of the Earth. Serpentinization produces molecular hydrogen (H2) that can be utilized by microorganisms to gain metabolic energy. Methane can be formed through reactions between molecular hydrogen and oxidized carbon (e.g., carbon dioxide) or through biotic processes. A simple criterion, the H2/CH4 ratio, has been proposed to differentiate abiotic from biotic methane, with values approximately lar...

  12. Fossil evidence for serpentinization fluids fueling chemosynthetic assemblages.

    Science.gov (United States)

    Lartaud, Franck; Little, Crispin T S; de Rafelis, Marc; Bayon, Germain; Dyment, Jerome; Ildefonse, Benoit; Gressier, Vincent; Fouquet, Yves; Gaill, Françoise; Le Bris, Nadine

    2011-05-10

    Among the deep-sea hydrothermal vent sites discovered in the past 30 years, Lost City on the Mid-Atlantic Ridge (MAR) is remarkable both for its alkaline fluids derived from mantle rock serpentinization and the spectacular seafloor carbonate chimneys precipitated from these fluids. Despite high concentrations of reduced chemicals in the fluids, this unique example of a serpentinite-hosted hydrothermal system currently lacks chemosynthetic assemblages dominated by large animals typical of high-temperature vent sites. Here we report abundant specimens of chemosymbiotic mussels, associated with gastropods and chemosymbiotic clams, in approximately 100 kyr old Lost City-like carbonates from the MAR close to the Rainbow site (36 °N). Our finding shows that serpentinization-related fluids, unaffected by high-temperature hydrothermal circulation, can occur on-axis and are able to sustain high-biomass communities. The widespread occurrence of seafloor ultramafic rocks linked to likely long-range dispersion of vent species therefore offers considerably more ecospace for chemosynthetic fauna in the oceans than previously supposed.

  13. Biofilm formation and potential for iron cycling in serpentinization-influenced groundwater of the Zambales and Coast Range ophiolites.

    Science.gov (United States)

    Meyer-Dombard, D'Arcy R; Casar, Caitlin P; Simon, Alexander G; Cardace, Dawn; Schrenk, Matthew O; Arcilla, Carlo A

    2018-05-01

    Terrestrial serpentinizing systems harbor microbial subsurface life. Passive or active microbially mediated iron transformations at alkaline conditions in deep biosphere serpentinizing ecosystems are understudied. We explore these processes in the Zambales (Philippines) and Coast Range (CA, USA) ophiolites, and associated surface ecosystems by probing the relevance of samples acquired at the surface to in situ, subsurface ecosystems, and the nature of microbe-mineral associations in the subsurface. In this pilot study, we use microcosm experiments and batch culturing directed at iron redox transformations to confirm thermodynamically based predictions that iron transformations may be important in subsurface serpentinizing ecosystems. Biofilms formed on rock cores from the Zambales ophiolite on surface and in-pit associations, confirming that organisms from serpentinizing systems can form biofilms in subsurface environments. Analysis by XPS and FTIR confirmed that enrichment culturing utilizing ferric iron growth substrates produced reduced, magnetic solids containing siderite, spinels, and FeO minerals. Microcosms and enrichment cultures supported organisms whose near relatives participate in iron redox transformations. Further, a potential 'principal' microbial community common to solid samples in serpentinizing systems was identified. These results indicate collectively that iron redox transformations should be more thoroughly and universally considered when assessing the function of terrestrial subsurface ecosystems driven by serpentinization.

  14. Smart Cooling Controlled System Exploiting Photovoltaic Renewable Energy Systems

    Directory of Open Access Journals (Sweden)

    Ahmad Atieh

    2018-03-01

    Full Text Available A smart cooling system to control the ambient temperature of a premise in Amman, Jordan, is investigated and implemented. The premise holds 650 people and has 14 air conditioners with the cooling capacity ranging from 3 to 5 ton refrigerant (TR each. The control of the cooling system includes implementing different electronics circuits that are used to sense the ambient temperature and humidity, count the number of people in the premise and then turn ON/OFF certain air conditioner(s. The data collected by different electronic circuits are fed wirelessly to a microcontroller, which decides which air conditioner will be turned ON/OFF, its location and its desired set cooling temperature. The cooling system is integrated with an on-grid solar photovoltaic energy system to minimize the operational cost of the overall cooling system.

  15. Weak Serpentine-bearing Fault Zones: laboratory evidence and implications for the activity of of oceanic detachments

    Science.gov (United States)

    Tesei, T.; Harbord, C. W. A.; Paola, N.; Collettini, C.; Viti, C.

    2017-12-01

    Serpentinites are major constituents of oceanic lithosphere shear zones located at slow-spreading margins, transform plate boundaries and obduction complexes. Geological and geophysical evidence suggests that these shear zones are inherently weak and, therefore, studies of serpentine friction are of paramount importance to constrain the strength of oceanic faults. However, laboratory friction experiments give a wide range of friction values for serpentine, which are not conclusive to explain the observed fault weakness. These variable results may arise from the difficulties to accurately characterize the mineralogical composition of serpentinite rocks and, hence, from the lack of pure monomineralic reference samples. Here we present laboratory experiments performed on a suite of serpentine samples, whose mineralogical composition was accurately characterized from the hand specimen down to the nanoscale. We observe that the main, low temperature polymorphs components of ocean-floor retrograde serpentinites (e.g. lizardite, chrysotile and polygonal serpentine) exhibit friction coefficients, µ reported, over a range of pressure and temperature conditions. We applied the frictional reactivation theory based on our experimental result to serpentine-bearing oceanic detachments. We show that detachments may slip until they rotate to very shallow dips 15°, as documented along some Atlantic detachments, accommodating large amounts of extension before being abandoned.

  16. Geochemical models of metasomatism in ultramafic systems: Serpentinization, rodingitization, and sea floor carbonate chimney precipitation

    Science.gov (United States)

    Palandri, J.L.; Reed, M.H.

    2004-01-01

    In a series of water-rock reaction simulations, we assess the processes of serpentinization of harzburgite and related calcium metasomatism resulting in rodingite-type alteration, and seafloor carbonate chimney precipitation. At temperatures from 25 to 300??C (P = 10 to 100 bar), using either fresh water or seawater, serpentinization simulations produce an assemblage commonly observed in natural systems, dominated by serpentine, magnetite, and brucite. The reacted waters in the simulations show similar trends in composition with decreasing water-rock ratios, becoming hyper-alkaline and strongly reducing, with increased dissolved calcium. At 25??C and w/r less than ???32, conditions are sufficiently reducing to yield H2 gas, nickel-iron alloy and native copper. Hyperalkalinity results from OH- production by olivine and pyroxene dissolution in the absence of counterbalancing OH- consumption by alteration mineral precipitation except at very high pH; at moderate pH there are no stable calcium minerals and only a small amount of chlorite forms, limited by aluminum, thus allowing Mg2+ and Ca2+ to accumulate in the aqueous phase in exchange for H+. The reducing conditions result from oxidation of ferrous iron in olivine and pyroxene to ferric iron in magnetite. Trace metals are computed to be nearly insoluble below 300??C, except for mercury, for which high pH stabilizes aqueous and gaseous Hg??. In serpentinization by seawater at 300??C, Ag, Au, Pd, and Pt may approach ore-forming concentrations in sulfide complexes. Simulated mixing of the fluid derived from serpentinization with cold seawater produces a mineral assemblage dominated by calcite, similar to recently discovered submarine, ultramafic rock-hosted, carbonate mineral deposits precipitating at hydrothermal vents. Simulated reaction of gabbroic or basaltic rocks with the hyperalkaline calcium- and aluminum-rich fluid produced during serpentinization at 300??C yields rodingite-type mineral assemblages, including

  17. The Correlation Between Porosity, Density and Degree of Serpentinization in Ophiolites from Point Sal, California: Implications for Strength of Oceanic Lithosphere

    Science.gov (United States)

    Karrasch, A. K.; Farough, A.; Lowell, R. P.

    2017-12-01

    Hydration and serpentinization of oceanic lithosphere influences its strength and behavior under stress. Serpentine content is the limiting factor in deformation and the correlation between crustal strength and the degree of serpentinization is not linear. Escartin et al., [2001] shows that the presence of only 10% serpentine results in a nominally non-dilatant mode of brittle deformation and reduces the strength of peridotites dramatically. In this study, we measured density and porosity of ophiolite samples from Point Sal, CA that had various degrees of serpentinization. The densities ranged between 2500- 3000 kg/m3 and porosities ranged between 2.1-4.8%. The degree of serpentinization was estimated from mineralogical analysis, and these data were combined with that of 4 other samples analyzed by Farough et al., [2016], which were obtained from various localities. The degree of serpentinization varied between 0.6 and 40%. We found that degree of serpentinization was inversely correlated with density with a slope of 7.25 (kg/m3)/%. Using Horen et al., [1996] models, estimated P-wave velocity of the samples ranged between 6.75-7.90 km/s and S-wave velocity ranged between 3.58-4.35 km/s. There were no distinguishable difference in the results between olivine-rich or pyroxene-rich samples. These results, along with correlations to strength and deformation style, can be used as a reference for mechanical properties of the crust at depth, analysis of deep drill cores and to estimate the rate of weakening of the oceanic crust after the onset of serpentinization reactions.

  18. Analysis of the steady state hydraulic behaviour of the ITER blanket cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Di Maio, P.A., E-mail: pietroalessandro.dimaio@unipa.it [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Dell’Orco, G.; Furmanek, A. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Garitta, S. [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Merola, M.; Mitteau, R.; Raffray, R. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Spagnuolo, G.A.; Vallone, E. [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy)

    2015-10-15

    Highlights: • Nominal steady state hydraulic behaviour of ITER blanket standard sector cooling system has been investigated. • Numerical simulations have been run adopting a qualified thermal-hydraulic system code. • Hydraulic characteristic functions and coolant mass flow rates, velocities and pressure drops have been assessed. • Most of the considered circuits are able to effectively cool blanket modules, meeting ITER requirements. - Abstract: The blanket system is the ITER reactor component devoted to providing a physical boundary for plasma transients and contributing to thermal and nuclear shielding of vacuum vessel, magnets and external components. It is expected to be subjected to significant heat loads under nominal conditions and its cooling system has to ensure an adequate cooling, preventing any risk of critical heat flux occurrence while complying with pressure drop limits. At the University of Palermo a study has been performed, in cooperation with the ITER Organization, to investigate the steady state hydraulic behaviour of the ITER blanket standard sector cooling system. A theoretical–computational approach based on the finite volume method has been followed, adopting the RELAP5 system code. Finite volume models of the most critical blanket cooling circuits have been set-up, realistically simulating the coolant flow domain. The steady state hydraulic behaviour of each cooling circuit has been investigated, determining its hydraulic characteristic function and assessing the spatial distribution of coolant mass flow rates, velocities and pressure drops under reference nominal conditions. Results obtained have indicated that the investigated cooling circuits are able to provide an effective cooling to blanket modules, generally meeting ITER requirements in term of pressure drop and velocity distribution, except for a couple of circuits that are being revised.

  19. Lower Crustal Strength Controls on Melting and Serpentinization at Magma-Poor Margins: Potential Implications for the South Atlantic

    Science.gov (United States)

    Ros, Elena; Pérez-Gussinyé, Marta; Araújo, Mario; Thoaldo Romeiro, Marco; Andrés-Martínez, Miguel; Morgan, Jason P.

    2017-12-01

    Rifted continental margins may present a predominantly magmatic continent-ocean transition (COT), or one characterized by large exposures of serpentinized mantle. In this study we use numerical modeling to show the importance of the lower crustal strength in controlling the amount and onset of melting and serpentinization during rifting. We propose that the relative timing between both events controls the nature of the COT. Numerical experiments for half-extension velocities serpentinized mantle underlain by some magmatic products. In contrast, a weak lower crust promotes margins with a gentle crustal tapering, small faults dipping both ocean- and landward and small syn-rift subsidence. Their COT is predominantly magmatic at any ultra-slow extension velocity and perhaps underlain by some serpentinized mantle. These margins can also be either symmetric or asymmetric. Our models predict that magmatic underplating mostly underlies the wide margin at weak asymmetric conjugates, whereas the wide margin is mainly underlain by serpentinized mantle at strong asymmetric margins. Based on this conceptual template, we propose different natures for the COTs in the South Atlantic.

  20. Three-dimensional flow measurements induced from serpentine plasma actuators in quiescent air

    International Nuclear Information System (INIS)

    Durscher, R J; Roy, S

    2012-01-01

    This paper presents three-dimensional flow measurements performed on a dielectric barrier discharge (DBD) actuator with the electrodes in a serpentine design. Such a configuration induces a local pinching and a local spreading of the fluid as one follows along the span of the actuator. In this work two different variations on the serpentine configuration are evaluated: one constructed from patterned circular arcs and one from patterned rectangles. The influence of applied voltage is studied for the former case. To quantify these effects stereo particle image velocimetry (PIV) is used to generate time averaged, spatially resolved measurements of the detailed flow structure. The three components of the velocity vector are measured along spanwise and streamwise cuts. These slices are then reconstructed to provide a three-dimensional view of the induced flow field. The results for the induced flow fields are also compared with stereo-PIV measurements made on a standard linear DBD actuator. A truly three-dimensional induced flow field was observed as a result of the serpentine configuration. These designs could be beneficial for rapid mixing of the local fluid. (paper)

  1. Analysis of Passive Mixing in a Serpentine Microchannel with Sinusoidal Side Walls

    Directory of Open Access Journals (Sweden)

    Muhammad Usman Javaid

    2017-12-01

    Full Text Available Sample mixing is difficult in microfluidic devices because of laminar flow. Micromixers are designed to ensure the optimal use of miniaturized devices. The present study aims to design a chaotic-advection-based passive micromixer with enhanced mixing efficiency. A serpentine-shaped microchannel with sinusoidal side walls was designed, and three cases, with amplitude to wavelength (A/λ ratios of 0.1, 0.15, and 0.2 were investigated. Numerical simulations were conducted using the Navier–Stokes equations, to determine the flow field. The flow was then coupled with the convection–diffusion equation to obtain the species concentration distribution. The mixing performance of sinusoidal walled channels was compared with that of a simple serpentine channel for Reynolds numbers ranging from 0.1 to 50. Secondary flows were observed at high Reynolds numbers that mixed the fluid streams. These flows were dominant in the proposed sinusoidal walled channels, thereby showing better mixing performance than the simple serpentine channel at similar or less mixing cost. Higher mixing efficiency was obtained by increasing the A/λ ratio.

  2. Strategy for the Operation of Cooling Towers with variable Speed Fans

    CERN Document Server

    Iñigo-Golfín, J

    2001-01-01

    Within the SPS Cooling Water Project at CERN aimed at the reduction of water consumption, this primary open cooling loop will be closed and all the primary cooling circuit components will be upgraded to the new required duty and brought to the necessary safety and operability standards. In particular the tower fans will be fitted with variable frequency drives to replace the existing two speed motors. This paper presents a study to optimize the operation of SPS cooling towers taking into account outdoor conditions (wet and dry bulb temperatures) and the entirety of the primary circuit in which they will operate.

  3. Design, Fabrication and Integration of a NaK-Cooled Circuit

    International Nuclear Information System (INIS)

    Garber, Anne; Godfroy, Thomas

    2006-01-01

    The Early Flight Fission Test Facilities (EFF-TF) team has been tasked by the NASA Marshall Space Flight Center Nuclear Systems Office to design, fabricate, and test an actively pumped alkali metal flow circuit. The system, which was originally designed for use with a eutectic mixture of sodium potassium (NaK), was redesigned for use with lithium. Due to a shift in focus, it is once again being prepared for use with NaK. Changes made to the actively pumped, high temperature circuit include the replacement of the expansion reservoir, addition of remotely operated valves, and modification of the support table. Basic circuit components include: reactor segment, NaK to gas heat exchanger, electromagnetic (EM) liquid metal pump, load/drain reservoir, expansion reservoir, instrumentation, and a spill reservoir. A 37-pin partial-array core (pin and flow path dimensions are the same as those in a full design) was selected for fabrication and test. This paper summarizes the integration and preparations for the fill of the pumped NaK circuit. (authors)

  4. Serpentinization and the Formation of H2 and CH4 on Celestial Bodies (Planets, Moons, Comets).

    Science.gov (United States)

    Holm, N G; Oze, C; Mousis, O; Waite, J H; Guilbert-Lepoutre, A

    2015-07-01

    Serpentinization involves the hydrolysis and transformation of primary ferromagnesian minerals such as olivine ((Mg,Fe)2SiO4) and pyroxenes ((Mg,Fe)SiO3) to produce H2-rich fluids and a variety of secondary minerals over a wide range of environmental conditions. The continual and elevated production of H2 is capable of reducing carbon, thus initiating an inorganic pathway to produce organic compounds. The production of H2 and H2-dependent CH4 in serpentinization systems has received significant interdisciplinary interest, especially with regard to the abiotic synthesis of organic compounds and the origins and maintenance of life in Earth's lithosphere and elsewhere in the Universe. Here, serpentinization with an emphasis on the formation of H2 and CH4 are reviewed within the context of the mineralogy, temperature/pressure, and fluid/gas chemistry present in planetary environments. Whether deep in Earth's interior or in Kuiper Belt Objects in space, serpentinization is a feasible process to invoke as a means of producing astrobiologically indispensable H2 capable of reducing carbon to organic compounds.

  5. Mantle Serpentinization near the Central Mariana Trench Constrained by Ocean Bottom Surface Wave Observations

    Science.gov (United States)

    Cai, C.; Wiens, D. A.; Lizarralde, D.; Eimer, M. O.; Shen, W.

    2017-12-01

    We investigate the crustal and uppermost mantle seismic structure across the Mariana trench by jointly inverting Rayleigh wave phase and group velocities from ambient noise and longer period phase velocities from Helmholtz tomography of teleseismic waveforms. We use data from a temporary deployment in 2012-2013, consisting of 7 island-based stations and 20 broadband ocean bottom seismographs, as well as data from the USGS Northern Mariana Islands Seismograph Network. To avoid any potential bias from the starting model, we use a Bayesian Monte-Carlo algorithm to invert for the azimuthally-averaged SV-wave velocity at each node. This method also allows us to apply prior constraints on crustal thickness and other parameters in a systematic way, and to derive formal estimates of velocity uncertainty. The results show the development of a low velocity zone within the incoming plate beginning about 80 km seaward of the trench axis, consistent with the onset of bending faults from bathymetry and earthquake locations. The maximum depth of the velocity anomaly increases towards the trench, and extends to about 30 km below the seafloor. The low velocities persist after the plate is subducted, as a 20-30 km thick low velocity layer with a somewhat smaller velocity reduction is imaged along the top of the slab beneath the forearc. An extremely low velocity zone is observed beneath the serpentine seamounts in the outer forearc, consistent with 40% serpentinization in the forearc mantle wedge. Azimuthal anisotropy results show trench parallel fast axis within the incoming plate at uppermost mantle depth (2%-4% anisotropy). All these observations suggest the velocity reduction in the incoming plate prior to subduction results from both serpentinized normal faults and water-filled cracks. Water is expelled from the cracks early in subduction, causing a modest increase in the velocity of the subducting mantle, and moves upward and causes serpentinization of the outer forearc

  6. An improved water cooled nuclear reactor and pressuriser assembly

    International Nuclear Information System (INIS)

    Gardner, F.J.; Strong, R.

    1991-01-01

    A water cooled nuclear reactor is described which comprises a reactor core, a primary water coolant circuit and a pressuriser arranged as an integral unit in a pressure vessel. The pressure vessel is divided into an upper and a lower chamber by a casing. The reactor core and primary water coolant circuit are arranged in the lower chamber and the pressuriser is arranged in the upper chamber. A plurality of spray pipes interconnect a steam space of the pressuriser with the downcomer of the primary water coolant circuit below a heat exchanger. A plurality of surge ports interconnect a water space of the pressuriser with the primary water coolant circuit. The surge ports have hydraulic diodes so that there is a low flow resistance for water from the water space of the pressuriser to the primary water coolant circuit and high flow resistance in the opposite direction. The spray pipes provide a desuperheating spray of cooled water into the pressuriser during positive volume surges of the primary water coolant. The pressuriser arrangement may also be applied to integral water cooled reactors with separate pressurisers and to dispersed pressurised water reactors. The surge ports also allow water to flow by gravity to the core in an emergency. (author)

  7. Stable isotope compositions of serpentinite seamounts in the Mariana forearc: Serpentinization processes, fluid sources and sulfur metasomatism

    Science.gov (United States)

    Alt, J.C.; Shanks, Wayne C.

    2006-01-01

    The Mariana and Izu-Bonin arcs in the western Pacific are characterized by serpentinite seamounts in the forearc that provide unique windows into the mantle wedge. We present stable isotope (O, H, S, and C) data for serpentinites from Conical seamount in the Mariana forearc and S isotope data for Torishima seamount in the Izu-Bonin forearc in order to understand the compositions of fluids and temperatures of serpentinization in the mantle wedge, and to investigate the transport of sulfur from the slab to the mantle wedge. Six serpentine mineral separates have a restricted range of ??18O (6.5-8.5???). Antigorite separates have ??D values of -29.5??? to -45.5??? that reflect serpentinization within the mantle wedge whereas chrysotile has low ??D values (-51.8??? to -84.0???) as the result of re-equilibration with fluids at low temperatures. Fractionation of oxygen isotopes between serpentine and magnetite indicate serpentinization temperatures of 300-375 ??C. Two late cross-fiber chrysotile veins have higher ??18O values of 8.9??? to 10.8??? and formed at lower temperatures (as low as ???100 ??C). Aqueous fluids in equilibrium with serpentine at 300-375 ??C had ??18O = 6.5-9??? and ??D = -4??? to -26???, consistent with sediment dehydration reactions at temperatures aragonite veins in metabasalt and siltstone clasts within the serpentinite flows have ??18O = 16.7-24.5???, consistent with the serpentinizing fluids at temperatures <250 ??C. ??13C values of 0.1-2.5??? suggest a source in subducting carbonate sediments. The ??34S values of sulfide in serpentinites on Conical Seamount (-6.7??? to 9.8???) result from metasomatism through variable reduction of aqueous sulfate (??34S = 14???) derived from slab sediments. Despite sulfur metasomatism, serpentinites have low sulfur contents (generally < 164 ppm) that reflect the highly depleted nature of the mantle wedge. The serpentinites are mostly enriched in 34S (median ??34Ssulfide = 4.5???), consistent with a 34S

  8. Air-cooled fast discharge resistors for ITER magnets

    International Nuclear Information System (INIS)

    Tanchuk, Victor; Grigoriev, Sergey; Lokiev, Vladimir; Roshal, Alexander; Song, Inho; Buzykin, Oleg

    2011-01-01

    The ITER superconducting magnets will store up to 50 GJ of magnetic energy per operation cycle. In case of coil quench the energy stored in the coils must be extracted rapidly with a time constant from 7.5 to 14 s. It will be achieved by fast discharge resistors (FDR) normally bridged by circuit breakers and inserted in series with the superconducting coils. The fast discharge of the coils results practically in adiabatic heating of the resistive elements up to 200-300 deg. C. The resistors need to be cooled to the initial temperature over 6-8 h. Natural air circulation is proposed as a cooling method. In order to simulate the temperature response of the resistors to energy released in the resistive plates and to demonstrate their cooling capability within the required time by natural air circulation the numerical model of the resistor cooling circuit has been developed. As the calculations have shown, the developed FDR cooling system based on cooling by natural air circulation is capable of providing the required temperature operation regime of FDRs, but the supply channels are to be optimized so that the cooling time does not exceed the permissible one.

  9. Water removal characteristics of parallel serpentine channels

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, K.; Zhou, B.; Quan, P. [Windsor Univ., ON (Canada). Dept. of Mechanical, Automotive and Materials Engineering

    2005-07-01

    A study was conducted in which the liquid water behaviours in parallel serpentine channels with manifolds on the cathode side of a proton exchange membrane (PEM) fuel cell stack were examined. A 3-dimensional, unsteady two-phase flow model within the commercial computational fluid dynamics software package FLUENT was used. Membrane electrode assemblies (MEA) were placed on different sides in the numerical analysis. Several water management issues were identified for this type of fuel cell stack by examining the flow behaviours of liquid water and airflow velocity fields. It was shown that water in the outflow manifold could be blocked by air streams from the gas flow channels, with water flowing continuously into the outflow manifold. It was also shown that the pressure drop along all the unit cells can never increase or decrease at the same pace. Water which adheres to the end wall of both the inlet and outlet manifolds is difficult to remove. It was suggested that faster water drainage can be achieved by keeping the MEA side of the gas flow channels close to the outlet of the outflow manifold. It was also suggested that the collecting and separating effect at the serpentine gas flow channels could improve the water drainage. 8 refs., 10 figs.

  10. Alternative Design Concepts for Multi-Circuit HTS Link Systems

    CERN Document Server

    Ballarino, A

    2011-01-01

    Superconducting cables for power transmission usually contain two conductors for DC application, or three conductors for AC, with high voltage insulation. In contrast, for some applications related to accelerators it is convenient to transfer high currents via superconducting links feeding a number of circuits at relatively low voltage, of the order of a kilovolt, over distances of up to a few hundred meters. For power transmission applications based on cooling via sub-cooled liquid nitrogen, suitable HTS conductors are only available in the form of tape, and a multi-layer variant can be envisaged for the multi-circuit links. However, where cooling to temperatures of the order of 20 K is feasible, MgB2 conductor, available in the form of both tape and wire, can also be envisaged and in the latter case used to assemble round cables. There are, therefore, two distinct topologies - based on the use of wires or tapes - that can be envisaged for use in applications to multi-circuit link systems. In this paper the ...

  11. Unusual metabolic diversity of hyperalkaliphilic microbial communities associated with subterranean serpentinization at The Cedars.

    Science.gov (United States)

    Suzuki, Shino; Ishii, Shun'ichi; Hoshino, Tatsuhiko; Rietze, Amanda; Tenney, Aaron; Morrill, Penny L; Inagaki, Fumio; Kuenen, J Gijs; Nealson, Kenneth H

    2017-11-01

    Water from The Cedars springs that discharge from serpentinized ultramafic rocks feature highly basic (pH=~12), highly reducing (E h serpentinizing system, was dominated by several bacterial taxa from the phyla OD1 ('Parcubacteria') and Chloroflexi. Members of the GPS1 community had, for the most part, the smallest genomes reported for their respective taxa, and encoded only archaeal (A-type) ATP synthases or no ATP synthases at all. Furthermore, none of the members encoded respiration-related genes and some of the members also did not encode key biosynthesis-related genes. In contrast, BS5, fed by shallow water, appears to have a community driven by hydrogen metabolism and was dominated by a diverse group of Proteobacteria similar to those seen in many terrestrial serpentinization sites. Our findings indicated that the harsh ultrabasic geological setting supported unexpectedly diverse microbial metabolic strategies and that the deep-water-fed springs supported a community that was remarkable in its unusual metagenomic and genomic constitution.

  12. Solution of multiple circuits of steam cycle HTR system

    International Nuclear Information System (INIS)

    Li, Fu; Wang, Dengying; Hao, Chen; Zheng, Yanhua

    2014-01-01

    In order to analyze the dynamic operation performance and safety characteristics of the steam cycle high temperature gas cooled reactor (HTR) systems, it is necessary to find the solution of the whole HTR systems with all coupled circuits, including the primary circuit, the secondary circuit, and the residual heat removal system (RHRS). Considering that those circuits have their own individual fluidity and characteristics, some existing code packages for independent circuits themselves have been developed, for example THEMRIX and TINTE code for the primary circuit of the pebble bed reactor, BLAST for once through steam generator. To solve the coupled steam cycle HTR systems, a feasible way is to develop coupling method to integrate these independent code packages. This paper presents several coupling methods, e.g. the equivalent component method between the primary circuit and steam generator which reflect the close coupling relationship, the overlapping domain decomposition method between the primary circuit and the passive RHRS which reflects the loose coupling relationship. Through this way, the whole steam cycle HTR system with multiple circuits can be easily and efficiently solved by integration of several existing code packages. Based on this methodology, a code package TINTE–BLAST–RHRS was developed. Using this code package, some operation performance of HTR–PM was analyzed, such as the start-up process of the plant, and the depressurized loss of forced cooling accident when different number of residual heat removal trains is operated

  13. Microbial diversity in The Cedars, an ultrabasic, ultrareducing, and low salinity serpentinizing ecosystem.

    Science.gov (United States)

    Suzuki, Shino; Ishii, Shun'ichi; Wu, Angela; Cheung, Andrea; Tenney, Aaron; Wanger, Greg; Kuenen, J Gijs; Nealson, Kenneth H

    2013-09-17

    The Cedars, in coastal northern California, is an active site of peridotite serpentinization. The spring waters that emerge from this system feature very high pH, low redox potential, and low ionic concentrations, making it an exceptionally challenging environment for life. We report a multiyear, culture-independent geomicrobiological study of three springs at The Cedars that differ with respect to the nature of the groundwater feeding them. Within each spring, both geochemical properties and microbial diversity in all three domains of life remained stable over a 3-y period, with multiple samples each year. Between the three springs, however, the microbial communities showed considerable differences that were strongly correlated with the source of the serpentinizing groundwater. In the spring fed solely by deep groundwater, phylum Chloroflexi, class Clostridia, and candidate division OD1 were the major taxa with one phylotype in Euryarchaeota. Less-abundant phylotypes include several minor members from other candidate divisions and one phylotype that was an outlier of candidate division OP3. In the springs fed by the mixture of deep and shallow groundwater, organisms close to the Hydrogenophaga within Betaproteobacteria dominated and coexisted with the deep groundwater community members. The shallow groundwater community thus appears to be similar to those described in other terrestrial serpentinizing sites, whereas the deep community is distinctly different from any other previously described terrestrial serpentinizing community. These unique communities have the potential to yield important insights into the development and survival of life in these early-earth analog environments.

  14. Suitability of Co as an alloy material for components of the primary circuit of HTR reactors

    International Nuclear Information System (INIS)

    Iniotakis, N.

    1977-02-01

    For high temperature reactors it is of interest if Co-alloys could be used for the different components of the primary cooling circuit. It has been investigated in detail to what amount the Co-60 created by neutron activation of Co-59 contained in the material of the components could possibly contribute to the contamination of the primary cooling circuit of the reactor. The result of these investigations is compared with the contamination of the cooling circuit by fission and activation products like Co-137, Cs-134, Ag-11om etc. For pebble bed reactors with an OTTO-type fuel management it could be shown that there is no limitation for the use of cobalt in alloys for materials of the components in the primary cooling circuit. The only boundary condition is that the local Thermal Flux at the position of the components should be less than phisub(th) 7 n/cm 2 . sec. (orig.) [de

  15. Repairing the deteriorated thermal insulation in the serpentine - moderator tank - SLCD assemblies

    International Nuclear Information System (INIS)

    Gyongyosi, Tiberiu

    2004-01-01

    Deterioration during operation of the thermal insulation at the upper serpentines in the serpentine assembly in the moderator tank of SLCD (the system of localising the failed fuel) can create problems when one scans the fuel channels in case of failure of one of the ventilated air refrigerator in the rooms of the LAC 10 reactor. Recovering the thermal insulation is absolutely necessary but it is difficult to execute because the loading operation with the granulated layer of diatomaceous filtering agent must be effected directly on the moderator tank after some 24 h from the reactor shut down. The paper presents two possible methods of repairing together with the necessary technological facilities

  16. A theoretical study of the fast-neutron attenuation in Ghanaian serpentine shields

    International Nuclear Information System (INIS)

    Akaho, E.H.K.; Anim-Sampong, S.

    1994-01-01

    Theoretical calculations were done to determine the suitability of local serpentine rocks for shielding fast neutrons. A coupled neutron-gamma library of 25 energy groups, IRAN3.LIB developed for ANISN/PC was used to generate nuclear data for the tested shields. Calculations were carried out assuming a P 3 scattering order for spherical geometry with S 6 angular quadrature. From the trends of attenuation and computer factors such as relaxation length and transmission there is the indication that the shielding properties of the local shields are better than the foreign serpentine shields used in this study. They are slightly inferior to ordinary concrete employed in shielding power reactors. (author). 9 refs.; 5 tabs.; 5 figs

  17. A three-dimensional model of PEM fuel cells with serpentine flow channels

    International Nuclear Information System (INIS)

    Nguyen, P.T.; Berning, T.; Bang, M.; Djilali, N.

    2003-01-01

    A three-dimensional computational model of PEM fuel cell with serpentine flow field channels is presented in this paper. This model presents a comprehensive account for all important transport phenomena in fuel cell such as heat transfer, mass transfer, electrode kinetics, and potential fields in the membrane and gas diffusion layers. A new approach of solving for the potential losses across the cell was also developed in this model. The dependency of local current density on oxygen concentration and activation overpotential is fully addressed in this model. The computational domain consists of serpentine gas flow channels, porous gas diffusion layers, catalyst layers, and a membrane. Results obtained from this model are in good agreement with experimental results. (author)

  18. Iron transformations during low temperature alteration of variably serpentinized rocks from the Samail ophiolite, Oman

    Science.gov (United States)

    Mayhew, Lisa E.; Ellison, Eric T.; Miller, Hannah M.; Kelemen, Peter B.; Templeton, Alexis S.

    2018-02-01

    Partially serpentinized peridotites in the Samail ophiolite in the Sultanate of Oman currently undergo low temperature alteration and hydration both at shallow levels, with water recently in contact with the atmosphere, and at depth, with anoxic, reducing fluids. However, it is unclear how changes in the distribution and oxidation state of Fe are driving the production of energy-rich gases such as hydrogen and methane detected in peridotite catchments. We track the Fe transformations in a suite of outcrop samples representing a subset of the spectrum of least to most altered end-members of the Oman peridotites. We use microscale mineralogical and geochemical analyses including QEMSCAN, Raman spectroscopy, synchrotron radiation X-ray fluorescence (XRF) mapping, and electron microprobe wavelength dispersive spectroscopy. The less-altered peridotites possess a diversity of Fe-bearing phases including relict primary minerals (e.g. olivine, pyroxene, chromite) and secondary phases (e.g. serpentine and brucite). Raman spectroscopy and electron microprobe data (Si/(Mg + Fe)) indicate that much of the serpentine is significantly intergrown with brucite on the sub-micron scale. These data also indicate that the Fe content of the brucite ranges from 10 to 20 wt% FeO. The mineral assemblage of the highly reacted rocks is less diverse, dominated by serpentine and carbonate while olivine and brucite are absent. Magnetite is relatively rare and mainly associated with chromite. Goethite and hematite, both Fe(III)-hydroxides, were also identified in the highly altered rocks. Whole rock chemical analyses reflect these mineralogical differences and show that Fe in the partially serpentinized samples is on average more reduced (∼0.40-0.55 Fe3+/FeTotal) than Fe in the highly reacted rocks (∼0.85-0.90 Fe3+/FeTotal). We propose that olivine, brucite, chromite and, perhaps, serpentine in the less-altered peridotites act as reactive phases during low temperature alteration of the Oman

  19. Modeling of Nonlinear Marine Cooling Systems with Closed Circuit Flow

    DEFF Research Database (Denmark)

    Hansen, Michael; Stoustrup, Jakob; Bendtsen, Jan Dimon

    2011-01-01

    We consider the problem of constructing a mathematical model for a specific type of marine cooling system. The system in question is used for cooling the main engine and main engine auxiliary components, such as diesel generators, turbo chargers and main engine air coolers for certain classes...

  20. Application of k0-based NAA for multielement determination in serpentines and associated minerals

    International Nuclear Information System (INIS)

    Nagendra Kumar, P.V.; S.V. University, Tirupati; Suresh Kumar, N.; King Fahad Specialist Hospital, Dammam; Acharya, R.; Krishna Reddy, L.; Reddy, A.V.R.

    2014-01-01

    The k 0 -based neutron activation analysis method was applied for multielement determination in black and yellow serpentines along with two associated minerals namely altered and unaltered dolomites and intrusive rock dolerite, obtained from the asbestos mines of Cuddapah basin, Andhra Pradesh, India. Concentrations of 20 elements were determined and they were used to predict the process of formation of fibrous chrysotile asbestos. Majority of elements as well as REEs reveal the contribution of elements from both dolerite and dolomite during the process of contact metamorphism in forming the mineral serpentine. (author)

  1. Quantum-Circuit Refrigerator

    Science.gov (United States)

    MöTtöNen, Mikko; Tan, Kuan Y.; Masuda, Shumpei; Partanen, Matti; Lake, Russell E.; Govenius, Joonas; Silveri, Matti; Grabert, Hermann

    Quantum technology holds great potential in providing revolutionizing practical applications. However, fast and precise cooling of the functional quantum degrees of freedom on demand remains a major challenge in many solid-state implementations, such as superconducting circuits. We demonstrate direct cooling of a superconducting resonator mode using voltage-controllable quantum tunneling of electrons in a nanoscale refrigerator. In our first experiments on this type of a quantum-circuit refrigerator, we measure the drop in the mode temperature by electron thermometry at a resistor which is coupled to the resonator mode through ohmic losses. To eliminate unwanted dissipation, we remove the probe resistor and directly observe the power spectrum of the resonator output in agreement with the so-called P(E) theory. We also demonstrate in microwave reflection experiments that the internal quality factor of the resonator can be tuned by orders of magnitude. In the future, our refrigerator can be integrated with different quantum electric devices, potentially enhancing their performance. For example, it may prove useful in the initialization of superconducting quantum bits and in dissipation-assisted quantum annealing. We acknowledge European Research Council Grant SINGLEOUT (278117) and QUESS (681311) for funding.

  2. Micro-coolers fabricated as a component in an integrated circuit

    International Nuclear Information System (INIS)

    Glover, James; Oxley, Chris H; Khalid, Ata; Cumming, David; Stephen, Alex; Dunn, Geoff

    2015-01-01

    The packing density and power capacity of integrated electronics is increasing resulting in higher thermal flux densities. Improved thermal management techniques are required and one approach is to include thermoelectric coolers as part of the integrated circuit. An analysis will be described showing that the supporting substrate will have a large influence on the cooling capacity of the thermoelectric cooler. In particular, for materials with a low ZT figure of merit (for example gallium arsenide (GaAs) based compounds) the substrate will have to be substantially thinned to obtain cooling, which may preclude the use of thermoelectric coolers, for example, as part of a GaAs based integrated circuit. Further, using experimental techniques to measure only the small positive cooling temperature difference (ΔT) between the anode (T h ) and the cathode (T c ) contacts can be misinterpreted as cooling when in fact it is heating. (paper)

  3. Low temperature dissolution creep induced B-type olivine fabric during serpentinization and deformation in mantle wedge

    Science.gov (United States)

    Liu, W.; Zhang, J.

    2017-12-01

    The B-type olivine fabric (i.e., the [010]ol axes subnormal to foliation and the [001]ol axes subparallel to the lineation) has been regarded as an important olivine fabric for interpreting global trench-parallel S-wave polarization in fore-arc regions. However, strong serpentinization and cold temperature environment in the mantle wedge should inhibit development of the B-type olivine fabric that requires high temperature to activate solid-state plastic deformation. Here we report fabrics of olivine and antigorite generated at low temperatures (300-370 oC) during serpentinization in a fossil mantle wedge of the Val Malenco area, Central Alps. Olivine in the serpentine matrix develops a pronounced B-type fabric, while antigorite in the same matrix displays a strong crystallographic orientation (CPO) with the (001) and the [010] subparallel to foliation and lineation, respectively. The following evidence leads to the conclusion that the B-type olivine fabric is resulted from dissolution creep assisted by grain boundaries sliding (GBS) and grain rotation, rather than solid-state plastic deformation: (1) serpentinization took place at low temperatures and a fluid-enriched environment, ideal for dissolution-precipitation creep; (2) the voids and zigzag boundaries along the interface between antigorite and olivine suggest a fluid dissolution reaction; (3) the primary coarse olivine develops a nearly random fabric, indicating the B-type fabrics in the fine-grained olivine can't be inherited fabrics. These results document for the first time the B-type olivine CPO formed by dissolution creep at low temperatures during serpentinization and provide a mechanism to reconcile petrofabric observations with geophysical observations of trench parallel fast S-wave seismic anisotropy in fore-arc mantle wedge regions.

  4. Time-resolved x-ray diffraction analysis of the experimental dehydration of serpentine at high pressure

    International Nuclear Information System (INIS)

    Inoue, Toru; Yoshimi, Isamu; Yamada, Akihiro; Kikegawa, Takumi

    2009-01-01

    Time-resolved, in situ X-ray diffraction analysis was used to determine the dehydration rate and kinetics of serpentine during experimental dehydration at high pressures. The capsule used comprises a diamond sleeve fitted with Au or Pt lids in order to provide high-quality, time-resolved X-ray diffraction data. Antigorite quickly dehydrated to enstatite + forsterite + fluid within 2 h at 650degC below ∼6 GPa. Avrami modeling of the results and SEM observations of the partially dehydrated sample revealed that the nucleation rate was quite high for enstatite but low for forsterite, showing incubation periods of ∼10 min before appearing. The crystallization of these minerals is controlled largely by the composition of the fluid generated from serpentine dehydration. The dehydration boundary determined below 6 GPa in the present study is consistent with the results of previous phase equilibrium studies. This study indicates that serpentine in a subducting slab dehydrates rapidly below 6 GPa when the slab intersects the dehydration boundary conditions. (author)

  5. Physiological and genomic features of highly alkaliphilic hydrogen-utilizing Betaproteobacteria from a continental serpentinizing site.

    Science.gov (United States)

    Suzuki, Shino; Kuenen, J Gijs; Schipper, Kira; van der Velde, Suzanne; Ishii, Shun'ichi; Wu, Angela; Sorokin, Dimitry Y; Tenney, Aaron; Meng, XianYing; Morrill, Penny L; Kamagata, Yoichi; Muyzer, Gerard; Nealson, Kenneth H

    2014-05-21

    Serpentinization, or the aqueous alteration of ultramafic rocks, results in challenging environments for life in continental sites due to the combination of extremely high pH, low salinity and lack of obvious electron acceptors and carbon sources. Nevertheless, certain Betaproteobacteria have been frequently observed in such environments. Here we describe physiological and genomic features of three related Betaproteobacterial strains isolated from highly alkaline (pH 11.6) serpentinizing springs at The Cedars, California. All three strains are obligate alkaliphiles with an optimum for growth at pH 11 and are capable of autotrophic growth with hydrogen, calcium carbonate and oxygen. The three strains exhibit differences, however, regarding the utilization of organic carbon and electron acceptors. Their global distribution and physiological, genomic and transcriptomic characteristics indicate that the strains are adapted to the alkaline and calcium-rich environments represented by the terrestrial serpentinizing ecosystems. We propose placing these strains in a new genus 'Serpentinomonas'.

  6. Cooling device for leaking fluid from a centrifugal pump

    International Nuclear Information System (INIS)

    Raymond, J.R.; Thomson, C.I.

    1978-01-01

    The patented device consists of an integrated heat exchanger in a centrifugal primary cooling circuit pump whose purpose is to cool the coolant medium which leaks along the pump shaft so that the shaft seals are not damaged. The cooling water passes through spirally arranged banks of tubes round the shaft, with baffle plates to direct the leaking coolant. (JIW)

  7. Simulation study of air and water cooled photovoltaic panel using ANSYS

    Science.gov (United States)

    Syafiqah, Z.; Amin, N. A. M.; Irwan, Y. M.; Majid, M. S. A.; Aziz, N. A.

    2017-10-01

    Demand for alternative energy is growing due to decrease of fossil fuels sources. One of the promising and popular renewable energy technology is a photovoltaic (PV) technology. During the actual operation of PV cells, only around 15% of solar irradiance is converted to electricity, while the rest is converted into heat. The electrical efficiency decreases with the increment in PV panel’s temperature. This electrical energy is referring to the open-circuit voltage (Voc), short-circuit current (Isc) and output power generate. This paper examines and discusses the PV panel with water and air cooling system. The air cooling system was installed at the back of PV panel while water cooling system at front surface. The analyses of both cooling systems were done by using ANSYS CFX and PSPICE software. The highest temperature of PV panel without cooling system is 66.3 °C. There is a decrement of 19.2% and 53.2% in temperature with the air and water cooling system applied to PV panel.

  8. Dimethylamine as a Replacement for Ammonia Dosing in the Secondary Circuit of an Advanced Gas-Cooled Reactor (AGR) Power Station

    International Nuclear Information System (INIS)

    Armstrong, C.; Mitchell, M.; Bull, A.; Quirk, G.P.; Rudge, A.

    2012-09-01

    Increasing flow resistance observed over recent years within the helical once-through boilers in the four Advanced Gas-Cooled Reactors (AGRs) at Hartlepool and Heysham 1 Power stations have reduced boiler performance, resulting in reductions in feedwater flow, steam temperatures, power output and the need to carry out periodic chemical cleaning. The root cause is believed to be the development of magnetite deposits with high flow impedance in the 9%Cr evaporator section of the boiler tubing. To prevent continued increases in boiler flow resistance, dimethylamine is being trialled, in one of the four affected units, as a replacement to the conventional ammonia dosing. Dimethylamine increases the pH at temperature around the secondary circuit and, based on full scale boiler rig simulations, is expected to reduce iron transport and prevent flow resistance increases within the evaporator section of the boiler. The dimethylamine plant trial commenced in January 2011 and is ongoing. The feedwater concentration of dimethylamine has been increased progressively towards a final target value of 900 μg kg -1 and its effect on iron transport and boiler pressure loss is being closely monitored. The high steam temperatures (>500 deg. C) of the secondary circuit lead to some decomposition of dimethylamine, which is being carefully monitored at various locations around the circuit. The decomposition products identified with dimethylamine dosing include ammonia, methylamine, formic acid, carbon dioxide and, as yet, unidentified neutral organic species. The effect of dimethylamine dosing on iron transport, boiler pressure drops and its decomposition behaviour around the secondary circuit during the plant trial will be presented in this paper. (authors)

  9. Two phase cooling for superconducting magnets

    International Nuclear Information System (INIS)

    Eberhard, P.H.; Gibson, G.A.; Green, M.A.; Ross, R.R.; Smits, R.G.

    1986-01-01

    Comments on the use of two phase helium in a closed circuit tubular cooling system and some results obtained with the TPC superconducting magnet are given. Theoretical arguments and experimental evidence are given against a previously suggested method to determine helium two phase flow regimes. Two methods to reduce pressure in the magnet cooling tubes during quenches are discussed; 1) lowering the density of helium in the magnet cooling tubes and 2) proper location of pressure relief valves. Some techniques used to protect the refrigerator from too much cold return gas are also mentioned

  10. Thermo-hydraulic analysis of the cool-down of the EDIPO test facility

    Science.gov (United States)

    Lewandowska, Monika; Bagnasco, Maurizio

    2011-09-01

    The first cool-down of the EDIPO (European DIPOle) test facility is foreseen to take place in 2011 by means of the existing 1.2 kW cryoplant at EPFL-CRPP Villigen. In this work, the thermo-hydraulic analysis of the EDIPO cool-down is performed in order both to assess the its duration and to optimize the procedure. The cool-down is driven by the helium flowing in both the outer cooling channel and in the windings connected hydraulically in parallel. We take into account limitations due to the pressure drop in the cooling circuit and the refrigerator capacity as well as heat conduction in the iron yoke. Two schemes of the hydraulic cooling circuit in the EDIPO windings are studied (coils connected in series and coils connected in parallel). The analysis is performed by means of an analytical model complemented by and numerical model. The results indicate that the cool-down to 5 K can be achieved in about 12 days.

  11. Thermo-hydraulic Analysis of a Water-cooled Printed Circuit Heat Exchanger in a Small-scale Nitrogen Loop

    International Nuclear Information System (INIS)

    Kim, Chan Soo; Hong, Sung Deok; Kim, Min Hwan; Shim, Jaesool; Lee, Gyung Dong

    2013-01-01

    The development of high-temperature heat exchangers is very important because of its higher operation temperature and pressure than those of common light water reactors and industrial process plants. In particular, the intermediate heat exchanger is a key-challenged high temperature component in a Very High Temperature gas-cooled Reactor (VHTR). A printed circuit heat exchanger is one of the candidates for an intermediate heat exchanger in a VHTR. The printed circuit heat exchanger (PCHE) was developed and commercialized by HEATRIC. The compactness is better than any other heat exchanger types, because its core matrices are fabricated by diffusion bonding with photo-chemically etched micro-channels. Various tests and analysis have been performed to verify the performance of PCHE. The thermal stress analysis of the high temperature PCHE is necessary to endure the extremely operation condition of IHX. In this study, the thermo-hydraulic analysis for the laboratory-scale PCHE is performed to provide the input data for the boundary conditions of a structural analysis. The results from the first-principal calculation are compared with those from computational fluid dynamics code analysis. COMSOL 4.3a analysis is successfully performed at the uniform pressure drop condition in a set of flow channel stacks. The heat-exchanged region concentrated to the nitrogen inlet cause the uniform mass velocity distribution in the channels, therefore there is little difference between two analytical results

  12. Serpentinization-Influenced Groundwater Harbors Extremely Low Diversity Microbial Communities Adapted to High pH.

    Science.gov (United States)

    Twing, Katrina I; Brazelton, William J; Kubo, Michael D Y; Hyer, Alex J; Cardace, Dawn; Hoehler, Tori M; McCollom, Tom M; Schrenk, Matthew O

    2017-01-01

    Serpentinization is a widespread geochemical process associated with aqueous alteration of ultramafic rocks that produces abundant reductants (H 2 and CH 4 ) for life to exploit, but also potentially challenging conditions, including high pH, limited availability of terminal electron acceptors, and low concentrations of inorganic carbon. As a consequence, past studies of serpentinites have reported low cellular abundances and limited microbial diversity. Establishment of the Coast Range Ophiolite Microbial Observatory (California, U.S.A.) allowed a comparison of microbial communities and physicochemical parameters directly within serpentinization-influenced subsurface aquifers. Samples collected from seven wells were subjected to a range of analyses, including solute and gas chemistry, microbial diversity by 16S rRNA gene sequencing, and metabolic potential by shotgun metagenomics, in an attempt to elucidate what factors drive microbial activities in serpentinite habitats. This study describes the first comprehensive interdisciplinary analysis of microbial communities in hyperalkaline groundwater directly accessed by boreholes into serpentinite rocks. Several environmental factors, including pH, methane, and carbon monoxide, were strongly associated with the predominant subsurface microbial communities. A single operational taxonomic unit (OTU) of Betaproteobacteria and a few OTUs of Clostridia were the almost exclusive inhabitants of fluids exhibiting the most serpentinized character. Metagenomes from these extreme samples contained abundant sequences encoding proteins associated with hydrogen metabolism, carbon monoxide oxidation, carbon fixation, and acetogenesis. Metabolic pathways encoded by Clostridia and Betaproteobacteria, in particular, are likely to play important roles in the ecosystems of serpentinizing groundwater. These data provide a basis for further biogeochemical studies of key processes in serpentinite subsurface environments.

  13. Atmospheric wet-type cooling tower with antifreeze system

    International Nuclear Information System (INIS)

    Coic, P.

    1985-01-01

    The cooling tower has air inlets at its base, a network of pipes which distributes the air to be cooled above the packing, and valves to isolate a part of the network. It includes also a bypass circuit, provided with means to control the flow rate fraction which is by-passed [fr

  14. The constructional design of cooling water discharge structures on German rivers

    International Nuclear Information System (INIS)

    Geldner, P.; Zimmermann, C.

    1975-11-01

    The present compilation of structures for discharging cooling water from power stations into rivers is an attempt to make evident developments in the constructional design of such structures and to give reasons for special structure shapes. A complete collection of all structures built in Germany, however, is difficult to realize because of the large number of power stations. For conventionally heated power stations therefore only a selection was made, while nuclear power stations in operation or under construction could almost completely be taken into account. For want of sufficient quantities of water for river water cooling, projected power stations are now almost exclusively designed for closed-circuit cooling so that the required discharge structures for elutrition water from the cooling towers as well as for the emergency and secondary cooling circuits have to be designed only for small amounts of water. (orig./HP) [de

  15. Serpentinization of abyssal peridotites from the MARK area, Mid-Atlantic Ridge: Sulfur geochemistry and reaction modeling

    Science.gov (United States)

    Alt, J.C.; Shanks, Wayne C.

    2003-01-01

    The opaque mineralogy and the contents and isotope compositions of sulfur in serpentinized peridotites from the MARK (Mid-Atlantic Ridge, Kane Fracture Zone) area were examined to understand the conditions of serpentinization and evaluate this process as a sink for seawater sulfur. The serpentinites contain a sulfur-rich secondary mineral assemblage and have high sulfur contents (up to 1 wt.%) and elevated ??34Ssulfide (3.7 to 12.7???). Geochemical reaction modeling indicates that seawater-peridotite interaction at 300 to 400??C alone cannot account for both the high sulfur contents and high ??34Ssulfide. These require a multistage reaction with leaching of sulfide from subjacent gabbro during higher temperature (???400??C) reactions with seawater and subsequent deposition of sulfide during serpentinization of peridotite at ???300??C. Serpentinization produces highly reducing conditions and significant amounts of H2 and results in the partial reduction of seawater carbonate to methane. The latter is documented by formation of carbonate veins enriched in 13C (up to 4.5???) at temperatures above 250??C. Although different processes produce variable sulfur isotope effects in other oceanic serpentinites, sulfur is consistently added to abyssal peridotites during serpentinization. Data for serpentinites drilled and dredged from oceanic crust and from ophiolites indicate that oceanic peridotites are a sink for up to 0.4 to 6.0 ?? 1012 g seawater S yr-1. This is comparable to sulfur exchange that occurs in hydrothermal systems in mafic oceanic crust at midocean ridges and on ridge flanks and amounts to 2 to 30% of the riverine sulfate source and sedimentary sulfide sink in the oceans. The high concentrations and modified isotope compositions of sulfur in serpentinites could be important for mantle metasomatism during subduction of crust generated at slow spreading rates. ?? 2003 Elsevier Science Ltd.

  16. Deformation associated to exhumation of serpentinized mantle rocks in a fossil Ocean Continent Transition: The Totalp unit in SE Switzerland

    Science.gov (United States)

    Picazo, S.; Manatschal, G.; Cannat, M.; Andréani, M.

    2013-08-01

    Although the exhumation of ultramafic rocks in slow and ultraslow spreading Mid-Ocean Ridges and Ocean Continent Transitions (OCTs) has been extensively investigated, the deformation processes related to mantle exhumation are poorly constrained. In this paper we present a new geological map and a section across the exhumed serpentinized peridotites of the Totalp unit near Davos (SE Switzerland), and we propose that the Totalp unit is formed by two Alpine thrust sheets. Geological mapping indicates local exposure of a paleo-seafloor that is formed by an exhumed detachment surface and serpentinized peridotites. The top of the exhumed mantle rocks is made of ophicalcites that resulted from the carbonation of serpentine under static conditions at the seafloor. The ophicalcites preserve depositional contacts with Upper Jurassic to Lower Cretaceous pelagic sediments (Bernoulli and Weissert, 1985). These sequences did not exceed prehnite-pumpellyite metamorphic facies conditions, and locally escaped Alpine deformation. Thin mylonitic shear zones as well as foliated amphibole-bearing ultramafic rocks have been mapped. The age of these rocks and the link with the final exhumation history are yet unknown but since amphibole-bearing ultramafic rocks can be found as clasts in cataclasites related to the detachment fault, they pre-date detachment faulting. Our petrostructural study of the exhumed serpentinized rocks also reveals a deformation gradient from cataclasis to gouge formation within 150 m in the footwall of the proposed paleo-detachment fault. This deformation postdates serpentinization. It involves a component of plastic deformation of serpentine in the most highly strained intervals that has suffered pronounced grain-size reduction and a polyphase cataclastic overprint.

  17. B-type olivine fabric induced by low temperature dissolution creep during serpentinization and deformation in mantle wedge

    Science.gov (United States)

    Liu, Wenlong; Zhang, Junfeng; Barou, Fabrice

    2018-01-01

    The B-type olivine fabric (i.e., the [010] axes subnormal to foliation and the [001] axes subparallel to the lineation) has been regarded as an important olivine fabric for interpreting global trench-parallel S-wave polarization in fore-arc regions. However, strong serpentinization and cold temperature environment in the mantle wedge should inhibit development of the B-type olivine fabric that requires high temperature to activate solid-state plastic deformation. Here we report fabrics of olivine and antigorite generated at low temperatures (300-370 °C) during serpentinization in a fossil mantle wedge of the Val Malenco area, Central Alps. Olivine in the serpentine matrix develops a pronounced B-type fabric, while antigorite in the same matrix displays a strong crystallographic preferred orientation (CPO) with the (001) planes and the [010] axes subparallel to foliation and lineation, respectively. The following evidence leads to the conclusion that the B-type olivine fabric results from dissolution creep assisted by grain boundary sliding (GBS) and grain rotation, rather than solid-state plastic deformation: (1) serpentinization took place at low temperatures and a fluid-enriched environment, ideal for dissolution-precipitation creep; (2) the voids and zigzag boundaries along the interface between antigorite and olivine suggest a fluid dissolution reaction; (3) the primary coarse olivine develops a nearly random fabric, indicating the B-type fabrics in the fine-grained olivine may not be inherited fabrics. These results document for the first time the B-type olivine CPO formed by dissolution creep at low temperatures during serpentinization and provide a mechanism to reconcile petrofabric observations with geophysical observations of trench parallel fast S-wave seismic anisotropy in fore-arc mantle wedge regions.

  18. A method and device for cooling

    International Nuclear Information System (INIS)

    Gautier, Daniel.

    1974-01-01

    The invention relates to a method and a device for cooling steam. The invention refers to a method for cooling steam from a turbine, e.g. a turbine coupled to a high power nuclear reactor, in which a fluid F in the state of a two-phase mixture (steam and condensation liquid) is circulated, in a closed circuit, in conduits passing through a condenser associated with the turbine in which fluid F contained in said conduits vaporizes by heat-exchange with the condenser hot steam, then through a cooling tower wherein the fluid condenses by heat-exchange with a coolant. This can be applied to cooling the steam in a turbine associated with a nuclear reactor [fr

  19. Stable and High Ajmalicine or Serpentine Production of Gamma Radiation Induction Mutant Catharantus Roseus

    International Nuclear Information System (INIS)

    Sumaryati Syukur

    2004-01-01

    Catharantus roseus Mutant have been selected by gamma irradiation with 20 krad doses of radiation and characterized as biochemical mutant with anti-feed back inhibition mechanism of tritophan decarboxylase (TDR) enzyme in biosynthetic path way of indole alkaloid. Production of indole alkaloid mainly ajmalicine with high economical values as a pharmaceutical drug for heart attack have been studied by using cell suspension cultures with several variation of medium, elicitors and stress osmosis. This treatment produced variation of indole alkaloid ajmalicine and serpentine. Several induction methods using Murashige and Skoog (MS) medium and polyethylene glycol PEG (6000) 1 to 7%, with hormones concentration of 2,4-D and kinetin as (10 : 1), showed optimal results of ajmalicine range between 20 and 50 nmol/gFW, and serpentine 10 to 60 nmol/gFW. This production increases ten time in mutant (20 Krad) by stress osmotic condition and performed long term stability in culture without subculture. In this paper explanation in detail about the selection methods, stability of mutant and the production of indole alkaloid ajmalicine and serpentine during growth phase, such as adaptation, log, and stationar in suspention culture of mutan cells. (author)

  20. Optimization of seed germination in an Iranian serpentine endemic, Fortuynia garcinii

    NARCIS (Netherlands)

    Salehi Eskandari, Behrooz; Ghaderian, Seyed Majid; Ghasemi, Rasoul; Schat, Henk

    2017-01-01

    Fortuynia garcinii (Brassicaceae) is endemic to serpentine soils in central Iran. It has indehiscent silicles. The effects of its fruit pericarp on seed imbibition and germination were determined. The effects of moist chilling (15 days) and gibberellic acid (GA3, four levels), both alone and

  1. Two phase cooling for superconducting magnets

    International Nuclear Information System (INIS)

    Eberhard, P.H.; Gibson, G.A.; Green, M.A.; Ross, R.R.; Smits, R.G.; Taylor, J.D.; Watt, R.D.

    1986-01-01

    Comments on the use of two phase helium in a closed circuit tubular cooling system and some results obtained with the TPC superconducting magnet are given. Theoretical arguments and experimental evidence are given against a previously suggested method to determine helium two phase flow regimes. Two methods to reduce pressure in the magnet cooling tubes during quenches are discussed; (1) lowering the density of helium in the magnet cooling tubes and (2) proper location of pressure relief valves. Some techniques used to protect the refrigerator from too much cold return gas are also mentioned. 10 refs., 1 fig., 5 tabs

  2. Radiation color and electron-hole centers of serpentines

    International Nuclear Information System (INIS)

    Lyutoev, V.P.; Yukhtanov, P.P.

    1999-01-01

    Radiation-induced coloring of serpentine (Mg 3 [Si 2 O 5 ](OH) 4 ), gamma radiation dose being 30 Mrad, is studied by the ESR and absorption spectroscopy methods. It is ascertained that ionizing radiation gives rise to formation of radiation centers on the mineral basic structural elements. paramagnetic centers and coloring centers, relating to radiation centers, stem from the same type of defects - O - oxygen centers, formed as a result of radiation-induced break of OH-bonds [ru

  3. Study of a Two-Pipe Chilled Beam System for both Cooling and Heating of Office Buildings

    DEFF Research Database (Denmark)

    Gordnorouzi, Rouzbeh; Hultmark, Göran; Afshari, Alireza

    Active chilled beam systems are used to provide heating and cooling in order to achieve comfortable thermal indoor climate. For heating and cooling applications, an active chilled beam has two water circuits comprising four pipes that supply warm and cold water respectively to the beam coil...... according to the space demand. Lindab Comfort A/S has introduced an active chilled beam system which has just one water circuit (two pipes) that is used for both heating and cooling. The concept is based on high temperature cooling and low temperature heating. In this study the energy saving potential...

  4. The H2/CH4 ratio during serpentinization cannot reliably identify biological signatures.

    Science.gov (United States)

    Huang, Ruifang; Sun, Weidong; Liu, Jinzhong; Ding, Xing; Peng, Shaobang; Zhan, Wenhuan

    2016-09-26

    Serpentinization potentially contributes to the origin and evolution of life during early history of the Earth. Serpentinization produces molecular hydrogen (H 2 ) that can be utilized by microorganisms to gain metabolic energy. Methane can be formed through reactions between molecular hydrogen and oxidized carbon (e.g., carbon dioxide) or through biotic processes. A simple criterion, the H 2 /CH 4 ratio, has been proposed to differentiate abiotic from biotic methane, with values approximately larger than 40 for abiotic methane and values of serpentinization experiments at 200 °C and 0.3 kbar. However, it is not clear whether the criterion is applicable at a wider range of temperatures. In this study, we performed sixteen experiments at 311-500 °C and 3.0 kbar using natural ground peridotite. Our results demonstrate that the H 2 /CH 4 ratios strongly depend on temperature. At 311 °C and 3.0 kbar, the H 2 /CH 4 ratios ranged from 58 to 2,120, much greater than the critical value of 40. By contrast, at 400-500 °C, the H 2 /CH 4 ratios were much lower, ranging from 0.1 to 8.2. The results of this study suggest that the H 2 /CH 4 ratios cannot reliably discriminate abiotic from biotic methane.

  5. The H2/CH4 ratio during serpentinization cannot reliably identify biological signatures

    Science.gov (United States)

    Huang, Ruifang; Sun, Weidong; Liu, Jinzhong; Ding, Xing; Peng, Shaobang; Zhan, Wenhuan

    2016-09-01

    Serpentinization potentially contributes to the origin and evolution of life during early history of the Earth. Serpentinization produces molecular hydrogen (H2) that can be utilized by microorganisms to gain metabolic energy. Methane can be formed through reactions between molecular hydrogen and oxidized carbon (e.g., carbon dioxide) or through biotic processes. A simple criterion, the H2/CH4 ratio, has been proposed to differentiate abiotic from biotic methane, with values approximately larger than 40 for abiotic methane and values of serpentinization experiments at 200 °C and 0.3 kbar. However, it is not clear whether the criterion is applicable at a wider range of temperatures. In this study, we performed sixteen experiments at 311-500 °C and 3.0 kbar using natural ground peridotite. Our results demonstrate that the H2/CH4 ratios strongly depend on temperature. At 311 °C and 3.0 kbar, the H2/CH4 ratios ranged from 58 to 2,120, much greater than the critical value of 40. By contrast, at 400-500 °C, the H2/CH4 ratios were much lower, ranging from 0.1 to 8.2. The results of this study suggest that the H2/CH4 ratios cannot reliably discriminate abiotic from biotic methane.

  6. Thermal, epithermal and thermalized neutron attenuation properties of ilmenite-serpentine heat resistant concrete shield

    International Nuclear Information System (INIS)

    Kany, A.M.I.; El-Gohary, M.I.; Kamal, S.M.

    1994-01-01

    Experimental measurements were carried out to study the attenuation properties of low-energy neutrons transmitted through unheated and preheated barriers of heavy-weight, highly hydrated and heat-resistant concrete shields. The concrete shields under investigation have been prepared from naturally occurring ilmenite and serpentine Egyptian ores. A collimated beam obtained from an Am-Be source was used as a source of neutrons, while the measurements of total thermal, epithermal, and thermalized neutron fluxes were performed using a BF-3 detector, multichannel analyzer and Cd filter. Results show that the ilmenite-serpentine concrete proved to be a better thermal, epithermal and thermalized neutron attenuator than the ordinary concrete especially at a high temperature of concrete exposure. (Author)

  7. Combined endophytic inoculants enhance nickel phytoextraction from serpentine soil in the hyperaccumulator Noccaea caerulescens

    Directory of Open Access Journals (Sweden)

    Giovanna eVisioli

    2015-08-01

    Full Text Available This study assesses the effects of specific bacterial endophytes on the phytoextraction capacity of the Ni-hyperaccumulator Noccaea caerulescens, spontaneously growing in a serpentine soil environment. Five metal-tolerant endophytes had already been selected for their high Ni tolerance (6 mM and plant growth promoting ability. Here we demonstrate that individual bacterial inoculation is ineffective in enhancing Ni translocation and growth of N. caerulescens in serpentine soil, except for specific strains Ncr-1 and Ncr-8, belonging to the Arthrobacter and Microbacterium genera, which showed the highest IAA production and ACC-deaminase activity. Ncr-1 and Ncr-8 co-inoculation was even more efficient in promoting plant growth, soil Ni removal and translocation of Ni, together with that of Fe, Co and Cu. Bacteria of both strains densely colonised the root surfaces and intercellular spaces of leaf epidermal tissue. These two bacterial strains also turned out to stimulate root length, shoot biomass and Ni uptake in Arabidopsis thaliana grown in MS agar medium supplemented with Ni. It is concluded that adaptation of N. caerulescens in highly Ni-contaminated serpentine soil can be enhanced by an integrated community of bacterial endophytes rather than by single strains; of the former, Arthrobacter and Microbacterium may be useful candidates for future phytoremediation trials

  8. Metamorphic assemblages and the direction of flow of metamorphic fluids in four instances of serpentinization

    Science.gov (United States)

    Barnes, I.; Rapp, J.B.; O'Neil, J.R.; Sheppard, R.A.; Gude, A.J.

    1972-01-01

    Fluids related to Serpentinization are of at least three types. The first reported (Barnes and O'Neil, 1969) is a fluid of local meteoric origin, the chemical and thermodynamic properties of which are entirely controlled by olivine, orthopyroxene, brucite, and serpentine reactions. It is a Ca+2-OH-1 type and is shown experimentally to be capable of reacting with albite to yield calcium hydroxy silicates. Rodingites may form where the Ca+2-OH-1 type waters flow across the ultramafic contact and react with siliceous country rock. The second type of fluid has its chemical composition largely controlled before it enters the ultramafic rocks, but reactions within the ultramafic rocks fix the thermodynamic properties by reactions of orthopyroxene, olivine, calcite, brucite, and serpentine. The precipitation of brucite from this fluid clearly shows that fluid flow allows reaction products to be deposited at a distance from the point of solution. Thus, textural evidence for volume relations during Serpentinization may not be valid. The third type of fluid has its chemical properties fixed in part before the reactions with ultramafic rocks, in part by the reactions of orthopyroxene, olivine, and serpentine and in part by reactions with siliceous country rock at the contact. The reactions of the ultramafic rock and country rock with the fluid must be contemporaneous and require flow to be along the contact. This third type of fluid is grossly supersaturated with talc and tremolite, both found along the contact. The occurrence of magadiite, kenyaite, mountainite, and rhodesite along the contact is probably due to a late stage low-temperature reaction of fluids of the same thermodynamic properties as those that formed the talc and tremolite at higher temperatures. Oxygen isotope analyses of some of these minerals supports this conclusion. Rodingites form from Ca+2-rich fluids flowing across the contact; talc and tremolite form from silica-rich fluids flowing along the contact

  9. Modeling low-temperature serpentinization reactions to estimate molecular hydrogen production with implications for potential microbial life on Saturn's moon Enceladus.

    Science.gov (United States)

    Zwicker, Jennifer; Smrzka, Daniel; Taubner, Ruth-Sophie; Bach, Wolfgang; Rittmann, Simon; Schleper, Christa; Peckmann, Jörn

    2017-04-01

    Serpentinization of ultramafic rocks attracts much interest in research on the origin of life on Earth and the search for life on extraterrestrial bodies including icy moons like Enceladus. Serpentinization on Earth occurs in peridotite-hosted systems at slow-spreading mid-ocean ridges, and produces large amounts of molecular hydrogen and methane. These reduced compounds can be utilized by diverse chemosynthetic microbial consortia as a metabolic energy source. Although many hydrothermal vents emit hot and acidic fluids today, it is more likely that life originated in the Archean at sites producing much cooler and more alkaline fluids that allowed for the synthesis and stability of essential organic molecules necessary for life. Therefore, a detailed understanding of water-rock interaction processes during low-temperature serpentinization is of crucial importance in assessing the life-sustaining potential of these environments. In the course of serpentinization, the metasomatic hydration of olivine and pyroxene produces various minerals including serpentine minerals, magnetite, brucite, and carbonates. Hydrogen production only occurs if ferrous iron within iron-bearing minerals is oxidized and incorporated as ferric iron into magnetite. The PHREEQC code was used to model the pH- and temperature-dependent dissolution of olivine and pyroxene to form serpentine, magnetite and hydrogen under pressure and temperature conditions that may exist on Saturn's icy moon Enceladus. Various model setups at 25 and 50°C were run to assess the influence of environmental parameters on hydrogen production. The results reveal that hydrogen production rates depend on the composition of the initial mineral assemblage and temperature. The current assumption is that there is a gaseous phase between Enceladus' ice sheet and subsurface ocean. To test various scenarios, model runs were conducted with and without the presence of a gas phase. The model results show that hydrogen production is

  10. Thermal and flow design of helium-cooled reactors

    International Nuclear Information System (INIS)

    Melese, G.; Katz, R.

    1984-01-01

    This book continues the American Nuclear Society's series of monographs on nuclear science and technology. Chapters of the book include information on the first-generation gas-cooled reactors; HTGR reactor developments; reactor core heat transfer; mechanical problems related to the primary coolant circuit; HTGR design bases; core thermal design; gas turbines; process heat HTGR reactors; GCFR reactor thermal hydraulics; and gas cooling of fusion reactors

  11. Radionuclide activity in the secondary cooling circuit of the NPP with WWER-440

    International Nuclear Information System (INIS)

    Voronin, L.M.; Volkov, A.P.; Kozlov, V.F.; Luzanova, L.M.; Pashevich, V.I.

    1979-01-01

    On the basis of the Kol'skaya NPP operating experience the radioactivity of water and steam fed to turbines and boilers has been determined. The radioactivity of water in the primary circuit is demonstrated to be mainly due to 24 Na, 42 K, 18 F, sup(131-135)I, and in the secondary circuit - due to 131 I and 133 I. The data obtained testify to the permanent leakage of water from the primary circuit to the secondary one averaging 19+-12 g/hr at the pressure gradient between the circuits approximately 7.0 MPa. With the probability of 1.2x10 -1 -1.6x10 -2 (eff. reactor day) -1 or 1.2x10 -8 -1.6x10 -9 (kWxhr) -1 the leakage may for some time increase to 1 l/hr

  12. An inverted continental Moho and serpentinization of the forearc mantle.

    Science.gov (United States)

    Bostock, M G; Hyndman, R D; Rondenay, S; Peacock, S M

    2002-05-30

    Volatiles that are transported by subducting lithospheric plates to depths greater than 100 km are thought to induce partial melting in the overlying mantle wedge, resulting in arc magmatism and the addition of significant quantities of material to the overlying lithosphere. Asthenospheric flow and upwelling within the wedge produce increased lithospheric temperatures in this back-arc region, but the forearc mantle (in the corner of the wedge) is thought to be significantly cooler. Here we explore the structure of the mantle wedge in the southern Cascadia subduction zone using scattered teleseismic waves recorded on a dense portable array of broadband seismometers. We find very low shear-wave velocities in the cold forearc mantle indicated by the exceptional occurrence of an 'inverted' continental Moho, which reverts to normal polarity seaward of the Cascade arc. This observation provides compelling evidence for a highly hydrated and serpentinized forearc region, consistent with thermal and petrological models of the forearc mantle wedge. This serpentinized material is thought to have low strength and may therefore control the down-dip rupture limit of great thrust earthquakes, as well as the nature of large-scale flow in the mantle wedge.

  13. H2-rich fluids from serpentinization: geochemical and biotic implications.

    Science.gov (United States)

    Sleep, N H; Meibom, A; Fridriksson, Th; Coleman, R G; Bird, D K

    2004-08-31

    Metamorphic hydration and oxidation of ultramafic rocks produces serpentinites, composed of serpentine group minerals and varying amounts of brucite, magnetite, and/or FeNi alloys. These minerals buffer metamorphic fluids to extremely reducing conditions that are capable of producing hydrogen gas. Awaruite, FeNi3, forms early in this process when the serpentinite minerals are Fe-rich. Olivine with the current mantle Fe/Mg ratio was oxidized during serpentinization after the Moon-forming impact. This process formed some of the ferric iron in the Earth's mantle. For the rest of Earth's history, serpentinites covered only a small fraction of the Earth's surface but were an important prebiotic and biotic environment. Extant methanogens react H2 with CO2 to form methane. This is a likely habitable environment on large silicate planets. The catalytic properties of FeNi3 allow complex organic compounds to form within serpentinite and, when mixed with atmospherically produced complex organic matter and waters that circulated through basalts, constitutes an attractive prebiotic substrate. Conversely, inorganic catalysis of methane by FeNi3 competes with nascent and extant life. Copyright 2004 The National Academy of Sciencs of the USA

  14. A segmented cell approach for studying the effects of serpentine flow field parameters on PEMFC current distribution

    International Nuclear Information System (INIS)

    Reshetenko, Tatyana V.; Bender, Guido; Bethune, Keith; Rocheleau, Richard

    2013-01-01

    Highlights: ► Effects of a flow field design on PEMFC were investigated. ► A segmented cell was used to study 6- and 10-channel serpentine flow fields. ► 10-Channel flow field improved a fuel cell's performance at high current. ► Performance distribution was more uniform for 10-channel than for 6-channel flow field. ► The performance improvement was due to an increased pressure drop. -- Abstract: A serpentine flow field is a commonly used design in proton exchange membrane fuel cells (PEMFCs). Consequently, optimization of the flow field parameters is critically needed. A segmented cell system was used to study the impact of the flow field's parameters on the current distribution in a PEMFC, and the data obtained were analyzed in terms of voltage overpotentials. 6-Channel and 10-channel serpentine flow field designs were investigated. At low current the segments performance was found to slightly decrease for a 10-channel serpentine flow field. However, increasing the number of channels increased the fuel cell performance when operating at high current and the cell performance became more uniform downstream. The observed improvement in fuel cell performance was attributed to a decrease in mass transfer voltage losses (permeability and diffusion), due to an increased pressure drop. Spatially distributed electrochemical impedance spectroscopy (EIS) data showed differences in the local segment impedance response and confirmed the performance distribution and the impact of the flow field design

  15. A SQUID Bootstrap Circuit with a Large Parameter Tolerance

    International Nuclear Information System (INIS)

    Zhang Guo-Feng; Kong Xiang-Yan; Xie Xiao-Ming; Zhang Yi; Krause Hans-Joachim; Offenhäusser Andreas

    2013-01-01

    The voltage biased (SQUID) bootstrap circuit (SBC) was recently introduced as an effective means to reduce the preamplifier noise contribution. We analyze the tolerances of the SBC noise suppression performance to spreads in SQUID and SBC circuit parameters. It is found that the tolerance to spread mainly caused by the integrated circuit fabrication process could be extended by a one-time adjustable current feedback. A helium-cooled niobium SQUID with a loop inductance of 350 pH is employed to experimentally verify the analysis. From this work, design criteria for fully integrated SBC devices with a high yield can be derived

  16. Expedition 357 Preliminary Report: Atlantis Massif Serpentinization and Life

    OpenAIRE

    Früh-Green, GL; Orcutt, BN; Green, S; Cotterill, C; McCaig, AM; Expedition 357 Scientists,

    2016-01-01

    International Ocean Discovery Program (IODP) Expedition 357 successfully cored an east–west transect across the southern wall of Atlantis Massif on the western flank of the Mid-Atlantic Ridge to study the links between serpentinization processes and microbial activity in the shallow subsurface of highly altered ultramafic and mafic sequences that have been uplifted to the seafloor along a major detachment fault zone. The primary goals of this expedition were to (1) examine the role of serpent...

  17. The serpentine mitral valve and cerebral embolism

    Directory of Open Access Journals (Sweden)

    Ker James

    2011-02-01

    Full Text Available Abstract Valvular strands, well-delineated filiform masses, attached to cardiac valve edges are associated with cerebral embolism and stroke. Strokes, caused by emboli from valvular strands, tend to occur among younger persons. In this case report a valvular strand, giving a peculiar serpentine appearance to the mitral valve is described. This mitral valvular strand was the only explanation for an episode of cerebral embolism, presenting with a transient right sided hemiparesis. It is proposed that a randomized study involving combined treatment with aspirin and clopidogrel is warranted in young patients with valvular strands, presenting with a first episode of cerebral embolism.

  18. Numerical simulation of draining and drying procedure for the ITER Generic Equatorial Port Plug cooling system

    International Nuclear Information System (INIS)

    Tanchuk, Victor; Grigoriev, Sergey; Lyublin, Boris; Maquet, Philippe; Senik, Konstantin; Pak, Sunil; Udintsev, Victor

    2016-01-01

    Highlights: • The cooling system of the ITER Generic Equatorial Port Plug (GEPP) is of a complicated combination of horizontal and vertical channels. • The calculation model for the entire GEPP cooling circuit comprising 12 sub-circuits and built up of 2421 finite-volume elements has been developed. • Transient analysis of this model simulating the draining procedure by the KORSAR/B1 code has been performed. • Water in amount of 263 g of initial 531 kg in the GEPP remains in the dead-ends of the DSM and DFW channels in 150 s of draining procedure. • Almost 3 h are required to boil off 263 g of water trapped in the dead-ends. - Abstract: For effective vacuum leak testing all cooling circuits serving the ITER vessel and in-vessel components shall be drained and dried so that after this procedure taking less than 100 h the purge gas passing through a component has water content less than 100 ppm. This process is four-stage, with the first stage using a short blast of compressed nitrogen to blow most of water in the coolant channels out of the circuit. This process is hindered by volumes which trap water due to gravity. To remove the trapped water, it is necessary, first, to heat up the structure by hot and compressed nitrogen, and then water is evaporated by depressurized nitrogen. The cooling system of the ITER Diagnostic Equatorial Port Plugs is of a complicated hydraulic configuration. The system branching might make difficult removal of water from the piping in the scheduled draining mode. The authors have proposed the KORSAR computation code to simulate draining of the GEPP cooling circuit. The numerical simulation performed has made it possible to describe the process dynamics during draining of the entire GEPP cooling circuit and to define the process time, amount and location of residual water and evolution of two-phase flow regime.

  19. Numerical simulation of draining and drying procedure for the ITER Generic Equatorial Port Plug cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Tanchuk, Victor, E-mail: Victor.Tanchuk@sintez.niiefa.spb.su [JSC “D.V. Efremov Institute of Electrophysical Apparatus”, 196641 St. Petersburg (Russian Federation); Grigoriev, Sergey; Lyublin, Boris [JSC “D.V. Efremov Institute of Electrophysical Apparatus”, 196641 St. Petersburg (Russian Federation); Maquet, Philippe [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Senik, Konstantin [JSC “D.V. Efremov Institute of Electrophysical Apparatus”, 196641 St. Petersburg (Russian Federation); Pak, Sunil [National Fusion Research Institute, Daejeon (Korea, Republic of); Udintsev, Victor [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France)

    2016-11-01

    Highlights: • The cooling system of the ITER Generic Equatorial Port Plug (GEPP) is of a complicated combination of horizontal and vertical channels. • The calculation model for the entire GEPP cooling circuit comprising 12 sub-circuits and built up of 2421 finite-volume elements has been developed. • Transient analysis of this model simulating the draining procedure by the KORSAR/B1 code has been performed. • Water in amount of 263 g of initial 531 kg in the GEPP remains in the dead-ends of the DSM and DFW channels in 150 s of draining procedure. • Almost 3 h are required to boil off 263 g of water trapped in the dead-ends. - Abstract: For effective vacuum leak testing all cooling circuits serving the ITER vessel and in-vessel components shall be drained and dried so that after this procedure taking less than 100 h the purge gas passing through a component has water content less than 100 ppm. This process is four-stage, with the first stage using a short blast of compressed nitrogen to blow most of water in the coolant channels out of the circuit. This process is hindered by volumes which trap water due to gravity. To remove the trapped water, it is necessary, first, to heat up the structure by hot and compressed nitrogen, and then water is evaporated by depressurized nitrogen. The cooling system of the ITER Diagnostic Equatorial Port Plugs is of a complicated hydraulic configuration. The system branching might make difficult removal of water from the piping in the scheduled draining mode. The authors have proposed the KORSAR computation code to simulate draining of the GEPP cooling circuit. The numerical simulation performed has made it possible to describe the process dynamics during draining of the entire GEPP cooling circuit and to define the process time, amount and location of residual water and evolution of two-phase flow regime.

  20. Cooling system of the core of a nuclear reactor while it is being stopped or normally operating

    International Nuclear Information System (INIS)

    Tilliette, Z.

    1986-01-01

    The present invention proposes a cooling system with intermediate gas flow which ensures the reactor core cooling when the primary pumps are stopped either directly by means of main heat-exchange circuits ensuring normally the reactor operation, or by means of separated loops, these ones being able so to operate in an autonomous way for they produce their own electricity needs and also an excedent which is added to the power plant production. The cooling circuit and the heat exchanger are described in detail [fr

  1. SEMTAP (Serpentine End Match TApe program): The Easy Way to Program Your Numerically Controlled Router for the Production of SEM Joints

    Science.gov (United States)

    Ronald E. Coleman

    1977-01-01

    SEMTAP (Serpentine End Match TApe Program) is an easy and inexpensive method of programing a numerically controlled router for the manufacture of SEM (Serpentine End Matching) joints. The SEMTAP computer program allows the user to issue commands that will accurately direct a numerically controlled router along any SEM path. The user need not be a computer programer to...

  2. Combined endophytic inoculants enhance nickel phytoextraction from serpentine soil in the hyperaccumulator Noccaea caerulescens.

    Science.gov (United States)

    Visioli, Giovanna; Vamerali, Teofilo; Mattarozzi, Monica; Dramis, Lucia; Sanangelantoni, Anna M

    2015-01-01

    This study assesses the effects of specific bacterial endophytes on the phytoextraction capacity of the Ni-hyperaccumulator Noccaea caerulescens, spontaneously growing in a serpentine soil environment. Five metal-tolerant endophytes had already been selected for their high Ni tolerance (6 mM) and plant growth promoting ability. Here we demonstrate that individual bacterial inoculation is ineffective in enhancing Ni translocation and growth of N. caerulescens in serpentine soil, except for specific strains Ncr-1 and Ncr-8, belonging to the Arthrobacter and Microbacterium genera, which showed the highest indole acetic acid production and 1-aminocyclopropane-1-carboxylic acid-deaminase activity. Ncr-1 and Ncr-8 co-inoculation was even more efficient in promoting plant growth, soil Ni removal, and translocation of Ni, together with that of Fe, Co, and Cu. Bacteria of both strains densely colonized the root surfaces and intercellular spaces of leaf epidermal tissue. These two bacterial strains also turned out to stimulate root length, shoot biomass, and Ni uptake in Arabidopsis thaliana grown in MS agar medium supplemented with Ni. It is concluded that adaptation of N. caerulescens in highly Ni-contaminated serpentine soil can be enhanced by an integrated community of bacterial endophytes rather than by single strains; of the former, Arthrobacter and Microbacterium may be useful candidates for future phytoremediation trials in multiple metal-contaminated sites, with possible extension to non-hyperaccumulator plants.

  3. Quantifying Cr(VI) Production and Export from Serpentine Soil of the California Coast Range.

    Science.gov (United States)

    McClain, Cynthia N; Fendorf, Scott; Webb, Samuel M; Maher, Kate

    2017-01-03

    Hexavalent chromium (Cr(VI)) is generated in serpentine soils and exported to surface and groundwaters at levels above health-based drinking water standards. Although Cr(VI) concentrations are elevated in serpentine soil pore water, few studies have reported field evidence documenting Cr(VI) production rates and fluxes that govern Cr(VI) transport from soil to water sources. We report Cr speciation (i) in four serpentine soil depth profiles derived from the California Coast Range serpentinite belt and (ii) in local surface waters. Within soils, we detected Cr(VI) in the same horizons where Cr(III)-minerals are colocated with biogenic Mn(III/IV)-oxides, suggesting Cr(VI) generation through oxidation by Mn-oxides. Water-extractable Cr(VI) concentrations increase with depth constituting a 7.8 to 12 kg/km 2 reservoir of Cr(VI) in soil. Here, Cr(VI) is produced at a rate of 0.3 to 4.8 kg Cr(VI)/km 2 /yr and subsequently flushed from soil during water infiltration, exporting 0.01 to 3.9 kg Cr(VI)/km 2 /yr at concentrations ranging from 25 to 172 μg/L. Although soil-derived Cr(VI) is leached from soil at concentrations exceeding 10 μg/L, due to reduction and dilution during transport to streams, Cr(VI) levels measured in local surface waters largely remain below California's drinking water limit.

  4. Cooling of nuclear power stations with high temperature reactors and helium turbine cycles

    International Nuclear Information System (INIS)

    Foerster, S.; Hewing, G.

    1977-01-01

    On nuclear power stations with high temperature reactors and helium turbine cycles (HTR-single circuits) the residual heat from the energy conversion process in the primary and intermediate coolers is removed from cycled gas, helium. Water, which is circulated for safety reasons through a closed circuit, is used for cooling. The primary and intermediate coolers as well as other cooling equipment of the power plant are installed within the reactor building. The heat from the helium turbine cycle is removed to the environment most effectively by natural draught cooling towers. In this way a net plant efficiency of about 40% is attainable. The low quantities of residual heat thereby produced and the high (in comparison with power stations with steam turbine cycles) cooling agent pressure and cooling water reheat pressure in the circulating coolers enable an economically favourable design of the overall 'cold end' to be expected. In the so-called unit range it is possible to make do with one or two cooling towers. Known techniques and existing operating experience can be used for these dry cooling towers. After-heat removal reactor shutdown is effected by a separate, redundant cooling system with forced air dry coolers. The heat from the cooling process at such locations in the power station is removed to the environment either by a forced air dry cooling installation or by a wet cooling system. (orig.) [de

  5. CFD Models of a Serpentine Inlet, Fan, and Nozzle

    Science.gov (United States)

    Chima, R. V.; Arend, D. J.; Castner, R. S.; Slater, J. W.; Truax, P. P.

    2010-01-01

    Several computational fluid dynamics (CFD) codes were used to analyze the Versatile Integrated Inlet Propulsion Aerodynamics Rig (VIIPAR) located at NASA Glenn Research Center. The rig consists of a serpentine inlet, a rake assembly, inlet guide vanes, a 12-in. diameter tip-turbine driven fan stage, exit rakes or probes, and an exhaust nozzle with a translating centerbody. The analyses were done to develop computational capabilities for modeling inlet/fan interaction and to help interpret experimental data. Three-dimensional Reynolds averaged Navier-Stokes (RANS) calculations of the fan stage were used to predict the operating line of the stage, the effects of leakage from the turbine stream, and the effects of inlet guide vane (IGV) setting angle. Coupled axisymmetric calculations of a bellmouth, fan, and nozzle were used to develop techniques for coupling codes together and to investigate possible effects of the nozzle on the fan. RANS calculations of the serpentine inlet were coupled to Euler calculations of the fan to investigate the complete inlet/fan system. Computed wall static pressures along the inlet centerline agreed reasonably well with experimental data but computed total pressures at the aerodynamic interface plane (AIP) showed significant differences from the data. Inlet distortion was shown to reduce the fan corrected flow and pressure ratio, and was not completely eliminated by passage through the fan

  6. ''Novel'' types of cooling towers for the power industry

    International Nuclear Information System (INIS)

    Mikyska, L.

    1991-01-01

    New types of cooling towers are beginning to be used abroad for the cooling circuits of nuclear power plants employing power generation units rated at 1,300 to 1,400 MW. These so-called water recovery cooling towers make use of natural draught without a droplet section. They are actually upgraded designs which were built in Europe as far back as 70 years ago. Because of the unsuitable materials then employed, these cooling towers fell into oblivion. Today, however, they are undergoing a renaissance. An upgraded design of these towers is described and compared with existing cooling towers with a droplet section. The feasibility of using these towers in Czechoslovak conditions is considered. (author)

  7. Plants as extreme environments? Ni-resistant bacteria and Ni-hyperaccumulators of serpentine flora.

    NARCIS (Netherlands)

    Mengoni, A.; Schat, H.; Vangronsveld, J.

    2010-01-01

    During recent years there has been an increasing interest in the bacterial communities occurring in unusual, often extreme, environments. On serpentine outcrops around the world, a high diversity of plant species showing the peculiar features of metal hyperaccumulation is present. These metal

  8. Control of Non-linear Marine Cooling System

    DEFF Research Database (Denmark)

    Hansen, Michael; Stoustrup, Jakob; Bendtsen, Jan Dimon

    2011-01-01

    We consider the problem of designing control laws for a marine cooling system used for cooling the main engine and auxiliary components aboard several classes of container vessels. We focus on achieving simple set point control for the system and do not consider compensation of the non-linearitie......-linearities, closed circuit flow dynamics or transport delays that are present in the system. Control laws are therefore designed using classical control theory and the performance of the design is illustrated through two simulation examples....

  9. Stable isotope study of serpentinization and metamorphism in the Highland Border Suite, Scotland, UK

    Energy Technology Data Exchange (ETDEWEB)

    Ikin, N.P. (University Coll., Cardiff (UK)); Harmon, R.S. (Southern Methodist Univ., Dallas, TX (USA))

    1983-02-01

    D/H and /sup 18/O//sup 16/O ratios have been measured for whole-rock samples and mineral separates from the mafic and ultramafic rocks of the Cambro-Ordovician Highland Border Suite. The H- and O-isotopic compositions of these rocks record individual stages in a relatively complex 500 Myr old hydrothermal/ metamorphic history. Lizardite serpentinites record a premetamorphic history and indicate that parent harzburgites, dunites, and pyroxenites were serpentinized through low-temperature interaction with meteoric waters during cooling. The other rocks of the Highland Border Suite record subsequent interaction with metamorphic fluids. Amphibolite facies hornblende schists were produced through thrust-related metamorphism of spilitic pillow lavas. During dehydration, D-enriched fluids were driven off from the spilites thus leaving the hornblende schists to equilibrate with a relatively D-depleted internal fluid reservoir. The expelled D-enriched fluids may have mixed with more typical Dalradian metamorphic waters which then exchanged with the remaining mafic rocks and lizardite serpentinites during greenschist facies regional metamorphism to produce antigorite serpentinites and greenschist metaspilites with similar H- and O-isotopic compositions. Serpentinites which have been only partially metamorphosed show intermediate H-isotopic compositions between that of metamorphic antigorite and non-metamorphic lizardite end members.

  10. Fission product behaviour in the primary circuit of an HTR

    International Nuclear Information System (INIS)

    Decken, C.B. von der; Iniotakis, N.

    1981-01-01

    The knowledge of fission product behaviour in the primary circuit of a High Temperature Reactor (HTR) is an essential requirement for the estimations of the availability of the reactor plant in normal operation, of the hazards to personnel during inspection and repair and of the potential danger to the environment from severe accidents. On the basis of the theoretical and experimental results obtained at the ''Institute for Reactor Components'' of the KFA Juelich /1/,/2/ the transport- and deposition behaviour of the fission- and activation products in the primary circuit of the PNP-500 reference plant has been investigated thoroughly. Special work had been done to quantify the uncertainties of the investigations and to calculate or estimate the dose rate level at different components of the primary cooling circuit. The contamination and the dose rate level in the inspection gap in the reactor pressure vessel is discussed in detail. For these investigations in particular the surface structure and the composition of the material, the chemical state of the fission products in the cooling gas, the composition of the cooling gas and the influence of dust on the transport- and deposition behaviour of the fission products have been taken into account. The investigations have been limited to the nuclides Ag-110m; Cs-134 and Cs-137

  11. Two-phase cooling fluids; Les fluides frigoporteurs diphasiques

    Energy Technology Data Exchange (ETDEWEB)

    Lallemand, A. [Institut National des Sciences Appliquees (INSA), 69 - Lyon (France)

    1997-12-31

    In the framework of the diminution of heat transfer fluid consumption, the concept of indirect refrigerating circuits, using cooling intermediate fluids, is reviewed and the fluids that are currently used in these systems are described. Two-phase cooling fluids advantages over single-phase fluids are presented with their thermophysical characteristics: solid fraction, two-phase mixture enthalpy, thermal and rheological properties, determination of heat and mass transfer characteristics, and cold storage through ice slurry

  12. Applicability of a desiccant dew-point cooling system independent of external water sources

    DEFF Research Database (Denmark)

    Bellemo, Lorenzo; Elmegaard, Brian; Kærn, Martin Ryhl

    2015-01-01

    The applicability of a technical solution for making desiccant cooling systems independent of external water sources is investigated. Water is produced by condensing the desorbed water vapour in a closed regeneration circuit. Desorbed water recovery is applied to a desiccant dew-point cooling...... system, which includes a desiccant wheel and a dew point cooler. The system is simulated during the summer period in the Mediterranean climate of Rome and it results completely independent of external water sources. The seasonal thermal COP drops 8% in comparison to the open regeneration circuit solution...

  13. Interface tuning of current-induced cooling in molecular circuits

    Czech Academy of Sciences Publication Activity Database

    Foti, Giuseppe; Vázquez, Héctor

    2017-01-01

    Roč. 121, č. 2 (2017), s. 1082-1088 ISSN 1932-7447 R&D Projects: GA ČR GA15-19672S Institutional support: RVO:68378271 Keywords : current-induced heating and cooling * molecular junction * Carbene Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.536, year: 2016

  14. Passive afterheat removal in the HTGR with the liner cooling system as a heat sink

    International Nuclear Information System (INIS)

    Rehm, W.; Jahn, W.; Verfondern, K.

    1984-09-01

    The report deals with the transients of temperature and system pressure and the fission product behaviour in the primary circuit of an HTGR during passive afterheat removal, where the liner cooling system of the PCRV serves as a heat sink. The analysis has been made for the PNP-500-reactor representing nuclear plants with medium thermal power. The investigations show that the liner cooling system is able to control a core heatup. High temperature loads are encountered in the upper core region. In the case of a reactor under pressure the fuel elements and the primary circuit remain intact as the first and second barriers for fission products. In the case of a depressurized primary circuit the liner cooling system also keeps the PCRV at normal operating temperatures. The effects of a core heatup on component damage and release of fission products are thus limited. (orig.) [de

  15. LS1 Report: short-circuit tests

    CERN Multimedia

    Katarina Anthony

    2014-01-01

    As the LS1 draws to an end, teams move from installation projects to a phase of intense testing. Among these are the so-called 'short-circuit tests'. Currently under way at Point 7, these tests verify the cables, the interlocks, the energy extraction systems, the power converters that provide current to the superconducting magnets and the cooling system.   Thermal camera images taken during tests at point 4 (IP4). Before putting beam into the LHC, all of the machine's hardware components need to be put to the test. Out of these, the most complicated are the superconducting circuits, which have a myriad of different failure modes with interlock and control systems. While these will be tested at cold - during powering tests to be done in August - work can still be done beforehand. "While the circuits in the magnets themselves cannot be tested at warm, what we can do is verify the power converter and the circuits right up to the place the cables go into the magn...

  16. Nuclear reactor lid cooling which can work by natural circulation

    International Nuclear Information System (INIS)

    Wagner, J.

    1985-01-01

    The well-known air cooling of the lid of liquid metal cooled nuclear reactors is improved by the start of natural convection flow ensuring removal of heat in a sufficiently short time, if the blower fails. Go and return branches of the individual cooling circuits are arranged at different heights for this purpose. The circulation is supported by opening valves, which provide a direct path into the reactor building for the cooling air. The draught can be increased by setting up special chimneys. The start of circulation is aided by the temporary opening of another valve. (orig.) [de

  17. Serpentinization as a source of energy at the origin of life.

    Science.gov (United States)

    Russell, M J; Hall, A J; Martin, W

    2010-12-01

    For life to have emerged from CO₂, rocks, and water on the early Earth, a sustained source of chemically transducible energy was essential. The serpentinization process is emerging as an increasingly likely source of that energy. Serpentinization of ultramafic crust would have continuously supplied hydrogen, methane, minor formate, and ammonia, as well as calcium and traces of acetate, molybdenum and tungsten, to off-ridge alkaline hydrothermal springs that interfaced with the metal-rich carbonic Hadean Ocean. Silica and bisulfide were also delivered to these springs where cherts and sulfides were intersected by the alkaline solutions. The proton and redox gradients so generated represent a rich source of naturally produced chemiosmotic energy, stemming from geochemistry that merely had to be tapped, rather than induced, by the earliest biochemical systems. Hydrothermal mounds accumulating at similar sites in today's oceans offer conceptual and experimental models for the chemistry germane to the emergence of life, although the ubiquity of microbial communities at such sites in addition to our oxygenated atmosphere preclude an exact analogy. Published 2010. This article is a US Government work and is in the public domain in the USA.

  18. Continuous particle separation in a serpentine microchannel via negative and positive dielectrophoretic focusing

    International Nuclear Information System (INIS)

    Church, Christopher; Zhu, Junjie; Nieto, Juan; Keten, Gyunay; Ibarra, Erl; Xuan, Xiangchun

    2010-01-01

    Dielectrophoresis (DEP) has been widely used to focus and separate cells and particles in microfluidic devices. This work first demonstrates negative and positive dielectrophoretic focusing of particles in a serpentine microchannel by changing only the electric conductivity of the suspending fluid. Due to the channel turn-induced dielectrophoretic force, particles are focused to either the centerline or the sidewalls of the channel when their electric conductivity is lower (i.e. negative DEP) or higher (i.e. positive DEP) than that of the fluid. These distinctive dielectrophoretic focusing phenomena in a serpentine microchannel are then combined to implement a continuous separation between particles of different sizes and electric conductivities. Such separation eliminates the fabrication of in-channel microelectrodes or micro-insulators that are typically required in DEP-based separation techniques. A numerical model is also developed to predict the particle motion, and the simulation results agree reasonably with the observed particle focusing and separation behaviors.

  19. Trade-off analysis of high-aspect-ratio-cooling-channels for rocket engines

    International Nuclear Information System (INIS)

    Pizzarelli, Marco; Nasuti, Francesco; Onofri, Marcello

    2013-01-01

    Highlights: • Aspect ratio has a significant effect on cooling efficiency and hydraulic losses. • Minimizing power loss is of paramount importance in liquid rocket engine cooling. • A suitable quasi-2D model is used to get fast cooling system analysis. • Trade-off with assigned weight, temperature, and channel height or wall thickness. • Aspect ratio is found that minimizes power loss in the cooling circuit. -- Abstract: High performance liquid rocket engines are often characterized by rectangular cooling channels with high aspect ratio (channel height-to-width ratio) because of their proven superior cooling efficiency with respect to a conventional design. However, the identification of the optimum aspect ratio is not a trivial task. In the present study a trade-off analysis is performed on a cooling channel system that can be of interest for rocket engines. This analysis requires multiple cooling channel flow calculations and thus cannot be efficiently performed by CFD solvers. Therefore, a proper numerical approach, referred to as quasi-2D model, is used to have fast and accurate predictions of cooling system properties. This approach relies on its capability of describing the thermal stratification that occurs in the coolant and in the wall structure, as well as the coolant warming and pressure drop along the channel length. Validation of the model is carried out by comparison with solutions obtained with a validated CFD solver. Results of the analysis show the existence of an optimum channel aspect ratio that minimizes the requested pump power needed to overcome losses in the cooling circuit

  20. Characterizing Dissolved Organic Matter and Metabolites in an Actively Serpentinizing Ophiolite Using Global Metabolomics Techniques

    Science.gov (United States)

    Seyler, L. M.; Rempfert, K. R.; Kraus, E. A.; Spear, J. R.; Templeton, A. S.; Schrenk, M. O.

    2017-12-01

    Environmental metabolomics is an emerging approach used to study ecosystem properties. Through bioinformatic comparisons to metagenomic data sets, metabolomics can be used to study microbial adaptations and responses to varying environmental conditions. Since the techniques are highly parallel to organic geochemistry approaches, metabolomics can also provide insight into biogeochemical processes. These analyses are a reflection of metabolic potential and intersection with other organisms and environmental components. Here, we used an untargeted metabolomics approach to characterize dissolved organic carbon and aqueous metabolites from groundwater obtained from an actively serpentinizing habitat. Serpentinites are known to support microbial communities that feed off of the products of serpentinization (such as methane and H2 gas), while adapted to harsh environmental conditions such as high pH and low DIC availability. However, the biochemistry of microbial populations that inhabit these environments are understudied and are complicated by overlapping biotic and abiotic processes. The aim of this study was to identify potential sources of carbon in an environment that is depleted of soluble inorganic carbon, and to characterize the flow of metabolites and describe overlapping biogenic and abiogenic processes impacting carbon cycling in serpentinizing rocks. We applied untargeted metabolomics techniques to groundwater taken from a series of wells drilled into the Semail Ophiolite in Oman.. Samples were analyzed via quadrupole time-of-flight liquid chromatography tandem mass spectrometry (QToF-LC/MS/MS). Metabolomes and metagenomic data were imported into Progenesis QI software for statistical analysis and correlation, and metabolic networks constructed using the Genome-Linked Application for Metabolic Maps (GLAMM), a web interface tool. Further multivariate statistical analyses and quality control was performed using EZinfo. Pools of dissolved organic carbon could

  1. HTGR [High Temperature Gas-Cooled Reactor] ingress analysis using MINET

    International Nuclear Information System (INIS)

    Van Tuyle, G.J.; Yang, J.W.; Kroeger, P.G.; Mallen, A.N.; Aronson, A.L.

    1989-04-01

    Modeling of water/steam ingress into the primary (helium) cooling circuit of a High Temperature Gas-Cooled Reactor (HTGR) is described. This modeling was implemented in the MINET Code, which is a program for analyzing transients in intricate fluid flow and heat transfer networks. Results from the simulation of a water ingress event postulated for the Modular HTGR are discussed. 27 refs., 6 figs., 6 tabs

  2. R + D work on gas-cooled breeder development

    International Nuclear Information System (INIS)

    Dalle Donne, M.; Dorner, S.; Jacobs, G.; Meyer, L.; Rehme, K.; Schumacher, G.; Wilhelm, D.

    1978-01-01

    The development work for the gas-cooled breeder in the Karlsruhe Nuclear Research Center may be assigned to two different groups: a) Investigations on fuel elements. b) Studies concerning the safety of gas-cooled fast breeder reactors. To the first group there belongs the work related to the: - heat transfer between fuel elements and coolant gas, - influence of increased content of water vapor in helium or the fuel rods. The second group concerns: - establishing a computer code for transient calculations in the primary and secondary circuit of a gas-cooled fast breeder reactor, - steam reactivity coefficients, - the core destruction phase of hypothetical accidents, - the core-catcher using borax. (orig./RW) [de

  3. Sliding friction and wear behaviors of surface-coated natural serpentine mineral powders as lubricant additive

    International Nuclear Information System (INIS)

    Zhang Baosen; Xu Yi; Gao Fei; Shi Peijing; Xu Binshi; Wu Yixiong

    2011-01-01

    This work aims to investigate the friction and wear properties of surface-coated natural serpentine powders (SP) suspended in diesel engine oil using an Optimal SRV oscillating friction and wear tester. The worn surface was characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). Results indicated that the additives can improve the wear resistance and decrease friction coefficient of carbon steel friction couples. The 0.5 wt% content of serpentine powders is found most efficient in reducing friction and wear at the load of 50 N. The SEM and XPS analysis results demonstrate that a tribofilm forms on the worn surface, which is responsible for the decrease in friction and wear, mainly with iron oxides, silicon oxides, graphite and organic compounds.

  4. Evaporative cooling in ATLAS - present and future

    CERN Document Server

    Viehhauser, G; The ATLAS collaboration

    2010-01-01

    The ATLAS Inner Detector cooling system is the largest evaporative cooling system used in High Energy Physics today. During the installation and commissioning of this system many lessons had to be learned, but the system is now operating reliably, although it does not achieve all original design specifications in all its circuits. We have re-evaluated the requirements for the cooling system, in particular for the evaporation temperature, over the full ATLAS operational lifetime. We find that the critical requirement is for thermal stability at the end of the operation in the high-radiation environment. To predict this we have developed a simple thermal model of the detector modules which yields analytical expressions to evaluate the results of changes in the operating conditions. After a comparison of the revised requirements and the actual present cooling system performance we will discuss various modifications to the system which will be required for future operation. In parallel we are developing a cooling...

  5. Estimation of the residual bromine concentration after disinfection of cooling water by statistical evaluation.

    Science.gov (United States)

    Megalopoulos, Fivos A; Ochsenkuehn-Petropoulou, Maria T

    2015-01-01

    A statistical model based on multiple linear regression is developed, to estimate the bromine residual that can be expected after the bromination of cooling water. Make-up water sampled from a power plant in the Greek territory was used for the creation of the various cooling water matrices under investigation. The amount of bromine fed to the circuit, as well as other important operational parameters such as concentration at the cooling tower, temperature, organic load and contact time are taken as the independent variables. It is found that the highest contribution to the model's predictive ability comes from cooling water's organic load concentration, followed by the amount of bromine fed to the circuit, the water's mean temperature, the duration of the bromination period and finally its conductivity. Comparison of the model results with the experimental data confirms its ability to predict residual bromine given specific bromination conditions.

  6. Cooling of high-density and power electronics by means of heat pipes

    International Nuclear Information System (INIS)

    Hubbeling, L.

    1980-06-01

    This report describes how heat pipes can be used for cooling modern electronic equipment, with numerous advantages over air-cooled systems. A brief review of heat-pipe properties is given, with a detailed description of a functioning prototype. This is a single-width CAMAC unit containing high-density electronic circuits cooled by three heat pipes, and allowing a dissipation of over 120 W instead of the normal maximum of 20 W. (orig.)

  7. A stable isotope study of serpentinization and metamorphism in the Highland Border Suite, Scotland, UK

    International Nuclear Information System (INIS)

    Ikin, N.P.; Harmon, R.S.

    1983-01-01

    D/H and 18 O/ 16 O ratios have been measured for whole-rock samples and mineral separates from the mafic and ultramafic rocks of the Cambro-Ordovician Highland Border Suite. The H- and O-isotopic compositions of these rocks record individual stages in a relatively complex 500 Myr old hydrothermal/ metamorphic history. Lizardite serpentinites record a premetamorphic history and indicate that parent harzburgites, dunites, and pyroxenites were serpentinized through low-temperature interaction with meteoric waters during cooling. The other rocks of the Highland Border Suite record subsequent interaction with metamorphic fluids. Amphibolite facies hornblende schists were produced through thrust-related metamorphism of spilitic pillow lavas. During dehydration, D-enriched fluids were driven off from the spilites thus leaving the hornblende schists to equilibrate with a relatively D-depleted internal fluid reservoir. The expelled D-enriched fluids may have mixed with more typical Dalradian metamorphic waters which then exchanged with the remaining mafic rocks and lizardite serpentinites during greenschist facies regional metamorphism to produce antigorite serpentinites and greenschist metaspilites with similar H- and O-isotopic compositions. Serpentinites which have been only partially metamorphosed show intermediate H-isotopic compositions between that of metamorphic antigorite and non-metamorphic lizardite end members. (author)

  8. Arbuscular mycorrhizal symbiosis alleviates drought stress imposed on Knautia arvensis plants in serpentine soil

    Czech Academy of Sciences Publication Activity Database

    Doubková, Pavla; Vlasáková, E.; Sudová, Radka

    2013-01-01

    Roč. 370, 1-2 (2013), s. 149-161 ISSN 0032-079X R&D Projects: GA AV ČR KJB600050812 Institutional support: RVO:67985939 Keywords : arbuscular mycorrhizal fungi * drought * serpentine soil Subject RIV: EF - Botanics Impact factor: 3.235, year: 2013

  9. Is the cooling of coils of pulsed accelerators profitable?

    International Nuclear Information System (INIS)

    Neyret, G.; Parain, J.; Schnuriger, J.C.

    1960-05-01

    In this report, the authors recall how metal resistivity decreases at low temperatures, and give some indications about the power and price of cryogenic installations. They report the study of the cooling of coils in accelerators displaying an alternate gradient with a 15 GeV energy, with or without a magnetic circuit in iron. They establish that cooling does not result in a decrease in the cost price for an hour of operation. They also state that it is not even sure that this cooling would result in a dimension reduction while increasing the maximum achievable induction [fr

  10. Geochemistry and geobiology of a present-day serpentinization site in California: The Cedars

    Science.gov (United States)

    Morrill, Penny L.; Kuenen, J. Gijs; Johnson, Orion J.; Suzuki, Shino; Rietze, Amanda; Sessions, Alex L.; Fogel, Marilyn L.; Nealson, Kenneth H.

    2013-05-01

    Ultra-basic (pH 11-12) reducing (-656 to -585 mV) groundwater springs discharging from serpentinized peridotite of The Cedars, CA, were investigated for their geochemistry and geobiology. The spring waters investigated were of meteoric origin; however, geochemical modeling suggests that there were two sources of groundwater, a shallow source with sufficient contact with The Cedars' peridotite body to be altered geochemically by serpentinization, and a deeper groundwater source that not only flows through the peridotite body but was also in contact with the marine sediments of the Franciscan Subduction Complex (FSC) below the peridotite body. We propose that the groundwater discharging from lower elevations (GPS1 and CS1) reflect the geochemistry of the deeper groundwater in contact with FSC, while groundwaters discharging from springs at higher elevations (NS1 and BSC) were a mixture of the shallow peridotite-only groundwater and the deeper groundwater that has been in contact with the FSC. Cell densities of suspended microbes within these waters were extremely low. In the NS1 and BSC spring fluids, cell densities ranged from 102 to 103 cells/ml, while suspended cells at GPS were lower than 10 cells/mL. However, glass slides incubated in the BSC and GPS1 springs for 2-3 weeks were colonized by cells with densities ranging from 106 to 107 cells/cm2 attached to their surfaces. All of the springs were very low (⩽1 μM) in several essential elements and electron acceptors (e.g. nitrate/ammonium, sulfate, and phosphate) required for (microbial) growth, which is not uncommon at sites of continental serpentinization. Gases rich in N2, H2, and CH4 were exsolving from the springs. The stable carbon isotope value (δ13CCH4 = -68 ± 0.6‰) and the CH4/C2+ (>103) of methane and other gaseous hydrocarbons exsolving from NS1 were typical of microbially sourced methane, whereas the isotope values and the CH4/C2+ of BSC and CS1 springs were more enriched in 13C and had CH4/C2

  11. A novel sandwich differential capacitive accelerometer with symmetrical double-sided serpentine beam-mass structure

    International Nuclear Information System (INIS)

    Xiao, D B; Li, Q S; Hou, Z Q; Wang, X H; Chen, Z H; Xia, D W; Wu, X Z

    2016-01-01

    This paper presents a novel differential capacitive silicon micro-accelerometer with symmetrical double-sided serpentine beam-mass sensing structure and glass–silicon–glass sandwich structure. The symmetrical double-sided serpentine beam-mass sensing structure is fabricated with a novel pre-buried mask fabrication technology, which is convenient for manufacturing multi-layer sensors. The glass–silicon–glass sandwich structure is realized by a double anodic bonding process. To solve the problem of the difficulty of leading out signals from the top and bottom layer simultaneously in the sandwich sensors, a silicon pillar structure is designed that is inherently simple and low-cost. The prototype is fabricated and tested. It has low noise performance (the peak to peak value is 40 μg) and μg-level Allan deviation of bias (2.2 μg in 1 h), experimentally demonstrating the effectiveness of the design and the novel fabrication technology. (paper)

  12. Temperature Field Accurate Modeling and Cooling Performance Evaluation of Direct-Drive Outer-Rotor Air-Cooling In-Wheel Motor

    Directory of Open Access Journals (Sweden)

    Feng Chai

    2016-10-01

    Full Text Available High power density outer-rotor motors commonly use water or oil cooling. A reasonable thermal design for outer-rotor air-cooling motors can effectively enhance the power density without the fluid circulating device. Research on the heat dissipation mechanism of an outer-rotor air-cooling motor can provide guidelines for the selection of the suitable cooling mode and the design of the cooling structure. This study investigates the temperature field of the motor through computational fluid dynamics (CFD and presents a method to overcome the difficulties in building an accurate temperature field model. The proposed method mainly includes two aspects: a new method for calculating the equivalent thermal conductivity (ETC of the air-gap in the laminar state and an equivalent treatment to the thermal circuit that comprises a hub, shaft, and bearings. Using an outer-rotor air-cooling in-wheel motor as an example, the temperature field of this motor is calculated numerically using the proposed method; the results are experimentally verified. The heat transfer rate (HTR of each cooling path is obtained using the numerical results and analytic formulas. The influences of the structural parameters on temperature increases and the HTR of each cooling path are analyzed. Thereafter, the overload capability of the motor is analyzed in various overload conditions.

  13. Process and device for cooling of nuclear reactor fuel elements enclosed in a transport container

    International Nuclear Information System (INIS)

    Stiefel, M.

    1986-01-01

    In order to remove the post-decay heat of the fuel elements contained in them, transport containers for burnt-up fuel elements can be connected to a water cooling circuit. In order to avoid thermal shocks, a tenside forming foam and air are introduced into the cooling circuit before its entry into the transport container in the direction of flow. The tenside and air continue to be supplied until the temperature inside the transport container has fallen below the temperature at which the foam is destroyed. By adding tenside and air, a two phase mixture is produced, which foams greatly when it enters the transport container and which cools the fuel elements so as to protect them.(orig./HP) [de

  14. Frequency analysis for the thermal hydraulic characterization of a natural circulation circuit

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Walmir M.; Macedo, Luiz A.; Sabundjian, Gaiane; Andrade, Delvonei A.; Umbehaun, Pedro E.; Conti, Thadeu N.; Mesquita, Roberto N.; Masotti, Paulo H.; Angelo, Gabriel, E-mail: wmtorres@ipen.b, E-mail: lamacedo@ipen.b, E-mail: gdjian@ipen.b, E-mail: delvonei@ipen.b, E-mail: umbehaun@ipen.b, E-mail: tnconti@ipen.b, E-mail: , E-mail: rnavarro@ipen.b, E-mail: pmasotti@ipen.b, E-mail: gabriel.angelo@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    This paper presents the frequency analysis studies of the pressure signals from an experimental natural circulation circuit during a heating process. The main objective is to identify the characteristic frequencies of this process using fast Fourier transform. Video images are used to associate these frequencies to the observed phenomenology in the circuit during the process. Sub-cooled and saturated flow boiling, heaters vibrations, overall circuit vibrations, chugging and geysering were observed. Each phenomenon has its specific frequency associated. Some phenomena and their frequencies must be avoided or attenuated since they can cause damages to the natural circulation circuit and its components. Special operation procedures and devices can be developed to avoid these undesirable frequencies. (author)

  15. Frequency analysis for the thermal hydraulic characterization of a natural circulation circuit

    International Nuclear Information System (INIS)

    Torres, Walmir M.; Macedo, Luiz A.; Sabundjian, Gaiane; Andrade, Delvonei A.; Umbehaun, Pedro E.; Conti, Thadeu N.; Mesquita, Roberto N.; Masotti, Paulo H.; Angelo, Gabriel

    2011-01-01

    This paper presents the frequency analysis studies of the pressure signals from an experimental natural circulation circuit during a heating process. The main objective is to identify the characteristic frequencies of this process using fast Fourier transform. Video images are used to associate these frequencies to the observed phenomenology in the circuit during the process. Sub-cooled and saturated flow boiling, heaters vibrations, overall circuit vibrations, chugging and geysering were observed. Each phenomenon has its specific frequency associated. Some phenomena and their frequencies must be avoided or attenuated since they can cause damages to the natural circulation circuit and its components. Special operation procedures and devices can be developed to avoid these undesirable frequencies. (author)

  16. Study of transitory regimes in hydraulic cooling circuits

    International Nuclear Information System (INIS)

    Bonnin, Jacques; Fanelli, Michel.

    1975-01-01

    The problem of transient regimes operated voluntary or not in hydraulic circuits is posed and the risks they cause are shown. As for the case of coolant flow loss the various methods for studying the problem are examined: numerical simulation (explicit and implicit), physical model, on-site testing. The numerical methods that not yet fully satisfying or economic, are still very badly representative for hollow closures. Physical models, expensive in the case of a first facility, are not still fully representative (inconsistent similitudes, difficulties in pump picturing). Site test recordings are often a trouble for exploitation and always limited to nondestructive tests. Comparison between the three methods, already satisfying, will have to be improved to allow remedies to the over pressures due to the transients to be developed [fr

  17. Study of water radiolysis in relation with the primary cooling circuit of pressurized water reactors; Etude sur la radiolyse de l`eau en relation avec le circuit primaire de refroidissement des reacteurs nucleaires a eau sous pression

    Energy Technology Data Exchange (ETDEWEB)

    Pastina, B

    1997-07-01

    This memorandum shows a fundamental study on the water radiolysis in relation with the cooling primary circuit of PWR type reactors. The water of the primary circuit contains boric acid a soluble neutronic poison and also hydrogen that has for role to inhibit the water decomposition under radiation effect. In the aim to better understand the mechanism of dissolved hydrogen action and to evaluate the impact of several parameters on this mechanism, aqueous solutions with boric acid and hydrogen have been irradiated in a experimental nuclear reactor, at 30, 100 and 200 Celsius degrees. It has been found that, with hydrogen, the water decomposition under irradiation is a threshold phenomenon in function of the ratio between the radiation flux `1` B(n, )`7 Li and the gamma flux. When this ratio become too high, the number of radicals is not sufficient to participate at the chain reaction, and then water is decomposed in O{sub 2} and H{sub 2}O{sub 2} in a irreversible way. The temperature has a beneficial part on this mechanism. The iron ion and the copper ion favour the water decomposition. (N.C.). 83 refs.

  18. MULTIFUNCTIONAL SOLAR SYSTEMS FOR HEATING AND COOLING

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2010-12-01

    Full Text Available The basic circuits of multifunctional solar systems of air drainage, heating (hot water supply and heating, cooling and air conditioning are developed on the basis of open absorption cycle with a direct absorbent regeneration. Basic decisions for new generation of gas-liquid solar collectors are developed. Heat-mass-transfer apparatus included in evaporative cooling system, are based on film interaction of flows of gas and liquid and in them, for the creation of nozzle, multi-channel structures from polymeric materials and porous ceramics are used. Preliminary analysis of multifunctional systems possibilities is implemented.

  19. The symbiosis with arbuscular mycorrhizal fungi contributes to plant tolerance to serpentine edaphic stress

    Czech Academy of Sciences Publication Activity Database

    Doubková, Pavla; Suda, Jan; Sudová, Radka

    2012-01-01

    Roč. 4, č. 1 (2012), s. 56-64 ISSN 0038-0717 R&D Projects: GA AV ČR KJB600050812 Institutional research plan: CEZ:AV0Z60050516 Keywords : serpentine syndrome * arbuscular mycorrhizal fungi * reciprocal transplant experiment Subject RIV: EF - Botanics Impact factor: 3.654, year: 2012

  20. Si-Metasomatism During Serpentinization of Jurassic Ultramafic Sea-floor: a Comparative Study

    Science.gov (United States)

    Vogel, M.; Frueh-Green, G. L.; Boschi, C.; Schwarzenbach, E. M.

    2014-12-01

    The Bracco-Levanto ophiolitic complex (northwestern Italy) represents one of the largest and better-exposed ophiolitic successions in the Northern Apennines. It is considered to be a fragment of heterogeneous Jurassic lithosphere that records tectono-magmatic and alteration histories similar to those documented along the Mid-Atlantic Ridge (MAR), such as at the 15°20'N area and the Atlantis Massif at 30°N. Structural and petrological studies on these rocks provide constraints on metamorphic/deformation processes during formation and hydrothermal alteration of the Jurassic oceanic lithosphere. We present a petrological and geochemical study of serpentinization processes and fluid-rock interaction in the Bracco-Levanto ophiolitic complex and compare these to published data from modern oceanic hydrothermal systems, such as the Lost City hydrothermal field hosted in serpentinites on the Atlantis Massif. Major element and mineral compositional data allow us to distinguish a multiphase history of alteration characterized by: (1) widespread Si-metasomatism during progressive serpentinization, and (2) multiple phases of veining and carbonate precipitation associated with circulation of seawater in the shallow ultramafic-dominated portions of the Jurassic seafloor, resulting in the formation of ophicalcites. In detail, regional variations in Si, Mg and Al content are observed in zones of ophicalcite formation, indicating metasomatic reactions and Si-Al transport during long-lived fluid-rock interaction and channelling of hydrothermal fluids. Rare earth element and isotopic analysis indicate that the Si-rich fluids are derived from alteration of pyroxenes to talc and tremolite in ultramafic rocks at depth. Comparison with serpentinites from the Atlantis Massif and 15°20'N indicates a similar degree of Si-enrichment in the modern seafloor and suggests that Si-metasomatism may be a fundamental process associated with serpentinization at slow-spreading ridge environments

  1. Simplified thermal-hydraulic analysis of single phase natural circulation circuit with two heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Pinheiro, Larissa Cunha; Su, Jian, E-mail: larissa@lasme.coppe.ufrj.br, E-mail: sujian@lasme.coppe.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenhraria Nuclear; Cotta, Renato Machado, E-mail: cotta@mecanica.coppe.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (POLI/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Mecanica

    2015-07-01

    Single phase natural circulation circuits composed of two convective heat exchangers and connecting tubes are important for the passive heat removal from spent fuel pools (SFP). To keep the structural integrity of the stored spent fuel assemblies, continuously cooling has to be provided in order to avoid increase at the pool temperature and subsequent uncovering of the fuel and enhanced reaction between water and metal releasing hydrogen. Decay heat can achieve considerably high amounts of energy e.g. in the AP1000, considering the emergency fuel assemblies, the maximum heat decay will reach 13 MW in the 15th day (Westinghouse Electric Company, 2010). A highly efficient alternative to do so is by means of natural circulation, which is cost-effective compared to active cooling systems and is inherently safer since presents less associated devices and no external work is required. Many researchers have investigated safety and stability aspects of natural circulation loops (NCL). However, there is a lack of literature concerning the improvement of NCL through a standard unified methodology, especially for natural circulation circuits with two heat exchangers. In the present study, a simplified thermal-hydraulic analysis of single phase natural circulation circuit with two heat exchanges is presented. Relevant dimensionless key groups were proposed to for the design and safety analysis of a scaled NCL for the cooling of spent fuel storage pool with convective cooling and heating. (author)

  2. Cooling system for the IFMIF-EVEDA radiofrequency system

    International Nuclear Information System (INIS)

    Perez Pichel, G. D.

    2012-01-01

    The IFMIF-EVEDA project consists on an accelerator prototype that will be installed at Rokkasho (Japan). Through CIEMAT, that is responsible of the development of many systems and components. Empresarios Agrupados get the responsibility of the detailed design of the cooling system for the radiofrequency system (RF system) that must feed the accelerator. the RF water cooling systems is the water primary circuit that provides the required water flow (with a certain temperature, pressure and water quality) and also dissipates the necessary thermal power of all the radiofrequency system equipment. (Author) 4 refs.

  3. Estimation of the amount of surface contamination of a water cooled nuclear reactor by cooling water analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, G. [KFKI Atomic Energy Research Institute, P.O. Box 49, Budapest H-1525 (Hungary)]. E-mail: nagyg@sunserv.kfki.hu; Somogyi, A. [KFKI Atomic Energy Research Institute, P.O. Box 49, Budapest H-1525 (Hungary); Patek, G. [Paks Nuclear Power Plant, P.O. Box 71, Paks H-7031 (Hungary); Pinter, T. [Paks Nuclear Power Plant, P.O. Box 71, Paks H-7031 (Hungary); Schiller, R. [KFKI Atomic Energy Research Institute, P.O. Box 49, Budapest H-1525 (Hungary)

    2007-06-15

    Calculations, based upon on-the-spot measurements, were performed to estimate the contamination of NPP primary circuit and spent fuel storage pool solid surfaces via the composition of the cooling water in connection with a non-nuclear incident in the Paks NPP. Thirty partially burnt-up fuel element bundles were damaged during a cleaning process, an incident which resulted in the presence of fission products in the cooling water of the cleaning tank (CT) situated in a separate pool (P1). Since this medium was in contact for an extended period of time with undamaged fuel elements to be used later and also with other structural materials of the spent fuel storage pool (SP), it was imperative to assess the surface contamination of these latter ones with a particular view to the amount of fission material. In want of direct methods, one was restricted to indirect information which rested mainly on the chemical and radiochemical data of the cooling water. It was found that (i) the most important contaminants were uranium, plutonium, cesium and cerium; (ii) after the isolation of P1 and SP and an extended period of filtering the only important contaminants were uranium and plutonium; (iii) the surface contamination of the primary circuit (PC) was much lower than that of either SP or P1; (iv) some 99% of the contamination was removed from the water by the end of the filtering process.

  4. Physiological and genomic features of highly alkaliphilic hydrogen-utilizing Betaproteobacteria from a continental serpentinizing site

    NARCIS (Netherlands)

    Suzuki, S.; Kuenen, J.G.; Schipper, K.; van der Velde, S.; Ishii, S.; Wu, A.; Sorokin, D.Y.; Tenney, A.; Meng, X.Y.; Morrill, P.L.; Kamagata, Y.; Muyzer, G.; Nealson, K.H.

    2014-01-01

    Serpentinization, or the aqueous alteration of ultramafic rocks, results in challenging environments for life in continental sites due to the combination of extremely high pH, low salinity and lack of obvious electron acceptors and carbon sources. Nevertheless, certain Betaproteobacteria have been

  5. Serpentine endophytic bacterium Pseudomonas azotoformans ASS1 accelerates phytoremediation of soil metals under drought stress.

    Science.gov (United States)

    Ma, Ying; Rajkumar, Mani; Moreno, António; Zhang, Chang; Freitas, Helena

    2017-10-01

    This study evaluates the potential of serpentine endophytic bacterium to foster phytoremediation efficiency of Trifolium arvense grown on multi-metal (Cu, Zn and Ni) contaminated soils under drought stress. A drought resistant endophytic bacterial strain ASS1 isolated from the leaves of Alyssum serpyllifolium grown in serpentine soils was identified as Pseudomonas azotoformans based on biochemical tests and partial 16S rRNA gene sequencing. P. azotoformans ASS1 possessed abiotic stress resistance (heavy metals, drought, salinity, antibiotics and extreme temperature) and plant growth promoting (PGP) properties (phosphate solubilization, nitrogen fixation, production of 1-aminocyclopropane-1-carboxylate deaminase, siderophore and ammonia). Inoculation of T. arvense with ASS1 considerably increased the plant biomass and leaf relative water content in both roll towel assay and pot experiments in the absence and presence of drought stress (DS). In the pot experiments, ASS1 greatly enhanced chlorophyll content, catalase, peroxidase, superoxide dismutase activities, and proline content (only in the absence of drought) in plant leaves, whereas they decreased the concentrations of malondialdehyde. Irrespective of water stress, ASS1 significantly improved accumulation, total removal, bio-concentration factor and biological accumulation coefficient of metals (Cu, Zn and Ni), while decreased translocation factors of Cu. The effective colonization and survival in the rhizosphere and tissue interior assured improved plant growth and successful metal phytoremediation under DS. These results demonstrate the potential of serpentine endophytic bacterium ASS1 for protecting plants against abiotic stresses and helping plants to thrive in semiarid ecosystems and accelerate phytoremediation process in metal polluted soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. The primary circuit of the dragon high temperature reactor experiment

    International Nuclear Information System (INIS)

    Simon, R.

    2005-01-01

    The 20 MWth Dragon Reactor Experiment was the first HTGR (High Temperature Gas-cooled Reactor) with coated particle fuel. Its purpose was to test fuel and materials for the High Temperature Reactor programmes pursued in Europe 40 years ago. This paper describes the design and construction of the primary (helium) circuit. It summarizes the main design objectives, lists the performance data and explains the flow paths of the heat removal and helium purification systems. The principal circuit accidents postulated are discussed and the choice of the main construction materials is given. (author)

  7. Magnetic properties of variably serpentinized peridotites and their implication for the evolution of oceanic core complexes

    NARCIS (Netherlands)

    Maffione, M.; Morris, A.; Plümper, O.|info:eu-repo/dai/nl/37155960X; van Hinsbergen, D.J.J.|info:eu-repo/dai/nl/269263624

    Serpentinization of ultramafic rocks during hydrothermal alteration at mid-ocean ridges profoundly changes the physical, chemical, rheological, and magnetic properties of the oceanic lithosphere. There is renewed interest in this process following the discovery of widespread exposures of

  8. Secondary process for securing emergency cooling in nuclear facilities

    International Nuclear Information System (INIS)

    Bachl, H.

    1975-01-01

    An auxiliary process for securing the emergency cooling of nuclear power plants is described which is characterized in that a two-material heat power auxiliary process is connected at the cold end of the cooling circuit to a main heat power process to obtain mechanical energy from thermal, which in normal operation works as a cold-absorption process, but with failure of the main process changes to a heat power process with full evaporation and subsequent superheating of the two-materials mixture. (RW/LH) [de

  9. Carbonate control of H2 and CH4 production in serpentinization systems at elevated P-Ts

    Science.gov (United States)

    Jones, L. Camille; Rosenbauer, Robert; Goldsmith, Jonas I.; Oze, Christopher

    2010-01-01

    Serpentinization of forsteritic olivine results in the inorganic synthesis of molecular hydrogen (H2) in ultramafic hydrothermal systems (e.g., mid-ocean ridge and forearc environments). Inorganic carbon in those hydrothermal systems may react with H2 to produce methane (CH4) and other hydrocarbons or react with dissolved metal ions to form carbonate minerals. Here, we report serpentinization experiments at 200°C and 300 bar demonstrating Fe2+ being incorporated into carbonates more rapidly than Fe2+ oxidation (and concomitant H2 formation) leading to diminished yields of H2 and H2-dependent CH4. In addition, carbonate formation is temporally fast in carbonate oversaturated fluids. Our results demonstrate that carbonate chemistry ultimately modulates the abiotic synthesis of both H2 and CH4 in hydrothermal ultramafic systems and that ultramafic systems present great potential for CO2-mineral sequestration.

  10. Numerical simulation of the transient thermal-hydraulic behaviour of the ITER blanket cooling system under the draining operational procedure

    Energy Technology Data Exchange (ETDEWEB)

    Di Maio, P.A. [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo Viale delle Scienze, 90128 Palermo (Italy); Dell’Orco, G.; Furmanek, A. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Garitta, S. [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo Viale delle Scienze, 90128 Palermo (Italy); Merola, M.; Mitteau, R.; Raffray, R. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Spagnuolo, G.A. [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo Viale delle Scienze, 90128 Palermo (Italy); Vallone, E., E-mail: eug.vallone@gmail.com [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo Viale delle Scienze, 90128 Palermo (Italy)

    2015-10-15

    Highlights: • ITER blanket cooling system hydraulic behaviour is studied under draining transient. • A computational approach based on the finite volume method has been followed. • Draining efficiency has been assessed in term of transient duration and residual water. • Transient duration ranges from ∼40 to 50 s, under the reference draining scenario. • Residual water is predicted to range from few tens of gram up to few kilograms. - Abstract: Within the framework of the research and development activities supported by the ITER Organization on the blanket system issues, an intense analysis campaign has been performed at the University of Palermo with the aim to investigate the thermal-hydraulic behaviour of the cooling system of a standard 20° sector of ITER blanket during the draining transient operational procedure. The analysis has been carried out following a theoretical-computational approach based on the finite volume method and adopting the RELAP5 system code. In a first phase, attention has been focused on the development and validation of the finite volume models of the cooling circuits of the most demanding modules belonging to the standard blanket sector. In later phase, attention has been put to the numerical simulation of the thermal-hydraulic transient behaviour of each cooling circuit during the draining operational procedure. The draining procedure efficiency has been assessed in terms of both transient duration and residual amount of coolant inside the circuit, observing that the former ranges typically between 40 and 120 s and the latter reaches at most ∼8 kg, in the case of the cooling circuit of twinned modules #6–7. Potential variations to operational parameters and/or to circuit lay-out have been proposed and investigated to optimize the circuit draining performances. In this paper, the set-up of the finite volume models is briefly described and the key results are summarized and critically discussed.

  11. Investigation of thermohydraulic parameter variations in operating conditions of Bilibino NPP CPS cooling circuit

    International Nuclear Information System (INIS)

    Baranaev, Yu.D.; Koz'menkova, V.V.; Parafilo, L.M.

    2015-01-01

    In consequence of activities on uncovering the reasons for through faults formation in cooling tubes of reactor control and protection system (CPS) channels of Bilibino-2 reactor the conclusion is made that corrosion failure development takes place against the backdrop of periodic increase of total moisture in reactor space at transient and standby modes at top of cooling tubes of CPS channels. Formation of corrosion defects in cooling tubes of four CPS channels of unit 2 in 2011-2012 is specific factor for this plant unit and do not effect on operation of other plant units. It is pointed out that ingress of moisture into gas system of the reactor is the critical factor providing integrity of structure elements of EhPG-6 reactor core cooling system. This fact agrees nicely with the results obtained during operation AM reactor of the First NPP [ru

  12. Toxic element profiles in selected medicinal plants growing on serpentines in Bulgaria.

    Science.gov (United States)

    Pavlova, Dolja; Karadjova, Irina

    2013-12-01

    Populations of medicinal plants growing on serpentines and their respective soils were analyzed for Fe, Ni, Mn, Cr, Co, Cd, Cu, Zn, and Pb using inductively coupled plasma atomic emission spectrometry. Aqua regia extraction and 0.43 M acetic acid extraction were used for the quantification of pseudototal and bioavailable fractions, respectively, of elements in soil and nitric acid digestion for determination of total element content in plants. Screening was performed to (1) document levels of toxic metals in herbs extensively used in preparation of products and standardized extracts, (2) compare accumulation abilities of ferns and seed plants, and (3) estimate correlations between metal content in plants and their soils. The toxic element content of plants varied from site to site on a large scale. The concentrations of Fe and Ni were elevated while those of Cu, Zn, and Pb were close to average values usually found in plants. The highest concentrations for almost all elements were measured in both Teucrium species. Specific differences in metal accumulation between ferns and seed plants were not recorded. The investigated species are not hyperaccumulators but can accumulate toxic elements, in some cases exceeding permissible levels proposed by the World Health Organization and European Pharmacopoeia. The harvesting of medicinal plants from serpentines could be hazardous to humans.

  13. Redox flow batteries with serpentine flow fields: Distributions of electrolyte flow reactant penetration into the porous carbon electrodes and effects on performance

    Science.gov (United States)

    Ke, Xinyou; Prahl, Joseph M.; Alexander, J. Iwan D.; Savinell, Robert F.

    2018-04-01

    Redox flow batteries with flow field designs have been demonstrated to boost their capacities to deliver high current density and power density in medium and large-scale energy storage applications. Nevertheless, the fundamental mechanisms involved with improved current density in flow batteries with serpentine flow field designs have been not fully understood. Here we report a three-dimensional model of a serpentine flow field over a porous carbon electrode to examine the distributions of pressure driven electrolyte flow penetrations into the porous carbon electrodes. We also estimate the maximum current densities associated with stoichiometric availability of electrolyte reactant flow penetrations through the porous carbon electrodes. The results predict reasonably well observed experimental data without using any adjustable parameters. This fundamental work on electrolyte flow distributions of limiting reactant availability will contribute to a better understanding of limits on electrochemical performance in flow batteries with serpentine flow field designs and should be helpful to optimizing flow batteries.

  14. Turbulence characteristics and mixing performances of viscoelastic fluid flow in a serpentine microchannel

    International Nuclear Information System (INIS)

    Tatsumi, K; Takeda, Y; Nakabe, K; Suga, K

    2011-01-01

    Flow velocity measurement and visualization using particle image velocimetry and fluorescent dye were carried out for a viscoelastic fluid flow in a serpentine microchannel for the purpose to quantitatively evaluate the unsteady flow characteristics that is observed even under very low Reynolds number regime due to the combined effect of the viscoelastic fluid properties and the channel shape. Sucrose water solution (Newtonian fluid) and the polyacrylamide-sucrose water solution (viscoelastic fluid) were used as working fluids. The mixing performance markedly increased when the Reynolds number exceeded a certain value in the polyacrylamide solution case. The single-point, cross-sectional and two-dimensional velocity distributions showed that low frequency fluctuation was produced in the polyacrylamide solution case. Particularly large fluctuation in the channel spanwise direction was observed in the upstream area of the serpentine channel. On the other hand, the amplitude of the fluctuation decreased in the downstream region. The fluctuation in the upstream region is believed to be generated by the flow instability at the curved part of the channel, while the fluctuations in the downstream area were attributed to the local instability and the vortices provided from the upstream region.

  15. Comparison of immersed liquid and air cooling of NASA's Airborne Information Management System

    Science.gov (United States)

    Hoadley, A. W.; Porter, A. J.

    1992-01-01

    The Airborne Information Management System (AIMS) is currently under development at NASA Dryden Flight Research Facility. The AIMS is designed as a modular system utilizing surface mounted integrated circuits in a high-density configuration. To maintain the temperature of the integrated circuits within manufacturer's specifications, the modules are to be filled with Fluorinert FC-72. Unlike ground based liquid cooled computers, the extreme range of the ambient pressures experienced by the AIMS requires the FC-72 be contained in a closed system. This forces the latent heat absorbed during the boiling to be released during the condensation that must take within the closed module system. Natural convection and/or pumping carries the heat to the outer surface of the AIMS module where the heat transfers to the ambient air. This paper will present an evaluation of the relative effectiveness of immersed liquid cooling and air cooling of the Airborne Information Management System.

  16. Secondary coolant circuit for liquid-metal cooled reactor and steam generator for such a circuit

    International Nuclear Information System (INIS)

    Brachet, A.; Figuet, J.; Guidez, J.; Lions, N.; Traiteur, R.; Zuber, T.

    1984-01-01

    An upper buffer tank and downstream buffer tank are disposed inside the steam generators. The downstream briffer tank is annular and it surrounds and communicates with a zone of the steam generator through which the liquid metal flows towards the bottom between the exchange zone and the outlet nozzle. The pressure of the inert gas blanket in the downstream buffer volume is more important than this one in the upper buffer volume. The invention applies to fast neutron nuclear reactor cooled by sodium [fr

  17. The integration of cryogenic cooling systems with superconducting electronic systems

    International Nuclear Information System (INIS)

    Green, Michael A.

    2003-01-01

    The need for cryogenic cooling has been critical issue that has kept superconducting electronic devices from reaching the market place. Even though the performance of the superconducting circuit is superior to silicon electronics, the requirement for cryogenic cooling has put the superconducting devices at a disadvantage. This report will talk about the various methods for refrigerating superconducting devices. Cryocooler types will be compared for vibration, efficiency, and cost. Some solutions to specific problems of integrating cryocoolers to superconducting devices are presented.

  18. A new modified-serpentine flow field for application in high temperature polymer electrolyte fuel cell

    DEFF Research Database (Denmark)

    Singdeo, Debanand; Dey, Tapobrata; Gaikwad, Shrihari

    2017-01-01

    field design is proposed and its usefulness for the fuel cell applications are evaluated in a high-temperature polymer electrolyte fuel cell. The proposed geometry retains some of the features of serpentine flow field such as multiple bends, while modifications are made in its in-plane flow path...

  19. Chromite and other mineral deposits in serpentine rocks of the Piedmont Upland, Maryland, Pennsylvania, and Delaware

    Science.gov (United States)

    Pearre, Nancy C.; Heyl, Allen V.

    1960-01-01

    The Piedmont Upland in Maryland, Pennsylvania, and Delaware is about 160 miles long and at the most 50 miles wide. Rocks that underlie the province are the Baltimore gneiss of Precambrian age and quartzite, gneiss, schist, marble, phyllite, and greenstone, which make up the Glenarm series of early Paleozoic (?) age. These are intruded by granitic, gabbroic, and ultramaflc igneous rocks. Most of the ultramaflc rocks, originally peridotite, pyroxenite, and dunite, have been partly or completely altered to serpentine and talc; they are all designated by the general term serpentine. The bodies of serpentine are commonly elongate and conformable with the enclosing rocks. Many have been extensively quarried for building, decorative, and crushed stone. In addition, chromite, titaniferous magnetite, rutile, talc and soapstone, amphibole asbestos, magnesite, sodium- rich feldspar (commercially known as soda spar), and corundum have been mined or prospected for in the serpentine. Both high-grade massive chromite and lower grade disseminated chromite occur in very irregular and unpredictable form in the serpentine, and placer deposits of chromite are in and near streams that drain areas underlain by serpentine. A group of unusual minerals, among them kammererite, are typical associates of high-grade massive chromite but are rare in lower grade deposits. Chromite was first discovered in the United States at Bare Hills, Md., around 1810. Between 1820 and 1850, additional deposits were discovered and mined in Maryland and Pennsylvania, including the largest deposit of massive chromite ever found in the United States the Wood deposit, in the State Line district. A second period of extensive chromite mining came during the late 1860's and early 1870's. Production figures are incomplete and conflicting. Estimates from the available data indicate that the aggregate production from 27 of 40 known mines before 1900 totaled between 250,000 and 280,000 tons of lode-chromite ore

  20. Toward sub-Kelvin resistive cooling and non destructive detection of trapped non-neutral electron plasma

    Science.gov (United States)

    Di Domizio, S.; Krasnický, D.; Lagomarsino, V.; Testera, G.; Vaccarone, R.; Zavatarelli, S.

    2015-01-01

    A resonant circuit tuned to a particular frequency of the motion of charged particles stored in a Penning trap and connected to a low noise amplifier allows, at the same time, cooling and non destructive detection of the particles. Its use is widely diffused when single or few particles are stored near the centre of a hyperbolic Penning trap. We present a consistent model that predicts the shape of the induced signal when the tuned circuit is used to detect and cool the axial motion of a cold non neutral plasma stored in an open-ended cylindrical Penning trap. The model correctly accounts for the not negligible axial plasma size. We show that the power spectrum of the signal measured across the tuned circuit provides information about the particle number and insights about the plasma temperature. We report on the design of a HEMT-based cryogenic amplifier working at 14.4 MHz and 4.2 K and the results of the noise measurements. We have measured a drain current noise in the range from 6 to 17 pA/√Hz, which corresponds to an increase of the tuned circuit equivalent temperature of at maximum 0.35 K. The cryogenic amplifier has a very low power consumption from few tens to few hundreds of μW corresponding to a drain current in the range 100-800 μ A. An additional contribution due to the gate noise has been identified when the drain current is below 300 μA above that value an upper limit of the increase of the equivalent tuned circuit temperature due to this contribution of 0.02 K has been obtained. These features make the tuned circuit connected to this amplifier a promising device for detecting and cooling the axial motion of an electron plasma when the Penning trap is mounted inside a dilution refrigerator.

  1. New insight on Li and B isotope fractionation during serpentinization derived from batch reaction investigations

    Science.gov (United States)

    Hansen, Christian T.; Meixner, Anette; Kasemann, Simone A.; Bach, Wolfgang

    2017-11-01

    Multiple batch experiments (100 °C, 200 °C; 40 MPa) were conducted, using Dickson-type reactors, to investigate Li and B partitioning and isotope fractionation between rock and water during serpentinization. We reacted fresh olivine (5 g; Fo90; [B] = anti-correlated with temperature, we argue for an overall attenuation of the isotopic effect through changes in B speciation in saline solutions (NaB(OH)4(aq) and B(OH)3Cl-) as well as variable B fixation and fractionation for different serpentinization product minerals (brucite, chrysotile). Breakdown of the Li-rich olivine and limited Li incorporation into product mineral phases resulted in an overall lower Li content of the final solid phase assemblage at 200 °C ([Li]final_200 °C = 0.77 μg/g; DS/FLi200 °C = 1.58). First order changes in Li isotopic compositions were defined by mixing of two isotopically distinct sources i.e. the fresh olivine and the fluid rather than by equilibrium isotope fraction. At 200 °C primary olivine is dissolved, releasing its Li budget into the fluid which shifts towards a lower δ7LiF of +38.62‰. Newly formed serpentine minerals (δ7LiS = +30.58‰) incorporate fluid derived Li with a minor preference of the 6Li isotope. At 100 °C Li enrichment of secondary phases exceeded Li release by olivine breakdown ([Li]final_100 °C = 2.10 μg/g; DS/FLi100 °C = 11.3) and it was accompanied by preferential incorporation of heavier 7Li isotope that might be due to incorporation of a 7Li enriched fluid fraction into chrysotile nanotubes.

  2. New evidence for the serpentinization of the Palaeozoic basement of southeastern Sicily from joint 3-D seismic velocity and attenuation tomography

    Science.gov (United States)

    Giampiccolo, E.; Brancato, A.; Manuella, F. C.; Carbone, S.; Gresta, S.; Scribano, V.

    2017-12-01

    In this study, we derived the first 3-D P-wave seismic attenuation images (QP) as well as new 3-D VP and VP/VS models for the crust in southeastern Sicily. We used a large data set of local seismic events occurring in the time span 1994-2013. The results of this tomographic study have important implications on the seismic behaviour of the region. Based on velocity and attenuation images, we identified distinct volumes characterized by different fluid content, which correlate well with seismicity distribution. Moreover, the obtained velocity and attenuation tomographies help us to provide a more complete picture of the crustal structure of the area. High VP, high QP and high VP/VS values have been obtained in the crustal basement, below a depth of 8 km, and may be interpreted as due to the presence of serpentinized peridotites. Accordingly, the new model for the degree of serpentinization, retrieved from VP values, shows that the basement has an average serpentinization value of 96 ± 3 vol.% at 8 km, decreasing to 44 ± 5 vol.% at about 18-20 km.

  3. Microjet flow control in an ultra-compact serpentine inlet

    Directory of Open Access Journals (Sweden)

    Da Xingya

    2015-10-01

    Full Text Available Microjets are used to control the internal flow to improve the performance of an ultra-compact serpentine inlet. A highly offset serpentine inlet with length-to-diameter ratio of 2.5 is designed and static tests are conducted to analyze the internal flow characteristics in terms of pressure recovery, distortion and flow separation. Flow separation is encountered in the second S-turn, and two strong counter-rotating vortices are formed at the aerodynamic interface plane (AIP face which occupy a quarter of the outlet area and result in severe pressure loss and distortion. A flow control model employing a row of microjets in the second turn is designed based on the internal flow characteristics and simplified CFD simulations. Flow control tests are conducted to verify the control effectiveness and understand the characteristics as a function of inlet throat Mach number, injection mass flow ratio, jet Mach number and momentum coefficient. At all test Mach numbers, microjet flow control (MFC effectively improves the recovery and reduces the distortion intensity. Between inlet throat Mach number 0.2 and 0.5, the strong flow separation in the second S-turn is suppressed at an optimum jet flow ratio of less than 0.65%, resulting in a maximum improvement of 4% for pressure recovery coefficient and a maximum decrease of 75% for circumferential distortion intensity at cruise. However, in order to suppress the flow separation, the injection rate should retain in an effective range. When the injection rate is higher than this range, the flow is degraded and the distortion contour is changed from 90° circumferential distortion pattern to 180° circumferential distortion pattern. Detailed data analysis shows that this optimum flow ratio depends on inlet throat Mach number and the momentum coefficient affects the control effectiveness in a dual stepping manner.

  4. Short Circuit Tests First Step of LHC Hardware Commissioning Completion

    CERN Document Server

    Barbero-Soto, E; Bordry, Frederick; Casas Lino, M P; Coelingh, G J; Cumer, G; Dahlerup-Petersen, K; Guillaume, J C; Inigo-Golfin, J; Montabonnet, V; Nisbet, D; Pojer, M; Principe, R; Rodríguez-Mateos, F; Saban, R; Schmidt, R; Thiesen, H; Vergara-Fernández, A; Zerlauth, M; Castaneda Serra, A; Romera Ramirez, I

    2008-01-01

    For the two counter rotating beams in the Large Hadron Collider (LHC) about 8000 magnets (main dipole and quadrupole magnets, corrector magnets, separation dipoles, matching section quadrupoles etc.) are powered in about 1500 superconducting electrical circuits. The magnets are powered by power converters that have been designed for the LHC with a current between 60 and 13000A. Between October 2005 and September 2007 the so-called Short Circuit Tests were carried-out in 15 underground zones where the power converters of the superconducting circuits are placed. The tests aimed to qualify the normal conducting equipments of the circuits such as power converters and normal conducting high current cables. The correct operation of interlock and energy extraction systems was validated. The infrastructure systems including AC distribution, water and air cooling and the control systems was also commissioned. In this paper the results of the two year test campaign are summarized with particular attention to problems e...

  5. An environmental survey of Serpentine Hot Springs: Geology, hydrology, geochemistry, and microbiology

    Science.gov (United States)

    Nordstrom, D. Kirk; Hasselbach, Linda; Ingebritsen, Steven E.; Skorupa, Dana; McCleskey, R. Blaine; McDermott, Timothy R.

    2015-01-01

    Serpentine Hot Springs is the most visited site in the Bering Land Bridge National Preserve. The hot springs have traditionally been used by the Native people of the Seward Peninsula for religious, medicinal and spiritual purposes and continue to be used in many of the same ways by Native people today. The hot springs are also popular with non-Native users from Nome and other communities, recreational users and pilots from out of the area, and hunters and hikers.

  6. Management of the Post-Shuttle Extravehicular Mobility Unit (EMU) Water Circuits

    Science.gov (United States)

    Steele, John W.; Etter, David; Rector, Tony; Hill, Terry; Wells, Kevin

    2011-01-01

    The EMU incorporates two separate water circuits for the rejection of metabolic heat from the astronaut and the cooling of electrical components. The first (the Transport Water Loop) circulates in a semi-closed-loop manner and absorbs heat into a Liquid Coolant and Ventilation Garment (LCVG) warn by the astronaut. The second (the Feed Water Loop) provides water to a cooling device (Sublimator) with a porous plate, and that water subsequently sublimates to space vacuum. The cooling effect from the sublimation of this water translates to a cooling of the LCVG water that circulates through the Sublimator. Efforts are underway to streamline the use of a water processing kit (ALCLR) that is being used to periodically clean and disinfect the Transport Loop Water. Those efforts include a fine tuning of the duty cycle based on a review of prior performance data as well as an assessment of a fixed installation of this kit into the EMU backpack or within on-orbit EMU interface hardware. Furthermore, testing is being conducted to ensure compatibility between the International Space Station (ISS) Water Processor Assembly (WPA) effluent and the EMU Sublimator as a prelude to using the WPA effluent as influent to the EMU Feed Water loop. This work is undertaken to reduce the crew-time and logistics burdens for the EMU, while ensuring the long-term health of the EMU water circuits for a post-Shuttle 6-year service life.

  7. The circuit of polychromator for Experimental Advanced Superconducting Tokamak edge Thomson scattering diagnostic

    International Nuclear Information System (INIS)

    Zang, Qing; Zhao, Junyu; Chen, Hui; Li, Fengjuan; Hsieh, C. L.

    2013-01-01

    The detector circuit is the core component of filter polychromator which is used for scattering light analysis in Thomson scattering diagnostic, and is responsible for the precision and stability of a system. High signal-to-noise and stability are primary requirements for the diagnostic. Recently, an upgraded detector circuit for weak light detecting in Experimental Advanced Superconducting Tokamak (EAST) edge Thomson scattering system has been designed, which can be used for the measurement of large electron temperature (T e ) gradient and low electron density (n e ). In this new circuit, a thermoelectric-cooled avalanche photodiode with the aid circuit is involved for increasing stability and enhancing signal-to-noise ratio (SNR), especially the circuit will never be influenced by ambient temperature. These features are expected to improve the accuracy of EAST Thomson diagnostic dramatically. Related mechanical construction of the circuit is redesigned as well for heat-sinking and installation. All parameters are optimized, and SNR is dramatically improved. The number of minimum detectable photons is only 10

  8. Experimental study on the proton stochastic cooling in the NAP-M

    International Nuclear Information System (INIS)

    Dement'ev, E.N.; Zinevich, N.I.; Medvedko, A.S.; Parkhomchuk, V.V.; Pestrikov, D.V.

    1982-01-01

    Results of experiments on stochastic cooling of proton beam energy spread at NAP-M storage ring are given. Dependences of dampling decrements on beam phase density, numbers of working harmonics and values of amplification factor of feedback circuit have been studied. A differential sensor made in the form of two end-disengaged strip lines is used as a signal source for the feedback circuit. Two cooling systems were investigated: a wide-band system consisting of a sensor and correcting element and a system with a resonance filter at the input. The correcting element is made in the form of four 50 Ohm consistent strip lines. Coaxial cable sections forming with sensor strip lines two resonance lines end-closed with low input resistances of amplifiers were used as a filter. Stable spread in the beam was determined with electronics hums. Coherent beam stability related to its shift in measuring pick up electrode is detected. Method limitations due to electronics noise and collective effects in intense beams are discussed. Cooling time of low-intense particle beam equal to 150 s when decreasing spread from 3x10 - 4 to 2x10 - 4 has been determined

  9. PH adjustment of power plant cooling water with flue gas/fly ash

    Science.gov (United States)

    Brady, Patrick V.; Krumhansl, James L.

    2015-09-22

    A system including a vessel including a heat source and a flue; a turbine; a condenser; a fluid conduit circuit disposed between the vessel, the turbine and the condenser; and a diverter coupled to the flue to direct a portion of an exhaust from the flue to contact with a cooling medium for the condenser water. A method including diverting a portion of exhaust from a flue of a vessel; modifying the pH of a cooling medium for a condenser with the portion of exhaust; and condensing heated fluid from the vessel with the pH modified cooling medium.

  10. Sodium-cooled nuclear reactor

    International Nuclear Information System (INIS)

    Hammers, H.W.

    1982-01-01

    The invention concerns a sodium-cooled nuclear reactor, whose reactor tank contains the primary circuit, shielding surrounding the reactor core and a primary/secondary heat exchanger, particularly a fast breeder reactor on the module principle. In order to achieve this module principle it is proposed to have electromagnetic circulating pumps outside the reactor tank, where the heat exchanger is accomodated in an annular case above the pumps. This case has several openings at the top end to the space above the reactor core, some smaller openings in the middle to the same space and is connected at the bottom to an annular space between the tank wall and the reactor core. As a favoured variant, it is proposed that the annular electromagnetic pumps should be arranged concentrically to the reactor tank, where there is an annual duct on the inside of the reactor tank. In this way the sodium-cooled nuclear reactor is made suitable as a module with a large number of such elements. (orig.) [de

  11. Active cooling of a down hole well tractor

    DEFF Research Database (Denmark)

    Soprani, Stefano; Nesgaard, Carsten

    Wireline interventions in high temperature wells represent one of today’s biggest challenges for the oil and gas industry. The high wellbore temperatures, which can reach 200 °C, drastically reduce the life of the electronic components contained in the wireline downhole tools, which can cause...... the intervention to fail. Active cooling systems represent a possible solution to the electronics overheating, as they could maintain the sensitive electronics at a tolerable temperature, while operating in hotter environments. This work presents the design, construction and testing of an actively cooled downhole......-width-modulation circuit was developed to adapt the downhole power source to a suitable voltage for the thermoelectric cooler. The implementation of the active cooling system was supported by the study of the thermal interaction between the downhole tool and the well environment, which was relevant to define the heat...

  12. Safety actuator of the Cabri reactor as a function of its power and cooling fluid flow rate

    International Nuclear Information System (INIS)

    Bertrand, Jean; Da Costa Vieira, David; Tattegrain, Alain

    1969-04-01

    This report present a device which is to provide a stop command to the Cabri reactor when the rate of its power to the cooling fluid rate reaches a value determined with respect to water temperature in the circuit. The stop command is delivered by an actuator which opens a relay contact when the power reaches a specific value. The authors present the device, its characteristics, and principle. They also present the different amplifier circuits, the input and output circuits (flow rate input, temperature input, and output circuit), the energy supply, and the various adjustments

  13. Serpentinization and alteration in an olivine cumulate from the Stillwater Complex, Southwestern Montana

    Science.gov (United States)

    Page, N.J.

    1976-01-01

    Some of the olivine cumulates of the Ultramafic zone of the Stillwater Complex, Montana, are progressively altered to serpentine minerals and thompsonite. Lizardite and chrysotile developed in the cumulus olivine and postcumulus pyroxenes; thompsonite developed in postcumulus plagioclase. The detailed mineralogy, petrology, and chemistry indicate that olivine and plagioclase react to form the alteration products, except for H2O, without changes in the bulk composition of the rocks. ?? 1976 Springer-Verlag.

  14. Modeling the cool down of the primary heat transport system using shut down cooling system in normal operation and after events such as LOCA

    International Nuclear Information System (INIS)

    Icleanu, D.L.; Prisecaru, I.

    2015-01-01

    This paper aims at modeling the cooling of the primary heat transport system using shutdown cooling system (SDCS), for a CANDU 6 NPP in all operating modes, normal and abnormal (particularly in case of LOCA accident), using the Flowmaster calculation code. The modelling of heavy water flow through the shutdown cooling system and primary heat transport system was performed to determine the distribution of flows, pressure in various areas of the hydraulic circuit and the pressure loss corresponding to the components but also for the heat calculation of the heat exchangers related to the system. The results of the thermo-hydraulic analysis show that in all cases analyzed, normal operation and for LOCA accident regime, the performance requirements are confirmed by analysis

  15. Experimental study of the application of two trickle media for inlet air pre-cooling of natural draft dry cooling towers

    International Nuclear Information System (INIS)

    He, Suoying; Guan, Zhiqiang; Gurgenci, Hal; Hooman, Kamel; Lu, Yuanshen; Alkhedhair, Abdullah M.

    2015-01-01

    Highlights: • Two trickle media were experimentally studied in a low-speed wind tunnel. • Correlations for cooling efficiency and pressure drop were developed. • Both trickle media were proven to have relatively low pressure drops. • Both trickle media had severe water entrainment at large air velocities. - Abstract: This paper is part two of a broader investigation into pre-cooling the air that enters natural draft dry cooling towers. Evaporative cooling of air is to some extent different from evaporative cooling of water. Two trickle media (Trickle125 and Trickle100) originally designed for evaporative cooling of water were studied in an open-circuit wind tunnel for evaporative cooling of air. Three medium thicknesses (200, 300 and 450 mm) and two water flow rates (10 and 5 l/min per m 2 horizontally exposed surface area) were used in the tests. The air velocities ranged from 0.5 to 3.0 m/s. The cooling efficiency and the pressure drop of the two media were curve fitted to yield a set of correlations. The pressure drop ranges for Trickle125 and Trickle100 were 0.7–50 Pa and 0.6–41.6 Pa, respectively. The cooling efficiencies of Trickle125 and Trickle100 fell within 15.7–55.1% and 11–44.4%, respectively. Generally, media with large effective surfaces provide high cooling efficiencies and high pressure drops; there is a trade-off between cooling efficiency and pressure drop when selecting a particular medium for a specific application. The water entrainment off the media was detected with water-sensitive papers, and both media had severe water entrainment at large air velocities

  16. Reduction of radiation fields in the cooling water circuits of PWRs: a one-step or a multistep process

    International Nuclear Information System (INIS)

    Lassau, R.T.; Cherepakhov, G.; Smee, J.L.; Berger, J.

    1988-01-01

    A basic problem for nuclear power plants is the formation or radioactive corrosion products in crud particles and oxide films found mainly in the primary side of the reactor cooling water circuits. The activated corrosion products produce radiation fields, which are the major source of exposure for personnel during maintenance and operation of the system. As a health safeguard for personnel, and for the considerable economic benefit to a plant that can be realized by the reduction of radiation fields, the nuclear industry implements physical and chemical decontamination methods to dissolve oxide films and to assist in the removal of crud during plant shutdowns. These procedures impact on the scheduling of activities that must be accomplished before the reactor can be returned to full operation and are therefore carefully planned to minimize the time for decontamination while maximizing the radioactive field reductions. Of considerable importance to the industry, therefore, are procedures that might be implemented during normal reactor operation and as a reactor approaches shutdown that would assist in the removal of radioactive material while controlling the recontamination during reactor operation. A study program was therefore undertaken to compare radioactive field reductions and corrosion rates obtained from a dilute multistep chemical decontamination with data obtained from a single-step parametric cycling experiment on PWR materials

  17. Structural assessment of intermediate printed circuit heat exchanger for sodium-cooled fast reactor with supercritical CO2 cycle

    International Nuclear Information System (INIS)

    Lee, Youho; Lee, Jeong Ik

    2014-01-01

    Highlights: • We numerically model PCHE stress arising from pressure, and thermal loadings. • Stress levels are the highest around S-CO 2 channels, due to high pressure of S-CO 2 . • The conventional analytic models for PCHE underestimate actual stress levels. • Plasticity sufficiently lowers stress levels at channel tips. • PCHE for SFR-SCO 2 is anticipated to assure compliance with ASME design standards. - Abstract: Structural integrity of intermediate Printed Circuit Heat Exchanger (PCHE) for Sodium-cooled Fast Reactor (SFR) attached to Supercritical CO 2 (S-CO 2 ) is investigated. ANSYS-Mechanical was used to simulate stress fields of representative PCHE channels, with temperature fields imported from FLUENT simulation. Mechanical stress induced by pressure loading is found to be the primary source of stress. As plasticity sufficiently lowers local stress concentration at PCHE channel tips, PCHE type intermediate heat exchangers made of SS316 are anticipated to reliably assure compliance with design standards prescribed in the ASME standards, thanks to the structure temperature that is below the effective creep inducing point. The actual life time of PCHE for SFR-SCO 2 is likely to be affected by mechanical behavior change of SS316 with reactions with S-CO 2 and fatigue

  18. Flow distribution analysis on the cooling tube network of ITER thermal shield

    International Nuclear Information System (INIS)

    Nam, Kwanwoo; Chung, Wooho; Noh, Chang Hyun; Kang, Dong Kwon; Kang, Kyoung-O; Ahn, Hee Jae; Lee, Hyeon Gon

    2014-01-01

    Thermal shield (TS) is to be installed between the vacuum vessel or the cryostat and the magnets in ITER tokamak to reduce the thermal radiation load to the magnets operating at 4.2K. The TS is cooled by pressurized helium gas at the inlet temperature of 80K. The cooling tube is welded on the TS panel surface and the composed flow network of the TS cooling tubes is complex. The flow rate in each panel should be matched to the thermal design value for effective radiation shielding. This paper presents one dimensional analysis on the flow distribution of cooling tube network for the ITER TS. The hydraulic cooling tube network is modeled by an electrical analogy. Only the cooling tube on the TS surface and its connecting pipe from the manifold are considered in the analysis model. Considering the frictional factor and the local loss in the cooling tube, the hydraulic resistance is expressed as a linear function with respect to mass flow rate. Sub-circuits in the TS are analyzed separately because each circuit is controlled by its own control valve independently. It is found that flow rates in some panels are insufficient compared with the design values. In order to improve the flow distribution, two kinds of design modifications are proposed. The first one is to connect the tubes of the adjacent panels. This will increase the resistance of the tube on the panel where the flow rate is excessive. The other design suggestion is that an orifice is installed at the exit of tube routing where the flow rate is to be reduced. The analysis for the design suggestions shows that the flow mal-distribution is improved significantly

  19. Air and water cooled modulator

    Science.gov (United States)

    Birx, Daniel L.; Arnold, Phillip A.; Ball, Don G.; Cook, Edward G.

    1995-01-01

    A compact high power magnetic compression apparatus and method for delivering high voltage pulses of short duration at a high repetition rate and high peak power output which does not require the use of environmentally unacceptable fluids such as chlorofluorocarbons either as a dielectric or as a coolant, and which discharges very little waste heat into the surrounding air. A first magnetic switch has cooling channels formed therethrough to facilitate the removal of excess heat. The first magnetic switch is mounted on a printed circuit board. A pulse transformer comprised of a plurality of discrete electrically insulated and magnetically coupled units is also mounted on said printed board and is electrically coupled to the first magnetic switch. The pulse transformer also has cooling means attached thereto for removing heat from the pulse transformer. A second magnetic switch also having cooling means for removing excess heat is electrically coupled to the pulse transformer. Thus, the present invention is able to provide high voltage pulses of short duration at a high repetition rate and high peak power output without the use of environmentally unacceptable fluids and without discharging significant waste heat into the surrounding air.

  20. Fastbus non-forced air-cooling tests

    International Nuclear Information System (INIS)

    Downing, R.W.

    1981-07-01

    Tests were conducted on a closed box with all walls at room temperature with heat test units positioned between the plates with small cardboard spacers. The rear of the test unit was taped closed, and no external air was allowed to flow through the box. Outside wall temperature was monitored for all tests. Tests were performed to test a possible method of conducting heat away from high powered I.C.'s in a closed chamber. The effect of a brass strip attached to the top of the I.C. and making mechanical contact with the wall of the box is tested. Tests show that some heatsinking technique is needed for I.C.'s of more than 3/4 watt dissipation. It is concluded that conventional air-cooled printed circuit boards can be effectively cooled by simply installing them in a cool-walled box. The chassis construction could also consist of card slots divided by water filled plates similar to refrigeration walls. Problems relating to wire-wrap modules are addressed

  1. Biofouling in the condenser cooling conduits of Madras Atomic Power Station

    International Nuclear Information System (INIS)

    Thiyagarajan, V.; Subramoniam, T.; Venugopalan, V.P.; Nair, K.V.K.

    1995-01-01

    The present paper deals with various aspects fouling organisms collected from the condenser cooling water circuit of Madras Atomic Power Station (MAPS II) their biomass, thickness, composition and length frequency distribution of one of the major species namely, B. reticulatus. (author). 8 refs., 1 tab., 2 figs

  2. Prospects for cooling nanomechanical motion by coupling to a superconducting microwave resonator

    International Nuclear Information System (INIS)

    Teufel, J D; Regal, C A; Lehnert, K W

    2008-01-01

    Recent theoretical work has shown that radiation pressure effects can in principle cool a mechanical degree of freedom to its ground state. In this paper, we apply this theory to our realization of an optomechanical system in which the motion of mechanical oscillator modulates the resonance frequency of a superconducting microwave circuit. We present experimental data demonstrating the large mechanical quality factors possible with metallic, nanomechanical beams at 20 mK. Further measurements also show damping and cooling effects on the mechanical oscillator due to the microwave radiation field. These data motivate the prospects for employing this dynamical backaction technique to cool a mechanical mode entirely to its quantum ground state.

  3. The quantity of algae colonizing the inside face of cooling towers and the consequences for wear of the shell

    International Nuclear Information System (INIS)

    Aprosi, G.; Chauvel, D.

    1990-01-01

    These studies are part of the interdirectorate working group's mandate relating to lifespan project on cooling towers. Involving the collaboration of several divisions of Electricity de France: the Construction Division (SEPTEN). The Generation and Transmission Division (SPT) and the Research and Development Division (EAA). Among the biological colonies which proliferate in the cooling circuits of power stations, algae are broadly represented in the form of wall coatings which cover the inside face of cooling towers: shell algae. They can also grow at other points in the cooling circuit; in the cold water basin, in the fill, and, in some cooling towers, in the hot water basin. These plant organisms hamper the operation of power stations by clogging the grids located in the pipe from the cold water basin to the condenser. In addition, when algae come free of the shell, they remove micro-fragments of the concrete, which could accelerate wear. This paper presents the findings of studies conducted by the Aquatic and Atmospheric Department on the infestation of cooling towers by algae. In particular, the results of studies to evaluate the quantity of algae on the inside face of the shell of cooling towers. Many scenarios will be proposed, linked to the operation of the plant and to the local meteorological conditions

  4. Chooz A: a model for the dismantling of water-cooled reactors

    International Nuclear Information System (INIS)

    Anon.

    2017-01-01

    The specificity of Chooz-A, the first French pressurized water reactor (PWR), is that the reactor and its major components (pumps, exchangers and cooling circuits) are installed in 2 caves dug out in a hill slope. Chooz-A was operating from 1967 to 1991, in 1993 the fuel was removed and in 2007 EDF received the authorization to dismantle the reactor. In 2012, EDF completed the dismantling of the cave containing the elements of the cooling circuit, a cornerstone was the removing of the four 14 m high steam generators. The dismantling of the pressure vessel began in march 2017, it is the same tools and the same processes that were used for the dismantling of the pressure vessel of the Zorita plant (Spain) in 2016. The end of the Chooz-A dismantling is expected in 2022. The feedback experience will help to standardize practices for the French fleet of PWRs. (A.C.)

  5. Analysis of the flow imbalance in the KSTAR PF cryo-circuit

    International Nuclear Information System (INIS)

    Lee, Hyun-Jung; Park, Dong-Seong; Kwag, Sang-Woo; Joo, Jae-Jun; Moon, Kyung-Mo; Kim, Nam-Won; Lee, Young-Joo; Park, Young-Min; Yang, Hyung-Lyeol

    2015-01-01

    Highlights: • Investigate of flow imbalance trend for the KSTAR PF superconducting magnet. • Flow imbalance is compared with individual magnet test and integration magnet test. • Intensifying of flow imbalance is proven from the flow monitoring in the KSTAR PF circuit. • Flow behavior is analyzed during magnet charging in the circulator circuit. • Variation of magnet outlet temperature is analyzed due to flow imbalance. - Abstract: The KSTAR PF cryo-circuit is a quasi-closed circulation system in which more than 370 g/s of supercritical helium (SHe) is circulated using a SHe circulator. The heated helium from superconducting magnet is cooled through sub cooler (4.3 K). The circulator is operated at 4.5 K and 6.5 bar, and the pressure drop of the circuit is kept at 2 bar in order to maintain the supercritical state and circulator stability. The circuit is connected with helium refrigerator system, distribution system, and supercritical magnet system. It has a hundred branches to supply supercritical helium to the poloidal field superconducting magnet. The branch was designed to optimize the operation conditions and they are grouped for one cryogenic valve has the same length within the cardinal principle of the optimization. Five cryogenic valves are installed to control the mass flow rate, and seven orifice mass flow meters, differential pressure gauges and temperature sensors were installed in front of the magnet in the distribution because upper magnet and lower magnet is symmetric theoretically. The cryogenic pipe line was manufactured with elevation about 10 m between upper magnet and lower magnet. The inlet and outlet helium feed-through were installed at the coil inside in case of KSTAR PF1–PF5 upper magnet and lower magnet. The flow imbalance is caused by void fraction and it could be changed due to manufacturing process even if it has the same length of cooling channel. This creates an imbalance among cooling channels and temperatures are

  6. Technological project of serpentine raw material milling from Dobšiná heaps

    Directory of Open Access Journals (Sweden)

    Alena Pietriková

    2005-11-01

    Full Text Available Serpentine heaps in the surrounding of Dobšiná are an old ecological problem of the city and at the same time a suitable material for the production of MgCl2 and SiO2. The technology of the production is based on the chemical processing of the raw material, which is preceded by the raw material preparation comprising of the mechanical and hydraulic sorting, milling and the magnetic separation operations.

  7. Arbuscular mycorrhizal symbiosis on serpentine soils: the effect of native fungal communities on different Knautia arvensis ecotypes

    Czech Academy of Sciences Publication Activity Database

    Doubková, Pavla; Suda, Jan; Sudová, Radka

    2011-01-01

    Roč. 345, 1-2 (2011), s. 325-338 ISSN 0032-079X R&D Projects: GA AV ČR KJB600050812 Institutional research plan: CEZ:AV0Z60050516 Keywords : arbuscular mycorrhiza * serpentine soils * edaphic stress Subject RIV: EF - Botanics Impact factor: 2.733, year: 2011

  8. Steam generators in indirect-cycle water-cooled reactors

    International Nuclear Information System (INIS)

    Fajeau, M.

    1976-01-01

    In the indirect cycle water-cooled nuclear reactors, the steam generators are placed between the primary circuit and the turbine. They act both as an energy transmitter and as a leaktigh barrier against fission or corrosion products. Their study is thus very important from a performance and reliability point of view. Two main types are presented here: the U-tube and the once-through steam generators [fr

  9. Effect of limb cooling on peripheral and global oxygen consumption in neonates.

    Science.gov (United States)

    Hassan, I A-A; Wickramasinghe, Y A; Spencer, S A

    2003-03-01

    To evaluate peripheral oxygen consumption (VO(2)) measurements using near infrared spectroscopy (NIRS) with arterial occlusion in healthy term neonates by studying the effect of limb cooling on peripheral and global VO(2). Twenty two healthy term neonates were studied. Peripheral VO(2) was measured by NIRS using arterial occlusion and measurement of the oxyhaemoglobin (HbO(2)) decrement slope. Global VO(2) was measured by open circuit calorimetry. Global and peripheral VO(2) was measured in each neonate before and after limb cooling. In 10 neonates, a fall in forearm temperature of 2.2 degrees C (mild cooling) decreased forearm VO(2) by 19.6% (p forearm temperature of 4 degrees C (moderate cooling) decreased forearm VO(2) by 34.7% (p cooling. The changes are more pronounced with moderate limb cooling when a concomitant rise in global VO(2) is observed. Change in peripheral temperature must be taken into consideration in the interpretation of peripheral VO(2) measurements in neonates.

  10. SIMULTANEOUS MECHANICAL AND HEAT ACTIVATION: A NEW ROUTE TO ENHANCE SERPENTINE CARBONATION REACTIVITY AND LOWER CO2 MINERAL SEQUESTRATION PROCESS COST

    Energy Technology Data Exchange (ETDEWEB)

    M.J. McKelvy; J. Diefenbacher; R. Nunez; R.W. Carpenter; A.V.G. Chizmeshya

    2005-01-01

    Coal can support a large fraction of global energy demands for centuries to come, if the environmental problems associated with CO{sub 2} emissions can be overcome. Unlike other candidate technologies, which propose long-term storage (e.g., ocean and geological sequestration), mineral sequestration permanently disposes of CO{sub 2} as geologically stable mineral carbonates. Only benign, naturally occurring materials are formed, eliminating long-term storage and liability issues. Serpentine carbonation is a leading mineral sequestration process candidate, which offers large scale, permanent sequestration. Deposits exceed those needed to carbonate all the CO{sub 2} that could be generated from global coal reserves, and mining and milling costs are reasonable ({approx}$4 to $5/ton). Carbonation is exothermic, providing exciting low-cost process potential. The remaining goal is to develop an economically viable process. An essential step in this development is increasing the carbonation reaction rate and degree of completion, without substantially impacting other process costs. Recently, the Albany Research Center (ARC) has accelerated serpentine carbonation, which occurs naturally over geological time, to near completion in less than an hour. While reaction rates for natural serpentine have been found to be too slow for practical application, both heat and mechanical (attrition grinding) pretreatment were found to substantially enhance carbonation reactivity. Unfortunately, these processes are too energy intensive to be cost-effective in their present form. In this project we explored the potential that utilizing power plant waste heat (e.g., available up to {approx}200-250 C) during mechanical activation (i.e., thermomechanical activation) offers to enhance serpentine mineral carbonation, while reducing pretreatment energy consumption and process cost. This project was carried out in collaboration with the Albany Research Center (ARC) to maximize the insight into the

  11. A voltage biased superconducting quantum interference device bootstrap circuit

    International Nuclear Information System (INIS)

    Xie Xiaoming; Wang Huiwu; Wang Yongliang; Dong Hui; Jiang Mianheng; Zhang Yi; Krause, Hans-Joachim; Braginski, Alex I; Offenhaeusser, Andreas; Mueck, Michael

    2010-01-01

    We present a dc superconducting quantum interference device (SQUID) readout circuit operating in the voltage bias mode and called a SQUID bootstrap circuit (SBC). The SBC is an alternative implementation of two existing methods for suppression of room-temperature amplifier noise: additional voltage feedback and current feedback. Two circuit branches are connected in parallel. In the dc SQUID branch, an inductively coupled coil connected in series provides the bias current feedback for enhancing the flux-to-current coefficient. The circuit branch parallel to the dc SQUID branch contains an inductively coupled voltage feedback coil with a shunt resistor in series for suppressing the preamplifier noise current by increasing the dynamic resistance. We show that the SBC effectively reduces the preamplifier noise to below the SQUID intrinsic noise. For a helium-cooled planar SQUID magnetometer with a SQUID inductance of 350 pH, a flux noise of about 3 μΦ 0 Hz -1/2 and a magnetic field resolution of less than 3 fT Hz -1/2 were obtained. The SBC leads to a convenient direct readout electronics for a dc SQUID with a wider adjustment tolerance than other feedback schemes.

  12. Multistage crack seal vein and hydrothermal Ni enrichment in serpentinized ultramafic rocks (Koniambo massif, New Caledonia)

    Science.gov (United States)

    Cathelineau, Michel; Myagkiy, Andrey; Quesnel, Benoit; Boiron, Marie-Christine; Gautier, Pierre; Boulvais, Philippe; Ulrich, Marc; Truche, Laurent; Golfier, Fabrice; Drouillet, Maxime

    2017-10-01

    Sets of fractures and breccia sealed by Ni-rich silicates and quartz occur within saprock of the New Caledonian regolith developed over ultramafic rocks. The crystallization sequence in fractures is as follows: (1) serpentine stage: lizardite > polygonal serpentine > white lizardite; (2) Ni stage: Ni-Mg kerolite followed by red-brown microcrystalline quartz; and (3) supergene stages. The red-brown microcrystalline quartz corresponds to the very last stage of the Ni sequence and is inferred to have precipitated within the 50-95 °C temperature range. It constitutes also the main cement of breccia that has all the typical features of hydraulic fracturing. The whole sequence is therefore interpreted as the result of hydrothermal fluid circulation under medium to low temperature and fluctuating fluid pressure. Although frequently described as the result of a single downward redistribution of Ni and Mg leached in the upper part of the regolith under ambient temperature, the Ni silicate veins thus appear as the result of recurrent crack and seal process, corresponding to upward medium temperature fluid convection, hydraulic fracturing and subsequent fluid mixing, and mineral deposition.

  13. Acoustical environment of gas-cooled nuclear reactors

    International Nuclear Information System (INIS)

    Blevins, R.D.

    1986-01-01

    Methods for acoustical analysis of gas-cooled nuclear reactors in terms of the sources of sound, the propagation of sound about the coolant circuit and the response of reactor structures to sound, are described. Sources of sound that are considered are circulators, jets, vortex shedding and separated flow. Circulators are generally the dominant source of sound. At low frequency the sound propagates one dimensionally through the ducts and cavities of the reactor. At high frequency the sound excites closely spaced two- and three-dimensional acoustic modes, and the resultant sound field can be described only statistically. The sound excites plate and shell structures within the coolant circuit. Secondary steam piping can also be excited by pumps and valves. Formulations are presented for the resultant vibration. Vibration-induced damage is also reviewed. (author)

  14. Heat management in integrated circuits on-chip and system-level monitoring and cooling

    CERN Document Server

    Ogrenci-Memik, Seda

    2016-01-01

    This essential overview covers the subject of thermal monitoring and management in integrated circuits. Specifically, it focuses on devices and materials that are intimately integrated on-chip (as opposed to in-package or on-board) for the purposes of thermal monitoring and thermal management.

  15. Integrated three-dimensional module heat exchanger for power electronics cooling

    Science.gov (United States)

    Bennion, Kevin; Lustbader, Jason

    2013-09-24

    Embodiments discussed herein are directed to a power semiconductor packaging that removes heat from a semiconductor package through one or more cooling zones that are located in a laterally oriented position with respect to the semiconductor package. Additional embodiments are directed to circuit elements that are constructed from one or more modular power semiconductor packages.

  16. Efficacy of woody biomass and biochar for alleviating heavy metal bioavailability in serpentine soil.

    Science.gov (United States)

    Bandara, Tharanga; Herath, Indika; Kumarathilaka, Prasanna; Hseu, Zeng-Yei; Ok, Yong Sik; Vithanage, Meththika

    2017-04-01

    Crops grown in metal-rich serpentine soils are vulnerable to phytotoxicity. In this study, Gliricidia sepium (Jacq.) biomass and woody biochar were examined as amendments on heavy metal immobilization in a serpentine soil. Woody biochar was produced by slow pyrolysis of Gliricidia sepium (Jacq.) biomass at 300 and 500 °C. A pot experiment was conducted for 6 weeks with tomato (Lycopersicon esculentum L.) at biochar application rates of 0, 22, 55 and 110 t ha -1 . The CaCl 2 and sequential extractions were adopted to assess metal bioavailability and fractionation. Six weeks after germination, plants cultivated on the control could not survive, while all the plants were grown normally on the soils amended with biochars. The most effective treatment for metal immobilization was BC500-110 as indicated by the immobilization efficiencies for Ni, Mn and Cr that were 68, 92 and 42 %, respectively, compared to the control. Biochar produced at 500 °C and at high application rates immobilized heavy metals significantly. Improvements in plant growth in biochar-amended soil were related to decreasing in metal toxicity as a consequence of metal immobilization through strong sorption due to high surface area and functional groups.

  17. Microbial Community Structure in a Serpentine-Hosted Abiotic Gas Seepage at the Chimaera Ophiolite, Turkey.

    Science.gov (United States)

    Neubeck, Anna; Sun, Li; Müller, Bettina; Ivarsson, Magnus; Hosgörmez, Hakan; Özcan, Dogacan; Broman, Curt; Schnürer, Anna

    2017-06-15

    The surface waters at the ultramafic ophiolitic outcrop in Chimaera, Turkey, are characterized by high pH values and high metal levels due to the percolation of fluids through areas of active serpentinization. We describe the influence of the liquid chemistry, mineralogy, and H 2 and CH 4 levels on the bacterial community structure in a semidry, exposed, ultramafic environment. The bacterial and archaeal community structures were monitored using Illumina sequencing targeting the 16S rRNA gene. At all sampling points, four phyla, Proteobacteria , Actinobacteria , Chloroflexi , and Acidobacteria , accounted for the majority of taxa. Members of the Chloroflexi phylum dominated low-diversity sites, whereas Proteobacteria dominated high-diversity sites. Methane, nitrogen, iron, and hydrogen oxidizers were detected as well as archaea and metal-resistant bacteria. IMPORTANCE Our study is a comprehensive microbial investigation of the Chimaera ophiolite. DNA has been extracted from 16 sites in the area and has been studied from microbial and geochemical points of view. We describe a microbial community structure that is dependent on terrestrial, serpentinization-driven abiotic H 2 , which is poorly studied due to the rarity of these environments on Earth. Copyright © 2017 Neubeck et al.

  18. Cooling tower make-up water processing for nuclear power plants: a comparison

    Energy Technology Data Exchange (ETDEWEB)

    Andres, O; Flunkert, F; Hampel, G; Schiffers, A [Rheinisch-Westfaelisches Elektrizitaetswerk A.G., Essen (Germany, F.R.)

    1977-01-01

    In water-cooled nuclear power plants, 1 to 2% of the total investment costs go to cooling tower make-up water processing. The crude water taken from rivers or stationary waters for cooling must be sufficiently purified regarding its content of solids, carbonate hardness and corrosive components so as to guarantee an operation free of disturbances. At the same time, the processing methods must be selected for operational-economic reasons in such a manner that waste water and waste problems are kept small regarding environmental protection. The various parameters described have a decisive influence on the processing methods of the crude water, individual processes (filtration, sedimentation, decarbonization) are described, circuit possibilities for cooling water systems are compared and the various processes are analyzed and compared with regard to profitableness and environmental compatability.

  19. Early Thermal History of Rhea: The Role of Serpentinization and Liquid State Convection

    OpenAIRE

    Czechowski Leszek; Łosiak Anna

    2016-01-01

    Early thermal history of Rhea is investigated. The role of the following parameters of the model is investigated: time of beginning of accretion, tini, duration of accretion, tac, viscosity of ice close to the melting point, η0, activation energy in the formula for viscosity, E, thermal conductivity of silicate component, ksil, ammonia content, XNH3, and energy of serpentinization, cserp. We found that tini and tac are crucial for evolution. All other parameters are also important, but no dra...

  20. Thermal simulation of a cooling system of hybrid commercial vehicles; Thermalsimulation eine Hybrid-LKW-Kuehlsystems

    Energy Technology Data Exchange (ETDEWEB)

    Stroh, Christoph; Schnoerch, Stefan; Rathberger, Christian [Magna Powertrain Engineering Center Steyr GmbH und Co. KG, St. Valentin (Austria)

    2012-11-01

    In the past few years hybrid vehicles have been in the center of automotive engineering efforts, in particular in the field of passenger cars. But hybrid powertrains will also be important for commercial trucks. This focus on hybrid vehicles leads to high demands on thermal management since the additional components in a hybrid vehicle need appropriate cooling or even heating. In the given paper the simulation of a complete cooling system of a hybrid commercial vehicle will be explained. For this virtual examination the commercial 1D thermal management software KULI will be used, a co-simulation with several programs will not be done deliberately. Yet all aspects which are relevant for a global assessment of the thermal management are considered. The main focus is put on the investigation of appropriate concepts for the fluid circuits, including low and high temperature circuits, electric water pumps, etc. Moreover, also a refrigerant circuit with a chiller for active battery cooling will be used, the appropriate control strategy is implemented as well. For simulating transient profiles a simple driving simulation model is included, using road profile, ambient conditions, and various vehicle parameters as input. In addition an engine model is included which enables the investigation of fuel consumption potentials. This simulation model shows how the thermal management of a hybrid vehicle can be investigated with a single program and with reasonable effort. (orig.)

  1. Characterization of Serpentine Samples from the Coast Range Ophiolite Microbial Observatory with μ-FTIR and XRD. ­­

    Science.gov (United States)

    Sousa, A.; Cardace, D.

    2017-12-01

    Serpentinizing systems hold much promise as potentially habitable environments in diverse planetary settings. They involve abundant and simple ingredients (i.e., the mineral olivine, liquid water), support subsurface microbial communities on Earth (Crespo-Medina et al. 2014; Suzuki et al. 2014; Kelley et al. 2005) and are thought to occur elsewhere in our solar system such as Mars (Schulte et al. 2006; Ehlmann et al. 2010)and possibly ocean worlds (Waite et al. 2017; Vance 2009). Although geochemical and microbial data collection continues in serpentinizing systems, the identification and resolution of potential biosignatures in serpentinites are not yet clear. Specifically, the micro-scale mineralogical contexts in which cell fragments or biofilm residues may be formed and preserved is lacking. Here we report preliminary transmission and reflection mode μ-FTIR spectral maps and XRD diffractograms, obtained with instruments relevant to robotic exploration missions (Blake et al. 2012; Igisu et al. 2009; Leroi et al. 2009). Samples analyzed include ultramafic rock and constituent mineral standards (e.g., olivine) and rocks collected from near surface sites associated with the NASA Astrobiology Institute-funded initiative, the Coast Range Ophiolite Microbial Observatory (CROMO), in Lower Lake, CA (Cardace et al. 2013). These new results provide co-registered, complementary data on astrobiologically important rock and mineral phases related to serpentinization (Crespo-Medina et al. 2014; Twing et al. 2017). Future work will leverage this data set in microbial colonization experiments aimed at parsing background organic loads in serpentinites from surficial/fracture-localized modern biofilm signatures.

  2. Schenkel circuit and its characteristics. DC power source for NHV ion accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Toshio; Yamada, Masahiro; Nakazawa, Makoto; Iwamoto, Eiji [Nissin - High Voltage Co. Ltd., Kyoto (Japan)

    1996-12-01

    For DC high voltage source, it is necessary to have sufficient power capacity to suit for electric current capacity required for operational load and further sufficient power stability when adapting it to an ion accelerator. In this paper, outlines of various DC high voltage forming circuits using generally and characteristics of Schenkel type DC source adapted to ion accelerator were described. Characteristics of the NHV Schenkel type DC electric source on actual circuit construction is shown as follows; (1) Whole circuit construction is intended to improve its discharge resistance by assembly with gaps and resistors. (2) Stability caused by geometric shape specific to the Schenkel circuit is improved by adopting integral moldings of aluminum for its structural material. And, (3) Upgrading of cooling effect, and miniaturization and forming heat loss reduction of system are intended by adopting all aluminum to increasing pressure transformer storing tank for countermeasure of vortex current. (G.K.)

  3. Schenkel circuit and its characteristics. DC power source for NHV ion accelerator

    International Nuclear Information System (INIS)

    Kimura, Toshio; Yamada, Masahiro; Nakazawa, Makoto; Iwamoto, Eiji

    1996-01-01

    For DC high voltage source, it is necessary to have sufficient power capacity to suit for electric current capacity required for operational load and further sufficient power stability when adapting it to an ion accelerator. In this paper, outlines of various DC high voltage forming circuits using generally and characteristics of Schenkel type DC source adapted to ion accelerator were described. Characteristics of the NHV Schenkel type DC electric source on actual circuit construction is shown as follows; 1) Whole circuit construction is intended to improve its discharge resistance by assembly with gaps and resistors. 2) Stability caused by geometric shape specific to the Schenkel circuit is improved by adopting integral moldings of aluminum for its structural material. And, 3) Upgrading of cooling effect, and miniaturization and forming heat loss reduction of system are intended by adopting all aluminum to increasing pressure transformer storing tank for countermeasure of vortex current. (G.K.)

  4. 77 FR 47089 - Public Land Order No. 7795; Withdrawal of Public Lands, Clear Creek Serpentine Area of Critical...

    Science.gov (United States)

    2012-08-07

    ... DEPARTMENT OF THE INTERIOR Bureau of Land Management [LLCAC09000, 16100000.DQ; CACA 051408] Public Land Order No. 7795; Withdrawal of Public Lands, Clear Creek Serpentine Area of Critical Environmental Concern; California AGENCY: Bureau of Land Management, Interior. ACTION: Public Land Order. SUMMARY: This...

  5. Choice of cooling regime of the superconducting magnetic system of the ''Crystal-2'' torsatron

    International Nuclear Information System (INIS)

    Glasov, B.V.; Druj, O.S.; Kurnosov, V.I.; Skibenko, E.I.; Yuferov, V.B.

    1981-01-01

    General requirements to a system of cryogenic cooling of superconducting magnetic systems (SMS) are formulated. Distributions of the value of thermal stresses about the temperature range are obtained for basic construction materials of SMS ''Crystal-2'' torsatron. Concrete circuits of SMS cryoprovision are considered. Values of specific and total heat capacity of the system, specific consumption of liquid are determined taking into consideration constructional peculiarities of SMS of''Crystal-2'' plant. Efficiency of different ways of SMS cooling are estimated, dynamical dependences of cooling and heating of SMS of the ''Crystal-2'' plant are obtained taking this into consideration [ru

  6. Mineralizing Filamentous Bacteria from the Prony Bay Hydrothermal Field Give New Insights into the Functioning of Serpentinization-Based Subseafloor Ecosystems.

    Science.gov (United States)

    Pisapia, Céline; Gérard, Emmanuelle; Gérard, Martine; Lecourt, Léna; Lang, Susan Q; Pelletier, Bernard; Payri, Claude E; Monnin, Christophe; Guentas, Linda; Postec, Anne; Quéméneur, Marianne; Erauso, Gaël; Ménez, Bénédicte

    2017-01-01

    Despite their potential importance as analogs of primitive microbial metabolisms, the knowledge of the structure and functioning of the deep ecosystems associated with serpentinizing environments is hampered by the lack of accessibility to relevant systems. These hyperalkaline environments are depleted in dissolved inorganic carbon (DIC), making the carbon sources and assimilation pathways in the associated ecosystems highly enigmatic. The Prony Bay Hydrothermal Field (PHF) is an active serpentinization site where, similar to Lost City (Mid-Atlantic Ridge), high-pH fluids rich in H 2 and CH 4 are discharged from carbonate chimneys at the seafloor, but in a shallower lagoonal environment. This study aimed to characterize the subsurface microbial ecology of this environment by focusing on the earliest stages of chimney construction, dominated by the discharge of hydrothermal fluids of subseafloor origin. By jointly examining the mineralogy and the microbial diversity of the conduits of juvenile edifices at the micrometric scale, we find a central role of uncultivated bacteria belonging to the Firmicutes in the ecology of the PHF. These bacteria, along with members of the phyla Acetothermia and Omnitrophica , are identified as the first chimneys inhabitants before archaeal Methanosarcinales . They are involved in the construction and early consolidation of the carbonate structures via organomineralization processes. Their predominance in the most juvenile and nascent hydrothermal chimneys, and their affiliation with environmental subsurface microorganisms, indicate that they are likely discharged with hydrothermal fluids from the subseafloor. They may thus be representative of endolithic serpentinization-based ecosystems, in an environment where DIC is limited. In contrast, heterotrophic and fermentative microorganisms may consume organic compounds from the abiotic by-products of serpentinization processes and/or from life in the deeper subsurface. We thus propose

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

    International Nuclear Information System (INIS)

    Sakai, Massao

    1978-01-01

    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)

  8. Free cooling potential of a PCM-based heat exchanger coupled with a novel HVAC system for simultaneous heating and cooling of buildings

    DEFF Research Database (Denmark)

    Maccarini, Alessandro; Hultmark, Göran; Bergsøe, Niels Christian

    2018-01-01

    . In particular, a model of a PCM-based heat exchanger was developed in this work by using the programming language Modelica. This device was designed to store cold energy during night-time and release it during daytime through the water circuit. Results for a typical office building model showed...... that the integration of free cooling devices can significantly reduce the primary energy use of the novel HVAC system. In particular, the thermal plant configuration including the PCM-based heat exchanger made it possible to almost completely avoid the use of mechanical cooling, leading to annual primary energy......This article presents a simulation-based study that estimates the primary energy use of a novel HVAC system for different configurations of a thermal plant. The main characteristic of the system is its ability to provide simultaneous heating and cooling to buildings by using a single hydronic...

  9. Model-based control of a fuel cell cooling circuit with automatic software testing; Modellbasierte Steuerung des Kuehlkreislaufes einer Brennstoffzelle mit automatisiertem Test der Software

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Sascha

    2012-07-01

    For reconstruction and control of the volume flow in a cooling circuit a fuel cell system is analyzed, and physical models of the fluid temperature and pump volume flow are derived. On this basis, functional models for derivation of software algorithms are presented which enable model-based calculation of the volume flow in a fluid circuit and coolant pump control on the basis of detailed system modelling. The available functions enable complete control and diagnosis of the volume flow. The functional models in Matlab/Simulink will be implemented in a control unit; they are discussed in the context of a software development process. It is stressed that correctness of the functions must be assured, and a trial automation system for functional models of this type is presented. (orig./AKB) [German] Zur Rekonstruktion und Steuerung des Volumenstroms in einem Kuehlkreislauf, wird ein Brennstoffzellensystem analysiert und physikalische Modelle fuer die Fluidtemperatur und den Pumpenvolumenstrom werden hergeleitet. Basierend auf diesen Zusammenhaengen werden Funktionsmodelle zur Ableitung von Softwarealgorithmen vorgestellt. Diese ermoeglichen es den Volumenstrom in einem Fluidkreislauf modellbasiert zu bestimmen bzw. die Kuehlmittelpumpe basierend auf einer detaillierten Systemmodellierung zu steuern. Die zur Verfuegung stehenden Funktionen erlauben eine komplette Regelung, Steuerung und Diagnose des Volumenstroms. Die Funktionsmodelle, in Matlab/Simulink realisiert und zur Ausfuehrung auf einem Steuergeraet vorgesehen, werden im Kontext eines Softwareentwicklungsprozesses diskutiert. Es wird die Notwendigkeit der Sicherstellung der Korrektheit der Funktionen herausgearbeitet und ein Testautomatisierungssystem fuer solche Funktionsmodelle vorgestellt.

  10. Improvements to secondary coolant circuits of a liquid metal cooled nuclear reactor

    International Nuclear Information System (INIS)

    Brachet, Alain.

    1981-01-01

    This invention concerns improvements to secondary coolant-systems for sodium cooled nuclear reactors. It further concerns a protective device for a free level mechanical pump which prevents any gas bubbles due to leaks of the working gas of the pump from entering the secondary system of the nuclear reactor [fr

  11. A small scale remote cooling system for a superconducting cyclotron magnet

    Science.gov (United States)

    Haug, F.; Berkowitz Zamorra, D.; Michels, M.; Gomez Bosch, R.; Schmid, J.; Striebel, A.; Krueger, A.; Diez, M.; Jakob, M.; Keh, M.; Herberger, W.; Oesterle, D.

    2017-02-01

    Through a technology transfer program CERN is involved in the R&D of a compact superconducting cyclotron for future clinical radioisotope production, a project led by the Spanish research institute CIEMAT. For the remote cooling of the LTc superconducting magnet operating at 4.5 K, CERN has designed a small scale refrigeration system, the Cryogenic Supply System (CSS). This refrigeration system consists of a commercial two-stage 1.5 W @ 4.2 K GM cryocooler and a separate forced flow circuit. The forced flow circuit extracts the cooling power of the first and the second stage cold tips, respectively. Both units are installed in a common vacuum vessel and, at the final configuration, a low loss transfer line will provide the link to the magnet cryostat for the cooling of the thermal shield with helium at 40 K and the two superconducting coils with two-phase helium at 4.5 K. Currently the CSS is in the testing phase at CERN in stand-alone mode without the magnet and the transfer line. We have added a “validation unit” housed in the vacuum vessel of the CSS representing the thermo-hydraulic part of the cyclotron magnet. It is equipped with electrical heaters which allow the simulation of the thermal loads of the magnet cryostat. A cooling power of 1.4 W at 4.5 K and 25 W at the thermal shield temperature level has been measured. The data produced confirm the design principle of the CSS which could be validated.

  12. Evolution of spreading rate and H2 production by serpentinization at mid-ocean ridges from 200 Ma to Present

    Science.gov (United States)

    Andreani, M.; García del Real, P.; Daniel, I.; Wright, N.; Coltice, N.

    2017-12-01

    Mid-oceanic ridge (MOR) spreading rate spatially varies today from 20 to 200 mm/yr and geological records attest of important temporal variations, at least during the past 200 My. The spreading rate has a direct impact on the mechanisms accomodating extension (magmatic vs tectonic), hence on the nature of the rocks forming the oceanic lithosphere. The latter is composed of variable amount of magmatic and mantle rocks, that dominate at fast and (ultra-) slow spreading ridges, respectively. Serpentinization of mantle rocks contributes to global fluxes and notably to those of hydrogen and carbon by providing a pathways for dihydrogen (H2) production, carbone storage by mineralization, and carbon reduction to CH4 and possibly complex organic compounds. Quantification of the global chemical impact of serpentinization through geological time requires a coupling of geochemical parameters with plate-tectonic reconstructions. Here we quantify serpentinization extent and concurrent H2 production at MOR from the Jurassic (200 Ma) to present day (0 Ma). We coupled mean values of relevant petro-chemical parameters such as the proportion of mantle rocks, initial iron in olivine, iron redox state in serpentinites, % of serpentinization to high-resolution models of plate motion within the GPlates infrastructure to estimate the lengths in 1 Myr intervals for the global MOR plate boundary (spreading and transform components), and spreading ridges as a function of their rate. The model sensitivity to selected parameters has been tested. The results show that fragmentation of Pangea resulted in elevated H2 rates (>1012 to 1013 mol/yr) starting at 160 Ma compared to Late Mesozoic (<160 Ma) rates (<1011-1012 mol/yr). From 160 Ma to present, the coupled opening of the Atlantic and Indian oceans as well as the variation in spreading rates maintained H2 generation in the 1012 mol/yr level, but with significant excursions mainly related to the length of ultra-slow spreading segments. For

  13. Short- circuit tests of circuit breakers

    OpenAIRE

    Chorovský, P.

    2015-01-01

    This paper deals with short-circuit tests of low voltage electrical devices. In the first part of this paper, there are described basic types of short- circuit tests and their principles. Direct and indirect (synthetic) tests with more details are described in the second part. Each test and principles are explained separately. Oscilogram is obtained from short-circuit tests of circuit breakers at laboratory. The aim of this research work is to propose a test circuit for performing indirect test.

  14. Experimental investigation of single-phase microjet cooling of microelectronics

    Directory of Open Access Journals (Sweden)

    Rusowicz Artur

    2015-09-01

    Full Text Available Development of electronics, which aims to improve the functionality of electronic devices, aims at increasing the packing of transistors in a chip and boosting clock speed (the number of elementary operations per second. While pursuing this objective, one encounters the growing problem of thermal nature. Each switching of the logic state at the elementary level of an integrated circuit is associated with the generation of heat. Due to a large number of transistors and high clock speeds, higher heat flux is emitted by the microprocessor to a level where the component needs to be intensively cooled, or otherwise it will become overheated. This paper presents the cooling of microelectronic components using microjets.

  15. Experimental investigation of single-phase microjet cooling of microelectronics

    Science.gov (United States)

    Rusowicz, Artur; Leszczyński, Maciej; Grzebielec, Andrzej; Laskowski, Rafał

    2015-09-01

    Development of electronics, which aims to improve the functionality of electronic devices, aims at increasing the packing of transistors in a chip and boosting clock speed (the number of elementary operations per second). While pursuing this objective, one encounters the growing problem of thermal nature. Each switching of the logic state at the elementary level of an integrated circuit is associated with the generation of heat. Due to a large number of transistors and high clock speeds, higher heat flux is emitted by the microprocessor to a level where the component needs to be intensively cooled, or otherwise it will become overheated. This paper presents the cooling of microelectronic components using microjets.

  16. Modelling of Transport of Radioactive Substances in the Primary Circuit of Water Cooled Reactors

    International Nuclear Information System (INIS)

    2012-03-01

    coordinated research project (CRP) was proposed to determine the accuracy of existing computer codes and to identify how they could be improved through application of this body of work. Specifically, the CRP was expected to: - Build a database for selected pressurized water reactor (PWR) plants that would contain the design information suitable for their description within a computer code, as well as give the operating history of the plant, which would include the water chemistry data over several refuelling cycles; - Show the contamination of selected out-of-core surfaces such as circulating loops and steam generator channel heads versus operating history and compare the prediction of surface contamination versus time from modern radioactivity transport codes with actual plant data in a blind benchmarking exercise; - Determine how current codes, as well as new ones, could be improved and encourage the development of accurate new codes in Member States using the recommendations from the present work. This report uses as its basis the results of this CRP on 'Modelling of Transport of Radioactive Substances in the Primary Circuit of Water Cooled Reactors', which was conducted over the period 1996-2001 for PWR type reactors. The report also describes the significant progress demonstrated in this field in the period that followed.

  17. Apparent Disequilibrium of Inorganic and Organic Carbon Compounds in Serpentinizing Fluids

    Science.gov (United States)

    Robinson, K.; Shock, E.

    2014-12-01

    During serpentinization of ultramafic rocks, ferrous iron in silicates is oxidized to ferric minerals and H2O is reduced to H2. This process is accompanied by the reduction of inorganic carbon, as observed in experiments and natural systems. To test the extent to which stable and metastable equilibria are reached among aqueous organic compounds during serpentinization, we sampled water and dissolved gases from circumneutral surface pools and hyperalkaline seeps in the Samail ophiolite in the Sultanate of Oman and analyzed for various carbon constituents, including dissolved inorganic carbon, dissolved organic carbon, methane, carbon monoxide, formate, acetate, and other small organic acid anions. Measurements of temperature, pH, dissolved H2, O2, major cations, major anions, and major and trace elements were also made. The aqueous composition of the analyzed samples was speciated based on ionic equilibrium interactions in order to obtain activities for inorganic carbon species, reduced carbon species, H2, and O2. The redox disequilibria among carbon species was then assessed using data and parameters for the revised HKF equations of state. This analysis demonstrates that the carbon species in this system are out of equilibrium with respect to one another in ways that cannot be compensated by altering the abundance of the other constituents within analytical uncertainties. Specifically, there is too much formate and too little methane relative to stable and metastable equilibria. This result implies the following: 1) Methane and formate equilibrated in separate parts of the system, given that no reasonable temperature, pressure, or composition changes satisfy equilibrium with their measured abundances. 2) Methane production is kinetically inhibited, as seen in experiments. 3) Microbial methane oxidation altered the abundance of methane and formate; methane oxidation to formate or carbonate is calculated to be extremely thermodynamically favorable in these fluids.

  18. Finite impulse testing (FIT) system for Emergency Cooling System (ECS) in Dhruva

    International Nuclear Information System (INIS)

    Punekar, Parag; Ramkumar, N.; Kulkarni, U.S.; Darbhea, M.D.; Bharadhwaj, G; Jangra, L.R.; Geetha, Patil; Das, Shantanu; Sonnis, S.T.; Trevedi, P.; Patil, M.B.; Biswas, B.B.

    2006-01-01

    Finite Impulse Testing (FIT) system for Emergency Cooling System (ECS) is used to check healthiness of ECS logic circuits in an online mode. The ECS is an important safety system that ensures the cooling of reactor core during shutdown state of Main Coolant Pumps (MCPs), and hence FIT-ECS that monitors the health of ECS logic circuits in an online (real time) mode is an important part of it. Based on a Safety Related Unusual Occurrence in ECS system due to the malfunction of its earlier single channel FIT system, the new FIT-ECS system has been designed with new features and is commissioned. The FIT-ECS system feeds the simulated input signals (fine impulses of nominal width 575 μS) to the ECS logic circuits and read the outputs. These output (predicted) signals from ECS logic circuit are processed in the FIT-ECS system and in event of any discrepancy, the FIT-ECS system displays fault signature on local panel, detailed information of the fault on Operator Console (OC), and generates an alarm 'ECS logic Fail' in the control room. FIT-ECS also monitors the inputs and outputs of ECS logic circuit. All the information required is stored as a database that can be subsequently displayed in various formats. ECS system is designated as Category I-A system and is a hardwired system and FIT-ECS monitors the healthiness of the logics of the ECS System is a computerized system. As per IEC 1226, FIT-ECS is categorized as Category I-B system. This paper provides technical information on FIT-ECS system design, its important features, the testing carried on the FIT-ECS system, interconnections of FIT-ECS and ECS and the commissioning experience of FIT-ECS system. (author)

  19. Study of temperature effect on the physical properties of ilmenite-serpentine heat resistant concrete radiation shields

    International Nuclear Information System (INIS)

    Kany, A.M.I.; EL-Fouly, M.M.; EL-Gohary, M.I.; Makatious, A.S.; Kamal, S.M.

    1990-01-01

    A series of experimental studies have been carried out to determine the change in unit weigh, compressive strength, water content and neutron macroscopic cross section of a new type of concrete shields made from egyptian ilmenite and serpentine ores when heated for long period at temperatures up to 600 degree C. Results show that the unit weight of the cure concrete has a value of 2.98 Ton/M 3 and decreases with increasing temperature, while the compressive strength reaches a maximum value of 19 Ton/M 2 at 100 degree C. The differential thermal analysis (D.T.A.) of this concrete shows three endothermic peaks at 100 degree C, 48 degree C and 740 degree C. Also, the thermogravimetry analysis (T.G.A.) shows that the cure concrete retains about 11% water content of the total sample weigh and still retains 4.5% of its initial value when heated for long period at 600 degree C. Results also show that the neutron macroscopic cross section (for neutrons of energies < 1 MeV) of the ilmenite-serpentine heat resistant concrete decreases to 18.6% of its initial value after heating to 600 degree C

  20. Serpentinization and carbonation of pristine continental ultramafic rocks and applications to the oceanic crust; H2O-CO2 alteration of dunites and re-distribution of Ni-Cu-PGE in sulphide deposits

    Science.gov (United States)

    Grant, Thomas; McEnroe, Suzanne; Eske Sørensen, Bjørn; Larsen, Rune; Pastore, Zeudia; Rune Grannes, Kim; Nikolaisen, Even

    2017-04-01

    Here, we document carbonation and serpentinization within a suite of ultramafic rocks from a continental setting. These ultramafic rocks vary from pristine dunites to varying degrees of serpentinization which locally penetrates the ultramafic complex. Hence, it allows us to observe a number of delicate serpentinization and carbonation reactions, otherwise lost during more extensive alteration or tectonic events. We use a multi-disciplinary approach using petrographic, EPMA, thermodynamic modelling and geophysical data to reveal how the initial stages of serpentization and carbonation in dunites affects the distribution of economic to sub-economic deposits of Ni-Cu and PGE. The data can then be applied to oceanic crust. The samples are dunites and poikilitic wehrlites from the Reinfjord Ultramafic complex, Seiland Igneous Province Northern Norway. The complex formed through crystallization of picritic melts in the lower continental crust. The dunites contain small amounts of interstitial clinopyroxene, sulphides and spinel, with local enrichments in Ni, Cu and PGE. Late magmatic CO2-H2O-S fluids reacted with the dunite forming clots of amphibole + dolomite + sulphides + enstatite, reaction rims of enstatite + dolomite, and inclusions trails of dolomite + enstatite + magnetite + CO2 fluid. Thermodynamic modelling reveals that these textures formed at pressures of >12 kbar and temperatures 850-950 °C, which would be consistent with the late magmatic history of the Reinfjord complex. The clots and reactions have local association with enrichments in gold-rich PGMs. A second stage of alteration involved H2O-dominated fluids. These formed predominantly lizardite serpentinization, as is often concentrated within highly localized fracture zones. Thermodynamic modelling shows that these formed serpentinization interacted with the earlier formed carbonate bearing assemblages leading to the formation of serpentinite, native copper and symplectites of brucite + calcite. The

  1. Boron, lithium and methane isotope composition of hyperalkaline waters (Northern Apennines, Italy): Terrestrial serpentinization or mixing with brine?

    International Nuclear Information System (INIS)

    Boschetti, Tiziano; Etiope, Giuseppe; Pennisi, Maddalena; Romain, Millot; Toscani, Lorenzo

    2013-01-01

    Highlights: ► First data on boron and lithium isotope on waters from ophiolites are described. ► High boron and lithium isotope composition may be related to terrestrial serpentinization. ► Methane isotope data show unusual biotic signature. - Abstract: Spring waters issuing from serpentinized ultramafic rocks of the Taro-Ceno Valleys (Northern Apennine, Emilia-Romagna region, Italy) were analyzed for major element, trace element and dissolved gas concentrations and δ 11 B, δ 7 Li, δ 18 O(H 2 O), δ 2 H(H 2 O), δ 13 C(CH 4 ) and δ 2 H(CH 4 ) isotope compositions. Similar to other springs worldwide that issue from serpentinites, the chemical composition of the waters evolves with water–rock interaction from Ca-HCO 3 , through Mg-HCO 3 and ultimately to a hyperalkaline Na-(Ca)-OH composition. Most of the Ca- and Mg-HCO 3 springs have δ 11 B ranging between +16.3‰ and +23.7‰, consistent with the range of low P–T serpentinites. Very high δ 11 B in two springs from Mt. Prinzera (PR10: +39‰; PR01: +43‰) can be related to isotopic fractionation during secondary phase precipitation, as also inferred from δ 7 Li values. In contrast to typical abiogenic isotope signatures of CH 4 from serpentinized rocks, dissolved CH 4 from the Taro-Ceno hyperalkaline springs has an apparent biotic (thermogenic and/or mixed thermogenic-microbial) signature with δ 13 C(CH 4 ) ranging from −57.5‰ to −40.8‰, which is similar to that of hydrocarbons from production wells and natural seeps in adjacent hydrocarbon systems. The data suggest that CH 4 in the hyperalkaline springs investigated in this study may derive from organic matter of the sedimentary (flysch and arenaceous) formations underlying the ophiolite unit. However, small amounts of H 2 were detected in one hyperalkaline spring (PR10), but for two springs with very low CH 4 concentrations (PR01 and UM15) the δ 2 H value could not be measured, so the occurrence of some abiotic CH 4 cannot be excluded

  2. Combined cooling and purification system for nuclear reactor spent fuel pit, refueling cavity, and refueling water storage tank

    Science.gov (United States)

    Corletti, Michael M.; Lau, Louis K.; Schulz, Terry L.

    1993-01-01

    The spent fuel pit of a pressured water reactor (PWR) nuclear power plant has sufficient coolant capacity that a safety rated cooling system is not required. A non-safety rated combined cooling and purification system with redundant branches selectively provides simultaneously cooling and purification for the spent fuel pit, the refueling cavity, and the refueling water storage tank, and transfers coolant from the refueling water storage tank to the refueling cavity without it passing through the reactor core. Skimmers on the suction piping of the combined cooling and purification system eliminate the need for separate skimmer circuits with dedicated pumps.

  3. Performance analysis of a ground-assisted direct evaporative cooling air conditioner

    Energy Technology Data Exchange (ETDEWEB)

    Heidarinejad, Ghassem; Khalajzadeh, Vahid [Department of Mechanical Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran); Delfani, Shahram [Building and Housing Research Center (BHRC), P O Box 13145-1696, Tehran (Iran)

    2010-11-15

    In this paper, the results of performance analysis of a ground-assisted hybrid evaporative cooling system in Tehran have been discussed. A Ground Coupled Circuit (GCC) provides the necessary pre-cooling effects, enabling a Direct Evaporative Cooler (DEC) that cools the air even below its wet-bulb temperature. The GCC includes four vertical ground heat exchangers (GHE) which were arrayed in series configuration. In order to have an accurate prediction of the optimum performance of a GCC, a computational fluid dynamic simulation was performed. Simulation results revealed that the combination of GCC and DEC system could provide comfort condition whereas DEC alone did not. Based on the simulation results the cooling effectiveness of a hybrid system is more than 100%. Thus, this novel hybrid system could decrease the air temperature below the ambient wet-bulb temperature. This environmentally clean and energy efficient system can be considered as an alternative to the mechanical vapor compression systems. (author)

  4. Passive cooling of condensate chambers as retrofitting measure in boiling water reactors; Passive Kuehlung der Kondensationskammern in Siedewasserreaktoren als Nachruestmassnahme

    Energy Technology Data Exchange (ETDEWEB)

    Freis, Daniel; Nachtrodt, Frederik; Sporn, Michael; Tietsch, Wolfgang; Sassen, Felix [Westinghouse Electric Germany GmbH, Mannheim (Germany)

    2012-11-01

    Westinghouse Electric Germany GmbH has developed a concept for passive cooling of condensate chambers of BWR-type reactors. Due to its compactness the system is feasible as retrofitting measure. The passive condensate chamber cooling system is based on a cooling module with ascending and down pipe that are connected with the evaporation condenser to form a cooling circuit. Based on the consequent use of high-effective heat transport mechanisms, as boiling, condensation without non-condensable gases and mass transport a high cooling performance and compact construction is possible. The system is completely passive and completely diverse to existing active cooling systems. In the frame of a true-scale experiment the significant cooling performance was demonstrated. RELAP5 calculations confirmed the functionality of the cooling module.

  5. The performance of a mobile air conditioning system with a water cooled condenser

    International Nuclear Information System (INIS)

    Di Battista, Davide; Cipollone, Roberto

    2015-01-01

    Vehicle technological evolution lived, in recent years, a strong acceleration due to the increased awareness of environmental issues related to pollutants and climate altering emissions. This resulted in a series of international regulations on automotive sector which put technical challenges that must consider the engine and the vehicle as a global system, in order to improve the overall efficiency of the system. The air conditioning system of the cabin, for instance, is the one of the most important auxiliaries in a vehicle and requires significant powers. Its performances can be significantly improved if it is integrated within the engine cooling circuit, eventually modified with more temperature levels.In this paper, the Authors present a mathematical model of the A/C system, starting from its single components: compressors, condenser, flush valve and evaporator and a comparison between different refrigerant fluid. In particular, it is introduced the opportunity to have an A/C condenser cooled by a water circuit instead of the external air linked to the vehicle speed, as in the actual traditional configuration. The A/C condenser, in fact, could be housed on a low temperature water circuit, reducing the condensing temperature of the refrigeration cycle with a considerable efficiency increase. (paper)

  6. The performance of a mobile air conditioning system with a water cooled condenser

    Science.gov (United States)

    Di Battista, Davide; Cipollone, Roberto

    2015-11-01

    Vehicle technological evolution lived, in recent years, a strong acceleration due to the increased awareness of environmental issues related to pollutants and climate altering emissions. This resulted in a series of international regulations on automotive sector which put technical challenges that must consider the engine and the vehicle as a global system, in order to improve the overall efficiency of the system. The air conditioning system of the cabin, for instance, is the one of the most important auxiliaries in a vehicle and requires significant powers. Its performances can be significantly improved if it is integrated within the engine cooling circuit, eventually modified with more temperature levels. In this paper, the Authors present a mathematical model of the A/C system, starting from its single components: compressors, condenser, flush valve and evaporator and a comparison between different refrigerant fluid. In particular, it is introduced the opportunity to have an A/C condenser cooled by a water circuit instead of the external air linked to the vehicle speed, as in the actual traditional configuration. The A/C condenser, in fact, could be housed on a low temperature water circuit, reducing the condensing temperature of the refrigeration cycle with a considerable efficiency increase.

  7. Improvement of coal focus and cooling towers of COFRENTES NPP

    International Nuclear Information System (INIS)

    Martinez, I.; Bogh, P.

    1998-01-01

    Cofrentes Nuclear Power Plant is performing a improving program of its cooling towers based on the filling revamping and cooling water circuit improvement. Furthermore, and as consequence of the acquired experience on cooling towers due to the mentioned program, Cofrentes NPP has decided to follow up with this project from a different point of view based on the thermal-hydraulic optimization of the cooling process inside the towers. This program, which is going to be carried out by Cofrentes NPP, Iberinco and Energy Planning and Power Generation (EPPG) provides an improvement on the thermal profile and of the draught inside the cooling towers by improving the water distribution in the towers active area. In order to perform such a program is needed to fulfill a test program to assure a guaranteed performance gain. In this way, Iberinco is developing a test procedure which improves the results which are obtained with the present standards used commonly by the industry. As a consequence of this program, Cofrentes is expecting to obtain a gain of 5 to 8 MWe with a revenue period of 4 to 5 months, results validated in another foreigner Plant which have developed a similar program. (Author)

  8. Commutation circuit for an HVDC circuit breaker

    Science.gov (United States)

    Premerlani, William J.

    1981-01-01

    A commutation circuit for a high voltage DC circuit breaker incorporates a resistor capacitor combination and a charging circuit connected to the main breaker, such that a commutating capacitor is discharged in opposition to the load current to force the current in an arc after breaker opening to zero to facilitate arc interruption. In a particular embodiment, a normally open commutating circuit is connected across the contacts of a main DC circuit breaker to absorb the inductive system energy trapped by breaker opening and to limit recovery voltages to a level tolerable by the commutating circuit components.

  9. Some problems raised by the operation of large nuclear turbo-generator sets. Cooling of shielded conductors. Precautionary steps for their thermal dimensioning

    International Nuclear Information System (INIS)

    Nisol, R.

    1976-01-01

    The role of the shielded conductors as power dissipation feeder from the generator towards the network is recalled. Their natural cooling limits and the possibilities of forced cooling are examined. The known incidence of short-circuit currents upon the components of the generator-network connection is reported [fr

  10. Cooling systems for efficient operation of induction heating installations; Kuehlsysteme fuer den effizienten Betrieb von Induktionsschmelzanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Doetsch, Erwin; Schmidt, Juergen [ABP Induction Systems GmbH, Dortmund (Germany)

    2009-12-15

    Electrical and thermal losses in the system components of induction melting systems are mainly carried off by the cooling water. The design and maintenance of the corresponding cooling systems play a decisive role in the operating reliability of induction installations. Due to the differing requirements made on water quality, cooling of the furnace and the electrical components is generally accomplished by means of two independent cooling circuits, which are described below. The article also examines utilization of waste-heat, which has a particular significance for energy-efficiency, since more than a fourth of the furnace power, in the case of melting of ferrous materials, and more than half, in the case of non-ferrous materials, is lost. (orig.)

  11. Emergency cooling system for the PHENIX reactor

    International Nuclear Information System (INIS)

    Megy, J.M.; Giudicelli, A.G.; Robert, E.A.; Crette, J.P.

    Among various engineered safeguards of the reactor plant, the authors describe the protective system designed to remove the decay heat in emergency, in case of complete loss of all normal decay heat removal systems. First the normal decay heat rejection systems are presented. Incidents leading to the loss of these normal means are then analyzed. The protective system and its constructive characteristics designed for emergency cooling and based on two independent and highly reliable circuits entirely installed outside the primary containment vessel are described

  12. Monitoring of primary circuit and reactor of NPP A-1

    International Nuclear Information System (INIS)

    Prazska, M.; Majersky, M.; Rezbarik, J.; Sekely, S.; Vozarik, P.; Walthery, R.; Stuller, P.

    2005-01-01

    Nuclear Power Plant A-1 in Jaslovske Bohunice was commissioned in 1972. Heavy water moderated, carbon dioxide cooled channel type reactor was shut down after two accidents in 1977. During more serious second accident, the reduced coolant flow caused local overheating of the fuel and consequent damage/melting of the fuel channel. Both accidents had led to the damage of several fuel assemblies with extensive local damage of fuel claddings. As a consequence, the main cooling circuit was significantly contaminated by fission products and long-life alpha nuclides. The detailed monitoring of dose rates, smearable contamination and sampling of contamination was performed. Extended monitoring in reacto vessel, primary circuit pipes, turbo-compressors, steam generators, main valves, gas tanks and also heavy water system with collectors, coolers, distilling and purification station, pumps and valves was done. Appropriate devices and procedures for the monitoring and examination of the installations were prepared and applied. Obtained results will serve for the future planning of the decontamination and decommissioning works. The 3-D model of the reactor that had been developed as part of this Project proved invaluable for orientation, visualisation, planning and analysis of results. Dose rates were measured in the technological channels from the reactor hall floor to the bottom of the hot gas chamber in decrements of 1 m and 0.5 m. The highest absolute values of dose rates were found in channels located in the middle of the reactor (up to 1900 mGy/h in the active zone region). It is estimated that the total contaminated area of primary circuit equipment (pipework, steam generators and turbo-compressors) is some 48 000 m 2 . It follows that the total gamma contamination is of the order of 10 14 to 10 15 Bq and total alpha contamination 10 11 to 10 13 Bq. The total amount of deposits in the gas circuit is about 14.3 tons. (authors)

  13. Feasibility study of superconducting power cables for DC electric railway feeding systems in view of thermal condition at short circuit accident

    Science.gov (United States)

    Kumagai, Daisuke; Ohsaki, Hiroyuki; Tomita, Masaru

    2016-12-01

    A superconducting power cable has merits of a high power transmission capacity, transmission losses reduction, a compactness, etc., therefore, we have been studying the feasibility of applying superconducting power cables to DC electric railway feeding systems. However, a superconducting power cable is required to be cooled down and kept at a very low temperature, so it is important to reveal its thermal and cooling characteristics. In this study, electric circuit analysis models of the system and thermal analysis models of superconducting cables were constructed and the system behaviors were simulated. We analyzed the heat generation by a short circuit accident and transient temperature distribution of the cable to estimate the value of temperature rise and the time required from the accident. From these results, we discussed a feasibility of superconducting cables for DC electric railway feeding systems. The results showed that the short circuit accident had little impact on the thermal condition of a superconducting cable in the installed system.

  14. Oscillator circuits

    CERN Document Server

    Graf, Rudolf F

    1996-01-01

    This series of circuits provides designers with a quick source for oscillator circuits. Why waste time paging through huge encyclopedias when you can choose the topic you need and select any of the specialized circuits sorted by application?This book in the series has 250-300 practical, ready-to-use circuit designs, with schematics and brief explanations of circuit operation. The original source for each circuit is listed in an appendix, making it easy to obtain additional information.Ready-to-use circuits.Grouped by application for easy look-up.Circuit source listing

  15. Measuring circuits

    CERN Document Server

    Graf, Rudolf F

    1996-01-01

    This series of circuits provides designers with a quick source for measuring circuits. Why waste time paging through huge encyclopedias when you can choose the topic you need and select any of the specialized circuits sorted by application?This book in the series has 250-300 practical, ready-to-use circuit designs, with schematics and brief explanations of circuit operation. The original source for each circuit is listed in an appendix, making it easy to obtain additional information.Ready-to-use circuits.Grouped by application for easy look-up.Circuit source listings

  16. Thermoelectricity from wasted heat of integrated circuits

    KAUST Repository

    Fahad, Hossain M.

    2012-05-22

    We demonstrate that waste heat from integrated circuits especially computer microprocessors can be recycled as valuable electricity to power up a portion of the circuitry or other important accessories such as on-chip cooling modules, etc. This gives a positive spin to a negative effect of ever increasing heat dissipation associated with increased power consumption aligned with shrinking down trend of transistor dimension. This concept can also be used as an important vehicle for self-powered systemson- chip. We provide theoretical analysis supported by simulation data followed by experimental verification of on-chip thermoelectricity generation from dissipated (otherwise wasted) heat of a microprocessor.

  17. The pretzel sign: angiographic pattern of tortuous intra-aneurysmal blood flow in a giant serpentine aneurysm.

    LENUS (Irish Health Repository)

    Fanning, N F

    2012-02-03

    Giant serpentine aneurysms (GSAs) form a specific subgroup of giant cerebral aneurysms that have pathognomonic angiographic features. We report the angiographic findings of a GSA demonstrating a striking convoluted dynamic flow pattern, which we have called the \\'pretzel sign\\'. The aneurysm was successfully treated by permanent occlusion of the parent vessel using a detachable balloon. GSAs should be identified prior to treatment in view of their particular management requirements.

  18. Out of the dark: Transitional subsurface-to-surface microbial diversity in a terrestrial serpentinizing seep (Manleluag, Pangasinan, the Philippines

    Directory of Open Access Journals (Sweden)

    Kristin eWoycheese

    2015-02-01

    Full Text Available In the Zambales ophiolite range terrestrial serpentinizing fluid seeps host diverse microbial assemblages. The fluids fall within the profile of Ca2+-OH--type waters, indicative of active serpentinization, and are low in dissolved inorganic carbon (<0.5 ppm. Influx of atmospheric carbon dioxide affects the solubility of calcium carbonate as distance from the source increases, triggering the formation of meter-scale travertine terraces. Samples were collected at the source and along the outflow channel to determine subsurface microbial community response to surface exposure. DNA was extracted and submitted for high-throughput 16S rRNA gene sequencing on the Illumina MiSeq platform. Taxonomic assignment of the sequence data indicates that 8.1% of the total sequence reads at the source of the seep affiliate with the genus Methanobacterium. Other major classes detected at the source include anaerobic taxa such as Bacteroidetes (40.7% of total sequence reads and Firmicutes (19.1% of total reads. Hydrogenophaga spp. increase in relative abundance as redox potential increases. At the carbonate terrace, 45% of sequence reads affiliate with Meiothermus spp. Taxonomic observations and geochemical data suggest that several putative metabolisms may be favorable, including hydrogen oxidation, H2-associated sulfur cycling, methanogenesis, methanotrophy, nitrogen fixation, ammonia oxidation, denitrification, nitrate respiration, methylotrophy, carbon monoxide respiration, and ferrous iron oxidation, based on capabilities of nearest known neighbors. Scanning electron microscopy and energy dispersive X-ray spectroscopy suggest that microbial activity produces chemical and physical traces in the precipitated carbonates forming downstream of the seep’s source. These data provide context for future serpentinizing seep ecosystem studies, particularly with regards to tropical biomes.

  19. Characterization of natural circulation looping of emergency cooling systems in naval and advanced reactors

    International Nuclear Information System (INIS)

    Macedo, Luiz Alberto; Baptista Filho, Benedito Dias

    2000-01-01

    This paper describes the natural circuit looping, resumes the main project characteristics, presents results of the hydraulic characterization, consisting of pressure loss measurements, and presents results from calibration tests of the power and flow measurements and the first experiments in natural circulation. Those experiments comprised transients in natural circulation with application of application of power steps. The results shown a non linear behaviour of the magnetic flow meter and a dependence on the fluid temperature as well. The assembly circuit/instrumentation/data acquisition system is suitable for the research on emergency cooling passive systems

  20. Jumping-droplet electronics hot-spot cooling

    Science.gov (United States)

    Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; Yin, Sabrina L.; Rentauskas, Michelle; Neely, Jason; Pilawa-Podgurski, Robert C. N.; Miljkovic, Nenad

    2017-03-01

    Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm × 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25 °C air temperature, 20%-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm) and applied heat flux (demonstrated to 13 W/cm2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm2. This work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.

  1. Jumping-droplet electronics hot-spot cooling

    International Nuclear Information System (INIS)

    Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; Yin, Sabrina L.; Rentauskas, Michelle

    2017-01-01

    Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm x 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25°C air temperature, 20-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm), and heat flux (demonstrated to 13 W/cm"2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈ 200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm"2. Finally, this work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.

  2. Two phase cooling for superconducting magnets

    International Nuclear Information System (INIS)

    Eberhard, P.H.; Gibson, G.A.; Green, M.A.; Ross, R.R.; Smits, R.G.; Taylor, J.D.; Watt, R.D.

    1985-08-01

    A closed circuit tubular cooling system for superconducting magnets offers advantages of limiting boiloff and containing high pressures during quenches. Proper location of automatic valves to lower pressures and protect the refrigerator in the event of quenches is described. Theoretical arguments and exprimental evidence are given against a previously suggested method to determine He two phase flow regimes. If loss of flow occurs due to some types of refrigeration failure and transfer lines have enough heat leak to warm up, quenches are induced when the flow is restored. Examples are taken from experience with the TPC magnet

  3. Resonance circuits for adiabatic circuits

    Directory of Open Access Journals (Sweden)

    C. Schlachta

    2003-01-01

    Full Text Available One of the possible techniques to reduces the power consumption in digital CMOS circuits is to slow down the charge transport. This slowdown can be achieved by introducing an inductor in the charging path. Additionally, the inductor can act as an energy storage element, conserving the energy that is normally dissipated during discharging. Together with the parasitic capacitances from the circuit a LCresonant circuit is formed.

  4. Bringing Together Evolution on Serpentine and Polyploidy: Spatiotemporal History of the Diploid-Tetraploid Complex of Knautia arvensis (Dipsacaceae)

    Czech Academy of Sciences Publication Activity Database

    Kolář, Filip; Fér, T.; Štech, M.; Trávníček, Pavel; Dušková, E.; Schönswetter, P.; Suda, Jan

    2012-01-01

    Roč. 7, č. 7 (2012), e39988 E-ISSN 1932-6203 R&D Projects: GA AV ČR KJB600050812; GA AV ČR(CZ) KJB601110627 Institutional research plan: CEZ:AV0Z6005908 Institutional support: RVO:67985939 Keywords : serpentine spetiation * Knautia arvensis * polyploidy Subject RIV: EF - Botanics Impact factor: 3.730, year: 2012

  5. Preparation and utilization of amorphous siliceous materials from serpentine (Mg3Si2O5(OH)4) by acid treatment; Jamonseki no kofuka kachika ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-30

    Concerning the conversion of serpentine, not only its magnesium component but also silica component, into industrial materials, conditions suitable for the production of porous materials and amorphous silica by acid treatment were evaluated, and the properties of the products were evaluated. The silica resulting from the acid treatment of serpentine comes out in different forms, each reflecting the structure of the parent rock, that is, an amorphous mass of planar particles from antigorite and a fascicular mass of filaments from chrysotile. A microporic structure resulted when a small quantity of magnesium was allowed to remain in the skeleton structure and acid treatment conditions were properly adjusted. Several siliceous compounds were prepared for the purpose of finding use for silica from this rock, and then it was found that high-efficiency production of high-crystallinity compounds was possible and that they were furnished with properties fit for use as materials. Furthermore, study was made about the kaolinite reaction in which serpentine would be directly converted into useful materials. 105 refs., 55 figs., 6 tabs.

  6. A cooling concept for improved field winding performance in large superconducting ac generators

    International Nuclear Information System (INIS)

    Laskaris, T.E.

    1977-01-01

    An analytical study of a flow circuit for large superconducting generator rotors is presented. The flow circuit provides regulation of the level of liquid in the rotor externally by adjusting the helium supply pressure. It also protects the vapour cooled structural members of the rotor from overcooling during transient periods of operation. Furthermore, it is capable of reducing the winding temperature below 4.2 K thereby enhancing the superconductor's performance. For example, a large generator rotor with NbTi superconducting field winding experiences approximately a 50% increase in its critical current density compared to that at 4.2 K. (author)

  7. Cooling system for the connecting rings of a fast neutron reactor vessel

    International Nuclear Information System (INIS)

    Martin, J.-P.; Malaval, Claude

    1974-01-01

    A description is given of a cooling system for the vessel connecting rings of a fast neutron nuclear reactor, particularly of a main vessel containing the core of the reactor and a volume of liquid metal coolant at high temperature and a safety vessel around the main vessel, both vessels being suspended to a rigid upper slab kept at a lower temperature. It is mounted in the annular space between the two vessels and includes a neutral gas circuit set up between the wall of the main vessel to be cooled and that of the safety vessel itself cooled from outer. The neutral gas system comprises a plurality of ventilators fitted in holes made through the thickness of the upper slab and opening on to the space between the two vessels. It also includes two envelopes lining the walls of these vessels, establishing with them small section channels for the circulation of the neutral gas cooled against the safety vessel and heated against the main vessel [fr

  8. Evolution of fracture permeability of ultramafic rocks undergoing serpentinization at hydrothermal conditions: An experimental study

    Science.gov (United States)

    Farough, Aida; Moore, Diane E.; Lockner, David A.; Lowell, R.P.

    2016-01-01

    We performed flow-through laboratory experiments on five cylindrically cored samples of ultramafic rocks, in which we generated a well-mated through-going tensile fracture, to investigate evolution of fracture permeability during serpentinization. The samples were tested in a triaxial loading machine at a confining pressure of 50 MPa, pore pressure of 20 MPa, and temperature of 260°C, simulating a depth of 2 km under hydrostatic conditions. A pore pressure difference of up to 2 MPa was imposed across the ends of the sample. Fracture permeability decreased by 1–2 orders of magnitude during the 200–330 h experiments. Electron microprobe and SEM data indicated the formation of needle-shaped crystals of serpentine composition along the walls of the fracture, and chemical analyses of sampled pore fluids were consistent with dissolution of ferro-magnesian minerals. By comparing the difference between fracture permeability and matrix permeability measured on intact samples of the same rock types, we concluded that the contribution of the low matrix permeability to flow is negligible and essentially all of the flow is focused in the tensile fracture. The experimental results suggest that the fracture network in long-lived hydrothermal circulation systems can be sealed rapidly as a result of mineral precipitation, and generation of new permeability resulting from a combination of tectonic and crystallization-induced stresses is required to maintain fluid circulation.

  9. Thermal and hydrodynamic studies for micro-channel cooling for large area silicon sensors in high energy physics experiments

    Energy Technology Data Exchange (ETDEWEB)

    Flaschel, Nils; Ariza, Dario; Diez, Sergio; Gregor, Ingrid-Maria; Tackmann, Kerstin [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gerboles, Marta; Jorda, Xavier; Mas, Roser; Quirion, David; Ullan, Miguel [Centro Nacional de Microelectronica, Barcelona (Spain)

    2017-01-15

    Micro-channel cooling initially aiming at small-sized high-power integrated circuits is being transferred to the field of high energy physics. Today's prospects of micro-fabricating silicon opens a door to a more direct cooling of detector modules. The challenge in high energy physics is to save material in the detector construction and to cool large areas. In this paper, we are investigating micro-channel cooling as a candidate for a future cooling system for silicon detectors in a generic research and development approach. The work presented in this paper includes the production and the hydrodynamic and thermal testing of a micro-channel equipped prototype optimized to achieve a homogeneous flow distribution. Furthermore, the device was simulated using finite element methods.

  10. Thermal and hydrodynamic studies for micro-channel cooling for large area silicon sensors in high energy physics experiments

    International Nuclear Information System (INIS)

    Flaschel, Nils; Ariza, Dario; Diez, Sergio; Gregor, Ingrid-Maria; Tackmann, Kerstin; Gerboles, Marta; Jorda, Xavier; Mas, Roser; Quirion, David; Ullan, Miguel

    2017-01-01

    Micro-channel cooling initially aiming at small-sized high-power integrated circuits is being transferred to the field of high energy physics. Today's prospects of micro-fabricating silicon opens a door to a more direct cooling of detector modules. The challenge in high energy physics is to save material in the detector construction and to cool large areas. In this paper, we are investigating micro-channel cooling as a candidate for a future cooling system for silicon detectors in a generic research and development approach. The work presented in this paper includes the production and the hydrodynamic and thermal testing of a micro-channel equipped prototype optimized to achieve a homogeneous flow distribution. Furthermore, the device was simulated using finite element methods.

  11. Simulation and experimental study on lithium ion battery short circuit

    International Nuclear Information System (INIS)

    Zhao, Rui; Liu, Jie; Gu, Junjie

    2016-01-01

    Highlights: • Both external and internal short circuit tests were performed on Li-ion batteries. • An electrochemical–thermal model with an additional nail site heat source is presented. • The model can accurately simulate the temperature variations of non-venting batteries. • The model is reliable in predicting the occurrence and start time of thermal runaway. • A hydrogel cooling system proves its strength in preventing battery thermal runaway. - Abstract: Safety is the first priority in lithium ion (Li-ion) battery applications. A large portion of electrical and thermal hazards caused by Li-ion battery is associated with short circuit. In this paper, both external and internal short circuit tests are conducted. Li-ion batteries and battery packs of different capacities are used. The results indicate that external short circuit is worse for smaller size batteries due to their higher internal resistances, and this type of short can be well managed by assembling fuses. In internal short circuit tests, higher chance of failure is found on larger capacity batteries. A modified electrochemical–thermal model is proposed, which incorporates an additional heat source from nail site and proves to be successful in depicting temperature changes in batteries. Specifically, the model is able to estimate the occurrence and approximate start time of thermal runaway. Furthermore, the effectiveness of a hydrogel based thermal management system in suppressing thermal abuse and preventing thermal runaway propagation is verified through the external and internal short tests on batteries and battery packs.

  12. Temperature control system for the study of single event effects in integrated circuits using a cyclotron accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Bakerenkov, A.S., E-mail: as_bakerenkov@list.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Belyakov, V.V. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Kozyukov, A.E. [Joint-Stock Company Institute of Space Device Engineering (JSC ISDE), Moscow (Russian Federation); Pershenkov, V.S.; Solomatin, A.V.; Shurenkov, V.V. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation)

    2015-02-11

    The temperature control system for the study of single event disruptions produced by hard ion impacts in integrated circuits is described. Heating and cooling of the irradiated device are achieved using thermoelectric modules (Peltier modules). The thermodynamic performance of the system is estimated. The technique for the numerical estimation of the main parameters of the temperature control system for cooling and heating is considered. The results of a test of the system in a vacuum cell of an accelerator are presented.

  13. Temperature control system for the study of single event effects in integrated circuits using a cyclotron accelerator

    International Nuclear Information System (INIS)

    Bakerenkov, A.S.; Belyakov, V.V.; Kozyukov, A.E.; Pershenkov, V.S.; Solomatin, A.V.; Shurenkov, V.V.

    2015-01-01

    The temperature control system for the study of single event disruptions produced by hard ion impacts in integrated circuits is described. Heating and cooling of the irradiated device are achieved using thermoelectric modules (Peltier modules). The thermodynamic performance of the system is estimated. The technique for the numerical estimation of the main parameters of the temperature control system for cooling and heating is considered. The results of a test of the system in a vacuum cell of an accelerator are presented

  14. COOLING COIL EFFECTS ON BLENDING IN A PILOT SCALE TANK

    International Nuclear Information System (INIS)

    Leishear, R.; Poirier, M.; Fowley, M.; Steeper, T.

    2010-01-01

    Blending, or mixing, processes in 1.3 million gallon nuclear waste tanks are complicated by the fact that miles of serpentine, vertical, cooling coils are installed in the tanks. As a step toward investigating blending interference due to coils in this type of tank, a 1/10.85 scale tank and pump model were constructed for pilot scale testing. A series of tests were performed in this scaled tank by adding blue dye to visualize blending, and by adding acid or base tracers to solution to quantify the time required to effectively blend the tank contents. The acid and base tests were monitored with pH probes, which were located in the pilot scale tank to ensure that representative samples were obtained. Using the probes, the hydronium ion concentration [H + ] was measured to ensure that a uniform concentration was obtained throughout the tank. As a result of pilot scale testing, a significantly improved understanding of mixing, or blending, in nuclear waste tanks has been achieved. Evaluation of test data showed that cooling coils in the waste tank model increased pilot scale blending times by 200% in the recommended operating range, compared to previous theoretical estimates of a 10-50% increase. Below the planned operating range, pilot scale blending times were increased by as much as 700% in a tank with coils installed. One pump, rather than two or more, was shown to effectively blend the tank contents, and dual pump nozzles installed parallel to the tank wall were shown to provide optimal blending. In short, experimental results varied significantly from expectations.

  15. Analysis of water hammer phenomena in RBMK-1500 reactor main circulation circuit

    International Nuclear Information System (INIS)

    Kaliatka, A.; Uspuras, E.; Vaisnoras, M.

    2006-01-01

    Water hammer can occur in any thermal-hydraulic systems. Water hammer can reach pressure levels far exceeding the pressure range of a pipe given by the manufacturer, and it can lead to the failure of the pipeline integrity. In the past three decades, since a large number of water hammer events occurred in the light-water- reactor power plants, a number of comprehensive studies on the phenomena associated with water hammer events have been performed. There are three basic types of severe water hammer occurring at power plants that can result in significant plant damage: rapid valve operation events; void-induced water hammer; condensation-induced water hammer. Correct prediction of water hammer transients, is therefore of paramount importance for the safe operation of the plant. Therefore verifying of computer codes capability to simulate water hammer type transients is very important issue at performing of safety analyses for nuclear power plants. Verification of RELAP5/MOD3.3 code capability to simulate water hammer type transients employing the experimental investigations is presented. Experience gained from benchmarking analyses has been used at development of the detail RELAP5 code RBMK-1500 model for simulation of water hammer effects in reactor main circulation circuit. Analysis of reactor cooling system shows, that water hammers can occur in main circulation circuit of RBMK-1500 reactor in cases of: (1) Guillotine break of the inlet piping upstream of the Group Distribution Header and (2) Guillotine break of the pressure piping upstream the Main Circulation Pump check valve. Analysis of above mentioned accident scenarios is presented in this paper. First scenario of the accident potentially is more dangerous, because the pressure pulses influence not only the reactor cooling circuit, but also the piping of safety related system (Emergency Core Cooling System pipeline) connected to affected Group Distribution Header. The performed analysis using RELAP5 code

  16. Development of a higher power cooling system for lithium targets.

    Science.gov (United States)

    Phoenix, B; Green, S; Scott, M C; Bennett, J R J; Edgecock, T R

    2015-12-01

    The accelerator based Boron Neutron Capture Therapy beam at the University of Birmingham is based around a solid thick lithium target cooled by heavy water. Significant upgrades to Birmingham's Dynamitron accelerator are planned prior to commencing a clinical trial. These upgrades will result in an increase in maximum achievable beam current to at least 3 mA. Various upgrades to the target cooling system to cope with this increased power have been investigated. Tests of a phase change coolant known as "binary ice" have been carried out using an induction heater to provide a comparable power input to the Dynamitron beam. The experimental data shows no improvement over chilled water in the submerged jet system, with both systems exhibiting the same heat input to target temperature relation for a given flow rate. The relationship between the cooling circuit pumping rate and the target temperature in the submerged jet system has also been tested. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Project Circuits in a Basic Electric Circuits Course

    Science.gov (United States)

    Becker, James P.; Plumb, Carolyn; Revia, Richard A.

    2014-01-01

    The use of project circuits (a photoplethysmograph circuit and a simple audio amplifier), introduced in a sophomore-level electric circuits course utilizing active learning and inquiry-based methods, is described. The development of the project circuits was initiated to promote enhanced engagement and deeper understanding of course content among…

  18. Experimental determination of average turbulent heat transfer and friction factor in stator internal rib-roughened cooling channels.

    Science.gov (United States)

    Battisti, L; Baggio, P

    2001-05-01

    In gas turbine cooling design, techniques for heat extraction from the surfaces exposed to the hot stream are based on the increase of the inner heat transfer areas and on the promotion of the turbulence of the cooling flow. This is currently obtained by casting periodic ribs on one or more sides of the serpentine passages into the core of the blade. Fluid dynamic and thermal behaviour of the cooling flow have been extensively investigated by means of experimental facilities and many papers dealing with this subject have appeared in the latest years. The evaluation of the average value of the heat transfer coefficient most of the time is inferred from local measurements obtained by various experimental techniques. Moreover the great majority of these studies are not concerned with the overall average heat transfer coefficient for the combined ribs and region between them, but do focus just on one of them. This paper presents an attempt to collect information about the average Nusselt number inside a straight ribbed duct. Series of measurements have been performed in steady state eliminating the error sources inherently connected with transient methods. A low speed wind tunnel, operating in steady state flow, has been built to simulate the actual flow condition occurring in a rectilinear blade cooling channel. A straight square channel with 20 transverse ribs on two sides has been tested for Re of about 3 x 10(4), 4.5 x 10(4) and 6 x 10(4). The ribbed wall test section is electrically heated and the heat removed by a stationary flow of known thermal and fluid dynamic characteristics.

  19. Ultra-High Resolution Ion Mobility Separations Utilizing Traveling Waves in a 13 m Serpentine Path Length Structures for Lossless Ion Manipulations Module

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Liulin; Ibrahim, Yehia M.; Hamid, Ahmed M.; Garimella, Sandilya V. B.; Webb, Ian K.; Zheng, Xueyun; Prost, Spencer A.; Sandoval, Jeremy A.; Norheim, Randolph V.; Anderson, Gordon A.; Tolmachev, Aleksey V.; Baker, Erin S.; Smith, Richard D.

    2016-09-20

    We report the development and initial evaluation of a 13-m path length Structures for Lossless Manipulations (SLIM) module for achieving high resolution separations using traveling waves (TW) with ion mobility (IM) spectrometry. The TW SLIM module was fabricated using two mirror-image printed circuit boards with appropriately configured RF, DC and TW electrodes and positioned with a 2.75-mm inter-surface gap. Ions were effective confined between the surfaces by RF-generated pseudopotential fields and moved losslessly through a serpentine path including 44 “U” turns using TWs. The ion mobility resolution was characterized at different pressures, gaps between the SLIM surfaces, TW and RF parameters. After initial optimization the SLIM IM-MS module provided about 5-fold higher resolution separations than present commercially available drift tube or traveling wave IM-MS platforms. Peak capacity and peak generation rates achieved were 246 and 370 s-1, respectively, at a TW speed of 148 m/s. The high resolution achieved in the TW SLIM IM-MS enabled e.g., isomeric sugars (Lacto-N-fucopentaose I and Lacto-N-fucopentaose II) to be baseline resolved, and peptides from a albumin tryptic digest much better resolved than with existing commercial IM-MS platforms. The present work also provides a foundation for the development of much higher resolution SLIM devices based upon both considerably longer path lengths and multi-pass designs.

  20. Total Dose Effects on Bipolar Integrated Circuits at Low Temperature

    Science.gov (United States)

    Johnston, A. H.; Swimm, R. T.; Thorbourn, D. O.

    2012-01-01

    Total dose damage in bipolar integrated circuits is investigated at low temperature, along with the temperature dependence of the electrical parameters of internal transistors. Bandgap narrowing causes the gain of npn transistors to decrease far more at low temperature compared to pnp transistors, due to the large difference in emitter doping concentration. When irradiations are done at temperatures of -140 deg C, no damage occurs until devices are warmed to temperatures above -50 deg C. After warm-up, subsequent cooling shows that damage is then present at low temperature. This can be explained by the very strong temperature dependence of dispersive transport in the continuous-time-random-walk model for hole transport. For linear integrated circuits, low temperature operation is affected by the strong temperature dependence of npn transistors along with the higher sensitivity of lateral and substrate pnp transistors to radiation damage.

  1. Modeling and Simulation of Truck Engine Cooling System for Onboard Diagnosis

    Institute of Scientific and Technical Information of China (English)

    朱正礼; 张建武; 包继华

    2004-01-01

    A cooling system model of a selected internal combustion engine has been built for onboard diagnosis. The model uses driving cycle data available within the production Engine Control Module (ECM): vehicle speed, engine speed, and fuel flow rate for the given ambient temperature and pressure, etc. Based on the conservation laws for heat transfer and mass flow process, the mathematical descriptions for the components involved in the cooling circuit are obtained and all the components are integrated into a model on Matlab/Simulink platform. The model can simulate the characteristics of thermostat (e.g. time-lag, hysteresis effect).The changes of coolant temperature, heat transfer flow rate, and pressure at individual component site are also shown.

  2. CPV cells cooling system based on submerged jet impingement: CFD modeling and experimental validation

    Science.gov (United States)

    Montorfano, Davide; Gaetano, Antonio; Barbato, Maurizio C.; Ambrosetti, Gianluca; Pedretti, Andrea

    2014-09-01

    Concentrating photovoltaic (CPV) cells offer higher efficiencies with regard to the PV ones and allow to strongly reduce the overall solar cell area. However, to operate correctly and exploit their advantages, their temperature has to be kept low and as uniform as possible and the cooling circuit pressure drops need to be limited. In this work an impingement water jet cooling system specifically designed for an industrial HCPV receiver is studied. Through the literature and by means of accurate computational fluid dynamics (CFD) simulations, the nozzle to plate distance, the number of jets and the nozzle pitch, i.e. the distance between adjacent jets, were optimized. Afterwards, extensive experimental tests were performed to validate pressure drops and cooling power simulation results.

  3. Thermoelectric cooling of microelectronic circuits and waste heat electrical power generation in a desktop personal computer

    International Nuclear Information System (INIS)

    Gould, C.A.; Shammas, N.Y.A.; Grainger, S.; Taylor, I.

    2011-01-01

    Thermoelectric cooling and micro-power generation from waste heat within a standard desktop computer has been demonstrated. A thermoelectric test system has been designed and constructed, with typical test results presented for thermoelectric cooling and micro-power generation when the computer is executing a number of different applications. A thermoelectric module, operating as a heat pump, can lower the operating temperature of the computer's microprocessor and graphics processor to temperatures below ambient conditions. A small amount of electrical power, typically in the micro-watt or milli-watt range, can be generated by a thermoelectric module attached to the outside of the computer's standard heat sink assembly, when a secondary heat sink is attached to the other side of the thermoelectric module. Maximum electrical power can be generated by the thermoelectric module when a water cooled heat sink is used as the secondary heat sink, as this produces the greatest temperature difference between both sides of the module.

  4. Radiolytic reactions in the coolant of helium cooled reactors

    International Nuclear Information System (INIS)

    Tingey, G.L.; Morgan, W.C.

    1975-01-01

    The success of helium cooled reactors is dependent upon the ability to prevent significant reaction between the coolant and the other components in the reactor primary circuit. Since the thermal reaction of graphite with oxidizing gases is rapid at temperatures of interest, the thermal reactions are limited primarily by the concentration of impurity gases in the helium coolant. On the other hand, the rates of radiolytic reactions in helium are shown to be independent of reactive gas concentration until that concentration reaches a very low level. Calculated steady-state concentrations of reactive species in the reactor coolant and core burnoff rates are presented for current U. S. designed, helium cooled reactors. Since precise base data are not currently available for radiolytic rates of some reactions and thermal reaction rate data are often variable, the accuracy of the predicted gas composition is being compared with the actual gas compositions measured during startup tests of the Fort Saint Vrain high temperature gas-cooled reactor. The current status of these confirmatory tests is discussed. 12 references

  5. Exergy Analysis of Serpentine Thermosyphon Solar Water Heater

    Directory of Open Access Journals (Sweden)

    Muhammad Faisal Hasan

    2018-03-01

    Full Text Available The performance of a solar hot water system is assessed for heat pump and domestic heating applications. Thermodynamic analysis on a serpentine-type thermosyphon flat-plate solar heater is conducted using the Second Law of thermodynamics. Exergetic optimization is first performed to determine the parameters for the maximum exergy efficiency using MATLAB optimization toolbox. Geometric parameters (collector surface area, dimensions, and pipe diameter, optical parameters (transmittance absorptance product, ambient temperature, solar irradiation and operating parameters (mass flow rate, fluid temperature, and overall heat transfer (loss coefficient are accounted for in the optimization scheme. The exergy efficiency at optimum condition is found to be 3.72%. The results are validated using experimental data and found to be in good agreement. The analysis is further extended to the influence of various operating parameters on the exergetic efficiency. It is observed that optical and thermal exergy losses contribute almost 20%, whereas approximately 77% exergy destruction is contributed by the thermal energy conversion. Exergy destruction due to pressure drop is found negligible. The result of this analysis can be used for designing and optimization of domestic heat pump system and hot water application.

  6. The transpiration cooled first wall and blanket concept

    International Nuclear Information System (INIS)

    Barleon, Leopold; Wong, Clement

    2002-01-01

    To achieve high thermal performance at high power density the EVOLVE concept was investigated under the APEX program. The EVOLVE W-alloy first wall and blanket concept proposes to use transpiration cooling of the first wall and boiling or vaporizing lithium (Li) in the blanket zone. Critical issues of this concept are: the Magnetohydrodynamic (MHD) pressure losses of the Li circuit, the evaporation through a capillary structure and the needed superheating of the Li at the first wall and blanket zones. Application of the transpiration concept to the blanket region results in the integrated transpiration cooling concept (ITCC) with either toroidal or poloidal first wall channels. For both orientations the routing of the liquid Li and the Li vapor has been modeled and the corresponding pressure losses have been calculated by varying the width of the supplying slot and the capillary diameter. The concept works when the sum of the active and passive pumping head is higher than the total system pressure losses and when the temperature at the inner side of the first wall does not override the superheating limit of the coolant. This cooling concept has been extended to the divertor design, and the removal of a surface heat flux of up to 10 MW/m 2 appears to be possible, but this paper will focus on the transpiration cooled first wall and blanket concept assessment

  7. Serpentine soils affect heavy metal tolerance but not genetic diversity in a common Mediterranean ant.

    Science.gov (United States)

    Frizzi, Filippo; Masoni, Alberto; Çelikkol, Mine; Palchetti, Enrico; Ciofi, Claudio; Chelazzi, Guido; Santini, Giacomo

    2017-08-01

    Natural habitats with serpentine soils are rich in heavy metal ions, which may significantly affect ecological communities. Exposure to metal pollutants results, for instance, in a reduction of population genetic diversity and a diffused higher tolerance towards heavy metals. In this study, we investigated whether chronic exposure to metals in serpentine soils affect accumulation patterns, tolerance towards metal pollutants, and genetic diversity in ants. In particular, we studied colonies of the common Mediterranean ant, Crematogaster scutellaris, along a contamination gradient consisting of two differently contaminated forests and a reference soil with no geogenic contamination. We first evaluated the metal content in both soil and ants' body. Then, we tested for tolerance towards metal pollutants by evaluating the mortality of ants fed with nickel (Ni) solutions of increasing concentrations. Finally, differences in genetic diversity among ants from different areas were assessed using eight microsatellite loci. Interestingly, a higher tolerance to nickel solutions was found in ants sampled in sites with intermediate levels of heavy metals. This may occur, because ants inhabiting strongly contaminated areas tend to accumulate higher amounts of contaminants. Additional ingestion of toxicants beyond the saturation threshold would lead to death. There was no difference in the genetic diversity among ant colonies sampled in different sites. This was probably the result of queen mediated gene flow during nuptial flights across uncontaminated and contaminated areas of limited geographical extent. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Insights into iodine behaviour and speciation in the Phébus primary circuit

    International Nuclear Information System (INIS)

    Girault, N.; Payot, F.

    2013-01-01

    Highlights: • Unexpectedly, gaseous iodine was transported in the circuit during some test periods. • The highest gaseous iodine fraction was measured in FPT3. • Several iodine vapours were evidenced in the hot leg, CsI being not predominant. • Equilibrium gas-phase chemistry do not explain the experimental iodine results. • Kinetic limitations in iodine reactions probably played a significant role. - Abstract: The Phébus FP integral test series studies a large spectrum of the phenomenology of severe accidents in water-cooled nuclear reactors. These tests represent a unique source of representative integral source term data, covering fuel rod degradation and behaviour of fission-products released via the coolant system into the containment. The present analysis concerns the behaviour of iodine in the test circuit representing the Reactor Coolant System (RCS) which reaches gas temperatures of nearly 1600 °C at the circuit entrance and descending to 150 °C before entry into the containment. The stake in the data analysis is a better understanding of iodine phenomenology in RCS. This is indeed all the more serious as iodine is one of the most radiological important fission products released from the fuel and may exist under highly volatile forms even within cold leg thermal– hydraulics conditions. Complex and coupled phenomena arise in the primary circuit during the tests as the temperature decreases (drops) from the inlet of the circuit to the outlet. These are respectively for the iodine vapours and aerosols: chemical transformation, condensation on walls/aerosols, homogeneous nucleation into aerosols and agglomeration, deposition by thermophoresis. Depending on the location in the primary circuit, a combination of these phenomena occurred simultaneously. The phenomenological behaviour of iodine in RCS will be appraised through the analyses of the iodine transport, retention, vapour speciation and gaseous occurrence in the Phébus FP primary circuit

  9. Emergency core cooling systems

    International Nuclear Information System (INIS)

    Kubokoya, Takashi; Okataku, Yasukuni.

    1984-01-01

    Purpose: To maintain the fuel soundness upon loss of primary coolant accidents in a pressure tube type nuclear reactor by injecting cooling heavy water at an early stage, to suppress the temperature of fuel cans at a lower level. Constitution: When a thermometer detects the temperature rise and a pressure gauge detects that the pressure for the primary coolants is reduced slightly from that in the normal operation upon loss of coolant accidents in the vicinity of the primary coolant circuit, heavy water is caused to flow in the heavy water feed pipeway by a controller. This enables to inject the heavy water into the reactor core in a short time upon loss of the primary coolant accidents to suppress the temperature rise in the fuel can thereby maintain the fuel soundness. (Moriyama, K.)

  10. Impact of NaCl Contamination and Climatic Conditions on the Reliability of Printed Circuit Board Assemblies

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Jellesen, Morten Stendahl; Ambat, Rajan

    2014-01-01

    The effect of climatic conditions and ionic contamination on the reliability of printed circuit board assembly has been investigated in terms of leakage current (LC) and electrochemical migration susceptibility. The change in LC as a function of relative humidity (RH) and temperature was measured...... and 15 $^{\\circ}\\hbox{C}$ –65 $^{\\circ}\\hbox{C}$. The variation of RH at the surface of the test specimens was imposed by 1) increasing the RH of the surrounding air and 2) reducing the temperature of the printed circuit boards using a cooling stage, while maintaining a constant climatic condition...

  11. Methane-bearing fluids in subduction zones: an experimental study of abiotic methanogenesis during serpentinization at 12 kbar and 300°C

    Science.gov (United States)

    Lazar, C.; Manning, C. E.

    2009-12-01

    Serpentinization within subduction zones may generate reduced fluids that contain higher concentrations of abiotic methane than near-surface ultramafic environments. We present preliminary experimental data suggesting that the kinetics of abiotic methanogenesis are enhanced at high pressures. Thermodynamic calculations of C-O-H fluid speciations at the low oxygen fugacities attained during early serpentinization suggest complete conversion of oxidized carbon to methane, yet previous field and experimental investigations have reported fluid compositions with CH4/CO2 far below equilibrium (McCollom and Seewald, 2007). Much experimental work, therefore, has focused on CH4 production rates and the kinetic effects of temperature and mineral catalysis (Horita and Berdt, 1999; Foustoukos and Seyfried, 2004). Methane has been shown experimentally to form at very high pressures (Scott et al, 2004), but the quantitative effect of pressure on methanogenesis kinetics is unknown. We present preliminary results of a comparison of methane production rates at 0.35 and 12 kbar, 300°C, using experiments performed in piston cylinder and cold seal hydrothermal apparatus. Carbon was introduced as a roughly 70 mmol solution of isotopically-labeled formic acid, H13COOH, known to decompose to 13CO2 and H2 at run conditions. Roughly 15 mL of this solution, along with 1.9 mg of natural awaruite (Ni3Fe), was loaded into a gold capsule and then sealed via DC spot welding. Awaruite, a known methane catalyst (Horita and Berndt, 1999), was added to increase the overall rates of all experiments in order to boost the concentration for analysis and as an fO2 buffer appropriate for serpentinization. The experiments were held at T and P for approximately 160 hours. After each run, the capsule was placed in a gas vial and punctured with a needle. The contents of the vial were extracted via gas syringe and injected into gas chromatograph mass spectrometer (GC-MS). CH4 concentration in the 12 kbar run

  12. Requirements on cast steel for the primary coolant circuit of water cooled reactors

    International Nuclear Information System (INIS)

    The most important requirements placed on the structural components of water cooled nuclear reactors include corrosion resistance and mechanical materials properties. Intercrystalline corrosion resistance was tested using the Strauss Test in compliance with the DIN 50914 Standard. Following sensitization between 600 to 700 degC with a dwell time between 15 minutes and 100 hours, a specimen homogeneously annealed with the casting and rapidly water cooled showed no intercrystalline corrosion. Specimens cooled from 1050 degC at a rate of 100 degC per hour showed no unambiguous tendency for intercrystalline corrosion after sensitization; in some cases, however, an initial attack of intercrystalline corrosion was found. It was found that austenitic Cr-Ni cast steel containing 2.5% Mo and about 15% ferrite showed the sensitive intercrystalline corrosion range at higher temperatures and longer dwell times than rolled Cr-Ni steels. In plating the ferritic cast steel with a corrosion resistant plating material, annealing temperature after welding must not exceed 600 to 620 degC otherwise the resistance of the plated layer against intercrystalline corrosion would not be safeguarded, and following annealing for stress removal at a temperature of 600 to 620 degC all requirements must be satisfied by the weld metal and weld transition placed on the initial material. Martensite materials are used for the manufacture of components which are not used under pressure, such as alloys with 13% Cr and 1% to 6% Ni and alloys with 17% Cr and 4% Ni. Carbon content is maintained below 0.10% to guarantee good weldability and the highest corrosion resistance. Cast steels with 13% Cr and 4% Ni after a dwell of 2500 hours in fully desalinated water without oxygen and with 3600 ppm of boron at a test temperature of 95 to 300 degC showed a surface reduction of 0.005 mm annually. In identical conditions except for the water containing oxygen the reduction in surface was 0.05 mm per year. (J.B.)

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

    International Nuclear Information System (INIS)

    Bongratz, R.; Breitbach, G.; Wolters, J.

    1988-01-01

    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 mm 2 , 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)

  14. Experimental study on supersonic film cooling on the surface of a blunt body in hypersonic flow

    International Nuclear Information System (INIS)

    Fu Jia; Yi Shi-He; Wang Xiao-Hu; He Lin; Ge Yong

    2014-01-01

    The experimental study focuses on the heat flux on a double cone blunt body in the presence of tangential-slot supersonic injection into hypersonic flow. The tests are conducted in a contoured axisymmetric nozzle with Mach numbers of 7.3 and 8.1, and the total temperature is about 900 K. The injection Mach number is 3.2, and total temperature is 300 K. A constant voltage circuit is developed to supply the temperature detectors instead of the normally used constant current circuit. The schlieren photographs are presented additionally to visualize the flow and help analyze the pressure relationship between the cooling flow and the main flow. The dependence of the film-cooling effectiveness on flow parameters, i.e. the blow ratio, the convective Mach number, and the attack angle, is determined. A semi-empirical formula is tested by the present data, and is improved for a better correlation. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  15. COOLING WATER ISSUES AND OPPORTUNITIES AT U.S. NUCLEAR POWER PLANTS

    Energy Technology Data Exchange (ETDEWEB)

    Gary Vine

    2010-12-01

    This report has been prepared for the Department of Energy, Office of Nuclear Energy (DOE-NE), for the purpose of providing a status report on the challenges and opportunities facing the U.S. commercial nuclear energy industry in the area of plant cooling water supply. The report was prompted in part by recent Second Circuit and Supreme Court decisions regarding cooling water system designs at existing thermo-electric power generating facilities in the U.S. (primarily fossil and nuclear plants). At issue in the courts have been Environmental Protection Agency regulations that define what constitutes “Best Technology Available” for intake structures that withdraw cooling water that is used to transfer and reject heat from the plant’s steam turbine via cooling water systems, while minimizing environmental impacts on aquatic life in nearby water bodies used to supply that cooling water. The report was also prompted by a growing recognition that cooling water availability and societal use conflicts are emerging as strategic energy and environmental issues, and that research and development (R&D) solutions to emerging water shortage issues are needed. In particular, cooling water availability is an important consideration in siting decisions for new nuclear power plants, and is an under-acknowledged issue in evaluating the pros and cons of retrofitting cooling towers at existing nuclear plants. Because of the significant ongoing research on water issues already being performed by industry, the national laboratories and other entities, this report relies heavily on ongoing work. In particular, this report has relied on collaboration with the Electric Power Research Institute (EPRI), including its recent work in the area of EPA regulations governing intake structures in thermoelectric cooling water systems.

  16. COOLING WATER ISSUES AND OPPORTUNITIES AT U.S. NUCLEAR POWER PLANTS

    International Nuclear Information System (INIS)

    Vine, Gary

    2010-01-01

    This report has been prepared for the Department of Energy, Office of Nuclear Energy (DOE-NE), for the purpose of providing a status report on the challenges and opportunities facing the U.S. commercial nuclear energy industry in the area of plant cooling water supply. The report was prompted in part by recent Second Circuit and Supreme Court decisions regarding cooling water system designs at existing thermo-electric power generating facilities in the U.S. (primarily fossil and nuclear plants). At issue in the courts have been Environmental Protection Agency regulations that define what constitutes 'Best Technology Available' for intake structures that withdraw cooling water that is used to transfer and reject heat from the plant's steam turbine via cooling water systems, while minimizing environmental impacts on aquatic life in nearby water bodies used to supply that cooling water. The report was also prompted by a growing recognition that cooling water availability and societal use conflicts are emerging as strategic energy and environmental issues, and that research and development (R and D) solutions to emerging water shortage issues are needed. In particular, cooling water availability is an important consideration in siting decisions for new nuclear power plants, and is an under-acknowledged issue in evaluating the pros and cons of retrofitting cooling towers at existing nuclear plants. Because of the significant ongoing research on water issues already being performed by industry, the national laboratories and other entities, this report relies heavily on ongoing work. In particular, this report has relied on collaboration with the Electric Power Research Institute (EPRI), including its recent work in the area of EPA regulations governing intake structures in thermoelectric cooling water systems.

  17. France uses the sun to cool its wine: the Banyuls winery solar cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2003-12-01

    The engineering consultancy Tecsol was asked to design a cooling system for a winery that would limit the variations in temperature during the year. Tecsol proposed a solar system. The total investment cost amounted to nearly two million French Francs (300,000 euros), almost double the cost of a conventional air-conditioning system. However, because the solar system reduced the conventional energy needs of the warehouse by about 40%, the French Agency for Environment and Energy Management (ADEME) provided a 37% subsidy for its rational use of energy. The 'Solarclim' solar installation has three functions: it produces hot water via 693 vacuum tube collectors with a useful surface of 130 m{sup 2}. The collectors are fixed to the roof of the wine cellar, which has an angle of 15 deg. Heat from the collectors is transferred to a 1000-litre hot water storage tank; it produces chilled water using a lithium bromide absorption plant with a nominal cooling capacity of 52 kW. This is housed in the technical premises on the lowest level and is used in conjunction with a 180 kW open-circuit cooling tower on the north facade; and the third function combines air-conditioning and, when necessary, space heating. The installation has been operating for 12 years with no particular problems. The equipment is environmentally friendly. The solar heat source avoids CO{sub 2} emissions, the absorption machine does not use CFCs or HCFCs, and the system is totally silent. (UK)

  18. Overview of gas cooled reactors' applications with CATHARE

    International Nuclear Information System (INIS)

    Genevieve Geffraye; Fabrice Bentivoglio; Anne Messie; Alain Ruby; Manuel Saez; Nicolas Tauveron; Ola Widlund

    2005-01-01

    Full text of publication follows: For about four years, CEA has launched feasibility studies of future nuclear advanced systems in a consistent series of Gas Cooled Reactors (GCR) ranging from thermal reactors, as the Very High Temperature Reactor (VHTR) for the mid term, to fast reactors (GFR) for the long term. Thermal hydraulic performances are a key issue for the core design, the evaluation of the thermal stresses on the structures and the decay heat removal systems. This analysis requires a 1D code able to simulate the whole reactor, including the core, the vessel, the piping and the components (turbine, compressors, heat exchangers). CATHARE is the reference code developed and extensively validated in collaboration between CEA, EDF, IRSN and FRAMATOME-ANP for the French Pressurized Water Reactors. CATHARE has the capabilities to model a Gas Cooled Reactor using standard 0D and 1D modules with some adaptations to treat the specificities of the GCR designs. In this paper, the different adaptations are presented and discussed. The direct coupling of a Gas Cooled Reactor with a closed gas-turbine cycle leads to a specific dynamic plant behaviour and a specific turbomachinery module has been developed. The thermal reactors' core consists of hexagonal graphite blocks with an annular-fueled region surrounded by reflectors and a special attention is paid on the thermal modeling of such a core leading to a quasi-2D thermal description. First designs of the VHTR are proposed and are based on an indirect cycle concept with a primary circuit, cooled by helium, and containing the core and a circulator. The core power is transmitted to the secondary circuit via an intermediate heat exchanger (IHX). The secondary circuit contains a turbine and a compressor coupled on a single shaft. It uses a mixture of helium and nitrogen, in order to benefit from both the favourable thermal properties of helium for the heat exchanger, and from existing experience of turbomachines using

  19. Studies of cooling tower components on the Mistral test bench

    International Nuclear Information System (INIS)

    Legrand, G.

    1992-07-01

    The conception of a humid air cooling tower with natural or forced draught, requires the knowledge of the thermal and aerodynamic exchange surfaces performances. Several points, among which the distribution nozzles and drift eliminators efficiencies, or the mechanical behavior of the components, should be considered. In order to be able to test this type of equipment and analyse its behavior, ELECTRICITE DE FRANCE set up in 1987 of a large dimensions test bench: MISTRAL. The investigations performed over the 3000 working hours of MISTRAL concern mainly the optimization of the counterflow and crossflow exchange surfaces proposed by the industrial cooling tower equipment suppliers. The quality of the experimental results is assured by the implementation of an extensive instrumentation on the air and water circuits, and by a severe control of the tests conditions

  20. Use of bromine as biocide in cooling waters (Preprint No. CA-19)

    Energy Technology Data Exchange (ETDEWEB)

    Sriraman, A K [Bhabha Atomic Research Centre, Bombay (India). Water Chemistry Div.

    1989-04-01

    In all fresh water circuits, the slime forming bacteria develop an insulating layer on the condenser surfaces. If these bacteria are not controlled, they induce bacterial promoted corrosion of the materials in contact with cooling water. Chlorination is effective against slime forming bacteria, fungi and algae. The algistatic nature of the chlorine is partly compensated by the use of other non-oxidisable biocides. Amongst the various alternative biocides such as bromine, methyl bis-isocyanate, sodium pentachlorophenate etc, bromine is the most simple biocide, which is being increasingly used in cooling water systems. In this context, the chemistry of bromination and its bactericidal properties is examined along with those of chlorination. (author). 7 refs., 3 tabs., 2 figs.

  1. The use of hybrid dry cooling towers/condensors; Einsatz von hybriden Trockenkuehltuermen/Verfluessigern

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, W. [Jaeggi/Guentner AG, Feldmeilen (Switzerland). Niederlassung Ostschweiz

    1998-03-01

    The hybride dry cooling tower/condenser has a closed circuit and an air side heat transfer surface which can be wetted. It is used for recooling of a liquide fluid (Water/Glycole) or for condensation of refrigerant by outdoor air and by evaporation of water from a secondary loop. This cooling tower concept has higher first costs, but considerably lower annual costs compared with similar cooling systems. The economy can be shown by a calculated example. (orig.) [Deutsch] Der hybride Trockenkuehlturm/Verfluessiger hat einen geschlossenen Kreislauf und eine wasserbenetzbare, luftseitige Waermeuebertragungsflaeche. Er dient der Rueckkuehlung eines fluessigen Mediums (Wasser/Glykol) oder der Verfluessigung von Kaeltemitteln mittels Umgebungsluft und durch Verdunstung von Wasser aus einem Sekundaerkreislauf. Dieser Kuehlturm hat hoehere Investitionskosten, aber wesentlich tiefere Jahreskosten als aehnliche Kuehlsysteme. Die Wirtschaftlichkeit wird anhand eines gerechneten Beispiels nachgewiesen. (orig.)

  2. Ultra-low power integrated circuit design circuits, systems, and applications

    CERN Document Server

    Li, Dongmei; Wang, Zhihua

    2014-01-01

    This book describes the design of CMOS circuits for ultra-low power consumption including analog, radio frequency (RF), and digital signal processing circuits (DSP). The book addresses issues from circuit and system design to production design, and applies the ultra-low power circuits described to systems for digital hearing aids and capsule endoscope devices. Provides a valuable introduction to ultra-low power circuit design, aimed at practicing design engineers; Describes all key building blocks of ultra-low power circuits, from a systems perspective; Applies circuits and systems described to real product examples such as hearing aids and capsule endoscopes.

  3. Development of an Integrated Cooling System Controller for Hybrid Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Chong Wang

    2017-01-01

    Full Text Available A hybrid electrical bus employs both a turbo diesel engine and an electric motor to drive the vehicle in different speed-torque scenarios. The cooling system for such a vehicle is particularly power costing because it needs to dissipate heat from not only the engine, but also the intercooler and the motor. An electronic control unit (ECU has been designed with a single chip computer, temperature sensors, DC motor drive circuit, and optimized control algorithm to manage the speeds of several fans for efficient cooling using a nonlinear fan speed adjustment strategy. Experiments suggested that the continuous operating performance of the ECU is robust and capable of saving 15% of the total electricity comparing with ordinary fan speed control method.

  4. Electronic circuit encyclopedia 2

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sun Ho

    1992-10-15

    This book is composed of 15 chapters, which are amplification of weak signal and measurement circuit audio control and power amplification circuit, data transmission and wireless system, forwarding and isolation, signal converting circuit, counter and comparator, discriminator circuit, oscillation circuit and synthesizer, digital and circuit on computer image processing circuit, sensor drive circuit temperature sensor circuit, magnetic control and application circuit, motor driver circuit, measuring instrument and check tool and power control and stability circuit.

  5. Electronic circuit encyclopedia 2

    International Nuclear Information System (INIS)

    Park, Sun Ho

    1992-10-01

    This book is composed of 15 chapters, which are amplification of weak signal and measurement circuit audio control and power amplification circuit, data transmission and wireless system, forwarding and isolation, signal converting circuit, counter and comparator, discriminator circuit, oscillation circuit and synthesizer, digital and circuit on computer image processing circuit, sensor drive circuit temperature sensor circuit, magnetic control and application circuit, motor driver circuit, measuring instrument and check tool and power control and stability circuit.

  6. Silicate geothermometry as an indicator of water-rock interaction processes in the serpentinized mafic-ultramafic intrusion of Ylivieska

    International Nuclear Information System (INIS)

    Ruskeeniemi, T.; Blomqvist, R.; Vuorela, P.; Frape, S.K.; Blyth, A.

    1996-01-01

    The aim of the study was to use oxygen and hydrogen isotopes to examine the origin of different generations of serpentine. Of special interest was the study of low-temperature generations that may be correlated with the present meteoric waters. The research was commenced with drill core logging in order to obtain insight into the fracture minerals and their distribution in a mafic-ultramafic intrusion. (39 refs., 17 figs., 5 tabs.)

  7. Fluid and element transfer at the slab-mantle interface: insights from the serpentinized Livingstone Fault, New Zealand

    Science.gov (United States)

    Smith, S. A. F.; Scott, J.; Tarling, M.; Tulley, C. J.; le Roux, P. J.

    2017-12-01

    At the slab-mantle interface in subduction zones, hydrous fluids released by dehydration reactions are fluxed upwards into the fore-arc mantle corner. The extent to which these fluids can move across the plate interface shear zone has significant implications for understanding the composition of the mantle wedge and the origin of episodic tremor and slow slip. The >1000 km long Livingstone Fault in New Zealand provides a superbly exposed analogue (both in terms of scale and the rock types involved) for the serpentinite shear zone likely to be present along the slab-mantle interface. The Livingstone Fault is a sheared serpentinite mélange up to several hundreds of meters wide that separates greenschist-facies quartzofeldspathic metasediments (e.g. analogue for slab sediments) from variably-serpentinized harzburgitic peridotite (e.g. analogue for mantle wedge). To track element mobility and paleo-fluid flow across the shear zone, Sr and Nd isotopes were measured in five transects across the metasediments, mélange and serpentinized peridotites. Results show that the mélange and serpentinized peridotites (originally with Sr and Nd similar to Permian MORB) were progressively overprinted with the isotopic composition of the metasediments at distances of up to c. 400 m from the mélange-metasediment contact. Mass balance calculations require that many elements were mobile across the mélange shear zone, but permeability modeling indicates that diffusive transfer of such elements is unrealistically slow. Instead, it appears that fluid and element percolation in to and across the mélange was aided by episodic over-pressuring and fracturing, as indicated by the widespread presence of tremolite-bearing breccias and veins that mutually cross-cut the serpentinite mélange fabrics. Overall, the field and isotopic results indicate that fluid and element redistribution within major serpentinite-bearing shear zones is strongly aided by fracturing and brecciation that are

  8. Solid-state circuits

    CERN Document Server

    Pridham, G J

    2013-01-01

    Solid-State Circuits provides an introduction to the theory and practice underlying solid-state circuits, laying particular emphasis on field effect transistors and integrated circuits. Topics range from construction and characteristics of semiconductor devices to rectification and power supplies, low-frequency amplifiers, sine- and square-wave oscillators, and high-frequency effects and circuits. Black-box equivalent circuits of bipolar transistors, physical equivalent circuits of bipolar transistors, and equivalent circuits of field effect transistors are also covered. This volume is divided

  9. Approaching the Processes in the Generator Circuit Breaker at Disconnection through Sustainability Concepts

    Directory of Open Access Journals (Sweden)

    Carmen A. Bulucea

    2013-03-01

    Full Text Available Nowadays, the electric connection circuits of power plants (based on fossil fuels as well as renewable sources entail generator circuit-breakers (GCBs at the generator terminals, since the presence of that electric equipment offers many advantages related to the sustainability of a power plant. In an alternating current (a.c. circuit the interruption of a short circuit is performed by the circuit-breaker at the natural passing through zero of the short-circuit current. During the current interruption, an electric arc is generated between the opened contacts of the circuit-breaker. This arc must be cooled and extinguished in a controlled way. Since the synchronous generator stator can flow via highly asymmetrical short-circuit currents, the phenomena which occur in the case of short-circuit currents interruption determine the main stresses of the generator circuit-breaker; the current interruption requirements of a GCB are significantly higher than for the distribution network circuit breakers. For shedding light on the proper moment when the generator circuit-breaker must operate, using the space phasor of the short-circuit currents, the time expression to the first zero passing of the short-circuit current is determined. Here, the manner is investigated in which various factors influence the delay of the zero passing of the short-circuit current. It is shown that the delay time is influenced by the synchronous machine parameters and by the load conditions which precede the short-circuit. Numerical simulations were conducted of the asymmetrical currents in the case of the sudden three-phase short circuit at the terminals of synchronous generators. Further in this study it is emphasized that although the phenomena produced in the electric arc at the terminals of the circuit-breaker are complicated and not completely explained, the concept of exergy is useful in understanding the physical phenomena. The article points out that just after the short-circuit

  10. Pressure drop and flow distribution characteristics of single and parallel serpentine flow fields for polymer electrolyte membrane fuel cells

    International Nuclear Information System (INIS)

    Baek, Seung Man; Kim, Charn Jung; Jeon, Dong Hyup; Nam, Jin Hyun

    2012-01-01

    This study numerically investigates pressure drop and flow distribution characteristics of serpentine flow fields (SFFs) that are designed for polymer electrolyte membrane fuel cells, which consider the Poiseuille flow with secondary pressure drop in the gas channel (GC) and the Darcy flow in the porous gas diffusion layer (GDL). The numerical results for a conventional SFF agreed well with those obtained via computational fluid dynamics simulations, thus proving the validity of the present flow network model. This model is employed to characterize various single and parallel SFFs, including multi-pass serpentine flow fields (MPSFFs). Findings reveal that under rib convection (convective flow through GDL under an interconnector rib) is an important transport process for conventional SFFs, with its intensity being significantly enhanced as GDL permeability increases. The results also indicate that under rib convection can be significantly improved by employing MPSFFs as the reactant flow field, because of the closely interlaced structure of GC regions that have different path lengths from the inlet. However, reactant flow rate through GCs proportionally decreases as under rib convection intensity increases, suggesting that proper optimization is required between the flow velocity in GCs and the under rib convection intensity in GDLs

  11. Early Mars serpentinization-derived CH4 reservoirs, H2 induced warming and paleopressure evolution

    Science.gov (United States)

    Lasue, J.; Chassefiere, E.; Langlais, B.; Quesnel, Y.

    2016-12-01

    CH4 has been observed on Mars both by remote sensing and in situ during the past 15 years. Early Mars serpentinization is one possible abiotic mechanism that could not only produce methane, but also explain the observed Martian remanent magnetic field. Assuming a cold early Mars, a cryosphere could trap such CH4 as clathrates in stable form at depth. We recently estimated the maximum storage capacity of such clathrate layer to be about 2x1019 to 2x1020 moles of methane. Such reservoirs may be stable or unstable, depending on many factors that are poorly constrained: major and sudden geological events such as the Tharsis bulge formation, the Hellas impact or the martian polar wander, could have destabilized the clathrates early in the history of the planet and released large quantities of gas in the atmosphere. Here we estimate the associated amounts of serpentinization-derived CH4 stored in the cryosphere that have been released to the atmosphere at the end of the Noachian and the beginning of the Hesperian. Due to rapid clathrate dissociation and photochemical conversion of CH4 to H2, these episodes of massive CH4 release may have resulted in transient H2-rich atmospheres, at typical levels of 10-20% in a background 1-2 bar CO2 atmosphere. We propose that the early Mars cryosphere had a sufficient CH4 storage capacity to have maintained H2-rich transient atmospheres during a total time period up to several Myr or tens of Myr, having potentially contributed - by collision-induced heating effect of atmospheric H2 - to the formation of valley networks during the late Noachian and early Hesperian.

  12. Collective of mechatronics circuit

    International Nuclear Information System (INIS)

    1987-02-01

    This book is composed of three parts, which deals with mechatronics system about sensor, circuit and motor. The contents of the first part are photo sensor of collector for output, locating detection circuit with photo interrupts, photo sensor circuit with CdS cell and lamp, interface circuit with logic and LED and temperature sensor circuit. The second part deals with oscillation circuit with crystal, C-R oscillation circuit, F-V converter, timer circuit, stability power circuit, DC amp and DC-DC converter. The last part is comprised of bridge server circuit, deformation bridge server, controlling circuit of DC motor, controlling circuit with IC for PLL and driver circuit of stepping motor and driver circuit of Brushless.

  13. Collective of mechatronics circuit

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1987-02-15

    This book is composed of three parts, which deals with mechatronics system about sensor, circuit and motor. The contents of the first part are photo sensor of collector for output, locating detection circuit with photo interrupts, photo sensor circuit with CdS cell and lamp, interface circuit with logic and LED and temperature sensor circuit. The second part deals with oscillation circuit with crystal, C-R oscillation circuit, F-V converter, timer circuit, stability power circuit, DC amp and DC-DC converter. The last part is comprised of bridge server circuit, deformation bridge server, controlling circuit of DC motor, controlling circuit with IC for PLL and driver circuit of stepping motor and driver circuit of Brushless.

  14. Modelling the transient analysis of flat miniature heat pipes in printed circuit boards using a control volume approacht

    NARCIS (Netherlands)

    Wits, W.W.; Kok, J.B.W.; van Steenhoven, A.A.; van der Meer, T.H.; Stoffels, G.G.M.

    2008-01-01

    The heat pipe is a two-phase cooling solution, offering very high thermal coefficients, for heat transport. Therefore, it is increasingly used in the design of electronic products. Flat miniature heat pipes are able to effectively remove heat from several hot spots on a Printed Circuit Board (PCB).

  15. Electrochemistry of Water-Cooled Nuclear Reactors

    International Nuclear Information System (INIS)

    Dgiby Macdonald; Mirna Urquidi-Macdonald; John Mahaffy; Amit Jain Han Sang Kim; Vishisht Gupta; Jonathan Pitt

    2006-01-01

    This project developed a comprehensive mathematical and simulation model for calculating thermal hydraulic, electrochemical, and corrosion parameters, viz. temperature, fluid flow velocity, pH, corrosion potential, hydrogen injection, oxygen contamination, stress corrosion cracking, crack growth rate, and other important quantities in the coolant circuits of water-cooled nuclear power plants, including both Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs). The model is being used to assess the three major operational problems in Pressurized Water Reactors (PWR), which include mass transport, activity transport, and the axial offset anomaly, and provide a powerful tool for predicting the accumulation of SCC damage in BWR primary coolant circuits as a function of operating history. Another achievement of the project is the development of a simulation tool to serve both as a training tool for plant operators and as an engineering test-bed to evaluate new equipment and operating strategies (normal operation, cold shut down and others). The development and implementation of the model allows us to estimate the activity transport or ''radiation fields'' around the primary loop and the vessel, as a function of the operating parameters and the water chemistry

  16. A novel readout integrated circuit for ferroelectric FPA detector

    Science.gov (United States)

    Bai, Piji; Li, Lihua; Ji, Yulong; Zhang, Jia; Li, Min; Liang, Yan; Hu, Yanbo; Li, Songying

    2017-11-01

    Uncooled infrared detectors haves some advantages such as low cost light weight low power consumption, and superior reliability, compared with cryogenically cooled ones Ferroelectric uncooled focal plane array(FPA) are being developed for its AC response and its high reliability As a key part of the ferroelectric assembly the ROIC determines the performance of the assembly. A top-down design model for uncooled ferroelectric readout integrated circuit(ROIC) has been developed. Based on the optical thermal and electrical properties of the ferroelectric detector the RTIA readout integrated circuit is designed. The noise bandwidth of RTIA readout circuit has been developed and analyzed. A novel high gain amplifier, a high pass filter and a low pass filter circuits are designed on the ROIC. In order to improve the ferroelectric FPA package performance and decrease of package cost a temperature sensor is designed on the ROIC chip At last the novel RTIA ROIC is implemented on 0.6μm 2P3M CMOS silicon techniques. According to the experimental chip test results the temporal root mean square(RMS)noise voltage is about 1.4mV the sensitivity of the on chip temperature sensor is 0.6 mV/K from -40°C to 60°C the linearity performance of the ROIC chip is better than 99% Based on the 320×240 RTIA ROIC, a 320×240 infrared ferroelectric FPA is fabricated and tested. Test results shows that the 320×240 RTIA ROIC meets the demand of infrared ferroelectric FPA.

  17. Experimental Device for Learning of Logical Circuit Design using Integrated Circuits

    OpenAIRE

    石橋, 孝昭

    2012-01-01

    This paper presents an experimental device for learning of logical circuit design using integrated circuits and breadboards. The experimental device can be made at a low cost and can be used for many subjects such as logical circuits, computer engineering, basic electricity, electrical circuits and electronic circuits. The proposed device is effective to learn the logical circuits than the usual lecture.

  18. Turbine airfoil cooling system with cooling systems using high and low pressure cooling fluids

    Science.gov (United States)

    Marsh, Jan H.; Messmann, Stephen John; Scribner, Carmen Andrew

    2017-10-25

    A turbine airfoil cooling system including a low pressure cooling system and a high pressure cooling system for a turbine airfoil of a gas turbine engine is disclosed. In at least one embodiment, the low pressure cooling system may be an ambient air cooling system, and the high pressure cooling system may be a compressor bleed air cooling system. In at least one embodiment, the compressor bleed air cooling system in communication with a high pressure subsystem that may be a snubber cooling system positioned within a snubber. A delivery system including a movable air supply tube may be used to separate the low and high pressure cooling subsystems. The delivery system may enable high pressure cooling air to be passed to the snubber cooling system separate from low pressure cooling fluid supplied by the low pressure cooling system to other portions of the turbine airfoil cooling system.

  19. Mechanics of ultra-stretchable self-similar serpentine interconnects

    International Nuclear Information System (INIS)

    Zhang, Yihui; Fu, Haoran; Su, Yewang; Xu, Sheng

    2013-01-01

    Graphical abstract: We developed analytical models of flexibility and elastic-stretchability for self-similar interconnect. The analytic solutions agree very well with the finite element analyses, both demonstrating that the elastic-stretchability more than doubles when the order of self-similar structure increases by one. Design optimization yields 90% and 50% elastic stretchability for systems with surface filling ratios of 50% and 70% of active devices, respectively. The analytic models are useful for the development of stretchable electronics that simultaneously demand large coverage of active devices, such as stretchable photovoltaics and electronic eye-ball cameras. -- Abstract: Electrical interconnects that adopt self-similar, serpentine layouts offer exceptional levels of stretchability in systems that consist of collections of small, non-stretchable active devices in the so-called island–bridge design. This paper develops analytical models of flexibility and elastic stretchability for such structures, and establishes recursive formulae at different orders of self-similarity. The analytic solutions agree well with finite element analysis, with both demonstrating that the elastic stretchability more than doubles when the order of the self-similar structure increases by one. Design optimization yields 90% and 50% elastic stretchability for systems with surface filling ratios of 50% and 70% of active devices, respectively

  20. Characterization of serpentine. A potential nuclear shielding material

    International Nuclear Information System (INIS)

    Sengupta, A.; Rajeswari, B.; Kadam, R.M.; Kshirsagar, R.J.

    2012-01-01

    The use of serpentine as a potential nuclear shielding material necessitates a chemical quality control of the samples before its use in reactors. With this in view, characterization of these mineral samples was carried out using inductively coupled plasma atomic emission spectrometry (ICP-AES) and Instrumental neutron activation analysis (INAA) methods. The analytical results obtained by both ICP-AES and NAA techniques were found to be comparable. Na, Cr, Co, Zn, and Cu were found to be present in all samples of Indian origin while Ga, Ag, Ni, and Cd were found to below the limits of detection. A comparison on the detection limits of elements of interest was also carried out by both the analytical techniques and found to be in good agreement. An infrared spectroscopic investigation was also carried out on all the mineral samples. Bands at 3,689 and 3,648 cm -1 were attributed to inner and outer hydroxyl stretching of Mg-OH, respectively. The weak and broad band centered around 3,416 cm -1 was assigned due to the stretching vibrations of the adsorbed water molecules while three bands at 1076, 1022 and 968 cm -1 were prescribed to the vibrations of the SiO 4 tetrahedra. (author)

  1. Technology assessment of dew point cooling; Beoordeling technologie dauwpuntskoeling

    Energy Technology Data Exchange (ETDEWEB)

    Uges, P.G.H. [Koudetechnisch Centrum, Nijmegen (Netherlands); Reinder, T.M.

    2003-03-01

    Results of measurements on an indirect adiabatic dew point cooling system are presented and discussed. The cooling system has been developed by OxyCom (formerly ComfortAir), Raalte, Netherlands. [Dutch] De techniek van dauwpuntskoeling is gebaseerd op bet principe van indirecte verdamping van water in een secundair circuit, waarbij geen extra vocht aan de te koelen luchtstroom wordt toegevoegd en waarmee luchttemperaturen worden bereikt die net boven het dauwpunt liggen en dus onder de natteboltemperatuur. Dauwpuntskoeling is een technische ontwikkeling met goede toekomstverwachtingen. Voorzover bekend zijn er tot op heden geen meetgegevens gepubliceerd met een dergelijke indirect werkende koeler. Dit artikel geeft de meetresultaten weer van een door OxyCorn in samenwerking met TNO-MEP uitgevoerd meetprogramma. Dit artikel is gebaseerd op de TNO-MEP rapportage met als auteurs N.R. Bootsveld en J. Afink en heeft eerder in het blad Koude en Luchtbehandeling, januari 2003, gestaan.

  2. Experimental and numerical study of flow deflection effects on electronic air-cooling

    International Nuclear Information System (INIS)

    Arfaoui, Ahlem; Ben Maad, Rejeb; Hammami, Mahmoud; Rebay, Mourad; Padet, Jacques

    2009-01-01

    This work present a numerical and experimental investigation of the influence of transversal flow deflector on the cooling of a heated block mounted on a flat plate. The deflector is inclined and therefore it guides the air flow to the upper surface of the block. This situation is simulating the air-cooling of a rectangular integrated circuit or a current converter mounted on an electronic board. The electronic component are assumed dissipating a low or medium heat flux (with a density lower than 5000 W/m 2 ), as such the forced convection air cooling without fan or heat sink is still sufficient. The study details the effects of the angle of deflector on the temperature and the heat transfer coefficient along the surface of the block and around it. The results of the numerical simulations and the InfraRed camera measurements show that the deviation caused by deflector may significantly enhance the heat transfer on the top face of block

  3. Color Coding of Circuit Quantities in Introductory Circuit Analysis Instruction

    Science.gov (United States)

    Reisslein, Jana; Johnson, Amy M.; Reisslein, Martin

    2015-01-01

    Learning the analysis of electrical circuits represented by circuit diagrams is often challenging for novice students. An open research question in electrical circuit analysis instruction is whether color coding of the mathematical symbols (variables) that denote electrical quantities can improve circuit analysis learning. The present study…

  4. Cooling for SC devices of test cryomodule for ADS Injector II at IMP

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L.; Wang, S. Y.; Sun, S.; Wang, S. H.; Liu, Y. Y. [Shanghai Institute of Applied Physics, CAS, Shanghai 201204 (China); Guo, X. L. [JiangSu University, Zhenjiang 212013 (China)

    2014-01-29

    The superconducting half-wave resonance cavities connected in series with superconducting solenoids will be applied to the Injector II of the Accelerator Driven Sub-critical System (ADS) to be built at the Modern Physics Institute, China. A test system has been developed for the purpose of performance test of the HWR cavities as well as validating the relevant technique for cooling the cavity and the solenoids together. It mainly comprises a cryogenic valve box (TVB), a test cryomodule (TCM1) and transfer lines. The TCM1 includes one HWR cavity, two superconducting solenoids, one cold BPM and their cooling system. The design of the TCM1 cryostat was carried out by the Shanghai Institute of Applied Physics (SINAP), CAS. Both the cavity and the solenoids will work at 4.4 K by bath cooling. The fast cooling down for the cavity from around 100 K to 120 K is required to avoid degrading of the cavity performance. After cool down and before energization, the solenoids should be warmed up to above 10 K and re-cooled down for the purpose of degaussing. The TCM1 can not only be cooled by using the dewar-filling system, but also operated by the refrigerator system. For the purpose of reducing the heat loads to the cold mass at 4 K from room temperature, thermal radiation shields cooled by liquid nitrogen flowing in tubing were employed. This paper presents the design details of cooling circuits and thermal shields of the TCM1 as well as related calculations and analyses.

  5. Design of an improved RCD buffer circuit for full bridge circuit

    Science.gov (United States)

    Yang, Wenyan; Wei, Xueye; Du, Yongbo; Hu, Liang; Zhang, Liwei; Zhang, Ou

    2017-05-01

    In the full bridge inverter circuit, when the switch tube suddenly opened or closed, the inductor current changes rapidly. Due to the existence of parasitic inductance of the main circuit. Therefore, the surge voltage between drain and source of the switch tube can be generated, which will have an impact on the switch and the output voltage. In order to ab sorb the surge voltage. An improve RCD buffer circuit is proposed in the paper. The peak energy will be absorbed through the buffer capacitor of the circuit. The part energy feedback to the power supply, another part release through the resistor in the form of heat, and the circuit can absorb the voltage spikes. This paper analyzes the process of the improved RCD snubber circuit, According to the specific parameters of the main circuit, a reasonable formula for calculating the resistance capacitance is given. A simulation model will be modulated in Multisim, which compared the waveform of tube voltage and the output waveform of the circuit without snubber circuit with the improved RCD snubber circuit. By comparing and analyzing, it is proved that the improved buffer circuit can absorb surge voltage. Finally, experiments are demonstrated to validate that the correctness of the RC formula and the improved RCD snubber circuit.

  6. Deep long-period earthquakes west of the volcanic arc in Oregon: evidence of serpentine dehydration in the fore-arc mantle wedge

    Science.gov (United States)

    Vidale, John E.; Schmidt, David A.; Malone, Stephen D.; Hotovec-Ellis, Alicia J.; Moran, Seth C.; Creager, Kenneth C.; Houston, Heidi

    2014-01-01

    Here we report on deep long-period earthquakes (DLPs) newly observed in four places in western Oregon. The DLPs are noteworthy for their location within the subduction fore arc: 40–80 km west of the volcanic arc, well above the slab, and near the Moho. These “offset DLPs” occur near the top of the inferred stagnant mantle wedge, which is likely to be serpentinized and cold. The lack of fore-arc DLPs elsewhere along the arc suggests that localized heating may be dehydrating the serpentinized mantle wedge at these latitudes and causing DLPs by dehydration embrittlement. Higher heat flow in this region could be introduced by anomalously hot mantle, associated with the western migration of volcanism across the High Lava Plains of eastern Oregon, entrained in the corner flow proximal to the mantle wedge. Alternatively, fluids rising from the subducting slab through the mantle wedge may be the source of offset DLPs. As far as we know, these are among the first DLPs to be observed in the fore arc of a subduction-zone system.

  7. Analog circuit design designing dynamic circuit response

    CERN Document Server

    Feucht, Dennis

    2010-01-01

    This second volume, Designing Dynamic Circuit Response builds upon the first volume Designing Amplifier Circuits by extending coverage to include reactances and their time- and frequency-related behavioral consequences.

  8. Corrosion products in the primary circuits of PWRs

    International Nuclear Information System (INIS)

    Darras, R.

    1983-01-01

    The characteristics of PWR primary circuits are recalled, particularly the chemical specifications of the medium and the various materials used (austenitic steel, nickel alloys, cobalt-based alloys and zirconium alloys). The behaviour of these materials as regards general corrosion in nominal and transient conditions is then outlined briefly, special emphasis being laid on the effect of the determining parameters on the quantity of corrosion products formed. The release of the latter into the primary coolant is caused by two main processes: solubilization and erosion. Particular attention was given therefore to the laws governing the solubility of the oxides involved, especially as a function of temperature and pH. Erosion, or release in the form of solid particles, is relatively severe during transient events. As these corrosion products are then carried through all circuits, they cause deposits to form in favourable places on the walls as a result either of precipitation of soluble species or of sedimentation followed by consolidation of suspended particles. The presence of corrosion products in the primary circuits creates a particular impact since they become radioactive as they pass through the core and especially when they remain in it in the form of deposits; as a result, the products are capable of contaminating the entire system. Finally, although long-term reliability is obviously an essential condition for materials developed, attention must also be given to problems associated with a build-up of corrosion products in the cooling circuits and efforts made to minimize them. To that end, a number of precautions are recommended, and various remedies can be applied: selecting materials which are not readily activated, keeping structures clean, purifying fluids properly, restricting solubilization and precipitation, and perhaps, periodic decontamination. (author)

  9. Low-Noise Active Decoupling Circuit and its Application to 13C Cryogenic RF Coils at 3T

    DEFF Research Database (Denmark)

    Sanchez, Juan Diego; Søvsø Szocska Hansen, Esben; Laustsen, Christoffer

    2017-01-01

    We analyze the loss contributions in a small, 50-mm-diameter receive-only coil for carbon-13 (13C) magnetic resonance imaging at 3 T for 3 different circuits, which, including active decoupling, are compared in terms of their Q-factors and signal-to-noise ratio (SNR). The results show that a circ......We analyze the loss contributions in a small, 50-mm-diameter receive-only coil for carbon-13 (13C) magnetic resonance imaging at 3 T for 3 different circuits, which, including active decoupling, are compared in terms of their Q-factors and signal-to-noise ratio (SNR). The results show...... that a circuit using unsegmented tuning and split matching capacitors can provide 20% SNR enhancement at room temperature compared with that using more traditional designs. The performance of the proposed circuit was also measured when cryogenically cooled to 105 K, and an additional 1.6-fold SNR enhancement...... was achieved on a phantom. The enhanced circuit performance is based on the low capacitance needed to match to 50 when coil losses are low, which significantly reduces the proportion of the current flowing through the matching network and therefore minimizes this loss contribution. This effect makes...

  10. Integrated thermal control and system assessment in plug-chip spray cooling enclosure

    International Nuclear Information System (INIS)

    Zhang, Wei-Wei; Cheng, Wen-Long; Shao, Shi-Dong; Jiang, Li-Jia; Hong, Da-Liang

    2016-01-01

    Highlights: • A novel multi-heat source plug-chip spray cooling enclosure was designed. • Enhanced surfaces with different geometric were analyzed in integrated enclosure. • Overall thermal control with adjustable parameters in enclosure was studied. • Temperature disequilibrium of multi-heat source in enclosure was tested. • A comprehensive assessment system used to evaluate the practicality was proposed. - Abstract: Practical and integrated spray cooling system is urgently needed for the cooling of high-performance electronic chips due to the growth requirements of thermal management in workstation. The integration of multi heat sources and the management of integral system are particularly lacking. In order to fill the vacancies in the study of plug-chip spray cooling, an integrated cooling enclosure was designed in this paper. Multi heat sources were placed in sealed space and the heat was removed by spray. The printed circuit board plug-ins and radio frequency resistors were used as analog motherboards and chips, respectively. The enhanced surfaces with four different geometries and the plain surface were studied under the conditions of different inclination angles. The results were compared and the maximum critical heat flux (CHF) was obtained. Moreover, with the intention of the overall management of multi-heat source in integrated enclosure, the effect of the flow rate and the temperature disequilibrium, and the pulse heating in the process of transient cooling were also analyzed. In addition, a comprehensive assessment system, used to evaluate the practicality of spray cooling experimental devices, was proposed and the performance of enclosure was evaluated.

  11. Radiochemical analysis of the first plateout probe from the Fort St. Vrain high-temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Burnette, R.D.

    1982-06-01

    This report presents the analysis of radioactive elements on the first plateout probe from the Fort St. Vrain high-temperature gas-cooled reactor. The plateout probe is a device which samples the primary coolant for condensible fission products. Circuit inventories of individual radionuclides are estimated from the probe analysis. The analysis shows that the radioactive contamination in the primary circuit is remarkable low, with activation product concentrations much greater than that of fission products. The analysis demonstrates that the concentrations of the key fission products I-131 and Sr-90 are far below the limits allowed by the technical specification

  12. Cooling system for the IFMIF-EVEDA radiofrequency system; Sistema de refrigeracion del sistema de radiofrecuencia del IFMIF-EVEDA

    Energy Technology Data Exchange (ETDEWEB)

    Perez Pichel, G. D.

    2012-07-01

    The IFMIF-EVEDA project consists on an accelerator prototype that will be installed at Rokkasho (Japan). Through CIEMAT, that is responsible of the development of many systems and components. Empresarios Agrupados get the responsibility of the detailed design of the cooling system for the radiofrequency system (RF system) that must feed the accelerator. the RF water cooling systems is the water primary circuit that provides the required water flow (with a certain temperature, pressure and water quality) and also dissipates the necessary thermal power of all the radiofrequency system equipment. (Author) 4 refs.

  13. Sideband cooling of micromechanical motion to the quantum ground state.

    Science.gov (United States)

    Teufel, J D; Donner, T; Li, Dale; Harlow, J W; Allman, M S; Cicak, K; Sirois, A J; Whittaker, J D; Lehnert, K W; Simmonds, R W

    2011-07-06

    The advent of laser cooling techniques revolutionized the study of many atomic-scale systems, fuelling progress towards quantum computing with trapped ions and generating new states of matter with Bose-Einstein condensates. Analogous cooling techniques can provide a general and flexible method of preparing macroscopic objects in their motional ground state. Cavity optomechanical or electromechanical systems achieve sideband cooling through the strong interaction between light and motion. However, entering the quantum regime--in which a system has less than a single quantum of motion--has been difficult because sideband cooling has not sufficiently overwhelmed the coupling of low-frequency mechanical systems to their hot environments. Here we demonstrate sideband cooling of an approximately 10-MHz micromechanical oscillator to the quantum ground state. This achievement required a large electromechanical interaction, which was obtained by embedding a micromechanical membrane into a superconducting microwave resonant circuit. To verify the cooling of the membrane motion to a phonon occupation of 0.34 ± 0.05 phonons, we perform a near-Heisenberg-limited position measurement within (5.1 ± 0.4)h/2π, where h is Planck's constant. Furthermore, our device exhibits strong coupling, allowing coherent exchange of microwave photons and mechanical phonons. Simultaneously achieving strong coupling, ground state preparation and efficient measurement sets the stage for rapid advances in the control and detection of non-classical states of motion, possibly even testing quantum theory itself in the unexplored region of larger size and mass. Because mechanical oscillators can couple to light of any frequency, they could also serve as a unique intermediary for transferring quantum information between microwave and optical domains.

  14. An example of R and D on safety assessment: study of a prolonged loss of cooling of halw (beyond design accident)

    International Nuclear Information System (INIS)

    Mercier, J.P.; Bonneval, F.; Martineau, D.; Gue, J.P.; Philippe, M.

    1991-01-01

    The consequences of a loss of cooling of storage tanks of fission products concentrated solutions were studied, for a variable period, in the context, of the safety analysis of the COGEMA spent fuel reprocessing plants of La Hague. As a result of fission products-induced heat emission, a prolonger loss of cooling could involve the progressive evaporation of solutions up to dryout and lead to the formation of radioactive aerosols and then of volatile species of ruthenium likely to be released in off gas circuits of the tanks. With the aim of determining the radioactivity fraction likely to be transferred throughout the loss of cooling out of the storage tanks, an extensive R and D programme was performed, including the main following stages: - experimental determination of the factor of radioactivity transfer through aerosols out of the tanks; - modelling, by means of a calculation code, of the aerosols transfer into the off gas circuits; - experimental study of the ruthenium behaviour with tests carried out in laboratory, by evaporation of samples representative of nitric solutions of fission products. The main conclusions can be summarized as follows (by assuming a heat power density of 10 watts per litre of solution and a storage system completely adiabatic): - the evaporation of solutions starts more than 5 hours after the total loss of cooling, the 10 -4 value being an over-estimated value of the factor of radioactivity transfer by aerosols out of the tanks; - transfer factor through the off gas circuits varies, according to the physical characteristics of aerosols, from 0 to 8.10 -2 ; - ruthenium volatilized only during the final stage of evaporation, shortly before dryout; the minimum time to reach dryness is about 90 hours

  15. Serpentinization and fluid-rock interaction in Jurassic mafic and ultramafic sea-floor: constraints from Ligurian ophiolite sequences

    Science.gov (United States)

    Vogel, Monica; Früh-Green, Gretchen L.; Boschi, Chiara; Schwarzenbach, Esther M.

    2014-05-01

    The Bracco-Levanto ophiolitic complex (Eastern Liguria) represents one of the largest and better-exposed ophiolitic successions in the Northern Apennines. It is considered to be a fragment of heterogeneous Jurassic lithosphere that records tectono-magmatic and alteration histories similar to those documented along the Mid-Atlantic Ridge, such as at the 15°20'N area and the Atlantis Massif at 30°N. Structural and petrological studies on these rocks provide constraints on metamorphic/deformation processes during formation and hydrothermal alteration of the Jurassic oceanic lithosphere. We present a petrological and geochemical study of deformation processes and fluid-rock interaction in the Bracco-Levanto ophiolitic complex and compare these to modern oceanic hydrothermal systems, such as the Lost City Hydrothermal Field hosted in ultramafic rocks on the Atlantis Massif. A focus is on investigating mass transfer and fluid flow paths during high and low temperature hydrothermal activity, and on processes leading to hydrothermal carbonate precipitation and the formation of ophicalcites, which are characteristic of the Bracco-Levanto sequences. Major element and mineral compositional data allow us to distinguish a multiphase history of alteration characterized by: (1) widespread SiO2 metasomatism during progressive serpentinization, and (2) multiple phases of veining and carbonate precipitation associated with circulation of seawater and high fluid-rock ratios in the shallow ultramafic-dominated portions of the Jurassic seafloor. We observe regional variations in MgO, SiO2 and Al2O3, suggesting Si-flux towards stratigraphically higher units. In general, the ophicalcites have higher Si, Al and Fe concentrations and lower Mg than the serpentinite basement rocks or serpentinites with minimal carbonate veins. Bulk rock trace element data and Sr isotope ratios indicate seawater reacting with rocks of more mafic composition, then channeled towards stratigraphically higher

  16. The Kolmården serpentine marble in Sweden, a building stone found at many levels in the society.

    Science.gov (United States)

    Wikström, Anders; Pereira, Dolores

    2013-04-01

    The Kolmården marble is a green serpentine marble of Svekofennian age (c. 1900 Ma). Serpentine is mainly secondary after diopside. The rock has been used as far back as in the 13th century. But it was mainly due to the start of the building of the Royal castles in Stockholm in the 17th century when the stone became more extensively used. The quarries were in operation until the 1970s and during the last years the production was so rationalized that one finds the stone in stairs, pavement and non structural ornaments within "common" houses all over the country. One can also find this stone in many exclusive places all over the world (e.g. the Paris Opera house, League of Nations building in Geneva, Leeds University Library, Uppsala University, Rockefeller Center, etc). The importance of this stone in international architecture, the good physical and mechanical behaviour observed in its emplacements and the possibilities for preservation of some of the quarries makes the Kolmården marble a good candidate as Global Stone Heritage Stone. The nomination will also trigger international publications on this natural stone to spread its knowledge among scientists and architects to be able to select this rock in case that some restoration on the mentioned important buildings is needed at some point.

  17. Superconducting quantum circuits theory and application

    Science.gov (United States)

    Deng, Xiuhao

    states. The model and toolbox are engineered with a superconducting quantum circuit where two superconducting resonators are coupled via the UQDP circuit. Using fourth order perturbation theory one can realize a complete set of quantum operations between these two photon modes. This helps open a new field to treat photon modes as qubits. Additional, a three-wave mixing scheme using phase qubits permits one to engineer the coupling Hamiltonian using a phase qubit as a tunable coupler. Along with Feynman's idea using quantum to simulate quantum, superconducting quantum simulators have been studied intensively recently. Taking the advantage of mesoscopic size of superconducting circuit and local tunability, we came out the idea to simulate quantum phase transition due to disorder. Our first paper was to propose a superconducting quantum simulator of Bose-Hubbard model to do site-wise manipulation and observe Mott-insulator to superfluid phase transition. The side-band cooling of an array of superconducting resonators is solved after the paper was published. In light of the developed technology in manipulating quantum information with superconducting circuit, one can couple other quantum oscillator system to superconducting resonators in order manipulation of its quantum states or parametric amplification of weak quantum signal. A theory that works for different coupling schemes has been studied in chapter 5. This will be a platform for further research.

  18. Prevent thermal runaway of lithium-ion batteries with minichannel cooling

    International Nuclear Information System (INIS)

    Xu, Jian; Lan, Chuanjin; Qiao, Yu; Ma, Yanbao

    2017-01-01

    Highlights: • A 3D model was developed to study nail penetration induced thermal runaway. • Effects of flow rate, thermal abuse reactions, and nail dimensions were examined. • Minichannel cooling at cell level cannot cease thermal runaway in a single cell. • Minichannel cooling can prevent thermal runaway propagation between cells. - Abstract: Thermal management on lithium-ion batteries is a crucial problem for the performance, lifetime, and safety of electric vehicles (EVs) and hybrid electric vehicles (HEVs). Fire and explosions can be triggered by thermal runaway if the temperature of the lithium-ion batteries is not maintained properly. This work describes a minichannel cooling system designed at the battery module level and the investigation on its efficacy on the mitigation of thermal runaway. Nail penetration was employed to simulate the internal short circuits, which in reality may be caused by vehicle collisions and/or manufacturing defects. Two integrated models were utilized to study thermal runaway: the conjugate heat transfer model and the reaction kinetics model. Numerical simulations were conducted to understand the thermal runaway process and the effects of flow rate, thermal abuse reactions, nail penetration depth, and nail diameter. It is concluded that minichannel cooling at cell level cannot cease thermal runaway in a single cell, but it can prevent battery fratricide due to thermal runaway propagation between cells.

  19. Channel geometric scales effect on performance and optimization for serpentine proton exchange membrane fuel cell (PEMFC)

    Science.gov (United States)

    Youcef, Kerkoub; Ahmed, Benzaoui; Ziari, Yasmina; Fadila, Haddad

    2017-02-01

    A three dimensional computational fluid dynamics model is proposed in this paper to investigate the effect of flow field design and dimensions of bipolar plates on performance of serpentine proton exchange membrane fuel cell (PEMFC). A complete fuel cell of 25 cm2 with 25 channels have been used. The aim of the work is to investigate the effect of flow channels and ribs scales on overall performance of PEM fuel cell. Therefore, geometric aspect ratio parameter defined as (width of flow channel/width of rib) is used. Influences of the ribs and openings current collector scales have been studied and analyzed in order to find the optimum ratio between them to enhance the production of courant density of PEM fuel cell. Six kind of serpentine designs have been used in this paper included different aspect ratio varying from 0.25 to 2.33 while the active surface area and number of channels are keeping constant. Aspect ratio 0.25 corresponding of (0.4 mm channel width/ 1.6mm ribs width), and Aspect ratio2.33 corresponding of (0.6 mm channel width/ 1.4mm ribs width. The results show that the best flow field designs (giving the maximum density of current) are which there dimensions of channels width is minimal and ribs width is maximal (Γ≈0.25). Also decreasing width of channels enhance the pressure drop inside the PEM fuel cell, this causes an increase of gazes velocity and enhance convection process, therefore more power generation.

  20. The Thermosiphon Cooling System of the ATLAS Experiment at the CERN Large Hadron Collider

    CERN Document Server

    Battistin, M; Bitadze, A; Bonneau, P; Botelho-Direito, J; Boyd, G; Corbaz, F; Crespo-Lopez, O; Da Riva, E; Degeorge, C; Deterre, C; DiGirolamo, B; Doubek, M; Favre, G; Godlewski, J; Hallewell, G; Katunin, S; Lefils, D; Lombard, D; McMahon, S; Nagai, K; Robinson, D; Rossi, C; Rozanov, A; Vacek, V; Zwalinski, L

    2015-01-01

    The silicon tracker of the ATLAS experiment at CERN Large Hadron Collider will operate around –15°C to minimize the effects of radiation damage. The present cooling system is based on a conventional evaporative circuit, removing around 60 kW of heat dissipated by the silicon sensors and their local electronics. The compressors in the present circuit have proved less reliable than originally hoped, and will be replaced with a thermosiphon. The working principle of the thermosiphon uses gravity to circulate the coolant without any mechanical components (compressors or pumps) in the primary coolant circuit. The fluorocarbon coolant will be condensed at a temperature and pressure lower than those in the on-detector evaporators, but at a higher altitude, taking advantage of the 92 m height difference between the underground experiment and the services located on the surface. An extensive campaign of tests, detailed in this paper, was performed using two small-scale thermosiphon systems. These tests confirmed th...

  1. Approximate method for calculating heat conditions in the magnetic circuits of transformers and betatrons

    International Nuclear Information System (INIS)

    Loginov, V.S.

    1986-01-01

    A technique for engineering design of two-dimensional stationary temperature field of rectangular cross section blending pile with inner heat release under nonsymmetrical cooling conditions is suggested. Area of its practical application is determined on the basis of experimental data known in literature. Different methods for calculating temperature distribution in betatron magnetic circuit are compared. Graph of maximum temperature calculation error on the basis of approximated expressions with respect to exact solution is given

  2. Discussion on amount of water ingress mass in steam generator heat-exchange tube rupture accident of high- temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Wang Yan; Zheng Yanhua; Shi Lei; Li Fu; Sun Ximing

    2009-01-01

    The steam generator heat-exchange tube rupture (SGTR) accident which will result in the water ingress to the primary circuit of reactor is an important and particular accident for high-temperature gas-cooled reactor (HTGR). The analysis of the water ingress accident is significant for verifying the inherent safety characteristics of HTGR. The amount of water ingress mass is one of the decisive factors for the seriousness of the accident consequence. The 250 MW Pebble-bed Modular High-Temperature Gas-cooled Reactor (HTR-PM) designed by Institute of Nuclear and New Energy Technology of Tsinghua University was selected as an example of analysis. The analysis results show that the amount of water ingress mass is not only affected directly with the broken position and the broken area of the tubes, but also related with the diameter of draining piping and restrictor, draining control valve, action setting of emptier system. With reasonable parameters chosen, the water in steam generator could be drained effectively, so it will prevent the primary circuit of reactor from water ingress in large quantity and reduce the radioactive isotopes ingress to the secondary circuit. (authors)

  3. Development and validation of the shutdown cooling system CATHENA model for Gentilly-2

    International Nuclear Information System (INIS)

    Lecuyer, H.; Hasnaoui, C.; Sabourin, G.; Chapados, S.

    2008-01-01

    A CATHENA representation of the Gentilly-2 Shutdown Cooling system has been developed for Hydro-Quebec. The model includes the SDCS circuit piping, valves, pumps and heat exchangers. The model is integrated in the G2 CATHENA overall plant model and coupled with the plant control software simulator TROLG2 to allow the simulation of various plant operational modes using the SDCS. Results have been obtained for normal cooling of the primary heat transport system following a planned shut down (transition from full power to shutdown) and for two special SDCS configurations that were used on September 14 and 15, 2006 at Gentilly-2. The results show close match with values measured at Gentilly-2 during either steady or transient states. (author)

  4. Development and validation of the shutdown cooling system CATHENA model for Gentilly-2

    Energy Technology Data Exchange (ETDEWEB)

    Lecuyer, H.; Hasnaoui, C. [Nucleonex Inc., Westmount, Quebec (Canada); Sabourin, G. [Atomic Energy of Canada Limited, Montreal, Quebec (Canada); Chapados, S. [Hydro-Quebec, Unite Analyse et Fiabilite, Montreal, Quebec (Canada)

    2008-07-01

    A CATHENA representation of the Gentilly-2 Shutdown Cooling system has been developed for Hydro-Quebec. The model includes the SDCS circuit piping, valves, pumps and heat exchangers. The model is integrated in the G2 CATHENA overall plant model and coupled with the plant control software simulator TROLG2 to allow the simulation of various plant operational modes using the SDCS. Results have been obtained for normal cooling of the primary heat transport system following a planned shut down (transition from full power to shutdown) and for two special SDCS configurations that were used on September 14 and 15, 2006 at Gentilly-2. The results show close match with values measured at Gentilly-2 during either steady or transient states. (author)

  5. Proceedings: Cooling tower and advanced cooling systems conference

    International Nuclear Information System (INIS)

    1995-02-01

    This Cooling Tower and Advanced Cooling Systems Conference was held August 30 through September 1, 1994, in St. Petersburg, Florida. The conference was sponsored by the Electric Power Research Institute (EPRI) and hosted by Florida Power Corporation to bring together utility representatives, manufacturers, researchers, and consultants. Nineteen technical papers were presented in four sessions. These sessions were devoted to the following topics: cooling tower upgrades and retrofits, cooling tower performance, cooling tower fouling, and dry and hybrid systems. On the final day, panel discussions addressed current issues in cooling tower operation and maintenance as well as research and technology needs for power plant cooling. More than 100 people attended the conference. This report contains the technical papers presented at the conference. Of the 19 papers, five concern cooling tower upgrades and retrofits, five to cooling tower performance, four discuss cooling tower fouling, and five describe dry and hybrid cooling systems. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database

  6. Two-Dimensional Numerical Study on the Migration of Particle in a Serpentine Channel

    Directory of Open Access Journals (Sweden)

    Yi Liu

    2018-01-01

    Full Text Available In this work, the momentum exchange scheme-based lattice Boltzmann method is adopted to numerically study the migration of a circular particle in a serpentine channel for the range of 20 ≤ Re ≤ 120. The effects of the Reynolds number, particle density, and the initial particle position are taken into account. Numerical results include the streamlines, particle trajectories, and final equilibrium positions. Close attention is also paid to the time it takes for the particle to travel in the channel. It has been found that the particle is likely to migrate to a similar equilibrium position irrespective of its initial position when Re is large. Furthermore, there exists a critical solid-to-fluid density ratio for which the particle travels fastest in the channel.

  7. Design Of Pump Monitoring Of Primary Cooling System

    International Nuclear Information System (INIS)

    Indrakoesoema, Koes; Sujarwono

    2000-01-01

    Monitoring of 3 primary cooling pumps done visually by operator on the spot. The operator must be check oil in a sight glass, oil leakage during pump operation and water leakage. If reaktor power increase about more than 3 MW, the radiation exposure also increase in the primary cell and that's way the operator can not check the pumps. To continuing monitor all pump without delay, one system has been added I.e Closed Circuit Television (CCTV). This system using 3 video camera to monitor 3 pumps and connected to one receiver video monitor by coaxial cable located in Main Control Room. The sequence monitoring can be done by sequential switcher

  8. Circuit analysis for dummies

    CERN Document Server

    Santiago, John

    2013-01-01

    Circuits overloaded from electric circuit analysis? Many universities require that students pursuing a degree in electrical or computer engineering take an Electric Circuit Analysis course to determine who will ""make the cut"" and continue in the degree program. Circuit Analysis For Dummies will help these students to better understand electric circuit analysis by presenting the information in an effective and straightforward manner. Circuit Analysis For Dummies gives you clear-cut information about the topics covered in an electric circuit analysis courses to help

  9. Current limiter circuit system

    Science.gov (United States)

    Witcher, Joseph Brandon; Bredemann, Michael V.

    2017-09-05

    An apparatus comprising a steady state sensing circuit, a switching circuit, and a detection circuit. The steady state sensing circuit is connected to a first, a second and a third node. The first node is connected to a first device, the second node is connected to a second device, and the steady state sensing circuit causes a scaled current to flow at the third node. The scaled current is proportional to a voltage difference between the first and second node. The switching circuit limits an amount of current that flows between the first and second device. The detection circuit is connected to the third node and the switching circuit. The detection circuit monitors the scaled current at the third node and controls the switching circuit to limit the amount of the current that flows between the first and second device when the scaled current is greater than a desired level.

  10. Mineral textures in Serpentine-hosted Alkaline Springs from the Oman ophiolite

    Science.gov (United States)

    Giampouras, Manolis; Garcia-Ruiz, Juan Manuel; Bach, Wolfgang; Garrido, Carlos J.; Los, Karin; Fussmann, Dario; Monien, Monien

    2017-04-01

    Meteoric water infiltration in ultramafic rocks leads to serpentinization and the formation of subaerial, low temperature, hydrothermal alkaline springs. Here, we present a detailed investigation of the mineral precipitation mechanisms and textural features of mineral precipitates, along as the geochemical and hydrological characterization, of two alkaline spring systems in the Semail ophiolite (Nasif and Khafifah sites, Wadi Tayin massif). The main aim of the study is to provide new insights into mineral and textural variations in active, on-land, alkaline vents of the Oman ophiolite. Discharge of circulating fluids forms small-scale, localized hydrological catchments consisting in unevenly interconnected ponds. Three different types of waters can be distinguished within the pond systems: i) Mg-type; alkaline (7.9 11.6), Ca-OH-rich waters; and iii) Mix-type waters arising from the mixing of Mg-type and Ca-type waters (9.6 ponds were carried out by X-ray diffraction (XRD), Raman spectroscopy and field-emission scanning electron microscopy coupled to dispersive energy spectroscopy (FE-SEM-EDS). Aragonite and calcite are the dominant minerals (95 vol.%) of the total mineralogical index in all sites. Mg-type waters host hydrated magnesium carbonates (nesquehonite) and magnesium hydroxycarbonate hydrates (artinite) due to evaporation. Brucite, hydromagnesite and dypingite presence in Mix-type waters is spatially controlled by the hydrology of the system and is localized around mixing zones between Ca-type with Mg-type waters. Residence time of discharging waters in the ponds before mixing has an impact on fluid chemistry as it influences the equilibration time with the atmosphere. Acicular aragonite is the main textural type in hyper-alkaline Ca-type waters, acting as a substratum for the growth of calcite and brucite crystals. Low crystallinity, dumbbell shaped and double pyramid aragonite dominates in Mix-type water precipitates. Rate of supersaturation is essential

  11. Potential autotrophic metabolisms in ultra-basic reducing springs associated with present-day continental serpentinization

    Science.gov (United States)

    Morrill, P. L.; Miles, S.; Kohl, L.; Kavanagh, H.; Ziegler, S. E.; Brazelton, W. J.; Schrenk, M. O.

    2013-12-01

    Ultra-basic reducing springs at continental sites of serpentinization act as windows into the biogeochemistry of this subsurface exothermic environment rich in H2 and CH4 gases. Biogeochemical carbon transformations in these systems are of interest because serpentinization creates conditions that are amenable to abiotic and biotic reduction of carbon. However, little is known about the metabolic capabilities of the microorganisms that live in this environment. To determine the potential for autotrophic metabolisms, bicarbonate and CO substrate addition microcosm experiments were performed using water and sediment from an ultra-basic reducing spring in the Tablelands, Newfoundland, Canada, a site of present-day continental serpentinization. CO was consistently observed to be utilized in the Live but not the Killed controlled replicates amended with 10% 13C labelled CO and non-labelled (natural C isotope abundance) CO. In the Live CO microcosms with natural C isotope abundance, the residual CO became enriched in 13C (~10 ‰) consistent with a decrease in the fraction of CO remaining. In the Killed CO controlled replicates with natural C isotope abundance the CO showed little 13C enrichment (~1.3 ‰). The data from the Live CO microcosms were well described by a Rayleigh isotopic distillation model, yielding an isotopic enrichment factor for microbial CO uptake of 15.7 ×0.5 ‰ n=2. These data suggest that there was microbial CO utilization in these experiments. The sediment and water from the 13C-labelled and non-labelled, Live and Killed microcosms were extracted for phospholipid fatty acids (PLFAs) to determine changes in community composition between treatments as well as to determine the microbial uptake of CO. The difference in community composition between the Live and Killed microcosms was not readily resolvable based on PLFA distributions. Additionally, the microbial uptake of 13CO had minimal to no affect on the δ13C of the cellular biomarkers, with the

  12. The voltage—current relationship and equivalent circuit implementation of parallel flux-controlled memristive circuits

    International Nuclear Information System (INIS)

    Bao Bo-Cheng; Feng Fei; Dong Wei; Pan Sai-Hu

    2013-01-01

    A flux-controlled memristor characterized by smooth cubic nonlinearity is taken as an example, upon which the voltage—current relationships (VCRs) between two parallel memristive circuits — a parallel memristor and capacitor circuit (the parallel MC circuit), and a parallel memristor and inductor circuit (the parallel ML circuit) — are investigated. The results indicate that the VCR between these two parallel memristive circuits is closely related to the circuit parameters, and the frequency and amplitude of the sinusoidal voltage stimulus. An equivalent circuit model of the memristor is built, upon which the circuit simulations and experimental measurements of both the parallel MC circuit and the parallel ML circuit are performed, and the results verify the theoretical analysis results

  13. EFFECT OF PRE-COOLING ON REPEAT-SPRINT PERFORMANCE IN SEASONALLY ACCLIMATISED MALES DURING AN OUTDOOR SIMULATED TEAM-SPORT PROTOCOL IN WARM CONDITIONS

    Directory of Open Access Journals (Sweden)

    Carly J. Brade

    2013-09-01

    Full Text Available Whether precooling is beneficial for exercise performance in warm climates when heat acclimatised is unclear. The purpose of this study was to determine the effect of precooling on repeat-sprint performance during a simulated team-sport circuit performed outdoors in warm, dry field conditions in seasonally acclimatised males (n = 10. They performed two trials, one with precooling (PC; ice slushy and cooling jacket and another without (CONT. Trials began with a 30-min baseline/cooling period followed by an 80 min repeat-sprint protocol, comprising 4 x 20-min quarters, with 2 x 5-min quarter breaks and a 10-min half-time recovery/cooling period. A clear and substantial (negative; PC slower effect was recorded for first quarter circuit time. Clear and trivial effects were recorded for overall circuit time, third and fourth quarter sprint times and fourth quarter best sprint time, otherwise unclear and trivial effects were recorded for remaining performance variables. Core temperature was moderately lower (Cohen's d=0.67; 90% CL=-1.27, 0.23 in PC at the end of the precooling period and quarter 1. No differences were found for mean skin temperature, heart rate, thermal sensation, or rating of perceived exertion, however, moderate Cohen's d effect sizes suggested a greater sweat loss in PC compared with CONT. In conclusion, repeat- sprint performance was neither clearly nor substantially improved in seasonally acclimatised players by using a combination of internal and external cooling methods prior to and during exercise performed in the field in warm, dry conditions. Of practical importance, precooling appears unnecessary for repeat-sprint performance if athletes are seasonally acclimatised or artificially acclimated to heat, as it provides no additional benefit

  14. Reduction in the specific consumption of heat by the thermal circuit, achieved by rationalization of the steam turbine condensation at nuclear power plants of the WWER-440 type

    International Nuclear Information System (INIS)

    Kubacek, A.

    1992-01-01

    Specific consumption of heat needed for the production of a net electricity unit is a criterion for assessing the efficiency of conversion of thermal energy into mechanical energy in the steam turbine. Based on theoretical calculations and analyses, a way of evaluating the specific heat consumption is demonstrated for the thermal circuit of the steam-engine equipment with one turbogenerator. The dependence of the specific heat consumption on the steam condensation temperature and on the amount of cooling water flowing through the condenser is calculated, as is the dependence of the limiting pressure on the relative loss of vacuum of the condenser and on the cooling water temperature. Such dependences can be used to upgrade the thermal circuit condensation regime. (M.D.). 2 figs., 12 refs

  15. High-quality GaN epitaxially grown on Si substrate with serpentine channels

    Science.gov (United States)

    Wei, Tiantian; Zong, Hua; Jiang, Shengxiang; Yang, Yue; Liao, Hui; Xie, Yahong; Wang, Wenjie; Li, Junze; Tang, Jun; Hu, Xiaodong

    2018-06-01

    A novel serpentine-channeled mask was introduced to Si substrate for low-dislocation GaN epitaxial growth and the fully coalesced GaN film on the masked Si substrate was achieved for the first time. Compared with the epitaxial lateral overgrowth (ELOG) growth method, this innovative mask only requires one-step epitaxial growth of GaN which has only one high-dislocation region per mask opening. This new growth method can effectively reduce dislocation density, thus improving the quality of GaN significantly. High-quality GaN with low dislocation density ∼2.4 × 107 cm-2 was obtained, which accounted for about eighty percent of the GaN film in area. This innovative technique is promising for the growth of high-quality GaN templates and the subsequent fabrication of high-performance GaN-based devices like transistors, laser diodes (LDs), and light-emitting diodes (LEDs) on Si substrate.

  16. Discrete-State Simulated Annealing For Traveling-Wave Tube Slow-Wave Circuit Optimization

    Science.gov (United States)

    Wilson, Jeffrey D.; Bulson, Brian A.; Kory, Carol L.; Williams, W. Dan (Technical Monitor)

    2001-01-01

    Algorithms based on the global optimization technique of simulated annealing (SA) have proven useful in designing traveling-wave tube (TWT) slow-wave circuits for high RF power efficiency. The characteristic of SA that enables it to determine a globally optimized solution is its ability to accept non-improving moves in a controlled manner. In the initial stages of the optimization, the algorithm moves freely through configuration space, accepting most of the proposed designs. This freedom of movement allows non-intuitive designs to be explored rather than restricting the optimization to local improvement upon the initial configuration. As the optimization proceeds, the rate of acceptance of non-improving moves is gradually reduced until the algorithm converges to the optimized solution. The rate at which the freedom of movement is decreased is known as the annealing or cooling schedule of the SA algorithm. The main disadvantage of SA is that there is not a rigorous theoretical foundation for determining the parameters of the cooling schedule. The choice of these parameters is highly problem dependent and the designer needs to experiment in order to determine values that will provide a good optimization in a reasonable amount of computational time. This experimentation can absorb a large amount of time especially when the algorithm is being applied to a new type of design. In order to eliminate this disadvantage, a variation of SA known as discrete-state simulated annealing (DSSA), was recently developed. DSSA provides the theoretical foundation for a generic cooling schedule which is problem independent, Results of similar quality to SA can be obtained, but without the extra computational time required to tune the cooling parameters. Two algorithm variations based on DSSA were developed and programmed into a Microsoft Excel spreadsheet graphical user interface (GUI) to the two-dimensional nonlinear multisignal helix traveling-wave amplifier analysis program TWA3

  17. Prolonged silicon carbide integrated circuit operation in Venus surface atmospheric conditions

    Directory of Open Access Journals (Sweden)

    Philip G. Neudeck

    2016-12-01

    Full Text Available The prolonged operation of semiconductor integrated circuits (ICs needed for long-duration exploration of the surface of Venus has proven insurmountably challenging to date due to the ∼ 460 °C, ∼ 9.4 MPa caustic environment. Past and planned Venus landers have been limited to a few hours of surface operation, even when IC electronics needed for basic lander operation are protected with heavily cumbersome pressure vessels and cooling measures. Here we demonstrate vastly longer (weeks electrical operation of two silicon carbide (4H-SiC junction field effect transistor (JFET ring oscillator ICs tested with chips directly exposed (no cooling and no protective chip packaging to a high-fidelity physical and chemical reproduction of Venus’ surface atmosphere. This represents more than 100-fold extension of demonstrated Venus environment electronics durability. With further technology maturation, such SiC IC electronics could drastically improve Venus lander designs and mission concepts, fundamentally enabling long-duration enhanced missions to the surface of Venus.

  18. Optimal design and placement of serpentine heat exchangers for indirect heat withdrawal, inside flat plate integrated collector storage solar water heaters (ICSSWH)

    Energy Technology Data Exchange (ETDEWEB)

    Gertzos, K.P.; Caouris, Y.G.; Panidis, T. [Dept. of Mechanical Engineering and Aeronautics, University of Patras, 265 00 Patras (Greece)

    2010-08-15

    Parameters that affect the temperature at which service hot water (SHW) is offered by an immersed tube heat exchanger (HX), inside a flat plate Integrated Collector Storage Solar Water Heater (ICSSWH), are examined numerically, by means of Computational Fluid Dynamics (CFD) analysis. The storage water is not refreshed and serves for heat accumulation. Service hot water is drawn off indirectly, through an immersed serpentine heat exchanger. For the intensification of the heat transfer process, the storage water is agitated by recirculation through a pump, which goes on only when service water flows inside the heat exchanger. Three main factors, which influence the performance, are optimized: The position of the HX relative to tank walls, the HX length and the tube diameter. All three factors are explored so that to maximize the service water outlet temperature. The settling time of the optimum configuration is also computed. Various 3-D CFD models were developed using the FLUENT package. The heat transfer rate between the two circuits of the optimum configuration is maintained at high levels, leading to service water outlet temperatures by 1-7 C lower than tank water temperatures, for the examined SHW flow rates. The settling time is retained at sufficient law values, such as 20 s. The optimal position was found to lay the HX in contact with the front and back walls of the tank, with an optimum inner tube diameter of 16 mm, while an acceptable HX length was found to be about 21.5 m. (author)

  19. Modelling nonstationary thermohydrodynamic processes in heat-exchange circuits with a two-phase coolant

    International Nuclear Information System (INIS)

    Blinkov, V.N.

    1993-01-01

    This paper presents a mathematical model and a open-quotes fastclose quotes computer program for analyzing nonstationary thermohydrodynamic processes in distributed multi-element circuits containing a two-phase coolant. The author's approach is based on representing the distributed multi-element circuits with the two-phase coolant (such as cooling circuits of the reactor of an atomic power station) in the form of equivalent thermohydrodynamic chains composed of idealized elements with the intrinsic properties of the structure elements of real systems. The author has developed the nomenclature of such conceptual elements for objects which can be modelled; the nomenclature encompasses the control volumes (with a single-phase or two-phase coolant or a moving boundary of boiling/condensation) and the branch lines (type of tube and connections in dependence on the inertia of the coolant being taken into account) for a hydrodynamic submodel and the thermal components and lines for a thermal submodel. The mathematical models which have been developed and the program using them are designated for various forms of calculating slow thermohydrodynamic processes in multi-element coolant circuits in reactors and modeling test stands. The program facilitates calculation of the range of stable operation, detailed studies of stationary and nonstationary modes of operation, and forecasts of effective engineering measures to obtain stability with the aid of microcomputers

  20. 30 CFR 75.518 - Electric equipment and circuits; overload and short circuit protection.

    Science.gov (United States)

    2010-07-01

    ... short circuit protection. 75.518 Section 75.518 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... Equipment-General § 75.518 Electric equipment and circuits; overload and short circuit protection... installed so as to protect all electric equipment and circuits against short circuit and overloads. Three...

  1. Cooling solutions in an operational data centre: A case study

    International Nuclear Information System (INIS)

    Fakhim, B.; Behnia, M.; Armfield, S.W.; Srinarayana, N.

    2011-01-01

    The rapid growth in data centres - large computing infrastructures containing vast quantities of data processing and storage equipment - has resulted in their consumption of up to 100 times more energy per square metre than office accommodation. The decrease in processing server sizes and the more efficient use of space and server processing are challenging data centre facilities to provide more power and cooling, significantly increasing energy demands. Energy consumption of data centres can be severely and unnecessarily high due to inadequate localised cooling and densely packed server rack layouts. However, as heat dissipation in data centres rises by orders of magnitude, inefficiencies such as air recirculation causing hot spots and flow short-circuiting will have a significant impact on the thermal manageability and energy efficiency of the cooling infrastructure. Therefore, an efficient thermal management of high-powered electronic equipment is a significant challenge for cooling of data centres. To highlight the importance of some of these issues, in this project, an operational data centre has been studied. Field measurements of temperature have been performed. Numerical analysis of flow and temperature fields is conducted in order to evaluate the thermal behaviour of the data centre. A number of undesirable hot spots have been identified. To rectify the problem, a few practical design and remedial solutions to improve the cooling effectiveness have been proposed and examined to allow a reduced air-conditioning power requirement. The findings lead to a better understanding of the cooling issues and the respective proposed solutions allow an improved design for future data centres. - Highlights: → Study of flow and temperature distribution in an operational data centre. → Both field measurements and numerical simulations are conducted. → Numerical simulations are validated by field measurements. → Various modifications to improve the thermal

  2. 30 CFR 77.506 - Electric equipment and circuits; overload and short-circuit protection.

    Science.gov (United States)

    2010-07-01

    ... short-circuit protection. 77.506 Section 77.506 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... circuits; overload and short-circuit protection. Automatic circuit-breaking devices or fuses of the correct type and capacity shall be installed so as to protect all electric equipment and circuits against short...

  3. Microbial analysis of meatballs cooled with vacuum and conventional cooling.

    Science.gov (United States)

    Ozturk, Hande Mutlu; Ozturk, Harun Kemal; Koçar, Gunnur

    2017-08-01

    Vacuum cooling is a rapid evaporative cooling technique and can be used for pre-cooling of leafy vegetables, mushroom, bakery, fishery, sauces, cooked food, meat and particulate foods. The aim of this study was to apply the vacuum cooling and the conventional cooling techniques for the cooling of the meatball and to show the vacuum pressure effect on the cooling time, the temperature decrease and microbial growth rate. The results of the vacuum cooling and the conventional cooling (cooling in the refrigerator) were compared with each other for different temperatures. The study shows that the conventional cooling was much slower than the vacuum cooling. Moreover, the microbial growth rate of the vacuum cooling was extremely low compared with the conventional cooling. Thus, the lowest microbial growth occurred at 0.7 kPa and the highest microbial growth was observed at 1.5 kPa for the vacuum cooling. The mass loss ratio for the conventional cooling and vacuum cooling was about 5 and 9% respectively.

  4. Analysis on blow-down transient in water ingress accident of high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Wang, Yan; Zheng, Yanhua; Li, Fu; Shi, Lei

    2014-01-01

    Water ingress into the primary circuit is generally recognized as one of the severe accidents with potential hazard to the modular high temperature gas-cooled reactor, which will cause a positive reactivity introduction with the increase of steam density in reactor core to enhance neutron slowing-down, also the chemical corrosion of graphite fuel elements and the damage of reflector structure material. The increase of the primary pressure may result in the opening of the safety valves, consequently leading the release of radioactive isotopes and flammable water gas. The research on water ingress transient is significant for the verification of inherent safety characteristics of high temperature gas-cooled reactor. The 200 MWe high temperature gas-cooled reactor (HTR-PM), designed by the Institute of Nuclear and New Energy Technology of Tsinghua University, is exampled to be analyzed in this paper. The design basis accident (DBA) scenarios of double-ended guillotine break of single heat-exchange tube (steam generator heat-exchange tube rupture) are simulated by the thermal-hydraulic analysis code, and some key concerns which are relative to the amount of water into the reactor core during the blow-down transient are analyzed in detail. The results show that both of water mass and steam ratio of the fluid spouting from the broken heat-exchange tube are affected by break location, which will increase obviously with the broken location closing to the outlet of the heat-exchange tube. The double-ended guillotine rupture at the outlet of the heat-exchange will result more steam penetrates into the reactor core in the design basis accident of water ingress. The mass of water ingress will also be affected by the draining system. It is concluded that, with reasonable optimization on design to balance safety and economy, the total mass of water ingress into the primary circuit of reactor could be limited effectively to meet the safety requirements, and the pollution of

  5. Hybrid electric vehicle thermal management and study of the power electronics cooling; Gestion thermique du vehicule hybride et etude du refroidissement de l'electronique de puissance

    Energy Technology Data Exchange (ETDEWEB)

    Rouaud, C.

    2004-07-01

    For decreasing the engine's consumption and pollutant emissions, automobile makers are developing hybrid electric vehicles incorporating an electric motor and power electronics leading to new under-hood thermal constraints. This is why we first present the tests results of a new common cooling circuit for all the vehicle components. With the aim of developing new energy management strategies between the components, we have chosen the nodal method to simulate the thermal behaviour of the engine, the electric motor, the power electronics and the cooling circuit. The second part of this thesis deals with a thermal-hydraulic analysis of several power electronics cooling methods, which has led us to choose the multiple jet impingement cooling. Several tests have been made for characterising the performances of this technique and enabled us to establish an optimal configuration. The last part shows the thermal simulation results run with the help of an innovative reduction method of thermal models applied to the power electronics. This technique allowed us to have a low cost of time simulation and will permit, in the future, the real-time control of the hybrid electric vehicle components. (author)

  6. Validation of CATHARE for gas-cooled reactors

    International Nuclear Information System (INIS)

    Fabrice Bentivoglio; Ola Widlund; Manuel Saez

    2005-01-01

    Full text of publication follows: Extensively validated and qualified for light-water reactor safety studies, the thermo-hydraulics code CATHARE has been adapted to deal also with gas-cooled reactor applications. In order to validate the code for these novel applications, CEA (Commissariat a l'Energie Atomique) has initiated an ambitious long-term experimental program. The foreseen experimental facilities range from small-scale loops for physical correlations, to component technology and system demonstration loops. In the short-term perspective, CATHARE is being validated against existing experimental data, in particular from the German power plant Oberhausen II and the South African Pebble-Bed Micro Model (PBMM). Oberhausen II, operated by the German utility EVO, is a 50 MW(e) direct-cycle Helium turbine plant. The power source is a gas burner rather than a nuclear reactor core, but the power conversion system resembles those of the GFR (Gas-cooled Fast Reactor) and other high-temperature reactor concepts. Oberhausen II was operated for more than 100 000 hours between 1974 and 1988. Design specifications, drawings and experimental data have been obtained through the European HTR project, offering a unique opportunity to validate CATHARE on a large-scale Brayton cycle. Available measurements of temperatures, pressures and mass flows throughout the circuit have allowed a very comprehensive thermohydraulic description of the plant, in steady-state conditions as well as during transients. The Pebble-Bed Micro Model (PBMM) is a small-scale model conceived to demonstrate the operability and control strategies of the South African PBMR concept. The model uses Nitrogen instead of Helium, and an electrical heater with a maximum rating of 420 kW. As the full-scale PBMR, the PBMM loop features three turbines and two compressors on the primary circuit, located on three separate shafts. The generator, however, is modelled by a third compressor on a separate circuit, with a

  7. Volumetric and chemical control auxiliary circuit for a PWR primary circuit

    International Nuclear Information System (INIS)

    Costes, D.

    1990-01-01

    The volumetric and chemical control circuit has an expansion tank with at least one water-steam chamber connected to the primary circuit by a sampling pipe and a reinjection pipe. The sampling pipe feeds jet pumps controlled by valves. An action on these valves and pumps regulates the volume of the water in the primary circuit. A safety pipe controlled by a flap automatically injects water from the chamber into the primary circuit in case of ruptures. The auxiliary circuit has also systems for purifying the water and controlling the boric acid and hydrogen content [fr

  8. Cooling techniques

    International Nuclear Information System (INIS)

    Moeller, S.P.

    1994-01-01

    After an introduction to the general concepts of cooling of charged particle beams, some specific cooling methods are discussed, namely stochastic, electron and laser cooling. The treatment concentrates on the physical ideas of the cooling methods and only very crude derivations of cooling times are given. At the end three other proposed cooling schemes are briefly discussed. (orig.)

  9. In situ electrochemical enrichment and isolation of a magnetite-reducing bacterium from a high pH serpentinizing spring.

    Science.gov (United States)

    Rowe, Annette R; Yoshimura, Miho; LaRowe, Doug E; Bird, Lina J; Amend, Jan P; Hashimoto, Kazuhito; Nealson, Kenneth H; Okamoto, Akihiro

    2017-06-01

    Serpentinization is a geologic process that produces highly reduced, hydrogen-rich fluids that support microbial communities under high pH conditions. We investigated the activity of microbes capable of extracellular electron transfer in a terrestrial serpentinizing system known as 'The Cedars'. Measuring current generation with an on-site two-electrode system, we observed daily oscillations in current with the current maxima and minima occurring during daylight hours. Distinct members of the microbial community were enriched. Current generation in lab-scale electrochemical reactors did not oscillate, but was correlated with carbohydrate amendment in Cedars-specific minimal media. Gammaproteobacteria and Firmicutes were consistently enriched from lab electrochemical systems on δ-MnO 2 and amorphous Fe(OH) 3 at pH 11. However, isolation of an electrogenic strain proved difficult as transfer cultures failed to grow after multiple rounds of media transfer. Lowering the bulk pH in the media allowed us to isolate a Firmicutes strain (Paenibacillus sp.). This strain was capable of electrode and mineral reduction (including magnetite) at pH 9. This report provides evidence of the in situ activity of microbes using extracellular substrates as sinks for electrons at The Cedars, but also highlights the potential importance of community dynamics for supporting microbial life through either carbon fixation, and/or moderating pH stress. © 2017 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  10. Annual investigation of vertical type ground source heat pump system performance on a wall heating and cooling system in Istanbul

    Energy Technology Data Exchange (ETDEWEB)

    Akbulut, U.; Yoru, Y.; Kincay, O. [Department of Mechanical Engineering, Yildiz Technical University (Turkey)], email: akbulutugur@yahoo.com, email: yilmazyoru@gmail.com, email: okincay@yildiz.edu.tr

    2011-07-01

    Wall heating and cooling systems (WHCS) are equipped with heating serpentines or panels for water circulation. These systems operate in a low temperature range so they are preferable to other, conventional systems. Furthermore, when these systems are connected to a ground source heat pump (GSHP) system, energy performance and thermal comfort are further enhanced. The purpose of this paper is to report the results of an annual inspection done on a vertical type ground-coupled heat pump systems (V-GSHP) WHCS in Istanbul and present the results. The performance data from the Yildiz Renewable Energy House at Davutpasa Campus of Yildiz Technical University, Istanbul, Turkey, during the year 2010 were collected and analyzed. The conclusions drawn from the inspection and analysis were listed in this paper. Using renewable energy sources effectively will bring both economic and environmental benefits and it is hoped that the use of these energy efficient WHCS systems will become widespread.

  11. Experimental Investigation Into Thermal Siphon Used as an Intermediate Circuit of an Integrated Cooling System Reactor

    International Nuclear Information System (INIS)

    Adamovich, L.A.; Gabaraev, B.A.; Solovjev, S.L.; Shpansky, S.B.

    2002-01-01

    In the paper the results of study in heat transfer capacity of the thermosyphon mock-up which is considered as an intermediate circuit of the reactor under design, are presented. The mock-up design, the test rig and the experimental results are described. It is shown that the simplest mathematical model describes the processes of power transfer by the thermosyphon under certain conditions. (authors)

  12. Intuitive analog circuit design

    CERN Document Server

    Thompson, Marc

    2013-01-01

    Intuitive Analog Circuit Design outlines ways of thinking about analog circuits and systems that let you develop a feel for what a good, working analog circuit design should be. This book reflects author Marc Thompson's 30 years of experience designing analog and power electronics circuits and teaching graduate-level analog circuit design, and is the ideal reference for anyone who needs a straightforward introduction to the subject. In this book, Dr. Thompson describes intuitive and ""back-of-the-envelope"" techniques for designing and analyzing analog circuits, including transistor amplifi

  13. The circuit designer's companion

    CERN Document Server

    Williams, Tim

    1991-01-01

    The Circuit Designer's Companion covers the theoretical aspects and practices in analogue and digital circuit design. Electronic circuit design involves designing a circuit that will fulfill its specified function and designing the same circuit so that every production model of it will fulfill its specified function, and no other undesired and unspecified function.This book is composed of nine chapters and starts with a review of the concept of grounding, wiring, and printed circuits. The subsequent chapters deal with the passive and active components of circuitry design. These topics are foll

  14. Electronic devices and circuits

    CERN Document Server

    Pridham, Gordon John

    1972-01-01

    Electronic Devices and Circuits, Volume 3 provides a comprehensive account on electronic devices and circuits and includes introductory network theory and physics. The physics of semiconductor devices is described, along with field effect transistors, small-signal equivalent circuits of bipolar transistors, and integrated circuits. Linear and non-linear circuits as well as logic circuits are also considered. This volume is comprised of 12 chapters and begins with an analysis of the use of Laplace transforms for analysis of filter networks, followed by a discussion on the physical properties of

  15. Risk Analyses of Charging Pump Control Improvements for Alternative RCP Seal Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun-Chan [Korea Hydro and Nuclear Power Co. Ltd. Daejeon (Korea, Republic of)

    2015-10-15

    There are two events that significantly affect the plant risk during a TLOCCW event. One is an event in which the seal assembly of a reactor coolant pump (RCP) fails due to heating stress from the loss of cooling water; the other is an event in which the operators fail to conduct alternative cooling for the RCP seal during the accident. KHNP reviewed the replacement of the RCP seal with a qualified shutdown seal in order to remove the risk due to RCP seal failure during a TLOCCW. As an optional measure, a design improvement in the alternative cooling method for the RCP seal is being considered. This analysis presents the alternative RCP seal cooling improvement and its safety effect. K2 is a nuclear power plant with a Westinghouse design, and it has a relatively high CDF during TLOCCW events because it has a different CCW system design and difficulty in preparing alternative cooling water sources. This analysis confirmed that an operator action providing cold water to the RWST as RCP seal injection water during a TLOCCW event is very important in K2. The control circuit improvement plan for the auxiliary charging pump was established in order to reduce the failure probability of this operator action. This analysis modeled the improvement as a fault tree and evaluated the resulting CDF change. The consequence demonstrated that the RCP seal injection failure probability was reduced by 89%, and the CDF decreased by 28%.

  16. Signal sampling circuit

    NARCIS (Netherlands)

    Louwsma, S.M.; Vertregt, Maarten

    2011-01-01

    A sampling circuit for sampling a signal is disclosed. The sampling circuit comprises a plurality of sampling channels adapted to sample the signal in time-multiplexed fashion, each sampling channel comprising a respective track-and-hold circuit connected to a respective analogue to digital

  17. Signal sampling circuit

    NARCIS (Netherlands)

    Louwsma, S.M.; Vertregt, Maarten

    2010-01-01

    A sampling circuit for sampling a signal is disclosed. The sampling circuit comprises a plurality of sampling channels adapted to sample the signal in time-multiplexed fashion, each sampling channel comprising a respective track-and-hold circuit connected to a respective analogue to digital

  18. Performance of Polycrystalline Photovoltaic and Thermal Collector (PVT on Serpentine-Parallel Absor

    Directory of Open Access Journals (Sweden)

    Mustofa

    2015-10-01

    Full Text Available This paper presents the performance of an unglazed polycrystalline photovoltaic-thermal PVT on 0.045 kg/s mass flow rate. PVT combine photovoltaic modules and solar thermal collectors, forming a single device that receive solar radiation and produces heat and electricity simultaneously. The collector figures out serpentine-parallel tubes that can prolong fluid heat conductivity from morning till afternoon. During testing, cell PV, inlet and outlet fluid temperatures were recorded by thermocouple digital LM35 Arduino Mega 2560. Panel voltage and electric current were also noted in which they were connected to computer and presented each second data recorded. But, in this performance only shows in the certain significant time data. This because the electric current was only noted by multimeter device not the digital one. Based on these testing data, average cell efficiency was about 19%, while thermal efficiency of above 50% and correspondent cell efficiency of 11%, respectively.

  19. Kinetics of Grinding of Secondary Serpentine Raw Material at Cascade Operating Mode

    Directory of Open Access Journals (Sweden)

    Marek Matik

    2004-12-01

    Full Text Available The paper deals with the grinding of secondary serpentine material from the Dobšiná´s heap in a ball ceramic mill. The raw material was pre-sieved to prepare fraction of +250 –1,000 µm that was fed to the mill. During batch experiment an amount of oversize on the screen with a mesh size of 200 µm was observed as a function of time. Two speed modes were tested. Firstly, it was the mode designed by mill producer implicit from the structure of milling stand equipped by electromotor, friction gear onto driving shaft with given diameter. The speed of this original alignment attains 40 rmp. Secondly, it was cascade speed mode according to the Haase´s equation, namely 53 rmp, achieved by enlargement of driving shaft diameter. As to winning of required final product 90 % –200 µm, increased speed resulted in the shortening of grinding time from 17.5 to15.7 hour.

  20. Evaluation of ilmenite serpentine concrete and ordinary concrete as nuclear reactor shielding

    International Nuclear Information System (INIS)

    Abulfaraj, W.H.; Kamal, S.M.

    1994-01-01

    The present study involves adapting a formal decision methodology to the selection of alternative nuclear reactor concrete shielding. Multiattribute utility theory is selected to accommodate decision maker's preferences. Multiattribute utility theory (MAU) is here employed to evaluate two appropriate nuclear reactor shielding concretes in terms of effectiveness to determine the optimal choice in order to meet the radiation protection regulations. These concretes are Ordinary concrete (O.C.) and Illmenite Serpentile concrete (I.S.C.). These are normal weight concrete and heavy weight heat resistive concrete, respectively. The effectiveness objective of the nuclear reactor shielding is defined and structured into definite attributes and subattributes to evaluate the best alternative. Factors affecting the decision are dose received by reactor's workers, the material properties as well as cost of concrete shield. A computer program is employed to assist in performing utility analysis. Based upon data, the result shows the superiority of Ordinary concrete over Illmenite Serpentine concrete. (Author)

  1. Electric circuits essentials

    CERN Document Server

    REA, Editors of

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Electric Circuits I includes units, notation, resistive circuits, experimental laws, transient circuits, network theorems, techniques of circuit analysis, sinusoidal analysis, polyph

  2. Approximate circuits for increased reliability

    Science.gov (United States)

    Hamlet, Jason R.; Mayo, Jackson R.

    2015-08-18

    Embodiments of the invention describe a Boolean circuit having a voter circuit and a plurality of approximate circuits each based, at least in part, on a reference circuit. The approximate circuits are each to generate one or more output signals based on values of received input signals. The voter circuit is to receive the one or more output signals generated by each of the approximate circuits, and is to output one or more signals corresponding to a majority value of the received signals. At least some of the approximate circuits are to generate an output value different than the reference circuit for one or more input signal values; however, for each possible input signal value, the majority values of the one or more output signals generated by the approximate circuits and received by the voter circuit correspond to output signal result values of the reference circuit.

  3. Removal of tritium from gas-cooled nuclear reactors

    International Nuclear Information System (INIS)

    Nieder, R.

    1976-01-01

    Tritium contained in the coolant gas in the primary circuit of a gas cooled nuclear reactor together with further tritium adsorbed on the graphite used as a moderator for the reactor is removed by introducing hydrogen or a hydrogen-containing compound, for example methane or ammonia, into the coolant gas. The addition of the hydrogen or hydrogen-containing compound to the coolant gas causes the adsorbed tritium to be released into the coolant gas and the tritium is then removed from the coolant gas by passing the mixture of coolant gas and hydrogen or hydrogen-containing compound through a gas purification plant before recirculating the coolant gas through the reactor. 14 claims, 1 drawing figure

  4. Short-circuit logic

    NARCIS (Netherlands)

    Bergstra, J.A.; Ponse, A.

    2010-01-01

    Short-circuit evaluation denotes the semantics of propositional connectives in which the second argument is only evaluated if the first argument does not suffice to determine the value of the expression. In programming, short-circuit evaluation is widely used. A short-circuit logic is a variant of

  5. Study on thermodynamic cycle of high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Qu Xinhe; Yang Xiaoyong; Wang Jie

    2017-01-01

    The development trend of the (very) High temperature gas-cooled reactor is to gradually increase the reactor outlet temperature. The different power conversion units are required at the different reactor outlet temperature. In this paper, for the helium turbine direct cycle and the combined cycle of the power conversion unit of the High temperature gas-cooled reactor, the mathematic models are established, and three cycle plans are designed. The helium turbine direct cycle is a Brayton cycle with recuperator, precooler and intercooler. In the combined cycle plan 1, the topping cycle is a simple Brayton cycle without recuperator, precooler and intercooler, and the bottoming cycle is based on the steam parameters (540deg, 6 MPa) recommended by Siemens. In the combined cycle plan 2, the topping cycle also is a simple Brayton cycle, and the bottoming cycle which is a Rankine cycle with reheating cycle is based on the steam parameters of conventional subcritical thermal power generation (540degC, 18 MPa). The optimization results showed that the cycle efficiency of the combined cycle plan 2 is the highest, the second is the helium turbine direct cycle, and the combined cycle plan 2 is the lowest. When the reactor outlet temperature is 900degC and the pressure ratio is 2.02, the cycle efficiency of the combined cycle plan 2 can reach 49.7%. The helium turbine direct cycle has a reactor inlet temperature above 500degC due to the regenerating cycle, so it requires a cooling circuit for the internal wall of the reactor pressure vessel. When the reactor outlet temperature increases, the increase of the pressure ratio required by the helium turbine direct cycle increases may bring some difficulties to the design and manufacture of the magnetic bearings. For the combined cycle, the reactor inlet temperature can be controlled below than 370degC, so the reactor pressure vessel can use SA533 steel without cooling the internal wall of the reactor pressure vessel. The pressure

  6. Coolant clean-up system in the primary coolant circuit for nuclear reactor

    International Nuclear Information System (INIS)

    Saito, Michio.

    1981-01-01

    Purpose: To maintain the quality of coolants at a prescribed level by distillating coolants in the primary coolant circuit for a BWR type reactor to remove impurities therefrom, taking out the condensates from the top of the distillation column and extracting impurities in a concentrated state from the bottom. Constitution: Coolant water for cooling the core is recycled by a recycling pump by way of a recycling pipeway in a reactor. The coolants extracted from an extraction pipeway connected to the recycling pipeway are fed into a distillation column, where distillation is taken place. Impurities in the coolants, that is, in-core corrosion products, fission products generated in the reactor core, etc. are separated by the distillation, concentrated and solidified in the bottom of the distillation column. While on the other hand, condensates removed with the impurities, that is, coolants cleaned-up are recycled to the coolant water for cooling the reactor core. (Moriyama, K.)

  7. Experiences with the ASDEX neutralizer plates and construction of water-cooled plates for long-pulse heating

    International Nuclear Information System (INIS)

    Rapp, H.; Niedermeyer, H.; Kornherr, M.

    1987-01-01

    After dismantling of the titanium neutralizer plates inspection yielded satisfactory status of flat areas whereas edges and curved shapes were heavily melted. At the inner plates of the lower divertor strongly focused melting and cutting was found which is caused by fast electrons. These electrons are continuously produced. The production mechanism is not yet clear but runaway processes can be excluded. With long-pulse additional heating of 6 MW/10s as planned for ASDEX in 1987, the total energy delivered to the plasma will increase by a factor of 30. Therefore new water-cooled neutralizer plates have been constructed which consist of a copper-steel compound. The construction principle and the topology of the cooling circuits is presented

  8. Load testing circuit

    DEFF Research Database (Denmark)

    2009-01-01

    A load testing circuit a circuit tests the load impedance of a load connected to an amplifier. The load impedance includes a first terminal and a second terminal, the load testing circuit comprising a signal generator providing a test signal of a defined bandwidth to the first terminal of the load...

  9. Timergenerator circuits manual

    CERN Document Server

    Marston, R M

    2013-01-01

    Timer/Generator Circuits Manual is an 11-chapter text that deals mainly with waveform generator techniques and circuits. Each chapter starts with an explanation of the basic principles of its subject followed by a wide range of practical circuit designs. This work presents a total of over 300 practical circuits, diagrams, and tables.Chapter 1 outlines the basic principles and the different types of generator. Chapters 2 to 9 deal with a specific type of waveform generator, including sine, square, triangular, sawtooth, and special waveform generators pulse. These chapters also include pulse gen

  10. CMOS circuits manual

    CERN Document Server

    Marston, R M

    1995-01-01

    CMOS Circuits Manual is a user's guide for CMOS. The book emphasizes the practical aspects of CMOS and provides circuits, tables, and graphs to further relate the fundamentals with the applications. The text first discusses the basic principles and characteristics of the CMOS devices. The succeeding chapters detail the types of CMOS IC, including simple inverter, gate and logic ICs and circuits, and complex counters and decoders. The last chapter presents a miscellaneous collection of two dozen useful CMOS circuits. The book will be useful to researchers and professionals who employ CMOS circu

  11. 30 CFR 75.601-1 - Short circuit protection; ratings and settings of circuit breakers.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit protection; ratings and settings... Trailing Cables § 75.601-1 Short circuit protection; ratings and settings of circuit breakers. Circuit breakers providing short circuit protection for trailing cables shall be set so as not to exceed the...

  12. Investigation of thermal and hydrodynamic processes in the oil transformer radiator cooling system

    OpenAIRE

    Ільїн, Сергій Віталійович

    2013-01-01

    Despite the large number of publications in the field of transformer, heat transfer and hydrodynamic processes that take place in the radiator cooling systems, lack of attention. However, for a comprehensive analysis of the entire oil circuit in the transformer, it is necessary to take into account the work of the radiator, as it was on the efficiency of removal of heat in it will depend on the oil temperature at the inlet of the transformer. To achieve these objectives, this paper describes ...

  13. Comparing Social Stories™ to Cool versus Not Cool

    Science.gov (United States)

    Leaf, Justin B.; Mitchell, Erin; Townley-Cochran, Donna; McEachin, John; Taubman, Mitchell; Leaf, Ronald

    2016-01-01

    In this study we compared the cool versus not cool procedure to Social Stories™ for teaching various social behaviors to one individual diagnosed with autism spectrum disorder. The researchers randomly assigned three social skills to the cool versus not cool procedure and three social skills to the Social Stories™ procedure. Naturalistic probes…

  14. Experimental study of film media used for evaporative pre-cooling of air

    International Nuclear Information System (INIS)

    He, Suoying; Guan, Zhiqiang; Gurgenci, Hal; Hooman, Kamel; Lu, Yuanshen; Alkhedhair, Abdullah M.

    2014-01-01

    Highlights: • Two film media were experimentally studied in a low-speed wind tunnel. • Correlations for heat transfer coefficient and pressure drop were developed. • Cellulose media provide higher cooling efficiency and pressure drop than PVC media. • Water entrainment of PVC media happens even at relatively low air velocities. - Abstract: An open-circuit low-speed wind tunnel was used to study the performance of evaporative cooling with cellulose and Polyvinyl Chloride (PVC) corrugated media. These two film media were selected as part of a broader investigation on pre-cooling the entering air of natural draft dry cooling towers. The heat and mass transfer and pressure drop across the two media with three thicknesses (i.e., 100, 200 and 300 mm) were experimentally studied in the wind tunnel. The test data were non-dimensionalized and curve fitted to yield a set of correlations. It was found that the pressure drop range of the cellulose media is 1.5–101.7 Pa while the pressure drops of the PVC media are much lower with the range of 0.9–49.2 Pa, depending on the medium thickness, air velocity and water flow rate. The cooling efficiencies of the cellulose media vary from 43% to 90% while the cooling efficiencies of the PVC media are 8% to 65%, depending on the medium thickness and air velocity. The water entrainment off the media was detected by water sensitive papers, and found that the cellulose media have negligible water entrainment under the studied conditions while care must be taken in the use of PVC media as water entrainment happens even at relatively low air velocities

  15. Tentative design basis new 100 Area water plant embodying a close cooling water circuit

    Energy Technology Data Exchange (ETDEWEB)

    1951-11-14

    The attached document includes a plot plan, flow diagram and delineation of basic assumptions upon which the report was developed. It summarizes the work which has been accomplished to date under RDA No. DC-6 in developing a recirculating water system to serve a new reactor. In order to proceed with the work under RDA No. DC-6 it has been necessary to make certain basic assumptions relative to the primary circuit requirements of RDA No. DC-3. These assumptions are explained in the report and are presented by the exhibits contained therein. Subsequent to the compilation of the basic report certain additional considerations have come to the authors attention and are included in the addendum.

  16. Film cooling for a closed loop cooled airfoil

    Science.gov (United States)

    Burdgick, Steven Sebastian; Yu, Yufeng Phillip; Itzel, Gary Michael

    2003-01-01

    Turbine stator vane segments have radially inner and outer walls with vanes extending therebetween. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. At least one film cooling hole is defined through a wall of at least one of the cavities for flow communication between an interior of the cavity and an exterior of the vane. The film cooling hole(s) are defined adjacent a potential low LCF life region, so that cooling medium that bleeds out through the film cooling hole(s) reduces a thermal gradient in a vicinity thereof, thereby the increase the LCF life of that region.

  17. Study of the mechanisms for the emergency cooling of the core of the Radioisotope Producing Reator (RPR)

    International Nuclear Information System (INIS)

    Lacerda, F.C.

    1987-01-01

    The mechanisms for the emergency cooling of the core of the Radioisotope Producing Reactor (R.P.R.) are studied, in particular the thermal-hydraulic behaviour of the coolant after reactor shut-down. The coolant operates bd convection, and flows downward through the core passing into beel-shaped plenum that encloses the core and proceeding across the primary cooling loop. When the reactor is shut-down, the coolant flow undergoes a transient period until the steady state of natural convection is reached, after which the coolant flows upwards from the lower plenum. A plocking valve will be installed at the exit of the lower plenum, which will automatically shut in case of an accident that will involve the loss of flow in the primary circuit. The present work aims at evaluating the contribution of natural convection by natural recirculation in the core when the blocking valve is close, and via the external coolant circuit when the blocking valve is open. In particular, we study the natural self-regulating mechanisms of extraction of the heat generated by the fission product after reactor shut-down. (author) [pt

  18. Heat-driven liquid metal cooling device for the thermal management of a computer chip

    Energy Technology Data Exchange (ETDEWEB)

    Ma Kunquan; Liu Jing [Cryogenic Laboratory, PO Box 2711, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)

    2007-08-07

    The tremendous heat generated in a computer chip or very large scale integrated circuit raises many challenging issues to be solved. Recently, liquid metal with a low melting point was established as the most conductive coolant for efficiently cooling the computer chip. Here, by making full use of the double merits of the liquid metal, i.e. superior heat transfer performance and electromagnetically drivable ability, we demonstrate for the first time the liquid-cooling concept for the thermal management of a computer chip using waste heat to power the thermoelectric generator (TEG) and thus the flow of the liquid metal. Such a device consumes no external net energy, which warrants it a self-supporting and completely silent liquid-cooling module. Experiments on devices driven by one or two stage TEGs indicate that a dramatic temperature drop on the simulating chip has been realized without the aid of any fans. The higher the heat load, the larger will be the temperature decrease caused by the cooling device. Further, the two TEGs will generate a larger current if a copper plate is sandwiched between them to enhance heat dissipation there. This new method is expected to be significant in future thermal management of a desk or notebook computer, where both efficient cooling and extremely low energy consumption are of major concern.

  19. Heat-driven liquid metal cooling device for the thermal management of a computer chip

    International Nuclear Information System (INIS)

    Ma Kunquan; Liu Jing

    2007-01-01

    The tremendous heat generated in a computer chip or very large scale integrated circuit raises many challenging issues to be solved. Recently, liquid metal with a low melting point was established as the most conductive coolant for efficiently cooling the computer chip. Here, by making full use of the double merits of the liquid metal, i.e. superior heat transfer performance and electromagnetically drivable ability, we demonstrate for the first time the liquid-cooling concept for the thermal management of a computer chip using waste heat to power the thermoelectric generator (TEG) and thus the flow of the liquid metal. Such a device consumes no external net energy, which warrants it a self-supporting and completely silent liquid-cooling module. Experiments on devices driven by one or two stage TEGs indicate that a dramatic temperature drop on the simulating chip has been realized without the aid of any fans. The higher the heat load, the larger will be the temperature decrease caused by the cooling device. Further, the two TEGs will generate a larger current if a copper plate is sandwiched between them to enhance heat dissipation there. This new method is expected to be significant in future thermal management of a desk or notebook computer, where both efficient cooling and extremely low energy consumption are of major concern

  20. A self-regulating valve for single-phase liquid cooling of microelectronics

    International Nuclear Information System (INIS)

    Donose, Radu; De Volder, Michaël; Peirs, Jan; Reynaerts, Dominiek

    2011-01-01

    This paper reports on the design, optimization and testing of a self-regulating valve for single-phase liquid cooling of microelectronics. Its purpose is to maintain the integrated circuit (IC) at constant temperature and to reduce power consumption by diminishing flow generated by the pump as a function of the cooling requirements. It uses a thermopneumatic actuation principle that combines the advantages of zero power consumption and small size in combination with a high flow rate and low manufacturing costs. The valve actuation is provided by the thermal expansion of a liquid (actuation fluid) which, at the same time, actuates the valve and provides feed-back sensing. A maximum flow rate of 38 kg h −1 passes through the valve for a heat load up to 500 W. The valve is able to reduce the pumping power by up to 60% and it has the capability to maintain the IC at a more uniform temperature.