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Sample records for subglacial water pressure

  1. Rapidly changing subglacial hydrological pathways at a tidewater glacier revealed through simultaneous observations of water pressure, supraglacial lakes, meltwater plumes and surface velocities

    Science.gov (United States)

    How, Penelope; Benn, Douglas I.; Hulton, Nicholas R. J.; Hubbard, Bryn; Luckman, Adrian; Sevestre, Heïdi; van Pelt, Ward J. J.; Lindbäck, Katrin; Kohler, Jack; Boot, Wim

    2017-11-01

    Subglacial hydrological processes at tidewater glaciers remain poorly understood due to the difficulty in obtaining direct measurements and lack of empirical verification for modelling approaches. Here, we investigate the subglacial hydrology of Kronebreen, a fast-flowing tidewater glacier in Svalbard during the 2014 melt season. We combine observations of borehole water pressure, supraglacial lake drainage, surface velocities and plume activity with modelled run-off and water routing to develop a conceptual model that thoroughly encapsulates subglacial drainage at a tidewater glacier. Simultaneous measurements suggest that an early-season episode of subglacial flushing took place during our observation period, and a stable efficient drainage system effectively transported subglacial water through the northern region of the glacier tongue. Drainage pathways through the central and southern regions of the glacier tongue were disrupted throughout the following melt season. Periodic plume activity at the terminus appears to be a signal for modulated subglacial pulsing, i.e. an internally driven storage and release of subglacial meltwater that operates independently of marine influences. This storage is a key control on ice flow in the 2014 melt season. Evidence from this work and previous studies strongly suggests that long-term changes in ice flow at Kronebreen are controlled by the location of efficient/inefficient drainage and the position of regions where water is stored and released.

  2. Rapidly changing subglacial hydrological pathways at a tidewater glacier revealed through simultaneous observations of water pressure, supraglacial lakes, meltwater plumes and surface velocities

    Directory of Open Access Journals (Sweden)

    P. How

    2017-11-01

    Full Text Available Subglacial hydrological processes at tidewater glaciers remain poorly understood due to the difficulty in obtaining direct measurements and lack of empirical verification for modelling approaches. Here, we investigate the subglacial hydrology of Kronebreen, a fast-flowing tidewater glacier in Svalbard during the 2014 melt season. We combine observations of borehole water pressure, supraglacial lake drainage, surface velocities and plume activity with modelled run-off and water routing to develop a conceptual model that thoroughly encapsulates subglacial drainage at a tidewater glacier. Simultaneous measurements suggest that an early-season episode of subglacial flushing took place during our observation period, and a stable efficient drainage system effectively transported subglacial water through the northern region of the glacier tongue. Drainage pathways through the central and southern regions of the glacier tongue were disrupted throughout the following melt season. Periodic plume activity at the terminus appears to be a signal for modulated subglacial pulsing, i.e. an internally driven storage and release of subglacial meltwater that operates independently of marine influences. This storage is a key control on ice flow in the 2014 melt season. Evidence from this work and previous studies strongly suggests that long-term changes in ice flow at Kronebreen are controlled by the location of efficient/inefficient drainage and the position of regions where water is stored and released.

  3. Creep and stick-slip in subglacial granular beds forced by variations in water pressure

    DEFF Research Database (Denmark)

    Damsgaard, Anders; Egholm, David Lundbek; Beem, Lucas H.

    of grain and fluid dynamics to show that rapid rearrangements of load-bearing force chains within the granular sediments drive mechanical transitions between stability and failure. Cyclic variations in driving stresses or pore-water pressure give rise to strain-rate dependent creeping motion at stress...

  4. Structure, morphology and water flux of a subglacial drainage system, Midtdalsbreen, Norway

    NARCIS (Netherlands)

    Willis, I.C.; Fitzsimmons, C.D.; Melvold, K.; Andreassen, L.M.; Giesen, R.H.|info:eu-repo/dai/nl/304831603

    2012-01-01

    Digital elevation models of the surface and bed of Midtdalsbreen, Norway are used to calculate subglacial hydraulic potential and infer drainage system structure for a series of subglacial water pressure assumptions ranging from atmospheric to ice overburden. A distributed degree-day model is used

  5. Subglacial water drainage, storage, and piracy beneath the Greenland ice sheet

    Science.gov (United States)

    Lindbäck, K.; Pettersson, R.; Hubbard, A. L.; Doyle, S. H.; As, D.; Mikkelsen, A. B.; Fitzpatrick, A. A.

    2015-09-01

    Meltwater drainage across the surface of the Greenland ice sheet (GrIS) is well constrained by measurements and modeling, yet despite its critical role, knowledge of its transit through the subglacial environment remains limited. Here we present a subglacial hydrological analysis of a land-terminating sector of the GrIS at unprecedented resolution that predicts the routing of surface-derived meltwater once it has entered the basal drainage system. Our analysis indicates the probable existence of small subglacial lakes that remain undetectable by methods using surface elevation change or radar techniques. Furthermore, the analysis suggests transient behavior with rapid switching of subglacial drainage between competing catchments driven by seasonal changes in the basal water pressure. Our findings provide a cautionary note that should be considered in studies that attempt to relate and infer future response from surface temperature, melt, and runoff from point measurements and/or modeling with measurements of proglacial discharge and ice dynamics.

  6. Stress Redistribution Explains Anti-correlated Subglacial Pressure Variations

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    Pierre-Marie Lefeuvre

    2018-01-01

    Full Text Available We used a finite element model to interpret anti-correlated pressure variations at the base of a glacier to demonstrate the importance of stress redistribution in the basal ice. We first investigated two pairs of load cells installed 20 m apart at the base of the 210 m thick Engabreen glacier in Northern Norway. The load cell data for July 2003 showed that pressurisation of a subglacial channel located over one load cell pair led to anti-correlation in pressure between the two pairs. To investigate the cause of this anti-correlation, we used a full Stokes 3D model of a 210 m thick and 25–200 m wide glacier with a pressurised subglacial channel represented as a pressure boundary condition. The model reproduced the anti-correlated pressure response at the glacier bed and variations in pressure of the same order of magnitude as the load cell observations. The anti-correlation pattern was shown to depend on the bed/surface slope. On a flat bed with laterally constrained cross-section, the resulting bridging effect diverted some of the normal forces acting on the bed to the sides. The anti-correlated pressure variations were then reproduced at a distance >10–20 m from the channel. In contrast, when the bed was inclined, the channel support of the overlying ice was vertical only, causing a reduction of the normal stress on the bed. With a bed slope of 5 degrees, the anti-correlation occurred within 10 m of the channel. The model thus showed that the effect of stress redistribution can lead to an opposite response in pressure at the same distance from the channel and that anti-correlation in pressure is reproduced without invoking cavity expansion caused by sliding.

  7. The use of magmatic water to reconstruct palaeo-ice thicknesses during subglacial rhyolitic eruptions

    Science.gov (United States)

    Owen, Jacqueline; Tuffen, Hugh; McGarvie, Dave; Pinkerton, Harry; Wilson, Lionel

    2010-05-01

    Magma degassing patterns can potentially be used to reconstruct ice thicknesses during subglacial eruptions, as the pressure dependence of water solubility in silicate melts is reasonably well constrained. The amount of water remaining in the quenched bulk glasses should record the quenching pressure, which, in a subglacial setting, will be dependent on the pressure of overlying ice and/or meltwater that was present. This reconstruction technique has been applied to several basaltic volcanoes[1]. In one study the dissolved water contents was seen to vary as a function of altitude, consistent with the presence of an ice sheet[2]. Similar techniques have been applied to a rhyolitic volcano, as described below. Bláhnúkur is a small-volume rhyolitic, subglacial volcano at Torfajökull volcano, southern Iceland[3] that erupted at ~95 ka[4]. 45 glassy lava samples were collected from a variety of elevations and lithofacies types. These samples were analysed for water content using infra-red spectroscopy (FTIR), and pressure-solubility relationships were calculated using VolatileCalc[5]. The results reveal a general decrease in water concentration with elevation, consistent with the presence of an ice sheet with a surface elevation of ~1,050 m a.s.l.. This corresponds with an ice thickness of ~450 m, consistent with the field evidence from tuyas of a similar age within the same region[6]. Furthermore, the results suggest an eruptive temperature of 850°C and 0 ppm CO2. However, not all samples agree with this overall trend. We suggest that samples with anomalously low water contents could have formed in regions where there was meltwater drainage which lowered the quenching pressure[7]. By contrast, water-rich samples could reflect intrusive formation resulting in loading by rock as well as ice[8]. Crucially though, the anomalous values are all from the same locations, suggesting that there are processes that are specifically affecting certain localities. In order to use

  8. Self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern Greenland

    Science.gov (United States)

    Jordan, Thomas M.; Cooper, Michael A.; Schroeder, Dustin M.; Williams, Christopher N.; Paden, John D.; Siegert, Martin J.; Bamber, Jonathan L.

    2017-05-01

    Subglacial roughness can be determined at a variety of length scales from radio-echo sounding (RES) data either via statistical analysis of topography or inferred from basal radar scattering. Past studies have demonstrated that subglacial terrain exhibits self-affine (power law) roughness scaling behaviour, but existing radar scattering models do not take this into account. Here, using RES data from northern Greenland, we introduce a self-affine statistical framework that enables a consistent integration of topographic-scale roughness with the electromagnetic theory of radar scattering. We demonstrate that the degree of radar scattering, quantified using the waveform abruptness (pulse peakiness), is topographically controlled by the Hurst (roughness power law) exponent. Notably, specular bed reflections are associated with a lower Hurst exponent, with diffuse scattering associated with a higher Hurst exponent. Abrupt waveforms (specular reflections) have previously been used as a RES diagnostic for basal water, and to test this assumption we compare our radar scattering map with a recent prediction for the basal thermal state. We demonstrate that the majority of thawed regions (above pressure melting point) exhibit a diffuse scattering signature, which is in contradiction to the prior approach. Self-affine statistics provide a generalised model for subglacial terrain and can improve our understanding of the relationship between basal properties and ice-sheet dynamics.

  9. MODELING OF WATER CIRCULATION IN THE ANTARCTIC SUBGLACIAL LAKE VOSTOK

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    G. V. Kazko

    2012-01-01

    Full Text Available Different ways of defining the characteristics of Antarctic subglacialLakeVostokcirculation are considered. The disadvantages of hydrodynamic models using the hydrostatic approximation exposed to analysis. Differential equations and boundary conditions of three-dimensional nonhydrostatic model in terms vorticity–vector potential, specially developed for the modelling of the lake circulation are presented. 3D model passed through the testing by means simulations of convective currents in the simple-form reservoirs. On the basis of the seismic data on the thickness of a glacier and bathimetry of the lake the computational domain approximating a water body ofLakeVostokis constructed. Some results of modeling of the convective processes in the lake, obtained at the initial stage of circulation evolution using finite-difference grid with a spatial resolution of 8000 × 1500 ×30 mare shown.

  10. A new methodology to simulate subglacial deformation of water saturated granular material

    DEFF Research Database (Denmark)

    Damsgaard, Anders; Egholm, David Lundbek; Piotrowski, Jan A.

    2015-01-01

    can cause variations in the pore-fluid pressure. The pressure variations weaken or strengthen the granular phase, and in turn influence the distribution of shear strain with depth. In permeable sediments the strain distribution is governed by the grain-size distribution and effective normal stress...... of subglacial sediment to the shear stress of an overriding glacier. In this study, we present a new methodology designed to simulate subglacial deformation using a coupled numerical model for computational experiments on grain-fluid mixtures. The granular phase is simulated on a per-grain basis by the discrete......The dynamics of glaciers are to a large degree governed by processes operating at the ice-bed interface, and one of the primary mechanisms of glacier flow over soft unconsolidated sediments is subglacial deformation. However, it has proven difficult to constrain the mechanical response...

  11. An isotopic model for basal freeze-on associated with subglacial upward flow of pore water

    Science.gov (United States)

    Souchez, R.; Samyn, D.; Lorrain, R.; Pattyn, F.; Fitzsimons, S.

    2004-01-01

    Subglacial freezing in polar glaciers can have a significant dynamical effect. Recent studies have shown that freezing of pore water flowing upward through subglacial fine-grained sediments at the freezing interface and progression of this freezing front downward are responsible for fast ice flow stoppage in ice streams. The upward pore water flow leads to the formation of debris-bearing basal ice layers. A model for stable isotope composition, both in δD and δ18O, is developed for predicting the isotopic composition of the ice segregated by such a mechanism. The development of this isotopic model for water films present along the grains of the subglacial sediment predicts the absence of apparent fractionation for the ice formed. This prediction is tested against two East Antarctic outlet glaciers by studying the δD-δ18O relationships in the basal ice layers of these glaciers.

  12. A balanced water layer concept for subglacial hydrology in large-scale ice sheet models

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    S. Goeller

    2013-07-01

    Full Text Available There is currently no doubt about the existence of a widespread hydrological network under the Antarctic Ice Sheet, which lubricates the ice base and thus leads to increased ice velocities. Consequently, ice models should incorporate basal hydrology to obtain meaningful results for future ice dynamics and their contribution to global sea level rise. Here, we introduce the balanced water layer concept, covering two prominent subglacial hydrological features for ice sheet modeling on a continental scale: the evolution of subglacial lakes and balance water fluxes. We couple it to the thermomechanical ice-flow model RIMBAY and apply it to a synthetic model domain. In our experiments we demonstrate the dynamic generation of subglacial lakes and their impact on the velocity field of the overlaying ice sheet, resulting in a negative ice mass balance. Furthermore, we introduce an elementary parametrization of the water flux–basal sliding coupling and reveal the predominance of the ice loss through the resulting ice streams against the stabilizing influence of less hydrologically active areas. We point out that established balance flux schemes quantify these effects only partially as their ability to store subglacial water is lacking.

  13. A balanced water layer concept for subglacial hydrology in large scale ice sheet models

    Science.gov (United States)

    Goeller, S.; Thoma, M.; Grosfeld, K.; Miller, H.

    2012-12-01

    There is currently no doubt about the existence of a wide-spread hydrological network under the Antarctic ice sheet, which lubricates the ice base and thus leads to increased ice velocities. Consequently, ice models should incorporate basal hydrology to obtain meaningful results for future ice dynamics and their contribution to global sea level rise. Here, we introduce the balanced water layer concept, covering two prominent subglacial hydrological features for ice sheet modeling on a continental scale: the evolution of subglacial lakes and balance water fluxes. We couple it to the thermomechanical ice-flow model RIMBAY and apply it to a synthetic model domain inspired by the Gamburtsev Mountains, Antarctica. In our experiments we demonstrate the dynamic generation of subglacial lakes and their impact on the velocity field of the overlaying ice sheet, resulting in a negative ice mass balance. Furthermore, we introduce an elementary parametrization of the water flux-basal sliding coupling and reveal the predominance of the ice loss through the resulting ice streams against the stabilizing influence of less hydrologically active areas. We point out, that established balance flux schemes quantify these effects only partially as their ability to store subglacial water is lacking.

  14. Clean hot water drilling for exploration of the Antarctic deep subglacial environment

    Science.gov (United States)

    Makinson, K.; Pearce, D.; Hodgson, D.; Bentley, M.; Smith, A.; Tranter, M.; Rose, M. C.; Ross, N.; Mowlem, M. C.; Parnell, J.; Siegert, M. J.

    2015-12-01

    Overlain by several kilometres of ice, the subglacial environments deep beneath the Antarctic Ice Sheet are regarded as extreme habitats for microbial life and repositories of important paleoclimate records. Of significant scientific interest, yet remaining largely unexplored, accessing and sampling these environments presents several challenges to existing drilling technologies. With over half of the ice sheet believed to be resting on a wet bed, much of it part of a hydrological drainage network, accessing of this environment must conform to international environmental contamination protocols. This makes hot water drilling the most viable option for clean, fast, access through thick ice. After two decades of planning, involving the development of drilling techniques for subglacial access, instrument design and logistics set up, significant progress has been made in attempts to directly access, measure, and sample subglacial lakes and sediments. Combining the experiences from the notable setbacks and successes, as well as recent field testing for this drilling technique, the most practical technical options and operational procedures for future clean entry into Subglacial Lake Ellsworth and other deep (>3000 m) access targets will be presented.

  15. Implications of sediment transport by subglacial water flow for interpreting contemporary glacial erosion rates

    Science.gov (United States)

    Beaud, Flavien; Flowers, Gwenn E.; Venditti, Jeremy G.

    2017-04-01

    The role of glaciers in landscape evolution is central to the interactions between climate and tectonic forces at high latitudes and in mountainous regions. Sediment yields from glacierized basins are used to quantify contemporary erosion rates on seasonal to decadal timescales, often under the assumption that subglacial water flow is the main contributor to these yields. Two recent studies have furthermore used such sediment fluxes to calibrate a glacial erosion rule, where erosion rate scales with ice sliding speed raised to a power greater than one. Subglacial sediment transport by water flow has however seldom been studied, thus the controls on sediment yield from glacierized basins remain enigmatic. To bridge this gap, we develop a 1-D model of morphodynamics in semi-circular bedrock-floored subglacial channels. We adapt a sediment conservation law from the fluvial literature, developed for both mixed bedrock / alluvial and alluvial conditions, to subglacial channels. Channel evolution is a function of the traditional melt-opening due to viscous heat dissipation from the water flow, and creep closure of the overlying ice, to which we add the closure or enlargement due to sediment deposition or removal, respectively. Using a simple ice geometry representing a land-terminating glacier, we find that the shear stresses produced by the water flow on the bed decrease significantly near the terminus. As the ice thins, creep closure decreases and large hydraulic potential gradients cannot be sustained. The resulting gradients in sediment transport lead to a bottleneck, and sediment accumulates if the sediment supply is adequate. A similar bottleneck occurs if a channel is well established and water discharge drops. Whether such constriction happens in space of time, in the presence of a sufficiently large sediment supply sediment accumulates temporarily near the terminus, followed shortly thereafter by enhanced sediment transport. Reduction in the cross-sectional area

  16. A lander mission to probe subglacial water on Saturn's moon Enceladus for life

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    Konstantinidis, Konstantinos; Flores Martinez, Claudio L.; Dachwald, Bernd; Ohndorf, Andreas; Dykta, Paul; Bowitz, Pascal; Rudolph, Martin; Digel, Ilya; Kowalski, Julia; Voigt, Konstantin; Förstner, Roger

    2015-01-01

    The plumes discovered by the Cassini mission emanating from the south pole of Saturn's moon Enceladus and the unique chemistry found in them have fueled speculations that Enceladus may harbor life. The presumed aquiferous fractures from which the plumes emanate would make a prime target in the search for extraterrestrial life and would be more easily accessible than the moon's subglacial ocean. A lander mission that is equipped with a subsurface maneuverable ice melting probe will be most suitable to assess the existence of life on Enceladus. A lander would have to land at a safe distance away from a plume source and melt its way to the inner wall of the fracture to analyze the plume subsurface liquids before potential biosignatures are degraded or destroyed by exposure to the vacuum of space. A possible approach for the in situ detection of biosignatures in such samples can be based on the hypothesis of universal evolutionary convergence, meaning that the independent and repeated emergence of life and certain adaptive traits is wide-spread throughout the cosmos. We thus present a hypothetical evolutionary trajectory leading towards the emergence of methanogenic chemoautotrophic microorganisms as the baseline for putative biological complexity on Enceladus. To detect their presence, several instruments are proposed that may be taken aboard a future subglacial melting probe. The "Enceladus Explorer" (EnEx) project funded by the German Space Administration (DLR), aims to develop a terrestrial navigation system for a subglacial research probe and eventually test it under realistic conditions in Antarctica using the EnEx-IceMole, a novel maneuverable subsurface ice melting probe for clean sampling and in situ analysis of ice and subglacial liquids. As part of the EnEx project, an initial concept study is foreseen for a lander mission to Enceladus to deploy the IceMole near one of the active water plumes on the moon's South-Polar Terrain, where it will search for

  17. Rock comminution as a source of hydrogen for subglacial ecosystems

    Science.gov (United States)

    Telling, J.; Boyd, E. S.; Bone, N.; Jones, E. L.; Tranter, M.; Macfarlane, J. W.; Martin, P. G.; Wadham, J. L.; Lamarche-Gagnon, G.; Skidmore, M. L.; Hamilton, T. L.; Hill, E.; Jackson, M.; Hodgson, D. A.

    2015-11-01

    Substantial parts of the beds of glaciers, ice sheets and ice caps are at the pressure melting point. The resulting water harbours diverse subglacial microbial ecosystems capable of affecting global biogeochemical cycles. Such subglacial habitats may have acted as refugia during Neoproterozoic glaciations. However, it is unclear how life in subglacial environments could be supported during glaciations lasting millions of years because energy from overridden organic carbon would become increasingly depleted. Here we investigate the potential for abiogenic H2 produced during rock comminution to provide a continual source of energy to support subglacial life. We collected a range of silicate rocks representative of subglacial environments in Greenland, Canada, Norway and Antarctica and crushed them with a sledgehammer and ball mill to varying surface areas. Under an inert atmosphere in the laboratory, we added water, and measured H2 production with time. H2 was produced at 0 °C in all silicate-water experiments, probably through the reaction of water with mineral surface silica radicals formed during rock comminution. H2 production increased with increasing temperature or decreasing silicate rock grain size. Sufficient H2 was produced to support previously measured rates of methanogenesis under a Greenland glacier. We conclude that abiogenic H2 generation from glacial bedrock comminution could have supported life and biodiversity in subglacial refugia during past extended global glaciations.

  18. Stable water isotopic composition of the Antarctic subglacial Lake Vostok: implications for understanding the lake's hydrology.

    Science.gov (United States)

    Ekaykin, Alexey A; Lipenkov, Vladimir Y; Kozachek, Anna V; Vladimirova, Diana O

    2016-01-01

    We estimated the stable isotopic composition of water from the subglacial Lake Vostok using two different sets of samples: (1) water frozen on the drill bit immediately after the first lake unsealing and (2) water frozen in the borehole after the unsealing and re-drilled one year later. The most reliable values of the water isotopic composition are: -59.0 ± 0.3 ‰ for oxygen-18, -455 ± 1 ‰ for deuterium and 17 ± 1 ‰ for d-excess. This result is also confirmed by the modelling of isotopic transformations in the water which froze in the borehole, and by a laboratory experiment simulating this process. A comparison of the newly obtained water isotopic composition with that of the lake ice (-56.2 ‰ for oxygen-18, -442.4 ‰ for deuterium and 7.2 ‰ for d-excess) leads to the conclusion that the lake ice is very likely formed in isotopic equilibrium with water. In turn, this means that ice is formed by a slow freezing without formation of frazil ice crystals and/or water pockets. This conclusion agrees well with the observed physical and chemical properties of the lake's accreted ice. However, our estimate of the water's isotopic composition is only valid for the upper water layer and may not be representative for the deeper layers of the lake, so further investigations are required.

  19. Direct observations of evolving subglacial drainage beneath the Greenland Ice Sheet.

    Science.gov (United States)

    Andrews, Lauren C; Catania, Ginny A; Hoffman, Matthew J; Gulley, Jason D; Lüthi, Martin P; Ryser, Claudia; Hawley, Robert L; Neumann, Thomas A

    2014-10-02

    Seasonal acceleration of the Greenland Ice Sheet is influenced by the dynamic response of the subglacial hydrologic system to variability in meltwater delivery to the bed via crevasses and moulins (vertical conduits connecting supraglacial water to the bed of the ice sheet). As the melt season progresses, the subglacial hydrologic system drains supraglacial meltwater more efficiently, decreasing basal water pressure and moderating the ice velocity response to surface melting. However, limited direct observations of subglacial water pressure mean that the spatiotemporal evolution of the subglacial hydrologic system remains poorly understood. Here we show that ice velocity is well correlated with moulin hydraulic head but is out of phase with that of nearby (0.3-2 kilometres away) boreholes, indicating that moulins connect to an efficient, channelized component of the subglacial hydrologic system, which exerts the primary control on diurnal and multi-day changes in ice velocity. Our simultaneous measurements of moulin and borehole hydraulic head and ice velocity in the Paakitsoq region of western Greenland show that decreasing trends in ice velocity during the latter part of the melt season cannot be explained by changes in the ability of moulin-connected channels to convey supraglacial melt. Instead, these observations suggest that decreasing late-season ice velocity may be caused by changes in connectivity in unchannelized regions of the subglacial hydrologic system. Understanding this spatiotemporal variability in subglacial pressures is increasingly important because melt-season dynamics affect ice velocity beyond the conclusion of the melt season.

  20. Greenland subglacial drainage evolution regulated by weakly connected regions of the bed.

    Science.gov (United States)

    Hoffman, Matthew J; Andrews, Lauren C; Price, Stephen A; Catania, Ginny A; Neumann, Thomas A; Lüthi, Martin P; Gulley, Jason; Ryser, Claudia; Hawley, Robert L; Morriss, Blaine

    2016-12-19

    Penetration of surface meltwater to the bed of the Greenland Ice Sheet each summer causes an initial increase in ice speed due to elevated basal water pressure, followed by slowdown in late summer that continues into fall and winter. While this seasonal pattern is commonly explained by an evolution of the subglacial drainage system from an inefficient distributed to efficient channelized configuration, mounting evidence indicates that subglacial channels are unable to explain important aspects of hydrodynamic coupling in late summer and fall. Here we use numerical models of subglacial drainage and ice flow to show that limited, gradual leakage of water and lowering of water pressure in weakly connected regions of the bed can explain the dominant features in late and post melt season ice dynamics. These results suggest that a third weakly connected drainage component should be included in the conceptual model of subglacial hydrology.

  1. Modeling of subglacial hydrological development following rapid supraglacial lake drainage

    Science.gov (United States)

    Dow, C. F.; Kulessa, B.; Rutt, I. C.; Tsai, V. C.; Pimentel, S.; Doyle, S. H.; van As, D.; Lindbäck, K.; Pettersson, R.; Jones, G. A.; Hubbard, A.

    2015-06-01

    The rapid drainage of supraglacial lakes injects substantial volumes of water to the bed of the Greenland ice sheet over short timescales. The effect of these water pulses on the development of basal hydrological systems is largely unknown. To address this, we develop a lake drainage model incorporating both (1) a subglacial radial flux element driven by elastic hydraulic jacking and (2) downstream drainage through a linked channelized and distributed system. Here we present the model and examine whether substantial, efficient subglacial channels can form during or following lake drainage events and their effect on the water pressure in the surrounding distributed system. We force the model with field data from a lake drainage site, 70 km from the terminus of Russell Glacier in West Greenland. The model outputs suggest that efficient subglacial channels do not readily form in the vicinity of the lake during rapid drainage and instead water is evacuated primarily by a transient turbulent sheet and the distributed system. Following lake drainage, channels grow but are not large enough to reduce the water pressure in the surrounding distributed system, unless preexisting channels are present throughout the domain. Our results have implications for the analysis of subglacial hydrological systems in regions where rapid lake drainage provides the primary mechanism for surface-to-bed connections.

  2. Subglacial sediment mechanics investigated by computer simulation of granular material

    Science.gov (United States)

    Damsgaard, A.; Egholm, D. L.; Tulaczyk, S. M.; Piotrowski, J. A.; Larsen, N. K.; Siegfried, M. R.; Beem, L.; Suckale, J.

    2016-12-01

    The mechanical properties of subglacial sediments are known to directly influence the stability of ice streams and fast-moving glaciers, but existing models of granular sediment deformation are poorly constrained. In addition, upscaling to generalized mathematical models is difficult due to the mechanical nonlinearity of the sediment, internal porosity changes during deformation, and associated structural and kinematic phase transitions. In this presentation, we introduce the Discrete Element Method (DEM) for particle-scale granular simulation. The DEM is fully coupled with fluid dynamics. The numerical method is applied to better understand the mechanical properties of the subglacial sediment and its interaction with meltwater. The computational approach allows full experimental control and offers insights into the internal kinematics, stress distribution, and mechanical stability. During confined shear with variable pore-water pressure, the sediment changes mechanical behavior, from stick, to non-linear creep, and unconstrained failure during slip. These results are contrary to more conventional models of plastic or (non-)linear viscous subglacial soft-bed sliding. Advection of sediment downstream is pressure dependent, which is consistent with theories of unstable bed bump growth. Granular mechanics prove to significantly influence the geometry and hydraulic properties of meltwater channels incised into the subglacial bed. Current models assume that channel bed erosion is balanced by linear-viscous sediment movement. We demonstrate how channel flanks are stabilized by the sediment frictional strength. Additionally, sediment liquefaction proves to be a possible mechanism for causing large and episodic sediment transport by water flow. Though computationally intense, our coupled numerical method provides a framework for quantifying a wide range of subglacial sediment-water processes, which are a key unknown in our ability to model the future evolution of ice

  3. Incorporating modelled subglacial hydrology into inversions for basal drag

    Directory of Open Access Journals (Sweden)

    C. P. Koziol

    2017-12-01

    Full Text Available A key challenge in modelling coupled ice-flow–subglacial hydrology is initializing the state and parameters of the system. We address this problem by presenting a workflow for initializing these values at the start of a summer melt season. The workflow depends on running a subglacial hydrology model for the winter season, when the system is not forced by meltwater inputs, and ice velocities can be assumed constant. Key parameters of the winter run of the subglacial hydrology model are determined from an initial inversion for basal drag using a linear sliding law. The state of the subglacial hydrology model at the end of winter is incorporated into an inversion of basal drag using a non-linear sliding law which is a function of water pressure. We demonstrate this procedure in the Russell Glacier area and compare the output of the linear sliding law with two non-linear sliding laws. Additionally, we compare the modelled winter hydrological state to radar observations and find that it is in line with summer rather than winter observations.

  4. Exploration of Subglacial Lake Ellsworth

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    Ross, N.

    2012-12-01

    Antarctic subglacial lakes are thought to be extreme habitats for microbial life and may contain important records of ice sheet history within their lake-floor sediments. To find if this is true, and to answer the science questions that would follow, direct measurement and sampling of these environments is required. Ever since the water depth of Vostok Subglacial Lake in East Antarctica was shown to be >500 m, attention has been given to how these unique, ancient and pristine subglacial environments may be entered without contamination and adverse disturbance. Several organizations have offered guidelines on the desirable cleanliness and sterility requirements for direct sampling experiments, including the US National Academy of Sciences and the Scientific Committee on Antarctic Research. The aims, design and implementation of subglacial lake access experiments have direct relevance for the exploration of extra-terrestrial ice-covered bodies (e.g. Europa) and the search for microbial life elsewhere in the Solar System. This presentation summarizes the scientific protocols and methods being developed for the exploration of Ellsworth Subglacial Lake in West Antarctica, and provides an up-to-date summary of the status of the project. The proposed exploration, planned for December 2012, involves accessing the lake using a hot-water drill and deploying a sampling probe and sediment corer to allow in situ measurement and sample collection. Details are presented on how this can be undertaken with minimal environmental impact that maximizes scientific return without compromising the environment for future experiments. The implications of this experiment for the search for extra-terrestrial life will be discussed.

  5. Subglacial lake matters: piracy on a divide between thawed and frozen bed

    Science.gov (United States)

    Carter, S. P.; Bougamont, M. H.; Christoffersen, P.; Fricker, H. A.; Lipscomb, W. H.; Price, S. F.

    2011-12-01

    The two most populated active subglacial lake districts in Antarctica, upper Kamb Ice Stream and lower Whillans Ice Stream, occur along boundaries between where temperature models predict net basal freezing and net basal accretion. This occurs in part due to a basal traction contrast, which creates a ridge in the ice surface and creates a pressure seal; this impedes the downstream movement of water until a subglacial lake flood occurs. Here we use a model for basal water routing, which incorporates subglacial floods and a realistic term for effective pressure, to explore the ability of these floods to provide water to areas of net basal accretion and thus maintain basal lubrication. We hypothesize that these floods can distribute sufficient water to most of the regions experiencing net basal freezing; the exception being those nearest to the lakes themselves, Discharge in these regions likely occurs via narrow subglacial conduits. Over time this will cause ice downstream of the dam to thicken and pre-flood lake levels to increase until water ultimately exits the lake via an alternate route i.e. water piracy. Once piracy occurs, water is no longer supplied along the former flowpath and ice stream shutdown accelerates. We conclude that the formation and quasi-periodic flooding of lakes at the basal melt/ basal freezing boundary is a critical process in accelerating ice stream shutdown.

  6. A confined-unconfined aquifer model for subglacial hydrology

    Science.gov (United States)

    Beyer, Sebastian; Kleiner, Thomas; Humbert, Angelika

    2017-04-01

    Modeling the evolution of subglacial channels underneath ice sheets is an urgent need for ice sheet modellers, as channels affect sliding velocities and hence ice discharge. Owing to very limited observations of the subglacial hydraulic system, the development of physical models is quite restricted. Subglacial hydrology models are currently taking two different approaches: either modeling the development of a network of individual channels or modeling an equivalent porous layer where the channels are not resolved individually but modeled as a diffusive process, adjusted to reproduce the characteristic of an efficient system. Here, we use the latter approach, improving it by using a confined-unconfined aquifer model (CUAS), that allows the system to run dry in absence of sufficient water input. This ensures physical values for the water pressure. Channels are represented by adjusting the permeability and storage of the system according to projected locations of channels. The evolution of channel positions is governed by a reduced complexity model that computes channel growths according to simple rules (weighted random walks descending the hydraulic potential). As a proof of concept we present the results of the evolution of the hydrological system over time for a simple artificial glacier geometry.

  7. Advances in modelling subglacial lakes and their interaction with the Antarctic ice sheet.

    Science.gov (United States)

    Pattyn, Frank; Carter, Sasha P; Thoma, Malte

    2016-01-28

    Subglacial lakes have long been considered hydraulically isolated water bodies underneath ice sheets. This view changed radically with the advent of repeat-pass satellite altimetry and the discovery of multiple lake discharges and water infill, associated with water transfer over distances of more than 200 km. The presence of subglacial lakes also influences ice dynamics, leading to glacier acceleration. Furthermore, subglacial melting under the Antarctic ice sheet is more widespread than previously thought, and subglacial melt rates may explain the availability for water storage in subglacial lakes and water transport. Modelling of subglacial water discharge in subglacial lakes essentially follows hydraulics of subglacial channels on a hard bed, where ice sheet surface slope is a major control on triggering subglacial lake discharge. Recent evidence also points to the development of channels in deformable sediment in West Antarctica, with significant water exchanges between till and ice. Most active lakes drain over short time scales and respond rapidly to upstream variations. Several Antarctic subglacial lakes exhibit complex interactions with the ice sheet due to water circulation. Subglacial lakes can therefore-from a modelling point of view-be seen as confined small oceans underneath an imbedded ice shelf. © 2015 The Author(s).

  8. Geoethical Approach to Antarctic Subglacial Lakes Exploration

    Science.gov (United States)

    Talalay, Pavel; Markov, Alexey; Sysoev, Mikhail

    2014-05-01

    Antarctic subglacial aquatic environment have become of great interest to the science community because they may provide unique information about microbial evolution, the past climate of the Earth, and the formation of the Antarctic ice sheet. Nowadays it is generally recognized that a vast network of lakes, rivers, and streams exists thousands of meters beneath Antarctic Ice Sheets. Up to date only four boreholes accessed subglacial aquatic system but three of them were filled with high-toxic drilling fluid, and the subglacial water was contaminated. Two recent exploration programs proposed by UK and USA science communities anticipated direct access down to the lakes Ellsworth and Whillans, respectively, in the 2012/2013 Antarctic season. A team of British scientists and engineers engaged in the first attempt to drill into Lake Ellsworth but failed. US research team has successfully drilled through 800 m of Antarctic ice to reach a subglacial lake Whillans and retrieve water and sediment samples. Both activities used hot-water drilling technology to access lakes. Hot water is considered by the world science community as the most clean drilling fluid medium from the present point of view but it cannot solve environmental problems in total because hot-water even when heated to 90 °C, filtered to 0.2 μm, and UV treated at the surface could pick up microorganisms from near-surface snow and circulate them in great volume through the borehole. Another negative impact of hot-water circulation medium is thermal pollution of subglacial water. The new approach to Antarctic subglacial lakes exploration is presented by sampling technology with recoverable autonomous sonde which is equipped by two hot-points with heating elements located on the bottom and top sides of the sonde. All down-hole sonde components will be sterilized by combination of chemical wash, HPV and UV sterilization prior using. At the beginning of the summer season sonde is installed on the surface of the

  9. Probe technologies for clean sampling and measurement of subglacial lakes.

    Science.gov (United States)

    Mowlem, Matt; Saw, Kevin; Brown, Robin; Waugh, Edward; Cardwell, Christopher L; Wyatt, James; Magiopoulos, Iordanis; Keen, Peter; Campbell, Jon; Rundle, Nicholas; Gkritzalis-Papadopoulos, Athanasios

    2016-01-28

    It is 4 years since the subglacial lake community published its plans for accessing, sampling, measuring and studying the pristine, and hitherto enigmatic and very different, Antarctic subglacial lakes, Vostok, Whillans and Ellsworth. This paper summarizes the contrasting probe technologies designed for each of these subglacial environments and briefly updates how these designs changed or were used differently when compared to previously published plans. A detailed update on the final engineering design and technical aspects of the probe for Subglacial Lake Ellsworth is presented. This probe is designed for clean access, is negatively buoyant (350 kg), 5.2 m long, 200 mm in diameter, approximately cylindrical and consists of five major units: (i) an upper power and communications unit attached to an optical and electrical conducting tether, (ii)-(iv) three water and particle samplers, and (v) a sensors, imaging and instrumentation pack tipped with a miniature sediment corer. To date, only in Subglacial Lake Whillans have instruments been successfully deployed. Probe technologies for Subglacial Lake Vostok (2014/15) and Lake Ellsworth (2012/13) were not deployed for technical reasons, in the case of Lake Ellsworth because hot-water drilling was unable to access the lake during the field season window. Lessons learned and opportunities for probe technologies in future subglacial access missions are discussed. © 2015 The Author(s).

  10. Antarctic subglacial lakes drain through sediment-floored canals: theory and model testing on real and idealized domains

    Science.gov (United States)

    Carter, Sasha P.; Fricker, Helen A.; Siegfried, Matthew R.

    2017-02-01

    Over the past decade, satellite observations of ice surface height have revealed that active subglacial lake systems are widespread under the Antarctic Ice Sheet, including the ice streams. For some of these systems, additional observations of ice-stream motion have shown that lake activity can affect ice-stream dynamics. Despite all this new information, we still have insufficient understanding of the lake-drainage process to incorporate it into ice-sheet models. Process models for drainage of ice-dammed lakes based on conventional R-channels incised into the base of the ice through melting are unable to reproduce the timing and magnitude of drainage from Antarctic subglacial lakes estimated from satellite altimetry given the low hydraulic gradients along which such lakes drain. We have developed an alternative process model, in which channels are mechanically eroded into the underlying deformable subglacial sediment. When applied to the known active lakes of the Whillans-Mercer ice-stream system, the model successfully reproduced both the inferred magnitudes and recurrence intervals of lake-volume changes, derived from Ice, Cloud and land Elevation Satellite (ICESat) laser altimeter data for the period 2003-2009. Water pressures in our model changed as the flood evolved: during drainage, water pressures initially increased as water flowed out of the lake primarily via a distributed system, then decreased as the channelized system grew, establishing a pressure gradient that drew water away from the distributed system. This evolution of the drainage system can result in the observed internal variability of ice flow over time. If we are correct that active subglacial lakes drain through canals in the sediment, this mechanism also implies that active lakes are typically located in regions underlain by thick subglacial sediment, which may explain why they are not readily observed using radio-echo-sounding techniques.

  11. Subglacial hydrology of the lake district ice lobe during the Younger Dryas (ca. 12 500 - 11 600 years ago) in the Kylaeniemi area, SE Finland

    Energy Technology Data Exchange (ETDEWEB)

    Lunkka, J. P.; Moisio, K.; Vainio, A. [Univ. of Oulu (Finland)

    2013-07-15

    It is essential to gain knowledge on the subglacial hydrological conditions at the glacier bed / bedrock interface when assessing how bedrock fracture zones affect subglacial melt water flow and in which subglacial zones pressurized and oxygen-rich melt water penetrates into the bedrock fracture systems. In the warm-based glacier zones, a part of subglacial melt water will penetrate deep into the fracture systems although the major part of melt water is drained to and beyond the ice margin via subglacial tunnel networks especially in the areas where ice is flowing on the crystalline bedrock. During the last deglaciation phase of the former Scandinavian Ice Sheet, glaciofluvial accumulations were deposited and these sediment accumulations are highly important when picturing the subglacial hydrology of different ice streams during deglaciation in the crystalline bedrock area. The aim of the present work was to map the bedrock fracture zones in the Kylaeniemi area and to shed light on the subglacial hydrology of the Scandinavian Ice Sheet's Lake District Ice Stream that occupied the Kylaeniemi area during the Younger Dryas between ca. 12 500 - 11 600 years ago. The special emphasis within this general aim was to study the relationship between bedrock fracture zones and the routes of subglacial drainage paths. The methods used to map and study bedrock fracture zones and subglacial drainage paths included remotes sensing methods, field observations, ground penetrating radar (GPR) investigations and GIS-based reconstructions. Conventional geological field methods aided by the GPR-method were also used to map bedrock exposures and their structures and to define the type of glaciofluvial sediments and glaciofluvial landform associations. Two main fracture zone sets occur in the study area. The most prominent bedrock fracture zone set trends NW-SE while the other, less prominent fracture zone set is aligned in NE-SW direction. The majority of the minor joint sets in

  12. Water Pressure. Water in Africa.

    Science.gov (United States)

    Garrett, Carly Sporer

    The Water in Africa Project was realized over a 2-year period by a team of Peace Corps volunteers. As part of an expanded, detailed design, resources were collected from over 90 volunteers serving in African countries, photos and stories were prepared, and standards-based learning units were created for K-12 students. This unit, "Water…

  13. Modeling Subglacial Permafrost Evolution

    Science.gov (United States)

    Koutnik, M. R.; Marshall, S.

    2002-12-01

    Permanently frozen ground was present both beneath and peripheral to the Quaternary ice sheets. In areas where the ice sheet grew or advanced over permafrost, the ice sheet insulated the ground, leading to subglacial permafrost degradation. This has created distinct signatures of ice sheet occupation in the Canadian north and in Alaska during the last glacial period, with greatly diminished permafrost thickness in regions that were ice covered for an extended period. In contrast, areas peripheral to the ice sheet, including the Midwest United States, were cooled by the glacial climate conditions and the regional cooling influence of the ice sheet, leading to permafrost growth. We have developed a sub- and proglacial diffusion based permafrost model that utilizes a logarithmic grid transformation to more efficiently track the changing depth of permafrost with time. This model is coupled with the ice sheet thermodynamic model of Marshall and Clarke [1997a] to explore the geologic signatures of the last glacial cycle in North America. This offers the potential for new constraints on modeled ice sheet history. Preliminary model runs show that the overlying ice sheet has a significant effect on the underlying and peripheral permafrost degradation and formation. Subglacial permafrost is also important because its evolution influences the basal temperature of the ice sheet, critical for evolution of subglacial hydrology and fast flow instabilities (e.g. ice streams). We present results of permafrost conditions under the last glacial maximum ice sheet and the effect of permafrost on basal temperature evolution through the last glacial cycle in North America. Marshall, S. J. and G. K. C. Clarke, 1997a. J. Geophys. Res., 102 (B9), 20,599-20,614.

  14. Tracking seasonal subglacial drainage evolution of alpine glaciers using radiogenic Nd and Sr isotope systematics: Lemon Creek Glacier, Alaska

    Science.gov (United States)

    Clinger, A. E.; Aciego, S.; Stevenson, E. I.; Arendt, C. A.

    2014-12-01

    The transport pathways of water beneath a glacier are subject to change as melt seasons progress due to variability in the balance between basal water pressure and water flux. Subglacial hydrology has been well studied, but the understanding of spatial distribution is less well constrained. Whereas radiogenic isotopic tracers have been traditionally used as proxies to track spatial variability and weathering rates in fluvial and riverine systems, these techniques have yet to be applied extensively to the subglacial environment and may help resolve ambiguity in subglacial hydrology. Research has shown the 143Nd/144Nd values can reflect variation in source provenance processes due to variations in the age of the continental crust. Correlating the 143Nd/144Nd with other radiogenic isotope systematics such as strontium (87Sr/86Sr) provides important constraints on the role of congruent and incongruent weathering processes. Our study presents the application of Nd and Sr systematics using isotopic ratios to the suspended load of subglacial meltwater collected over a single melt season at Lemon Creek Glacier, USA (LCG). The time-series data show an average ɛNd ~ -6.83, indicating a young bedrock (~60 MYA). Isotopic variation helps track the seasonal expansion of the subglacial meltwater channels and subsequent return to early season conditions due to the parabolic trend towards less radiogenic Nd in June and towards more radiogenic Nd beginning in mid-August. However, the high variability in July and early August may reflect a mixture of source as the channels diverge and derive sediment from differently aged lithologies. We find a poor correlation between 143Nd/144Nd and 87Sr/86Sr (R2= 0.38) along with a slight trend towards more radiogenic 87Sr/86Sr values with time ((R2= 0.49). This may indicate that, even as the residence time decreases over the melt season, the LCG subglacial system is relatively stable and that the bedrock is congruently weathered. Our study

  15. Physiography and tectonic setting of the subglacial lake district between Vostok and Belgica subglacial highlands (Antarctica)

    Science.gov (United States)

    Tabacco, I. E.; Cianfarra, P.; Forieri, A.; Salvini, F.; Zirizotti, A.

    2006-06-01

    We present the interpretation of 11 radio echo-sounding (RES) missions carried out over the Vostok-Dome Concordia region during the Italian Antarctic expeditions in the period 1995-2001. The extension and the density of the radar data in the surveyed area allowed to reconstruct a reliable subglacial morphology and to identify four relevant morphological structures namely: the Aurora trench, the Concordia trench, the Concordia ridge and the South Hills. These structures show evidence compatible with the presence of tectonic features. Morphological considerations indicate their development in Cenozoic time. Hybrid cellular automata (HCA)-based numerical modelling allowed to justify a possible role played by the tectonics of the Aurora and Concordia trench evolution. This was accomplished by matching the bed profiles along opportunely projected sections with the modelled surfaces as derived by the activity of normal faults with variable surfaces within the continental crust. The Vostok-Dome C region is characterized by a large number of subglacial lakes. From the analysis of basal reflected power echo, we identified 14 new lakes and obtained information about their physiography as well as their possible relations with tectonics. We propose a grouping of subglacial lakes on the base of their physiography and geological setting, namely relief lakes, basin lakes and trench lakes. Relief lakes located in the Belgica subglacial highlands and are characterized by sharp and steep symmetric edges, suggesting a maximum water depth of the order of 100 m. Their origin may well relate to localized, positive geothermal flux anomalies. Basin lakes located in the Vincennes subglacial basin and are characterized by wider dimension that allow the development of well-defined, flat ice surface anomalies. Trench lakes characterize the Aurora and Concordia trenches as the possible effect of normal fault activity.

  16. Analysis of subglacial hydrodynamics and ice dynamics through combined terrestrial laser scanning and ground penetrating radar survey

    Science.gov (United States)

    Gabbud, Chrystelle; Rüttimann, Sébastien; Micheletti, Natan; Irving, James; Lane, Stuart

    2015-04-01

    This study shows how high resolution surveys of subglacial channel morphology combined with high resolution terrestrial laser scanner survey of an Alpine glacier help to understand subglacial hydrological forcing of ice dynamics. The study area is the Haut Glacier d'Arolla in Switzerland, an Alpine valley glacier for which subglacial drainage system has been well studied. A new generation of terrestrial laser scanners was used to investigate glacier surface ablation and other elements of glacial hydrodynamics at exceptionally high spatial and temporal resolution. The LiDAR RIEGL VZ-6000 scanner, with a laser 3B specifically designed for measurements of snow and ice cover surfaces, was tested at seasonal and daily scales. The data revealed spatial variations in the patterns of surface melt, controlled by both aspect and differential debris cover at the seasonal scale, and controlled by ogive-related differences in ice surface debris content at the daily scale. More tentatively, intra-daily scale measurements pointed to possible hydraulic jacking of the glacier associated with short-term water pressure rises at the downstream part of the glacier. A ground-penetrating radar (GPR) field campaign was conducted a year later in the location where possible hydraulic jacking had been detected previously. The aims of this campaign were (i) to assess GPR usage for subglacial channel detection; (ii) identify more precisely the channel morphology; and (iii) investigate further the hydraulic jacking hypothesis. 100 MHz antennas were used to map a 240 x 34 m area near the glacier snout where the ice thickness did not exceed 50 m. The corresponding data, after processing, allowed reconstruction of the bed topography and the morphology of subglacial channels in 3D, showing two of the latter in this area. One channel was followed for approximately 20 m upglacier and corresponding morphology estimates were performed. These data allowed for 3D reconstructions of both the bed

  17. PROSPECTS FOR LIFE IN THE SUBGLACIAL LAKE VOSTOK, EAST ANTARCTICA

    Directory of Open Access Journals (Sweden)

    S. A. Bulat

    2012-01-01

    Full Text Available The objective was to estimate the genuine microbial content of ice samples from refrozen water (accretion ice from the subglacialLakeVostok(Antarctica buried beneath the 4-km thick East Antarctic ice sheet as well as surface snow nearby Vostok station. The lake ice samples were extracted by heavy deep ice drilling from3764 mbelow the surface reaching the depth3769.3 mby February 2011 (lake entering. High pressure, an ultra low carbon and chemical content, isolation, complete darkness and the probable excess of oxygen in water for millions of years characterize this extreme environment. A decontamination protocol was first applied to samples selected for the absence of cracks to remove the outer part contaminated by handling and drilling fluid. Preliminary indications showed the accretion ice samples to be almost gas free with the very low impurity content. Flow cytometry showed the very low unevenly distributed biomass in both accretion (0–19 cells per ml and glacier (0–24 cells per ml ice and surface snow (0–0.02 cells per ml as well while repeated microscopic observations were unsuccessful meaning that the whole Central East Antarctic ice sheet seems to be microbial cell-free.We used strategies of Ancient DNA research that include establishing contaminant databases and criteria to validate the amplification results. To date, positive results that passed the artifacts and contaminant databases have been obtained for a few bacterial phylotypes only in accretion ice samples featured by some bedrock sediments. Amongst them are the chemolithoautotrophic thermophile Hydrogenophilus thermoluteolus of beta-Proteobacteria, the actinobacterium rather related (95% to Ilumatobacter luminis and one unclassified phylotype distantly related (92% to soil-inhabiting uncultured bacteria. Combined with geochemical and geophysical considerations, our results suggest the presence of a deep biosphere, possibly thriving within some active faults of the bedrock

  18. Seismicity and Subglacial Hydrological Processes During Early Melt Season, Engabreen, Norway

    Science.gov (United States)

    Moore, P. L.; Winberry, J.; Christianson, K.; Iverson, N. R.; Anandakrishnan, S.; Jackson, M.; Cohen, D. O.

    2012-12-01

    A broad array of mechanical and seismic instrumentation was deployed during May 2011 in subglacial tunnels beneath Engabreen, an outlet glacier of the Svartisen ice cap in northern Norway. Following a warm spell, increased melt supply to the glacier bed prompted several episodes of transient ice uplift and establishment of a more efficient basal hydraulic system. In each event, hydrological adjustment was accompanied by three distinct seismic sources, two of which have not been previously documented in glacial environments. High-frequency impulsive events with dominant Rayleigh-wave energy increased their rate-of-occurrence immediately prior to an abrupt change in basal water pressure and normal stress. These events are inferred represent propagation of water-filled crevasses permitting meltwater access to the bed. Ultra-long period (ULP, hydraulic jacking. During recovery of basal water pressure, vertical ULP deflections were correlated with increases in basal water flux and doubling of local subglacial seismic noise. The increase in seismic noise may represent turbulent flow and bedload sediment transport through newly-opened subglacial meltwater passages. The vertical ULP signal therefore likely reflects meltwater-forced uplift of ice. Surprisingly, although there was direct evidence that jacking activated frictional slip at the bed, there was no clear seismic expression of slip. Thus, broadband seismometers appear to have captured the transit of meltwater through crevasses, into isolated pockets at the glacier bed and then, by promoting ice uplift, draining though newly-established meltwater passages along the bed. Similar seismic sources could be detected elsewhere with strategically-located broadband seismic instrumentation, providing a means of remotely monitoring the hydrological processes that control ice motion.

  19. Subglacial till formation: Microscale processes within the subglacial shear zone

    Science.gov (United States)

    Hart, Jane K.

    2017-08-01

    This was a study of subglacial deformation till genesis from a modern temperate glacier, at Skálafellsjökull, Iceland. Detailed microscale properties of till samples (from Scanning Electron Microscope [SEM] and thin section analysis) were examined from a glacial site with in situ subglacial process monitoring and an exposed subglacial surface in the foreland. Two lithofacies were examined, a grey sandy till derived from the ash and basalt, and a silty reddish brown till derived from oxidized paleosols and/or tephra layers. These also represented a clay-content continuum from low (0.3%) to high (22.3%). The evolution from debris to subglacial till was investigated. This included a reduction in grain-size (21% for grey lithology, 13% reddish brown lithology), and reduction in rounding (RA) (32% for the grey lithology, 26% for the reddish brown lithology), and the quantification and analysis of the different grain erosion/comminution processes in the resultant till. It was shown that the microstructures within a till were dependent on shear strain and glaciological conditions (deformation history). The low clay content tills were dominated by linear structures (lineations and boudins, and anisotropic microfabric) whilst the higher clay content tills were dominated by rotational structures (turbates and plaster, and isotropic microfabric). These results are important in our understanding of the formation of both modern and Quaternary tills and informs our reconstruction of past glacial dynamics.

  20. Subglacial hydrological modelling of a rapid lake drainage event on the Russell Glacier catchment, SW Greenland

    Science.gov (United States)

    Dow, C. F.; Pimentel, S.; Doyle, S. H.; Booth, A. D.; Fitzpatrick, A.; Jones, G. A.; Kulessa, B.; Hubbard, A.

    2011-12-01

    We use local-scale subglacial hydrological models to assess the development of the basal drainage system in response to a rapid lake-tapping event on the Russell Glacier catchment, SW Greenland. Water inputs to the model are constrained by in-situ records of the lake drainage rate. Subglacial conditions are estimated from active seismic line analysis including basal topography and substrate characteristics. A borehole slug test model is used to determine the radial flux of water from the drainage input point. Water flowing in the downstream direction is used to drive a 1-D flowband model, which allows development of interacting channelised and distributed drainage systems. The simulated basal water pressures are applied to an elastic beam model to assess vertical uplift at the lake drainage site. Modelled uplift outputs are compared with results from GPS stations located next to the lake. Initial modelling results suggest that channels are necessary for evacuation of water from rapid lake drainage events, even with the presence of a sediment-based bed, the latter of which is usually associated with distributed drainage.

  1. The Subglacial Access and Fast Ice Research Experiment (SAFIRE): 1. Borehole-based englacial and subglacial measurements from a rapidly-moving tidewater glacier: Store Glacier, Greenland

    Science.gov (United States)

    Hubbard, Bryn; Doyle, Samuel; Christoffersen, Poul; Young, Tun Jan; Hofstede, Coen; Hubbard, Alun; Box, Jason; Todd, Joe; Bougamont, Marion

    2016-04-01

    As part of the Subglacial Access and Fast Ice Research Experiment (SAFIRE) pressurised hot water was used to drill four 603-616 m-long boreholes to the bed of the Greenland Ice Sheet at a site located 30 km from the calving front of fast-flowing, marine-terminating Store Glacier (70 degrees N, ~1000 m elevation). Four wired sensor strings were successfully installed in three of the boreholes. These included a thermistor string to obtain the englacial temperature profile installed in the same borehole as a string of tilt sensors to measure borehole deformation, and two sets of combined water pressure, electrical conductivity and turbidity sensors installed just above the bed in separate, adjacent boreholes. The boreholes made a strong hydrological connection to the bed during drilling, draining rapidly to ~80 m below the ice surface. The connection of subsequent boreholes was observed as a perturbation in water pressure and temperature recorded in neighbouring boreholes, indicating an effective hydrological connection between them. The sensors, which were wired to data-loggers at the surface, operated for between ~30 and >80 days from late summer into autumn before the cables stretched and snapped, with the lowermost sensors failing first. The records obtained from these sensors reveal (i) subglacial water pressures that were close to overburden but which generally increased through the period of measurement and varied diurnally by ~0.3 m, (ii) a minimum englacial temperature of -21 degrees C underlain by a zone of temperate ice, some tens of m thick, located immediately above the bed, and (iii) high rates of internal deformation and strain that increased towards the bed. These borehole observations are complemented by GPS measurements of ice motion, meteorological data, and seismic and radar surveys.

  2. Clean access, measurement, and sampling of Ellsworth Subglacial Lake: A method for exploring deep Antarctic subglacial lake environments

    Science.gov (United States)

    Siegert, Martin J.; Clarke, Rachel J.; Mowlem, Matt; Ross, Neil; Hill, Christopher S.; Tait, Andrew; Hodgson, Dominic; Parnell, John; Tranter, Martyn; Pearce, David; Bentley, Michael J.; Cockell, Charles; Tsaloglou, Maria-Nefeli; Smith, Andy; Woodward, John; Brito, Mario P.; Waugh, Ed

    2012-01-01

    Antarctic subglacial lakes are thought to be extreme habitats for microbial life and may contain important records of ice sheet history and climate change within their lake floor sediments. To find whether or not this is true, and to answer the science questions that would follow, direct measurement and sampling of these environments are required. Ever since the water depth of Vostok Subglacial Lake was shown to be >500 m, attention has been given to how these unique, ancient, and pristine environments may be entered without contamination and adverse disturbance. Several organizations have offered guidelines on the desirable cleanliness and sterility requirements for direct sampling experiments, including the U.S. National Academy of Sciences and the Scientific Committee on Antarctic Research. Here we summarize the scientific protocols and methods being developed for the exploration of Ellsworth Subglacial Lake in West Antarctica, planned for 2012-2013, which we offer as a guide to future subglacial environment research missions. The proposed exploration involves accessing the lake using a hot-water drill and deploying a sampling probe and sediment corer to allow sample collection. We focus here on how this can be undertaken with minimal environmental impact while maximizing scientific return without compromising the environment for future experiments.

  3. The Subglacial Access and Fast Ice Research Experiment (SAFIRE): 2. Preliminary outcomes from hot-water drilling and borehole instrumentation on Store Glacier, West Greenland

    Science.gov (United States)

    Doyle, Samuel; Hubbard, Bryn; Christoffersen, Poul; Young, Tun Jan; Hofstede, Coen; Todd, Joe; Bougamont, Marion; Hubbard, Alun

    2015-04-01

    As part of the SAFIRE research programme, pressurised hot water was used to drill four 603-616 m-long boreholes to the bed of the Greenland Ice Sheet at a site located 30 km from the calving front of marine-terminating Store Glacier (70° N, ~1000 m elevation). Despite the boreholes freezing within hours, 4 wired sensor strings were successfully deployed in three of the boreholes. These included a thermistor string to obtain the englacial temperature profile installed in the same borehole as a string of tilt sensors to measure borehole deformation, and two sets of water pressure, electrical conductivity and turbidity sensors installed just above the bed in separate, adjacent boreholes. The boreholes made a strong hydrological connection to the bed during drilling, draining rapidly to ~80 m below the ice surface. The connection of subsequent boreholes was observed as a perturbation in water pressure and temperature recorded in neighbouring boreholes, indicating an effective hydrological sub- or en-glacial connection between them. The short (week long) records obtained from these sensors in summer 2014 tentatively reveal (i) water pressure varying diurnally close to overburden albeit of a small magnitude (~0.3 m H2O), (ii) a minimum extrapolated englacial temperature of -21° C, (iii) and thermistors in the lowest 10 m of the borehole recorded temperatures above the pressure melting point indicating the presence of water. Data loggers were left running and longer records should become available in the near future. Differential drilling and instrument installation depths together with observations of discrete, diurnal turbidity events provisionally suggest the presence of sediment at the bed. These preliminary borehole observations will be complemented by GPS measurements of ice motion, meteorological data, and seismic and radar surveys to be undertaken over the next two years.

  4. Calculating the balance between atmospheric CO2 drawdown and organic carbon oxidation in subglacial hydrochemical systems

    Science.gov (United States)

    Graly, Joseph A.; Drever, James I.; Humphrey, Neil F.

    2017-04-01

    In order to constrain CO2 fluxes from biogeochemical processes in subglacial environments, we model the evolution of pH and alkalinity over a range of subglacial weathering conditions. We show that subglacial waters reach or exceed atmospheric pCO2 levels when atmospheric gases are able to partially access the subglacial environment. Subsequently, closed system oxidation of sulfides is capable of producing pCO2 levels well in excess of atmosphere levels without any input from the decay of organic matter. We compared this model to published pH and alkalinity measurements from 21 glaciers and ice sheets. Most subglacial waters are near atmospheric pCO2 values. The assumption of an initial period of open system weathering requires substantial organic carbon oxidation in only 4 of the 21 analyzed ice bodies. If the subglacial environment is assumed to be closed from any input of atmospheric gas, large organic carbon inputs are required in nearly all cases. These closed system assumptions imply that order of 10 g m-2 y-1 of organic carbon are removed from a typical subglacial environment—a rate too high to represent soil carbon built up over previous interglacial periods and far in excess of fluxes of surface deposited organic carbon. Partial open system input of atmospheric gases is therefore likely in most subglacial environments. The decay of organic carbon is still important to subglacial inorganic chemistry where substantial reserves of ancient organic carbon are found in bedrock. In glaciers and ice sheets on silicate bedrock, substantial long-term drawdown of atmospheric CO2 occurs.

  5. Evolution of climate, glaciation and subglacial environments of Antarctica from the deep ice core and Lake Vostok water sample studies (Key results of implementation of the Russian Science Foundation project, 2014–2016

    Directory of Open Access Journals (Sweden)

    V. Ya. Lipenkov

    2017-01-01

    Full Text Available Work on the project focused on the following five areas: 1  field works in Antarctica at Vostok and Concordia stations; 2  experimental and theoretical studies in the field of ice core and paleoclimate research; 3 experimental and theoretical works related to the exploration of subglacial Lake Vostok; 4 development of technology and drilling equipment for deep ice coring and exploration of subglacial lakes; 5 upgrading the analytical instrumentation in the Climate and Environmental Research Laboratory (CERL of the Arctic and Antarctic Research Institute. The main achievements in the field of ice core and paleoclimate research include 1 further elaboration of a new method of ice core dating, which is based on the link between air content of ice and local insolation, 2 investigation of the possible applications of the 17O-excess measurements in ice core to the paleoclimate research, 3  a better understanding of the mechanisms of the formation of relief-related variations in the isotopic content of an ice core drilled in the area of Antarctic megadunes, and 4 obtaining the first reliable data set on the variations of the 17O-excess in the Vostok core corresponding to marine isotope stage 11. As part of our studies of subglacial Lake Vostok, we have obtained a large body of new experimental data from the new ice core recovered from the 5G-3 borehole to the surface of the subglacial lake. Stacked profiles of isotopic composition, gas content and the size and orientation of the ice crystals in the lake ice have been composed from the data of three replicate cores from boreholes 5G-1, 5G-2 and 5G-3. The study reveals that the concentration of gases in the lake water beneath Vostok is unexpectedly low. A clear signature of the melt water in the surface layer of the lake, which is subject to refreezing on the icy ceiling of Lake Vostok, has been discerned in the three different properties of the accreted ice (the ice texture, the isotopic and

  6. Landscape evolution by subglacial quarrying

    DEFF Research Database (Denmark)

    Ugelvig, Sofie Vej; Egholm, D.L.; Iverson, Neal R.

    of sliding and erosion is not well supported when considering models for quarrying of rock blocks from the bed. Iverson (2012) introduced a new subglacial quarrying model that operates from the theory of adhesive wear. The model is based on the fact that cavities, with a high level of bedrock differential...... to a model for glacial hydrology. In order to also include the effects of cavitation on the subglacial sliding rate, we use a sliding law proposed by Schoof (2005), which includes an upper limit for the stress that can be supported at the bed. Computational experiments show that the combined influence...... evolution models. Geology, v. 40, no. 8, 679-682 (2012). Schoof, C. The effect of cavitation on glacier sliding. Proc. R. Soc. A , 461, 609-627 (2005). Jaeger, J.C., and Cook, N.G.W. Fundamentals of rock mechanics: New York, Chapman and Hall, 593 p. (1979)...

  7. Fast flow of Jakobshavn Isbræ and its subglacial drainage system

    Science.gov (United States)

    Werder, M. A.; Joughin, I. R.

    2013-12-01

    Jakobshavn Isbræ and many other outlet glaciers of present and past ice sheets lie in deep troughs which often have several overdeepened sections. The subglacial drainage system of such glaciers is heavily influenced by two effects caused by the pressure dependence of the melting point of water. The melting point decreases with increasing water pressure, this enhances wall-melt in downward sloping channels and diminishes wall-melt in upward sloping channels. Thus the first effect is the well known shutdown of channels on steep adverse bed slopes of overdeepenings and the associated high water pressure/low effective pressure. The second effect is a 2D effect and has not received much/any attention so far: the orientation of a channel will be deflected from the direction of the (negative) hydraulic potential gradient (which drives the water flow) towards the steepest slope of the bed. This leads to the enhanced formation of side channels dipping into the trough at about a 45° angle. This efficient connection between the margin and the trough equalizes the hydraulic potential, again leading to higher water pressure in the trough. We investigate these two effects with the 2D subglacial drainage system model GlaDS using Jakobshavn Isbræ as an example. We compare model runs with the pressure melt term disabled and enabled. With the term disabled the main channel situated in the trough is continuous and produces a large depression in the hydraulic potential and consequently high effective pressure in the trough (1-2MPa). Conversely, with the term enabled the main channel becomes discontinuous on steep adverse bed slopes and many side channels form on the margins of the trough. This leads to a hydraulic potential in the trough which is higher than in the surrounding area and consequently the effective pressure is low (0-1MPa). Low effective pressure leads to reduced basal drag and thus to more basal sliding. The modeled large decrease of effective pressure in the trough

  8. Subglacial discharge-driven renewal of tidewater glacier fjords

    Science.gov (United States)

    Carroll, Dustin; Sutherland, David A.; Shroyer, Emily L.; Nash, Jonathan D.; Catania, Ginny A.; Stearns, Leigh A.

    2017-08-01

    The classic model of fjord renewal is complicated by tidewater glacier fjords, where submarine melt and subglacial discharge provide substantial buoyancy forcing at depth. Here we use a suite of idealized, high-resolution numerical ocean simulations to investigate how fjord circulation driven by subglacial plumes, tides, and wind stress depends on fjord width, grounding line depth, and sill height. We find that the depth of the grounding line compared to the sill is a primary control on plume-driven renewal of basin waters. In wide fjords the plume exhibits strong lateral recirculation, increasing the dilution and residence time of glacially-modified waters. Rapid drawdown of basin waters by the subglacial plume in narrow fjords allows for shelf waters to cascade deep into the basin; wide fjords result in a thin, boundary current of shelf waters that flow toward the terminus slightly below sill depth. Wind forcing amplifies the plume-driven exchange flow; however, wind-induced vertical mixing is limited to near-surface waters. Tidal mixing over the sill increases in-fjord transport of deep shelf waters and erodes basin stratification above the sill depth. These results underscore the first-order importances of fjord-glacier geometry in controlling circulation in tidewater glacier fjords and, thus, ocean heat transport to the ice.

  9. Photogrammetric recognition of subglacial drainage channels during glacier lake outburst events

    Science.gov (United States)

    Schwalbe, Ellen; Koschitzki, Robert

    2016-04-01

    In recent years, many glaciers all over the world have been distinctly retreating and thinning. One of the consequences of this is the increase of so called glacier lake outburst flood events (GLOFs): Lakes that have been dammed by a glacier spontaneously start to drain through a subglacial channel underneath the glacier due to their outweighing hydrostatic pressure. In a short period of time, the lake water drains under the glacier and causes floods in downstream valleys. In many cases the latter become hazardous for people and their property. Due to glacier movement, the tunnel will soon collapse, and the glacier lake refills, thus starting a new GLOF cycle. The mechanisms ruling GLOF events are yet still not fully understood by glaciologists. Thus, there is a demand for data and measurement values that can help to understand and model the phenomena. In view of the above, we will show how photogrammetric image sequence analysis can be used to collect data which allows for drawing conclusions about the location and development of a subglacial channel. The work is a follow-up on earlier work on a photogrammetric GLOF early warning system (Mulsow et. al., 2013). For the purpose of detecting the subglacial tunnel, a camera has been installed in a pilot study to observe the area of the Colonia glacier (Northern Patagonian ice field) where it dams the lake Lago Cachet II. To verify the hypothesis, that the course of the subglacial tunnel is indicated by irregular surface motion patterns during its collapse, the camera acquired image sequences of the glacier surface during several GLOF events. Applying LSM-based tracking techniques to these image sequences, surface feature motion trajectories could be obtained for a dense raster of glacier points. Since only a single camera has been used for image sequence acquisition, depth information is required to scale the trajectories. Thus, for scaling and georeferencing of the measurements a GPS-supported photogrammetric network

  10. Drumlins, subglacial meltwater floods, and ocean responses

    Science.gov (United States)

    Shaw, John

    1989-09-01

    Drumlins and erosional marks in bedrock give evidence for broad, subglacial meltwater floods that have discharge-rate estimates of about 106 m3/s. Similar discharge rates are obtained for other late glacial catastrophic floods. The total volume of meltwater that is thought to have formed the Livingstone Lake, Saskatchewan, drumlin field is estimated at 8.4 x 104 km3. This volume is equivalent to a eustatic rise of 0.23 m in global sea level. Meltwater release and roughly contemporaneous formation of drumlin fields in North America and Europe could have involved several metres of sea-level rise in a few years. The implications of such floods for the generation of myths and the interpretation of the oxygen isotopic record of the oceans are discussed. High meltwater discharges are of potential importance to the generation of a lid of cold, fresh water over the North Atlantic and its effects on late glacial climate.

  11. Managing water pressure for water savings in developing countries

    African Journals Online (AJOL)

    2014-04-02

    Apr 2, 2014 ... prediction of the total amount of water savings under reduced pressures, with only 6% difference between measured and estimated volume ... efficiently used for estimating water savings when a calibrated simulation model .... that under high pressure these appliances consume water faster but the volumes ...

  12. Subglacial lake and meltwater flow predictions of the last North American and European Ice Sheets

    Science.gov (United States)

    Livingstone, S. J.; Clark, C. D.; Tarasov, L.

    2012-04-01

    There is increasing recognition that subglacial lakes act as key components within the ice sheet system, capable of influencing ice-sheet topography, ice volume and ice flow. The subglacial water systems themselves are recognised as being both active and dynamic, with large discharges of meltwater capable of flowing down hydrological pathways both between lakes and to the ice-sheet margins. At present, much glaciological research is concerned with the role of modern subglacial lake systems in Antarctica. Another approach to the exploration of subglacial lakes involves identification of the geological record of subglacial lakes that once existed beneath ice sheets of the last glaciation. Investigation of such palaeo-subglacial lakes offers significant advantages because we have comprehensive information about the bed properties, they are much more accessible and we can examine and sample the sediments with ease. If we can find palaeo-subglacial lakes then we have the potential to advance understanding with regard to the topographic context and hydrological pathways that the phenomena form a part of; essentially we gain spatial and sedimentological information in relation to investigations of contemporary subglacial lakes and lose out on the short-time dynamics. In this work we present predictions of palaeo-subglacial lakes and meltwater drainage pathways under the former European and North American ice sheets during the last glaciation. We utilise data on the current topography and seafloor bathymetry, and elevation models of the ice and ground surface topography (interpolated to a 5 km grid) to calculate the hydraulic potential surface at the ice-sheet bed. Meltwater routing algorithms and the flooding of local hydraulic minima allow us to predict subglacial channels and lakes respectively. Given that specific ice-surface and bed topographies are only known from modelled outputs, and thus contain significant uncertainty, we utilise many such outputs to examine

  13. Managing water pressure for water savings in developing countries ...

    African Journals Online (AJOL)

    Many water utilities, particularly in the developing countries, continue to operate inefficient water distribution systems (WDSs) with a significant amount of water and revenue losses. Various factors, manageable to different extents, contribute to water losses, such as poor infrastructure, high pressures, illegal water use, etc.

  14. Unveiling the Antarctic subglacial landscape.

    Science.gov (United States)

    Warner, Roland; Roberts, Jason

    2010-05-01

    Better knowledge of the subglacial landscape of Antarctica is vital to reducing uncertainties regarding prediction of the evolution of the ice sheet. These uncertainties are associated with bedrock geometry for ice sheet dynamics, including possible marine ice sheet instabilities and subglacial hydrological pathways (e.g. Wright et al., 2008). Major collaborative aerogeophysics surveys motivated by the International Polar Year (e.g. ICECAP and AGAP), and continuing large scale radar echo sounding campaigns (ICECAP and NASA Ice Bridge) are significantly improving the coverage. However, the vast size of Antarctica and logistic difficulties mean that data gaps persist, and ice thickness data remains spatially inhomogeneous. The physics governing large scale ice sheet flow enables ice thickness, and hence bedrock topography, to be inferred from knowledge of ice sheet surface topography and considerations of ice sheet mass balance, even in areas with sparse ice thickness measurements (Warner and Budd, 2000). We have developed a robust physically motivated interpolation scheme, based on these methods, and used it to generate a comprehensive map of Antarctic bedrock topography, using along-track ice thickness data assembled for the BEDMAP project (Lythe et al., 2001). This approach reduces ice thickness biases, compared to traditional inverse distance interpolation schemes which ignore the information available from considerations of ice sheet flow. In addition, the use of improved balance fluxes, calculated using a Lagrangian scheme, eliminates the grid orientation biases in ice fluxes associated with finite difference methods (Budd and Warner, 1996, Le Brocq et al., 2006). The present map was generated using a recent surface DEM (Bamber et al., 2009, Griggs and Bamber, 2009) and accumulation distribution (van de Berg et al., 2006). Comparing our results with recent high resolution regional surveys gives confidence that all major subglacial topographic features are

  15. Antarctic Subglacial Lake Classification Inventory, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is an Antarctic radar-based subglacial lake classification collection, which focuses on the radar reflection properties of each given lake.

  16. Water-Pressure Distribution on Seaplane Float

    Science.gov (United States)

    Thompson, F L

    1929-01-01

    The investigation presented in this report was conducted for the purpose of determining the distribution and magnitude of water pressures likely to be experienced on seaplane hulls in service. It consisted of the development and construction of apparatus for recording water pressures lasting one one-hundredth second or longer and of flight tests to determine the water pressures on a UO-1 seaplane float under various conditions of taxiing, taking off, and landing. The apparatus developed was found to operate with satisfactory accuracy and is suitable for flight tests on other seaplanes. The tests on the UO-1 showed that maximum pressures of about 6.5 pounds per square inch occur at the step for the full width of the float bottom. Proceeding forward from the step the maximum pressures decrease in magnitude uniformly toward the bow, and the region of highest pressures narrows toward the keel. Immediately abaft the step the maximum pressures are very small, but increase in magnitude toward the stern and there once reached a value of about 5 pounds per square inch. (author)

  17. Microbial sulfur transformations in sediments from Subglacial Lake Whillans

    Directory of Open Access Journals (Sweden)

    Alicia M Purcell

    2014-11-01

    Full Text Available Diverse microbial assemblages inhabit subglacial aquatic environments. While few of these environments have been sampled, data reveal that subglacial organisms gain energy for growth from reduced minerals containing nitrogen, iron, and sulfur. Here we investigate the role of microbially mediated sulfur transformations in sediments from Subglacial Lake Whillans (SLW, Antarctica, by examining key genes involved in dissimilatory sulfur oxidation and reduction. The presence of sulfur transformation genes throughout the top 34 cm of SLW sediments changes with depth. SLW surficial sediments were dominated by genes related to known sulfur-oxidizing chemoautotrophs. Sequences encoding the adenosine-5’-phosphosulfate (APS reductase gene, involved in both dissimilatory sulfate reduction and sulfur oxidation, were present in all samples and clustered into 16 distinct OTUs. The majority of APS reductase sequences (74% clustered with known sulfur oxidizers including those within the Sideroxydans and Thiobacillus genera. Reverse-acting dissimilatory sulfite reductase (rDSR and 16S rRNA gene sequences further support dominance of Sideroxydans and Thiobacillus phylotypes in the top 2 cm of SLW sediments. The SLW microbial community has the genetic potential for sulfate reduction which is supported by experimentally measured low rates (1.4 pmol cm-3d-1 of biologically mediated sulfate reduction and the presence of APS reductase and DSR gene sequences related to Desulfobacteraceae and Desulfotomaculum. Our results also infer the presence of sulfur oxidation, which can be a significant energetic pathway for chemosynthetic biosynthesis in SLW sediments. The water in SLW ultimately flows into the Ross Sea where intermediates from subglacial sulfur transformations can influence the flux of solutes to the Southern Ocean.

  18. Testing the influence of subglacial erosion on the long-term evolution and stability of continental ice sheets using numerical modelling

    Science.gov (United States)

    Swift, D. A.; Egholm, D. L.; Brædstrup, C. F.; Cook, S.; Livingstone, S. J.; Clark, C.; Patton, H.; Ely, J.

    2013-12-01

    Focussed erosion beneath continental ice sheets promotes efficient evacuation of ice along fast-flowing marine outlet glacier systems. Theory indicates that bed profiles should tend toward uniformly overdeepened geometries that will reduce ice sheet stability because (a) grounding lines situated on negative slopes are vulnerable to catastrophic retreat and (b) grounding-line stability is sensitive to ice velocity, meaning grounding lines should become unstable as overdeepening causes subglacial water pressures and basal sediment thickness and continuity to increase. This suggests a conceptual model of ice-bed evolution in which ice sheets are self-destructive, because bed erosion reduces equilibrium ice sheet volume and extent. However, many outlet glacier and ice stream systems possess complex bed topographies, raising questions about the nature of subglacial landscape evolution that have major implications for our understanding of ice sheet evolution and stability. For example, a contrasting model of ice-bed evolution in which strong ice-erosion feedbacks produce multiple overdeepenings might enhance ice sheet stability, because numerous bed undulations should resist fast ice flow and impede grounding line retreat. We therefore explore the possible glaciological significance of contrasting models of subglacial landscape evolution using a higher-order ice sheet model (iSOSIA) and assess the implications for the evolution and stability of continental ice sheets. The results will also aid understanding of contemporary ice sheet stability and identify weaknesses in process understanding that will aid further development of ice-erosion models.

  19. Supercritical-pressure light water cooled reactors

    CERN Document Server

    Oka, Yoshiaki

    2014-01-01

    This book focuses on the latest reactor concepts, single pass core and experimental findings in thermal hydraulics, materials, corrosion, and water chemistry. It highlights research on supercritical-pressure light water cooled reactors (SCWRs), one of the Generation IV reactors that are studied around the world. This book includes cladding material development and experimental findings on heat transfer, corrosion and water chemistry. The work presented here will help readers to understand the fundamental elements of reactor design and analysis methods, thermal hydraulics, materials and water

  20. High pressure water jet mining machine

    Science.gov (United States)

    Barker, Clark R.

    1981-05-05

    A high pressure water jet mining machine for the longwall mining of coal is described. The machine is generally in the shape of a plowshare and is advanced in the direction in which the coal is cut. The machine has mounted thereon a plurality of nozzle modules each containing a high pressure water jet nozzle disposed to oscillate in a particular plane. The nozzle modules are oriented to cut in vertical and horizontal planes on the leading edge of the machine and the coal so cut is cleaved off by the wedge-shaped body.

  1. Coolant mixing in pressurized water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Hoehne, T.; Grunwald, G.

    1998-10-01

    The behavior of PWRs during cold water or boron dilution transients is strongly influenced by the distribution of coolant temperature and boron concentration at the core inlet. This distribution is the needed input to 3-dimensional neutron kinetics to calculate the power distribution in the core. It mainly depends on how the plugs of cold or unborated water formed in a single loop are mixed in the downcomer and in the lower plenum. To simulate such mixture phenomena requires the application of 3-dimensional CFD (computational fluid dynamics) codes. The results of the simulation have to be validated against mixture experiments at scaled facilities. Therefore, in the framework of a research project funded by BMBF, the institute creates a 1:5 mixture facility representing first the geometry of a German pressurized water reactor and later the European Pressurized Water Reactor (EPR) geometry. The calculations are based on the CFD Code CFX-4. (orig.)

  2. Actively evolving subglacial conduits and eskers initiate ice shelf channels at an Antarctic grounding line

    Science.gov (United States)

    Drews, R.; Pattyn, F.; Hewitt, I. J.; Ng, F. S. L.; Berger, S.; Matsuoka, K.; Helm, V.; Bergeot, N.; Favier, L.; Neckel, N.

    2017-05-01

    Ice-shelf channels are long curvilinear tracts of thin ice found on Antarctic ice shelves. Many of them originate near the grounding line, but their formation mechanisms remain poorly understood. Here we use ice-penetrating radar data from Roi Baudouin Ice Shelf, East Antarctica, to infer that the morphology of several ice-shelf channels is seeded upstream of the grounding line by large basal obstacles indenting the ice from below. We interpret each obstacle as an esker ridge formed from sediments deposited by subglacial water conduits, and calculate that the eskers' size grows towards the grounding line where deposition rates are maximum. Relict features on the shelf indicate that these linked systems of subglacial conduits and ice-shelf channels have been changing over the past few centuries. Because ice-shelf channels are loci where intense melting occurs to thin an ice shelf, these findings expose a novel link between subglacial drainage, sedimentation and ice-shelf stability.

  3. Actively evolving subglacial conduits and eskers initiate ice shelf channels at an Antarctic grounding line.

    Science.gov (United States)

    Drews, R; Pattyn, F; Hewitt, I J; Ng, F S L; Berger, S; Matsuoka, K; Helm, V; Bergeot, N; Favier, L; Neckel, N

    2017-05-09

    Ice-shelf channels are long curvilinear tracts of thin ice found on Antarctic ice shelves. Many of them originate near the grounding line, but their formation mechanisms remain poorly understood. Here we use ice-penetrating radar data from Roi Baudouin Ice Shelf, East Antarctica, to infer that the morphology of several ice-shelf channels is seeded upstream of the grounding line by large basal obstacles indenting the ice from below. We interpret each obstacle as an esker ridge formed from sediments deposited by subglacial water conduits, and calculate that the eskers' size grows towards the grounding line where deposition rates are maximum. Relict features on the shelf indicate that these linked systems of subglacial conduits and ice-shelf channels have been changing over the past few centuries. Because ice-shelf channels are loci where intense melting occurs to thin an ice shelf, these findings expose a novel link between subglacial drainage, sedimentation and ice-shelf stability.

  4. Managing water pressure for water savings in developing countries

    African Journals Online (AJOL)

    2014-03-03

    Mar 3, 2014 ... The Kotež district is a suburb located in the northern part of the city, on the flatlands on the left bank of the Danube River at an altitude of 71.50 m asl, at the edge of the Belgrade water supply system's lowest pressure zone. The water distribution network in Kotež was constructed during the 1970s and is pre-.

  5. Physiological ecology of microorganisms in Subglacial Lake Whillans

    Directory of Open Access Journals (Sweden)

    Trista J Vick-Majors

    2016-10-01

    Full Text Available Subglacial microbial habitats are widespread in glaciated regions of our planet. Some of these environments have been isolated from the atmosphere and from sunlight for many thousands of years. Consequently, ecosystem processes must rely on energy gained from the oxidation of inorganic substrates or detrital organic matter. Subglacial Lake Whillans (SLW is one of more than 400 subglacial lakes known to exist under the Antarctic ice sheet; however, little is known about microbial physiology and energetics in these systems. When it was sampled through its 800 m thick ice cover in 2013, the SLW water column was shallow (~2 m deep, oxygenated, and possessed sufficient concentrations of C, N, and P substrates to support microbial growth. Here, we use a combination of physiological assays and models to assess the energetics of microbial life in SLW. In general, SLW microorganisms grew slowly in this energy-limited environment. Heterotrophic cellular carbon turnover times, calculated from 3H-thymidine and 3H-leucine incorporation rates, were long (60 to 500 days while cellular doubling times averaged 196 days. Inferred growth rates (average ~0.006 d-1 obtained from the same incubations were at least an order of magnitude lower than those measured in Antarctic surface lakes and oligotrophic areas of the ocean. Low growth efficiency (8% indicated that heterotrophic populations in SLW partition a majority of their carbon demand to cellular maintenance rather than growth. Chemoautotrophic CO2-fixation exceeded heterotrophic organic C-demand by a factor of ~1.5. Aerobic respiratory activity associated with heterotrophic and chemoautotrophic metabolism surpassed the estimated supply of oxygen to SLW, implying that microbial activity could deplete the oxygenated waters, resulting in anoxia. We used thermodynamic calculations to examine the biogeochemical and energetic consequences of environmentally imposed switching between aerobic and anaerobic metabolisms

  6. Physiological Ecology of Microorganisms in Subglacial Lake Whillans

    Science.gov (United States)

    Vick-Majors, Trista J.; Mitchell, Andrew C.; Achberger, Amanda M.; Christner, Brent C.; Dore, John E.; Michaud, Alexander B.; Mikucki, Jill A.; Purcell, Alicia M.; Skidmore, Mark L.; Priscu, John C.

    2016-01-01

    Subglacial microbial habitats are widespread in glaciated regions of our planet. Some of these environments have been isolated from the atmosphere and from sunlight for many thousands of years. Consequently, ecosystem processes must rely on energy gained from the oxidation of inorganic substrates or detrital organic matter. Subglacial Lake Whillans (SLW) is one of more than 400 subglacial lakes known to exist under the Antarctic ice sheet; however, little is known about microbial physiology and energetics in these systems. When it was sampled through its 800 m thick ice cover in 2013, the SLW water column was shallow (~2 m deep), oxygenated, and possessed sufficient concentrations of C, N, and P substrates to support microbial growth. Here, we use a combination of physiological assays and models to assess the energetics of microbial life in SLW. In general, SLW microorganisms grew slowly in this energy-limited environment. Heterotrophic cellular carbon turnover times, calculated from 3H-thymidine and 3H-leucine incorporation rates, were long (60 to 500 days) while cellular doubling times averaged 196 days. Inferred growth rates (average ~0.006 d−1) obtained from the same incubations were at least an order of magnitude lower than those measured in Antarctic surface lakes and oligotrophic areas of the ocean. Low growth efficiency (8%) indicated that heterotrophic populations in SLW partition a majority of their carbon demand to cellular maintenance rather than growth. Chemoautotrophic CO2-fixation exceeded heterotrophic organic C-demand by a factor of ~1.5. Aerobic respiratory activity associated with heterotrophic and chemoautotrophic metabolism surpassed the estimated supply of oxygen to SLW, implying that microbial activity could deplete the oxygenated waters, resulting in anoxia. We used thermodynamic calculations to examine the biogeochemical and energetic consequences of environmentally imposed switching between aerobic and anaerobic metabolisms in the SLW

  7. Subglacial processes revealed by the internal structure of drumlins, Stargard drumlin field, NW Poland

    Science.gov (United States)

    Hermanowski, Piotr; Piotrowski, Jan A.; Szuman-Kalita, Izabela

    2017-04-01

    Numerous studies have provided insight into processes operating under contemporary and palaeo-ice sheets. Many of these studies concerned drumlins, landforms whose formation is essential to the understanding of subglacial soft-bedded systems. Despite the interdisciplinary efforts involving sophisticated analytical and interpretative tools the "drumlin problem" remains elusive and continues to generate much controversy. In this study the geological composition of two drumlins from the Stargard drumlin field (NW Poland) in the terminal area of a major last-glacial palaeo-ice stream was examined in three excavated trenches at macro- and microscales. In each trench, sediment description and fabric analyses were conducted, and samples collected for micromorphological, AMS (anisotropy of magnetic susceptibility) and grain size measurements. Both investigated drumlins are mainly composed of macroscopically homogeneous till with minor, max. 5 cm thick sand stringers and sparse silty inclusions. Distinct features are (1) a highly deformed, up to 18-cm thick till layer with clay- and pebble-sized clasts at the top, and (2) a continuous thin intra-till clay layer. Till macro-fabric measurements reveal a very high clustering strength and low isotropy index. AMS eigenvectors V1 vary significantly, but the dominant direction is consistent with the macrofabric measurements. Most of the observed microstructures indicate ductile deformation of the till. The overall observations suggest a shallow subglacial deformation not affecting the entire till thickness at any time intervening with ice/bed separation facilitating enhanced basal sliding. The intra-till clay layer of low hydraulic conductivity contributed to elevated pore-water pressure in the sediment causing its fluidization and deformation. Intervening thin-skinned sediment deformation and basal de-coupling resulted in fast ice flow that, coupled with material release from the ice sole and its accretion at the ice

  8. Exploring Explanations of Subglacial Bedform Sizes Using Statistical Models.

    Directory of Open Access Journals (Sweden)

    John K Hillier

    Full Text Available Sediments beneath modern ice sheets exert a key control on their flow, but are largely inaccessible except through geophysics or boreholes. In contrast, palaeo-ice sheet beds are accessible, and typically characterised by numerous bedforms. However, the interaction between bedforms and ice flow is poorly constrained and it is not clear how bedform sizes might reflect ice flow conditions. To better understand this link we present a first exploration of a variety of statistical models to explain the size distribution of some common subglacial bedforms (i.e., drumlins, ribbed moraine, MSGL. By considering a range of models, constructed to reflect key aspects of the physical processes, it is possible to infer that the size distributions are most effectively explained when the dynamics of ice-water-sediment interaction associated with bedform growth is fundamentally random. A 'stochastic instability' (SI model, which integrates random bedform growth and shrinking through time with exponential growth, is preferred and is consistent with other observations of palaeo-bedforms and geophysical surveys of active ice sheets. Furthermore, we give a proof-of-concept demonstration that our statistical approach can bridge the gap between geomorphological observations and physical models, directly linking measurable size-frequency parameters to properties of ice sheet flow (e.g., ice velocity. Moreover, statistically developing existing models as proposed allows quantitative predictions to be made about sizes, making the models testable; a first illustration of this is given for a hypothesised repeat geophysical survey of bedforms under active ice. Thus, we further demonstrate the potential of size-frequency distributions of subglacial bedforms to assist the elucidation of subglacial processes and better constrain ice sheet models.

  9. Subglacial Calcites from Northern Victoria Land: archive of Antarctic volcanism in the Last Glacial Maximum

    Science.gov (United States)

    Frisia, Silvia; Weirich, Laura; Hellstrom, John; Borsato, Andrea; Golledge, Nicholas R.; Anesio, Alexandre M.; Bajo, Petra; Drysdale, Russell N.; Augustinus, Paul C.; Barbante, Carlo; Cooper, Alan

    2017-04-01

    Subglacial carbonates bear similarities to stalagmites in their fabrics and the potential to obtain precise chronologies using U-series methods. Their chemical properties also reflect those of their parent waters, which, in contrast to stalagmites, are those of subglacial meltwaters. In analogy to speleothems, stable Carbon isotope ratios and trace elements such as Uranium, Iron and Manganese provide the opportunity to investigate ancient extreme environments without the need to drill through thousands of metres of ice. Sedimentological, geochemical and microbial evidence preserved in LGM subglacial calcites from Northern Victoria Land, close to the East Antarctic Ice Sheet margin, allow us to infer that subglacial volcanism was active in the Trans Antarctic Mountain region and induced basal ice melting. We hypothesize that a meltwater reservoir was drained and injected into interconnected basal pore systems where microbial processes enhanced bedrock weathering and, thus, released micronutrients. Volcanic influence is supported by the presence of fluorine (F) and sulphur in sediment-laden calcite layers containing termophilic species. Notably, calcite δ13C points to dissolved inorganic carbon evolved from subglacial metabolic processes. Once transported to the sea, soluble iron likely contributed to fertilizing the Southern Ocean and CO2 drawdown. This is the first well-dated evidence for LGM volcanism in Antarctica, which complements the record of volcanic eruptions retrieved from Talos Dome ice core, and supports the hypothesis of large-scale volcanism as an important driver of climate change. We conclude that subglacial carbonates are equivalent to speleothems in their palaeoclimate potential and may become a most useful source of information of ecosystems and processes at peak glacials in high altitude/high latitude settings.

  10. Subglacial sediment provenance and transport in West Antarctica from micropaleontologic analysis of Subglacial Lake Whillans and the upstream sectors of the Whillans and Kamb ice streams

    Science.gov (United States)

    Scherer, Reed; Coenen, Jason; Warny, Sophie

    2014-05-01

    The WISSARD (Whillans Ice Stream Subglacial Access Research Drilling) project recovered sediment cores from Subglacial Lake Whillans (SLW) in West Antarctica. We report preliminary micropaleontological analyses of SLW sediments, augmented by analysis of sediments previously recovered from beneath the upstream camps of the Whillans Ice Stream (WIS) and Kamb Ice Stream (KIS). Microfossils in these sediments (notably diatoms, sponge spicules, and organic-walled palynomorphs), include information regarding sediment transport, subglacial physical processes and ice sheet history. Absolute abundance (particles per gram dry sediment) of identifiable diatoms and diatom fragments in different size classes were calculated to compare and contrast each environment. Sponge spicules are being analyzed for taphonomic effects from subglacial transport and shearing. Palynomorphs are analyzed for abundance, diversity, and source rock ages. In SLW the upper 30 cm is softer and more water-rich than the underlying sediments. However, no statistically significant variation in microfossil and fragment abundance or taphonomy is noted in these diamictons, which is in agreement with the stratigraphic homogeneity evident from geochemical and geological analyses performed to date. SLW contains 1.52x106 to 1.13x107 diatom fragments per gram, compared with 6.43x106 to 4.63x108 at upstream WIS and 6.13 107 to 1.58x108 at KIS. Whole diatoms are orders of magnitude lower in concentration. Low abundance and poor preservation of diatoms and spicules at SLW suggests relatively long distance transport from their marine sediment source, with evidence of high shear strain, following the subglacial shearing index of Scherer et al. (2004). Upper Miocene diatoms dominate all samples analyzed, though older and younger diatoms are noted as well. The WIS samples exhibit the highest diversity of diatoms, including Paleogene freshwater diatoms. KIS sediments have the highest abundance of whole diatoms, but they

  11. Geology and environments of subglacial Lake Vostok.

    Science.gov (United States)

    Leitchenkov, German L; Antonov, Anton V; Luneov, Pavel I; Lipenkov, Vladimir Ya

    2016-01-28

    The reconstruction of the geological (tectonic) structure and environments of subglacial Lake Vostok is based on geophysical surveys and the study of mineral particles found in cores of accreted ice and frozen lake water (sampled after the lake was unsealed). Seismic reflection and refraction investigations conducted in the southern part of Lake Vostok show very thin (200-300 m) sedimentary cover overlying a crystalline basement. Most of this thin veneer is thought to have been deposited during temperate-glacial conditions in Oligocene to Middle Miocene time (ca 34-14 Ma). The composition of the lake-bottom sediments can be deduced from mineral inclusions found in cores of accreted ice. Inclusions are represented by soft aggregates consisting mainly of clay-mica minerals and micrometre-sized quartz grains. Some of these inclusions contain subangular to semi-rounded rock clasts (siltstones and sandstones) ranging from 0.3 to 8 mm in size. In total, 31 zircon grains have been identified in two rock clasts and dated using SHRIMP-II. The ages of the studied zircons range from 0.6 to 2.0 Ga with two distinct clusters between 0.8 and 1.15 Ga and between 1.6 and 1.8 Ga. Rock clasts obviously came from the western lake shore, which is thus composed of terrigenous strata with an age of not older than 600 Ma. The sedimentary nature of the western lake shore is also confirmed by seismic refraction data showing seismic velocities there of 5.4-5.5 km s(-1) at the bedrock surface. After Lake Vostok was unsealed, its water (frozen and sampled next season) was also studied with scanning electron microscopy and X-ray microprobe analysis. This study showed the existence of calcium carbonate and silica microparticles (10-20 μm across) in frozen water. © 2015 The Author(s).

  12. Modelling subglacial drainage and its role in ice-ocean interaction

    Science.gov (United States)

    Hewitt, Ian; Dallaston, Michael; Wells, Andrew

    2015-04-01

    Melting at the ice-ocean interface, both beneath ice shelves and at near-vertical tidewater margins, is strongly influenced by discharge of meltwater from beneath the grounded ice. The fresh water source can help to initiate a buoyant plume that rises up the ice face, entraining heat from the ocean to melt the ice. When the subglacial discharge is spatially and temporally variable, it can cause spatial and temporal variations in the melting rate, which in turn may influence ocean circulation in the cavity and ice flow within the shelf. Recent observations of channelized ice shelf bases may have their origin in variable subglacial discharge from beneath the grounded ice. In this work, we use physically-based models of the subglacial drainage system to examine the likely mode of melt water delivery across the grounding line. We find that if subglacial channels (Rothlisberger channels) exist they can be expected to `trumpet' out as the ocean is approached, due to a lack of confining stress to counteract wall melting. This causes a reduction in horizontal momentum in the water and can lead to pronounced localized melting around channel termini. This may lead to increased propensity for calving at such locations. We also examine the effect of subglacial discharge variations on the evolution of a downstream floating ice shelf. We find that lateral variations in the flow across the grounding line can result in variations in plume-driven melting which evolve to create basal channels in the shelf aligned with the flow. The preferred spacing of the channels is controlled by a balance between buoyancy-driven acceleration and turbulent mixing in the ocean layer.

  13. Recharge of a subglacial lake by surface meltwater in northeast Greenland.

    Science.gov (United States)

    Willis, Michael J; Herried, Bradley G; Bevis, Michael G; Bell, Robin E

    2015-02-12

    In a warming climate, surface meltwater production on large ice sheets is expected to increase. If this water is delivered to the ice sheet base it may have important consequences for ice dynamics. For example, basal water distributed in a diffuse network can decrease basal friction and accelerate ice flow, whereas channelized basal water can move quickly to the ice margin, where it can alter fjord circulation and submarine melt rates. Less certain is whether surface meltwater can be trapped and stored in subglacial lakes beneath large ice sheets. Here we show that a subglacial lake in Greenland drained quickly, as seen in the collapse of the ice surface, and then refilled from surface meltwater input. We use digital elevation models from stereo satellite imagery and airborne measurements to resolve elevation changes during the evolution of the surface and basal hydrologic systems at the Flade Isblink ice cap in northeast Greenland. During the autumn of 2011, a collapse basin about 70 metres deep and about 0.4 cubic kilometres in volume formed near the southern summit of the ice cap as a subglacial lake drained into a nearby fjord. Over the next two years, rapid uplift of the floor of the basin (which is approximately 8.4 square kilometres in area) occurred as surface meltwater flowed into crevasses around the basin margin and refilled the subglacial lake. Our observations show that surface meltwater can be trapped and stored at the bed of an ice sheet. Sensible and latent heat released by this trapped meltwater could soften nearby colder basal ice and alter downstream ice dynamics. Heat transport associated with meltwater trapped in subglacial lakes should be considered when predicting how ice sheet behaviour will change in a warming climate.

  14. Effect of pressure on colloidal behavior in hydrothermal water.

    Science.gov (United States)

    Ghosh, Swapan K; Tsujii, Kaoru

    2008-06-12

    The pressure dependence of the colloidal phenomena of nanoparticles in hydrothermal water was investigated by both experiment and theory. Dynamic light scattering experiments show that diamond nanoparticles, which are highly stable in ambient water, easily aggregate in high-temperature and high-pressure water. Although the stability of nanoparticles in ambient pure water does not depend on pressure, it is interestingly found that at constant temperature particles aggregate faster in the hydrothermal regime when the pressure is higher. A theoretical interpretation is proposed to predict the stability of colloids in water as a function of temperature and pressure. Numerical analysis shows that the repulsive interparticle potential barrier, which stabilizes particles in the dispersion, decreases dramatically in high-temperature and high-pressure water. The decrease in the potential barrier arises from the temperature and the pressure dependencies of the dielectric constant (epsilon) and the ion product (p K w) of water. Numerical analysis shows that the pressure dependence of epsilon is negligible in the temperature range of 20-300 degrees C, whereas the pressure dependence of p K w is significant at temperatures of T > 150 degrees C. The theory reveals that the pressure dependence of the rate of size increment in the hydrothermal regime results from the pressure dependence of p K w. An increase in pressure in the hydrothermal water enhances the ionization of water molecules which reduces the surface potential of the particles. This effect lowers the interparticle repulsive potential barrier, which accelerates aggregation of the particles.

  15. Microbial Community Structure of Subglacial Lake Whillans, West Antarctica.

    Science.gov (United States)

    Achberger, Amanda M; Christner, Brent C; Michaud, Alexander B; Priscu, John C; Skidmore, Mark L; Vick-Majors, Trista J

    2016-01-01

    Subglacial Lake Whillans (SLW) is located beneath ∼800 m of ice on the Whillans Ice Stream in West Antarctica and was sampled in January of 2013, providing the first opportunity to directly examine water and sediments from an Antarctic subglacial lake. To minimize the introduction of surface contaminants to SLW during its exploration, an access borehole was created using a microbiologically clean hot water drill designed to reduce the number and viability of microorganisms in the drilling water. Analysis of 16S rRNA genes (rDNA) amplified from samples of the drilling and borehole water allowed an evaluation of the efficacy of this approach and enabled a confident assessment of the SLW ecosystem inhabitants. Based on an analysis of 16S rDNA and rRNA (i.e., reverse-transcribed rRNA molecules) data, the SLW community was found to be bacterially dominated and compositionally distinct from the assemblages identified in the drill system. The abundance of bacteria (e.g., Candidatus Nitrotoga, Sideroxydans, Thiobacillus, and Albidiferax) and archaea (Candidatus Nitrosoarchaeum) related to chemolithoautotrophs was consistent with the oxidation of reduced iron, sulfur, and nitrogen compounds having important roles as pathways for primary production in this permanently dark ecosystem. Further, the prevalence of Methylobacter in surficial lake sediments combined with the detection of methanogenic taxa in the deepest sediment horizons analyzed (34-36 cm) supported the hypothesis that methane cycling occurs beneath the West Antarctic Ice Sheet. Large ratios of rRNA to rDNA were observed for several operational taxonomic units abundant in the water column and sediments (e.g., Albidiferax, Methylobacter, Candidatus Nitrotoga, Sideroxydans, and Smithella), suggesting a potentially active role for these taxa in the SLW ecosystem. Our findings are consistent with chemosynthetic microorganisms serving as the ecological foundation in this dark subsurface environment, providing new

  16. Penicillium mycobiota in Arctic subglacial ice

    DEFF Research Database (Denmark)

    Sonjak, S.; Frisvad, Jens Christian; Gunde-Cimerman, N.

    2006-01-01

    to be inhabited exclusively by heterotrophic bacteria. In this study we report on the very high occurrence (up to 9000 CFU L-1) and diversity of filamentous Penicillium spp. in the sediment-rich subglacial ice of three different polythermal Arctic glaciers (Svalbard, Norway). The dominant species was P. crustosum......, representing on the average half of all isolated strains from all three glaciers. The other most frequently isolated species were P. bialowiezense, P. chrysogenum, P. thomii, P. solitum, P. palitans, P. echinulatum, P. polonicum, P. commune, P. discolor, P. expansum, and new Penicillium species (sp. 1). Twelve...... more Penicillium species were occasionally isolated. The fungi isolated produced consistent profiles of secondary metabolites, not different from the same Penicillium species from other habitats. This is the first report on the presence of large populations of Penicillium spp. in subglacial sediment...

  17. Numerical Modeling of Subglacial Sediment Deformation

    DEFF Research Database (Denmark)

    Damsgaard, Anders

    2015-01-01

    may cause mass loss in the near future to exceed current best estimates. Ice flow in larger ice sheets focuses in fast-moving streams due to mechanical non-linearity of ice. These ice streams often move at velocities several magnitudes larger than surrounding ice and consequentially constitute...... glaciers move by deforming their sedimentary beds. Several modern ice streams, in particular, move as plug flows due to basal sediment deformation. An intense and long-winded discussion about the appropriate description for subglacial sediment mechanics followed this discovery, with good reason...... velocities previously associated with elastic or viscous ice deformation. If a glacier dominated by subglacial creep experiences prolonged events of strong surface melt or increased driving stresses, the plastic strength limit can cause rapid acceleration downslope due to imbalance of stresses....

  18. Paleo ice flow and subglacial meltwater dynamics in Pine Island Bay, West Antarctica

    Directory of Open Access Journals (Sweden)

    F. O. Nitsche

    2013-02-01

    Full Text Available Increasing evidence for an elaborate subglacial drainage network underneath modern Antarctic ice sheets suggests that basal meltwater has an important influence on ice stream flow. Swath bathymetry surveys from previously glaciated continental margins display morphological features indicative of subglacial meltwater flow in inner shelf areas of some paleo ice stream troughs. Over the last few years several expeditions to the eastern Amundsen Sea embayment (West Antarctica have investigated the paleo ice streams that extended from the Pine Island and Thwaites glaciers. A compilation of high-resolution swath bathymetry data from inner Pine Island Bay reveals details of a rough seabed topography including several deep channels that connect a series of basins. This complex basin and channel network is indicative of meltwater flow beneath the paleo-Pine Island and Thwaites ice streams, along with substantial subglacial water inflow from the east. This meltwater could have enhanced ice flow over the rough bedrock topography. Meltwater features diminish with the onset of linear features north of the basins. Similar features have previously been observed in several other areas, including the Dotson-Getz Trough (western Amundsen Sea embayment and Marguerite Bay (SW Antarctic Peninsula, suggesting that these features may be widespread around the Antarctic margin and that subglacial meltwater drainage played a major role in past ice-sheet dynamics.

  19. Subglacial conditions and Scandinavian Ice Sheet dynamics at the coarse-grained substratum of the fore-mountain area of southern Poland

    Science.gov (United States)

    Salamon, Tomasz

    2016-11-01

    The fore-mountain areas of southern Poland are locally composed of the coarse-grained sediments of alluvial fans, which created unusual conditions under the advancing Scandinavian Ice Sheet during the Elsterian glaciation. This highly permeable substratum potentially enabled rapid outflow of meltwater from the ice sheet base, thereby reducing the water pressure and strongly influencing the ice sheet dynamics. The subglacial conditions and the relationship between the ice sheet behaviour and its coarse-grained substratum were studied at the foreland of the western Carpathian Mountains. The sedimentological and structural analysis of the till and related sediments that were deposited above the alluvial gravel of the fore-mountain fans are presented. The study indicates that despite the high permeability of the coarse-grained substratum, it did not slow the ice sheet movement. Conversely, the ice sheet moved mainly due to basal slip and locally shallow deformations. This was a consequence of very high basal water pressure, which resulted largely from the presence of permafrost that restricted subglacial groundwater outflow. In addition, the ice sheet substratum was inclined opposite to the direction of its movement, increasing the pressure of the subglacial water. Numerous subhorizontal sandy laminae within the till indicate that the meltwater from the ice sheet base was drained by a water film along the ice/bed interface. The water escape structures within the till and subtill sediments indicate the occasional instability of the ice sheet hydrological system and suggest that the meltwater was periodically stored in the ice sheet base. Temporal changes occurring in the ice sheet hydrological system might indicate variations in the ice sheet behaviour; i.e. phases of relatively fast ice flow and phases of ice stagnation. The latter were probably correlated with the freezing of the ice margin to its base. The study shows how the coarse-grained substratum could

  20. Subglacial sediment mechanics investigated by computer simulation of granular material

    DEFF Research Database (Denmark)

    Damsgaard, Anders; Egholm, David Lundbek; Tulaczyk, Slawek

    to the mechanical nonlinearity of the sediment, internal porosity changes during deformation, and associated structural and kinematic phase transitions. In this presentation, we introduce the Discrete Element Method (DEM) for particle-scale granular simulation. The DEM is fully coupled with fluid dynamics....... The numerical method is applied to better understand the mechanical properties of the subglacial sediment and its interaction with meltwater. The computational approach allows full experimental control and offers insights into the internal kinematics, stress distribution, and mechanical stability. During...... by linear-viscous sediment movement. We demonstrate how channel flanks are stabilized by the sediment frictional strength. Additionally, sediment liquefaction proves to be a possible mechanism for causing large and episodic sediment transport by water flow. Though computationally intense, our coupled...

  1. Determining Atmospheric Pressure Using a Water Barometer

    Science.gov (United States)

    Lohrengel, C. Frederick, II; Larson, Paul R.

    2012-01-01

    The atmosphere is an envelope of compressible gases that surrounds Earth. Because of its compressibility and nonuniform heating by the Sun, it is in constant motion. The atmosphere exerts pressure on Earth's surface, but that pressure is in constant flux. This experiment allows students to directly measure atmospheric pressure by measuring the…

  2. Evaluation of pressure transducers under turbid natural waters

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; Desa, E.; Desa, E.; Smith, D.; Peshwe, V.B.; VijayKumar, K.; Desa, J.A.E.

    , the use of rho sub(eff) in contrast to the bulk density, significantly improves the measurement accuracy. For celar waters, precision density measurements made on discrete water samples agreed with rho sub(eff) values derived from pressure measurements...

  3. Subglacial discharge at tidewater glaciers revealed by seismic tremor

    Science.gov (United States)

    Bartholomaus, Timothy C.; Amundson, Jason M.; Walter, Jacob I.; O'Neel, Shad; West, Michael E.; Larsen, Christopher F.

    2015-01-01

    Subglacial discharge influences glacier basal motion and erodes and redeposits sediment. At tidewater glacier termini, discharge drives submarine terminus melting, affects fjord circulation, and is a central component of proglacial marine ecosystems. However, our present inability to track subglacial discharge and its variability significantly hinders our understanding of these processes. Here we report observations of hourly to seasonal variations in 1.5–10 Hz seismic tremor that strongly correlate with subglacial discharge but not with basal motion, weather, or discrete icequakes. Our data demonstrate that vigorous discharge occurs from tidewater glaciers during summer, in spite of fast basal motion that could limit the formation of subglacial conduits, and then abates during winter. Furthermore, tremor observations and a melt model demonstrate that drainage efficiency of tidewater glaciers evolves seasonally. Glaciohydraulic tremor provides a means by which to quantify subglacial discharge variations and offers a promising window into otherwise obscured glacierized environments.

  4. The influence of Antarctic subglacial volcanism on the global iron cycle during the Last Glacial Maximum

    Science.gov (United States)

    Frisia, Silvia; Weyrich, Laura S.; Hellstrom, John; Borsato, Andrea; Golledge, Nicholas R.; Anesio, Alexandre M.; Bajo, Petra; Drysdale, Russell N.; Augustinus, Paul C.; Rivard, Camille; Cooper, Alan

    2017-06-01

    Marine sediment records suggest that episodes of major atmospheric CO2 drawdown during the last glacial period were linked to iron (Fe) fertilization of subantarctic surface waters. The principal source of this Fe is thought to be dust transported from southern mid-latitude deserts. However, uncertainty exists over contributions to CO2 sequestration from complementary Fe sources, such as the Antarctic ice sheet, due to the difficulty of locating and interrogating suitable archives that have the potential to preserve such information. Here we present petrographic, geochemical and microbial DNA evidence preserved in precisely dated subglacial calcites from close to the East Antarctic Ice-Sheet margin, which together suggest that volcanically-induced drainage of Fe-rich waters during the Last Glacial Maximum could have reached the Southern Ocean. Our results support a significant contribution of Antarctic volcanism to subglacial transport and delivery of nutrients with implications on ocean productivity at peak glacial conditions.

  5. Adaptive Reference Control for Pressure Management in Water Networks

    DEFF Research Database (Denmark)

    Kallesøe, Carsten; Jensen, Tom Nørgaard; Wisniewski, Rafal

    2015-01-01

    Water scarcity is an increasing problem worldwide and at the same time a huge amount of water is lost through leakages in the distribution network. It is well known that improved pressure control can lower the leakage problems. In this work water networks with a single pressure actuator and several....... Subsequently, these relations are exploited in an adaptive reference control scheme for the actuator pressure that ensures constant pressure at the critical points. Numerical experiments underpin the results. © Copyright IEEE - All rights reserved....

  6. Numerical modelling of esker formation in semi-circular subglacial channels

    Science.gov (United States)

    Beaud, Flavien; Flowers, Gwenn E.; Venditti, Jeremy G.

    2017-04-01

    Eskers hold valuable information about past subglacial hydraulic conditions in their spatial organization, geometry, and sedimentary structures. The relations between hydraulic conditions and esker properties are nevertheless intricate as the formation of eskers has been mainly inferred from descriptive theories, about which a consensus has yet to be reached. Eskers are prevalent in areas of rigid bed and thin till cover and their formation is thought to be predominantly controlled by either water or sediment availability. In this study, we develop a 1-D numerical model of sediment transport in semi-circular bedrock-floored channels to explore the physical processes leading to esker formation. The model encompasses channel evolution by melt-opening created by the viscous heat dissipated as water flows, the creep closure of the ice walls, and changes in cross-sectional area due to sediment accumulation and removal. We find that a bottleneck in sediment transport close to the terminus is an inherent characteristic of subglacial channels. Creep closure is reduced as the ice thins towards the terminus and hydraulic potential gradients decline, thus reducing shear stresses. This bottleneck is accentuated when water discharge drops in a well established channel. We find the conditions most conducive to sediment deposition are low ice-surface slopes within several kilometres of the terminus and water discharge fluctuations over a few to several weeks. The model also produces shear stresses large enough to transport boulders under typical melt-season conditions. Our results thus suggest that incipient eskers form toward the end of the melt season, provided water input and sediment supply are sufficient. Overall these findings corroborate the theory that eskers are formed progressively during the waning stage of an ice sheet, although we suggest that eskers are a natural manifestation of the subglacial hydraulic system in the presence of an adequate trade-off between

  7. Volume analysis of supercooled water under high pressure

    OpenAIRE

    Duki, Solomon F.; Tsige, Mesfin

    2016-01-01

    Motivated by recent experimental findings on the volume of supercooled water at high pressure [O. Mishima, J. Chem. Phys. 133, 144503 (2010)] we performed atomistic molecular dynamics simulations study of bulk water in the isothermal-isobaric ensemble. Cooling and heating cycles at different isobars and isothermal compression at different temperatures are performed on the water sample with pressures that range from 0 to 1.0 GPa. The cooling simulations are done at temperatures that range from...

  8. Lattuce growth and water use in closed, low pressure environment

    Science.gov (United States)

    Fowler, P.; Rygalov, V.; Wheeler, R.; Bucklin, R.; Schumacher, N.

    Lettuce (Lactuca sativa L.) cv. Waldmann's Green plants were grown in a clear, hemispherical enclosure at a reduced atmospheric pressure to study the potential for using low pressure greenhouses on planetary missions. The atmosphere was maintained at 25 kPa total pressure, with ˜20 kPa of N_2, ˜5 kPa of O_2, and between 0.1 and 0.2 kPa of CO_2, supplied by CO_2 injection and a feed-back control system. A closed water cycle was maintained inside the low pressure greenhouse by recycling condensed humidity back to the plants, and only adding external water to offset water vapor leakage and uptake in the plant tissue. All plants were grown in a granular, arcillite medium (calcined clay chips), with nutrients supplied by adding time-release fertilizer (Osmocote 20-20-20). Plants were harvested after 45 days, averaging 237 g fresh mass, and 23.7 g dry mass. No obvious adverse effects were noted on the plants, with the exception of some minor "tip-burn" injury to some leaves. Additional studies are planned to compare growth and water flux (evapotranspiration) rates at higher pressures. Preliminary results suggest that water fluxes should be lower at the higher pressures provided equal vapor pressure deficits can be maintained. The results suggest that vegetative crops such as lettuce should grow well at reduced pressures if adequate water, nutrients, and CO_2 are provided.

  9. Preliminary Analysis of Life within a Former Subglacial Lake Sediment in Antarctica

    Directory of Open Access Journals (Sweden)

    Gavin Burns

    2013-09-01

    Full Text Available Since the first descriptions of Antarctic subglacial lakes, there has been a growing interest and awareness of the possibility that life will exist and potentially thrive in these unique and little known environments. The unusual combination of selection pressures, and isolation from the rest of the biosphere, might have led to novel adaptations and physiology not seen before, or indeed to the potential discovery of relic populations that may have become extinct elsewhere. Here we report the first microbiological analysis of a sample taken from a former subglacial lake sediment in Antarctica (Lake Hodgson, on the Antarctic Peninsula. This is one of a number of subglacial lakes just emerging at the margins of the Antarctic ice sheet due to the renewed onset of deglaciation. Microbial diversity was divided into 23.8% Actinobacteria, 21.6% Proteobacteria, 20.2% Planctomycetes and 11.6% Chloroflexi, characteristic of a range of habitat types ( Overall, common sequences were neither distinctly polar, low temperature, freshwater nor marine. Twenty three percent of this diversity could only be identified to “unidentified bacterium”. Clearly these are diverse ecosystems with enormous potential.

  10. Geophysical investigations of subglacial Antarctic lakes: identifying drill sites for lake access

    Science.gov (United States)

    Woodward, J.; Tulaczyk, S. M.; Smith, A.; Walter, J.; Ross, N.; Fricker, H. A.; Siegert, M. J.; Pettersson, R.; Thoma, M.; Corr, H.; King, E. C.; Vaughan, D.

    2009-12-01

    Subglacial lakes are regarded as viable habitats for novel microbial life forms and may contain sedimentary palaeo-environmental records which would provide critical insights into the glacial history of Antarctica. In-situ sampling and analysis is the only way to explore these lake environments. In order to successfully plan access programs detailed geophysical investigations, in particular seismic measurements of water depth, are required to identify suitable drill sites. Prior to the austral summer of 2006/07 measurements of water depths only existed for Subglacial Lake Vostok, and spatial coverage was limited due to the size of the lake. More recently, active source seismic experiments have been carried out over three subglacial lakes, South Pole Lake, Subglacial Lake Ellsworth (SLE) and Subglacial Lake Whillans (SLW). With drilling programs now funded for SLW (access planned for 2011/12) and SLE (access planned for 2012/13) we present results from the geophysical experiments at SLE and SLW to allow the identification of primary drill sites. The two lakes are very different. Geophysical results from SLE suggest that the lake is over 155 m deep and has been a stable system for much of the Holocene. We propose that in order to optimize the chances of successful access and sampling, the entry site should be located in an area with a melting interface near the centre of the lake where water depths are in the order of 100 m. This is away from the down-lake end which shows a higher possibility for basal freezing, with the consequent risk to equipment deployment and retrieval. In contrast, SLW is characterized by dynamic filling and draining over short (2-3 year periods) and most likely has a shallow water column (currently estimated to be in the order of 5-10 m). We suggest that the most suitable location for access will be the centre of the elevation change anomaly recorded over the lake. This point is near equidistant from the lake shoreline features identified from

  11. High-pressure-induced water penetration into 3-isopropylmalate dehydrogenase

    Energy Technology Data Exchange (ETDEWEB)

    Nagae, Takayuki; Kawamura, Takashi [Nagoya University, (Japan); Chavas, Leonard M. G. [High Energy Research Organization (KEK), (Japan); Niwa, Ken; Hasegawa, Masashi [Nagoya University, (Japan); Kato, Chiaki [Japan Agency for Marine-Earth Science and Technology (JAMSTEC), (Japan); Watanabe, Nobuhisa, E-mail: nobuhisa@nagoya-u.jp [Nagoya University, (Japan); Nagoya University, (Japan)

    2012-03-01

    Structures of 3-isopropylmalate dehydrogenase were determined at pressures ranging from 0.1 to 650 MPa. Comparison of these structures gives a detailed picture of the swelling of a cavity at the dimer interface and the generation of a new cleft on the molecular surface, which are accompanied by water penetration. Hydrostatic pressure induces structural changes in proteins, including denaturation, the mechanism of which has been attributed to water penetration into the protein interior. In this study, structures of 3-isopropylmalate dehydrogenase (IPMDH) from Shewanella oneidensis MR-1 were determined at about 2 Å resolution under pressures ranging from 0.1 to 650 MPa using a diamond anvil cell (DAC). Although most of the protein cavities are monotonically compressed as the pressure increases, the volume of one particular cavity at the dimer interface increases at pressures over 340 MPa. In parallel with this volume increase, water penetration into the cavity could be observed at pressures over 410 MPa. In addition, the generation of a new cleft on the molecular surface accompanied by water penetration could also be observed at pressures over 580 MPa. These water-penetration phenomena are considered to be initial steps in the pressure-denaturation process of IPMDH.

  12. Assessment of water pipes durability under pressure surge

    Science.gov (United States)

    Pham Ha, Hai; Minh, Lanh Pham Thi; Tang Van, Lam; Bulgakov, Boris; Bazhenova, Soafia

    2017-10-01

    Surge phenomenon occurs on the pipeline by the closing valve or pump suddenly lost power. Due to the complexity of the water hammer simulation, previous researches have only considered water hammer on the single pipe or calculation of some positions on water pipe network, it have not been analysis for all of pipe on the water distribution systems. Simulation of water hammer due to closing valve on water distribution system and the influence level of pressure surge is evaluated at the defects on pipe. Water hammer on water supply pipe network are simulated by Water HAMMER software academic version and the capacity of defects are calculated by SINTAP. SINTAP developed from Brite-Euram projects in Brussels-Belgium with the aim to develop a process for assessing the integrity of the structure for the European industry. Based on the principle of mechanical fault, indicating the size of defects in materials affect the load capacity of the product in the course of work, the process has proposed setting up the diagram to fatigue assessment defect (FAD). The methods are applied for water pipe networks of Lien Chieu district, Da Nang city, Viet Nam, the results show the affected area of wave pressure by closing the valve and thereby assess the greatest pressure surge effect to corroded pipe. The SINTAP standard and finite element mesh analysis at the defect during the occurrence of pressure surge which will accurately assess the bearing capacity of the old pipes. This is one of the bases to predict the leakage locations on the water distribution systems. Amount of water hammer when identified on the water supply networks are decreasing due to local losses at the nodes as well as the friction with pipe wall, so this paper adequately simulate water hammer phenomena applying for actual water distribution systems. The research verified that pipe wall with defect is damaged under the pressure surge value.

  13. Performance Evaluation of Pressure Transducers for Water Impacts

    Science.gov (United States)

    Vassilakos, Gregory J.; Stegall, David E.; Treadway, Sean

    2012-01-01

    The Orion Multi-Purpose Crew Vehicle is being designed for water landings. In order to benchmark the ability of engineering tools to predict water landing loads, test programs are underway for scale model and full-scale water impacts. These test programs are predicated on the reliable measurement of impact pressure histories. Tests have been performed with a variety of pressure transducers from various manufacturers. Both piezoelectric and piezoresistive devices have been tested. Effects such as thermal shock, pinching of the transducer head, and flushness of the transducer mounting have been studied. Data acquisition issues such as sampling rate and anti-aliasing filtering also have been studied. The response of pressure transducers have been compared side-by-side on an impulse test rig and on a 20-inch diameter hemisphere dropped into a pool of water. The results have identified a range of viable configurations for pressure measurement dependent on the objectives of the test program.

  14. Bridge pressure flow scour for clear water conditions

    Science.gov (United States)

    2009-10-01

    The equilibrium scour at a bridge caused by pressure flow with critical approach velocity in clear-water simulation conditions was studied both analytically and experimentally. The flume experiments revealed that (1) the measured equilibrium scour pr...

  15. Capital Cost: Pressurized Water Reactor Plant Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    1977-06-01

    The investment cost study for the 1139-MW(e) pressurized water reactor (PWR) central station power plant consists of two volumes. This volume includes in addition to the foreword and summary, the plant description and the detailed cost estimate.

  16. Microscale evidence of liquefaction and its potential triggers during soft-bed deformation within subglacial traction tills

    Science.gov (United States)

    Phillips, Emrys R.; Evans, David J. A.; van der Meer, Jaap J. M.; Lee, Jonathan R.

    2018-02-01

    Published conceptual models argue that much of the forward motion of modern and ancient glaciers is accommodated by deformation of soft-sediments within the underlying bed. At a microscale this deformation results in the development of a range of ductile and brittle structures in water-saturated sediments as they accommodate the stresses being applied by the overriding glacier. Detailed micromorphological studies of subglacial traction tills reveal that these polydeformed sediments may also contain evidence of having undergone repeated phases of liquefaction followed by solid-state shear deformation. This spatially and temporally restricted liquefaction of subglacial traction tills lowers the shear strength of the sediment and promotes the formation of "transient mobile zones" within the bed, which accommodate the shear imposed by the overriding ice. This process of soft-bed sliding, alternating with bed deformation, facilitates glacier movement by way of 'stick-slip' events. The various controls on the slip events have previously been identified as: (i) the introduction of pressurised meltwater into the bed, a process limited by the porosity and permeability of the till; and (ii) pressurisation of porewater as a result of subglacial deformation; to which we include (iii) episodic liquefaction of water-saturated subglacial traction tills in response to glacier seismic activity (icequakes), which are increasingly being recognized as significant processes in modern glaciers and ice sheets. As liquefaction operates only in materials already at very low values of effective stress, its process-form signatures are likely indicative of glacier sub-marginal tills.

  17. Antarctic Active Subglacial Lake Inventory from ICESat Altimetry, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains lake boundaries, volume changes, and gridded elevations for 124 active subglacial lakes beneath the Antarctic ice sheet. Lakes were identified...

  18. Observations and modelling of subglacial discharge and heat transport in Godthåbsfjord (Greenland, 64 °N)

    Science.gov (United States)

    Bendtsen, Jørgen; Mortensen, John; Rysgaard, Søren

    2017-04-01

    Subglacial discharge from tidewater outlet glaciers forms convective bouyant freshwater plumes ascending close the glacier face, and entrainment of ambient bottom water increases the salinity of the water until the plume reaches its level of neutral buoyancy at sub-surface levels or reaches the surface. Relatively warm bottom water masses characterize many fjords around Greenland and therefore entrainment would also increase the temperature in the plumes and, thereby, impact the heat transport in the fjords. However, relatively few oceanographic measurements have been made in or near plumes from subglacial discharge and, therefore, the potential for subglacial discharge for increasing heat transport towards the tidewater outlet glaciers are poorly understood. We present the first direct hydrographic measurements in a plume from subglacial discharge in Godthåbsfjord (located on the western coast of Greenland) where a XCTD was launched from a helicopter directly into the plume. Measurements of the surface salinity showed that the plume only contained 7% of freshwater at the surface, implying a large entrainment with a mixing ratio of 1:13 between outflowing meltwater and saline fjord water. These observations are analyzed together with seasonal observations of ocean heat transport towards the tidewater outlet glaciers in Godthåbsfjord and we show that subglacial discharge only had modest effects on the overall heat budget in front of the glacier. These results were supported from a high-resolution three-dimensional model of Godthåbsfjord. The model explicitly considered subglacial freshwater discharge from three tidewater outlet glaciers where entrainment of bottom water was taken into account. Model results showed that subglacial discharge only affected the fjord circulation relatively close ( 10 km) to the glaciers. Thus, the main effect on heat transport was due to the freshwater discharge itself whereas the subsurface discharge and associated entrainment only

  19. Subglacial discharges create fluctuating foraging hotspots for sea birds in tidewater glacier bays

    Science.gov (United States)

    Urbanski, Jacek Andrzej; Stempniewicz, Lech; Węsławski, Jan Marcin; Dragańska-Deja, Katarzyna; Wochna, Agnieszka; Goc, Michał; Iliszko, Lech

    2017-01-01

    Although the processes occurring at the front of an ice face in tidewater glacier bays still await thorough investigation, their importance to the rapidly changing polar environment is spurring a considerable research effort. Glacier melting, sediment delivery and the formation of seabird foraging hotspots are governed by subglacial discharges of meltwater. We have combined the results of tracking black-legged kittiwakes Rissa tridactyla equipped with GPS loggers, analyses of satellite images and in situ measurements of water temperature, salinity and turbidity in order to examine the magnitude and variability of such hotspots in the context of glacier bay hydrology. Small though these hotspots are in size, foraging in them appears to be highly intensive. They come into existence only if the subglacial discharge reaches the surface, if the entrainment velocity at a conduit is high and if there is sufficient macroplankton in the entrainment layer. The position and type of subglacial discharges may fluctuate in time and space, thereby influencing glacier bay hydrology and the occurrence of foraging hotspots. PMID:28266602

  20. Subglacial discharges create fluctuating foraging hotspots for sea birds in tidewater glacier bays

    Science.gov (United States)

    Urbanski, Jacek Andrzej; Stempniewicz, Lech; Węsławski, Jan Marcin; Dragańska-Deja, Katarzyna; Wochna, Agnieszka; Goc, Michał; Iliszko, Lech

    2017-03-01

    Although the processes occurring at the front of an ice face in tidewater glacier bays still await thorough investigation, their importance to the rapidly changing polar environment is spurring a considerable research effort. Glacier melting, sediment delivery and the formation of seabird foraging hotspots are governed by subglacial discharges of meltwater. We have combined the results of tracking black-legged kittiwakes Rissa tridactyla equipped with GPS loggers, analyses of satellite images and in situ measurements of water temperature, salinity and turbidity in order to examine the magnitude and variability of such hotspots in the context of glacier bay hydrology. Small though these hotspots are in size, foraging in them appears to be highly intensive. They come into existence only if the subglacial discharge reaches the surface, if the entrainment velocity at a conduit is high and if there is sufficient macroplankton in the entrainment layer. The position and type of subglacial discharges may fluctuate in time and space, thereby influencing glacier bay hydrology and the occurrence of foraging hotspots.

  1. Experimental Study and Engineering Practice of Pressured Water Coupling Blasting

    Directory of Open Access Journals (Sweden)

    J. X. Yang

    2017-01-01

    Full Text Available Overburden strata movement in large space stope is the major reason that induces the appearance of strong mining pressure. Presplitting blasting for hard coal rocks is crucial for the prevention and control of strong pressure in stope. In this study, pressured water coupling blasting technique was proposed. The process and effect of blasting were analyzed by orthogonal test and field practice. Results showed that the presence of pressure-bearing water and explosive cartridges in the drill are the main influence factors of the blasting effect of cement test block. The high load-transmitting performance of pore water and energy accumulation in explosive cartridges were analyzed. Noxious substances produced during the blasting process were properly controlled because of the moistening, cooling, and diluting effect of pore water. Not only the goal of safe and static rock fragmentation by high-explosive detonation but also a combination of superdynamic blast loading and static loading effect of the pressured water was achieved. Then the practice of blasting control of hard coal rocks in Datong coal mine was analyzed to determine reasonable parameters of pressured water coupling blasting. A good presplitting blasting control effect was achieved for the hard coal rocks.

  2. Fresh Water Generation from Aquifer-Pressured Carbon Storage

    Energy Technology Data Exchange (ETDEWEB)

    Aines, R D; Wolery, T J; Bourcier, W L; Wolfe, T; Haussmann, C

    2010-02-19

    Can we use the pressure associated with sequestration to make brine into fresh water? This project is establishing the potential for using brine pressurized by Carbon Capture and Storage (CCS) operations in saline formations as the feedstock for desalination and water treatment technologies including reverse osmosis (RO) and nanofiltration (NF). Possible products are: Drinking water, Cooling water, and Extra aquifer space for CO{sub 2} storage. The conclusions are: (1) Many saline formation waters appear to be amenable to largely conventional RO treatment; (2) Thermodynamic modeling indicates that osmotic pressure is more limiting on water recovery than mineral scaling; (3) The use of thermodynamic modeling with Pitzer's equations (or Extended UNIQUAC) allows accurate estimation of osmotic pressure limits; (4) A general categorization of treatment feasibility is based on TDS has been proposed, in which brines with 10,000-85,000 mg/L are the most attractive targets; (5) Brines in this TDS range appear to be abundant (geographically and with depth) and could be targeted in planning future CCS operations (including site selection and choice of injection formation); and (6) The estimated cost of treating waters in the 10,000-85,000 mg/L TDS range is about half that for conventional seawater desalination, due to the anticipated pressure recovery.

  3. Cavitation nuclei in water exposed to transient pressures

    DEFF Research Database (Denmark)

    Andersen, Anders Peter; Mørch, Knud Aage

    2015-01-01

    A model of skin-stabilized interfacial cavitation nuclei and their response to tensile and compressive stressing is presented. The model is evaluated in relation to experimental tensile strength results for water at rest at the bottom of an open water-filled container at atmospheric pressure...... and room temperature. These results are obtained by recording the initial growth of cavities generated by a short tensile pulse applied to the bottom of the container. It is found that the cavitation nuclei shift their tensile strength depending on their pressure history. Static pressurization...

  4. NATIONAL SEISMIC, RADAR AND SEISMOLOGICAL STUDIES OF SUBGLACIAL LAKE VOSTOK

    Directory of Open Access Journals (Sweden)

    S. V. Popov

    2012-01-01

    Full Text Available The results of the remote sensing which carried out in the LakeVostokarea are discussed in the paper. A.P. Kapitsa and O.G. Sorokhtin started the geophysical researches in this area in 1950s. Satellite altimetry data, which analyzed in 1990s yielded to the discovering of the LakeVostok. After that, PMGE and RAE started the systematic studying of this natural phenomenon by seismic and radio-echo sounding. Total, 318 seismic soundings and 5190 kmof the radio-echo profiles has been collected by 2008. Special precise measurements which carried out in the 5G-1 borehole vicinity are resulted in the ice thickness over Vostok Station is 3760±30 mby seismic and 3775±15 mby radio-echo sounding. Thus, the error of geophysical measurements is less than 0.3%. The Russian investigations are resulted in definition the border of the lake, the discovering of 56 subglacial water caves around the lake and compilation the maps including ice thickness, ice base and bedrock topography and the depth of the lake. Average depth of the LakeVostokis about 400 m; water volume is 6100 km3. After 2008, the remote sensing works have been concentrated to the studying of the bottom sediments by refraction seismic technique. The firsts result shown that the bottom sediments thickness varies from 400 to1200 m.

  5. Investigating the hydrological origins of Blood Falls - geomicrobiological insights into a briny subglacial Antarctic aquifer

    Science.gov (United States)

    Mikucki, J.; Tulaczyk, S. M.; Purcell, A. M.; Dachwald, B.; Lyons, W. B.; Welch, K. A.; Auken, E.; Dugan, H. A.; Walter, J. I.; Pettit, E. C.; Doran, P. T.; Virginia, R. A.; Schamper, C.; Foley, N.; Feldmann, M.; Espe, C.; Ghosh, D.; Francke, G.

    2015-12-01

    Subglacial waters tend to accumulate solutes from extensive rock-water interactions, which, when released to the surface, can provide nutrients to surface ecosystems providing a 'hot spot' for microbial communities. Blood Falls, an iron-rich, saline feature at the terminus of Taylor Glacier in the McMurdo Dry Valleys, Antarctica is a well-studied subglacial discharge. Here we present an overview of geophysical surveys, thermomechanical drilling exploration and geomicrobiological analyses of the Blood Falls system. A helicopter-borne transient electromagnetic system (SkyTEM) flown over the Taylor Glacier revealed a surprisingly extensive subglacial aquifer and indicates that Blood Falls may be the only surface manifestation of this extensive briny groundwater. Ground-based temperature sensing and GPR data combined with the helicopter-borne TEM data enabled targeted drilling into the englacial conduit that delivers brine to the surface. During the 2014-15 austral summer field season, we used a novel ice-melting drill (the IceMole) to collect englacial brine for geomicrobiological analyses. Results from previously collected outflow and more recent samples indicate that the brine harbors a metabolically active microbial community that persists, despite cold, dark isolation. Isotope geochemistry and molecular analysis of functional genes from BF suggested that a catalytic or 'cryptic' sulfur cycle was linked to iron reduction. Recent metagenomic analysis confirms the presence of numerous genes involved in oxidative and reductive sulfur transformations. Metagenomic and metabolic activity data also indicate that subglacial dark CO2 fixation occurs via various pathways. Genes encoding key steps in CO2 fixation pathways including the Calvin Benson Basham and Wood Ljungdahl pathway were present and brine samples showed measureable uptake of 14C-labeled bicarbonate. These results support the notion that, like the deep subsurface, subglacial environments are chemosynthetic

  6. Undermoderated spectrum MOX core study. Supercritical pressure light water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Oka, Yoshiaki; Kosizuka, Seiichi [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

    1998-09-01

    The supercritical pressure light water cooling reactor is a nuclear reactor concept with the once through type and the direct cycle reactor cooled with supercritical pressure water. The cooling water controlled with the feed pump flows directly to the turbine and a recirculation is never done by the nuclear reactor of this type. Therefore, this system isn`t equipped with the recirculation system and the steam separator, the system becomes simple. As for this system, it is expected that the cost performance improves. Here, the outline of former study is described. (author)

  7. Pressure caused by underwater discharge near the surface of water

    Science.gov (United States)

    Kusakabe, K.; Uchiyama, M.; Isuzugawa, Kohji

    2001-04-01

    Spark discharge in water generates a spherical shock wave and a bubble that contains water vapor, with each center at a gap between electrodes. The bubble repeats the movement of the expansion and contraction. An impulsive pressure wave also arises at each transition from the contraction to the expansion of the bubble. In case that a rigid wall exists near the bubble, the bubble moves toward it keeping the expansion and contraction and then a water jet is formed toward the wall. The jet exerts the impulsive pressure on the wall. In case that the bubble is near the surface of water, it moves as if a rigid wall existed just below it and then the downward water jet is also formed. We are interested in the relationship of the movement of the bubble to the effect of the pressure caused by the under-water discharge near the surface of water. We are also interested in whether there are some differences between the following two cases as to the effect of pressure; one case is that the bubble exists near the surface of water and its movement is affected by the surface, another case the movement of the bubble is not affected by the surface of water for the sake of enough large distance between the bubble and the surface. In this study, impulsive pressure waves caused by the under-water discharge in above two cases are observed by means of a transducer or their schlieren photographs are taken with an image converter camera, and observations are examined.

  8. Small scale high resolution LiDAR measurements of a subglacial conduit

    Science.gov (United States)

    Mankoff, K. D.; Gulley, J.

    2012-04-01

    We present direct measurements of surface roughness in a sub-glacial conduit system underneath the Rieperbreen Glacier, Svalbard, Norway. Data was collected with a low-cost (129 USD) Microsoft Kinect video game device used as a LIDAR sensor. Surface roughness is a primary control on water flow in rivers, channels, and cave conduit systems and understanding the effects of surface roughness on water flow has been problematic due to lack of direct measurements of roughness in natural systems. We use the ice scallop dimensions to derive flow velocity and explore implications of the changing roughness parameters as the cave grows and shrinks.

  9. Glycerin Reformation in High Temperature and Pressure Water

    Science.gov (United States)

    2012-01-01

    hygroscopic, while ethanol is renewable and non-toxic (94). Water has a detrimental effect on the reaction because soaps can be formed, which cause...Lavric, V. (2005) Delocalized organic pollutant destruction through a self-sustaining supercritical water oxidation process, Energy Conversion and...2012 2. REPORT TYPE 3. DATES COVERED 00-00-2012 to 00-00-2012 4. TITLE AND SUBTITLE Glycerin Reformation in High Temperature and Pressure Water

  10. The Subglacial Access and Fast Ice Research Experiment - SAFIRE - on Store Glacier, West Greenland

    Science.gov (United States)

    Christoffersen, P.; Hubbard, B. P.; Doyle, S. H.; Young, T. J.; Hofstede, C. M.; Bougamont, M. H.; Todd, J.; Toberg, N.; Nicholls, K. W.; Box, J.; Walter, J. I.; Hubbard, A.

    2015-12-01

    Marine-terminating outlet glaciers drain 90 percent of the Greenland Ice Sheet and are responsible for about half of the ice sheet's net annual mass loss, which currently raises global sea level by 1 mm per year. The basal controls on these fast-flowing glaciers are, however, poorly understood, with the implication that numerical ice sheet models needed to predict future dynamic ice loss from Greenland relies on uncertain and often untested basal parameterizations. The Subglacial Access and Fast Ice Research Experiment - SAFIRE - is addressing this paucity of observational constraints by drilling to the bed of Store Glacier, a fast-flowing outlet glacier terminating in Uummannaq Fjord, West Greenland. In 2014, we gained access to the bed in four boreholes drilled to depths of 603-616 m near the center of the glacier, 30 km inland from the calving terminus where ice flows at a rate of 700 m/year. A seismic survey showed the glacier bed to consist of water-saturated, soft sediment. The water level in all four boreholes nevertheless dropped rapidly to 80 m below the ice surface when the drill connected with a basal water system, indicating effective drainage over a sedimentary bed. We were able to install wired sensor strings at the bed (water pressure, temperature, electrical conductivity and turbidity) and within the glacier (temperature and tilt) in three boreholes. The sensors operated for up to 80+ days before cables stretched and ultimately snapped due to high internal strain. The data collected during this sensor deployment show ice as cold as -21 degrees Celcius; yet, temperature of water in the basal water system was persistently above the local freezing point. With diurnal variations detected in several sensor records, we hypothesise that surface water lubricates the ice flow while also warming basal ice. The fast basal motion of Store Glacier not only occurs by basal sliding, but from high rates of concentrated strain in the bottom third of the glacier

  11. Water Pressure Distribution on a Twin-Float Seaplane

    Science.gov (United States)

    Thompson, F L

    1930-01-01

    This is the second of a series of investigations to determine water pressure distribution on various types of seaplane floats and hulls, and was conducted on a twin-float seaplane. It consisted of measuring water pressures and accelerations on a TS-1 seaplane during numerous landing and taxiing maneuvers at various speeds and angles. The results show that water pressures as great as 10 lbs. per sq. in.may occur at the step in various maneuvers and that pressures of approximately the same magnitude occur at the stern and near the bow in hard pancake landings with the stern way down. At the other parts of the float the pressures are less and are usually zero or slightly negative for some distance abaft the step. A maximum negative pressure of 0.87 lb. Per square inch was measured immediately abaft the step. The maximum positive pressures have a duration of approximately one-twentieth to one-hundredth second at any given location and are distributed over a very limited area at any particular instant.

  12. Water cycles in closed ecological systems: effects of atmospheric pressure.

    Science.gov (United States)

    Rygalov, Vadim Y; Fowler, Philip A; Metz, Joannah M; Wheeler, Raymond M; Bucklin, Ray A

    2002-01-01

    In bioregenerative life support systems that use plants to generate food and oxygen, the largest mass flux between the plants and their surrounding environment will be water. This water cycle is a consequence of the continuous change of state (evaporation-condensation) from liquid to gas through the process of transpiration and the need to transfer heat (cool) and dehumidify the plant growth chamber. Evapotranspiration rates for full plant canopies can range from ~1 to 10 L m-2 d-1 (~1 to 10 mm m-2 d-1), with the rates depending primarily on the vapor pressure deficit (VPD) between the leaves and the air inside the plant growth chamber. VPD in turn is dependent on the air temperature, leaf temperature, and current value of relative humidity (RH). Concepts for developing closed plant growth systems, such as greenhouses for Mars, have been discussed for many years and the feasibility of such systems will depend on the overall system costs and reliability. One approach for reducing system costs would be to reduce the operating pressure within the greenhouse to reduce structural mass and gas leakage. But managing plant growth environments at low pressures (e.g., controlling humidity and heat exchange) may be difficult, and the effects of low-pressure environments on plant growth and system water cycling need further study. We present experimental evidence to show that water saturation pressures in air under isothermal conditions are only slightly affected by total pressure, but the overall water flux from evaporating surfaces can increase as pressure decreases. Mathematical models describing these observations are presented, along with discussion of the importance for considering "water cycles" in closed bioregenerative life support systems.

  13. Investigating the potential for "water piracy" in North East Greenland

    Science.gov (United States)

    Karlsson, Nanna B.; Dahl-Jensen, Dorthe

    2013-04-01

    The incorporation of subglacial processes in ice flow models remains a challenge while at the same time observational evidence increasingly underscores the important role liquid water plays in ice flow dynamics. One of the many problems ice flow models face (that also includes scarcity of data at the bed and the deformational properties of water-saturated sediments) is the different time-scales on which the processes operate. For example, observations indicate that subglacial water may be re-routed to a neighbouring ice stream in response to changes in surface elevation. This implies that ice flow models have to allow for changes in ice flow mode where, depending on the basal properties, the flow may be dominated by deformation or basal sliding. The re-routing of water between neighbouring ice streams is often termed "water piracy" and in this study we demonstrate that the potential for water piracy exists even in regions with very small surface elevation changes. We use a simple, vertically integrated, 2D-plane ice flow model based on the shallow ice flow approximation to model the large-scale changes in surface elevation of North East Greenland in response to gravity and mass balance. Considering time-scales of 100-500 years the model predicts changes in elevation of less than a metre per year which is in agreement with data from remote sensing. We then calculate the corresponding changes in hydrological pressure potential and use evidence from radio-echo sounding data to identify areas with basal melting and thus potential liquid water production. The corresponding change in hydrological pressure potential in response to the surface elevation changes is sufficient to divert the subglacial water to different pathways. This change in subglacial water pathways could be sufficient to change the ice flow mode from deformation to sliding and might initiate speed-up and/or slow-down of the ice streams at the margins of the basin.

  14. Design of virtual SCADA simulation system for pressurized water reactor

    Science.gov (United States)

    Wijaksono, Umar; Abdullah, Ade Gafar; Hakim, Dadang Lukman

    2016-02-01

    The Virtual SCADA system is a software-based Human-Machine Interface that can visualize the process of a plant. This paper described the results of the virtual SCADA system design that aims to recognize the principle of the Nuclear Power Plant type Pressurized Water Reactor. This simulation uses technical data of the Nuclear Power Plant Unit Olkiluoto 3 in Finland. This device was developed using Wonderware Intouch, which is equipped with manual books for each component, animation links, alarm systems, real time and historical trending, and security system. The results showed that in general this device can demonstrate clearly the principles of energy flow and energy conversion processes in Pressurized Water Reactors. This virtual SCADA simulation system can be used as instructional media to recognize the principle of Pressurized Water Reactor.

  15. Design of virtual SCADA simulation system for pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Wijaksono, Umar, E-mail: umar.wijaksono@student.upi.edu; Abdullah, Ade Gafar; Hakim, Dadang Lukman [Electrical Power System Research Group, Department of Electrical Engineering Education, Jl. Dr. Setiabudi No. 207 Bandung, Indonesia 40154 (Indonesia)

    2016-02-08

    The Virtual SCADA system is a software-based Human-Machine Interface that can visualize the process of a plant. This paper described the results of the virtual SCADA system design that aims to recognize the principle of the Nuclear Power Plant type Pressurized Water Reactor. This simulation uses technical data of the Nuclear Power Plant Unit Olkiluoto 3 in Finland. This device was developed using Wonderware Intouch, which is equipped with manual books for each component, animation links, alarm systems, real time and historical trending, and security system. The results showed that in general this device can demonstrate clearly the principles of energy flow and energy conversion processes in Pressurized Water Reactors. This virtual SCADA simulation system can be used as instructional media to recognize the principle of Pressurized Water Reactor.

  16. Experiments on aerosol removal by high-pressure water spray

    Energy Technology Data Exchange (ETDEWEB)

    Corno, Ada del, E-mail: delcorno@rse-web.it [RSE, Power Generation Technologies and Materials Dept, via Rubattino 54, I-20134 Milano (Italy); Morandi, Sonia, E-mail: morandi@rse-web.it [RSE, Power Generation Technologies and Materials Dept, via Rubattino 54, I-20134 Milano (Italy); Parozzi, Flavio, E-mail: parozzi@rse-web.it [RSE, Power Generation Technologies and Materials Dept, via Rubattino 54, I-20134 Milano (Italy); Araneo, Lucio, E-mail: lucio.araneo@polimi.it [Politecnico di Milano, Department of Energy, via Lambruschini 4A, I-20156 Milano (Italy); CNR-IENI, via Cozzi 53, I-20125 Milano (Italy); Casella, Francesco, E-mail: francesco2.casella@mail.polimi.it [Politecnico di Milano, Department of Energy, via Lambruschini 4A, I-20156 Milano (Italy)

    2017-01-15

    Highlights: • Experimental research to measure the efficiency of high-pressure sprays in capturing aerosols if applied to a filtered containment venting system in case of severe accident. • Cloud of monodispersed SiO{sub 2} particles with sizes 0.5 or 1.0 μm and initial concentration in the range 2–90 mg/m{sup 3}. • Carried out in a chamber 0.5 × 1.0 m and 1.5 m high, with transparent walls equipped with a high pressure water spray with single nozzle. • Respect to low-pressure sprays, removal efficiency turned out significant: the half-life for 1 μm particles with a removal high-pressure spray system is orders of magnitude shorter than that with a low-pressure sprays system. - Abstract: An experimental research was managed in the framework of the PASSAM European Project to measure the efficiency of high-pressure sprays in capturing aerosols when applied to a filtered containment venting system in case of severe accident. The campaign was carried out in a purposely built facility composed by a scrubbing chamber 0.5 × 1.0 m and 1.5 m high, with transparent walls to permit the complete view of the aerosol removal process, where the aerosol was injected to form a cloud of specific particle concentration. The chamber was equipped with a high pressure water spray system with a single nozzle placed on its top. The test matrix consisted in the combination of water pressure injections, in the range 50–130 bar, on a cloud of monodispersed SiO{sub 2} particles with sizes 0.5 or 1.0 μm and initial concentration ranging between 2 and 99 mg/m{sup 3}. The spray was kept running for 2 min and the efficiency of the removal was evaluated, along the test time, using an optical particle sizer. With respect to low-pressure sprays, the removal efficiency turned out much more significant: the half-life for 1 μm particles with a removal high-pressure spray system is orders of magnitude shorter than that with a low-pressure spray system. The highest removal rate was

  17. Supercritical water gasification with decoupled pressure and heat transfer modules

    KAUST Repository

    Dibble, Robert

    2017-09-14

    The present invention discloses a system and method for supercritical water gasification (SCWG) of biomass materials wherein the system includes a SCWG reactor and a plurality of heat exchangers located within a shared pressurized vessel, which decouples the function of containing high pressure from the high temperature function. The present invention allows the heat transfer function to be conducted independently from the pressure transfer function such that the system equipment can be designed and fabricated in manner that would support commercial scaled-up SCWG operations. By using heat exchangers coupled to the reactor in a series configuration, significant efficiencies are achieved by the present invention SCWG system over prior known SCWG systems.

  18. Height changes over subglacial Lake Vostok, East Antarctica: Insights from GNSS observations

    National Research Council Canada - National Science Library

    Richter, Andreas; Popov, Sergey V; Fritsche, Mathias; Lukin, Valery V; Matveev, Alexey Yu; Ekaykin, Alexey A; Lipenkov, Vladimir Ya; Fedorov, Denis V; Eberlein, Lutz; Schröder, Ludwig; Ewert, Heiko; Horwath, Martin; Dietrich, Reinhard

    2014-01-01

    Height changes of the ice surface above subglacial Lake Vostok, East Antarctica, reflect the integral effect of different processes within the subglacial environment and the ice sheet. Repeated GNSS...

  19. Methodology for surge pressure evaluation in a water injection system

    Energy Technology Data Exchange (ETDEWEB)

    Meliande, Patricia; Nascimento, Elson A. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Civil; Mascarenhas, Flavio C.B. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Lab. de Hidraulica Computacional; Dandoulakis, Joao P. [SHELL of Brazil, Rio de Janeiro, RJ (Brazil)

    2009-07-01

    Predicting transient effects, known as surge pressures, is of high importance for offshore industry. It involves detailed computer modeling that attempts to simulate the complex interaction between flow line and fluid in order to ensure efficient system integrity. Platform process operators normally raise concerns whether the water injection system is adequately designed or not to be protected against possible surge pressures during sudden valve closure. This report aims to evaluate the surge pressures in Bijupira and Salema water injection systems due to valve closure, through a computer model simulation. Comparisons among the results from empirical formulations are discussed and supplementary analysis for Salema system were performed in order to define the maximum volumetric flow rate for which the design pressure was able to withstand. Maximum surge pressure values of 287.76 bar and 318.58 bar, obtained in Salema and Bijupira respectively, using empirical formulations have surpassed the operating pressure design, while the computer model results have pointed the greatest surge pressure value of 282 bar in Salema system. (author)

  20. Fracture analysis of axially cracked pressure tube of pressurized heavy water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, S.; Bhasin, V.; Mahajan, S.C. [Bhabha Atomic Research Centre, Bombay (India)] [and others

    1997-04-01

    Three Dimensional (313) finite element elastic plastic fracture analysis was done for through wall axially cracked thin pressure tubes of 220 MWe Indian Pressurized Heavy Water Reactor. The analysis was done for Zr-2 and Zr-2.5Nb pressure tubes operating at 300{degrees}C and subjected to 9.5 Mpa internal pressure. Critical crack length was determined based on tearing instability concept. The analysis included the effect of crack face pressure due to the leaking fluid from tube. This effect was found to be significant for pressure tubes. The available formulae for calculating J (for axially cracked tubes) do not take into account the effect of crack face pressure. 3D finite element analysis also gives insight into variation of J across the thickness of pressure tube. It was observed that J is highest at the mid-surface of tube. The results have been presented in the form of across the thickness average J value and a peak factor on J. Peak factor on J is ratio of J at mid surface to average J value. Crack opening area for different cracked lengths was calculated from finite element results. The fracture assessment of pressure tubes was also done using Central Electricity Generating Board R-6 method. Ductile tearing was considered.

  1. Seismic Tremor Reveals Subglacial Discharge at Tidewater Glaciers

    Science.gov (United States)

    Bartholomaus, T. C.; Larsen, C. F.; O'Neel, S.; West, M. E.; Amundson, J. M.; Walter, J. I.; Catania, G. A.; Stearns, L. A.; Walker, R. T.; Sutherland, D.; Shroyer, E.; Nash, J. D.

    2014-12-01

    Subglacial discharge from the termini of tidewater glaciers drives submarine terminus melting, influences fjord circulation, erodes and redeposits subglacial sediment, and is a central component of proglacial marine ecosystems. The timing and variability of subglacial discharge can also exert a strong influence on the upstream flow of tidewater glaciers through hydrology-mediated changes in basal motion. However, a lack of observations of subglacial discharge at the ice-ocean interface hinders progress in understanding these processes and contributes to some of the largest uncertainties in sea level rise projections. Here we demonstrate that passive seismic observations collected adjacent to glaciers can meet this observational need. At tidewater and lake-terminating glaciers in Alaska and Greenland, we observe hourly to seasonal variations in low-amplitude, background seismic noise, termed glacio-hydraulic tremor. Variations in tremor amplitude correlate with discharge during the drainage of a glacially-dammed lake and reveal increases in discharge efficiency over the course of the melt season. Recordings of glacio-hydraulic tremor across a range of settings suggest widespread utility for our method. Reliable prediction of future sea level rise requires observations of subglacial discharge that elicit physical insight and can validate models. Our findings provide a platform for new understanding of ice-ocean interactions and related oceanographic, geologic, and ecological disciplines.

  2. Disjoining pressure isotherms of water-in-bitumen emulsion films.

    Science.gov (United States)

    Taylor, Shawn D; Czarnecki, Jan; Masliyah, Jacob

    2002-08-01

    In the oil sands industry, undesirable water-in-oil emulsions are often formed during the bitumen recovery process where water is used to liberate bitumen from sand grains. Nearly all of the water is removed except for a small percentage (approximately 1 to 2%), which remains in the solvent-diluted bitumen as micrometer-sized droplets. Knowledge of the colloidal forces that stabilized these water droplets would help to increase our understanding of how these emulsions are stabilized. In this study, the thin liquid film-pressure balance technique has been used to measure isotherms of disjoining pressure in water/toluene-diluted bitumen/water films at five different toluene-bitumen mass ratios. Even though a broad range of mass ratios was studied, only two isotherms are obtained, indicating a possible change in the molecular orientation of surfactant molecules at the bitumen/water interfaces. At low toluene-bitumen mass ratios, the film stability appears to be due to a strong, short-range steric repulsion created by a surfactant bilayer. Similar isotherms were obtained for water/toluene-diluted asphaltene/water films, indicating that the surface active material at the interface probably originated from the asphaltene fraction of the bitumen. However, unlike the bitumen films, films of toluene-diluted asphaltenes often formed very rigid interfaces similar to the "protective skin" described by other researcher.

  3. A study of water pressure influence on failure of large diameter water pipelines

    OpenAIRE

    Rathnayaka, Suranji Uditha Priyankara

    2017-01-01

    This research is part of a large research project investigating how, when, and where critical pipes (diameter≥300mm) fail in water supply networks. The failure of large- diameter pipe is critical, as it may have devastating consequences for both the public and the water utility. Factors contributing to pipe failure, such as internal pressure, external load, and corrosion, are examined in this research. The objective of the study is to understand the contribution of internal water pressur...

  4. Ultra-high pressure water jet: Baseline report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-07-31

    The ultra-high pressure waterjet technology was being evaluated at Florida International University (FIU) as a baseline technology. In conjunction with FIU`s evaluation of efficiency and cost, this report covers the evaluation conducted for safety and health issues. It is a commercially available technology and has been used for various projects at locations throughout the country. The ultra-high pressure waterjet technology acts as a cutting tool for the removal of surface substrates. The Husky{trademark} pump feeds water to a lance that directs the high pressure water at the surface to be removed. The safety and health evaluation during the testing demonstration focused on two main areas of exposure. These were dust and noise. The dust exposure was found to be minimal, which would be expected due to the wet environment inherent in the technology, but noise exposure was at a significant level. Further testing for noise is recommended because of the outdoor environment where the testing demonstration took place. In addition, other areas of concern found were arm-hand vibration, ergonomics, heat stress, tripping hazards, electrical hazards, lockout/tagout, fall hazards, slipping hazards, hazards associated with the high pressure water, and hazards associated with air pressure systems.

  5. PREDICTED SEDIMENTARY SECTION OF SUBGLACIAL LAKE VOSTOK

    Directory of Open Access Journals (Sweden)

    G. I. Leychenkov

    2012-01-01

    Full Text Available In early February 2012, the drill hole at the Vostok Station encountered theLakeVostokwater. This step is important to study the lake composition including possible microbial life and to model subglacial environments however, the next ambitious target of the Vostok Drilling Project is sampling of bottom sediments, which contain the unique record of ice sheet evolution and environmental changes in centralAntarcticafor millions of years. In this connection, the forecast of sedimentary succession based on existing geophysical data, study of mineral inclusions in the accretion ice cores and tectonic models is important task. Interpretation of Airborne geophysical data suggests thatLakeVostokis the part of spacious rift system, which exists at least from Cretaceous. Reflection and refraction seismic experiments conducted in the southern part ofLakeVostokshow very thin (200–300 m stratified sedimentary cover overlying crystalline basement with velocity of 6.0–6.2 km/s. At present, deposition in southernLakeVostokis absent and similar conditions occurred likely at least last3 m.y. when ice sheet aboveLakeVostokchanged insignificantly. It can be also inferred that from the Late Miocene the rate of deposition inLakeVostokwas extremely low and so the most of sedimentary section is older being possibly of Oligocene to early to middle Miocene age when ice sheet oscillated and deposition was more vigorous. If so, the sampling of upper few meters of this condensed section is very informative in terms of history of Antarctic glaciation. Small thickness of sedimentary cover raises a question about existence of lake (rift depression during preglacial and early glacial times.

  6. Ultra-high pressure water jet: Baseline report; Greenbook (chapter)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-07-31

    The ultra-high pressure waterjet technology was being evaluated at Florida International University (FIU) as a baseline technology. In conjunction with FIU`s evaluation of efficiency and cost, this report covers the evaluation conducted for safety and health issues. It is a commercially available technology and has been used for various projects at locations throughout the country. The ultra-high pressure waterjet technology acts as a cutting tool for the removal of surface substrates. The Husky{trademark} pump feeds water to a lance that directs the high pressure water at the surface to be removed. The technologies being tested for concrete decontamination are targeted for alpha contamination. The safety and health evaluation during the human factors assessment focused on two main areas: noise and dust.

  7. Pressure effect on water dynamics in tert-butyl alcohol/water solutions

    Science.gov (United States)

    Calandrini, Vania; Deriu, Antonio; Onori, Giuseppe; Paciaroni, Alessandro; Telling, Mark T. F.

    2006-09-01

    We report here a quasi-elastic neutron scattering (QENS) investigation of the effect of pressure on the diffusivity properties of water in a dilute aqueous solution of hydrophobic molecules (tert-butyl alcohol, TBA). The experiment was performed at fixed TBA concentration (0.02 molar fraction) by varying pressure from 1 to 2000 bar at two different temperatures (268 and 278 K). The quasi-elastic line-shapes have been analysed in terms of a model based on the memory function formalism. Our data indicate that, on increasing pressure up to 2000 bar, the diffusion coefficient of water in the TBA/water mixture exhibits a relative increase larger than that of pure water under the same thermodynamic conditions. The extent of this effect increases with decreasing temperature. The observed behaviour is described in terms of pressure-induced distortions of the H-bonded random network of liquid water.

  8. Fracturing Pressure of Shallow Sediment in Deep Water Drilling

    Directory of Open Access Journals (Sweden)

    Chuanliang Yan

    2013-01-01

    Full Text Available The shallow sediment in deep water has weak strength and easily gets into plastic state under stress concentration induced by oil and gas drilling. During drilling, the formation around a wellbore can be divided into elastic zone and plastic zone. The unified strength theory was used after yielding. The radius of the plastic zone and the theoretical solution of the stress distribution in these two zones were derived in undrained condition. The calculation model of excess pore pressure induced by drilling was obtained with the introduction of Henkel’s excess pore pressure theory. Combined with hydraulic fracturing theory, the fracturing mechanism of shallow sediment was analyzed and the theoretical formula of fracturing pressure was given. Furthermore, the influence of the parameters of unified strength theory on fracturing pressure was analyzed. The theoretical calculation results agreed with measured results approximately, which preliminary verifies the reliability of this theory.

  9. Structural analysis of fuel rod applied to pressurized water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Faria, Danilo P.; Pinheiro, Andre Ricardo M.; Lotto, André A., E-mail: danilo.pinheiro@marinha.mil.br [Centro Tecnológico da Marinha em São Paulo (CTMSP), São Paulo, SP (Brazil)

    2017-07-01

    The design of fuel assemblies applied to Pressurized Water Reactors (PWR) has several requirements and acceptance criteria that must be attended for licensing. In the case of PWR fuel rods, an important mechanical structural requirement is to keep the radial stability when submitted to the coolant external pressure. In the framework of the Accident Tolerant Fuel (ATF) program new materials have been studied to replace zirconium based alloys as cladding, including iron-based alloys. In this sense, efforts have been made to evaluate the behavior of these materials under PWR conditions. The present work aims to evaluate the collapse cold pressure of a stainless steel thin-walled tube similar to that used as cladding material of fuel rods by means of the comparison of numeric data, and experimental results. As a result of the simulations, it was observed that the collapse pressure has a value intermediate value between those found by regulatory requirements and analytical calculations. The experiment was carried out for the validation of the computational model using test specimens of thin-walled tubes considering empty tube. The test specimens were sealed at both ends by means of welding. They were subjected to a high pressure device until the collapse of the tubes. Preliminary results obtained from experiments with the empty test specimens indicate that the computational model can be validated for stainless steel cladding, considering the difference between collapse pressure indicated in the regulatory document and the actual limit pressure concerning to radial instability of tubes with the studied characteristics. (author)

  10. Contribution of Water to Pressure and Cold Denaturation of Proteins

    Science.gov (United States)

    Bianco, Valentino; Franzese, Giancarlo

    2015-09-01

    The mechanisms of cold and pressure denaturation of proteins are matter of debate and are commonly understood as due to water-mediated interactions. Here, we study several cases of proteins, with or without a unique native state, with or without hydrophilic residues, by means of a coarse-grain protein model in explicit solvent. We show, using Monte Carlo simulations, that taking into account how water at the protein interface changes its hydrogen bond properties and its density fluctuations is enough to predict protein stability regions with elliptic shapes in the temperature-pressure plane, consistent with previous theories. Our results clearly identify the different mechanisms with which water participates to denaturation and open the perspective to develop advanced computational design tools for protein engineering.

  11. An In-Situ Deep-UV Optical Probe for Examining Biochemical Presence in Deep Glaciers and Sub-Glacial Lakes

    Science.gov (United States)

    Lane, A. L.; Behar, A.; Bhartia, R.; Conrad, P. G.; Hug, W. F.

    2007-12-01

    The quest to study and understand extremophiles has led to many quite different research paths in the past 30 years. One of the more difficult directions has been the study of biochemical material in deep glacial ice and in subglacial lakes. Lake Vostok in Eastern Antarctica has been perhaps the most discussed subglacial lake because of its large size (~14,000 sq km), deep location under >3700 m of overlying ice, and thick sediment bed (~200m). Once the physical conditions of the Lake were assessed, questions immediately arose about the potential existence of biological material - either extinct or possibly extant under conditions of extremely limited energy and nutrients [1-2]. To investigate the biology of Vostok, via in-situ methods, is a major issue that awaits proven techniques that will not contaminate the Lake beyond what may have occurred to date. Lake Ellsworth, in West Antarctica, also discovered by ice penetrating radar, is of significantly smaller size, but is also >3500 m below the overlying ice. It represents a wonderful opportunity to design, engineer and build in-situ delivery systems that consider bio-cleanliness approaches to enable examination of its water, sediment bed and the "roof" area accretion ice for biochemicals [3]. Our laboratory has been developing deep UV fluorescence and UV Raman instrumentation to locate and classify organic material at a variety of extremophile locations. The confluence of the measurement techniques and the engineering for high external pressure instrument shells has enabled us to design and begin prototype fabrication of a biochemical sensing probe that can be inserted into a hot-water drilled ice borehole, functioning as a local area mapper in water environments as deep as 6000 m. Real-time command and control is conducted from a surface science station. We have been using the deep Vostok ice cores at the U.S. National Ice Core Lab to validate our science and data analysis approaches with an "inverted" system

  12. Water vapor pressure versus environmental lapse rate near the tropopause

    Science.gov (United States)

    Ferreira, Antonio; Castanheira, Jose; Gimeno, Luis

    2010-05-01

    The relationship between water vapor pressure and temperature lapse rate in the vicinity of the tropopause was investigated using in situ observations. The water vapor partial pressures and the lapse rates within a vertical distance of ±1.5 km around the first thermal tropopause were calculated from the vertical soundings conducted by the NOAA/CMDL at several locations in the last few decades (GMD Data Archive). A positive non-linear relationship between the two quantities was found to hold across the studied tropopause region at mid-latitudes and polar latitudes. A similar analysis was performed on the 300 and 250 hPa pressure levels (which often intercept the tropopause region), by collecting temperature and humidity observations within 1979-2008 from the Integrated Global Radiosonde Archive (IGRA). A relationship having almost the same shape was detected for statically stable lapse rates at all latitude zones. Given the relevance of water vapor in the radiative transfer in the upper troposphere, the results are an indication of a local influence of water vapor on the thermal structure of the transition layer between the troposphere and stratosphere

  13. Ice thickness, volume and subglacial topography of Urumqi Glacier ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 123; Issue 3. Ice thickness, volume and subglacial topography of Urumqi Glacier No. 1, Tianshan mountains, central Asia, by ground penetrating radar survey. Puyu Wang Zhongqin Li Shuang Jin Ping Zhou Hongbing Yao Wenbin Wang. Volume 123 Issue 3 April ...

  14. Lake Vostok: From a Continental Margin to a Subglacial Lake

    Science.gov (United States)

    Studinger, M.; Bell, R. E.; KArner, G. D.; Tikku, A. A.; Levin, V.; Raymond, C. A.; Lerner-Lam, A.

    2002-05-01

    Subglacial ecosystems, in particular subglacial lakes, represent the most oligothrophic environments on Earth. The geologic origin of Lake Vostok is a critical boundary condition for both the stability of the lake and energy fluxes into the lake. Microbial life may use geothermal energy, similar to life discovered at deep sea hydrothermal vents. Significant geothermal anomalies are often associated with active faulting. The topographic depression which forms the craddle for Lake Vostok is part of a regional tectonic structure ranging from the Gamburtsev Subglacial Mountains to the Aurora Subglacial Basin. This geologic boundary was formed by emplacement of a thrust sheet from the east over a pre-existing passive continental margin beneath the present-day Lake Vostok. No data exist to directly date either the timing of passive margin formation or the subsequent crustal shortening. Minor extensional reactivation of the thrust sheet explains a simple mechanism to explain the formation of the Lake Vostok basin. The steep slopes bounding this depression are likley being fault-controlled. Our recent discovery of microseismic activity suggest that this faults might be active and could act as conduits for convecting fluids. The tectonic processes can have an important influence on the ecosystem within the lake.

  15. A wireless subglacial probe for deep ice applications

    NARCIS (Netherlands)

    Smeets, C.J.P.P.|info:eu-repo/dai/nl/191522236; Boot, W.; Hubbard, A.; Pettersson, R.; Wilhelms, F.; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; van de Wal, R.S.W.|info:eu-repo/dai/nl/101899556

    2012-01-01

    We present the design and first results from two experiments using a wireless subglacial sensor system (WiSe) that is able to transmit data through 2500m thick ice. Energy consumption of the probes is minimized, enabling the transmission of data for at least 10 years. In July 2010 the first

  16. In-Situ Observations of a Subglacial Outflow Plume in a Greenland Fjord

    Science.gov (United States)

    Mankoff, K. D.; Straneo, F.; Singh, H.; Das, S. B.

    2014-12-01

    We present oceanographic observations collected in and immediately outside of a buoyant, fresh, sediment-laden subglacial outflow plume rising up the marine-terminating front of Sarqardleq Glacier, Greenland (68.9 N, 50.4 W). Subglacial outflow plumes, associated with the discharge at depth of upstream glacial surface melt, entrain the relatively warm fjord waters and are correlated with enhanced submarine melt and increased calving. Few in-situ observations exist due to the challenges of making measurements at the calving front of glaciers. Our data were collected using a small boat, a helicopter, and a JetYak (a remote-controlled jet-ski-powered kayak). Temperature and salinity profiles in, around, and far from the plume are used to described its oceanographic properties, spatial extent, and temporal variability. This plume rises vertically up the ice front expanding laterally and away from the ice, over-shoots its stable isopycnal and reaches the surface. Its surface expression is identified by colder, saltier, sediment-laden water flowing at ~5 m/s away from the ice face. Within ~300 m from the ice it submerges as it seeks buoyant stability.

  17. Theoretical study of flashing and water hammer in a supercritical water cycle during pressure drop

    Energy Technology Data Exchange (ETDEWEB)

    Imre, A.R., E-mail: imre@aeki.kfki.h [Simulator Laboratory, MTA KFKI Atomic Energy Research Institute, Budapest, POB 49, H-1525 (Hungary); Barna, I.F.; Ezsoel, G. [Thermohydraulics Laboratory, MTA KFKI Atomic Energy Research Institute, Budapest, POB 49, H-1525 (Hungary); Hazi, G. [Simulator Laboratory, MTA KFKI Atomic Energy Research Institute, Budapest, POB 49, H-1525 (Hungary); Kraska, T. [Institute for Physical Chemistry, University of Cologne, Luxemburger Str. 116, D-50939 Koeln (Germany)

    2010-06-15

    During a loss of coolant accident (LOCA) the pressure of the coolant can drop significantly in the vicinity of the leak. It will be shown that unlike in pressurized water reactors (PWRs) where this pressure drop can cause only sudden vaporization - also called flashing - in supercritical water cooled reactors (SCWRs) it can cause sudden condensation (condensation-induced water hammer), too. The reason is that from supercritical state the system can go to metastable liquid as well as to metastable vapour state after LOCA. Relaxation from metastable fluid states is a fast process, followed by a local positive or negative pressure-jump, which might increase the damage around the leak. Conservative estimation will be given for the magnitude of these pressure jumps caused by the flashing or water hammer by assuming various initial pressure losses. In our calculations, three different equations of state are used: the simple van der Waals EoS; the Redlich-Kwong as an empirical development; and the more sophisticated non-cubic Deiters equation of state. These equations are able to describe metastable states qualitatively but with different accuracy. These calculations can help us to map the local immediate effect of any sudden pressure drop and therefore it can help to design better safety protocols.

  18. Drinking water fluoride and blood pressure? An environmental study.

    Science.gov (United States)

    Amini, Hassan; Taghavi Shahri, Seyed Mahmood; Amini, Mohamad; Ramezani Mehrian, Majid; Mokhayeri, Yaser; Yunesian, Masud

    2011-12-01

    The relationship between intakes of fluoride (F) from drinking water and blood pressure has not yet been reported. We examined the relationship of F in ground water resources (GWRs) of Iran with the blood pressure of Iranian population in an ecologic study. The mean F data of the GWRs (as a surrogate for F levels in drinking water) were derived from a previously conducted study. The hypertension prevalence and the mean of systolic and diastolic blood pressures (SBP & DBP) of Iranian population by different provinces and genders were also derived from the provincial report of non-communicable disease risk factor surveillance of Iran. Statistically significant positive correlations were found between the mean concentrations of F in the GWRs and the hypertension prevalence of males (r = 0.48, p = 0.007), females (r = 0.36, p = 0.048), and overall (r = 0.495, p = 0.005). Also, statistically significant positive correlations between the mean concentrations of F in the GWRs and the mean SBP of males (r = 0.431, p = 0.018), and a borderline correlation with females (r = 0.352, p = 0.057) were found. In conclusion, we found the increase of hypertension prevalence and the SBP mean with the increase of F level in the GWRs of Iranian population.

  19. Anomalies in bulk supercooled water at negative pressure

    Science.gov (United States)

    Pallares, Gaël; El Mekki Azouzi, Mouna; González, Miguel A.; Aragones, Juan L.; Abascal, José L. F.; Valeriani, Chantal; Caupin, Frédéric

    2014-01-01

    Water anomalies still defy explanation. In the supercooled liquid, many quantities, for example heat capacity and isothermal compressibility κT, show a large increase. The question arises if these quantities diverge, or if they go through a maximum. The answer is key to our understanding of water anomalies. However, it has remained elusive in experiments because crystallization always occurred before any extremum is reached. Here we report measurements of the sound velocity of water in a scarcely explored region of the phase diagram, where water is both supercooled and at negative pressure. We find several anomalies: maxima in the adiabatic compressibility and nonmonotonic density dependence of the sound velocity, in contrast with a standard extrapolation of the equation of state. This is reminiscent of the behavior of supercritical fluids. To support this interpretation, we have performed simulations with the 2005 revision of the transferable interaction potential with four points. Simulations and experiments are in near-quantitative agreement, suggesting the existence of a line of maxima in κT (LMκT). This LMκT could either be the thermodynamic consequence of the line of density maxima of water [Sastry S, Debenedetti PG, Sciortino F, Stanley HE (1996) Phys Rev E 53:6144–6154], or emanate from a critical point terminating a liquid–liquid transition [Sciortino F, Poole PH, Essmann U, Stanley HE (1997) Phys Rev E 55:727–737]. At positive pressure, the LMκT has escaped observation because it lies in the “no man’s land” beyond the homogeneous crystallization line. We propose that the LMκT emerges from the no man’s land at negative pressure. PMID:24843177

  20. Anomalies in bulk supercooled water at negative pressure.

    Science.gov (United States)

    Pallares, Gaël; El Mekki Azouzi, Mouna; González, Miguel A; Aragones, Juan L; Abascal, José L F; Valeriani, Chantal; Caupin, Frédéric

    2014-06-03

    Water anomalies still defy explanation. In the supercooled liquid, many quantities, for example heat capacity and isothermal compressibility κT, show a large increase. The question arises if these quantities diverge, or if they go through a maximum. The answer is key to our understanding of water anomalies. However, it has remained elusive in experiments because crystallization always occurred before any extremum is reached. Here we report measurements of the sound velocity of water in a scarcely explored region of the phase diagram, where water is both supercooled and at negative pressure. We find several anomalies: maxima in the adiabatic compressibility and nonmonotonic density dependence of the sound velocity, in contrast with a standard extrapolation of the equation of state. This is reminiscent of the behavior of supercritical fluids. To support this interpretation, we have performed simulations with the 2005 revision of the transferable interaction potential with four points. Simulations and experiments are in near-quantitative agreement, suggesting the existence of a line of maxima in κT (LMκT). This LMκT could either be the thermodynamic consequence of the line of density maxima of water [Sastry S, Debenedetti PG, Sciortino F, Stanley HE (1996) Phys Rev E 53:6144-6154], or emanate from a critical point terminating a liquid-liquid transition [Sciortino F, Poole PH, Essmann U, Stanley HE (1997) Phys Rev E 55:727-737]. At positive pressure, the LMκT has escaped observation because it lies in the "no man's land" beyond the homogeneous crystallization line. We propose that the LMκT emerges from the no man's land at negative pressure.

  1. Processing of water level derived from water pressure data at the Time Series Station Spiekeroog

    OpenAIRE

    Holinde, L.; Badewien, T. H.; Freund, J. A.; E. V. Stanev; Zielinski, O.

    2015-01-01

    The quality of water level time series data strongly varies with periods of high- and low-quality sensor data. In this paper we are presenting the processing steps which were used to generate high-quality water level data from water pressure measured at the Time Series Station (TSS) Spiekeroog. The TSS is positioned in a tidal inlet between the islands of Spiekeroog and Langeoog in the East Frisian Wadden Sea (southern North Sea). The processing steps will cover sensor drift...

  2. Thermal Hydraulic Integral Effect Tests for Pressurized Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Baek, W. P.; Song, C. H.; Kim, Y. S. and others

    2005-02-15

    The objectives of the project are to construct a thermal-hydraulic integral effect test facility and to perform various integral effect tests for design, operation, and safety regulation of pressurized water reactors. During the first phase of this project (1997.8{approx}2002.3), the basic technology for thermal-hydraulic integral effect tests was established and the basic design of the test facility was accomplished: a full-height, 1/300-volume-scaled full pressure facility for APR1400, an evolutionary pressurized water reactor that was developed by Korean industry. Main objectives of the present phase (2002.4{approx}2005.2), was to optimize the facility design and to construct the experimental facility. We have performed following researches: 1) Optimization of the basic design of the thermal-hydraulic integral effect test facility for PWRs - ATLAS (Advanced Thermal-hydraulic Test Loop for Accident Simulation) - Reduced height design for APR1400 (+ specific design features of KSNP safety injection systems) - Thermal-hydraulic scaling based on three-level scaling methodology by Ishii et al. 2) Construction of the ATLAS facility - Detailed design of the test facility - Manufacturing and procurement of components - Installation of the facility 3) Development of supporting technology for integral effect tests - Development and application of advanced instrumentation technology - Preliminary analysis of test scenarios - Development of experimental procedures - Establishment and implementation of QA system/procedure.

  3. Palaeogeographical And Archaeological Records Of Natural Changes Of The Jordanowo-Niesulice Subglacial Channel Near Lubrza, The Lubusz Lakeland

    Directory of Open Access Journals (Sweden)

    Ratajczak-Szczerba Magdalena

    2015-09-01

    Full Text Available The region of the Lubusz Lakeland in western Poland where there are a lot of subglacial channels provides opportunity for multi-proxy palaeoenvironmental reconstructions. None of them has not been the object of a specific study. The developmental history of the palaeolakes and their vicinity in the subglacial trough Jordanowo-Niesulice, spanning the Late Glacial and beginning of the Holocene, was investigated using geological research, lithological and geomorphological analysis, geochemical composition, palynological and archaeological research, OSL and AMS-radiocarbon dating. Geological research shows varied morphology of subglacial channel where at least two different reservoirs functioned in the end of the Last Glacial period and at the beginning of the Holocene. Mostly during the Bølling-Allerød interval and at the beginning of the Younger Dryas there took place melting of buried ice-blocks which preserved the analysied course of the Jordanowo-Niesulice trough. The level of water, and especially depth of reservoirs underwent also changes. Palynological analysis shows very diversified course of the Allerød interval.

  4. Culinary and pressure irrigation water system hydroelectric generation

    Energy Technology Data Exchange (ETDEWEB)

    Christiansen, Cory [Water Works Engineers, Pleasant Grove City, UT (United States)

    2016-01-29

    Pleasant Grove City owns and operates a drinking water system that included pressure reducing stations (PRVs) in various locations and flow conditions. Several of these station are suitable for power generation. The City evaluated their system to identify opportunities for power generation that can be implemented based on the analysis of costs and prediction of power generation and associated revenue. The evaluation led to the selection of the Battle Creek site for development of a hydro-electric power generating system. The Battle Creek site includes a pipeline that carries spring water to storage tanks. The system utilizes a PRV to reduce pressure before the water is introduced into the tanks. The evaluation recommended that the PRV at this location be replaced with a turbine for the generation of electricity. The system will be connected to the utility power grid for use in the community. A pelton turbine was selected for the site, and a turbine building and piping system were constructed to complete a fully functional power generation system. It is anticipated that the system will generate approximately 440,000 kW-hr per year resulting in $40,000 of annual revenue.

  5. ENERGY RECOVERY POTENTIAL FROM EXCESS PRESSURE in WATER SUPPLY and DISTRIBUTION SYSTEMS

    Directory of Open Access Journals (Sweden)

    I.Ethem Karadirek

    2016-06-01

    Full Text Available Sustainability of water supply systems has started to become an important issue besides continuous and hygienic supply of water. Sustainable water supply systems require improvement of energy efficiency, reduction of energy and water losses in water distribution systems and reduction of carbon dioxide emissions. Pressure is one of the main design parameters for gravity water supply systems and water distribution networks. Therefore, pressure has to be between certain limits. An excess pressure occurs during water transmission from high elevations of water resources to low elevations. By use of break pressure tanks, water storage tanks or pressure reducing valves (PRV excess pressure is reduced and damages on transmission pipes are prevented. However, energy recovery from excess pressure is possible at this stage by using turbines. Similarly, PRVs are used at certain locations of water distribution networks to control excess water pressure and to reduce it down to optimum operational levels. Energy recovery from excess pressure is also possible at this stage although energy recovery will be low. High pressure at water supply systems causes both energy and water losses. In Turkey, allowable water pressure at water distribution networks is between 20-60 m water column but excess pressure is commonly observed. At low pressure levels, water cannot reach water subscribers and this causes customer dissatisfaction. On the other side, at high pressure levels, water losses and pipe bursts increase which causes indirect increase in energy losses. For sustainable operation of water distribution networks, it is recommended to divide the network into smaller and independent subzones (District Metered Area, DMA. By placing a flow meter and a pressure meter at the entrance of a DMA, flow rate and pressure could be monitored on-line. However, in order to monitor spatial and temporal variations of flow rate and pressure at all pipes in the network, a hydraulic

  6. High pressure supercritical water - still an open field

    Energy Technology Data Exchange (ETDEWEB)

    Franck, E.U. [Inst. fuer Physikalische Chemie, Univ. Karlsruhe (Germany)

    1999-07-01

    A selected group of thermophysical phenomena of aqueous systems is presented and discussed. Emphasis is given to temperatures well above the critical temperature of water and to pressures extending in some cases to 3000 bar. Special attention is given to homogeneous supercritical binary mixture systems. The viscosity of water to 1000 C is discussed as well as the thermal conductivity and the static dielectric constant. As an example for dense water-molten salt systems, measurements of density and electrolytic conductivity up to the pure molten sodium hydroxide are shown. - Above its critical temperature the dense water is miscible also with nonpolar partners. Sveral of these have practical interest, for example H{sub 2}O-CO{sub 2}, H{sub 2}O-CH{sub 4}, H{sub 2}O-H{sub 2} and H{sub 2}O-O{sub 2}. Critical curves are demonstrated and discussed with phase diagrams of ternary systems to 2500 bar. ''Hydrothermal'' diffusion flames in dense H{sub 2}O-CH{sub 4} mixtures to 1000 bar can be produced and are presented. For the first time a phase diagram of the ternary water-oxyhydrogen system is shown, calculated to 350 C and 2500 bar. Also for hydrogen fluoride the molar volume V = (p,T) is shown for the first time to 2000 bar and 600 C. (orig.)

  7. Advanced fuels for plutonium management in pressurized water reactors

    Science.gov (United States)

    Vasile, A.; Dufour, Ph; Golfier, H.; Grouiller, J. P.; Guillet, J. L.; Poinot, Ch; Youinou, G.; Zaetta, A.

    2003-06-01

    Several fuel concepts are under investigation at CEA with the aim of manage plutonium inventories in pressurized water reactors. This options range from the use of mature technologies like MOX adapted in the case of MOX-EUS (enriched uranium support) and COmbustible Recyclage A ILot (CORAIL) assemblies to more innovative technologies using IMF like DUPLEX and advanced plutonium assembly (APA). The plutonium burning performances reported to the electrical production go from 7 to 60 kg (TW h) -1. More detailed analysis covering economic, sustainability, reliability and safety aspects and their integration in the whole fuel cycle would allow identifying the best candidate.

  8. Soil Water Thermodynamic to Unify Water Retention Curve by Pressure Plates and Tensiometer

    Directory of Open Access Journals (Sweden)

    Erik eBraudeau

    2014-10-01

    Full Text Available The pressure plate method is a standard method for measuring the pF curves, also called soil water retention curves, in a large soil moisture range from saturation to a dry state corresponding to a tension pressure of near 1500 kPa. However, the pressure plate can only provide discrete water retention curves represented by a dozen measured points. In contrast, the measurement of the soil water retention curves by tensiometer is direct and continuous, but limited to the range of the tensiometer reading: from saturation to near 70-80 kPa. The two methods stem from two very different concepts of measurement and the compatibility of both methods has never been demonstrated. The recently established thermodynamic formulation of the pedostructure water retention curve, will allow the compatibility of the two curves to be studied, both theoretically and experimentally. This constitutes the object of the present article. We found that the pressure plate method provides accurate measurement points of the pedostructure water retention curve h(W, conceptually the same as that accurately measured by the tensiometer. However, contrarily to what is usually thought, h is not equal to the applied air pressure on the sample, but rather, is proportional to its logarithm, in agreement with the thermodynamic theory developed in the article. The pF curve and soil water retention curve, as well as their methods of measurement are unified in a same physical theory. It is the theory of the soil medium organization (pedostructure and its interaction with water. We show also how the hydrostructural parameters of the theoretical curve equation can be estimated from any measured curve, whatever the method of measurement. An application example using published pF curves is given.

  9. Instrumentation and control strategies for an integral pressurized water reactor

    Directory of Open Access Journals (Sweden)

    Belle R. Upadhyaya

    2015-03-01

    Full Text Available Several vendors have recently been actively pursuing the development of integral pressurized water reactors (iPWRs that range in power levels from small to large reactors. Integral reactors have the features of minimum vessel penetrations, passive heat removal after reactor shutdown, and modular construction that allow fast plant integration and a secure fuel cycle. The features of an integral reactor limit the options for placing control and safety system instruments. The development of instrumentation and control (I&C strategies for a large 1,000 MWe iPWR is described. Reactor system modeling—which includes reactor core dynamics, primary heat exchanger, and the steam flashing drum—is an important part of I&C development and validation, and thereby consolidates the overall implementation for a large iPWR. The results of simulation models, control development, and instrumentation features illustrate the systematic approach that is applicable to integral light water reactors.

  10. Water-Energy balance in pressure irrigation systems

    Science.gov (United States)

    Sánchez, Raúl; Rodríguez-Sinobas, Leonor; Juana, Luis; Laguna, Francisco V.; Castañón, Guillermo; Gil, María; Benitez, Javier

    2013-04-01

    Modernization of irrigation schemes, generally understood as transformation of surface irrigation systems into pressure -sprinkler and trickle- irrigation systems, aims at, among others, improving irrigation efficiency and reduction of operation and maintenance efforts made by the irrigators. Automation techniques become easier after modernization, and operation management plays an important role in energy efficiency issues. Modern systems use to include elevated water reservoirs with enough capacity to irrigate during peak water demand period about 16 to 48 h. However, pressure irrigation systems, in contrast, carry a serious energy cost. Energy requirements depend on decisions taken on management strategies during the operation phase, which are conditioned by previous decisions taken on the design project of the different elements which compose the irrigation system. Most of the countries where irrigation activity is significant bear in mind that modernization irrigation must play a key role in the agricultural infrastructure policies. The objective of this study is to characterize and estimate the mean and variation of the energy consumed by common types of irrigation systems according to their management possibilities. Also is an objective to estimate the fraction of the water reservoirs available along the irrigation campaign for storing the energy from renewable sources during their availability periods. Simulation taking into account all elements comprising the irrigation system has been used to estimate the energy requirements of typical irrigation systems of several crop production systems. The simulation of various types of irrigation systems and management strategies, in the framework imposed by particular cropping systems, would help to develop criteria for improving the energy balance in relation to the irrigation water supply productivity and new opportunities in the renewable energy field.

  11. Intra-abdominal pressure correlates with extracellular water content.

    Directory of Open Access Journals (Sweden)

    Wojciech Dąbrowski

    Full Text Available Secondary increase in intra-abdominal pressure (IAP may result from extra-abdominal pathology, such as massive fluid resuscitation, capillary leak or sepsis. All these conditions increase the extravascular water content. The aim of this study was to analyze the relationship between IAP and body water volume.Adult patients treated for sepsis or septic shock with acute kidney injury (AKI and patients undergoing elective pharyngolaryngeal or orthopedic surgery were enrolled. IAP was measured in the urinary bladder. Total body water (TBW, extracellular water content (ECW and volume excess (VE were measured by whole body bioimpedance. Among critically ill patients, all parameters were analyzed over three consecutive days, and parameters were evaluated perioperatively in surgical patients.One hundred twenty patients were studied. Taken together, the correlations between IAP and VE, TBW, and ECW were measured at 408 time points. In all participants, IAP strongly correlated with ECW and VE. In critically ill patients, IAP correlated with ECW and VE. In surgical patients, IAP correlated with ECW and TBW. IAP strongly correlated with ECW and VE in the mixed population. IAP also correlated with VE in critically ill patients. ROC curve analysis showed that ECW and VE might be discriminative parameters of risk for increased IAP.IAP strongly correlates with ECW.

  12. Constraining local subglacial bedrock erosion rates with cosmogenic nuclides

    Science.gov (United States)

    Wirsig, Christian; Ivy-Ochs, Susan; Christl, Marcus; Reitner, Jürgen; Reindl, Martin; Bichler, Mathias; Vockenhuber, Christof; Akcar, Naki; Schlüchter, Christian

    2014-05-01

    The constant buildup of cosmogenic nuclides, most prominently 10Be, in exposed rock surfaces is routinely employed for dating various landforms such as landslides or glacial moraines. One fundamental assumption is that no cosmogenic nuclides were initially present in the rock, before the event to be dated. In the context of glacially formed landscapes it is commonly assumed that subglacial erosion of at least a few meters of bedrock during the period of ice coverage is sufficient to remove any previously accumulated nuclides, since the production of 10Be ceases at a depth of 2-3 m. Insufficient subglacial erosion leads to overestimation of surface exposure ages. If the time since the retreat of the glacier is known, however, a discordant concentration of cosmogenic nuclides delivers information about the depth of subglacial erosion. Here we present data from proglacial bedrock at two sites in the Alps. Goldbergkees in the Hohe Tauern National Park in Austria and Gruebengletscher in the Grimsel Pass area in Switzerland. Samples were taken inside as well as outside of the glaciers' Little Ice Age extent. Measured nuclide concentrations are analyzed with the help of a MATLAB model simulating periods of exposure or glacial cover of user-definable length and erosion rates.

  13. What controls the explosivity of subglacial rhyolite in Iceland?

    Science.gov (United States)

    Owen, J.; Tuffen, H.; McGarvie, D. W.

    2012-04-01

    The eruption controls of subglacial rhyolite are poorly understood but this is of key importance in mitigating hazards. In subaerial rhyolite eruptions the pre-eruptive volatile content and degassing path are considered to be the primary controls of explosivity, but is this also the case when rhyolitic eruptions occur under ice? We present the first pre-eruptive volatile content and degassing path data for subglacial rhyolite eruptions, comparing three edifices of contrasting eruption style from the Torfajökull complex in South Iceland[1]. Volatile concentrations were measured using infra-red spectroscopy (FTIR) and Secondary Ion Mass Spectroscopy (SIMS). SE Rauðfossafjöll is a large volume (~1 km3) explosively erupted tuya, Dalakvísl (~0.2 km3) is an entirely subglacial edifice that has both explosive and effusive deposits and Bláhnúkur is a small volume (Bull Vol. [3] Tuffen et al. (2007) Ann Glac, 45(1): 87-94

  14. Predictive modelling of (palaeo-)subglacial lake locations and their meltwater drainage routeways

    Science.gov (United States)

    Livingstone, S. J.; Clark, C.; Tarasoff, L.; Woodward, J.

    2013-12-01

    There is increasing recognition that subglacial lakes act as key components within the ice sheet system, capable of influencing ice-sheet topography, ice volume and ice flow. At present, much glaciological research is concerned with the role of modern subglacial lake systems in Antarctica. Another approach to the exploration of subglacial lakes involves identification of the geological record of subglacial lakes that once existed beneath ice sheets of the last glaciation. Investigation of such palaeo-subglacial lakes offers significant advantages because we have comprehensive information about the bed properties, they are much more accessible and we can examine and sample the sediments with ease. However, their identification in the geological record remains controversial. We therefore present a simple diagnostic approach based on the Shreve equation, for predicting and investigating likely (palaeo-)subglacial lake locations. Data on the current topography and seafloor bathymetry, and elevation models of the ice and ground surface topography from data-calibrated glaciological modelling are used to calculate the hydraulic potential surface at the ice-sheet bed. Meltwater routing algorithms and the flooding of local hydraulic minima allow us to predict subglacial routeways and lakes respectively. Discovered subglacial lakes beneath the Antarctic Ice Sheet present an opportunity to verify the model using the BEDMAP2 dataset. Using a lake threshold of 5 km2 we identify 12,767 subglacial lakes occurring over 4% of the grounded bed and are able to recover >60% of the discovered subglacial lakes. Applying the same approach to the Greenland Ice Sheet produces 1,607 potential subglacial lakes, covering 1.3% of the bed. These lake localities will make suitable targets for radar surveys attempting to find subglacial lakes. Finally, we apply the Shreve equation to the North American Ice Sheet to try and predict likely palaeo-subglacial lake locations. Given that specific ice

  15. Detecting pin diversion from pressurized water reactors spent fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Ham, Young S.; Sitaraman, Shivakumar

    2017-01-10

    Detecting diversion of spent fuel from Pressurized Water Reactors (PWR) by determining possible diversion including the steps of providing a detector cluster containing gamma ray and neutron detectors, inserting the detector cluster containing the gamma ray and neutron detectors into the spent fuel assembly through the guide tube holes in the spent fuel assembly, measuring gamma ray and neutron radiation responses of the gamma ray and neutron detectors in the guide tube holes, processing the gamma ray and neutron radiation responses at the guide tube locations by normalizing them to the maximum value among each set of responses and taking the ratio of the gamma ray and neutron responses at the guide tube locations and normalizing the ratios to the maximum value among them and producing three signatures, gamma, neutron, and gamma-neutron ratio, based on these normalized values, and producing an output that consists of these signatures that can indicate possible diversion of the pins from the spent fuel assembly.

  16. Dominant accident sequences in Oconee-1 pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Dearing, J F; Henninger, R J; Nassersharif, B

    1985-04-01

    A set of dominant accident sequences in the Oconee-1 pressurized water reactor was selected using probabilistic risk analysis methods. Because some accident scenarios were similar, a subset of four accident sequences was selected to be analyzed with the Transient Reactor Analysis Code (TRAC) to further our insights into similar types of accidents. The sequences selected were loss-of-feedwater, small-small break loss-of-coolant, loss-of-feedwater-initiated transient without scram, and interfacing systems loss-of-coolant accidents. The normal plant response and the impact of equipment availability and potential operator actions were also examined. Strategies were developed for operator actions not covered in existing emergency operator guidelines and were tested using TRAC simulations to evaluate their effectiveness in preventing core uncovery and maintaining core cooling.

  17. Analytical study on water hammer pressure in pressurized conduits with a throttled surge chamber for slow closure

    Directory of Open Access Journals (Sweden)

    Yong-liang Zhang

    2010-06-01

    Full Text Available This paper presents an analytical investigation of water hammer in a hydraulic pressurized pipe system with a throttled surge chamber located at the junction between a tunnel and a penstock, and a valve positioned at the downstream end of the penstock. Analytical formulas of maximum water hammer pressures at the downstream end of the tunnel and the valve were derived for a system subjected to linear and slow valve closure. The analytical results were then compared with numerical ones obtained using the method of characteristics. There is agreement between them. The formulas can be applied to estimating water hammer pressure at the valve and transmission of water hammer pressure through the surge chamber at the junction for a hydraulic pipe system with a surge chamber.

  18. Basal interstitial water pressure in laboratory debris flows over a rigid bed in an open channel

    Directory of Open Access Journals (Sweden)

    N. Hotta

    2012-08-01

    Full Text Available Measuring the interstitial water pressure of debris flows under various conditions gives essential information on the flow stress structure. This study measured the basal interstitial water pressure during debris flow routing experiments in a laboratory flume. Because a sensitive pressure gauge is required to measure the interstitial water pressure in shallow laboratory debris flows, a differential gas pressure gauge with an attached diaphragm was used. Although this system required calibration before and after each experiment, it showed a linear behavior and a sufficiently high temporal resolution for measuring the interstitial water pressure of debris flows. The values of the interstitial water pressure were low. However, an excess of pressure beyond the hydrostatic pressure was observed with increasing sediment particle size. The measured excess pressure corresponded to the theoretical excess interstitial water pressure, derived as a Reynolds stress in the interstitial water of boulder debris flows. Turbulence was thought to induce a strong shear in the interstitial space of sediment particles. The interstitial water pressure in boulder debris flows should be affected by the fine sediment concentration and the phase transition from laminar to turbulent debris flow; this should be the subject of future studies.

  19. Water-bearing, high-pressure Ca-silicates

    Science.gov (United States)

    Németh, Péter; Leinenweber, Kurt; Ohfuji, Hiroaki; Groy, Thomas; Domanik, Kenneth J.; Kovács, István J.; Kovács, Judit S.; Buseck, Peter R.

    2017-07-01

    Water-bearing minerals provide fundamental knowledge regarding the water budget of the mantle and are geophysically significant through their influence on the rheological and seismic properties of Earth's interior. Here we investigate the CaO-SiO2-H2O system at 17 GPa and 1773 K, corresponding to mantle transition-zone condition, report new high-pressure (HP) water-bearing Ca-silicates and reveal the structural complexity of these phases. We document the HP polymorph of hartrurite (Ca3SiO5), post-hartrurite, which is tetragonal with space group P4/ncc, a = 6.820 (5), c = 10.243 (8) Å, V = 476.4 (8) Å3, and Z = 4, and is isostructural with Sr3SiO5. Post-hartrurite occurs in hydrous and anhydrous forms and coexists with larnite (Ca2SiO4), which we find also has a hydrous counterpart. Si is 4-coordinated in both post-hartrurite and larnite. In their hydrous forms, H substitutes for Si (4H for each Si; hydrogrossular substitution). Fourier transform infrared (FTIR) spectroscopy shows broad hydroxyl absorption bands at ∼3550 cm-1 and at 3500-3550 cm-1 for hydrous post-hartrurite and hydrous larnite, respectively. Hydrous post-hartrurite has a defect composition of Ca2.663Si0.826O5H1.370 (5.84 weight % H2O) according to electron-probe microanalysis (EPMA), and the Si deficiency relative to Ca is also observed in the single-crystal data. Hydrous larnite has average composition of Ca1.924Si0.851O4H0.748 (4.06 weight % H2O) according to EPMA, and it is in agreement with the Si occupancy obtained using X-ray data collected on a single crystal. Superlattice reflections occur in electron-diffraction patterns of the hydrous larnite and could indicate crystallographic ordering of the hydroxyl groups and their associated cation defects. Although textural and EPMA-based compositional evidence suggests that hydrous perovskite may occur in high-Ca-containing (or low silica-activity) systems, the FTIR measurement does not show a well-defined hydroxyl absorption band for this

  20. Subglacial Lake Vostok (Antarctica accretion ice contains a diverse set of sequences from aquatic, marine and sediment-inhabiting bacteria and eukarya.

    Directory of Open Access Journals (Sweden)

    Yury M Shtarkman

    Full Text Available Lake Vostok, the 7(th largest (by volume and 4(th deepest lake on Earth, is covered by more than 3,700 m of ice, making it the largest subglacial lake known. The combination of cold, heat (from possible hydrothermal activity, pressure (from the overriding glacier, limited nutrients and complete darkness presents extreme challenges to life. Here, we report metagenomic/metatranscriptomic sequence analyses from four accretion ice sections from the Vostok 5G ice core. Two sections accreted in the vicinity of an embayment on the southwestern end of the lake, and the other two represented part of the southern main basin. We obtained 3,507 unique gene sequences from concentrates of 500 ml of 0.22 µm-filtered accretion ice meltwater. Taxonomic classifications (to genus and/or species were possible for 1,623 of the sequences. Species determinations in combination with mRNA gene sequence results allowed deduction of the metabolic pathways represented in the accretion ice and, by extension, in the lake. Approximately 94% of the sequences were from Bacteria and 6% were from Eukarya. Only two sequences were from Archaea. In general, the taxa were similar to organisms previously described from lakes, brackish water, marine environments, soil, glaciers, ice, lake sediments, deep-sea sediments, deep-sea thermal vents, animals and plants. Sequences from aerobic, anaerobic, psychrophilic, thermophilic, halophilic, alkaliphilic, acidophilic, desiccation-resistant, autotrophic and heterotrophic organisms were present, including a number from multicellular eukaryotes.

  1. Microbial life in ice and subglacial environments

    Science.gov (United States)

    Price, P. B.; Bramall, N.; Tatebe, K.

    2003-04-01

    Conditions for microbial life to exist in solid ice require the presence of liquid water and sources of energy and bioelements. In ice in thermal equilibrium, liquid water will exist in a three-dimensional network of micron-sized veins and in nanometer-thick films on mineral grains in ice. Ionic impurities lower the freezing temperature in the veins to as low as -95^oC. Depending on mineral type, the film on a grain surface will remain liquid down to ˜ -40^oC. The impurities provide both energy (via microbially catalyzed redox reactions) and bioelements. The maximum sustainable microbial population depends on metabolic rate, which in turn depends on species, temperature, and type and concentration of impurities in veins and surfaces. Microbes have been imaged by epifluorescence in veins in sea and Arctic lake ice and on grains in Dry Valleys lake ice. Indirect evidence exists for metabolism of microbes in Vostok glacial ice, in Greenland basal ice, and in Sajama (Bolivia) glacial ice. We will discuss several approaches to detection of microbes: epifluorescence microscopy of glacial ice at low temperature; fluorescence spectra taken with BSL (a new borehole logging instrument); fluorescence of microbes on surfaces of silt and volcanic ash in glacial ice; and in-situ cultivation of bacterial colonies at intersections of mineral grains and liquid veins in ice held in contact with a nutrient medium at subfreezing temperature. Based on measurements in the oligotrophic Lake Tahoe, BSL is sensitive to a concentration of ˜10^3 microbes cm-3, which may be adequate to detect life in Greenland ice and in Lake Vostok. A miniaturized version could be used to search for life in Martian permafrost and in diapirs in Europan ice.

  2. Test of simultaneous synthetic DNA tracer injections for the estimation of the englacial and subglacial drainage system structure of Storglaciären, northern Sweden

    Science.gov (United States)

    Dahlke, H. E.; Leung, S.; Lyon, S. W.; Sharma, A. N.; Walter, M. T.; Williamson, A.

    2013-12-01

    Storglaciären glacier, located in the sub-arctic Tarfala catchment, in northern Sweden is one of the world's longest continuously monitored glaciers which provides a unique research platform for the long-term assessment of glacier and ice sheet processes. For example, small mountain glacier hydrological knowledge of the subglacial water distribution at the ice-bed interface has been applied to ice sheets to predict basal sliding processes. Basal sliding promoted by hydraulic jacking is an important glacial-velocity control that is dependent on the subglacial flow pathways' morphology. Thus, understanding subglacial water distribution and drainage system structure and morphology is crucial for modeling ice masses' flow. In order to estimate subglacial drainage system structure and morphology dye tracing experiments are widely employed. Tracer experiments provide quantitative parameters for any input location including tracer transit velocity, dispersivity, recovery and storage. However, spatial data coverage is limited by the finite number of tracers available for simultaneous tracing. In the presented study we test the use of synthetic DNA tracers for the assessment of the englacial and subglacial drainage system structure of Storglaciären. The synthetic DNA tracer is composed of polylactic acid (PLA) microspheres into which short strands of synthetic DNA and paramagnetic iron oxide nanoparticles are incorporated (Sharma et al., 2012, Environmental Science & Technology). Because the DNA sequences can be randomly combined the synthetic DNA tracer provides an enormous number of unique tracers (approximately 1.61 x 1060). Thus, these synthetic tracers have the advantage that multiple (>10) experiments can be conducted simultaneously, allowing a greater information gain within a shorter measurement period. Quantities of a certain DNA strand can be detected using biotechnology tools such as polymerase chain reaction (PCR) and quantitative PCR (qPCR). During the 2013

  3. Seasonal speed-up of large Greenland marine-terminating outlet glacier related to surface melt-induced changes in subglacial hydrology

    Science.gov (United States)

    Mair, D.; Sole, A.; Nienow, P. W.; Bartholomew, I. D.

    2010-12-01

    The Greenland Ice Sheet (GrIS) has experienced increased rates of mass loss over the last decade due to increased surface melt and runoff and accelerated ice discharge. Two principal links between climate and ice discharge have been proposed. The first suggests that changes at the calving front of marine-terminating glaciers reduce resistive forces resulting in glacier acceleration and thinning or ‘draw-down’, while the second postulates that increased surface melt reaches the ice sheet bed locally and causes enhanced basal sliding, again leading to draw-down. Marine-terminating GrIS outlet glaciers generally display less sensitivity to variations in surface meltwater availability. Seasonal velocity variations have previously been explained by variations in calving rates due to the break up of the seasonal ice mélange or the ungrounding of ice near the terminus. Here we present sub-daily GPS ice velocity, surface lowering and air temperature measurements spanning the 2009 melt season along a flow line of Kangiata Nunata Sermia (KNS), the largest marine-terminating outlet glacier in South West Greenland. Surface velocity was measured at four GPS sites located 32-76 km from the calving front. A timelapse camera was installed with a field of view encompassing the calving terminus of KNS. The seasonal growth and drainage of supra-glacial lakes within the catchment was identified from MODIS imagery. The GPS data show multiple 2- to 12- day speed up events, often coincident with surface uplift, superimposed on a period of generally elevated velocity lasting 2 to 3 months. Reductions in lake volume were coincident with speed-up events at the nearby GPS sites providing strong evidence that these lakes drained to the glacier bed. These large volumes of meltwater were interpreted to be input to an inefficient, distributed drainage system creating episodes of high subglacial water pressure, hydraulic jacking and enhanced basal sliding. We conclude that between 36 km and

  4. High Performance Fuel Desing for Next Generation Pressurized Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Mujid S. Kazimi; Pavel Hejzlar

    2006-01-31

    The use of internally and externally cooled annular fule rods for high power density Pressurized Water Reactors is assessed. The assessment included steady state and transient thermal conditions, neutronic and fuel management requirements, mechanical vibration issues, fuel performance issues, fuel fabrication methods and econmic assessment. The investigation was donducted by a team from MIT, Westinghouse, Gamma Engineering, Framatome ANP, and AECL. The analyses led to the conclusion that raising the power density by 50% may be possible with this advanced fuel. Even at the 150% power level, the fuel temperature would be a few hundred degrees lower than the current fuel temperatre. Significant economic and safety advantages can be obtained by using this fuel in new reactors. Switching to this type of fuel for existing reactors would yield safety advantages, but the economic return is dependent on the duration of plant shutdown to accommodate higher power production. The main feasiblity issue for the high power performance appears to be the potential for uneven splitting of heat flux between the inner and outer fuel surfaces due to premature closure of the outer fuel-cladding gap. This could be overcome by using a very narrow gap for the inner fuel surface and/or the spraying of a crushable zirconium oxide film at the fuel pellet outer surface. An alternative fuel manufacturing approach using vobropacking was also investigated but appears to yield lower than desirable fuel density.

  5. Pressurized-water reactor internals aging degradation study. Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    Luk, K.H. [Oak Ridge National Lab., TN (United States)

    1993-09-01

    This report documents the results of a Phase I study on the effects of aging degradations on pr internals. Primary stressers for internals an generated by the primary coolant flow in the they include unsteady hydrodynamic forces and pump-generated pressure pulsations. Other stressors are applied loads, manufacturing processes, impurities in the coolant and exposures to fast neutron fluxes. A survey of reported aging-related failure information indicates that fatigue, stress corrosion cracking (SCC) and mechanical wear are the three major aging-related degradation mechanisms for PWR internals. Significant reported failures include thermal shield flow-induced vibration problems, SCC in guide tube support pins and core support structure bolts, fatigue-induced core baffle water-jet impingement problems and excess wear in flux thimbles. Many of the reported problems have been resolved by accepted engineering practices. Uncertainties remain in the assessment of long-term neutron irradiation effects and environmental factors in high-cycle fatigue failures. Reactor internals are examined by visual inspections and the technique is access limited. Improved inspection methods, especially one with an early failure detection capability, can enhance the safety and efficiency of reactor operations.

  6. High protein flexibility and reduced hydration water dynamics are key pressure adaptive strategies in prokaryotes

    Science.gov (United States)

    Martinez, N.; Michoud, G.; Cario, A.; Ollivier, J.; Franzetti, B.; Jebbar, M.; Oger, P.; Peters, J.

    2016-09-01

    Water and protein dynamics on a nanometer scale were measured by quasi-elastic neutron scattering in the piezophile archaeon Thermococcus barophilus and the closely related pressure-sensitive Thermococcus kodakarensis, at 0.1 and 40 MPa. We show that cells of the pressure sensitive organism exhibit higher intrinsic stability. Both the hydration water dynamics and the fast protein and lipid dynamics are reduced under pressure. In contrast, the proteome of T. barophilus is more pressure sensitive than that of T. kodakarensis. The diffusion coefficient of hydration water is reduced, while the fast protein and lipid dynamics are slightly enhanced with increasing pressure. These findings show that the coupling between hydration water and cellular constituents might not be simply a master-slave relationship. We propose that the high flexibility of the T. barophilus proteome associated with reduced hydration water may be the keys to the molecular adaptation of the cells to high hydrostatic pressure.

  7. High protein flexibility and reduced hydration water dynamics are key pressure adaptive strategies in prokaryotes

    KAUST Repository

    Martinez, N.

    2016-09-06

    Water and protein dynamics on a nanometer scale were measured by quasi-elastic neutron scattering in the piezophile archaeon Thermococcus barophilus and the closely related pressure-sensitive Thermococcus kodakarensis, at 0.1 and 40 MPa. We show that cells of the pressure sensitive organism exhibit higher intrinsic stability. Both the hydration water dynamics and the fast protein and lipid dynamics are reduced under pressure. In contrast, the proteome of T. barophilus is more pressure sensitive than that of T. kodakarensis. The diffusion coefficient of hydration water is reduced, while the fast protein and lipid dynamics are slightly enhanced with increasing pressure. These findings show that the coupling between hydration water and cellular constituents might not be simply a master-slave relationship. We propose that the high flexibility of the T. barophilus proteome associated with reduced hydration water may be the keys to the molecular adaptation of the cells to high hydrostatic pressure.

  8. Pressure dependence of viscosity in supercooled water and a unified approach for thermodynamic and dynamic anomalies of water

    Science.gov (United States)

    Singh, Lokendra P.; Issenmann, Bruno; Caupin, Frédéric

    2017-01-01

    The anomalous decrease of the viscosity of water with applied pressure has been known for over a century. It occurs concurrently with major structural changes: The second coordination shell around a molecule collapses onto the first shell. Viscosity is thus a macroscopic witness of the progressive breaking of the tetrahedral hydrogen bond network that makes water so peculiar. At low temperature, water at ambient pressure becomes more tetrahedral and the effect of pressure becomes stronger. However, surprisingly, no data are available for the viscosity of supercooled water under pressure, in which dramatic anomalies are expected based on interpolation between ambient pressure data for supercooled water and high pressure data for stable water. Here we report measurements with a time-of-flight viscometer down to 244K and up to 300MPa, revealing a reduction of viscosity by pressure by as much as 42%. Inspired by a previous attempt [Tanaka H (2000) J Chem Phys 112:799–809], we show that a remarkably simple extension of a two-state model [Holten V, Sengers JV, Anisimov MA (2014) J Phys Chem Ref Data 43:043101], initially developed to reproduce thermodynamic properties, is able to accurately describe dynamic properties (viscosity, self-diffusion coefficient, and rotational correlation time) as well. Our results support the idea that water is a mixture of a high density, “fragile” liquid, and a low density, “strong” liquid, the varying proportion of which explains the anomalies and fragile-to-strong crossover in water. PMID:28404733

  9. Dual temperature dual pressure water-hydrogen chemical exchange for water detritiation

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, Takahiko, E-mail: t-sugiyama@nucl.nagoya-u.ac.jp [Faculty of Engineering, Nagoya University, Fro-cho 1, Chikusa-ku, Nagoya 464-8603 (Japan); Takada, Akito; Morita, Youhei [Faculty of Engineering, Nagoya University, Fro-cho 1, Chikusa-ku, Nagoya 464-8603 (Japan); Kotoh, Kenji [Graduate School of Engineering, Kyushu University, Moto-oka 744, Nishi-ku, Fukuoka 819-0395 (Japan); Munakata, Kenzo [Faculty of Engineering and Resource Science, Akita University, Tegata-gakuen-machi 1-1, Akita 010-8502 (Japan); Taguchi, Akira [Hydrogen Isotope Research Center, University of Toyama, Gofuku 3190, Toyama 930-8555 (Japan); Kawano, Takao; Tanaka, Masahiro; Akata, Naofumi [National Institute for Fusion Science, Oroshi-cho 322-6, Toki, Gifu 509-5292 (Japan)

    2015-10-15

    Experimental and analytical studies on hydrogen-tritium isotope separation by a dual temperature dual pressure catalytic exchange (DTDP-CE) with liquid phase chemical exchange columns were carried out in order to apply it to a part of the water detritiation system for DEMO fuel cycle. A prototype DTDP-CE apparatus was successfully operated and it was confirmed that tritium was separated by the apparatus as significantly distinguishable. A calculation code was developed based on the channeling stage model. The values of separation factors and the effects of some operating parameters were well predicted by the separative analyses with the code.

  10. Anomalous dependence of the heat capacity of supercooled water on pressure and temperature

    Directory of Open Access Journals (Sweden)

    I.A. Stepanov

    2014-01-01

    Full Text Available In some papers, dependences of the isobaric heat capacity of water versus pressure and temperature were obtained. It is shown that these dependences contradict both the dependence of heat capacity on temperature for supercooled water, and an important thermodynamic equation for the dependence of heat capacity on pressure. A possible explanation for this contradiction is proposed.

  11. The Subglacial Access and Fast Ice Research Experiment (SAFIRE): 3. Englacial and subglacial conditions revealed by seismic reflection data on Store Glacier, West Greenland.

    Science.gov (United States)

    Hofstede, Coen; Eisen, Olaf; Young, Tun Jan; Doyle, Samuel; Hubbard, Bryn; Christoffersen, Poul; Hubbard, Alun

    2015-04-01

    Basal conditions have a profound influence on the dynamics of outlet glaciers. As part of the SAFIRE research programme, we carried out a seismic survey on Store Glacier, a tidewater glacier terminating in Uummanaq Fjord in West Greenland (see joint abstracts by Christoffersen et al. and Doyle et al. for details). At the survey site the ice moves 700m/a making the terrain crevassed and bumpy. Despite the rough terrain we collected two 1.5 km long survey lines parallel and perpendicular to the ice flow direction using a 300m snow streamer and explosives as a source. The seismic data reveal an ice thickness of about 620m and 20 to 30m of subglacial sediment on the upstream side of the area thinning in the downstream direction. From polarity reversals seen along the ice-bed contact we speculate that the sediments have varying degrees of water content. The ice itself has several englacial reflections parallel and close to the bed. At approximately 475m depth, a clear single englacial reflection is observed in the parallel survey line. Thermistor data installed at this location show a clear increase in ice temperature starting at this depth. We speculate that the observed englacial reflection is caused by a change in crystal orientation fabric allowing greater ice deformation below this depth causing increased strain heating.

  12. Thin-layer effects in glaciological seismic amplitude-versus-angle (AVA analysis: implications for characterising a subglacial till unit, Russell Glacier, West Greenland

    Directory of Open Access Journals (Sweden)

    A. D. Booth

    2012-08-01

    Full Text Available Seismic amplitude-versus-angle (AVA methods are a powerful means of quantifying the physical properties of subglacial material, but serious interpretative errors can arise when AVA is measured over a thinly-layered substrate. A substrate layer with a thickness less than 1/4 of the seismic wavelength, λ, is considered "thin", and reflections from its bounding interfaces superpose and appear in seismic data as a single reflection event. AVA interpretation of subglacial till can be vulnerable to such thin-layer effects, since a lodged (non-deforming till can be overlain by a thin (metre-scale cap of dilatant (deforming till. We assess the potential for misinterpretation by simulating seismic data for a stratified subglacial till unit, with an upper dilatant layer between 0.1–5.0 m thick (λ / 120 to > λ / 4, with λ = 12 m. For dilatant layers less than λ / 6 thick, conventional AVA analysis yields acoustic impedance and Poisson's ratio that indicate contradictory water saturation. A thin-layer interpretation strategy is proposed, that accurately characterises the model properties of the till unit. The method is applied to example seismic AVA data from Russell Glacier, West Greenland, in which characteristics of thin-layer responses are evident. A subglacial till deposit is interpreted, having lodged till (acoustic impedance = 4.26±0.59 × 106 kg m−2 s−1 underlying a water-saturated dilatant till layer (thickness < 2 m, Poisson's ratio ~ 0.5. Since thin-layer considerations offer a greater degree of complexity in an AVA interpretation, and potentially avoid misinterpretations, they are a valuable aspect of quantitative seismic analysis, particularly for characterising till units.

  13. Molecular dynamics simulations of water on a hydrophilic silica surface at high air pressures

    DEFF Research Database (Denmark)

    Zambrano, H.A.; Walther, Jens Honore; Jaffe, R.L.

    2014-01-01

    Wepresent a force field forMolecular Dynamics (MD) simulations ofwater and air in contactwith an amorphous silica surface. We calibrate the interactions of each species present in the systemusing dedicated criteria such as the contact angle of a water droplet on a silica surface, and the solubility...... of air in water at different pressures. Using the calibrated force field, we conduct MD simulations to study the interface between a hydrophilic silica substrate and water surrounded by air at different pressures. We find that the static water contact angle is independent of the air pressure imposed...

  14. The initial responses of hot liquid water released under low atmospheric pressures: Experimental insights

    Science.gov (United States)

    Bargery, Alistair Simon; Lane, Stephen J.; Barrett, Alexander; Wilson, Lionel; Gilbert, Jennie S.

    2010-11-01

    Experiments have been performed to simulate the shallow ascent and surface release of water and brines under low atmospheric pressure. Atmospheric pressure was treated as an independent variable and water temperature and vapor pressure were examined as a function of total pressure variation down to low pressures. The physical and thermal responses of water to reducing pressure were monitored with pressure transducers, temperature sensors and visible imaging. Data were obtained for pure water and for solutions with dissolved NaCl or CO 2. The experiments showed the pressure conditions under which the water remained liquid, underwent a rapid phase change to the gas state by boiling, and then solidified because of removal of latent heat. Liquid water is removed from phase equilibrium by decompression. Solid, liquid and gaseous water are present simultaneously, and not at the 611 Pa triple point, because dynamic interactions between the phases maintain unstable temperature gradients. After phase changes stop, the system reverts to equilibrium with its surroundings. Surface and shallow subsurface pressure conditions were simulated for Mars and the icy satellites of the outer Solar System. Freezing by evaporation in the absence of wind on Mars is shown to be unlikely for pure water at pressures greater than c. 670 Pa, and for saline solutions at pressures greater than c. 610 Pa. The physical nature of ice that forms depends on the salt content. Ice formed from saline water at pressures less than c. 610 Pa could be similar to terrestrial sea ice. Ice formed from pure water at pressures less than c. 100 Pa develops a low thermal conductivity and a 'honeycomb' structure created by sublimation. This ice could have a density as low as c. 450 kg m -3 and a thermal conductivity as low as 1.6 W m -1 K -1, and is highly reflective, more akin to snow than the clear ice from which it grew. The physical properties of ice formed from either pure or saline water at low pressures will

  15. High conversion pressurized water reactor with boiling channels

    Energy Technology Data Exchange (ETDEWEB)

    Margulis, M., E-mail: maratm@post.bgu.ac.il [The Unit of Nuclear Engineering, Ben Gurion University of the Negev, POB 653, Beer Sheva 84105 (Israel); Shwageraus, E., E-mail: es607@cam.ac.uk [Department of Engineering, University of Cambridge, CB2 1PZ Cambridge (United Kingdom)

    2015-10-15

    Highlights: • Conceptual design of partially boiling PWR core was proposed and studied. • Self-sustainable Th–{sup 233}U fuel cycle was utilized in this study. • Seed-blanket fuel assembly lattice optimization was performed. • A coupled Monte Carlo, fuel depletion and thermal-hydraulics studies were carried out. • Thermal–hydraulic analysis assured that the design matches imposed safety constraints. - Abstract: Parametric studies have been performed on a seed-blanket Th–{sup 233}U fuel configuration in a pressurized water reactor (PWR) with boiling channels to achieve high conversion ratio. Previous studies on seed-blanket concepts suggested substantial reduction in the core power density is needed in order to operate under nominal PWR system conditions. Boiling flow regime in the seed region allows more heat to be removed for a given coolant mass flow rate, which in turn, may potentially allow increasing the power density of the core. In addition, reduced moderation improves the breeding performance. A two-dimensional design optimization study was carried out with BOXER and SERPENT codes in order to determine the most attractive fuel assembly configuration that would ensure breeding. Effects of various parameters, such as void fraction, blanket fuel form, number of seed pins and their dimensions, on the conversion ratio were examined. The obtained results, for which the power density was set to be 104 W/cm{sup 3}, created a map of potentially feasible designs. It was found that several options have the potential to achieve end of life fissile inventory ratio above unity, which implies potential feasibility of a self-sustainable Thorium fuel cycle in PWRs without significant reduction in the core power density. Finally, a preliminary three-dimensional coupled neutronic and thermal–hydraulic analysis for a single seed-blanket fuel assembly was performed. The results indicate that axial void distribution changes drastically with burnup. Therefore

  16. Effects of water availability and pest pressures on tea (Camellia sinensis) growth and functional quality

    OpenAIRE

    Ahmed, Selena; Orians, Colin M.; Griffin, Timothy S; Buckley, Sarabeth; Unachukwu, Uchenna; Stratton, Anne Elise; Stepp, John Richard; Robbat, Albert; Cash, Sean; Kennelly, Edward J.

    2013-01-01

    Extreme shifts in water availability linked to global climate change are impacting crops worldwide. The present study examines the direct and interactive effects of water availability and pest pressures on tea (Camellia sinensis; Theaceae) growth and functional quality. Manipulative greenhouse experiments were used to measure the effects of variable water availability and pest pressures simulated by jasmonic acid (JA) on tea leaf growth and secondary metabolites that determine tea quality. Wa...

  17. Construction management of Indian pressurized heavy water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Bohra, S.A. [Nuclear Power Corporation of India Limited, Vikram Sarabhai Bhavan, Anushaktinagar, Mumbai 400094 (India)]. E-mail: sabohra@npcil.co.in; Sharma, P.D. [Nuclear Power Corporation of India Limited, Vikram Sarabhai Bhavan, Anushaktinagar, Mumbai 400094 (India)

    2006-04-15

    Pandit Jawaharlal Nehru and Dr. Homi J. Bhabha, the visionary architects of Science and Technology of modern India foresaw the imperative need to establish a firm base for indigenous research and development in the field of nuclear electricity generation. The initial phase has primarily focused on the technology development in a systematic and structured manner, which has resulted in establishment of strong engineering, manufacturing and construction base. The nuclear power program started with the setting up of two units of boiling light water type reactors in 1969 for speedy establishment of nuclear technology, safety culture, and development of operation and maintenance manpower. The main aim at that stage was to demonstrate (to ourselves, and indeed to the rest of the world) that India, inspite of being a developing country, with limited industrial infrastructure and low capacity power grids, could successfully assimilate the high technology involved in the safe and economical operation of nuclear power reactors. The selection of a BWR was in contrast to the pressurized heavy water reactors (PHWR), which was identified as the flagship for the first stage of India's nuclear power program. The long-term program in three stages utilizes large reserves of thorium in the monazite sands of Kerala beaches in the third stage with first stage comprising of series of PHWR type plants with a base of 10,000 MW. India has at present 14 reactors in operation 12 of these being of PHWR type. The performance of operating units of 2720 MW has improved significantly with an overall capacity factor of about 90% in recent times. The construction work on eight reactor units with installed capacity of 3960 MW (two PHWRs of 540 MW each, four PHWRs of 220 MW each and two VVERs of 1000 MW each) is proceeding on a rapid pace with project schedules of less than 5 years from first pour of concrete. This is being achieved through advanced construction technology and management. Present

  18. Review of Water Resource Exploitation and Landuse Pressure in ...

    African Journals Online (AJOL)

    In addition, changes in climate regime, due to increasing temperature and reduced rainfall conditions, contribute to the reduced water supply. ... methods and 4- application of modern innovative techniques of water storage such as Aquifer Storage and Recovery (ASR) in preference to surface water storage systems.

  19. Pressure suppression containment system for boiling water reactor

    Science.gov (United States)

    Gluntz, Douglas M.; Nesbitt, Loyd B.

    1997-01-01

    A system for suppressing the pressure inside the containment of a BWR following a postulated accident. A piping subsystem is provided which features a main process pipe that communicates the wetwell airspace to a connection point downstream of the guard charcoal bed in an offgas system and upstream of the main bank of delay charcoal beds which give extensive holdup to offgases. The main process pipe is fitted with both inboard and outboard containment isolation valves. Also incorporated in the main process pipe is a low-differential-pressure rupture disk which prevents any gas outflow in this piping whatsoever until or unless rupture occurs by virtue of pressure inside this main process pipe on the wetwell airspace side of the disk exceeding the design opening (rupture) pressure differential. The charcoal holds up the radioactive species in the noncondensable gas from the wetwell plenum by adsorption, allowing time for radioactive decay before the gas is vented to the environs.

  20. A Laboratory Investigation of the Effects of Subglacial Meltwater Plumes on Submarine Ablation at the Fronts of Tidewater Glaciers

    Science.gov (United States)

    Kerr, R. C.; McConnochie, C. D.

    2016-12-01

    We investigate experimentally the effect of a basal freshwater source on the ablation of a vertical ice wall in salty water. We measure as a function of height the turbulent wall plume velocity, the ablation velocity of the ice, and the temperature at the ice wall. By systematically varying the volume flow rate of the freshwater source, we determine where the turbulent wall plume transitions from a free convection regime (controlled by the distributed buoyancy flux due to dissolution of the ice) to a forced convection regime (controlled by the buoyancy flux Bs of the basal freshwater source). In the forced convection regime, we find that the turbulent plume velocity is uniform with height and is proportional to Bs1/3, the interface temperature is independent of Bs, and the ablation velocity increases with Bs. In the two convection regimes, we find that there are fundamental differences in the wall turbulent plume, the turbulent entrainment coefficient, and the detrainment from the turbulent plume at the top of the wall. Lateral variations in subglacial discharge rates can enable these regimes to occur simultaneously along the front of a tidewater glacier, which will result in subglacial meltwater and submarine meltwater being seen at differing depths in the Greenland fjords.

  1. Simulation and experiment research on the proportional pressure control of water-assisted injection molding

    Science.gov (United States)

    Zhou, Hua; Chen, Yinglong; Zhang, Zengmeng; Yang, Huayong

    2012-05-01

    Water-assisted injection molding (WAIM), a newly developed fluid-assisted injection molding technology has drawn more and more attentions for the energy saving, short cooling circle time and high quality of products. Existing research for the process of WAIM has shown that the pressure control of the injecting water is mostly important for the WAIM. However, the proportional pressure control for the WAIM system is quite complex due to the existence of nonlinearities in the water hydraulic system. In order to achieve better pressure control performance of the injecting water to meet the requirements of the WAIM, the proportional pressure control of the WAIM system is investigated both numerically and experimentally. A newly designed water hydraulic system for WAIM is first modeled in AMEsim environment, the load characteristics and the nonlinearities of water hydraulic system are both considered, then the main factors affecting the injecting pressure and load flow rate are extensively studied. Meanwhile, an open-loop model-based compensation control strategy is employed to regulate the water injection pressure and a feedback proportional integrator controller is further adopted to achieve better control performance. In order to verify the AMEsim simulation results WAIM experiment for particular Acrylonitrile Butadiene Styrene (ABS) parts is implemented and the measured experimental data including injecting pressure and flow rate results are compared with the simulation. The good coincidence between experiment and simulation shows that the AMEsim model is accurate, and the tracking performance of the load pressure indicates that the proposed control strategy is effective for the proportional pressure control of the nonlinear WAIM system. The proposed proportional pressure control strategy and the conclusions drawn from simulation and experiment contribute to the application of water hydraulic proportional control and WAIM technology.

  2. Predicting subglacial lakes and meltwater drainage pathways beneath the Antarctic and Greenland ice sheets

    Science.gov (United States)

    Livingstone, S. J.; Clark, C. D.; Woodward, J.

    2013-03-01

    In this paper we use the Shreve hydraulic potential equation to predict subglacial lakes and meltwater drainage pathways beneath the Antarctic and Greenland ice sheets. For the Antarctic Ice Sheet we are able to predict known subglacial lakes with a >70% success rate, which demonstrates the validity of this method. Despite the success in predicting known subglacial lakes the calculations produce two-orders of magnitude more lakes than are presently identified, covering 4% of the ice-sheet bed. The difference is thought to result from our poor knowledge of the bed (which has resulted in artefacts associated with the interpolation method), intrinsic errors associated with the simplified modelling approach and because thousands of subglacial lakes, particularly smaller ones, remain to be found. Applying the same modelling approach to the Greenland Ice Sheet predicts only 90 lakes under the present-day ice-sheet configuration, covering 0.2% of the bed. The paucity of subglacial lakes in Greenland is thought to be a function of steeper overall ice-surface gradients. As no lakes have currently been located under Greenland, model predictions will make suitable targets for radar surveys of Greenland to identify subglacial lakes. During deglaciation from the Last Glacial Maximum both ice sheets had more subglacial lakes at their beds, though many of these lakes have persisted to present conditions. These lakes, inherited from past ice-sheet configurations would not form under current surface conditions, suggesting a retreating ice-sheet will have many more subglacial lakes than an advancing ice sheet. This hysteresis effect has implications for ice-stream formation and flow, bed lubrication and meltwater drainage. The lake model also allows modelling of the drainage pathways of the present-day and former Greenland and Antarctic ice sheets. Significantly, key sectors of the ice sheets, such as the Siple Coast (Antarctica) and NE Greenland Ice Stream system, are shown to have

  3. Potential subglacial lake locations and meltwater drainage pathways beneath the Antarctic and Greenland ice sheets

    Science.gov (United States)

    Livingstone, S. J.; Clark, C. D.; Woodward, J.; Kingslake, J.

    2013-11-01

    We use the Shreve hydraulic potential equation as a simplified approach to investigate potential subglacial lake locations and meltwater drainage pathways beneath the Antarctic and Greenland ice sheets. We validate the method by demonstrating its ability to recall the locations of >60% of the known subglacial lakes beneath the Antarctic Ice Sheet. This is despite uncertainty in the ice-sheet bed elevation and our simplified modelling approach. However, we predict many more lakes than are observed. Hence we suggest that thousands of subglacial lakes remain to be found. Applying our technique to the Greenland Ice Sheet, where very few subglacial lakes have so far been observed, recalls 1607 potential lake locations, covering 1.2% of the bed. Our results will therefore provide suitable targets for geophysical surveys aimed at identifying lakes beneath Greenland. We also apply the technique to modelled past ice-sheet configurations and find that during deglaciation both ice sheets likely had more subglacial lakes at their beds. These lakes, inherited from past ice-sheet configurations, would not form under current surface conditions, but are able to persist, suggesting a retreating ice-sheet will have many more subglacial lakes than advancing ones. We also investigate subglacial drainage pathways of the present-day and former Greenland and Antarctic ice sheets. Key sectors of the ice sheets, such as the Siple Coast (Antarctica) and NE Greenland Ice Stream system, are suggested to have been susceptible to subglacial drainage switching. We discuss how our results impact our understanding of meltwater drainage, basal lubrication and ice-stream formation.

  4. Reconstruction of a Palaeo-Subglacial Lake Network in Alberta, Canada

    Science.gov (United States)

    Livingstone, S. J.; Utting, D.; Clark, C.; Ruffell, A.; Pawley, S. M.; Atkinson, N.; Mallon, G.

    2014-12-01

    Subglacial lakes have been widely documented since first being identified beneath the Antarctic Ice Sheet in the 1960s and comprise a significant component of the subglacial hydrological system (Wright & Siegert, 2011). However, their investigation is largely limited to contemporary ice masses despite critical information that could be gleaned from palaeo-subglacial lake studies, including: (i) their influence on meltwater drainage, ice flow and ice streams; (ii) details about how they relate to palaeo-floods, ice dynamics and sub-Milankovitch-scale climate events; and (iii) as archives of long-term Quaternary climate change. They are also readily available, we can sample the sediments and maps the landforms with ease and we have comprehensive information on the lake-bed properties. Output from numerical ice sheet models and the simple Shreve equation approach has been used to diagnose where subglacial lakes are likely to have occurred in the geological record (Livingstone et al. 2013). However, their identification remains controversial due to the difficulty in distinguishing their signature from proglacial lake deposits (see Livingstone et al. 2012). Here, we present new geomorphological, geophysical and sedimentological evidence for the existence of a palaeo-subglacial lake network beneath the suture zone of the former Cordilleran and Laurentide ice sheets. These relatively small (~1 km diameter) palaeo-subglacial lakes manifest as flat-spots in a drumlin field and are perched in upland areas behind small ridges. The flat-spots, which comprise basins in-filled with diamicton, are associated with subglacial meltwater channels and eskers that we interpret to document lake drainage events. References: Livingstone, S.J., et al., 2012. Quaternary Science Reviews,55, 88-110. Livingstone, S.J., et al., 2013. Earth and Planetary Science Letters, 375, 13-33. Wright A.P., Siegert M.J. 2011. In: Siegert, M.J., Kennicutt, C., Bindschadler, B. (Eds.). Subglacial Antarctic

  5. Negative Pressures and Spallation in Water Drops Subjected to Nanosecond Shock Waves.

    Science.gov (United States)

    Stan, Claudiu A; Willmott, Philip R; Stone, Howard A; Koglin, Jason E; Liang, Mengning; Aquila, Andrew L; Robinson, Joseph S; Gumerlock, Karl L; Blaj, Gabriel; Sierra, Raymond G; Boutet, Sébastien; Guillet, Serge A H; Curtis, Robin H; Vetter, Sharon L; Loos, Henrik; Turner, James L; Decker, Franz-Josef

    2016-06-02

    Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below -100 MPa were reached in the drops. We model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.

  6. Response of the water status of soybean to changes in soil water potentials controlled by the water pressure in microporous tubes

    Science.gov (United States)

    Steinberg, S. L.; Henninger, D. L.

    1997-01-01

    Water transport through a microporous tube-soil-plant system was investigated by measuring the response of soil and plant water status to step change reductions in the water pressure within the tubes. Soybeans were germinated and grown in a porous ceramic 'soil' at a porous tube water pressure of -0.5 kpa for 28 d. During this time, the soil matric potential was nearly in equilibrium with tube water pressure. Water pressure in the porous tubes was then reduced to either -1.0, -1.5 or -2.0 kPa. Sap flow rates, leaf conductance and soil, root and leaf water potentials were measured before and after this change. A reduction in porous tube water pressure from -0.5 to -1.0 or -1.5 kPa did not result in any significant change in soil or plant water status. A reduction in porous tube water pressure to -2.0 kPa resulted in significant reductions in sap flow, leaf conductance, and soil, root and leaf water potentials. Hydraulic conductance, calculated as the transpiration rate/delta psi between two points in the water transport pathway, was used to analyse water transport through the tube-soil-plant continuum. At porous tube water pressures of -0.5 to-1.5 kPa soil moisture was readily available and hydraulic conductance of the plant limited water transport. At -2.0 kPa, hydraulic conductance of the bulk soil was the dominant factor in water movement.

  7. China's coal-fired power plants impose pressure on water resources

    NARCIS (Netherlands)

    Zhang, Xinxin; Liu, Junguo; Tang, Yu; Zhao, Xu; Yang, Hong; Gerbens-Leenes, P.W.; Vliet, van Michelle T.H.; Yan, Jinyue

    2017-01-01

    Coal is the dominant fuel for electricity generation around the world. This type of electricity generation uses large amounts of water, increasing pressure on water resources. This calls for an in-depth investigation in the water-energy nexus of coal-fired electricity generation. In China,

  8. Gray water recycle: Effect of pretreatment technologies on low pressure reverse osmosis treatment

    Science.gov (United States)

    Gray water can be a valuable source of water when properly treated to reduce the risks associated with chemical and microbial contamination to acceptable levels for the intended reuse application. In this study, the treatment of gray water using low pressure reverse osmosis (RO) filtration after pre...

  9. Soak Feet Warm Water Therapy Effective To Reduce Blood Pressure In The Elderly

    Directory of Open Access Journals (Sweden)

    yessi harnani

    2017-12-01

    Full Text Available Hypertension is a heart and blood vessels disease that is manifested by rising blood pressure. Untreated hypertension will lead to complication such as stroke and heart failure. Soak feet warm water is one of the complementary therapy that can reduce blood pressure. The purpose of this research is to find out the effecveness of soak feet warm water therapy to reduce blood pressure in the elderly. This research was a quantave by using the pre-experimental design and pretest and posest approach. The Sample were elderly with hypertension in working area of Puskesmas Simpang Tiga Pekanbaru. The sampling technique was used purposive sampling. The data collection techniques were used observation and measuring blood pressure by using sphignomanometer. The data analyzed was used Wilcoxon test. The Results showed that generally elderly with hypertension were on stage II. Stasc result showed that mean blood pressure post soak feet warm water therapy was 74,00 and standard deviaon was 5, 026, with the sistolic P value was 0.000 (<0.05 and diastolic P value was 0.000 (<0.05. So, it could be stated that soak feet warm water therapy effecve to reduce blood pressure in elderly. It is recommended to elderly with hypertension to always controlling their blood pressure, if there is a rising of blood pressure they could using soak feet warm water therapy to treat hypertension as a complementary therapy, cheap and easy to do indenpendently.

  10. Evaluating the hydrostatic equilibrium of the subglacial Lake Vostok, Antarctica, using a precise regional geoid model

    Science.gov (United States)

    Schwabe, Joachim; Ewert, Heiko; Scheinert, Mirko; Dietrich, Reinhard

    2014-05-01

    We present a study on the determination and application of a precise geoid model for the region of the subglacial Lake Vostok, Antarctica. The geoid model is derived by combining a global satellite-only geopotential model mainly based on GOCE data with dense airborne gravity data and topographic information. Ice-thickness data and lake water depths are used for a residual terrain modelling (RTM) in a remove-restore approach. In that context, special focus is given to the correct treatment of the ice sheet when computing the residual terrain effects. The use of the refined regional geoid model for glaciological and geophysical applications is exemplarily demonstrated by means of the hydrostatic equilibrium surface (HE) of the lake. It was found that the mean quadratic residual geoid signal is about two times larger than the estimated deviations of the HE surface. Thus, the significance of the refined geoid solution is proven. In this context, a comparison with the strictly computed geopotential shows that the estimated apparent lake level may be expressed as a constant metric bias w.r.t. to the quasigeoid. Furthermore, the HE condition is used to derive an adjusted estimate of the lake water density. However, in this case the theoretical latitudinal trend of the equilibrium surface needs to be taken into account. Finally, the (hypothetical) deviations from the HE state at and around the shoreline of the lake indicate candidate outflow locations in case of a possible depletion event.

  11. Ecology of Subglacial Lake Vostok (Antarctica, Based on Metagenomic/Metatranscriptomic Analyses of Accretion Ice

    Directory of Open Access Journals (Sweden)

    Tom D'Elia

    2013-03-01

    Full Text Available Lake Vostok is the largest of the nearly 400 subglacial Antarctic lakes and has been continuously buried by glacial ice for 15 million years. Extreme cold, heat (from possible hydrothermal activity, pressure (from the overriding glacier and dissolved oxygen (delivered by melting meteoric ice, in addition to limited nutrients and complete darkness, combine to produce one of the most extreme environments on Earth. Metagenomic/metatranscriptomic analyses of ice that accreted over a shallow embayment and over the southern main lake basin indicate the presence of thousands of species of organisms (94% Bacteria, 6% Eukarya, and two Archaea. The predominant bacterial sequences were closest to those from species of Firmicutes, Proteobacteria and Actinobacteria, while the predominant eukaryotic sequences were most similar to those from species of ascomycetous and basidiomycetous Fungi. Based on the sequence data, the lake appears to contain a mixture of autotrophs and heterotrophs capable of performing nitrogen fixation, nitrogen cycling, carbon fixation and nutrient recycling. Sequences closest to those of psychrophiles and thermophiles indicate a cold lake with possible hydrothermal activity. Sequences most similar to those from marine and aquatic species suggest the presence of marine and freshwater regions.

  12. Complex cooling water systems optimization with pressure drop consideration

    CSIR Research Space (South Africa)

    Gololo, KV

    2012-12-01

    Full Text Available -integer nonlinear programming (MINLP) structure. The cooling tower model is used to predict the exit conditions of the cooling towers, given the inlet conditions from the cooling water network model. The case studies showed that the circulating cooling water flow...

  13. Troubled waters: Growing climate and population pressures in ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2014-04-09

    Apr 9, 2014 ... Rapid urbanization is squeezing India's limited water resources. While climate change may compound the problem, research in two southern watersheds points to industrial pollution, unregulated extraction, and changes in land use as the greatest threats to water quality and availability.

  14. Analysis of External Water Pressure for a Tunnel in Fractured Rocks

    Directory of Open Access Journals (Sweden)

    Ze-jun Liu

    2017-01-01

    Full Text Available External water pressure around tunnels is a main influential factor in relation to the seepage safety of underground chambers and powerhouses which make managing external water pressure crucial to water conservation and hydropower projects. The equivalent continuous medium model and the discrete fracture network (DFN model were, respectively, applied to calculate the seepage field of the study domain. Calculations were based on the integrity and permeability of rocks, the extent of fracture development, and the combination of geological and hydrogeological conditions in the Huizhou pump-storage hydropower station. The station generates electricity from the upper reservoir and stores power by pumping water from the lower to the upper reservoir. In this paper, the external water pressure around the cavern and variations in pressure with only one operational and one venting powerhouse were analyzed to build a predictive model. The results showed that the external water pressure was small with the current anti-seepage and drainage system that normal operation of the reservoir can be guaranteed. The results of external water pressure around the tunnels provided sound scientific evidence for the future design of antiseepage systems.

  15. Study on the pressure self-adaptive water-tight junction box in underwater vehicle

    Directory of Open Access Journals (Sweden)

    Haocai Huang

    2012-09-01

    Full Text Available Underwater vehicles play a very important role in underwater engineering. Water-tight junction box (WJB is one of the key components in underwater vehicle. This paper puts forward a pressure self-adaptive water-tight junction box (PSAWJB which improves the reliability of the WJB significantly by solving the sealing and pressure problems in conventional WJB design. By redundancy design method, the pressure self-adaptive equalizer (PSAE is designed in such a way that it consists of a piston pressure-adaptive compensator (PPAC and a titanium film pressure-adaptive compensator (TFPAC. According to hydro-mechanical simulations, the operating volume of the PSAE is more than or equal to 11.6 % of the volume of WJB liquid system. Furthermore, the required operating volume of the PSAE also increases as the gas content of oil, hydrostatic pressure or temperature difference increases. The reliability of the PSAWJB is proved by hyperbaric chamber tests.

  16. High-Pressure Water-Rinse Cleaning of Copper(LCC-0067)

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, R

    2003-11-06

    Copper, niobium and stainless steel surfaces were cleaned by high-pressure water-rinsing spray (HPWR). Surface chemical and topographic analyses show that the HPWR process is neither a contaminating nor a significantly eroding process.

  17. Capital cost: pressurized water reactor plant. Commercial electric power cost studies

    Energy Technology Data Exchange (ETDEWEB)

    1977-06-01

    The investment cost study for the 1139 MW(e) pressurized water reactor (PWR) central station power plant consists of two volumes. This volume contains the drawings, equipment list and site description.

  18. Exploration of Impinging Water Spray Heat Transfer at System Pressures Near the Triple Point

    Science.gov (United States)

    Golliher, Eric L.; Yao, Shi-Chune

    2013-01-01

    The heat transfer of a water spray impinging upon a surface in a very low pressure environment is of interest to cooling of space vehicles during launch and re-entry, and to industrial processes where flash evaporation occurs. At very low pressure, the process occurs near the triple point of water, and there exists a transient multiphase transport problem of ice, water and water vapor. At the impingement location, there are three heat transfer mechanisms: evaporation, freezing and sublimation. A preliminary heat transfer model was developed to explore the interaction of these mechanisms at the surface and within the spray.

  19. Nuclear Engineering Computer Modules, Thermal-Hydraulics, TH-1: Pressurized Water Reactors.

    Science.gov (United States)

    Reihman, Thomas C.

    This learning module is concerned with the temperature field, the heat transfer rates, and the coolant pressure drop in typical pressurized water reactor (PWR) fuel assemblies. As in all of the modules of this series, emphasis is placed on developing the theory and demonstrating its use with a simplified model. The heart of the module is the PWR…

  20. Development of a quasi-adiabatic calorimeter for the determination of the water vapor pressure curve.

    Science.gov (United States)

    Mokdad, S; Georgin, E; Hermier, Y; Sparasci, F; Himbert, M

    2012-07-01

    Progress in the knowledge of the water saturation curve is required to improve the accuracy of the calibrations in humidity. In order to achieve this objective, the LNE-CETIAT and the LNE-CNAM have jointly built a facility dedicated to the measurement of the saturation vapor pressure and temperature of pure water. The principle is based on a static measurement of the pressure and the temperature of pure water in a closed, temperature-controlled thermostat, conceived like a quasi-adiabatic calorimeter. A copper cell containing pure water is placed inside a temperature-controlled copper shield, which is mounted in a vacuum-tight stainless steel vessel immersed in a thermostated bath. The temperature of the cell is measured with capsule-type standard platinum resistance thermometers, calibrated with uncertainties below the millikelvin. The vapor pressure is measured by calibrated pressure sensors connected to the cell through a pressure tube whose temperature is monitored at several points. The pressure gauges are installed in a thermostatic apparatus ensuring high stability of the pressure measurement and avoiding any condensation in the tubes. Thanks to the employment of several technical solutions, the thermal contribution to the overall uncertainty budget is reduced, and the remaining major part is mainly due to pressure measurements. This paper presents a full description of this facility and the preliminary results obtained for its characterization.

  1. Effects of altitude on transpiration, leaf vapor pressure deficit and leaf water potential in oriental beech

    Directory of Open Access Journals (Sweden)

    Fatih Bayraktar

    2015-04-01

    Full Text Available This study was designed to determine the effect of altitude on transpiration, leaf vapor pressure deficit and leaf water potential in oriental beech (Fagus orientalis Lipsky. The study area was located in Ortaköy, Artvin, and the experimental area had the same soil structure and aspect. The study showed that transpiration and leaf vapor pressure deficit increased but leaf water potential decreased by altitudinal gradient

  2. Liquid sinusoidal pressure measurement by laser interferometry based on the refractive index of water.

    Science.gov (United States)

    Yang, Jun; Fan, Shangchun; Li, Cheng; Guo, Zhanshe; Li, Bo; Shi, Bo

    2016-12-01

    A new method with laser interferometry is used to enhance the traceability for sinusoidal pressure calibration in water. The laser vibrometer measures the dynamic pressure based on the acousto-optic effect. The relation of the refractive index of water and the optical path length with the pressure's change is built based on the Lorentz-Lorenz equation, and the conversion coefficients are tested by static calibration in situ. A device with a piezoelectric transducer and resonant pressure pipe with water is set up to generate sinusoidal pressure up to 20 kHz. With the conversion coefficients, the reference sinusoidal pressure is measured by the laser interferometer for pressure sensors' dynamic calibration. The experiment results show that under 10 kHz, the measurement results between the laser vibrometer and a piezoelectric sensor are in basic agreement and indicate that this new method and its measurement system are feasible in sinusoidal pressure calibration. Some disturbing components including small amplitude, temperature change, pressure maldistribution, and glass windows' vibration are also analyzed, especially for the dynamic calibrations above 10 kHz.

  3. EFFECTS OF PRESSURE AND TEMPERATURE ON ULTRAFILTRATION HOLLOW FIBER MEMBRANE IN MOBILE WATER TREATMENT SYSTEM

    Directory of Open Access Journals (Sweden)

    ROSDIANAH RAMLI

    2016-07-01

    Full Text Available In Sabah, Malaysia, there are still high probability of limited clean water access in rural area and disaster site. Few villages had been affected in Pitas due to improper road access, thus building a water treatment plant there might not be feasible. Recently, Kundasang area had been affected by earthquake that caused water disruption to its people due to the damage in the underground pipes and water tanks. It has been known that membrane technology brought ease in making mobile water treatment system that can be transported to rural or disaster area. In this study, hollow fiber membrane used in a mobile water treatment system due to compact and ease setup. Hollow fiber membrane was fabricated into small module at 15 and 30 fibers to suit the mobile water treatment system for potable water production of at least 80 L/day per operation. The effects of transmembrane pressure (TMP and feed water temperature were investigated. It was found that permeate flux increases by more than 96% for both 15 and 30 fiber bundles with increasing pressure in the range of 0.25 to 3.0 bar but dropped when the pressure reached maximum. Lower temperature of 17 to 18˚C increase the water viscosity by 15% from normal temperature of water at 24˚C, making the permeate flux decreases. The fabricated modules effectively removed 96% turbidity of the surface water sample tested.

  4. Water pressure and ground vibrations induced by water guns at a backwater pond on the Illinois River near Morris, Illinois

    Science.gov (United States)

    Koebel, Carolyn M.; Egly, Rachel M.

    2016-09-27

    Three different geophysical sensor types were used to characterize the underwater pressure waves and ground velocities generated by the underwater firing of seismic water guns. These studies evaluated the use of water guns as a tool to alter the movement of Asian carp. Asian carp are aquatic invasive species that threaten to move into the Great Lakes Basin from the Mississippi River Basin. Previous studies have identified a threshold of approximately 5 pounds per square inch (lb/in2) for behavioral modification and for structural limitation of a water gun barrier.Two studies were completed during August 2014 and May 2015 in a backwater pond connected to the Illinois River at a sand and gravel quarry near Morris, Illinois. The August 2014 study evaluated the performance of two 80-cubic-inch (in3) water guns. Data from the 80-in3 water guns showed that the pressure field had the highest pressures and greatest extent of the 5-lb/in2 target value at a depth of 5 feet (ft). The maximum recorded pressure was 13.7 lb/in2, approximately 25 ft from the guns. The produced pressure field took the shape of a north-south-oriented elongated sphere with the 5-lb/in2 target value extending across the entire study area at a depth of 5 ft. Ground velocities were consistent over time, at 0.0067 inches per second (in/s) in the transverse direction, 0.031 in/s in the longitudinal direction, and 0.013 in/s in the vertical direction.The May 2015 study evaluated the performance of one and two 100-in3 water guns. Data from the 100-in3 water guns, fired both individually and simultaneously, showed that the pressure field had the highest pressures and greatest extent of the 5-lb/in2 target value at a depth of 5 ft. The maximum pressure was 57.4 lb/in2, recorded at the underwater blast sensor closest to the water guns (at a horizontal distance of approximately 3 ft), as two guns fired simultaneously. Pressures and extent of the 5-lb/in2 target value decrease above and below this 5-ft depth

  5. Automatic detection of subglacial lakes in radar sounder data acquired in Antarctica

    Science.gov (United States)

    Ilisei, Ana-Maria; Khodadadzadeh, Mahdi; Dalsasso, Emanuele; Bruzzone, Lorenzo

    2017-10-01

    Subglacial lakes decouple the ice sheet from the underlying bedrock, thus facilitating the sliding of the ice masses towards the borders of the continents, consequently raising the sea level. This motivated increasing attention in the detection of subglacial lakes. So far, about 70% of the total number of subglacial lakes in Antarctica have been detected by analysing radargrams acquired by radar sounder (RS) instruments. Although the amount of radargrams is expected to drastically increase, from both airborne and possible future Earth observation RS missions, currently the main approach to the detection of subglacial lakes in radargrams is by visual interpretation. This approach is subjective and extremely time consuming, thus difficult to apply to a large amount of radargrams. In order to address the limitations of the visual interpretation and to assist glaciologists in better understanding the relationship between the subglacial environment and the climate system, in this paper, we propose a technique for the automatic detection of subglacial lakes. The main contribution of the proposed technique is the extraction of features for discriminating between lake and non-lake basal interfaces. In particular, we propose the extraction of features that locally capture the topography of the basal interface, the shape and the correlation of the basal waveforms. Then, the extracted features are given as input to a supervised binary classifier based on Support Vector Machine to perform the automatic subglacial lake detection. The effectiveness of the proposed method is proven both quantitatively and qualitatively by applying it to a large dataset acquired in East Antarctica by the MultiChannel Coherent Radar Depth Sounder.

  6. A reassessment of the englacial and subglacial drainage system of Storglaciären in northern Sweden - How much did climate warming change the drainage system?

    Science.gov (United States)

    Dahlke, H. E.; Rosqvist, G. N.; Jansson, P.; Lyon, S. W.

    2012-12-01

    Storglaciären glacier, located in the sub-arctic Tarfala catchment, in northern Sweden is one of the world's longest continuously monitored glaciers which provides a unique research platform for the long-term assessment of climate change impacts on mountain glacier systems. In the presented study we assess signals of climate-induced change in the englacial and subglacial drainage system of the lower ablation area of Storglaciären. Flow velocities and dispersive characteristics of the englacial and subglacial hydraulic system were re-investigated in the 2012 summer melt season using fluorescent dye-tracing tests and compared to previous assessments of from the 1980s and 1990s. Historical hydro-climatic records from Tarfala catchment indicate that there have been significant increases in the cold season air temperature (0.76 °C/decade, 1965-2009) and a doubling of summer event precipitation over the past four decades. These changes contributed to the consistently negative glacier net balance of Storglaciären and significant positive trends in both the mean summer discharge and flood magnitudes over the past 45 years. Six of the eight largest annual maximum flood events occurred during the last decade and meltwater contributions from Storglaciären to the Tarfalajokken stream increased by 15% during the same period. These hydro-climatic trends in conjunction with an isotopic hydrograph separation of present-day samplings indicate that high magnitude rainfall events receive an increasing role in the runoff generation in Tarfala catchment and the glacier systems. This shift towards a greater rainwater contribution to catchment streamflow and glacier runoff indicates fundamental changes in the pathways that water takes through the glacier. The isotopic data suggests that the transit of rainwater via the englacial drainage system is increasing. However, in contrast to the 1980s assessment, dye-tracing tests conducted in 2012 indicate that the majority of meltwater

  7. High pressure water electrolysis for space station EMU recharge

    Science.gov (United States)

    Lance, Nick; Puskar, Michael; Moulthrop, Lawrence; Zagaja, John

    1988-01-01

    A high pressure oxygen recharge system (HPORS), is being developed for application on board the Space Station. This electrolytic system can provide oxygen at up to 6000 psia without a mechanical compressor. The Hamilton standard HPORS based on a solid polymer electrolyte system is an extension of the much larger and succesful 3000 psia system of the U.S. Navy. Cell modules have been successfully tested under conditions beyond which spacecraft may encounter during launch. The control system with double redundancy and mechanical backups for all electronically controlled components is designed to ensure a safe shutdown.

  8. A Prediction of Increase in Subglacial Volcanism Beneath the West Antarctic Ice Sheet (WAIS) as Future Deglaciation Caused by Ocean Circulation Proceeds

    Science.gov (United States)

    Behrendt, J. C.; LeMasurier, W. E.

    2015-12-01

    Many decades of aeromagnetic surveying (e.g. Behrendt, 1964; 2013; and others) over the West Antarctic Ice sheet (WAIS) have shown >1000 high amplitude, shallow source magnetic anomalies interpreted as as indicating subglacial volcanic centers of late Cenozoic age to presently active. Similar anomalies exist over exposed volcanic rocks bordering the WAIS in places.Recent papers (e.g. Wouters et al., 2015; Paolo, et al.; 2015 and others) based on satellite altimetry have shown dramatic thinning and retreat of ice shelves, particularly those bordering the Amundsen and Bellingshausen Seas, caused by melting from circulation of warming sea water. Previous workers have shown that when ice shelves collapse, the ice streams previously dammed by them accelerate an order of magnitude higher velocity, and surface elevation decreases. GRACE satellite interpretations (e.g. Velicogna et al., and others) indicate mass loss of WAIS in recent years.The bed elevation beneath the WAIS deepens inland from the Amundsen and Bellingshausen coasts, although high relief volcanic topography is present in a number of areas beneath the ice.Crowley et a. (2015) have shown that glacial cycles may drive production of oceanic crust by lowering pressure in the mantle resulting in increased melting and magma production. Increased volcanism due to deglaciation in Iceland has apparently produced increased in volcanic activity there. Deglaciation of the Norwegian continental shelf has resulted in faulting of the sea floor and similar faulting has been reported of the Ross Sea shelf following deglaciation there.I suggest here that as the WAIS collapses in the future resulting from climate change, an increase in volcanic activity beneath the ice might be expected. This may provide a feedback mechanism for increase in ice melting.

  9. Water vaporization promotes coseismic fluid pressurization and buffers temperature rise

    NARCIS (Netherlands)

    Chen, Jianye|info:eu-repo/dai/nl/370819071; Niemeijer, André|info:eu-repo/dai/nl/370832132; Yao, Lu; Ma, Shengli

    2017-01-01

    We investigated the frictional properties of carbonate-rich gouge layers at a slip rate of 1.3 m/s, under dry and water-saturated conditions, while monitoring temperature at different locations on one of the gouge-host rock interfaces. All experiments showed a peak frictional strength of 0.4–0.7,

  10. The Subglacial Access and Fast Ice Research Experiment (SAFIRE): 1. Programme of investigation on Store Glacier, West Greenland

    Science.gov (United States)

    Christoffersen, Poul; Hubbard, Bryn; Bougamont, Marion; Doyle, Samuel; Young, Tun Jan; Hofstede, Coen; Nicholls, Keith; Todd, Joe; Box, Jason; Ryan, Johnny; Toberg, Nick; Walter, Jacob; Hubbard, Alun

    2015-04-01

    Marine-terminating outlet glaciers drain 90 percent of the Greenland Ice Sheet and are responsible for about half of the ice sheet's net annual mass loss, which currently raises global sea level by almost 1 mm per year. Understanding the processes that drive the fast flow of these glaciers is crucial because a growing body of evidence points to a strong, but spatially varied and often complex, response to oceanographic as well as atmospheric forcing. While the bed of glaciers elsewhere is known to strongly influence the flow of ice, no observations have ever been made at the bed of a marine-terminating glacier in Greenland. The flow of ice in numerical models of the Greenland Ice Sheet consequently rely on untested basal parameterisations, which form a likely and potentially significant source of error in the prediction of sea level rise over the coming decades and century. The Subglacial Access and Fast Ice Research Experiment (SAFIRE) is addressing this paucity of observational constraints by gaining access to the bed of Store Glacier, a marine-terminating outlet of the Greenland Ice Sheet which has a drainage basin of 35,000 square kilometres and terminates in Uummannaq Fjord. In 2014, the SAFIRE programme drilled four boreholes in a region where ice flows at a rate of 700 m per year and where a seismic survey revealed a bed consisting of soft sediment. (See joint abstract by Hofstede et al. for details.) The boreholes were 603-616 m deep and direct access to the bed was confirmed by a clear hydrological connectivity with a basal water system. (See joint abstract by Doyle et al. for details.) With sensors deployed englacially (temperature and tilt) and at the bed (water pressure, turbidity, electrical conductivity), the SAFIRE will inform the ratio of internal ice deformation and basal slip, vertical strain, ice temperature, and fluctuations in water pressure linked to supraglacial lake drainage as well as diurnal drainage into moulins. In 2015, we plan to

  11. Failure Mode of the Water-filled Fractures under Hydraulic Pressure in Karst Tunnels

    Directory of Open Access Journals (Sweden)

    Dong Xin

    2017-06-01

    Full Text Available Water-filled fractures continue to grow after the excavation of karst tunnels, and the hydraulic pressure in these fractures changes along with such growth. This paper simplifies the fractures in the surrounding rock as flat ellipses and then identifies the critical hydraulic pressure values required for the occurrence of tensile-shear and compression-shear failures in water-filled fractures in the case of plane stress. The occurrence of tensile-shear fracture requires a larger critical hydraulic pressure than compression-shear failure in the same fracture. This paper examines the effects of fracture strike and lateral pressure coefficient on critical hydraulic pressure, and identifies compression-shear failure as the main failure mode of water-filled fractures. This paper also analyses the hydraulic pressure distribution in fractures with different extensions, and reveals that hydraulic pressure decreases along with the continuous growth of fractures and cannot completely fill a newly formed fracture with water. Fracture growth may be interrupted under the effect of hydraulic tensile shear.

  12. Two innovative pore pressure calculation methods for shallow deep-water formations

    Science.gov (United States)

    Deng, Song; Fan, Honghai; Liu, Yuhan; He, Yanfeng; Zhang, Shifeng; Yang, Jing; Fu, Lipei

    2017-11-01

    There are many geological hazards in shallow formations associated with oil and gas exploration and development in deep-water settings. Abnormal pore pressure can lead to water flow and gas and gas hydrate accumulations, which may affect drilling safety. Therefore, it is of great importance to accurately predict pore pressure in shallow deep-water formations. Experience over previous decades has shown, however, that there are not appropriate pressure calculation methods for these shallow formations. Pore pressure change is reflected closely in log data, particularly for mudstone formations. In this paper, pore pressure calculations for shallow formations are highlighted, and two concrete methods using log data are presented. The first method is modified from an E. Philips test in which a linear-exponential overburden pressure model is used. The second method is a new pore pressure method based on P-wave velocity that accounts for the effect of shallow gas and shallow water flow. Afterwards, the two methods are validated using case studies from two wells in the Yingqiong basin. Calculated results are compared with those obtained by the Eaton method, which demonstrates that the multi-regression method is more suitable for quick prediction of geological hazards in shallow layers.

  13. Pressurized hydrogenotrophic denitrification reactor for small water systems.

    Science.gov (United States)

    Epsztein, Razi; Beliavski, Michael; Tarre, Sheldon; Green, Michal

    2017-03-15

    The implementation of hydrogenotrophic denitrification is limited due to safety concerns, poor H2 utilization and low solubility of H2 gas with the resulting low transfer rate. The current paper presents the main research work conducted on a pressurized hydrogenotrophic reactor for denitrification that was recently developed. The reactor is based on a new concept suggesting that a gas-liquid equilibrium is achieved in the closed headspace of denitrifying reactor, further produced N2 gas is carried out by the effluent and gas purging is not required. The feasibility of the proposed reactor was shown for two effluent concentrations of 10 and 1 mg NO3--N/L. Hydrogen gas utilization efficiencies of 92.8% and 96.9% were measured for the two effluent concentrations, respectively. Reactor modeling predicted high denitrification rates above 4 g NO3--N/(Lreactor·d) at reasonable operational conditions. Hydrogen utilization efficiency was improved up to almost 100% by combining the pressurized reactor with a following open-to-atmosphere polishing unit. Also, the potential of the reactor to remove ClO4- was shown. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Pressure-induced volume phase transition of polyacrylamide gels in acetone-water mixtures

    Science.gov (United States)

    Kato, Eiji

    2000-07-01

    Equilibrium swelling curves of ionized polyacrylamide gels immersed in acetone-water mixtures were measured as a function of pressure up to pressures of 300 MPa. The gels, which shrank at atmospheric pressure, underwent an abrupt volume change (pressure-induced volume phase transition) from a shrunken state to a swollen state at the transition pressure. The transition pressure increased with an increase of acetone concentration. The pressure-induced volume phase transition can be interpreted by taking account of the free-energy change ΔVṡP between swollen (hydrated) and shrunken (dehydrated) states. The ΔV represents the difference between the molar volume of water structured around hydrophilic groups of polyacrylamide chains and that of free water in the bulk mixtures. The estimated value of ΔV is -3.3 mL/mol, which qualitatively agrees with that obtained from the experiments of denaturation of proteins. The pressure-induced volume phase transition is generally expected in many hydrogels.

  15. Optimization of pressure gauge locations for water distribution systems using entropy theory.

    Science.gov (United States)

    Yoo, Do Guen; Chang, Dong Eil; Jun, Hwandon; Kim, Joong Hoon

    2012-12-01

    It is essential to select the optimal pressure gauge location for effective management and maintenance of water distribution systems. This study proposes an objective and quantified standard for selecting the optimal pressure gauge location by defining the pressure change at other nodes as a result of demand change at a specific node using entropy theory. Two cases are considered in terms of demand change: that in which demand at all nodes shows peak load by using a peak factor and that comprising the demand change of the normal distribution whose average is the base demand. The actual pressure change pattern is determined by using the emitter function of EPANET to reflect the pressure that changes practically at each node. The optimal pressure gauge location is determined by prioritizing the node that processes the largest amount of information it gives to (giving entropy) and receives from (receiving entropy) the whole system according to the entropy standard. The suggested model is applied to one virtual and one real pipe network, and the optimal pressure gauge location combination is calculated by implementing the sensitivity analysis based on the study results. These analysis results support the following two conclusions. Firstly, the installation priority of the pressure gauge in water distribution networks can be determined with a more objective standard through the entropy theory. Secondly, the model can be used as an efficient decision-making guide for gauge installation in water distribution systems.

  16. Revisiting the Integrated Pressurized Thermal Shock Studies of an Aging Pressurized Water Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Bryson, J.W.; Dickson, T.L.; Malik, S.N.M.; Simonen, F.A.

    1999-08-01

    The Integrated Pressurized Thermal Shock (IPTS) studies were a series of studies performed in the early-mid 1980s as part of an NRC-organized comprehensive research project to confirm the technical bases for the pressurized thermal shock (PTS) rule, and to aid in the development of guidance for licensee plant-specific analyses. The research project consisted of PTS pilot analyses for three PWRs: Oconee Unit 1, designed by Babcock and Wilcox; Calvert Cliffs Unit 1, designed by Combustion Engineering; and H.B. Robinson Unit 2, designed by Westinghouse. The primary objectives of the IPTS studies were (1) to provide for each of the three plants an estimate of the probability of a crack propagating through the wall of a reactor pressure vessel (RPV) due to PTS; (2) to determine the dominant overcooling sequences, plant features, and operator actions and the uncertainty in the plant risk due to PTS; and (3) to evaluate the effectiveness of potential corrective actions. The NRC is currently evaluating the possibility of revising current PTS regulatory guidance. Technical bases must be developed to support any revisions. In the years since the results of IPTS studies were published, the fracture mechanics model, the embrittlement database, embrittlement correlation, inputs for flaw distributions, and the probabilistic fracture mechanics (PFM) computer code have been refined. An ongoing effort is underway to determine the impact of these fracture-technology refinements on the conditional probabilities of vessel failure calculated in the IPTS Studies. This paper discusses the results of these analyses performed for one of these plants.

  17. Capillary pressure as a unique function of electric permittivity and water saturation

    NARCIS (Netherlands)

    Plug, W.J.; Slob, E.; Van Turnhout, J.; Bruining, J.

    2007-01-01

    The relation between capillary pressure (Pc) and interfacial area has been investigated by measuring Pc and the electric permittivity at 100 kHz simultaneously as function of the water saturation, (Sw). Drainage and imbibition experiments have been conducted for sand-distilled water-gas (CO2/N2)

  18. Undermoderated spectrum MOX core study. Pressurized water-type breeder

    Energy Technology Data Exchange (ETDEWEB)

    Tochihara, Hiroshi; Komano, Yasuo [Mitsubishi Heavy Industries Ltd., Tokyo (Japan)

    1998-09-01

    The purpose of this development is the advance of the PWR core. The conversion ratio (the breeding ratio) are examined. In the case of heavy water as the coolant, the breeding ratio can be achieved about 1.1 with using a hexagonal lattice and space about 1 mm assembly fuel. In the case of light water coolant, the breeding ratio becomes about 1.0, using a hexagonal lattice and fuel space about 0.5 mm fuel assembly. Here, it reports on the situation of the examination such as the nucleus design of core, the design of fuel assembly, the heat hydraulics design of the core, the structure design and so on. (author)

  19. Water pressure and ground vibrations induced by water guns near Bandon Road Lock and Dam and Lemont, Illinois

    Science.gov (United States)

    Adams, Ryan F.; Koebel, Carolyn M.; Morrow, William S.

    2018-02-13

    Multiple geophysical sensors were used to characterize the underwater pressure field and ground vibrations of a seismic water gun and its suitability to deter the movement of Asian carps (particularly the silver [Hypophthalmichthys molitrix] and bighead [Hypophthalmichthys nobilis] carps) while ensuring the integrity of surrounding structures. The sensors used to collect this information were blast-rated hydrophones, surface- and borehole-mounted geophones, and fixed accelerometers.Results from two separate studies are discussed in this report. The Brandon Road study took place in May 2014, in the Des Plaines River, in a concrete-walled channel downstream of the Brandon Road Lock and Dam near Joliet, Illinois. The Lemont study took place in June 2014, in a segment of the dolomite setblock-lined Chicago Sanitary and Ship Canal near Lemont, Illinois.Two criteria were evaluated to assess the potential deterrence to carp migration, and to minimize the expected effect on nearby structures from discharge of the seismic water gun. The first criterion was a 5-pound-per-square-inch (lb/in2) limit for dynamic underwater pressure variations. The second criterion was a maximum velocity and acceleration disturbance of 0.75 inch per second (in/s) for sensitive machinery (such as the lock gates and pumps) and 2.0 in/s adjacent to canal walls, respectively. The criteria were based on previous studies of fish responses to dynamic pressure variations, and effects of vibrations on the structural integrity of concrete walls.The Brandon Road study evaluated the magnitude and extent of the pressure field created by two water gun configurations in the concrete-walled channel downstream of the lock where channel depths ranged from 11 to 14 feet (ft). Data from a single 80-cubic-inch (in³) water gun set at 6 ft below water surface (bws) produced a roughly cylindrical 5-lb/in2 pressure field 20 ft in radius, oriented vertically, with the radius decreasing to less than 15 ft at the water

  20. Heat sources for glacial ice melt in a West Greenland tidewater outlet glacier fjord: The role of subglacial freshwater discharge

    DEFF Research Database (Denmark)

    Bendtsen, Jørgen; Mortensen, John; Lennert, Kunuk

    2015-01-01

    The melting of tidewater outlet glaciers from the Greenland Ice Sheet contributes significantly to global sea level rise. Accelerated mass loss is related to melt-processes in front of calving glaciers, yet the role of ocean heat transports is poorly understood. Here we present the first direct...... measurements from a subglacial plume in front of a calving tidewater outlet glacier. Surface salinity in the plume corresponded to a meltwater content of 7 %, which is indicative of significant entrainment of warm bottom water and, according to plume model calculations, significant ice melt. Energy balance...... of the area near the glacier showed that ice melt was mainly due to ocean heat transport and that direct plume-associated melt was only important in periods with high meltwater discharge rates of ~100 m3 s−1. Ocean mixing outside of the plume area was thus the primary heat source for melting glacier ice....

  1. Molecular Dynamics Simulation of Water Nanodroplets on Silica Surfaces at High Air Pressures

    DEFF Research Database (Denmark)

    Zambrano, Harvey A; Jaffe, Richard Lawrence; Walther, Jens Honore

    2010-01-01

    Silicon dioxides-water systems are abundant in nature and play fundamental roles in a diversity of novel science and engineering applications. Although extensive research has been devoted to study the nature of the interaction between silica and water a complete understanding of the system has...... e.g., nanobubbles. In the present work we study the role of air on the wetting of hydrophilic systems. We conduct molecular dynamics simulations of a water nanodroplet on an amorphous silica surface at different air pressures. The interaction potentials describing the silica, water, and air...... are obtained from the literature. The silica surface is modeled by a large 32 ⨯ 32 ⨯ 2 nm amorphous SiO2 structure consisting of 180000 atoms. The water consists of 18000 water molecules surrounded by N2 and O2 air molecules corresponding to air pressures of 0 bar (vacuum), 50 bar, 100 bar and 200 bar. We...

  2. Experimental apparatus for measurement of density of supercooled water at high pressure

    Directory of Open Access Journals (Sweden)

    Peukert Pavel

    2012-04-01

    Full Text Available Thermodynamic behavior of supercooled water (metastable fluid water existing transiently below the equilibrium freezing point at high pressures was subject to many recent theoretical studies. Some of them assume that a second critical point of water exists, related to two liquid phases of supercooled water: the low-density liquid and the high-density liquid. To test these theories, an original experimental cryogenic apparatus is being developed. The volume changes are measured optically in custom-treated fused-silica capillary tubes. The capillaries are placed in a metal vessel designed for pressures up to 200 MPa. The vessel is connected to a circulation thermostat enabling a rapid change of temperature to prevent freezing. A new high-vacuum device was developed for degassing of the ultrapure water sample and filling it into the measuring capillaries. The experiments will contribute to fundamental understanding of the anomalous behavior of water and to applications in meteorology, aerospace engineering, cryobiology etc.

  3. Drilling Performance of Rock Drill by High-Pressure Water Jet under Different Configuration Modes

    Directory of Open Access Journals (Sweden)

    Songyong Liu

    2017-01-01

    Full Text Available In the rock drilling progress, the resistant force results in tools failure and the low drilling efficiency; thus, it is necessary to reduce the tools failure and enhance the drilling efficiency. In this paper, different configuration modes of drilling performance assisted with water jet are explored based on the mechanism and experiment analysis of rock drilling assisted with water jet. Moreover, the rotary sealing device with high pressure is designed to achieve the axial and rotation movement simultaneously as well as good sealing effect under high-pressure water jet. The results indicate that the NDB and NFB have better effects on drilling performance compared with that of NSB. Moreover, the high-pressure water jet is helpful not only to reduce the drill rod deflection, but also to reduce the probability of drill rod bending and improve the drill rod service life.

  4. Fatigue crack growth behavior of pressure vessel steels and submerged arc weldments in a high-temperature pressurized water environment

    Science.gov (United States)

    Liaw, P. K.; Logsdon, W. A.; Begley, J. A.

    1989-10-01

    The fatigue crack growth rate (FCGR) properties of SA508 C1 2a and SA533 Gr A C1 2 pressure vessel steels and the corresponding automatic submerged are weldments were developed in a high-temperature pressurized water (HPW) environment at 288 °C (550°F) and 7.2 MPa (1044 psi) at load ratios of 0.02 and 0.50. The HPW enviromment FCGR properties of these pressure vessel steels and submerged arc weldments were generally conservative, compared with the approrpriate American Society of Mechanical Engineers (ASME) Section XI water environmental reference curve. The growth rate of fatigue cracks in the base materials, however, was considerably faster in the HPW environment than in a corresponding 288°C (550°F) base line air environment. The growth rate of fatigue cracks in the two submerged are weldments was also accelerated in the HPW environment but to a significantly lesser degree than that demonstrated by the corresponding base materials. In the air environment, fatigue striations were observed, independent of material and load ratio, while in the HPW environment, some intergranular facets were present. The greater environmental effect on crack growth rates displayed by the base materials, as compared with the weldments, was attributed to a different sulfide composition and morphology.

  5. Tensile Strength of Water Exposed to Pressure Pulses

    DEFF Research Database (Denmark)

    Andersen, Anders Peter; Mørch, Knud Aage

    2012-01-01

    at an extended water-solid interface by imposing a tensile stress pulse which easily causes cavitation. Next, a compressive pulse of duration ~1 ms and a peak intensity of a few bar is imposed prior to the tensile stress pulse. A dramatic increase of the tensile strength is observed immediately after...... the compressive pulse, but the effect is shortlived. We presume that diffusion of non-condensable gas from the cavitation nuclei into the liquid at compression, and back again later, is responsible for the changes of tensile strength....

  6. Development of a pressurized bipolar alkaline water electrolyzer

    Energy Technology Data Exchange (ETDEWEB)

    Neves Junior, Newton Pimenta; Pinto, Edgar A. de Godoi Rodrigues; Silva, Ennio Peres da; Rapelli, Rubia; Pinto, Cristiano da Silva [Universidade Estadual de Campinas (DFA/ IFGW/UNICAMP), SP (Brazil). Inst. de Fisica Gleb Wataghin. Dept. de Fisica Aplicada], Email: nevesjr@unicamp.br; Marin Neto, Antonio Jose; Lopes, Daniel Gabriel; Camargo, Joao Carlos; Ferreira, Paulo F.P. [Hydrogen Technology (HyTron), Campinas, SP (Brazil); Furlan, Andre Luis [Universidade Estadual de Campinas (DE/FEC/UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica

    2010-07-01

    This paper reports the actual development status of a bipolar alkaline water electrolyzer with maximum production capacity of 1 m3/h of hydrogen and controlled by a PLC (Programmable Logic Controller), which also interfaces the electrolytic system with operators and other equipment, such as gas storage tanks, fuel cells and photovoltaic panels. The project also includes the construction of an electrolysis test bench to record electrical parameters (cathode, anode, separator and electrolyte potentials), the amount of produced gases and gas quality determined by gas chromatography. (author)

  7. Capillary pressure-saturation relationships for diluted bitumen and water in gravel

    Science.gov (United States)

    Hossain, S. Zubair; Mumford, Kevin G.

    2017-08-01

    Spills of diluted bitumen (dilbit) to rivers by rail or pipeline accidents can have serious long-term impacts on environment and ecology due to the submergence and trapping of oil within the river bed sediment. The extent of this problem is dictated by the amount of immobile oil available for mass transfer into the water flowing through the sediment pores. An understanding of multiphase (oil and water) flow in the sediment, including oil trapping by hysteretic drainage and imbibition, is important for the development of spill response and risk assessment strategies. Therefore, the objective of this study was to measure capillary pressure-saturation (Pc-Sw) relationships for dilbit and water, and air and water in gravel using a custom-made pressure cell. The Pc-Sw relationships obtained using standard procedures in coarse porous media are height-averaged and often require correction. By developing and comparing air-water and dilbit-water Pc-Sw curves, it was found that correction was less important in dilbit-water systems due to the smaller difference in density between the fluids. In both systems, small displacement pressures were needed for the entry of non-wetting fluid in gravel. Approximately 14% of the pore space was occupied by trapped dilbit after imbibition, which can serve as a source of long-term contamination. While air-water data can be scaled to reasonably predict dilbit-water behaviour, it cannot be used to determine the trapped amount.

  8. Indirect desalination of Red Sea water with forward osmosis and low pressure reverse osmosis for water reuse

    KAUST Repository

    Yangali-Quintanilla, Victor

    2011-10-01

    The use of energy still remains the main component of the costs of desalting water. Forward osmosis (FO) can help to reduce the costs of desalination, and extracting water from impaired sources can be beneficial in this regard. Experiments with FO membranes using a secondary wastewater effluent as a feed water and Red Sea water as a draw solution demonstrated that the technology is promising. FO coupled with low pressure reverse osmosis (LPRO) was implemented for indirect desalination. The system consumes only 50% (~1.5 kWh/m3) of the energy used for high pressure seawater RO (SWRO) desalination (2.5-4 kWh/m3), and produces a good quality water extracted from the impaired feed water. Fouling of the FO membranes was not a major issue during long-term experiments over 14 days. After 10 days of continuous FO operation, the initial flux declined by 28%. Cleaning the FO membranes with air scouring and clean water recovered the initial flux by 98.8%. A cost analysis revealed FO per se as viable technology. However, a minimum average FO flux of 10.5 L/m2-h is needed to compete with water reuse using UF-LPRO, and 5.5 L/m2-h is needed to recover and desalinate water at less cost than SWRO. © 2011 Elsevier B.V.

  9. Subglacial bedforms and conditions associated with the 1991 surge of Skeidarárjökull, Iceland

    NARCIS (Netherlands)

    Waller, R.I.; Dijk, T. van; Knudson, O.

    2008-01-01

    Much previous research at surge-type glaciers has sought to identify features diagnostic of surge-type behaviour. However, in comparatively little work have subglacial landform-sediment characteristics been used to reconstruct changing basal processes and conditions during surge events. Subglacial

  10. Experimental Study on Peak Pressure of Shock Waves in Quasi-Shallow Water

    Directory of Open Access Journals (Sweden)

    Zhenxiong Wang

    2015-01-01

    Full Text Available Based on the similarity laws of the explosion, this research develops similarity requirements of the small-scale experiments of underwater explosions and establishes a regression model for peak pressure of underwater shock waves under experimental condition. Small-scale experiments are carried out with two types of media at the bottom of the water and for different water depths. The peak pressure of underwater shock waves at different measuring points is acquired. A formula consistent with the similarity law of explosions is obtained and an analysis of the regression precision of the formula confirms its accuracy. Significance experiment indicates that the influence of distance between measuring points and charge on peak pressure of underwater shock wave is the greatest and that of water depth is the least within the range of geometric parameters. An analysis of data from experiments with different media at the bottom of the water reveals an influence on the peak pressure, as the peak pressure of a shock wave in a body of water with a bottom soft mud and rocks is about 1.33 times that of the case where the bottom material is only soft mud.

  11. Development of Extended Period Pressure-Dependent Demand Water Distribution Models

    Energy Technology Data Exchange (ETDEWEB)

    Judi, David R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mcpherson, Timothy N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-20

    Los Alamos National Laboratory (LANL) has used modeling and simulation of water distribution systems for N-1 contingency analyses to assess criticality of water system assets. Critical components considered in these analyses include pumps, tanks, and supply sources, in addition to critical pipes or aqueducts. A contingency represents the complete removal of the asset from system operation. For each contingency, an extended period simulation (EPS) is run using EPANET. An EPS simulates water system behavior over a time period, typically at least 24 hours. It assesses the ability of a system to respond and recover from asset disruption through distributed storage in tanks throughout the system. Contingencies of concern are identified as those in which some portion of the water system has unmet delivery requirements. A delivery requirement is defined as an aggregation of water demands within a service area, similar to an electric power demand. The metric used to identify areas of unmet delivery requirement in these studies is a pressure threshold of 15 pounds per square inch (psi). This pressure threshold is used because it is below the required pressure for fire protection. Any location in the model with pressure that drops below this threshold at any time during an EPS is considered to have unmet service requirements and is used to determine cascading consequences. The outage area for a contingency is the aggregation of all service areas with a pressure below the threshold at any time during the EPS.

  12. Spectroscopic and thermodynamic properties of molecular hydrogen dissolved in water at pressures up to 200 MPa.

    Science.gov (United States)

    Borysow, Jacek; del Rosso, Leonardo; Celli, Milva; Moraldi, Massimo; Ulivi, Lorenzo

    2014-04-28

    We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas. The separations between these lines were found to be significantly smaller than in gaseous hydrogen and their widths were slightly increasing with pressure. The lines were narrowing with increasing rotational quantum number. The Raman frequencies of all roto-vibrational lines were approaching the values of gas phase hydrogen with increasing pressure. Additionally, from the comparison of the integrated intensity signal of Q-branch of hydrogen to the integrated Raman signal of the water bending mode, we have obtained the concentration of hydrogen in a solution with water along the 280 K isotherm. Hydrogen solubility increases slowly with pressure, and no deviation from a smooth behaviour was observed, even reaching thermodynamic conditions very close to the transition to the stable hydrogen hydrate. The analysis of the relative hydrogen concentration in solution on the basis of a simple thermodynamic model has allowed us to obtain the molar volume for the hydrogen gas/water solution. Interestingly, the volume relative to one hydrogen molecule in solution does not decrease with pressure and, at high pressure, is larger than the volume pertinent to one molecule of water. This is in favour of the theory of hydrophobic solvation, for which a larger and more stable structure of the water molecules is expected around a solute molecule.

  13. Spectroscopic and thermodynamic properties of molecular hydrogen dissolved in water at pressures up to 200 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Borysow, Jacek, E-mail: jborysow@mtu.edu; Rosso, Leonardo del; Celli, Milva; Ulivi, Lorenzo, E-mail: lorenzo.ulivi@isc.cnr.it [Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Via Madonna del piano 10, I-50019 Sesto Fiorentino (Italy); Moraldi, Massimo [Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino (Italy)

    2014-04-28

    We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas. The separations between these lines were found to be significantly smaller than in gaseous hydrogen and their widths were slightly increasing with pressure. The lines were narrowing with increasing rotational quantum number. The Raman frequencies of all roto-vibrational lines were approaching the values of gas phase hydrogen with increasing pressure. Additionally, from the comparison of the integrated intensity signal of Q-branch of hydrogen to the integrated Raman signal of the water bending mode, we have obtained the concentration of hydrogen in a solution with water along the 280 K isotherm. Hydrogen solubility increases slowly with pressure, and no deviation from a smooth behaviour was observed, even reaching thermodynamic conditions very close to the transition to the stable hydrogen hydrate. The analysis of the relative hydrogen concentration in solution on the basis of a simple thermodynamic model has allowed us to obtain the molar volume for the hydrogen gas/water solution. Interestingly, the volume relative to one hydrogen molecule in solution does not decrease with pressure and, at high pressure, is larger than the volume pertinent to one molecule of water. This is in favour of the theory of hydrophobic solvation, for which a larger and more stable structure of the water molecules is expected around a solute molecule.

  14. The initiation of boiling during pressure transients. [water boiling on metal surfaces

    Science.gov (United States)

    Weisman, J.; Bussell, G.; Jashnani, I. L.; Hsieh, T.

    1973-01-01

    The initiation of boiling of water on metal surfaces during pressure transients has been investigated. The data were obtained by a new technique in which light beam fluctuations and a pressure signal were simultaneously recorded on a dual beam oscilloscope. The results obtained agreed with those obtained using high speed photography. It was found that, for water temperatures between 90-150 C, the wall superheat required to initiate boiling during a rapid pressure transient was significantly higher than required when the pressure was slowly reduced. This result is explained by assuming that a finite time is necessary for vapor to fill the cavity at which the bubble originates. Experimental measurements of this time are in reasonably good agreement with calculations based on the proposed theory. The theory includes a new procedure for estimating the coefficient of vaporization.

  15. Experimental study of the ecological impact of hot water/high pressure cleaning on rocky shores

    Energy Technology Data Exchange (ETDEWEB)

    Menot, L.; Chasse, C.; Kerambrun, L. [CEDRE, Plouzane (France)

    1998-09-01

    The efficiency of high pressure/hot water washing for cleaning oiled rocky shores was determined. The study also highlighted the level of tolerance towards high pressure/hot water of different intertidal biota and proposed some operational recommendations for using this technique in regards with the biota sensitivity range. The study showed that pressure, higher than 170 g/m{sup 2} on the substratum, had the most detrimental effects on intertidal biota. Temperatures between 25 and 53 degrees C had only minor effects. The most sensitive taxa were the foliaceous lichens and the barnacles. Crustose lichens and algae were found to be tolerant to both pressure and temperature. Seaweeds protected the underneath epifauna. 12 refs., 1 tab., 4 figs.

  16. Probabilistic Structural Integrity Analysis of Boiling Water Reactor Pressure Vessel under Low Temperature Overpressure Event

    Directory of Open Access Journals (Sweden)

    Hsoung-Wei Chou

    2015-01-01

    Full Text Available The probabilistic structural integrity of a Taiwan domestic boiling water reactor pressure vessel has been evaluated by the probabilistic fracture mechanics analysis. First, the analysis model was built for the beltline region of the reactor pressure vessel considering the plant specific data. Meanwhile, the flaw models which comprehensively simulate all kinds of preexisting flaws along the vessel wall were employed here. The low temperature overpressure transient which has been concluded to be the severest accident for a boiling water reactor pressure vessel was considered as the loading condition. It is indicated that the fracture mostly happens near the fusion-line area of axial welds but with negligible failure risk. The calculated results indicate that the domestic reactor pressure vessel has sufficient structural integrity until doubling of the present end-of-license operation.

  17. Fresh Water Generation from Aquifer-Pressured Carbon Storage: Annual Report FY09

    Energy Technology Data Exchange (ETDEWEB)

    Wolery, T; Aines, R; Hao, Y; Bourcier, W; Wolfe, T; Haussman, C

    2009-11-25

    This project is establishing the potential for using brine pressurized by Carbon Capture and Storage (CCS) operations in saline formations as the feedstock for desalination and water treatment technologies including reverse osmosis (RO) and nanofiltration (NF). The aquifer pressure resulting from the energy required to inject the carbon dioxide provides all or part of the inlet pressure for the desalination system. Residual brine is reinjected into the formation at net volume reduction, such that the volume of fresh water extracted balances the volume of CO{sub 2} injected into the formation. This process provides additional CO{sub 2} storage capacity in the aquifer, reduces operational risks (cap-rock fracturing, contamination of neighboring fresh water aquifers, and seismicity) by relieving overpressure in the formation, and provides a source of low-cost fresh water to offset costs or operational water needs. This multi-faceted project combines elements of geochemistry, reservoir engineering, and water treatment engineering. The range of saline formation waters is being identified and analyzed. Computer modeling and laboratory-scale experimentation are being used to examine mineral scaling and osmotic pressure limitations. Computer modeling is being used to evaluate processes in the storage aquifer, including the evolution of the pressure field. Water treatment costs are being evaluated by comparing the necessary process facilities to those in common use for seawater RO. There are presently limited brine composition data available for actual CCS sites by the site operators including in the U.S. the seven regional Carbon Sequestration Partnerships (CSPs). To work around this, we are building a 'catalog' of compositions representative of 'produced' waters (waters produced in the course of seeking or producing oil and gas), to which we are adding data from actual CCS sites as they become available. Produced waters comprise the most common

  18. Crop yields response to water pressures in the Ebro basin in Spain: risk and water policy implications

    Directory of Open Access Journals (Sweden)

    S. Quiroga

    2011-02-01

    Full Text Available The increasing pressure on water systems in the Mediterranean enhances existing water conflicts and threatens water supply for agriculture. In this context, one of the main priorities for agricultural research and public policy is the adaptation of crop yields to water pressures. This paper focuses on the evaluation of hydrological risk and water policy implications for food production. Our methodological approach includes four steps. For the first step, we estimate the impacts of rainfall and irrigation water on crop yields. However, this study is not limited to general crop production functions since it also considers the linkages between those economic and biophysical aspects which may have an important effect on crop productivity. We use statistical models of yield response to address how hydrological variables affect the yield of the main Mediterranean crops in the Ebro river basin. In the second step, this study takes into consideration the effects of those interactions and analyzes gross value added sensitivity to crop production changes. We then use Montecarlo simulations to characterize crop yield risk to water variability. Finally we evaluate some policy scenarios with irrigated area adjustments that could cope in a context of increased water scarcity. A substantial decrease in irrigated land, of up to 30% of total, results in only moderate losses of crop productivity. The response is crop and region specific and may serve to prioritise adaptation strategies.

  19. Ultra-high pressure water jetting for coating removal and surface preparation

    Science.gov (United States)

    Johnson, Spencer T.

    1995-01-01

    This paper shall examine the basics of water technology with particular attention paid to systems currently in use and some select new applications. By providing an overview of commercially available water jet systems in the context of recent case histories, potential users may evaluate the process for future applications. With the on going introduction of regulations prohibiting the use of chemical paint strippers, manual scrapping and dry abrasive media blasting, the need for an environmentally compliant coating removal process has been mandated. Water jet cleaning has been a traditional part of many industrial processed for year, although it has only been in the last few years that reliable pumping equipment capable of ultra-high pressure operation have become available. With the advent of water jet pumping equipment capable of sustaining pressures in excess of 36,000 psi. there has been shift away from lower pressure, high water volume systems. One of the major factors in driving industry to seek higher pressures is the ability to offer higher productivity rates while lowering the quantity of water used and subsequently reprocessed. Among benefits of the trend toward higher pressure/lower volume systems is the corresponding reduction in water jet reaction forces making hand held water jetting practical and safe. Other unique applications made possible by these new generation pumping systems include the use of alternative fluids including liquid ammonia for specialized and hazardous material removal applications. A review of the equipment used and the required modifications will be presented along with the conclusions reached reached during this test program.

  20. Pressurized water extraction of isoflavones by experimental design from soybean flour and Soybean Protein Isolate.

    Science.gov (United States)

    Moras, Benjamin; Rey, Stéphane; Vilarem, Gérard; Pontalier, Pierre-Yves

    2017-01-01

    A Doehlert experimental design was conducted and surface response methodology was used to determine the effect of temperature, contact time and solid liquid ratio on isoflavone extraction from soybean flour or Soybean Protein Isolate in pressurized water system. The optimal conditions conducted gave an extraction yield of 85% from soybean flour. For Soybean Protein Isolate compared to soybean flour, the isoflavone extraction yield is 61%. This difference could be explained by higher aglycon content, while aglycon appears to be the least extracted isoflavone by pressurized water. The solid liquid ratio in the ASE cell was the overriding factor in obtaining high yields with both soybean products, while temperature has less influence. A high temperature causes conversion of the malonyls-glucosides and glucosides isoflavone derivatives into glucosides or aglycons forms. pressurized water extraction showed a high solubilization of protein material up to 95% of inserted Soybean Protein Isolate. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Effects of water availability and pest pressures on tea (Camellia sinensis) growth and functional quality.

    Science.gov (United States)

    Ahmed, Selena; Orians, Colin M; Griffin, Timothy S; Buckley, Sarabeth; Unachukwu, Uchenna; Stratton, Anne Elise; Stepp, John Richard; Robbat, Albert; Cash, Sean; Kennelly, Edward J

    2014-01-01

    Extreme shifts in water availability linked to global climate change are impacting crops worldwide. The present study examines the direct and interactive effects of water availability and pest pressures on tea (Camellia sinensis; Theaceae) growth and functional quality. Manipulative greenhouse experiments were used to measure the effects of variable water availability and pest pressures simulated by jasmonic acid (JA) on tea leaf growth and secondary metabolites that determine tea quality. Water treatments were simulated to replicate ideal tea growing conditions and extreme precipitation events in tropical southwestern China, a major centre of tea production. Results show that higher water availability and JA significantly increased the growth of new leaves while their interactive effect was not significant. The effect of water availability and JA on tea quality varied with individual secondary metabolites. Higher water availability significantly increased total methylxanthine concentrations of tea leaves but there was no significant effect of JA treatments or the interaction of water and JA. Water availability, JA treatments or their interactive effects had no effect on the concentrations of epigallocatechin 3-gallate. In contrast, increased water availability resulted in significantly lower concentrations of epicatechin 3-gallate but the effect of JA and the interactive effects of water and JA were not significant. Lastly, higher water availability resulted in significantly higher total phenolic concentrations but there was no significant impact of JA and their interaction. These findings point to the fascinating dynamics of climate change effects on tea plants with offsetting interactions between precipitation and pest pressures within agro-ecosystems, and the need for future climate studies to examine interactive biotic and abiotic effects.

  2. Total dissolved gas, barometric pressure, and water temperature data, lower Columbia River, Oregon and Washington, 1996

    Science.gov (United States)

    Tanner, Dwight Q.; Harrison, Howard E.; McKenzie, Stuart W.

    1996-01-01

    Increased levels of total dissolved gas pressure can cause gas-bubble trauma in fish downstream from dams on the Columbia River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey collected data on total dissolved gas pressure, barometric pressure, water temperature, and dissolved oxygen pressure at 11 stations on the lower Columbia River from the John Day forebay (river mile 215.6) to Wauna Mill (river mile 41.9) from March to September 1996. Methods of data collection, review, and processing are described in this report. Summaries of daily minimum, maximum, and mean hourly values are presented for total dissolved gas pressure, barometric pressure, and water temperature. Hourly values for these parameters are presented graphically. Dissolved oxygen data are not presented in this report because the quality-control data show that the data have poor precision and high bias. Suggested changes to monitoring procedures for future studies include (1) improved calibration procedures for total dissolved gas and dissolved oxygen to better define accuracy at elevated levels of supersaturation and (2) equipping dissolved oxygen sensors with stirrers because river velocities at the shoreline monitoring stations probably cannot maintain an adequate flow of water across the membrane surface of the dissolved oxygen sensor.

  3. Simulation of Pressure-swing Distillation for Separation of Ethyl Acetate-Ethanol-Water

    Science.gov (United States)

    Yang, Jing; Zhou, Menglin; Wang, Yujie; Zhang, Xi; Wu, Gang

    2017-12-01

    In the light of the azeotrope of ethyl acetate-ethanol-water, a process of pressure-swing distillation is proposed. The separation process is simulated by Aspen Plus, and the effects of theoretical stage number, reflux ratio and feed stage about the pressure-swing distillation are optimized. Some better process parameters are as follows: for ethyl acetate refining tower, the pressure is 500.0 kPa, theoretical stage number is 16, reflux ratio is 0.6, feed stage is 5; for crude ethanol tower, the pressure is 101.3 kPa, theoretical stage number is 15, reflux ratio is 0.3, feed stage is 4; for ethanol tower, the pressure is 101.3 kPa, theoretical stage number is 25, reflux ratio is 1.2, feed stage is 10. The mass fraction of ethyl acetate in the bottom of the ethyl acetate refining tower reaches 0.9990, the mass fraction of ethanol in the top of the ethanol tower tower reaches 0.9017, the mass fraction of water in the bottom of the ethanol tower tower reaches 0.9622, and there is also no ethyl acetate in the bottom of the ethanol tower. With laboratory tests, experimental results are in good agreement with the simulation results, which indicates that the separation of ethyl acetate ethanol water can be realized by the pressure-swing distillation separation process. Moreover, it has certain practical significance to industrial practice.

  4. Long-term subglacial sliding patterns based on a sliding law with cavitation

    DEFF Research Database (Denmark)

    Ugelvig, Sofie Vej; Egholm, D.L.

    In ice-sheet models and glacial landscape evolution models, subglacial sliding rates are often related to basal shear stress by a power-law. However, the power-law relationship implies that the subglacial bed can provide unlimited levels of basal drag as sliding rates increases, which is recogniz...... of cavitation on glacier sliding. Proc. R. Soc. A , 461, 609-627 (2005). Egholm et al. Modeling the flow of glaciers in steep terrains: The integrated second-order shallow ice approximation (iSOSIA). Journal of Geophysical Research, 116, F02012 (2011)....

  5. Feedbacks between subglacial dynamics and long-term glacial landscape evolution

    DEFF Research Database (Denmark)

    Brædstrup, Christian; Egholm, D.L.; Ugelvig, Sofie Vej

    computational experiments with a higher-order ice sheet model (Egholm et al., 2009) capable of simulating the long-term evolution of subglacial dynamics at a high spatial resolution. The orientation and magnitude of subglacial stress components depend not only on ice thickness and ice surface gradients...... associated to the level of cavitation (Iverson, 2012). The highly non-linear computational experiments are made possible by new and very efficient GPU-accelerated multigrid algorithms. The computational experiments show that higher-order stress effects associated with local changes to the bed gradient...

  6. The effects of pulse pressure from seismic water gun technology on Northern Pike

    Science.gov (United States)

    Gross, Jackson A.; Irvine, Kathryn M.; Wilmoth, Siri K.; Wagner, Tristany L.; Shields, Patrick A; Fox, Jeffrey R.

    2013-01-01

    We examined the efficacy of sound pressure pulses generated from a water gun for controlling invasive Northern Pike Esox lucius. Pulse pressures from two sizes of water guns were evaluated for their effects on individual fish placed at a predetermined random distance. Fish mortality from a 5,620.8-cm3 water gun (peak pressure source level = 252 dB referenced to 1 μP at 1 m) was assessed every 24 h for 168 h, and damage (intact, hematoma, or rupture) to the gas bladder, kidney, and liver was recorded. The experiment was replicated with a 1,966.4-cm3 water gun (peak pressure source level = 244 dB referenced to 1 μP at 1 m), but fish were euthanized immediately. The peak sound pressure level (SPLpeak), peak-to-peak sound pressure level (SPLp-p), and frequency spectrums were recorded, and the cumulative sound exposure level (SELcum) was subsequently calculated. The SPLpeak, SPLp-p, and SELcum were correlated, and values varied significantly by treatment group for both guns. Mortality increased and organ damage was greater with decreasing distance to the water gun. Mortality (31%) by 168 h was only observed for Northern Pike exhibiting the highest degree of organ damage. Mortality at 72 h and 168 h postexposure was associated with increasing SELcum above 195 dB. The minimum SELcum calculated for gas bladder rupture was 199 dB recorded at 9 m from the 5,620.8-cm3 water gun and 194 dB recorded at 6 m from the 1,966.4-cm3water gun. Among Northern Pike that were exposed to the large water gun, 100% of fish exposed at 3 and 6 m had ruptured gas bladders, and 86% exposed at 9 m had ruptured gas bladders. Among fish that were exposed to pulse pressures from the smaller water gun, 78% exhibited gas bladder rupture. Results from these initial controlled experiments underscore the potential of water guns as a tool for controlling Northern Pike.

  7. Pressure of drinking water network on the Meyrin site to be boosted

    CERN Multimedia

    2004-01-01

    In the framework of the refurbishment of CERN's drinking water supply system, the final part of the network on the Meyrin site is to be connected to the pumping station operated by Services Industriels de Genève, bringing about a significant increase in the network pressure of up to 5 bar. This means that from January 2005 onwards, the water pressure in buildings will be increased from 2 - 4 bar to 7 - 9 bar. The TS Department will be checking and upgrading the drinking water supply equipment in toilets and washrooms. All users with devices connected to the water supply system are kindly requested to check that these are compatible with the new pressure levels. More information on the buildings affected, the new pressure levels and the dates on which the changes will come into effect can be found at: https://edms.cern.ch/document/525717/1 Should any equipment under your responsibility be incompatible with the future pressure levels, please contact the Technical Control Room on 72201.

  8. Managing risks from virus intrusion into water distribution systems due to pressure transients.

    Science.gov (United States)

    Yang, Jian; LeChevallier, Mark W; Teunis, Peter F M; Xu, Minhua

    2011-06-01

    Low or negative pressure transients in water distribution systems, caused by unexpected events (e.g. power outages) or routine operation/maintenance activities, are usually brief and thus are rarely monitored or alarmed. Previous studies have shown connections between negative pressure events in water distribution systems and potential public health consequences. Using a quantitative microbial risk assessment (QMRA) model previously developed, various factors driving the risk of viral infection from intrusion were evaluated, including virus concentrations external to the distribution system, maintenance of a disinfectant residual, leak orifice sizes, the duration and the number of nodes drawing negative pressures. The most sensitive factors were the duration and the number of nodes drawing negative pressures, indicating that mitigation practices should be targeted to alleviate the severity of low/negative pressure transients. Maintaining a free chlorine residual of 0.2 mg/L or above is the last defense against the risk of viral infection due to negative pressure transients. Maintaining a chloramine residual did not appear to significantly reduce the risk. The effectiveness of ensuring separation distances from sewer mains to reduce the risk of infection may be system-specific. Leak detection/repair and cross-connection control should be prioritized in areas vulnerable to negative pressure transients.

  9. Franco-German nuclear cooperation: from the `common product` to the first European pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Vignon, D. [Societe Franco-Americaine de Constructions Atomiques (FRAMATOME), 92 - Paris-la-Defense (France)

    1999-01-01

    It has now been 10 years since Framatome and Siemens decided to collaborate on the design and sales of an advanced nuclear power plant (NPP) model based on pressurized water reactor (PWR) technology. Originally called the `common product`, this model was renamed the European pressurized water reactor when Electricite de France (EDF) and the German electric utilities joined this cooperative development effort in 1992. Since the beginning, this cooperation has been formalized in the framework of an agreement that led to the founding of a joint and equally owned subsidiary, Nucler Power International (NPI), which is reponsible for leading the development of the new model and later handling its export sales.

  10. Methodology for Calculation of Pressure Impulse Distribution at Gas-Impulse Regeneration of Water Well Filters

    Directory of Open Access Journals (Sweden)

    V. V. Ivashechkin

    2010-01-01

    Full Text Available The paper considers a mathematical model for process of pressure impulse distribution in a water well which appear as a result of underwater gas explosions in cylindrical and spherical explosive chambers with elastic shells and in a rigid cylindrical chamber which is open from the bottom. The proposed calculation methodology developed on the basis of the mathematical model makes it possible to determine pressure in the impulse on a filter wall and at any point of a water well pre-filter zone. 

  11. The analysis of energy efficiency in water electrolysis under high temperature and high pressure

    Science.gov (United States)

    Hourng, L. W.; Tsai, T. T.; Lin, M. Y.

    2017-11-01

    This paper aims to analyze the energy efficiency of water electrolysis under high pressure and high temperature conditions. The effects of temperature and pressure on four different kinds of reaction mechanisms, namely, reversible voltage, activation polarization, ohmic polarization, and concentration polarization, are investigated in details. Results show that the ohmic and concentration over-potentials are increased as temperature is increased, however, the reversible and activation over-potentials are decreased as temperature is increased. Therefore, the net efficiency is enhanced as temperature is increased. The efficiency of water electrolysis at 350°C/100 bars is increased about 17%, compared with that at 80°C/1bar.

  12. Energetic behavior of the pure silica ITQ-12 (ITW) zeolite under high pressure water intrusion.

    Science.gov (United States)

    Khay, Ismail; Tzanis, Lydie; Daou, T Jean; Nouali, Habiba; Ryzhikov, Andrey; Patarin, Joël

    2013-12-14

    Experimental water intrusion-extrusion isotherms were obtained at room temperature on pure silica ITW-type zeolites (ITQ-12 zeosil). The water intrusion is obtained by applying a high hydraulic pressure corresponding to the intrusion step. When the pressure is released, the water extrusion occurs at a similar pressure to that of the intrusion one. Therefore, the "ITW zeosil-water" system behaves like a spring and the phenomenon is reproducible over several cycles. Several characterization techniques have been performed before and after water intrusion-extrusion experiments in order to reveal the presence or the lack of defects after such experiments. Structural modifications at the long range order cannot be observed by XRD analysis after three water intrusion-extrusion cycles. However, solid state NMR spectroscopy provides evidence of the presence of Q3 groups revealing the breaking of some siloxane bridges after the intrusion step. The "ITW zeosil-water" system can restore 100% of the stored energy corresponding to about 8 J g(-1).

  13. Durable Suit Bladder with Improved Water Permeability for Pressure and Environment Suits

    Science.gov (United States)

    Bue, Grant C.; Kuznetz, Larry; Orndoff, Evelyne; Tang, Henry; Aitchison, Lindsay; Ross, Amy

    2009-01-01

    Water vapor permeability is shown to be useful in rejecting heat and managing moisture accumulation in launch-and-entry pressure suits. Currently this is accomplished through a porous Gortex layer in the Advanced Crew and Escape Suit (ACES) and in the baseline design of the Constellation Suit System Element (CSSE) Suit 1. Non-porous dense monolithic membranes (DMM) that are available offer potential improvements for water vapor permeability with reduced gas leak. Accordingly, three different pressure bladder materials were investigated for water vapor permeability and oxygen leak: ElasthaneTM 80A (thermoplastic polyether urethane) provided from stock polymer material and two custom thermoplastic polyether urethanes. Water vapor, carbon dioxide and oxygen permeability of the DMM's was measured in a 0.13 mm thick stand-alone layer, a 0.08 mm and 0.05 mm thick layer each bonded to two different nylon and polyester woven reinforcing materials. Additional water vapor permeability and mechanical compression measurements were made with the reinforced 0.05 mm thick layers, further bonded with a polyester wicking and overlaid with moistened polyester fleece thermal underwear .This simulated the pressure from a supine crew person. The 0.05 mm thick nylon reinforced sample with polyester wicking layer was further mechanically tested for wear and abrasion. Concepts for incorporating these materials in launch/entry and Extravehicular Activity pressure suits are presented.

  14. Refined broad-scale sub-glacial morphology of Aurora Subglacial Basin, East Antarctica derived by an ice-dynamics-based interpolation scheme

    Directory of Open Access Journals (Sweden)

    J. L. Roberts

    2011-07-01

    Full Text Available Ice thickness data over much of East Antarctica are sparse and irregularly distributed. This poses difficulties for reconstructing the homogeneous coverage needed to properly assess underlying sub-glacial morphology and fundamental geometric constraints on sea level rise. Here we introduce a new physically-based ice thickness interpolation scheme and apply this to existing ice thickness data in the Aurora Subglacial Basin region. The skill and robustness of the new reconstruction is demonstrated by comparison with new data from the ICECAP project. The interpolated morphology shows an extensive marine-based ice sheet, with considerably more area below sea-level than shown by prior studies. It also shows deep features connecting the coastal grounding zone with the deepest regions in the interior. This has implications for ice sheet response to a warming ocean and underscores the importance of obtaining additional high resolution data in these marginal zones for modelling ice sheet evolution.

  15. Water surface elevations recorded by submerged pressure transducers along the upper Willamette River, Oregon, Spring, 2015

    Science.gov (United States)

    Lind, Greg D.; Wellman, Roy E.; Mangano, Joseph F.

    2017-01-01

    Water-surface elevations were recorded by submerged pressure transducers in Spring, 2015 along the upper Willamette River, Oregon, between Eugene and Corvallis. The water-surface elevations were surveyed by using a real-time kinematic global positioning system (RTK-GPS) at each pressure sensor location. These water-surface elevations were logged over a small range of discharges, from 4,600 cubic feet per second to 10,800 cubic feet per second at Harrisburg, OR. These datasets were collected for equipment calibration and validation for the National Aeronautics and Space Administration’s (NASA) Surface Water and Ocean Topography (SWOT) satellite mission. This is one of multiple datasets that will be released for this effort.

  16. Negative Pressures and the First Water Siphon Taller than 10.33 Meters.

    Science.gov (United States)

    Vera, Francisco; Rivera, Rodrigo; Romero-Maltrana, Diego; Villanueva, Jaime

    2016-01-01

    A siphon is a device that is used to drain a container, with water rising inside a hose in the form of an inverted U and then going down towards a discharge point placed below the initial water level. The siphon is the first of a number of inventions of the ancients documented about 2.000 years ago by Hero of Alexandria in his treatise Pneumatics, and although the explanation given by Hero was essentially correct, there is nowadays a controversy about the underlying mechanism that explains the working of this device. Discussions concerning the physics of a siphon usually refer to concepts like absolute negative pressures, the strength of liquid's cohesion and the possibility of a siphon working in vacuum or in the presence of bubbles. Torricelli understood the working principle of the barometer and the impossibility of pumping water out of wells deeper than 10.33 m. Following Torricelli's ideas it would also not be possible to build a siphon that drives pure water to ascend higher than 10.33 m. In this work, we report the first siphon that drives water (with surfactant) to ascend higher than the Torricellian limit. Motivated by the rising of sap in trees, we built a 15.4 m siphon that shows that absolute negative pressures are not prohibited, that cohesion plays an important role in transmitting forces through a fluid, and that surfactants can help to the transport of water in a metastable regime of negative pressures.

  17. Negative Pressures and the First Water Siphon Taller than 10.33 Meters.

    Directory of Open Access Journals (Sweden)

    Francisco Vera

    Full Text Available A siphon is a device that is used to drain a container, with water rising inside a hose in the form of an inverted U and then going down towards a discharge point placed below the initial water level. The siphon is the first of a number of inventions of the ancients documented about 2.000 years ago by Hero of Alexandria in his treatise Pneumatics, and although the explanation given by Hero was essentially correct, there is nowadays a controversy about the underlying mechanism that explains the working of this device. Discussions concerning the physics of a siphon usually refer to concepts like absolute negative pressures, the strength of liquid's cohesion and the possibility of a siphon working in vacuum or in the presence of bubbles. Torricelli understood the working principle of the barometer and the impossibility of pumping water out of wells deeper than 10.33 m. Following Torricelli's ideas it would also not be possible to build a siphon that drives pure water to ascend higher than 10.33 m. In this work, we report the first siphon that drives water (with surfactant to ascend higher than the Torricellian limit. Motivated by the rising of sap in trees, we built a 15.4 m siphon that shows that absolute negative pressures are not prohibited, that cohesion plays an important role in transmitting forces through a fluid, and that surfactants can help to the transport of water in a metastable regime of negative pressures.

  18. Effects of High Hydrostatic Pressure on Water Absorption of Adzuki Beans

    Directory of Open Access Journals (Sweden)

    Shigeaki Ueno

    2015-05-01

    Full Text Available The effect of high hydrostatic pressure (HHP treatment on dried soybean, adzuki bean, and kintoki kidney bean, which are low-moisture-content cellular biological materials, was investigated from the viewpoint of water absorption. The samples were vacuum-packed with distilled water and pressurized at 200 MPa and 25 °C for 10 min. After the HHP treatment, time courses of the moisture contents of the samples were measured, and the dimensionless moisture contents were estimated. Water absorption in the case of soybean could be fitted well by a simple water diffusion model. High pressures were found to have negligible effects on water absorption into the cotyledon of soybean and kintoki kidney bean. A non-linear least square method based on the Weibull equation was applied for the adzuki beans, and the effective water diffusion coefficient was found to increase significantly from 8.6 × 10−13 to 6.7 × 10−10 m2/s after HHP treatment. Approximately 30% of the testa of the adzuki bean was damaged upon HHP treatment, which was comparable to the surface area of the testa in the partially peeled adzuki bean sample. Thus, HHP was confirmed to promote mass transfer to the cotyledon of legumes with a tight testa.

  19. Low-pressure membrane integrity tests for drinking water treatment: A review.

    Science.gov (United States)

    Guo, H; Wyart, Y; Perot, J; Nauleau, F; Moulin, P

    2010-01-01

    Low-pressure membrane systems, including microfiltration (MF) and ultrafiltration (UF) membranes, are being increasingly used in drinking water treatments due to their high level of pathogen removal. However, the pathogen will pass through the membrane and contaminate the product if the membrane integrity is compromised. Therefore, an effective on-line integrity monitoring method for MF and UF membrane systems is essential to guarantee the regulatory requirements for pathogen removal. A lot of works on low-pressure membrane integrity tests have been conducted by many researchers. This paper provides a literature review about different low-pressure membrane integrity monitoring methods for the drinking water treatment, including direct methods (pressure-based tests, acoustic sensor test, liquid porosimetry, etc.) and indirect methods (particle counting, particle monitoring, turbidity monitoring, surrogate challenge tests). Additionally, some information about the operation of membrane integrity tests is presented here. It can be realized from this review that it remains urgent to develop an alternative on-line detection technique for a quick, accurate, simple, continuous and relatively inexpensive evaluation of low-pressure membrane integrity. To better satisfy regulatory requirements for drinking water treatments, the characteristic of this ideal membrane integrity test is proposed at the end of this paper.

  20. Water cycle and its management for plant habitats at reduced pressures

    Science.gov (United States)

    Rygalov, Vadim Y.; Fowler, Philip A.; Wheeler, Raymond M.; Bucklin, Ray A.

    2004-01-01

    Experimental and mathematical models were developed for describing and testing temperature and humidity parameters for plant production in bioregenerative life support systems. A factor was included for analyzing systems operating at low (10-101.3 kPa) pressure to reduce gas leakage and structural mass (e.g., inflatable greenhouses for space application). The expected close relationship between temperature and relative humidity was observed, along with the importance of heat exchanger coil temperature and air circulation rate. The presence of plants in closed habitats results in increased water flux through the system. Changes in pressure affect gas diffusion rates and surface boundary layers, and change convective transfer capabilities and water evaporation rates. A consistent observation from studies with plants at reduced pressures is increased evapotranspiration rates, even at constant vapor pressure deficits. This suggests that plant water status is a critical factor for managing low-pressure production systems. The approach suggested should help space mission planners design artificial environments in closed habitats.

  1. Formation of genotoxic compounds by medium pressure ultra violet treatment of nitrate rich water

    NARCIS (Netherlands)

    Martijn, A.J.; Boersma, M.G.; Vervoort, Jacques; Rietjens, I.; Kruithof, J.C.

    2014-01-01

    Genotoxic compounds were produced by full-scale medium pressure (MP) ultraviolet hydrogen peroxide (UV/H2O2) treatment of nitrate-rich pretreated surface water. It was hypothesized that this formation was caused by the reaction of nitrate photolysis intermediates with natural organic matter (NOM).

  2. An investigation of rock fall and pore water pressure using LIDAR in Highway 63 rock cuts.

    Science.gov (United States)

    2014-07-01

    The purpose of this research work is compare LIDAR scanning measurements of rock fall with the natural changes in groundwater level to determining the effect of water pressures (levels) on rock fall. To collect the information of rock cut volume chan...

  3. 77 FR 23513 - Updated Aging Management Criteria for Reactor Vessel Internal Components of Pressurized Water...

    Science.gov (United States)

    2012-04-19

    ... COMMISSION Updated Aging Management Criteria for Reactor Vessel Internal Components of Pressurized Water... Management Criteria for PWR Reactor Vessel Internal Components.'' The original notice provided the ADAMS... published a notice requesting public comments on draft LR-ISG-2011-04, ``Updated Aging Management Criteria...

  4. 77 FR 16270 - Updated Aging Management Criteria for Reactor Vessel Internal Components of Pressurized Water...

    Science.gov (United States)

    2012-03-20

    ... COMMISSION Updated Aging Management Criteria for Reactor Vessel Internal Components of Pressurized Water... license renewal interim staff guidance (LR-ISG), LR-ISG-2011-04, ``Updated Aging Management Criteria for... Aging Lessons Learned (GALL) Report for the aging management of stainless steel structures and...

  5. Low pressure water vapour plasma treatment of surfaces for biomolecules decontamination

    DEFF Research Database (Denmark)

    Fumagalli, F; Kylian, O; Amato, Letizia

    2012-01-01

    Decontamination treatments of surfaces are performed on bacterial spores, albumin and brain homogenate used as models of biological contaminations in a low-pressure, inductively coupled plasma reactor operated with water-vapour-based gas mixtures. It is shown that removal of contamination can...... vapour plasma process are discussed for practical applications in medical devices decontamination....

  6. An improved film evaporation correlation for saline water at sub-atmospheric pressures

    KAUST Repository

    Shahzada, Muhammad Wakil

    2011-10-03

    This paper presents an investigation of heat transfer correlation in a falling-film evaporator working with saline water at sub-atmospheric pressures. The experiments are conducted at different salinity levels ranging from 15000 to 90000 ppm, and the pressures were maintained between 0.92 to 2.81 kPa (corresponds to saturation temperatures of 5.9 – 23 0C). The effect of salinity, saturation pressures and chilled water temperatures on the heat transfer coefficient are accounted in the modified film evaporation correlations. The results are fitted to the Han & Fletcher\\'s and Chun & Seban\\'s falling-film correlations which are used in desalination industry. We modify the said correlations by adding salinity and saturation temperature corrections with respective indices to give a better agreement to our measured data.

  7. An improved film evaporation correlation for saline water at sub-atmospheric pressures

    Science.gov (United States)

    Shahzada, Muhammad Wakil; Ng, Kim Choon; Thu, Kyaw; Myat, Aung; Gee, Chun Won

    2012-06-01

    This paper presents an investigation of heat transfer correlation in a falling-film evaporator working with saline water at sub-atmospheric pressures. The experiments are conducted at different salinity levels ranging from 15000 to 90000 ppm, and the pressures were maintained between 0.92 to 2.81 kPa (corresponds to saturation temperatures of 5.9 - 23 0C). The effect of salinity, saturation pressures and chilled water temperatures on the heat transfer coefficient are accounted in the modified film evaporation correlations. The results are fitted to the Han & Fletcher's and Chun & Seban's falling-film correlations which are used in desalination industry. We modify the said correlations by adding salinity and saturation temperature corrections with respective indices to give a better agreement to our measured data.

  8. Sensitivity of total stress to changes in externally applied water pressure in KBS-3 buffer bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, J.F.; Birchall, D.J. [British Geological Survey, Chemical and Biological Hazards Programme, Kingsley Dunham Centre (United Kingdom)

    2007-04-15

    In the current Swedish repository design concept, composite copper and steel canisters containing spent nuclear fuel will be placed in large diameter disposal boreholes drilled into the floor of the repository tunnels. The space around each canister will be filled with pre-compacted bentonite which over time will draw in the surrounding ground water and swell, closing up any construction joints. However, for the purposes of performance assessment, it is necessary to consider the effect of glacial loading of a future repository and its impact on the mechanical behaviour of the bentonite, in particular, the sensitivity of total stress to changes in porewater pressure (backpressure). Two experimental histories have been undertaken using a custom-designed constant volume and radial flow (CVRF) apparatus. In both tests backpressure was varied in a number of incremental and decremental cycles while total stress, porewater pressure and volumetric flow rate were continuously monitored. The swelling pressure of the buffer clay at dry densities of 1.8 Mg/m{sup 3} and 1.61 Mg/m{sup 3} was determined to be around 5.5 MPa and 7.2 MPa respectively. For initial ascending porewater pressure histories the average proportionality factor {alpha} ranged from 0.86 and 0.92. Data exhibited a general trend of increasing {alpha} with increasing backpressure. In test Mx80-11 this was supported by analysis of the water inflow data which indicated a reduction in system compressibility. Asymptotic values of porewater pressure within the clay are in good agreement with externally applied backpressure values. Inspection of data provides no evidence for the development of hydraulic thresholds within the clay, subject to the boundary conditions of this test geometry. Analysis of the stress data demonstrates significant hysteresis between ascending and descending porewater pressure histories. The amount of hysteresis appears to be linked to the magnitude of the backpressure applied to the specimen

  9. Viable cold-tolerant iron-reducing microorganisms in geographically diverse subglacial environments

    Science.gov (United States)

    Nixon, Sophie L.; Telling, Jon P.; Wadham, Jemma L.; Cockell, Charles S.

    2017-03-01

    Subglacial environments are known to harbour metabolically diverse microbial communities. These microbial communities drive chemical weathering of underlying bedrock and influence the geochemistry of glacial meltwater. Despite its importance in weathering reactions, the microbial cycling of iron in subglacial environments, in particular the role of microbial iron reduction, is poorly understood. In this study we address the prevalence of viable iron-reducing microorganisms in subglacial sediments from five geographically isolated glaciers. Iron-reducing enrichment cultures were established with sediment from beneath Engabreen (Norway), Finsterwalderbreen (Svalbard), Leverett and Russell glaciers (Greenland), and Lower Wright Glacier (Antarctica). Rates of iron reduction were higher at 4 °C compared with 15 °C in all but one duplicated second-generation enrichment culture, indicative of cold-tolerant and perhaps cold-adapted iron reducers. Analysis of bacterial 16S rRNA genes indicates Desulfosporosinus were the dominant iron-reducing microorganisms in low-temperature Engabreen, Finsterwalderbreen and Lower Wright Glacier enrichments, and Geobacter dominated in Russell and Leverett enrichments. Results from this study suggest microbial iron reduction is widespread in subglacial environments and may have important implications for global biogeochemical iron cycling and export to marine ecosystems.

  10. Recent technical developments at the IMAU: A new generation of AWS and wireless subglacial measurements

    NARCIS (Netherlands)

    Smeets, C.J.P.P.; Boot, W.; van den Broeke, M.R.; van de Wal, R.S.W.

    2011-01-01

    Two technical developments are presented: a new generation of AWS and a wireless subglacial measurement system. Both systems build on the experience of the IMAU in developing GPS systems (Den Ouden et al., 2010). Combining methods to minimize energy consumption and wireless communication form the

  11. Passive containment cooling system with drywell pressure regulation for boiling water reactor

    Science.gov (United States)

    Hill, Paul R.

    1994-01-01

    A boiling water reactor having a regulating valve for placing the wetwell in flow communication with an intake duct of the passive containment cooling system. This subsystem can be adjusted to maintain the drywell pressure at (or slightly below or above) wetwell pressure after the initial reactor blowdown transient is over. This addition to the PCCS design has the benefit of eliminating or minimizing steam leakage from the drywell to the wetwell in the longer-term post-LOCA time period and also minimizes the temperature difference between drywell and wetwell. This in turn reduces the rate of long-term pressure buildup of the containment, thereby extending the time to reach the design pressure limit.

  12. Application of pressure assisted forward osmosis for water purification and reuse of reverse osmosis concentrate from a water reclamation plant

    KAUST Repository

    Jamil, Shazad

    2016-07-26

    The use of forward osmosis (FO) is growing among the researchers for water desalination and wastewater treatment due to use of natural osmotic pressure of draw solute. In this study pressure assisted forward osmosis (PAFO) was used instead of FO to increase the water production rate. In this study a low concentration of draw solution (0.25 M KCl) was applied so that diluted KCl after PAFO operation can directly be used for fertigation. The performance of PAFO was investigated for the treatment of reverse osmosis concentrate (ROC) from a water reclamation plant. The water production in PAFO was increased by 9% and 29% at applied pressure of 2 and 4 bars, respectively, to feed side based on 90 h of experiments. Granular activated carbon (GAC) pretreatment and HCl softening were used to reduce organic fouling and scaling prior to application of PAFO. It reduced total organic carbon (TOC) and total inorganic carbon (TIC) by around 90% and 85%, respectively from untreated ROC. Subsequently, this led to an increase in permeate flux. In addition, GAC pretreatment adsorbed 12 out of 14 organic micropollutants tested from ROC to below detection limit. This application enabled to minimise the ROC volume with a sustainable operation and produced high quality and safe water for discharge or reuse. The draw solution (0.25 M KCl) used in this study was diluted to 0.14 M KCl, which is a suitable concentration (10 kg/m3) for fertigation, due to water transport from feed solution. © 2016 Elsevier B.V.

  13. Effect of renal venous pressure elevation on tubular sodium and water reabsorption in the dog kidney

    DEFF Research Database (Denmark)

    Abildgaard, U; Amtorp, O; Holstein-Rathlou, N H

    1988-01-01

    of [51Cr]EDTA was used as a measure of the rate of glomerular filtration (GFR). GFR, urinary excretion rates of sodium and water, and lithium clearance were used for assessing the absolute and fractional reabsorption rates of sodium and water in the proximal as well as in more distal segments......This study was performed in order to quantify the effects of renal venous pressure (RVP) elevation on absolute and fractional reabsorption rates of sodium and water in proximal and distal segments of the nephron in dog kidneys. Renal blood flow (RBF) was measured electromagnetically. Clearance...

  14. Licensing assessment of the Candu Pressurized Heavy Water Reactor. Preliminary safety information document. Volume II. [USA

    Energy Technology Data Exchange (ETDEWEB)

    1977-06-01

    ERDA has requested United Engineers and Constructors (UE and C) to evaluate the design of the Canadian natural uranium fueled, heavy water moderated (CANDU) nuclear reactor power plant to assess its conformance with the licensing criteria and guidelines of the U.S. Nuclear Regulatory Commission (USNRC) for light water reactors. This assessment was used to identify cost significant items of nonconformance and to provide a basis for developing a detailed cost estimate for a 1140 MWe, 3-loop Pressurized Heavy Water Reactor (PHWR) located at the Middletown, USA Site.

  15. Pressure in a tank due to water-ice phase transformation

    Science.gov (United States)

    Lexcellent, C.; Vigoureux, D.; Vigoureux, J.-M.

    2017-11-01

    Our aim is to show the surprising force of hydrogen bonds in ice. When a tank completely filled with water is cooled, ice formation can generate a pressure which can cause its breaking. This phenomenon is due to the fact that water has a higher density in its liquid phase than in its solid state. Such a breaking is all the more surprising in that hydrogen bonds between water molecules are known as being weak chemical bonds. We show here that in the case of a total phase change, even the best steels or alloys could not prevent its breakage.

  16. Water Flow Testing and Unsteady Pressure Analysis of a Two-Bladed Liquid Oxidizer Pump Inducer

    Science.gov (United States)

    Schwarz, Jordan B.; Mulder, Andrew; Zoladz, Thomas

    2011-01-01

    The unsteady fluid dynamic performance of a cavitating two-bladed oxidizer turbopump inducer was characterized through sub-scale water flow testing. While testing a novel inlet duct design that included a cavitation suppression groove, unusual high-frequency pressure oscillations were observed. With potential implications for inducer blade loads, these high-frequency components were analyzed extensively in order to understand their origins and impacts to blade loading. Water flow testing provides a technique to determine pump performance without the costs and hazards associated with handling cryogenic propellants. Water has a similar density and Reynolds number to liquid oxygen. In a 70%-scale water flow test, the inducer-only pump performance was evaluated. Over a range of flow rates, the pump inlet pressure was gradually reduced, causing the flow to cavitate near the pump inducer. A nominal, smooth inducer inlet was tested, followed by an inlet duct with a circumferential groove designed to suppress cavitation. A subsequent 52%-scale water flow test in another facility evaluated the combined inducer-impeller pump performance. With the nominal inlet design, the inducer showed traditional cavitation and surge characteristics. Significant bearing loads were created by large side loads on the inducer during synchronous cavitation. The grooved inlet successfully mitigated these loads by greatly reducing synchronous cavitation, however high-frequency pressure oscillations were observed over a range of frequencies. Analytical signal processing techniques showed these oscillations to be created by a rotating, multi-celled train of pressure pulses, and subsequent CFD analysis suggested that such pulses could be created by the interaction of rotating inducer blades with fluid trapped in a cavitation suppression groove. Despite their relatively low amplitude, these high-frequency pressure oscillations posed a design concern due to their sensitivity to flow conditions and

  17. Integration of a Water Scrubbing Technique and Two-Stage Pressurized Anaerobic Digestion in One Process

    Directory of Open Access Journals (Sweden)

    Andreas Lemmer

    2015-03-01

    Full Text Available Two-stage pressurized anaerobic digestion is a promising technology. This technology integrates in one process biogas production with upgrading and pressure boosting for grid injection. To investigate whether the efficiency of this novel system could be further increased, a water scrubbing system was integrated into the methanogensis step. Therefore, six leach-bed reactors were used for hydrolysis/acidification and a 30-L pressurized anaerobic filter operated at 9 bar was adopted for acetogenesis/methanogenesis. The fermentation liquid of the pressurized anaerobic filter was circulated periodically via a flash tank, operating at atmospheric pressure. Due to the pressure drop, part of dissolved carbon dioxide was released from the liquid phase into the flash tank. The depressurized fermentation liquid was then recycled to the pressurized reactor. Three different flow rates (0 L·day−1, 20 L·day−1 and 40 L·day−1 were tested with three repetitions. As the daily recycled flashed liquid flow was increased from 0 to 40 L, six times as much as the daily feeding, the methane content in the biogas increased from 75 molar percent (mol% to 87 mol%. The pH value of the substrate in the methane reactor rose simultaneously from 6.5 to 6.7. The experimental data were verified by calculation.

  18. Acrylic resin water sorption under different pressure, temperature and time conditions

    Directory of Open Access Journals (Sweden)

    Rizzatti-Barbosa Célia Marisa

    2001-01-01

    Full Text Available The purpose of this work was to analyze water sorption by polymerized acrylic resins under different pressure, temperature and time treatments. A thermo-cured acrylic resin was used as the denture base (Classico Ltda. and ethylene glycol di-methacrylate as a cross-linking agent, with processing carried out in a water bath at 73 °C for nine hours. Forty-five samples were prepared following the criteria and dimensions of specification # 12 of the American Dental Association (ADA, using a matrix in the shape of a stainless steel disc with 50 ± 1 mm diameter and 0.5 ± 0.05 mm thickness. The control group samples were stored in distilled water for 30 days, while groups GII to GIX were placed in a polymerization device with adjustable pressure, time and temperature. An analysis of the variance of the results revealed the influence of different factors on water sorption only, with significant factors being temperature, time, pressure and the interaction between time and temperature. Other interactions exerted no significant influence on water sorption. Neither additional treatments nor the control group (GI showed any significant difference in comparison to the averages of other treatments.

  19. Robust aqua material. A pressure-resistant self-assembled membrane for water purification

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Erez; Weissman, Haim; Rybtchinski, Boris [Department of Organic Chemistry, Weizmann Institute of Science, 234 Herzl Street, Rehovot, 7610001 (Israel); Shimoni, Eyal; Kaplan-Ashiri, Ifat [Department of Chemical Research Support, Weizmann Institute of Science, 234 Herzl Street, Rehovot, 7610001 (Israel); Werle, Kai; Wohlleben, Wendel [Department of Material Physics, Materials and Systems Research, BASF SE, 67056, Ludwigshafen (Germany)

    2017-02-13

    ''Aqua materials'' that contain water as their major component and are as robust as conventional plastics are highly desirable. Yet, the ability of such systems to withstand harsh conditions, for example, high pressures typical of industrial applications has not been demonstrated. We show that a hydrogel-like membrane self-assembled from an aromatic amphiphile and colloidal Nafion is capable of purifying water from organic molecules, including pharmaceuticals, and heavy metals in a very wide range of concentrations. Remarkably, the membrane can sustain high pressures, retaining its function. The robustness and functionality of the water-based self-assembled array advances the idea that aqua materials can be very strong and suitable for demanding industrial applications. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Effect of supplementation of water-soluble vitamins on oxidative stress and blood pressure in prehypertensives.

    Science.gov (United States)

    Talikoti, Prashanth; Bobby, Zachariah; Hamide, Abdoul

    2015-01-01

    The objective of the study was to evaluate the effect of water-soluble vitamins on oxidative stress and blood pressure in prehypertensives. Sixty prehypertensives were recruited and randomized into 2 groups of 30 each. One group received water-soluble vitamins and the other placebo for 4 months. Further increase in blood pressure was not observed in the vitamin group which increased significantly in the placebo group at the end of 4 months. Malonedialdehyde and protein carbonylation were reduced during the course of treatment with vitamins whereas in the placebo group there was an increase in the level of malondialdehyde. In conclusion, supplementation of water-soluble vitamins in prehypertension reduces oxidative stress and its progression to hypertension.

  1. Weak interactions between water and clathrate-forming gases at low pressures

    Energy Technology Data Exchange (ETDEWEB)

    Thurmer, Konrad; Yuan, Chunqing; Kimmel, Gregory A.; Kay, Bruce D.; Smith, R. Scott

    2015-11-01

    Using scanning probe microscopy and temperature programed desorption we examined the interaction between water and two common clathrate-forming gases, methane and isobutane, at low temperature and low pressure. Water co-deposited with up to 10-1 mbar methane or 10-5 mbar isobutane at 140 K onto a Pt(111) substrate yielded pure crystalline ice, i.e., the exposure to up to ~107 gas molecules for each deposited water molecule did not have any detectable effect on the growing films. Exposing metastable, less than 2 molecular layers thick, water films to 10-5 mbar methane does not alter their morphology, suggesting that the presence of the Pt(111) surface is not a strong driver for hydrate formation. This weak water-gas interaction at low pressures is supported by our thermal desorption measurements from amorphous solid water and crystalline ice where 1 ML of methane desorbs near ~43 K and isobutane desorbs near ~100 K. Similar desorption temperatures were observed for desorption from amorphous solid water.

  2. Environmental response nanosilica for reducing the pressure of water injection in ultra-low permeability reservoirs

    Science.gov (United States)

    Liu, Peisong; Niu, Liyong; Li, Xiaohong; Zhang, Zhijun

    2017-12-01

    The super-hydrophobic silica nanoparticles are applied to alter the wettability of rock surface from water-wet to oil-wet. The aim of this is to reduce injection pressure so as to enhance water injection efficiency in low permeability reservoirs. Therefore, a new type of environmentally responsive nanosilica (denote as ERS) is modified with organic compound containing hydrophobic groups and "pinning" groups by covalent bond and then covered with a layer of hydrophilic organic compound by chemical adsorption to achieve excellent water dispersibility. Resultant ERS is homogeneously dispersed in water with a size of about 4-8 nm like a micro-emulsion system and can be easily injected into the macro or nano channels of ultra-low permeability reservoirs. The hydrophobic nanosilica core can be released from the aqueous delivery system owing to its strong dependence on the environmental variation from normal condition to injection wells (such as pH and salinity). Then the exposed silica nanoparticles form a thin layer on the surface of narrow pore throat, leading to the wettability from water-wet to oil-wet. More importantly, the two rock cores with different permeability were surface treated with ERS dispersion with a concentration of 2 g/L, exhibit great reduce of water injection pressure by 57.4 and 39.6%, respectively, which shows great potential for exploitation of crude oil from ultra-low permeability reservoirs during water flooding. [Figure not available: see fulltext.

  3. Surface Features Parameterization and Equivalent Roughness Height Estimation of a Real Subglacial Conduit in the Arctic

    Science.gov (United States)

    Chen, Y.; Liu, X.; Manko ff, K. D.; Gulley, J. D.

    2016-12-01

    The surfaces of subglacial conduits are very complex, coupling multi-scale roughness, large sinuosity, and cross-sectional variations together. Those features significantly affect the friction law and drainage efficiency inside the conduit by altering velocity and pressure distributions, thus posing considerable influences on the dynamic development of the conduit. Parameterizing the above surface features is a first step towards understanding their hydraulic influences. A Matlab package is developed to extract the roughness field, the conduit centerline, and associated area and curvature data from the conduit surface, acquired from 3D scanning. By using those data, the characteristic vertical and horizontal roughness scales are then estimated based on the structure functions. The centerline sinuosities, defined through three concepts, i.e., the traditional definition of a fluvial river, entropy-based sinuosity, and curvature-based sinuosity, are also calculated and compared. The cross-sectional area and equivalent circular diameter along the centerline are also calculated. Among those features, the roughness is especially important due to its pivotal role in determining the wall friction, and thus an estimation of the equivalent roughness height is of great importance. To achieve such a goal, the original conduit is firstly simplified into a straight smooth pipe with the same volume and centerline length, and the roughness field obtained above is then reconstructed into the simplified pipe. An OpenFOAM-based Large-eddy-simulation (LES) is then performed based on the reconstructed pipe. Considering that the Reynolds number is of the order 106, and the relative roughness is larger than 5% for 60% of the conduit, we test the validity of the resistance law for completely rough pipe. The friction factor is calculated based on the pressure drop and mean velocity in the simulation. Working together, the equivalent roughness height can be calculated. However, whether the

  4. The magnesium sulfate-water system at pressures to 4 kilobars

    Science.gov (United States)

    Hogenboom, D. L.; Kargel, Jeffrey S.; Ganasan, J. P.; Lewis, J. S.

    1991-01-01

    Hydrated magnesium sulfate constitutes up to 1/6 of the mass of carbonaceous chondrites, and probably is important in many icy asteroids and satellites. It occurs naturally in meteorites mostly as epsomite. MgSO4, considered anhydrously, comprises nearly 3/4 of the highly soluble fraction of C1 chondrites. Thus, MgSO4 is probably an important solute in cryovolcanic brines erupted on certain icy objects in the outer solar system. While the physiochemical properties of the water-magnesium sulfate system are well known at low pressures, planetological applications of these data are hindered by a dearth of useful published data at elevated pressures. Accordingly, solid-liquid phase equilibria was recently explored in this chemical system at pressures extending to about 4 kilobars. The water magnesium sulfate system in the region of the eutectic exhibits qualitatively constant behavior between pressures of 1 atm and 2 kbar. The eutectic melting curve closely follows that for water ice, with a freezing point depression of about 4 K at 1 atm decreasing to around 3.3 K at 2 kbars. The eutectic shifts from 17 pct. MgSO4 at 1 atm to about 15.3 pct at 2 kbars. Above 2 kbars, the eutectic melting curve again tends to follow ice.

  5. ANNEALING OF POLYCRYSTALLINE THIN FILM SILICON SOLAR CELLS IN WATER VAPOUR AT SUB-ATMOSPHERIC PRESSURES

    Directory of Open Access Journals (Sweden)

    Peter Pikna

    2014-10-01

    Full Text Available Thin film polycrystalline silicon (poly-Si solar cells were annealed in water vapour at pressures below atmospheric pressure. PN junction of the sample was contacted by measuring probes directly in the pressure chamber filled with steam during passivation. Suns-VOC method and a Lock-in detector were used to monitor an effect of water vapour to VOC of the solar cell during whole passivation process (in-situ. Tested temperature of the sample (55°C – 110°C was constant during the procedure. Open-circuit voltage of a solar cell at these temperatures is lower than at room temperature. Nevertheless, voltage response of the solar cell to the light flash used during Suns-VOC measurements was good observable. Temperature dependences for multicrystalline wafer-based and polycrystalline thin film solar cells were measured and compared. While no significant improvement of thin film poly-Si solar cell parameters by annealing in water vapour at under-atmospheric pressures was observed up to now, in-situ observation proved required sensitivity to changing VOC at elevated temperatures during the process.

  6. Removal of barometric pressure effects and earth tides from observed water levels.

    Science.gov (United States)

    Toll, Nathanial J; Rasmussen, Todd C

    2007-01-01

    The effects of barometric pressure and earth tide changes are often observed in ground water level measurements. These disturbances can make aquifer test interpretation difficult by masking the small changes induced by aquifer testing at late times and great distances. A computer utility is now available that automatically removes the effects of barometric pressure and earth tides from water level observations using regression deconvolution. This procedure has been shown to remove more noise then traditional constant barometric efficiency techniques in both confined and unconfined aquifers. Instead of a single, instantaneous barometric efficiency, the procedure more correctly accounts for the lagged responses caused by barometric pressure and earth tide changes. Simultaneous measurements of water levels (or total heads) and nearby barometric pressures are required. As an additional option, the effects of earth tides can also be removed using theoretical earth tides. The program is demonstrated for two data sets collected at the Waste Isolation Pilot Plant, Carlsbad, New Mexico. The program is available free by request at http://www.hydrology.uga.edu/tools.html.

  7. Real-time adjustment of pressure to demand in water distribution systems: Parameter-less P-controller algorithm

    CSIR Research Space (South Africa)

    Page, Philip R

    2016-08-01

    Full Text Available Remote real-time control is currently the most advanced form of pressure management. Here the parameters describing pressure control valves (or pumps) are changed in real-time in such a way to provide the most optimal pressure in the water...

  8. 46 CFR 52.01-110 - Water-level indicators, water columns, gauge-glass connections, gauge cocks, and pressure gauges...

    Science.gov (United States)

    2010-10-01

    ... connections, gauge cocks, and pressure gauges (modifies PG-60). 52.01-110 Section 52.01-110 Shipping COAST... § 52.01-110 Water-level indicators, water columns, gauge-glass connections, gauge cocks, and pressure.... (Modifies PG-60.3.) Gage glasses and gage cocks shall be connected directly to the head or shell of a boiler...

  9. Risks assessment of water pollution by pesticides at local scale (PESTEAUX project): study of polluting pressure.

    Science.gov (United States)

    Noel, Stéphanie; Billo Bah, Boubacar

    2009-01-01

    Pollution of water resources (surface waters and ground waters) by pesticide uses is one of the key point of the European policy with the implementation of the Water Frame Work Directive (2000/60/EC) and the thematic Strategy on the Sustainable use of pesticides. According to this legislation, the Member States must initiate measures to limit environmental and toxicological effects caused by pesticide uses. The Agricultural Research Centre of Wallonia (CRA-W) emphasized the need of a tool for spatial risk analysis and develOPs it within the framework of PESTEAUX project. The originality of the approach proposed by the CRA-W is to generate maps to identify the risk of pollution at locale scale (agricultural parcel). The risk will be assessed according to the study of different factors, grouped under 3 data's layers: polluting pressure, vulnerability of the physical environment (soil) and meteorological data. This approach is directly based on the risk's definition which takes into account the polluting pressure, linked to the human activities, and the vulnerability of the soil, defined by factors of physical environment which characterize the water flow in the parcel. Moreover, meteorological data influence the intensity and likelihood flow of water, and indirectly pesticide by leaching or runoff. The PESTEAUX's approach to study the pollution is based on the model "source-vector-target". The source is the polluting pressure, in other words, the pesticides which could reach the targets. The main vector is the water which vehicles the pesticide on and trough the soil until the target which are the surface waters or ground waters. In this paper we introduce the factors contributing to the polluting pressure. These factors are linking to the human activities and more precisely, to the pesticide uses. The factors considered have an influence on pesticide's transport by water (in its solid state or in dissolved state by leaching, run-off, or erosion) but also on a set of

  10. Tissue fusion bursting pressure and the role of tissue water content

    Science.gov (United States)

    Cezo, James; Kramer, Eric; Taylor, Kenneth; Ferguson, Virginia; Rentschler, Mark

    2013-02-01

    Tissue fusion is a complex, poorly understood process which bonds collagenous tissues together using heat and pressure. The goal of this study is to elucidate the role of hydration in bond efficacy. Hydration of porcine splenic arteries (n=30) was varied by pre-fusion treatments: 24-48 hour immersion in isotonic, hypotonic, or hypertonic baths. Treated arteries were fused in several locations using Conmed's Altrus thermal fusion device and the bursting pressure was then measured for each fused segment. Artery sections were then weighed before and after lyophilization, to quantify water content. Histology (HE, EVG staining) enabled visualization of the bonding interface. Bursting pressure was significantly greater (p=4.17 E-ll) for the hypotonic group (607.6 +/- 83.2mmHg), while no significant difference existed between the isotonic (332.6 +/- 44.7mmHg) and hypertonic (348.7 +/- 44.0mmHg) treatment groups. Total water content varied (p=8.80 E-24) from low water content in the hypertonic samples (72.5% weight +/- 0.9), to high water content in the hypotonic samples (83.1% weight +/- 1.9), while the isotonic samples contained 78.8% weight +/- 1.1. Strength differences between the treated vessels imply that bound water driven from the tissue during fusion may reveal available collagen crosslinking sites to facilitate bond formation during the fusion process. Thus when the tissue contains greater bound water volumes, more crosslinking sites may become available during fusion, leading to a stronger bond. This study provides an important step towards understanding the chemistry underlying tissue fusion and the mechanics of tissue fusion as a function of bound water within the tissue.

  11. The Wilkes subglacial basin eastern margin electrical conductivity anomaly

    Science.gov (United States)

    Rizzello, Daniele; Armadillo, Egidio; Ferraccioli, Fausto; Caneva, Giorgio

    2014-05-01

    We have analyzed the deep conductivity structure at the transition between the Transantarctic Mountains (TAM) and the eastern margin of the WSB in NVL, by means of the GDS (Geomagnetic Deep Sounding) technique, in order to constrain the geodynamical interpretation of this antarctic sector. The TAM form the uplifted flank of the Mesozoic and Cenozoic West Antarctic Rift System. Structure of the TAM rift flank has been partially investigated with different geophysical approaches.The Wilkes Subglacial Basin is a broad depression over 400 km wide at the George V Coast and 1200 km long. Geology, lithospheric structure and tectonics of the Basin are only partially known because the Basin is buried beneath the East Antarctic Ice Sheet and is located in a remote region which makes geophysical exploration logistically challenging. Different authors have proposed contrasting hypothesis regarding the origin of the WSB: it could represent a region of rifted continental crust, or it may have a flexural origin or might represent an "extended terrane". Recently aerogeophysical investigations have demonstrated a strong structural control on the margin. Magnetovariational studies carried out at high geomagnetic latitudes are often hampered by source effects, mainly due to the closeness to the Polar Electrojet currents systems (PEJ). Its presence, in fact, makes the uniform magnetic field assumption, on which the magnetovariational methods are based on, often invalid, which outcome is a bias in the GDS transfer functions and to compromise the reliability of the inverted models. Data from the aforementioned campaigns have been then processed under the ISEE project (Ice Sheet Electromagnetic Experiment), aimed at evaluate and mitigate the bias effect of the PEJ on geomagnetic an magnetotelluric transfer functions at high geomagnetic latitudes, by means of suitable processing algorithms, developed upon a statistical analysis study on PEJ effects (Rizzello et al. 2013). Recent results

  12. Pressure impact of autoclave treatment on water sorption and pectin composition of flax cellulosic-fibres.

    Science.gov (United States)

    Alix, S; Colasse, L; Morvan, C; Lebrun, L; Marais, S

    2014-02-15

    The tensile properties of flax fibres might permit them to be used in composites as reinforcement in organic resin, as long as their mechanical properties are reproducible and their water sorption are reduced. In this study, to minimise the variability of mechanical properties, several samples of flax fibres were blended as a non-woven fabric. In order to reduce the water absorption of this non-woven technical fibres, an autoclave treatment was performed which was expected to remove the pectins and then to reduce the water sorption on their negative charges. The impact of autoclave pressure (0.5, 1 and 2 bars) on water sorption was investigated by using a gravimetric static equilibrium method. The Park model based on the three sorption modes: Langmuir, Henry's law and clustering, was successfully used to simulate the experimental sorption data. The lowest pressure treatments impacted only the Langmuir contribution while the 2 bar autoclave-treatment positively impacted the water resistance in the core of fibres by reducing Henry's absorption rate. This was shown to be related to the chemical modifications at the surface and in the core of fibres. A schematic model is presented relating the water sorption and the pectic composition of the fabric. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Attenuation of wave-induced groundwater pressure in shallow water. Part 2. Theory

    Directory of Open Access Journals (Sweden)

    Stanisław R. Massel

    2005-09-01

    Full Text Available In this Part 2 of the paper (Part 1 was published by Massel et al. 2004 an exact close-form solution for the pore-water pressure component and velocity circulation pattern induced by surface waves is developed. This comprehensive theoretical model, based on Biot's theory, takes into account soil deformations, volume change and pore-water flow. The calculations indicate that for the stiffness ratio G/E'w ≥ 100, the vertical distribution of the pore pressure becomes very close to the Moshagen & Tørum (1975 approach, when the soil is rigid and the fluid is incompressible.     The theoretical results of the paper have been compared with the experimental data collected during the laboratory experiment in the Large Wave Channel in Hannover (see Massel et al. 2004 and showed very good agreement. The apparent bulk modulus of pore water was not determined in the experiment but was estimated from the best fit of the experimental pore-water pressure with the theoretical one. In the paper only a horizontal bottom is considered and the case of an undulating bottom will be dealt with in another paper.

  14. Molecular dynamics of equilibrium and pressure-driven transport properties of water through LTA-type zeolites.

    Science.gov (United States)

    Turgman-Cohen, Salomon; Araque, Juan C; Hoek, Eric M V; Escobedo, Fernando A

    2013-10-08

    We consider an atomistic model to investigate the flux of water through thin Linde type A (LTA) zeolite membranes with differing surface chemistries. Using molecular dynamics, we have studied the flow of water under hydrostatic pressure through a fully hydrated LTA zeolite film (~2.5 nm thick) capped with hydrophilic and hydrophobic moieties. Pressure drops in the 50-400 MPa range were applied across the membrane, and the flux of water was monitored for at least 15 ns of simulation time. For hydrophilic membranes, water molecules adsorb at the zeolite surface, creating a highly structured fluid layer. For hydrophobic membranes, a depletion of water molecules occurs near the water/zeolite interface. For both types of membranes, the water structure is independent of the pressure drop established in the system and the flux through the membranes is lower than that observed for the bulk zeolitic material; the latter allows an estimation of surface barrier effects to pressure-driven water transport. Mechanistically, it is observed that (i) bottlenecks form at the windows of the zeolite structure, preventing the free flow of water through the porous membrane, (ii) water molecules do not move through a cage in a single-file fashion but rather exhibit a broad range of residence times and pronounced mixing, and (iii) a periodic buildup of a pressure difference between inlet and outlet cages takes place which leads to the preferential flow of water molecules toward the low-pressure cages.

  15. Molecular Dynamics of Equilibrium and Pressure-Driven Transport Properties of Water through LTA-Type Zeolites

    KAUST Repository

    Turgman-Cohen, Salomon

    2013-10-08

    We consider an atomistic model to investigate the flux of water through thin Linde type A (LTA) zeolite membranes with differing surface chemistries. Using molecular dynamics, we have studied the flow of water under hydrostatic pressure through a fully hydrated LTA zeolite film (∼2.5 nm thick) capped with hydrophilic and hydrophobic moieties. Pressure drops in the 50-400 MPa range were applied across the membrane, and the flux of water was monitored for at least 15 ns of simulation time. For hydrophilic membranes, water molecules adsorb at the zeolite surface, creating a highly structured fluid layer. For hydrophobic membranes, a depletion of water molecules occurs near the water/zeolite interface. For both types of membranes, the water structure is independent of the pressure drop established in the system and the flux through the membranes is lower than that observed for the bulk zeolitic material; the latter allows an estimation of surface barrier effects to pressure-driven water transport. Mechanistically, it is observed that (i) bottlenecks form at the windows of the zeolite structure, preventing the free flow of water through the porous membrane, (ii) water molecules do not move through a cage in a single-file fashion but rather exhibit a broad range of residence times and pronounced mixing, and (iii) a periodic buildup of a pressure difference between inlet and outlet cages takes place which leads to the preferential flow of water molecules toward the low-pressure cages. © 2013 American Chemical Society.

  16. Global Catalogue of the Martian Valley Networks: Evidences for Fluvial, Sapping and Subglacial Processes on Early Mars

    Science.gov (United States)

    Grau Galofre, A.; Jellinek, A. M.

    2017-10-01

    We use erosion models and statistical morphometry schemes to show quantitative evidence for fluvial, glacial, groundwater sapping and subglacial erosion on the Noachian highlands, to then build a global map of valley network origin and distribution.

  17. Impact of climate change and anthropogenic pressure on the water resources of India: challenges in management

    Science.gov (United States)

    Shadananan Nair, K.

    2016-10-01

    Freshwater resources of India are getting fast degraded and depleted from the changing climate and pressure of fast rising population. Changing intensity and seasonality of rainfall affect quantity and quality of water. Most of the rivers are polluted far above safety limits from the untreated domestic, industrial and agricultural effluents. Changes in the intensity, frequency and tracks of storms salinate coastal aquifers. Aquifers are also under the threat from rising sea level. Groundwater in urban limits and industrial zones are far beyond safety limits. Large-scale destruction of wetlands for industries and residential complexes has affected the quality of surface and groundwater resources in most parts of India. Measures to maintain food security and the new developments schemes such as river linking will further deteriorate the water resources. Falling water availability leads to serious health issues and various socio-economic issues. India needs urgent and appropriate adaptation strategies in the water sector.

  18. Impact of climate change and anthropogenic pressure on the water resources of India: challenges in management

    Directory of Open Access Journals (Sweden)

    K. Shadananan Nair

    2016-10-01

    Full Text Available Freshwater resources of India are getting fast degraded and depleted from the changing climate and pressure of fast rising population. Changing intensity and seasonality of rainfall affect quantity and quality of water. Most of the rivers are polluted far above safety limits from the untreated domestic, industrial and agricultural effluents. Changes in the intensity, frequency and tracks of storms salinate coastal aquifers. Aquifers are also under the threat from rising sea level. Groundwater in urban limits and industrial zones are far beyond safety limits. Large-scale destruction of wetlands for industries and residential complexes has affected the quality of surface and groundwater resources in most parts of India. Measures to maintain food security and the new developments schemes such as river linking will further deteriorate the water resources. Falling water availability leads to serious health issues and various socio-economic issues. India needs urgent and appropriate adaptation strategies in the water sector.

  19. Interfacing systems LOCA (loss-of-coolant accidents): Pressurized water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Bozoki, G.; Kohut, P.; Fitzpatrick, R.

    1989-02-01

    This report summarizes a study performed by Brookhaven National Laboratory for the Office of Nuclear Regulatory Research, Reactor and Plant Safety Issues Branch, Division of Reactor and Plant Systems, US Nuclear Regulatory Commission. This study was requested by the NRC in order to provide a technical basis for the resolution of Generic Issue 105 ''Interfacing LOCA at LWRs.'' This report deals with pressurized water reactors (PWRs). A parallel report was also accomplished for boiling water reactors. This study focuses on three representative PWRs and extrapolates the plant-specific findings for their generic applicability. In addition, a generic analysis was performed to investigate the cost-benefit aspects of imposing a testing program that would require some minimum level of leak testing of the pressure isolation valves on plants that presently have no such requirements. 28 refs., 31 figs., 64 tabs.

  20. TRAC-PF1: an advanced best-estimate computer program for pressurized water reactor analysis

    Energy Technology Data Exchange (ETDEWEB)

    Liles, D.R.; Mahaffy, J.H.

    1984-02-01

    The Transient Reactor Analysis Code (TRAC) is being developed at the Los Alamos National Laboratory to provide advanced best-estimate predictions of postulated accidents in light water reactors. The TRAC-PF1 program provides this capability for pressurized water reactors and for many thermal-hydraulic experimental facilities. The code features either a one-dimensional or a three-dimensional treatment of the pressure vessel and its associated internals; a two-phase, two-fluid nonequilibrium hydrodynamics model with a noncondensable gas field; flow-regime-dependent constitutive equation treatment; optional reflood tracking capability for both bottom flood and falling-film quench fronts; and consistent treatment of entire accident sequences including the generation of consistent initial conditions. This report describes the thermal-hydraulic models and the numerical solution methods used in the code. Detailed programming and user information also are provided.

  1. Welding residual stress distributions for dissimilar metal nozzle butt welds in pressurized water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Soo; Kim, Ju Hee; Bae, Hong Yeol; OH, Chang Young; Kim, Yun Jae [Korea Univ., Seoul (Korea, Republic of); Lee, Kyungsoo [Korea Electric Power Research Institute, Daejeon (Korea, Republic of); Song, Tae Kwang [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2012-02-15

    In pressurized water nuclear reactors, dissimilar metal welds are susceptible to primary water stress corrosion cracking. To access this problem, accurate estimation of welding residual stresses is important. This paper provides general welding residual stress profiles in dissimilar metal nozzle butt welds using finite element analysis. By introducing a simplified shape for dissimilar metal nozzle butt welds, changes in the welding residual stress distribution can be seen using a geometry variable. Based on the results, a welding residual stress profile for dissimilar metal nozzle butt welds is proposed that modifies the existing welding residual stress profile for austenitic pipe butt welds.

  2. Pressure induced by the interaction of water waves with nearly equal frequencies and nearly opposite directions

    Directory of Open Access Journals (Sweden)

    L. Pellet

    2017-05-01

    Full Text Available We present second-order expressions for the free-surface elevation, velocity potential and pressure resulting from the interaction of surface waves in water of arbitrary depth. When the surface waves have nearly equal frequencies and nearly opposite directions, a second-order pressure can be felt all the way to the sea bottom. There are at least two areas of applications: reflective structures and microseisms. Microseisms generated by water waves in the ocean are small vibrations of the ground resulting from pressure oscillations associated with the coupling of ocean surface gravity waves and the sea floor. They are recorded on land-based seismic stations throughout the world and they are divided into primary and secondary types, as a function of spectral content. Secondary microseisms are generated by the interaction of surface waves with nearly equal frequencies and nearly opposite directions. The efficiency of microseism generation thus depends in part on ocean wave frequency and direction. Based on the second-order expressions for the dynamic pressure, a simple theoretical analysis that quantifies the degree of nearness in amplitude, frequency, and incidence angle, which must be reached to observe the phenomenon, is presented.

  3. The flooding incident at the Aagesta pressurized heavy water nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Dahlgren, C. [Royal Inst. of Tech., Stockholm (Sweden). Div. of Nuclear Power Safety

    1996-03-01

    This work is an independent investigation of the consequences of the flooding incident at the Aagesta HPWR, Stockholm in May 1969. The basis for the report is an incident in which, due to short circuits in the wiring because of flooding water, the ECCS is momentarily subjected to a pressure much higher than designed for. The hypothetical scenario analyzed here is the case in which the ECCS breaks due to the high pressure. As a consequence of the break, the pressure and the water level in the reactor vessel decrease. The report is divided into three parts; First the Aagesta HPWR is described as well as the chronology of the incident, an analysis of the effects of a hypothetical break in the ECCS is then developed. The second part is a scoping analysis of the incident, modeling the pressure decrease and mass flow rate out of the break. The heat-up of the core, and the core degradation was modeled as well. The third part is formed by a RELAP5/MOD3.1 modeling of the Aagesta HPWR. 18 refs.

  4. Borehole water level response to barometric pressure as an indicator of aquifer vulnerability

    OpenAIRE

    Hussein, MEA; Odling, NE; Clark, RA

    2013-01-01

    The response of borehole water levels to barometric pressure changes in semiconfined aquifers can be used to determine barometric response functions from which aquifer and confining layer properties can be obtained. Following earlier work on barometric response functions and aquifer confinement, we explore the barometric response function as a tool to improve the assessment of groundwater vulnerability in semiconfined aquifers, illustrated through records from two contrasting boreholes in the...

  5. REFERENCE ON THERMOPHYSICAL PROPERTIES: DENSITY AND VISCOSITY OF WATER FOR ATMOSPHERIC PRESSURE

    Directory of Open Access Journals (Sweden)

    Elin Yusibani

    2016-09-01

    Full Text Available A reference on thermophysical properties, density and viscosity, for water at atmospheric pressure has been developed in MS Excel (as a macros. Patterson’s density equations and Kestin’s viscosity equations have been chosen as a basic equation in the VBA programming as a user-defined function. These results have been compared with REFPROF as a wellknow standart reference

  6. Optimal pressure sensor placement in water distribution networks minimizing leak location uncertainty

    OpenAIRE

    Nejjari, Fatiha; Sarrate, Ramon; Blesa, Joaquim

    2015-01-01

    In this paper an optimal sensor placement strategy based on pressure sensitivity matrix analysis and an exhaustive search strategy that maximizes some diagnosis specifications for a water distribution network is presented. An average worst leak expansion distance as a new leak location performance measure has been proposed. This metric is later used to assess the leak location uncertainty provided by a sensor configuration. The method is combined with a clustering technique in order to reduce...

  7. Water ingestion affects orthostatic challenge-induced blood pressure and heart rate responses in young healthy subjects: gender implications.

    Science.gov (United States)

    Olatunji, L A; Aaron, A O; Micheal, O S; Oyeyipo, I P

    2011-11-23

    Evidence exists that women have lower orthostatic tolerance than men during quiescent standing. Water ingestion has been demonstrated to improve orthostatic tolerance in patients with severe autonomic dysfunction. We therefore sought to test the hypothesis that water ingestion would improve orthostatic tolerance in healthy young women more than in aged-matched men. Thirty seven (22 men and 15 women) healthy subjects aged 22.5± 1.7 and 21.5±1.4 (means±SD) respectively, ingested 50ml (control) and 500ml of water 40min before orthostatic challenge on two separate days of appointment in a randomized controlled, cross-over design. Seated and standing blood pressure and heart rate were determined. Orthostatic tolerance was assessed as the time to presyncope during standing. Ingesting 500ml of water significantly improves orthostatic tolerance by 22% (32.0 ± 5.2 vs 26.2 ± 2.4min; pwater, seated systolic blood pressure, diastolic blood pressure, pulse pressure and mean arterial pressure rose significantly in men while only systolic blood pressure and pulse pressure rose significantly in women. However ingesting 500ml of water did not have significant effect on seated heart rate in both men and women. Ingestion of 500ml of water significantly attenuated both the orthostatic challenge-induced increased heart rate and decreased pulse pressure responses especially in women. Diastolic blood pressure tended to be positively correlated with orthostatic tolerance strongly in men than in women. Pulse pressure correlated positively while heart rate correlated negatively to orthostatic tolerance in women but not in men independent of other correlates. Water ingestion is associated with orthostatic tolerance strongly in women but weakly in men independent of other correlates. In conclusion, the findings in the present study demonstrated that water ingestion caused improvement strongly in young women than in young men. This improvement is associated with increased pulse pressure

  8. Evaluation of low degree polynomial kernel support vector machines for modelling Pore-water pressure responses

    Directory of Open Access Journals (Sweden)

    Babangida Nuraddeen Muhammad

    2016-01-01

    Full Text Available Pore-water pressure (PWP is influenced by climatic changes, especially rainfall. These changes may affect the stability of, particularly unsaturated slopes. Thus monitoring the changes in PWP resulting from climatic factors has become an important part of effective slope management. However, this monitoring requires field instrumentation program, which is resource and labour expensive. Recently, soft computing modelling has become an alternative. Low degree polynomial kernel support vector machine (SVM was evaluated in modelling the PWP changes. The developed model used pore-water pressure and rainfall data collected from an instrumented slope. Wrapper technique was used to select input features and k-fold cross validation was used to calibrate the model parameters. The developed model showed great promise in modelling the pore-water pressure changes. High correlation, with coefficient of determination of 0.9694 between the predicted and observed changes was obtained. The one degree polynomial SVM model yielded competitive result, and can be used to provide lead time records of PWP which can aid in better slope management.

  9. Acute combined pressure and temperature exposures on a shallow-water crustacean: novel insights into the stress response and high pressure neurological syndrome.

    Science.gov (United States)

    Morris, J P; Thatje, S; Ravaux, J; Shillito, B; Fernando, D; Hauton, C

    2015-03-01

    Little is known about the ecological and physiological processes governing depth distribution limits in species. Temperature and hydrostatic pressure are considered to be two dominant factors. Research has shown that some marine ectotherms are shifting their bathymetric distributions in response to rapid anthropogenic ocean surface warming. Shallow-water species unable to undergo latitudinal range shifts may depend on bathymetric range shifts to seek refuge from warming surface waters. As a first step in constraining the molecular basis of pressure tolerance in shallow water crustaceans, we examined differential gene expression in response to acute pressure and temperature exposures in juveniles of the shallow-water shrimp Palaemonetes varians. Significant increases in the transcription of genes coding for an NMDA receptor-regulated protein, an ADP ribosylation factor, β-actin, two heat shock protein 70 kDa isoforms (HSP70), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were found in response to elevated pressure. NMDA receptors have been implicated in pathways of excitotoxic damage to neurons and the onset of high pressure neurological syndrome (HPNS) in mammals. These data indicate that the sub-lethal effects of acute barotrauma are associated with transcriptional disturbances within the nervous tissue of crustaceans, and cellular macromolecular damage. Such transcriptional changes lead to the onset of symptoms similar to that described as HPNS in mammals, and may act as a limit to shallow water organisms' prolonged survival at depth. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Plasma-water interactions at atmospheric pressure in a dc microplasma

    Science.gov (United States)

    Patel, Jenish; Němcová, Lucie; Mitra, Somak; Graham, William; Maguire, Paul; Švrček, Vladimir; Mariotti, Davide

    2013-09-01

    Plasma-liquid interactions generate a variety of chemical species that are very useful for the treatment of many materials and that makes plasma-induced liquid chemistry (PiLC) very attractive for industrial applications. The understanding of plasma-induced chemistry with water can open up a vast range of plasma-activated chemistry in liquid with enormous potential for the synthesis of chemical compounds, nanomaterials synthesis and functionalization. However, this basic understanding of the chemistry occurring at the plasma-liquid interface is still poor. In the present study, different properties of water are analysed when processed by plasma at atmospheric-pressure with different conditions. In particular, pH, temperature and conductivity of water are measured against current and time of plasma processing. We also observed the formation of molecular oxygen (O2) and hydrogen peroxide (H2O2) for the same plasma conditions. The current of plasma processing was found to affect the water properties and the production of hydrogen peroxide in water. The relation between the number of electrons injected from plasma in water and the number of H2O2 molecules was established and based on these results a scenario of reactions channels activated by plasma-water interface is concluded.

  11. Hydrostatic pressure effect on PNIPAM cononsolvency in water-methanol solutions.

    Science.gov (United States)

    Pica, Andrea; Graziano, Giuseppe

    2017-12-01

    When methanol is added to water at room temperature and 1atm, poly (N-isopropylacrylamide), PNIPAM, undergoes a coil-to-globule collapse transition. This intriguing phenomenon is called cononsolvency. Spectroscopic measurements have shown that application of high hydrostatic pressure destroys PNIPAM cononsolvency in water-methanol solutions. We have developed a theoretical approach that identifies the decrease in solvent-excluded volume effect as the driving force of PNIPAM collapse on increasing the temperature. The same approach indicates that cononsolvency, at room temperature and P=1atm, is caused by the inability of PNIPAM to make all the attractive energetic interactions that it could be engaged in, due to competition between water and methanol molecules. The present analysis suggests that high hydrostatic pressure destroys cononsolvency because the coil state becomes more compact, and the quantity measuring PNIPAM-solvent attractions increases in magnitude due to the solution density increase, and the ability of small water molecules to substitute methanol molecules on PNIPAM surface. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Rapid Submarine Melting Driven by Subglacial Discharge, LeConte Glacier, Alaska

    Science.gov (United States)

    Motyka, R. J.; Dryer, W. P.; Amundson, J. M.; Truffer, M.; Fahnestock, M. A.

    2013-12-01

    Submarine melting impacts the stability of tidewater glaciers worldwide, but the connections between the ocean, a warming climate, and retreat of outlet glaciers are poorly known. Clearly warm seawater plays an important role, but the tremendous heat potential resident in oceans and fjords must first be brought into contact with outlet glacier termini in order to affect them. We show here that for many glaciers, the principal process driving high rates of submarine melting is subglacial discharge of freshwater. This buoyant discharge draws in warm seawater, entraining it in a turbulent upwelling convective flow along the submarine face that melts glacier ice. To capture the effect of changing subglacial discharge on submarine melting, we conducted four days of hydrographic transects during late summer 2012 at LeConte Glacier, Alaska. A major rainstorm allowed us to directly measure the influence of large changes in subglacial discharge. We found strong submarine melt rates that increased from 9.0×1.0 to 16.8×1.3 m/d (ice face equivalent frontal ablation) as subglacial discharge increased from 130 to 440 m^3/s over a four day period. This subglacial discharge drove influx of warm seawater (thermal forcing ~ 8° C) to the terminus with fluxes increasing from 1800 to 4000 m3/s. Our ice equivalent frontal ablation rates due to submarine melting are two to three times values found for Greenland glaciers, where thermal forcing is substantially lower (~ 1 - 4 °C) and termini are wider. Together, these studies confirm the importance of submarine melting at grounded glaciers. At LeConte, the total frontal ablation rate (calving flux plus submarine melting) is ~ 3.0 x10^6 m^3/d w.e., which far surpasses surface ablation. One-half to two-thirds of the frontal ablation during September 2012 can be attributed to submarine melting. A two-layer model driven by a buoyant plume of subglacial discharge has been previously invoked to describe the proglacial fjord circulation

  13. Prospects of obtaining samples of bottom sediments from subglacial lake Vostok

    Directory of Open Access Journals (Sweden)

    Н. И. Васильев

    2017-04-01

    Full Text Available The paper proves the timeliness of obtaining and examining bottom sediments from subglacial Lake Vostok. Predictive geological section of Lake Vostok and information value of bottom sediments have been examined. Severe requirements towards environmental security of lake examinations and sampling of bottom sediments rule out the use of conventional drilling technologies, as they would pollute the lake with injection liquid from the borehole. In order to carry out sampling of bottom sediments from the subglacial lake, it is proposed to use a dynamically balanced tool string, which enables rotary drilling without any external support on borehole walls to transmit counter torque.     A theoretical analysis has been carried out to assess the operation of the tool string, which is a two-mass oscillatory electromechanical system of reciprocating and rotating motion (RRM with two degrees of freedom.

  14. Pellet-Cladding Mechanical Interaction Failure Threshold for Reactivity Initiated Accidents for Pressurized Water Reactors and Boiling Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Carl E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Geelhood, Kenneth J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-06-01

    Pacific Northwest National Laboratory (PNNL) has been requested by the U.S. Nuclear Regulatory Commission to evaluate the reactivity initiated accident (RIA) tests that have recently been performed in the Nuclear Safety Research Reactor (NSRR) and CABRI (French research reactor) on uranium dioxide (UO2) and mixed uranium and plutonium dioxide (MOX) fuels, and to propose pellet-cladding mechanical interaction (PCMI) failure thresholds for RIA events. This report discusses how PNNL developed PCMI failure thresholds for RIA based on least squares (LSQ) regression fits to the RIA test data from cold-worked stress relief annealed (CWSRA) and recrystallized annealed (RXA) cladding alloys under pressurized water reactor (PWR) hot zero power (HZP) conditions and boiling water reactor (BWR) cold zero power (CZP) conditions.

  15. Geomorphological evidence of channelized subglacial meltwater drainage under the Scandinavian Ice Sheet

    Science.gov (United States)

    Adamczyk, Aleksander; Wysota, Wojciech; Sobiech, Marcin; Piotrowski, Jan A.

    2016-04-01

    The impact of subglacial meltwater erosion on shaping glacial landscapes is contentious and often difficult to constrain due to the lack of unequivocal diagnostic criteria. The same holds for the role of subglacial meltwater in glacier movement processes and sediment transport and deposition. Here we present new evidence of widespread channelized erosion under the southern, soft-bedded fringe of the last Scandinavian Ice Sheet (SIS) based on high-resolution terrain analysis with LiDAR imagery. We identify several tens of sites with "glacial curvilineation" landscapes first recognized by Lesemann et al. (2010, 2014) and considered as evidence of erosion by turbulent meltwater flows at the ice/bed interface. The "glacial curvilineation" landscapes mapped here consist of sets of parallel, winding ridges typically several metres high and up to several kilometres long occupying glacial overdeepenings and tunnel valleys. The ridges are aligned approximately perpendicular to the past ice sheet margins and they are composed of various deposits often pre-dating the last ice advance. We interpret them as erosional remnants of older landscapes dissected by high-energy subglacial meltwater flows. These findings suggest that the palaeoglaciological significance of meltwater drainage under the southern portion of SIS may have been grossly underestimated. References Lesemann, J.-E., Piotrowski, J.A. and Wysota, W., 2010. „Glacial curvilineations": New glacial landforms produced by longitudinal vortices in subglacial meltwater flows. Geomorphology 120, 153-161. Lesemann, J.-E., Piotrowski, J.A. and Wysota, W., 2014. Genesis of the "glacial curvilineation" landscape by meltwater processes under the former Scandinavian Ice Sheet, Poland. Sedimentary Geology 312, 1-18.

  16. Aerobic and Anaerobic Thiosulfate Oxidation by a Cold-Adapted, Subglacial Chemoautotroph

    Science.gov (United States)

    Harrold, Zoë R.; Skidmore, Mark L.; Hamilton, Trinity L.; Desch, Libby; Amada, Kirina; van Gelder, Will; Glover, Kevin; Roden, Eric E.

    2015-01-01

    Geochemical data indicate that protons released during pyrite (FeS2) oxidation are important drivers of mineral weathering in oxic and anoxic zones of many aquatic environments, including those beneath glaciers. Oxidation of FeS2 under oxic, circumneutral conditions proceeds through the metastable intermediate thiosulfate (S2O32−), which represents an electron donor capable of supporting microbial metabolism. Subglacial meltwaters sampled from Robertson Glacier (RG), Canada, over a seasonal melt cycle revealed concentrations of S2O32− that were typically below the limit of detection, despite the presence of available pyrite and concentrations of the FeS2 oxidation product sulfate (SO42−) several orders of magnitude higher than those of S2O32−. Here we report on the physiological and genomic characterization of the chemolithoautotrophic facultative anaerobe Thiobacillus sp. strain RG5 isolated from the subglacial environment at RG. The RG5 genome encodes genes involved with pathways for the complete oxidation of S2O32−, CO2 fixation, and aerobic and anaerobic respiration with nitrite or nitrate. Growth experiments indicated that the energy required to synthesize a cell under oxygen- or nitrate-reducing conditions with S2O32− as the electron donor was lower at 5.1°C than 14.4°C, indicating that this organism is cold adapted. RG sediment-associated transcripts of soxB, which encodes a component of the S2O32−-oxidizing complex, were closely affiliated with soxB from RG5. Collectively, these results suggest an active sulfur cycle in the subglacial environment at RG mediated in part by populations closely affiliated with RG5. The consumption of S2O32− by RG5-like populations may accelerate abiotic FeS2 oxidation, thereby enhancing mineral weathering in the subglacial environment. PMID:26712544

  17. Structure and Dynamics of Low-Density and High-Density Liquid Water at High Pressure.

    Science.gov (United States)

    Fanetti, Samuele; Lapini, Andrea; Pagliai, Marco; Citroni, Margherita; Di Donato, Mariangela; Scandolo, Sandro; Righini, Roberto; Bini, Roberto

    2014-01-02

    Liquid water has a primary role in ruling life on Earth in a wide temperature and pressure range as well as a plethora of chemical, physical, geological, and environmental processes. Nevertheless, a full understanding of its dynamical and structural properties is still lacking. Water molecules are associated through hydrogen bonds, with the resulting extended network characterized by a local tetrahedral arrangement. Two different local structures of the liquid, called low-density (LDW) and high-density (HDW) water, have been identified to potentially affect many different chemical, biological, and physical processes. By combining diamond anvil cell technology, ultrafast pump-probe infrared spectroscopy, and classical molecular dynamics simulations, we show that the liquid structure and orientational dynamics are intimately connected, identifying the P-T range of the LDW and HDW regimes. The latter are defined in terms of the speeding up of the orientational dynamics, caused by the increasing probability of breaking and reforming the hydrogen bonds.

  18. Feasibility study of underground energy storage using high-pressure, high-temperature water. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Dooley, J.L.; Frost, G.P.; Gore, L.A.; Hammond, R.P.; Rawson, D.L.; Ridgway, S.L.

    1977-01-01

    A technical, operational and economic feasibility study on the storage of energy as heated high pressure water in underground cavities that utilize the rock overburden for containment is presented. Handling peak load requirements of electric utility power networks is examined in some detail. The cavity is charged by heating water with surplus steaming capacity during periods of low power requirement. Later this hot water supplies steam to peaking turbines when high load demands must be met. This system can be applied to either new or existing power plants of nuclear or fossil fuel type. The round trip efficiency (into storage and back) is higher than any other system - over 90%. Capital costs are competitive and the environmental impact is quite benign. Detailed installation and design problems are studied and costs are estimated. The continental United States is examined for the most applicable geology. Formations favorable for these large cavities exist in widespread areas.

  19. Oxidation of uranium in low partial pressures of oxygen and water vapor at 100/sup 0/C

    Energy Technology Data Exchange (ETDEWEB)

    Weirick, L J

    1984-06-01

    Oxygen isotope studies indicate that a previously proposed theory describing the oxidation of uranium is incorrect. This theory had proposed that the uranium reacted directly with water vapor to form uranium dioxide and hydrogen and the hydrogen subsequently reacted with the free oxygen to form water. This study shows that oxygen reacts directly with uranium, the role of water vapor being to affect the uranium oxide structure which is formed. The reaction rate of uranium with water vapor in the absence of oxygen was linear and proportional to the water vapor pressure for water vapor pressures between 2 and 20 Torr. Hydrogen was produced by the reaction at a rate of almost two moles for every one mole of uranium dioxide formed. The oxide was identified as UO/sub 2/ /sub 0/. The reaction of uranium with water vapor in the presence of oxygen showed three separate regions of reaction response. In one region, at low oxygen pressure, the reaction was the same as with no oxygen, a second region at oxygen pressures between 0.05 and 1 Torr was a transition stage and in the third region, at oxygen pressures above 1 Torr, the reaction rate was linear and independent of both oxygen and water vapor pressure. The oxide formed was identified as nominally U/sub 4/O/sub 9/. Only a small amount of hydrogen was produced.

  20. Salinity of injection water and its impact on oil recovery absolute permeability, residual oil saturation, interfacial tension and capillary pressure

    Directory of Open Access Journals (Sweden)

    Mehdi Mohammad Salehi

    2017-06-01

    This paper presents laboratory investigation of the effect of salinity injection water on oil recovery, pressure drop, permeability, IFT and relative permeability in water flooding process. The experiments were conducted at the 80 °C and a net overburden pressure of 1700 psi using core sample. The results of this study have been shown oil recovery increases as the injected water salinity up to 200,000 ppm and appointment optimum salinity. This increase has been found to be supported by a decrease in the IFT. This effect caused a reduction in capillary pressure increasing the tendency to reduce the residual oil saturation.

  1. STUDY OF WATER HAMMERS IN THE FILLING OF THE SYSTEM OF PRESSURE COMPENSATION IN THE WATER-COOLED AND WATER-MODERATED POWER REACTORS

    Directory of Open Access Journals (Sweden)

    A. V. Korolyev

    2017-01-01

    Full Text Available The research presented in the article conforms to the severe accident that took place at the Three Mail Island nuclear power plant in the USA. The research is focused on improving the reliability of the pressure compensator that is an important equipment of the primary circuit. In order to simulate such a situation, the stand has been developed to simulate the design of the pressurizer of the PWR-440 reactor, in particular an elliptical shape of the upper lid which has a steam outlet pipe at the top of the construction that creates conditions for occurrence of such water hammers. For the experiments, an installation has been created that makes it possible to measure and record the water hammering that occur when the tanks are filled. Measurement of the amplitude of the water hammering was carried out by a specially developed piezoelectric sensor, and the registration – by a light-beam oscilloscope. The technique of carrying out the experiment is described and the results of an experimental study of the water hammers arising when the vessels are completely filled are presented. Quantitative data were obtained on the amplitudes of the hydraulic impacts depending on the rate of filling of the vessel and the diameter of the outlet, the maximum pressure of the hydraulic shock was 7–9 atm. Comparison of calculated and experimental data has been performed. The allowable discrepancy is explained by the calculated value of the system stiffness coefficient, which did not take into account the presence of welded seams in the tank that imparts the system with additional rigidity. The calculated relationships are obtained, that make it possible to estimate the amplitudes of the water hammers through the acceleration of the water level in front of the outlet from a vessel with an elliptical bottom. The possibility of a water hammer in the pressure compensator is demonstrated by experiment and by theoretical calculations. Based on the experimental data, a

  2. Effect of Leaf Water Potential on Internal Humidity and CO2 Dissolution: Reverse Transpiration and Improved Water Use Efficiency under Negative Pressure

    Science.gov (United States)

    Vesala, Timo; Sevanto, Sanna; Grönholm, Tiia; Salmon, Yann; Nikinmaa, Eero; Hari, Pertti; Hölttä, Teemu

    2017-01-01

    The pull of water from the soil to the leaves causes water in the transpiration stream to be under negative pressure decreasing the water potential below zero. The osmotic concentration also contributes to the decrease in leaf water potential but with much lesser extent. Thus, the surface tension force is approximately balanced by a force induced by negative water potential resulting in concavely curved water-air interfaces in leaves. The lowered water potential causes a reduction in the equilibrium water vapor pressure in internal (sub-stomatal/intercellular) cavities in relation to that over water with the potential of zero, i.e., over the flat surface. The curved surface causes a reduction also in the equilibrium vapor pressure of dissolved CO2, thus enhancing its physical solubility to water. Although the water vapor reduction is acknowledged by plant physiologists its consequences for water vapor exchange at low water potential values have received very little attention. Consequences of the enhanced CO2 solubility to a leaf water-carbon budget have not been considered at all before this study. We use theoretical calculations and modeling to show how the reduction in the vapor pressures affects transpiration and carbon assimilation rates. Our results indicate that the reduction in vapor pressures of water and CO2 could enhance plant water use efficiency up to about 10% at a leaf water potential of −2 MPa, and much more when water potential decreases further. The low water potential allows for a direct stomatal water vapor uptake from the ambient air even at sub-100% relative humidity values. This alone could explain the observed rates of foliar water uptake by e.g., the coastal redwood in the fog belt region of coastal California provided the stomata are sufficiently open. The omission of the reduction in the water vapor pressure causes a bias in the estimates of the stomatal conductance and leaf internal CO2 concentration based on leaf gas exchange

  3. COMPARISON OF VENTED AND ABSOLUTE PRESSURE TRANSDUCERS FOR WATER-LEVEL MONITORING IN HANFORD SITE CENTRAL PLATEAU WELLS

    Energy Technology Data Exchange (ETDEWEB)

    MCDONALD JP

    2011-09-08

    Automated water-level data collected using vented pressure transducers deployed in Hanford Site Central Plateau wells commonly display more variability than manual tape measurements in response to barometric pressure fluctuations. To explain this difference, it was hypothesized that vented pressure transducers installed in some wells are subject to barometric pressure effects that reduce water-level measurement accuracy. Vented pressure transducers use a vent tube, which is open to the atmosphere at land surface, to supply air pressure to the transducer housing for barometric compensation so the transducer measurements will represent only the water pressure. When using vented transducers, the assumption is made that the air pressure between land surface and the well bore is in equilibrium. By comparison, absolute pressure transducers directly measure the air pressure within the wellbore. Barometric compensation is achieved by subtracting the well bore air pressure measurement from the total pressure measured by a second transducer submerged in the water. Thus, no assumption of air pressure equilibrium is needed. In this study, water-level measurements were collected from the same Central Plateau wells using both vented and absolute pressure transducers to evaluate the different methods of barometric compensation. Manual tape measurements were also collected to evaluate the transducers. Measurements collected during this study demonstrated that the vented pressure transducers over-responded to barometric pressure fluctuations due to a pressure disequilibrium between the air within the wellbores and the atmosphere at land surface. The disequilibrium is thought to be caused by the relatively long time required for barometric pressure changes to equilibrate between land surface and the deep vadose zone and may be exacerbated by the restriction of air flow between the well bore and the atmosphere due to the presence of sample pump landing plates and well caps. The

  4. Potential Activity of Subglacial Microbiota Transported to Anoxic River Delta Sediments

    DEFF Research Database (Denmark)

    Cameron, Karen A.; Stibal, Marek; Olsen, Nikoline S.

    2017-01-01

    The Watson River drains a portion of the SW Greenland ice sheet, transporting microbial communities from subglacial environments to a delta at the head of Søndre Strømfjord. This study investigates the potential activity and community shifts of glacial microbiota deposited and buried under layers...... shift in predominant community members and a decline in diversity and cell abundance. These results highlight the need for further investigations into the fate of subglacial microbiota within downstream environments.......The Watson River drains a portion of the SW Greenland ice sheet, transporting microbial communities from subglacial environments to a delta at the head of Søndre Strømfjord. This study investigates the potential activity and community shifts of glacial microbiota deposited and buried under layers...... of sediments within the river delta. A long-term (12-month) incubation experiment was established using Watson River delta sediment under anaerobic conditions, with and without CO2/H2 enrichment. Within CO2/H2-amended incubations, sulphate depletion and a shift in the microbial community to a 52% predominance...

  5. Evaluation of an accident management strategy of emergency water injection using fire engines in a typical pressurized water reactor

    Directory of Open Access Journals (Sweden)

    Soo-Yong Park

    2015-10-01

    Full Text Available Following the Fukushima accident, a special safety inspection was conducted in Korea. The inspection results show that Korean nuclear power plants have no imminent risk for expected maximum potential earthquake or coastal flooding. However long- and short-term safety improvements do need to be implemented. One of the measures to increase the mitigation capability during a prolonged station blackout (SBO accident is installing injection flow paths to provide emergency cooling water of external sources using fire engines to the steam generators or reactor cooling systems. This paper illustrates an evaluation of the effectiveness of external cooling water injection strategies using fire trucks during a potential extended SBO accident in a 1,000 MWe pressurized water reactor. With regard to the effectiveness of external cooling water injection strategies using fire engines, the strategies are judged to be very feasible for a long-term SBO, but are not likely to be effective for a short-term SBO.

  6. Nonlinear Creep Model for Deep Rock under High Stress and High Pore Water Pressure Condition

    Directory of Open Access Journals (Sweden)

    Xie Yuanguang

    2016-05-01

    Full Text Available Conventional triaxial compression creep experiments for deep sandstone under high confining pressure and high pore water pressure were carried out, in order to predict the creep response of deep rock under these conditions. A nonlinear viscoelastic-plastic creep constitutive model was proposed based on the experimental results. The theory of component model was used as a basis for the formulation of this model. First, by using mathematical fitting and analogy, a new nonlinear viscous component was introduced based on the properties of the creep curves during the tertiary stage. Second, a timer component to judge whether the creep can get into the tertiary stage was presented. Finally, a nonlinear creep model was proposed. Results showed good agreement between theory curves from the nonlinear creep model and experimental data. This model can be applied to predict deep rock creep responses under high stress and high pore water pressure conditions. Hence, the obtained conclusions in this study are beneficial to deep rock engineering.

  7. Hydrothermal Treatment of Cellulose in Hot-Pressurized Water for the Production of Levulinic Acid

    Directory of Open Access Journals (Sweden)

    ASLI YUKSEL

    2016-12-01

    Full Text Available In this paper, hot-pressurized water, operating above boiling point and below critical point of water (374. 15 °C and 22.1 MPa, was used as a reaction medium for the decomposition of cellulose to high-value chemicals, such levulinic acid. Effects of reaction temperature, pressure, time, external oxidant type and concentration on the cellulose degradation and product distribution were evaluated. In order to compare the cellulose decomposition and yields of levulinic acid, experiments were performed with and without addition of oxidizing agents (H2SO4 and H2O2. Analysis of the liqueur was monitored by HPLC and GC-MS at different temperatures (150 - 280 °C, pressures (5-64 bars and reaction times (30 - 120 mins. Levulinic acid, 5-HMF and formic acid were detected as main products. 73% cellulose conversion was achieved with 38% levulinic acid yield when 125 mM of sulfuric acid was added to the reaction medium at 200 °C for 60 min reaction time.

  8. Existence for a global pressure formulation of water-gas flow in porous media

    Directory of Open Access Journals (Sweden)

    Brahim Amaziane

    2012-06-01

    Full Text Available We consider a model of water-gas flow in porous media with an incompressible water phase and a compressible gas phase. Such models appear in gas migration through engineered and geological barriers for a deep repository for radioactive waste. The main feature of this model is the introduction of a new global pressure and it is fully equivalent to the original equations. The system is written in a fractional flow formulation as a degenerate parabolic system with the global pressure and the saturation potential as the main unknowns. The major difficulties related to this model are in the nonlinear degenerate structure of the equations, as well as in the coupling in the system. Under some realistic assumptions on the data, including unbounded capillary pressure function and non-homogeneous boundary conditions, we prove the existence of weak solutions of the system. Furthermore, it is shown that the weak solution has certain desired properties, such as positivity of the saturation. The result is proved with the help of an appropriate regularization and a time discretization of the coupled system. We use suitable test functions to obtain a priori estimates and a compactness result in order to pass to the limit in nonlinear terms.

  9. Countercurrent Air-Water Flow in a Scale-Down Model of a Pressurizer Surge Line

    Directory of Open Access Journals (Sweden)

    Takashi Futatsugi

    2012-01-01

    Full Text Available Steam generated in a reactor core and water condensed in a pressurizer form a countercurrent flow in a surge line between a hot leg and the pressurizer during reflux cooling. Characteristics of countercurrent flow limitation (CCFL in a 1/10-scale model of the surge line were measured using air and water at atmospheric pressure and room temperature. The experimental results show that CCFL takes place at three different locations, that is, at the upper junction, in the surge line, and at the lower junction, and its characteristics are governed by the most dominating flow limitation among the three. Effects of inclination angle and elbows of the surge line on CCFL characteristics were also investigated experimentally. The effects of inclination angle on CCFL depend on the flow direction, that is, the effect is large for the nearly horizontal flow and small for the vertical flow at the upper junction. The presence of elbows increases the flow limitation in the surge line, whereas the flow limitations at the upper and lower junctions do not depend on the presence of elbows.

  10. Intraocular pressure dynamics with prostaglandin analogs: a clinical application of water-drinking test

    Directory of Open Access Journals (Sweden)

    Özyol P

    2016-07-01

    Full Text Available Pelin Özyol,1 Erhan Özyol,1 Ercan Baldemir2 1Ophthalmology Department, 2Biostatistics Department, Faculty of Medicine, Mugla Sitki Kocman University, Mugla, Turkey Aim: To evaluate the clinical applicability of the water-drinking test in treatment-naive primary open-angle glaucoma patients. Methods: Twenty newly diagnosed primary open-angle glaucoma patients and 20 healthy controls were enrolled in this prospective study. The water-drinking test was performed at baseline and 6 weeks and 3 months after prostaglandin analog treatment. Peak and fluctuation of intraocular pressure (IOP measurements obtained with the water-drinking test during follow-up were analyzed. Analysis of variance for repeated measures and paired and unpaired t-tests were used for statistical analysis. Results: The mean baseline IOP values in patients with primary open-angle glaucoma were 25.1±4.6 mmHg before prostaglandin analog treatment, 19.8±3.7 mmHg at week 6, and 17.9±2.2 mmHg at month 3 after treatment. The difference in mean baseline IOP of the water-drinking tests was statistically significant (P<0.001. At 6 weeks of prostaglandin analog treatment, two patients had high peak and fluctuation of IOP measurements despite a reduction in baseline IOP. After modifying treatment, patients had lower peak and fluctuation of IOP values at month 3 of the study. Conclusion: Peak and fluctuation of IOP in response to the water-drinking test were lower with prostaglandin analogs compared with before medication. The water-drinking test can represent an additional benefit in the management of glaucoma patients, especially by detecting higher peak and fluctuation of IOP values despite a reduced mean IOP. Therefore, it could be helpful as a supplementary method in monitoring IOP in the clinical practice. Keywords: glaucoma, intraocular pressure, water-drinking test, prostaglandin analog, intra­ocular pressure fluctuation

  11. Preliminary Study on the High Efficiency Supercritical Pressure Water-Cooled Reactor for Electricity Generation

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Yoon Yeong; Park, Jong Kyun; Cho, Bong Hyun and others

    2006-01-15

    This research has been performed to introduce a concept of supercritical pressure water cooled reactor(SCWR) in Korea The area of research includes core conceptual design, evaluation of candidate fuel, fluid systems conceptual design with mechanical consideration, preparation of safety analysis code, and construction of supercritical pressure heat transfer test facility, SPHINX, and preliminary test. As a result of the research, a set of tools for the reactor core design has been developed and the conceptual core design with solid moderator was proposed. The direct thermodynamic cycle has been studied to find a optimum design. The safety analysis code has also been adapted to supercritical pressure condition. A supercritical pressure CO2 heat transfer test facility has been constructed and preliminary test proved the facility works as expected. The result of this project will be good basis for the participation in the international collaboration under GIF GEN-IV program and next 5-year mid and long term nuclear research program of MOST. The heat transfer test loop, SPHINX, completed as a result of this project may be used for the power cycle study as well as further heat transfer study for the various geometries.

  12. An innovative technique for estimating water saturation from capillary pressure in clastic reservoirs

    Science.gov (United States)

    Adeoti, Lukumon; Ayolabi, Elijah Adebowale; James, Logan

    2017-11-01

    A major drawback of old resistivity tools is the poor vertical resolution and estimation of hydrocarbon when applying water saturation (Sw) from historical resistivity method. In this study, we have provided an alternative method called saturation height function to estimate hydrocarbon in some clastic reservoirs in the Niger Delta. The saturation height function was derived from pseudo capillary pressure curves generated using modern wells with complete log data. Our method was based on the determination of rock type from log derived porosity-permeability relationship, supported by volume of shale for its classification into different zones. Leverette-J functions were derived for each rock type. Our results show good correlation between Sw from resistivity based method and Sw from pseudo capillary pressure curves in wells with modern log data. The resistivity based model overestimates Sw in some wells while Sw from the pseudo capillary pressure curves validates and predicts more accurate Sw. In addition, the result of Sw from pseudo capillary pressure curves replaces that of resistivity based model in a well where the resistivity equipment failed. The plot of hydrocarbon pore volume (HCPV) from J-function against HCPV from Archie shows that wells with high HCPV have high sand qualities and vice versa. This was further used to predict the geometry of stratigraphic units. The model presented here freshly addresses the gap in the estimation of Sw and is applicable to reservoirs of similar rock type in other frontier basins worldwide.

  13. A numerical study on high-pressure water-spray cleaning for CSP reflectors

    Science.gov (United States)

    Anglani, Francesco; Barry, John; Dekkers, Willem

    2016-05-01

    Mirror cleaning for concentrated solar thermal (CST) systems is an important aspect of operation and maintenance (O&M), which affects solar field efficiency. The cleaning process involves soil removal by erosion, resulting from droplet impingement on the surface. Several studies have been conducted on dust accumulation and CSP plant reflectivity restoration, demonstrating that parameters such as nozzle diameter, jet impingement angle, interaxial distance between nozzles, standoff distance, water velocity, nozzle pressure and others factors influence the extent of reflectance restoration. In this paper we aim at identifying optimized cleaning strategies suitable for CST plants, able to restore mirror reflectance by high-pressure water-spray systems through the enhancement of shear stress over reflectors' surface. In order to evaluate the forces generated by water-spray jet impingement during the cleaning process, fluid dynamics simulations have been undertaken with ANSYS CFX software. In this analysis, shear forces represent the "critical phenomena" within the soil removal process. Enhancing shear forces on a particular area of the target surface, varying the angle of impingement in combination with the variation of standoff distances, and managing the interaxial distance of nozzles can increase cleaning efficiency. This procedure intends to improve the cleaning operation for CST mirrors reducing spotted surface and increasing particles removal efficiency. However, turbulence developed by adjacent flows decrease the shear stress generated on the reflectors surface. The presence of turbulence is identified by the formation of "fountain regions" which are mostly responsible of cleaning inefficiency. By numerical analysis using ANSYS CFX, we have modelled a stationary water-spray system with an array of three nozzles in line, with two angles of impingement: θ = 90° and θ = 75°. Several numerical tests have been carried out, varying the interaxial distance of

  14. Experimental Research on Water Boiling Heat Transfer on Horizontal Copper Rod Surface at Sub-Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Li-Hua Yu

    2015-09-01

    Full Text Available In recent years, water (R718 as a kind of natural refrigerant—which is environmentally-friendly, safe and cheap—has been reconsidered by scholars. The systems of using water as the refrigerant, such as water vapor compression refrigeration and heat pump systems run at sub-atmospheric pressure. So, the research on water boiling heat transfer at sub-atmospheric pressure has been an important issue. There are many research papers on the evaporation of water, but there is a lack of data on the characteristics at sub-atmospheric pressures, especially lower than 3 kPa (the saturation temperature is 24 °C. In this paper, the experimental research on water boiling heat transfer on a horizontal copper rod surface at 1.8–3.3 kPa is presented. Regression equations of the boiling heat transfer coefficient are obtained based on the experimental data, which are convenient for practical application.

  15. Relative Distribution of Water Clusters at Temperature (300-3000K) and Pressure (1-500MPa)

    CERN Document Server

    Ri, Yong-U; Sin, Kye-Ryong

    2016-01-01

    At 300-3000K and 1-500MPa, variations of relative contents for small water clusters (H2O)n (n=1~6) were calculated by using statistical mechanical methods. First, 9 kinds of small water clusters were selected and their structures were optimized by using ab initio method. In the wide range of temperature (300-3000K) and pressure (1-500MPa), their equilibrium constants of reactions for formation of 9 kinds of water clusters were determined by using molecular partition function. Next, changes of contents (molar fractions) as function of temperature and pressure were estimated. The obtained results for small water clusters can be used to interpret temperature-pressure dependency of the average number for the hydrogen bonds in water clusters and redistribution of the water clusters at the ultrasonic cavitation reactions.

  16. High Pressure Water Jet System Performance Assessment Project A-2A

    Energy Technology Data Exchange (ETDEWEB)

    FARWICK, C.C.

    1999-12-03

    Performance assessment for canister cleaning system in the KE Basin. Information obtained from this assessment will be used to design any additional equipment used to clean canisters. After thorough review of the design, maintenance history and operational characteristics of the 105 K East (KE) canister cleaning system, Bartlett recommends that the high pressure water jet system (HPWJS) be modified as outlined in section 5.0, and retained for future use. Further, it is recommended that Spent Nuclear Fuel (SNF) Project consider use of a graded approach for canister cleaning, based on individual canister type and characteristics. This approach would allow a simple method to be used on canisters not needing the more rigorous, high-pressure method. Justification is provided in section 5.0. Although Bartlett has provided some preliminary cost estimates, it is recommended that SNF Project perform a detailed cost-benefit analysis to weigh the alternatives presented.

  17. Power supply improvements for ballasts-low pressure mercury/argon discharge lamp for water purification

    Science.gov (United States)

    Bokhtache, A. Aissa; Zegaoui, A.; Djahbar, A.; Allouache, H.; Hemici, K.; Kessaissia, F. Z.; Bouchrit, M. S.; Aillerie, M.

    2017-02-01

    The low-pressure electrical discharges established in the mercury rare gas mixtures are the basis of many applications both in the field of lighting and for industrial applications. In order to select an efficient high frequency power supply (ECG -based PWM inverter), we present and discuss results obtained in the simulation of three kinds of power supplies delivering a 0.65 A - 50KHz sinusoidal current dedicated to power low pressure UV Mercury - Argon lamp used for effect germicide on water treatment thus allowing maximum UVC radiation at 253.7 nm. Three ballasts half-bridge configurations were compared with criteria based on resulting germicide efficiency, electrical yield and reliability, for example the quality of the sinusoidal current with reduced THD, and finally, we also considered in this analysis the final economic aspect.

  18. Renin, water drinking, walt preference and blood pressure in alcohol preferring and alcohol avoiding rats.

    Science.gov (United States)

    Linkola, J; Tikkanen, I; Fyhrquist, F; Rusi, M

    1980-02-01

    Mechanisms controlling fluid volume were studied in alcohol preferring AA (Alko, Alcohol) and alcohol avoiding ANA (Alko, Non-Alcohol) rats. Hypertonic sodium chloride solution (5%) given orally caused a higher dipsogenic response in AA rats than in the ANA's. One hour after ethanol loading (4.8 g/kg, by stomach tube), plasma renin activity of AA rats was four times as high as in ANA rats. ANA rats had higher degree of sodium chloride (0.9%) preference and higher blood pressure. The strain differences in voluntary salt intake and salt metabolism may modulate the consumption of calories and water as well as blood pressure and different reactivity of the renin system in AA and ANA rats.

  19. Molecular density functional theory for water with liquid-gas coexistence and correct pressure.

    Science.gov (United States)

    Jeanmairet, Guillaume; Levesque, Maximilien; Sergiievskyi, Volodymyr; Borgis, Daniel

    2015-04-21

    The solvation of hydrophobic solutes in water is special because liquid and gas are almost at coexistence. In the common hypernetted chain approximation to integral equations, or equivalently in the homogenous reference fluid of molecular density functional theory, coexistence is not taken into account. Hydration structures and energies of nanometer-scale hydrophobic solutes are thus incorrect. In this article, we propose a bridge functional that corrects this thermodynamic inconsistency by introducing a metastable gas phase for the homogeneous solvent. We show how this can be done by a third order expansion of the functional around the bulk liquid density that imposes the right pressure and the correct second order derivatives. Although this theory is not limited to water, we apply it to study hydrophobic solvation in water at room temperature and pressure and compare the results to all-atom simulations. The solvation free energy of small molecular solutes like n-alkanes and hard sphere solutes whose radii range from angstroms to nanometers is now in quantitative agreement with reference all atom simulations. The macroscopic liquid-gas surface tension predicted by the theory is comparable to experiments. This theory gives an alternative to the empirical hard sphere bridge correction used so far by several authors.

  20. Numerical investigation on stress corrosion cracking behavior of dissimilar weld joints in pressurized water reactor plants

    Directory of Open Access Journals (Sweden)

    Lingyan Zhao

    2014-07-01

    Full Text Available There have been incidents recently where stress corrosion cracking (SCC observed in the dissimilar metal weld (DMW joints connecting the reactor pressure vessel (RPV nozzle with the hot leg pipe. Due to the complex microstructure and mechanical heterogeneity in the weld region, dissimilar metal weld joints are more susceptible to SCC than the bulk steels in the simulated high temperature water environment of pressurized water reactor (PWR. Tensile residual stress (RS, in addition to operating loads, has a great contribution to SCC crack growth. Limited experimental conditions, varied influence factors and diverging experimental data make it difficult to accurately predict the SCC behavior of DMW joints with complex geometry, material configuration, operating loads and crack shape. Based on the film slip/dissolution oxidation model and elastic-plastic finite element method (EPFEM, an approach is developed to quantitatively predict the SCC growth rate of a RPV outlet nozzle DMW joint. Moreover, this approach is expected to be a pre-analytical tool for SCC experiment of DMW joints in PWR primary water environment.

  1. Optical modeling of nickel-base alloys oxidized in pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Clair, A. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon cedex (France); Foucault, M.; Calonne, O. [Areva ANP, Centre Technique Departement Corrosion-Chimie, 30 Bd de l' industrie, BP 181, 71205 Le Creusot (France); Finot, E., E-mail: Eric.Finot@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon cedex (France)

    2012-10-01

    The knowledge of the aging process involved in the primary water of pressurized water reactor entails investigating a mixed growth mechanism in the corrosion of nickel-base alloys. A mixed growth induces an anionic inner oxide and a cationic diffusion parallel to a dissolution-precipitation process forms the outer zone. The in situ monitoring of the oxidation kinetics requires the modeling of the oxide layer stratification with the full knowledge of the optical constants related to each component. Here, we report the dielectric constants of the alloys 600 and 690 measured by spectroscopic ellipsometry and fitted to a Drude-Lorentz model. A robust optical stratification model was determined using focused ion beam cross-section of thin foils examined by transmission electron microscopy. Dielectric constants of the inner oxide layer depleted in chromium were assimilated to those of the nickel thin film. The optical constants of both the spinels and extern layer were determined. - Highlights: Black-Right-Pointing-Pointer Spectroscopic ellipsometry of Ni-base alloy oxidation in pressurized water reactor Black-Right-Pointing-Pointer Measurements of the dielectric constants of the alloys Black-Right-Pointing-Pointer Optical simulation of the mixed oxidation process using a three stack model Black-Right-Pointing-Pointer Scattered crystallites cationic outer layer; linear Ni-gradient bottom layer Black-Right-Pointing-Pointer Determination of the refractive index of the spinel and the Cr{sub 2}O{sub 3} layers.

  2. The effect of temperature and methanol–water mixture on pressurized hot water extraction (PHWE) of anti-HIV analogoues from Bidens pilosa

    CSIR Research Space (South Africa)

    Gbashi, S

    2016-06-01

    Full Text Available Pressurized hot water extraction (PHWE) technique has recently gain much attention for the extraction of biologically active compounds from plant tissues for analytical purposes, due to the limited use of organic solvents, its cost...

  3. GOZCARDS Source Data for Water Vapor Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

    Data.gov (United States)

    National Aeronautics and Space Administration — The GOZCARDS Source Data for Water Vapor Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozSmlpH2O) contains zonal means and related...

  4. GOZCARDS Merged Data for Water Vapor Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

    Data.gov (United States)

    National Aeronautics and Space Administration — The GOZCARDS Merged Data for Water Vapor Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozMmlpH2O) contains zonal means and related...

  5. Where do winds come from? A new theory on how water vapor condensation influences atmospheric pressure and dynamics

    CERN Document Server

    Makarieva, A M; Sheil, D; Nobre, A D; Li, B -L

    2010-01-01

    Phase transitions of atmospheric water play a ubiquitous role in the Earth's climate system, but their direct impact on atmospheric dynamics has escaped wide attention. Here we examine and advance a theory as to how condensation influences atmospheric pressure through the mass removal of water from the gas phase with a simultaneous account of the latent heat release. Building from the fundamental physical principles we show that condensation is associated with a decline in air pressure in the lower atmosphere. This decline occurs up to a certain height, which ranges from 3 to 4 km for surface temperatures from 10 to 30 deg C. We then estimate the horizontal pressure differences associated with water vapor condensation and find that these are comparable in magnitude with the pressure differences driving observed circulation patterns. The water vapor delivered to the atmosphere via evaporation represents a store of potential energy available to accelerate air and thus drive winds. Our estimates suggest that the...

  6. The effect of pressure and temperature on aluminium hydrolysis: Implications to trace metal scavenging in natural waters

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.

    Removal of aluminium through precipitation/scavenging in natural waters was evaluated based on its hydrolysis at different temperatures and pressures. In general, pH for the occurrence of cation hydrolysis was lowered with hike in temperature which...

  7. Assessing the efficiency of carbide drill bits and factors influencing their application to debris-rich subglacial ice

    Science.gov (United States)

    Yang, Cheng; Jiang, Jianliang; Cao, Pinlu; Wang, Jinsong; Fan, Xiaopeng; Shang, Yuequan; Talalay, Pavel

    2017-09-01

    When drilling into subglacial bedrock, drill operators commonly encounter basal ice containing high concentrations of rock debris and melt water. As such conditions can easily damage conventional ice drills, researchers have experimented with carbide, diamond, and polycrystalline diamond compact drill bits, with varying degrees of success. In this study, we analyzed the relationship between drilling speed and power consumption for a carbide drill bit penetrating debris-rich ice. We also assessed drill load, rotation speed, and various performance parameters for the cutting element, as well as the physical and mechanical properties of rock and ice, to construct mathematical models. We show that our modeled results are in close agreement with the experimental data, and that both penetration speed and power consumption are positively correlated with drill speed and load. When used in ice with 30% rock content, the maximum penetration speed of the carbide bit is 3.4 mm/s with a power consumption of ≤0.5 kW, making the bit suitable for use with existing electromechanical drills. Our study also provides a guide for further research into cutting heat and equipment design.

  8. Pressure drop correlation for air/water two-phase flow in horizontal helicoidal pipes

    Energy Technology Data Exchange (ETDEWEB)

    Ebadian, M.A.; Dong, Z.F.; Awwad, A.; Xin, R.C. [Florida International Univ., Miami, FL (United States)

    1995-10-01

    In this paper, an experimental investigation is reported for air/water two-phase flow in horizontal helicoidal pipes. The helicoidal pipes are constructed of Tygon tubing with varying inside diameters of 12.7 mm, 19.1 mm, 25.4 mm, and 38.1 mm wrapped around two different cylindrical concrete forms with outside diameters of 304.8 mm and 609.6 mm each. Also, the helix angle of each helicoidal pipe varies up to 20 degrees. The experiments are conducted for superficial water velocity in the range of U{sub L} = 0.008 {minus} 2.2 m/s and superficial air velocity in the range of U{sub G} = 0.2 {minus} 50 m/s. The pressure drop of the two-phase flow is measured and the data are correlated. It was found that the Lockhart-Martinelli correlation for a straight pipe can represent the data for a helicoidal pipe only in the cases of a high rate of flow; nevertheless, the pressure drop relates strongly to the superficial air/water velocity when the flow rate is lower. The helix angle has almost no effect on the pressure drop, although the pipe and coil diameters have certain effects in low rates of flow. Correlations for two-phase flow in each of the horizontal helicoidal pipes have been established based on the present data. Helicoidal pipes are used extensively in compact heat exchangers, boilers, refrigerators, nuclear reactors, chemical plants, as well as the food, drug, and cryogenics industries.

  9. Tissue distribution of CysAP activity and its relationship to blood pressure and water balance.

    Science.gov (United States)

    Prieto, Isabel; Villarejo, Ana Belén; Segarra, Ana Belén; Wangensteen, Rosemary; Banegas, Inmaculada; de Gasparo, Marc; Vanderheyden, Patrick; Zorad, Stefan; Vives, Francisco; Ramírez-Sánchez, Manuel

    2015-08-01

    To better understand the functional role of soluble (Sol) and membrane-bound (MB) cystinyl-aminopeptidase (CysAP) activities, we studied differentially their organ distribution in adult male Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR)with or without treatment with captopril.We searched for a possible tissue-specific association of CysAP with water balance and blood pressure. We used twenty WKY rats distributed in ten controls and ten captopril-treated, and sixteen SHR divided in eight controls and eight captopril-treated. Captopril (100 mg/kg/day) was administered in drinking water for 4 weeks. Systolic blood pressure, water intake and diuresis were measured individually. CysAP was assayed fluorometrically using L-cystine-di-β-naphthylamide as substrate. Sol or MB activities were generally higher in SHR compared to WKY notably in hypothalamus and kidney than in the other tissues. Captopril mainly decreased CysAP in SHR whereas it increased in WKY. The distribution of Sol CysAP was more homogeneous among tissues ofWKY than SHR. In contrast, the distribution of MB CysAP was more heterogeneous than Sol CysAP in both WKY and SHR. This suggests that MB CysAP activity acts in a more tissue-specific manner than Sol CysAP. The majority of the significant correlations between tissue activities and the measured physiological parameters were observed mostly in renal medulla and hypothalamus. Sol and MB CysAP activities, acting separately or in concert and mainly in renal medulla, regulate the function of their susceptible endogenous substrates, and may participate meaningfully in the control of blood pressure and fluid balance.

  10. In-Vessel Melt Retention of Pressurized Water Reactors: Historical Review and Future Research Needs

    OpenAIRE

    Ma, Weimin; Yuan, Yidan; Sehgal, Bal Raj

    2016-01-01

    A historical review of in-vessel melt retention (IVR) is given, which is a severe accident mitigation measure extensively applied in Generation III pressurized water reactors (PWRs). The idea of IVR actually originated from the back-fitting of the Generation II reactor Loviisa VVER-440 in order to cope with the core-melt risk. It was then employed in the new deigns such as Westinghouse AP1000, the Korean APR1400 as well as Chinese advanced PWR designs HPR1000 and CAP1400. The most influential...

  11. Mesos-scale modeling of irradiation in pressurized water reactor concrete biological shields

    Energy Technology Data Exchange (ETDEWEB)

    Le Pape, Yann [ORNL; Huang, Hai [Idaho National Laboratory (INL)

    2016-01-01

    Neutron irradiation exposure causes aggregate expansion, namely radiation-induced volumetric expansion (RIVE). The structural significance of RIVE on a portion of a prototypical pressurized water reactor (PWR) concrete biological shield (CBS) is investigated by using a meso- scale nonlinear concrete model with inputs from an irradiation transport code and a coupled moisture transport-heat transfer code. RIVE-induced severe cracking onset appears to be triggered by the ini- tial shrinkage-induced cracking and propagates to a depth of > 10 cm at extended operation of 80 years. Relaxation of the cement paste stresses results in delaying the crack propagation by about 10 years.

  12. Vibration analysis of land mine detection using high-pressure water jets

    Science.gov (United States)

    Denier, Robert; Herrick, Thomas J.

    2000-08-01

    The goal of the waterjet-based mine location and identification project is to investigate the use of waterjets to locate and differentiate buried objects. When a buried object is struck with a high-pressure waterjet, the impact will cause characteristic vibrations in the object depending on the object's shape and composition. These vibrations will be transferred to the ground and then to the water stream that is hitting the object. Some of these vibrations will also be transferred to the air via the narrow channel the waterjet cuts in the ground.

  13. Geophysical investigation of the pressure field produced by water guns at a pond site in La Crosse, Wisconsin

    Science.gov (United States)

    Adams, Ryan F.; Morrow, William S.

    2015-09-03

    Three different geophysical sensor types were used to characterize the underwater pressure waves generated by the underwater firing of a seismic water gun and their suitability for establishing a pressure barrier to potentially direct or prevent the movement of the Asian carps. The sensors used to collect the seismic information were blast rated hydrophones and underwater blast sensors. Specific location information for the water guns and the sensors was obtained using either laser rangefinders or differentially corrected global positioning systems (GPS).

  14. Pressure Drop in Cold Water Flow in Beds Packed with Several Kinds of Crushed Ice.

    Science.gov (United States)

    Yanadori, Michio; Ohira, Akiyoshi

    This paper deals with the pressure drop in cold water flow in the beds packed with crushed ice. 1n each case, ice-packed beds were filled with sevral kinds of crushed ice, and friction-loss coefficients were examined. The following results were obtained. (1) The friction factor of rectangular-type ice-packed beds is smaller than that of ideal sphere beds by about 1/4 to 1/2. (2) The friction factor of small-stone-type ice-packed beds is about twice as large as that of ideal sphere beds. (3) It is difficult to compare the flow model of water in restricted channel of particle-type ice-packed beds with that of ideal packed beds.

  15. A jazz-based approach for optimal setting of pressure reducing valves in water distribution networks

    Science.gov (United States)

    De Paola, Francesco; Galdiero, Enzo; Giugni, Maurizio

    2016-05-01

    This study presents a model for valve setting in water distribution networks (WDNs), with the aim of reducing the level of leakage. The approach is based on the harmony search (HS) optimization algorithm. The HS mimics a jazz improvisation process able to find the best solutions, in this case corresponding to valve settings in a WDN. The model also interfaces with the improved version of a popular hydraulic simulator, EPANET 2.0, to check the hydraulic constraints and to evaluate the performances of the solutions. Penalties are introduced in the objective function in case of violation of the hydraulic constraints. The model is applied to two case studies, and the obtained results in terms of pressure reductions are comparable with those of competitive metaheuristic algorithms (e.g. genetic algorithms). The results demonstrate the suitability of the HS algorithm for water network management and optimization.

  16. A Flooding Induced Station Blackout Analysis for a Pressurized Water Reactor Using the RISMC Toolkit

    Directory of Open Access Journals (Sweden)

    Diego Mandelli

    2015-01-01

    Full Text Available In this paper we evaluate the impact of a power uprate on a pressurized water reactor (PWR for a tsunami-induced flooding test case. This analysis is performed using the RISMC toolkit: the RELAP-7 and RAVEN codes. RELAP-7 is the new generation of system analysis codes that is responsible for simulating the thermal-hydraulic dynamics of PWR and boiling water reactor systems. RAVEN has two capabilities: to act as a controller of the RELAP-7 simulation (e.g., component/system activation and to perform statistical analyses. In our case, the simulation of the flooding is performed by using an advanced smooth particle hydrodynamics code called NEUTRINO. The obtained results allow the user to investigate and quantify the impact of timing and sequencing of events on system safety. In addition, the impact of power uprate is determined in terms of both core damage probability and safety margins.

  17. Atmospheric-pressure electric discharge as an instrument of chemical activation of water solutions

    Science.gov (United States)

    Rybkin, V. V.; Shutov, D. A.

    2017-11-01

    Results of experimental studies and numerical simulations of physicochemical characteristics of plasmas generated in different types of atmospheric-pressure discharges (pulsed streamer corona, gliding electric arc, dielectric barrier discharge, glow-discharge electrolysis, diaphragmatic discharge, and dc glow discharge) used to initiate various chemical processes in water solutions are analyzed. Typical reactor designs are considered. Data on the power supply characteristics, plasma electron parameters, gas temperatures, and densities of active particles in different types of discharges excited in different gases and their dependences on the external parameters of discharges are presented. The chemical composition of active particles formed in water is described. Possible mechanisms of production and loss of plasma particles are discussed.

  18. A comparative summary on streamers of positive corona discharges in water and atmospheric pressure gases

    Science.gov (United States)

    Tachibana, Kunihide; Motomura, Hideki

    2015-07-01

    From an intention of summarizing present understandings of positive corona discharges in water and atmospheric pressure gases, we tried to observe streamers in those media by reproducing and complementing previously reported results under a common experimental setup. We used a point-to-plane electrode configuration with different combinations of electrode gap (7 and 19 mm length) and pulsed power sources (0.25 and 2.5 ɛs duration). The general features of streamers were similar and the streamer-to-spark transition was also observed in both the media. However, in the details large differences were observed due to inherent nature of the media. The measured propagation speed of streamers in water of 0.035 × 106 ms-1 was much smaller than the speed in gases (air, N2 and Ar) from 0.4 to 1.1 × 106 ms-1 depending on species. In He the discharge looked glow-like and no streamer was observed. The other characteristics of streamers in gases, such as inception voltage, number of branches and thickness did also depend on the species. The thickness and the length of streamers in water were smaller than those in gases. From the volumetric expansion of a streamer in water after the discharge, the molecular density within the streamer medium was estimated to be rarefied from the density of water by about an order of magnitude in the active discharge phase. We derived also the electron density from the analysis of Stark broadened spectral lines of H and O atoms on the order of 1025 m-3 at the earlier time of the streamer propagation. The analyzed background blackbody radiation, rotational temperature of OH band emission and population density of Cu atomic lines yielded a consistent temperature of the streamer medium between 7000 and 10 000 K. Using the present data with a combination of the analysis of static electric field and previously reported results, we discuss the reason for the relatively low streamer inception voltage in water as compared to the large difference in the

  19. Pump schedules optimisation with pressure aspects in complex large-scale water distribution systems

    Directory of Open Access Journals (Sweden)

    P. Skworcow

    2014-06-01

    Full Text Available This paper considers optimisation of pump and valve schedules in complex large-scale water distribution networks (WDN, taking into account pressure aspects such as minimum service pressure and pressure-dependent leakage. An optimisation model is automatically generated in the GAMS language from a hydraulic model in the EPANET format and from additional files describing operational constraints, electricity tariffs and pump station configurations. The paper describes in details how each hydraulic component is modelled. To reduce the size of the optimisation problem the full hydraulic model is simplified using module reduction algorithm, while retaining the nonlinear characteristics of the model. Subsequently, a nonlinear programming solver CONOPT is used to solve the optimisation model, which is in the form of Nonlinear Programming with Discontinuous Derivatives (DNLP. The results produced by CONOPT are processed further by heuristic algorithms to generate integer solution. The proposed approached was tested on a large-scale WDN model provided in the EPANET format. The considered WDN included complex structures and interactions between pump stations. Solving of several scenarios considering different horizons, time steps, operational constraints, demand levels and topological changes demonstrated ability of the approach to automatically generate and solve optimisation problems for a variety of requirements.

  20. Integrity of the reactor coolant boundary of the European pressurized water reactor (EPR)

    Energy Technology Data Exchange (ETDEWEB)

    Goetsch, D.; Bieniussa, K.; Schulz, H.; Jalouneix, J.

    1997-04-01

    This paper is an abstract of the work performed in the frame of the development of the IPSN/GRS approach in view of the EPR conceptual safety features. EPR is a pressurized water reactor which will be based on the experience gained by utilities and designers in France and in Germany. The reactor coolant boundary of a PWR includes the reactor pressure vessel (RPV), those parts of the steam generators (SGs) which contain primary coolant, the pressurizer (PSR), the reactor coolant pumps (RCPs), the main coolant lines (MCLs) with their branches as well as the other connecting pipes and all branching pipes including the second isolation valves. The present work covering the integrity of the reactor coolant boundary is mainly restricted to the integrity of the main coolant lines (MCLs) and reflects the design requirements for the main components of the reactor coolant boundary. In the following the conceptual aspects, i.e. design, manufacture, construction and operation, will be assessed. A main aspect is the definition of break postulates regarding overall safety implications.

  1. Geochemical processes leading to the precipitation of subglacial carbonate crusts at Bossons glacier, Mont Blanc Massif (French Alps)

    Science.gov (United States)

    Thomazo, Christophe; Buoncristiani, Jean-Francois; Vennin, Emmanuelle; Pellenard, Pierre; Cocquerez, Theophile; Mugnier, Jean L.; Gérard, Emmanuelle

    2017-09-01

    Cold climate carbonates can be used as paleoclimatic proxies. The mineralogy and isotopic composition of subglacially precipitated carbonate crusts provide insights into the subglacial conditions and processes occurring at the meltwater-basement rock interface of glaciers. This study documents such crusts discovered on the lee side of a gneissic roche moutonnée at the terminus of the Bossons glacier in the Mont Blanc Massif area (France). The geological context and mineralogical investigations suggest that the Ca used for the precipitation of large crystals of radial fibrous sparite observed in these crusts originated from subglacial chemical weathering of Ca-bearing minerals of the local bedrock (plagioclase and amphibole). Measurements of the carbon and oxygen isotope compositions in the crusts indicate precipitation at, or near to, equilibrium with the basal meltwater under open system conditions during refreezing processes. The homogeneous and low carbonate δ13C values (ca. -11.3‰) imply a large contribution of soil organic carbon to the Bossons subglacial meltwater carbon reservoir at the time of deposition. In addition, organic remains trapped within the subglacially precipitated carbonate crusts give an age of deposition around 6500 years cal BP suggesting that the Mid-Holocene climatic and pedological optima are archived in the Bossons glacier carbonate crusts.

  2. Changes in Land Surface Water Dynamics since the 1990s and Relation to Population Pressure

    Science.gov (United States)

    Prigent, C.; Papa, F.; Aires, F.; Jimenez, C.; Rossow, W. B.; Matthews, E.

    2012-01-01

    We developed a remote sensing approach based on multi-satellite observations, which provides an unprecedented estimate of monthly distribution and area of land-surface open water over the whole globe. Results for 1993 to 2007 exhibit a large seasonal and inter-annual variability of the inundation extent with an overall decline in global average maximum inundated area of 6% during the fifteen-year period, primarily in tropical and subtropical South America and South Asia. The largest declines of open water are found where large increases in population have occurred over the last two decades, suggesting a global scale effect of human activities on continental surface freshwater: denser population can impact local hydrology by reducing freshwater extent, by draining marshes and wetlands, and by increasing water withdrawals. Citation: Prigent, C., F. Papa, F. Aires, C. Jimenez, W. B. Rossow, and E. Matthews (2012), Changes in land surface water dynamics since the 1990s and relation to population pressure, in section 4, insisting on the potential applications of the wetland dataset.

  3. Atmospheric Pressure Glow Discharge for Point-of-Use Water Treatment

    Science.gov (United States)

    Lindsay, Alexander; Byrns, Brandon; Shannon, Steven; Knappe, Detlef

    2012-10-01

    Treatment of biological and chemical contaminants is an area of growing global interest where atmospheric pressure plasmas can make a significant contribution. Addressing key challenges of volume processing and operational cost, a large volume 162 MHz coaxial air-plasma source has been developed.footnotetextByrns (2012) J. Phys. D: Appl. Phys. 45 (2012) 195204 Because of VHF ballasting effects, the electric discharge is maintained at a steady glow, allowing formation of critical non-equilibrium chemistry. High densities, ne = 10^11-10^12, have been recorded. The atmospheric nature of the device permits straightforward and efficient treatment of water samples. [H^+] concentrations in 150 milliliter tap water samples have been shown to increase by 10^5 after five minutes of discharge exposure. Recent literature has demonstrated that increasing acidity is strongly correlated with a solution's ability to deactivate microbial contaminants.footnotetextTraylor (2011) J. Phys. D: Appl. Phys. 44 (2011) 472001 The work presented here will explore the impact of treatment gas, system configuration, and power density on water disinfection and PFC abatement. An array of plasma diagnostics, including OES and electrical measurements, are combined with post-process water analysis, including GC-MS and QT analysis of coliform and E.coli bacteria. Development of volume processing atmospheric plasma disinfection methods offers promise for point-of-use treatments in developing areas of the world, potentially supplementing or replacing supply and weather-dependent disinfection methods.

  4. Effect of pressure on the anomalous response functions of a confined water monolayer at low temperature

    Science.gov (United States)

    Mazza, Marco G.; Stokely, Kevin; Stanley, H. Eugene; Franzese, Giancarlo

    2012-11-01

    We study a coarse-grained model for a water monolayer that cannot crystallize due to the presence of confining interfaces, such as protein powders or inorganic surfaces. Using both Monte Carlo simulations and mean field calculations, we calculate three response functions: the isobaric specific heat CP, the isothermal compressibility KT, and the isobaric thermal expansivity αP. At low temperature T, we find two distinct maxima in CP, KT, and |αP|, all converging toward a liquid-liquid critical point (LLCP) with increasing pressure P. We show that the maximum in CP at higher T is due to the fluctuations of hydrogen (H) bond formation and that the second maximum at lower T is due to the cooperativity among the H bonds. We discuss a similar effect in KT and |αP|. If this cooperativity were not taken into account, both the lower-T maximum and the LLCP would disappear. However, comparison with recent experiments on water hydrating protein powders provides evidence for the existence of the lower-T maximum, supporting the hypothesized LLCP at positive P and finite T. The model also predicts that when P moves closer to the critical P the CP maxima move closer in T until they merge at the LLCP. Considering that other scenarios for water are thermodynamically possible, we discuss how an experimental measurement of the changing separation in T between the two maxima of CP as P increases could determine the best scenario for describing water.

  5. The effect of head-down tilt and water immersion on intracranial pressure in nonhuman primates

    Science.gov (United States)

    Keil, Lanny C.; Mckeever, Kenneth H.; Skidmore, Michael G.; Hines, John; Severs, Walter B.

    1992-01-01

    Intracranial pressure (ICP) is investigated in primates during and after -6-deg head-down tilt (HDT) and immersion in water to examine the effects of the headward fluid shift related to spaceflight. Following the HDT the primates are subjected to head-out thermoneutral water immersion, and the ICP is subsequently measured. ICP is found to increase from 3.8 +/- 1.1 to 5.3 +/- 1.3 mm Hg during the horizontal control period. ICP stabilizes at -6.3 +/- 1.3 mm Hg and then increases to -2.2 +/- 1.9 mm Hg during partial immersion, and ICP subsequently returns to preimmersion levels after immersion. These data indicate that exposure to HDT or water immersion lead to an early sharp increase in ICP, and water immersion alone leads to higher ICP levels. A significant conclusion of the work is that the ICP did not approach pathological levels, and this finding is relevant to human spaceflight research.

  6. The Effect of Water Pressure and Chlorine Concentration on Microbiological Characteristics of Spray Washed Broiler Carcasses

    Directory of Open Access Journals (Sweden)

    Pissol AD

    2013-08-01

    Full Text Available The objective of this study was to evaluate the efficiency of water pressure and concentration of dichloromethane after the evisceration system under the fecal decontamination of chicken carcasse  surfaces with and without apparent contamination. From a total of  322 carcasses, 50% were intentionally added chicken droppings in an area of more  than 2 cm2 and the rest of carcasses were kept without fecal inoculation. Escherichia coli and Enterobacteriaceae counting was carried out in samples immediately after the inoculation (initial counting and after different treatments. Treatments consisted of water with different pressures (1.5,  3.5 and  5.5 Kgf/cm2, and the addition of a echnological adjuvant (dichloride at the concentrations of 0, 5 and 10 ppm. The results were validated using  40 chicken carcasses for each treatment by means of a  22  factorial statistical design. The results showed no significant differences (P

  7. Characterization of pressurized hot water extracts of grape pomace: chemical and biological antioxidant activity.

    Science.gov (United States)

    Vergara-Salinas, J R; Vergara, Mauricio; Altamirano, Claudia; Gonzalez, Álvaro; Pérez-Correa, J R

    2015-03-15

    Pressurized hot water extracts obtained at different temperatures possess different compositions and antioxidant activities and, consequently, different bioactivities. We characterized two pressurized hot water extracts from grape pomace obtained at 100°C (GPE100) and 200°C (GPE200) in terms of antioxidant activity and composition, as well as protective effect on cell growth and mitochondrial membrane potential (Δψm) in a HL-60 cell culture under oxidative conditions. GPE100 extracts were richer in polyphenols and poorer in Maillard reaction products (MRPs) than were GPE200 extracts. Moreover, hydroxymethylfurfural was detected only in GPE200. Both extracts exhibited similar protective effects on cell growth (comparable to the effect of trolox). In addition, GPE100 strongly decreased the Δψm loss, reaching values even lower than those of the control culture. This protective effect may be related to its high polyphenols content. At the highest concentration assessed, both extracts showed strong cytotoxicity, especially GPE200. This cytotoxicity could be related to their MRPs content. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Drinking Water Salinity and Raised Blood Pressure: Evidence from a Cohort Study in Coastal Bangladesh

    Science.gov (United States)

    Chowdhury, Muhammad A.H.; Haines, Andy; Alam, Dewan S.; Hoque, Mohammad A.; Butler, Adrian P.; Khan, Aneire E.; Mojumder, Sontosh K.; Blangiardo, Marta A.G.; Elliott, Paul; Vineis, Paolo

    2017-01-01

    Background: Millions of coastal inhabitants in Southeast Asia have been experiencing increasing sodium concentrations in their drinking-water sources, likely partially due to climate change. High (dietary) sodium intake has convincingly been proven to increase risk of hypertension; it remains unknown, however, whether consumption of sodium in drinking water could have similar effects on health. Objectives: We present the results of a cohort study in which we assessed the effects of drinking-water sodium (DWS) on blood pressure (BP) in coastal populations in Bangladesh. Methods: DWS, BP, and information on personal, lifestyle, and environmental factors were collected from 581 participants. We used generalized linear latent and mixed methods to model the effects of DWS on BP and assessed the associations between changes in DWS and BP when participants experienced changing sodium levels in water, switched from “conventional” ponds or tube wells to alternatives [managed aquifer recharge (MAR) and rainwater harvesting] that aimed to reduce sodium levels, or experienced a combination of these changes. Results: DWS concentrations were highly associated with BP after adjustments for confounding factors. Furthermore, for each 100mg/L reduction in sodium in drinking water, systolic/diastolic BP was lower on average by 0.95/0.57mmHg, and odds of hypertension were lower by 14%. However, MAR did not consistently lower sodium levels. Conclusions: DWS is an important source of daily sodium intake in salinity-affected areas and is a risk factor for hypertension. Considering the likely increasing trend in coastal salinity, prompt action is required. Because MAR showed variable effects, alternative technologies for providing reliable, safe, low-sodium fresh water should be developed alongside improvements in MAR and evaluated in “real-life” salinity-affected settings. https://doi.org/10.1289/EHP659 PMID:28599268

  9. Drinking Water Salinity and Raised Blood Pressure: Evidence from a Cohort Study in Coastal Bangladesh.

    Science.gov (United States)

    Scheelbeek, Pauline FD; Chowdhury, Muhammad A H; Haines, Andy; Alam, Dewan S; Hoque, Mohammad A; Butler, Adrian P; Khan, Aneire E; Mojumder, Sontosh K; Blangiardo, Marta A G; Elliott, Paul; Vineis, Paolo

    2017-05-30

    Millions of coastal inhabitants in Southeast Asia have been experiencing increasing sodium concentrations in their drinking-water sources, likely partially due to climate change. High (dietary) sodium intake has convincingly been proven to increase risk of hypertension; it remains unknown, however, whether consumption of sodium in drinking water could have similar effects on health. We present the results of a cohort study in which we assessed the effects of drinking-water sodium (DWS) on blood pressure (BP) in coastal populations in Bangladesh. DWS, BP, and information on personal, lifestyle, and environmental factors were collected from 581 participants. We used generalized linear latent and mixed methods to model the effects of DWS on BP and assessed the associations between changes in DWS and BP when participants experienced changing sodium levels in water, switched from "conventional" ponds or tube wells to alternatives [managed aquifer recharge (MAR) and rainwater harvesting] that aimed to reduce sodium levels, or experienced a combination of these changes. DWS concentrations were highly associated with BP after adjustments for confounding factors. Furthermore, for each 100 mg/L reduction in sodium in drinking water, systolic/diastolic BP was lower on average by 0.95/0.57 mmHg, and odds of hypertension were lower by 14%. However, MAR did not consistently lower sodium levels. DWS is an important source of daily sodium intake in salinity-affected areas and is a risk factor for hypertension. Considering the likely increasing trend in coastal salinity, prompt action is required. Because MAR showed variable effects, alternative technologies for providing reliable, safe, low-sodium fresh water should be developed alongside improvements in MAR and evaluated in "real-life" salinity-affected settings. https://doi.org/10.1289/EHP659.

  10. Aging of the containment pressure boundary in light-water reactor plants

    Energy Technology Data Exchange (ETDEWEB)

    Naus, D.J.; Oland, C.B. [Oak Ridge National Lab., TN (United States); Ellingwood, B.R. [Johns Hopkins Univ., Baltimore, MD (United States)] [and others

    1997-01-01

    Research is being conducted by the Oak Ridge National Laboratory to address aging of the containment pressure boundary in light-water reactor plants. The objectives of this work are to (1) identify the significant factors related to occurrence of corrosion, efficacy of inspection, and structural capacity reduction of steel containments and liners of concrete containments, and to make recommendations on use of risk models in regulatory decisions; (2) provide NRC reviewers a means of establishing current structural capacity margins for steel containments, and concrete containments as limited by liner integrity; and (3) provide recommendations, as appropriate, on information to be requested of licensees for guidance that could be utilized by NRC reviewers in assessing the seriousness of reported incidences of containment degradation. In meeting these objectives research is being conducted in two primary task areas - pressure boundary condition assessment and root-cause resolution practices, and reliability-based condition assessments. Under the first task area a degradation assessment methodology was developed for use in characterizing the in-service condition of metal and concrete containment pressure boundary components and quantifying the amount of damage that is present. An assessment of available destructive and nondestructive techniques for examining steel containments and liners is ongoing. Under the second task area quantitative structural reliability analysis methods are being developed for application to degraded metallic pressure boundaries to provide assurances that they will be able to withstand future extreme loads during the desired service period with a level of reliability that is sufficient for public safety. To date, mathematical models that describe time-dependent changes in steel due to aggressive environmental factors have been identified, and statistical data supporting their use in time-dependent reliability analysis have been summarized.

  11. Modified water solubility of milk protein concentrate powders through the application of static high pressure treatment.

    Science.gov (United States)

    Udabage, Punsandani; Puvanenthiran, Amirtha; Yoo, Jin Ah; Versteeg, Cornelis; Augustin, Mary Ann

    2012-02-01

    The effects of high pressure (HP) treatment (100-400 MPa at 10-60 °C) on the solubility of milk protein concentrate (MPC) powders were tested. The solubility, measured at 20 °C, of fresh MPC powders made with no HP treatment was 66%. It decreased by 10% when stored for 6 weeks at ambient temperature (~20 °C) and continued to decrease to less than 50% of its initial solubility after 12 months of storage. Of the combinations of pressure and heat used, a pressure of 200 MPa at 40 °C applied to the concentrate before spray drying was found to be the most beneficial for improved solubility of MPC powders. This combination of pressure/heat improved the initial cold water solubility to 85%. The solubility was maintained at this level after 6 weeks storage at ambient temperature and 85% of the initial solubility was preserved after 12 months. The improved solubility of MPC powders on manufacture and on storage are attributed to an altered surface composition arising from an increased concentration of non-micellar casein in the milk due to HP treatment prior to drying. The improved solubility of high protein powders (95% protein) made from blends of sodium caseinate and whey protein isolate compared with MPC powders (~85% protein) made from ultrafiltered/diafiltered milk confirmed the detrimental role of micellar casein on solubility. The results suggest that increasing the non-micellar casein content by HP treatment of milk or use of blends of sodium caseinate and whey proteins are strategies that may be used to obtain high protein milk powders with enhanced solubility.

  12. Air humidity and water pressure effects on the performance of air-cathode microbial fuel cell cathodes

    KAUST Repository

    Ahn, Yongtae

    2014-02-01

    To better understand how air cathode performance is affected by air humidification, microbial fuel cells were operated under different humidity conditions or water pressure conditions. Maximum power density decreased from 1130 ± 30 mW m-2 with dry air to 980 ± 80 mW m -2 with water-saturated air. When the cathode was exposed to higher water pressures by placing the cathode in a horizontal position, with the cathode oriented so it was on the reactor bottom, power was reduced for both with dry (1030 ± 130 mW m-2) and water-saturated (390 ± 190 mW m-2) air. Decreased performance was partly due to water flooding of the catalyst, which would hinder oxygen diffusion to the catalyst. However, drying used cathodes did not improve performance in electrochemical tests. Soaking the cathode in a weak acid solution, but not deionized water, mostly restored performance (960 ± 60 mW m-2), suggesting that there was salt precipitation in the cathode that was enhanced by higher relative humidity or water pressure. These results showed that cathode performance could be adversely affected by both flooding and the subsequent salt precipitation, and therefore control of air humidity and water pressure may need to be considered for long-term MFC operation. © 2013 Elsevier B.V. All rights reserved.

  13. High-pressure vapor-liquid equilibria of systems containing ethylene glycol, water and methane - Experimental measurements and modeling

    DEFF Research Database (Denmark)

    Folas, Georgios; Berg, Ole J.; Solbraa, Even

    2007-01-01

    This work presents new experimental phase equilibrium measurements of the binary MEG-methane and the ternary MEG-water-methane system at low temperatures and high pressures which are of interest to applications related to natural gas processing. Emphasis is given to MEG and water solubility...

  14. Improving the oxidation resistance of 316L stainless steel in simulated pressurized water reactor primary water by electropolishing treatment

    Energy Technology Data Exchange (ETDEWEB)

    Han, Guangdong [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Shanghai, 200072 (China); Lu, Zhanpeng, E-mail: zplu@shu.edu.cn [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Shanghai, 200072 (China); State Key Laboratory of Advanced Special Steels, Shanghai University, Shanghai, 200072 (China); Ru, Xiangkun; Chen, Junjie; Xiao, Qian; Tian, Yongwu [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Shanghai, 200072 (China)

    2015-12-15

    The oxidation behavior of 316L stainless steel specimens after emery paper grounding, mechanical polishing, and electropolishing were investigated in simulated pressurized water reactor primary water at 310 °C for 120 and 500 h. Electropolishing afforded improved oxidation resistance especially during the early immersion stages. Duplex oxide films comprising a coarse Fe-rich outer layer and a fine Cr-rich inner layer formed on all specimens after 500 h of immersion. Only a compact layer was observed on the electropolished specimen after 120 h of immersion. The enrichment of chromium in the electropolished layer contributed to the passivity and protectiveness of the specimen. - Highlights: • Duplex oxide films on ground and mechanically polished specimens. • Compact oxide on electropolished specimen after 120 h immersion. • Large spinel outer layer rich in Fe and fine spinel inner layer rich in Cr. • Electropolishing improved oxidation resistance especially at the early stages. • Inhomogeneous Cr-rich inner layer with granular areas affected by surface treatment.

  15. Combined effects of high hydrostatic pressure and sodium nitrite on color, water holding capacity and texture of frankfurter

    Science.gov (United States)

    Jonas, G.; Csehi, B.; Palotas, P.; Toth, A.; Kenesei, Gy; Pasztor-Huszar, K.; Friedrich, L.

    2017-10-01

    The aim of this study was to investigate the effect of sodium nitrite and high hydrostatic pressure on the color, water holding capacity (WHC) and texture characteristics of frankfurter. Three hundred, 450 and 600 MPa (5 minutes; 20 °C) and 50, 75, 100 and 125 ppm (calculated on weight of meat) sodium nitrite were applied. Parameters were measured right after the pressure treatment. Data were evaluated with two-way analysis of variance (p 0.05) with pressure levels and sodium nitrite amounts as factors. Nitrite reduction significantly increased lightness (L*) and resulted in decreased redness (a*) value. The pressure treatments decreased the lightness at all nitrite concentrations and did not significantly affect the red color of frankfurters. Fifty and 75 ppm nitrite and pressurization at 300 or 450 MPa improved the water holding property of frankfurter. The pressure treatment did not significantly affect the WHC but changing the nitrite amount had significant effect on it. Interactive effect occurred between pressure levels and nitrite concentrations for hardness. The pressure treatment increased and the nitrite reduction decreased hardness. Significant changes were found in cohesiveness at 450 and 600 MPa in frankfurters containing 50 and 75 ppm nitrite: pressure treatment at higher levels and nitrite reduction decreased the value of cohesiveness.

  16. Design of a supercritical water-cooled reactor. Pressure vessel and internals

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Kai

    2008-08-15

    The High Performance Light Water Reactor (HPLWR) is a light water reactor with supercritical steam conditions which has been investigated within the 5th Framework Program of the European Commission. Due to the supercritical pressure of 25 MPa, water, used as moderator and as coolant, flows as a single phase through the core and can be directly fed to the turbine. Using the technology of coal fired power plants with supercritical steam conditions, the heat-up in the core is done in several steps to achieve the targeted high steam outlet temperature of 500.C without exceeding available cladding material limits. Based on a first design of a fuel assembly cluster for a HPLWR with a single pass core, the surrounding internals and the reactor pressure vessel (RPV) are dimensioned for the first time, following the safety standards of the nuclear safety standards commission in Germany. Furthermore, this design is extended to the incorporation of core arrangements with two and three passes. The design of the internals and the RPV are verified using mechanical or, in the case of large thermal deformations, combined mechanical and thermal stress analyses. Additionally, a passive safety component for the feedwater inlet of the RPV of the HPLWR is designed. Its purpose is the reduction of the mass flow rate in case of a LOCA for a feedwater line break until further steps are executed. Starting with a simple vortex diode, several steps are executed to enhance the performance of the diode and adapt it to this application. Then, this first design is further optimized using combined 1D and 3D flow analyses. Parametric studies determine the performance and characteristic for changing mass flow rates for this backflow limiter. (orig.)

  17. Acute blood pressure response in hypertensive elderly women immediately after water aerobics exercise: A crossover study.

    Science.gov (United States)

    Cunha, Raphael Martins; Vilaça-Alves, José; Noleto, Marcelo Vasconcelos; Silva, Juliana Sá; Costa, Andressa Moura; Silva, Christoffer Novais Farias; Póvoa, Thaís Inácio Rolim; Lehnen, Alexandre Machado

    2017-01-01

    Water aerobics exercise is widely recommended for elderly people. However, little is known about the acute effects on hemodynamic variables. Thus, we assessed the effects of a water aerobic session on blood pressure in hypertensive elderly women. Fifty hypertensive elderly women aged 67.8 ± 4.1 years, 1.5 ± 0.6 m high and BMI 28.6 ± 3.9 kg/m(2), participated in a crossover clinical trial. The experiment consisted of a 45-minute water aerobics session (70%-75% HRmax adjusted for the aquatic environment) (ES) and a control session (no exercise for 45 minutes) (CS). Heart rate was monitored using a heart rate monitor and systolic blood pressure (SBP) and diastolic (DBP) measurements were taken using a semi-automatic monitor before and immediately after the sessions, and at 10, 20 and 30 minutes thereafter. It was using a generalized estimating equation (GEE) with Bonferroni's post-hoc test (p exercise, BP declined in ES by a greater magnitude than in CS (SBP 7.5 mmHg, 6.2%, p = 0.005 and DBP 3.8 mmHg, 5.5%, p = 0.013). At 20 minutes after exercise and thereafter, SBP and DBP were similar in both ES and CS. In conclusion, BP returned to control levels within 10-20 minutes remaining unchanged until 30 minutes after exercise, and post-exercise hypotension was not observed. Besides, BP changed after exercise was a safe rise of small magnitude for hypertensive people.

  18. Coupling autotrophic sulfide mineral weathering with dolomite dissolution in a subglacial ecosystem

    Science.gov (United States)

    Boyd, E. S.; Hamilton, T. L.; Havig, J. R.; Lange, R.; Murter, E.; Skidmore, M. L.; Peters, J.; Shock, E.

    2013-12-01

    Evidence in the rock record suggests that glaciers have been present and covered a significant portion of the Earth's surface since the putative Mozaan Glaciation (circa 2.9 Ga) and were demonstrated recently to host active microbial communities that impact local and global biogeochemical cycles. In the present study, we applied a microcosm-based radioisotopic biocarbonate tracer approach to quantify rates of inorganic carbon assimilation in sediments sampled from beneath Robertson Glacier (RG), Alberta, Canada at 4°C. Rates of inorganic carbon assimilation were stimulated by the addition of ammonium and phosphate, suggesting that these nutrients might be of limited supply in the subglacial environment or, in the case of ammonia, might be serving as a source of reductant fueling inorganic carbon fixation. Geochemical analyses were used to assess the potential redox couples that might be fueling autotrophic activity. The difference in the concentration of sulfate (2.4 mM) in unamended microcosm fluids when compared to fluids sampled from killed controls following 180 days incubation suggests that inorganic carbon assimilation in microcosms is driven by microbial populations involved in the oxidation of mineral sulfides, most likely pyrite. Amendment of microcosms with 1 mM ammonia led to near stoichiometric production of nitrate (~890 μM) and lower production of sulfate (~1.5 mM), indicating that the enhanced activity observed in ammonia treated microcosms is likely due to the stimulation of autotrophic ammonia oxidizing populations. The isotopic composition of dissolved organic carbon in subglacial meltwaters ranged was -24.40 ‰ versus VPDB, which is consistent with a source for this organic carbon via the activity of autotrophs that use the Calvin cycle of inorganic carbon fixation. Quantification and sequencing of transcripts of Calvin cycle biomarker genes (ribulose-1,5 bisphosphate carboxylase/oxygenase, encoded by cbbL) suggest the presence of a ubiquitous

  19. Removal of aqueous nC60 fullerene from water by low pressure membrane filtration.

    Science.gov (United States)

    Floris, R; Nijmeijer, K; Cornelissen, E R

    2016-03-15

    The potential environmental and health risks of engineered nanoparticles such as buckminsterfullerene C60 in water require their removal during the production of drinking water. We present a study focusing on (i) the removal mechanism and (ii) the elucidation of the role of the membrane pore size during removal of nC60 fullerene nanoparticle suspensions in dead-end microfiltration and ultrafiltration mimicking separation in real industrial water treatment plants. Membranes were selected with pore sizes ranging from 18 nm to 500 nm to determine the significance of the nC60 to membrane pore size ratio and the adsorption affinity between nC60 and membrane material during filtration. Experiments were carried out with a dead-end bench-scale system operated at constant flux conditions including a hydraulic backwash cleaning procedure. nC60 nanoparticles can be efficiently removed by low pressure membrane technology with smaller and, unexpectedly, also by mostly similar or larger pores than the particle size, although the nC60 filtration behaviour appeared to be different. The nC60 size to membrane pore size ratio and the ratio of the cake-layer deposition resistance to the clean membrane resistance, both play an important role on the nC60 filtration behaviour and on the efficiency of the backwash procedure recovering the initial membrane filtration conditions. These results become specifically significant in the context of drinking water production, for which they provide relevant information for an accurate selection between membrane processes and operational parameters for the removal of nC60 in the drinking water treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Effect of High Hydrostatic Pressure Combined with Moderate Heat to Inactivate Pressure-Resistant Bacteria in Water-Boiled Salted Duck.

    Science.gov (United States)

    Ye, Keping; Feng, Yulin; Wang, Kai; Bai, Yun; Xu, Xinglian; Zhou, Guanghong

    2015-06-01

    The objective of this work was to study the effect of high hydrostatic pressure combined with moderate heat to inactivate pressure-resistant bacteria in water-boiled salted duck meat (WBSDM), and to establish suitable procedures to improve the quality of WBSDM. The conditions (300 MPa/60 °C, 400 MPa/60 °C, and 500 MPa/50 °C) effectively inactivated the pressure-resistant bacteria (Bacillus cereus and Staphylococcus warneri) in WBSDM. Although more pressure-resistant than S. warneri, the above treatment conditions inactivated B. cereus more than 10(7) CFU/mL in buffer, and more than 10(6) CFU/g in WBSDM, and did not cause any changes in color, texture, or moisture content of products. The interaction between pressure and temperature is a more significant factor than only pressure in inactivating both B. cereus and S. warneri, the treatment of WBSDM at 400 MPa/ 60 °C/ 10 min is the most practical condition for postprocess of WBSDM after cooking. © 2015 Institute of Food Technologists®

  1. Culturable bacteria in subglacial sediments and ice from two Southern Hemisphere glaciers.

    Science.gov (United States)

    Foght, J; Aislabie, J; Turner, S; Brown, C E; Ryburn, J; Saul, D J; Lawson, W

    2004-05-01

    Viable prokaryotes have been detected in basal sediments beneath the few Northern Hemisphere glaciers that have been sampled for microbial communities. However, parallel studies have not previously been conducted in the Southern Hemisphere, and subglacial environments in general are a new and underexplored niche for microbes. Unfrozen subglacial sediments and overlying glacier ice samples collected aseptically from the Fox Glacier and Franz Josef Glacier in the Southern Alps of New Zealand now have been shown to harbor viable microbial populations. Total direct counts of 2-7 x 10(6) cells g(-1) dry weight sediment were observed, whereas culturable aerobic heterotrophs ranged from 6-9 x 10(5) colony-forming units g(-1) dry weight. Viable counts in the glacier ice typically were 3-4 orders of magnitude smaller than in sediment. Nitrate-reducing and ferric iron-reducing bacteria were detected in sediment samples from both glaciers, but were few or below detection limits in the ice samples. Nitrogen-fixing bacteria were detected only in the Fox Glacier sediment. Restriction fragment analysis of 16S rDNA amplified from 37 pure cultures of aerobic heterotrophs capable of growth at 4 degrees C yielded 23 distinct groups, of which 11 were identified as beta-Proteobacteria. 16S rDNA sequences from representatives of these 11 groups were analyzed phylogenetically and shown to cluster with bacteria such as Polaromonas vacuolata and Rhodoferax antarcticus, or with clones obtained from permanently cold environments. Chemical analysis of sediment and ice samples revealed a dilute environment for microbial life. Nevertheless, both the sediment samples and one ice sample demonstrated substantial aerobic mineralization of 14C-acetate at 8 degrees C, indicating that sufficient nutrients and viable psychrotolerant microbes were present to support metabolism. Unfrozen subglacial sediments may represent a significant global reservoir of biological activity with the potential to

  2. Salinity of injection water and its impact on oil recovery absolute permeability, residual oil saturation, interfacial tension and capillary pressure

    OpenAIRE

    Mohammad Salehi, Mehdi; Omidvar, Pouria; Naeimi, Fatemeh

    2016-01-01

    Laboratory tests and field applications show that low-salinity water flooding could lead to significant reduction of residual oil saturation. There has been a growing interest with an increasing number of low-salinity water flooding studies. However, there are few quantitative studies on flow and transport behavior of low-salinity IOR processes. This paper presents laboratory investigation of the effect of salinity injection water on oil recovery, pressure drop, permeability, IFT and relat...

  3. Computational investigations of streamers in a single bubble suspended in distilled water under atmospheric pressure conditions

    Science.gov (United States)

    Sharma, Ashish; Levko, Dmitry; Raja, Laxminarayan

    2016-09-01

    We present a computational model of nanosecond streamers generated in helium bubbles immersed in distilled water at the atmospheric pressure conditions. The model is based on the self-consistent, multispecies and the continuum description of plasma and takes into account the presence of water vapor in the gas bubble for a more accurate description of the kinetics of the discharge. We find that the dynamic characteristics of the streamer discharge are completely different at low and high over voltages. We observe that the polarity of the trigger voltage has a substantial effect on initiation, transition and evolution stages of streamers with the volumetric distribution of species in the streamer channel much more uniform for negative trigger voltages due to the presence of multiple streamers. We also find that the presence of water vapor significantly influences the distribution of the dominant species in the streamer trail and has a profound effect on the flux of the dominant species to the bubble wall. The research reported in this publication was supported by Competitive Research Funding from King Abdullah University of Science and Technology (KAUST).

  4. Subacute blood pressure response in elderly hypertensive women after a water exercise session : a controlled clinical trial.

    Science.gov (United States)

    Cunha, Raphael M; Macedo, Camilla B; Araújo, Siomara F M; Santos, Jessica C; Borges, Viviane S; Soares, Ademar A; Ayres, Flávio; Pfrimer, Linda M

    2012-12-01

    There are few studies relating the practice of water exercises and blood pressure responses. The objective of this study was to evaluate the subacute blood pressure behaviour in elderly hypertensive women after a water exercise session. This was a controlled clinical trial, carried out with 16 hypertensive elderly women with the following characteristics (mean ± SD): age 66 ± 2.94 years, body weight 68.43 ± 12.08 kg, height 158 ± 5.34 cm and body mass index 27.32 ± 4.30 kg/m(2). The study occurred on 2 days, 48 hours apart, with an experimental protocol and a control protocol. The experimental protocol underwent a moderately intense and predominantly aerobic 40-minute session with water exercises for the upper and lower limbs. The control protocol did not enter the pool and did not exercise, but all other procedures were similar to those of the experimental protocol. The blood pressure measurements were performed at times before and every 10 minutes for 30 minutes after the protocols. Student's t-test was used to determine if the averages of the two samples were significantly different. Blood pressure increased significantly but not greatly after the water exercise session, but this did not happen with the control protocol. Systolic blood pressure in the experimental protocol decreased significantly only 30 minutes after the exercise session, which did not occur in the control protocol. Diastolic blood pressure, on the other hand, decreased significantly at minutes 10, 20 and 30. This also did not occur with the control protocol, but an intergroup analysis showed that diastolic blood pressure was similar for the two protocols. The results of this study show that a prescription of water exercises can be carried out in relative safety with this group of patients, and that systolic blood pressure tended to decrease, as shown by the measurement at minute 30.

  5. Modelling the coupling of flood discharge with glacier flow during jokulhlaups

    OpenAIRE

    Kingslake, J.; Ng, F.

    2013-01-01

    We explore a mathematical model that couples together a thermomechanically evolving subglacial channel, distributed cavity drainage, and basal sliding along a subglacial flood path fed by a jökulhlaup lake. It allows water transfer between channel and cavities and a migrating subglacial water divide or 'seal' to form between floods. Notably, it accounts for full coupling between the lake and subglacial drainage in terms of both discharge and pressure, unlike models that neglect the pressure c...

  6. Modelling the coupling of flood discharge with glacier flow during jökulhlaups

    OpenAIRE

    Kingslake, Jonathan; Ng, Felix

    2013-01-01

    We explore a mathematical model that couples together a thermomechanically evolving subglacial channel, distributed cavity drainage, and basal sliding along a subglacial flood path fed by a jökulhlaup lake. It allows water transfer between channel and cavities and a migrating subglacial water divide or 'seal' to form between floods. Notably, it accounts for full coupling between the lake and subglacial drainage in terms of both discharge and pressure, unlike models that neglect the pressure c...

  7. Thermal-Hydraulics analysis of pressurized water reactor core by using single heated channel model

    Directory of Open Access Journals (Sweden)

    Reza Akbari

    2017-08-01

    Full Text Available Thermal hydraulics of nuclear reactor as a basis of reactor safety has a very important role in reactor design and control. The thermal-hydraulic analysis provides input data to the reactor-physics analysis, whereas the latter gives information about the distribution of heat sources, which is needed to perform the thermal-hydraulic analysis. In this study single heated channel model as a very fast model for predicting thermal hydraulics behavior of pressurized water reactor core has been developed. For verifying the results of this model, we used RELAP5 code as US nuclear regulatory approved thermal hydraulics code. The results of developed single heated channel model have been checked with RELAP5 results for WWER-1000. This comparison shows the capability of single heated channel model for predicting thermal hydraulics behavior of reactor core.

  8. Pressurized hot water extraction of β-glucans from Cantharellus tubaeformis.

    Science.gov (United States)

    Rodríguez-Seoane, Paula; González-Muñoz, María Jesús; Falqué, Elena; Domínguez, Herminia

    2018-02-20

    Cantharellus tubaeformis was processed by pressurized hot water extraction (80-240 °C) with the aim of maximizing the extraction of oligomeric fractions, β-glucans and the in vitro antioxidant properties of the extracts. Increased severity of treatment enhanced the extraction yields above 62% at temperatures of 210 ºC or higher, corresponding to the maximum β-glucan yields. The highest antioxidant capacity was obtained at 170 ºC, although the highest content of phenolic compounds was obtained at the highest severity studied. This hydrothermal treatment can be considered a suitable process to obtain extracts with antioxidant properties and rich in β-glucans. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  9. Pressurized Hot Water Extraction of anthocyanins from red onion: A study on extraction and degradation rates.

    Science.gov (United States)

    Petersson, Erik V; Liu, Jiayin; Sjöberg, Per J R; Danielsson, Rolf; Turner, Charlotta

    2010-03-17

    Pressurized Hot Water Extraction (PHWE) is a quick, efficient and environmentally friendly technique for extractions. However, when using PHWE to extract thermally unstable analytes, extraction and degradation effects occur at the same time, and thereby compete. At first, the extraction effect dominates, but degradation effects soon take over. In this paper, extraction and degradation rates of anthocyanins from red onion were studied with experiments in a static batch reactor at 110 degrees C. A total extraction curve was calculated with data from the actual extraction and degradation curves, showing that more anthocyanins, 21-36% depending on the species, could be extracted if no degradation occurred, but then longer extraction times would be required than those needed to reach the peak level in the apparent extraction curves. The results give information about the different kinetic processes competing during an extraction procedure. Copyright 2010 Elsevier B.V. All rights reserved.

  10. Luminescence of mesoporous silicon powders treated by high-pressure water vapor annealing

    Science.gov (United States)

    Gelloz, Bernard; Loni, Armando; Canham, Leigh; Koshida, Nobuyoshi

    2012-07-01

    We have studied the photoluminescence of nanocrystalline silicon microparticle powders fabricated by fragmentation of PSi membranes. Several porosities were studied. Some powders have been subjected to further chemical etching in HF in order to reduce the size of the silicon skeleton and reach quantum sizes. High-pressure water vapor annealing was then used to enhance both the luminescence efficiency and stability. Two visible emission bands were observed. A red band characteristic of the emission of Si nanocrystals and a blue band related to localized centers in oxidized powders. The blue band included a long-lived component, with a lifetime exceeding 1 sec. Both emission bands depended strongly on the PSi initial porosity. The colors of the processed powders were tunable from brown to off-white, depending on the level of oxidation. The surface area and pore volume of some powders were also measured and discussed. The targeted applications are in cosmetics and medicine.

  11. Power level effects on thorium-based fuels in pressure-tube heavy water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Bromley, B.P.; Edwards, G.W.R., E-mail: blair.bromley@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada); Sambavalingam, P. [Univ. of Ontario Inst. of Technology, Oshawa, Ontario (Canada)

    2016-06-15

    Lattice and core physics modeling and calculations have been performed to quantify the impact of power/flux levels on the reactivity and achievable burnup for 35-element fuel bundles made with Pu/Th or U-233/Th. The fissile content in these bundles has been adjusted to produce on the order of 20 MWd/kg burnup in homogeneous cores in a 700 MWe-class pressure-tube heavy water reactor, operating on a once-through thorium cycle. Results demonstrate that the impact of the power/flux level is modest for Pu/Th fuels but significant for U-233/Th fuels. In particular, high power/flux reduces the breeding and burnup potential of U-233/Th fuels. Thus, there may be an incentive to operate reactors with U-233/Th fuels at a lower power density or to develop alternative refueling schemes that will lower the time-average specific power, thereby increasing burnup.(author)

  12. Pressure effect on the amide I frequency of the solvated {alpha}-helical structure in water

    Energy Technology Data Exchange (ETDEWEB)

    Takekiyo, T [Department of Applied Chemistry, National Defence Academy, 1-10-20 Hashirimizu, Yokosuka, Kanagawa, 239-8686 (Japan); Yoshimura, Y [Department of Applied Chemistry, National Defence Academy, 1-10-20 Hashirimizu, Yokosuka, Kanagawa, 239-8686 (Japan); Shimizu, A [Department of Environmental Engineering for Symbiosis Factory of Engineering, Soka University, 1-326 Tanjincho, Hachioji, Tokyo, 192-8577 (Japan); Koizumi, T [Department of Applied Chemistry, National Defence Academy, 1-10-20 Hashirimizu, Yokosuka, Kanagawa, 239-8686 (Japan); Kato, M [Department of Applied Chemistry, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga, 525-8577 (Japan); Taniguchi, Y [Department of Applied Chemistry, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga, 525-8577 (Japan)

    2007-10-24

    As a model system of the pressure dependence of the amide I mode of the solvated {alpha}-helical structure in a helical peptide, we have calculated the frequency shifts of the amide I modes as a function of the distance between trans-N-methylacetamide (t-NMA) dimer and a water molecule (d{sub C=O{center_dot}}{sub {center_dot}}{sub {center_dot}}{sub H-O}) by the density-functional theory (DFT) method at the B3LYP/6-31G++(d,p) level. Two amide I frequencies at 1652 and 1700 cm{sup -1} were observed under this calculation. The former is ascribed to the amide I mode forming the intermolecular hydrogen bond (H-bond) between t-NMA and H{sub 2}O in addition to the intermolecular H-bond in the t-NMA dimer. The latter is due to the amide I mode forming only the intermolecular H-bond in the t-NMA dimer. We have found that the amide I frequency at 1652 cm{sup -1} shifts to a lower frequency with decreasing d{sub C=O{center_dot}}{sub {center_dot}}{sub {center_dot}}{sub H-O}) (i.e., increasing pressure), whereas that at 1700 cm{sup -1} shifts to a higher frequency. The amide I frequency shift of 1652 cm{sup -1} is larger than that of 1700 cm{sup -1} by the intermolecular H-bond. Thus, our results clearly indicate that the pressure-induced amide I frequency shift of the solvated {alpha}-helical structure correlates with the change in d{sub C=O{center_dot}}{sub {center_dot}}{sub {center_dot}}{sub H-O})

  13. Effect Of Cuo-Distilled Water Based Nanofluids On Heat Transfer Characteristics And Pressure Drop Characteristics.

    Directory of Open Access Journals (Sweden)

    SANDEEP KUMAR

    2014-09-01

    Full Text Available In this paper, the heat transfer and pressure drop characteristics of the distilled water and the copper oxide-distilled water based nanofluid flowing in a horizontal circular pipe under constant heat flux condition are studied. Copper oxide nanoparticles of 40nm size are dispersed in distilled water using sodium dodecyl sulphate as surfactant and sonicated the nanofluid for three hour. Both surfactant and sonication increases the stability of the nanofluid. The nanofluids are made in three different concentration i.e. 0.1 Vol. %, 0.25 Vol. % and 0.50 Vol. %. The thermal conductivity is measured by KD2 PRO, density with pycnometer, viscosity with Brookfield LVDV-III rheometer. The results show that the thermal conductivity increases with both temperature and concentration. The viscosity and density increases with concentration but decreases with temperature. The specific heat is calculated by model and it decreases with concentration. The experimental local Nusselt number of distilled water is compared with local Nusselt number obtained by the well known shah equation for laminar flow under constant heat flux condition for validation of the experimental set up. The relative error is 4.48 % for the Reynolds number 750.9. The heat transfer coefficient increases with increase in both flow rate and concentration. It increases from 14.33 % to 46.1 % when the concentration is increased from 0.1 Vol. % to 0.5 Vol. % at 20 LPH flow rate. Friction factor decreases with increase in flow rate. It decreases 66.54 % when the flow rate increases from 10 LPH to 30 LPH for 0.1 Vol. %.

  14. Application of volume-retarded osmosis and low-pressure membrane hybrid process for water reclamation

    KAUST Repository

    Im, Sung-Ju

    2017-11-15

    A new concept of volume-retarded osmosis and low-pressure membrane (VRO-LPM) hybrid process was developed and evaluated for the first time in this study. Commercially available forward osmosis (FO) and ultrafiltration (UF) membranes were employed in a VRO-LPM hybrid process to overcome energy limitations of draw solution (DS) regeneration and production of permeate in the FO process. To evaluate its feasibility as a water reclamation process, and to optimize the operational conditions, cross-flow FO and dead-end mode UF processes were individually evaluated. For the FO process, a DS concentration of 0.15 g mL−1 of polysulfonate styrene (PSS) was determined to be optimal, having a high flux with a low reverse salt flux. The UF membrane with a molecular weight cut-off of 1 kDa was chosen for its high PSS rejection in the LPM process. As a single process, UF (LPM) exhibited a higher flux than FO, but this could be controlled by adjusting the effective membrane area of the FO and UF membranes in the VRO-LPM system. The VRO-LPM hybrid process only required a circulation pump for the FO process. This led to a decrease in the specific energy consumption of the VRO-LPM process for potable water production, that was similar to the single FO process. Therefore, the newly developed VRO-LPM hybrid process, with an appropriate DS selection, can be used as an energy efficient water production method, and can outperform conventional water reclamation processes.

  15. In-Vessel Melt Retention of Pressurized Water Reactors: Historical Review and Future Research Needs

    Directory of Open Access Journals (Sweden)

    Weimin Ma

    2016-03-01

    Full Text Available A historical review of in-vessel melt retention (IVR is given, which is a severe accident mitigation measure extensively applied in Generation III pressurized water reactors (PWRs. The idea of IVR actually originated from the back-fitting of the Generation II reactor Loviisa VVER-440 in order to cope with the core-melt risk. It was then employed in the new deigns such as Westinghouse AP1000, the Korean APR1400 as well as Chinese advanced PWR designs HPR1000 and CAP1400. The most influential phenomena on the IVR strategy are in-vessel core melt evolution, the heat fluxes imposed on the vessel by the molten core, and the external cooling of the reactor pressure vessel (RPV. For in-vessel melt evolution, past focus has only been placed on the melt pool convection in the lower plenum of the RPV; however, through our review and analysis, we believe that other in-vessel phenomena, including core degradation and relocation, debris formation, and coolability and melt pool formation, may all contribute to the final state of the melt pool and its thermal loads on the lower head. By looking into previous research on relevant topics, we aim to identify the missing pieces in the picture. Based on the state of the art, we conclude by proposing future research needs.

  16. The simulation of thermohydraulic phenomena in a pressurized water reactor primary loop

    Energy Technology Data Exchange (ETDEWEB)

    Popp, M

    1987-01-01

    Several important fluid flow and heat transfer phenomena essential to nuclear power reactor safety were investigated. Scaling and modeling laws for pressurized water reactors are reviewed and a new scaling approach focusing on the overall loop behavior is presented. Scaling criteria for one- and two-phase natural circulation are developed, as well as a simplified model describing the first phase of a small break loss of coolant accident. Reactor vessel vent valve effects are included in the analysis of steady one-phase natural circulation flow. Two new dimensionless numbers, which uniquely describe one-phase flow in natural circulation loops, were deduced and are discussed. A scaled model of the primary loop of a typical Babcock and Wilcox reactor was designed, built, and tested. The particular prototype modeled was the TMI unit 2 reactor. The electrically heated, stainless steel model operates at a maximum pressure of 300 psig and has a maximum heat input of 188 kW. The model is about 4 times smaller in height than the prototype reactor, with a nominal volume scale of 1:500. Experiments were conducted establishing subcooled natural circulation in the model loop. Both steady flow and power transients were investigated.

  17. Standard Master Matrix for Light-Water Reactor Pressure Vessel Surveillance Standards, E706(0)

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2002-01-01

    1.1 This master matrix standard describes a series of standard practices, guides, and methods for the prediction of neutron-induced changes in light-water reactor (LWR) pressure vessel (PV) and support structure steels throughout a pressure vessel's service life (Fig. 1). Some of these are existing ASTM standards, some are ASTM standards that have been modified, and some are proposed ASTM standards. General requirements of content and consistency are discussed in Section 6 . More detailed writers' and users' information, justification, and specific requirements for the nine practices, ten guides, and three methods are provided in Sections 3-5. Referenced documents are discussed in Section 2. The summary-type information that is provided in Sections 3 and 4 is essential for establishing proper understanding and communications between the writers and users of this set of matrix standards. It was extracted from the referenced documents, Section 2 and references (1-106) for use by individual writers and users. 1...

  18. Application of Genetic Algorithm methodologies in fuel bundle burnup optimization of Pressurized Heavy Water Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jayalal, M.L., E-mail: jayalal@igcar.gov.in [Electronics, Instrumentation and Radiological Safety Group (EIRSG), Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, Tamil Nadu (India); Ramachandran, Suja [Electronics, Instrumentation and Radiological Safety Group (EIRSG), Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, Tamil Nadu (India); Rathakrishnan, S. [Reactor Physics Section, Madras Atomic Power Station (MAPS), Kalpakkam, Tamil Nadu (India); Satya Murty, S.A.V. [Electronics, Instrumentation and Radiological Safety Group (EIRSG), Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, Tamil Nadu (India); Sai Baba, M. [Resources Management Group (RMG), Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, Tamil Nadu (India)

    2015-01-15

    Highlights: • We study and compare Genetic Algorithms (GA) in the fuel bundle burnup optimization of an Indian Pressurized Heavy Water Reactor (PHWR) of 220 MWe. • Two Genetic Algorithm methodologies namely, Penalty Functions based GA and Multi Objective GA are considered. • For the selected problem, Multi Objective GA performs better than Penalty Functions based GA. • In the present study, Multi Objective GA outperforms Penalty Functions based GA in convergence speed and better diversity in solutions. - Abstract: The work carried out as a part of application and comparison of GA techniques in nuclear reactor environment is presented in the study. The nuclear fuel management optimization problem selected for the study aims at arriving appropriate reference discharge burnup values for the two burnup zones of 220 MWe Pressurized Heavy Water Reactor (PHWR) core. Two Genetic Algorithm methodologies namely, Penalty Functions based GA and Multi Objective GA are applied in this study. The study reveals, for the selected problem of PHWR fuel bundle burnup optimization, Multi Objective GA is more suitable than Penalty Functions based GA in the two aspects considered: by way of producing diverse feasible solutions and the convergence speed being better, i.e. it is capable of generating more number of feasible solutions, from earlier generations. It is observed that for the selected problem, the Multi Objective GA is 25.0% faster than Penalty Functions based GA with respect to CPU time, for generating 80% of the population with feasible solutions. When average computational time of fixed generations are considered, Penalty Functions based GA is 44.5% faster than Multi Objective GA. In the overall performance, the convergence speed of Multi Objective GA surpasses the computational time advantage of Penalty Functions based GA. The ability of Multi Objective GA in producing more diverse feasible solutions is a desired feature of the problem selected, that helps the

  19. Drinking Water Sodium and Elevated Blood Pressure of Healthy Pregnant Women in Salinity-Affected Coastal Areas.

    Science.gov (United States)

    Scheelbeek, Pauline F D; Khan, Aneire E; Mojumder, Sontosh; Elliott, Paul; Vineis, Paolo

    2016-08-01

    Coastal areas in Southeast Asia are experiencing high sodium concentrations in drinking water sources that are commonly consumed by local populations. Salinity problems caused by episodic cyclones and subsequent seawater inundations are likely (partly) related to climate change and further exacerbated by changes in upstream river flow and local land-use activities. Dietary (food) sodium plays an important role in the global burden of hypertensive disease. It remains unknown, however, if sodium in drinking water-rather than food-has similar effects on blood pressure and disease risk. In this study, we examined the effect of drinking water sodium on blood pressure of pregnant women: increases in blood pressure in this group could severely affect maternal and fetal health. Data on blood pressure, drinking water source, and personal, lifestyle, and environmental confounders was obtained from 701 normotensive pregnant women residing in coastal Bangladesh. Generalized linear mixed regression models were used to investigate association of systolic and diastolic blood pressure of these-otherwise healthy-women with their water source. After adjustment for confounders, drinkers of tube well and pond water (high saline sources) were found to have significantly higher average systolic (+4.85 and +3.62 mm Hg) and diastolic (+2.30 and +1.72 mm Hg) blood pressures than rainwater drinkers. Drinking water salinity problems are expected to exacerbate in the future, putting millions of coastal people-including pregnant women-at increased risk of hypertension and associated diseases. There is an urgent need to further explore the health risks associated to this understudied environmental health problem and feasibility of possible adaptation strategies. © 2016 American Heart Association, Inc.

  20. Creep and stick-slip in subglacial granular beds forced by ocean tides

    DEFF Research Database (Denmark)

    Damsgaard, Anders; Egholm, David Lundbek; Beem, Lucas H.

    rearrangements of load-bearing force chains within the granular sediments drive the mechanical transitions. Cyclic variations in driving stresses or pore-water pressure, caused by ocean tides, give rise to strain-rate dependent creeping motion at stress levels below the point of failure, while disruption...

  1. Mean force potential of interaction between Na+ and Cl- ions in planar nanopores in contact with water under pressure

    Science.gov (United States)

    Shevkunov, S. V.

    2017-11-01

    The mean force potential (MFP) of interaction between counterions Na+ and Cl- in a planar nanopore with structureless hydrophobic walls is calculated via computer simulation under the condition that the nanopore is in contact with water at an external pressure that exceeds the saturation pressure but remains insufficient to fill the nanopore with water. For a nanopore with a liquid phase, the MFP dependence on the interionic distance indicates the dissociation of an ion pair into two hydrated ions in a nanopore that is not completely filled with water. Fluctuations in the number of water molecules drawn into the interionic space decisively influence the dissociation. The attraction between counterions, averaged over thermal fluctuations, depends largely on the pore width and grows as the shielding of the ions' electric field by water molecules in a narrow pore diminishes. The contributions from energy and entropy to the free energy of hydration are analyzed.

  2. Pressure field induced in the water column by acoustic-gravity waves generated from sea bottom motion

    Science.gov (United States)

    Oliveira, Tiago C. A.; Kadri, Usama

    2016-10-01

    An uplift of the ocean bottom caused by a submarine earthquake can trigger acoustic-gravity waves that travel at near the speed of sound in water and thus may act as early tsunami precursors. We study the spatiotemporal evolution of the pressure field induced by acoustic-gravity modes during submarine earthquakes, analytically. We show that these modes may all induce comparable temporal variations in pressure at different water depths in regions far from the epicenter, though the pressure field depends on the presence of a leading acoustic-gravity wave mode. Practically, this can assist in the implementation of an early tsunami detection system by identifying the pressure and frequency ranges of measurement equipment and appropriate installation locations.

  3. Effect of administration of water enriched in O2 by injection or electrolysis on transcutaneous oxygen pressure in anesthetized pigs.

    Science.gov (United States)

    Charton, Antoine; Péronnet, François; Doutreleau, Stephane; Lonsdorfer, Evelyne; Klein, Alexis; Jimenez, Liliana; Geny, Bernard; Diemunsch, Pierre; Richard, Ruddy

    2014-01-01

    Oral administration of oxygenated water has been shown to improve blood oxygenation and could be an alternate way for oxygen (O2) supply. In this experiment, tissue oxygenation was compared in anesthetized pigs receiving a placebo or water enriched in O2 by injection or a new electrolytic process. Forty-two pigs randomized in three groups received either mineral water as placebo or water enriched in O2 by injection or the electrolytic process (10 mL/kg in the stomach). Hemodynamic parameters, partial pressure of oxygen in the arterial blood (PaO2), skin blood flow, and tissue oxygenation (transcutaneous oxygen pressure, or TcPO2) were monitored during 90 minutes of general anesthesia. Absorption and tissue distribution of the three waters administered were assessed using dilution of deuterium oxide. Mean arterial pressure, heart rate, PaO2, arteriovenous oxygen difference, and water absorption from the gut were not significantly different among the three groups. The deuterium to protium ratio was also similar in the plasma, skin, and muscle at the end of the protocol. Skin blood flow decreased in the three groups. TcPO2 slowly decreased over the last 60 minutes of the experiment in the three groups, but when compared to the control group, the values remained significantly higher in animals that received the water enriched in O2 by electrolysis. In this protocol, water enriched in O2 by electrolysis lessened the decline of peripheral tissue oxygenation. This observation is compatible with the claim that the electrolytic process generates water clathrates which trap O2 and facilitate O2 diffusion along pressure gradients. Potential applications of O2-enriched water include an alternate method of oxygen supply.

  4. Effect of administration of water enriched in O2 by injection or electrolysis on transcutaneous oxygen pressure in anesthetized pigs

    Science.gov (United States)

    Charton, Antoine; Péronnet, François; Doutreleau, Stephane; Lonsdorfer, Evelyne; Klein, Alexis; Jimenez, Liliana; Geny, Bernard; Diemunsch, Pierre; Richard, Ruddy

    2014-01-01

    Background Oral administration of oxygenated water has been shown to improve blood oxygenation and could be an alternate way for oxygen (O2) supply. In this experiment, tissue oxygenation was compared in anesthetized pigs receiving a placebo or water enriched in O2 by injection or a new electrolytic process. Methods Forty-two pigs randomized in three groups received either mineral water as placebo or water enriched in O2 by injection or the electrolytic process (10 mL/kg in the stomach). Hemodynamic parameters, partial pressure of oxygen in the arterial blood (PaO2), skin blood flow, and tissue oxygenation (transcutaneous oxygen pressure, or TcPO2) were monitored during 90 minutes of general anesthesia. Absorption and tissue distribution of the three waters administered were assessed using dilution of deuterium oxide. Results Mean arterial pressure, heart rate, PaO2, arteriovenous oxygen difference, and water absorption from the gut were not significantly different among the three groups. The deuterium to protium ratio was also similar in the plasma, skin, and muscle at the end of the protocol. Skin blood flow decreased in the three groups. TcPO2 slowly decreased over the last 60 minutes of the experiment in the three groups, but when compared to the control group, the values remained significantly higher in animals that received the water enriched in O2 by electrolysis. Conclusions In this protocol, water enriched in O2 by electrolysis lessened the decline of peripheral tissue oxygenation. This observation is compatible with the claim that the electrolytic process generates water clathrates which trap O2 and facilitate O2 diffusion along pressure gradients. Potential applications of O2-enriched water include an alternate method of oxygen supply. PMID:25210438

  5. Synergetic effect of temperature and pressure on energetic and structural characteristics of {ZIF-8 + water} molecular spring

    Science.gov (United States)

    Grosu, Ya.; Renaudin, G.; Eroshenko, V.; Nedelec, J.-M.; Grolier, J.-P. E.

    2015-05-01

    Metal-organic frameworks (MOFs) and particularly their subclass - Zeolite Imidazolate Frameworks (ZIFs) - are used for a variety of applications including particularly energy storage. Highly porous MOFs mixed with non-wetting liquids can be used to form molecular springs (MS) for efficient mechanical and thermal energy storage/transformation. In this paper by means of high-pressure calorimetry the energetic characteristics of {ZIF-8 + water} MS were investigated in wide temperature and pressure ranges. Unexpectedly XRD measurements show that the concomitant effects of temperature and pressure on {ZIF-8 + water} MS leads to an irreversible change of the ZIF-8 structure, transforming its symmetry from cubic to orthorhombic. Whereas, previous studies have demonstrated the stability of ZIF-8 under either high pressure or high temperature.Metal-organic frameworks (MOFs) and particularly their subclass - Zeolite Imidazolate Frameworks (ZIFs) - are used for a variety of applications including particularly energy storage. Highly porous MOFs mixed with non-wetting liquids can be used to form molecular springs (MS) for efficient mechanical and thermal energy storage/transformation. In this paper by means of high-pressure calorimetry the energetic characteristics of {ZIF-8 + water} MS were investigated in wide temperature and pressure ranges. Unexpectedly XRD measurements show that the concomitant effects of temperature and pressure on {ZIF-8 + water} MS leads to an irreversible change of the ZIF-8 structure, transforming its symmetry from cubic to orthorhombic. Whereas, previous studies have demonstrated the stability of ZIF-8 under either high pressure or high temperature. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01340b

  6. Characterization of the physicochemical properties of phospholipid vesicles prepared in CO2/water systems at high pressure.

    Science.gov (United States)

    Nakamura, Hidemi; Taguchi, Shogo; Suga, Keishi; Hayashi, Keita; Jung, Ho-Sup; Umakoshi, Hiroshi

    2015-09-21

    Phospholipid vesicles were prepared by the nonsolvent method using high-pressure CO2/water systems. The membrane properties of vesicles prepared at different pressures and temperatures were mainly characterized based on analysis of the membrane fluidity and membrane polarity, using the fluorescent probes 1,6-diphenyl-1,3,5-hexatriene and 6-dodecanoyl-N,N-dimethyl-2-naphthylamine, respectively. The CO2(liquid)/water(liquid) and the CO2(supercritical)/water(liquid) two-phase (heterogeneous) systems resulted in the formation of vesicles with high yield (ca. 85%-88%). The membrane fluidity and polarity of the vesicles were similar to those of liposomes prepared by the conventional method. It is suggested that high-pressure CO2 can be used to form an appropriate hydrophobic-hydrophilic interface where phospholipid molecules as a self-assembled membrane.

  7. Experimental study on the influence of clamping pressure on proton exchange membrane water electrolyzer (PEMWE) cell’s characteristics

    DEFF Research Database (Denmark)

    Al Shakhshir, Saher; Cui, Xiaoti; Kær, Søren Knudsen

    at lower clamping pressure values at the same temperature and current density. Furthermore, early results have not shown any significant change in the amount of hydrogen crossing-over from cathode to anode and water from anode to cathode. This might be attributed to the membrane properties which might....... PEMWE cell splits water into hydrogen and oxygen when an electric current is passed through it. Electrical current forces the positively charged ions to migrate to negatively charged cathode, where hydrogen is reduced. Meanwhile, oxygen is produced at the anode side electrode and escapes as a gas...... with the circulating water. In the recent few years, PEMWE’s R&D has inched towards; operating conditions; such as increased operating temperature and cathode-anode high differential pressure operation, flow field design, stack development, and numerical modelling [2,3]. In this work the effect of clamping pressure...

  8. Light Water Reactor Sustainability Program: Analysis of Pressurized Water Reactor Station Blackout Caused by External Flooding Using the RISMC Toolkit

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Curtis [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Prescott, Steven [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alfonsi, Andrea [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cogliati, Joshua [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kinoshita, Robert [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-08-01

    The existing fleet of nuclear power plants is in the process of extending its lifetime and increasing the power generated from these plants via power uprates. In order to evaluate the impact of these factors on the safety of the plant, the Risk Informed Safety Margin Characterization (RISMC) project aims to provide insight to decision makers through a series of simulations of the plant dynamics for different initial conditions (e.g., probabilistic analysis and uncertainty quantification). This report focuses, in particular, on the application of a RISMC detailed demonstration case study for an emergent issue using the RAVEN and RELAP-7 tools. This case study looks at the impact of a couple of challenges to a hypothetical pressurized water reactor, including: (1) a power uprate, (2) a potential loss of off-site power followed by the possible loss of all diesel generators (i.e., a station black-out event), (3) and earthquake induces station-blackout, and (4) a potential earthquake induced tsunami flood. The analysis is performed by using a set of codes: a thermal-hydraulic code (RELAP-7), a flooding simulation tool (NEUTRINO) and a stochastic analysis tool (RAVEN) – these are currently under development at the Idaho National Laboratory.

  9. A numerical and experimental study of oblique impact of ultra-high pressure abrasive water jet

    Directory of Open Access Journals (Sweden)

    Can Kang

    2016-03-01

    Full Text Available An investigation of the abrasive water jet with an emphasis on the oblique impact of abrasive particles on the target plate is performed. Ultra-high jet pressure necessitates a close examination of the phenomena featured by small spatial and temporal scales. The effect of oblique impact is assessed from both numerical and practical aspects. Numerical simulation, implemented using the commercial code LS-DYNA, allows a detailed inspection of transient stress wave propagation inside the target plate. And impact experiments facilitate a qualitative description of resultant footprints of oblique water jet. Different incident angles of abrasive particles are adopted and a comparison is thereby unfolded. The results indicate that rebound, embedding, and penetration of single abrasive particle are three representative final operation states. Adjacent to the abrasive particle, the response of the target plate to oblique impact is reflected by von Mises stress distribution and plate deformation as well. Oblique impact arouses non-symmetrical stress wave distributions and distinct unbalanced node displacements at the two sides of the abrasive particle. As for the target plate, global surface morphology is in accordance with predicted effects. The most favorable surface roughness is not associated with vertical impact, and it hinges upon the selection of standoff distance. Furthermore, variation of surface roughness with incident angle is not monotonous.

  10. Spectrochemical analysis of Cs in water and soil using low pressure laser induced breakdown spectroscopy

    Science.gov (United States)

    Ramli, Muliadi; Khumaeni, Ali; Kurniawan, Koo Hendrik; Tjia, May On; Kagawa, Kiichiro

    2017-06-01

    An experimental study has been conducted for the practical and in situ application of laser-induced breakdown spectroscopy (LIBS) for the detection of Cs pollutant in water and soil in the nearby area of Fukushima Nuclear Power Station. The spectrochemical measurements were carried out by means of 355 nm Nd-YAG laser with N2 and He ambient gases at atmospheric and low pressures. The soil samples were prepared by pelletizing the mixtures of 80% soil and 20% KBr while the aqueous samples were prepared as thin films electro deposited on indium tin oxide (ITO) glass. The resulted emission spectra using 0.5 kPa N2 ambient gas shows the minimum detectable Cs concentration of 0.2 ppm and 0.3 ppm in the water and soil samples, respectively. The result of this experiment has thus demonstrated the viability of the LIBS equipment employed here as a more practical, in-situ and even mobile alternative to the standard use of gamma-ray spectroscopy using germanium detector.

  11. Modeling of a Flooding Induced Station Blackout for a Pressurized Water Reactor Using the RISMC Toolkit

    Energy Technology Data Exchange (ETDEWEB)

    Mandelli, Diego; Prescott, Steven R; Smith, Curtis L; Alfonsi, Andrea; Rabiti, Cristian; Cogliati, Joshua J; Kinoshita, Robert A

    2011-07-01

    In the Risk Informed Safety Margin Characterization (RISMC) approach we want to understand not just the frequency of an event like core damage, but how close we are (or are not) to key safety-related events and how might we increase our safety margins. The RISMC Pathway uses the probabilistic margin approach to quantify impacts to reliability and safety by coupling both probabilistic (via stochastic simulation) and mechanistic (via physics models) approaches. This coupling takes place through the interchange of physical parameters and operational or accident scenarios. In this paper we apply the RISMC approach to evaluate the impact of a power uprate on a pressurized water reactor (PWR) for a tsunami-induced flooding test case. This analysis is performed using the RISMC toolkit: RELAP-7 and RAVEN codes. RELAP-7 is the new generation of system analysis codes that is responsible for simulating the thermal-hydraulic dynamics of PWR and boiling water reactor systems. RAVEN has two capabilities: to act as a controller of the RELAP-7 simulation (e.g., system activation) and to perform statistical analyses (e.g., run multiple RELAP-7 simulations where sequencing/timing of events have been changed according to a set of stochastic distributions). By using the RISMC toolkit, we can evaluate how power uprate affects the system recovery measures needed to avoid core damage after the PWR lost all available AC power by a tsunami induced flooding. The simulation of the actual flooding is performed by using a smooth particle hydrodynamics code: NEUTRINO.

  12. A Tilt, Soil Moisture, and Pore Water Pressure Sensor System for Slope Monitoring Applications

    Directory of Open Access Journals (Sweden)

    Rosanno de Dios

    2009-06-01

    Full Text Available This paper describes the design, implementation and characterization of a sensor network intended for monitoring of slope deformation and potential failures. The sensor network system consists of a tilt and moisture sensor column, a pore water pressure sensor column and a personal computer for data storage and processing. The tilt sensor column consists of several pipe segments containing tri-axial accelerometers and signal processing electronics. Each segment is joined together by flexible joints to allow for the column to deform and subsequently track underground movement. Capacitive-type sensors for soil moisture measurement are also included in the sensor column, which are used to measure the soil moisture at different depths. The measurements at each segment are transferred via a Controller Area Network (CAN bus, where the CAN master node is located at the top of the column above ground. The CAN master node transmits the collected data from the slave nodes via a wireless connection to a personal computer that performs data storage, processing and display via a Python-based graphical user interface (GUI. The entire system was deployed and characterized on a small-scale slope model. Slope failure was induced via water seepage and the system was demonstrated to ably measure the inclination and soil moisture content throughout the landslide event.

  13. Impact of continuous positive airway pressure on the pulmonary changes promoted by immersion in water

    Science.gov (United States)

    Rizzetti, Danize Aparecida; Quadros, Janayna Rodembuch Borba; Ribeiro, Bruna Esmerio; Callegaro, Letícia; Veppo, Aline Arebalo; Wiggers, Giulia Alessandra; Peçanha, Franck Maciel

    2017-01-01

    ABSTRACT Objective: To determine whether different levels of CPAP improve the lung volumes and capacities of healthy subjects immersed in water. Methods: This was a randomized clinical trial, conducted between April and June of 2016, involving healthy female volunteers who were using oral contraceptives. Three 20-min immersion protocols were applied: control (no CPAP); CPAP5 (CPAP at 5 cmH2O); and CPAP10 (CPAP at 10 cmH2O). We evaluated HR, SpO2, FVC, FEV1, the FEV1/FVC ratio, peak expiratory flow rate (PEFR), and FEF25-75%) at three time points: pre-immersion; 10 min after immersion; and 10 min after the end of each protocol. Results: We evaluated 13 healthy volunteers. The CPAP10 protocol reversed the restrictive pattern of lung function induced by immersion in water, maintaining pulmonary volumes and capacities for a longer period than did the CPAP5 protocol. Conclusions: When the hemodynamic change causing a persistent lung disorder, only the application of higher positive pressures is effective in maintaining long-term improvements in the pulmonary profile. PMID:29340488

  14. Flow patterns and pressure drop in air/water two-phase flow in horizontal helicoidal pipes

    Energy Technology Data Exchange (ETDEWEB)

    Awwad, A.; Xin, R.C.; Dong, Z.F.; Ebadian, M.A. [Florida International Univ., Miami, FL (United States). Dept. of Mechanical Engineering; Soliman, H.M. [Univ. of Manitoba, Winnipeg, Manitoba (Canada). Dept. of Mechanical Engineering

    1995-12-01

    An experimental investigation is conducted for air/water two-phase flow in horizontal helicoidal pipes. The helicoidal pipes are constructed of 25.4 mm I.D. Tygon tubing wrapped around cylindrical concrete forms with outside diameters of 62 cm and 124 cm. The helix angles of the helicoidal pipes vary from 1 to 20 deg. The experiments are performed for superficial water velocity in a range of U{sub L} = 0.008 {approximately} 2.2 m/s and for superficial air velocity in a range of U{sub G} = 0.2 {approximately} 50 m/s. The flow patterns are discerned and recorded photographically. The pressure drop of the air/water two-phase flow in the coils is measured and the Lockhart-Martinelli approach is used to analyze the data. The results are presented in the form of frictional pressure drop multipliers versus the Lockhart-Martinelli parameter. It was found that the flow patterns differ greatly from those of the straight pipe, and that the frictional pressure drop multipliers depend on both the Lockhart-Martinelli parameter and the flow rates. The correlation of the frictional pressure drop has been provided based on the current data. Furthermore, it was also found that the helix angle of the helicoidal pipe had almost no effect on the air/water two-phase flow pressure drop in the present experimental ranges.

  15. Effect of tender coconut water on systolic and diastolic blood pressure in prehypertensive women

    Directory of Open Access Journals (Sweden)

    Farapti Farapti

    2014-02-01

    . Dietary intakes of high potassium will decrease blood pressure (BP. Tender coconut water (TCW is a typical drink high in potassium. This study aimed to investigate the effect of TCW on BP in female teachers and employees prehypertension. Methods: The research was a parallel single blind randomized clinical trial. A total of 32 female prehypertension subjects aged 25-44 years. The subjects were selected using certain criteria and randomly allocated to one of two groups using block randomized, 16 subjects each. The treatment group received TCW 300 ml twice daily for 14 days and nutritional counseling, and the control group received water 300 ml twice daily for 14 days and nutritional counseling. Assessment of BP was done on day 0, day 8, and day 15. Statistical analysis were done using t-test and Mann-Whitney test. Results: Mean dietary intakes of potassium were 1420.28±405.54 mg/day or 30.22±8.63% compared to Recommended Dietary Allowance (RDA. During treatment period, potassium intake increased significantly in the treatment group. There were decreased BP in both groups, which were greater in the treatment group, but not statistically significant different (P > 0.05. The mean decrease of systolic BP was significant in treatment group (P = 0.031, meanwhile the mean decrease of diastolic BP was not significant (P=0.134. Conclusion: Tender coconut water 300 ml twice daily for 14 consecutive days has tendency to decrease systolic BP, but not diastolic blood pressure. (Health Science Indones 2013;2: 64-8Key words: coconut water, systolic and diastolic blood pressure

  16. Evaluation of Very Low Pressure Sprinkler Irrigation and Reservoir Tillage for Efficient Use of Water and Energy : Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    Kincaid, Dennis C.

    1987-03-01

    Two types of very low pressure devices were tested, spray nozzles and furrow drops (bubblers). For minimizing spray loss and maintaining uniformity, optimum conditions for spray heads are elevation about 6 feet, spacing 8 to 9 feet and pressure 15 to 20 psi. Use of furrow bubblers is not recommended for most regional conditions. Reservoir tillage with very low pressure systems reduces runoff on sloping fields while maintaining or slightly increasing yield. The total amount of water applied is slightly less because of reduction in spray loss. Effectiveness of reservoir tillage depends on the reservoir storing water until it infiltrates. Failure of the reservoirs during the season may result in increased runoff and erosion. Pressure regulators tested are adequate for their intended use. The uniformity of application using low pressure components was comparable to that of high pressure systems. Energy saving scan result from both low operating pressure and better application efficiency, but the relative importance of these two factors depends on individual circumstances. Payback times for some example systems are four years or less.

  17. DEVELOPMENT OF A SIPHON SYSTEM WITH POROUS TUBES FOR MAINTAINING A CONSTANT NEGATIVE WATER PRESSURE IN A ROOTING MATRIX

    OpenAIRE

    Tibbitts, T. W.; Frank, T.

    1995-01-01

    A reliable and effective water and nutrient delivery system with porous tubes has been developed for growing plants at a controllable, constant, negative water pressure. Multiple porous stainless steel tubes were positioned 4cm apart in a shallow tray (44cm long, 32cm wide and 8cm deep), and then covered with a 4cm layer of fine medium (≤1mm in diameter). Nutrient solution was recirculated through the porous tubes under a negative pressure maintained with a siphoning procedure. A range of ...

  18. Response of salt structures to ice-sheet loading: implications for ice-marginal and subglacial processes

    Science.gov (United States)

    Lang, Jörg; Hampel, Andrea; Brandes, Christian; Winsemann, Jutta

    2014-10-01

    During the past decades the effect of glacioisostatic adjustment has received much attention. However, the response of salt structures to ice-sheet loading and unloading is poorly understood. Our study aims to test conceptual models of the interaction between ice-sheet loading and salt structures by finite-element modelling. The results are discussed with regard to their implications for ice-marginal and subglacial processes. Our models consist of 2D plane-strain cross-sections, which represent simplified geological cross-sections from the Central European Basin System. The model layers represent (i) sedimentary rocks of elastoplastic rheology, (ii) a viscoelastic diapir and layer of salt and (iii) an elastoplastic basement. On top of the model, a temporarily variable pressure simulates the advance and retreat of an ice sheet. The durations of the individual loading phases were defined to resemble the durations of the Pleistocene ice advances in northern central Europe. The geometry and rheology of the model layers and the magnitude, spatial distribution and timing of ice-sheet loading were systematically varied to detect the controlling factors. All simulations indicate that salt structures respond to ice-sheet loading. An ice advance towards the diapir causes salt flow from the source layer below the ice sheet towards the diapir, resulting in an uplift of up to +4 m. The diapir continues to rise as long as the load is applied to the source layer but not to the crest of the diapir. When the diapir is transgressed by the ice sheet the diapir is pushed down (up to -36 m) as long as load is applied to the crest of the diapir. During and after ice unloading large parts of the displacement are compensated by a reversal of the salt flow. Plastic deformation of the overburden is restricted to the area immediately above the salt diapir. The displacements after unloading range between -3.1 and +2.7 m. Larger displacements are observed in models with deep-rooted diapirs

  19. Pressure monitoring and characterization of external sources of contamination at the site of the payment drinking water epidemiological studies.

    Science.gov (United States)

    Besner, Marie-Claude; Broséus, Romain; Lavoie, Jean; Giovanni, George Di; Payment, Pierre; Prévost, Michèle

    2010-01-01

    The 1990s epidemiological studies by Payment and colleagues suggested that an increase in gastrointestinal illnesses observed in the population consuming tap water from a system meeting all water quality regulations might be associated with distribution system deficiencies. In the current study, the vulnerability of this distribution system to microbial intrusion was assessed by characterizing potential sources of contamination near pipelines and monitoring the frequency and magnitude of negative pressures. Bacterial indicators of fecal contamination were recovered more frequently in the water from flooded air-valve vaults than in the soil or water from pipe trenches. The level of fecal contamination in these various sources was more similar to levels from river water rather than wastewater. Because of its configuration, this distribution system is vulnerable to negative pressures when pressure values out of the treatment plant reach or drop below 172 kPa (25 psi), which occurred nine times during a monitoring period of 17 months. The results from this investigation suggest that this distribution system is vulnerable to contamination by intrusion. Comparison of the frequency of occurrence of negative pressure events and repair rates with data from other distribution systems suggests that the system studied by Payment and colleagues is not atypical.

  20. Multiple-pressure-tapped core holder combined with X-ray computed tomography scanning for gas-water permeability measurements of methane-hydrate-bearing sediments.

    Science.gov (United States)

    Konno, Yoshihiro; Jin, Yusuke; Uchiumi, Takashi; Nagao, Jiro

    2013-06-01

    We present a novel setup for measuring the effective gas-water permeability of methane-hydrate-bearing sediments. We developed a core holder with multiple pressure taps for measuring the pressure gradient of the gas and water phases. The gas-water flooding process was simultaneously detected using an X-ray computed tomography scanner. We successfully measured the effective gas-water permeability of an artificial sandy core with methane hydrate during the gas-water flooding test.

  1. Delimitation of areas under the real pressure from agricultural activities due to nitrate water pollution in Poland

    Science.gov (United States)

    Wozniak, E.; Nasilowska, S.; Jarocinska, A.; Igras, J.; Stolarska, M.; Bernoussi, A. S.; Karaczun, Z.

    2012-04-01

    The aim of the performed research was to determine catchments under the nitrogen pressure in Poland in period of 2007-2010. National Water Management Authority in Poland uses the elaborated methodology to fulfil requirements of Nitrate Directive and Water Framework Directive. Multicriteria GIS analysis was conducted on the base on various types of environmental data, maps and remote sensing products. Final model of real agricultural pressure was made using two components: (i) potential pressure connected with agriculture (ii) the vulnerability of the area. The agricultural pressure was calculated using the amount of nitrogen in fertilizers and the amount of nitrogen produced by animal breeding. The animal pressure was based on the information about the number of bred animals of each species for communes in Poland. The spatial distribution of vegetation pressure was calculated using kriging for the whole country base on the information about 5000 points with the amount of nitrogen dose in fertilizers. The vulnerability model was elaborated only for arable lands. It was based on the probability of the precipitation penetration to the ground water and runoff to surface waters. Catchment, Hydrogeological, Soil, Relief or Land Cover maps allowed taking into account constant environmental conditions. Additionally information about precipitation for each day of analysis and evapotranspiration for every 16-day period (calculated from satellite images) were used to present influence of meteorological condition on vulnerability of the terrain. The risk model is the sum of the vulnerability model and the agricultural pressure model. In order to check the accuracy of the elaborated model, the authors compared the results with the eutrophication measurements. The model accuracy is from 85,3% to 91,3%.

  2. Geochemical Processes Leading to the Precipitation of Subglacial Carbonate Crusts at Bossons Glacier, Mont Blanc Massif (French Alps

    Directory of Open Access Journals (Sweden)

    Christophe Thomazo

    2017-09-01

    Full Text Available Cold climate carbonates can be used as paleoclimatic proxies. The mineralogy and isotopic composition of subglacially precipitated carbonate crusts (SPCCs provide insights into the subglacial conditions and processes occurring at the meltwater-basement rock interface of glaciers. This study documents such crusts discovered on the lee side of a gneissic roche moutonnée at the terminus of the Bossons glacier in the Mont Blanc Massif area (France. The geological context and mineralogical investigations suggest that the Ca used for the precipitation of large crystals of radial fibrous sparite observed in these crusts originated from subglacial chemical weathering of Ca-bearing minerals of the local bedrock (plagioclase and amphibole. Measurements of the carbon and oxygen isotope compositions in the crusts indicate precipitation at, or near to, equilibrium with the basal meltwater under open system conditions during refreezing processes. The homogeneous and low carbonate δ13C values (ca. −11.3‰ imply a large contribution of soil organic carbon to the Bossons subglacial meltwater carbon reservoir at the time of deposition. In addition, organic remains trapped within the SPCCs give an age of deposition around 6,500 years cal BP suggesting that the Mid-Holocene climatic and pedological optima are archived in the Bossons glacier carbonate crusts.

  3. Subglacial bed conditions during Late Pleistocene glaciations and their impact on ice dynamics in the southern North Sea

    NARCIS (Netherlands)

    Passchier, S.; Laban, C.; Mesdag, C.S.; Rijsdijk, K.F.

    2010-01-01

    Changes in subglacial bed conditions through multiple glaciations and their effect on ice dynamics are addressed through an analysis of glacigenic sequences in the Upper Pleistocene stratigraphy of the southern North Sea basin. During Elsterian (MIS 12) ice growth, till deposition was subdued when

  4. Layers of air in the water beneath the floating fern Salvinia are exposed to fluctuations in pressure.

    Science.gov (United States)

    Mayser, Matthias J; Barthlott, Wilhelm

    2014-12-01

    Superhydrophobic, hierarchically structured, technical surfaces (Lotus-effect) are of high scientific and economic interest because of their remarkable properties. Recently, the immense potential of air-retaining superhydrophobic surfaces, for example, for low-friction transport of fluids and drag-reducing coatings of ships has begun to be explored. A major problem of superhydrophobic surfaces mimicking the Lotus-effect is the limited persistence of the air retained, especially under rough conditions of flow. However, there are a variety of floating or diving plant and animal species that possess air-retaining surfaces optimized for durable water-repellency (Salvinia-effect). Especially floating ferns of the genus Salvinia have evolved superhydrophobic surfaces capable of maintaining layers of air for months. Apart from maintaining stability under water, the layer of air has to withstand the stresses of water pressure (up to 2.5 bars). Both of these aspects have an application to create permanent air layers on ships' hulls. We investigated the effect of pressure on air layers in a pressure cell and exposed the air layer to pressures of up to 6 bars. We investigated the suppression of the air layer at increasing pressures as well as its restoration during decreases in pressure. Three of the four examined Salvinia species are capable of maintaining air layers at pressures relevant to the conditions applying to ships' hulls. High volumes of air per surface area are advantageous for retaining at least a partial Cassie-Baxter-state under pressure, which also helps in restoring the air layer after depressurization. Closed-loop structures such as the baskets at the top of the "egg-beater hairs" (see main text) also help return the air layer to its original level at the tip of the hairs by trapping air bubbles. © The Author 2014. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions

  5. Computational fluid dynamics (CFD) round robin benchmark for a pressurized water reactor (PWR) rod bundle

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Shin K., E-mail: paengki1@tamu.edu; Hassan, Yassin A.

    2016-05-15

    Highlights: • The capabilities of steady RANS models were directly assessed for full axial scale experiment. • The importance of mesh and conjugate heat transfer was reaffirmed. • The rod inner-surface temperature was directly compared. • The steady RANS calculations showed a limitation in the prediction of circumferential distribution of the rod surface temperature. - Abstract: This study examined the capabilities and limitations of steady Reynolds-Averaged Navier–Stokes (RANS) approach for pressurized water reactor (PWR) rod bundle problems, based on the round robin benchmark of computational fluid dynamics (CFD) codes against the NESTOR experiment for a 5 × 5 rod bundle with typical split-type mixing vane grids (MVGs). The round robin exercise against the high-fidelity, broad-range (covering multi-spans and entire lateral domain) NESTOR experimental data for both the flow field and the rod temperatures enabled us to obtain important insights into CFD prediction and validation for the split-type MVG PWR rod bundle problem. It was found that the steady RANS turbulence models with wall function could reasonably predict two key variables for a rod bundle problem – grid span pressure loss and the rod surface temperature – once mesh (type, resolution, and configuration) was suitable and conjugate heat transfer was properly considered. However, they over-predicted the magnitude of the circumferential variation of the rod surface temperature and could not capture its peak azimuthal locations for a central rod in the wake of the MVG. These discrepancies in the rod surface temperature were probably because the steady RANS approach could not capture unsteady, large-scale cross-flow fluctuations and qualitative cross-flow pattern change due to the laterally confined test section. Based on this benchmarking study, lessons and recommendations about experimental methods as well as CFD methods were also provided for the future research.

  6. Zinc corrosion after loss-of-coolant accidents in pressurized water reactors – Physicochemical effects

    Energy Technology Data Exchange (ETDEWEB)

    Kryk, Holger, E-mail: h.kryk@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics, P.O. Box 510119, D-01314 Dresden (Germany); Hoffmann, Wolfgang [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics, P.O. Box 510119, D-01314 Dresden (Germany); Kästner, Wolfgang; Alt, Sören; Seeliger, André; Renger, Stefan [Hochschule Zittau/Görlitz, Institute of Process Technology, Process Automation and Measuring Technology, Theodor-Körner-Allee 16, D-02763 Zittau (Germany)

    2014-12-15

    Highlights: • Physicochemical effects due to post-LOCA zinc corrosion in PWR were elucidated. • Decreasing solubility of corrosion products with increasing temperature was found. • Solid corrosion products may be deposited on hot surfaces and/or within hot-spots. • Corrosion products precipitating from coolant were identified as zinc borates. • Depending on coolant temperature, different types of zinc borate are formed. - Abstract: Within the framework of the reactor safety research, generic experimental investigations were carried out aiming at the physicochemical background of possible zinc corrosion product formation, which may occur inside the reactor pressure vessel during the sump circulation operation after loss-of-coolant accidents in pressurized water reactors. The contact of the boric acid containing coolant with hot-dip galvanized steel containment internals causes corrosion of the corresponding materials resulting in dissolution of the zinc coat. A retrograde solubility of zinc corrosion products with increasing temperature was observed during batch experiments of zinc corrosion in boric acid containing coolants. Thus, the formation and deposition of solid corrosion products cannot be ruled out if the coolant containing dissolved zinc is heated up during its recirculation into hot regions within the emergency cooling circuit (e.g. hot-spots in the core). Corrosion experiments at a lab-scale test facility, which included formation of corrosion products at a single heated cladding tube, proved that dissolved zinc, formed at low temperatures in boric acid solution by zinc corrosion, turns into solid deposits of zinc borates when contacting heated zircaloy surfaces during the heating of the coolant. Moreover, the temperature of formation influences the chemical composition of the zinc borates and thus the deposition and mobilization behavior of the products.

  7. Effect of administration of water enriched in O2 by injection or electrolysis on transcutaneous oxygen pressure in anesthetized pigs

    Directory of Open Access Journals (Sweden)

    Charton A

    2014-08-01

    Full Text Available Antoine Charton,1 François Péronnet,2 Stephane Doutreleau,3 Evelyne Lonsdorfer,3 Alexis Klein,4 Liliana Jimenez,4 Bernard Geny,3 Pierre Diemunsch,1 Ruddy Richard5 1Department of Anesthesia and Critical Care, and EA 3072, Hôpital de Hautepierre; University of Strasbourg, Strasbourg, France; 2Department of Kinesiology, Université de Montréal, Montreal, QC, Canada; 3CHRU of Strasbourg, Physiology and Functional Explorations Department, New Civil Hospital, Strasbourg, France and University of Strasbourg, Faculty of Medicine, Physiology Department, Strasbourg, France; 4Danone Research, Palaiseau, France; 5Department of Sport Medicine and Functional Explorations, CHU Clermont-Ferrand and INRA UMR 1019, CRNH-Auvergne, Clermont-Ferrand, France Background: Oral administration of oxygenated water has been shown to improve blood oxygenation and could be an alternate way for oxygen (O2 supply. In this experiment, tissue oxygenation was compared in anesthetized pigs receiving a placebo or water enriched in O2 by injection or a new electrolytic process. Methods: Forty-two pigs randomized in three groups received either mineral water as placebo or water enriched in O2 by injection or the electrolytic process (10 mL/kg in the stomach. Hemodynamic parameters, partial pressure of oxygen in the arterial blood (PaO2, skin blood flow, and tissue oxygenation (transcutaneous oxygen pressure, or TcPO2 were monitored during 90 minutes of general anesthesia. Absorption and tissue distribution of the three waters administered were assessed using dilution of deuterium oxide. Results: Mean arterial pressure, heart rate, PaO2, arteriovenous oxygen difference, and water absorption from the gut were not significantly different among the three groups. The deuterium to protium ratio was also similar in the plasma, skin, and muscle at the end of the protocol. Skin blood flow decreased in the three groups. TcPO2 slowly decreased over the last 60 minutes of the experiment in

  8. The development of a neutralizing amines based reagent for maintaining the water chemistry for medium and high pressures steam boilers

    Science.gov (United States)

    Butakova, M. V.; Orlov, K. A.; Guseva, O. V.

    2017-11-01

    An overview of the development for neutralizing amine based reagent for water chemistry of steam boilers for medium and high pressures was given. Total values of the neutralization constants and the distribution coefficients of the compositions selected as a main criteria for reagent composition. Experimental results of using this new reagent for water chemistry in HRSG of power plant in oil-production company are discussed.

  9. Tribocorrosion in pressurized high temperature water: a mass flow model based on the third body approach

    Energy Technology Data Exchange (ETDEWEB)

    Guadalupe Maldonado, S.

    2014-07-01

    Pressurized water reactors (PWR) used for power generation are operated at elevated temperatures (280-300 °C) and under higher pressure (120-150 bar). In addition to these harsh environmental conditions some components of the PWR assemblies are subject to mechanical loading (sliding, vibration and impacts) leading to undesirable and hardly controllable material degradation phenomena. In such situations wear is determined by the complex interplay (tribocorrosion) between mechanical, material and physical-chemical phenomena. Tribocorrosion in PWR conditions is at present little understood and models need to be developed in order to predict component lifetime over several decades. The goal of this project, carried out in collaboration with the French company AREVA NP, is to develop a predictive model based on the mechanistic understanding of tribocorrosion of specific PWR components (stainless steel control assemblies, stellite grippers). The approach taken here is to describe degradation in terms of electro-chemical and mechanical material flows (third body concept of tribology) from the metal into the friction film (i.e. the oxidized film forming during rubbing on the metal surface) and from the friction film into the environment instead of simple mass loss considerations. The project involves the establishment of mechanistic models for describing the single flows based on ad-hoc tribocorrosion measurements operating at low temperature. The overall behaviour at high temperature and pressure in investigated using a dedicated tribometer (Aurore) including electrochemical control of the contact during rubbing. Physical laws describing the individual flows according to defined mechanisms and as a function of defined physical parameters were identified based on the obtained experimental results and from literature data. The physical laws were converted into mass flow rates and solved as differential equation system by considering the mass balance in compartments

  10. Photolytic removal of DBPs by medium pressure UV in swimming pool water

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Kamilla M.S. [Department of Environmental Engineering, Technical University of Denmark (Denmark); Zortea, Raissa [Department of Land, Environment and Geotechnology Engineering, Polytechnic University of Turin (Italy); Piketty, Aurelia [Institute of Chemistry, Industrial and Chemical Engineering and Technology (INP-ENCIACET), National Polytechnic Institute of Toulouse (France); Vega, Sergio Rodriguez [Chemical Engineering, Complutense University of Madrid (Spain); Andersen, Henrik Rasmus, E-mail: Henrik@ndersen.net [Department of Environmental Engineering, Technical University of Denmark (Denmark)

    2013-01-15

    Medium pressure UV is used for controlling the concentration of combined chlorine (chloramines) in many public swimming pools. Little is known about the fate of other disinfection by-products (DBPs) in UV treatment. Photolysis by medium pressure UV treatment was investigated for 12 DBPs reported to be found in swimming pool water: chloroform, bromodichloromethane, dibromochloromethane, bromoform, dichloroacetonitrile, bromochloroacetonitrile, dibromoacetronitrile, trichloroacetonitrile, trichloronitromethane, dichloropropanone, trichloropropanone, and chloral hydrate. First order photolysis constants ranged 26-fold from 0.020 min{sup −1} for chloroform to 0.523 min{sup −1} for trichloronitromethane. The rate constants generally increased with bromine substitution. Using the UV removal of combined chlorine as an actinometer, the rate constants were recalculated to actual treatment doses of UV applied in a swimming pool. In an investigated public pool the UV dose was equivalent to an applied electrical energy of 1.34 kWh m{sup −3} d{sup −1} and the UV dose required to removed 90% of trichloronitromethane was 0.4 kWh m{sup −3} d{sup −1}, while 2.6 kWh m{sup −3} d{sup −1} was required for chloral hydrate and the bromine containing haloacetonitriles and trihalomethanes ranged from 0.6 to 3.1 kWh m{sup −3} d{sup −1}. It was predicted thus that a beneficial side-effect of applying UV for removing combined chlorine from the pool water could be a significant removal of trichloronitromethane, chloral hydrate and the bromine containing haloacetonitriles and trihalomethanes. - Highlights: ► UV irradiation is able to degrade all 12 investigated disinfection by-products. ► Bromine species are easier to remove than their chlorinated analogues. ► UV dose used for combined chlorine was comparable with doses required for DBP removal. ► Significant removal of some disinfection by-products in swimming pools is indicated.

  11. The subglacial Lake Vostok (East Antarctica) surface snow is Earth-bound DNA (and dust)-free

    Science.gov (United States)

    Bulat, S.; Marie, D.; Bulat, E.; Alekhina, I.; Petit, J.-R.

    2012-09-01

    came up with only contaminant bacterial phylotypes (mostly of human source). The bioexposure trials showed that even in one day of open exposure the gDNA of rather complex microbial community composition was fatally damaged in terms of long-, mid-range and short-size amplicon generation in PCR. All this testify for very harsh conditions for life to survive the climate conditions of Central East Antarctica which could be considered as a presentday 'zone mortale' or 'polar desert' for known Earthbound microbial life forms. In addition this means that no life seeds are expected to reach subglacial lakes and water reservoirs and establish indigenous lake microbiota during their transit through the thick and aged Antarctic ice sheet upon its bottom melting. In general the subglacial Lake Vostok surface (ice sheet as well) environ represents the unique test area (sterile - in fact Earth-bound DNA-free and clean - in fact Earth-bound dust-free) for advancing extraterrestrial (ET) life detection technologies and searching for ET life indices in AMMs and IDPs.

  12. Removal of TiO2 nanoparticles from water by low pressure pilot plant filtration.

    Science.gov (United States)

    Olabarrieta, Josune; Monzón, Oihane; Belaustegui, Yolanda; Alvarez, Jon-Iñaki; Zorita, Saioa

    2017-11-14

    Rising use of nanoparticles in manufacturing as well as in commercial products bring issues related to environmental release and human exposure. A large amount of TiO2 nanoparticles will eventually reach wastewater treatment plants. Low pressure membrane filtration has been suggested as a feasible treatment of water streams. This study investigated first at laboratory scale the influence of: i) membrane material, ii) pore size and iii) water chemistry on nTiO2 removal. TiO2 retention was governed by the cake layer formation mechanism and significant retention of nanoparticles was observed even for filters having considerably larger pores than nTiO2. PVDF showed a great potential for nTiO2 rejection. Additionally, filtration pilot plant experiments were carried out using PVDF membranes (0.03 and 0.4μm pore size). The release of nTiO2 in the pilot scale filtration system was always above the instrumental detection limit (>1.5μg/L) and in most cases below 100μg/L regardless of the pore size and applied conditions. The nTiO2 membrane breakthrough predominantly occurred in the first few minutes after backwashes and ceased when the cake layer was formed. Ultrafiltration and microfiltration were comparable with rejection of nTiO2 above 95% at similar permeate flow rates. Nevertheless, ultrafiltration is more promising than microfiltration because it allowed longer operation times between backwash cycles. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Effect of amphiphilic additives on the behavior of water-based acrylic pressure-sensitive adhesives during paper recycling

    Science.gov (United States)

    Jihui Guo; Steven J. Severtson; Larry E. Gwin; Carl J. Houtman

    2008-01-01

    Pressure-sensitive adhesives (PSAs) in recovered paper reduce efficiency and increase operating costs for paper recycling mills. Increased PSA fragmentation during pulping and the corresponding reduction in screening efficiency are indications that a PSA will likely interfere with paper recycling. Water-based PSAs, which dominate the label market, have complex...

  14. Where do winds come from? A new theory on how water vapor condensation influences atmospheric pressure and dynamics

    Directory of Open Access Journals (Sweden)

    A. M. Makarieva

    2013-01-01

    Full Text Available Phase transitions of atmospheric water play a ubiquitous role in the Earth's climate system, but their direct impact on atmospheric dynamics has escaped wide attention. Here we examine and advance a theory as to how condensation influences atmospheric pressure through the mass removal of water from the gas phase with a simultaneous account of the latent heat release. Building from fundamental physical principles we show that condensation is associated with a decline in air pressure in the lower atmosphere. This decline occurs up to a certain height, which ranges from 3 to 4 km for surface temperatures from 10 to 30 °C. We then estimate the horizontal pressure differences associated with water vapor condensation and find that these are comparable in magnitude with the pressure differences driving observed circulation patterns. The water vapor delivered to the atmosphere via evaporation represents a store of potential energy available to accelerate air and thus drive winds. Our estimates suggest that the global mean power at which this potential energy is released by condensation is around one per cent of the global solar power – this is similar to the known stationary dissipative power of general atmospheric circulation. We conclude that condensation and evaporation merit attention as major, if previously overlooked, factors in driving atmospheric dynamics.

  15. Effects on Vocal Fold Collision and Phonation Threshold Pressure of Resonance Tube Phonation with Tube End in Water

    Science.gov (United States)

    Enflo, Laura; Sundberg, Johan; Romedahl, Camilla; McAllister, Anita

    2013-01-01

    Purpose: Resonance tube phonation in water (RTPW) or in air is a voice therapy method successfully used for treatment of several voice pathologies. Its effect on the voice has not been thoroughly studied. This investigation analyzes the effects of RTPW on collision and phonation threshold pressures (CTP and PTP), the lowest subglottal pressure…

  16. Waste water ducts in high-rise buildings. Pressure compensation in the downpipe; Schmutzwasserleitungen in Hochhaeusern. Druckausgleich im Fallrohr

    Energy Technology Data Exchange (ETDEWEB)

    Ishorst, B. [Informationszentrum Entwaesserungstechnik Guss e.V. (IZEG) (Germany); Guetegemeinschaft Entwaesserungstechnik Guss e.V. (GEG) (Germany)

    2006-09-15

    Ventilation is a key aspect for correct function of a waste water system. In order to enable pressure compensation and ensure that sewer gases are led outside, downpipes in high-rise buildings must have at least one main ventilation duct. The author presents examples to illustrate how downpipes should be constructed for optimum flow conditions and reliable function. (orig.)

  17. Standard Test Method for Water Penetration of Flat Plate Solar Collectors by Uniform Static Air Pressure Difference

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1986-01-01

    1.1 This test method covers the determination of the resistance of flat plate solar collectors to water penetration when water is applied to their outer surfaces with a static air pressure at the outer surface higher than the pressure at the interior of the collector. 1.2 This test method is applicable to any flat plate solar collector. 1.3 The proper use of this test method requires a knowledge of the principles of pressure and deflection measurement. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary information is contained in Section 6.

  18. Navigating Rough Waters: A Synthesis of the Countervailing Pressures against Leading for Social Justice

    Science.gov (United States)

    Theoharis, George

    2007-01-01

    This article presents a synthesis of countervailing pressures against leading for social justice as described in the literature. This synthesis focuses on the present-day countervailing pressures that school leaders face as detailed in the literature on leading for social justice. These countervailing pressures include a deficit-thinking status…

  19. Design of PIλDμ controller for global power control of Pressurized Heavy Water Reactor.

    Science.gov (United States)

    Bongulwar, M R; Patre, B M

    2017-07-01

    In this paper, a robust stabilizing controller design method is presented for global power control of a Pressurized Heavy Water Reactor (PHWR) under step-back condition scheme using a Fractional Order Proportional Integral Derivative (PIλDμ) controller resulting into robust performance. The method is applicable to design a controller for One Non Integer Order Plus Time Delay (NIOPTD-I) plant which satisfies design specifications such as phase margin and gain crossover frequency. Stability boundary locus method is used in (Kp, Ki, Kd) parameter space for NIOPTD-I plants to obtain stability region. The robust performance is obtained by satisfying flat phase condition at gain crossover frequency where phase is almost constant for large span of frequencies. The simulation result of the proposed PIλDμ controller shows active step-back control to the insertion of the rod with no undershoot and with the robust performance, hence safe to the plant for gain variations from 500% lower side to 1000% upper side. The PIλDμ controller with a plant shows that 30% and 50% global power drop from initial 100% is achieved in a reasonable time without undershoot. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  20. Development of Abnormal Operating Strategies for Station Blackout in Shutdown Operating Mode in Pressurized Water Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Duk-Joo; Lee, Seung-Chan; Sung, Je-Joong; Ha, Sang-Jun [KHNP CRI, Daejeon (Korea, Republic of); Hwang, Su-Hyun [FNC Tech. Co., Yongin (Korea, Republic of)

    2016-10-15

    Loss of all AC power is classified as one of multiple failure accident by regulatory guide of Korean accident management program. Therefore we need develop strategies for the abnormal operating procedure both of power operating and shutdown mode. This paper developed abnormal operating guideline for loss of all AC power by analysis of accident scenario in pressurized water reactor. This paper analyzed the loss of ultimate heat sink (LOUHS) in shutdown operating mode and developed the operating strategy of the abnormal procedure. Also we performed the analysis of limiting scenarios that operator actions are not taken in shutdown LOUHS. Therefore, we verified the plant behavior and decided operator action to taken in time in order to protect the fuel of core with safety. From the analysis results of LOUHS, the fuel of core maintained without core uncovery for 73 minutes respectively for opened RCS states after the SBO occurred. Therefore, operator action for the emergency are required to take in 73 minutes for opened RCS state. Strategy is to cooldown by using spent fuel pool cooling system. This method required to change the plant design in some plant. In RCS boundary closed state, first abnormal operating strategy in shutdown LOUHS is first abnormal operating strategy in shutdown LOUHS is to remove the residual heat of core by steam dump flow and auxiliary feedwater of SG.

  1. Capillary pressure heterogeneity and hysteresis for the supercritical CO2/water system in a sandstone

    Science.gov (United States)

    Pini, Ronny; Benson, Sally M.

    2017-10-01

    We report results from an experimental investigation on the hysteretic behaviour of the capillary pressure curve for the supercritical CO2-water system in a Berea Sandstone core. Previous observations have highlighted the importance of subcore-scale capillary heterogeneity in developing local saturations during drainage; we show in this study that the same is true for the imbibition process. Spatially distributed drainage and imbibition scanning curves were obtained for mm-scale subsets of the rock sample non-invasively using X-ray CT imagery. Core- and subcore-scale measurements are well described using the Brooks-Corey formalism, which uses a linear trapping model to compute mobile saturations during imbibition. Capillary scaling yields two separate universal drainage and imbibition curves that are representative of the full subcore-scale data set. This enables accurate parameterisation of rock properties at the subcore-scale in terms of capillary scaling factors and permeability, which in turn serve as effective indicators of heterogeneity at the same scale even when hysteresis is a factor. As such, the proposed core-analysis workflow is quite general and provides the required information to populate numerical models that can be used to extend core-flooding experiments to conditions prevalent in the subsurface, which would be otherwise not attainable in the laboratory.

  2. Acoustic and Doppler radar detection of buried land mines using high-pressure water jets

    Science.gov (United States)

    Denier, Robert; Herrick, Thomas J.; Mitchell, O. Robert; Summers, David A.; Saylor, Daniel R.

    1999-08-01

    The goal of the waterjet-based mine location and identification project is to find a way to use waterjets to locate and differentiate buried objects. When a buried object is struck with a high-pressure waterjets, the impact will cause characteristic vibrations in the object depending on the object's shape and composition. These vibrations will be transferred to the ground and then to the water stream that is hitting the object. Some of these vibrations will also be transferred to the air via the narrow channel the waterjet cuts in the ground. Currently the ground vibrations are detected with Doppler radar and video camera sensing, while the air vibrations are detected with a directional microphone. Data is collected via a Labview based data acquisition system. This data is then manipulated in Labview to produce the associated power spectrums. These power spectra are fed through various signal processing and recognition routines to determine the probability of there being an object present under the current test location and what that object is likely to be. Our current test area consists of a large X-Y positioning system placed over approximately a five-foot circular test area. The positioning system moves both the waterjet and the sensor package to the test location specified by the Labview control software. Currently we are able to locate buried land mine models at a distance of approximately three inches with a high degree of accuracy.

  3. Nonlinear control for core power of pressurized water nuclear reactors using constant axial offset strategy

    Directory of Open Access Journals (Sweden)

    Gholam Reza Ansarifar

    2015-12-01

    Full Text Available One of the most important operations in nuclear power plants is load following, in which an imbalance of axial power distribution induces xenon oscillations. These oscillations must be maintained within acceptable limits otherwise the nuclear power plant could become unstable. Therefore, bounded xenon oscillation is considered to be a constraint for the load following operation. In this paper, the design of a sliding mode control (SMC, which is a robust nonlinear controller, is presented. SMC is a means to control pressurized water nuclear reactor (PWR power for the load following operation problem in a way that ensures xenon oscillations are kept bounded within acceptable limits. The proposed controller uses constant axial offset (AO strategy to ensure xenon oscillations remain bounded. The constant AO is a robust state constraint for the load following problem. The reactor core is simulated based on the two-point nuclear reactor model with a three delayed neutron groups. The stability analysis is given by means of the Lyapunov approach, thus the control system is guaranteed to be stable within a large range. The employed method is easy to implement in practical applications and moreover, the SMC exhibits the desired dynamic properties during the entire output-tracking process independent of perturbations. Simulation results are presented to demonstrate the effectiveness of the proposed controller in terms of performance, robustness, and stability. Results show that the proposed controller for the load following operation is so effective that the xenon oscillations are kept bounded in the given region.

  4. Power Maneuvering of Pressurized Water Reactors with Axially Variable Strength Control Rods

    Science.gov (United States)

    Kim, Ung-Soo; Seong, Poong-Hyun

    2004-02-01

    In this research, axially variable strength control rods (AVSCRs) are developed to solve the problems related to the axial power distribution of a reactor during power maneuvering of pressurized water reactors (PWRs). The control rods are classified into two types: multipurpose control rods and regulating control rods. Two multipurpose control rod banks (AVSCR1, AVSCR2) are newly developed; conventional axially uniform strength control rods are adopted as regulating control rod banks to minimize the design change. The newly developed AVSCRs are axially three-sectioned and their worth shapes are optimized to obtain appropriate moving characteristics related to the variation of the axial offset (AO) according to the motion of the AVSCRs. The operation strategy for the power maneuvering is developed in consideration of the moving characteristics of the AVSCRs. This strategy consists of simple logics, and no use of reactivity compensation by boron is considered. Finally, the AVSCRs are applied to the power maneuvering with a typical 100-50-100%, 2-6-2-14 h pattern of daily load-follow for all burn-up state of the core. From the application results, it is shown that the use of AVSCRs makes it possible to regulate AO within the target band during the power maneuvering with only control rods. Consequently, power maneuvering is accomplished without reactivity compensation by a change in boron concentration, and the AVSCRs can cover the entire burn-up states of the reactor core.

  5. Neutron-gamma flux and dose calculations in a Pressurized Water Reactor (PWR

    Directory of Open Access Journals (Sweden)

    Brovchenko Mariya

    2017-01-01

    Full Text Available The present work deals with Monte Carlo simulations, aiming to determine the neutron and gamma responses outside the vessel and in the basemat of a Pressurized Water Reactor (PWR. The model is based on the Tihange-I Belgian nuclear reactor. With a large set of information and measurements available, this reactor has the advantage to be easily modelled and allows validation based on the experimental measurements. Power distribution calculations were therefore performed with the MCNP code at IRSN and compared to the available in-core measurements. Results showed a good agreement between calculated and measured values over the whole core. In this paper, the methods and hypotheses used for the particle transport simulation from the fission distribution in the core to the detectors outside the vessel of the reactor are also summarized. The results of the simulations are presented including the neutron and gamma doses and flux energy spectra. MCNP6 computational results comparing JEFF3.1 and ENDF-B/VII.1 nuclear data evaluations and sensitivity of the results to some model parameters are presented.

  6. Correlation of surface pressure and hue of planarizable push-pull chromophores at the air/water interface.

    Science.gov (United States)

    Neuhaus, Frederik; Zobi, Fabio; Brezesinski, Gerald; Dal Molin, Marta; Matile, Stefan; Zumbuehl, Andreas

    2017-01-01

    It is currently not possible to directly measure the lateral pressure of a biomembrane. Mechanoresponsive fluorescent probes are an elegant solution to this problem but it requires first the establishment of a direct correlation between the membrane surface pressure and the induced color change of the probe. Here, we analyze planarizable dithienothiophene push-pull probes in a monolayer at the air/water interface using fluorescence microscopy, grazing-incidence angle X-ray diffraction, and infrared reflection-absorption spectroscopy. An increase of the lateral membrane pressure leads to a well-packed layer of the 'flipper' mechanophores and a clear change in hue above 18 mN/m. The fluorescent probes had no influence on the measured isotherm of the natural phospholipid DPPC suggesting that the flippers probe the lateral membrane pressure without physically changing it. This makes the flipper probes a truly useful addition to the membrane probe toolbox.

  7. Correlation of surface pressure and hue of planarizable push–pull chromophores at the air/water interface

    Science.gov (United States)

    Neuhaus, Frederik; Zobi, Fabio; Brezesinski, Gerald; Dal Molin, Marta; Matile, Stefan

    2017-01-01

    It is currently not possible to directly measure the lateral pressure of a biomembrane. Mechanoresponsive fluorescent probes are an elegant solution to this problem but it requires first the establishment of a direct correlation between the membrane surface pressure and the induced color change of the probe. Here, we analyze planarizable dithienothiophene push–pull probes in a monolayer at the air/water interface using fluorescence microscopy, grazing-incidence angle X-ray diffraction, and infrared reflection–absorption spectroscopy. An increase of the lateral membrane pressure leads to a well-packed layer of the ‘flipper’ mechanophores and a clear change in hue above 18 mN/m. The fluorescent probes had no influence on the measured isotherm of the natural phospholipid DPPC suggesting that the flippers probe the lateral membrane pressure without physically changing it. This makes the flipper probes a truly useful addition to the membrane probe toolbox. PMID:28684989

  8. Water holdup estimation from pressure drop measurements in oil-water two-phase flows by means of the two-fluid model

    Science.gov (United States)

    Colombo, L. P. M.; Guilizzoni, M.; Sotgia, G.; Babakhani Dehkordi, P.; Lucchini, A.

    2017-11-01

    The Two-Fluid Model (TFM) has been applied to determine water holdup from pressure drop measurements for core-annular flows in horizontal pipes. The fluids are Milpar 220 oil (ρo=890 kg/m3, μo=0.832 Pa·s at 20 °C) and tap water (μw=1.026×10-3 Pa·s at 20 °C). The investigated volume flow rates range from 2 to 6 m3/h, for water, and from 1 to 3.5 m3/h, for oil, respectively. The results are in very good agreement with available experimental data from the literature and a simple correlation between water holdup and water input fraction has been benchmarked to the overall data set. Eventually, the TFM endowed with the holdup correlation has been adopted to predict the pressure drop with quite satisfactory results: 98% of data fall within a percentage error of ±10%, 99% of the data fall within ±15%, and all the data are predicted within ±20%. On the other hand, the mean absolute relative error for the pressure drop reduction factor is 5.5%.

  9. Managing multiple diffuse pressures on water quality and ecological habitat: Spatially targeting effective mitigation actions at the landscape scale.

    Science.gov (United States)

    Joyce, Hannah; Reaney, Sim

    2015-04-01

    Catchment systems provide multiple benefits for society, including: land for agriculture, climate regulation and recreational space. Yet, these systems also have undesirable externalities, such as flooding, and the benefits they create can be compromised through societal use. For example, agriculture, forestry and urban land use practices can increase the export of fine sediment and faecal indicator organisms (FIO) delivered to river systems. These diffuse landscape pressures are coupled with pressures on the in stream temperature environment from projected climate change. Such pressures can have detrimental impacts on water quality and ecological habitat and consequently the benefits they provide for society. These diffuse and in-stream pressures can be reduced through actions at the landscape scale but are commonly tackled individually. Any intervention may have benefits for other pressures and hence the challenge is to consider all of the different pressures simultaneously to find solutions with high levels of cross-pressure benefits. This research presents (1) a simple but spatially distributed model to predict the pattern of multiple pressures at the landscape scale, and (2) a method for spatially targeting the optimum location for riparian woodland planting as mitigation action against these pressures. The model follows a minimal information requirement approach along the lines of SCIMAP (www.scimap.org.uk). This approach defines the critical source areas of fine sediment diffuse pollution, rapid overland flow and FIOs, based on the analysis of the pattern of the pressure in the landscape and the connectivity from source areas to rivers. River temperature was modeled using a simple energy balance equation; focusing on temperature of inflowing and outflowing water across a catchment. The model has been calibrated using a long term observed temperature record. The modelling outcomes enabled the identification of the severity of each pressure in relative rather

  10. Solubility of natural gases in water under high pressure; Solubilite des gaz naturels dans l`eau a pression elevee

    Energy Technology Data Exchange (ETDEWEB)

    Dhima, A.

    1998-10-08

    Under high pressure (up to 1200 bar) and high temperature (up to 200 deg C) petroleum reservoir conditions the hydrocarbon-water mutual solubilities may become important. Under such conditions, the prediction of hydrocarbon water solubilities is a challenge for petroleum engineers. Indeed, very few studies have been done ar pressures higher that 700 bars. New solubility data for methane, ethane, n-butane, CO{sub 2} and their mixtures in pure water were obtained at 344.25 K and from 2.5 to 100 MPa. The results agree very well with those of the literature in the case of pure hydrocarbons in water, but differ for the hydrocarbon mixtures. A rigorous thermodynamic analysis allows the elaboration of a model that combines a cubic equation of state (Peng-Robinson with k{sub ij} given in literature) with the Henry`s law approach. The (P,T) functional form of Henry`s constant is given by the Krichevsky-Kasarnovsky equation which involves two important parameters: partial molar volume at infinite dilution and Henry`s constant at the vapour pressure of water. For a given solute both parameters are only functions of temperature. A critical selection of binary solubility data for a large number of solutes has been used as a basis for a new correlation for calculating both this partial molar volume and the corresponding Henry`s constants as a function of temperature. (author) 169 refs.

  11. Aggregation of non-polar solutes in water at different pressures and temperatures: the role of hydrophobic interaction.

    Science.gov (United States)

    Ferrara, C Gastón; Chara, Osvaldo; Grigera, J Raúl

    2012-10-07

    Due to the importance of the hydrophobic interaction in protein folding, we decided to study the effect of pressure and temperature on the phase transitions of non-polar solutes in water, and thereby their solubility, using molecular dynamics simulations. The main results are: (1) within a certain range, temperature induces the aggregation of Lennard-Jones particles in water; and (2) pressure induces disaggregation of the formed clusters. From the simulated data, a non-monotonic coexistence curve for the binary system was obtained, from which a critical point of T(c) = 383 ± 9 K and p(c) = 937 ± 11 bar was determined. The results are in accordance with previous experimental evidence involving transitions of hydrocarbons in water mixtures, and protein unfolding.

  12. Destruction of hazardous waste in supercritical water. Part 2, A study of high-pressure methanol oxidation kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, R.G.; Butler, P.B. [Iowa Univ., Iowa City, IA (United States); Bergan, N.E. [Sandia National Labs., Livermore, CA (United States); Pitz, W.J.; Westbrook, C.K. [Lawrence Livermore National Lab., CA (United States)

    1991-12-31

    In supercritical water oxidation, dilute aqueous organic wastes are oxidized at temperatures and pressures above the critical point of water. This process has been successfully demonstrated to treat waste streams of interest to the Department of Energy production facilities. In this paper we present a numerical study on the oxidation kinetics of a waste containing 98% water and 2% methanol under supercritical conditions. The plug-flow reactor model is similar to that presented in an earlier publication. We have corrected the chemistry in this model by changing the reaction rates of unimolecular reactions to their high-pressure limits. Our results show that the decomposition step of H{sub 2}O{sub 2} into the OH radical is the dominant reaction step controlling the destruction of methanol under supercritical conditions. Using the corrected chemistry model, we calculate the characteristic destruction times of methanol as a function of reactor inlet conditions.

  13. Detrital zircons - the unique source of information on tectonics, paleogeography and denudation processes of East Antarctica (subglacial challenge)

    Science.gov (United States)

    Belyatsky, Boris; Leitchenkov, German; Rodionov, Nickolay; Antonov, Anton; Sergeev, Sergey; Savva, Helen

    2010-05-01

    composition of hafnium in detrital zircons from two moraine samples was studied using SIMS CAMECA-4f and laser device coupled with HR-MC-ICPMS. Distribution of trace elements allows us to suggest that 70-85% zircons have been crystallized from magma of intermediate-silicic composition with temperature of crystallization of 700-800° C (65% SiO2) and about 10-15% - from low-temperature water-saturated granitoid melts. Only 5-7% zircons are formed as a result of metamorphic processes. Four zircon grains from metasandstone (Fisher Massive) have specific distribution of trace elements which are typical to high-temperature (up to 950° C) magmas of alkaline or mafic affinity. Hf isotope signatures show according to two-step evolution model that zircons from metasandstone of Fisher Massive were formed in crust protoliths of 1400-2200 m.y. old, whereas zircons from sandstone of Meridith Massive - in protolith of 1400-1600 m.y. and 3000-3400 m.y. old. Generally, Hf isotope composition of studied zircons corresponds to composition of chondrite unfractionated reservoir (CHUR). The first opportunity to obtain direct information about the bedrock geology of the central East Antarctic arose when the 3650 m deep borehole at the Vostok station, located in the southern part of Lake Vostok (largest subglacial freshwater lake in Antarctica) recovered the basal layer of the ice sheet. We studied a small (4.7 mm long) clast of siltstone extracted from the 3607 m depth ice core of the Vostok Station Borehole. This clast was entrapped from bottom sediments in the shallow area of the lake and incorporated into the accreted ice. Siltstone consists of poorly-rounded quartz and a minor amount of accessories including zircon and monazite. We infer that the bedrock upstream (northwest) of Lake Vostok from where the siltstone clast was scraped off bedrock by ice and transported to the lake is of sedimentary nature. 23 zircon and 5 monazite grains in the siltstone clast have yielded two age clusters

  14. Melt-induced speed-up of Greenland ice sheet offset by efficient subglacial drainage.

    Science.gov (United States)

    Sundal, Aud Venke; Shepherd, Andrew; Nienow, Peter; Hanna, Edward; Palmer, Steven; Huybrechts, Philippe

    2011-01-27

    Fluctuations in surface melting are known to affect the speed of glaciers and ice sheets, but their impact on the Greenland ice sheet in a warming climate remains uncertain. Although some studies suggest that greater melting produces greater ice-sheet acceleration, others have identified a long-term decrease in Greenland's flow despite increased melting. Here we use satellite observations of ice motion recorded in a land-terminating sector of southwest Greenland to investigate the manner in which ice flow develops during years of markedly different melting. Although peak rates of ice speed-up are positively correlated with the degree of melting, mean summer flow rates are not, because glacier slowdown occurs, on average, when a critical run-off threshold of about 1.4 centimetres a day is exceeded. In contrast to the first half of summer, when flow is similar in all years, speed-up during the latter half is 62 ± 16 per cent less in warmer years. Consequently, in warmer years, the period of fast ice flow is three times shorter and, overall, summer ice flow is slower. This behaviour is at odds with that expected from basal lubrication alone. Instead, it mirrors that of mountain glaciers, where melt-induced acceleration of flow ceases during years of high melting once subglacial drainage becomes efficient. A model of ice-sheet flow that captures switching between cavity and channel drainage modes is consistent with the run-off threshold, fast-flow periods, and later-summer speeds we have observed. Simulations of the Greenland ice-sheet flow under climate warming scenarios should account for the dynamic evolution of subglacial drainage; a simple model of basal lubrication alone misses key aspects of the ice sheet's response to climate warming.

  15. A Unified Constitutive Model for Subglacial Till, Part I: The Disturbed State Concept

    Science.gov (United States)

    Jenson, J. W.; Desai, C. S.; Clark, P. U.; Contractor, D. N.; Sane, S. M.; Carlson, A. E.

    2006-12-01

    Classical plasticity models such as Mohr-Coulomb may not adequately represent the full range of possible motion and failure in tills underlying ice sheets. Such models assume that deformations are initially elastic, and that when a peak or failure stress level is reached the system experiences sudden failure, after which the stress remains constant and the deformations can tend to infinite magnitudes. However, theory suggests that the actual behavior of deforming materials, including granular materials such as glacial till, can involve plastic or irreversible strains almost from the beginning, in which localized zones of microcracking and "failure" can be distributed over the material element. As the loading increases, and with associated plastic and creep deformations, the distributed failure zones coalesce. When the extent of such coalesced zones reaches critical values of stresses and strains, the critical condition (failure) can occur in the till, which would cause associated movements of the ice sheet. Failure or collapse then may occur at much larger strain levels. Classical models (e.g., Mohr-Coulomb) may therefore not be able to fully and realistically characterize deformation behavior and the gradual developments of localized failures tending to the global failure and movements. We present and propose the application of the Disturbed State Concept (DSC), a unified model that incorporates the actual pre- and post-failure behavior, for characterizing the behavior of subglacial tills. In this presentation (Part I), we describe the DSC and propose its application to subglacial till. Part II (Desai et al.) describes our application of the DSC with laboratory testing, model calibration, and validations to evaluate the mechanical properties of two regionally significant Pleistocene tills.

  16. IR-based Water Quantification in Nominally Anhydrous High-Pressure Minerals

    Science.gov (United States)

    Koch-Müller, Monika; Rhede, Dieter

    2010-05-01

    ) but follow the same trend, i.e. they increase with decreasing wavenumbers of the OH bands from 59000 ± 6000 for the Fe-endmember to 85800 ± 10000 L mol H2O-1 cm-2 for the Mg-richest sample. From these data we can predict an absorption coefficient for the iron-free Mg-endmember as 100000 ± 7000 L mol H2O-1 cm-2. This value together with ɛ-values for forsterite (Thomas et al. 2009) and wadsleyite (Deon et al. 2010) confirm the negative correlation with the molar volume and positive correlation with the density within this polymophic series. This allows us to predict absorption coefficients for some minerals, where coefficients for one or better two of their polymorphs, either high- or low-pressure, are available. References Bell, D. R., Rossman, G. R., Maldener, J., Endisch, D. & Rauch, F. (2003) Hydroxide in olivine; a quantitative determination of the absolute amount and calibration of the IR spectrum. Journal of Geophysical Research, B, Solid Earth and Planets 108. Deon, F, Koch-Müller, M., Rhede, D., Gottschalk, M., Wirth, R. and Thomas, S.-M. (2010) Location and quantification of hydroxyl in wadsleyite: new insights. Am Mineral (in press). Libowitzky, E. & Rossman, G. R. (1997) An IR absorption calibration for water in minerals. Am Mineral 82, 1111-1115. Paterson, M. S. (1982) The determination of hydroxyl by infrared absorption in quartz, silicate glasses and similar materials. Bull Minéral 105, 20-29. Rossman, G. R. (2006) Analytical methods for measuring water in nominally anhydrous minerals. In: Keppler H, Smyth JR (eds) Water in nominally anhydrous minerals. Reviews in Mineralogy and Geochemistry, vol 62. Mineralogical Society of America, Chantilly, pp 1-28. Thomas, S.-M., Koch-Müller, M., Reichart, P., Rhede, D., Thomas, R., Wirth, R. and Matsyuk, S. (2009) IR calibrations for water determination in olivine, r-GeO2 and SiO2 polymorphs. Physics and Chemistry of Minerals, 36, 489 - 509.

  17. Osmosis-induced water uptake by Eurobitum bituminized radioactive waste and pressure development in constant volume conditions

    Energy Technology Data Exchange (ETDEWEB)

    Marieen, A., E-mail: amarien@sckcen.be [Waste and Disposal Expert Group, Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, 2400 Mol (Belgium); Mokni, N., E-mail: Nadia.mokni@upc.edu [Department of Geotechnical Engineering and Geosciences, Universidad Politecnica de Catalunya (UPC), Calle Gran Capitan, s/n, Edificio C-1, 08034 Barcelona (Spain); Valcke, E. [Waste and Disposal Expert Group, Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, 2400 Mol (Belgium); Olivella, S. [Department of Geotechnical Engineering and Geosciences, Universidad Politecnica de Catalunya (UPC), Calle Gran Capitan, s/n, Edificio C-1, 08034 Barcelona (Spain); Smets, S. [Waste and Disposal Expert Group, Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, 2400 Mol (Belgium); Li, X., E-mail: xli@sckcen.be [EIG EURIDICE, Boeretang 200, 2400 Mol (Belgium)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer The water uptake by Eurobitum is studied to judge the safety of geological disposal. Black-Right-Pointing-Pointer High pressures of up to 20 MPa are measured in constant volume water uptake tests. Black-Right-Pointing-Pointer The morphology of leached Eurobitum samples is studied with {mu}CT and ESEM. Black-Right-Pointing-Pointer The observations are reproduced by an existing CHM formulation for Eurobitum. - Abstract: The chemo-hydro-mechanical (CHM) interaction between swelling Eurobitum radioactive bituminized waste (BW) and Boom Clay is investigated to assess the feasibility of geological disposal for the long-term management of this waste. These so-called compatibility studies include laboratory water uptake tests at Belgian Nuclear Research Center SCK-CEN, and the development of a coupled CHM formulation for Eurobitum by the International Center for Numerical Methods and Engineering (CIMNE, Polytechnical University of Cataluna, Spain). In the water uptake tests, the osmosis-induced swelling, pressure increase and NaNO{sub 3} leaching of small cylindrical BW samples (diameter 38 mm, height 10 mm) is studied under constant total stress conditions and nearly constant volume conditions; the actual geological disposal conditions should be intermediate between these extremes. Two nearly constant volume tests were stopped after 1036 and 1555 days to characterize the morphology of the hydrated BW samples and to visualize the hydrated part with microfocus X-ray Computer Tomography ({mu}CT) and Environmental Scanning Electron Microscopy (ESEM). In parallel, a coupled CHM formulation is developed that describes chemically and hydraulically coupled flow processes in porous materials with salt crystals, and that incorporates a porosity dependent membrane efficiency, permeability and diffusivity. When Eurobitum BW is hydrated in (nearly) constant volume conditions, the osmosis-induced water uptake results in an increasing pressure to

  18. Seasonal Variations of the Earth's Gravitational Field: An Analysis of Atmospheric Pressure, Ocean Tidal, and Surface Water Excitation

    Science.gov (United States)

    Dong, D,; Gross, R.S.; Dickey, J.

    1996-01-01

    Monthly mean gravitational field parameters (denoted here as C(sub even)) that represent linear combinations of the primarily even degree zonal spherical harmonic coefficients of the Earth's gravitational field have been recovered using LAGEOS I data and are compared with those derived from gridded global surface pressure data of the National meteorological center (NMC) spanning 1983-1992. The effect of equilibrium ocean tides and surface water variations are also considered. Atmospheric pressure and surface water fluctuations are shown to be the dominant cause of observed annual C(sub even) variations. Closure with observations is seen at the 1sigma level when atmospheric pressure, ocean tide and surface water effects are include. Equilibrium ocean tides are shown to be the main source of excitation at the semiannual period with closure at the 1sigma level seen when both atmospheric pressure and ocean tide effects are included. The inverted barometer (IB) case is shown to give the best agreement with the observation series. The potential of the observed C(sub even) variations for monitoring mass variations in the polar regions of the Earth and the effect of the land-ocean mask in the IB calculation are discussed.

  19. Better well control through safe drilling margin identification, influx analysis and direct bottom hole pressure control method for deep water

    Energy Technology Data Exchange (ETDEWEB)

    Veeningen, Daan [National Oilwell Varco IntelliServ (NOV), Houston, TX (United States)

    2012-07-01

    Currently, well control events are almost exclusively detected by using surface measurements. Measuring a volume increase in the 'closed loop' mud circulation system; a standpipe pressure decrease; or changes in a variety of drilling parameters provide indicators of a kick. Especially in deep water, where the riser comprises a substantial section of the well bore, early kick detection is paramount for limiting the severity of a well bore influx and improve the ability to regain well control. While downhole data is presently available from downhole tools nearby the bit, available data rates are sparse as mud pulse telemetry bandwidth is limited and well bore measurements compete with transmission of other subsurface data. Further, data transfer is one-directional, latency is significant and conditions along the string are unknown. High-bandwidth downhole data transmission system, via a wired or networked drill string system, has the unique capability to acquire real-time pressure and temperature measurement at a number of locations along the drill string. This system provides high-resolution downhole data available at very high speed, eliminating latency and restrictions that typically limit the availability of downhole data. The paper describes well control opportunities for deep water operations through the use of downhole data independent from surface measurements. First, the networked drill string provides efficient ways to identify pore pressure, fracture gradient, and true mud weight that comprise the safe drilling margin. Second, the independent measurement capability provides early kick detection and improved ability to analyze an influx even with a heterogeneous mud column through distributed along-string annular pressure measurements. Third, a methodology is proposed for a direct measurement method using downhole real-time pressure for maintaining constant bottom hole pressure during well kills in deep water. (author)

  20. Destruction of plutonium using non-uranium fuels in pressurized water reactor peripheral assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Chodak, III, Paul [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    1996-05-01

    This thesis examines and confirms the feasibility of using non-uranium fuel in a pressurized water reactor (PWR) radial blanket to eliminate plutonium of both weapons and civilian origin. In the equilibrium cycle, the periphery of the PWR is loaded with alternating fresh and once burned non-uranium fuel assemblies, with the interior of the core comprised of conventional three batch UO2 assemblies. Plutonium throughput is such that there is no net plutonium production: production in the interior is offset by destruction in the periphery. Using this approach a 50 MT WGPu inventory could be eliminated in approximately 400 reactor years of operation. Assuming all other existing constraints were removed, the 72 operating US PWRs could disposition 50 MT of WGPu in 5.6 years. Use of a low fissile loading plutonium-erbium inert-oxide-matrix composition in the peripheral assemblies essentially destroys 100% of the 239Pu and ≥90% {sub total}Pu over two 18 month fuel cycles. Core radial power peaking, reactivity vs EFPD profiles and core average reactivity coefficients were found to be comparable to standard PWR values. Hence, minimal impact on reload licensing is anticipated. Examination of potential candidate fuel matrices based on the existing experience base and thermo-physical properties resulted in the recommendation of three inert fuel matrix compositions for further study: zirconia, alumina and TRISO particle fuels. Objective metrics for quantifying the inherent proliferation resistance of plutonium host waste and fuel forms are proposed and were applied to compare the proposed spent WGPu non-uranium fuel to spent WGPu MOX fuels and WGPu borosilicate glass logs. The elimination disposition option spent non-uranium fuel product was found to present significantly greater barriers to proliferation than other plutonium disposal products.

  1. A Neural-Network-Based Nonlinear Adaptive State-Observer for Pressurized Water Reactors

    Directory of Open Access Journals (Sweden)

    Zhe Dong

    2013-10-01

    Full Text Available Although there have been some severe nuclear accidents such as Three Mile Island (USA, Chernobyl (Ukraine and Fukushima (Japan, nuclear fission energy is still a source of clean energy that can substitute for fossil fuels in a centralized way and in a great amount with commercial availability and economic competitiveness. Since the pressurized water reactor (PWR is the most widely used nuclear fission reactor, its safe, stable and efficient operation is meaningful to the current rebirth of the nuclear fission energy industry. Power-level regulation is an important technique which can deeply affect the operation stability and efficiency of PWRs. Compared with the classical power-level controllers, the advanced power-level regulators could strengthen both the closed-loop stability and control performance by feeding back the internal state-variables. However, not all of the internal state variables of a PWR can be obtained directly by measurements. To implement advanced PWR power-level control law, it is necessary to develop a state-observer to reconstruct the unmeasurable state-variables. Since a PWR is naturally a complex nonlinear system with parameters varying with power-level, fuel burnup, xenon isotope production, control rod worth and etc., it is meaningful to design a nonlinear observer for the PWR with adaptability to system uncertainties. Due to this and the strong learning capability of the multi-layer perceptron (MLP neural network, an MLP-based nonlinear adaptive observer is given for PWRs. Based upon Lyapunov stability theory, it is proved theoretically that this newly-built observer can provide bounded and convergent state-observation. This observer is then applied to the state-observation of a special PWR, i.e., the nuclear heating reactor (NHR, and numerical simulation results not only verify its feasibility but also give the relationship between the observation performance and observer parameters.

  2. Reactor Physics Behavior of Transuranic-Bearing TRISO-Particle Fuel in a Pressurized Water Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Michael A. Pope; R. Sonat Sen; Abderrafi M. Ougouag; Gilles Youinou; Brian Boer

    2012-04-01

    Calculations have been performed to assess the neutronic behavior of pins of Fully-Ceramic Micro-encapsulated (FCM) fuel in otherwise-conventional Pressurized Water Reactor (PWR) fuel pins. The FCM fuel contains transuranic (TRU)-only oxide fuel in tri-isotropic (TRISO) particles with the TRU loading coming from the spent fuel of a conventional LWR after 5 years of cooling. Use of the TRISO particle fuel would provide an additional barrier to fission product release in the event of cladding failure. Depletion calculations were performed to evaluate reactivity-limited burnup of the TRU-only FCM fuel. These calculations showed that due to relatively little space available for fuel, the achievable burnup with these pins alone is quite small. Various reactivity parameters were also evaluated at each burnup step including moderator temperature coefficient (MTC), Doppler, and soluble boron worth. These were compared to reference UO{sub 2} and MOX unit cells. The TRU-only FCM fuel exhibits degraded MTC and Doppler coefficients relative to UO{sub 2} and MOX. Also, the reactivity effects of coolant voiding suggest that the behavior of this fuel would be similar to a MOX fuel of very high plutonium fraction, which are known to have positive void reactivity. In general, loading of TRU-only FCM fuel into an assembly without significant quantities of uranium presents challenges to the reactor design. However, if such FCM fuel pins are included in a heterogeneous assembly alongside LEU fuel pins, the overall reactivity behavior would be dominated by the uranium pins while attractive TRU destruction performance levels in the TRU-only FCM fuel pins is. From this work, it is concluded that use of heterogeneous assemblies such as these appears feasible from a preliminary reactor physics standpoint.

  3. A modified firefly algorithm applied to the nuclear reload problem of a pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Iona Maghali Santos de; Schirru, Roberto, E-mail: ioliveira@con.ufrj.b, E-mail: schirru@lmp.ufrj.b [Universidade Federal do Rio de Janeiro (PEN/COPPE/UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia. Programa de Engenharia Nuclear

    2011-07-01

    The Nuclear Reactor Reload Problem (NRRP) is an issue of great importance and concern in nuclear engineering. It is the problem related with the periodic operation of replacing part of the fuel of a nuclear reactor. Traditionally, this procedure occurs after a period of operation called a cycle, or whenever the nuclear power plant is unable to continue operating at its nominal power. Studied for more than 40 years, the NRRP still remains a challenge for many optimization techniques due to its multiple objectives concerning economics, safety and reactor physics calculations. Characteristics such as non-linearity, multimodality and high dimensionality also make the NRRP a very complex optimization problem. In broad terms, it aims at getting the best arrangement of fuel in the nuclear reactor core that leads to a maximization of the operating time. The primary goal is to design fuel loading patterns (LPs) so that the core produces the required energy output in an economical way, without violating safety limits. Since multiple feasible solutions can be obtained to this problem, judicious optimization is required in order to identify the most economical among them. In this sense, this paper presents a new contribution in this area and introduces a modified firefly algorithm (FA) to perform LPs optimization for a pressurized water reactor. Based on the original FA introduced by Xin-She Yang in 2008, the proposed methodology seems to be very promising as an optimizer to the NRRP. The experiments performed and the comparisons with some well known best performing algorithms from the literature, confirm this statement. (author)

  4. Liquid Steel at Low Pressure: Experimental Investigation of a Downward Water Air Flow

    Science.gov (United States)

    Thumfart, Maria

    2016-07-01

    In the continuous casting of steel controlling the steel flow rate to the mould is critical because a well-defined flow field at the mould level is essential for a good quality of the cast product. The stopper rod is a commonly used device to control this flow rate. Agglomeration of solid material near the stopper rod can lead to a reduced cross section and thus to a decreased casting speed or even total blockage (“clogging”). The mechanisms causing clogging are still not fully understood. Single phase considerations of the flow in the region of the stopper rod result in a low or even negative pressure at the smallest cross section. This can cause degassing of dissolved gases from the melt, evaporation of alloys and entrainment of air through the porous refractory material. It can be shown that the degassing process in liquid steel is taking place mainly at the stopper rod tip and its surrounding. The steel flow around the stopper rod tip is highly turbulent. In addition refractory material has a low wettability to liquid steel. So the first step to understand the flow situation and transport phenomena which occur near the stopper is to understand the behaviour of this two phase (steel, gas) flow. To simulate the flow situation near the stopper rod tip, water experiments are conducted using a convergent divergent nozzle with three different wall materials and three different contact angles respectively. These experiments show the high impact of the wettability of the wall material on the actual flow structure at a constant gas flow rate.

  5. Unveiling subglacial geology and crustal architecture in the Recovery frontier of East Antarctica with recent aeromagnetic and airborne gravity imaging

    Science.gov (United States)

    Ferraccioli, F.; Forsberg, R.; Jordan, T. A.; Matsuoka, K.; Olsen, A.; King, O.; Ghidella, M.

    2014-12-01

    East Antarctica is the least known continent, despite being a keystone in the Gondwana, Rodinia and Columbia supercontinents. Significant progress has been made in recent years in exploring East Antarctica using aeromagnetic and airborne gravity together with radar. Major aerogeophysical campaigns over the Wilkes Subglacial Basin (Ferraccioli et al., 2009 Tectonophysics), the Aurora Subglacial Basin (Aitken et al., 2014 GRL) and the Gamburtsev Subglacial Mountains (Ferraccioli et al., 2011, Nature) provide new glimpses into the crustal architecture of East Antarctica. However, a major sector of the continent that includes key piercing points for reconstructing linkages between East Antarctica and Laurentia within Rodinia, and also the inferred remnants of a major suture zone active during Gondwana amalgamation in Pan-African times (ca 500 Ma), has remained largely terra incognita. Here we present the results of a major aerogeophysical survey flown over this sector of East Antarctica, named the Recovery Frontier, from the major ice stream flowing in the region. The survey was flown during the IceGRAV 2012-13 field season, as part of a Danish-Norwegian-UK and Argentine collaboration and led to the collection of 29,000 line km of radar, laser altimetry, gravity and magnetic data. We present the new aeromagnetic anomaly, Bouguer and residual and enhanced anomaly maps for the region. Using these images we trace the extent of major subglacial faults and interpret these to delineate the tectonic boundaries separating the Coast block, the Shackleton Range and the Dronning Maud Land crustal provinces. Forward magnetic and gravity modelling enables us to examine the inferred Pan-African age suture zone in the Shackleton Range and address its tectonic relationships with older terranes of the Mawson Craton and Grenvillian-age terranes of Dronning Maud Land and interior East Antarctica. Finally, we present new models to test our hypothesis that Paleozoic to Mesozoic rift basins

  6. Potential application of high pressure carbon dioxide in treated wastewater and water disinfection: Recent overview and further trends.

    Science.gov (United States)

    Vo, Huy Thanh; Imai, Tsuyoshi; Ho, Truc Thanh; Dang, Thanh-Loc Thi; Hoang, Son Anh

    2015-10-01

    Recently emerging disadvantages in conventional disinfection have heightened the need for finding a new solution. Developments in the use of high pressure carbon dioxide for food preservation and sterilization have led to a renewed interest in its applicability in wastewater treatment and water disinfection. Pressurized CO2 is one of the most investigated methods of antibacterial treatment and has been used extensively for decades to inhibit pathogens in dried food and liquid products. This study reviews the literature concerning the utility of CO2 as a disinfecting agent, and the pathogen inactivation mechanism of CO2 treatment is evaluated based on all available research. In this paper, it will be argued that the successful application and high effectiveness of CO2 treatment in liquid foods open a potential opportunity for its use in wastewater treatment and water disinfection. The findings from models with different operating conditions (pressure, temperature, microorganism, water content, media …) suggest that most microorganisms are successfully inhibited under CO2 treatment. It will also be shown that the bacterial deaths under CO2 treatment can be explained by many different mechanisms. Moreover, the findings in this study can help to address the recently emerging problems in water disinfection, such as disinfection by-products (resulting from chlorination or ozone treatment). Copyright © 2015. Published by Elsevier B.V.

  7. Application of water-insoluble polymers to orally disintegrating tablets treated by high-pressure carbon dioxide gas.

    Science.gov (United States)

    Ito, Yoshitaka; Maeda, Atsushi; Kondo, Hiromu; Iwao, Yasunori; Noguchi, Shuji; Itai, Shigeru

    2016-09-10

    The phase transition of pharmaceutical excipients that can be induced by humidifying or heating is well-known to increase the hardness of orally disintegrating tablets (ODTs). However, these conditions are not applicable to drug substances that are chemically unstable against such stressors. Here, we describe a system which enhances the hardness of tablets containing water-insoluble polymers by using high-pressure carbon dioxide (CO2). On screening of 26 polymeric excipients, aminoalkyl methacrylate copolymer E (AMCE) markedly increased tablet hardness (+155N) when maintained in a high-pressure CO2 environment. ODTs containing 10% AMCE were prepared and treatment with 4.0MPa CO2 gas at 25°C for 10min increased the hardness to +30N, whose level corresponded to heating at 70°C for 720min. In addition, we confirmed the effects of CO2 pressure, temperature, treatment time, and AMCE content on the physical properties of ODTs. Optimal pressure of CO2 gas was considered to be approximately 3.5MPa for an AMCE formula, as excessive pressure delayed the disintegration of ODTs. Combination of high-pressure CO2 gas and AMCE is a prospective approach for increasing the tablet hardness for ODTs, and can be conducted without additional heat or moisture stress using a simple apparatus. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Effect of Electronic Toilet System (Bidet) on Anorectal Pressure in Normal Healthy Volunteers: Influence of Different Types of Water Stream and Temperature

    Science.gov (United States)

    Ryoo, Seungbum; Song, Yoon Suk; Seo, Mi Sun; Oh, Heung-Kwon; Choe, Eun Kyung

    2011-01-01

    Although bidets are widely used in Korea, its effects on anorectal pressures have not been studied in detail in terms of the water settings used. Twenty healthy volunteers were placed on a toilet equipped with a bidet, and anorectal pressures were measured with a manometry catheter inserted into the rectum and anal canal before and after using the bidet at different water forces (40, 80, 160, 200 mN), temperatures (24℃ vs 38℃), and water jet widths (narrow vs wide). The pressure at anal high pressure zone decreased from 96.1 ± 22.5 to 81.9 ± 23.3 mmHg at water jet pressure of 40 mN and 38℃ wide water jet (P < 0.001), from 94.3 ± 22.4 to 80.0 ± 24.1 mmHg at water jet pressure of 80 mN and 38℃ narrow water jet (P < 0.001), and from 92.3 ± 22.4 to 79.6 ± 24.7 mmHg at a water jet pressure of 80 mN and 38℃ wide water jet (P < 0.001). At other settings, no significant changes were observed. Our results indicate that, in addition to cleansing effect, bidet could be used to reduce anal resting pressure in the same manner as the traditional warm sitz bath under the conditions of low or medium water jet pressure, a warm water temperature, and a wide type water jet. PMID:21218033

  9. High pressure membrane foulants of seawater, brackish water and river water: Origin assessed by sugar and bacteriohopanepolyol signatures

    KAUST Repository

    Mondamert, Leslie

    2011-01-01

    The present work aimed to study the origin of foulant material recovered on membranes used in water treatment. Firstly, sugar signatures were assessed from the monosaccharide composition. As results were not conclusive, a statistical approach using discriminant analysis was applied to the sugar data set in order to predict the origin of the foulant material. Three groups of various origins (algal, microbial, continental dissolved organic matter) were used as sugar references for the prediction. The results of the computation showed that the origin of reverse osmosis (RO) seawater foulant material is influenced by both the location of the water sources and the season. RO brackish water and nanofiltration river water foulant materials had a terrestrial origin. Secondly, bacteriohopanepolyol signatures indicated that RO seawater foulant material had a marine signature, RO brackish water foulant material had both a marine and a terrestrial origin and the nanofiltration river water foulant material contained only a terrestrial signature. © 2011 Taylor & Francis.

  10. Photolytic removal of DBPs by medium pressure UV in swimming pool water

    DEFF Research Database (Denmark)

    Hansen, Kamilla Marie Speht; Zortea, R.; Piketty, A.

    2013-01-01

    Medium pressure UV is used for controlling the concentration of combined chlorine (chloramines) in many public swimming pools. Little is known about the fate of other disinfection by-products (DBPs) in UV treatment. Photolysis by medium pressure UV treatment was investigated for 12 DBPs reported...

  11. Heat transfer in vertical pipe flow at supercritical pressures of water; Waermeuebergang von Wasser in vertikalen Rohrstroemungen bei ueberkritischem Druck

    Energy Technology Data Exchange (ETDEWEB)

    Loewenberg, M.F.

    2007-05-15

    A new reactor concept with light water at supercritical conditions is investigated in the framework of the European project ''High Performance Light Water Reactor'' (HPLWR). Characteristics of this reactor are the system pressure and the coolant