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Sample records for in-vessel melt water

  1. Numerical modeling of in-vessel melt water interaction in large scale PWR`s

    Energy Technology Data Exchange (ETDEWEB)

    Kolev, N.I. [Siemens AG, KWU NA-M, Erlangen (Germany)

    1998-01-01

    This paper presents a comparison between IVA4 simulations and FARO L14, L20 experiments. Both experiments were performed with the same geometry but under different initial pressures, 51 and 20 bar respectively. A pretest prediction for test L21 which is intended to be performed under an initial pressure of 5 bar is also presented. The strong effect of the volume expansion of the evaporating water at low pressure is demonstrated. An in-vessel simulation for a 1500 MW el. PWR is presented. The insight gained from this study is: that at no time are conditions for the feared large scale melt-water intermixing at low pressure in force, with this due to the limiting effect of the expansion process which accelerates the melt and the water into all available flow paths. (author)

  2. The modeling of core melting and in-vessel corium relocation in the APRIL code

    Energy Technology Data Exchange (ETDEWEB)

    Kim. S.W.; Podowski, M.Z.; Lahey, R.T. [Rensselaer Polytechnic Institute, Troy, NY (United States)] [and others

    1995-09-01

    This paper is concerned with the modeling of severe accident phenomena in boiling water reactors (BWR). New models of core melting and in-vessel corium debris relocation are presented, developed for implementation in the APRIL computer code. The results of model testing and validations are given, including comparisons against available experimental data and parametric/sensitivity studies. Also, the application of these models, as parts of the APRIL code, is presented to simulate accident progression in a typical BWR reactor.

  3. Oxidation effect on steel corrosion and thermal loads during corium melt in-vessel retention

    Energy Technology Data Exchange (ETDEWEB)

    Granovsky, V.S.; Khabensky, V.B.; Krushinov, E.V.; Vitol, S.A.; Sulatsky, A.A.; Almjashev, V.I. [Alexandrov Scientific-Research Technology Institute (NITI), Sosnovy Bor (Russian Federation); Bechta, S.V. [KTH, Stockholm (Sweden); Gusarov, V.V. [SPb State Technology University (SPbGTU), St. Petersburg (Russian Federation); Barrachin, M. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), St Paul lez Durance (France); Bottomley, P.D., E-mail: paul.bottomley@ec.europa.eu [EC-Joint Research Centre, Institute for Transuranium Elements (ITU), Karlsruhe (Germany); Fischer, M. [AREVA GmbH, Erlangen (Germany); Piluso, P. [Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Cadarache, St Paul lez Durance (France)

    2014-10-15

    Highlights: • The METCOR facility simulates vessel steel corrosion in contact with corium. • Steel corrosion rates in UO{sub 2+x}–ZrO{sub 2}–FeO{sub y} coria accelerate above 1050 K. • However corrosion rates can also be limited by melt O{sub 2} supply. • The impact of this on in-vessel retention (IVR) strategy is discussed. - Abstract: During a severe accident with core meltdown, the in-vessel molten core retention is challenged by the vessel steel ablation due to thermal and physicochemical interaction of melt with steel. In accidents with oxidizing atmosphere above the melt surface, a low melting point UO{sub 2+x}–ZrO{sub 2}–FeO{sub y} corium pool can form. In this case ablation of the RPV steel interacting with the molten corium is a corrosion process. Experiments carried out within the International Scientific and Technology Center's (ISTC) METCOR Project have shown that the corrosion rate can vary and depends on both surface temperature of the RPV steel and oxygen potential of the melt. If the oxygen potential is low, the corrosion rate is controlled by the solid phase diffusion of Fe ions in the corrosion layer. At high oxygen potential and steel surface layer temperature of 1050 °C and higher, the corrosion rate intensifies because of corrosion layer liquefaction and liquid phase diffusion of Fe ions. The paper analyzes conditions under which corrosion intensification occurs and can impact on in-vessel melt retention (IVR)

  4. SWR 1000 severe accident control through in-vessel melt retention by external RPV cooling

    Energy Technology Data Exchange (ETDEWEB)

    Kolev, N.I. [Framatome Advanced Nuclear Power, NDSI, Erlangen (Germany)

    2001-07-01

    Framatome Advanced Nuclear Power is being designing a new generation NPP with boiling water reactor SWR1000. Besides of various of modern passive and active safety features the system is also designed for controlling of a postulated severe accident with extreme low probability of occurrence. This work presents the rationales behind the decision to select the external cooling as a safety management strategy during severe accident. Bounding scenery are analyzed regarding the core melting, melt-water interaction during relocation of the melt from the core region into the lower head and the external coolability of the lower head. The conclusion is reached that the external cooling for the SWR1000 is a valuable strategy for accident management during postulated severe accidents. (authors)

  5. Studies on melt-water-structure interaction during severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Sehgal, B.R.; Dinh, T.N.; Okkonen, T.J.; Bui, V.A.; Nourgaliev, R.R.; Andersson, J. [Royal Inst. of Technology, Div. of Nucl. Power Safety, Stockholm (Sweden)

    1996-10-01

    Results of a series of studies, on melt-water-structure interactions which occur during the progression of a core melt-down accident, are described. The emphasis is on the in-vessel interactions and the studies are both experimental and analytical. Since, the studies performed resulted in papers published in proceedings of the technical meetings, and in journals, copies of a set of selected papers are attached to provide details. A summary of the results obtained is provided for the reader who does not, or cannot, venture into the perusal of the attached papers. (au).

  6. In-vessel coolability and retention of a core melt. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Theofanous, T.G.; Liu, C.; Additon, S.; Angelini, S.; Kymaelaeinen, O.; Salmassi, T. [California Univ., Santa Barbara, CA (United States). Center for Risk Studies and Safety

    1996-10-01

    The efficacy of external flooding of a reactor vessel as a severe accident management strategy is assessed for an AP600-like reactor design. The overall approach is based on the Risk Oriented Accident Analysis Methodology (ROAAM), and the assessment includes consideration of bounding scenarios and sensitivity studies, as well as arbitrary parametric evaluations that allow the delineation of the failure boundaries. Quantification of the input parameters is carried out for an AP600-like design, and the results of the assessment demonstrate that lower head failure is physically unreasonable. Use of this conclusion for any specific application is subject to verifying the required reliability of the depressurization and cavity-flooding systems, and to showing the appropriateness (in relation to the database presented here, or by further testing as necessary) of the thermal insulation design and of the external surface properties of the lower head, including any applicable coatings. The AP600 is particularly favorable to in-vessel retention. Some ideas to enhance the assessment basis as well as performance in this respect, for applications to larger and/or higher power density reactors are also provided.

  7. In-vessel coolability and retention of a core melt. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Theofanous, T.G.; Liu, C.; Additon, S.; Angelini, S.; Kymaelaeinen, O.; Salmassi, T. [California Univ., Santa Barbara, CA (United States). Center for Risk Studies and Safety

    1996-10-01

    The efficacy of external flooding of a reactor vessel as a severe accident management strategy is assessed for an AP600-like reactor design. The overall approach is based on the Risk Oriented Accident Analysis Methodology (ROAAM), and the assessment includes consideration of bounding scenarios and sensitivity studies, as well as arbitrary parametric evaluations that allow the delineation of the failure boundaries. Quantification of the input parameters is carried out for an AP600-like design, and the results of the assessment demonstrate that lower head failure is physically unreasonable. Use of this conclusion for any specific application is subject to verifying the required reliability of the depressurization and cavity-flooding systems, and to showing the appropriateness (in relation to the database presented here, or by further testing as necessary) of the thermal insulation design and of the external surface properties of the lower head, including any applicable coatings. The AP600 is particularly favorable to in-vessel retention. Some ideas to enhance the assessment basis as well as performance in this respect, for applications to larger and/or higher power density reactors are also provided.

  8. Validation of the THIRMAL-1 melt-water interaction code

    Energy Technology Data Exchange (ETDEWEB)

    Chu, C.C.; Sienicki, J.J.; Spencer, B.W. [Argonne National Lab., IL (United States)

    1995-09-01

    The THIRMAL-1 computer code has been used to calculate nonexplosive LWR melt-water interactions both in-vessel and ex-vessel. To support the application of the code and enhance its acceptability, THIRMAL-1 has been compared with available data from two of the ongoing FARO experiments at Ispra and two of the Corium Coolant Mixing (CCM) experiments performed at Argonne. THIRMAL-1 calculations for the FARO Scoping Test and Quenching Test 2 as well as the CCM-5 and -6 experiments were found to be in excellent agreement with the experiment results. This lends confidence to the modeling that has been incorporated in the code describing melt stream breakup due to the growth of both Kelvin-Helmholtz and large wave instabilities, the sizes of droplets formed, multiphase flow and heat transfer in the mixing zone surrounding and below the melt metallic phase. As part of the analysis of the FARO tests, a mechanistic model was developed to calculate the prefragmentation as it may have occurred when melt relocated from the release vessel to the water surface and the model was compared with the relevant data from FARO.

  9. In-vessel melt retention as a severe accident management strategy for the Loviisa Nuclear Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Kymaelaeinen, O.; Tuomisto, H. [IVO International Ltd., Vantaa (Finland); Theofanous, T.G. [Univ. of California, Santa Barbara, CA (United States)

    1997-02-01

    The concept of lower head coolability and in-vessel retention of corium has been approved as a basic element of the severe accident management strategy for IVO`s Loviisa Plant (VVER-440) in Finland. The selected approach takes advantage of the unique features of the plant such as low power density, reactor pressure vessel without penetrations at the bottom and ice-condenser containment which ensures flooded cavity in all risk significant sequences. The thermal analyses, which are supported by experimental program, demonstrate that in Loviisa the molten corium on the lower head of the reactor vessel is coolable externally with wide margins. This paper summarizes the approach and the plant modifications being implemented. During the approval process some technical concerns were raised, particularly with regard to thermal loadings caused by contact of cool cavity water and hot corium with the reactor vessel. Resolution of these concerns is also discussed.

  10. Experiments and analyses on melt-structure-water interactions during severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Seghal, B.R.; Dinh, T.N.; Bui, V.A.; Green, J.A.; Nourgaliev, R.R.; Okkonen, T.O.; Dinh, A.T. [Royal Inst. of Tech., Stockholm (Sweden). Div. of Nuclear Power Safety

    1998-04-01

    This report is the final report for the research project Melt Structure Water Interactions (MSWI). It describes results of analytical and experimental studies concerning MSWI during the course of a hypothetical core meltdown accident in a LWR. Emphasis has been placed on phenomena which govern vessel failure mode and timing and the mechanisms and properties which govern the fragmentation and breakup of melt jets and droplets. It was found that: 2-D effects significantly diminished the focusing effect of an overlying metallic layer on top of an oxide melt pool. This result improves the feasibility of in-vessel retention of a melt pool through external cooling of the lower head; phenomena related to hole ablation and melt discharge, in the event of vessel failure, are affected significantly by crust formation; the jet fragmentation process is a function of many related phenomena. The fragmentation rate depends not only on the traditional parameters but also on the melt physical properties, which change as the melt cools down from liquid to solid temperature; film boiling was investigated by developing a two-phase flow model and inserting it in a multi-D fluid dynamics code. It was concluded that the thickness of the film on the surface of a melt jet would be small and that the effects of the film on the process should not be large. This conclusion is contrary to the modeling employed in some other codes. The computer codes were developed and validated against the data obtained in the MSWI Project. The melt vessel interaction thermal analysis code describes the process of melt pool formation and convection and the resulting vessel thermal loadings. In addition, several innovative models were developed to describe the melt-water interaction process. The code MELT-3D treats the melt jet as a collection of particles whose movement is described with a three-dimensional Eulerian formulation. The model (SIPHRA) tracks the melt jet with an additional equation, using the

  11. Charged Water Droplets can Melt Metallic Electrodes

    Science.gov (United States)

    Elton, Eric; Rosenberg, Ethan; Ristenpart, William

    2016-11-01

    A water drop, when immersed in an insulating fluid, acquires charge when it contacts an energized electrode. Provided the electric field is strong enough, the drop will move away to the opposite electrode, acquire the opposite charge, and repeat the process, effectively 'bouncing' back and forth between the electrodes. A key implicit assumption, dating back to Maxwell, has been that the electrode remains unaltered by the charging process. Here we demonstrate that the electrode is physically deformed during each charge transfer event with an individual water droplet or other conducting object. We used optical, electron, and atomic force microscopy to characterize a variety of different metallic electrodes before and after drops were electrically bounced on them. Although the electrodes appear unchanged to the naked eye, the microscopy reveals that each charge transfer event yielded a crater approximately 1 micron wide and 50 nm deep, with the exact dimensions proportional to the applied field strength. We present evidence that the craters are formed by localized melting of the electrodes via Joule heating in the metal and concurrent dielectric breakdown of the surrounding fluid, suggesting that the electrode locally achieves temperatures exceeding 3400°C. Present address: Dept. Materials Sci. Engineering, MIT.

  12. Cloud screening and melt water detection over melting sea ice using AATSR/SLSTR

    Science.gov (United States)

    Istomina, Larysa; Heygster, Georg

    2014-05-01

    With the onset of melt in the Arctic Ocean, the fraction of melt water on sea ice, the melt pond fraction, increases. The consequences are: the reduced albedo of sea ice, increased transmittance of sea ice and affected heat balance of the system with more heat passing through the ice into the ocean, which facilitates further melting. The onset of melt, duration of melt season and melt pond fraction are good indicators of the climate state of the Arctic and its change. In the absence of reliable sea ice thickness retrievals in summer, melt pond fraction retrieval from satellite is in demand as input for GCM as an indicator of melt state of the sea ice. The retrieval of melt pond fraction with a moderate resolution radiometer as AATSR is, however, a non-trivial task due to a variety of subpixel surface types with very different optical properties, which give non-unique combinations if mixed. In this work this has been solved by employing additional information on the surface and air temperature of the pixel. In the current work, a concept of melt pond detection on sea ice is presented. The basis of the retrieval is the sensitivity of AATSR reflectance channels 550nm and 860nm to the amount of melt water on sea ice. The retrieval features extensive usage of a database of in situ surface albedo spectra. A tree of decisions is employed to select the feasible family of in situ spectra for the retrieval, depending on the melt stage of the surface. Reanalysis air temperature at the surface and brightness temperature measured by the satellite sensor are analyzed in order to evaluate the melting status of the surface. Case studies for FYI and MYI show plausible retrieved melt pond fractions, characteristic for both of the ice types. The developed retrieval can be used to process the historical AATSR (2002-2012) dataset, as well as for the SLSTR sensor onboard the future Sentinel-3 mission (scheduled for launch in 2015), to keep the continuity and obtain longer time sequence

  13. EXPERIMENTAL STUDY OF CRITICAL HEAT FLUX WITH ALUMINA-WATER NANOFLUIDS IN DOWNWARD-FACING CHANNELS FOR IN-VESSEL RETENTION APPLICATIONS

    Directory of Open Access Journals (Sweden)

    G. DEWITT

    2013-06-01

    Full Text Available The Critical Heat Flux (CHF of water with dispersed alumina nanoparticles was measured for the geometry and flow conditions relevant to the In-Vessel Retention (IVR situation which can occur during core melting sequences in certain advanced Light Water Reactors (LWRs. CHF measurements were conducted in a flow boiling loop featuring a test section designed to be thermal-hydraulically similar to the vessel/insulation gap in the Westinghouse AP1000 plant. The effects of orientation angle, pressure, mass flux, fluid type, boiling time, surface material, and surface state were investigated. Results for water-based nanofluids with alumina nanoparticles (0.001% by volume on stainless steel surface indicate an average 70% CHF enhancement with a range of 17% to 108% depending on the specific flow conditions expected for IVR. Experiments also indicate that only about thirty minutes of boiling time (which drives nanoparticle deposition are needed to obtain substantial CHF enhancement with nanofluids.

  14. Experiments on melt droplets falling into a water pool

    Energy Technology Data Exchange (ETDEWEB)

    Okkonen, T.; Sehgal, B.R. [Royal Inst. of Tech., Stockholm (Sweden). Div. of Nuclear Power Safety

    1998-01-01

    This paper presents experimental data and analysis related to melt droplets falling into a water pool. A binary CaO-B{sub 2}O{sub 3} melt mixture is used to study the influence of melt superheat and water subcooling on droplet deformation and fragmentation. For the conditions studied (We {<=} 1000), the surface tension of the melt droplet and the film boiling stability greatly affect the fragmentation behaviour. If the melt temperature is between the liquidus and solidus point (mushy zone) or if the film boiling is stable due to a relatively low subcooling, the droplet deformation and fragmentation are mitigated. This behaviour can be related to the effective Weber number (We) of the melt droplet upon entry into the water pool. Similar phenomena can be expected also for interactions of corium (UO{sub 2}-ZrO{sub 2}) and water, which are characterized by a potentially fast transformation of melt into the mushy zone and by particularly stable film boiling. (author)

  15. Continuous melting through a hexatic phase in confined bilayer water

    Science.gov (United States)

    Zubeltzu, Jon; Corsetti, Fabiano; Fernández-Serra, M. V.; Artacho, Emilio

    2016-06-01

    Liquid water is not only of obvious importance but also extremely intriguing, displaying many anomalies that still challenge our understanding of such an a priori simple system. The same is true when looking at nanoconfined water: The liquid between constituents in a cell is confined to such dimensions, and there is already evidence that such water can behave very differently from its bulk counterpart. A striking finding has been reported from computer simulations for two-dimensionally confined water: The liquid displays continuous or discontinuous melting depending on its density. In order to understand this behavior, we have analyzed the melting exhibited by a bilayer of nanoconfined water by means of molecular dynamics simulations. At high density we observe the continuous melting to be related to the phase change of the oxygens only, with the hydrogens remaining liquidlike throughout. Moreover, we find an intermediate hexatic phase for the oxygens between the liquid and a triangular solid ice phase, following the Kosterlitz-Thouless-Halperin-Nelson-Young theory for two-dimensional melting. The liquid itself tends to maintain the local structure of the triangular ice, with its two layers being strongly correlated yet with very slow exchange of matter. The decoupling in the behavior of the oxygens and hydrogens gives rise to a regime in which the complexity of water seems to disappear, resulting in what resembles a simple monoatomic liquid. This intrinsic tendency of our simulated water may be useful for understanding novel behaviors in other confined and interfacial water systems.

  16. Melt water-driven gully formation in Moni Crater, Mars

    Science.gov (United States)

    Glines, N. H.; Gulick, V. C.; Freeman, P. M.

    2015-12-01

    The southern mid-latitude 5-km diameter Moni Crater (47S, 18.5E) in Noachis Terra is typical of many small craters of this latitude, containing both gullies on its walls and arcuate ridges on its floor. Interpreted by Howard (2003) and others as remnant terminal moraines, these ridges are located at the distal margins of the gullies' debris aprons, suggesting a possible association in their formation. Our results suggest that these arcuate ridges might result from the downslope movement of ice-rich deposits that pushed pre-existing ice-rich crater floor deposits into a moraine-like ridge. The pre-existing floor deposits can be interpreted to be a form of sublimated Concentric Crater Fill (CCF), which would have been among the first ice deposits to erode the Moni Crater walls. If we assume the arcuate ridges to be glacial moraines, then we can also assume the same processes that elevated the ridges also provided melt water to form the gullies. There is evidence that water and ice deposit-related processes incised the gully headwalls, exposing bedrock, plucking boulders, and initiating fractures, through ice-wedging or surface abrasion. HiRISE images (~25cm/pixel) show shallow gullies extending several tens of meters beyond the crater rim, exploiting possible fractures or lineation in the rock. Melt water from these ice deposits, or snow melt, is a potential gully formation mechanism that would be consistent with the shallow runoff-like drainage morphology extending above the gully alcoves and beyond the crater rim. An initial phase of rapid melt water flows would also explain the wider degraded remnant channels we see on the crater slopes. The more gradual melting of ice frozen around headwall rocks could explain a secondary phase of melt water flows that form the more-recent channels.

  17. Drain line melt through experiment under water-free condition

    Energy Technology Data Exchange (ETDEWEB)

    Nakada, Kotaro [Nuclear Engineering Lab., Toshiba Corp., Kawasaki, Kanagawa (Japan); Jaeckel, Bernd; Hirschmann, Harald; Patorski, Jacek; Duijvestijn, Guus

    1999-07-01

    In order to investigate the behavior of a BWR drain line attacked by an oxidic melt, the experiment, CORVIS (Corium Reactor Vessel Interaction Studies) 03/2 was performed. The drain line tube was formed according to the design of an existing BWR. Aluminum oxide was used as the core melt substitute. The melt with an initial temperature of 2518 to 2543 K flowed into the water-free drain line and filled it on entire length of 7012 mm. The melt would have penetrated even further it the melt flow was not stopped by a steel plug at the tube end. The drain line did not fail but was distorted at the high temperature and elongated by 50 mm by thermoplastic deformation under its dead weight. Maximum surface temperature of 1323 K were measured near the drain line welding nozzle. It was concluded that the drain was torn off at higher internal pressure under the same thermal conditions. Temperature histories indicate that a crust was formed on the test plate screening temporarily the steel structures against melting. (author)

  18. Constraints from Water on Mantle Melting and Slab Fluid Composition

    Science.gov (United States)

    Plank, T.; Wade, J.

    2005-12-01

    Water drives mantle melting and fluid migration in subduction zones, but most models for these phenomena have been developed without constraints from water measurements in arc magmas. For example, the Central American volcanic arc (CAVA) records systematic variations in La/Yb, Ba/La and d18O, and these proxies have been used to predict the extent of mantle melting during decompression [1] and water-addition [2]. Here we use water concentrations in olivine-hosted melt inclusions from arc tephra, along with estimates derived from a clinopyroxene hygrometer [3], to test different models for mantle melting and slab fluid composition along the CAVA (from Nicaragua to Costa Rica). We use Ti as a proxy for mantle melt fraction (F) and invert H2O concentrations in CAVA magmas to obtain those in the mantle source (H2Oo), as in [4]. The relationship between F and H2Oo is nominally linear for Costa Rica mantle, with wet melting productivity dF/dH2O = 30 (wt%/wt%), higher than that used in [2], but consistent with experimentally-determined and MELTS-calculated productivity at 50 degrees above the dry solidus. This predicts mantle temperature beneath Costa Rica of at least 1350°C, and allows for a small (1-2% F) decompression-melting contribution, relative to the wet melting contribution (8-20% F). The percent of wet melting correlates locally with Ba/La, but not regionally, and so the use of Ba/La as a wet melting proxy [1] should be limited to single volcanoes or clusters. The water content of the CAVA melting region varies from 2500-9000 ppm H2O but does not decrease monotonically from Nicaragua to Costa Rica as does Ba/La. The relationship between H2Oo and Ba/La is thus complex, and requires a large along-strike decrease in Ba/La and H2O/La in the slab fluids towards the southeast. Such variation appears to be driven largely by La concentration, reflecting more dilute fluids (higher H2O/La) beneath Nicaragua and more solute-rich fluids (e.g., sediment melts with high La/ H

  19. Experimental studies of interaction between water and albite melts

    Institute of Scientific and Technical Information of China (English)

    SUN; Qiang; (孙樯); XIE; Hongsen; (谢鸿森); ZHENG; Haifei; (郑海飞); GUO; Jie; (郭捷); DING; Dongye,(丁东业)

    2002-01-01

    On the basis of FTIR and Raman spectra studies on hydrous albite glasses, it is found that there exist two water solubility mechanisms in albite melts simultaneously. On the one hand, water interacts with Al -O°-Al to produce the Q3 Al-OH, leading to depolymerization, and this results in the appearance of 4500 cm(1 in FTIR spectra and 900 cm(1 in Raman spectra. On the other hand, the exchange of H+ in water with Na+ in albite melt as charge-balancing cation occurs at the same time. In the initial stage, the production of Al -OH is the dominant solubility mechanism, at the stage of higher water contents, the exchange of H+ with Na+ becomes the important dissolution mechanism. The dissolution of water into albite melt can be expressed as H2O+ 3NaAlSi3O8 = 2NaAl(OH)Si3O7.5 +HAlSi3O8 +NaOH.

  20. Water diffusion in Mount Changbai peralkaline rhyolitic melt

    Science.gov (United States)

    Wang, Haoyue; Xu, Zhengjiu; Behrens, Harald; Zhang, Youxue

    2009-10-01

    Diffusion couple experiments with wet half (up to 4.6 wt%) and dry half were carried out at 789-1,516 K and 0.47-1.42 GPa to investigate water diffusion in a peralkaline rhyolitic melt with major oxide concentrations matching Mount Changbai rhyolite. Combining data from this work and a related study, total water diffusivity in peralkaline rhyolitic melt can be expressed as: D_{{{text{H}}_{ 2} {text{O}}_{text{t}} }} = D_{{{text{H}}_{ 2} {text{O}}_{text{m}} }} left( {1 - 0.5 - X/{sqrt {[4exp (3110/T - 1.876) - 1](X - X^{2 ) + 0.25} }}} right), {text{with}}D_{{{text{H}}_{ 2} {text{O}}_{text{m}} }} = exp left[ { - 1 2. 7 8 9- 13939/T - 1229.6P/T + ( - 27.867 + 60559/T)X} right], where D is in m2 s-1, T is the temperature in K, P is the pressure in GPa, and X is the mole fraction of water and calculated as X = ( C/18.015)/( C/18.015 + (100 - C)/33.14), where C is water content in wt%. We recommend this equation in modeling bubble growth and volcanic eruption dynamics in peralkaline rhyolitic eruptions, such as the 1,000- ad eruption of Mount Changbai in North East China. Water diffusivities in peralkaline and metaluminous rhyolitic melts are comparable within a factor of 2, in contrast with the 1.0-2.6 orders of magnitude difference in viscosities. The decoupling of diffusivity of neutral molecular species from melt viscosity, i.e., the deviation from the inversely proportional relationship predicted by the Stokes-Einstein equation, might be attributed to the small size of H2O molecules. With distinct viscosities but similar diffusivity, bubble growth controlled by diffusion in peralkaline and metaluminous rhyolitic melts follows similar parabolic curves. However, at low confining pressure or low water content, viscosity plays a larger role and bubble growth rate in peralkaline rhyolitic melt is much faster than that in metaluminous rhyolite.

  1. Analysis of Water Recovery Rate from the Heat Melt Compactor

    Science.gov (United States)

    Balasubramaniam, R.; Hegde, U.; Gokoglu, S.

    2013-01-01

    Human space missions generate trash with a substantial amount of plastic (20% or greater by mass). The trash also contains water trapped in food residue and paper products and other trash items. The Heat Melt Compactor (HMC) under development by NASA Ames Research Center (ARC) compresses the waste, dries it to recover water and melts the plastic to encapsulate the compressed trash. The resulting waste disk or puck represents an approximately ten-fold reduction in the volume of the initial trash loaded into the HMC. In the current design concept being pursued, the trash is compressed by a piston after it is loaded into the trash chamber. The piston face, the side walls of the waste processing chamber and the end surface in contact with the waste can be heated to evaporate the water and to melt the plastic. Water is recovered by the HMC in two phases. The first is a pre-process compaction without heat or with the heaters initially turned on but before the waste heats up. Tests have shown that during this step some liquid water may be expelled from the chamber. This water is believed to be free water (i.e., not bound with or absorbed in other waste constituents) that is present in the trash. This phase is herein termed Phase A of the water recovery process. During HMC operations, it is desired that liquid water recovery in Phase A be eliminated or minimized so that water-vapor processing equipment (e.g., condensers) downstream of the HMC are not fouled by liquid water and its constituents (i.e., suspended or dissolved matter) exiting the HMC. The primary water recovery process takes place next where the trash is further compacted while the heated surfaces reach their set temperatures for this step. This step will be referred to herein as Phase B of the water recovery process. During this step the waste chamber may be exposed to different selected pressures such as ambient, low pressure (e.g., 0.2 atm), or vacuum. The objective for this step is to remove both bound and

  2. Deformation mechanism of nanoporous materials upon water freezing and melting

    Science.gov (United States)

    Erko, Maxim; Wallacher, Dirk; Paris, Oskar

    2012-10-01

    Temperature-induced non-monotonous reversible deformation of water-filled nanoporous silica materials is investigated experimentally using in-situ small-angle x-ray scattering. The influence of freezing and melting in the nanopores on this deformation is treated quantitatively by introducing a simple model based on the Gibbs-Thomson equation and a generalized Laplace-pressure. The physical origin of the melting/freezing induced pore lattice deformation is found to be exactly the same as for capillary condensation/evaporation, namely the curved phase boundary due to the preferred wetting of the pore walls by the liquid phase. As a practical implication, elastic properties of the nanoporous framework can be determined from the temperature-deformation curves.

  3. Phenomenological Studies on Melt-Structure-Water Interactions (MSWI) during Postulated Severe Accidents: Year 2004 Activity. APRI 5 report

    Energy Technology Data Exchange (ETDEWEB)

    Sehgal, B.R.; Park, H.S.; Nayak, A.K.; Hansson, R.C.; Chiferaw, D.; Stepanyan, A.; Rao, R.S.; Karbojian, A. [Royal Inst. of Technology, Stockholm (Sweden). Div. of Nuclear Power Safety

    2005-04-01

    This report presents descriptions of the major results obtained in the research program 'Melt-Structure-Water Interaction (MSWI)' at NPS/RIT during the year 2004. The primary objectives of the MSWI Project in year 2004 were to study (1) the in-vessel and exvessel melt/debris bed coolability process when melt is flooded with water, and (2) the energetics and characteristics of steam explosions. Our general approaches are to establish scaling relationships so that the data obtained in the experiments could be extended to prototypical accident geometries and conditions, develop phenomenological or computational models for the processes under investigation and validate the existing and newly developed models against data obtained at RIT and at other laboratories. In 2004, several experimental programs, such as the COMECO (Corium MElt COolability), POMECO (POrous MEdia COolability) and MISTEE (Micro-Interactions in STeam Explosion Experiments) programs were continued. The SIMECO (Simulation of MElt Coolability) program was restarted in 2004. The construction of the POMECO-GRAND (POrous MEdia COolability) facility was delayed due to lack of finances. However, existing POMECO facility was modified to study 3-D effects on debris coolability. In this report, the results from the COMECO experiment with high temperature oxidic melt, from the POMECO experiments for the multi-dimensional effects on debris bed coolability, from the SIMECO experiment for three-layer pool configuration and from the MISTEE experiments for steam explosion characteristics and loads are described. For analytical efforts, results from the COMETA code for the entire process of the steam explosions are discussed.

  4. Electrical capacitance volume tomography for measurement soil water infiltration in vessel experiments

    Institute of Scientific and Technical Information of China (English)

    Muhammad Mukhlisin; Marlin Ramadhan Baidillah; Mohd Raihan Taha

    2014-01-01

    Electrical capacitance volume tomography (ECVT) is a recently-developed technique for real-time, non-invasive 3D monitoring of processes involving materials with strong contrasts in dielectric permittivity. This work is first application of the method to visualization of water flow in soil. We describe the principles behind the method, and then demonstrate its use with a simple laboratory infiltration experiment. 32 ECVT sensors were installed on the sides of an empty PVC column. Water was poured into the column at a constant rate, and ECVT data were collected every second. The column was then packed with dry sand and again supplied with water at a constant rate with data collected every second. Data were analyzed to give bulk average water contents, which proved consistent with the water supply rates. Data were also analyzed to give 3D images (216 voxels) allowing visualization of the water distribution during the experiments. Result of this work shows that water infiltration into the soil, wall flow, progress of the unstable wetting front and the final water distribution are clearly visible.

  5. Water isotopic ratios from a continuously melted ice core sample

    CERN Document Server

    Gkinis, V; Blunier, T; Bigler, M; Schüpbach, S; Kettner, E; Johnsen, S J

    2014-01-01

    A new technique for on-line high resolution isotopic analysis of liquid water, tailored for ice core studies is presented. We built an interface between a Wavelength Scanned Cavity Ring Down Spectrometer (WS-CRDS) purchased from Picarro Inc. and a Continuous Flow Analysis (CFA) system. The system offers the possibility to perform simultaneous water isotopic analysis of $\\delta^{18}$O and $\\delta$D on a continuous stream of liquid water as generated from a continuously melted ice rod. Injection of sub ${\\mu}$l amounts of liquid water is achieved by pumping sample through a fused silica capillary and instantaneously vaporizing it with 100% efficiency in a home made oven. A calibration procedure allows for proper reporting of the data on the VSMOW--SLAP scale. Application of spectral methods yields the combined uncertainty of the system at below 0.1 permil and 0.5 permil for $\\delta^{18}$O and $\\delta$D, respectively. This performance is comparable to that achieved with mass spectrometry. Dispersion of the sampl...

  6. Shifts in coastal Antarctic marine microbial communities during and after melt water-related surface stratification

    NARCIS (Netherlands)

    Piquet, Anouk M. -T.; Bolhuis, Henk; Meredith, Michael P.; Buma, Anita G. J.

    2011-01-01

    Antarctic coastal waters undergo major physical alterations during summer. Increased temperatures induce sea-ice melting and glacial melt water input, leading to strong stratification of the upper water column. We investigated the composition of micro-eukaryotic and bacterial communities in Ryder Ba

  7. Water isotopic ratios from a continuously melted ice core sample

    Directory of Open Access Journals (Sweden)

    V. Gkinis

    2011-11-01

    Full Text Available A new technique for on-line high resolution isotopic analysis of liquid water, tailored for ice core studies is presented. We built an interface between a Wavelength Scanned Cavity Ring Down Spectrometer (WS-CRDS purchased from Picarro Inc. and a Continuous Flow Analysis (CFA system. The system offers the possibility to perform simultaneuous water isotopic analysis of δ18O and δD on a continuous stream of liquid water as generated from a continuously melted ice rod. Injection of sub μl amounts of liquid water is achieved by pumping sample through a fused silica capillary and instantaneously vaporizing it with 100% efficiency in a~home made oven at a temperature of 170 °C. A calibration procedure allows for proper reporting of the data on the VSMOW–SLAP scale. We apply the necessary corrections based on the assessed performance of the system regarding instrumental drifts and dependance on the water concentration in the optical cavity. The melt rates are monitored in order to assign a depth scale to the measured isotopic profiles. Application of spectral methods yields the combined uncertainty of the system at below 0.1‰ and 0.5‰ for δ18O and δD, respectively. This performance is comparable to that achieved with mass spectrometry. Dispersion of the sample in the transfer lines limits the temporal resolution of the technique. In this work we investigate and assess these dispersion effects. By using an optimal filtering method we show how the measured profiles can be corrected for the smoothing effects resulting from the sample dispersion. Considering the significant advantages the technique offers, i.e. simultaneuous measurement of δ18O and δD, potentially in combination with chemical components that are traditionally measured on CFA systems, notable reduction on analysis time and power consumption, we consider it as an alternative to traditional isotope ratio mass spectrometry with the possibility to

  8. Water isotopic ratios from a continuously melted ice core sample

    Directory of Open Access Journals (Sweden)

    V. Gkinis

    2011-06-01

    Full Text Available A new technique for on-line high resolution isotopic analysis of liquid water, tailored for ice core studies is presented. We build an interface between an Infra Red Cavity Ring Down Spectrometer (IR-CRDS and a Continuous Flow Analysis (CFA system. The system offers the possibility to perform simultaneuous water isotopic analysis of δ18O and δD on a continuous stream of liquid water as generated from a continuously melted ice rod. Injection of sub μl amounts of liquid water is achieved by pumping sample through a fused silica capillary and instantaneously vaporizing it with 100 % efficiency in a home made oven at a temperature of 170 °C. A calibration procedure allows for proper reporting of the data on the VSMOW scale. We apply the necessary corrections based on the assessed performance of the system regarding instrumental drifts and dependance on humidity levels. The melt rates are monitored in order to assign a depth scale to the measured isotopic profiles. Application of spectral methods yields the combined uncertainty of the system at below 0.1 ‰ and 0.5 ‰ for δ18O and δD, respectively. This performance is comparable to that achieved with mass spectrometry. Dispersion of the sample in the transfer lines limits the resolution of the technique. In this work we investigate and assess these dispersion effects. By using an optimal filtering method we show how the measured profiles can be corrected for the smoothing effects resulting from the sample dispersion. Considering the significant advantages the technique offers, i.e. simultaneuous measurement of δ18O and δD, potentially in combination with chemical components that are traditionally measured on CFA systems, notable reduction on analysis time and power consumption, we consider it as an alternative to traditional isotope ratio mass spectrometry with the possibility to be deployed for field ice core studies. We present data acquired in the

  9. The responses of hydro-environment system in the Second Songhua River Basin to melt water

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the continuous monitoring data of hydrology and water quality in the period from 1972 to 1997, the responses of hydro-environment system to melt water in the Second Songhua River basin were derived. Because of melt water, the water quality in the Second Songhua River is good and changes very except that the contents of Hg and Mn in the water are higher. The contribution of melt water to the water fluxes in the Second Songhua River basin is distinct: the water flow in April increases remarkably, reaches the peak in the upper reaches. The pollutant contributions and water pollution indices (WPIs) of the Second Songhua River in April are high in the upper reaches while that in the lower reaches are low. The responses of hydro-environment system to melt water of that basin are affected by content of packed snow and the underlining surface systems.

  10. Effect of boiling regime on melt stream breakup in water

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, B.W.; Gabor, J.D.; Cassulo, J.C.

    1986-01-01

    A study has been performed examining the breakup and mixing behavior of an initially coherent stream of high-density melt as it flows downward through water. This work has application to the quenching of molten core materials as they drain downward during a postulated severe reactor accident. The study has included examination of various models of breakup distances based upon interfacial instabilities dominated either by liquid-liquid contact or by liquid-vapor contact. A series of experiments was performed to provide a data base for assessment of the various modeling approaches. The experiments involved Wood's metal (T/sub m/ = 73/sup 0/C, rho = 9.2 g/cm/sup 3/, d/sub j/ = 20 mm) poured into a deep pool of water. The temperature of the water and wood's metal were varied to span the range from single-phase, liquid-liquid contact to the film boiling regime. Experiment results showed that breakup occurred largely as a result of the spreading and entrainment from the leading edge of the jet. However, for streams of sufficient lengths a breakup length could be discerned at which there was no longer a coherent central core of the jet to feed the leading edge region. The erosion of the vertical trailing column is by Kelvin-Helmoltz instabilities and related disengagement of droplets from the jet into the surrounding fluid. For conditions of liquid-liquid contact, the breakup length has been found to be about 20 jet diameters; when substantial vapor is produced at the interface due to heat transfer from the jet to the water, the breakup distance was found to range to as high as 50 jet diameters. The former values are close to the analytical prediction of Taylor, whereas the latter values are better predicted by the model of Epstein and Fauske.

  11. A phenomenological analysis of melt progression in the lower head of a pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, J.M., E-mail: jean-marie.seiler@cea.fr [CEA, DEN, DTN, F-38054 Grenoble (France); Tourniaire, B. [EDF/Septen, Lyon (France)

    2014-03-15

    Highlights: • We propose a phenomenological description of melt progression into the lower head. • We examine changes in heat loads on the vessel. • Heat loads are more severe than emphasized by the bounding situation assumption. • Both primary circuit and ex-vessel reflooding are necessary for in-vessel retention. • Vessel failure conditions are examined. - Abstract: The analysis of in-vessel corium cooling (IVC) and retention (IVR) involves the description of very complex and transient physical phenomena. To get round this difficulty, “bounding” situations are often emphasized for the demonstration of corium coolability, by vessel flooding and/or by reactor pit flooding. This approach however comes up against its own limitations. More realistic melt progression scenarios are required to provide plausible corium configurations and vessel failure conditions. Work to develop more realistic melt progression scenarios has been done at CEA, in collaboration with EDF. Development has concentrated on the French 1300 MWe PWR, considering both dry scenarios and the possibility of flooding of the RPC (reactor primary circuit) and/or the reactor pit. The models used for this approach have been derived from the analysis of the TMI2 accident and take benefit from the lessons derived from several programs related to pool thermal hydraulics (BALI, COPO, ACOPO, etc.), material interactions (RASPLAV, MASCA), critical heat flux (CHF) on the external surface of the vessel (KAIST, SULTAN, ULPU), etc. Important conclusions of this work are as follows: (a)After the start of corium melting and onset of melt formation in the core at low pressure (∼1 to 5 bars), it seems questionable that RPV (reactor pressure vessel) reflooding alone would be sufficient to achieve corium retention in the vessel; (b)If the vessel is not cooled externally, it may fail due to local heat-up before the whole core fuel inventory is relocated in the lower head; (c)Even if the vessel is

  12. Water Recovery with the Heat Melt Compactor in a Microgravity Environment

    Science.gov (United States)

    Golliher, Eric L.; Goo, Jonathan; Fisher, John

    2015-01-01

    The Heat Melt Compactor is a proposed utility that will compact astronaut trash, extract the water for eventual re-use, and form dry square tiles that can be used as additional ionizing radiation shields for future human deep space missions. The Heat Melt Compactor has been under development by a consortium of NASA centers. The downstream portion of the device is planned to recover a small amount of water while in a microgravity environment. Drop tower low gravity testing was performed to assess the effect of small particles on a capillary-based water/air separation device proposed for the water recovery portion of the Heat Melt Compactor.

  13. Contrasting patterns of river runoff and sea-ice melted water in the Canada Basin

    Institute of Scientific and Technical Information of China (English)

    TONG Jinlu; CHEN Min; QIU Yusheng; LI Yanping; CAO Jianping

    2014-01-01

    The fractions of river runoff and sea-ice melted water in the Canada Basin in summer 2003 were determined by the salinity-δ18O system. The fraction of river runoff (fR) was high in the upper 50 m of the water column and decreased with depth and latitude. The signals of the river runoff were confined to water depths above 200 m. The total amount of river runoff in the Canada Basin was higher than that in other arctic seas, indi-cating that the Canada Basin is a main storage region for river runoff. The penetration depth of the sea-ice melted water was less than 50 m to the south of 78°N, while it was about 150 m to the north of 78°N. The total amount of sea-ice melted water was much higher to the north of 78°N than to the south of 78°N, indicating the sea-ice melted waters accumulated on the ice edge. The abundant sea-ice melted water on the ice edge was attributed to the earlier melted water in the southern Canada Basin and transported by the Beaufort Gyre or the reinforced melting of sea ice by solar radiation in the polynya.

  14. Melting of short 1-alcohol monolayers on water: Thermodynamics and x-ray scattering studies

    DEFF Research Database (Denmark)

    Berge, B.; Konovalov, O.; Lajzerowicz, J.

    1994-01-01

    From surface tension measurements we extract the melting entropy Delta S-2D of fatty-alcohol monolayers on water. Delta S-2D is found to be 4(kB)/mol lower than in the bulk. Because of the role of the conformational entropy, the melting transition is discontinuous for long chains, but tends...

  15. Drag Moderation by the Melting of an Ice Surface in Contact with Water

    Science.gov (United States)

    Vakarelski, Ivan U.; Chan, Derek Y. C.; Thoroddsen, Sigurdur T.

    2015-07-01

    We report measurements of the effects of a melting ice surface on the hydrodynamic drag of ice-shell-metal-core spheres free falling in water at a Reynolds of number Re ˜2 ×104- 3 ×105 and demonstrate that the melting surface induces the early onset of the drag crisis, thus reducing the hydrodynamic drag by more than 50%. Direct visualization of the flow pattern demonstrates the key role of surface melting. Our observations support the hypothesis that the drag reduction is due to the disturbance of the viscous boundary layer by the mass transfer from the melting ice surface.

  16. Drag Moderation by the Melting of an Ice Surface in Contact with Water

    KAUST Repository

    Vakarelski, Ivan Uriev

    2015-07-24

    We report measurements of the effects of a melting ice surface on the hydrodynamic drag of ice-shell-metal-core spheres free falling in water at a Reynolds of number Re∼2×104–3×105 and demonstrate that the melting surface induces the early onset of the drag crisis, thus reducing the hydrodynamic drag by more than 50%. Direct visualization of the flow pattern demonstrates the key role of surface melting. Our observations support the hypothesis that the drag reduction is due to the disturbance of the viscous boundary layer by the mass transfer from the melting ice surface.

  17. Experiments on water/melt explosions, nature of products, and models of dispersal

    Science.gov (United States)

    Sheridan, M. F.; Wohletz, K. H.

    1984-01-01

    Experiments were carried out in a steel pressure device using controlled amounts of water and thermite melt to examine the mechanical energy released on explosive mixing following the initial contact of the two materials. An experimental design was used to allow the direct calculation of the mechanical energy by the dynamic lift of the device as recorded both optically and physically. A large number of experiments were run to accurately determine the optimum mixture of water and melt for the conversion of thermal to mechanical energy. The maximum efficiency observed was about 12% at a water/thermite mass ratio of 0.50. These experiments are the basis for the development of models of hydroexplosions and melt fragmentation. Particles collected from the experimental products are similar in size and shape to pyroclasts produced by much larger hydrovolcanic explosions. Melt rupture at optimum ratios produces very fine particles whereas rupture at high or low water/melt ratios produces large melt fragments. Grain surface textures in the experimental products are also related to the water/melt ratio and the mechanism of explosive mixing. It is thus possible to have qualitative information about the nature of the explosion from the sizes and shapes of the fragments produced.

  18. Modeling the Spreading of Glacial Melt Water from the Amundsen and Bellingshausen Seas

    Science.gov (United States)

    Nakayama, Y.; Timmermann, R.; Rodehacke, C. B.; Schröder, M.; Hellmer, H. H.

    2014-12-01

    The ice shelves and glaciers of the West Antarctic Ice Sheet (WAIS) are rapidly thinning, especially in the Amundsen Sea (AS) and Bellingshausen Sea (BS). The high basal melting of these small ice shelves is caused by relatively warm Circumpolar Deep Water (CDW) that, based on observations, mainly intrudes via two submarine glacial troughs located at the eastern and central AS continental shelf break. When CDW reaches the grounding line of the fringing glaciers, it melts the glaciers and forms buoyant melt water plumes. As the glacial melt becomes part of the AS shelf circulation, it may cause a freshening of the shelf water locally as well as remotely in the Ross Sea (RS). To test whether the observed freshening of the RS is a consequence of the enhanced basal melting of AS ice shelves, we use Finite-Element Sea-ice/ice-shelf/Ocean Model (FESOM) with a horizontal resolution of 2-10 km on the AS and BS continental shelves. The model is forced with 6-hourly atmospheric data from the National Centers for Environmental Prediction Climate Forecast System Reanalysis (NCEP-CFSR) for the period 1979-1988. The model results show bottom temperatures in the AS and BS close to observations, and basal melt rates of AS and BS ice shelves consistent with other observation-based estimates. Using several independent virtual passive tracers to identify pathways of the glacial melt, we find that the melt water from the ice shelves in the AS flows towards the Ross Ice Shelf front. After 10 years of simulation, about half of the melt water in the Ross Sea originates from the Getz Ice Shelf. Further, we investigate the sensitivity of the melt water transport into the RS associated with the strength of the basal melt water flux. When this flux is increased by 30%, the transport of glacial melt into the RS more than doubles, supporting the idea that the basal melting of AS and BS ice shelves is one of the main reasons for the freshening of the RS continental shelf.

  19. Melt water interaction tests. PREMIX tests PM10 and PM11

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, A.; Schuetz, W.; Will, H. [Forschungszentrum Karlsruhe Inst. fuer Reaktorsicherheit, Karlsruhe (Germany)

    1998-01-01

    A series of experiments is being performed in the PREMIX test facility in which the mixing behaviour is investigated of a hot alumina melt discharged into water. The major parameters have been: the melt mass, the number of nozzles, the distance between the nozzle and the water, and the depth of the water. The paper describes the last two tests in which 20 kg of melt were released through one and three nozzles, respectively, directly into the water whose depth was 500 mm. The melt penetration and the associated phenomena of mixing are described by means of high-speed films and various measurements. The steam production and, subsequently, the pressure increased markedly only after the melt had reached the bottom of the pool. Spreading of the melt across the bottom caused violent boiling in both tests. Whereas the boiling lasted for minutes in the single-jet test, a steam explosion occurred in the triple-jet test about one second after the start of melt penetration. (author)

  20. A Study on Solidification and Melting of Water around Spine-fin Tube

    Science.gov (United States)

    Hirasawa, Yoshio; Takegoshi, Eisyun; Konya, Hiroshi; Tajima, Ikuo

    The authors have studied the phase change process of composite materials containing conductive solids in order to improve the heat transfer characteristics of phase change materials. In this study, experiments for the solidification and melting of water around a spine-fin tube are carried out, and the phase change volume and temperature distribution in the water are measured. As a result, the solidification and melting process are promoted considerably by the heat conduction of the fin and the natural convection in the lower side of the spine-fin tube for the melting process.

  1. Experiments on explosive interactions between zirconium-containing melt and water (ZREX).

    Energy Technology Data Exchange (ETDEWEB)

    Cho, D. H.

    1998-04-10

    The results of two series of experiments on explosive interactions between zirconium-containing melt and water are described. The first series of experiments involved dropping 1-kg batches of zirconium-zirconium dioxide mixture melt into a column of water while the second series employed 1.2-kg batches of zirconium-stainless steel mixture melt. Explosions took place only in those tests which were externally triggered. While the extent of zirconium oxidation in the triggered experiments was quite large, the explosion energies estimated from the experimental measurements were found to be small compared to the combined thermal and chemical energy available.

  2. Identification of glacial melt water runoff in a karstic environment and its implication for present and future water availability

    Directory of Open Access Journals (Sweden)

    D. Finger

    2013-03-01

    Full Text Available Glaciers all over the world are expected to continue to retreat due to the global warming throughout the 21st century. Consequently, future seasonal water availability might become scarce once glacier areas have declined below a certain threshold affecting future water management strategies. Particular attention should be paid to glaciers located in a karstic environment, as parts of the melt water can be drained by souterrain karst systems. In this study tracer experiments, karst modeling and glacier melt modeling are combined in order to identify flow paths in a high alpine, glacierized, karstic environment (Glacier de la Plaine Morte, Switzerland and to investigate current and predict future downstream water availability. Flow paths through the karst underground were determined with natural and fluorescent tracers. Subsequently, tracer results and geologic information were assembled in a karst model. Finally, glacier melt projections driven with a climate scenario were performed to discuss future water availability in the area surrounding the glacier. The results suggest that during late summer glacier melt water is rapidly drained through well-developed channels at the glacier bottom to the north of the glacier, while during low flow season melt water enters into the karst and is drained to the south. Climate change projections reveal that by the end of the century glacier melt will be significantly reduced in the summer, jeopardizing water availability in glacier-fed karst springs.

  3. Investigation on Melt-Structure-Water Interactions (MSWI) during severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Sehgal, B.R.; Yang, Z.L.; Dinh, T.N.; Nourgaliev, R.R.; Bui, V.A.; Haraldsson, H.O.; Li, H.X.; Konovakhin, M.; Paladino, D.; Leung, W.H [Royal Inst. of Tech., Stockholm (Sweden). Div. of Nuclear Power Safety

    1999-08-01

    This report is the final report for the work performed in 1998 in the research project Melt Structure Water Interactions (MSWI), under the auspices of the APRI Project, jointly funded by SKI, HSK, USNRC and the Swedish and Finnish power companies. The present report describes results of advanced analytical and experimental studies concerning melt-water-structure interactions during the course of a hypothetical severe core meltdown accident in a light water reactor (LWR). Emphasis has been placed on phenomena and properties which govern the fragmentation and breakup of melt jets and droplets, melt spreading and coolability, and thermal and mechanical loadings of a pressure vessel during melt-vessel interaction. Many of the investigations performed in support of this project have produced papers which have been published in the proceedings of technical meetings. A short summary of the results achieved in these papers is provided in this overview. Both experimental and analytical studies were performed to improve knowledge about phenomena of melt-structure-water interactions. We believe that significant technical advances have been achieved during the course of these studies. It was found that: the solidification has a strong effect on the drop deformation and breakup. Initially appearing at the drop surface and, later, thickening inwards, the solid crust layer dampens the instability waves on the drop surface and, therefore, hinders drop deformation and breakup. The drop thermal properties also affect the thermal behavior of the drop and, therefore, have impact on its deformation behavior. The jet fragmentation process is a function of many related phenomena. The fragmentation rate depends not only on the traditional parameters, e.g. the Weber number, but also on the melt physical properties, which change as the melt cools down from the liquidus to the solidus temperature. Additionally, the crust formed on the surface of the melt jet will also reduce the propensity

  4. Experimental investigation of 150-KG-scale corium melt jet quenching in water

    Energy Technology Data Exchange (ETDEWEB)

    Magallon, D.; Hohmann, H.

    1995-09-01

    This paper compares and discusses the results of two large scale FARO quenching tests known as L-11 and L-14, which involved, respectively, 151 kg of W% 76.7 UO{sub 2} + 19.2 ZrO{sub 2} + 4.1 Zr and 125 kg of W% 80 UO{sub 2} + 20 ZrO{sub 2} melts poured into 600-kg, 2-m-depth water at saturation at 5.0 MPa. The results are further compared with those of two previous tests performed using a pure oxidic melt, respectively 18 and 44 kg of W% 80 UO{sub 2} + 20 ZrO{sub 2} melt quenched in 1-m-depth water at saturation at 5.0 MPa. In all the tests, significant breakup and quenching took place during the melt fall through the water. No steam explosion occurred. In the tests performed with a pure oxide UO{sub 2}-ZrO{sub 2} melt, part of the corium (from 1/6 to 1/3) did not breakup and reached the bottom plate still molten whatever the water depth was. Test L-11 data suggest that full oxidation and complete breakup of the melt occurred during the melt fall through the water. A proportion of 64% of the total energy content of the melt was released to the water during this phase ({approximately}1.5 s), against 44% for L-14. The maximum temperature increase of the bottom plate was 330 K (L-14). The mean particle size of the debris ranged between 2.5 and 4.8mm.

  5. Development of Scaling Approach for Prediction of Terminal Spread Thickness of Melt Poured into a Pool of Water

    OpenAIRE

    Konovalenko, Alexander; Kudinov, Pavel

    2012-01-01

    Corium melt stabilization and long term cooling in a pool of water located beneath reactor vessel is adopted in several existing designs of light water reactors (LWRs) as an element in severe accident (SA) mitigation strategy. At certain conditions of melt release into the pool (e.g. large ratio of the vessel breach size to the pool depth), liquid melt can spread under water and reach a coolable configuration. Coolability of the melt is contingent on terminal spread thickness of the melt laye...

  6. Fundamentals of Melt-Water Interfacial Transport Phenomena: Improved Understanding for Innovative Safety Technologies in ALWRs

    Energy Technology Data Exchange (ETDEWEB)

    M. Anderson; M. Corradini; K.Y. Bank; R. Bonazza; D. Cho

    2005-04-26

    The interaction and mixing of high-temperature melt and water is the important technical issue in the safety assessment of water-cooled reactors to achieve ultimate core coolability. For specific advanced light water reactor (ALWR) designs, deliberate mixing of the core-melt and water is being considered as a mitigative measure, to assure ex-vessel core coolability. The goal of this work is to provide the fundamental understanding needed for melt-water interfacial transport phenomena, thus enabling the development of innovative safety technologies for advanced LWRs that will assure ex-vessel core coolability. The work considers the ex-vessel coolability phenomena in two stages. The first stage is the melt quenching process and is being addressed by Argonne National Lab and University of Wisconsin in modified test facilities. Given a quenched melt in the form of solidified debris, the second stage is to characterize the long-term debris cooling process and is being addressed by Korean Maritime University in via test and analyses. We then address the appropriate scaling and design methodologies for reactor applications.

  7. Estimating Temporal Redistribution of Surface Melt Water into Upper Stratigraphy of the Juneau Icefield, Alaska

    Science.gov (United States)

    Wilner, J.; Smith, B.; Moore, T.; Campbell, S. W.; Slavin, B. V.; Hollander, J.; Wolf, J.

    2015-12-01

    The redistribution of winter accumulation from surface melt into firn or deeper layers (i.e. internal accumulation) remains a poorly understood component of glacier mass balance. Winter accumulation is usually quantified prior to summer melt, however the time window between accumulation and the onset of melt is minimal so this is not always possible. Studies which are initiated following the onset of summer melt either neglect sources of internal accumulation or attempt to estimate melt (and therefore winter accumulation uncertainty) through a variety of modeling methods. Here, we used ground-penetrating radar (GPR) repeat common midpoint (CMP) surveys with supporting common offset surveys, mass balance snow pits, and probing to estimate temporal changes in water content within the winter accumulation and firn layers of the southern Juneau Icefield, Alaska. In temperate glaciers, radio-wave velocity is primarily dependent on water content and snow or firn density. We assume density changes are temporally slow relative to water flow through the snow and firn pack, and therefore infer that changing radio-wave velocities measured by successive CMP surveys result from flux in surface melt through deeper layers. Preliminary CMP data yield radio-wave velocities of 0.15 to 0.2 m/ns in snowpack densities averaging 0.56 g cm-3, indicating partially to fully saturated snowpack (4-9% water content). Further spatial-temporal analysis of CMP surveys is being conducted. We recommend that repeat CMP surveys be conducted over a longer time frame to estimate stratigraphic water redistribution between the end of winter accumulation and maximum melt season. This information could be incorporated into surface energy balance models to further understanding of the influence of internal accumulation on glacier mass balance.

  8. Ionic-polymeric models and the amphoteric behavior of water in silicate melts

    Science.gov (United States)

    Moretti, R.

    2012-04-01

    In silicate melts it is almost impossible to readily distinguish solute and solvent like in aqueous solutions. The anionic framework of silicate melts, in fact, makes solute and solvents so intimately related that one cannot identify a solvation shell and identify directly, from structural studies, the complexes needed to define acid-base reactions. Therefore, the distinction between solute and solvent becomes blurred in systems such as silicate melts, because speciation is not only complex but changes with the marked depolymerization of the silicate framework that obtains from pure SiO2 to metal-oxide rich compositions. These features do not allow proper understanding of the actual physico-chemical role of many species detected by conventional techniques, a fact which can lead to confusing notation. However, these may not be serious limits to account correctly for the acid-base reactions that take place in every kind of magmatic setting, provided a 'syntax' describing the effective interactions among significative cationic and anionic entities. In particular, the syntax for acid-base exchanges is needed such that constituting oxides (i.e. chemical components) can be treated independently of (but not necessarily extraneous to) structural features in defining such entities. So-called ionic-polymeric models highlight the mutual correspondence between polymerization and acid-base properties of dissolved oxides through the Lux-Flood formalism for molten oxides. They thus provide the syntax to write chemical exchanges, but have no pretension to structural description. In fact the concept of melt polymerization is used to identify basic anions and cations that can be used, along with their formal charge, to describe effectively acid-base interactions taking place in melts. In this respect, an example is given by the description of the amphoteric behavior of water dissolved on melts, hence water autoprotolysis. Although it exerts a profound influence on properties of

  9. Phenomenological studies on melt-structure-water interactions (MSWI) during severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Sehgal, B.R.; Yang, Z.L.; Haraldsson, H.O.; Nourgaliev, R.R.; Konovalikhin, M.; Paladino, D.; Gubaidullin, A.A.; Kolb, G.; Theerthan, A. [Royal Inst. of Tech., Stockholm (Sweden). Div. of Nuclear Power Safety

    2000-05-01

    This is the annual report for the work performed in 1999 in the research project Melt-Structure-Water Interactions During Severe Accidents in LWRs, under the auspices of the APRI Project, jointly funded by SKI, HSK, USNRC and the Swedish and Finnish power companies. The emphasis of the work is placed on phenomena and properties which govern the fragmentation and breakup of melt jets and droplets, melt spreading and coolability, and thermal and mechanical loadings of a pressure vessel during melt-vessel interaction. We believe that significant technical advances have been achieved during the course of these studies. It was found that: The coolant temperature has significant influence on the characteristics of debris fragments produced from the breakup of an oxidic melt jet. At low subcooling the fragments are relatively large and irregular compared to the smaller particles produced at high subcooling. The melt jet density has considerable effect on the fragment size produced. As the melt density increases the fragment size becomes smaller. The mass mean size of the debris changes proportionally to the square root of the coolant to melt density ratio. The melt superheat has little effect on the debris particle size distribution produced during the melt jet fragmentation. The impingement velocity of the jet has significant impact on the fragmentation process. At lower jet velocity the melt fragments agglomerate and form a cake of large size debris. When the jet velocity is increased more complete fragmentation is obtained. The scaling methodology for melt spreading, developed during 1998, has been further validated against almost all of the spreading experimental data available so far. Experimental results for the dryout heat flux of homogeneous particulate debris beds with top flooding compare well with the Lipinski correlation. For the stratified particle beds, the fine particle layer resting on the top of another particle layer dominates the dryout processes

  10. Several properties offilament fibers made from recycled bottles of mineral water using melt spinning method

    Science.gov (United States)

    Muslim, Ikhwanul; Mardiyati; Basuki, Arif

    2016-01-01

    Waste mineral water bottles made of PET called post-consumer POSTC-PET packaging with recycling code no. 1 can be made into another material other than the bottle by using a mechanical recycling process. In this experiment carried waste recycling process bottled mineral water bottles of PET into filament fibres with the aid of a melt spinning. From the resulting experimental filament fibres diameter of 14-15 microns, obtained the draw ratio is 1/46, 573,5 - 699,8 MPa tensile strength, modulus of elasticity of 2,01 - 2,45GPa, moisture regain of 2,84. Keywords. PET; Bottle; Fiber; Melt; Spinning; Drawing.

  11. Surface Transformations and Water Uptake on Liquid and Solid Butanol near the Melting Temperature

    CERN Document Server

    Papagiannakopoulos, Panos; Thomson, Erik S; Markovic, Nikola; Pettersson, Jan B C

    2013-01-01

    Water interactions with organic surfaces are of central importance in biological systems and many Earth system processes. Here we describe experimental studies of water collisions and uptake kinetics on liquid and solid butanol from 160 to 200 K. Hyperthermal D2O molecules (0.32 eV) undergo efficient trapping on both solid and liquid butanol, and only a minor fraction scatters inelastically after an 80% loss of kinetic energy to surface modes. Trapped molecules either desorb within a few ms, or are taken up by the butanol phase during longer times. The water uptake and surface residence time increase with temperature above 180 K indicating melting of the butanol surface 4.5 K below the bulk melting temperature. Water uptake changes gradually across the melting point and trapped molecules are rapidly lost by diffusion into the liquid above 190 K. This indicates that liquid butanol maintains a surface phase with limited water permeability up to 5.5 K above the melting point. These surface observations are indic...

  12. Human activities and its Responses to Glacier Melt Water Over Tarim River Basin

    Science.gov (United States)

    He, Hai; Zhou, Shenbei; Bai, Minghao

    2017-04-01

    Tarim River Basin lies in the south area of Xinjiang Uygur Autonomous Region, the north-west area of China. It is the longest inland river of China. Being far away from ocean and embraced by high mountains, Tarim River Basin is the typical arid region in the world. The intensity of human activities increased rapidly in Tarim River Basin since 1980's and water resources lacking is the major issue restricting the development of social economy. The glacier melt water plays an important role for the regional social and economic development, and it accounts for 40% of mountain-pass runoff. It is a fragile mutual-dependent relationship between local sustainable development and runoff. Under the background of global change glacier melt water process has also changed especially in the arid and semi-arid region. Due to climate change, glacier in Tarim River Basin has melted in an observed way since 1980s, together with increasing trend of annual rainfall and virgin flow in mountain basins. Correspondingly, human activity gets more frequent since 1970s, resulting into the obvious fragile mutual-dependent relationship between basin runoff and water use amount. Through an analysis of meteorological, hydrological and geographical observation data from 1985 to 2015, this thesis make a multi-factor variance analysis of population, cultivation area, industrial development and runoff in upstream and mid-stream of Tarim River under changing conditions. Furthermore, the regulation function of natural factors and water demand management factors on relationship between runoff and water using amount are discussed, including temperature, rainfall, and evaporation, water conservation technology and soil-water exploitation administrative institutions. It concludes that: first, increase in glacier runoff, rainfall amount, and virgin flow haven't notably relieved ecological issue in Tarim River Basin, and even has promoted water use behaviour in different flowing areas and noticeably reduced

  13. Oxygen exchange and ice melt measured at the ice-water interface by eddy correlation

    DEFF Research Database (Denmark)

    Long, M.H.; Koopmans, D.; Berg, P.

    2012-01-01

    This study examined fluxes across the ice-water interface utilizing the eddy correlation technique. Temperature eddy correlation systems were used to determine rates of ice melting and freezing, and O2 eddy correlation systems were used to examine O2 exchange rates driven by biological and physical...... processes. The study was conducted below 0.7 m thick sea-ice in mid-March 2010 in a southwest Greenland fjord and revealed low rates of ice melt at a maximum of 0.80 mm dĝ̂'1. The O2 flux associated with release of O2 depleted melt water was less than 13 % of the average daily O2 respiration rate. Ice melt...... heterotrophic with a daily gross primary production of 0.69 mmol O2 mĝ̂'2 dĝ̂'1 and a respiration rate of ĝ̂'2.13 mmol O2 mĝ̂'2 dĝ̂'1 leading to a net ecosystem metabolism of ĝ̂'1.45 mmol O2 mĝ̂'2 dĝ̂'1. This application of the eddy correlation technique produced high temporal resolution O2 fluxes and ice melt...

  14. Water- and Boron-Rich Melt Inclusions in Quartz from the Malkhan Pegmatite, Transbaikalia, Russia

    Directory of Open Access Journals (Sweden)

    Elena Badanina

    2012-11-01

    Full Text Available In this paper we show that the pegmatite-forming processes responsible for the formation of the Malkhan pegmatites started at magmatic temperatures around 720 °C. The primary melts or supercritical fluids were very water- and boron-rich (maximum values of about 10% (g/g B2O3 and over the temperature interval from 720 to 600 °C formed a pseudobinary solvus, indicated by the coexistence of two types of primary melt inclusions (type-A and type-B representing a pair of conjugate melts. Due to the high water and boron concentration the pegmatite-forming melts are metastable and can be characterized either as genuine melts or silicate-rich fluids. This statement is underscored by Raman spectroscopic studies. This study suggested that the gel state proposed by some authors cannot represent the main stage of the pegmatite-forming processes in the Malkhan pegmatites, and probably in all others. However there are points in the evolution of the pegmatites where the gel- or gel-like state has left traces in form of real gel inclusions in some mineral in the Malkhan pegmatite, however only in a late, fluid dominated stage.

  15. Quantifying present and future glacier melt-water contribution to runoff in a Central Himalayan river basin

    OpenAIRE

    Prasch, M.; Mauser, W.; Weber, M.

    2012-01-01

    Water supply of most lowland cultures heavily depends on rain and melt-water from the upstream mountains. Especially melt-water release of alpine mountain ranges is usually attributed a pivotal role for the water supply of large downstream regions. Water scarcity is assumed as consequence of glacier shrinkage and possible disappearance due to Global Climate Change, particular for large parts of Central and South East Asia. In this paper, the application and validation of a coupled modeling ap...

  16. Quantifying present and future glacier melt-water contribution to runoff in a central Himalayan river basin

    OpenAIRE

    Prasch, M.; Mauser, W.; Weber, M.

    2013-01-01

    Water supply of most lowland cultures heavily depends on rain and melt water from the upstream mountains. Especially melt-water release of alpine mountain ranges is usually attributed a pivotal role for the water supply of large downstream regions. Water scarcity is assumed as consequence of glacier shrinkage and possible disappearance due to global climate change (GCC), in particular for large parts of Central and Southeast Asia. In this paper, the application and validatio...

  17. Effect of water on the fluorine and chlorine partitioning behavior between olivine and silicate melt

    Science.gov (United States)

    Joachim, Bastian; Stechern, André; Ludwig, Thomas; Konzett, Jürgen; Pawley, Alison; Ruzié-Hamilton, Lorraine; Clay, Patricia L.; Burgess, Ray; Ballentine, Christopher J.

    2017-04-01

    Halogens show a range from moderate (F) to highly (Cl, Br, I) volatile and incompatible behavior, which makes them excellent tracers for volatile transport processes in the Earth's mantle. Experimentally determined fluorine and chlorine partitioning data between mantle minerals and silicate melt enable us to estimate Mid Ocean Ridge Basalt (MORB) and Ocean Island Basalt (OIB) source region concentrations for these elements. This study investigates the effect of varying small amounts of water on the fluorine and chlorine partitioning behavior at 1280 °C and 0.3 GPa between olivine and silicate melt in the Fe-free CMAS+F-Cl-Br-I-H2O model system. Results show that, within the uncertainty of the analyses, water has no effect on the chlorine partitioning behavior for bulk water contents ranging from 0.03 (2) wt% H2O (DCl ol/melt = 1.6 ± 0.9 × 10-4) to 0.33 (6) wt% H2O (DCl ol/melt = 2.2 ± 1.1 × 10-4). Consequently, with the effect of pressure being negligible in the uppermost mantle (Joachim et al. Chem Geol 416:65-78, 2015), temperature is the only parameter that needs to be considered for the determination of chlorine partition coefficients between olivine and melt at least in the simplified iron-free CMAS+F-Cl-Br-I-H2O system. In contrast, the fluorine partition coefficient increases linearly in this range and may be described at 1280 °C and 0.3 GPa with ( R 2 = 0.99): DF^{ol/melt} = 3.6± 0.4 × 10^{-3} × X_{H}_{2O}( wt %) + 6 ± 0.4× 10^{-4}. The observed fluorine partitioning behavior supports the theory suggested by Crépisson et al. (Earth Planet Sci Lett 390:287-295, 2014) that fluorine and water are incorporated as clumped OH/F defects in the olivine structure. Results of this study further suggest that fluorine concentration estimates in OIB source regions are at least 10% lower than previously expected (Joachim et al. Chem Geol 416:65-78, 2015), implying that consideration of the effect of water on the fluorine partitioning behavior between Earth

  18. Experiments on interactions between zirconium-containing melt and water (ZREX). Hydrogen generation and chemical augmentation of energetics

    Energy Technology Data Exchange (ETDEWEB)

    Cho, D.H.; Armstrong, D.R.; Gunther, W.H. [Argonne National Lab., IL (United States); Basu, S.

    1998-01-01

    The results of the first data series of experiments on interactions between zirconium-containing melt and water are described. These experiments involved dropping 1-kg batches of pure zirconium or zirconium-zirconium dioxide mixture melt into a column of water. A total of nine tests were conducted, including four with pure zirconium melt and five with Zr-ZrO{sub 2} mixture melt. Explosions took place only in those tests which were externally triggered. While the extent of zirconium oxidation in the triggered experiments was quite extensive, the estimated explosion energetics were found to be very small compared to the combined thermal and chemical energy available. (author)

  19. The suppression of Antarctic bottom water formation by melting ice shelves in Prydz Bay

    Science.gov (United States)

    Williams, G. D.; Herraiz-Borreguero, L.; Roquet, F.; Tamura, T.; Ohshima, K. I.; Fukamachi, Y.; Fraser, A. D.; Gao, L.; Chen, H.; McMahon, C. R.; Harcourt, R.; Hindell, M.

    2016-08-01

    A fourth production region for the globally important Antarctic bottom water has been attributed to dense shelf water formation in the Cape Darnley Polynya, adjoining Prydz Bay in East Antarctica. Here we show new observations from CTD-instrumented elephant seals in 2011-2013 that provide the first complete assessment of dense shelf water formation in Prydz Bay. After a complex evolution involving opposing contributions from three polynyas (positive) and two ice shelves (negative), dense shelf water (salinity 34.65-34.7) is exported through Prydz Channel. This provides a distinct, relatively fresh contribution to Cape Darnley bottom water. Elsewhere, dense water formation is hindered by the freshwater input from the Amery and West Ice Shelves into the Prydz Bay Gyre. This study highlights the susceptibility of Antarctic bottom water to increased freshwater input from the enhanced melting of ice shelves, and ultimately the potential collapse of Antarctic bottom water formation in a warming climate.

  20. Melting of the precipitated ice IV in LiCl aqueous solution and polyamorphism of water.

    Science.gov (United States)

    Mishima, Osamu

    2011-12-08

    Melting of the precipitated ice IV in supercooled LiCl-H(2)O solution was studied in the range of 0-0.6 MPa and 160-270 K. Emulsified solution was used to detect this metastable transition. Ice IV was precipitated from the aqueous solution of 2.0 mol % LiCl (or 4.8 mol % LiCl) in each emulsion particle at low-temperature and high-pressure conditions, and the emulsion was decompressed at different temperatures. The melting of ice IV was detected from the temperature change of the emulsified sample during the decompression. There was an apparently sudden change in the slope of the ice IV melting curve (liquidus) in the pressure-temperature diagram. At the high-pressure and high-temperature side of the change, the solute-induced freezing point depression was observed. At the low-pressure and low-temperature side, ice IV transformed into ice Ih on the decompression, and the transition was almost unrelated to the concentration of LiCl. These experimental results were roughly explained by the presumed existence of two kinds of liquid water (low-density liquid water and high-density liquid water), or polyamorphism in water, and by the simple assumption that LiCl dissolved maily in high-density liquid water.

  1. Oxygen exchange and ice melt measured at the ice-water interface by eddy correlation

    DEFF Research Database (Denmark)

    Long, M.H.; Koopmans, D.; Berg, P.

    2012-01-01

    This study examined fluxes across the ice-water interface utilizing the eddy correlation technique. Temperature eddy correlation systems were used to determine rates of ice melting and freezing, and O2 eddy correlation systems were used to examine O2 exchange rates driven by biological and physical...... processes. The study was conducted below 0.7 m thick sea-ice in mid-March 2010 in a southwest Greenland fjord and revealed low rates of ice melt at a maximum of 0.80 mm dĝ̂'1. The O2 flux associated with release of O2 depleted melt water was less than 13 % of the average daily O2 respiration rate. Ice melt...... and insufficient vertical turbulent mixing due to low current velocities caused periodic stratification immediately below the ice. This prevented the determination of fluxes 61 % of the deployment time. These time intervals were identified by examining the velocity and the linearity and stability of the cumulative...

  2. Mechanisms and implications of α-HCH enrichment in melt pond water on Arctic sea ice.

    Science.gov (United States)

    Pućko, M; Stern, G A; Barber, D G; Macdonald, R W; Warner, K-A; Fuchs, C

    2012-11-06

    During the summer of 2009, we sampled 14 partially refrozen melt ponds and the top 1 m of old ice in the pond vicinity for α-hexachlorocyclohexane (α-HCH) concentrations and enantiomer fractions (EFs) in the Beaufort Sea. α-HCH concentrations were 3 - 9 times higher in melt ponds than in the old ice. We identify two routes of α-HCH enrichment in the ice over the summer. First, atmospheric gas deposition results in an increase of α-HCH concentration from 0.07 ± 0.02 ng/L (old ice) to 0.34 ± 0.08 ng/L, or ~20% less than the atmosphere-water equilibrium partitioning concentration (0.43 ng/L). Second, late-season ice permeability and/or complete ice thawing at the bottom of ponds permit α-HCH rich seawater (~0.88 ng/L) to replenish pond water, bringing concentrations up to 0.75 ± 0.06 ng/L. α-HCH pond enrichment may lead to substantial concentration patchiness in old ice floes, and changed exposures to biota as the surface meltwater eventually reaches the ocean through various drainage mechanisms. Melt pond concentrations of α-HCH were relatively high prior to the late 1980-s, with a Melt pond Enrichment Factor >1 (MEF; a ratio of concentration in surface meltwater to surface seawater), providing for the potential of increased biological exposures.

  3. Termination of light-water reactor core-melt accidents with a chemical core catcher: the core-melt source reduction system (COMSORS)

    Energy Technology Data Exchange (ETDEWEB)

    Forsberg, C.W.; Parker, G.W.; Rudolph, J.C.; Osborne-Lee, I.W. [Oak Ridge National Lab., TN (United States); Kenton, M.A. [Dames and Moore, Westmont, IL (United States)

    1996-09-01

    The Core-Melt Source Reduction System (COMSORS) is a new approach to terminate light-water reactor core melt accidents and ensure containment integrity. A special dissolution glass is placed under the reactor vessel. If core debris is released onto the glass, the glass melts and the debris dissolves into the molten glass, thus creating a homogeneous molten glass. The molten glass, with dissolved core debris, spreads into a wide pool, distributing the heat for removal by radiation to the reactor cavity above or by transfer to water on top of the molten glass. Expected equilibrium glass temperatures are approximately 600 degrees C. The creation of a low-temperature, homogeneous molten glass with known geometry permits cooling of the glass without threatening containment integrity. This report describes the technology, initial experiments to measure key glass properties, and modeling of COMSORS operations.

  4. Studies of Aquatic Fungi. XXIV. Aquatic Fungi in the Water of Melting Snow

    Directory of Open Access Journals (Sweden)

    Bazyli Czeczuga

    2014-08-01

    Full Text Available The work was undertaken to investigate the mycoflora in the water of melting snow. Samples of water were collected in March 1987-1988 for hydrochemical analysis (3 sites and studies of the fungus content (9 sites. Forty-nine species of fungi were found in this waters. The following fungi unknown from Poland were found: Skirgiella septigena, Monoblepharis macraodra, M. polymorpha, M. fascicutlta, M. insignis, Achlya apiculata, Apodachlya punctata, Pythium dissotocum, Hansenula holstii, H. saturnus, Actiaospora megalospora and Heliscus lugdunensis.

  5. Attributing the changes in seasonal runoff to dominated water sources in a snow and glacier melt-dominated catchment

    Science.gov (United States)

    He, Zhihua

    2016-04-01

    Attributing the changes in seasonal runoff to dominated water sources in a snow and glacier melt-dominated catchment Trend analysis indicates significant changes in the magnitude and timing of seasonal runoff from 1960 to 2010 in the Ala_archa catchment in Central Asia, which is dominated by snow and glacier meltwater. This study modeled the dominated water sources, including snowmelt water, glacier melt water and rainfall water, for daily discharge events in this basin. Hydrological parameters were estimated in a stepwise method. First, parameters were divided into the melting group and non-melting group based on sensitive analysis. The parameters belonged to the melting group effect the estimation of snow and glacier melting, while it is the opposite for the parameters belonged to the non-melting group. Second, the melting parameters were calibrated on the observed annual glacier mass balance data. Third, the non-melting parameters were calibrated on the observed daily discharge series using the calibrated melting parameters. Fourth, the melting parameters were recalibrated on both the observed glacier mass balance data and the daily discharge series. The calibration steps were repeated until the relative difference of all the melting parameter values between two calibration procedures were lower than 5%. The dominated water sources for each discharge event were identified by the fraction of water inputs in the whole basin during a 7-day period preceded the discharge event. The fraction of various water inputs were calculated in 300m-elevation bands. In cases the fraction of snowmelt water is higher than 0.6, the corresponding discharge events were identified as snowmelt dominated events, and it is the same for the rainfall and glacier melt dominated events. Results show that the increasing in winter runoff is caused by the increased rainfall, the increased spring runoff is driven by the increasing of snowmelt, while the increased glacier meltwater dominated the

  6. Light absorption and partitioning in Arctic Ocean surface waters: impact of multi year ice melting

    Directory of Open Access Journals (Sweden)

    S. Bélanger

    2013-03-01

    Full Text Available Ice melting in the Arctic Ocean exposes the surface water to more radiative energy with poorly understood effects on photo-biogeochemical processes and heat deposition in the upper ocean. In August 2009, we documented the vertical variability of light absorbing components at 37 stations located in the southeastern Beaufort Sea including both Mackenzie river-influenced waters and polar mixed layer waters. We found that melting multi-year ice released significant amount of non-algal particulates (NAP near the sea surface relative to sub-surface waters. NAP absorption coefficients at 440 nm (aNAP(440 immediately below the sea surface (0- were on average 3-fold (up to 10-fold higher compared to sub-surface values measured at 2–3 m depth. The impact of this unusual feature on the light transmission and remote sensing reflectance (Rrs was further examined using a radiative transfer model. A 10-fold particle enrichment homogeneously distributed in the first meter of the water column slightly reduced photosynthetically available and usable radiation (PAR and PUR by ~6% and ~8%, respectively, relative to a fully homogenous water column with low particles concentration. In terms of Rrs, the particle enrichment significantly flattered the spectrum by reducing the Rrs by up to 20% in the blue-green spectral region (400–550 nm. These results highlight the impact of melt water on the concentration of particles at sea surface, and the need for considering nonuniform vertical distribution of particles in such systems when interpreting remotely sensed ocean color. Spectral slope of aNAP spectra calculated in the UV domain decreased with depth suggesting that this parameter is sensitive to detritus composition and/or diagenesis state (e.g., POM photobleaching.

  7. Synthetic analyses of the LAVA experimental results on in-vessel corium retention through gap cooling

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Kyoung Ho; Cho, Young Ro; Koo, Kil Mo; Park, Rae Joon; Kim, Jong Hwan; Kim, Jong Tae; Ha, Kwang Sun; Kim, Sang Baik; Kim, Hee Dong

    2001-03-01

    LAVA(Lower-plenum Arrested Vessel Attack) has been performed to gather proof of gap formation between the debris and lower head vessel and to evaluate the effect of the gap formation on in-vessel cooling. Through the total of 12 tests, the analyses on the melt relocation process, gap formation and the thermal and mechanical behaviors of the vessel were performed. The thermal behaviors of the lower head vessel were affected by the formation of the fragmented particles and melt pool during the melt relocation process depending on mass and composition of melt and subcooling and depth of water. During the melt relocation process 10.0 to 20.0 % of the melt mass was fragmented and also 15.5 to 47.5 % of the thermal energy of the melt was transferred to water. The experimental results address the non-adherence of the debris to the lower head vessel and the consequent gap formation between the debris and the lower head vessel in case there was an internal pressure load across the vessel abreast with the thermal load induced by the thermite melt. The thermal behaviors of the lower head vessel during the cooldown period were mainly affected by the heat removal characteristics through this gap, which were determined by the possibilities of the water ingression into the gap depending on the melt composition of the corium simulant. The enhanced cooling capacity through the gap was distinguished in the Al{sub 2}O{sub 3} melt tests. It could be inferred from the analyses on the heat removal capacity through the gap that the lower head vessel could effectively cooldown via heat removal in the gap governed by counter current flow limits(CCFL) even if 2mm thick gap should form in the 30 kg Al{sub 2}O{sub 3} melt tests, which was also confirmed through the variations of the conduction heat flux in the vessel and rapid cool down of the vessel outer surface in the Al{sub 2}O{sub 3} melt tests. In the case of large melt mass of 70 kg Al{sub 2}O{sub 3} melt, however, the infinite

  8. Widespread Refreezing of Both Surface and Basal Melt Water Beneath the Greenland Ice Sheet

    Science.gov (United States)

    Bell, R. E.; Tinto, K. J.; Das, I.; Wolovick, M.; Chu, W.; Creyts, T. T.; Frearson, N.

    2013-12-01

    The isotopically and chemically distinct, bubble-free ice observed along the Greenland Ice Sheet margin both in the Russell Glacier and north of Jacobshavn must have formed when water froze from subglacial networks. Where this refreezing occurs and what impact it has on ice sheet processes remain unclear. We use airborne radar data to demonstrate that freeze-on to the ice sheet base and associated deformation produce large ice units up to 700 m thick throughout northern Greenland. Along the ice sheet margin, in the ablation zone, surface meltwater, delivered via moulins, refreezes to the ice sheet base over rugged topography. In the interior, water melted from the ice sheet base is refrozen and surrounded by folded ice. A significant fraction of the ice sheet is modified by basal freeze-on and associated deformation. For the Eqip and Petermann catchments, representing the ice sheet margin and interior respectively, extensive airborne radar datasets show that 10%-13% of the base of the ice sheet and up to a third of the catchment width is modified by basal freeze-on. The interior units develop over relatively subdued topography with modest water flux from basal melt where conductive cooling likely dominates. Steps in the bed topography associated with subglacial valley networks may foster glaciohydraulic supercooling. The ablation zone units develop where both surface melt and crevassing are widespread and large volumes of surface meltwater will reach the base of the ice sheet. The relatively steep topography at the upslope edge of the ablation zone units combined with the larger water flux suggests that supercooling plays a greater role in their formation. The ice qualities of the ablation zone units should reflect the relatively fresh surface melt whereas the chemistry of the interior units should reflect solute-rich basal melt. Changes in basal conditions such as the presence of till patches may contribute to the formation of the large basal units near the

  9. Estimating the glacial melt water contribution to the fresh water budget from salinity and δ18O measurements in Godthåbsfjord

    Science.gov (United States)

    Fitzner, Antje; van As, Dirk; Bendtsen, Jorgen; Dahl-Jensen, Dorthe; Fettweis, Xavier; Mortensen, John; Rysgaard, Soren

    2013-04-01

    The mass loss of the Greenland ice sheet increases due to changes in the surface mass balance and accelerated ice discharge through numerous outlet glaciers at the margins. The melt has global and local consequences. Globally the sea level rises and locally the increased fresh water inflow affects fishery and transportation. In this study we focus on the fjord system near Nuuk in West Greenland, Godthåbsfjord. Godthåbsfjord is a unique fjord with its length of about 300 km and a shallow sill at the fjord entrance that protects the fjord system. There are several tidewater glaciers terminating into the fjord and two land-terminating glaciers along the fjord contributing to the fresh water content in the fjord. The largest tidewater glacier is Kangiata Nunåta Sermia. The freshwater originates primarily from three processes: surface melt, ice berg calving and basal melt. Observations and climate models can give estimates for calving and surface melt. Basal melt, however, cannot be observed directly. Even though mass loss by basal melting is neglected on the global scale, it plays an important role in the small regional environment like fjords and the glaciers itself. Warmer ocean temperatures increase basal melt, and resulting lubrication accelerates tidewater glaciers. Overall, the freshwater content in the fjord increases. Salinity measurements taken in the fjord between 2007 and 2011 show a seasonal variability originating from the variation in fresh water inflow. Based on salinity records only, it is not possible to distinguish between the different fresh water sources like precipitation and melt. Hence, δ18O measurements are used in addition to salinity records to determine the origin of the fresh water because of the different δ18O signatures of run-off and glacial melt water. The resulting fresh water inflow and the glacial melt contribution are compared to independent estimates and regional climate model output.

  10. Air-sea flux of CO2 in arctic coastal waters influenced by glacial melt water and sea ice

    DEFF Research Database (Denmark)

    Sejr, Mikael Kristian; Krause-Jensen, Dorte; Rysgaard, Søren

    2011-01-01

    and thereby efficiently blocked air–sea CO2 exchange. During sea ice melt, dissolution of CaCO3 combined with primary production and strong stratification of the water column acted to lower surface-water pCO2 levels in the fjord. Also, a large input of glacial melt water containing geochemically reactive......Annual air–sea exchange ofCO2 inYoung Sound,NEGreenlandwas estimated using pCO2 surface-water measurements during summer (2006–2009) and during an ice-covered winter 2008. All surface pCO2 values were below atmospheric levels indicating an uptake of atmospheric CO2. During sea ice formation......, dissolved inorganic carbon (DIC) content is reduced causing sea ice to be under saturated in CO2. Approximately 1% of the DIC forced out of growing sea ice was released into the atmosphere while the remaining 99% was exported to the underlying water column. Sea ice covered the fjord 9 months a year...

  11. Outgassed water on Mars - Constraints from melt inclusions in SNC meteorites

    Science.gov (United States)

    Mcsween, Harry Y., Jr.; Harvey, Ralph P.

    1993-01-01

    The SNC (shergottite-nakhlite-chassignite) meteorites, thought to be igneous rocks from Mars, contain melt inclusions trapped at depth in early-formed crystals. Determination of the pre-eruptive water contents of SNC parental magmas from calculations of the solidification histories of these amphibole-bearing inclusions indicates that Martian magmas commonly contained 1.4 percent water by weight. When combined with an estimate of the volume of igneous materials on Mars, this information suggests that the total amount of water outgassed since 3.9 billion years ago corresponds to global depths on the order of 200 meters. This value is significantly higher than previous geochemical estimates but lower than estimates based on erosion by floods. These results imply a wetter Mars interior than has been previously thought and support suggestions of significant outgassing before formation of a stable crust or heterogeneous accretion of a veneer of cometary matter.

  12. Fission product release phenomena during core melt accidents in metal fueled heavy water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Ellison, P G; Hyder, M L; Monson, P R; Randolph, H W [Westinghouse Savannah River Co., Aiken, SC (USA); Hagrman, D L [EG and G Idaho, Inc., Idaho Falls, ID (USA); McClure, P R; Leonard, M T [Science Applications International Corp., Albuquerque, NM (USA)

    1990-01-01

    The phenomena that determine fission product release rates from a core melting accident in a metal-fueled, heavy water reactor are described in this paper. This information is obtained from the analysis of the current metal fuel experimental data base and from the results of analytical calculations. Experimental programs in place at the Savannah River Site are described that will provide information to resolve uncertainties in the data base. The results of the experiments will be incorporated into new severe accident computer codes recently developed for this reactor design. 47 refs., 4 figs.

  13. Light absorption and partitioning in Arctic Ocean surface waters: impact of multiyear ice melting

    Directory of Open Access Journals (Sweden)

    S. Bélanger

    2013-10-01

    Full Text Available Ice melting in the Arctic Ocean exposes the surface water to more radiative energy with poorly understood effects on photo-biogeochemical processes and heat deposition in the upper ocean. In August 2009, we documented the vertical variability of light absorbing components at 37 stations located in the southeastern Beaufort Sea including both Mackenzie River-influenced waters and polar mixed layer waters. We found that melting multiyear ice released significant amount of non-algal particulates (NAP near the sea surface relative to subsurface waters. NAP absorption coefficients at 440 nm (aNAP(440 immediately below the sea surface were on average 3-fold (up to 10-fold higher compared to subsurface values measured at 2–3 m depth. The impact of this unusual feature on the light transmission and remote sensing reflectance (Rrs was further examined using a radiative transfer model. A 10-fold particle enrichment homogeneously distributed in the first meter of the water column slightly reduced photosynthetically available and usable radiation (PAR and PUR by ∼6 and ∼8%, respectively, relative to a fully homogenous water column with low particle concentration. In terms of Rrs, the particle enrichment significantly flattered the spectrum by reducing the Rrs by up to 20% in the blue-green spectral region (400–550 nm. These results highlight the impact of meltwater on the concentration of particles at sea surface, and the need for considering non-uniform vertical distribution of particles in such systems when interpreting remotely sensed ocean color. Spectral slope of aNAP spectra calculated in the UV (ultraviolet domain decreased with depth suggesting that this parameter is sensitive to detritus composition and/or diagenesis state (e.g., POM (particulate organic matter photobleaching.

  14. Wastewater contamination in Antarctic melt-water streams evidenced by virological and organic molecular markers.

    Science.gov (United States)

    Tort, L F L; Iglesias, K; Bueno, C; Lizasoain, A; Salvo, M; Cristina, J; Kandratavicius, N; Pérez, L; Figueira, R; Bícego, M C; Taniguchi, S; Venturini, N; Brugnoli, E; Colina, R; Victoria, M

    2017-12-31

    Human activities in the Antarctica including tourism and scientific research have been raised substantially in the last century with the concomitant impact on the Antarctic ecosystems through the release of wastewater mainly from different scientific stations activities. The aim of this study was to assess the wastewater contamination of surface waters and sediments of three melt-water streams (11 sites) by leaking septic tanks located in the vicinity of the Uruguayan Scientific Station in the Fildes Peninsula, King George Island, Antarctica, during summer 2015. For this purpose, we combined the analysis of fecal steroids in sediments by using gas chromatography and six enteric viruses in surface waters by quantitative and qualitative PCR. Coprostanol concentrations (from 0.03 to 3.31μgg(-1)) and fecal steroids diagnostic ratios indicated that stations C7 and C8 located in the kitchen stream presented sewage contamination. Rotavirus was the only enteric virus detected in five sites with concentration ranging from 1.2×10(5)gcL(-)(1) to 5.1×10(5)gcL(-)(1) being three of them located downstream from the leaking AINA and Kitchen septic tanks. This study shows for the first time the presence of both virological and molecular biomarkers of wastewater pollution in surface waters and sediments of three melt-water streams in the vicinity of a scientific station in the Antarctica. These results highlight the importance of the complementation of these biomarkers in two different matrices (surface waters and sediments) to assess wastewater pollution in an Antarctic environment related to anthropogenic activities in the area. Copyright © 2017. Published by Elsevier B.V.

  15. Bottom melting of Arctic Sea Ice in the Nansen Basin due to Atlantic Water influence

    Science.gov (United States)

    Muilwijk, Morven; Smedsrud, Lars H.; Meyer, Amelie

    2016-04-01

    Our global climate is warming, and a shrinking Arctic sea ice cover remains one of the most visible signs of this warming. Sea Ice loss is now visible for all months in all regions of the Arctic. Hydrographic and current observations from a region north of Svalbard collected during the Norwegian Young Sea Ice Cruise (N-ICE2015) are presented here. Comparison with historical data shows that the new observations from January through June fill major gaps in available observations, and help describing important processes linking changes in regional Atlantic Water (AW) heat transport and sea ice. Warm and salty AW originating in the North Atlantic enters the Arctic Ocean through the Fram Strait and is present below the Arctic Sea Ice cover throughout the Arctic. However, the depth of AW varies by region and over time. In the region north of Svalbard, we assume that depth could be governed primarily by local processes, by upstream conditions of the ice cover (Northwards), or by upstream conditions of the AW (Southwards). AW carries heat corresponding to the volume transport of approximately 9 SV through Fram Strait, varying seasonally from 28 TW in winter to 46 TW in summer. Some heat is recirculated, but the net annual heat flux into the Arctic Ocean from AW is estimated to be around 40 TW. The Atlantic Water layer temperature at intermediate depths (150-900m) has increased in recent years. Until recently, maximum temperatures have been found to be 2-3 C in the Nansen Basin. Studies have shown that for example, in the West Spitsbergen Current the upper 50-200m shows an overall AW warming of 1.1 C since 1979. In general we expect efficient melting when AW is close to the surface. Previously the AW entering through Fram Strait has been considered as less important because changes in the sea ice cover have been connected to greater inflow of Pacific Water through Bering Strait and atmospheric forcing. Conversely it is now suggested that AW has direct impact on melting of

  16. Quantifying present and future glacier melt-water contribution to runoff in a central Himalayan river basin

    Science.gov (United States)

    Prasch, M.; Mauser, W.; Weber, M.

    2013-05-01

    Water supply of most lowland cultures heavily depends on rain and melt water from the upstream mountains. Especially melt-water release of alpine mountain ranges is usually attributed a pivotal role for the water supply of large downstream regions. Water scarcity is assumed as consequence of glacier shrinkage and possible disappearance due to global climate change (GCC), in particular for large parts of Central and Southeast Asia. In this paper, the application and validation of a coupled modeling approach with regional climate model (RCM) outputs and a process-oriented glacier and hydrological model is presented for the central Himalayan Lhasa River basin despite scarce data availability. Current and possible future contributions of ice melt to runoff along the river network are spatially explicitly shown. Its role among the other water balance components is presented. Although glaciers have retreated and will continue to retreat according to the chosen climate scenarios, water availability is and will be primarily determined by monsoon precipitation and snowmelt. Ice melt from glaciers is and will be a minor runoff component in summer monsoon-dominated Himalayan river basins.

  17. Quantifying present and future glacier melt-water contribution to runoff in a central Himalayan river basin

    Directory of Open Access Journals (Sweden)

    M. Prasch

    2013-05-01

    Full Text Available Water supply of most lowland cultures heavily depends on rain and melt water from the upstream mountains. Especially melt-water release of alpine mountain ranges is usually attributed a pivotal role for the water supply of large downstream regions. Water scarcity is assumed as consequence of glacier shrinkage and possible disappearance due to global climate change (GCC, in particular for large parts of Central and Southeast Asia. In this paper, the application and validation of a coupled modeling approach with regional climate model (RCM outputs and a process-oriented glacier and hydrological model is presented for the central Himalayan Lhasa River basin despite scarce data availability. Current and possible future contributions of ice melt to runoff along the river network are spatially explicitly shown. Its role among the other water balance components is presented. Although glaciers have retreated and will continue to retreat according to the chosen climate scenarios, water availability is and will be primarily determined by monsoon precipitation and snowmelt. Ice melt from glaciers is and will be a minor runoff component in summer monsoon-dominated Himalayan river basins.

  18. Dissolved and particulate organic carbon in the melt water of Icelandic glaciers

    Science.gov (United States)

    Chifflard, Peter; Reiss, Martin

    2017-04-01

    Recently, glaciers have been recognized as unique ecosystems with potential effects on the global carbon cycle. Among other transport processes organic carbon stored in glacier ecosystems is released from the glaciers through melt at the glaciers surface that discharges into proglacial streams and finally into the ocean. Nevertheless, the potential role of glaciers in the carbon cycle remains poorly understood (Hood et al. 2015). One particular problem in this respect is that there is a lack in regional and global analysis of the total amount of organic carbon released from glaciers. Although, the release of organic carbon has been investigated in proglacial streams in Alaska, the European Alps and Greenland, to our knowledge, there is no information available for Icelandic proglacial streams. Thus, the aims of this study are: 1) to develop a first base information about the concentration of dissolved and particulate organic carbon (DOC and POC) in several Icelandic proglacial streams and 2) to detect the variability of DOC and POC along a proglacial stream from the glacier source to the mouth into the Atlantic Ocean. Therefore, a field trip was conducted between 23 and 31 July 2016, whereby, 25 water samples were taken. The sampling points cover melt water from the following Icelandic glaciers Vatnajökull, Langjökull, Hofsjökull, Myrdalsjökull and Tungnafellsjökull. Further water samples were taken along the river Hvitá starting at the glacier Langjökull and ending at the mouth into the Atlantic ocean in the southwest of Iceland. At every sample point electrical conductivity, water temperate and the pH-value were measured in situ using a calibrated portable water quality meter (Hanna Combo HI98129). The water samples (130 ml) were filtered using pre-combusted GF/F filters (Whatman, pore sizes 0.7 µm) and stored in a cooling box until the shipment to the laboratory of the Department for Geography, Philipps-University of Marburg. The DOC concentrations in

  19. Holocene evolution of a drowned melt-water valley in the Danish Wadden Sea

    DEFF Research Database (Denmark)

    Pedersen, Jørn Bjarke Torp; Svinth, Steffen; Bartholdy, Jesper

    2009-01-01

    the total post-glacial transgression, and the reconstructed sea level curve represents the first unbroken curve of this kind from the Danish Wadden Sea, including all phases from the time where sea level first reached the Pleistocene substrate of the area. The sea level has been rising from - 12 m below...... the present level at c. 8400 cal yr BP, interrupted by two minor drops of sea level rise, and the Holocene sequence consists in most places of clay atop......Cores from the salt marshes along the drowned melt-water valley of river Varde Å in the Danish Wadden Sea have been dated and analysed (litho- and biostratigraphically) to reconstruct the Holocene geomorphologic evolution and relative sea level history of the area. The analysed cores cover...

  20. High water contents in basaltic melt inclusions from Arenal volcano, Costa Rica

    Science.gov (United States)

    Wade, J. A.; Plank, T.; Hauri, E. H.; Melson, W. G.; Soto, G. J.

    2004-12-01

    Despite the importance of water to arc magma genesis, fractionation and eruption, few quantitative constraints exist on the water content of Arenal magmas. Early estimates, by electron microprobe sum deficit, suggested up to 4 wt% H2O in olivine-hosted basaltic andesite melt inclusions (MI) from pre-historic ET-6 tephra (Melson, 1982), and up to 7 wt% H2O in plagioclase and orthopyroxene-hosted dacitic MI from 1968 lapilli (Anderson, 1979). These high water contents are consistent with abundant hornblende phenocrysts in Arenal volcanics, but inconsistent with geochemical tracers such as 10Be and Ba/La that suggest a low flux of recycled material (and presumably water) from the subduction zone. In order to test these ideas, and provide the first direct measurements of water in mafic Arenal magmas, we have studied olivine-hosted MI from the prehistoric (900 yBP; Soto et al., 1998) ET3 tephra layer. MI range from andesitic (> 58% SiO2) to basaltic compositions ( 4 wt%) found here for Arenal basaltic MI support the semi-quantitative data from earlier studies, but are somewhat unexpected given predictions from slab tracers. Arenal water contents (4%) approach those of the 1995 eruption of Cerro Negro in Nicaragua (4-5 wt% in basaltic MI; Roggensack et al., 1997), despite the fact that the latter has Ba/La of > 100, while Arenal has Ba/La Boletin de Volcanologia; Roggensack et al. (1997) Science; Soto et al. (1998) OSIVAM; Williams-Jones et al. (2001) Journal of Volc. and Geoth. Res.

  1. Transformation of irregular shaped silver nanostructures into nanoparticles by under water pulsed laser melting.

    Science.gov (United States)

    Yadavali, S; Sandireddy, V P; Kalyanaraman, R

    2016-05-13

    The ability to easily manufacture nanostructures with a desirable attribute, such as well-defined size and shape, especially from any given initial shapes or sizes of the material, will be helpful towards accelerating the use of nanomaterials in various applications. In this work we report the transformation of discontinuous irregular nanostructures (DIN) of silver metal by rapid heating under a bulk fluid layer. Ag films were changed into DIN by dewetting in air and subsequently heated by nanosecond laser pulses under water. Our findings show that the DIN first ripens into elongated structures and then breaks up into nanoparticles. From the dependence of this behavior on laser fluence we found that under water irradiation reduced the rate of ripening and also decreased the characteristic break-up length scale of the elongated structures. This latter result was qualitatively interpreted as arising from a Rayleigh-Plateau instability modified to yield significantly smaller length scales than the classical process due to pressure gradients arising from the rapid evaporation of water during laser melting. These results demonstrate that it is possible to fabricate a dense collection of monomodally sized Ag nanoparticles with significantly enhanced plasmonic quality starting from the irregular shaped materials. This can be beneficial towards transforming discontinuous Ag films into nanostructures with useful plasmonic properties, that are relevant for biosensing applications.

  2. Testing recent charge-on-spring type polarizable water models. I. Melting temperature and ice properties

    Science.gov (United States)

    Kiss, Péter T.; Bertsyk, Péter; Baranyai, András

    2012-11-01

    We determined the freezing point of eight molecular models of water. All models use the charge-on-spring (COS) method to express polarization. The studied models were the COS/G2, COS/G3 [H. Yu and W. F. van Gunsteren, J. Chem. Phys. 121, 9549 (2004), 10.1063/1.1805516], the COS/B2 [H. Yu, T. Hansson, and W. F. van Gunsteren, J. Chem. Phys. 118, 221 (2003), 10.1063/1.1523915], the SWM4-DP [G. Lamoureux, A. D. MacKerell, Jr., and B. Roux, J. Chem. Phys. 119, 5185 (2003), 10.1063/1.1598191], the SWM4-NDP [G. Lamoureux, E. Harder, I. V. Vorobyov, B. Roux, and A. D. MacKerell, Jr., Chem. Phys. Lett. 418, 245 (2006), 10.1016/j.cplett.2005.10.135], and three versions of our model, the BKd1, BKd2, and BKd3. The BKd1 is the original Gaussian model [P. T. Kiss, M. Darvas, A. Baranyai, and P. Jedlovszky, J. Chem. Phys. 136, 114706 (2012), 10.1063/1.3692602] with constant polarization and with a simple exponential repulsion. The BKd2 applies field-dependent polarizability [A. Baranyai and P. T. Kiss, J. Chem. Phys. 135, 234110 (2011), 10.1063/1.3670962], while the BKd3 model has variable size to approximate the temperature-density (T-ρ) curve of water [P. T. Kiss and A. Baranyai, J. Chem. Phys. 137, 084506 (2012), 10.1063/1.4746419]. We used the thermodynamic integration (TI) and the Gibbs-Helmholtz equation to determine the equality of the free energy for liquid water and hexagonal ice (Ih) at 1 bar. We used the TIP4P and the SPC/E models as reference systems of the TI. The studied models severely underestimate the experimental melting point of ice Ih. The calculated freezing points of the models are the following: COS/G2, 215 K; COS/G3, 149 K; SWM4-DP, 186 K; BKd1, 207 K; BKd2, 213 K; BKd3, 233 K. The freezing temperature of the SWM4-NDP system is certainly below 120 K. It might even be that the water phase is more stable than the ice Ih at 1 bar in the full temperature range. The COS/B2 model melts below 100 K. The best result was obtained for the BKd3 model which

  3. The Effective Convectivity Model for Simulation and Analysis of Melt Pool Heat Transfer in a Light Water Reactor Pressure Vessel Lower Head

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Chi Thanh

    2009-09-15

    , is indispensable for scrutinizing flow physics, on the other hand, the validated CFD method can be used to generate necessary data for validation of the accident analysis models. Given the insights gained from the CFD study, physics-based models and computationally-efficient tools are developed for multi-dimensional simulations of transient thermal-hydraulic phenomena in the lower plenum of a LWR during the late phase of an in-vessel core melt progression. To describe natural convection heat transfer in an internally heated volume, and molten metal layer heated from below and cooled from the top (and side) walls, the Effective Convectivity Models (ECM) are developed and implemented in a commercial CFD code. The ECM uses directional heat transfer characteristic velocities to transport the heat to cooled boundaries. The heat transport and interactions are represented through an energy-conservation formulation. The ECM then enables 3D heat transfer simulations of a homogeneous (and stratified) melt pool formed in the LWR lower head. In order to describe phase-change heat transfer associated with core debris or binary mixture (e.g. in a molten metal layer), a temperature-based enthalpy formulation is employed in the Phase-change ECM (so called the PECM). The PECM is capable to represent natural convection heat transfer in a mushy zone. Simple formulation of the PECM method allows implementing different models of mushy zone heat transfer for non-eutectic mixtures. For a non-eutectic binary mixture, compositional convection associated with concentration gradients can be taken into account. The developed models are validated against both existing experimental data and the CFD-generated data. ECM and PECM simulations show a superior computational efficiency compared to the CFD simulation method. The ECM and PECM methods are applied to predict thermal loads imposed on the vessel wall and Control Rod Guide Tubes (CRGTs) during core debris heatup and melting in a Boiling Water

  4. In-vessel coolability and steam explosion in Nordic BWRs

    Energy Technology Data Exchange (ETDEWEB)

    Ma, W.; Hansson, R.; Li, L.; Kudinov, P.; Cadinu, F.; Tran, C-.T. (Royal Institute of Technology (KTH), Stockholm (Sweden))

    2010-05-15

    The INCOSE project is to reduce the uncertainty in quantification of steam explosion risk and in-vessel coolability in Nordic BWR plants with the cavity flooding as a severe accident management (SAM) measure. During 2009 substantial advances and new insights into physical mechanisms were gained for studies of: (i) in-vessel corium coolability - development of the methodologies to assess the efficiency of the control rod guide tube (CRGT) cooling as a potential SAM measure; (ii) debris bed coolability - characterization of the effective particle diameter of multi-size particles and qualification of friction law for two-phase flow in the beds packed with multi-size particles; and (iii) steam explosion - investigation of the effect of binary oxides mixture's properties on steam explosion. An approach for coupling of ECM/PECM models with RELAP5 was developed to enhance predictive fidelity for melt pool heat transfer. MELCOR was employed to examine the CRGT cooling efficiency by considering an entire accident scenario, and the simulation results show that the nominal flowrate (approx10kg/s) of CRGT cooling is sufficient to maintain the integrity of the vessel in a BWR of 3900 MWth, if the water injection is activated no later than 1 hour after scram. The POMECO-FL experimental data suggest that for a particulate bed packed with multi-size particles, the effective particle diameter can be represented by the area mean diameter of the particles, while at high velocity (Re>7) the effective particle diameter is closer to the length mean diameter. The pressure drop of two-phase flow through the particulate bed can be predicted by Reed's model. The steam explosion experiments performed at high melt superheat (>200oC) using oxidic mixture of WO3-CaO didn't detect an apparent difference in steam explosion energetics and preconditioning between the eutectic and noneutectic melts. This points out that the next step of MISTEE experiment will be conducted at lower

  5. Flocculation alters the distribution and flux of melt-water supplied sediments and nutrients in the Arctic

    DEFF Research Database (Denmark)

    Markussen, Thor Nygaard; Andersen, Thorbjørn Joest; Ernstsen, Verner Brandbyge

    environment but comparatively little is known about the flocculation processes in the Arctic. We investigated flocculation dynamics from a melt-water river in the inner Disko Fjord, West Greenland. A novel, laser-illuminated camera system significantly improved the particle size measurement capabilities...

  6. The peculiarities of water crystallization and ice melting processes in the roots of one-year plants (Plantago major L.).

    Science.gov (United States)

    Bakradze, N; Kiziria, E; Sokhadze, V; Gogichaishvili, S

    2008-01-01

    Results are presented of a water phase transition study in plantain (Plantago major L.) roots, which were used as a model system to research the peculiarities of water crystallization and ice melting processes in complex heterogeneous biological systems. It was confirmed that water in such systems is crystallized in two clearly distinguished temperature ranges: -10 to -25 degree capital ES, Cyrillic and -25 to -45 degree capital ES, Cyrillic. These water fractions are conditionally attributed to extracellular (-10 to -25 degree capital ES, Cyrillic) and intracellular (-25 to -45 degree capital ES, Cyrillic) solutions. A possible explanation is given for such significant supercooling of the intracellular solution. The values of osmotic pressures of extra- and intracellular solutions were determined according to ice melting curves. It is noted that the intracellular solution, which crystallized at lower temperatures, had a lower osmotic pressure.

  7. A study of freezing-melting hysteresis of water in different porous materials. Part II: surfactant-templated silicas.

    Science.gov (United States)

    Petrov, Oleg; Furó, István

    2011-09-28

    The freezing-melting hysteresis of water in mesoporous silicas MCM-48, MCM-41 and SBA-16 has been studied by NMR cryoporometry. The hysteresis in MCM-48 was found to exhibit nearly parallel branches, matching type H1 hysteresis that had been observed earlier in controlled pore glass. The same type of hysteresis is observed in two of three different-sized MCM-41 under study (a pore diameter of 3.6 and 3 nm), superimposed with a secondary, extremely broad, type H3 hysteresis. No hysteresis was found in the smallest MCM-41 with a pore diameter hysteresis with the freezing branch being essentially steeper than the melting one, which is attributed to a pore blockage upon freezing, similar to what we observed earlier in Vycor porous glass. The data were analyzed using the model of curvature-dependent metastability of a solid phase upon melting; the validity of this model has been discussed.

  8. Satellite observation of winter season subsurface liquid melt water retention on the Greenland ice sheet using spectroradiometer and scatterometer data

    Science.gov (United States)

    Miller, J. Z.; Forster, R. R.; Long, D. G.; Brewer, S.

    2013-12-01

    The recently discovered perennial firn aquifer (PFA) represents a new glacier facie and a previously undefined liquid water storage mechanism on the Greenland ice sheet (GrIS). The current hypothesis suggests that at least two geophysical processes control the formation of the PFA: 1) high melt rates that saturate snow and firn layers with liquid water during the melt season, and 2) high snow accumulation rates that subsequently insulate this saturated layer allowing it to be retained in liquid form during the winter season. The PFA is potentially an important component in ice sheet mass and energy budget calculations, however, large-scale observations linking surface melt, subsurface liquid melt water retention, and the PFA currently do not exist. Satellite-borne spectroradiometers and scatterometers are frequently used to detect the presence of liquid water content over the GrIS. The sensor's penetration depth is dependent on the frequency (which determines wavelength) and time-varying geophysical properties (which determine absorption and scattering characteristics). At shorter spectral wavelengths, penetration depths are limited at the interface between the ice sheet surface and the atmosphere. Spectroradiometer-derived retrievals of liquid water content represent an integrated response on the order of a few millimeters. At longer microwave wavelengths (C- and Ku-band), penetration depths are increased. Scatterometer-derived retrievals of liquid water content represent an integrated response on the order of a few centimeters to several meters. We combine spectroradiometer data acquired from the Moderate Resolution Imaging Spectroradiometer aboard Terra and Aqua (MODIS) and C- and Ku-band scatterometer data acquired from MetOP-A (ASCAT) and OceanSAT-2 (OSCAT) to investigate the spatiotemporal variability of subsurface liquid water content on the GrIS. Penetration depth differences are exploited to distinguish between the detection of liquid water content

  9. The melting temperature of liquid water with the effective fragment potential

    Energy Technology Data Exchange (ETDEWEB)

    Brorsen, Kurt R.; Willow, Soohaeng Y.; Xantheas, Sotiris S.; Gordon, Mark S.

    2015-09-17

    Direct simulation of the solid-liquid water interface with the effective fragment potential (EFP) via the constant enthalpy and pressure (NPH) ensemble was used to estimate the melting temperature (Tm) of ice-Ih. Initial configurations and velocities, taken from equilibrated constant pressure and temperature (NPT) simulations at T = 300 K, 350 K and 400 K, respectively, yielded corresponding Tm values of 378±16 K, 382±14 K and 384±15 K. These estimates are consistently higher than experiment, albeit to the same degree with previously reported estimates using density functional theory (DFT)-based Born-Oppenheimer simulations with the Becke-Lee-Yang-Parr functional plus dispersion corrections (BLYP-D). KRB was supported by a Computational Science Graduate Fellowship from the Department of Energy. MSG was supported by a U.S. National Science Foundation Software Infrastructure (SI2) grant (ACI – 1047772). SSX acknowledges support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle.

  10. Methane excess in Arctic surface water-triggered by sea ice formation and melting.

    Science.gov (United States)

    Damm, E; Rudels, B; Schauer, U; Mau, S; Dieckmann, G

    2015-11-10

    Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence that sea ice is a potential source. We show that methane release from sea ice into the ocean occurs via brine drainage during freezing and melting i.e. in winter and spring. In summer under a fractional sea ice cover, reduced turbulence restricts gas transfer, then seawater acts as buffer in which methane remains entrained. However, in autumn and winter surface convection initiates pronounced efflux of methane from the ice covered ocean to the atmosphere. Our results demonstrate that sea ice-sourced methane cycles seasonally between sea ice, sea-ice-influenced seawater and the atmosphere, while the deeper ocean remains decoupled. Freshening due to summer sea ice retreat will enhance this decoupling, which restricts the capacity of the deeper Arctic Ocean to act as a sink for this greenhouse gas.

  11. Methane excess in Arctic surface water- triggered by sea ice formation and melting

    Science.gov (United States)

    Damm, E.; Rudels, B.; Schauer, U.; Mau, S.; Dieckmann, G.

    2015-11-01

    Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence that sea ice is a potential source. We show that methane release from sea ice into the ocean occurs via brine drainage during freezing and melting i.e. in winter and spring. In summer under a fractional sea ice cover, reduced turbulence restricts gas transfer, then seawater acts as buffer in which methane remains entrained. However, in autumn and winter surface convection initiates pronounced efflux of methane from the ice covered ocean to the atmosphere. Our results demonstrate that sea ice-sourced methane cycles seasonally between sea ice, sea-ice-influenced seawater and the atmosphere, while the deeper ocean remains decoupled. Freshening due to summer sea ice retreat will enhance this decoupling, which restricts the capacity of the deeper Arctic Ocean to act as a sink for this greenhouse gas.

  12. Dissolution Enhancement of Poorly Water Soluble Efavirenz by Hot Melt Extrusion Technique

    Directory of Open Access Journals (Sweden)

    Smita Kolhe

    2013-06-01

    Full Text Available Large number of drugs; including new chemical entity (NCE, are facing the solubility problem [classified as biopharmaceutical classification system (BCS Class II or IV]. Hence extensive development in solubility enhancement is required. Hot melt extrusion (HME is the most widely applied processing techniques useful for preparing granules, pellets, sustained release tablets, implants, transdermal and transmucosal drug delivery systems ,while its major advantages include enhancement of the dissolution rate and bioavailability, controlling or modifying drug release, taste masking, stabilizing the active pharmaceutical ingredient (API. Hot melt extruded dosage forms are generally complex mixtures of API, plastisizers and polymer carriers which are passed through single or twin-screw extruders at high temperature and stress, molten thermoplastic polymers during the extrusion process can function as thermal binders and/or release retardants. Present investigation deals with enhancement of dissolution rate and hence solubility of Efavirenz (Efv, which belongs to BCS class II. Efv is non neucleotide reverse transcriptase inhibitor (NNRTI for first line antiretroviral treatment type 1 with long half life of 52-56 hrs. Solubility enhancement techniques are available in wide range but HME was the preferred technique due to its several advantages. Copovidone (Kollidon VA64 as polymer and polyethylene glycol (PEG 4000, polyoxy 35 castor oil (Cremophor EL and sorbiton monolaurate (Montane 20 PHA as plasticizers were studied and optimized. Evaluation techniques like saturation solubility, effect of temperature on preparation of complexes, differential scanning calorimetry (DSC, x-ray diffraction (XRD, Infra red (IR, dissolution and in vitro permeability studies were carried out. XRD data concluded that HME process demolished the sharp peaks of Efv which indicate the complete conversion of crystal form of Efv to amorphous form. Dissolution and solubility

  13. Effects of water, depth and temperature on partial melting of mantle-wedge fluxed by hydrous sediment-melt in subduction zones

    Science.gov (United States)

    Mallik, Ananya; Dasgupta, Rajdeep; Tsuno, Kyusei; Nelson, Jared

    2016-12-01

    This study investigates the partial melting of variable bulk H2O-bearing parcels of mantle-wedge hybridized by partial melt derived from subducted metapelites, at pressure-temperature (P-T) conditions applicable to the hotter core of the mantle beneath volcanic arcs. Experiments are performed on mixtures of 25% sediment-melt and 75% fertile peridotite, from 1200 to 1300 °C, at 2 and 3 GPa, with bulk H2O concentrations of 4 and 6 wt.%. Combining the results from these experiments with previous experiments containing 2 wt.% bulk H2O (Mallik et al., 2015), it is observed that all melt compositions, except those produced in the lowest bulk H2O experiments at 3 GPa, are saturated with olivine and orthopyroxene. Also, higher bulk H2O concentration increases melt fraction at the same P-T condition, and causes exhaustion of garnet, phlogopite and clinopyroxene at lower temperatures, for a given pressure. The activity coefficient of silica (ϒSiO2) for olivine-orthopyroxene saturated melt compositions (where the activity of silica, aSiO2 , is buffered by the reaction olivine + SiO2 = orthopyroxene) from this study and from mantle melting studies in the literature are calculated. In melt compositions generated at 2 GPa or shallower, with increasing H2O concentration, ϒSiO2 increases from transition from non-ideal mixing as OH- in the melt (ϒSiO2 2 GPa, ϒSiO2 >1 at higher H2O concentrations in the melt, indicate requirement of excess energy to incorporate molecular H2O in the silicate melt structure, along with a preference for bridging species and polyhedral edge decorations. With vapor saturation in the presence of melt, ϒSiO2 decreases indicating approach towards ideal mixing of H2O in silicate melt. For similar H2O concentrations in the melt, ϒSiO2 for olivine-orthopyroxene saturated melts at 3 GPa is higher than melts at 2 GPa or shallower. This results in melts generated at 3 GPa being more silica-poor than melts at 2 GPa. Thus, variable bulk H2O and pressure of

  14. Selection of excipients for melt extrusion with two poorly water-soluble drugs by solubility parameter calculation and thermal analysis.

    Science.gov (United States)

    Forster, A; Hempenstall, J; Tucker, I; Rades, T

    2001-09-11

    The aim of this study was to determine the miscibility of drug and excipient to predict if glass solutions are likely to form when drug and excipient are melt extruded. Two poorly water-soluble drugs, indomethacin and lacidipine, were selected along with 11 excipients (polymeric and non-polymeric). Estimation of drug/excipient miscibility was performed using a combination of the Hoy and Hoftzyer/Van Krevelen methods for Hansen solubility parameter calculation. Miscibility was experimentally investigated with differential scanning calorimetry (DSC) and hot stage microscopy (HSM). Studies were performed at drug/excipient ratios, 1:4, 1:1 and 4:1. Analysis of the glass transition temperature (T(g)) was performed by quench cooling drug/excipient melts in the DSC. Differences in the drug/excipient solubility parameters of 10 MPa(1/2) were expected to indicate a lack of miscibility and not form glass solutions when melt extruded. Experimentally, miscibility was shown by changes in drug/excipient melting endotherms and confirmed by HSM investigations. Experimental results were in agreement with solubility parameter predictions. In addition, drug/excipient combinations predicted to be largely immiscible often exhibited more than one T(g) upon reheating in the DSC. Melt extrusion of miscible components resulted in amorphous solid solution formation, whereas extrusion of an "immiscible" component led to amorphous drug dispersed in crystalline excipient. In conclusion, combining calculation of Hansen solubility parameters with thermal analysis of drug/excipient miscibility can be successfully applied to predict formation of glass solutions with melt extrusion.

  15. Flocculation alters the distribution and flux of melt-water supplied sediments and nutrients in the Arctic

    DEFF Research Database (Denmark)

    Markussen, Thor Nygaard; Andersen, Thorbjørn Joest; Ernstsen, Verner Brandbyge;

    In the Arctic, thawing permafrost and increased melting of glaciers are important drivers for changes in fine-grained sediment supply and biogeochemical fluxes from land to sea. Flocculation of particles is a controlling factor for the magnitude of fluxes and deposition rates in the marine...... environment but comparatively little is known about the flocculation processes in the Arctic. We investigated flocculation dynamics from a melt-water river in the inner Disko Fjord, West Greenland. A novel, laser-illuminated camera system significantly improved the particle size measurement capabilities...... and settling tubes were sampled to enable sub-sampling of different floc size fractions. Flocculation was observed during periods with low turbulent shear and also at the front of the fresh water plume resulting in significant volumes of large sized flocs at depth below the plume. The floc sizes and volumes...

  16. Volatile Solubilities in Mt. Somma-Vesuvius Phonolite Melt and New Insights on Degassing of Sulfur, Chlorine, and Water

    Science.gov (United States)

    Webster, J. D.; Sintoni, M. F.; de Vivo, B.; Lima, A.

    2007-05-01

    To better understand volatile exsolution, degassing, and eruptive processes in subduction-related magmas, we have conducted thirty H2O plus S plus Cl solubility experiments with phonolite melt at 905 to 1000 deg. C, 200 MPa, and relatively oxidizing conditions. The experiments include an 8000-year old Mt. Somma-Vesuvius phonolite, distilled H2O, NaCl, KCl, and CaSO4, and they involve a new method of constraining the concentration of S in the run-product fluids. Unlike prior S-solubility experiments, the S concentration in fluid is determined as proportional to the mass loss of the anhydrite crystals in the starting charges of the experiments. This method provides accurate S contents of fluids. The H2O, Cl, and S concentrations of the phonolitic glasses of our experiments range from 4 to 8, 0.38 to 0.84, and 0.01 to 0.19 wt.%, respectively. Sulfur solubility increases with increasing CaO and FeO (total iron) in melt, decreasing Cl and K2O in melt, decreasing Cl in fluid(s), and with increasing oxygen fugacity values greater than NNO. Chlorine solubility in melt increases with decreasing S content of melt and decreasing S and H2O in the coexisting fluid(s). Water solubility in melt shows no systematic variation with melt composition, but varies strongly with the composition of fluids. The partition coefficients (wt.% of X in fluid[s]/wt.% of X in phonolitic melt) range from 40 to > 200 for S and from 12 to 87 for Cl. At pressure-temperature-oxygen fugacity conditions similar to those of this study, these partition coefficients are equivalent to those determined previously for natural equilibria involving andesite melt plus Cl-free, S-bearing aqueous fluid (Scaillet and Pichavant, 2003) and experimental equilibria with andesite melt plus S-free, Cl-bearing aqueous fluid (Webster et al., 1999), respectively. Our research also shows that these partition coefficients for S and Cl are inversely proportional to one another. Silicate melt inclusions in pyroxene phenocrysts

  17. Tailor-made release triggering from hot-melt extruded complexes of basic polyelectrolyte and poorly water-soluble drugs.

    Science.gov (United States)

    Kindermann, Christoph; Matthée, Karin; Strohmeyer, Jutta; Sievert, Frank; Breitkreutz, Jörg

    2011-10-01

    The aim of the study was the formulation of polyelectrolyte complexes composed of poorly water-soluble acid drugs and basic polymethacrylates by hot-melt extrusion enabling a tailor-made release pattern by the addition of inorganic salts. The influence of different electrolytes was analyzed at varying conditions in order to control drug delivery from the complexes. Poorly water-soluble model drugs naproxen and furosemide were applied in their non-ionic form. After hot-melt extrusion of the naproxen-polymethacrylate powder blend, XRPD and DSC measurements indicated the formation of a single-phase amorphous system. Milled extrudates were stable under storage at long-term and intermediate conditions. Polyelectrolyte complex formation by an acid-base reaction during hot-melt extrusion could be proven by the lack of vibrations of dimethylamino and carboxylic groups by FT-IR and Raman spectroscopy. The complexes did not dissolve in demineralized water. Drug release could be immediately induced by addition of neutral electrolytes. Tailor-made dissolution profiles were realized by controlled electrolyte triggering. Maximal effects were achieved by concentrations of 0.05-0.15 M NaCl. Different anions of alkali halogenides revealed variant magnitudes of the effect depending on the anion radius. Polyelectrolyte complex formation and dissolution principles were also confirmed for furosemide.

  18. Effect of Bulk Water Concentration on Mantle Wedge Hybridization by Rhyolitic Sediment Melt - Implications for Generation of K-rich Basalts to Andesites in Subduction Zones

    Science.gov (United States)

    Mallik, A.; Dasgupta, R.; Nelson, J. M.; Tsuno, K.

    2014-12-01

    Similarities in trace element geochemistry between ocean-floor sediments and arc lavas suggest the involvement of subducted sediments in the mantle source of arc volcanoes. Siliciclastic sediments produce rhyo-dacitic, hydrous partial melts at sub-arc depths, which must react with wedge peridotite during their ascent. In addition to fluids, these sediment melts can be a major carrier of water to the arc source. Here we investigate the effects of bulk water concentration on the phase equilibria of reaction between sediment partial melt and peridotite. Piston-cylinder experiments were performed using Au-Pd capsules, at 2 and 3 GPa, 1050 - 1350 °C with mixtures of 25% rhyolite + 75% lherzolite, bearing bulk water content of 2 (low-water) and 4 wt.% (high-water). Melting degree is higher in high-water experiments at both 2 and 3 GPa with a sharp increase in melt mode from 31 to 53 wt.% at 1250-1300 °C, 2 GPa and 21 to 49 wt.% at 1225-1250 °C, 3 GPa. This sharp increase in melt mode is accompanied by a corresponding abrupt increase in residual olivine to opx ratio at both pressures (0.11 to 0.53 at 1250-1300 °C, 2 GPa and 0 to 0.71 at 1225-1250 °C, 3 GPa). The stability field of phlogopite, clinopyroxene, and garnet are reduced in high-water experiments due to higher degrees of partial melting. Low-water experiments produce basalts with SiO2, on a volatile-free basis, increasing from 49 to 51 wt.% at 2 GPa and 46 to 48 wt.% at 3 GPa. For high-water experiments, melt SiO2 contents at 2 GPa are slightly higher than those in low-water experiments for a given temperature, varying from 51 to 52 wt.%, and, at 3 GPa, the melts trend towards andesitic compositions with SiO2 ~54 wt.%. These compositional characteristics of the melts can be attributed to the effect of increased olivine to opx ratios in the residue as a function of increasing bulk water concentration. Our study shows that a spectrum of ultra-potassic, high-Mg arc lavas (MgO varying from 10-16 wt.%) from

  19. In-vessel coolability and retention of a core melt

    Energy Technology Data Exchange (ETDEWEB)

    Theofanous, T.G.; Liu, C.; Additon, S. [Univ. of California, Santa Barbara, CA (United States)] [and others

    1997-02-01

    The efficacy of external flooding of a reactor vessel as a severe accident management strategy is assessed for an AP600-like reactor design. The overall approach is based on the Risk Oriented Accident Analysis Methodology (ROAAM), and the assessment includes consideration of bounding scenarios and sensitivity studies, as well as arbitrary parametric evaluations that allow the delineation of the failure boundaries. The technical treatment in this assessment includes: (a) new data on energy flow from either volumetrically heated pools or non-heated layers on top, boiling and critical heat flux in inverted, curved geometries, emissivity of molten (superheated) samples of steel, and chemical reactivity proof tests, (b) a simple but accurate mathematical formulation that allows prediction of thermal loads by means of convenient hand calculations, (c) a detailed model programmed on the computer to sample input parameters over the uncertainty ranges, and to produce probability distributions of thermal loads and margins for departure from nucleate boiling at each angular position on the lower head, and (d) detailed structural evaluations that demonstrate that departure from nucleate boiling is a necessary and sufficient criterion for failure. Quantification of the input parameters is carried out for an AP600-like design, and the results of the assessment demonstrate that lower head failure is {open_quotes}physically unreasonable.{close_quotes} Use of this conclusion for any specific application is subject to verifying the required reliability of the depressurization and cavity-flooding systems, and to showing the appropriateness (in relation to the database presented here, or by further testing as necessary) of the thermal insulation design and of the external surface properties of the lower head, including any applicable coatings.

  20. A study on the late core melt progression in pressurized water reactor severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jae Hong; Jeun Gyoo Dong; Bang, Kwang Hyun; Park, Seh In; Lim, Jae Hyuck; Park, Seong Yong [Hanyang Univ., Seoul (Korea, Republic of); Back, Hyung Hmm [Korea Maritime Univ., Busan (Korea, Republic of)

    1998-03-15

    After TMI-2 accidents, it has been paid much attention to severe accidents beyond the design basis accidents and the research on the progress of severe accidents and mitigation and the closure of severe accidents has been actively performed. In particular, a great deal of uncertainties yet exist in the phase of late core melt progression and thus the research on this phase of severe accident progress has a key role in obtaining in severe accident mitigation and nuclear reactor safety. In the present study, physics of late core melt progression, experimental data and the major phenomenological models of computer codes are reviewed and a direction of reducing the uncertainties in the late core melt progression os proposed.

  1. Nano-pulverization of poorly water soluble compounds with low melting points by a rotation/revolution pulverizer.

    Science.gov (United States)

    Yuminoki, K; Takeda, M; Kitamura, K; Numata, S; Kimura, K; Takatsuka, T; Hashimoto, N

    2012-08-01

    We report a method for pulverizing poorly water soluble compounds with low melting points to nanoparticles without producing an amorphous phase using a rotation/revolution pulverizer. Fenofibrate, flurbiprofen, and probucol were used as crystalline model compounds. They were suspended in a methylcellulose aqueous solution and pulverized with zirconia balls by the rotation/revolution pulverizer. Beeswax, an amorphous compound, was also examined to investigate whether nano-pulverization of a compound with a low melting point was possible. Beeswax was suspended in ethyl alcohol cooled with liquid nitrogen and pulverized with zirconia balls by the rotation/revolution pulverizer. By optimizing the pulverization parameters, nanoparticles (D50 revolution speed of 1000 rpm and a rotation/revolution ratio of 1.0 when the vessel was 0 degrees C. Amorphous fenofibrate and flurbiprofen were not detected by differential scanning calorimetry or powder X-ray diffraction, whereas small amounts of amorphous probucol were detected. Beeswax was pulverized to nanoparticles (D50 = 0.14 microm) with ethyl alcohol cooled with liquid nitrogen. Fine nanoparticles of these poorly water soluble compounds with low melting points were obtained by controlling the rotation/revolution speed and reducing the vessel temperature.

  2. The Primary Research on the Variation of Melted Water Quality and Quantity During Saline Ice Melting%咸水结冰融化过程中水质与水量的变化规律初步研究

    Institute of Scientific and Technical Information of China (English)

    郭凯; 刘小京

    2013-01-01

    在室内利用相同水量、不同矿化度和钠吸附比(SAR)的咸水进行结冰融化,以研究其在融化过程中水质和水量的变化过程.结果表明,成水冰在融化过程中淡化效果明显,其中利用10 g/L的成水冰,融出49%小于3 g/L的微咸水和淡水;矿化度越高的咸水冰,在融化初期融出水的矿化度、体积和SAR越高,而淡化效果越差,融化1h后15 g/L的咸水冰融出水的矿化度和SAR分另为136.8 g/L和67.5,高于5 g/L和10 g/L的成水冰处理;高SAR的成水冰,在融化初期融出水主要表现在SAR较高,利用SAR为5、10和30的咸水冰进行融化,融化1h后,融出水的SAR值分别为82.5、56.4和22.3,其中矿化度和体积无显著差异;在以上基础上,建立了关于不同水质的咸水冰在不同温度条件下的二元回归方程,利用该方程可知,矿化度较低的咸水冰在低的温度条件下融化,淡化效果越好.%A laboratory experiment was conducted to investigate the quality and quantity of melted water during the saline ice with different salinity and sodium adsorption ratio levels melting. The results were as follows: The desalinization effect was obvious during the saline ice melting, and about 49% slight saline water that below 3 g/L was melted out using saline ice with 10 g/L salinity level. The salinity, volume and SAR level were higher when the higher salinity saline ice started melting, and the desalinization effect of higher salinity level saline ice treatment was worse than lower one. The salinity and SAR value of melted water were 136. 8 g/L and 67. 5 respectively one hour after the saline ice with 15 g/L melted, which were higher than saline ice treatments of 5 g/L and 10 g/L. The SAR value of melted water was higher during higher SAR level saline ice melting. One hour after the saline ice with 5, 10 and 30 SAR level, the SAR value were 82. 5, 56. 4 and 22. 3 of melted water respectively, while the salinity and volume had no significant

  3. Rheology and Structure of Chlorine, Fluorine and Water-Bearing Na2O-CaO-Al2O3-SiO2 Melts

    Science.gov (United States)

    Baasner, A.; Schmidt, B.; Webb, S. L.; Dupree, R.

    2012-12-01

    The effect of chlorine (Cl), fluorine (F) and water (H2O), alone and in combination, on the rheology and structure of synthetic peralkaline Na2O-CaO-Al2O3-SiO2 melts as an analog for highly evolved alkaline melts is investigated. We also investigated a peraluminous counterpart to study how the effect of Cl and F depends on the (Na+Ca)/Al ratio. The volatile-free melts were produced from oxide and carbonate powders at 1 atm and temperatures between 1200 and 1650 °C. Amounts of 0.5 to 1.3 mol% of Cl and 0.5 to 18 mol% F were added as NH4Cl, NH4F, NaCl, NaF, CaCl2 and CaF2. The composition of the samples was analysed by electron microprobe. The melts were hydrated with 0.5 to 4 wt% H2O. For the hydration of the peralkaline melts we used an internally heated pressure vessel at 1200 to 1250 °C and 1.5 to 3 kbar. Because of their high liquidus temperatures, the peraluminous melts were hydrated at 1600 to 1675°C and 5 kbar in a piston cylinder apparatus. Water contents were determined by Karl-Fischer-titration, thermogravimetry and IR-spectroscopy. The viscosities of the dry and hydrous peralkaline and peraluminous melts were measured with micropenetration and parallel plate techniques between 13 log10(Pa s) and 5.5 log10(Pa s). We found that the addition of 1.1 mol% Cl to peralkaline melts increased the viscosity by 0.8 log10(Pa s) while 1.9 mol% F decreased the viscosity by 1.2 log10(Pa s) relative to a viscosity of 12 log10(Pa s) of the halogen-free melt. In peralkaline melts containing equal amounts of both, Cl and F, the viscosity is 0.5 log10(Pa s) lower than the volatile-free melt, independent of the total amount of halogens. The effects of Cl and F seem to buffer each other. If there is twice as much F in the melt as Cl, the viscosity is reduced by 0.7 log10(Pa s). In peraluminous melts containing Cl and F the viscosity decreases with increasing volatile content independent of the ratio between the two volatiles. The addition of H2O decreases the viscosity of

  4. [Chemical composition and daily variation of melt water during ablation season in monsoonal temperate Glacier region: a case study of Baishui Glacier No. 1].

    Science.gov (United States)

    Zhu, Guo-Feng; Pu, Tao; He, Yuan-Qing; Wang, Pei-Zhen; Kong, Jian-Long; Zhang, Ning-Ning; Xin, Hui-Juan

    2012-12-01

    Melt water samples collected continuously from 29 August to 3 September 2009 in the Baishui Glacier No. 1 at elevation of 4750 m were analyzed for pH, conductivity, delta18O and inorganic ions. The results showed that the pH had obvious diurnal variations and was increased slightly by the influence of precipitation. The dissolution of alkaline soluble salts in the dust was the main reason for the increase of melt water conductivity; the value of delta18O was relatively low in strong ablation period and high in slight ablation period. Different from other research areas, the concentrations of Na+, K+, which were influenced by lithological and marine water vapor, were higher than that of Mg2+ in the study area; HCO3- and Ca2+ accounted for more than 80% of total ions in snow and ice melt water, indicating that the ions mainly came from limestone and the melt water was a typical carbonate solution; The content of melt water had an obvious daily change with temperature change, but the response amplitudes were different; Monsoon transport, local rock lithology, human industrial and agricultural activities were the main sources of inorganic ions and the deciding factors of the ion composition in the Baishui Glacier No. 1.

  5. Efficient one-step melt-compounding of copolyetheramide/pristine clay nanocomposites using water-injection as intercalating/exfoliating aid

    Directory of Open Access Journals (Sweden)

    J. Soulestin

    2011-12-01

    Full Text Available Polyether-block-amide (PEBA /clay nanocomposites were prepared water-assisted by twin-screw extrusion. Both organomodified and pristine (i.e. purified but non-modified montmorillonite clays were used. A high-pressure differential scanning calorimetry analysis carried out in the processing conditions demonstrated that PEBA/water blend exhibits some miscibility and that amide blocks and water behave as a single phase. In addition to a significant decrease of the melting temperature, water injected into the melt plays a key role among the filler dispersion and prevents the matrix from degradation during melt-extrusion. This process enables the compounding of pristine clay-based nanocomposites whose dispersion state is high enough for the resulting mechanical performances in tension to be at least equivalent to what is reached with organomodified clay. Effects of the nanofiller dispersion onto the macromolecules’ mobility are detailed and fracture mechanisms are identified for the various structures.

  6. Coexisting methane and oxygen excesses in nitrate-limited polar water (Fram Strait during ongoing sea ice melting

    Directory of Open Access Journals (Sweden)

    E. Damm

    2011-05-01

    Full Text Available Summer sea ice cover in the Arctic Ocean has undergone a reduction in the last decade exposing the sea surface to unforeseen environmental changes. Melting sea ice increases water stratification and induces nutrient limitation, which is also known to play a crucial role in methane formation in oxygenated surface water. We report on a hotspot of methane formation in the marginal ice zone in the western Fram Strait. Our study is based on measurements of oxygen, methane, DMSP, nitrate and phosphate concentrations as well as on phytoplankton composition and light transmission, conducted along the 79° N oceanographic transect. We show that between the eastern Fram Strait, where Atlantic water enters from the south and the western Fram Strait, where Polar water enters from the north, different nutrient limitation occurs and consequently different bloom conditions were established. Ongoing sea ice melting enhances the environmental differences and initiates regenerated production in the western Fram Strait. In a unique biogeochemical feedback process, methane production occurs despite an oxygen excess. We postulate that DMSP (dimethylsulfoniopropionate released from sea ice may serve as a precursor for methane formation. Thus, feedback effects on cycling pathways of methane are likely, with DMSP catabolism in high latitudes possibly contributing to a warming effect on the earth's climate. This process could constitute an additional component in biogeochemical cycling in a seasonal ice-free Arctic Ocean. The metabolic activity (respiration of unicellular organisms explains the presence of anaerobic conditions in the cellular environment. Therefore we present a theoretical model which explains the maintenance of anaerobic conditions for methane formation inside bacterial cells, despite enhanced oxygen concentrations in the environment.

  7. Coexisting methane and oxygen excesses in nitrate-limited polar water (Fram Strait) during ongoing sea ice melting

    Science.gov (United States)

    Damm, E.; Thoms, S.; Kattner, G.; Beszczynska-Möller, A.; Nöthig, E. M.; Stimac, I.

    2011-05-01

    Summer sea ice cover in the Arctic Ocean has undergone a reduction in the last decade exposing the sea surface to unforeseen environmental changes. Melting sea ice increases water stratification and induces nutrient limitation, which is also known to play a crucial role in methane formation in oxygenated surface water. We report on a hotspot of methane formation in the marginal ice zone in the western Fram Strait. Our study is based on measurements of oxygen, methane, DMSP, nitrate and phosphate concentrations as well as on phytoplankton composition and light transmission, conducted along the 79° N oceanographic transect. We show that between the eastern Fram Strait, where Atlantic water enters from the south and the western Fram Strait, where Polar water enters from the north, different nutrient limitation occurs and consequently different bloom conditions were established. Ongoing sea ice melting enhances the environmental differences and initiates regenerated production in the western Fram Strait. In a unique biogeochemical feedback process, methane production occurs despite an oxygen excess. We postulate that DMSP (dimethylsulfoniopropionate) released from sea ice may serve as a precursor for methane formation. Thus, feedback effects on cycling pathways of methane are likely, with DMSP catabolism in high latitudes possibly contributing to a warming effect on the earth's climate. This process could constitute an additional component in biogeochemical cycling in a seasonal ice-free Arctic Ocean. The metabolic activity (respiration) of unicellular organisms explains the presence of anaerobic conditions in the cellular environment. Therefore we present a theoretical model which explains the maintenance of anaerobic conditions for methane formation inside bacterial cells, despite enhanced oxygen concentrations in the environment.

  8. Experimental Evidence for Fast Lithium Diffusion and Isotope Fractionation in Water-bearing Rhyolitic Melts at Magmatic Conditions

    Science.gov (United States)

    Cichy, S. B.; Till, C. B.; Roggensack, K.; Hervig, R. L.; Clarke, A. B.

    2015-12-01

    The aim of this work is to extend the existing database of experimentally-determined lithium diffusion coefficients to more natural cases of water-bearing melts at the pressure-temperature range of the upper crust. In particular, we are investigating Li intra-melt and melt-vapor diffusion and Li isotope fractionation, which have the potential to record short-lived magmatic processes (seconds to hours) in the shallow crust, especially during decompression-induced magma degassing. Hydrated intra-melt Li diffusion-couple experiments on Los Posos rhyolite glass [1] were performed in a piston cylinder at 300 MPa and 1050 °C. The polished interfaces between the diffusion couples were marked by addition of Pt powder for post-run detection. Secondary ion mass spectrometry analyses indicate that lithium diffuses extremely fast in the presence of water. Re-equilibration of a hydrated ~2.5 mm long diffusion-couple experiment was observed during the heating period from room temperature to the final temperature of 1050 °C at a rate of ~32 °C/min. Fractionation of ~40‰ δ7Li was also detected in this zero-time experiment. The 0.5h and 3h runs show progressively higher degrees of re-equilibration, while the isotope fractionation becomes imperceptible. Li contamination was observed in some experiments when flakes filed off Pt tubing were used to mark the diffusion couple boundary, while the use of high purity Pt powder produced better results and allowed easier detection of the diffusion-couple boundary. The preliminary lithium isotope fractionation results (δ7Li vs. distance) support findings from [2] that 6Li diffuses substantially faster than 7Li. Further experimental sets are in progress, including lower run temperatures (e.g. 900 °C), faster heating procedure (~100 °C/min), shorter run durations and the extension to mafic systems. [1] Stanton (1990) Ph.D. thesis, Arizona State Univ., [2] Richter et al. (2003) GCA 67, 3905-3923.

  9. Evaluation of In-Vessel Corium Retention under a Severe Accident

    Energy Technology Data Exchange (ETDEWEB)

    Park, Rae-Joon; Kang, Kyung-Ho; Ha, Kwang-Soon; Kim, Jong-Tae; Koo, Kil-Mo; Cho, Young-Ro; Hong, Seong-Wan; Kim, Sang-Baik; Kim, Hee-Dong

    2008-02-15

    The current study on In-Vessel corium Retention and its application activities to the actual nuclear power plant have been reviewed and discussed in this study. Severe accident sequence which determines an initial condition of the IVR has been evaluated and late phase melt progression, heat transfer on the outer reactor vessel, and in-vessel corium cooling mechanism have been estimated in detail. During the high pressure sequence of the reactor coolant system, a natural circulation flow of the hot steam leads to a failure of the pressurizer surge line before the reactor vessel failure, which leads to a rapid decrease of the reactor coolant system pressure. The results of RASPLAV/MASCA study by OECD/NEA have shown that a melt stratification has occurred in the lower plenum of the reactor vessel. In particular, laver inversion has occurred, which is that a high density of the metal melt moves to the lower part of the oxidic melt layer. A method of heat transfer enhancement on the outer reactor vessel is an optimal design of the reactor vessel insulation for an increase of the natural circulation flow between the outer reactor vessel and the its insulation, and an increase of the critical Heat flux on the outer reactor vessel by using various method, such as Nono fluid, coated reactor vessel, and so on. An increase method of the in-vessel melt cooling is a development of the In-vessel core catcher and a decrease of focusing effect in the metal layer.

  10. Hydrous melting and partitioning in and above the mantle transition zone: Insights from water-rich MgO-SiO2-H2O experiments

    Science.gov (United States)

    Myhill, R.; Frost, D. J.; Novella, D.

    2017-03-01

    Hydrous melting at high pressures affects the physical properties, dynamics and chemical differentiation of the Earth. However, probing the compositions of hydrous melts at the conditions of the deeper mantle such as the transition zone has traditionally been challenging. In this study, we conducted high pressure multianvil experiments at 13 GPa between 1200 and 1900 °C to investigate the liquidus in the system MgO-SiO2-H2O. Water-rich starting compositions were created using platinic acid (H2Pt(OH)6) as a novel water source. As MgO:SiO2 ratios decrease, the T -XH2O liquidus curve develops an increasingly pronounced concave-up topology. The melting point reduction of enstatite and stishovite at low water contents exceeds that predicted by simple ideal models of hydrogen speciation. We discuss the implications of these results with respect to the behaviour of melts in the deep upper mantle and transition zone, and present new models describing the partitioning of water between the olivine polymorphs and associated hydrous melts.

  11. Needleless Melt-Electrospinning of Biodegradable Poly(Lactic Acid Ultrafine Fibers for the Removal of Oil from Water

    Directory of Open Access Journals (Sweden)

    Haoyi Li

    2017-01-01

    Full Text Available As environmentally friendly and degradable material, Poly(lactic acid (PLA ultrafine fibers are promising candidates for the removal of oil from water. In this work, a self-established needleless melt-electrospinning process was used to produce PLA ultrafine fibers with diameters in the range of 800 nm–9 µm. In order to obtain ultrafine fibers, three types of hyperbranched polymers were respectively added into the melt for electrospinning. Effects of amount and molecular weight of the added hyperbranched polymers on average fiber diameter and its distribution, and contact angle were investigated. The prepared PLA ultrafine fibers exhibited superhydrophobicity with the contact angle as high as 156°, making it a potential candidate in marine oil spill recovery. The oil sorption capability of these fibers is as high as 159, 118, and 96 g/g for motor oil, crude oil, and diesel, respectively. Even after seven cycles of reuse, the fiber still maintained about 60% of its initial capacity of sorption. The kinetics of oil sorption in the film agrees very well with the pseudo-second-order kinetic model. This work is expected to promote the mass production and application of biodegradable PLA fibers in the treatment of marine oil spill pollution.

  12. Low-Ti melts from the southeastern Siberian Traps Large Igneous Province: Evidence for a water-rich mantle source?

    Indian Academy of Sciences (India)

    Alexei V Ivanov; Elena I Demonterova; Sergei V Rasskazov; Tatyana A Yasnygina

    2008-02-01

    Siberian Traps Large Igneous Province (STLIP) is one of the most voluminous volcanic provinces on Earth. The dominant erupted rocks are low-Ti basalts, which make up 80% by volume of the classical Noril’sk lava sequence. In the west Siberian basin and Maymecha-Kotuy area, the low- Ti basalts make up about 99% and 50% by volume, respectively. Dolerite sills in the Angara– Taseevskaya Syncline at the southeastern STLIP exhibit trace element patterns and Sr isotope ratios typical of the low-Ti basalts of the Noril’sk sequence. The most Mg-rich (MgO 9.5–11 wt%) and hence least differentiated dolerites are characterized by trace element patterns with Ta-Nb depletion, low Ce/Pb and high Sr/Pr. These trace element features are similar to water-saturated, mantle wedge-derived island arc basalts. These imply an important role of subduction fluid-derived trace elements in the source of melting beneath the Angara–Taseevskaya Syncline and other regions of the STLIP. Less magnesium rocks (MgO 3.8–6.1 wt%) with less prominent Ta-Nb depletion, higher Ce/Pb and lower Sr/Pr could be produced via olivine-plagioclase fractionation of primary high-magnesium melts.

  13. The influence of Greenland melt water on climate during past and future warm periods: a model study

    Science.gov (United States)

    Blaschek, Michael; Bakker, Pepijn; Renssen, Hans

    2013-04-01

    "Can past climates teach us something about the future?" Under this general question of interest to most palaeoclimate-modeller we specified it more to "Can past changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) related to melt water from the Greenland Ice Sheet (GIS) teach us something about future changes in the AMOC forced by predicted partial melting of the GIS?" To address this question, we developed a series of sensitivity experiments with the global atmosphere-ocean-sea-ice model LOVECLIM to better understand the relationship between the strength of the Atlantic Meridional Overturning Circulation (AMOC) and Greenland Ice Sheet (GIS) melt over the last and present interglacials (the Eemian and the Holocene, respectively) and put these into perspective of future greenhouse gas emission scenarios. In terms of radiative forcing, future emission scenarios are different from past orbitally-forced warm periods, as past insolation varied per season and per latitude, whereas radiative forcing due to future greenhouse gas emissions has no seasonal component (i.e. it is an annual forcing) and shows little variation per latitude. However, the two can be compared when we consider the radiative forcing regimes of the different considered warm climates, by focusing on the energy that is potentially available from radiative forcing to melt the GIS. In a similar approach, Swingedouw et al. (2009) have shown in simulations with an AOGCM that the AMOC sensitivity relates non-linear to freshwater input and that under Last Glacial Maximum (LGM) conditions the climate is more sensitive compared to warmer climates. They conclude that different climatic conditions share similar patterns in response and that past climates are useful for models to evaluate their abilities in reproducing past events. The authors encourage further model sensitivity testing to gain a better understanding of this highly important question. In order to test this approach we

  14. Impact of Snow Melt Water on Aalfalfa Sseedlings%雪水对苜蓿幼苗的影响

    Institute of Scientific and Technical Information of China (English)

    曲善民; 刘艾; 杜广明; 李建英; 李国良; 杨智明; 鞠晓峰

    2012-01-01

    采用盆钵垂直板法,研究了清水和雪水对紫花苜蓿在幼苗生长过程中的影响,对两组苜蓿幼苗的株高、根长、茎粗、物质积累等指标进行了对比分析。结果表明:雪水处理组的苜蓿幼苗生长状态明显优于清水处理组,发芽率较对照平均高出28.26%,株高、茎粗、干物质积累均显著高于对照(P〈5%),根长与对照相比较无显著差异(P〉5%),雪水对苜蓿幼苗生长具有显著促进效应。建议:在农业生产中,广泛应用雪水促进牧草饲料作物增产丰收,尤其雪水浸种对改善作物苗期的生长势效果明显。%The paper have Separately studied the influnce of running water and snow melt water on alfalfa in seedling growth process, adopting the basin-port vertical slab method,and carries out a comparative analysis of two groups of alfalfa seedlings height, root length,stem diameter,matter accumulation of such indicators.To alfalfa seedlings growth state,results show that snow water treatment group obviously superior water treatment groups,high 28.26% than the average.Stem diameter,dry matter accumulation were significantly higher than controls(p5%),compared with controls for root no significant difference(p5%),snow melt water to alfalfa seedlings significantly promote effect.Suggestion: the wide applications on pasture feed will promote increasing harvest in the agricultural production,especially with snow smelt water soaked seeds,to improve crop seedling growth vigour influnce is obvious.

  15. Melting glaciers stimulate large summer phytoplankton blooms in southwest Greenland waters

    Science.gov (United States)

    Arrigo, Kevin R.; van Dijken, Gert L.; Castelao, Renato M.; Luo, Hao; Rennermalm, Ósa K.; Tedesco, Marco; Mote, Thomas L.; Oliver, Hilde; Yager, Patricia L.

    2017-06-01

    Each summer, large quantities of freshwater and associated dissolved and particulate material are released from the Greenland Ice Sheet (GrIS) into local fjords where they promote local phytoplankton growth. Whether the influx of freshwater and associated micronutrients in glacial meltwater is able to stimulate phytoplankton growth beyond the fjords is disputed, however. Here we show that the arrival of freshwater discharge from outlet glaciers from both southeast and southwest GrIS coincides with large-scale blooms in the Labrador Sea that extend over 300 km from the coast during summer. This summer bloom develops about a week after the arrival of glacial meltwater in early July and persists until the input of glacial meltwater slows in August or September, accounting for 40% of annual net primary production for the area. In view of the absence of a significant change in the depth of the mixed layer associated with the arrival of glacial meltwater to the Labrador Sea, we suggest that the increase in phytoplankton biomass and productivity in summer is likely driven by a greater nutrient supply (most likely iron). Our results highlight that the ecological impact of meltwater from the GrIS likely extends far beyond the boundaries of the local fjords, encompassing much of the eastern Labrador Sea. Such impacts may increase if melting of the GrIS accelerates as predicted.

  16. Freezing and melting of water in porous geomaterials studied by magnetic resonance

    OpenAIRE

    2010-01-01

    We intend to study mechanical effects of freezing and thawing on bulky samples of concrete by nuclear resonance high resolution spectroscopy and imaging (MRI). Variously functionalised three dimensional images of liquid water in the porous media can be obtained by MRI. NMR spectroscopy, on the other hand, can be used to directly measure the total quantity of liquid water as a function of temperature. Moreover, measurements of magnetic spin relaxation rates and diffusion can provide info...

  17. Diazotroph diversity in the sea ice, melt ponds and surface waters of the Eurasian Basin of the Central Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Mar Fernández-Méndez

    2016-11-01

    Full Text Available The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing towards a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77ºN. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed.

  18. Diazotroph Diversity in the Sea Ice, Melt Ponds, and Surface Waters of the Eurasian Basin of the Central Arctic Ocean

    Science.gov (United States)

    Fernández-Méndez, Mar; Turk-Kubo, Kendra A.; Buttigieg, Pier L.; Rapp, Josephine Z.; Krumpen, Thomas; Zehr, Jonathan P.; Boetius, Antje

    2016-01-01

    The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing toward a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77°N. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed. PMID:27933047

  19. Diazotroph Diversity in the Sea Ice, Melt Ponds, and Surface Waters of the Eurasian Basin of the Central Arctic Ocean.

    Science.gov (United States)

    Fernández-Méndez, Mar; Turk-Kubo, Kendra A; Buttigieg, Pier L; Rapp, Josephine Z; Krumpen, Thomas; Zehr, Jonathan P; Boetius, Antje

    2016-01-01

    The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing toward a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77°N. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed.

  20. A coupled melt-freeze temperature index approach in a one-layer model to predict bulk volumetric liquid water content dynamics in snow

    Science.gov (United States)

    Avanzi, Francesco; Yamaguchi, Satoru; Hirashima, Hiroyuki; De Michele, Carlo

    2016-04-01

    Liquid water in snow rules runoff dynamics and wet snow avalanches release. Moreover, it affects snow viscosity and snow albedo. As a result, measuring and modeling liquid water dynamics in snow have important implications for many scientific applications. However, measurements are usually challenging, while modeling is difficult due to an overlap of mechanical, thermal and hydraulic processes. Here, we evaluate the use of a simple one-layer one-dimensional model to predict hourly time-series of bulk volumetric liquid water content in seasonal snow. The model considers both a simple temperature-index approach (melt only) and a coupled melt-freeze temperature-index approach that is able to reconstruct melt-freeze dynamics. Performance of this approach is evaluated at three sites in Japan. These sites (Nagaoka, Shinjo and Sapporo) present multi-year time-series of snow and meteorological data, vertical profiles of snow physical properties and snow melt lysimeters data. These data-sets are an interesting opportunity to test this application in different climatic conditions, as sites span a wide latitudinal range and are subjected to different snow conditions during the season. When melt-freeze dynamics are included in the model, results show that median absolute differences between observations and predictions of bulk volumetric liquid water content are consistently lower than 1 vol%. Moreover, the model is able to predict an observed dry condition of the snowpack in 80% of observed cases at a non-calibration site, where parameters from calibration sites are transferred. Overall, the analysis show that a coupled melt-freeze temperature-index approach may be a valid solution to predict average wetness conditions of a snow cover at local scale.

  1. In-vessel coolability and steam explosion in Nordic BWRs

    Energy Technology Data Exchange (ETDEWEB)

    Ma, W.; Li, L.; Hansson, R.; Villanueva, W.; Kudinov, P.; Manickam, L.; Tran, C.-T. (Royal Institute of Technology (KTH) (Sweden))

    2011-05-15

    The objective of this research is to reduce the uncertainty in quantification of steam explosion risk and in-vessel coolability in the Nordic BWR plants which employ cavity flooding as severe accident management (SAM) strategy. To quantify the coolability of debris bed packed with irregular particles, the friction laws of fluid flow in particulate beds packed with non-spherical particles were investigated on the POMECO-FL test facility, and the experimental data suggest that the Ergun equation is applicable if the effective particle diameter of the particles is represented by the equivalent diameter of the particles, which is the product of Sauter mean diameter and shape factor of the particles. One-way coupling analysis between PECM model for melt pool heat transfer and ANSYS thermo-structural mechanics was performed to analyze the vessel creep, and the results revealed two different modes of vessel failure: a 'ballooning' of the vessel bottom and a 'localized creep' concentrated within the vicinity of the top surface of the melt pool. Single-droplet steam explosion experiments were carried out by using oxidic mixture of WO{sub 3}-CaO, and the results show an apparent difference in steam explosion energetics between the eutectic and non-eutectic melts at low melt superheat (100 deg. C). (Author)

  2. Reconsidering Melt-water Pulses 1A and 1B:Global Impacts of Rapid Sea-level Rise

    Institute of Scientific and Technical Information of China (English)

    J.Paul Liu; John D.Milliman

    2004-01-01

    Re-evaluation of the post-glacial sea level derived from the Barbados coral-reef borings suggests slightly revised depth ranges and timing of melt-water pulses MWP-1A(96-76 m, 14.3-14.0 ka cal BP)and 1B(58-45 m, 11.5-11.2 ka cal BP), respectively. Ages of non-reef sea-level indicators from the Sunda Shelf, the East China Sea and Yellow Sea for these two intervals are unreliable because of the well-documented radiocarbon(14C)plateau, but their vertical clustering corresponds closely with MWP-1A and 1B depth ranges. Close correlation of the revised sea-level curve with Greenland ice-core data suggests that the 14C plateau may be related to oceanographic-atmospheric changes due to rapid sea-level rise, fresh-water input, and impaired ocean circulation. MWP-1A appears to have occurred at the end of Blling Warm Transition, suggesting that the rapid sea-level rise may have resulted from lateral heat transport from low to high-latitude regions and subsequent abrupt ice-sheet collapses in both North America-Europe and Antarctica. An around 70 mm a-1 transgression during MWP-1A may have increased freshwater discharge to the North Atlantic by as much as an order of magnitude, thereby disturbing thermohaline circulation and initiating the Older Dryas global cooling.

  3. Methane excess in Arctic surface water-triggered by sea ice formation and melting

    OpenAIRE

    Damm, E.; Rudels, B.; Schauer, U.; Mau, S.; Dieckmann, G.

    2015-01-01

    Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence t...

  4. Process and formulation variables in the preparation of wax microparticles by a melt dispersion technique. I. Oil-in-water technique for water-insoluble drugs.

    Science.gov (United States)

    Bodmeier, R; Wang, J; Bhagwatwar, H

    1992-01-01

    Ibuprofen-wax (carnauba, paraffin, beeswax, and the semisynthetic glyceryl esters--Gelucire 64/02 and Precirol ATO5) microparticles were prepared without organic solvents as an alternative to polymeric microparticles. In the melt dispersion technique, the drug-wax melt was emulsified into a heated aqueous phase followed by cooling to form the microparticles. The microparticles were characterized with respect to their drug loading, and morphological and release properties. They were spherical and non-agglomerated and drug loading close to 60 per cent were achieved. The more hydrophilic waxes (Gelucire 64/02 or Precirol ATO5) could be prepared without the use of surfactants. With the other waxes, increasing amounts of sodium lauryl sulphate in the external aqueous phase decreased the drug loading because of drug solubilization when compared to the polymeric stabilizer, poly(vinyl alcohol). The type of wax, the rate of cooling, and the temperature of the aqueous phase had no significant effect on the drug loading because of the low solubility of the drug in the external aqueous phase. The drug release was controlled by the hydrophobicity of the wax. Besides ibuprofen, other water-soluble drugs (ketoprofen, indomethacin, hydrocortisone) were also encapsulated by this method. The wax microparticles could be formulated into an aqueous sustained-release oral suspension dosage form.

  5. The Gibbs-Thomson effect and intergranular melting in ice emulsions: Interpreting the anomalous heat capacity and volume of supercooled water

    Science.gov (United States)

    Johari, G. P.

    1997-12-01

    Calculations for the Gibbs-Thomson effect and the intergranular melting of the ice droplets in (water) emulsions at temperatures below 273.16 K show that water and ice coexist at thermodynamic equilibrium in an apparently frozen emulsion. The fraction of water at this equilibrium increases on heating, which alters further the thermodynamic properties of the emulsion. As some of the ice in the emulsion has already melted, the increase in the enthalpy, H, and heat capacity, Cp, and the decrease in the volume measured on the normal melting at 273.16 K, are less than the values anticipated. The ratio of this increase in H, or Cp, on melting of the emulsion to the corresponding value for pure ice, underestimates the emulsion's water content which, when used for scaling the difference between the Cp of the unfrozen and frozen emulsion at lower temperatures, as in earlier studies, leads to a larger Cp of supercooled water than the actual value. Similar scaling of the corresponding difference between the volume leads to higher volume, or lower density, than the actual value. A formalism for this premelting effect is given for both the adiabatic and differential scanning calorimetry (DSC), and its magnitude is calculated. New experiments show that the rise in the DSC signal, or equivalently in the apparent Cp observed on heating the frozen emulsion, occurs over a temperature range much wider than the Gibbs-Thomson effect and intergranular melting predict, for which reasons are given. It is shown that Cp of the dispersant phase is also affected by the melting of ice droplets. There are four consequences of the premelting effects for all finely dispersed materials, for frozen water emulsions below 273.16 K: (i) water and ice coexist in the emulsion, (ii) its apparent Cp will increase with increase in the heat input used to measure it, (iii) the apparent Cp will increase with decrease in the average size of the droplets, and (iv) the apparent Cp will decrease on annealing the

  6. Ice-melt rates during volcanic eruptions within water-drained, low-pressure subglacial cavities

    Science.gov (United States)

    Woodcock, D. C.; Lane, S. J.; Gilbert, J. S.

    2016-02-01

    Subglacial volcanism generates proximal and distal hazards including large-scale flooding and increased levels of explosivity. Direct observation of subglacial volcanic processes is infeasible; therefore, we model heat transfer mechanisms during subglacial eruptions under conditions where cavities have become depressurized by connection to the atmosphere. We consider basaltic eruptions in a water-drained, low-pressure subglacial cavity, including the case when an eruption jet develops. Such drained cavities may develop on sloping terrain, where ice may be relatively shallow and where gravity drainage of meltwater will be promoted. We quantify, for the first time, the heat fluxes to the ice cavity surface that result from steam condensation during free convection at atmospheric pressure and from direct and indirect radiative heat transfer from an eruption jet. Our calculations indicate that the direct radiative heat flux from a lava fountain (a "dry" end-member eruption jet) to ice is c. 25 kW m-2 and is a minor component. The dominant heat transfer mechanism involves free convection of steam within the cavity; we estimate the resulting condensation heat flux to be c. 250 kW m-2. Absorption of radiation from a lava fountain by steam enhances convection, but the increase in condensing heat flux is modest at c. 25 kW m-2. Overall, heat fluxes to the ice cavity surface are likely to be no greater than c. 300 kW m-2. These are comparable with heat fluxes obtained by single phase convection of water in a subglacial cavity but much less than those obtained by two-phase convection.

  7. The great melting pot. Common sole population connectivity assessed by otolith and water fingerprints.

    Science.gov (United States)

    Morat, Fabien; Letourneur, Yves; Dierking, Jan; Pécheyran, Christophe; Bareille, Gilles; Blamart, Dominique; Harmelin-Vivien, Mireille

    2014-01-01

    Quantifying the scale and importance of individual dispersion between populations and life stages is a key challenge in marine ecology. The common sole (Solea solea), an important commercial flatfish in the North Sea, Atlantic Ocean and the Mediterranean Sea, has a marine pelagic larval stage, a benthic juvenile stage in coastal nurseries (lagoons, estuaries or shallow marine areas) and a benthic adult stage in deeper marine waters on the continental shelf. To date, the ecological connectivity among these life stages has been little assessed in the Mediterranean. Here, such an assessment is provided for the first time for the Gulf of Lions, NW Mediterranean, based on a dataset on otolith microchemistry and stable isotopic composition as indicators of the water masses inhabited by individual fish. Specifically, otolith Ba/Ca and Sr/Ca profiles, and δ(13)C and δ(18)O values of adults collected in four areas of the Gulf of Lions were compared with those of young-of-the-year collected in different coastal nurseries. Results showed that a high proportion of adults (>46%) were influenced by river inputs during their larval stage. Furthermore Sr/Ca ratios and the otolith length at one year of age revealed that most adults (∼70%) spent their juvenile stage in nurseries with high salinity, whereas the remainder used brackish environments. In total, data were consistent with the use of six nursery types, three with high salinity (marine areas and two types of highly saline lagoons) and three brackish (coastal areas near river mouths, and two types of brackish environments), all of which contributed to the replenishment of adult populations. These finding implicated panmixia in sole population in the Gulf of Lions and claimed for a habitat integrated management of fisheries.

  8. Comparing the impacts of mature spruce forests and grasslands on snow melt, water resource recharge, and run-off in the northern boreal environment

    Directory of Open Access Journals (Sweden)

    Jiří Kremsa

    2015-03-01

    Full Text Available Snow-melt runoff is an important factor in control of flooding and soil erosion in higher and cold regions of the world. In 1992–2008–2008, processes of snow accumulation and melting were monitored at two adjacent sites of the Paljakka environmental research centre (Finland. The forest stand of mature spruce (Picea abies has been compared with adjacent, local, and open grassland. In the forest, snowpack duration fluctuated for 180–245 days, with a maximum depth of 78–152 cm and snow–water content of 167–406 mm, while in the open grassland this occurred for some 20 days less, with maximum depth 65–122 cm, and snow–water content 143–288 mm. The snow–water captured in the canopy reached a maximum 27% of that registered on the ground; the loss of intercepted snow by sublimation was approximately 26% of the annual snowfall. During the high melt period (April–May, the degree-day factor in the forest stand achieved 60% of values observed in the grassland (2.3–3.5 against 3.8–6.0 mm °C−1 day−1. The hydrological model BROOK 90 was employed to analyse potential water resources recharge, and flood risk at Paljakka. Considering the normal climate season, snow-melt runoff from the forest exceeded the grassland by 22% (225 against 185 mm. In extreme situations, the maximum daily runoff from snow-melt in the grasslands (57 mm day−1 exceeded 2.6 times the values in spruce forest (22 mm day−1.

  9. Using ground penetrating radar to assess the variability of snow water equivalent and melt in a mixed canopy forest, Northern Colorado

    Science.gov (United States)

    Webb, Ryan W.

    2017-09-01

    Snow is an important environmental variable in headwater systems that controls hydrological processes such as streamflow, groundwater recharge, and evapotranspiration. These processes will be affected by both the amount of snow available for melt and the rate at which it melts. Snow water equivalent (SWE) and snowmelt are known to vary within complex subalpine terrain due to terrain and canopy influences. This study assesses this variability during the melt season using ground penetrating radar to survey multiple plots in northwestern Colorado near a snow telemetry (SNOTEL) station. The plots include south aspect and flat aspect slopes with open, coniferous (subalpine fir, Abies lasiocarpa and engelman spruce, Picea engelmanii), and deciduous (aspen, populous tremuooides) canopy cover. Results show the high variability for both SWE and loss of SWE during spring snowmelt in 2014. The coefficient of variation for SWE tended to increase with time during snowmelt whereas loss of SWE remained similar. Correlation lengths for SWE were between two and five meters with melt having correlation lengths between two and four meters. The SNOTEL station regularly measured higher SWE values relative to the survey plots but was able to reasonably capture the overall mean loss of SWE during melt. Ground Penetrating Radar methods can improve future investigations with the advantage of non-destructive sampling and the ability to estimate depth, density, and SWE.

  10. Nanofilled and/or toughened POM composites produced by water-mediated melt compounding: Structure and mechanical properties

    Directory of Open Access Journals (Sweden)

    2008-10-01

    Full Text Available Binary and ternary composites composed of polyoxymethylene (POM, polyurethane (PU and synthetic boehmite alumina (AlO(OH were produced by water-mediated melt compounding technique. PU latex and/or aqueous alumina suspension were injected into the molten POM in a twin-screw extruder to prepare toughened and/or reinforced polymer composites. The dispersion of the alumina and PU was studied by transmission- and scanning electron microcopy techniques (TEM and SEM, respectively, and discussed. The crystallization of the POM-based systems was inspected by polarized optical microscopy (PLM. The mechanical and thermomechanical properties of the composites were determined in dynamic-mechanical thermal analysis (DMTA, short-time creep tests (performed at various temperatures, uniaxial static tensile and notched Charpy impact tests. Incorporation of alumina increased the stiffness and resistance to creep and reduced the tensile strength, elongation at break and impact toughness. The change in the above parameters was opposite for the POM/PU binary blends. Additional incorporation of alumina in the POM/PU blend enhanced the resistance to creep, elongation at break and maintained the impact toughness compared to the POM/PU blend.

  11. Dissolution enhancement of poorly water-soluble APIs processed by hot-melt extrusion using hydrophilic polymers.

    Science.gov (United States)

    Maniruzzaman, M; Rana, M M; Boateng, J S; Mitchell, J C; Douroumis, D

    2013-02-01

    The aim of this study was to investigate the efficiency of hydrophilic polymers to enhance the dissolution rate of poorly water-soluble active pharmaceutical ingredients (APIs) processed by hot-melt extrusion (HME). Indomethacin (INM) and famotidine (FMT) were selected as model active substances while polyvinyl caprolactam graft copolymer, soluplus (SOL) and vinylpyrrolidone-vinyl acetate copolymer grades, Kollidon VA64 (VA64) and Plasdone S630 (S630) were used as hydrophilic polymeric carriers. For the purpose of the study, drug-polymer binary blends at various ratios were processed by a Randcastle single screw extruder. The physicochemical properties and the morphology of the extrudates were evaluated through X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Increased drug loadings of up to 40% were achieved in the extruded formulations for both drugs. INM and FMT exhibited strong plasticization effects with increasing concentrations and were found to be molecularly dispersed within the polymer blends. The in vitro dissolution studies showed increased INM/FMT release rates for all formulations compared to that of pure APIs alone.

  12. The Influence of Greenland melt water on the temporal and spatial response of the Holocene Thermal Maximum in the Nordic Seas: a modelling study

    Science.gov (United States)

    Blaschek, M.; Renssen, H.

    2012-04-01

    In the early-to-mid Holocene a period of relatively warm climate, known as the Holocene thermal maximum (HTM, 11-5 kyr BP), has been associated with the orbitally-forced northern hemisphere summer insolation maximum at approximately 10 kyr BP. Although the HTM is orbitally forced, the spatial and temporal response of its climate signature is diverse. At 9 kyr BP remnants of glacial ice sheets, most importantly the Laurentide Ice Sheet (LIS), modified the climate of the North Atlantic region by freshening the ocean surface through melt water discharge, and by altering the surface albedo and topography. A previous climate modelling study (Renssen et al. 2009) has shown that the LIS delayed the HTM in the Nordic Seas by up to 3000 years. We extend this approach by introducing another source of melt water in the early Holocene, the Greenland Ice Sheet (GIS). The GIS was likely up to 25% larger (at 9 kyr BP) in volume than at present-day (Vinther et al. 2009, Peltier, 2004) and is therefore potentially an important regional contributor to climate change in the Nordic Seas. We present here simulations performed with the LOVECLIM1.2 global ocean-atmosphere-vegetation model. These simulations seek to highlight the spatial and temporal impact of GIS melting on the early Holocene climate, in terms of sea surface temperature (SST). Several sensitivity experiments with fixed 9 kyr BP forcings were performed for different Greenland melt water fluxes to test model and climate sensitivity. These melt water fluxes range from 0 to 52 mSv. The sensitivity experiments show that GIS melting considerably influences sea surface conditions around the southern part of Greenland, and that 13 to 26 mSv of GIS melting, in a combination with the LIS background melting, agrees better in that region with proxy-based SST reconstructions. In a further step, transient simulations exhibit the long term (9 to 0 kyr BP) impact of GIS melting on the development of the Holocene climate. Transient

  13. Estimated Wind River Range (Wyoming, USA Glacier Melt Water Contributions to Agriculture

    Directory of Open Access Journals (Sweden)

    Larry Pochop

    2009-10-01

    Full Text Available In 2008, Wyoming was ranked 8th in barley production and 20th in hay production in the United States and these crops support Wyoming’s $800 million cattle industry. However, with a mean elevation of 2,040 meters, much of Wyoming has a limited crop growing season (as little as 60 days and relies on late-summer and early-fall streamflow for agricultural water supply. Wyoming is host to over 80 glaciers with the majority of these glaciers being located in the Wind River Range. These “frozen reservoirs” provide a stable source of streamflow (glacier meltwater during this critical late-summer and early-fall growing season. Given the potential impacts of climate change (increased temperatures resulting in glacier recession, the quantification of glacier meltwater during the late-summer and early-fall growing seasons is needed. Glacier area changes in the Wind River Range were estimated for 42 glaciers using Landsat data from 1985 to 2005. The total surface area of the 42 glaciers was calculated to be 41.2 ± 11.7 km2 in 1985 and 30.8 ± 8.2 km2 in 2005, an average decrease of 25% over the 21 year period. Small glaciers experienced noticeably more area reduction than large glaciers. Of the 42 glaciers analyzed, 17 had an area of greater than 0.5 km2 in 1985, while 25 were less than 0.5 km2 in 1985. The glaciers with a surface area less than 0.5 km2 experienced an average surface area loss (fraction of 1985 surface area of 43%, while the larger glaciers (greater than 0.5 km2 experienced an average surface area loss of 22%. Applying area-volume scaling relationships for glaciers, volume loss was estimated to be 409 × 106 m3 over the 21 year period, which results in an estimated 4% to 10% contribution to warm season (July–October streamflow.

  14. Ikaite crystals in melting sea ice - implications for pCO(2) and pH levels in Arctic surface waters

    DEFF Research Database (Denmark)

    Rysgaard, Søren; Glud, Ronnie N.; Lennert, K.

    2012-01-01

    that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km(2) (0.5-1m thick) drifting ice floe......, melt reduced the ice floe thickness by 0.2m per week and resulted in an estimated 3.8 ppm decrease of pCO(2) in the ocean surface mixed layer. This corresponds to an air-sea CO2 uptake of 10.6 mmol m(-2) sea ice d(-1) or to 3.3 ton km(-2) ice floe week(-1). This is markedly higher than the estimated...... primary production within the ice floe of 0.3-1.3 mmol m(-2) sea ice d(-1). Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated pCO(2) uptake...

  15. Ikaite crystals in melting sea ice – implications for pCO2 and pH levels in Arctic surface waters

    DEFF Research Database (Denmark)

    Rysgaard, Søren; Glud, R.N.; Lennert, K.

    2012-01-01

    chemical transformations occur in sea ice with a possible effect on CO 2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km 2 (0.5-1 m thick) drifting ice floe in the Fram Strait...... during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced...... within the ice floe of 0.3-1.3 mmol m -2 sea ice d -1. Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated pCO 2 uptake. © Author(s) 2012....

  16. Consequences of material effects on in-vessel retention

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, Jean Marie [CEA Grenoble, DTN/SE2T/LPTM, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Tourniaire, Bruno [CEA Grenoble, DTN/SE2T/LPTM, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)]. E-mail: bruno.tourniaire@cea.fr; Defoort, Francoise [CEA Grenoble, DTN/SE2T/LPTM, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Froment, Karine [CEA Grenoble, DTN/SE2T/LPTM, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2007-09-15

    In-vessel retention (IVR) consists in cooling the corium contained in the reactor vessel by natural convection and reactor cavity flooding. This strategy of severe accident management enables the corium to be kept inside the second confinement barrier: the reactor vessel. The general approach which is used to study IVR problems is a 'bounding' approach which consists in assuming a specified corium stratification in the vessel and then demonstrating that the vessel can cope with the resulting thermal and mechanical loads. Thermal loading on the vessel is controlled by the convective heat transfer inside the molten corium in the lower head. If there is no water in the vessel and if the corium pool is overlaid by a liquid steel layer, then the heat flux might focus on the vessel in front of the steel layer ('focusing effect') and exceed the dry-out heat flux (CHF or DHF). One of the critical points of these studies is linked to the determination of the height of the molten steel layer that can stratify above the oxidic pool. The MASCA experiments have highlighted that part of molten steel may stratify under the oxidic corium which reduces the thickness of the steel layer on top of the pool. This behavior can be explained by chemical interaction between the oxide and metallic phases of the pool which confirms that these materials cannot be treated as inert species. Following these conclusions, a methodology which couples physicochemical effects and thermalhydraulics has been developed to address the IVR issue. The main purpose of this paper is to present this methodology and its application for given corium mass inventories. Attention focuses on the influence of parameters such as the ratio U/Zr and oxidation ratio of zirconia. For a 1000 MW PWR, approximately 10 t of steel stratify at the bottom of the vessel for 40% Zr oxidation, and 25 t for 30% Zr oxidation. This leads to a 25-50% increase of the mass of molten steel that is required for

  17. Melting Heat Transfer Characteristics of Latent Heat Microcapsule-Water Mixed Slurry Flowing in a Pipe with Constant Wall Heat Flux (Experimental Study)

    Science.gov (United States)

    Inaba, Hideo; Kim, Myoung-Jun; Horibe, Akihiko

    The present experiments have been performed for obtaining the melting heat transfer characteristics of micro-encapsulated solid-liquid phase change material and water mixed slurry flow in a circular tube heated with constant wall heat flux. The phase change material having a low melting point was selected for a domestic cooling system in the present study. The governing parameters were found to be latent heat material concentration,heat,flux,and the slurry velocity. The experimental results revealed that the mean heat transfer coefficient of latent microcapsule slurry was about l.3~l.8 times greater than that of the single phase of water. Moreover the effectiveness of heat transfer coefficient to friction factor had a maximum at latent heat material concentration of 25%.

  18. Stearic acid and high molecular weight PEO as matrix for the highly water soluble metoprolol tartrate in continuous twin-screw melt granulation

    OpenAIRE

    Monteyne, Tinne; Adriaensens, Peter; Brouckaert, Davinia; Remon, Jean-Paul; Vervaet, Chris; De Beer, Thomas

    2016-01-01

    Granules with release-sustaining properties were developed by twin screw hot melt granulation (HMG) using a combination of stearic acid (SA) and high molecular weight polyethylene oxide (PEO) as matrix for a highly water soluble model drug, metoprolol tartrate (MPT). Earlier studies demonstrated that mixing molten SA and PEO resulted in hydrogen bond formation between hydroxyl groups of fatty acid molecules and ether groups in PEO chains. These molecular interactions might be beneficial in or...

  19. Effects of water-saturation on strength and ductility of three igneous rocks at effective pressures to 50 MPA and temperatures to partial melting

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, S.J.; Friedman, M.; Handin, J.

    1981-01-01

    The short-term failure strengths and strains at failure of room-dry and water-saturated, cylindrical specimens (2 by 4 cm) of Charcoal Granodiorite (CG), Mt. Hood Andesite (MHA), and Cuerbio Basalt (CB) at a strain rate of 10/sup -4/s/sup -1/, at effective confining pressures of 0, 50, and 100 MPa and at temperatures to partial melting were investigated. Data from water-saturated specimens of the granodiorite and andesite, compared to room-dry counterparts, indicate (1) the pore pressures are essentially communicated throughout each test specimen so that they are fully effective; (2) at P/sub e/ = 0 and 50 MPa the granodiorite does not water-weaken; (3) at these same effective pressures the more porous and finer-grained andesite begins to exhibit water-weakening at about 600/sup 0/C; (4) at P/sub e/ = 0 and 870 to 900/sup 0/C the andesite's strength averages 20 MPa while the strength of dry specimens at the same P and T exhibit a strength of 100 MPa; (5) at P/sub e/ = 50 MPa compared to 160 MPa dry; (6) the basalt at P/sub e/ = 0, appears to be water-weakened at 800/sup 0/C; (7) water saturated specimens deformed at temperatures less than that of melting exhibit ultimate strengths at less than 2% shortening and then work-soften along faults; (8) again as do the dry counterparts, the wet specimens deform primarily by microscopic fracturing that coalesces into one or more macroscopic faults; and (9) the temperature for incipient melting of the andesite is decreased >150/sup 0/C in the water-saturated tests.

  20. 融雪剂对地表水及地下水的影响%The Influence of Snow-melting Agent on Surface Water and Groundwater

    Institute of Scientific and Technical Information of China (English)

    蔡雯璐

    2011-01-01

    The changes of aquatic environment after using snow-melting agent on highway are studied by detecting the relevant indexes of surface water and groundwater samples.The result shows that: the using of snow-melting agent increases the content of chlorine ion and other relevant metal salt ions in surface water and groundwater,among which surface water is influenced more seriously by snow-melting agent and the highest increasing rate of chloride content is 56.77%.%通过对地表水和地下水样品相关指标进行检测,对公路在使用融雪剂后水体环境的变化情况进行研究。结果表明:融雪剂的使用提高了地表水和地下水中的氯离子和其它相关金属盐离子的含量。其中地表水受融雪剂影响较大,氯化物含量增加率最高为56.77%。

  1. Application of carrier and plasticizer to improve the dissolution and bioavailability of poorly water-soluble baicalein by hot melt extrusion.

    Science.gov (United States)

    Zhang, Yilan; Luo, Rui; Chen, Yi; Ke, Xue; Hu, Danrong; Han, Miaomiao

    2014-06-01

    The objective of this study was to develop a suitable formulation for baicalein (a poorly water-soluble drug exhibiting high melting point) to prepare solid dispersions using hot melt extrusion (HME). Proper carriers and plasticizers were selected by calculating the Hansen solubility parameters, evaluating melting processing condition, and measuring the solubility of obtained melts. The characteristic of solid dispersions prepared by HME was evaluated. The dissolution performance of the extrudates was compared to the pure drug and the physical mixtures. Physicochemical properties of the extrudates were characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR). Relative bioavailability after oral administration in beagle dogs was assessed. As a result, Kollidon VA64 and Eudragit EPO were selected as two carriers; Cremophor RH was used as the plasticizer. The dissolution of all the extrudates was significantly improved. DSC and PXRD results suggested that baicalein in the extrudates was amorphous. FTIR spectroscopy revealed the interaction between drug and polymers. After oral administration, the relative bioavailability of solid dispersions with VA64 and EPO was comparative, about 2.4- and 2.9-fold greater compared to the pure drug, respectively.

  2. Basal terraces on melting ice shelves

    National Research Council Canada - National Science Library

    Dutrieux, Pierre; Stewart, Craig; Jenkins, Adrian; Nicholls, Keith W; Corr, Hugh F. J; Rignot, Eric; Steffen, Konrad

    2014-01-01

    Ocean waters melt the margins of Antarctic and Greenland glaciers, and individual glaciers' responses and the integrity of their ice shelves are expected to depend on the spatial distribution of melt...

  3. Rapid and specific detection of Salmonella in water samples using real-time PCR and High Resolution Melt (HRM) curve analysis.

    Science.gov (United States)

    van Blerk, G N; Leibach, L; Mabunda, A; Chapman, A; Louw, D

    2011-01-01

    A real-time PCR assay combined with a pre-enrichment step for the specific and rapid detection of Salmonella in water samples is described. Following amplification of the invA gene target, High Resolution Melt (HRM) curve analysis was used to discriminate between products formed and to positively identify invA amplification. The real-time PCR assay was evaluated for specificity and sensitivity. The assay displayed 100% specificity for Salmonella and combined with a 16-18 h non-selective pre-enrichment step, the assay proved to be highly sensitive with a detection limit of 1.0 CFU/ml for surface water samples. The detection assay also demonstrated a high intra-run and inter-run repeatability with very little variation in invA amplicon melting temperature. When applied to water samples received routinely by the laboratory, the assay showed the presence of Salmonella in particularly surface water and treated effluent samples. Using the HRM based assay, the time required for Salmonella detection was drastically shortened to less than 24 h compared to several days when using standard culturing methods. This assay provides a useful tool for routine water quality monitoring as well as for quick screening during disease outbreaks.

  4. An Experimental Investigation of Ice Melting and Heat Transfer Characteristics from Submerged Jets of Hot Water, Implications for Subglacial Volcanic Eruptions

    Science.gov (United States)

    Jamshidnia, H.; Gudmundsson, M. T.

    2014-12-01

    The rates and processes of energy transfer in water-filled cavities formed under glaciers by geothermal and volcanic activity has been investigated by designing, developing, and using an experimental setup in which hot water jets can impinge on an ice block. Systematic sets of experimental runs typically lasting 60-90 seconds with water jet temperatures in the range 10° - 90°C have been performed with initial ice block temparature. It is quantitatively found that heat flux from flowing water to ice is linearly dependent on temperature of the jet flow. The hot water jet meltes out a cavity into the ice block during the process. The cavities had steep to vertical sides with a doming roof. Some of the ice blocks used had trapped air bubbles. In these cases melting of the ice lead to the trapping of air at the top of the cavity, partially insulating the roof from the hot water jet. Such cavities had lower aspect ratios (height/width) and flatter and less dome shaped roofs than did cavities in ice blocks with little or no air bubbles. The overall heat transfer rate in cavity formation varied with jet temperature from water in cool, subglacial water bodies and above subglacial flowpaths of jökulhlaups. However, the highest experimental rates for 80-90°C jets are 3-10 times less than inferred from observations of recent subglacial eruptions (2000-4000 kW m-2). This can indicate that single phase liquid water convection alone is not sufficient to explain the rates seen in recent subglacial eruptions in Iceland, suggesting that during such eruptions forced two-phase (liquid and steam) or three phase (liquid, steam and pyroclasts) convection is common. Further recommendations may also be presented for future research in this field.

  5. Ikaite crystals in melting sea ice – implications for pCO2 and pH levels in Arctic surface waters

    Directory of Open Access Journals (Sweden)

    R. J. G. Leakey

    2012-08-01

    Full Text Available A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air–sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO3·6H2O in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km2 (0.5–1 m thick drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice floe thickness by 0.2 m per week and resulted in an estimated 3.8 ppm decrease of pCO2 in the ocean surface mixed layer. This corresponds to an air–sea CO2 uptake of 10.6 mmol m−2 sea ice d−1 or to 3.3 ton km−2 ice floe week−1. This is markedly higher than the estimated primary production within the ice floe of 0.3–1.3 mmol m−2 sea ice d−1. Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated pCO2 uptake.

  6. An Experimental Investigation of Ice-melting and heat transfer rates from submerged warm water jets upward impinging into ice-blocks as analogous for water-filled cavities formed during subglacial eruptions.

    Science.gov (United States)

    Jamshidnia, Hamidreza; Gudmundsson, Magnus Tumi

    2016-11-01

    Rates of energy transfer in water-filled cavities formed under glaciers by geothermal and volcanic activity are investigated by conducting experiments in which hot water jets (10°- 90°C) impinging into an ice block for jet Reynolds numbers in turbulent regime of 10000 -70000. It is found that heat flux is linearly dependent on jet flow temperature. Water jet melts a cavity into an ice block. Cavities had steep to vertical sides with a doming roof. Some of ice blocks used had trapped air bubbles. In these cases that melting of the ice could have led to trapping of air at the top of cavity, partially insulating the roof from hot water jet. The overall heat transfer rate in cavity formation varied with jet temperature from <100 kW m-2 to 900 kW m-2 while melting rates in the vertical direction yield heat transfer rates of 200-1200 kW m-2. Experimental heat transfer rates can be compared to data on subglacial melting observed for ice cauldrons in Iceland. For lowest temperatures the numbers are comparable to those for geothermal water in cool, subglacial water bodies and above subglacial flowpaths of jökulhlaups. Highest experimental rates for 80-90°C jets are 3-10 times less than inferred from observations of recent subglacial eruptions (2000-4000 kW m-2) . This can indicate that single phase liquid water convection alone may not be sufficient to explain the rates seen in recent subglacial eruptions, suggesting that forced 2 or 3 phase convection can be common.

  7. Application of Carrier and Plasticizer to Improve the Dissolution and Bioavailability of Poorly Water-Soluble Baicalein by Hot Melt Extrusion

    National Research Council Canada - National Science Library

    Zhang, Yilan; Luo, Rui; Chen, Yi; Ke, Xue; Hu, Danrong; Han, Miaomiao

    2014-01-01

    ...) to prepare solid dispersions using hot melt extrusion (HME). Proper carriers and plasticizers were selected by calculating the Hansen solubility parameters, evaluating melting processing condition, and measuring the solubility of obtained melts...

  8. Design and implementation of visual inspection system handed in tokamak flexible in-vessel robot

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hesheng; Xu, Lifei [Department of Automation, Shanghai Jiao Tong University, Shanghai 200240 (China); Key Laboratory of System Control and Information Processing, Ministry of Education of China (China); Chen, Weidong, E-mail: wdchen@sjtu.edu.cn [Department of Automation, Shanghai Jiao Tong University, Shanghai 200240 (China); Key Laboratory of System Control and Information Processing, Ministry of Education of China (China)

    2016-05-15

    In-vessel viewing system (IVVS) is a fundamental tool among the remote handling systems for ITER, which is used to providing information on the status of the in-vessel components. The basic functional requirement of in-vessel visual inspection system is to perform a fast intervention with adequate optical resolution. In this paper, we present the software and hardware solution, which is designed and implemented for tokamak in-vessel viewing system that installed on end-effector of flexible in-vessel robot working under vacuum and high temperature. The characteristic of our in-vessel viewing system consists of two parts: binocular heterogeneous vision inspection tool and first wall scene emersion based augment virtuality. The former protected with water-cooled shield is designed to satisfy the basic functional requirement of visual inspection system, which has the capacity of large field of view and high-resolution for detection precision. The latter, achieved by overlaying first wall tiles images onto virtual first wall scene model in 3D virtual reality simulation system, is designed for convenient, intuitive and realistic-looking visual inspection instead of viewing the status of first wall only by real-time monitoring or off-line images sequences. We present the modular division of system, each of them in smaller detail, and go through some of the design choices according to requirements of in-vessel visual inspection task.

  9. MELTED BUTTER TECHNOLOGY DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    L. V. Golubeva

    2014-01-01

    Full Text Available Summary. Melted butter is made from dairy butter by rendering the fat phase. It has specific taste and aroma, high-calorie content and good assimilability. Defects of butter which appeared during the storage causes by the development of microbiological processes or by the chemical oxidation. On the development of these processes influence quality and composition of fresh butter, its physical structure, content of the increased amount of gas phase and content of heavy metals, storage conditions. Microbiological spoilage of butter occurs generally due to damage of plasma which is good environment for the development of microorganisms. Defects of microbiological origin include: unclean, sour, moldy, yeasty, cheesy, bitter taste. Defects of test and smell chemical origin are formed due to hydrolytic digestion of lipids. It's prevailed at long storage of butter in the conditions of freezing temperatures. It's picked out the following main processes of spoiling: souring, acidifying and sallowness. Often these processes take place simultaneously.It has been investigated melted butter with lactated additive. The latter improves the microbiological and toxicological safety, prolongs the storage condition of the products. Technological efficiency of the additives is achieved by a multilayer products formation from the inactive bound water, preventing microorganisms growth and by the barrier layer with lactate inhibiting hydrolytic reactions. Oil samples were obtained with the batch-type butter maker application, then they were melted and after that lactated additive were supplemented. It has been studied organoleptic and physico-chemical indices of the melted butter samples. The fatty-acid composition of melted butter were studied. Comparative analysis of fatty-acid composition of cow's milk fat and produced melted butter has shown their similarity. Also in the last sample there is increased weight fraction of linoleic and linolenic acids. The obtained

  10. Sources of water for the outflow channels on Mars: Implications of the Late Noachian "icy highlands" model for melting and groundwater recharge on the Tharsis rise

    Science.gov (United States)

    Cassanelli, James P.; Head, James W.; Fastook, James L.

    2015-04-01

    predicted "cold and icy" conditions is required. We test basal melting of surface snow and ice in response to a regionally elevated geothermal heat flux throughout the Tharsis rise (resulting from widespread volcanic and magmatic activity during the Noachian) as a mechanism that can provide: (1) liquid water generation at the surface of Mars under generally "cold and icy" conditions, and (2) potentially large scale integration of the hydrological system (through thinning or breaching of the cryosphere), allowing for infiltration of meltwater to provide groundwater recharge during the Late Noachian to supply the later formation of outflow channels. We find: (1) Regional scale basal melting of LNIH ice sheets is not likely to occur at the predicted nominal average ice sheet thicknesses, even in the presence of the anomalous bottom-up heating conditions expected in the Tharsis region (although the increased baseline heating will render the LNIH ice sheets more susceptible to melting through additional anomalous heating conditions introduced by top-down and bottom-up processes). (2) Local scale basal melting and groundwater recharge through a "heat-pipe drain pipe" mechanism is likely to occur, but is not predicted to produce sufficient groundwater recharge to supply the water needed to form the outflow channels. (3) Under the assumption of an ice saturated cryosphere, regional scale melting of the cryosphere due to the insulating effect of the LNIH ice sheets does not provide enough water to explain the formation of all of the outflow channels. Therefore, if the LNIH model is correct, the groundwater recharge that supplied outflow channel formation requires a source that operated earlier in martian history, or the recharge was supplied by other mechanisms.

  11. Decrease in water activity due to fluid absent partial melting monitored with water content in biotite in the Western Adamello contact aureole (Italy)

    Science.gov (United States)

    Siron, Guillaume; Baumgartner, Lukas; Bouvier, Anne-Sophie; Vennemann, Torsten

    2016-04-01

    interpret the concentration of OH- to be influenced by water activity within the rocks, and temperature. Our results confirm that oxy-biotite is a non-negligible component, but in the case of prograde metamorphism we do not interpret this as the consequence of a Ti-oxygen exchange only, but also as the consequence of a decrease in water activity due to partial melting. Bauer, K. K., & Vennemann, T. W. (2014). Analytical methods for the measurement of hydrogen isotope composition and water content in clay minerals by TC/EA. Chemical Geology, 363(C), 229-240. Cesare, B., Satish-Kumar, M., Cruciani, G., Pocker, S., & Nodari, L. (2008). Mineral chemistry of Ti-rich biotite from pegmatite and metapelitic granulites of the Kerala Khondalite Belt (southeast India): Petrology and further insight into titanium substitutions. American Mineralogist, 93(2-3), 327-338. Floess, D., & Baumgartner, L. (2013). Formation of garnet clusters during polyphase metamorphism. Terra Nova, 25(2), 144-150. Munoz, J. L. (1984). F-OH and Cl-OH Exchange in Micas with Applications to Hydrothermal Ore Deposits. Reviews in Mineralogy and Geochemistry, 13, 469-493.

  12. Stearic acid and high molecular weight PEO as matrix for the highly water soluble metoprolol tartrate in continuous twin-screw melt granulation.

    Science.gov (United States)

    Monteyne, Tinne; Adriaensens, Peter; Brouckaert, Davinia; Remon, Jean-Paul; Vervaet, Chris; De Beer, Thomas

    2016-10-15

    Granules with release-sustaining properties were developed by twin screw hot melt granulation (HMG) using a combination of stearic acid (SA) and high molecular weight polyethylene oxide (PEO) as matrix for a highly water soluble model drug, metoprolol tartrate (MPT). Earlier studies demonstrated that mixing molten SA and PEO resulted in hydrogen bond formation between hydroxyl groups of fatty acid molecules and ether groups in PEO chains. These molecular interactions might be beneficial in order to elevate the sustained release effect of drugs from a SA/PEO matrix. This study aims to investigate the continuous twin screw melt granulation technique to study the impact of a SA/PEO matrix on the dissolution rate of a highly water soluble drug (MPT). Decreasing the SA/PEO ratio improved the release-sustaining properties of the matrix. The solid state of the granules was characterized using differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) and near infrared chemical imaging (NIR-CI) in order to understand the dissolution behavior. The results revealed a preferential interaction of the MPT molecules with stearic acid impeding the PEO to form hydrogen bonds with the stearic acid chains. However, this allowed the PEO chains to recrystallize inside the stearic acid matrix after granulation, hence, elevating the release-sustaining characteristics of the formulation.

  13. Volatile diffusion in silicate melts and its effects on melt inclusions

    Directory of Open Access Journals (Sweden)

    P. Scarlato

    2005-06-01

    Full Text Available A compendium of diffusion measurements and their Arrhenius equations for water, carbon dioxide, sulfur, fluorine, and chlorine in silicate melts similar in composition to natural igneous rocks is presented. Water diffusion in silicic melts is well studied and understood, however little data exists for melts of intermediate to basic compositions. The data demonstrate that both the water concentration and the anhydrous melt composition affect the diffusion coefficient of water. Carbon dioxide diffusion appears only weakly dependent, at most, on the volatilefree melt composition and no effect of carbon dioxide concentration has been observed, although few experiments have been performed. Based upon one study, the addition of water to rhyolitic melts increases carbon dioxide diffusion by orders of magnitude to values similar to that of 6 wt% water. Sulfur diffusion in intermediate to silicic melts depends upon the anhydrous melt composition and the water concentration. In water-bearing silicic melts sulfur diffuses 2 to 3 orders of magnitude slower than water. Chlorine diffusion is affected by both water concentration and anhydrous melt composition; its values are typically between those of water and sulfur. Information on fluorine diffusion is rare, but the volatile-free melt composition exerts a strong control on its diffusion. At the present time the diffusion of water, carbon dioxide, sulfur and chlorine can be estimated in silicic melts at magmatic temperatures. The diffusion of water and carbon dioxide in basic to intermediate melts is only known at a limited set of temperatures and compositions. The diffusion data for rhyolitic melts at 800°C together with a standard model for the enrichment of incompatible elements in front of growing crystals demonstrate that rapid crystal growth, greater than 10-10 ms-1, can significantly increase the volatile concentrations at the crystal-melt interface and that any of that melt trapped

  14. Ikaite crystals in melting sea ice - implications for pCO(2) and pH levels in Arctic surface waters

    DEFF Research Database (Denmark)

    Rysgaard, Søren; Glud, Ronnie N.; Lennert, K.

    2012-01-01

    A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO3 center dot 6H(2)O) in Arctic and Antarctic sea ice, which indicate...... that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km(2) (0.5-1m thick) drifting ice floe......, melt reduced the ice floe thickness by 0.2m per week and resulted in an estimated 3.8 ppm decrease of pCO(2) in the ocean surface mixed layer. This corresponds to an air-sea CO2 uptake of 10.6 mmol m(-2) sea ice d(-1) or to 3.3 ton km(-2) ice floe week(-1). This is markedly higher than the estimated...

  15. Ikaite crystals in melting sea ice – implications for pCO2 and pH levels in Arctic surface waters

    DEFF Research Database (Denmark)

    Rysgaard, Søren; Glud, R.N.; Lennert, K.

    2012-01-01

    A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO 2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO 3•6H 2O) in Arctic and Antarctic sea ice, which indicate that multiple...... chemical transformations occur in sea ice with a possible effect on CO 2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km 2 (0.5-1 m thick) drifting ice floe in the Fram Strait...... during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced...

  16. Ikaite crystals in melting sea ice – implications for pCO2 and pH levels in Arctic surface waters

    Directory of Open Access Journals (Sweden)

    R. J. G. Leakey

    2012-03-01

    Full Text Available A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (CaCO3·6H2O in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from an actively melting 1.7 km2 (0.5–1 m thick drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures gradually disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice flow thickness by ca. 0.2 m per week and resulted in an estimated 1.6 ppm decrease of pCO2 in the ocean surface mixed layer. This corresponds to an air-sea CO2 uptake of 11 mmol m−2 sea ice d−1 or to 3.5 ton km−2 ice floe week−1.

  17. Effect of the in- and ex-vessel dual cooling on the retention of an internally heated melt pool in a hemispherical vessel

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, K.I.; Kim, B.S.; Kim, D.H. [Korea Atomic Energy Research Inst., Thermal Hydraulic Safety Research, Taejon (Korea, Republic of)

    2001-07-01

    A concept of in-vessel melt retention (IVMR) by in-vessel reflooding and/or reactor cavity flooding has been considered as one of severe accident management strategies and intensive researches to be performed worldwide. This paper provides some results of analytical investigations on the effect of both in- / ex-vessel cooling on the retention of an internally heated molten pool confined in a hemispherical vessel and the related thermal behavior of the vessel wall. For the present analysis, a scale-down reactor vessel for the KSNP reactor design of 1000 MWe (a large dry PWR) is utilized for a reactor vessel. Aluminum oxide melt simulant is also utilized for a real corium pool. An internal power density in the molten pool is determined by a simple scaling analysis that equates the heat flux on the the scale-down vessel wall to that estimated from KSNP. Well-known temperature-dependent boiling heat transfer curves are applied to the in- and ex-vessel cooling boundaries and radiative heat transfer has been only considered in the case of dry in-vessel. MELTPOOL, which is a computational fluid dynamics (CFD) code developed at KAERI, is applied to obtain the time-varying heat flux distribution from a molten pool and the vessel wall temperature distributions with angular positions along the vessel wall. In order to gain further insights on the effectiveness of in- and ex-vessel dual cooling on the in-vessel corium retention, four different boundary conditions has been considered: no water inside the vessel without ex-vessel cooling, water inside the vessel without ex-vessel cooling, no water inside the vessel with ex-vessel cooling, and water inside the vessel with ex-vessel cooling. (authors)

  18. ITER in-vessel system design and performance

    Science.gov (United States)

    Parker, R. R.

    2000-03-01

    The article reviews the design and performance of the in-vessel components of ITER as developed for the Engineering Design Activities (EDA) Final Design Report. The double walled vacuum vessel is the first confinement boundary and is designed to maintain its integrity under all normal and off-normal conditions, e.g. the most intense vertical displacement events (VDEs) and seismic events. The shielding blanket consists of modules connected to a toroidal backplate by flexible connectors which allow differential displacements due to temperature non-uniformities. Breeding blanket modules replace the shield modules for the Enhanced Performance Phase. The divertor concept is based on a cassette structure which is convenient for remote installation and removal. High heat flux (HHF) components are mechanically attached and can be removed and replaced in the hot cell. Operation of the divertor is based on achieving partially detached plasma conditions along and near the separatrix. Nominal heat loads of 5-10 MW/m2 are expected on the target. These are accommodated by HHF technology developed during the EDA. Disruptions and VDEs can lead to melting of the first wall armour but no damage to the underlying structure. Stresses in the main structural components remain within allowable ranges for all postulated disruption and seismic events.

  19. Pavement Snow Melting

    Energy Technology Data Exchange (ETDEWEB)

    Lund, John W.

    2005-01-01

    The design of pavement snow melting systems is presented based on criteria established by ASHRAE. The heating requirements depends on rate of snow fall, air temperature, relative humidity and wind velocity. Piping materials are either metal or plastic, however, due to corrosion problems, cross-linked polyethylene pipe is now generally used instead of iron. Geothermal energy is supplied to systems through the use of heat pipes, directly from circulating pipes, through a heat exchanger or by allowing water to flow directly over the pavement, by using solar thermal storage. Examples of systems in New Jersey, Wyoming, Virginia, Japan, Argentina, Switzerland and Oregon are presented. Key words: pavement snow melting, geothermal heating, heat pipes, solar storage, Wyoming, Virginia, Japan, Argentina, Klamath Falls.

  20. Potential for AP600 in-vessel retention through ex-vessel flooding

    Energy Technology Data Exchange (ETDEWEB)

    Rempe, J.L.; Knudson, D.L.; Allison, C.M.; Thinnes, G.L.; Atwood, C.L.

    1997-12-01

    External reactor vessel cooling (ERVC) is a new severe accident management strategy that involves flooding the reactor cavity to submerge the reactor vessel in an attempt to cool core debris that has relocated to the vessel lower head. Advanced and existing light water reactors (LWRs) are considering ERVC as an accident management strategy for in-vessel retention (IVR) of relocated debris. In the probabilistic risk assessment (PRA) for the AP600 design, Westinghouse credits ERVC for preventing vessel failure during postulated severe accidents with successful reactor coolant system (RCS) depressurization and reactor cavity flooding. To support the Westinghouse position on IVR, DOE contracted the University of California--Santa Barbara (UCSB) to produce the peer-reviewed report. To assist in the NRC`s evaluation of IVR of core melt by ex-vessel flooding of the AP6OO, the Idaho National Engineering and Environmental Laboratory (INEEL) was tasked to perform: An in-depth critical review of the UCSB study and the model that UCSB used to assess ERVC effectiveness; An in-depth review of the UCSB study peer review comments and of UCSB`s resolution method to identify areas where technical concerns weren`t addressed; and An independent analysis effort to investigate the impact of residual concerns on the margins to failure and conclusions presented in the UCSB study. This report summarizes results from these tasks. As discussed in Sections 1.1 and 1.2, INEEL`s review of the UCSB study and peer reviewer comments suggested that additional analysis was needed to assess: (1) the integral impact of peer reviewer-suggested changes to input assumptions and uncertainties and (2) the challenge present by other credible debris configurations. Section 1.3 summarized the corresponding analysis approach developed by INEEL. The remainder of this report provides more detailed descriptions of analysis methodology, input assumptions, and results.

  1. Properties of water-soluble and insoluble particulate matter emitted from dewatered sewage sludge incineration in a pilot-scale ash melting furnace

    Energy Technology Data Exchange (ETDEWEB)

    Lian Zhang; Megumi Masui; Hiroharu Mizukoshi; Yoshihiko Ninomiya; Jugo Koketsu; Chikao Kanaoka [Chubu University, Aichi (Japan). Department of Applied Chemistry

    2008-05-15

    Emission of inorganic particulate matter (PM) from the incineration of dewatered sewage sludge has been investigated in a novel ash melting furnace. The sludge containing 79 wt% water was incinerated in an oxygen-enriched atmosphere at the primary temperature of 1400{sup o}C, and its unburned volatile was combusted at 1100{sup o}C in a secondary combustion chamber. A 13-stage low-pressure-impactor and the conventional impinger methods were employed for PM sampling at the outlet of the secondary combustion chamber. The results indicate that, PM is dominated by volatile and semi-volatile elements including Br, Cl, P, S, Na, K, Zn, As, Cu, Mn and Ni. Less refractory elements were found. PM has two major fractions: {lt}0.22 and {ge}0.22 {mu}m. Their chemical forms as well as water solubility are different between two fractions. The majority of Br, nearly half of Cl, and 40% of S and P are present in the small fraction. They are mostly water-soluble due to the association with alkali elements and heavy metals. The water-insoluble calcium sulfate and calcium/iron phosphate were, however, found in the large fraction of PM. Regarding the cations, the water solubilities of Na, K, Mn and Ni are close to their proportions partitioned into the small fraction of PM, since their water-soluble species were preferentially formed in this fraction. A relatively weak correlation for Al, Ca and As, while no such a correlation were found for Cu, Zn and Fe, due to the complex compounds formed for them. 31 refs., 11 figs., 5 tabs.

  2. Snow Melting and Freezing on Older Townhouses

    DEFF Research Database (Denmark)

    Nielsen, Anker; Claesson, Johan

    2011-01-01

    The snowy winter of 2009/2010 in Scandinavia prompted many newspaper articles on icicles falling from buildings and the risk this presented for people walking below. The problem starts with snow melting on the roof due to heat loss from the building. Melt water runs down the roof and some...... of it will freeze on the overhang. The rest of the water will either run off or freeze in gutters and downpipes or turn into icicles. This paper describes use of a model for the melting and freezing of snow on roofs. Important parameters are roof length, overhang length, heat resistance of roof and overhang......, outdoor and indoor temperature, snow thickness and thermal conductivity. If the snow thickness is above a specific limit value – the snow melting limit- some of the snow will melt. Another interesting limit value is the dripping limit. All the melt water will freeze on the overhang, if the snow thickness...

  3. Diazotroph diversity in the sea ice, melt ponds and surface waters of the Eurasian Basin of the Central Arctic Ocean

    OpenAIRE

    Fernández-Méndez, Mar; Turk-Kubo, Kendra A.; Rapp, Josephine Z.; Buttigieg, Pier Luigi; Krumpen, Thomas; Jonathan P Zehr; Boetius, Antje

    2016-01-01

    The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which ...

  4. Studies on in-vessel debris coolability in ALPHA program

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, Yu; Yamano, Norihiro; Moriyama, Kiyofumi [Japan Atomic Energy Research Institute, Ibaraki-ken (Japan)] [and others

    1997-02-01

    In-vessel debris coolability experiments have been performed in ALPHA Program at JAERI. Aluminum oxide (Al{sub 2}O{sub 3}) produced by a thermite reaction was applied as a debris simulant. Two scoping experiments using approximately 30 kg or 50 kg of Al{sub 2}O{sub 3} were conducted. In addition to post-test observations, temperature histories of the debris simulant and the lower head experimental vessel were evaluated. Rapid temperature reduction observed on the outer surface of the experimental vessel may imply that water penetration into a gap between the solidified debris and the experimental vessel occurred resulting in an effective cooling of once heated vessel wall. Preliminary measurement of a gap width was made with an ultrasonic device. Signals to show the existence of gaps, ranging from 0.7 mm to 1.4 mm, were detected at several locations.

  5. Melt and collapse of buried water ice: An alternative hypothesis for the formation of chaotic terrains on Mars

    NARCIS (Netherlands)

    Zegers, T.E.; Oosthoek, J.H.P.; Rossi, A.P.; Blom, J.K.; Schumacher, S.

    2010-01-01

    Chaotic terrains and the associated massive outflow channels are some of the most enigmatic features on Mars. Over hundreds of kilometres of rock units are fractured, tilted, and have subsided, forming chaotic terrain basins (Sharp, 1973). Large quantities of water emanated from these chaotic terrai

  6. The ITER in-vessel system

    Energy Technology Data Exchange (ETDEWEB)

    Lousteau, D.C.

    1994-09-01

    The overall programmatic objective, as defined in the ITER Engineering Design Activities (EDA) Agreement, is to demonstrate the scientific and technological feasibility of fusion energy for peaceful purposes. The ITER EDA Phase, due to last until July 1998, will encompass the design of the device and its auxiliary systems and facilities, including the preparation of engineering drawings. The EDA also incorporates validating research and development (R&D) work, including the development and testing of key components. The purpose of this paper is to review the status of the design, as it has been developed so far, emphasizing the design and integration of those components contained within the vacuum vessel of the ITER device. The components included in the in-vessel systems are divertor and first wall; blanket and shield; plasma heating, fueling, and vacuum pumping equipment; and remote handling equipment.

  7. In-vessel Zircaloy oxidation/hydrogen generation behavior during severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Cronenberg, A.W. (Science and Engineering Associates, Inc., Albuquerque, NM (USA))

    1990-09-01

    In-vessel Zircaloy oxidation and hydrogen generation data from various US Nuclear Regulatory Commission severe-fuel damage test programs are presented and compared, where the effects of Zircaloy melting, bundle reconfiguration, and bundle quenching by reflooding are assessed for common findings. The experiments evaluated include fuel bundles incorporating fresh and previously irradiated fuel rods, as well as control rods. Findings indicate that the extent of bundle oxidation is largely controlled by steam supply conditions and that high rates of hydrogen generation continued after melt formation and relocation. Likewise, no retardation of hydrogen generation was noted for experiments which incorporated control rods. Metallographic findings indicate extensive oxidation of once-molten Zircaloy bearing test debris. Such test results indicate no apparent limitations to Zircaloy oxidation for fuel bundles subjected to severe-accident coolant-boiloff conditions. 46 refs., 22 figs., 12 tabs.

  8. Identification and initial assessment of candidate BWR late-phase in-vessel accident management strategies

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, S.A.

    1991-04-15

    Work sponsored by the United States Nuclear Regulatory Commission (USNRC) to identify and perform preliminary assessments of candidate BWR (boiling water reactor) in-vessel accident management strategies was completed at Oak Ridge National Laboratory (ORNL) during fiscal year 1990. Mitigative strategies for containment events have been the subject of a companion study at Brookhaven National Laboratory. The focus of this Oak Ridge effort was the development of new strategies for mitigation of the late phase events, that is, the events that would occur in-vessel after the onset of significant core damage. The work began with an investigation of the current status of BWR in-vessel accident management procedures and proceeded through a preliminary evaluation of several candidate new strategies. The steps leading to the identification of the candidate strategies are described. The four new candidate late-phase (in-vessel) accident mitigation strategies identified by this study and discussed in the report are: (1) keep the reactor vessel depressurized; (2) restore injection in a controlled manner; (3) inject boron if control blade damage has occurred; and (4) containment flooding to maintain core and structural debris in-vessel. Additional assessments of these strategies are proposed.

  9. Contrasting sea-ice and open-water boundary layers during melt and freeze-up seasons: Some result from the Arctic Clouds in Summer Experiment.

    Science.gov (United States)

    Tjernström, Michael; Sotiropoulou, Georgia; Sedlar, Joseph; Achtert, Peggy; Brooks, Barbara; Brooks, Ian; Persson, Ola; Prytherch, John; Salsbury, Dominic; Shupe, Matthew; Johnston, Paul; Wolfe, Dan

    2016-04-01

    With more open water present in the Arctic summer, an understanding of atmospheric processes over open-water and sea-ice surfaces as summer turns into autumn and ice starts forming becomes increasingly important. The Arctic Clouds in Summer Experiment (ACSE) was conducted in a mix of open water and sea ice in the eastern Arctic along the Siberian shelf during late summer and early autumn 2014, providing detailed observations of the seasonal transition, from melt to freeze. Measurements were taken over both ice-free and ice-covered surfaces, offering an insight to the role of the surface state in shaping the lower troposphere and the boundary-layer conditions as summer turned into autumn. During summer, strong surface inversions persisted over sea ice, while well-mixed boundary layers capped by elevated inversions were frequent over open-water. The former were often associated with advection of warm air from adjacent open-water or land surfaces, whereas the latter were due to a positive buoyancy flux from the warm ocean surface. Fog and stratus clouds often persisted over the ice, whereas low-level liquid-water clouds developed over open water. These differences largely disappeared in autumn, when mixed-phase clouds capped by elevated inversions dominated in both ice-free and ice-covered conditions. Low-level-jets occurred ~20-25% of the time in both seasons. The observations indicate that these jets were typically initiated at air-mass boundaries or along the ice edge in autumn, while in summer they appeared to be inertial oscillations initiated by partial frictional decoupling as warm air was advected in over the sea ice. The start of the autumn season was related to an abrupt change in atmospheric conditions, rather than to the gradual change in solar radiation. The autumn onset appeared as a rapid cooling of the whole atmosphere and the freeze up followed as the warm surface lost heat to the atmosphere. While the surface type had a pronounced impact on boundary

  10. Melt spreading code assessment, modifications, and application to the EPR core catcher design.

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, M. T .; Nuclear Engineering Division

    2009-03-30

    The Evolutionary Power Reactor (EPR) is under consideration by various utilities in the United States to provide base load electrical production, and as a result the design is undergoing a certification review by the U.S. Nuclear Regulatory Commission (NRC). The severe accident design philosophy for this reactor is based upon the fact that the projected power rating results in a narrow margin for in-vessel melt retention by external cooling of the reactor vessel. As a result, the design addresses ex-vessel core melt stabilization using a mitigation strategy that includes: (1) an external core melt retention system to temporarily hold core melt released from the vessel; (2) a layer of 'sacrificial' material that is admixed with the melt while in the core melt retention system; (3) a melt plug in the lower part of the retention system that, when failed, provides a pathway for the mixture to spread to a large core spreading chamber; and finally, (4) cooling and stabilization of the spread melt by controlled top and bottom flooding. The overall concept is illustrated in Figure 1.1. The melt spreading process relies heavily on inertial flow of a low-viscosity admixed melt to a segmented spreading chamber, and assumes that the melt mass will be distributed to a uniform height in the chamber. The spreading phenomenon thus needs to be modeled properly in order to adequately assess the EPR design. The MELTSPREAD code, developed at Argonne National Laboratory, can model segmented, and both uniform and nonuniform spreading. The NRC is thus utilizing MELTSPREAD to evaluate melt spreading in the EPR design. MELTSPREAD was originally developed to support resolution of the Mark I containment shell vulnerability issue. Following closure of this issue, development of MELTSPREAD ceased in the early 1990's, at which time the melt spreading database upon which the code had been validated was rather limited. In particular, the database that was utilized for initial

  11. Hydrological scenarios for two selected Alpine catchments for the 21st century using a stochastic weather generator and enhanced process understanding for modelling of seasonal snow and glacier melt for improved water resources management

    Science.gov (United States)

    Strasser, Ulrich; Schneeberger, Klaus; Dabhi, Hetal; Dubrovsky, Martin; Hanzer, Florian; Marke, Thomas; Oberguggenberger, Michael; Rössler, Ole; Schmieder, Jan; Rotach, Mathias; Stötter, Johann; Weingartner, Rolf

    2016-04-01

    The overall objective of HydroGeM³ is to quantify and assess both water demand and water supply in two coupled human-environment mountain systems, i.e. Lütschine in Switzerland and Ötztaler Ache in Austria. Special emphasis is laid on the analysis of possible future seasonal water scarcity. The hydrological response of high Alpine catchments is characterised by a strong seasonal variability with low runoff in winter and high runoff in spring and summer. Climate change is expected to cause a seasonal shift of the runoff regime and thus it has significant impact on both amount and timing of the release of the available water resources, and thereof, possible future water conflicts. In order to identify and quantify the contribution of snow and ice melt as well as rain to runoff, streamflow composition will be analysed with natural tracers. The results of the field investigations will help to improve the snow and ice melt and runoff modules of two selected hydrological models (i.e. AMUNDSEN and WaSiM) which are used to investigate the seasonal water availability under current and future climate conditions. Together, they comprise improved descriptions of boundary layer and surface melt processes (AMUNDSEN), and of streamflow runoff generation (WaSiM). Future meteorological forcing for the modelling until the end of the century will be provided by both a stochastic multi-site weather generator, and downscaled climate model output. Both approches will use EUROCORDEX data as input. The water demand in the selected study areas is quantified for the relevant societal sectors, e.g. agriculture, hydropower generation and (winter) tourism. The comparison of water availability and water demand under current and future climate conditions will allow the identification of possible seasonal bottlenecks of future water supply and resulting conflicts. Thus these investigations can provide a quantitative basis for the development of strategies for sustainable water management in

  12. Wet inside and out? Constraints on water in the Martian mantle and on outgassed water, based on melt inclusions in SNC meteorites

    Science.gov (United States)

    Mcsween, H. Y., Jr.; Harvey, R. P.

    1993-01-01

    Constraints on the volatile inventory and outgassing history of Mars are critical to understanding the origin of ancient valley systems and paleoclimates. Planetary accretion models for Mars allow either a volatile-rich or volatile-poor mantle, depending on whether the accreted materials were fully oxidized or whether accretion was homogeneous so that water was lost through reaction with metallic iron. The amount of water that has been outgassed from the interior is likewise a contentious subject, and estimates of globally distributed water based on various geochemical and geological measurements vary from a few meters to more than a thousand meters. New data on SNC meteorites, which are thought to be Martian igneous rocks, provide constraints on both mantle and outgassed water.

  13. Advanced in-vessel retention design for next generation risk management

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Kune Y.; Hwang, Il Soon [Seoul National University, Seoul (Korea, Republic of)

    1997-12-31

    In the TMI-2 accident, approximately twenty (20) tons of molten core material drained into the lower plenum. Early advanced light water reactor (LWR) designs assumed a lower head failure and incorporated various measures for ex-vessel accident mitigation. However,one of the major findings from the TMI-2 Vessel Investigation Project was that one part of the reactor lower head wall estimated to have attained a temperature of 1100 deg C for about 30 minutes has seemingly experienced a comparatively rapid cooldown with no major threat to the vessel integrity. In this regard, recent empirical and analytical studies have shifted interests to such in-vessel retention designs or strategies as reactor cavity flooding, in-vessel flooding and engineered gap cooling of the vessel. Accurate thermohydrodynamic and creep deformation modeling and rupture prediction are the key to the success in developing practically useful in-vessel accident/risk management strategies. As an advanced in-vessel design concept, this work presents the COrium Attack Syndrome Immunization Structures (COASIS) that are being developed as prospective in-vessel retention devices for a next-generation LWR in concert with existing ex-vessel management measures. Both the engineered gap structures in-vessel (COASISI) and ex-vessel (COASISO) are demonstrated to maintain effective heat transfer geometry during molten core debris attack when applied to the Korean Standard Nuclear Power Plant (KSNPP) reactor. The likelihood of lower head creep rupture during a severe accident is found to be significantly suppressed by the COASIS options. 15 refs., 5 figs., 1 tab. (Author)

  14. 玻璃和熔体包裹体中水含量的拉曼光谱定量测定方面的进展评述%Progress in the determination of water in glasses and melt inclusions with Raman spectroscopy: A short review

    Institute of Scientific and Technical Information of China (English)

    Rainer Thomas; Paul Davidson

    2007-01-01

    This paper is focused on the progress in the determination of water in glasses and melt inclusions with Raman spectroscopy. Using the presented "Comparator Technique" the water content of a sample is determined by simple comparison with a known standard. A calibration curve is not necessary. Furthermore, with this technique the water concentration in silicate melt inclusions can be determined without exposing the inclusions for measurements. This is very important for extremely water-rich melt inclusions, which would loose H2O on exposure.

  15. Dissolved iron in the Arctic shelf seas and surface waters of the central Arctic Ocean : Impact of Arctic river water and ice-melt

    NARCIS (Netherlands)

    Klunder, M. B.; Bauch, D.; Laan, P.; de Baar, H. J. W.; van Heuven, S.; Ober, S.

    2012-01-01

    Concentrations of dissolved (10 nM) in the bottom waters of the Laptev Sea shelf may be attributed to either sediment resuspension, sinking of brine or regeneration of DFe in the lower layers. A significant correlation (R-2 = 0.60) between salinity and DFe is observed. Using delta O-18, salinity, nu

  16. Integrated simulation of snow and glacier melt in water and energy balance‐based, distributed hydrological modeling framework at Hunza River Basin of Pakistan Karakoram region

    National Research Council Canada - National Science Library

    Shrestha, Maheswor; Koike, Toshio; Hirabayashi, Yukiko; Xue, Yongkang; Wang, Lei; Rasul, Ghulam; Ahmad, Bashir

    2015-01-01

    Energy budget‐based distributed modeling of snow and glacier melt runoff is essential in a hydrologic model to accurately describe hydrologic processes in cold regions and high‐altitude catchments...

  17. Water and salt changes during the melting of sea ice covered on soil in winter%冬季覆盖海冰条件下海冰消融过程水盐变化分析

    Institute of Scientific and Technical Information of China (English)

    武林红; 陶军; 张化; 许映军; 常志云

    2014-01-01

    众多国家和地区对非常规水源利用一直给予研究和重视。冬季海冰覆盖条件下,融水质量变化特征不同于常规灌溉,研究和掌握其规律对咸水冰资源综合利用十分重要。利用冬季室外冰柱、土柱实验,以实时监测海冰消融全过程为手段,深入分析冬季覆冰条件下海冰融水水量及总盐动态变化。实验结果表明:融水量最大值出现在下午15时左右;覆盖海冰条件下,海冰消融入渗过程分为集中排盐、深度脱盐、淡水入渗三个阶段。实验结果可为冬季覆冰或咸水结冰灌溉提供技术参考。%Many countries have been taking research on and paying attention to the use of unconventional water resources.In win-ter,sea ice covers on soil,and thus the variation of quality of melted water differs from conventional irrigation water.A thorough understanding of this is of great importance to comprehensively utilize salty ice resources.In this paper,winter outdoor ice col-umn and soil column experiments were carried out by real-time monitoring of sea ice melting in the whole process,and amount and Ec dynamics of melted water were analyzed under sea ice covering conditions.The experimental results showed that,the maximum amount of melted water occurred at about 15:00 pm;under ice covering conditions,ice melting process can be divided into three stages,i.e.,concentrated salt drainage,purity desalination,and fresh water infiltration.Our results could provide technical reference to the winter sea ice or salty water irrigation.

  18. Melting of Transition Metals

    Energy Technology Data Exchange (ETDEWEB)

    Ross, M; Japel, S; Boehler, R

    2005-04-11

    We review the transition melting studies carried out at Mainz, and describe a recently developed model used to explain that the relatively low melting slopes are due to the partially filled d-bands, and the persistence of the pressure induced s-d transition. The basic tenets of the model have now been reconfirmed by new measurements for Cu and Ni. The measurements show that Cu which has a filled 3d-band, has a melt slope that is about 2.5 greater than its neighbor Ni. In the case of Mo, the apparent discrepancy of DAC melting measurements with shock melting can be explained by accounting for the change in melt slope due to the bcc-cp transition observed in the shock studies. The Fe melt curve is revisited. The possible relevance of the Jahn-Teller effect and recently observed transition metal melts with Icosahedral Short-Range Order (ISRO) is discussed.

  19. Anticipating Central Asian Water Stress: Variation in River Flow Dependency on Melt Waters from Alpine to Plains in the Remote Tien Shan Range, Kyrgyzstan Using a Rapid Hydro Assessment Methodology

    Science.gov (United States)

    Hill, A. F.; Wilson, A. M.; Williams, M. W.

    2016-12-01

    The future of mountain water resources in High Asia is of high interest to water managers, development organizations and policy makers given large populations downstream reliant on snow and ice sourced river flow. Together with historical and cultural divides among ex-Soviet republics, a lack of central water management following the Soviet break-up has led to water stress as trans-boundary waters weave through and along borders. New upstream hydropower development, a thirsty downstream agricultural sector and a shrinking Aral Sea has led to increasing tension in the region. Despite these pressures and in contrast to eastern High Asia's Himalayan basins (Ganges, Brahmaputra), little attention has been given to western High Asia draining the Pamir and Tien Shan ranges (Syr Darya and Amu Darya basins) to better understand the hydrology of this vast and remote area. Difficult access and challenging terrain exacerbate challenges to working in this remote mountain region. As part of the Contributions to High Asia Runoff from Ice and Snow (CHARIS) project, we asked how does river flow source water composition change over an alpine-to-plains domain of Kyrgyzstan's Naryn River in the Syr Darya basin? In addition, what may the future hold for river flow in Central Asia given the differing responses of snow and ice to climate changes? Utilizing a Rapid Hydrologic Assessment methodology including a suite of pre-field mapping techniques we collected in situ water chemistry data at targeted, remote mountain sites over 450km of the Naryn River over an elevation gradient from glacial headwaters to the lower lying areas - places where people, hydropower and agriculture utilize water. Chemical and isotope tracers were used to separate stream flow to understand relative dependency on melt waters as the river moves downstream from glaciers and snow covered areas. This case study demonstrates a technique to acquire field data over large scales in remote regions that facilitates

  20. Active cooling system for Tokamak in-vessel operation manipulator

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Jianjun, E-mail: yuanjj@sjtu.edu.cn; Chen, Tan; Li, Fashe; Zhang, Weijun; Du, Liang

    2015-10-15

    Highlights: • We summarized most of the challenges of fusion devices to robot systems. • Propose an active cooling system to protect all of the necessary components. • Trial design test and theoretical analysis were conducted. • Overall implementation of the active cooling system was demonstrated. - Abstract: In-vessel operation/inspection is an indispensable task for Tokamak experimental reactor, for a robot/manipulator is more capable in doing this than human being with more precise motion and less risk of damaging the ambient equipment. Considering the demanding conditions of Tokamak, the manipulator should be adaptable to rapid response in the extreme conditions such as high temperature, vacuum and so on. In this paper, we propose an active cooling system embedded into such manipulator. Cameras, motors, gearboxes, sensors, and other mechanical/electrical components could then be designed under ordinary conditions. The cooling system cannot only be a thermal shield since the components are also heat sources in dynamics. We carry out a trial test to verify our proposal, and analyze the active cooling system theoretically, which gives a direction on the optimization by varying design parameters, components and distribution. And based on thermal sensors monitoring and water flow adjusting a closed-loop feedback control of temperature is added to the system. With the preliminary results, we believe that the proposal gives a way to robust and inexpensive design in extreme environment. Further work will concentrate on overall implementation and evaluation of this cooling system with the whole inspection manipulator.

  1. Lessons learnt from FARO/TERMOS corium melt quenching experiments

    Energy Technology Data Exchange (ETDEWEB)

    Magallon, D.; Huhtiniemi, I.; Hohmann, H. [Commission of the European Communities, Ispra (Italy). Joint Research Center

    1998-01-01

    The influence of melt quantity, melt composition, water depth and initial pressure on quenching is assessed on the basis of seven tests performed in various conditions in the TERMOS vessel of the FARO facility at JRC-Ispra. Tests involved UO{sub 2}-based melt quantities in the range 18-176 kg at a temperature of approximately 3000 K poured into saturated water. The results suggest that erosion of the melt jet column is an efficient contributor to the amount of break-up, and thus quenching, for large pours of corium melt. The presence of Zr metal in the melt induced a much more efficient quenching than in a similar test with no Zr metal, attributed to the oxidation of the Zr. Significant amounts of H{sub 2} were produced also in tests with pure oxidic melts (e.g. about 300 g for 157 kg melt). In the tests at 5.0 and 2.0 MPa good mixing with significant melt break-up and quenching was obtained during the penetration in the water. At 0.5 MPa, good penetration of the melt into the water could still be achieved, but a jump in the vessel pressurisation occurred when the melt contacted the bottom and part (5 kg) of the debris was re-ejected from the water. (author)

  2. Development of ITER in-vessel viewing and metrology systems

    Energy Technology Data Exchange (ETDEWEB)

    Obara, Kenjiro; Kakudate, Satoshi; Nakahira, Masataka; Ito, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-04-01

    The ITER in-vessel viewing system is vital for detecting and locating damage to in-vessel components such as the blankets and divertors and in monitoring and assisting in-vessel maintenance. This system must be able to operate at high temperature (200degC) under intense gamma radiation ({approx}30 kGy/h) in a high vacuum or 1 bar inert gas. A periscope viewing system was chosen as a reference due to its clear, wide view and a fiberscope viewing system chosen as a backup for viewing in narrow confines. According to the ITER R and D program, both systems and a metrology system are being developed through the joint efforts of Japan, the U.S., and RF Home Teams. This paper outlines design and technology development mainly on periscope in-vessel viewing and laser metrology contributed by the Japan Home Team. (author)

  3. Experimental Research of the melting Rate of Water Flow Across Sngle Ice Pillar%水流外掠单体冰柱融化速率试验研究

    Institute of Scientific and Technical Information of China (English)

    孟凡康; 于航

    2014-01-01

    建立水流外掠冰柱实验台,分别开展了水流速度(0.02、0.03、0.04、0.05、0.06和0.07m/s)、水流温度(7、10、13、16和19℃)、冰柱直径(60、70、80和105mm)及冰柱初始温度(-12、-8和-5℃)对于冰柱融化速率的影响研究。通过对融化时间的统计和分析,获得以下结论:水流温度对于融化时间的影响呈幂函数规律;水流速度和冰柱直径对于融化时间的影响呈线性规律;冰柱初始温度对于融化时间影响较小。%The experiment table of water flow across ice pillar was established in this research which mainly analysis how the water velocity (0.02 m/s,0.03 m/s,0.04 m/s,0.05 m/s,0.06 m/s and 0.07m/s),diameter of the ice pillar (60mm、70mm、80mm和105mm),the temperature of water flow(7℃、10℃、13℃、16℃和19℃) and initial temperature of the ice pillar (-12℃、-8℃和-5℃) influenced on the ice pillar melting rate.By analyzing the statistic of melting times,some conclusion could be got as follows:The effects of water temperature on melting time are representing as power function.The effect of water ve-locity and diameter of the ice pillar on melting time are representing as linear.And the influence of initial temperature of ice pillar on melting time has a minimal effect.

  4. Melt onset over Arctic sea ice controlled by atmospheric moisture transport

    Science.gov (United States)

    Mortin, Jonas; Svensson, Gunilla; Graversen, Rune G.; Kapsch, Marie-Luise; Stroeve, Julienne C.; Boisvert, Linette N.

    2016-06-01

    The timing of melt onset affects the surface energy uptake throughout the melt season. Yet the processes triggering melt and causing its large interannual variability are not well understood. Here we show that melt onset over Arctic sea ice is initiated by positive anomalies of water vapor, clouds, and air temperatures that increase the downwelling longwave radiation (LWD) to the surface. The earlier melt onset occurs; the stronger are these anomalies. Downwelling shortwave radiation (SWD) is smaller than usual at melt onset, indicating that melt is not triggered by SWD. When melt occurs early, an anomalously opaque atmosphere with positive LWD anomalies preconditions the surface for weeks preceding melt. In contrast, when melt begins late, clearer than usual conditions are evident prior to melt. Hence, atmospheric processes are imperative for melt onset. It is also found that spring LWD increased during recent decades, consistent with trends toward an earlier melt onset.

  5. In-vessel Retention Strategy for High Power Reactors - K-INERI Final Report (includes SBLB Test Results for Task 3 on External Reactor Vessel Cooling (ERVC) Boiling Data and CHF Enhancement Correlations)

    Energy Technology Data Exchange (ETDEWEB)

    F. B. Cheung; J. Yang; M. B. Dizon; J. Rempe

    2005-01-01

    In-vessel retention (IVR) of core melt is a key severe accident management strategy adopted by some operating nuclear power plants and proposed for some advanced light water reactors (ALWRs). If there were inadequate cooling during a reactor accident, a significant amount of core material could become molten and relocate to the lower head of the reactor vessel, as happened in the Three Mile Island Unit 2 (TMI-2) accident. If it is possible to ensure that the vessel head remains intact so that relocated core materials are retained within the vessel, the enhanced safety associated with these plants can reduce concerns about containment failure and associated risk. For example, the enhanced safety of the Westinghouse Advanced 600 MWe PWR (AP600), which relied upon External Reactor Vessel Cooling (ERVC) for IVR, resulted in the U.S. Nuclear Regulatory Commission (US NRC) approving the design without requiring certain conventional features common to existing LWRs. However, it is not clear that currently proposed external reactor vessel cooling (ERVC) without additional enhancements could provide sufficient heat removal for higher-power reactors (up to 1500 MWe). Hence, a collaborative, three-year, U.S. - Korean International Nuclear Energy Research Initiative (INERI) project was completed in which the Idaho National Engineering and Environmental Laboratory (INEEL), Seoul National University (SNU), Pennsylvania State University (PSU), and the Korea Atomic Energy Research Institute (KAERI) investigated the performance of ERVC and an in-vessel core catcher (IVCC) to determine if IVR is feasible for reactors up to 1500 MWe.

  6. Water content, δD and δ11B tracking in the Vanuatu arc magmas (Aoba Island): Insights from olivine-hosted melt inclusions

    Science.gov (United States)

    Métrich, Nicole; Deloule, Etienne

    2014-10-01

    Ion microprobe measurements of H and B isotopic ratios and H2O, B and trace element contents are reported here for a series of melt inclusions typical of alkaline basalts of Aoba Island in the central part of Vanuatu arc (Southwestern Pacific). The melt inclusions, hosted in olivine Fo86-90, display large ranges in trace element concentrations and hydrogen (δD from - 48.2 to + 61.7‰) and boron (δ11B from - 11.9 to + 6.4‰) isotopic compositions. The high deuterium enrichment (δD ≥ 0‰) observed in a small subset of melt inclusions requires a proton diffusion loss through the olivine network, in addition to late-stage magma interactions with aqueous saline fluids. These melt inclusions are therefore not considered as representative of the magma from which the olivine grew. In most melt inclusions, positive correlations between H2O, K2O, Ba and Sr lead us to determine the K2O/H2O (1.5 ± 0.2), H2O/Ba (46 ± 3 × 10- 4) and H2O/Sr (29 ± 2 × 10- 4) ratios of Aoba basalts. Overall correlations between δ11B, B/Nb, and B/Nd testify to the mixing between slab-derived fluids, preferentially enriched in δ11B and fluid mobile elements and a relatively depleted MORB-type mantle wedge beneath Aoba Island. Heavy δ11B (on average 5.4 ± 0.7‰) indicate slab-derived fluids, possibly involving serpentine, which would have a mean δD value of - 28.4 ± 7‰. The chemical and isotopic variability recorded by Aoba magmas (melt inclusions) is consistent with the geodynamic context of ridge-arc collision in the central segment of Vanuatu arc.

  7. Late Eocene-Early Oligocene two-mica granites in NW Turkey (the Uludağ Massif): Water-fluxed melting products of a mafic metagreywacke

    Science.gov (United States)

    Topuz, Gültekin; Okay, Aral I.

    2017-01-01

    hornblende, (iii) occurrence in a ductile strike-slip zone, and (iv) relatively low magma temperatures can be accounted for by water-fluxed melting of a metagreywacke source with substantial mafic component at middle to lower crustal depths.

  8. CAREM-25 RPV thermal regime evaluation during the application of in-vessel retention strategies

    Energy Technology Data Exchange (ETDEWEB)

    Pomier Baez, Lazaro E.; Baron, Jorge H.; Nunez Mac Leod, Juan E. [Universidad Nacional de Cuyo, Mendoza (Argentina). Facultad de Ingenieria. Instituto CEDIAC

    2002-07-01

    The structural integrity of the reactor vessel is a key question in the analysis of the possibility for retaining the melted materials inside the pressure vessel as a severe accident management (SAM) strategy. The pressure of the system and the thermohydraulic behavior of relocated materials that determine the loads, stresses and the displacements of reactor vessel determine the vessel failure mode and the time until rupture. In-Vessel Retention (IVR) strategy analyses are carried on as part of the advanced design CAREM-25 SAM evaluations. One of the most promising initiatives in this area, is the development of an in-vessel metallic core catcher (IVCC) to arrest reactor vessel meltdown sequences during a severe accident. The concept working principle consists in the mixing of the catcher metallic material (so-called sacrificial material) with the corium relocating fragments in the reactor lower head after the initiation of relocation process. The catcher will limit the catcher-corium mixture temperature by boiling the sacrificial material. For this purpose, a low-boiling point material is chosen. The analysis methodology presented in this paper is designed to evaluate the integrity of CAREM-25 pressure vessel during a severe accident sequence with complete core damage when the IVR strategy is employed. CAREM-25 is a multipurpose small advanced reactor design being developed by CNEA (Comision Nacional de Energia Atomica) and INVAP S. E. in Argentina. (author)

  9. Stability of foams in silicate melts

    Science.gov (United States)

    Proussevitch, Alexander A.; Sahagian, Dork L.; Kutolin, Vladislav A.

    1993-12-01

    Bubble coalescence and the spontaneous disruption of high-porosity foams in silicate melts are the result of physical expulsion of interpore melt (syneresis) leading to bubble coalescence, and diffusive gas exchange between bubbles. Melt expulsion can be achieved either along films between pairs of bubbles, or along Plateau borders which represent the contacts between 3 or more bubbles. Theoretical evaluation of these mechanisms is confirmed by experimental results, enabling us to quantify the relevant parameters and determine stable bubble size and critical film thickness in a foam as a function of melt viscosity, surface tension, and time. Foam stability is controlled primarily by melt viscosity and time. Melt transport leading to coalescence of bubbles proceeds along inter-bubble films for smaller bubbles, and along Plateau borders for larger bubbles. Thus the average bubble size accelerates with time. In silicate melts, the diffusive gas expulsion out of a region of foam is effective only for water (and even then, only at small length scales), as the diffusion of CO 2 is negligible. The results of our analyses are applicable to studies of vesicularity of lavas, melt degassing, and eruption mechanisms.

  10. Development of KSTAR in-vessel components and heating systems

    Energy Technology Data Exchange (ETDEWEB)

    Yang, H.L., E-mail: hlyang@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Park, Y.M.; Bae, Y.S.; Kim, H.K.; Kim, K.M.; Lee, K.S.; Bang, E.N.; Kim, H.T.; Lee, H.J.; Kwag, S.W.; Chang, Y.B.; Song, N.H.; Park, H.T.; Joung, M.; Kim, J.S.; Han, W.S.; Kwon, M. [National Fusion Research Institute, Daejeon (Korea, Republic of); Park, S.I.; Do, H.J.; Cho, M.H. [Pohang University of Science and Technology, Pohang (Korea, Republic of)

    2011-10-15

    In-vessel components of the Korea Superconducting Tokamak Advanced Research (KSTAR) were developed for 2010 campaign to provide a crucial circumstance for achieving the strongly shaped and diverted plasma. Moreover, the in-vessel components such as limiter, divertor, passive stabilizer, in-vessel control coil (IVCC) system demonstrated good performances satisfying the original design concepts. In addition to the plasma facing components and the IVCC, in-vessel cryo-pump (IVCP) system was also installed to leverage divertor operation. Besides the in-vessel components, there have been substantial progresses in development of the heating and current drive system. The KSTAR heating and current drive system includes all kinds of the major heating systems such as neutral beam injection (NBI), ion cyclotron range of frequency (ICRF), electron cyclotron resonance heating and current drive (ECH and ECCD), lower hybrid current drive (LHCD) systems. As an initial stage for full equipment of the heating systems to total power of 26 MW, several key systems such as 1st NBI (called NBI-1), ICRF, and ECH-assisted startup system successfully demonstrated their excellent feasibilities in the design and performances for dedication to the 2010 campaign.

  11. Excess water generation during reaction-inducing intrusion of granitic melts into ultramafic rocks at crustal P-T conditions in the Sør Rondane Mountains of East Antarctica

    Science.gov (United States)

    Uno, Masaoki; Okamoto, Atsushi; Tsuchiya, Noriyoshi

    2017-07-01

    Arc magmas are one of the main sources of aqueous geofluids in the crust, and the movement of fluids above magma chambers has been geophysically imaged. Here, we constrain the water budget (i.e., supply, consumption and release of H2O) in these areas above magma chamber by examining the hydration caused by crust-melt reactions in the Sør Rondane Mountains of East Antarctica. The study area contains a phlogopite-pargasite-peridotite unit that has been intruded by numerous granitic dikes, creating hydration reaction zones at the dike-peridotite boundary. These reactions occurred at 0.5 GPa and 700 °C, corresponding to middle crustal conditions, and generated a series of reaction zones with distance from the granitic dikes as follows: (i) granitic dike, (ii) pargasite-actinolite zone, (iii) tremolite-phlogopite zone, (iv) anthophyllite-phlogopite zone, (v) phlogopite-olivine-orthopyroxene zone, and (vi) unaltered pargasite-phlogopite peridotite. The presence of amphiboles with a preferred orientation perpendicular to the dike margins and an absence of Cr-rich magnetite indicate that the pargasite-actinolite zone [zone (ii)] grew from the dike margins as a result of the dike reacting with the host rock, with an initial melt/rock boundary located between zones (ii) and (iii). The H2O contents of reaction zones (ii)-(v) are higher than the content in the hosting pargasite-phlogopite peridotite, suggesting that the intrusion of the dike was associated with hydration reactions. Geochemical analysis along a profile through the reaction zones indicates Mg and Fe depletion, and Si enrichment in zones (iii)-(iv), and Ca depletion and K enrichment in zones (iv)-(v) relative to the hosting pargasite-phlogopite peridotite. In contrast, zone (ii) is characterized by Ca, Fe, and Mg enrichments relative to the granitic dike. These observations suggest that the reaction zone sequence was formed by the elemental transfer between granitic dike and parasite-phlogopite peridotite: Ca

  12. 不同钠吸附比的咸水结冰融水入渗后滨海盐土的水盐分布%Water and salt distribution in coastal saline soil after infiltration of melt-water of saline water ice with different sodium adsorption ratio

    Institute of Scientific and Technical Information of China (English)

    郭凯; 陈丽娜; 张秀梅; 刘小京

    2011-01-01

    在室内利用相同矿化度(10 g·L-1)、不同钠吸附比(5、10和30)的咸水进行咸水结冰融水模拟试验、结冰融水入渗和咸水直接入渗的土柱试验,以淡水处理为对照,分析不同钠吸附比咸水结冰融水入渗下滨海盐土水盐分布特征.结果表明:咸水冰融化过程中,融出水的矿化度和钠吸附比均呈由高到低的变化趋势.咸水结冰融水入渗速度和入渗深度均快于和深于淡水.咸水钠吸附比越小,结冰融水入渗速率越快、深度越深.水盐分布也表现为低钠吸附比咸水结冰处理的表层土壤含水量较低,水分向深层迁移,这种水分分布也使盐分向深层运移,表现为表层土壤含盐量低,深层土壤含盐量大.土层含水量低钠吸附比咸水处理高于高钠吸附比处理,10~45 cm土层则表现出相反的趋势;表层土含盐量低钠吸附比处理高于高钠吸附比处理,且咸水处理下土壤脱盐的深度大于淡水处理.钠吸附比5的咸水结冰处理,0~10 cm土壤平均含水量和含盐量分别为30.3%和1.1 g·kg-1,显著低于其他处理.为比较咸水结冰灌溉和咸水直接灌溉的效果,室内利用含盐量为10 g.L-1、钠吸附比10的咸水进行直接入渗的土柱(土壤含盐量为213 g·kg-1)模拟试验,结果表明:与咸水直接入渗处理相比,咸水结冰融水处理盐分淋洗效果更好,该处理0~25 cm土层平均土壤含盐量为2.9g·kg-1,显著低于咸水直接入渗的10.6 g·kg-1.%A laboratory soil column experiment was conducted to investigate water and salt distribution in coastal saline soil after saline ice melt-water infiltration. A salinity of 10 g·L-1 was designed with three variants of saline sodium adsorption ratios (SAR, i. e,5, 10 and 30) as source water in the experiment, with fresh water as the control. The results showed that both the salinity and SAR levels of melt-water were extremely higher in the initial melt-water than in subsequent melt-waters

  13. Inhibitive effect of molybdate-based inhibitor for carbon steel in sea ice melt water%钼酸盐复合缓蚀剂对海冰融水中碳钢的缓蚀作用

    Institute of Scientific and Technical Information of China (English)

    程方; 况宇飞; 罗大兵; 何怡; 苏雅丽

    2012-01-01

    By orthogonal experiment screening,the molybdate-based multiple corrosion inhibitor has been composited. The corrosion inhibiting effect of molybdate composite corrosion inhibitor in sea ice melt water on Q235 carbon steel is studied by weight loss method, and polarization curve method. And the corrosion inhibiting effect of it in sea ice melt water with high concentration multiple(2-5 times) is verified. The results show that this molybdate-based inhibitor in sea ice melt water presents good effects of corrosion inhibition. The optimum inhibition rate of molybdate composite corrosion inhibitor is up to 99.35%, which functions as an anodic inhibitor.%通过正交试验筛选、复配以钼酸盐为主剂的多元复合缓蚀剂,以失重法和极化曲线法研究了该钼酸盐复合缓蚀剂在海冰融水中对Q235碳钢的缓蚀效果,并对其在高浓缩倍数(2~5倍)海冰融水中的缓蚀作用进行了验证.结果表明:该钼酸盐复合缓蚀剂在海冰融水中对碳钢的缓蚀效果良好,缓蚀率最高达到99.35%;该钼酸盐复合缓蚀剂为阳极抑制型缓蚀剂.

  14. Melting Metal on a Playing Card

    Science.gov (United States)

    Greenslade, Thomas B., Jr.

    2016-01-01

    Many of us are familiar with the demonstration of boiling water in a paper cup held over a candle or a Bunsen burner; the ignition temperature of paper is above the temperature of 100°C at which water boils under standard conditions. A more dramatic demonstration is melting tin held in a playing card. This illustration is from Tissandier's book on…

  15. Rotation of melting ice disks due to melt fluid flow.

    Science.gov (United States)

    Dorbolo, S; Adami, N; Dubois, C; Caps, H; Vandewalle, N; Darbois-Texier, B

    2016-03-01

    We report experiments concerning the melting of ice disks (85 mm in diameter and 14 mm in height) at the surface of a thermalized water bath. During the melting, the ice disks undergo translational and rotational motions. In particular, the disks rotate. The rotation speed has been found to increase with the bath temperature. We investigated the flow under the bottom face of the ice disks by a particle image velocimetry technique. We find that the flow goes downwards and also rotates horizontally, so that a vertical vortex is generated under the ice disk. The proposed mechanism is the following. In the vicinity of the bottom face of the disk, the water eventually reaches the temperature of 4 °C for which the water density is maximum. The 4 °C water sinks and generates a downwards plume. The observed vertical vorticity results from the flow in the plume. Finally, by viscous entrainment, the horizontal rotation of the flow induces the solid rotation of the ice block. This mechanism seems generic: any vertical flow that generates a vortex will induce the rotation of a floating object.

  16. Multi-purpose deployer for ITER in-vessel maintenance

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Chang-Hwan, E-mail: Chang-Hwan.CHOI@iter.org [ITER Organization, Route de Vinon-sur-Verdon, 13115 St Paul lez Durance (France); Tesini, Alessandro; Subramanian, Rajendran [ITER Organization, Route de Vinon-sur-Verdon, 13115 St Paul lez Durance (France); Rolfe, Alan; Mills, Simon; Scott, Robin; Froud, Tim; Haist, Bernhard; McCarron, Eddie [Oxford Technologies Ltd., 7 Nuffield Way, Abingdon, OXON (United Kingdom)

    2015-10-15

    Highlights: • ITER RH system called as the multi-purpose deployer (MPD) is introduced. • The MPD performs dust and tritium inventory control, in-service inspection. • The MPD performs leak localization, in-vessel diagnostics maintenance. • The MPD has nine degrees of freedom with a payload capacity up to 2 tons. - Abstract: The multi-purpose deployer (MPD) is a general purpose in-vessel remote handling (RH) system in the ITER RH system. The MPD provides the means for deployment and handling of in-vessel tools or components inside the vacuum vessel (VV) for dust and tritium inventory control, in-service inspection, leak localization, and in-vessel diagnostics. It also supports the operation of blanket first wall maintenance and neutral beam duct liner module maintenance operations. This paper describes the concept design of the MPD. The MPD is a cask based system, i.e. it stays in the hot cell building during the machine operation, and is deployed to the VV using the cask system for the in-vessel operations. The main part of the MPD is the articulated transporter which provides transportation and positioning of the in-vessel tools or components. The articulated transporter has nine degrees of freedom with a payload capacity up to 2 tons. The articulated transporter can cover the whole internal surface of the VV by switching between the four equatorial RH ports. Additionally it can use two non-RH equatorial ports to transfer large tools or components. A concept for in-cask tool exchange is developed which minimizes the cask transportation by allowing the MPD to stay in the VV during the tool exchange.

  17. Evolution of melt-vapor surface tension in silicic volcanic systems: Experiments with hydrous melts

    Science.gov (United States)

    Mangan, M.; Sisson, T.

    2005-01-01

    We evaluate the melt-vapor surface tension (??) of natural, water-saturated dacite melt at 200 MPa, 950-1055??C, and 4.8-5.7 wt % H2O. We experimentally determine the critical supersaturation pressure for bubble nucleation as a function of dissolved water and then solve for ?? at those conditions using classical nucleation theory. The solutions obtained give dacite melt-vapor surface tensions that vary inversely with dissolved water from 0.042 (??0.003) J m-2 at 5.7 wt% H2O to 0.060 (??0.007) J m-2 at 5.2 wt% H2O to 0.073 (??0.003) J m-2 at 4.8 wt% H2O. Combining our dacite results with data from published hydrous haplogranite and high-silica rhyolite experiments reveals that melt-vapor surface tension also varies inversely with the concentration of mafic melt components (e.g., CaO, FeOtotal, MgO). We develop a thermodynamic context for these observations in which melt-vapor surface tension is represented by a balance of work terms controlled by melt structure. Overall, our results suggest that cooling, crystallization, and vapor exsolution cause systematic changes in ?? that should be considered in dynamic modeling of magmatic processes.

  18. Signatures of nonthermal melting

    Directory of Open Access Journals (Sweden)

    Tobias Zier

    2015-09-01

    Full Text Available Intense ultrashort laser pulses can melt crystals in less than a picosecond but, in spite of over thirty years of active research, for many materials it is not known to what extent thermal and nonthermal microscopic processes cause this ultrafast phenomenon. Here, we perform ab-initio molecular-dynamics simulations of silicon on a laser-excited potential-energy surface, exclusively revealing nonthermal signatures of laser-induced melting. From our simulated atomic trajectories, we compute the decay of five structure factors and the time-dependent structure function. We demonstrate how these quantities provide criteria to distinguish predominantly nonthermal from thermal melting.

  19. Atmospheric conditions during the Arctic Clouds in Summer Experiment (ACSE): Contrasting open-water and sea-ice surfaces during melt and freeze-up seasons

    OpenAIRE

    Sotiropoulou, G.; Tjernström, M.; Sedlar, J.; Achtert, P; Brooks, BJ; Brooks, IM; Persson, POG; Prytherch, J.; Salisbury, DJ; Shupe, MD; Johnston, PE; Wolfe, D.

    2016-01-01

    The Arctic Clouds in Summer Experiment (ACSE) was conducted during summer and early autumn 2014, providing a detailed view of the seasonal transition from ice melt into freeze-up. Measurements were taken over both ice-free and ice-covered surfaces near the ice edge, offering insight into the role of the surface state in shaping the atmospheric conditions. The initiation of the autumn freeze-up was related to a change in air mass, rather than to changes in solar radiation alone; the lower atmo...

  20. Trajectory planning of tokamak flexible in-vessel inspection robot

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hesheng [Department of Automation, Shanghai Jiao Tong University, 200240 Shanghai (China); Key Laboratory of System Control and Information Processing, Ministry of Education of China, 200240 Shanghai (China); Chen, Weidong, E-mail: wdchen@sjtu.edu.cn [Department of Automation, Shanghai Jiao Tong University, 200240 Shanghai (China); Key Laboratory of System Control and Information Processing, Ministry of Education of China, 200240 Shanghai (China); Lai, Yinping; He, Tao [Department of Automation, Shanghai Jiao Tong University, 200240 Shanghai (China); Key Laboratory of System Control and Information Processing, Ministry of Education of China, 200240 Shanghai (China)

    2015-10-15

    Highlights: • A tokamak flexible in-vessel inspection robot is designed. • Two trajectory planning methods are used to ensure the full coverage of the first wall scanning. • The method is tested on a simulated platform of EAST with the flexible in-vessel inspection robot. • Experimental results show the effectiveness of the proposed algorithm. - Abstract: Tokamak flexible in-vessel inspection robot is mainly designed to carry a camera for close observation of the first wall of the vacuum vessel, which is essential for the maintenance of the future tokamak reactor without breaking the working condition of the vacuum vessel. A tokamak flexible in-vessel inspection robot is designed. In order to improve efficiency of the remote maintenance, it is necessary to design a corresponding trajectory planning algorithm to complete the automatic full coverage scanning of the complex tokamak cavity. Two different trajectory planning methods, RS (rough scanning) and FS (fine scanning), according to different demands of the task, are used to ensure the full coverage of the first wall scanning. To quickly locate the damage position, the first trajectory planning method is targeted for quick and wide-ranging scan of the tokamak D-shaped section, and the second one is for careful observation. Furthermore, both of the two different trajectory planning methods can ensure the full coverage of the first wall scanning with an optimal end posture. The method is tested on a simulated platform of EAST (Experimental Advanced Superconducting Tokamak) with the flexible in-vessel inspection robot, and the results show the effectiveness of the proposed algorithm.

  1. Optimization and Update of EAST In-Vessel Components in 2011

    Science.gov (United States)

    Ji, Xiang; Song, Yuntao; Shen, Guang; Cao, Lei; Zhou, Zibo; Xu, Tiejun; Liu, Xufeng; Xu, Weiwei; Peng, Xuebing; Wang, Shengming; Zhang, Ping; Zhu, Ning; Dai, Yu; Liu, Zhihong; Wu, Jiefeng; Gao, Daming; Gong, Xianzu; Fu, Peng; Wan, Baonian; Li, Jiangang

    2013-03-01

    For safe operation with active water cooling plasma facing components (PFCs) to handle a large input power over a long pulse discharge, some design optimization, R&D and maintenance were accomplished to improve the in-vessel components. For the purpose of large plasma current (1 MA) operation, the previous separated top and bottom passive stabilizers in the low field were electrical connected to stabilize plasma in the case of vertical displace events (VDEs). The design and experiments are described in this paper

  2. Melt Cast High Explosives

    Directory of Open Access Journals (Sweden)

    Stanisław Cudziło

    2014-12-01

    Full Text Available [b]Abstract[/b]. This paper reviews the current state and future developments of melt-cast high explosives. First the compositions, properties and methods of preparation of trinitrotoluene based (TNT conventional mixtures with aluminum, hexogen (RDX or octogen (HMX are described. In the newer, less sensitive explosive formulations, TNT is replaced with dinitroanisole (DNANDNANDNAN and nitrotriazolone (NTONTONTO, nitroguanidine (NG or ammonium perchlorate (AP are the replacement for RDRDX and HMX. Plasticized wax or polymer-based binder systems for melt castable explosives are also included. Hydroxyl terminated polybutadiene (HPTB is the binder of choice, but polyethylene glycol, and polycaprolactone with energetic plasticizers are also used. The most advanced melt-cast explosives are compositions containing energetic thermoplastic elastomers and novel highly energetic compounds (including nitrogen rich molecules in whose particles are nanosized and practically defect-less.[b]Keywords[/b]: melt-cast explosives, detonation parameters

  3. Melting of sodium clusters

    CERN Document Server

    Reyes-Nava, J A; Beltran, M R; Michaelian, K

    2002-01-01

    Thermal stability properties and the melting-like transition of Na_n, n=13-147, clusters are studied through microcanonical molecular dynamics simulations. The metallic bonding in the sodium clusters is mimicked by a many-body Gupta potential based on the second moment approximation of a tight-binding Hamiltonian. The characteristics of the solid-to-liquid transition in the sodium clusters are analyzed by calculating physical quantities like caloric curves, heat capacities, and root-mean-square bond length fluctuations using simulation times of several nanoseconds. Distinct melting mechanisms are obtained for the sodium clusters in the size range investigated. The calculated melting temperatures show an irregular variation with the cluster size, in qualitative agreement with recent experimental results. However, the calculated melting point for the Na_55 cluster is about 40 % lower than the experimental value.

  4. Surface melt and ponding on Larsen C Ice shelf and the impact of foehn winds

    OpenAIRE

    Luckman, Adrian; Elvidge, Andrew; Jansen, Daniela; Kulessa, Bernd; Kuipers-Munneke, Peter; King, John; Barrand, Nick

    2014-01-01

    A common precursor to ice shelf disintegration, most notably that of Larsen B Ice Shelf, is unusually intense or prolonged surface melt and the presence of surface standing water. However, there has been little research into detailed patterns of melt on ice shelves or the nature of summer melt ponds. We investigated surface melt on Larsen C Ice Shelf at high resolution using Envisat advanced synthetic aperture radar (ASAR) data and explored melt ponds in a range of satellite image...

  5. Melt onset over Arctic sea ice controlled by atmospheric moisture transport

    OpenAIRE

    Mortin, J.; G. Svensson; Graversen, R.; Kapsch, M.; Stroeve, J.; Boisvert, L.

    2016-01-01

    The timing of melt onset affects the surface energy uptake throughout the melt season. Yet the processes triggering melt and causing its large interannual variability are not well understood. Here we show that melt onset over Arctic sea ice is initiated by positive anomalies of water vapor, clouds, and air temperatures that increase the downwelling longwave radiation (LWD) to the surface. The earlier melt onset occurs; the stronger are these anomalies. Downwelling shortwave radiation (SWD) is...

  6. Ice-sheet acceleration driven by melt supply variability.

    Science.gov (United States)

    Schoof, Christian

    2010-12-09

    Increased ice velocities in Greenland are contributing significantly to eustatic sea level rise. Faster ice flow has been associated with ice-ocean interactions in water-terminating outlet glaciers and with increased surface meltwater supply to the ice-sheet bed inland. Observed correlations between surface melt and ice acceleration have raised the possibility of a positive feedback in which surface melting and accelerated dynamic thinning reinforce one another, suggesting that overall warming could lead to accelerated mass loss. Here I show that it is not simply mean surface melt but an increase in water input variability that drives faster ice flow. Glacier sliding responds to melt indirectly through changes in basal water pressure, with observations showing that water under glaciers drains through channels at low pressure or through interconnected cavities at high pressure. Using a model that captures the dynamic switching between channel and cavity drainage modes, I show that channelization and glacier deceleration rather than acceleration occur above a critical rate of water flow. Higher rates of steady water supply can therefore suppress rather than enhance dynamic thinning, indicating that the melt/dynamic thinning feedback is not universally operational. Short-term increases in water input are, however, accommodated by the drainage system through temporary spikes in water pressure. It is these spikes that lead to ice acceleration, which is therefore driven by strong diurnal melt cycles and an increase in rain and surface lake drainage events rather than an increase in mean melt supply.

  7. Force induced DNA melting

    Energy Technology Data Exchange (ETDEWEB)

    Santosh, Mogurampelly; Maiti, Prabal K [Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore-12 (India)], E-mail: santosh@physics.iisc.ernet.in, E-mail: maiti@physics.iisc.ernet.in

    2009-01-21

    When pulled along the axis, double-strand DNA undergoes a large conformational change and elongates by roughly twice its initial contour length at a pulling force of about 70 pN. The transition to this highly overstretched form of DNA is very cooperative. Applying a force perpendicular to the DNA axis (unzipping), double-strand DNA can also be separated into two single-stranded DNA, this being a fundamental process in DNA replication. We study the DNA overstretching and unzipping transition using fully atomistic molecular dynamics (MD) simulations and argue that the conformational changes of double-strand DNA associated with either of the above mentioned processes can be viewed as force induced DNA melting. As the force at one end of the DNA is increased the DNA starts melting abruptly/smoothly above a critical force depending on the pulling direction. The critical force f{sub m}, at which DNA melts completely decreases as the temperature of the system is increased. The melting force in the case of unzipping is smaller compared to the melting force when the DNA is pulled along the helical axis. In the case of melting through unzipping, the double-strand separation has jumps which correspond to the different energy minima arising due to sequence of different base pairs. The fraction of Watson-Crick base pair hydrogen bond breaking as a function of force does not show smooth and continuous behavior and consists of plateaus followed by sharp jumps.

  8. Simulation of the melt season using a resolved sea ice model with snow cover and melt ponds

    Science.gov (United States)

    Skyllingstad, Eric D.; Shell, Karen M.; Collins, Lee; Polashenski, Chris

    2015-07-01

    A three-dimensional sea ice model is presented with resolved snow thickness variations and melt ponds. The model calculates heating from solar radiative transfer and simulates the formation and movement of brine/melt water through the ice system. Initialization for the model is based on observations of snow topography made during the summer melt seasons of 2009, 2010, and 2012 from a location off the coast of Barrow, AK. Experiments are conducted to examine the importance of snow properties and snow and ice thickness by comparing observed and modeled pond fraction and albedo. One key process simulated by the model is the formation of frozen layers in the ice as relatively warm fresh water grid cells freeze when cooled by adjacent, cold brine-filled grid cells. These layers prevent vertical drainage and lead to flooding of melt water commonly observed at the beginning of the melt season. Flooding persists until enough heat is absorbed to melt through the frozen layer. The resulting long-term melt pond coverage is sensitive to both the spatial variability of snow cover and the minimum snow depth. For thin snow cover, initial melting results in earlier, reduced flooding with a small change in pond fraction after drainage of the melt water. Deeper snow tends to generate a delayed, larger peak pond fraction before drainage.

  9. DESIGN OF THE ITER IN-VESSEL COILS

    Energy Technology Data Exchange (ETDEWEB)

    Neumeyer, C; Bryant, L; Chrzanowski, J; Feder, R; Gomez, M; Heitzenroeder, P; Kalish, M; Lipski, A; Mardenfeld, M; Simmons, R; Titus, P; Zatz, I; Daly, E; Martin, A; Nakahira, M; Pillsbury, R; Feng, J; Bohm, T; Sawan, M; Stone, H; Griffiths, I

    2010-11-27

    The ITER project is considering the inclusion of two sets of in-vessel coils, one to mitigate the effect of Edge Localized Modes (ELMs) and another to provide vertical stabilization (VS). The in-vessel location (behind the blanket shield modules, mounted to the vacuum vessel inner wall) presents special challenges in terms of nuclear radiation (~3000 MGy) and temperature (100oC vessel during operations, 200oC during bakeout). Mineral insulated conductors are well suited to this environment but are not commercially available in the large cross section required. An R&D program is underway to demonstrate the production of mineral insulated (MgO or Spinel) hollow copper conductor with stainless steel jacketing needed for these coils. A preliminary design based on this conductor technology has been developed and is presented herein.

  10. A new trial of tokamak in-vessel inspection manipulator

    Energy Technology Data Exchange (ETDEWEB)

    Du, Liang; Yuan, Jianjun, E-mail: yuanjj@sjtu.edu.cn; Zhang, Weijun; Li, Fashe

    2015-10-15

    In this paper, we discuss the design and partial implementation of an in-vessel inspection manipulator in detail, which is considered to serve for China's Experimental Advanced Superconducting Tokamak (EAST). Besides the ordinary kinematic/dynamic constraints and specifications for a multiple degrees of freedom (DOF) manipulator suitable for EAST in-vessel inspection, there is extra necessity in design for the extreme in-vessel environment, e.g., high temperature and high vacuum. Based on our recent developed active cooling system, a specific proposal is explored, which employs ordinary commercial mechanical/electrical components only, as if the manipulator works in normal temperature environment. This paper also emphasizes some challenging technical issues toward an implementation, such as an optimization of thermal gradient/cooling path in the manipulator, a trade-off between large reachable space and large rotation angle of each joint, a special designed revolute joint structure for cooling tube arrangement and so on. We use an EtherCAT based real time control platform connecting drivers and sensors, which achieves a robust closed-loop system and a clean cable aspect simultaneously. In the later part of the paper, basic mechanical tests and inspection process are described. Evaluation on recent progress and future work toward a whole-scale test is stated and expected.

  11. ESCIMO.spread – a spreadsheet-based point snow surface energy balance model to calculate hourly snow water equivalent and melt rates for historical and changing climate conditions

    Directory of Open Access Journals (Sweden)

    T. Marke

    2010-05-01

    Full Text Available This paper describes the spreadsheet-based point energy balance model ESCIMO.spread which simulates the energy and mass balance as well as melt rates of a snow surface. The model makes use of hourly recordings of temperature, precipitation, wind speed, relative humidity, global and longwave radiation. The effect of potential climate change on the seasonal evolution of the snow cover can be estimated by modifying the time series of observed temperature and precipitation by means of adjustable parameters. Model output is graphically visualized in hourly and daily diagrams. The results compare well with weekly measured snow water equivalent (SWE. The model is easily portable and adjustable, and runs particularly fast: hourly calculation of a one winter season is instantaneous on a standard computer. ESICMO.spread can be obtained from the authors on request (contact: ulrich.strasser@uni-graz.at.

  12. Experimental study of in-and-ex-vessel melt cooling during a severe accident

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Baik; Yoo, K. J.; Park, C. K.; Seok, S. D.; Park, R. J.; Yi, S. J.; Kang, K. H.; Ham, Y. S.; Cho, Y. R.; Kim, J. H.; Jeong, J. H.; Shin, K. Y.; Cho, J. S.; Kim, D. H.

    1997-07-01

    After code damage during a severe accident in a nuclear reactor, the degraded core has to be cooled down and the decay heat should be removed in order to cease the accident progression and maintain a stable state. The cooling of core melt is divided into in-vessel and ex-vessel cooling depending on the location of molten core which is dependent on the timing of vessel failure. Since the cooling mechanism varies with the conditions of molten core and surroundings and related phenomena, it contains many phenomenological uncertainties so far. In this study, an experimental study for verification of in-vessel corium cooling and several separate effect experiments for ex-vessel cooling are carried out to verify in- and ex-vessel cooling phenomena and finally to develop the accident management strategy and improve engineered reactor design for the severe accidents. SONATA-IV (Simulation of Naturally Arrested Thermal Attack in Vessel) program is set up for in-vessel cooling and a progression of the verification experiment has been done, and an integral verification experiment of the containment integrity for ex-vessel cooling is planned to be carried out based on the separate effect experiments performed in the first phase. First phase study of SONATA-IV is proof of principle experiment and it is composed of LALA (Lower-plenum Arrested Vessel Attack) experiment to find the gap between melt and the lower plenum during melt relocation and to certify melt quenching and CHFG (Critical Heat Flux in Gap) experiment to certify heat transfer mechanism in an artificial gap. As separate effect experiments for ex-vessel cooling, high pressure melt ejection experiment related to the initial condition for debris layer formation in the reactor cavity, crust formation and heat transfer experiment in the molten pool and molten core concrete interaction experiment are performed. (author). 150 refs., 24 tabs., 127 figs.

  13. Gelatinization of starch in excess water: beyond the melting of lamellar crystallites. A combined wide- and small-angle X-ray scattering study.

    Science.gov (United States)

    Vermeylen, Rudi; Derycke, Veerle; Delcour, Jan A; Goderis, Bart; Reynaers, Harry; Koch, Michel H J

    2006-09-01

    The gelatinization of waxy rice, regular rice, and potato starch suspensions (66% w/w moisture) was investigated by real-time small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) during heating and by fast ramp differential scanning calorimetry (DSC). The high-angle tail of the SAXS patterns suggested the transition from surface to mass fractal structures in the DSC gelatinization range. Amylose plays a major role in determining the dimensions of the self-similar structures that develop during this process as the characteristic power-law scattering behavior extends to lower scattering angles for regular than for waxy starches. Crystallinity of A-type starches is lost in the temperature region roughly corresponding to the DSC gelatinization range. At the end of the gelatinization endotherm, the B-type potato starch showed residual crystallinity (WAXD), while SAXS-patterns exhibited features of remaining lamellar stacks. Results indicate that the melting of amylopectin crystallites during gelatinization is accompanied by the (exothermic) formation of amorphous networks.

  14. GLASS MELTING PHENOMENA, THEIR ORDERING AND MELTING SPACE UTILISATION

    Directory of Open Access Journals (Sweden)

    Němec L.

    2013-12-01

    Full Text Available Four aspects of effective glass melting have been defined – namely the fast kinetics of partial melting phenomena, a consideration of the melting phenomena ordering, high utilisation of the melting space, and effective utilisation of the supplied energy. The relations were defined for the specific melting performance and specific energy consumption of the glass melting process which involve the four mentioned aspects of the process and indicate the potentials of effective melting. The quantity “space utilisation” has been treated in more detail as an aspect not considered in practice till this time. The space utilisation was quantitatively defined and its values have been determined for the industrial melting facility by mathematical modelling. The definitions of the specific melting performance and specific energy consumption have been used for assessment of the potential impact of a controlled melt flow and high space utilisation on the melting process efficiency on the industrial scale. The results have shown that even the partial control of the melt flow, leading to the partial increase of the space utilisation, may considerably increase the melting performance, whereas a decrease of the specific energy consumption was determined to be between 10 - 15 %.

  15. Viscosity Measurement for Tellurium Melt

    Science.gov (United States)

    Lin, Bochuan; Li, Chao; Ban, Heng; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.

    2006-01-01

    The viscosity of high temperature Te melt was measured using a new technique in which a rotating magnetic field was applied to the melt sealed in a suspended ampoule, and the torque exerted by rotating melt flow on the ampoule wall was measured. Governing equations for the coupled melt flow and ampoule torsional oscillation were solved, and the viscosity was extracted from the experimental data by numerical fitting. The computational result showed good agreement with experimental data. The melt velocity transient initiated by the rotating magnetic field reached a stable condition quickly, allowing the viscosity and electrical conductivity of the melt to be determined in a short period.

  16. Thermoacoustic Streaming and Ultrasonic Processing of Low Melting Melts

    Science.gov (United States)

    Trinh, E. H.

    1997-01-01

    Ultrasonic levitation allows the processing of low melting materials both in 1 G as well as in microgravity. The free suspension of the melts also facilitates undercooling, permitting the measurements of the physical properties of the metastable liquids.

  17. Simulation of In-Vessel Corium Retention through External Reactor Vessel Cooling for SMART using SIMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jin-Sung; Son, Donggun; Park, Rae-Joon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Thermal load analysis from the corium pool to the outer reactor vessel in the lower plenum of the reactor vessel is necessary to evaluate the effect of the IVR-ERVC during a severe accident for SMART. A computational code called SIMPLE (Sever Invessel Melt Progression in Lower plenum Environment) has been developed for analyze transient behavior of molten corium in the lower plenum, interaction between corium and coolant, and heat-up and ablation of reactor vessel wall. In this study, heat load analysis of the reactor vessel for SMART has been conducted using the SIMPLE. Transient behavior of the molten corium in the lower plenum and IVR-ERVC for SMART has been simulated using SIMPLE. Heat flux from the corium pool to the outer reactor vessel is concentrated in metallic layer by the focusing effect. As a result, metallic layer shows higher temperature than the oxidic layer. Also, vessel wall of metallic layer has been ablated by the high in-vessel temperature. Ex-vessel temperature of the metallic layer was maintained 390 K and vessel thickness was maintained 14 cm. It means that the reactor vessel integrity is maintained by the IVR-ERVC.

  18. Neutronics Analysis of the ITER In-Vessel Viewing System

    CERN Document Server

    Turner, Andrew; Puiu, Adrian

    2013-01-01

    The In-Vessel Viewing System (IVVS) in ITER consists of six identical units which are deployed between pulses or during shutdown, to perform visual examination and metrology of plasma facing components. The system is housed in dedicated ports at B1 level, with deployment at the level between the divertor cassettes and the lowermost outboard blanket modules. Boron carbide shielding blocks are envisaged to protect the sensitive components of the IVVS from damage during operations, and personnel from radiation fields. In order to progress the design of the IVVS beyond the pre-conceptual stage, analyses were conducted using MCNP to determine the acceptability of a series of different shielding configurations.

  19. Effects of saline ice-melt water irrigation on soil water, salt movement and corn growth in agricultural fields%咸水结冰融水入渗对土壤水盐运移和玉米苗期生长的影响

    Institute of Scientific and Technical Information of China (English)

    车升国; 林治安; 左余宝; 赵秉强

    2012-01-01

    Freshwater is widely, regarded as the most important and fundamental natural resource that is integral to all ecological and societal activities, including food and energy production, industrial development and human health. At the global or even country level, there exists significant spatio-temporal variability in renewable water resources, resulting in severe freshwater shortages in some regions of the world. Underground salt-water deposits could not meet domestic water supply requirements due the generally high salt content even for agricultural irrigation, let alone for domestic consumption. So desalination, which is the separation of water form salt solution for freshwater supply, could be a viable option needing facilitation. Four laboratory irrigation modes were designed in Dezhou Experiment Station of Chinese Academy of Agricultural Sciences. The irrigation modes included control treatment (freshwater irrigation, CK), saline water irrigation (SW), saline ice-melt water irrigation (MI) and saline ice-water irrigation plus wheat straw mulch (MI+SW). The mechanisms of water and salt movement in the soil during saline ice-water melt were studied in a soil column experiment. Corn was planted in the soil column after seven days and the effects of saline ice-melt water irrigation on soil water content, salt movement and corn growth determined. The results showed soil water content in the 0~40 cm layer under saline water irrigation treatment was lower and that in the deeper soil layer higher compared to that under freshwater irrigation treatment. Compared with freshwater irrigation treatment, saline ice-melt water irrigation treatment also showed a similar trend; where there was lower water content in surface soil and higher water content in deep soil layers. However, wheat straw mulching increased soil profile water content. Soil salinity under freshwater irrigation treatment was very low in the 0~60 cm soil later, less than 0.2 dS·m-1. In the 60~80 cm soil

  20. Plastic Melt Waste Compactor Flight Demonstrator Payload (PFDP) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The PMWC Flight Demonstrator Payload is a trash dewatering and volume reduction system that uses heat melt compaction to remove nearly 100% of water from trash while...

  1. Geometric and oceanographic controls on melting beneath Pine Island Glacier

    National Research Council Canada - National Science Library

    De Rydt, J; Holland, P. R; Dutrieux, P; Jenkins, A

    2014-01-01

    .... As a result, a large ocean cavity has formed behind the ridge, strongly controlling the ocean circulation beneath the ice shelf and modulating the ocean water properties that cause ice melting...

  2. Water wafers: structure and melting of a hydrate inclusion compound of a neutral Pt(IV) complex with 1-methylcytosinato ligands

    Science.gov (United States)

    Randaccio, Lucio; Zangrando, Ennio; Cesàro, Attilio; Holthenrich, Dagmar; Lippert', Bernhard

    1998-01-01

    The characterization by X-ray analysis of the trans, trans, trans-[bis(1-methylcytosinate, N4)bis(ammine)bis(hydroxo)platinum(IV)] octahydrate complex (I) reveals an unexpected crystal packing. The neutral complex molecule is hosted by layers, totally built up by water molecules which do not exhibit a direct coordination to metal ions. These corrugated layers are made by puckered eight- and planar four-membered rings of water molecules, held together by hydrogen bonds with an ordered proton arrangement.

  3. Development of design Criteria for ITER In-vessel Components

    Energy Technology Data Exchange (ETDEWEB)

    Sannazzaro, G., E-mail: Giulio.Sannazzaro@iter.org [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Barabash, V.; Kang, S.C. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Fernandez, E. [Fusion For Energy, Josep Pla, 2, Torres Diagonal Mar B3, 08019 Barcelona (Spain); Kalinin, G.; Obushev, A. [The Research and Development Institute of Power Engineering, P.O. Box 788, Moscow (Russian Federation); Martínez, V.J.; Vázquez, I. [IDESA, Parque Científico Tecnológico, C/Profesor Potter 105, 33203 Gijón (Spain); Fernández, F.; Guirao, J. [NATEC, C/Marqués de San Esteban 52 Entlo, 33209 Gijón (Spain)

    2013-10-15

    Absrtract: The components located inside the ITER vacuum chamber (in-vessel components – IC), due to their specific nature and the environments they are exposed to (neutron radiation, high heat fluxes, electromagnetic forces, etc.), have specific design criteria which are, in this paper, referred as Structural Design Criteria for In-vessel Components (SDC-IC). The development of these criteria started in the very early phase of the ITER design and followed closely the criteria of the RCC-MR code. Specific rules to include the effect of neutron irradiation were implemented. In 2008 the need of an update of the SDC-IC was identified to add missing specifications, to implement improvements, to modernise rules including recent evolutions in international codes and regulations (i.e. PED). Collaboration was set up between ITER Organization (IO), European (EUDA) and Russian Federation (RFDA) Domestic Agencies to generate a new version of SDC-IC. A Peer Review Group (PRG) composed by members of the ITER Organization and all ITER Domestic Agencies and code experts was set-up to review the proposed modifications, to provide comments, contributions and recommendations.

  4. Thermodynamics of Oligonucleotide Duplex Melting

    Science.gov (United States)

    Schreiber-Gosche, Sherrie; Edwards, Robert A.

    2009-01-01

    Melting temperatures of oligonucleotides are useful for a number of molecular biology applications, such as the polymerase chain reaction (PCR). Although melting temperatures are often calculated with simplistic empirical equations, application of thermodynamics provides more accurate melting temperatures and an opportunity for students to apply…

  5. Melting of polydisperse hard disks

    NARCIS (Netherlands)

    Pronk, S.; Frenkel, D.

    2004-01-01

    The melting of a polydisperse hard-disk system is investigated by Monte Carlo simulations in the semigrand canonical ensemble. This is done in the context of possible continuous melting by a dislocation-unbinding mechanism, as an extension of the two-dimensional hard-disk melting problem. We find

  6. Melting of polydisperse hard disks

    NARCIS (Netherlands)

    Pronk, S.; Frenkel, D.

    2004-01-01

    The melting of a polydisperse hard-disk system is investigated by Monte Carlo simulations in the semigrand canonical ensemble. This is done in the context of possible continuous melting by a dislocation-unbinding mechanism, as an extension of the two-dimensional hard-disk melting problem. We find th

  7. Surface melt and ponding of Larsen C Ice Shelf and the impact of foehn winds

    NARCIS (Netherlands)

    Luckman, Adrian; Elvidge, Andrew; Jansen, Daniela; Kulessa, Bernd; Kuipers Munneke, Peter|info:eu-repo/dai/nl/304831891; King, John; Barrand, Nicholas

    2014-01-01

    A common precursor to ice shelf disintegration, most notably that of Larsen B Ice Shelf, is unusually intense or prolonged surface melt and the presence of surface standing water. However, there has been little research into detailed patterns of melt on ice shelves or the nature of summer melt

  8. Experimental Results on Pouring and Underwater Liquid Melt Spreading and Energetic Melt-coolant Interaction

    OpenAIRE

    Konovalenko, Alexander; Karbojian, Aram; Kudinov, Pavel

    2012-01-01

    In a hypothetical light water reactor (LWR) core-melt accident with corium release from the reactor  vessel,  the  ultimate  containment  integrity  is  contingent  on  coolability  of  the decay-heated core debris. Pouring of melt into a pool of water located in the reactor cavity is considered in several designs of existing and new LWRs  as a part of severe accident (SA) management strategies. At certain conditions of melt release into the pool (e.g. large ratio of the  vessel  breach  size...

  9. Estimation of the lifetime of resin insulators against baking temperature for JT-60SA in-vessel coils

    Energy Technology Data Exchange (ETDEWEB)

    Sukegawa, Atsuhiko M., E-mail: morioka.atsuhiko@jaea.go.jp; Murakami, Haruyuki; Matsunaga, Go; Sakurai, Shinji; Takechi, Manabu; Yoshida, Kiyoshi; Ikeda, Yoshitaka

    2015-10-15

    Highlights: • The lifetime of resin insulators at about 200 °C was estimated. • We make use of the Arrhenius plot by the Weibull analysis for the estimation. • A suitable temperatures for the in-vessel coils were discussed. - Abstract: In the present study, the thermal endurance of epoxy-based, bismaleimides, and cyanate ester resins for the current design of the in-vessel coils was measured by performing acceleration tests to assess their insulation properties using the thermal endurance defined by the International Electrotechnical Commission (IEC-60216 Part1–Part 6) for a minimum of 5,000 h in the 180–240 °C temperature range. It was found that none of the resin insulators could tolerate the baking conditions of 40,000 h at ∼200 °C in the JT-60SA vacuum vessel. Therefore, the design of the in-vessel coils, including the error field correction coils (EFCC), was changed from the type without water cooling to with water cooling on JT-60SA.

  10. Development of in situ diagnostics and tools handled by a light multipurpose carrier for tokamak in-vessel interventions

    Energy Technology Data Exchange (ETDEWEB)

    Houry, M., E-mail: michael.houry@cea.f [CEA, Institut de Recherche sur la Fusion par confinement Magnetique, F-13108 Saint-Paul-Lez-Durance (France); Bayetti, P. [CEA, Institut de Recherche sur la Fusion par confinement Magnetique, F-13108 Saint-Paul-Lez-Durance (France); Keller, D. [CEA, LIST, Service de Robotique Interactive, 18 route du Panorama, BP6, F-92265 Fontenay-aux-Roses (France); Gargiulo, L.; Bruno, V.; Hatchressian, J.C.; Hernandez, C.; Martins, J.P. [CEA, Institut de Recherche sur la Fusion par confinement Magnetique, F-13108 Saint-Paul-Lez-Durance (France); Measson, Y.; Perrot, Y.; Russotto, F.X. [CEA, LIST, Service de Robotique Interactive, 18 route du Panorama, BP6, F-92265 Fontenay-aux-Roses (France)

    2010-12-15

    A multipurpose carrier prototype called Articulated Inspection Arm (AIA) has been developed and demonstrated by CEA laboratories to operate embedded diagnostics or tools into a tokamak vacuum-vessel. The AIA robot with a vision diagnostic has been deployed inside the vacuum-vessel of Tore Supra tokamak and has realized closed inspections of plasma facing components' under relevant conditions (high vacuum and temperature). CEA is engaged in development of interchangeable diagnostics or tools to be plugged on the front head of the arm. This covers applications such as in-vessel inspections, water leak localization, Plasma Facing Components (PFCs) characterization and treatment. This paper describes R and D activities performed in CEA laboratories to develop diagnostics and tools for in-vessel interventions. The AIA multipurpose carrier to carry such devices is also presented. The first demonstration of a quick intervention for plasma facing components performed in the Tore Supra Facility is described as well.

  11. Improvement in the water solubility of drugs with a solid dispersion system by spray drying and hot-melt extrusion with using the amphiphilic polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer and d-mannitol.

    Science.gov (United States)

    Ogawa, Noriko; Hiramatsu, Tomoki; Suzuki, Ryohei; Okamoto, Ryohei; Shibagaki, Kohei; Fujita, Kosuke; Takahashi, Chisato; Kawashima, Yoshiaki; Yamamoto, Hiromitsu

    2017-09-08

    The aim of this study was to prepare and characterize solid dispersion particles with a novel amphiphilic polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer, as a water-soluble carrier. Solid dispersion particles were prepared by hot-melt extrusion and spray drying. Indomethacin (IMC) was used as a model comprising drugs with low solubility in water and d-mannitol (MAN) was used as an excipient. The physicochemical properties of prepared particles were characterized by scanning electron microscopy, thermal analysis, powder X-ray diffraction (PXRD) analysis, FTIR spectra analysis, and drug release studies. Stability studies were also conducted under stress conditions at 40°C, 75% relative humidity. We found that dissolution behavior of the original drug crystal could be improved by solid dispersion with the polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer. The PXRD pattern and thermal analysis indicated that the solid dispersion prepared with the polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer and IMC was in an amorphous state. FTIR spectra analysis indicated that the interaction manner between the polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer and IMC may differ with the preparation method and formulation of solid dispersions. Stability studies proved that the amorphous state of IMC in solid dispersion particles was preserved under stress conditions for more than two weeks. Copyright © 2017. Published by Elsevier B.V.

  12. Hydrothermal alteration of impact melt sheets with implications for Mars

    Science.gov (United States)

    Newsom, H. E.

    1980-01-01

    A model of the interaction of water with an impact melt sheet is constructed to explain the presence of hydrothermal alteration, fluid flow channels, and the redistribution of volatile elements in terrestrial melt sheets. A calculation of the amount of water vaporized beneath a melt sheet with a large fraction of melt results in a maximum total steam/melt sheet ratio of 23% by weight. The model also applies to Martian impact melt sheets, which have a total volume greater than a global layer 60 m thick. Hydrothermal circulation of steam in Martian melt sheets may have produced iron-rich alteration clays, ferric hydroxides, and near-surface accumulations of salts. The ability of vapor-dominated hydrothermal systems to concentrate sulfate relative to chloride is consistent with the high sulfate to chloride ratio found in the Martian soil by the Viking landers. A major fraction of the Martian soil may consist of the erosion products of hydrothermally altered impact melt sheets.

  13. CFD Modeling of Melt Spreading on the Reactor Cavity Floor

    Energy Technology Data Exchange (ETDEWEB)

    Yeon, Wan Sik; Bang, Kwang Hyun [Korea Maritime University, Busan (Korea, Republic of); Cho, Young Jo; Lee, Jae Gon [Korea Hydro and Nuclear Power Co., Daejeon (Korea, Republic of)

    2010-05-15

    In the very unlikely event of a severe reactor accident involving core melt and reactor pressure vessel failure, it is important to provide an accident management strategy that would allow the molten core material to cool down, resolidify and bring the core debris to a stable coolable state for Light Water Reactors (LWRs). One approach to achieve a stable coolable state is to quench the core melt after its relocation from the reactor pressure vessel into the reactor cavity. This approach typically requires a large cavity floor area on which a large amount of core melt spreads well and forms a shallow melt thickness for small thermal resistance across the melt pool. Spreading of high temperature (approx3000 K), low superheat (approx200 K) core melt over a wide cavity floor has been a key question to the success of the ex-vessel core coolability and it has brought a number of experimental work (CORINE, ECOKATS, VULCANO) and analytical work (CORFLOW, MELTSPREAD, THEMA). These computational models are currently able to predict well the spreading of stimulant materials but yet have shown a limitation for prototypic core melt of UO{sub 2}+ZrO{sub 2} mixture. A computational model for the melt spreading requires a multiphase treatment of liquid melt, solidified melt, and air. Also solidification and thermal radiation physics should be included. The present work uses ANSYS-CFX code to simulate core melt spreading on the reactor cavity. The CFX code is a general-purpose multiphase code and the present work is focused on exploring the code's capability to model melt spreading problem in a step by step approach

  14. Possible in-vessel corium progression way in the Unit 1 of Fukushima Dai-ichi nuclear power plant using a phenomenological analysis

    Directory of Open Access Journals (Sweden)

    Payot Frédéric

    2015-01-01

    Full Text Available In the field of severe accident, the description of corium progression events is mainly carried out by using integral calculation codes. However, these tools are usually based on bounding assumptions because of high complexity of phenomena. The limitations associated with bounding situations ([J.M. Seiler, B. Tourniaire, A phenomenological analysis of melt progression in the lower head of a pressurized water reactor, Nucl. Eng. Des. 268, 87 (2014] e.g. steady state situations and instantaneous whole core relocation in the lower head led CEA to develop an alternative approach in order to improve the phenomenological description of melt progression. The methodology used to describe the corium progression was designed to cover the accidental situations from the core meltdown to the molten core concrete interaction. This phenomenological approach is based on available data (including learnings from TMI2, on physical models and knowledge about the corium behavior. It provides emerging trends and best estimated intermediate situations. As different phenomena are unknown, but strongly coupled, uncertainties at large scale for the reactor application must be taken into account. Furthermore, the analysis is complicated by the fact that these configurations are most probably three dimensional, all the more so because 3D effects are expected to have significant consequences for the corium progression and the resulting vessel failure. Such an analysis of the in-vessel melt progression was carried out for the Unit 1 of the Fukushima Dai-ichi nuclear power plant. The core uncovering kinetics governs the core degradation and impacts the appearance of the first molten corium inside the core. The initial conditions used to carry out this analysis are based on available results derived from codes like MELCOR calculation code [R. Ganntt, D. Kalinich, J. Cardoni, J. Phillips, A. Goldmann, S. Pickering, M. Francis, K. Robb, L. Ott, D. Wang, C. Smith, S. St. Germain

  15. In-Vessel Retention Technology Development and Use for Advanced PWR Designs in the USA and Korea

    Energy Technology Data Exchange (ETDEWEB)

    T.G. Theofanous; S.J. Oh; J.H. Scobel

    2004-05-18

    In-Vessel Retention (IVR) of molten core debris by means of external reactor vessel flooding is a cornerstone of severe accident management for Westinghouse's AP600 (advanced passive light water reactor) design. The case for its effectiveness (made in previous work by the PI) has been thoroughly documented, reviewed as part of the licensing certification, and accepted by the US Nuclear Regulatory Commission. A successful IVR would terminate a severe accident, passively, with the core in a stable, coolable configuration (within the lower head), thus avoiding the largely uncertain accident evolution with the molten debris on the containment floor. This passive plant design has been upgraded by Westinghouse to the AP1000, a 1000 MWe plant very similar to the AP600. The severe accident management approach is very similar too, including In-Vessel Retention as the cornerstone feature, and initial evaluations indicated that this would be feasible at the higher power as well. A similar strategy is adopted in Korea for the APR1400 plant. The overall goal of this project is to provide experimental data and develop the necessary basic understanding so as to allow the robust extension of the AP600 In-Vessel Retention strategy for severe accident management to higher power reactors, and in particular, to the AP1000 advanced passive design.

  16. Comparison of a novel spray congealing procedure with emulsion-based methods for the micro-encapsulation of water-soluble drugs in low melting point triglycerides.

    Science.gov (United States)

    McCarron, Paul A; Donnelly, Ryan F; Al-Kassas, Rasil

    2008-09-01

    The particle size characteristics and encapsulation efficiency of microparticles prepared using triglyceride materials and loaded with two model water-soluble drugs were evaluated. Two emulsification procedures based on o/w and w/o/w methodologies were compared to a novel spray congealing procedure. After extensive modification of both emulsification methods, encapsulation efficiencies of 13.04% tetracycline HCl and 11.27% lidocaine HCl were achievable in a Witepsol-based microparticle. This compares to much improved encapsulation efficiencies close to 100% for the spray congealing method, which was shown to produce spherical particles of approximately 58 microm. Drug release studies from a Witepsol formulation loaded with lidocaine HCl showed a temperature-dependent release mechanism, which displayed diffusion-controlled kinetics at temperatures approximately 25 degrees C, but exhibited almost immediate release when triggered using temperatures close to that of skin. Therefore, such a system may find application in topical semi-solid formulations, where a temperature-induced burst release is preferred.

  17. Glacier melt on the Third Pole

    Science.gov (United States)

    Yao, T.

    2015-12-01

    With an average elevation above 4,000 metres, the Third Pole (TP) is a unique region with many high mountains centered on the Tibetan Plateau stretching over 5 million square kilometers. Major environmental changes are taking place on the TP characterized by complex interactions of atmospheric, cryospheric, hydrological, geological and environmental processes. These processes are critical for the well-being of the three billion people inhabiting the plateau and the surrounding regions. Glacier melt is one of the most significant environmental changes observed on the TP. Over the past decade, most of the glaciers on the TP have undergone considerable melt. The Third Pole Environment (TPE) has focused on the causes of the glacier melt by conducting large-scale ground in-situ observation and monitoring, analyzing satellite images and remote sensing data, and applying numerical modeling to environmental research on the TP. The studies of long-term record of water stable isotopes in precipitation and ice core throughout the TP have revealed different features with regions, thus proposing significant influence of atmospheric circulations on spatial precipitation pattern over the TP. Validation of the result by isotope-equipped general circulation models confirms the spatial distribution of different atmospheric circulation dominances on the TP, with northern part dominated by the westerlies, southern part by the summer monsoon, and central part featuring the influences of both circulation systems. Such unique circulation patterns also bear directly on the status of glaciers and lakes over the TP and its surroundings. The studies therefore found the largest glacier melt in the monsoon-dominated southern part, moderate melt in the central part of transition, and the least melt, or even slight advance in the westerlies-dominated northern TP. It is clear that some mountains on the TP are undergoing rapid melt and the consequence of without ice and snow will be very soon. The

  18. Dynamic Melting of Freezing Droplets on Ultraslippery Superhydrophobic Surfaces.

    Science.gov (United States)

    Chu, Fuqiang; Wu, Xiaomin; Wang, Lingli

    2017-03-08

    Condensed droplet freezing and freezing droplet melting phenomena on the prepared ultraslippery superhydrophobic surface were observed and discussed in this study. Although the freezing delay performance of the surface is common, the melting of the freezing droplets on the surface is quite interesting. Three self-propelled movements of the melting droplets (ice- water mixture) were found including the droplet rotating, the droplet jumping, and the droplet sliding. The melting droplet rotating, which means that the melting droplet rotates spontaneously on the superhydrophobic surface like a spinning top, is first reported in this study and may have some potential applications in various engineering fields. The melting droplet jumping and sliding are similar to those occurring during condensation but have larger size scale and motion scale, as the melting droplets have extra-large specific surface area with much more surface energy available. These self-propelled movements make all the melting droplets on the superhydrophobic surface dynamic, easily removed, which may be promising for the anti-icing/frosting applications.

  19. Melting of Ice under Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Schwegler, E; Sharma, M; Gygi, F; Galli, G

    2008-07-31

    The melting of ice under pressure is investigated with a series of first principles molecular dynamics simulations. In particular, a two-phase approach is used to determine the melting temperature of the ice-VII phase in the range of 10 to 50 GPa. Our computed melting temperatures are consistent with existing diamond anvil cell experiments. We find that for pressures between 10 to 40 GPa, ice melts as a molecular solid. For pressures above {approx}45 GPa there is a sharp increase in the slope of the melting curve due to the presence of molecular dissociation and proton diffusion in the solid, prior to melting. The onset of significant proton diffusion in ice-VII as a function of increasing temperature is found to be gradual and bears many similarities to that of a type-II superionic solid.

  20. Trace element mass balance in hydrous adiabatic mantle melting: The Hydrous Adiabatic Mantle Melting Simulator version 1 (HAMMS1)

    Science.gov (United States)

    Kimura, Jun-Ichi; Kawabata, Hiroshi

    2014-06-01

    numerical mass balance calculation model for the adiabatic melting of a dry to hydrous peridotite has been programmed in order to simulate the trace element compositions of basalts from mid-ocean ridges, back-arc basins, ocean islands, and large igneous provinces. The Excel spreadsheet-based calculator, Hydrous Adiabatic Mantle Melting Simulator version 1 (HAMMS1) uses (1) a thermodynamic model of fractional adiabatic melting of mantle peridotite, with (2) the parameterized experimental melting relationships of primitive to depleted mantle sources in terms of pressure, temperature, water content, and degree of partial melting. The trace element composition of the model basalt is calculated from the accumulated incremental melts within the adiabatic melting regime, with consideration for source depletion. The mineralogic mode in the primitive to depleted source mantle in adiabat is calculated using parameterized experimental results. Partition coefficients of the trace elements of mantle minerals are parameterized to melt temperature mostly from a lattice strain model and are tested using the latest compilations of experimental results. The parameters that control the composition of trace elements in the model are as follows: (1) mantle potential temperature, (2) water content in the source mantle, (3) depth of termination of adiabatic melting, and (4) source mantle depletion. HAMMS1 enables us to obtain the above controlling parameters using Monte Carlo fitting calculations and by comparing the calculated basalt compositions to primary basalt compositions. Additionally, HAMMS1 compares melting parameters with a major element model, which uses petrogenetic grids formulated from experimental results, thus providing better constraints on the source conditions.

  1. Densification and grain coarsening of melting snow

    Institute of Scientific and Technical Information of China (English)

    周石硚; 中尾正义; 桥本重将; 坂井亚规子; 成田英器; 石川信敬

    2003-01-01

    A field work was conducted at Moshiri in Japan.The work included intensive snow pit work, taking snow grain photos, recording snow and air temperatures, as well as measuring snow water content.By treating the snow as a viscous fluid, it is found that the snow compactive viscosity decreases as the density increases, which is opposite to the relation for dry snow.Based on the measurements of snow grain size, it is shown that, similar to the water-saturated snow, the frequency distributions of grain size at different times almost have the same shape.This reveals that the water-unsaturated melting snow holds the same grain-coarsening behavior as the water-saturated snow does.It is also shown that the water-unsaturated melting snow coarsens much more slowly than the water-saturated snow.The C value, which is the viscosity when the snow density is zero, is related to the mean grain size and found to decrease with increasing grain size.The decreasing rate of C value increases with decreasing grain-coarsening rate.

  2. MULTIPLE MELTING IN NYLON 1010

    Institute of Scientific and Technical Information of China (English)

    FU Shuren; CHEN Taoyung

    1983-01-01

    Multiple melting behavior of nylon 1010 has been investigated by using DSC instrument. Effects of partial scanning, partial scanning and annealing, heating rate, cooling rate and stepwise annealing on the melting curve were studied. Experimental results indicate that the sample undergoes a process of continuous melting and recrystallization during DSC scanning. Nylon 1010 contains a distribution of crystallites of different degrees of perfection which is strongly dependent on its previous thermal history. From the structural reorganization point of view, the origin of double and multiple peaks of the melting curve is explained.

  3. NUMERICAL SIMULATION OF INDUCTION SKULL MELTING PROCESS FOR TITANIUM-ALUMINIUM BASE ALLOY

    Institute of Scientific and Technical Information of China (English)

    Z.Y. Chen; L.J. Xu; F.T. Kong; Q. Shu; Y.Y. Chen

    2004-01-01

    The mathematics model for temperature field of water-cooling copper crucible induction skull melting process was established. The program for simulating temperature field of melting process was developed with finite element method. The temperature field of the melting process for Ti-47Al-2Cr-2Nb alloy was calculated. During melting period, the temperature is raised gradually along radius augmentation direction. The elements of the charge near the crucible wall are molten first. The center elements of the charge are molten last. The melting time of the center element is just that of all the charge melting. The melting time of Ti-47Al-2Cr-2Nb alloy is 15min. In which, the charge was heated by low power 80kW for 9min and by high power 300kW for 6min. When melting Ti-47Al-2Cr-2Nb alloy,the loading power is nearly direct proportion to melt temperature. Increasing loading power may raise melt temperature. The best melting power of Ti-47Al-2Cr-2Nb alloy is 305-310kW. This is identical with the melting test and has guidance sense to the melting process of actual titanium alloy.

  4. Floating Ice-Algal Aggregates below melting Arctic Sea Ice

    OpenAIRE

    Philipp Assmy; Jens K. Ehn; Mar Fernández-Méndez; Haakon Hop; Christian Katlein; Arild Sundfjord; Katrin Bluhm; Malin Daase; Anja Engel; Agneta Fransson; Granskog, Mats A.; Hudson, Stephen R.; Svein Kristiansen; Marcel Nicolaus; Ilka Peeken

    2013-01-01

    During two consecutive cruises to the Eastern Central Arctic in late summer 2012, we observed floating algal aggregates in the melt-water layer below and between melting ice floes of first-year pack ice. The macroscopic (1 – 15 cm in diameter) aggregates had a mucous consistency and were dominated by typical ice-associated pennate diatoms embedded within the mucous matrix. Aggregates maintained buoyancy and accumulated just above a strong pycnocline that separated meltwater and seawater layer...

  5. Spatial and Temporal Observations of Summer Ice Melt Using ERS-1 SAR Imagery

    Science.gov (United States)

    Holt, B.; Martin, S.

    1995-01-01

    The complete understanding of the heat and mass balance of the polar oceans includes the melting of sea ice in the summer and the reinjection of fresh water into the upper ocean. This study examines the spatial and temporal character of ice melt. Using ERS-1 SAR imagery, the development of small floes formed by melt and deforma- tion, and changes in the fraction of open water and floes is examined.

  6. Spatial and Temporal Observations of Summer Ice Melt Using ERS-1 SAR Imagery

    Science.gov (United States)

    Holt, B.; Martin, S.

    1995-01-01

    The complete understanding of the heat and mass balance of the polar oceans includes the melting of sea ice in the summer and the reinjection of fresh water into the upper ocean. This study examines the spatial and temporal character of ice melt. Using ERS-1 SAR imagery, the development of small floes formed by melt and deforma- tion, and changes in the fraction of open water and floes is examined.

  7. Melt pool dynamics during selective electron beam melting

    Science.gov (United States)

    Scharowsky, T.; Osmanlic, F.; Singer, R. F.; Körner, C.

    2014-03-01

    Electron beam melting is a promising additive manufacturing technique for metal parts. Nevertheless, the process is still poorly understood making further investigations indispensable to allow a prediction of the part's quality. To improve the understanding of the process especially the beam powder interaction, process observation at the relevant time scale is necessary. Due to the difficult accessibility of the building area, the high temperatures, radiation and the very high scanning speeds during the melting process the observation requires an augmented effort in the observation equipment. A high speed camera in combination with an illumination laser, band pass filter and mirror system is suitable for the observation of the electron beam melting process. The equipment allows to observe the melting process with a high spatial and temporal resolution. In this paper the adjustment of the equipment and results of the lifetime and the oscillation frequencies of the melt pool for a simple geometry are presented.

  8. Review of SFR In-Vessel HCDA Source Terms

    Energy Technology Data Exchange (ETDEWEB)

    Suk, S. D.; Ha, K. S. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-10-15

    An effort has been made in this study to search for and review the literatures on the studies of the phenomena related to the release of radionuclides and aerosols to the reactor containment of the sodium fast reactor (SFR) plants ( i.e., in-vessel source term. Review work is focused on the experimental programs to investigate the phenomena related to determining the source terms, with a brief review on supporting analytical models and computer programs. As a result of the severe accidents experienced at TMI and Chernobyl, much work has been done on the energetic CDA bubble source term (also called 'primary' or 'instantaneous' source term) defined as the amount of radioactive material released from the reactor vessel to the containment due to the rapid expansion of fuel or sodium leading to a failure of the vessel head. In this study, the research programs conducted to investigate the CDA (core disruptive accident) bubble behavior in the sodium pool for determining 'primary' or 'instantaneous' source term are introduced. The research programs to investigate the release and transport of fission products(FPs) and aerosols in the reactor containment (i.e., in-containment source term) are not described in this study.

  9. Beyond the Melting Pot Reconsidered.

    Science.gov (United States)

    Anderson, Elijah

    2000-01-01

    Discusses the 1963 book, "Beyond the Melting Pot," which suggested that eventually the problem of different ethnicities in the U.S. would be resolved and society would become one melting pot. Examines how changes in immigration and economic structures have affected the issue, noting the devastating effect of the dominant culture's…

  10. Effect of In-Vessel Retention Strategies under Postulated SGTR Accidents of OPR1000

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Wonjun; Lee, Yongjae; Kim, Sung Joong [Hanyang University, Seoul (Korea, Republic of); Kim, Hwan-Yeol; Park, Rae-Joon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    In this study, MELCOR code was used to simulate the severe accident of the OPR1000. MELCOR code is computer code which enables to simulate the progression of the severe accident for light water reactors. It has been developed by Sandia National Laboratories for plant risk assessment and source term analysis since 1982. According to the probabilistic safety analysis (PSA) Level 1 of OPR1000, typical severe accident scenarios of high probability of a transition to severe accident for OPR1000 were identified as Small Break Loss of Coolant Accident (SBLOCA), Station Black out (SBO), Total Loss of Feed Water (TLOFW), and Steam Generator Tube Rupture. While the first three accidents are expected to result in the generation and transportation of the radioactive nuclides within the containment building as consequence of the core damage and subsequent reactor pressure vessel (RPV) failure, the latter accident scenario may be progressed with possible direct release of the radioactive nuclides to the environment by bypassing the containment building. Thus it is of significance to investigate the SGTR accident with a sophisticated severe accident code. This code can simulate the whole phenomena of a severe accident such as thermal-hydraulic response, core heat-up, oxidation and relocation, and fission product release and transport. Thus many researchers have used MELCOR in severe accident studies. In this study, in-vessel retention strategies were applied for postulated SGTR accidents. Mitigation effect and adverse effect of in-vessel strategies was studied in aspect of RPV failure, fission product release and containment thermal-hydraulic and hydrogen behavior. Base case of SGTR accident and three mitigation cases were simulated using MELCOR code 1.8.6. For each mitigation cases, mitigation effect and adverse effect were investigated. Conclusions can be summarized as follows: (1) RPV failure of SGTR base case occurred at 5.62 hours and fission product of RCS released to

  11. Channelling of Melt Above Plumes and Beneath MORs

    Science.gov (United States)

    Mueller, K.; Schmeling, H.

    2003-12-01

    We investigate melt transportation in partially molten rocks under different stress fields above the head of a mantle plume or beneath a spreading mid-oceanic ridge under hydrous and anhydrous conditions. We model such aggregates with the 2D-FD code FDCON [1] by means of a porous deformable matrix with melt under the influence of a given stress field to clarify the following key questions: Could channeling occur in a matrix containing a random melt distribution under a given stress field? Which orientation does it take? Is it possible to achieve a focusing of melt towards a MOR (dykes)? Does applying simple or pure shear to the matrix result in a difference in the formation and orientation of channels? How does the channel instability evolve during finite simple shear? In a deforming partially molten aggregate, weakening of the solid matrix due to the presence of melt creates an instability in which melt is localized by the following mechanism: regions of initially high melt fraction are areas of low viscosity and pressure, so that melt is drawn into these regions from higher pressure surroundings. This further enhances the melt weakening, producing a self-excited localization mechanism [2]. The channeling developing in models with a random melt distribution of 3.5 +/- 0.5% shows that melt is accumulated preferably in inclined channels. For both, simple as well as pure shear, the growth rate is highest for an orientation parallel to the direction of the maximum compressive stress and proportional to applied stress and the reverse of the Melt Retention Number. This also confirms the theoretical growth rate found by Stevenson [2]. In our isothermal models we found that the influence of water reduces the growth rate, in contrast to non-isothermal models of Hall [3]. Under simple shear melt channels evolve from an irregular melt distribution at angles of 45 degrees to the direction of shear. Upon further straining they rotate out of the orientation of maximum growth

  12. Partial melting of apatite-bearing charnockite, granulite, and diorite: Melt compositions, restite mineralogy, and petrologic implications

    Science.gov (United States)

    Beard, James S.; Lofgren, Gary E.; Sinha, A. Krishna; Tollo, Richard P.

    1994-01-01

    Melting experiments (P = 6.9 kbar, T = 850-950 deg C, NNO is less than fO2 is less than HM) were done on mafic to felsic charnockites, a dioritic gneiss, and a felsic garnet granulite, all common rock types in the Grenville basement of eastern North America. A graphite-bearing granulite gneiss did not melt. Water (H2O(+) = 0.60 to 2.0 wt %) is bound in low-grade, retrograde metamorphic minerals and is consumed during the earliest stages of melting. Most melts are water-undersaturated. Melt compositions range from metaluminous, silicic granodiorite (diorite starting composition) to peraluminous or weakly metaluminous granites (all others). In general, liquids become more feldspathic, less silicic, and less peraluminous and are enriched in FeO, MgO, and TiO2 with increasing temperature. Residual feldspar mineralogy controls the CaO, K2O, and Na2O contents of the partial melts and the behavior of these elements can be used, particularly if the degree of source melting can be ascertained, to infer some aspects of the feldspar mineralogy of the source. K-feldspar, a common restite phase in the charnockite and granulite (but not the diorite) should control the behavior of Ba and, possibly, Eu in these systems and yield signatures of these elements that can distinguish source regions and, in some cases, bulk versus melt assimilation. Apatite, a common restite phase, is enriched in rare earth elements (REE), especially middle REE. Retention of apatite in the restite will result in steep, light REE-enriched patterns for melts derived from the diorite and charnockites.

  13. Fault rheology beyond frictional melting.

    Science.gov (United States)

    Lavallée, Yan; Hirose, Takehiro; Kendrick, Jackie E; Hess, Kai-Uwe; Dingwell, Donald B

    2015-07-28

    During earthquakes, comminution and frictional heating both contribute to the dissipation of stored energy. With sufficient dissipative heating, melting processes can ensue, yielding the production of frictional melts or "pseudotachylytes." It is commonly assumed that the Newtonian viscosities of such melts control subsequent fault slip resistance. Rock melts, however, are viscoelastic bodies, and, at high strain rates, they exhibit evidence of a glass transition. Here, we present the results of high-velocity friction experiments on a well-characterized melt that demonstrate how slip in melt-bearing faults can be governed by brittle fragmentation phenomena encountered at the glass transition. Slip analysis using models that incorporate viscoelastic responses indicates that even in the presence of melt, slip persists in the solid state until sufficient heat is generated to reduce the viscosity and allow remobilization in the liquid state. Where a rock is present next to the melt, we note that wear of the crystalline wall rock by liquid fragmentation and agglutination also contributes to the brittle component of these experimentally generated pseudotachylytes. We conclude that in the case of pseudotachylyte generation during an earthquake, slip even beyond the onset of frictional melting is not controlled merely by viscosity but rather by an interplay of viscoelastic forces around the glass transition, which involves a response in the brittle/solid regime of these rock melts. We warn of the inadequacy of simple Newtonian viscous analyses and call for the application of more realistic rheological interpretation of pseudotachylyte-bearing fault systems in the evaluation and prediction of their slip dynamics.

  14. Calving on tidewater glaciers amplified by submarine frontal melting

    Directory of Open Access Journals (Sweden)

    M. O'Leary

    2012-08-01

    Full Text Available While it has been shown repeatedly that ocean conditions exhibit an important control on the behaviour of grounded tidewater glaciers, modelling studies have focused largely on the effects of basal and surface melting. Here, a finite-element model of stresses near the front of a tidewater glacier is used to investigate the effects of frontal melting on calving, independently of the calving criterion used. Applications of the stress model to idealized scenarios reveal that undercutting of the ice front due to frontal melting can drive calving at up to ten times the mean melt rate. Factors which cause increased frontal melt-driven calving include a strong thermal gradient in the ice, and a concentration of frontal melt at the base of the glacier. These properties are typical of both Arctic and Antarctic tidewater glaciers. The finding that frontal melt near the base is a strong driver of calving leads to the conclusion that water temperatures near the bed of the glacier are critically important to the glacier front, and thus the flow of the glacier. These conclusions are robust against changes in the basal boundary condition and the choice of calving criterion, as well as variations in the glacier size or level of crevassing.

  15. Greenland Ice Sheet surface melt:A review

    Institute of Scientific and Technical Information of China (English)

    Kang Yang; ManChun Li

    2014-01-01

    Surface melt has great impacts on the Greenland Ice Sheet (GrIS) mass balance and thereby has become the focus of significant GrIS research in recent years. The production, transport, and release processes of surface meltwater are the keys to understanding the poten-tial impacts of the GrIS surface melt. These hydrological processes can elucidate the following scientific questions:How much melt-water is produced atop the GrIS? What are the characteristics of the meltwater-formed supraglacial hydrological system? How does the meltwater influence the GrIS motion? The GrIS supraglacial hydrology has a number of key roles and yet continues to be poorly understood or documented. This paper summarizes the current understanding of the GrIS surface melt, emphasizing the three essential supraglacial hydrological processes:(1) meltwater production:surface melt modeling is an important approach to acquire surface melt information, and areas, depths, and volumes of supraglacial lakes extracted from remotely sensed imagery can also provide surface melt information;(2) meltwater transport:the spatial distributions of supraglacial lakes, supraglacial streams, moulins, and crevasses demonstrate the characteristics of the supraglacial hydrological system, revealing the meltwater transport process;and (3) meltwater release:the release of meltwater into the englacial and the subglacial ice sheet has important but undetermined impacts on the GrIS motion. The correlation between surface runoff and the GrIS motion speed is employed to understand these influences.

  16. Calving on tidewater glaciers amplified by submarine frontal melting

    CERN Document Server

    O'Leary, Martin

    2012-01-01

    While it has been shown repeatedly that ocean conditions exhibit an important control on the behaviour of grounded tidewater glaciers, modelling studies have focused largely on the effects of basal and surface melting. Here, a finite-element model of stresses near the front of a tidewater glacier is used to investigate the effects of frontal melting on calving, independently of the calving criterion used. Applications of the stress model to idealized scenarios reveal that undercutting of the ice front due to frontal melting can drive calving at up to ten times the mean melt rate. Factors which cause increased frontal melt-driven calving include a strong thermal gradient in the ice, and a concentration of frontal melt at the base of the glacier. These properties are typical of both Arctic and Antarctic tidewater glaciers. The finding that frontal melt near the base is a strong driver of calving leads to the conclusion that water temperatures near the bed of the glacier are critically important to the glacier f...

  17. Melting the hydrous, subarc mantle: the origin of primitive andesites

    Science.gov (United States)

    Mitchell, Alexandra L.; Grove, Timothy L.

    2015-08-01

    This experimental study is the first comprehensive investigation of the melting behavior of an olivine + orthopyroxene ± spinel—bearing fertile mantle (FM) composition as a function of variable pressure and water content. The fertile composition was enriched with a metasomatic slab component of ≤0.5 % alkalis and investigated from 1135 to 1470 °C at 1.0-2.0 GPa. A depleted lherzolite with 0.4 % alkali addition was also studied from 1225 to 1240 °C at 1.2 GPa. Melts of both compositions were water-undersaturated: fertile lherzolite melts contained 0-6.4 wt% H2O, and depleted lherzolite melts contained ~2.5 wt% H2O. H2O contents of experimental glasses are measured using electron microprobe, secondary ion mass spectrometry, and synchrotron-source reflection Fourier transform infrared spectroscopy, a novel technique for analyzing H2O in petrologic experiments. Using this new dataset in conjunction with results from previous hydrous experimental studies, a thermobarometer and a hygrometer-thermometer are presented to determine the conditions under which primitive lavas were last in equilibration with the mantle. These predictive models are functions of H2O content and pressure, respectively. A predictive melting model is also presented that calculates melt compositions in equilibrium with an olivine + orthopyroxene ± spinel residual assemblage (harzburgite). This model quantitatively predicts the following influences of H2O on mantle lherzolite melting: (1) As melting pressure increases, melt compositions become more olivine-normative, (2) as melting extent increases, melt compositions become depleted in the normative plagioclase component, and (3) as melt H2O content increases, melts become more quartz-normative. Natural high-Mg# [molar Mg/(Mg + Fe2+)], high-MgO basaltic andesite and andesite lavas—or primitive andesites (PAs)—contain high SiO2 contents at mantle-equilibrated Mg#s. Their compositional characteristics cannot be readily explained by melting

  18. Electrical Conductivity of Cryolite Melts

    Science.gov (United States)

    Fellner, P.; Grjotheim, K.; Kvande, H.

    1985-11-01

    This paper proposes an equation for the electrical conductivity of multicomponent cryolite-based mixtures. The equation is based on a physical model which assumes that the conductivity is proportional to the number density of the effective electric charges in the melt. The various authors in the available literature show a great discrepancy in conductivity data of cryolite-based melts. The equation based on the physical model enables determination of which set of data is preferable. Special consideration in this respect is given to the influence of magnesium flouride and lithium flouride additions to the melt.

  19. Modeling the elution of organic chemicals from a melting homogeneous snow pack.

    Science.gov (United States)

    Meyer, Torsten; Wania, Frank

    2011-06-01

    Organic chemicals are often released in peak concentrations from melting snow packs. A simple, mechanistic snowmelt model was developed to simulate and predict the elution of organic substances from melting, homogeneous snow, as influenced by chemical properties and snow pack characteristics. The model calculates stepwise the chemical transport along with the melt water flow in a multi-layered snow pack, based on chemical equilibrium partitioning between the individual bulk snow phases. The model succeeds in reproducing the elution behavior of several organic contaminants observed in previously conducted cold room experiments. The model aided in identifying four different types of enrichment of organic substances during snowmelt. Water soluble substances experience peak releases early during a melt period (type 1), whereas chemicals that strongly sorb to particulate matter (PM) or snow grain surfaces elute at the end of melting (type 2). Substances that are somewhat water soluble and at the same time have a high affinity for snow grain surfaces may exhibit increasing concentrations in the melt water (type 3). Finally, elution sequences involving peak loads both at the beginning and the end of melting are simulated for chemicals that are partially dissolved in the aqueous melt water phase and partially sorbed to PM (type 4). The extent of type 1 enrichment mainly depends on the snow depth, whereby deeper snow generates more pronounced concentration peaks. PM influences the elution behavior of organic chemicals strongly because of the very large natural variability in the type and amount of particles present in snow. Urban and road-side snow rich in PM can generate type 2 concentration peaks at the end of the melt period for even relatively water soluble substances. From a clean, melting snow pack typical for remote regions, even fairly hydrophobic chemicals can be released in type 1 mode while being almost completely dissolved in the aqueous melt water phase. The

  20. Geometry of the melting interface in cylindrical metal rods under microgravity conditions

    Science.gov (United States)

    Ward, Nicolas R.; Steinberg, Ted A.

    2007-05-01

    The melting interface geometries present within cylindrical iron rods in microgravity are examined. Melting samples are quenched in microgravity by immersion in a water bath. Samples are sectioned on multiple planes and photo microscopy analysis is used to determine the shape of the melting interface on each plane. Images from multiple cross-sections are assembled to produce a three-dimensional representation of the melting interface present in microgravity. Iron rods are shown to have an asymmetric, convex melting interface in microgravity, with a significantly different (increased) heat transfer area compared to the planar normal-gravity case. The change in surface area of the melting interface between normal gravity and microgravity is shown to provide excellent agreement with the observed change in melting rate, as predicted by simple one-dimensional heat transfer analysis. To cite this article: N.R. Ward, T.A. Steinberg, C. R. Mecanique 335 (2007).

  1. Effects of volatiles on melt production and reactive flow in the mantle

    CERN Document Server

    Keller, Tobias

    2015-01-01

    Magmatism in the Earth interior has a significant impact on its dynamic, thermal and compositional evolution. Experimental studies of petrology of mantle melting find that small concentrations of water and carbon dioxide have a significant effect on the solidus temperature and distribution of melting in the upper mantle. However, it has remained unclear what effect small fractions of deep, volatile-rich melts have on melting and melt transport in the shallow asthenosphere. We present a method to simulate the thermochemical evolution of the upper mantle in the presence of volatiles. The method is based on a novel, thermodynamically consistent framework for reactive, disequilibrium, multi-component melting/crystallisation. This is coupled with a system of equations representing conservation of mass, momentum, and energy for a partially molten grain aggregate. Application of this method to upwelling-column models demonstrates that it captures leading-order features of hydrated and carbonated peridotite melting. ...

  2. Inorganic carbon dynamics of melt pond-covered first year sea ice in the Canadian Arctic

    Directory of Open Access Journals (Sweden)

    N.-X. Geilfus

    2014-05-01

    Full Text Available Melt pond formation is a common feature of the spring and summer Arctic sea ice. However, the role of the melt ponds formation and the impact of the sea ice melt on both the direction and size of CO2 flux between air and sea is still unknown. Here we describe the CO2-carbonate chemistry of melting sea ice, melt ponds and the underlying seawater associated with measurement of CO2 fluxes across first year landfast sea ice in the Resolute Passage, Nunavut, in June 2012. Early in the melt season, the increase of the ice temperature and the subsequent decrease of the bulk ice salinity promote a strong decrease of the total alkalinity (TA, total dissolved inorganic carbon (TCO2 and partial pressure of CO2 (pCO2 within the bulk sea ice and the brine. Later on, melt pond formation affects both the bulk sea ice and the brine system. As melt ponds are formed from melted snow the in situ melt pond pCO2 is low (36 μatm. The percolation of this low pCO2 melt water into the sea ice matrix dilutes the brine resulting in a strong decrease of the in situ brine pCO2 (to 20 μatm. As melt ponds reach equilibrium with the atmosphere, their in situ pCO2 increase (up to 380 μatm and the percolation of this high concentration pCO2 melt water increase the in situ brine pCO2 within the sea ice matrix. The low in situ pCO2 observed in brine and melt ponds results in CO2 fluxes of −0.04 to −5.4 mmol m–2 d–1. As melt ponds reach equilibrium with the atmosphere, the uptake becomes less significant. However, since melt ponds are continuously supplied by melt water their in situ pCO2 still remains low, promoting a continuous but moderate uptake of CO2 (~ −1mmol m–2 d–1. The potential uptake of atmospheric CO2 by melting sea ice during the Arctic summer has been estimated from 7 to 16 Tg of C ignoring the role of melt ponds. This additional uptake of CO2 associated to Arctic sea ice needs to be further explored and considered in the estimation of the Arctic

  3. Pressure vessel deformation under in-vessel retention condition%熔融物堆内滞留条件下压力容器变形

    Institute of Scientific and Technical Information of China (English)

    温爽; 李铁萍; 李聪新; 高新力

    2016-01-01

    熔融物堆内滞留(In-Vessel Retention, IVR)已经成为第三代反应堆一项关键的严重事故缓解策略,而压力容器外部冷却(External Reactor Vessel Cooling, ERVC)技术则是保证IVR得以成功实施的关键。当发生堆芯熔化时,高温熔融物对压力容器(Reactor Pressure Vessel, RPV)下封头的热冲击会导致RPV壁面和由其构成的外部冷却通道的形状发生变化,使局部传热恶化,进而造成IVR的失效。因此,有必要对IVR条件下RPV壁面的变形进行研究。本文利用有限元软件ANSYS对RPV进行了几何建模、温度场分析和力学场分析。结果表明,在RPV外部实现冷却、内部实现泄压的前提下,壁面变形为13.85−18.75 mm。在1 MPa内压的作用下,高温蠕变会使壁面变形随时间增大,但其增量有限。热膨胀是造成壁面变形的主要因素。%Background: In-vessel retention (IVR) has become an important severe accident mitigation strategy for advanced light water reactor in recent years. The successful implementation of IVR depends on the external reactor vessel cooling (ERVC) technique. In case of core melt, the bottom head of reactor pressure vessel (RPV) becomes deformed due to the thermal impacts of high temperature, and causes the narrowing of external coolant channel which is the gap between pressure vessel outer wall and insulation layer. This phenomenon could lead to local heat transfer deterioration and then causes the failure of IVR.Purpose: The aim of this paper is to analyze the deformation of reactor pressure vessel under IVR condition.Methods: The thermal and mechanical calculations of reactor pressure vessel are performed by using the finite element methods. This work can be divided into two steps. The first step is the evaluation of the thermal field of RPV, and the second step is the calculation of stress and displacement of RPV based on its temperature fields.Results: The result shows that the maximum vertical

  4. Nitrogen Control in VIM Melts

    Science.gov (United States)

    Jablonski, P. D.; Hawk, J. A.

    NETL has developed a design and control philosophy for the addition of nitrogen to austenitic and ferritic steels. The design approach uses CALPHAD as the centerpiece to predict the level to which nitrogen is soluble in both the melt and the solid. Applications of this technique have revealed regions of "exclusion" in which the alloy, while within specification limits of prescribed, cannot be made by conventional melt processing. Furthermore, other investigations have found that substantial retrograde solubility of nitrogen exists, which can become problematic during subsequent melt processing and/or other finishing operations such as welding. Additionally, the CALPHAD method has been used to adjust primary melt conditions. To that end, nitrogen additions have been made using chrome nitride, silicon nitride, high-nitrogen ferrochrome as well as nitrogen gas. The advantages and disadvantages of each approach will be discussed and NETL experience in this area will be summarized with respect to steel structure.

  5. Pressure-induced melting of micellar crystal

    DEFF Research Database (Denmark)

    Mortensen, K.; Schwahn, D.; Janssen, S.

    1993-01-01

    Aqueous solutions of triblock copolymers of poly(ethylene oxide) and poly(propylene oxide) aggregate at elevated temperatures into micelles which for polymer concentrations greater-than-or-equal-to 20% make a hard sphere crystallization to a cubic micellar crystal. Structural studies show...... that pressure improves the solvent quality of water, thus resulting in decomposition of the micelles and consequent melting of the micellar crystal. The combined pressure and temperature dependence reveals that in spite of the apparent increase of order on the 100 angstrom length scale upon increasing...... temperature (decreasing pressure) the overall entropy increases through the inverted micellar crystallization characteristic....

  6. Study on Snow-Melting System around Steel Top of Underground Fire Cistern using Heat Pipe

    Science.gov (United States)

    Nagai, Niro; Nakano, Norimasa; Takeuchi, Masanori; Maekawa, Yoshitaka; Maegawa, Yoshikazu

    This research aims to develop snow melting system around steel top of underground fire cistern by using heat pipe, for realizing quick finding of the steel top under heavy snow fall. Water in a fire cistern installed underground is heated by underground heat source, 10 ~15 °C. The iron top is put on snow melting panel made of reinforced concrete. Heat is transported from water to the snow melting panel by heat pipes, which melts snow on it. The experimental results obtained for two years show that this system can melt the snow around the steel top in winter season preferably. The numerical simulation using only weather data was found to predict temperature variations of the whole system with good agreements to the experimental data. Therefore, this simulation software can be used for designing this snow-melting system.

  7. Laser melting of uranium carbides

    Science.gov (United States)

    Utton, C. A.; De Bruycker, F.; Boboridis, K.; Jardin, R.; Noel, H.; Guéneau, C.; Manara, D.

    2009-03-01

    In the context of the material research aimed at supporting the development of nuclear plants of the fourth Generation, renewed interest has recently arisen in carbide fuels. A profound understanding of the behaviour of nuclear materials in extreme conditions is of prime importance for the analysis of the operation limits of nuclear fuels, and prediction of possible nuclear reactor accidents. In this context, the main goal of the present paper is to demonstrate the feasibility of laser induced melting experiments on stoichiometric uranium carbides; UC, UC1.5 and UC2. Measurements were performed, at temperatures around 3000 K, under a few bars of inert gas in order to minimise vaporisation and oxidation effects, which may occur at these temperatures. Moreover, a recently developed investigation method has been employed, based on in situ analysis of the sample surface reflectivity evolution during melting. Current results, 2781 K for the melting point of UC, 2665 K for the solidus and 2681 K for the liquidus of U2C3, 2754 K for the solidus and 2770 K for the liquidus of UC2, are in fair agreement with early publications where the melting behaviour of uranium carbides was investigated by traditional furnace melting methods. Further information has been obtained in the current research about the non-congruent (solidus-liquidus) melting of certain carbides, which suggest that a solidus-liquidus scheme is followed by higher ratio carbides, possibly even for UC2.

  8. Scaleable Clean Aluminum Melting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Han, Q.; Das, S.K. (Secat, Inc.)

    2008-02-15

    The project entitled 'Scaleable Clean Aluminum Melting Systems' was a Cooperative Research and Development Agreements (CRADAs) between Oak Ridge National Laboratory (ORNL) and Secat Inc. The three-year project was initially funded for the first year and was then canceled due to funding cuts at the DOE headquarters. The limited funds allowed the research team to visit industrial sites and investigate the status of using immersion heaters for aluminum melting applications. Primary concepts were proposed on the design of furnaces using immersion heaters for melting. The proposed project can continue if the funding agency resumes the funds to this research. The objective of this project was to develop and demonstrate integrated, retrofitable technologies for clean melting systems for aluminum in both the Metal Casting and integrated aluminum processing industries. The scope focused on immersion heating coupled with metal circulation systems that provide significant opportunity for energy savings as well as reduction of melt loss in the form of dross. The project aimed at the development and integration of technologies that would enable significant reduction in the energy consumption and environmental impacts of melting aluminum through substitution of immersion heating for the conventional radiant burner methods used in reverberatory furnaces. Specifically, the program would couple heater improvements with furnace modeling that would enable cost-effective retrofits to a range of existing furnace sizes, reducing the economic barrier to application.

  9. Research of Snow-Melt Process on a Heated Platform

    Directory of Open Access Journals (Sweden)

    Vasilyev Gregory P.

    2016-01-01

    Full Text Available The article has shown the results of experimental researches of the snow-melt on a heated platform-near building heat-pump snow-melt platform. The near-building (yard heat pump platforms for snow melt with the area up to 10-15 m2 are a basis of the new ideology of organization of the street cleaning of Moscow from snow in the winter period which supposes the creation in the megalopolis of the «distributed snow-melt system» (DSMS using non-traditional energy sources. The results of natural experimental researches are presented for the estimation of efficiency of application in the climatic conditions of Moscow of heat pumps in the snow-melt systems. The researches were conducted on a model sample of the near-building heat-pump platform which uses the low-potential thermal energy of atmospheric air. The conducted researches have confirmed experimentally in the natural conditions the possibility and efficiency of using of atmospheric air as a source of low-potential thermal energy for evaporation of the snow-melt heat pump systems in the climatic conditions of Moscow. The results of laboratory researches of snow-melt process on a heated horizontal platform are presented. The researches have revealed a considerable dependence of efficiency of the snow-melt process on its piling mode (form-building and the organization of the process of its piling mode (form-building and the organization of the process of its (snow mass heat exchange with the surface of the heated platform. In the process of researches the effect of formation of an «ice dome» under the melting snow mass called by the fact that in case of the thickness of snow loaded on the platform more than 10 cm the water formed from the melting snow while the contact with the heating surface don’t spread on it, but soaks into the snow, wets it due to capillary effect and freezes. The formation of «ice dome» leads to a sharp increase of snow-melt period and decreases the operating

  10. In-vessel ITER tubing failure rates for selected materials and coolants

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, T.D. [Rensselaer Polytechnic Institute, Troy, NY (United States); Cadwallader, L.C. [EG& G Idaho Inc., Idaho Falls, ID (United States)

    1994-03-01

    Several materials have been suggested for fabrication of ITER in-vessel coolant tubing: beryllium, copper, Inconel, niobium, stainless steel, titanium, and vanadium. This report generates failure rates for the materials to identify the best performer from an operational safety and availability perspective. Coolant types considered in this report are helium gas, liquid lithium, liquid sodium, and water. Failure rates for the materials are generated by including the influence of ITER`s operating environment and anticipated tubing failure mechanisms with industrial operating experience failure rates. The analyses define tubing failure mechanisms for ITER as: intergranular attack, flow erosion, helium induced swelling, hydrogen damage, neutron irradiation embrittlement, cyclic fatigue, and thermal cycling. K-factors, multipliers, are developed to model each failure mechanism and are applied to industrial operating experience failure rates to generate tubing failure rates for ITER. The generated failure rates identify the best performer by its expected reliability. With an average leakage failure rate of 3.1e-10(m-hr){sup {minus}1}and an average rupture failure rate of 3.1e-11(m-hr){sup {minus}1}, titanium proved to be the best performer of the tubing materials. The failure rates generated in this report are intended to serve as comparison references for design safety and optimization studies. Actual material testing and analyses are required to validate the failure rates.

  11. Water

    Science.gov (United States)

    ... www.girlshealth.gov/ Home Nutrition Nutrition basics Water Water Did you know that water makes up more ... to drink more water Other drinks How much water do you need? top Water is very important, ...

  12. Structural materials for ITER in-vessel component design

    Science.gov (United States)

    Kalinin, G.; Gauster, W.; Matera, R.; Tavassoli, A.-A. F.; Rowcliffe, A.; Fabritsiev, S.; Kawamura, H.

    1996-10-01

    The materials proposed for ITER in-vessel components have to exhibit adequate performance for the operating lifetime of the reactor or for specified replacement intervals. Estimates show that maximum irradiation dose to be up to 5-7 dpa (for 1 MWa/m 2 in the basic performance phase (BPP)) within a temperature range from 20 to 300°C. Austenitic SS 316LN-ITER Grade was defined as a reference option for the vacuum vessel, blanket, primary wall, pipe lines and divertor body. Conventional technologies and mill products are proposed for blanket, back plate and manifold manufacturing. HIPing is proposed as a reference manufacturing method for the primary wall and blanket and as an option for the divertor body. The existing data show that mechanical properties of HIPed SS are no worse than those of forged 316LN SS. Irradiation will result in property changes. Minimum ductility has been observed after irradiation in an approximate temperature range between 250 and 350°C, for doses of 5-10 dpa. In spite of radiation-induced changes in tensile deformation behavior, the fracture remains ductile. Irradiation assisted corrosion cracking is a concern for high doses of irradiation and at high temperatures. Re-welding is one of the critical issues because of the need to replace failed components. It is also being considered for the replacement of shielding blanket modules by breeding modules after the BPP. Estimates of radiation damage at the locations for re-welding show that the dose will not exceed 0.05 dpa (with He generation of 1 appm) for the manifold and 0.01 dpa (with He generation 0.1 appm) for the back plate for the BPP of ITER operation. Existing experimental data show that these levels will not result in property changes for SS; however, neutron irradiation and He generation promote crack formation in the heat affected zone during welding. Cu based alloys, DS-Cu (Glidcop A125) and PHCu CuCrZr bronze) are proposed as a structural materials for high heat flux

  13. Quantifying melting and mobilistaion of interstitial melts in crystal mushes

    Science.gov (United States)

    Veksler, Ilya; Dobson, Katherine; Hess, Kai-Uwe; Ertel-Ingrisch, Werner; Humphreys, Madeleine

    2015-04-01

    The deformation of crystals mushes and separation of melts and crystals in is critical to understanding the development of physical and chemical heterogeneity in magma chambers and has been invoked as an eruption trigger mechanism. Here we investigate the behaviour of the melt in the well characterised, classic crystal mush system of the Skaergaard intrusion by combining experimental petrology and the non-destructive 3D imaging methods. Starting materials for partial melting experiments were four samples from the upper Middle Zone of the Layered Series. Cylinders, 15 mm in diameter and 20 mm in length, were drilled out of the rock samples, placed in alumina crucibles and held for 5 days in electric furnaces at atmospheric pressure and 1050-1100 °C. Redox conditions set by the CO-CO2 gas mixture were kept close to those of the FMQ buffer. We then use spatially registered 3D x-ray computed tomography images, collected before and after the experiment, to determine the volume and distribution of the crystal framework and interstitial phases, and the volume, distribution and connectivity the interstitial phases that undergo melting and extraction while at elevated temperature. Image analysis has allowed us to quantify these physical changes with high spatial resolution. Our work is a first step towards quantitative understanding of the melt mobilisation and migration processes operating in notionally locked crystal rich magmatic systems.

  14. Methods for Melting Temperature Calculation

    Science.gov (United States)

    Hong, Qi-Jun

    Melting temperature calculation has important applications in the theoretical study of phase diagrams and computational materials screenings. In this thesis, we present two new methods, i.e., the improved Widom's particle insertion method and the small-cell coexistence method, which we developed in order to capture melting temperatures both accurately and quickly. We propose a scheme that drastically improves the efficiency of Widom's particle insertion method by efficiently sampling cavities while calculating the integrals providing the chemical potentials of a physical system. This idea enables us to calculate chemical potentials of liquids directly from first-principles without the help of any reference system, which is necessary in the commonly used thermodynamic integration method. As an example, we apply our scheme, combined with the density functional formalism, to the calculation of the chemical potential of liquid copper. The calculated chemical potential is further used to locate the melting temperature. The calculated results closely agree with experiments. We propose the small-cell coexistence method based on the statistical analysis of small-size coexistence MD simulations. It eliminates the risk of a metastable superheated solid in the fast-heating method, while also significantly reducing the computer cost relative to the traditional large-scale coexistence method. Using empirical potentials, we validate the method and systematically study the finite-size effect on the calculated melting points. The method converges to the exact result in the limit of a large system size. An accuracy within 100 K in melting temperature is usually achieved when the simulation contains more than 100 atoms. DFT examples of Tantalum, high-pressure Sodium, and ionic material NaCl are shown to demonstrate the accuracy and flexibility of the method in its practical applications. The method serves as a promising approach for large-scale automated material screening in which

  15. Determination of Reactive Surface Area of Melt Glass

    Energy Technology Data Exchange (ETDEWEB)

    Bourcier,W.L.; Roberts, S.; Smith, D.K.; Hulsey, S.; Newton,L.; Sawvel, A.; Bruton, C.; Papelis, C.; Um, W.; Russell, C. E.; Chapman,J.

    2000-10-01

    A comprehensive investigation of natural and manmade silicate glasses, and nuclear melt glass was undertaken in order to derive an estimate of glass reactive surface area. Reactive surface area is needed to model release rates of radionuclides from nuclear melt glass in the subsurface. Because of the limited availability of nuclear melt glasses, natural volcanic glass samples were collected which had similar textures and compositions as those of melt glass. A flow-through reactor was used to measure the reactive surface area of the analog glasses in the presence of simplified NTS site ground waters. A measure of the physical surface area of these glasses was obtained using the BET gas-adsorption method. The studies on analog glasses were supplemented by measurement of the surface areas of pieces of actual melt glass using the BET method. The variability of the results reflect the sample preparation and measurement techniques used, as well as textural heterogeneity inherent to these samples. Based on measurements of analog and actual samples, it is recommended that the hydraulic source term calculations employ a range of 0.001 to 0.01 m{sup 2}/g for the reactive surface area of nuclear melt glass.

  16. A metastable liquid melted from a crystalline solid under decompression

    Science.gov (United States)

    Lin, Chuanlong; Smith, Jesse S.; Sinogeikin, Stanislav V.; Kono, Yoshio; Park, Changyong; Kenney-Benson, Curtis; Shen, Guoyin

    2017-01-01

    A metastable liquid may exist under supercooling, sustaining the liquid below the melting point such as supercooled water and silicon. It may also exist as a transient state in solid–solid transitions, as demonstrated in recent studies of colloidal particles and glass-forming metallic systems. One important question is whether a crystalline solid may directly melt into a sustainable metastable liquid. By thermal heating, a crystalline solid will always melt into a liquid above the melting point. Here we report that a high-pressure crystalline phase of bismuth can melt into a metastable liquid below the melting line through a decompression process. The decompression-induced metastable liquid can be maintained for hours in static conditions, and transform to crystalline phases when external perturbations, such as heating and cooling, are applied. It occurs in the pressure–temperature region similar to where the supercooled liquid Bi is observed. Akin to supercooled liquid, the pressure-induced metastable liquid may be more ubiquitous than we thought. PMID:28112152

  17. Design and development of in-vessel viewing periscope for ITER (International Thermonuclear Experimental Reactor)

    Energy Technology Data Exchange (ETDEWEB)

    Obara, Kenjiro; Kakudate, Satoshi; Ito, Akira; Shibanuma, Kiyoshi; Tada, Eisuke [Department of Fusion Engineering Research, Naka Fusion Research Establishment, Japan Atomic Energy Research Institute, Naka , Ibaraki (Japan)

    1999-02-01

    An in-vessel viewing system is essential not only to detect and locate damage of components exposed to plasma, but also to monitor and assist in-vessel maintenance operation. In ITER, the in-vessel viewing system must be capable of operating at high temperature (200degC), under intense gamma radiation (30 kGy/h) and high vacuum or 1 bar inert gas. A periscope-type in-vessel viewing system has been chosen as a reference of the ITER in-vessel viewing system due to its wide viewing capability and durability for sever environments. According to the ITER research and development program, a full-scale radiation hard periscope with a length of 15 m has been successfully developed by the Japan Home Team. The performance tests have been shown sufficient capability at high temperature up to 250degC and radiation resistance over 100 MGy. This report describes the design and R and D results of the ITER in-vessel viewing periscope based on the development of 15-m-length radiation hard periscope. (author)

  18. Design and development of in-vessel viewing periscope for ITER (International Thermonuclear Experimental Reactor)

    Energy Technology Data Exchange (ETDEWEB)

    Obara, Kenjiro; Kakudate, Satoshi; Ito, Akira; Shibanuma, Kiyoshi; Tada, Eisuke [Department of Fusion Engineering Research, Naka Fusion Research Establishment, Japan Atomic Energy Research Institute, Naka , Ibaraki (Japan)

    1999-02-01

    An in-vessel viewing system is essential not only to detect and locate damage of components exposed to plasma, but also to monitor and assist in-vessel maintenance operation. In ITER, the in-vessel viewing system must be capable of operating at high temperature (200degC), under intense gamma radiation (30 kGy/h) and high vacuum or 1 bar inert gas. A periscope-type in-vessel viewing system has been chosen as a reference of the ITER in-vessel viewing system due to its wide viewing capability and durability for sever environments. According to the ITER research and development program, a full-scale radiation hard periscope with a length of 15 m has been successfully developed by the Japan Home Team. The performance tests have been shown sufficient capability at high temperature up to 250degC and radiation resistance over 100 MGy. This report describes the design and R and D results of the ITER in-vessel viewing periscope based on the development of 15-m-length radiation hard periscope. (author)

  19. Hybrid System for Snow Melting and Space Cooling by using Geothermal Energy

    Science.gov (United States)

    Hamada, Yasuhiro; Nakamura, Makoto; Kubota, Hideki

    This paper aims to develop a hybrid system for snow melting and space cooling by using geothermal energy in order to improve the availability factor of the borehole heat exchanger. Based on field experiments, a feasibility evaluation of the system was performed. First, snow melting experiments using geothermal energy were performed and the comparatively good road surface situation was realized. The primary energy reduction rate over 70% was shown in comparison with the conventional snow melting system. Second, regarding a snow melting tank with the hot water piping, it was clarified that the snow melting was possible even in the low temperature water of approximately 9-10°C by using water sprinkling in the tank jointly. Finally, by supplying the space cooling and dehumidification panel with the cold through the borehole heat exchanger in summer, it was shown that the good cooling effect was obtained.

  20. Melting of superheated molecular crystals

    Science.gov (United States)

    Cubeta, Ulyana; Bhattacharya, Deepanjan; Sadtchenko, Vlad

    2017-07-01

    Melting dynamics of micrometer scale, polycrystalline samples of isobutane, dimethyl ether, methyl benzene, and 2-propanol were investigated by fast scanning calorimetry. When films are superheated with rates in excess of 105 K s-1, the melting process follows zero-order, Arrhenius-like kinetics until approximately half of the sample has transformed. Such kinetics strongly imply that melting progresses into the bulk via a rapidly moving solid-liquid interface that is likely to originate at the sample's surface. Remarkably, the apparent activation energies for the phase transformation are large; all exceed the enthalpy of vaporization of each compound and some exceed it by an order of magnitude. In fact, we find that the crystalline melting kinetics are comparable to the kinetics of dielectric α-relaxation in deeply supercooled liquids. Based on these observations, we conclude that the rate of non-isothermal melting for superheated, low-molecular-weight crystals is limited by constituent diffusion into an abnormally dense, glass-like, non-crystalline phase.

  1. Crust behavior and erosion rate prediction of EPR sacrificial material impinged by core melt jet

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gen; Liu, Ming, E-mail: ming.liu@mail.xjtu.edu.cn; Wang, Jinshi; Chong, Daotong; Yan, Junjie

    2017-04-01

    Highlights: • A numerical code was developed to analyze melt jet-concrete interaction in the frame of MPS method. • Crust and ablated concrete layer at UO{sub 2}-ZrO{sub 2} melt and concrete interface periodically developed and collapsed. • Concrete surface temperature fluctuated around a low temperature and ablation temperature. • Concrete erosion by Fe-Zr melt jet was significantly faster than that by UO{sub 2}-ZrO{sub 2} melt jet. - Abstract: Sacrificial material is a special ferro-siliceous concrete, designed in the ex-vessel core melt stabilization system of European Pressurized water Reactor (EPR). Given a localized break of RPV lower head, the melt directly impinges onto the dry concrete in form of compact jet. The concrete erosion behavior influences the failure of melt plug, and further affects melt spreading. In this study, a numerical code was developed in the frame of Moving Particle Semi-implicit (MPS) method, to analyze the crust behavior and erosion rate of sacrificial concrete, impinged by prototypic melt jet. In validation of numerical modeling, the time-dependent erosion depth and erosion configuration matched well with the experimental data. Sensitivity study of sacrificial concrete erosion indicates that the crust and ablated concrete layer presented at UO{sub 2}-ZrO{sub 2} melt and concrete interface, whereas no crust could be found in the interaction of Fe-Zr melt with concrete. The crust went through stabilization-fracture-reformation periodic process, accompanied with accumulating and collapsing of molten concrete layer. The concrete surface temperature fluctuated around a low temperature and ablation temperature. It increased as the concrete surface layer was heated to melting, and dropped down when the cold concrete was revealed. The erosion progression was fast in the conditions of small jet diameter and large concrete inclination angle, and it was significantly faster in the erosion by metallic melt jet than by oxidic melt jet.

  2. University Students' Conceptions of Bonding in Melting and Dissolving Phenomena

    Science.gov (United States)

    Smith, K. Christopher; Nakhleh, Mary B.

    2011-01-01

    Undergraduate and graduate students' predictions and submicroscopic level explanations for the melting of four materials (salt, chalk, sugar, and butter), and for the mixing of these solutes in two solvents (water and cooking oil) were collected. Twenty-three undergraduate students and seven graduate students participated in the study, and data…

  3. Does Sea Level Change when a Floating Iceberg Melts?

    Science.gov (United States)

    Lan, Boon Leong

    2010-01-01

    On the answer page to a recent "Figuring Physics" question, the cute mouse asks another question: "Does the [sea] water level change if the iceberg melts?" The conventional answer is "no." However, in this paper I will show through a simple analysis involving Archimedes' principle that the sea level will rise. The analysis shows the wrong…

  4. Influence of glycerol on the melting of potato starch

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Soest, J.J.G. van; Bezemer, R.C.; Wit, D. de

    1996-01-01

    The gelatinization and melting of granular and recrystallized starch have been studied in the presence of low and high levels of glycerol or water by differential scanning calorimetry. The gelatinization onset temperature is increased in the presence of glycerol, whereas the excess gelatinization

  5. Does Sea Level Change when a Floating Iceberg Melts?

    Science.gov (United States)

    Lan, Boon Leong

    2010-01-01

    On the answer page to a recent "Figuring Physics" question, the cute mouse asks another question: "Does the [sea] water level change if the iceberg melts?" The conventional answer is "no." However, in this paper I will show through a simple analysis involving Archimedes' principle that the sea level will rise. The analysis shows the wrong…

  6. Influence of glycerol on the melting of potato starch

    NARCIS (Netherlands)

    Soest, van J.J.G.; Bezemer, R.C.; Wit, de D.; Viiegenthart, J.F.G.

    1996-01-01

    The gelatinization and melting of granular and recrystallized starch have been studied in the presence of low and high levels of glycerol or water by differential scanning calorimetry. The gelatinization onset temperature is increased in the presence of glycerol, whereas the excess gelantinization

  7. Additive manufacturing of ITER first wall panel parts by two approaches: Selective laser melting and electron beam melting

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Yuan [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm (Sweden); Rännar, Lars-Erik [Department of Quality Technology, Mechanical Engineering and Mathematics, Sports Tech Research Centre, Mid Sweden University, SE-831 25 Östersund (Sweden); Wikman, Stefan [Fusion for Energy, Torres Diagonal Litoral B3, Josep Pla 2, 08019 Barcelona (Spain); Koptyug, Andrey [Department of Quality Technology, Mechanical Engineering and Mathematics, Sports Tech Research Centre, Mid Sweden University, SE-831 25 Östersund (Sweden); Liu, Leifeng; Cui, Daqing [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm (Sweden); Shen, Zhijian, E-mail: shen@mmk.su.se [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm (Sweden)

    2017-03-15

    Highlights: • A novel way using additive manufacturing to fabricated ITER First Wall Panel parts is proposed. • ITER First Wall Panel parts successfully manufactured by both SLM and EBM are compared. • Physical and mechanical properties of SLM and EBM SS316L are clearly compared. • Problems encountered for large scale part building were discussed and possible solutions are given. - Abstract: Fabrication of ITER First Wall (FW) Panel parts by two additive manufacturing (AM) technologies, selective laser melting (SLM) and electron beam melting (EBM), was supported by Fusion for Energy (F4E). For the first time, AM is applied to manufacture ITER In-Vessel parts with complex design. Fully dense SS316L was prepared by both SLM and EBM after developing optimized laser/electron beam parameters. Characterizations on the density, magnetic permeability, microstructure, defects and inclusions were carried out. Tensile properties, Charpy-impact properties and fatigue properties of SLM and EBM SS316L were also compared. ITER FW Panel parts were successfully fabricated by both SLM and EBM in a one-step building process. The SLM part has smoother surface, better size accuracy while the EBM part takes much less time to build. Issues with removing support structures might be solved by slightly changing the design of the internal cooling system. Further investigation of the influence of neutron irradiation on materials properties between the two AM technologies is needed.

  8. 明永冰川融水中一株裂解性低温噬菌体的分离及特征%Isolation and characterization of a lytic bacteriophage from Mingyong glacier melt water

    Institute of Scientific and Technical Information of China (English)

    李明源; 季秀玲; 王宝强; 张琦; 林连兵; 张兵; 魏云林

    2012-01-01

    [目的]高山冰川是一类独特的生态系统,本研究探索从明永冰川地区分离和培养低温菌噬菌体,并对其特征进行研究.[方法]利用已分离的低温菌为宿主,采用“双层平板法”从明永冰川融水中分离纯化低温菌噬菌体;对噬菌体及其宿主进行电镜形态观察,并进行噬菌体基因组限制性酶切片段长度多态性分析、衣壳蛋白组成分析及噬菌体生理特征研究.[结果]从明永冰川融水中分离获得一株裂解性低温噬菌体,命名为MYSP03(Mingyong Flavobacterium Siphoviridae Bacteriophage),其宿主菌MYB03鉴定为Flavobacterium菌株.噬菌体MYSP03为长尾型,无囊膜,头部具典型的正多面体立体对称结构,直径约72 nm;尾管长约240 nm,直径约10 nm;4℃时具侵染活性,在4℃- 20℃范围内均可产生边缘清晰、透明的噬菌斑,最适感染温度约10℃,pH耐受范围较广,最适感染pH约9.4,对氯仿不敏感,基冈组为双链DNA,大小约66 kb.%[ Objective] Glacier is a unique ecological system. This study focused on the isolation and characterization of a cold-active bateriophage from Mingyong glacier area in northwest Yunnan. [ Methods ] Bacterial strains isolated from glacial melt water were used as host cells to isolate and purify bacteriophages by double-layer plate method. The morphology of the isolated phages and their host strains were observed by electron microscope. Restriction fragment length polymorphism (RFLP) analysis of genomic DNA, constituent proteins and physiological analysis of the bacteriophages were further carried out to characterize the phages. [Results] A lytic cold-active bacteriophage, designated as MYSP03 , was isolated from Mingyong glacier. Its host strain MYB03 was identified as a member of genus Flavobacterium, based on the 16S rRNA sequence analysis. The bacteriophage MYSP03 has a isometric head ( about 72 nm in diameter) and a long tail (about 240 nm in length and 10 nm in width) , but no

  9. Channelized bottom melting and stability of floating ice shelves

    OpenAIRE

    Rignot, E; Steffen, K.

    2008-01-01

    The floating ice shelf in front of Petermann Glacier, in northwest Greenland, experiences massive bottom melting that removes 80% of its ice before calving into the Arctic Ocean. Detailed surveys of the ice shelf reveal the presence of 1-2 km wide, 200-400 in deep, sub-ice shelf channels, aligned with the flow direction and spaced by 5 km. We attribute their formation to the bottom melting of ice from warm ocean waters underneath. Drilling at the center of one of channel, only 8 m above sea l...

  10. Magnetic Biocomposites for Remote Melting.

    Science.gov (United States)

    Zhou, Mengbo; Liebert, Tim; Müller, Robert; Dellith, Andrea; Gräfe, Christine; Clement, Joachim H; Heinze, Thomas

    2015-08-10

    A new approach toward the fabrication of biocompatible composites suitable for remote melting is presented. It is shown that magnetite nanoparticles (MNP) can be embedded into a matrix of biocompatible thermoplastic dextran esters. For that purpose, fatty acid esters of dextran with adjustable melting points in the range of 30-140 °C were synthesized. Esterification of the polysaccharide by activation of the acid as iminium chlorides guaranteed mild reaction conditions leading to high quality products as confirmed by FTIR- and NMR spectroscopy as well as by gel permeation chromatography (GPC). A method for the preparation of magnetically responsive bionanocomposites was developed consisting of combined dissolution/suspension of the dextran ester and hydrophobized MNPs in an organic solvent followed by homogenization with ultrasonication, casting of the solution, drying and melting of the composite for a defined shaping. This process leads to a uniform distribution of MNPs in nanocomposite as revealed by scanning electron microscope. Samples of different geometries were exposed to high frequency alternating magnetic field. It could be shown that defined remote melting of such biocompatible nanocomposites is possible for the first time. This may lead to a new class of magnetic remote control systems, which are suitable for controlled release applications or self-healing materials.

  11. UNCONSTRAINED MELTING AND SOLIDIFICATION INSIDE ...

    African Journals Online (AJOL)

    2015-09-01

    Sep 1, 2015 ... Department of Mechanical Engineering, Sari Branch, Islamic Azad University, ... at initial time of melting process where the layer of liquid PCM near hot ... They carried out the simulation at different Rayleigh numbers ranging from 10 .... An enthalpy-porosity technique [28] is used in FLUENT for modeling the.

  12. Thermodynamics of freezing and melting

    DEFF Research Database (Denmark)

    Pedersen, Ulf Rørbæk; Costigliola, Lorenzo; Bailey, Nicholas

    2016-01-01

    phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variation along this line of the reduced crystalline vibrational mean-square displacement (the Lindemann ratio...

  13. Analysis of ex-vessel melt jet breakup and coolability. Part 1: Sensitivity on model parameters and accident conditions

    Energy Technology Data Exchange (ETDEWEB)

    Moriyama, Kiyofumi; Park, Hyun Sun, E-mail: hejsunny@postech.ac.kr; Hwang, Byoungcheol; Jung, Woo Hyun

    2016-06-15

    Highlights: • Application of JASMINE code to melt jet breakup and coolability in APR1400 condition. • Coolability indexes for quasi steady state breakup and cooling process. • Typical case in complete breakup/solidification, film boiling quench not reached. • Significant impact of water depth and melt jet size; weak impact of model parameters. - Abstract: The breakup of a melt jet falling in a water pool and the coolability of the melt particles produced by such jet breakup are important phenomena in terms of the mitigation of severe accident consequences in light water reactors, because the molten and relocated core material is the primary heat source that governs the accident progression. We applied a modified version of the fuel–coolant interaction simulation code, JASMINE, developed at Japan Atomic Energy Agency (JAEA) to a plant scale simulation of melt jet breakup and cooling assuming an ex-vessel condition in the APR1400, a Korean advanced pressurized water reactor. Also, we examined the sensitivity on seven model parameters and five initial/boundary condition variables. The results showed that the melt cooling performance of a 6 m deep water pool in the reactor cavity is enough for removing the initial melt enthalpy for solidification, for a melt jet of 0.2 m initial diameter. The impacts of the model parameters were relatively weak and that of some of the initial/boundary condition variables, namely the water depth and melt jet diameter, were very strong. The present model indicated that a significant fraction of the melt jet is not broken up and forms a continuous melt pool on the containment floor in cases with a large melt jet diameter, 0.5 m, or a shallow water pool depth, ≤3 m.

  14. [The applicability of sucrose laurate in hot-melt technology].

    Science.gov (United States)

    Lang, Péter; Szuts, Angéla; Ambrus, Rita; Szabóné, Révész Piroska

    2011-01-01

    Nowadays, one of the most important task of the pharmaceutical technology is to optimize the dissolution of active ingredients, because most of the drug candidates have a poorly water solubility and hence a slow absorption. According to the latest examinations, the bioavailability of poorly water soluble drugs can be increased significantly by using surfactants or the mixture of surfactants and polymers. Nowadays, surfactants (like polysorbates) are generally used in the production of solid dispersions, so the use of surface-active sucrose esters can be resulted an innovative solution in the pharmaceutical technology. The aim of our investigation was to examine the applicability of sucrose laurate in hot-melt technology in order to influence the crystalline structure and dissolution rate of a poorly water soluble drug (gemfibrosil) having low-melting point. The results of the X-ray powder diffractometry have showed that the sucrose laurate had no significant effect on the crystallization degree of the drug which is important in case of the stability. On the bases of the results of in-vitro dissolution studies, it can be concluded that the sucrose laurate (using minimum 5%) can be well applied in hot-melt technology with carriers having characteristic melting point (e.g. Macrogol) to increase the dissolution rate of poorly soluble drugs.

  15. On edge melting under the Colorado Plateau margin

    Science.gov (United States)

    Rudzitis, Sean; Reid, Mary R.; Blichert-Toft, Janne

    2016-07-01

    Asthenosphere beneath the relatively thin lithosphere of the Basin and Range province appears to be juxtaposed in step-like fashion against the Colorado Plateau's thick lithospheric keel. Primary to near-primary basalts are found above this edge, in the San Francisco-Morman Mountain volcanic fields, north central Arizona, western USA. We show that at least two distinct peridotite-dominated mantle end-members contributed to the origin of the basalts. One has paired Nd and Hf isotopic characteristics that cluster near the mantle array and trace element patterns as expected for melts generated in the asthenosphere, possibly in the presence of garnet. The second has isotopic compositions displaced above the ɛHf - ɛNd mantle array which, together with its particular trace element characteristics, indicate contributions from hydrogenous sediments and/or melt (carbonatite or silicate)-related metasomatism. Melt equilibration temperatures obtained from Si- and Mg-thermobarometry are mostly 1340-1425°C and account for the effects of water (assumed to be 2 wt.%) and estimated CO2 (variable). Melt equilibration depths cluster at the inferred location of the lithosphere-asthenosphere boundary at ˜70-75 km beneath the southwestern margin of the Colorado Plateau but scatter to somewhat greater values (˜100 km). Melt generation may have initiated in or below the garnet-spinel facies transition zone by edge-driven convection and continued as mantle and/or melts upwelled, assimilating and sometimes equilibrating with shallower contaminated mantle, until melts were finally extracted.

  16. THE PHYSICS OF MELTING IN EARLY MODERN LOVE POETRY

    Directory of Open Access Journals (Sweden)

    Andrea Brady

    2014-12-01

    Full Text Available Melting is a familiar trope in early modern erotic poetry, where it can signify the desire to transform the beloved from icy chastity through the warmth of the lover’s passion. However, this Petrarchan convention can be defamiliarised by thinking about the experiences of freezing and melting in this period. Examining melting in the discourses of early modern meteorology, medicine, proverb, scientific experiments, and preservative technologies, as well as weather of the Little Ice Age and the exploration of frozen hinterlands, this essay shows that our understanding of seeming constants – whether they be the physical properties of water or the passions of love – can be modulated through attention to the specific histories of cognition and of embodiment.

  17. Electron Beam Melting and Refining of Metals: Computational Modeling and Optimization

    National Research Council Canada - National Science Library

    Katia Vutova; Veliko Donchev

    2013-01-01

    ..., instrument engineering, electronics, etc. A time-dependent 3D axis-symmetrical heat model for simulation of thermal transfer in metal ingots solidified in a water-cooled crucible at electron beam melting and refining (EBMR) is developed...

  18. Chemical Composition and Daily Variation of Melt Water During Ablation Season in Monsoonal Temperate Glacier Region:A Case Study of Baishui Glacier No.1%典型季风型温冰川消融期融水化学日变化特征

    Institute of Scientific and Technical Information of China (English)

    朱国锋; 蒲焘; 何元庆; 王培震; 孔建龙; 张宁宁; 辛惠娟

    2012-01-01

    Melt water samples collected continuously from 29 August to 3 September 2009 in the Baishui Glacier No.1 at elevation of 4 750 m were analyzed for pH,conductivity,δ18 O and inorganic ions.The results showed that the pH had obvious diurnal variations and was increased slightly by the influence of precipitation.The dissolution of alkaline soluble salts in the dust was the main reason for the increase of melt water conductivity;the value of δ18 O was relatively low in strong ablation period and high in slight ablation period.Different from other research areas,the concentrations of Na+,K+,which were influenced by lithological and marine water vapor,were higher than that of Μg2+ in the study area;HCO-3 and Ca2+ accounted for more than 80% of total ions in snow and ice melt water,indicating that the ions mainly came from limestone and the melt water was a typical carbonate solution;The content of melt water had an obvious daily change with temperature change,but the response amplitudes were different;Monsoon transport,local rock lithology,human industrial and agricultural activities were the main sources of inorganic ions and the deciding factors of the ion composition in the Baishui Glacier No.1.%分析了玉龙雪山白水1号冰川区2009年8月29日~9月3日4 750 m处冰雪融水的pH、电导率、无机离子和δ18O的化学特征,结果表明,消融期日尺度上pH值受气温变化影响较大.碱性尘埃中的可溶盐溶解导致融水电导率增大.一天中消融速率快时δ18O值较低,消融速率慢时δ18O值较高.受岩石岩性和海洋水汽影响,研究区Na+、K+的平均浓度高于Μg2+的平均浓度.融水中阳离子主要来源于石灰岩风化,属典型的碳酸盐溶滤水.融水中无机离子的总含量随气温的变化而变化,具有明显的周期性,但是不同可溶性离子对气温变化所导致的消融速率响应幅度不一致.局地岩石岩性、季风输送和人类活动是白水1号冰川融水中无机离子的主要来源.

  19. Electro-mechanical connection system for ITER in-vessel magnetic sensors

    Energy Technology Data Exchange (ETDEWEB)

    Rizzolo, Andrea; Brombin, Matteo; Gonzalez, Winder [Consorzio RFX, Corso Stati Uniti, 4, 35127 Padova (Italy); Marconato, Nicolò, E-mail: nicolo.marconato@igi.cnr.it [Consorzio RFX, Corso Stati Uniti, 4, 35127 Padova (Italy); Peruzzo, Simone [Consorzio RFX, Corso Stati Uniti, 4, 35127 Padova (Italy); Arshad, Shakeib [Fusion for Energy, C/Josep Pla, 2, 08019 Barcelona (Spain); Ma, Yunxing; Vayakis, George [ITER Organization, Route de Vinon-sur-Verdon, 13067 St Paul Lez Durance (France); Williams, Adrian [Oxford Technologies Ltd, 7 Nuffield Way, Abingdon, Oxon, OX14 1RL (United Kingdom)

    2016-11-01

    Highlights: • Latest status of the ITER “Generic In-Vessel Magnetic Platform” design activity. • Integration within the ITER In-Vessel configuration model. • Geometry optimization based on thermo-mechanical and magnetic field 3D calculation. • Assessment of the remote handling maintenance compatibility. - Abstract: This paper presents the preliminary design of the “In-Vessel Magnetic platform”, which is a subsystem of the magnetic diagnostics formed by all the components necessary for guaranteeing the thermo-mechanical interface of the actual magnetic sensors with the vacuum vessel (VV), their protection and the electrical connection to the in-vessel wiring for the transmission of the detected signal with a minimum level of noise. The design has been developed in order to comply with different functional requirements: the mechanical attachment to the VV; the electrical connection to the in-vessel wiring; efficient heat transfer to the VV; the compatibility with Remote Handling (RH) system for replacement; the integration of metrology features for post-installation control; the Electro Magnetic Interference (EMI) shielding from Electron Cyclotron Heating (ECH) stray radiation without compromising the sensor pass band (15 kHz). Significant effort has been dedicated to develop the CAD model, integrated within the ITER In-Vessel configuration model, taking care of the geometrical compliance with the Blanket modules (modified in order to accommodate the magnetic sensors in suitable grooves) and the RH compatibility. Thorough thermo-mechanical and electro-magnetic Finite Element Method (FEM) analyses have been performed to assess the reliability of the system in standard and off-normal operating conditions for the low frequency magnetic sensors.

  20. Multidimensional shielding analysis of the JASPER in-vessel fuel storage experiments

    Energy Technology Data Exchange (ETDEWEB)

    Bucholz, J.A.

    1993-03-01

    The In-Vessel Fuel Storage (IVFS) experiments analyzed in this report were conducted at the Oak Ridge National Laboratory`s Tower Shielding Reactor (TSR) as part of the Japanese-American Shielding Program for Experimental Research (JASPER). These IVFS experiments were designed to study source multiplication and three-dimensional effects related to in-vessel storage of spent fuel elements in liquid metal reactor (LMR) systems. The present report describes the 2-D and 3-D models, analyses, and calculated results corresponding to a limited subset of those IVFS experiments in which the US LMR program has a particular interest.

  1. In-vessel tritium retention and removal in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Federici, G. [ITER JWS Garching Co-Center (Germany); Anderl, R.A. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Andrew, P. [JET Joint Undertaking, Abingdon (United Kingdom)] [and others

    1998-06-01

    The International Thermonuclear Experimental Reactor (ITER) is envisioned to be the next major step in the world`s fusion program from the present generation of tokamaks and is designed to study fusion plasmas with a reactor relevant range of plasma parameters. During normal operation, it is expected that a fraction of the unburned tritium, that is used to routinely fuel the discharge, will be retained together with deuterium on the surfaces and in the bulk of the plasma facing materials (PFMs) surrounding the core and divertor plasma. The understanding of he basic retention mechanisms (physical and chemical) involved and their dependence upon plasma parameters and other relevant operation conditions is necessary for the accurate prediction of the amount of tritium retained at any given time in the ITER torus. Accurate estimates are essential to assess the radiological hazards associated with routine operation and with potential accident scenarios which may lead to mobilization of tritium that is not tenaciously held. Estimates are needed to establish the detritiation requirements for coolant water, to determine the plasma fueling and tritium supply requirements, and to establish the needed frequency and the procedures for tritium recovery and clean-up. The organization of this paper is as follows. Section 2 provides an overview of the design and operating conditions of the main components which define the plasma boundary of ITER. Section 3 reviews the erosion database and the results of recent relevant experiments conducted both in laboratory facilities and in tokamaks. These data provide the experimental basis and serve as an important benchmark for both model development (discussed in Section 4) and calculations (discussed in Section 5) that are required to predict tritium inventory build-up in ITER. Section 6 emphasizes the need to develop and test methods to remove the tritium from the codeposited C-based films and reviews the status and the prospects of the

  2. In-vessel tritium retention and removal in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Federici, G. [ITER JWS Garching Co-Center (Germany); Anderl, R.A. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Andrew, P. [JET Joint Undertaking, Abingdon (United Kingdom)] [and others

    1998-06-01

    The International Thermonuclear Experimental Reactor (ITER) is envisioned to be the next major step in the world`s fusion program from the present generation of tokamaks and is designed to study fusion plasmas with a reactor relevant range of plasma parameters. During normal operation, it is expected that a fraction of the unburned tritium, that is used to routinely fuel the discharge, will be retained together with deuterium on the surfaces and in the bulk of the plasma facing materials (PFMs) surrounding the core and divertor plasma. The understanding of he basic retention mechanisms (physical and chemical) involved and their dependence upon plasma parameters and other relevant operation conditions is necessary for the accurate prediction of the amount of tritium retained at any given time in the ITER torus. Accurate estimates are essential to assess the radiological hazards associated with routine operation and with potential accident scenarios which may lead to mobilization of tritium that is not tenaciously held. Estimates are needed to establish the detritiation requirements for coolant water, to determine the plasma fueling and tritium supply requirements, and to establish the needed frequency and the procedures for tritium recovery and clean-up. The organization of this paper is as follows. Section 2 provides an overview of the design and operating conditions of the main components which define the plasma boundary of ITER. Section 3 reviews the erosion database and the results of recent relevant experiments conducted both in laboratory facilities and in tokamaks. These data provide the experimental basis and serve as an important benchmark for both model development (discussed in Section 4) and calculations (discussed in Section 5) that are required to predict tritium inventory build-up in ITER. Section 6 emphasizes the need to develop and test methods to remove the tritium from the codeposited C-based films and reviews the status and the prospects of the

  3. Filament stretching rheometry of polymer melts

    DEFF Research Database (Denmark)

    Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz

    2005-01-01

    The Filament Stretching Rheometry (FSR) method developed by Sridhar, McKinley and coworkers for polymer solutions has been extended to be used also for polymer melts. The design of a melt-FSR will be described and differences to conventional melt elongational rheometers will be pointed out. Results...

  4. Filament stretching rheometry of polymer melts

    DEFF Research Database (Denmark)

    Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz

    2005-01-01

    The Filament Stretching Rheometry (FSR) method developed by Sridhar, McKinley and coworkers for polymer solutions has been extended to be used also for polymer melts. The design of a melt-FSR will be described and differences to conventional melt elongational rheometers will be pointed out. Results...

  5. Non-eruptive ice melt driven by internal heat at glaciated stratovolcanoes

    Science.gov (United States)

    Hemmings, Brioch; Whitaker, Fiona; Gottsmann, Joachim; Hawes, Molly C.

    2016-11-01

    Mudflows, floods and lahars from rapid snow and ice melting present potentially devastating hazards to populations surrounding glacial stratovolcanoes. Most ice-melt induced lahars have resulted from eruptive processes. However, there is evidence for non-eruptive hydrothermal volcanic unrest generating rapid and hazardous glacial melt. Here, we use TOUGH2 numerical fluid flow simulations to explore ice melt potential associated with hydrothermal perturbation. Our simulations are loosely based on Cotopaxi Volcano, Ecuadorian Andes. We show that dynamic permeability has a strong control on ice melt response to perturbation. In the absence of concurrent permeability increases, the delay time between onset of a deep hydrothermal perturbation and a response in surface heat flow is on the order of many 10s of years. When increased hot fluid influx at depth is combined with permeability enhancement, the surface heat flow response can be immediate. However, our results suggest that melt rates resulting from such hydrothermal perturbation are still orders of magnitude lower than those induced by eruptive processes; potentially hazardous melt volumes take many months to accumulate, compared to minutes for eruption induced melting. Additional mechanisms, such as glacier destabilisation, meltwater impounding and hydrothermal outburst, may be required to generate volumes of water similar to those associated with catastrophic eruption initiated ice-melt lahars.

  6. SURFACE MELTING OF ALUMINIUM ALLOYS

    OpenAIRE

    Veit, S.; Albert, D; Mergen, R.

    1987-01-01

    The wear properties of aluminium base alloys are relatively poor. Laser surface melting and alloying has proved successful in many alloy systems as a means of significantly improving the surface properties. The present work describes experiments designed to establish the scope of laser treatment of aluminium alloys. Aluminium does not absorb CO2 laser light as well as other metals which necessitated first a general study of absorption caotings. Aluminium alloys offer fewer opportunities than ...

  7. The formation and chemistry of low degree hydrous partial melt on top of the transition zone

    Science.gov (United States)

    Frost, Daniel J.; Mookherjee, Mainak

    2010-05-01

    There is some geophysical evidence for the presence of silicate melt on top of the 410 km seismic discontinuity. It has also been argued that the difference in the water storage capacity of upper mantle versus transition zone minerals may cause dehydration melting as material up-wells across the 410. Studies have proposed that hydrous partial melts may be neutrally buoyant in the mantle at these conditions. In order to assess these possibilities it is important to determine the likely composition of small degree hydrous melts at these conditions and to measure the H2O contents of mantle minerals coexisting with this melt phase. The composition of a hydrous melt in equilibrium with a mantle peridotite composition has been determined at conditions of the 410 and 1450°C. Sandwich experiments were performed where an 'initial-guess' hydrous melt composition was equilibrated with 50% anhydrous peridotite. The resulting melt composition was used to assemble a further melt, which was then equilibrated in the same way. After several iterations it was possible to derive a melt composition, which was in equilibrium with a mineral assemblage identical to that observed for an anhydrous peridotite composition at the same conditions. We assess whether this melt composition could be neutrally buoyant at 410km. The 410 km discontinuity may also correspond to a transition in redox state in the mantle from a reducing transition zone to a less reduced upper mantle. Volatiles may also collect and induce melting at this horizon due to the oxidation of a rising mobile reduced fluid phase containing CH4. Minerals in mantle upwelling out of a hydrous melt layer would be expected to have H2O contents close to saturation; however, this may not be the case if the melt layer also contains other volatile components such as CO2 or CH4, which further lower the H2O activity in the melt. We assess ranges of melt compositions that may be in equilibrium with minerals containing relatively low H2O

  8. Impact ejecta-induced melting of surface ice deposits on Mars

    Science.gov (United States)

    Weiss, David K.; Head, James W.

    2016-12-01

    , depending on crater diameter, ice thickness, surface temperature, and geothermal heat flux. Contact melting is predicted to produce fluvial features on the surface of ejecta and the interior crater walls, whereas basal melting is predicted to produce fluvial features only on the interior crater walls. Before basal melting initiates, the ice-cemented cryosphere underlying the crater ejecta is predicted to melt and drain downwards through the substratum, generating a source of water for chemical alteration and possibly subsurface clay formation. These candidate melting processes are predicted to occur under a wide range of parameters, and provides a basis for further morphologic investigation.

  9. Results of recent KROTOS FCI tests. Alumina vs. corium melts

    Energy Technology Data Exchange (ETDEWEB)

    Huhtiniemi, I.; Magallon, D.; Hohmann, H. [Commission of the European Communities, Ispra (Italy). Joint Research Center

    1998-01-01

    Recent results from KROTOS fuel-coolant interaction experiments are discussed. Five tests with alumina were performed under highly subcooled conditions, all of these tests resulted in spontaneous steam explosions. Additionally, four tests were performed at low subcooling to confirm, on one hand, the suppression of spontaneous steam explosions under such conditions and, on the other hand, that such a system is still triggerable using an external initiator. The other test parameters in these alumina tests included the melt superheat and the initial pressure. All the tests in the investigated superheat range (150 K - 750 K) produced a steam explosion and no evidence of the explosion suppression by the elevated initial pressure (in the limited range of 0.1 - 0.375 MPa) was observed in the alumina tests. The corium test series include a test with 3 kg of melt under both subcooled and near saturated conditions at ambient pressure. Two additional tests were performed with subcooled water; one test was performed at an elevated pressure of 0.2 MPa with 2.4 kg of melt and another test with 5.1 kg of melt at ambient pressure. None of these tests with corium produced a propagating energetic steam explosion. However, propagating low energy (about twice the energy of the trigger pulse) events were observed. All corium tests produced significantly higher water level swells during the mixing phase than the corresponding alumina tests. Present experimental evidence suggests that the water depletion in the mixing zone suppresses energetic steam explosions with corium melts at ambient pressure and in the present pour geometry. Processes that could produce such a difference in void generation are discussed. (author)

  10. Melting Behaviour of Ferronickel Slags

    Science.gov (United States)

    Sagadin, Christoph; Luidold, Stefan; Wagner, Christoph; Wenzl, Christine

    2016-12-01

    The industrial manufacturing of ferronickel in electric furnaces produces large amounts of slag with strong acidic character and high melting points, which seriously stresses the furnace refractory lining. In this study, the melting behavior of synthetically produced ferronickel slags on magnesia as refractory material was determined by means of a hot stage microscope. Therefore, slags comprising the main oxides SiO2 (35-70 wt.%), MgO (15-45 wt.%) and Fe2O3 (5-35 wt.%) were melted in a graphite crucible and afterwards analyzed by a hot stage microscope. The design of experiments, which was created by the statistic software MODDE®, included 20 experiments with varying slag compositions as well as atmospheres. The evaluation of the test results occurred at three different characteristic states of the samples like the softening point according to DIN 51730 and the temperatures at which the area of residual cross-section of the samples amounted to 30% and 40%, respectively, of the original value depending of their SiO2/MgO ratio and iron oxide content. Additionally, the thickness of the zone influenced by the slag was measured and evaluated.

  11. Optimization of the Brass Melting

    Directory of Open Access Journals (Sweden)

    Biernat S.

    2014-08-01

    Full Text Available The article describes the optimization of the melting brass. Brasses, as one of the most popular alloys of copper, deserve special attention in the context of the processes of melting, which in turn would provide not only products of better quality, but also reduce the cost of their production or refining. For this purpose, several studies carried out deriatographic (DTA and thermogravimetric (TG using derivatograph. The results were confronted with the program SLAG - PROP used to evaluate the physicochemical properties of the coatings extraction. Based on the survey and analysis of the program can identify the most favorable physico - chemical properties, which should be carried out treatments. This allows for slag mixtures referred configurations oxide matrix containing specific stimulators of the reaction. Conducted empirical studies indicate a convergence of the areas proposed by the application. It should also be noted that the program also indicates additional areas in which to carry out these processes would get even better, to optimize the melting process, the results.

  12. Study of subaqueous melting of Store Glacier, West Greenland using ocean observations and numerical simulations

    Science.gov (United States)

    Xu, Y.; Rignot, E. J.; Menemenlis, D.; van den Broeke, M. R.

    2012-12-01

    Ice discharge from the Greenland Ice Sheet is mainly through tidewater glaciers that terminate in the ocean and melt in contact with ocean waters. Subaqueous melting at the calving front is a direct mechanism for mass loss and a potential trigger for glacier acceleration. We present an analysis of oceanographic data collected in the fjord of Store Glacier, West Greenland during August 2010 and 2012. Using these data, we calculate the subaqueous melt rates. Independently, we employ the Massachusetts Institute of Technology general circulation model (MITgcm), modified to include melting at the calving front and outflow of subglacial water to model the ice melt rates of Store Glacier. Previous 2-D sensitivity studies showed that the subaqueous melt rate reaches several meters per day during the summer, increases non-linearly with subglacial runoff and linearly with ocean thermal forcing, and ceases when subglacial discharge is off during winter. We present new 3-D simulations at very high resolution, with measured oceanic temperature/salinity as boundary conditions, and subglacial runoff from the University of Utrecht's Regional Atmospheric Climate Model outputs on different years and seasons. We compare the ocean observations and numerical simulations and discuss the seasonal and inter-annual variations of subaqueous melting. This study helps evaluate the impact of the ocean on the subaqueous melting of Greenland tidewater glaciers and in turn on glacier mass balance. This work was carried out at University of California, Irvine and at the Jet Propulsion Laboratory under contract with NASA Cryosphere Science Program.

  13. Specific Changes of Exocarp and Mesocarp Occurring during Softening Differently Affect Firmness in Melting (MF) and Non Melting Flesh (NMF) Fruits

    OpenAIRE

    Onelli, E.; Ghiani, A.; Gentili, R; S Serra; Musacchi, S.; Citterio, S.

    2015-01-01

    Melting (MF) and non melting flesh (NMF) peaches differ in their final texture and firmness. Their specific characteristics are achieved by softening process and directly dictate fruit shelf life and quality. Softening is influenced by various mechanisms including cell wall reorganization and water loss. In this work, the biomechanical properties of MF Spring Crest's and NMF Oro A's exocarp and mesocarp along with the amount and localization of hydroxycinnamic acids and flavonoids were invest...

  14. Oscillatory subglacial drainage in the absence of surface melt

    Directory of Open Access Journals (Sweden)

    C. Schoof

    2013-11-01

    Full Text Available The presence of strong diurnal cycling in basal water pressure records obtained during the melt season is well-established for many glaciers. The behaviour of the drainage system outside the melt season is less well understood. Here we present borehole observations from a surge-type valley glacier in the St Elias Mountains, Yukon Territory, Canada. These indicate the onset of strongly correlated multi-day oscillations in water pressure in multiple boreholes straddling a main drainage axis, starting several weeks after the disappearance of a dominant diurnal mode in August 2011 and persisting until at least January 2012, when multiple data loggers suffered power failure. Jökulhlaups provide a template for understanding spontaneous water pressure oscillations not driven by external supply variability. Using a subglacial drainage model, we show that water pressure oscillations can also be driven on a much smaller scale by the interaction between conduit growth and distributed water storage in smaller water pockets, basal crevasses and moulins, and that oscillations can be triggered when water supply drops below a critical value. We suggest this in combination with a steady background supply of water from groundwater or englacial drainage as a possible explanation for the observed wintertime pressure oscillations.

  15. Complete dissipation of 2,4,6-trinitrotoluene by in-vessel composting

    NARCIS (Netherlands)

    Gümüscü, B.; Cekmecelioglu, Deniz; Tekinay, Turgay

    2015-01-01

    We demonstrate complete removal of 2,4,6-trinitrotoluene (TNT) in 15 days using an in-vessel composting system, which is amended with TNT-degrading bacteria strains. A mixture of TNT, food waste, manure, wood chips, soil and TNT-degrading bacteria consortium are co-composted for 15 days in an aerobi

  16. Complete dissipation of 2,4,6-trinitrotoluene by in-vessel composting

    NARCIS (Netherlands)

    Gümüscü, B.; Cekmecelioglu, Deniz; Tekinay, Turgay

    2015-01-01

    We demonstrate complete removal of 2,4,6-trinitrotoluene (TNT) in 15 days using an in-vessel composting system, which is amended with TNT-degrading bacteria strains. A mixture of TNT, food waste, manure, wood chips, soil and TNT-degrading bacteria consortium are co-composted for 15 days in an

  17. Complete dissipation of 2,4,6-trinitrotoluene by in-vessel composting

    NARCIS (Netherlands)

    Gumuscu, Burcu; Cekmecelioglu, Deniz; Tekinay, Turgay

    2016-01-01

    We demonstrate complete removal of 2,4,6-trinitrotoluene (TNT) in 15 days using an in-vessel composting system, which is amended with TNT-degrading bacteria strains. A mixture of TNT, food waste, manure, wood chips, soil and TNT-degrading bacteria consortium are co-composted for 15 days in an aerobi

  18. Recent developments of in-vessel calibration of mid-IR cameras at JET

    Science.gov (United States)

    Balboa, I.; Silburn, S.; Drewelow, P.; Huber, V.; Huber, A.; Kinna, D.; Price, M.; Matthews, G. F.; Collins, S.; Fessey, J.; Rack, M.; Trimble, P.; Zastrow, K.-D.

    2016-11-01

    Recent improvements in software tools and methodology have allowed us to perform a more comprehensive in-vessel calibration for all mid-infrared camera systems at JET. A comparison of experimental methods to calculate the non-uniformity correction is described as well as the linearity for the different camera systems. Measurements of the temperature are assessed for the different diagnostics.

  19. Sparse Representation and Dictionary Learning as Feature Extraction in Vessel Imagery

    Science.gov (United States)

    2014-12-01

    TECHNICAL REPORT 2070 December 2014 Sparse Representation and Dictionary Learning as Feature Extraction in Vessel Imagery...2 2.1.1 Dictionary Learning...8]. The descriptors are then clustered and pooled with respect to a dictionary of vocabulary features obtained from training imagery. The image is

  20. How much can Greenland melt? An upper bound on mass loss from the Greenland Ice Sheet through surface melting

    Science.gov (United States)

    Liu, X.; Bassis, J. N.

    2015-12-01

    With observations showing accelerated mass loss from the Greenland Ice Sheet due to surface melt, the Greenland Ice Sheet is becoming one of the most significant contributors to sea level rise. The contribution of the Greenland Ice Sheet o sea level rise is likely to accelerate in the coming decade and centuries as atmospheric temperatures continue to rise, potentially triggering ever larger surface melt rates. However, at present considerable uncertainty remains in projecting the contribution to sea level of the Greenland Ice Sheet both due to uncertainty in atmospheric forcing and the ice sheet response to climate forcing. Here we seek an upper bound on the contribution of surface melt from the Greenland to sea level rise in the coming century using a surface energy balance model coupled to an englacial model. We use IPCC Representative Concentration Pathways (RCP8.5, RCP6, RCP4.5, RCP2.6) climate scenarios from an ensemble of global climate models in our simulations to project the maximum rate of ice volume loss and related sea-level rise associated with surface melting. To estimate the upper bound, we assume the Greenland Ice Sheet is perpetually covered in thick clouds, which maximize longwave radiation to the ice sheet. We further assume that deposition of black carbon darkens the ice substantially turning it nearly black, substantially reducing its albedo. Although assuming that all melt water not stored in the snow/firn is instantaneously transported off the ice sheet increases mass loss in the short term, refreezing of retained water warms the ice and may lead to more melt in the long term. Hence we examine both assumptions and use the scenario that leads to the most surface melt by 2100. Preliminary models results suggest that under the most aggressive climate forcing, surface melt from the Greenland Ice Sheet contributes ~1 m to sea level by the year 2100. This is a significant contribution and ignores dynamic effects. We also examined a lower bound

  1. Studies of Behavior Melting Temperature Characteristics for Multi Thermocouple In-Core Instrument Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Donghyup; Chae, Myoungeun; Kim, Sungjin; Lee, Kyulim [Woojin inc, Hwasung (Korea, Republic of)

    2015-05-15

    Bottom-up type in-core instruments (ICIs) are used for the pressurized water reactors of OPR-1000, APR- 1400 in order to measure neutron flux and temperature in the reactor. It is a well-known technique and a proven design using years in the nuclear field. ICI consists of one pair of K-type thermocouple, five self-powered neutron detectors (SPNDs) and one back ground detector. K-type thermocouple's purpose is to measure the core exit temperature (CET) in the reactor. The CET is a very important factor for operating nuclear power plants and it is 327 .deg. C when generally operating the reactor in the nuclear power plant(NPP) in case of OPR- 1000. If the CET will exceed 650 .deg. C, Operators in the main control room should be considered to be an accident situation in accordance with a severe accident management guidance(SAMG). The Multi Thermocouple ICI is a new designed ICI assuming severe accident conditions. It consists of four more thermocouples than the existing design, so it has five Ktype thermocouples besides the thermocouple measuring CET is located in the same elevation as the ICI. Each thermocouple is able to be located in the desired location as required. The Multi Thermocouple ICI helps to measure the temperature distribution of the entire reactor. In addition, it will measure certain point of melted core because of the in-vessel debris of nuclear fuel when an accident occurs more seriously. In this paper, to simulate a circumstance such as a nuclear reactor severe accident was examined. In this study, the K-type thermocouples of Multi Thermocouple ICI was confirmed experimentally to be able to measure up to 1370 .deg. C before the thermocouples have been melted. And after the thermocouples were melted by debris, it was able to be monitored that the signal of EMF directed the infinite value of voltage. Therefore through the results of the test, it can be assumed that if any EMF data among the Multi Thermocouple ICI will direct the infinite value

  2. Mechanism Research on Melting Loss of Coppery Tuyere Small Sleeve in Blast Furnace

    Science.gov (United States)

    Chai, Yi-Fan; Zhang, Jian-Liang; Ning, Xiao-Jun; Wei, Guang-Yun; Chen, Yu-Ting

    2016-01-01

    The tuyere small sleeve in blast furnace works under poor conditions. The abnormal damage of it will severely affect the performance of the blast furnace, thus it should be replaced during the damping down period. So it is of great significance that we study and reduce the burnout of tuyere small sleeve. Melting loss is one case of its burnout. This paper studied the reasons of tuyere small sleeve's melting loss, through computational simulation and microscopic analysis of the melting section. The research shows that the temperature of coppery tuyere small sleeve is well distributed when there is no limescale in the lumen, and the temperature increases with the thickness of limescale. In addition, the interruption of circulating water does great harm to the tuyere small sleeve. The melting loss of tuyere small sleeve is caused by iron-slag erosion, with the occurrence of the melt metallurgical bonding and diffusion metallurgical combination.

  3. The impact of melt ponds on summertime microwave brightness temperatures and sea-ice concentrations

    DEFF Research Database (Denmark)

    Kern, Stefan; Rösel, Anja; Pedersen, Leif Toudal

    2016-01-01

    Sea-ice concentrations derived from satellite microwave brightness temperatures are less accurate during summer. In the Arctic Ocean the lack of accuracy is primarily caused by melt ponds, but also by changes in the properties of snow and the sea-ice surface itself. We investigate the sensitivity...... of eight sea-ice concentration retrieval algorithms to melt ponds by comparing sea-ice concentration with the melt-pond fraction. We derive gridded daily sea-ice concentrations from microwave brightness temperatures of summer 2009. We derive the daily fraction of melt ponds, open water between ice floes......, and the ice-surface fraction from contemporary Moderate Resolution Spectroradiometer (MODIS) reflectance data. We only use grid cells where the MODIS sea ice concentration, which is the melt-pond fraction plus the ice-surface fraction, exceeds 90 %. For one group of algorithms, e.g., Bristol and Comiso...

  4. Effect of melting conditions on striae in iron-bearing silicate melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Yue, Yuanzheng

    2012-01-01

    Chemical striae are present in a broad range of glass products, but due to their negative impact on e.g., the optical and mechanical properties, elimination of striae from melts is a key issue in glass technology. By varying melting temperatures, retentions times and redox conditions of an iron......-bearing calciumaluminosilicate melt, we quantify the effect of each of the three melting parameters on the stria content in the melt. The quantification of the stria content in the melt is conducted by means of image analysis on casted melt samples. We find that in comparison to an extension of retention time an increase...... factors such as compositional fluctuation of melts and bubbling due to iron reduction on the stria content. During the melting process, striae with a chemical gradient in a more mobile species equilibrate faster than striae caused by a chemical gradient in a less mobile species. The temperature and time...

  5. Water

    Science.gov (United States)

    Leopold, Luna Bergere; Baldwin, Helene L.

    1962-01-01

    What do you use water for?If someone asked you this question you would probably think right away of water for drinking. Then you would think of water for bathing, brushing teeth, flushing the toilet. Your list would get longer as you thought of water for cooking, washing the dishes, running the garbage grinder. Water for lawn watering, for play pools, for swimming pools, for washing the car and the dog. Water for washing machines and for air conditioning. You can hardly do without water for fun and pleasure—water for swimming, boating, fishing, water-skiing, and skin diving. In school or the public library, you need water to wash your hands, or to have a drink. If your home or school bursts into flames, quantities of water are needed to put it out.In fact, life to Americans is unthinkable without large supplies of fresh, clean water. If you give the matter a little thought, you will realize that people in many countries, even in our own, may suffer from disease and dirt simply because their homes are not equipped with running water. Imagine your own town if for some reason - an explosion, perhaps - water service were cut off for a week or several weeks. You would have to drive or walk to a neighboring town and bring water back in pails. Certainly if people had to carry water themselves they might not be inclined to bathe very often; washing clothes would be a real chore.Nothing can live without water. The earth is covered by water over three-fourths of its surface - water as a liquid in rivers, lakes and oceans, and water as ice and snow on the tops of high mountains and in the polar regions. Only one-quarter of our bodies is bone and muscle; the other three-fourths is made of water. We need water to live, and so do plants and animals. People and animals can live a long time without food, but without water they die in a few days. Without water, everything would die, and the world would turn into a huge desert.

  6. Directional close-contact melting in glacier ice

    Science.gov (United States)

    Kowalski, Julia; Schüller, Kai

    2015-04-01

    The Saturnian moon Enceladus shows incidence of liquid water underneath a thick ice sheet cover and is thought to be a potential candidate for extraterrestrial life. However, direct exploration of these subglacial aquatic ecosystems is very challenging. Within the scope of the joint research project 'Enceladus Explorer' (EnEx) (consisting of FH Aachen, RWTH Aachen, Bergische Universität Wuppertal, Universität Bremen, TU Braunschweig und Bundeswehr Universität München), initiated by the German Space Agency, a maneuverable close-contact melting probe has been developed. The force-regulated and heater-controlled probe is able to melt against gravity or even on a curved trajectory. Hence, it offers additional degrees of freedom in its melting motion, e.g. for target oriented melting or obstacle avoidance strategies. General feasibility of the concept has been demonstrated in various field tests. However, in order to optimize its design and to adopt it to extraterrestrial missions a simulation model is needed, capable of determining melting velocity and efficiency at given environmental conditions and system configurations. Within this contribution, the physical situation is abstracted into a quasi-stationary mathematical model description, and a numerical solution strategy is developed to compute melting velocity and temperature distribution within the probe and the surrounding ice. We present an inverse solution approach, in which a background velocity field of the ice mimics the melting velocity. The fundamental balance laws are solved with the corresponding melting rate. Following Newton's laws, the resulting force acting on the probe has to balance the contact force exerted by the probe and can hence be used for convergence. We present both, analytical results to a simplified head geometry, as well as results from a simulation model implemented into the open source software Elmer for arbitrary head geometries. The latter can deal with the full 3d situation

  7. The judgment of the All-melted-moment during using electron beam melting equipment to purify silicon

    Science.gov (United States)

    Han, Xiaojie; Meng, Jianxiong; Wang, Shuaiye; Jiang, Tonghao; Wang, Feng; Tan, Yi; Jiang, Dachuan

    2017-06-01

    Experiment has proved that the rate of impurity removal depends on the pressure and the temperature of the vacuum chamber during using electron beam to smelt silicon, and the amount of removed-impurity depends on time when other conditions are the same. In the actual production process, smelting time is a decisive factor of impurity removal amount while pressure and temperature of the vacuum chamber is certain due to a certain melting power. To avoiding the influence of human control and improving the quality of production, thinking of using cooling water temperature to estimate the state of material during metal smelting is considered. We try to use the change of cooling water temperature to judge that when silicon is all melted and to evaluate the effectiveness of this method.

  8. Feasibility of re-melting NORM-contaminated scrap metal

    Energy Technology Data Exchange (ETDEWEB)

    Winters, S. J.; Smith, K. P.

    1999-10-26

    Naturally occurring radioactive materials (NORM) sometimes accumulate inside pieces of equipment associated with oil and gas production and processing activities. Typically, the NORM accumulates when radium that is present in solution in produced water precipitates out in scale and sludge deposits. Scrap equipment containing residual quantities of these NORM-bearing scales and sludges can present a waste management problem if the radium concentrations exceed regulatory limits or activate the alarms on radiation screening devices installed at most scrap metal recycling facilities. Although NORM-contaminated scrap metal currently is not disposed of by re-melting, this form of recycling could present a viable disposition option for this waste stream. Studies indicate that re-melting NORM-contaminated scrap metal is a viable recycling option from a risk-based perspective. However, a myriad of economic, regulatory, and policy issues have caused the recyclers to turn away virtually all radioactive scrap metal. Until these issues can be resolved, re-melting of the petroleum industry's NORM-impacted scrap metal is unlikely to be a widespread practice. This paper summarizes the issues associated with re-melting radioactive scrap so that the petroleum industry and its regulators will understand the obstacles. This paper was prepared as part of a report being prepared by the Interstate Oil and Gas Compact Commission's NORM Subcommittee.

  9. Molecular dynamics simulation for surface melting and self-preservation effect of methane hydrate

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The surface melting process of structure sI methane hydrate is simulated at T = 240, 260, 280, and 300 K using NVT molecular dynamics method. The simulation results show that a quasi-liquid layer will be formed during the melting process. The density distribution, translation, orientation, and dynamic properties of water molecules in the quasi-liquid layer are calculated as a function of the distance normal to the interface, which indicates the performance of quasi-liquid layer exhibits a continuous change from crystal-like to liquid-like. The quasi-liquid layer plays as a resistance of mass transfer restraining the diffusion of water and methane molecules during the melting process. The resistance of quasi-liquid layer will restrain methane molecules diffuse from hydrate phase to gas phase and slow the melting process, which can be considered as a possible mechanism of self-preservation effect. The performance of quasi-liquid layer is more crystal-like when the temperature is lower than the melt- ing-point of water, which will exhibit an obvious self-preservation. The self-preservation will weaken while the temperature is higher than the melting-point of water because of the liquid-like performance of the quasi-liquid layer.

  10. The effect of salt on the melting of ice: A molecular dynamics simulation study

    Science.gov (United States)

    Kim, Jun Soo; Yethiraj, Arun

    2008-09-01

    The effect of added salt (NaCl) on the melting of ice is studied using molecular dynamics simulations. The equilibrium freezing point depression observed in the simulations is in good agreement with experimental data. The kinetic aspects of melting are investigated in terms of the exchange of water molecules between ice and the liquid phase. The ice/liquid equilibrium is a highly dynamic process with frequent exchange of water molecules between ice and the liquid phase. The balance is disturbed when ice melts and the melting proceeds in two stages; the inhibition of the association of water molecules to the ice surface at short times, followed by the increased dissociation of water molecules from the ice surface at longer times. We also find that Cl- ions penetrate more deeply into the interfacial region than Na+ ions during melting. This study provides an understanding of the kinetic aspects of melting that could be useful in other processes such as the inhibition of ice growth by antifreeze proteins.

  11. Variability of Basal Melt Beneath the Pine Island Glacier Ice Shelf, West Antarctica

    Science.gov (United States)

    Bindschadler, Robert; Vaughan, David G.; Vornberger, Patricia

    2011-01-01

    Observations from satellite and airborne platforms are combined with model calculations to infer the nature and efficiency of basal melting of the Pine Island Glacier ice shelf, West Antarctica, by ocean waters. Satellite imagery shows surface features that suggest ice-shelf-wide changes to the ocean s influence on the ice shelf as the grounding line retreated. Longitudinal profiles of ice surface and bottom elevations are analyzed to reveal a spatially dependent pattern of basal melt with an annual melt flux of 40.5 Gt/a. One profile captures a persistent set of surface waves that correlates with quasi-annual variations of atmospheric forcing of Amundsen Sea circulation patterns, establishing a direct connection between atmospheric variability and sub-ice-shelf melting. Ice surface troughs are hydrostatically compensated by ice-bottom voids up to 150m deep. Voids form dynamically at the grounding line, triggered by enhanced melting when warmer-than-average water arrives. Subsequent enlargement of the voids is thermally inefficient (4% or less) compared with an overall melting efficiency beneath the ice shelf of 22%. Residual warm water is believed to cause three persistent polynyas at the ice-shelf front seen in Landsat imagery. Landsat thermal imagery confirms the occurrence of warm water at the same locations.

  12. Rheology of Melt-bearing Crustal Rocks

    Science.gov (United States)

    Rosenberg, C. L.; Medvedev, S.; Handy, M. R.

    2006-12-01

    A review and reinterpretation of previous experimental data on the deformation of melt-bearing crustal rocks (Rosenberg and Handy, 2005) revealed that the relationship of aggregate strength to melt fraction is non-linear, even if plotted on a linear ordinate and abscissa. At melt fractions, Φ 0.07, the dependence of aggregate strength on Φ is significantly greater than at Φ > 0.07. This melt fraction (Φ= 0.07) marks the transition from a significant increase in the proportion of melt-bearing grain boundaries up to this point to a minor increase thereafter. Therefore, we suggest that the increase of melt-interconnectivity causes the dramatic strength drop between the solidus and a melt fraction of 0.07. A second strength drop occurs at higher melt fractions and corresponds to the breakdown of the solid (crystal) framework, corresponding to the well-known "rheologically critical melt percentage" (RCMP; Arzi, 1978). Although the strength drop at the RCMP is about 4 orders of magnitude, the absolute value of this drop is small compared to the absolute strength of the unmelted aggregate, rendering the RCMP invisible in a linear aggregate strength vs. melt fraction diagram. Predicting the rheological properties and thresholds of melt-bearing crust on the basis of the results and interpretations above is very difficult, because the rheological data base was obtained from experiments performed at undrained conditions in the brittle field. These conditions are unlikely to represent the flow of partially melted crust. The measured strength of most of the experimentally deformed, partially-melted samples corresponds to their maximum differential stress, before the onset of brittle failure, not to their viscous strength during "ductile" (viscous) flow. To overcome these problems, we extrapolated a theoretically-derived flow law for partially melted granite deforming by diffusion-accommodated grain-boundary sliding (Paterson, 2001) and an experimentally-derived flow law for

  13. Viscosity model for aluminosilicate melt

    Directory of Open Access Journals (Sweden)

    Zhang G.H.

    2012-01-01

    Full Text Available The structurally based viscosity model proposed in our previous study is extended to include more components, e.g. SiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O and K2O. A simple method is proposed to calculate the numbers of different types of oxygen ions classified by the different cations they bonded with, which is used to characterize the influence of composition on viscosity. When dealing with the aluminosilicate melts containing several basic oxides, the priority order is established for different cations for charge compensating Al3+ ions, according to the coulombic force between cation and oxygen anion. It is indicated that basic oxides have two paradox influences on viscosity: basic oxide with a higher basicity decreases viscosity more greatly by forming weaker non-bridging oxygen bond; while it increases viscosity more greatly by forming stronger bridging oxygen bond in tetrahedron after charge compensating Al3+ ion. The present model can extrapolate its application range to the system without SiO2. Furthermore, it could also give a satisfy interpretation to the abnormal phenomenon that viscosity increases when adding K2O to CaO-Al2O3-SiO2 melt within a certain composition range.

  14. Water

    Science.gov (United States)

    ... Lead Poisoning Prevention Training Center (HHLPPTC) Training Tracks Water Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir For information about lead in water in Flint, MI, please visit http://www.phe. ...

  15. Numerical analysis of grid plate melting after a severe accident in a Fast-Breeder Reactor (FBR)

    Indian Academy of Sciences (India)

    A Jasmin Sudha; K Velusamy

    2013-12-01

    Fast breeder reactors (FBRs) are provided with redundant and diverse plant protection systems with a very low failure probability (<10-6/reactor year), making core disruptive accident (CDA), a beyond design basis event (BDBE). Nevertheless, safety analysis is carried out even for such events with a view to mitigate their consequences by providing engineered safeguards like the in-vessel core catcher. During a CDA, a significant fraction of the hot molten fuel moves downwards and gets relocated to the lower plate of grid plate. The ability of this plate to resist or delay relocation of core melt further has been investigated by developing appropriate mathematical models and translating them into a computer code HEATRAN-1. The core melt is a time dependent volumetric heat source because of the radioactive decay of the fission products which it contains. The code solves the nonlinear heat conduction equation including phase change. The analysis reveals that if the bottom of grid plate is considered to be adiabatic, melt-through of grid plate (i.e., melting of the entire thickness of the plate) occurs between 800 s and 1000 s depending upon the initial conditions. Knowledge of this time estimate is essential for defining the initial thermal load on the core catcher plate. If heat transfer from the bottom of grid plate to the underlying sodium is taken into account, then melt-through does not take place, but the temperature of grid plate is high enough to cause creep failure.

  16. RHEOLOGY FEATURE OF SIMPLE METAL MELT

    Institute of Scientific and Technical Information of China (English)

    C.J. Sun; H.R. Geng; Y.S. Shen; X.Y. Teng; Z.X. Yang

    2007-01-01

    The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80, alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20, alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.

  17. Felsic Melt Generation at the MOR Magma Chamber Roof: Trace Element Evidence of Experimental Hydrous Partial Melts for Anatectic Processes at the East-Pacific Rise

    Science.gov (United States)

    Erdmann, M.; Fischer, L. A.; France, L.; Deloule, E.; Koepke, J.

    2013-12-01

    Felsic lithologies in oceanic crust environment are volumetrically small but occur frequently. Based on experimental and geochemical studies, different models for their generation are suggested, as fractional crystallization, partial melting of mafic lithologies, and liquid immiscibility. Geochemical studies on felsic lithologies from fast-spreading ridge systems imply that partial melting of previously hydrothermally altered mafic lithologies at the gabbro/dike transitions may play an important role (e.g., Wanless et al., 2010). For a detailed study of this process, we simulated experimentally anatexis at the gabbro/dike transition. In order to evaluate the potential of MORB contamination by anatectic melts, trace elements of the experimental melts were analyzed in-situ by applying secondary ion mass spectrometry (SIMS). As starting material we used rock powder (125-200 μm) of different hydrothermally altered dikes and basaltic hornfelses (so-called granoblastic dikes) from the base of the sheeted dike complex of the IODP site 1256 (East-Pacific Rise, EPR). Such lithologies are assumed to undergo partial melting due to an upward moving of the axial melt lens after replenishment, while granoblastic lithologies are regarded as restitic material of anatectic processes (France et al., 2010). Partial melting experiments under water-saturated conditions were performed in internally heated pressure vessels (IHPV) under conditions similar to those prevailing at the base of the sheeted dike complex (i.e. 100 MPa, 910 to 1030°C, fO2=ΔQFM+1). Our results show that melting of altered basalt with melt fractions less than 20 % (corresponding to temperatures ≤ 970°C) exhibit residual phases perfectly matching those observed in basalts with granoblastic texture (i.e. clinopyroxene, orthopyroxene, plagioclase, magnetite). Anatectic melts of these low degree melting experiments show trace element pattern which are very similar to those of natural dacites from the EPR

  18. Multiscale Models of Melting Arctic Sea Ice

    Science.gov (United States)

    2014-09-30

    1 Multiscale Models of Melting Arctic Sea Ice Kenneth M. Golden University of Utah, Department of Mathematics phone: (801) 581-6851...feedback has played a major role in the recent declines of the summer Arctic sea ice pack. However, understanding the evolution of melt ponds and sea...Models of Melting Arctic Sea Ice 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER

  19. Percolation blockage: A process that enables melt pond formation on first year Arctic sea ice

    Science.gov (United States)

    Polashenski, Chris; Golden, Kenneth M.; Perovich, Donald K.; Skyllingstad, Eric; Arnsten, Alexandra; Stwertka, Carolyn; Wright, Nicholas

    2017-01-01

    Melt pond formation atop Arctic sea ice is a primary control of shortwave energy balance in the Arctic Ocean. During late spring and summer, the ponds determine sea ice albedo and how much solar radiation is transmitted into the upper ocean through the sea ice. The initial formation of ponds requires that melt water be retained above sea level on the ice surface. Both theory and observations, however, show that first year sea ice is so highly porous prior to the formation of melt ponds that multiday retention of water above hydraulic equilibrium should not be possible. Here we present results of percolation experiments that identify and directly demonstrate a mechanism allowing melt pond formation. The infiltration of fresh water into the pore structure of sea ice is responsible for blocking percolation pathways with ice, sealing the ice against water percolation, and allowing water to pool above sea level. We demonstrate that this mechanism is dependent on fresh water availability, known to be predominantly from snowmelt, and ice temperature at melt onset. We argue that the blockage process has the potential to exert significant control over interannual variability in ice albedo. Finally, we suggest that incorporating the mechanism into models would enhance their physical realism. Full treatment would be complex. We provide a simple temperature threshold-based scheme that may be used to incorporate percolation blockage behavior into existing model frameworks.

  20. Impact Melt in Small Lunar Highlands Craters

    Science.gov (United States)

    Plescia, J. B.; Cintala, M. J.; Robinson, M. S.; Barnouin, O.; Hawke, B. R.

    2011-01-01

    Impact-melt deposits are a typical characteristic of complex impact craters, occurring as thick pools on the crater floor, ponds on wall terraces, veneers on the walls, and flows outside and inside the rim. Studies of the distribution of impact melt suggested that such deposits are rare to absent in and around small (km to sub-km), simple impact craters. noted that the smallest lunar crater observed with impact melt was approximately 750 m in diameter. Similarly, theoretical models suggest that the amount of melt formed is a tiny fraction (crater volume and thus significant deposits would not be expected for small lunar craters. LRO LROC images show that impact-melt deposits can be recognized associated with many simple craters to diameters down to approximately 200 m. The melt forms pools on the crater floor, veneer on the crater walls or ejecta outside the crater. Such melt deposits are relatively rare, and can be recognized only in some fresh craters. These observations indicate that identifiable quantities of impact melt can be produced in small impacts and the presence of such deposits shows that the material can be aggregated into recognizable deposits. Further, the present of such melt indicates that small craters could be reliably radiometrically dated helping to constrain the recent impact flux.

  1. Low Melt Height Solidification of Superalloys

    Science.gov (United States)

    Montakhab, Mehdi; Bacak, Mert; Balikci, Ercan

    2016-06-01

    Effect of a reduced melt height in the directional solidification of a superalloy has been investigated by two methods: vertical Bridgman (VB) and vertical Bridgman with a submerged baffle (VBSB). The latter is a relatively new technique and provides a reduced melt height ahead of the solidifying interface. A low melt height leads to a larger primary dendrite arm spacing but a lower mushy length, melt-back transition length, and porosity. The VBSB technique yields up to 38 pct reduction in the porosity. This may improve a component's mechanical strength especially in a creep-fatigue type dynamic loading.

  2. Solute Redistribution in Directional Melting Process

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@The solute redistribution in directional melting process is theoretically studied. Based on quantitative evaluations, uniform solute distribution in liquid and a quasi-steady solute distribution in solid are supposed. The discussion on the solute balance comes to a simple model for the solute redistribution in directional melting process. As an example, the variation of liquid composition during melting process of carbon steel is quantitatively evaluated using the model. Results show that the melting of an alloy starts at solidus temperature, but approaches the liquidus temperature after a very short transient process.

  3. Nuclear analysis and shielding optimisation in support of the ITER In-Vessel Viewing System design

    CERN Document Server

    Turner, A; Loughlin, M J; Ghani, Z; Hurst, G; Bue, A Lo; Mangham, S; Puiu, A; Zheng, S

    2014-01-01

    The In-Vessel Viewing System (IVVS) units proposed for ITER are deployed to perform in-vessel examination. During plasma operations, the IVVS is located beyond the vacuum vessel, with shielding blocks envisaged to protect components from neutron damage and reduce shutdown dose rate (SDR) levels. Analyses were conducted to determine the effectiveness of several shielding configurations. The neutron response of the system was assessed using global variance reduction techniques and a surface source, and shutdown dose rate calculations were undertaken using MCR2S. Unshielded, the absorbed dose to piezoelectric motors (PZT) was found to be below stable limits, however activation of the primary closure plate (PCP) was prohibitively high. A scenario with shielding blocks at probe level showed significantly reduced PCP contact dose rate, however still marginally exceeded port cell requirements. The addition of shielding blocks at the bioshield plug demonstrated PCP contact dose rates below project requirements. SDR l...

  4. Alignment of in-vessel components by metrology defined adaptive machining

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, David [ITER Organization, Route de Vinon sur Verdon, CS90 046, St Paul-lez-Durance (France); Bernard, Nathanaël [G2Métric, Launaguet 31140 (France); Mariani, Antony [Spatial Alignment Ltd., Witney (United Kingdom)

    2015-10-15

    Highlights: • Advanced metrology techniques developed for large volume high density in-vessel surveys. • Virtual alignment process employed to optimize the alignment of 440 blanket modules. • Auto-geometry construct, from survey data, using CAD proximity detection and orientation logic. • HMI developed to relocate blanket modules if customization limits on interfaces are exceeded. • Data export format derived for Catia parametric models, defining customization requirements. - Abstract: The assembly of ITER will involve the precise and accurate alignment of a large number of components and assemblies in areas where access will often be severely constrained and where process efficiency will be critical. One such area is the inside of the vacuum vessel where several thousand components shall be custom machined to provide the alignment references for in-vessel systems. The paper gives an overview of the process that will be employed; to survey the interfaces for approximately 3500 components then define and execute the customization process.

  5. In-Vessel Coil Material Failure Rate Estimates for ITER Design Use

    Energy Technology Data Exchange (ETDEWEB)

    L. C. Cadwallader

    2013-01-01

    The ITER international project design teams are working to produce an engineering design for construction of this large tokamak fusion experiment. One of the design issues is ensuring proper control of the fusion plasma. In-vessel magnet coils may be needed for plasma control, especially the control of edge localized modes (ELMs) and plasma vertical stabilization (VS). These coils will be lifetime components that reside inside the ITER vacuum vessel behind the blanket modules. As such, their reliability is an important design issue since access will be time consuming if any type of repair were necessary. The following chapters give the research results and estimates of failure rates for the coil conductor and jacket materials to be used for the in-vessel coils. Copper and CuCrZr conductors, and stainless steel and Inconel jackets are examined.

  6. Identification and evaluation of PWR in-vessel severe accident management strategies

    Energy Technology Data Exchange (ETDEWEB)

    Dukelow, J S [Pacific Northwest Lab., Richland, WA (United States); Harrison, D G [Jason Associates, Idaho Falls, ID (United States); Morgenstern, M [Battelle Human Affairs Research Center, Seattle, WA (United States)

    1992-03-01

    This reports documents work performed the NRC/RES Accident Management Guidance Program to evaluate possible strategies for mitigating the consequences of PWR severe accidents. The selection and evaluation of strategies was limited to the in-vessel phase of the severe accident, i.e., after the initiation of core degradation and prior to RPV failure. A parallel project at BNL has been considering strategies applicable to the ex-vessel phase of PWR severe accidents.

  7. Convective melting in a magma chamber: theory and numerical experiment.

    Science.gov (United States)

    Simakin, A.

    2012-04-01

    We present results of the numerical modeling of convective melting in a magma chamber in 2D. Model was pointed on the silicic system approximated with Qz-Fsp binary undersaturated with water. Viscosity was calculated as a function of the melt composition, temperature and crystal content and comprises for the pure melt 104.5-105.5 Pas. Lower boundary was taken thermally insulated in majority of the runs. Size of FEM (bilinear elements) grid for velocity is 25x25 cm and for the integration of the density term 8x8 cm. Melting of the chamber roof proceeds with the heat supply due to the chaotic thermo-compositional convection and conductive heat loose into melted substrate. We compare our numerical data with existing semi-analytical models. Theoretical studies of the assimilation rates in the magma chambers usually use theoretical semi-analytical model by Huppert and Sparks (1988) (e.g., Snyder, 2000). We find that this model has strong points: 1) Independence of the melting rate on the sill thickness (Ra>>Rac) 2) Independence of the convective heat transfer on the roof temperature 3) Determination of the exponential thermal boundary layer ahead of the melting front and weak points: 1) Ignoring the possibility of the crystallization without melting regime for narrow sills and dykes. 2)Neglecting of two-phase character of convection. 3)Ignoring of the strong viscosity variation near the melting front. Independence of convective flux from the sill size (at Ra>>Rac) allows reducing of computational domain to the geologically small size (10-15 m). Concept of exponential thermal boundary layer is also rather important. Length scale (L0) of this layer is related to the melting rate and thermal diffusivity coefficient kT as L0=kT/um and at the melting rate 10 m/yr becomes about 2 m. Such small scale implies that convective melting is very effective (small conductive heat loss) and part of the numerical domain filled with roof rocks can be taken small. In the H&S model

  8. Stress and Thermal Analysis of the In-Vessel RMP Coils in HL-2M

    Science.gov (United States)

    Cen, Yishun; Li, Qiang; Ding, Yonghua; Cai, Lijun; Jiang, Jiaming; Li, Guangsheng; Liu, Yi

    2013-09-01

    A set of in-vessel resonant magnetic perturbation (RMP) coils for MHD instability suppression is proposed for the design of a HL-2M tokamak. Each coil is to be fed with a current of up to 5 kA, operated in a frequency range from DC to about 1 kHz. Stainless steel (SS) jacketed mineral insulated cables are proposed for the conductor of the coils. In-vessel coils must withstand large electromagnetic (EM) and thermal loads. The support, insulation and vacuum sealing in a very limited space are crucial issues for engineering design. Hence finite element calculations are performed to verify the design, optimize the support by minimizing stress caused by EM forces on the coil conductors and work out the temperature rise occurring on the coil in different working conditions, the corresponding thermal stress caused by the thermal expansion of materials is evaluated to be allowable. The techniques to develop the in-vessel RMP coils, such as support, insulation and cooling, are discussed.

  9. Design, Analysis and R&D of the EAST In-Vessel Components

    Institute of Scientific and Technical Information of China (English)

    YAO Damao; LIU Xufeng; CAO Lei; ZHOU Zibo; CHEN Junling; MAO Xinqiao; WANG Shengming; ZHU Ning; WENG Peide; WAN Yuanxi; BAO Liman; LI Jiangang; SONG Yuntao; CHEN Wenge; DU Shijun; HU Qingsheng; WEI Jing; XIE Han

    2008-01-01

    In-vessel components are important parts of the EAST superconducting tokamak. They include the plasma facing components, passive plates, cryo-pumps, in-vessel coils, etc. The structural design, analysis and related R&D have been completed. The divertor is designed in an up-down symmetric configuration to accommodate both double null and single null plasma operation. Passive plates are used for plasma movement control. In-vessel coils are used for the active control of plasma vertical movements. Each cryo-pump can provide an approximately 45 m3/s pumping rate at a pressure of 10-1 Pa for particle exhaust. Analysis shows that, when a plasma current of 1 MA disrupts in 3 ms, the EM loads caused by the eddy current and the halo current in a vertical displacement event (VDE) will not generate an unacceptable stress on the divertor structure. The bolted divertor thermal structure with an active cooling system can sustain a load of 2 MW/m2 up to a 60 s operation if the plasma facing surface temperature is limited to 1500℃. Thermal testing and structural optimization testing were conducted to demonstrate the analysis results.

  10. Ocean Properties and Submarine Melt of Ice Shelves in a High-Arctic Fiord (Milne Fiord)

    Science.gov (United States)

    Hamilton, A.; Mueller, D.; Laval, B.

    2014-12-01

    The role of ambient stratification, the vertical distribution of heat, and fiord circulation on submarine melt rates in glacial fiords in the Canadian Arctic are largely unknown despite recent widespread collapse of ice shelves in this region. A 3-year field study was conducted to investigate ocean influence on ice loss from an ice shelf and glacier tongue in Milne Fiord (82oN), Ellesmere Island. Direct ocean observations of the sub-ice cavities from through-ice profiles showed a vertically stratified water column consisting of a perennial fresh ice-dammed epishelf lake at the surface, above cold relatively fresh Polar Water, and warm saline waters from the upper halocline of the Atlantic layer at depth. The broad continental shelf and a topographic sill prevented the warmest waters of the Atlantic layer from entering the 450 m deep fiord. Meltwater concentrations were highest near the glacier grounding line, with meltwater exported at depth due to the strong ambient stratification. There was little evidence of increased buoyancy-driven melt in summer from subglacial discharge as observed in sub-Arctic fiords (e.g. southern Greenland), suggesting that circulation in high-latitude fiords is largely melt-driven convection with less pronounced seasonality. Basal melt rates estimated using three methods, meltwater flux, divergence of ice flux, and an ocean thermodynamic model, were broadly consistent. Average melt rates of 0.75 ± 0.46 m a-1 and 1.14 ± 0.83 m a-1 were found for the Milne Ice Shelf and Milne Glacier Tongue, respectively, although showed high spatial variability. The highest melt rates (~4 m a-1) were found near the glacier grounding line and were driven by warm upper halocline waters. Similar melt rates occurred in near-surface waters driven by solar heating of the epishelf lake, enhancing melt along the margins of the glacier tongue and the landward edge of the ice shelf. The Milne Ice Shelf and Milne Glacier Tongue are in a state of negative mass

  11. Melting and Sintering of Ashes

    DEFF Research Database (Denmark)

    Hansen, Lone Aslaug

    1997-01-01

    The thesis contains an experimental study of the fusion and sintering of ashes collected during straw and coal/straw co-firing.A laboratory technique for quantitative determination of ash fusion has been developed based on Simultaneous Thermal Analysis (STA). By means of this method the fraction...... of melt in the investigated ashes has been determined as a function of temperature. Ash fusion results have been correlated to the chemical and mineralogical composition of the ashes, to results from a standard ash fusion test and to results from sintering experiments. Furthermore, the ash fusion results......-firing, the model only had a qualitative agreement with the measured ash deposit formation rates.Sintering measurements were carried out by means of compression strength testing of ash pellets. This method showed to not be applicable for the salt rich fly ash derived from straw combustion. For the fly ashes...

  12. 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....

  13. 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....

  14. Do Melt Inclusions Answer Big Questions?

    Science.gov (United States)

    Hofmann, A. W.; Sobolev, A. V.

    2009-12-01

    In a pioneering paper, Sobolev and Shimizu (1993) demonstrated the existence of ultra-depleted melt inclusions in olivine phenocrysts in MORB. They interpreted these as evidence for the preservation of parental melts formed by progressive near-fractional melting. Subsequently many cases have been described where melt inclusions from single basalt samples display enormous chemical and isotopic heterogeneity. The interpretation of these observations hinges critically on whether such melt inclusions can faithfully preserve primary or parental melt composition. If they do, melt inclusion data can truly answer big questions from small-scale observations. If they do not, they answer rather small questions. Favoring the second possibility, Danyushevsky et al. (2004) have suggested that much of the observed variability of highly incompatible trace elements in melt inclusions “may not represent geologically significant melts, but instead reflect localized, grain-scale reaction processes within the magmatic plumbing system.” We disagree and show that this mechanism cannot, for example, explain isotopic heterogeneity measured in several suites of melt inclusions, nor does it not account for the presence of ultra-depleted melts and "ghost" plagioclase signatures in other inclusions. More recently, Spandler et al. (2007) have suggested on the basis of experimental evidence that diffusion rates for REE in olivine are so rapid that parental melt compositions in melt inclusions are rapidly falsified by diffusional exchange with (evolved) host lava. We show that the very fact that extreme chemical and isotopic heterogeneities are routinely preserved in melt inclusions demonstrates that this conclusion is unwarranted, either because residence times of the olivine phenocrysts are much shorter than assumed by Spandler et al. or because the high experimental diffusion rates are caused by an unknown experimental artifact. Although there is no obvious flaw in design and execution of

  15. Development of in-vessel neutron flux monitor equipped with microfission chambers to withstand the extreme ITER environment

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, Masao, E-mail: ishikawa.masao@jaea.go.jp; Takeda, Keigo; Itami, Kiyoshi

    2016-11-01

    Highlights: • The in-vessel components of MFC system must withstand the extreme ITER environment. • To verify this, the thermal cycle test and the vibration tests were conducted. • Both tests were conducted under much severer conditions than ITER environment. • Soundness verification tests after the tests indicated that no problemswere found. • It is shown that the in-vessel component is sufficiently robust ITER environment. - Abstract: Via thermal cycling and vibration tests, this study aims to demonstrate that the in-vessel components of the microfission chamber (MFC) system can withstand the extreme International Thermonuclear Experimental Reactor (ITER) environment. In thermal cycle tests, the signal cable of the device was bent into a smaller radius and it was given more bends than those in its actual configuration within ITER. A faster rate of temperature change than that under the typical ITER baking scenario was then imposed on in-vessel components. For the vibration tests, strong 10 G vibrational accelerations with frequencies ranging from 30 Hz to 2000 Hz were imposed to the detector and the connector of the in-vessel components to simulate various types of electromagnetic events. Soundness verification tests of the in-vessel components conducted after thermal cycling and vibration testing indicated that problems related to the signal transmission cable functioning were not found. Thus, it was demonstrated that the in-vessel components of the MFC can withstand the extreme environment within ITER.

  16. Melt production and magma emplacement: What use are they?

    Science.gov (United States)

    Nimmo, F.

    2003-04-01

    I will review the processes of melt production and magma emplacement and address two questions: how do these processes affect planetary evolution?; and what can we learn from observing them, both now and in the future? Melt production is primarily controlled by the temperature of the planetary interior. The extraction of melt from silicate mantles has a number of effects. Firstly, it advects heat (e.g. Io, Venus?). Secondly, it segregates radiogenic materials into the crust, thus cooling the mantle (e.g. Mars, Earth). Thirdly, it removes volatiles from the interior (e.g. Venus, Mars). Recognition that melting is occurring gives us information about likely conditions inside the planet. Models of melt generation by convective upwelling have been used to constrain the interior properties of the Earth, Venus and Mars. Melting during tidal heating (Io) or accretion is less well understood. Magma emplacement is primarily controlled by the density of the magma and the surrounding material. Extrusive activity is likely for high volatile concentrations or low crustal densities. Water is particularly difficult to erupt, since (unlike silicates) the melt is denser than the solid. Different styles of magma emplacement are observed: voluminous surface flows and volcanic edifices of various kinds (ubiquitous); giant radiating dyke swarms (Earth, Venus, Mars); intrusive sills and diapirs (Earth, Venus?, Mars?, Europa?). The extrusive emplacement of magma will cause resurfacing, and is thus easily detected. The release of volatiles during emplacement may have local (e.g. Laki) or global (Venus? Mars?) effects on climate and atmosphere. Intrusive emplacement is harder to detect, but may interact with local volatiles to create unusual landforms (Earth, Mars). The style and volume of emplacement is a useful diagnostic tool. The morphology of lava flows gives information about the rheology and composition of the flow material (e.g. Venus, Miranda). Observations of dykes may be used to

  17. A benchmark initiative on mantle convection with melting and melt segregation

    Science.gov (United States)

    Schmeling, Harro; Dannberg, Juliane; Dohmen, Janik; Kalousova, Klara; Maurice, Maxim; Noack, Lena; Plesa, Ana; Soucek, Ondrej; Spiegelman, Marc; Thieulot, Cedric; Tosi, Nicola; Wallner, Herbert

    2016-04-01

    In recent years a number of mantle convection models have been developed which include partial melting within the asthenosphere, estimation of melt volumes, as well as melt extraction with and without redistribution at the surface or within the lithosphere. All these approaches use various simplifying modelling assumptions whose effects on the dynamics of convection including the feedback on melting have not been explored in sufficient detail. To better assess the significance of such assumptions and to provide test cases for the modelling community we carry out a benchmark comparison. The reference model is taken from the mantle convection benchmark, cases 1a to 1c (Blankenbach et al., 1989), assuming a square box with free slip boundary conditions, the Boussinesq approximation, constant viscosity and Rayleigh numbers of 104 to 10^6. Melting is modelled using a simplified binary solid solution with linearly depth dependent solidus and liquidus temperatures, as well as a solidus temperature depending linearly on depletion. Starting from a plume free initial temperature condition (to avoid melting at the onset time) five cases are investigated: Case 1 includes melting, but without thermal or dynamic feedback on the convection flow. This case provides a total melt generation rate (qm) in a steady state. Case 2 is identical to case 1 except that latent heat is switched on. Case 3 includes batch melting, melt buoyancy (melt Rayleigh number Rm) and depletion buoyancy, but no melt percolation. Output quantities are the Nusselt number (Nu), root mean square velocity (vrms), the maximum and the total melt volume and qm approaching a statistical steady state. Case 4 includes two-phase flow, i.e. melt percolation, assuming a constant shear and bulk viscosity of the matrix and various melt retention numbers (Rt). These cases are carried out using the Compaction Boussinseq Approximation (Schmeling, 2000) or the full compaction formulation. For cases 1 - 3 very good agreement

  18. Bubble Formation in Basalt-like Melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Keding, Ralf; Yue, Yuanzheng

    2011-01-01

    The effect of the melting temperature on bubble size and bubble formation in an iron bearing calcium aluminosilicate melt is studied by means of in-depth images acquired by optical microscopy. The bubble size distribution and the total bubble volume are determined by counting the number of bubble...

  19. Bubble Formation in Basalt-like Melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Keding, Ralf; Yue, Yuanzheng

    2011-01-01

    The effect of the melting temperature on bubble size and bubble formation in an iron bearing calcium aluminosilicate melt is studied by means of in-depth images acquired by optical microscopy. The bubble size distribution and the total bubble volume are determined by counting the number of bubbles...

  20. Disordering and Melting of Aluminum Surfaces

    DEFF Research Database (Denmark)

    Stoltze, Per; Nørskov, Jens Kehlet; Landman, U.

    1988-01-01

    We report on a molecular-dynamics simulation of an Al(110) surface using the effective-medium theory to describe the interatomic interactions. The surface region is found to start melting ≅200 K below the bulk melting temperature with a gradual increase in the thickness of the disordered layer as...

  1. Uniaxial Elongational viscosity of bidisperse polystyrene melts

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

    2006-01-01

    The startup and steady uniaxial elongational viscosity have been measured for three bidisperse polystyrene (PS) melts, consisting of blends of monodisperse PS with molecular weights of 52 kg/mole or 103 kg/mole and 390 kg/mole. The bidisperse melts have a maximum in the steady elongational...

  2. Uniaxial Elongational viscosity of bidisperse polystyrene melts

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

    2006-01-01

    The startup and steady uniaxial elongational viscosity have been measured for three bidisperse polystyrene (PS) melts, consisting of blends of monodisperse PS with molecular weights of 52 kg/mole or 103 kg/mole and 390 kg/mole. The bidisperse melts have a maximum in the steady elongational viscos...

  3. Purification of Niobium by Electron Beam Melting

    Science.gov (United States)

    Sankar, M.; Mirji, K. V.; Prasad, V. V. Satya; Baligidad, R. G.; Gokhale, A. A.

    2016-06-01

    Pure niobium metal, produced by alumino-thermic reduction of niobium oxide, contains various impurities which need to be reduced to acceptable levels to obtain aerospace grade purity. In the present work, an attempt has been made to refine niobium metals by electron beam drip melting technique to achieve purity confirming to the ASTM standard. Input power to the electron gun and melt rate were varied to observe their combined effect on extend of refining and loss of niobium. Electron beam (EB) melting is shown to reduce alkali metals, trace elements and interstitial impurities well below the specified limits. The reduction in the impurities during EB melting is attributed to evaporation and degassing due to the combined effect of high vacuum and high melt surface temperature. The % removal of interstitial impurities is essentially a function of melt rate and input power. As the melt rate decreases or input power increases, the impurity levels in the solidified niobium ingot decrease. The EB refining process is also accompanied by considerable amount of niobium loss, which is attributed to evaporation of pure niobium and niobium sub-oxide. Like other impurities, Nb loss increases with decreasing melt rate or increase in input power.

  4. Shock-induced melting and rapid solidification

    Energy Technology Data Exchange (ETDEWEB)

    Nellis, W.J.; Gourdin, W.H.; Maple, M.B.

    1987-08-01

    Model calculations are presented to estimate that approx.50 GPa is required to completely shock melt metal powders with quenching at rates up to 10/sup 8/ K/s. Experiments are discussed for powders of a Cu-Zr alloy compacted in the usual way at 16 GPa and melted by shocking to 60 GPa. 12 refs.

  5. Indirect measurement of interfacial melting from macroscopic ice observations.

    Science.gov (United States)

    Saruya, Tomotaka; Kurita, Kei; Rempel, Alan W

    2014-06-01

    Premelted water that is adsorbed to particle surfaces and confined to capillary regions remains in the liquid state well below the bulk melting temperature and can supply the segregated growth of ice lenses. Using macroscopic measurements of ice-lens initiation position in step-freezing experiments, we infer how the nanometer-scale thicknesses of premelted films depend on temperature depression below bulk melting. The interfacial interactions between ice, liquid, and soda-lime glass particles exhibit a power-law behavior that suggests premelting in our system is dominated by short-range electrostatic forces. Using our inferred film thicknesses as inputs to a simple force-balance model with no adjustable parameters, we obtain good quantitative agreement between numerical predictions and observed ice-lens thickness. Macroscopic observations of lensing behavior have the potential as probes of premelting behavior in other systems.

  6. Development of in-vessel type control rod drive mechanism for a innovative small reactor (Contract research)

    Energy Technology Data Exchange (ETDEWEB)

    Yoritsune, Tsutomu; Ishida, Toshihisa [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    Although the control rod drive mechanism of an existing large scale light water reactor is generally installed outside the reactor vessel, an in-vessel type control rod drive mechanism (INV-CRDM) is installed inside the reactor vessel. The INV-CRDM contributes to compactness and simplicity of the reactor system, and it can eliminate the possibility of a rod ejection accident. Therefore, INV-CRDM is an important technology adopted in an innovative small reactor. Japan Atomic Energy Research Institute (JAERI) has developed this type of CRDM driven by an electric motor, which can work under high temperature and high pressure water for the advanced marine reactor. On the basis of this research result, a driving motor coil and a bearing were developed to be used under the high temperature steam, severe condition for an innovative small reactor. About the driving motor, we manufactured the driving motor available for high temperature steam and carried out performance test under room temperature atmosphere to confirm the electric characteristic and coolability of the driving coil. With these test results and the past test results under high temperature water, we analyzed and evaluated the electric performance and coolability of the driving coil under high temperature steam. Concerning bearing, we manufactured the test pieces using some candidate material for material characteristic test and carried out the rolling wear test under high temperature steam to select the material. Consequently, we confirmed that performance of the driving coil for the advanced type driving motor, is enough to be used under high temperature steam. And, we evaluated the performance of the bearing and selected the material of the bearing, which can be used under high temperature steam. From these results, we have obtained the prospect that the INV-CRDM can be used for an innovative small reactor under steam atmosphere could be developed. (author)

  7. Development of in-vessel type control rod drive mechanism for a innovative small reactor (Contract research)

    Energy Technology Data Exchange (ETDEWEB)

    Yoritsune, Tsutomu; Ishida, Toshihisa [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    Although the control rod drive mechanism of an existing large scale light water reactor is generally installed outside the reactor vessel, an in-vessel type control rod drive mechanism (INV-CRDM) is installed inside the reactor vessel. The INV-CRDM contributes to compactness and simplicity of the reactor system, and it can eliminate the possibility of a rod ejection accident. Therefore, INV-CRDM is an important technology adopted in an innovative small reactor. Japan Atomic Energy Research Institute (JAERI) has developed this type of CRDM driven by an electric motor, which can work under high temperature and high pressure water for the advanced marine reactor. On the basis of this research result, a driving motor coil and a bearing were developed to be used under the high temperature steam, severe condition for an innovative small reactor. About the driving motor, we manufactured the driving motor available for high temperature steam and carried out performance test under room temperature atmosphere to confirm the electric characteristic and coolability of the driving coil. With these test results and the past test results under high temperature water, we analyzed and evaluated the electric performance and coolability of the driving coil under high temperature steam. Concerning bearing, we manufactured the test pieces using some candidate material for material characteristic test and carried out the rolling wear test under high temperature steam to select the material. Consequently, we confirmed that performance of the driving coil for the advanced type driving motor, is enough to be used under high temperature steam. And, we evaluated the performance of the bearing and selected the material of the bearing, which can be used under high temperature steam. From these results, we have obtained the prospect that the INV-CRDM can be used for an innovative small reactor under steam atmosphere could be developed. (author)

  8. The Impact Of Snow Melt On Surface Runoff Of Sava River In Slovenia

    Science.gov (United States)

    Horvat, A.; Brilly, M.; Vidmar, A.; Kobold, M.

    2009-04-01

    Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Snow remains on the ground until it melts or sublimates. Spring snow melt is a major source of water supply to areas in temperate zones near mountains that catch and hold winter snow, especially those with a prolonged dry summer. In such places, water equivalent is of great interest to water managers wishing to predict spring runoff and the water supply of cities downstream. In temperate zone like in Slovenia the snow melts in the spring and contributes certain amount of water to surface flow. This amount of water can be great and can cause serious floods in case of fast snow melt. For this reason we tried to determine the influence of snow melt on the largest river basin in Slovenia - Sava River basin, on surface runoff. We would like to find out if snow melt in Slovenian Alps can cause spring floods and how serious it can be. First of all we studied the caracteristics of Sava River basin - geology, hydrology, clima, relief and snow conditions in details for each subbasin. Furtermore we focused on snow and described the snow phenomenom in Slovenia, detailed on Sava River basin. We collected all available data on snow - snow water equivalent and snow depth. Snow water equivalent is a much more useful measurement to hydrologists than snow depth, as the density of cool freshly fallen snow widely varies. New snow commonly has a density of between 5% and 15% of water. But unfortunately there is not a lot of available data of SWE available for Slovenia. Later on we compared the data of snow depth and river runoff for some of the 40 winter seasons. Finally we analyzed the use of satellite images for Slovenia to determine the snow cover for hydrology reason. We concluded that snow melt in Slovenia does not have a greater influence on Sava River flow. The snow cover in Alps can melt fast due to higher temperatures but the water distributes

  9. Water

    CSIR Research Space (South Africa)

    Van Wyk, Llewellyn V

    2010-08-01

    Full Text Available Water scarcity is without a doubt on of the greatest threats to the human species and has all the potential to destabilise world peace. Falling water tables are a new phenomenon. Up until the development of steam and electric motors, deep groudwater...

  10. Size-dependent melting of Bi nanoparticles

    Science.gov (United States)

    Olson, E. A.; Efremov, M. Yu.; Zhang, M.; Zhang, Z.; Allen, L. H.

    2005-02-01

    Nanocalorimetry was used to investigate the melting of Bi nanoparticles. The particles were formed by evaporating Bi onto a silicon nitride substrate, which was then heated. The particles self-assemble into truncated spherical particles. Below 5-nm average film thickness, mean particle sizes increased linearly with deposition thickness but increased rapidly for 10-nm-thick films. As expected, small particles were found to exhibit size-dependent melting temperatures less than the bulk melting temperature (e.g., ΔT =67K for a 3-nm radius particle). The measured melting temperatures for particles below ˜7nm in radius, however, were ˜50K above the value predicted by the homogeneous melting model. We discuss this discrepancy in terms of a possible size-dependent crystal structure change and the superheating of the solid phase.

  11. Nanotexturing of surfaces to reduce melting point.

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Ernest J.; Zubia, David (University of Texas at El Paso El Paso, TX); Mireles, Jose (Universidad Aut%C3%94onoma de Ciudad Ju%C3%94arez Ciudad Ju%C3%94arez, Mexico); Marquez, Noel (University of Texas at El Paso El Paso, TX); Quinones, Stella (University of Texas at El Paso El Paso, TX)

    2011-11-01

    This investigation examined the use of nano-patterned structures on Silicon-on-Insulator (SOI) material to reduce the bulk material melting point (1414 C). It has been found that sharp-tipped and other similar structures have a propensity to move to the lower energy states of spherical structures and as a result exhibit lower melting points than the bulk material. Such a reduction of the melting point would offer a number of interesting opportunities for bonding in microsystems packaging applications. Nano patterning process capabilities were developed to create the required structures for the investigation. One of the technical challenges of the project was understanding and creating the specialized conditions required to observe the melting and reshaping phenomena. Through systematic experimentation and review of the literature these conditions were determined and used to conduct phase change experiments. Melting temperatures as low as 1030 C were observed.

  12. Melt Rate Improvement for DWPF MB3: Melt Rate Furnace Testing

    Energy Technology Data Exchange (ETDEWEB)

    Stone, M.E.

    2001-07-24

    The Defense Waste Processing Facility (DWPF) would like to increase its canister production rate. The goal of this study is to improve the melt rate in DWPF specifically for Macrobatch 3. However, the knowledge gained may result in improved melting efficiencies translating to future DWPF macrobatches and in higher throughput for other Department of Energy's (DOE) melters. Increased melting efficiencies decrease overall operational costs by reducing the immobilization campaign time for a particular waste stream. For melt rate limited systems, a small increase in melting efficiency translates into significant hard dollar savings by reducing life cycle operational costs.

  13. Partitioning coefficients between olivine and silicate melts

    Science.gov (United States)

    Bédard, J. H.

    2005-08-01

    Variation of Nernst partition coefficients ( D) between olivine and silicate melts cannot be neglected when modeling partial melting and fractional crystallization. Published natural and experimental olivine/liquidD data were examined for covariation with pressure, temperature, olivine forsterite content, and melt SiO 2, H 2O, MgO and MgO/MgO + FeO total. Values of olivine/liquidD generally increase with decreasing temperature and melt MgO content, and with increasing melt SiO 2 content, but generally show poor correlations with other variables. Multi-element olivine/liquidD profiles calculated from regressions of D REE-Sc-Y vs. melt MgO content are compared to results of the Lattice Strain Model to link melt MgO and: D0 (the strain compensated partition coefficient), EM3+ (Young's Modulus), and r0 (the size of the M site). Ln D0 varies linearly with Ln MgO in the melt; EM3+ varies linearly with melt MgO, with a dog-leg at ca. 1.5% MgO; and r0 remains constant at 0.807 Å. These equations are then used to calculate olivine/liquidD for these elements using the Lattice Strain Model. These empirical parameterizations of olivine/liquidD variations yield results comparable to experimental or natural partitioning data, and can easily be integrated into existing trace element modeling algorithms. The olivine/liquidD data suggest that basaltic melts in equilibrium with pure olivine may acquire small negative Ta-Hf-Zr-Ti anomalies, but that negative Nb anomalies are unlikely to develop. Misfits between results of the Lattice Strain Model and most light rare earth and large ion lithophile partitioning data suggest that kinetic effects may limit the lower value of D for extremely incompatible elements in natural situations characterized by high cooling/crystallization rates.

  14. Melt and Chemical Transport in the Mantle: Insights from Deglaciation-Induced Melting Perturbations in Iceland

    Science.gov (United States)

    Eason, D. E.; Ito, G.; Sinton, J. M.

    2011-12-01

    Eruptive products represent a time-averaged view of the melting region and melt migration processes, making numerous fundamental parameters of the melt system difficult to constrain. Temporal and spatial variations in melting provide potential windows into this obscure region of the Earth by preferentially sampling melts from different regions of the mantle or mixing melts over different length-scales. We present a newly extended geochemical time series from the Western Volcanic Zone (WVZ) of Iceland, which experienced a short-lived melting perturbation due to glacial unloading during the last major deglaciation (~15-10 ka). Glacial unloading during this period led to increased degrees of melting particularly in the shallow mantle, which is manifest as an observed increase in volcanic production up to 30 times the steady-state value, decreased levels of highly to moderately incompatible element ratios (e.g., a 35-50% decrease in Nb/Y, with the greatest change occurring in the northernmost WVZ), and elevated SiO2 and CaO concentrations (~0.8 wt. % and ~1.9 wt. % increase in average oxide concentrations respectively) during and immediately following deglaciation. Although eruptive productivity returns to steady-state values within ~3000 yr following deglaciation, the incompatible element concentrations in erupted lavas gradually increase throughout the post-glacial period. We exploit this short-lived melting perturbation to examine and constrain knowledge of fundamental characteristics of melt generation and transport, including mantle permeability, melt ascent rates, depth-dependent melting functions (dF/dP), and the nature of chemical transport and melt mixing in the system. Using conservation equations describing the generation and porous flow of melt in a viscous matrix, we model melt migration in the mantle during and after ice sheet removal, as well as trace element transport for both equilibrium and disequilibrium transport end members. The predicted

  15. Evaluation of Melt Behavior with initial Melt Velocity under SFR Severe Accidents

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Hyo; Bang, In Cheol [UNIST, Ulsan (Korea, Republic of); Jerng, Dong Wook [Chung-Ang Univ, Seoul (Korea, Republic of)

    2015-10-15

    In the current Korean sodium-cooled fast reactor (SFR) program, early dispersion of the molten metallic fuel within a subchannel is suggested as one of the inherent safety strategies for the initiating phase of hypothetical core disruptive accident (HCDA). The safety strategy provides negative reactivity driven by the melt dispersal, so it could reduce the possibility of the recriticality event under a severe triple or more fault scenario for SFR. Since the behavior of the melt dispersion is unpredictable, it depends on the accident condition, particularly core region. While the voided coolant channel region is usually developed in the inner core, the unvoided coolant channel region is formed in the outer core. It is important to confirm the fuel dispersion with the core region, but there are not sufficient existing studies for them. From the existing studies, the coolant vapor pressure is considered as one of driving force to move the melt towards outside of the core. There is a complexity of the phenomena during intermixing of the melt with the coolant after the horizontal melt injections. It is too difficult to understand the several combined mechanisms related to the melt dispersion and the fragmentation. Thus, it could be worthwhile to study the horizontal melt injections at lower temperature as a preliminary study in order to identify the melt dispersion phenomena. For this reason, it is required to clarify whether the coolant vapor pressure is the driving force of the melt dispersion with the core region. The specific conditions to be well dispersed for the molten metallic fuel were discussed in the experiments with the simulant materials. The each melt behavior was compared to evaluate the melt dispersion under the coolant void condition and the boiling condition. As the results, the following results are remarked: 1. The upward melt dispersion did not occur for a given melt and coolant temperature in the nonboiling range. Over current range of conditions

  16. Water

    Directory of Open Access Journals (Sweden)

    E. Sanmuga Priya

    2017-05-01

    Full Text Available Phytoremediation through aquatic macrophytes treatment system (AMATS for the removal of pollutants and contaminants from various natural sources is a well established environmental protection technique. Water hyacinth (Eichhornia crassipes, a worst invasive aquatic weed has been utilised for various research activities over the last few decades. The biosorption capacity of the water hyacinth in minimising various contaminants present in the industrial wastewater is well studied. The present review quotes the literatures related to the biosorption capacity of the water hyacinth in reducing the concentration of dyestuffs, heavy metals and minimising certain other physiochemical parameters like TSS (total suspended solids, TDS (total dissolved solids, COD (chemical oxygen demand and BOD (biological oxygen demand in textile wastewater. Sorption kinetics through various models, factors influencing the biosorption capacity, and role of physical and chemical modifications in the water hyacinth are also discussed.

  17. Viscosity of ring polymer melts

    KAUST Repository

    Pasquino, Rossana

    2013-10-15

    We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as a function of the number of entanglements Z. In the unentangled regime η0,linear/η 0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear/ η0,ring = 2. In the entanglement regime, the Z-dependence of ring viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1 < Z < 20, η0,linear/η0,ring ∼ Z 1.2±0.3, is weaker than the scaling prediction (η0,linear/η0,ring ∼ Z 1.6±0.3) and the simulations (η0,linear/ η0,ring ∼ Z2.0±0.3). Nevertheless, the present collection of state-of-the-art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year-old problem. © 2013 American Chemical Society.

  18. A 25-year Simulation of Snow Deposition and Melt over a Semiarid Mountain Catchment

    Science.gov (United States)

    Marks, D. G.; Reba, M. L.; Winstral, A. H.; Kumar, M.

    2009-12-01

    Both urban and agricultural systems in the mountains of the western US are water limited, and nearly all water in the region comes from melting snow. Over the last 20-30 years climate warming in western North America has resulted in a critical shift in patterns of snow deposition and melt. A carefully collected, processed, and validated meteorological dataset for the 1984 - 2008 water years was assembled for a headwater catchment within the Reynolds Creek Experimental Watershed in the Owyhee Mountains of Idaho. These data are used to force the Isnobal energy balance snow model to simulate patterns of snow deposition and melt over the catchment for the 25-year period. The simulation period includes both the highest (1984) and lowest (1992) snow seasons, along with a high degree of inter-annual variability. Results indicate statistically significant trend toward more rain and less snow, earlier melt, and reduced summer streamflow. In this region nearly all precipitation occurs during winter and spring, with very dry summer and fall seasons. Earlier melt and more winter rain will negatively impact growing season water supplies in the region even if precipitation is unchanged.

  19. Experimental and theoretical evidence for bilayer-by-bilayer surface melting of crystalline ice

    Science.gov (United States)

    Sánchez, M. Alejandra; Kling, Tanja; Ishiyama, Tatsuya; van Zadel, Marc-Jan; Mezger, Markus; Jochum, Mara N.; Cyran, Jenée D.; Smit, Wilbert J.; Bakker, Huib J.; Shultz, Mary Jane; Morita, Akihiro; Donadio, Davide; Nagata, Yuki; Bonn, Mischa; Backus, Ellen H. G.

    2017-01-01

    On the surface of water ice, a quasi-liquid layer (QLL) has been extensively reported at temperatures below its bulk melting point at 273 K. Approaching the bulk melting temperature from below, the thickness of the QLL is known to increase. To elucidate the precise temperature variation of the QLL, and its nature, we investigate the surface melting of hexagonal ice by combining noncontact, surface-specific vibrational sum frequency generation (SFG) spectroscopy and spectra calculated from molecular dynamics simulations. Using SFG, we probe the outermost water layers of distinct single crystalline ice faces at different temperatures. For the basal face, a stepwise, sudden weakening of the hydrogen-bonded structure of the outermost water layers occurs at 257 K. The spectral calculations from the molecular dynamics simulations reproduce the experimental findings; this allows us to interpret our experimental findings in terms of a stepwise change from one to two molten bilayers at the transition temperature. PMID:27956637

  20. Slab melting beneath the Cascades Arc driven by dehydration of altered oceanic peridotite

    Science.gov (United States)

    Walowski, Kristina J; Wallace, Paul J.; Hauri, E.H.; Wada, I.; Clynne, Michael A.

    2015-01-01

    Water is returned to Earth’s interior at subduction zones. However, the processes and pathways by which water leaves the subducting plate and causes melting beneath volcanic arcs are complex; the source of the water—subducting sediment, altered oceanic crust, or hydrated mantle in the downgoing plate—is debated; and the role of slab temperature is unclear. Here we analyse the hydrogen-isotope and trace-element signature of melt inclusions in ash samples from the Cascade Arc, where young, hot lithosphere subducts. Comparing these data with published analyses, we find that fluids in the Cascade magmas are sourced from deeper parts of the subducting slab—hydrated mantle peridotite in the slab interior—compared with fluids in magmas from the Marianas Arc, where older, colder lithosphere subducts. We use geodynamic modelling to show that, in the hotter subduction zone, the upper crust of the subducting slab rapidly dehydrates at shallow depths. With continued subduction, fluids released from the deeper plate interior migrate into the dehydrated parts, causing those to melt. These melts in turn migrate into the overlying mantle wedge, where they trigger further melting. Our results provide a physical model to explain melting of the subducted plate and mass transfer from the slab to the mantle beneath arcs where relatively young oceanic lithosphere is subducted.

  1. Performance assessment of the antenna setup for the ITER plasma position reflectometry in-vessel systems

    Science.gov (United States)

    Varela, P.; Belo, J. H.; Quental, P. B.

    2016-11-01

    The design of the in-vessel antennas for the ITER plasma position reflectometry diagnostic is very challenging due to the need to cope both with the space restrictions inside the vacuum vessel and with the high mechanical and thermal loads during ITER operation. Here, we present the work carried out to assess and optimise the design of the antenna. We show that the blanket modules surrounding the antenna strongly modify its characteristics and need to be considered from the early phases of the design. We also show that it is possible to optimise the antenna performance, within the design restrictions.

  2. Performance assessment of the antenna setup for the ITER plasma position reflectometry in-vessel systems.

    Science.gov (United States)

    Varela, P; Belo, J H; Quental, P B

    2016-11-01

    The design of the in-vessel antennas for the ITER plasma position reflectometry diagnostic is very challenging due to the need to cope both with the space restrictions inside the vacuum vessel and with the high mechanical and thermal loads during ITER operation. Here, we present the work carried out to assess and optimise the design of the antenna. We show that the blanket modules surrounding the antenna strongly modify its characteristics and need to be considered from the early phases of the design. We also show that it is possible to optimise the antenna performance, within the design restrictions.

  3. Cold Model Investigations of Melting of Ice in a Gas-Stirred Vessel

    Science.gov (United States)

    Shukla, Ajay Kumar; Dmitry, Ryabov; Volkova, Olena; Scheller, Piotr R.; Deo, Brahma

    2011-02-01

    The melting of steel scrap in high temperature liquid iron melt is investigated by conducting cold model experiments of the melting of ice sample of different geometries and sizes in an argon-stirred vessel containing water. The melting process of ice samples is observed using a high-speed camera. Design of experiments is based on similarity criteria. The relationships between non-dimensional groups related to heat transfer (Nu, Re, Pr, and Gr) are derived for different experimental conditions. The results are compared with those reported in the literature. The heat transfer coefficient is estimated as a function of mixing power and is found to be in good agreement with the calculated values obtained by using reported relationships in literature.

  4. Rapidly solidified titanium alloys by melt overflow

    Science.gov (United States)

    Gaspar, Thomas A.; Bruce, Thomas J., Jr.; Hackman, Lloyd E.; Brasmer, Susan E.; Dantzig, Jonathan A.; Baeslack, William A., III

    1989-01-01

    A pilot plant scale furnace was designed and constructed for casting titanium alloy strips. The furnace combines plasma arc skull melting techniques with melt overflow rapid solidification technology. A mathematical model of the melting and casting process was developed. The furnace cast strip of a suitable length and width for use with honeycomb structures. Titanium alloys Ti-6Al-4V and Ti-14Al-21 Nb were successfully cast into strips. The strips were evaluated by optical metallography, microhardness measurements, chemical analysis, and cold rolling.

  5. Physics of the Lindemann melting rule

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, Andrew C [Los Alamos National Laboratory

    2008-01-01

    We investigate the thermodynamics of melting for 74 distinct chemical elements including several actinides and rare earths. We find that the observed melting points are consistent with a linear relationship between the correlation entropy of the liquid and the Grueneisen constant of the solid, and that the Lindemann rule is well obeyed for the elements with simple structures and less well obeyed for the less symmetric more open structures. No special assumptions are required to explain the melting points of the rare earths or light actinides.

  6. Melt processed high-temperature superconductors

    CERN Document Server

    1993-01-01

    The achievement of large critical currents is critical to the applications of high-temperature superconductors. Recent developments have shown that melt processing is suitable for producing high J c oxide superconductors. Using magnetic forces between such high J c oxide superconductors and magnets, a person could be levitated.This book has grown largely out of research works on melt processing of high-temperature superconductors conducted at ISTEC Superconductivity Research Laboratory. The chapters build on melt processing, microstructural characterization, fundamentals of flux pinning, criti

  7. Thermal-Hydraulic Assessment of W7-X Plasma Vessel Venting System in Case of 40 mm In-Vessel LOCA

    Directory of Open Access Journals (Sweden)

    E. Urbonavičius

    2015-01-01

    Full Text Available This paper presents assessment of the capacity of W7-X venting system in response to in-vessel LOCA, rupture of 40 mm diameter pipe during operation mode “baking.” The integral analysis of the coolant release from the cooling system, pressurisation of PV, and response of the venting system is performed using RELAP5 code. The same coolant release rate was introduced to the COCOSYS code, which is a lumped-parameter code developed for analysis of processes in containment of the light water reactors and the detailed analysis of the plasma vessel and the venting system is performed. Different options of coolant release modeling available in COCOSYS are compared to define the base case model, which is further used for assessment of the other parameters, that is, the failure of one burst disk, the temperature in the environment, and the pressure losses in the piping of venting system. The performed analysis identified the best option for coolant release modeling and showed that the capacity of the W7-X venting system is enough to prevent overpressure of the plasma vessel in the case of in-vessel LOCA.

  8. Diffusive loss of argon in response to melt vein formation in polygenetic impact melt breccias

    Science.gov (United States)

    Mercer, Cameron M.; Hodges, Kip V.

    2017-08-01

    Many planetary surfaces in the solar system have experienced prolonged bombardment. With each impact, new rocks can be assembled that incorporate freshly generated impact melts with fragments of older rocks. Some breccias can become polygenetic, containing multiple generations of impact melt products, and can potentially provide important insights into the extensive bombardment history of a region. However, the amount of chronological information that can be extracted from such samples depends on how well the mineral isotopic systems of geochronometers can preserve the ages of individual melt generations without being disturbed by younger events. We model the thermal evolution of impact melt veins and the resulting loss of Ar from K-bearing phases common in impact melt breccias to assess the potential for preserving the 40Ar/39Ar ages of individual melt generations. Our model results demonstrate that millimeter-scale, clast-free melt veins cause significant heating of adjacent host rock minerals and can cause detectable Ar loss in contact zones that are generally thinner than, and at most about the same thickness as, the vein width. The incorporation of cold clasts in melt veins reduces the magnitudes of heating and Ar loss in the host rocks, and Ar loss can be virtually undetectable for sufficiently clast-rich veins. Quantitative evidence of the timing of impacts, as measured with the 40Ar/39Ar method, can be preserved in polygenetic impact melt breccias, particularly for those containing millimeter-scale bodies of clast-bearing melt products.

  9. 废铝旋转喷吹除氢的水模拟试验与熔炼实验验证%Water-simulation experiment of scrap aluminium dehydrogenation by rotating impeller degassing and melting experiment verification

    Institute of Scientific and Technical Information of China (English)

    李聪; 龙思远; 杨怀德; 范超; 逯志浩

    2013-01-01

    In order to explore the optimization process combination of dehydrogenation by rotating impeller degassing technology for molten scrap aluminum, the water-simulation experiments were made from the source of hydrogen in molten aluminum and with Approximation Principle as guidance. Then with results of water-simulation experiments for reference, dehydrogenation experiments for smelting aluminum scrap were accomplished. By analyzing the experimental effect, it is shown that the hydrogen content is decreased from 0.30 mL/100 g to 0.11 mL/100 g, and the experimental results of rotor offset distribution are obviously superior to that of rotor center distribution. So the accuracy of optimizing process combination of water-simulation experiment is verified.%为探索废铝熔体旋转喷吹除氢的优化工艺组合,从氢的来源入手,以相似原理为指导,进行旋转喷吹的水模拟试验,然后以水模拟试验结果为参考,进行废铝的熔炼除氢实验,并分析其除氢效果.结果表明:转子偏置分布实验中,氢的质量浓度从0.30 mL/100 g降至0.11 mL/100 g,效果明显优于转子中心分布实验,从而验证水模拟试验的优化工艺组合的准确性.

  10. Development of melting system for Measurement of trace elements and ions in ice core

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sang Bum; Lee, Khang Hyun; Hur, Soon Do; Soyol-Erene, Tseren-Ochir; Kim, Sun Mee; Chung, Ji Woong; Jun, Seong Joon [Korea Polar Research Institute, KIOST, Incheon (Korea, Republic of); Hong, Sung Min [Dept. of Ocean Sciences, Inha University, Incheon (Korea, Republic of); Kang, Chang Hee [Dept. of Chemistry and Research Institute for Basic Sciences, Jeju National University, Jeju (Korea, Republic of)

    2015-04-15

    We present a titanium (Ti) melting head divided into three zones as an improved melting system for decontaminating ice-core samples. This system was subjected to performance tests using short ice-core samples (4 × 4 cm{sup 2}, ⁓5 cm long). The procedural blanks (PBs) and detection limits of ionic species, with the exception of math formula, were comparable with published values, but for elements the experimental procedures should be refined to obtain valid Zn concentrations due to the PB of ⁓90.0 ± 16.2 ng/L. The improved melting system efficiently decontaminated the samples, as verified by the concentration profiles of elements and ions in the melted samples from the three melting-head zones. The recovery of trace elements in ice-core samples was ⁓70–120% at ⁓100 ng/L in artificial ice cores. Because of the memory effects between ice-core samples melted in series, the melting system should be rinsed at least 5–6 times (in a total volume of ⁓2.5 mL deionized water) after each melting procedure. Finally, as an application of this technique, trace elements were measured in ice-core samples recovered from the East Rongbuk Glacier, Mount Everest, (28°03′N, 86°96′E, 6518 m a.s.l.), and the concentrations of trace elements following mechanical chiseling and the melting method were compared.

  11. The impact of under-ice melt ponds on Arctic sea ice volume

    Science.gov (United States)

    Smith, Naomi; Flocco, Daniela; Feltham, Daniel

    2016-04-01

    A one-dimensional, thermodynamic model of Arctic sea ice [Flocco et al, 2015] has been adapted to study the evolution of under-ice melt ponds, pools of fresh water that are found below the Arctic sea ice, and false bottoms, sheets of ice that form at the boundary between the under-ice melt pond and the oceanic mixed layer. Over time, either the under-ice melt pond freezes or the false bottom is completely ablated. We have been investigating the impact that these features have on the growth or ablation of sea ice during the time that they are present. The sensitivity of our model to a range of parameters has been tested, revealing some interesting effects of the thermodynamic processes taking place during the life-cycle of these phenomena. For example, the under-ice melt pond and its associated false bottom can insulate the sea ice layer from ocean, increasing the thickness of sea ice present at the end of the time frame considered. A comparison of the results of the model of under-ice melt pond evolution with that of sea ice with a bare base has been used to estimate the impact of under-ice melt ponds on sea ice volume towards the end of the melt season. We find that the under-ice melt ponds could have a significant impact on the mass balance of the sea ice, suggesting that it could be desirable to include a parameterisation of the effects of under-ice melt pond in the sea ice components of climate models.

  12. The Reaction of Carbonates in Contact with Superheated Silicate Melts: New Insights from MEMIN Laser Melting Experiments

    Science.gov (United States)

    Hamann, C.; Hecht, L.; Schäffer, S.; Deutsch, A.; Lexow, B.

    2016-08-01

    The reaction of carbonates in contact with silicate impact melts is discussed quite controversially in the impact community. Here, we discuss four MEMIN laser melting experiments involving carbonates in contact with superheated silicate melts.

  13. Floating ice-algal aggregates below melting arctic sea ice.

    Science.gov (United States)

    Assmy, Philipp; Ehn, Jens K; Fernández-Méndez, Mar; Hop, Haakon; Katlein, Christian; Sundfjord, Arild; Bluhm, Katrin; Daase, Malin; Engel, Anja; Fransson, Agneta; Granskog, Mats A; Hudson, Stephen R; Kristiansen, Svein; Nicolaus, Marcel; Peeken, Ilka; Renner, Angelika H H; Spreen, Gunnar; Tatarek, Agnieszka; Wiktor, Jozef

    2013-01-01

    During two consecutive cruises to the Eastern Central Arctic in late summer 2012, we observed floating algal aggregates in the melt-water layer below and between melting ice floes of first-year pack ice. The macroscopic (1-15 cm in diameter) aggregates had a mucous consistency and were dominated by typical ice-associated pennate diatoms embedded within the mucous matrix. Aggregates maintained buoyancy and accumulated just above a strong pycnocline that separated meltwater and seawater layers. We were able, for the first time, to obtain quantitative abundance and biomass estimates of these aggregates. Although their biomass and production on a square metre basis was small compared to ice-algal blooms, the floating ice-algal aggregates supported high levels of biological activity on the scale of the individual aggregate. In addition they constituted a food source for the ice-associated fauna as revealed by pigments indicative of zooplankton grazing, high abundance of naked ciliates, and ice amphipods associated with them. During the Arctic melt season, these floating aggregates likely play an important ecological role in an otherwise impoverished near-surface sea ice environment. Our findings provide important observations and measurements of a unique aggregate-based habitat during the 2012 record sea ice minimum year.

  14. Onset of convective instabilities in under-ice melt ponds.

    Science.gov (United States)

    Hirata, Sílvia C; Goyeau, Benoît; Gobin, Dominique

    2012-06-01

    The onset of double-diffusive natural convection in under-ice melt ponds is investigated through a linear stability analysis. The three-layer configuration is composed by a fluid layer (melt pond) overlying a saturated porous medium (ice matrix), which in turn overlies another fluid layer (under-ice melt pond). Water density inversion is taken into account by adopting a density profile with a quadratic temperature dependence and a linear concentration dependence. We show that the key parameter affecting stability is the depth of the ice matrix, while the depths of the upper and lower fluid layers play a marginal role. A Hopf bifurcation is observed in the whole range of parameters studied, and the size of the convection cells depends on ice permeability. The influence of the external temperature gradient is investigated by means of the definition of an extra thermal parameter accounting for the relative position of the density maximum. It is shown that convection is favored by larger temperature gradients, which occur during Arctic summer.

  15. Early Earth melt production in a subduction zone, a petrological model

    Science.gov (United States)

    Magni, V.; Bouilhol, P.; Van Hunen, J.; Moyen, J.

    2013-12-01

    A large part of the Archean continental crust is made of a composite rock assemblage dominated by granitoids belonging to the TTG series (tonalite-trondhejmeite-granodiorite). The modus operandi of this sodic granitoids still disputed. If the modern processes leading to continental crust formation at convergent margins are well constrained, the extrapolation to early Earth conditions is hazardous, because the composition of Earth's early crust can be achieved through several processes. However, an 'arc' signature seems to be present in TTGs, suggesting a formation of continental crust in subduction zone settings. Moreover, they show strong similarities with modern adakites, which are thought to be formed by melting of the oceanic subducting crust. We present the results of a study where numerical models of subduction are integrated with a thermodynamic database. Our goal is to investigate under which conditions slab melting can be achieved if at all. We particularly focus our attention on the fate of water, since it is a component that is essential to the formation of TTG series, independently of the petrogenetical scenario preferred. The amount and composition of water bearing fluids in a subduction zone is controlled by slab devolatilization, and influence both the melting regime and the melt composition. Our reference model of an early Earth regime, with a high mantle potential temperature, show that the slab dehydrates early, ending up being composed of a dry eclogites. Importantly, our models show that dehydration melting is not achieved in the slab crust; yet, water-present melting of the 'dry' eclogites can be achieved if a dehydration reaction occurs in the deeper portion of the slab, fuelling the melting reaction with water. Moreover, the dehydration reactions that occurred within the slab are able to metasomatize the overlying mantle wedge, forming hydrated peridotites, that becomes a melt source when dragged down by corner-flow. Our results show the

  16. Glacier melt buffering sustains river flow in the Pamir Mountains

    Science.gov (United States)

    Pohl, Eric; Andermann, Christoff; Gloaguen, Richard

    2017-04-01

    Central Asia's water resources and agricultural practices depend on snow and glacier melts in the high mountains. The Amu Darya, the main river draining the Pamir Mountains, exemplifies the resulting seasonality in stream flow. In winter, comparably low amounts of groundwater discharge feed the streams, while the bulk of precipitation is provided and stored as snow. Successive melting of snow cover and glaciers during summer releases these stored waters to the swelling rivers. Despite a strong variability in precipitation and temperatures over the entire Pamir Mountain region, river flow shows severely less variability. We investigate what processes lead to this apparent discrepancy by using a simple but robust hydrological model that we thoroughly validate with remote sensing snow cover observations, Gravity Recovery and Climate Experiment (GRACE) data, highlighting changes in total water storage, and hydrograph comparison. We find that glaciers play a paramount role by buffering extreme meteorological conditions to sustain stream flow. In a simplified scheme, low precipitation amounts in winter result in small snow stocks, compensated for by more intensive glacier melt, and vice versa. By carrying out analyses over the extensive catchment area of the Amu Darya in the high mountain domain, we highlight regional differences in the effectiveness of this mechanism. Regional influences of wind systems and associated moisture transport as well as glaciated area emerge as main factors. Modeled negative glacier mass balances between -0.38 and -0.93 m/year agree with other studies based on geodetic methods and indicate a future reduction in stream flow sustainability. This not only exacerbates the conflict potential between riparian countries downstream, but also means that extreme weather events are more likely to cause floods and droughts.

  17. A benchmark initiative on mantle convection with melting and melt segregation

    Science.gov (United States)

    Schmeling, Harro; Dohmen, Janik; Wallner, Herbert; Noack, Lena; Tosi, Nicola; Plesa, Ana-Catalina; Maurice, Maxime

    2015-04-01

    In recent years a number of mantle convection models have been developed which include partial melting within the asthenosphere, estimation of melt volumes, as well as melt extraction with and without redistribution at the surface or within the lithosphere. All these approaches use various simplifying modelling assumptions whose effects on the dynamics of convection including the feedback on melting have not been explored in sufficient detail. To better assess the significance of such assumptions and to provide test cases for the modelling community we initiate a benchmark comparison. In the initial phase of this endeavor we focus on the usefulness of the definitions of the test cases keeping the physics as sound as possible. The reference model is taken from the mantle convection benchmark, case 1b (Blanckenbach et al., 1989), assuming a square box with free slip boundary conditions, the Boussinesq approximation, constant viscosity and a Rayleigh number of 1e5. Melting is modelled assuming a simplified binary solid solution with linearly depth dependent solidus and liquidus temperatures, as well as a solidus temperature depending linearly on depletion. Starting from a plume free initial temperature condition (to avoid melting at the onset time) three cases are investigated: Case 1 includes melting, but without thermal or dynamic feedback on the convection flow. This case provides a total melt generation rate (qm) in a steady state. Case 2 includes batch melting, melt buoyancy (melt Rayleigh number Rm), depletion buoyancy and latent heat, but no melt percolation. Output quantities are the Nusselt number (Nu), root mean square velocity (vrms) and qm approaching a statistical steady state. Case 3 includes two-phase flow, i.e. melt percolation, assuming a constant shear and bulk viscosity of the matrix and various melt retention numbers (Rt). These cases should be carried out using the Compaction Boussinseq Approximation (Schmeling, 2000) or the full compaction

  18. A wide angle view imaging diagnostic with all reflective, in-vessel optics at JET

    Energy Technology Data Exchange (ETDEWEB)

    Clever, M. [Institute of Energy and Climate Research – Plasma Physics, Forschungszentrum Jülich GmbH, Association EURATOM-FZJ, 52425 Jülich (Germany); Arnoux, G.; Balshaw, N. [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Garcia-Sanchez, P. [Laboratorio Nacional de Fusion, Asociacion EURATOM-CIEMAT, Madrid (Spain); Patel, K. [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Sergienko, G. [Institute of Energy and Climate Research – Plasma Physics, Forschungszentrum Jülich GmbH, Association EURATOM-FZJ, 52425 Jülich (Germany); Soler, D. [Winlight System, 135 rue Benjamin Franklin, ZA Saint Martin, F-84120 Pertuis (France); Stamp, M.F.; Williams, J.; Zastrow, K.-D. [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

    2013-10-15

    Highlights: ► A new wide angle view camera system has been installed at JET. ► The system helps to protect the ITER-like wall plasma facing components from damage. ► The coverage of the vessel by camera observation systems was increased. ► The system comprises an in-vessel part with parabolic and flat mirrors. ► The required image quality for plasma monitoring and wall protection was delivered. -- Abstract: A new wide angle view camera system has been installed at JET in preparation for the ITER-like wall campaigns. It considerably increases the coverage of the vessel by camera observation systems and thereby helps to protect the – compared to carbon – more fragile plasma facing components from damage. The system comprises an in-vessel part with parabolic and flat mirrors and an ex-vessel part with beam splitters, lenses and cameras. The system delivered the image quality required for plasma monitoring and wall protection.

  19. Engineering analysis of ITER In-Vessel Viewing System guide tube

    Energy Technology Data Exchange (ETDEWEB)

    Casal, Natalia, E-mail: natalia.casal@iter.org [ITER Organization, Route de Vinon sur Verdon, St Paul-lez-Durance (France); Bates, Philip [Fusion for Energy, Barcelona (Spain); Bede, Ottó [Oxford Technologies Ltd., Abingdon (United Kingdom); Damiani, Carlo; Dubus, Gregory [Fusion for Energy, Barcelona (Spain); Omran, Hassan [Oxford Technologies Ltd., Abingdon (United Kingdom); Palmer, Jim [ITER Organization, Route de Vinon sur Verdon, St Paul-lez-Durance (France); Puiu, Adrian [Fusion for Energy, Barcelona (Spain); Reichle, Roger; Suárez, Alejandro; Walker, Christopher; Walsh, Michael [ITER Organization, Route de Vinon sur Verdon, St Paul-lez-Durance (France)

    2015-10-15

    Highlights: • Conceptual design of IVVS Loads action on IVVS Dominant loads. • Seismic and baking conditions. • No active cooling needed for IVVS. • IVVS requires additional support points to avoid excessive deformation. - Abstract: The In Vessel Viewing System (IVVS) will be one of the essential machine diagnostic systems at ITER to provide information about the status of in-vessel and plasma facing components and to evaluate the dust inside the Vacuum Vessel. The current design consists of six scanning probes and their deployment systems, which are placed in dedicated ports at the divertor level. These units are located in resident guiding tubes 10 m long, which allow the IVVS probes to go from their storage location to the scanning position by means of a simple straight translation. Moreover, each resident tube is supported inside the corresponding Vacuum Vessel and Cryostat port extensions, which are part of the primary confinement barrier. As the Vacuum Vessel and the Cryostat will move with respect to each other during operation (especially during baking) and during incidents and accidents (disruptions, vertical displacement events, seismic events), the structural integrity of the resident tube and the surrounding vacuum boundaries would be compromised if the required flexibility and supports are not appropriately assured. This paper focuses on the integration of the present design of the IVVS into the Vacuum Vessel and Cryostat environment. It presents the adopted strategy to withstand all the main interfacing loads without damaging the confinement barriers and the corresponding analysis supporting it.

  20. Development of a long reach articulated manipulator for ITER in vessel inspection under vacuum and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Perrot, Y. E-mail: yann.perrot@cea.fr; Cordier, J.J.; Friconneau, J.P.; Maisonnier, D.; Martin, E.; Palmer, J.D

    2003-09-01

    This project takes place in the EFDA Remote Handling (RH) activities for the fusion reactor International Thermonuclear Experimental Reactor (ITER). The aim of the R and D program is to demonstrate the feasibility of in-vessel RH intervention by a long reach, limited payload manipulator which penetrates the first wall using the six IVVS penetrations. Potential activities for this device include close inspection of the plasma facing surfaces and leak detection. The work includes the design, manufacture and testing of a demonstrator articulated manipulator called the In-Vessel Penetrator (IVP). The first part of this work concerned the analysis of the requirements and resulted in the development of the conceptual design of the overall manipulator, comprising a 5 module, 11 d.o.f robot based on a parallelogram structure. A scale one mock up of a representative segment was manufactured and tested. In parallel, a feasibility study of the IVP operation was made and provided recommendations to modify the design for intervention under vacuum and temperature. Some technologies were selected and analysed to determine their suitability to the IVP application and items identified for further validation. This paper presents the whole robot concept, the results of the test campaign on the prototype demonstrator and the vacuum and temperature technologies study.

  1. Evaluation of the neutron activation of JET in-vessel components following DT irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Vuolo, M.; Bonifetto, R.; Dulla, S. [Dipartimento Energia, Politecnico di Torino, I-10129 Torino (Italy); Heinola, K. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Association EURATOM-TEKES, University of Helsinki, PO Box 64, 00560 Helsinki (Finland); Lengar, I. [Association EURATOM-MESCS, Reactor Physics Division, Jožef Stefan Institute, Ljubljana (Slovenia); Ravetto, P., E-mail: piero.ravetto@polito.it [Dipartimento Energia, Politecnico di Torino, I-10129 Torino (Italy); Richard, L.Savoldi [Dipartimento Energia, Politecnico di Torino, I-10129 Torino (Italy); Villari, R. [Associazione EURATOM-ENEA sulla Fusione, Via Enrico Fermi 45, 00044 Frascati, Rome (Italy); Widdowson, A. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Zanino, R. [Dipartimento Energia, Politecnico di Torino, I-10129 Torino (Italy)

    2014-10-15

    Highlights: The temporal evolution of the radioactive species in the in-vessel components after the end of the JET-DT campaign is calculated; Different levels of neutron irradiation are assumed; The neutron flux in the selected components is calculated by the MCNP5 code; The neutron spectra are input to the FISPACT code that computes the evolution of the radioactive species; For each irradiation scenario, the time behavior of the contact dose rate is determined. Abstract: The forthcoming deuterium–tritium (DT) campaign at the Joint European Torus (JET) will induce a significant activation of the system components. In the present work we evaluate the temporal evolution of the radioactive species in the main in-vessel components after the end of the future DT campaign, assuming different levels of neutron irradiation. The neutron flux in the selected components is calculated by the MCNP5 code using the emission source by a typical DT plasma. The resulting neutron spectra are then input to the FISPACT code that computes the evolution of the radioactive species generated by the neutron activation process. For each irradiation scenario, the time behavior of the contact dose rate is determined.

  2. Nuclear analysis and shielding optimisation in support of the ITER In-Vessel Viewing System design

    Energy Technology Data Exchange (ETDEWEB)

    Turner, Andrew, E-mail: andrew.turner@ccfe.ac.uk [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Pampin, Raul [F4E Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Loughlin, M.J. [ITER Organisation, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Ghani, Zamir; Hurst, Gemma [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Lo Bue, Alessandro [F4E Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Mangham, Samuel [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Puiu, Adrian [F4E Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Zheng, Shanliang [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

    2014-10-15

    The In-Vessel Viewing System (IVVS) units proposed for ITER are deployed to perform in-vessel examination. During plasma operations, the IVVS is located beyond the vacuum vessel, with shielding blocks envisaged to protect components from neutron damage and reduce shutdown dose rate (SDR) levels. Analyses were conducted to determine the effectiveness of several shielding configurations. The neutron response of the system was assessed using global variance reduction techniques and a surface source, and shutdown dose rate calculations were undertaken using MCR2S. Unshielded, the absorbed dose to piezoelectric motors (PZT) was found to be below stable limits, however activation of the primary closure plate (PCP) was prohibitively high. A scenario with shielding blocks at probe level showed significantly reduced PCP contact dose rate, however still marginally exceeded port cell requirements. The addition of shielding blocks at the bioshield plug demonstrated PCP contact dose rates below project requirements. SDR levels in contact with the isolated IVVS cartridge were found to marginally exceed the hands-on maintenance limit. For engineering feasibility, shielding blocks at bioshield level are to be avoided, however the port cell SDR field requires further consideration. In addition, alternative low-activation steels are being considered for the IVVS cartridge.

  3. Analysis and optimization on in-vessel inspection robotic system for EAST

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Weijun, E-mail: zhangweijun@sjtu.edu.cn; Zhou, Zeyu; Yuan, Jianjun; Du, Liang; Mao, Ziming

    2015-12-15

    Since China has successfully built her first Experimental Advanced Superconducting TOKAMAK (EAST) several years ago, great interest and demand have been increasing in robotic in-vessel inspection/operation systems, by which an observation of in-vessel physical phenomenon, collection of visual information, 3D mapping and localization, even maintenance are to be possible. However, it has been raising many challenges to implement a practical and robust robotic system, due to a lot of complex constraints and expectations, e.g., high remanent working temperature (100 °C) and vacuum (10{sup −3} pa) environment even in the rest interval between plasma discharge experiments, close-up and precise inspection, operation efficiency, besides a general kinematic requirement of D shape irregular vessel. In this paper we propose an upgraded robotic system with redundant degrees of freedom (DOF) manipulator combined with a binocular vision system at the tip and a virtual reality system. A comprehensive comparison and discussion are given on the necessity and main function of the binocular vision system, path planning for inspection, fast localization, inspection efficiency and success rate in time, optimization of kinematic configuration, and the possibility of underactuated mechanism. A detailed design, implementation, and experiments of the binocular vision system together with the recent development progress of the whole robotic system are reported in the later part of the paper, while, future work and expectation are described in the end.

  4. Investigation of Melting Dynamics of Hafnium Clusters.

    Science.gov (United States)

    Ng, Wei Chun; Lim, Thong Leng; Yoon, Tiem Leong

    2017-03-27

    Melting dynamics of hafnium clusters are investigated using a novel approach based on the idea of the chemical similarity index. Ground state configurations of small hafnium clusters are first derived using Basin-Hopping and Genetic Algorithm in the parallel tempering mode, employing the COMB potential in the energy calculator. These assumed ground state structures are verified by using the Low Lying Structures (LLS) method. The melting process is carried out either by using the direct heating method or prolonged simulated annealing. The melting point is identified by a caloric curve. However, it is found that the global similarity index is much more superior in locating premelting and total melting points of hafnium clusters.

  5. Ice-shelf melting around Antarctica

    National Research Council Canada - National Science Library

    Rignot, E; Jacobs, S; Mouginot, J; Scheuchl, B

    2013-01-01

    We compare the volume flux divergence of Antarctic ice shelves in 2007 and 2008 with 1979 to 2010 surface accumulation and 2003 to 2008 thinning to determine their rates of melting and mass balance...

  6. Energy-Efficient Glass Melting: Submerged Combustion

    Energy Technology Data Exchange (ETDEWEB)

    None

    2004-01-01

    Oxy-gas-fired submerged combustion melter offers simpler, improved performance. For the last 100 years, the domestic glass industry has used the same basic equipment for melting glass on an industrial scale.

  7. Principle of Melt-glue Cloth

    Institute of Scientific and Technical Information of China (English)

    陈人豪; 曹建达; 李济群; 张利梅; 何洋

    2003-01-01

    This paper advances a new concept of textile-meltglue cloth, and introduces the readers to the basic principle of melt-glue cloth. On the basis of melt spinning, the spinneret can be replaced by a spinning device that consists of an outer spinneret (a loop)and an inner spinneret ( a round plate), and between them there is an interval circle on which the centers of the holes are evenly distributed. When the machine is running, the outer spinneret (or the inner one) is fixed, the inner spinneret (or the outer one)is spinning, and a columnar net will be obtained.Then it will be excided with the help of a cutter in transporting it. Finally the once-forming melt-glue cloth will be produced. Compared with the traditional woven fabric, melt-glue cloth has a lot of special features and a bright future of application.

  8. Energy Saving Melting and Revert Reduction Technology (E-SMARRT): Melting Efficiency Improvement

    Energy Technology Data Exchange (ETDEWEB)

    Principal Investigator Kent Peaslee; Co-PI’s: Von Richards, Jeffrey Smith

    2012-07-31

    Steel foundries melt recycled scrap in electric furnaces and typically consume 35-100% excess energy from the theoretical energy requirement required to pour metal castings. This excess melting energy is multiplied by yield losses during casting and finishing operations resulting in the embodied energy in a cast product typically being three to six times the theoretical energy requirement. The purpose of this research project was to study steel foundry melting operations to understand energy use and requirements for casting operations, define variations in energy consumption, determine technologies and practices that are successful in reducing melting energy and develop new melting techniques and tools to improve the energy efficiency of melting in steel foundry operations.

  9. Spatiotemporal tracer variability in glacier melt and its influence on hydrograph separation

    Science.gov (United States)

    Schmieder, Jan; Marke, Thomas; Strasser, Ulrich

    2017-04-01

    Glaciers are important seasonal water contributors in many mountainous regions. Knowledge on the timing and amount of glacier melt water is crucial for water resources management, especially in downstream regions where the water is needed (hydropower, drinking water) or where it represents a potential risk (drought, flood). This becomes even more relevant in a changing climate. Environmental tracers are a useful tool in the assessment of ice water resources, because they provide information about the sources, flow paths and traveling times of water contributing to streamflow at the catchment scale. Hydrometric and meteorological measurements combined with tracer analyses help to unravel streamflow composition and improve the understanding of hydroclimatological processes. Empirical studies on runoff composition are necessary to parameterize and validate hydrological models in a process-oriented manner, rather than comparing total measured and simulated runoff only. In the present study three approaches of hydrograph separation are compared to decide which sampling frequency is required to capture the spatiotemporal variability of glacier melt, and to draw implications for future studies of streamflow partitioning. Therefore glacier melt contributions to a proglacial stream at the sub-daily, daily, and seasonal scale were estimated using electrical conductivity and oxygen-18 as tracers. The field work was conducted during December 2015 and September 2016 in the glaciated (34%) high-elevation catchment of the Hochjochbach, a small sub-basin (17 km2) of the Oetztaler Ache river in the Austrian Alps, ranging from 2400 to 3500 m a.s.l. in elevation. Hydroclimatological data was provided by an automatic weather station and a streamflow gauging station equipped with a pressure transducer. Water samples of streamflow, glacier melt, and rain were collected throughout the winter period (December to March) and the ablation season (July to September). In the proposed

  10. Electrochemical Studies in Aluminum Chloride Melts

    Science.gov (United States)

    1976-07-31

    Molten Salt Systems", Symposium on Molten Salts, Symposium Volume, The Electrochemical Society , in press (1976). Manuscripts in Preparation--Related to...Fused Salt Technology, Electrochemical Society Meeting, Chicaao, May 8-13, 1973. R. A. Osteryoung, R. H. Abel, L. G. Boxall and B. H. Vassos, "An...aluminate Melts", Electrochemical Society , San Francisco, CA, May, 1974. R. A. Osteryoung, "Chemistry in Aluminum Chloride Melts", Fifth International

  11. Terrestrial analogues for lunar impact melt flows

    Science.gov (United States)

    Neish, C. D.; Hamilton, C. W.; Hughes, S. S.; Nawotniak, S. Kobs; Garry, W. B.; Skok, J. R.; Elphic, R. C.; Schaefer, E.; Carter, L. M.; Bandfield, J. L.; Osinski, G. R.; Lim, D.; Heldmann, J. L.

    2017-01-01

    Lunar impact melt deposits have unique physical properties. They have among the highest observed radar returns at S-Band (12.6 cm wavelength), implying that they are rough at the decimeter scale. However, they are also observed in high-resolution optical imagery to be quite smooth at the meter scale. These characteristics distinguish them from well-studied terrestrial analogues, such as Hawaiian pāhoehoe and ´a´ā lava flows. The morphology of impact melt deposits can be related to their emplacement conditions, so understanding the origin of these unique surface properties will help to inform us as to the circumstances under which they were formed. In this work, we seek to find a terrestrial analogue for well-preserved lunar impact melt flows by examining fresh lava flows on Earth. We compare the radar return and high-resolution topographic variations of impact melt flows to terrestrial lava flows with a range of surface textures. The lava flows examined in this work range from smooth Hawaiian pāhoehoe to transitional basaltic flows at Craters of the Moon (COTM) National Monument and Preserve in Idaho to rubbly and spiny pāhoehoe-like flows at the recent eruption at Holuhraun in Iceland. The physical properties of lunar impact melt flows appear to differ from those of all the terrestrial lava flows studied in this work. This may be due to (a) differences in post-emplacement modification processes or (b) fundamental differences in the surface texture of the melt flows due to the melts' unique emplacement and/or cooling environment. Information about the surface properties of lunar impact melt deposits will be critical for future landed missions that wish to sample these materials.

  12. An energy-budget-based glacier melting model for the Tibetan Plateau

    Science.gov (United States)

    Ding, Baohong; Yang, Kun; Chen, Yingying

    2013-04-01

    There have been rapid glacier retreats during the past few decades on the Tibetan Plateau, which not only have far-reaching impacts on the water resources in this region, but also potentially threat the downstream by glacial lake outburst floods. It is therefore important to model the physical link between glacier melting and climate changes and its implication in water resources. There have been a few studies on glacier melting models, of which the applicability is limited to some areas and the simulation capability also needs to be improved. This paper presents a new energy-budget-based model for the melting of the mountainous glaciers. Enthalpy, rather than temperature, is used in the energy balance equations to simplify the computation for the energy transfer through water phase transition and within-snow liquid water movement. Heat transfer is computed in both snow and ice layers, and the inhomogeneous layering method is employed to describe the temperature profiles better, especially at the interface between snow and atmosphere as well as that between snow and ice. A new parameterization scheme is introduced into the model to calculate turbulent heat transfer over glacier surfaces. This model was validated based on the data collected from a field experiment which was implemented in the melting zone of the Parlung No. 4 Glacier in the southeastern TP from May to August in 2009. The result shows that the RMSE of the simulated hourly surface temperature is about 0.97 degree centigrade and the R2 is 0.81. The RMSE of the simulated hourly latent heat flux and hourly sensible heat flux are 14.5W m^-2 and 23.5W m^-2 respectively, and R2 are 0.92 and 0.93. In general, this energy-budget-based model could reasonably simulate the glacier melting process. The model is still under development for a better simulation of the glacier melting and its contribution to the water resources.

  13. The melting and solidification of nanowires

    Science.gov (United States)

    Florio, B. J.; Myers, T. G.

    2016-06-01

    A mathematical model is developed to describe the melting of nanowires. The first section of the paper deals with a standard theoretical situation, where the wire melts due to a fixed boundary temperature. This analysis allows us to compare with existing results for the phase change of nanospheres. The equivalent solidification problem is also examined. This shows that solidification is a faster process than melting; this is because the energy transfer occurs primarily through the solid rather than the liquid which is a poorer conductor of heat. This effect competes with the energy required to create new solid surface which acts to slow down the process, but overall conduction dominates. In the second section, we consider a more physically realistic boundary condition, where the phase change occurs due to a heat flux from surrounding material. This removes the singularity in initial melt velocity predicted in previous models of nanoparticle melting. It is shown that even with the highest possible flux the melting time is significantly slower than with a fixed boundary temperature condition.

  14. Melting behavior of large disordered sodium clusters

    CERN Document Server

    Aguado, A

    2000-01-01

    The melting-like transition in disordered sodium clusters Na_N, with N=92 and 142 is studied by using a first-principles constant-energy molecular dynamics simulation method. Na_142, whose atoms are distributed in two (surface and inner) main shells with different radial distances to the center of mass of the cluster, melts in two steps: the first one, at approx. 130 K, is characterized by a high intrashell mobility of the atoms, and the second, homogeneous melting, at approx. 270 K, involves diffusive motion of all the atoms across the whole cluster volume (both intrashell and intershell displacements are allowed). On the contrary, the melting of Na_92 proceeds gradually over a very wide temperature interval, without any abrupt step visible in the thermal or structural melting indicators. The occurrence of well defined steps in the melting transition is then shown to be related to the existence of a distribution of the atoms in shells. Thereby we propose a necessary condition for a cluster to be considered r...

  15. Manufacturing laser glass by continuous melting

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J H; Suratwala, T; krenitsky, S; Takeuchi, K

    2000-07-01

    A novel, continuous melting process is being used to manufacture meter-sized plates of laser glass at a rate 20-times faster, 5-times cheaper, and with 2-3 times better optical quality than with previous one-at-a-time, ''discontinuous'' technology processes. This new technology for manufacturing laser glass, which is arguably the most difficult continuously-melted optical material ever produced, comes as a result of a $60 million, six-year joint R&D program between government and industry. The glasses manufactured by the new continuous melting process are Nd-doped phosphate-based glasses and are marketed under the product names LG-770 (Schott Glass Technologies) and LHG-8 (Hoya Corporation USA). With this advance in glass manufacturing technology, it is now possible to construct high-energy, high-peak-power lasers for use in fusion energy development, national defense, and basic physics research that would have been impractical to build using the old melting technology. The development of continuously melted laser glass required technological advances that have lead to improvements in the manufacture of other optical glass products as well. For example, advances in forming, annealing, and conditioning steps of the laser glass continuous melting process are now being used in manufacture of other large-size optical glasses.

  16. Agglomeration and size distribution of debris in DEFOR-A experiments with Bi{sub 2}O{sub 3}–WO{sub 3} corium simulant melt

    Energy Technology Data Exchange (ETDEWEB)

    Kudinov, Pavel, E-mail: pavel@safety.sci.kth.se; Karbojian, Aram, E-mail: aram@safety.sci.kth.se; Tran, Chi-Thanh, E-mail: thanh@safety.sci.kth.se; Villanueva, Walter, E-mail: walter@safety.sci.kth.se

    2013-10-15

    Highlights: • Debris agglomeration in case of melt pouring into a coolant is experimentally investigated. • The effects of jet diameter, melt superheat and water subcooling are addressed. • Most influential factor which can significantly increase fraction of agglomerates is melt superheat. • Rapid decrease of the fraction of agglomerates as a function of water depth is obtained in all cases. • Provided data is valuable for model development and code validation. -- Abstract: Flooding of lower drywell has been adopted as a cornerstone of severe accident management strategy in Nordic type Boiling Water Reactors (BWR). It is assumed that the melt ejected into a deep pool of water will fragment, quench and form a porous debris bed coolable by natural circulation. If debris bed is not coolable, then dryout and possibly re-melting of the debris can occur. Melt attack on the containment basemat can threaten containment integrity. Agglomeration of melt debris and formation of solid “cake” regions provide a negative impact on coolability of the porous debris bed. In this work we present results of experimental investigation on the fraction of agglomerated debris obtained in the process of hot binary oxidic melt pouring into a pool of water. The Debris Bed Formation and Agglomeration (DEFOR-A) experiments provide data about the effects of the pool depth and water subcooling, melt jet diameter, and initial melt superheat on the fraction of agglomerated debris. The data presents first systematic study of the debris agglomeration phenomena and facilitates understanding of underlying physics which is necessary for development and validation of computational codes to enable prediction of the debris bed coolability in different scenarios of melt release.

  17. Primary crustal melt compositions: Insights into the controls, mechanisms and timing of generation from kinetics experiments and melt inclusions

    Science.gov (United States)

    Acosta-Vigil, Antonio; London, David; Morgan, George B.; Cesare, Bernardo; Buick, Ian; Hermann, Jörg; Bartoli, Omar

    2017-08-01

    We explore the controls, mechanisms and timing of generation of primary melts and their compositions, and show that the novel studies of melt inclusions in migmatites can provide important insights into the processes of crustal anatexis of a particular rock. Partial melting in the source region of granites is dependent on five main processes: (i) supply of heat; (ii) mineral-melt interface reactions associated with the detachment and supply of mineral components to the melt, (iii) diffusion in the melt, (iv) diffusion in minerals, and (v) recrystallization of minerals. As the kinetics of these several processes vary over several orders of magnitude, it is essential to evaluate in Nature which of these processes control the rate of melting, the composition of melts, and the extent to which residue-melt chemical equilibrium is attained under different circumstances. To shed light on these issues, we combine data from experimental and melt inclusion studies. First, data from an extensive experimental program on the kinetics of melting of crustal protoliths and diffusion in granite melt are used to set up the necessary framework that describes how primary melt compositions are established during crustal anatexis. Then, we use this reference frame and compare compositional trends from experiments with the composition of melt inclusions analyzed in particular migmatites. We show that, for the case of El Hoyazo anatectic enclaves in lavas, the composition of glassy melt inclusions provides important information on the nature and mechanisms of anatexis during the prograde suprasolidus history of these rocks, including melting temperatures and reactions, and extent of melt interconnection, melt homogenization and melt-residue equilibrium. Compositional trends in several of the rehomogenized melt inclusions in garnet from migmatites/granulites in anatectic terranes are consistent with diffusion in melt-controlled melting, though trace element compositions of melt inclusions

  18. Silicate melts density, buoyancy relations and the dynamics of magmatic processes in the upper mantle

    Science.gov (United States)

    Sanchez-Valle, Carmen; Malfait, Wim J.

    2016-04-01

    Although silicate melts comprise only a minor volume fraction of the present day Earth, they play a critical role on the Earth's geochemical and geodynamical evolution. Their physical properties, namely the density, are a key control on many magmatic processes, including magma chamber dynamics and volcanic eruptions, melt extraction from residual rocks during partial melting, as well as crystal settling and melt migration. However, the quantitative modeling of these processes has been long limited by the scarcity of data on the density and compressibility of volatile-bearing silicate melts at relevant pressure and temperature conditions. In the last decade, new experimental designs namely combining large volume presses and synchrotron-based techniques have opened the possibility for determining in situ the density of a wide range of dry and volatile-bearing (H2O and CO2) silicate melt compositions at high pressure-high temperature conditions. In this contribution we will illustrate some of these progresses with focus on recent results on the density of dry and hydrous felsic and intermediate melt compositions (rhyolite, phonolite and andesite melts) at crustal and upper mantle conditions (up to 4 GPa and 2000 K). The new data on felsic-intermediate melts has been combined with in situ data on (ultra)mafic systems and ambient pressure dilatometry and sound velocity data to calibrate a continuous, predictive density model for hydrous and CO2-bearing silicate melts with applications to magmatic processes down to the conditions of the mantle transition zone (up to 2773 K and 22 GPa). The calibration dataset consist of more than 370 density measurements on high-pressure and/or water-and CO2-bearing melts and it is formulated in terms of the partial molar properties of the oxide components. The model predicts the density of volatile-bearing liquids to within 42 kg/m3 in the calibration interval and the model extrapolations up to 3000 K and 100 GPa are in good agreement

  19. Recent changes in Arctic sea ice melt onset, freezeup, and melt season length

    Science.gov (United States)

    Markus, Thorsten; Stroeve, Julienne C.; Miller, Jeffrey

    2009-12-01

    In order to explore changes and trends in the timing of Arctic sea ice melt onset and freezeup, and therefore melt season length, we developed a method that obtains this information directly from satellite passive microwave data, creating a consistent data set from 1979 through present. We furthermore distinguish between early melt (the first day of the year when melt is detected) and the first day of continuous melt. A similar distinction is made for the freezeup. Using this method we analyze trends in melt onset and freezeup for 10 different Arctic regions. In all regions except for the Sea of Okhotsk, which shows a very slight and statistically insignificant positive trend (0.4 d decade-1), trends in melt onset are negative, i.e., toward earlier melt. The trends range from -1.0 d decade-1 for the Bering Sea to -7.3 d decade-1 for the East Greenland Sea. Except for the Sea of Okhotsk all areas also show a trend toward later autumn freeze onset. The Chukchi/Beaufort seas and Laptev/East Siberian seas observe the strongest trends with 7 d decade-1. For the entire Arctic, the melt season length has increased by about 20 days over the last 30 years. Largest trends of over 10 d decade-1 are seen for Hudson Bay, the East Greenland Sea, the Laptev/East Siberian seas, and the Chukchi/Beaufort seas. Those trends are statistically significant at the 99% level.

  20. Experimental investigation on melt coolability under bottom flooding with and without decay heat simulation

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Nitendra [Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, Maharashtra (India); Kulkarni, Parimal P. [Reactor Engineering Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Nayak, Arun K., E-mail: arunths@barc.gov.in [Reactor Engineering Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India)

    2015-04-15

    Highlights: • The effect of decay heat on melt coolability under bottom flooding was studied. • Decay heat of 0.5 MW/m{sup 3} was simulated. • A single simulant material with same mass and initial temperature was used. • Quenching of melt pool does not depend on decay heat. • Comparison of with and without decay heat experiments has been presented. - Abstract: Investigations on severe accident phenomena help us in understanding the realistic accidental phenomena for the assessment of associated risk. The societal impact of radiological leakage to the environment has demanded further robustness in the line of defence of nuclear safety. Thus, to ensure the cooling and stabilization of corium within reactor containment in case of severe accident scenarios, many new reactors have been envisaged with core catcher. In this regard, corium coolability still remains an unresolved issue in spite of several efforts being taken towards its understanding. After studying the various cooling strategies, it has been demonstrated that melt coolability using bottom flooding of water is one of the most efficient techniques so far. To study the effect of decay heat on melt pool coolability under bottom flooding condition, two experiments have been performed in this paper; one without the decay heat and the other with decay heat. The test section used for carrying out these experiments consisted of two parts viz. lower part for retaining the melt from furnace, water inlet and melt quenching, and upper part for steam expansion and its outlet. The total height of the test section was 1400 mm and was made of 33 mm thick carbon steel. Total six stainless steel nozzles of diameter 12 mm were used for injecting water at the bottom of the melt pool. The lower part was surrounded by 10 radiative heaters to simulate decay heat of 10 kW which corresponds to 0.5 MW/m{sup 3}. The experiments showed that quenching of about 25 l of melt at initial temperature of nearly 1200 °C took only a

  1. Design, fabrication, and evaluation of a partially melted ice particle cloud facility

    Science.gov (United States)

    Soltis, Jared T.

    High altitude ice crystal clouds created by highly convective storm cells are dangerous to jet transport aircraft because the crystals are ingested into the compressor section, partially melt, accrete, and cause roll back or flame out. Current facilities to test engine particle icing are not ideal for fundamental mixed-phase ice accretion experiments or do not generate frozen droplet clouds under representative conditions. The goal of this research was to develop a novel facility capable of testing fundamental partially melted ice particle icing physics and to collect ice accretion data related to mixed-phase ice accretion. The Penn State Icing Tunnel (PSIT) has been designed and fabricated to conduct partially melted ice particle cloud accretion. The PSIT generated a cloud with air assisted atomizing nozzles. The water droplets cool from the 60psi pressure drop as the water exited the nozzle and fully glaciate while flowing in the -11.0°C tunnel air flow. The glaciated cloud flowed through a duct in the center of the tunnel where hot air was introduced. The temperature of the duct was regulated from 3.3°C to 24°C which melted particle the frozen particle from 0% to 90%. The partially melted particle cloud impinged on a temperature controlled flat plate. Ice accretion data was taken for a range of duct temperature from 3.3°C to 24°C and plate temperature from -4.5°C to 7.0°C. The particle median volumetric diameter was 23mum, the total water content was 4.5 g/m 3, the specific humidity was 1.12g/kg, and the wet bulb temperature ranged from 1.0°C to 7.0°C depending on the duct temperature. The boundaries between ice particle bounce off, ice accretion, and water run off were determined. When the particle were totally frozen and the plate surface was below freezing, the ice particle bounced off as expected. Ice accretion was seen for all percent melts tested, but the plate temperature boundary between water runoff and ice accretion increased from 0°C at 8

  2. Thermosyphon assisted melting of PCM inside a rectangular enclosure:A synergistic numerical approach

    Science.gov (United States)

    Srikanth, R.; Nair, Rohit S.; Balaji, C.

    2016-09-01

    Melting of a phase change material assisted by a thermosyphon inside a two dimensional rectangular domain is numerically investigated. The PCM used is n-eicosane and the thermosyphon is made of copper. The working fluid is water. The fill ratio of the working fluid (water) is taken to be 50%. A lumped model is used for the simulation of transient operation of the thermosyphon and enthalpy-porosity method is employed for numerical simulation of melting of PCM. The effects of inclusion of multiple heat pipes on the melting of the PCM inside the enclosure is studied. Simulation results indicate that the addition of heat pipes enhances the performance of latent heat thermal energy storage system only upto a certain extent.

  3. Integral coolant channels supply made by melt-out method

    Science.gov (United States)

    Escher, W. J. D.

    1964-01-01

    Melt-out method of constructing strong, pressure-tight fluid coolant channels for chambers is accomplished by cementing pins to the surface and by depositing a melt-out material on the surface followed by two layers of epoxy-resin impregnated glass fibers. The structure is heated to melt out the low-melting alloy.

  4. Satellite and In Situ Observations of Arctic Sea Ice Floe Breakup and Melt

    Science.gov (United States)

    Richter-Menge, J.; Perovich, D. K.

    2013-12-01

    During the summer melt season the Arctic sea ice cover undergoes a major transformation. In spring the ice cover consists of large, angular floes covered by snow. By late-summer it is an ensemble of smaller rounded ice floes embedded in a lace of open water, with a surface that is a mix of bare ice and melt ponds. We integrated in situ observations of sea ice mass balance with high resolution, visible satellite imagery from April to October 2013 to follow the evolution of the seasonal marginal ice zone in the Beaufort Sea. The autonomous sea ice mass balance buoy recorded a time series of ice temperature, ice growth, snow depth, ice thickness, and surface and bottom melting. The satellite images were collected by tracking the movement of the buoy as it drifted with the ice cover. Each image covered an area of about 250 km2 with a spatial resolution of just over one meter. From the images we computed ice concentration, pond fraction, floe perimeter, pond fraction, floe and pond size distribution, and the timing of melt and freezeup. Ridges and cracks formed in winter were followed into summer to investigate their effect on the floe size distribution. Measurements from the ice mass balance buoys are scaled up using the imagery to generate area estimates of the evolution of the sea ice mass loss during summer melt. There was an increase in pond coverage starting in mid-June and an increase in floe perimeter as melt proceeded into July and August.

  5. The theoretical plausibility of central pit crater formation via melt drainage

    Science.gov (United States)

    Elder, Catherine M.; Bray, Veronica J.; Melosh, H. Jay

    2012-11-01

    Central pit craters are seen in large craters on some icy satellites and on Mars. We investigate the hypothesis that central pits form when impact melt drains into fractures beneath the impact crater. For this process to occur, the volume of melt generated during the impact, the volume of void space in fractures beneath the impact crater, and the volume of melt able to drain before the fractures freeze shut all must exceed the volume of the observed central pits. We estimate the volume of melt generated using results from previous numerical modeling studies. The fracture volume is estimated using gravity anomalies over terrestrial craters. To estimate the amount of melt able to drain before freezing, we consider flow through plane parallel fractures. These calculations all suggest that enough liquid water could drain into fractured ice beneath a crater on Ganymede to form a central pit. On Earth and the Moon, silicate impact melt will freeze before a large volume is able to drain, so we do not expect to see central pits in impact craters in targets with no ice. In summary, we find our calculations are consistent with observed central pits in craters on Ganymede and the lack of central pits in craters on Earth and the Moon.

  6. The Dynamic Role of Melt-Vapor Surface Tension in Magmatic Degassing

    Science.gov (United States)

    Mangan, M.; Sisson, T.

    2004-05-01

    It is well known from classical nucleation theory that melt-vapor surface tension (σ ) critically influences both the supersaturation pressure needed to initiate eruptive degassing (Δ Pcritical) and the rate of gas bubble nucleation (J ). Here we highlight an important aspect of melt-vapor surface tension that is generally ignored, namely, that σ is dynamic quantity responsive to the changes in melt composition, water content, and temperature that occur during magma storage and ascent. Crystallization, degassing, and cooling impart a time-dependency to σ that must be considered in any effort to accurately model eruption processes. In this study, we document changes to σ in natural, water-saturated dacitic melt at 200 MPa and 950-1055° C and 5.7-4.8 wt% H2O. Rather than traditional macroscopic measurements (sessile drop, capillarity, detachment techniques), we experimentally determine the Δ Pcritical of bubble nucleation during depressurization from 200 MPa as a function of T and wt% H2O (techniques as in Mangan and Sisson, E&PSL, 2000), and then solve for σ at those conditions using classical nucleation theory (Blander and Katz, AIChE Jour., 1975). Meshing experiment and theory gives σ = 42 (±3), 60 (±7), 73 (±3) mN/m at T= 950, 1000, 1055° C, and H2O = 5.7 (±0.1), 5.3 (±0.2), 4.8 (±0.1) wt%, respectively. Our data show a negative dependence of σ on dissolved water content of -33 mN/m/wt% H2O and a positive dependence of σ on temperature of +0.30 mN/m/° C. Comparable relationships between σ and changing water content and temperature were obtained in sessile-drop style experiments using hydrous haplogranite melts (Bagdassarov et al., Amer. Mineral., 2000). To illustrate how the observed σ -H2O-T dependencies might impact degassing models we consider two idealized regimes. The first is a storage regime in which isobaric cooling and crystallization in the magma chamber gradually increases the H2O content of the residual melt. Surface tension is

  7. Submarine Melting of Icebergs from Repeat High-Resolution Digital Elevation Models

    Science.gov (United States)

    Enderlin, E. M.; Hamilton, G. S.; Straneo, F.; Cenedese, C.

    2014-12-01

    Icebergs calved from tidewater glaciers act as distributed freshwater sources as they transit through fjords to the surrounding ocean basins. Glacier discharge estimates provide a crude approximation of the total iceberg discharge on inter-annual timescales, but the liquid freshwater flux from icebergs in glacial fjords is largely unknown. Here we use repeat high-resolution digital elevation models (DEMs) to derive meltwater fluxes for 18 icebergs in Sermilik Fjord, East Greenland, during the 2011-2013 boreal summers, and for 33 comparably-sized icebergs in Ilulissat Fjord, West Greenland, during March-April 2011 and July 2012. We find that iceberg melt rates for Sermilik Fjord are in good agreement with simulated melt rates along the vertical terminus of Helheim Glacier in winter, i.e. when melting at the glacier front is not enhanced by subglacial discharge, providing an independent validation of our technique. Variations in meltwater fluxes from icebergs are primarily related to differences in the submerged area of individual icebergs, which is consistent with theory. The stratification of water masses in fjords has a noticeable effect on summertime-derived melt estimates, with lower melt rates (and meltwater fluxes) observed in the relatively cold and fresh Polar Water layer and higher melt rates in the underlying warmer and more saline Atlantic Water layer. The meltwater flux dependence on submerged area, particularly within the deeper Atlantic Water layer, suggests that changes in the characteristics of icebergs (size/shape/keel-depth) calved from a tidewater glacier will alter the magnitude and distribution of meltwater fluxes within the fjord, which may in turn influence fjord circulation and the heat content delivered to the glacier terminus.

  8. Analysis of ex-vessel melt jet breakup and coolability. Part 2: Uncertainty analysis

    Energy Technology Data Exchange (ETDEWEB)

    Moriyama, Kiyofumi; Park, Hyun Sun, E-mail: hejsunny@postech.ac.kr; Hwang, Byoungcheol; Jung, Woo Hyun

    2016-06-15

    Highlights: • Uncertainty analysis for quasi steady state melt jet breakup/cooling in APR1400. • Debris solidification reached in most of cases, film boiling quench never reached. • More than 1% molten pool formation in more than half probability. • Significant importance of accident conditions, weak impacts of model parameters. • Ratio of water depth to melt jet breakup length dominates the molten pool formation. - Abstract: An uncertainty analysis was performed on the molten core jet breakup and cooling by assuming the ex-vessel condition in APR1400, a Korean advanced pressurized water reactor, by probabilistic framework with the Latin Hypercube Sampling (LHS) and a fuel–coolant interaction (FCI) simulation code, JASMINE, as a physics model. Eight input variables including four model parameters and four initial/boundary condition variables were chosen as uncertainty variables. Three sets of size 100 samples, in total 300 cases of inputs were produced and simulation results were obtained for each of them. Statistics of the output variables as coolability indexes: the ratio of removed heat to the enthalpy for quench and the fraction of molten pool on the floor, indicated that, in the assumed range of conditions, the debris bed is likely to be cooled in average to the solidification point by ∼85% probability; however, it is not cooled to the minimum film boiling temperature, ∼500 K; and, more than 1% of the melt mass is in a molten pool on the floor by ∼65% probability. The importance analysis showed that the ratio of water pool depth and the melt jet breakup length dominates the cooling performance during the melt discharge transient. The uncertainty of initial and boundary condition variables such as the melt jet size and water pool depth is much more important than that of the model parameters.

  9. Composition and origin of rhyolite melt intersected by drilling in the Krafla geothermal field, Iceland

    Science.gov (United States)

    Zierenberg, R.A.; Schiffman, P.; Barfod, G.H.; Lesher, C.E.; Marks, N.E.; Lowenstern, Jacob B.; Mortensen, A.K.; Pope, E.C.; Bird, D.K.; Reed, M.H.; Friðleifsson, G.O.; Elders, W.A.

    2013-01-01

    The Iceland Deep Drilling Project Well 1 was designed as a 4- to 5-km-deep exploration well with the goal of intercepting supercritical hydrothermal fluids in the Krafla geothermal field, Iceland. The well unexpectedly drilled into a high-silica (76.5 % SiO2) rhyolite melt at approximately 2.1 km. Some of the melt vesiculated while extruding into the drill hole, but most of the recovered cuttings are quenched sparsely phyric, vesicle-poor glass. The phenocryst assemblage is comprised of titanomagnetite, plagioclase, augite, and pigeonite. Compositional zoning in plagioclase and exsolution lamellae in augite and pigeonite record changing crystallization conditions as the melt migrated to its present depth of emplacement. The in situ temperature of the melt is estimated to be between 850 and 920 °C based on two-pyroxene geothermometry and modeling of the crystallization sequence. Volatile content of the glass indicated partial degassing at an in situ pressure that is above hydrostatic (~16 MPa) and below lithostatic (~55 MPa). The major element and minor element composition of the melt are consistent with an origin by partial melting of hydrothermally altered basaltic crust at depth, similar to rhyolite erupted within the Krafla Caldera. Chondrite-normalized REE concentrations show strong light REE enrichment and relative flat patterns with negative Eu anomaly. Strontium isotope values (0.70328) are consistent with mantle-derived melt, but oxygen and hydrogen isotope values are depleted (3.1 and −118 ‰, respectively) relative to mantle values. The hydrogen isotope values overlap those of hydrothermal epidote from rocks altered by the meteoric-water-recharged Krafla geothermal system. The rhyolite melt was emplaced into and has reacted with a felsic intrusive suite that has nearly identical composition. The felsite is composed of quartz, alkali feldspar, plagioclase, titanomagnetite, and augite. Emplacement of the rhyolite magma has resulted in partial melting of

  10. Thermo-mechanical analyses of ITER in-vessel magnetic sensor assembly

    Science.gov (United States)

    Gonzalez, W.; Arshad, S.; Peruzzo, S.; Portales, M.; Rizzolo, A.; Vayakis, G.

    2014-08-01

    This paper summarizes the work concerning design studies of the ITER in-vessel discrete magnetic sensor assemblies, with particular emphasis on the thermal behaviour of the Low Temperature Co-fired Ceramic (LTCC) magnetic sensor and on the thermo-mechanical aspects of the interface with the Vacuum Vessel (VV). The paper summarises the results of FEM thermal analyses performed on the LTCC sensor head and on the sensor assembly to assess the temperature distribution during operating conditions, which could affect the sensor signal due to Temperature-Induced Electromotive Force effect. The paper then concentrates on mechanical analysis of the Base-Plate to assess that the stress and deformation due to the welding to the VV are acceptable to guarantee a sound installation and a suitable thermal contact of the sensor assembly to the VV.

  11. Physics design of the in-vessel collection optics for the ITER electron cyclotron emission diagnostic

    Science.gov (United States)

    Rowan, W. L.; Houshmandyar, S.; Phillips, P. E.; Austin, M. E.; Beno, J. H.; Hubbard, A. E.; Khodak, A.; Ouroua, A.; Taylor, G.

    2016-11-01

    Measurement of the electron cyclotron emission (ECE) is one of the primary diagnostics for electron temperature in ITER. In-vessel, in-vacuum, and quasi-optical antennas capture sufficient ECE to achieve large signal to noise with microsecond temporal resolution and high spatial resolution while maintaining polarization fidelity. Two similar systems are required. One views the plasma radially. The other is an oblique view. Both views can be used to measure the electron temperature, while the oblique is also sensitive to non-thermal distortion in the bulk electron distribution. The in-vacuum optics for both systems are subject to degradation as they have a direct view of the ITER plasma and will not be accessible for cleaning or replacement for extended periods. Blackbody radiation sources are provided for in situ calibration.

  12. Physics design of the in-vessel collection optics for the ITER electron cyclotron emission diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Rowan, W. L., E-mail: w.l.rowan@austin.utexas.edu; Houshmandyar, S.; Phillips, P. E.; Austin, M. E. [Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712 (United States); Beno, J. H.; Ouroua, A. [Center for Electromechanics, The University of Texas at Austin, Austin, Texas 78712 (United States); Hubbard, A. E. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); Khodak, A.; Taylor, G. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2016-11-15

    Measurement of the electron cyclotron emission (ECE) is one of the primary diagnostics for electron temperature in ITER. In-vessel, in-vacuum, and quasi-optical antennas capture sufficient ECE to achieve large signal to noise with microsecond temporal resolution and high spatial resolution while maintaining polarization fidelity. Two similar systems are required. One views the plasma radially. The other is an oblique view. Both views can be used to measure the electron temperature, while the oblique is also sensitive to non-thermal distortion in the bulk electron distribution. The in-vacuum optics for both systems are subject to degradation as they have a direct view of the ITER plasma and will not be accessible for cleaning or replacement for extended periods. Blackbody radiation sources are provided for in situ calibration.

  13. Safety assessment of in-vessel vapor explosion loads in next generation reactor

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Kwang Hyun; Cho, Jong Rae; Choi, Byung Uk; Kim, Ki Yong; Lee, Kyung Jung [Korea Maritime University, Busan (Korea); Park, Ik Kyu [Seoul National University, Seoul (Korea)

    1998-12-01

    A safety assessment of the reactor vessel lower head integrity under in-vessel vapor explosion loads has been performed. The premixing and explosion calculations were performed using TRACER-II code. Using the calculated explosion pressures imposed on the lower head inner wall, strain calculations were performed using ANSYS code. The explosion analyses show that the explosion impulses are not altered significantly by the uncertain parameters of triggering location and time, fuel and vapor volume fractions in uniform premixture bounding calculations within the conservative ranges. Strain analyses using the calculated pressure loads on the lower head inner wall show that the vapor explosion-induced lower head failure is physically unreasonable. The static analysis using the conservative explosion-end pressure of 7,246 psia shows that the maximum equivalent strain is 4.3% at the bottom of lower head, which is less than the allowable threshold value of 11%. (author). 24 refs., 40 figs., 3 tabs.

  14. Evaluation of the In-vessel Downstream Effects for the APR1400 Design and License

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Jeong-kwan; Kim, Jae-won; Kwon, Sun-guk; Lee, Jae-yong [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    These reports include the licensing issues as follows; the effect of a flow channel gap change, the effect of debris settling, the accuracy of the GF630 flow meter, the effect of bubbles impinging on the bottom nozzle, and the bypass fiber amount. In this paper, the valuation results of the in-vessel downstream effects for the APR1400 were described. In addition, the effect of a flow channel gap change and the bypass fiber amount were evaluated. In-vessel downstream effect tests with a mock-up PLUS7 fuel assembly were performed to confirm that the head losses caused by debris meet the available driving head following a LOCA. All the test results showed lower pressure drops than the available head limits. Therefore, a sufficient driving force is available to maintain an adequate flow rate, and the LTCC capability is adequately maintained in the APR1400. A sensitivity test was conducted to assess the effect of a change in the gap size between the mock-up fuel assembly and the test column. The maximum pressure drop recorded for the test was 19.73 kPa under the re-manufactured condition. This value is larger by 1.6% than the previous test result (19.4 kPa) under the same conditions. As such, changing the gap of the flow path between the mock-up fuel assembly and the test column from the previous manufactured conditions to the re-manufactured conditions is expected to result in a slight increase in the differential pressure. However, this is a negligible amount compared to the test uncertainty value of 25%.

  15. Feedstock optimization of in-vessel food waste composting systems for inactivation of pathogenic microorganisms.

    Science.gov (United States)

    Cekmecelioglu, Deniz; Demirci, Ali; Graves, Robert E

    2005-03-01

    An optimum composting recipe was investigated to reduce pathogenic microorganisms in a forced-aerated in-vessel system (55 liters). The feedstocks used for in-vessel composting were food waste, cow manure, and bulking materials (wood shavings and mulch hay). A statistical extreme vertices mixture design method was used to design the composting experiments and analyze the collected data. Each mixture (nine total) was replicated randomly three times. Temperature was monitored as an indicator of the efficiency of the composting experiments. The maximum temperature values of the mixtures were used as a response for both extreme vertices mixture design and statistical analyses. Chemical changes (moisture content, carbon/nitrogen ratio, volatile solids, and pH) and reductions of indicator (fecal coliforms and fecal streptococci) and pathogenic microorganisms (Salmonella and Escherichia coli O157:H7) were measured by the most-probable-number method before and after a 12-day composting period. Maximum temperatures for the tested compost mixtures were in the range of 37.0 to 54.7 degrees C. Extreme vertices mixture design analysis of the surface plot suggested an optimum mixture containing 50% food waste, 40% manure, and 10% bulking agents. This optimum mixture achieved maximum temperatures of 54.7 to 56.6 degrees C for about 3.3 days. The total reduction of Salmonella and E. coli O157:H7 were 92.3%, whereas fecal coliforms and fecal streptococci reductions were lower (59.3 and 27.1%, respectively). Future study is neededto evaluate the extreme vertices mixture design method for optimization of large-scale composting.

  16. Comparative Study on Two Melting Simulation Methods: Melting Curve of Gold

    Science.gov (United States)

    Liu, Zhong-Li; Sun, Jun-Sheng; Li, Rui; Zhang, Xiu-Lu; Cai, Ling-Cang

    2016-05-01

    Melting simulation methods are of crucial importance to determining melting temperature of materials efficiently. A high-efficiency melting simulation method saves much simulation time and computational resources. To compare the efficiency of our newly developed shock melting (SM) method with that of the well-established two-phase (TP) method, we calculate the high-pressure melting curve of Au using the two methods based on the optimally selected interatomic potentials. Although we only use 640 atoms to determine the melting temperature of Au in the SM method, the resulting melting curve accords very well with the results from the TP method using much more atoms. Thus, this shows that a much smaller system size in SM method can still achieve a fully converged melting curve compared with the TP method, implying the robustness and efficiency of the SM method. Supported by the National Natural Science Foundation of China under Grant No. 41574076 and the NSAF of China under Grant No. U1230201/A06, and the Young Core Teacher Scheme of Henan Province under Grant No. 2014GGJS-108

  17. Energy Saving Melting and Revert Reduction Technology: Melting Efficiency in Die Casting Operations

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam

    2012-12-15

    This project addressed multiple aspects of the aluminum melting and handling in die casting operations, with the objective of increasing the energy efficiency while improving the quality of the molten metal. The efficiency of melting has always played an important role in the profitability of aluminum die casting operations. Consequently, die casters need to make careful choices in selecting and operating melting equipment and procedures. The capital cost of new melting equipment with higher efficiency can sometimes be recovered relatively fast when it replaces old melting equipment with lower efficiency. Upgrades designed to improve energy efficiency of existing equipment may be well justified. Energy efficiency is however not the only factor in optimizing melting operations. Melt losses and metal quality are also very important. Selection of melting equipment has to take into consideration the specific conditions at the die casting shop such as availability of floor space, average quantity of metal used as well as the ability to supply more metal during peaks in demand. In all these cases, it is essential to make informed decisions based on the best available data.

  18. Modeling soil moisture processes and recharge under a melting snowpack

    Science.gov (United States)

    Flint, A.L.; Flint, L.E.; Dettinger, M.D.

    2008-01-01

    Recharge into granitic bedrock under a melting snowpack is being investigated as part of a study designed to understand hydrologic processes involving snow at Yosemite National Park in the Sierra Nevada Mountains of California. Snowpack measurements, accompanied by water content and matric potential measurements of the soil under the snowpack, allowed for estimates of infiltration into the soil during snowmelt and percolation into the bedrock. During portions of the snowmelt period, infiltration rates into the soil exceeded the permeability of the bedrock and caused ponding to be sustained at the soil-bedrock interface. During a 5-d period with little measured snowmelt, drainage of the ponded water into the underlying fractured granitic bedrock was estimated to be 1.6 cm d?1, which is used as an estimate of bedrock permeability. The numerical simulator TOUGH2 was used to reproduce the field data and evaluate the potential for vertical flow into the fractured bedrock or lateral flow at the bedrock-soil interface. During most of the snowmelt season, the snowmelt rates were near or below the bedrock permeability. The field data and model results support the notion that snowmelt on the shallow soil overlying low permeability bedrock becomes direct infiltration unless the snowmelt rate greatly exceeds the bedrock permeability. Late in the season, melt rates are double that of the bedrock permeability (although only for a few days) and may tend to move laterally at the soil-bedrock interface downgradient and contribute directly to streamflow. ?? Soil Science Society of America.

  19. Origin of impact melt rocks in the Bununu howardite

    Science.gov (United States)

    Klein, L. C.; Hewins, R. H.

    1979-01-01

    The Bununu howardite is a polymict regolith breccia which contains impact melt that is largely restricted to a 1-cm thick intrusion containing residual glass. As in Malvern, the melt rock contains melt with meteoritic Ni-Co contents. The cooling rate, interpreted for forming glass from this composition, is a few tenths of a degree per minute. The intrusive melts rock, which is a feature unique to Bununu, may indicate that Bununu was consolidated at the time of impact melting.

  20. OECD MCCI project Melt Eruption Test (MET) design report, Rev. 2. April 15, 2003.

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, M. T.; Lomperski, S.; Kilsdonk, D. J.; Aeschlimann, R. W.; Basu, S. (Nuclear Engineering Division); (NRC)

    2011-05-23

    The Melt Attack and Coolability Experiments (MACE) program at Argonne National Laboratory addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. The Melt Coolability and Concrete Interaction (MCCI) program is pursuing separate effect tests to examine the viability of the melt coolability mechanisms identified as part of the MACE program. These mechanisms include bulk cooling, water ingression, volcanic eruptions, and crust breach. At the second PRG meeting held at ANL on 22-23 October 2002, a preliminary design1 for a separate effects test to investigate the melt eruption cooling mechanism was presented for PRG review. At this meeting, NUPEC made several recommendations on the experiment approach aimed at optimizing the chances of achieving a floating crust boundary condition in this test. The principal recommendation was to incorporate a mortar sidewall liner into the test design, since data from the COTELS experiment program indicates that corium does not form a strong mechanical bond with this material. Other recommendations included: (i) reduction of the electrode elevation to well below the melt upper surface elevation (since the crust may bond to these solid surfaces), and (ii) favorably taper the mortar liner to facilitate crust detachment and relocation during the experiment. Finally, as a precursor to implementing these modifications, the PRG recommended the development of a design for a small-scale scoping test intended to verify the ability of the mortar liner to preclude formation of an anchored bridge crust under core-concrete interaction conditions. This revised Melt Eruption Test (MET) plan is intended to

  1. Melting of the Earth's inner core.

    Science.gov (United States)

    Gubbins, David; Sreenivasan, Binod; Mound, Jon; Rost, Sebastian

    2011-05-19

    The Earth's magnetic field is generated by a dynamo in the liquid iron core, which convects in response to cooling of the overlying rocky mantle. The core freezes from the innermost surface outward, growing the solid inner core and releasing light elements that drive compositional convection. Mantle convection extracts heat from the core at a rate that has enormous lateral variations. Here we use geodynamo simulations to show that these variations are transferred to the inner-core boundary and can be large enough to cause heat to flow into the inner core. If this were to occur in the Earth, it would cause localized melting. Melting releases heavy liquid that could form the variable-composition layer suggested by an anomaly in seismic velocity in the 150 kilometres immediately above the inner-core boundary. This provides a very simple explanation of the existence of this layer, which otherwise requires additional assumptions such as locking of the inner core to the mantle, translation from its geopotential centre or convection with temperature equal to the solidus but with composition varying from the outer to the inner core. The predominantly narrow downwellings associated with freezing and broad upwellings associated with melting mean that the area of melting could be quite large despite the average dominance of freezing necessary to keep the dynamo going. Localized melting and freezing also provides a strong mechanism for creating seismic anomalies in the inner core itself, much stronger than the effects of variations in heat flow so far considered.

  2. CRYSTALLIZATION AND MELTING OF NYLON 610

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Differential scanning calorimetry was used to study the crystallization and melting of nylon 610. For nylon 610 crystallized from the melt state (260℃), the overall rate of bulk crystallization can be described by a simple Avrami equation with Avrami exponent n≈2, independent of crystallization temperature. With the experimentally obtained Tm0 (235℃~255℃) of nylon 610, the fold surface free energy σe was determined to be 35~38 erg/cm2. The effects of annealing temperature and time on the melting of quenched nylon 610 were also investigated. For nylon 610 quenched at room temperature there is only one DSC endotherm peak DSC scans on annealed samples exhibited an endotherm peak at approximately 10℃ above the annealing temperature. The size and position of the endothermic peak is strongly related to annealing temperature and time. An additional third melting was observed when quenched nylon 610 was annealed at high temperature for a sufficiently long residence time. The existence of the third melting peak suggests that more than one kind of distribution of lamella thickness may occur when quenched nylon610 is annealed. The implications of these results in terms of crystal thickening mechanism were discussed.

  3. Polyether Based Thermoplastic Polyurethane Melt Blown Nonwovens

    Directory of Open Access Journals (Sweden)

    Terezie Zapletalova

    2006-08-01

    Full Text Available A series of melt blown samples were produced from three hardness grades of ether based thermoplastic polyurethane elastomers (TPU. The fabrics were tested to investigate their structure-property relationship in a melt blown process. Solution viscosities of the web were only 20-26% of there original values indicating a large loss in polymer molecular weight during melt blowing. Fiber diameter distributions measured on melt blown samples were found comparable to those made with more conventional polymers. The fiber orientation distribution functions (ODF suggest slight fiber orientation in machine direction. Tensile and elongation properties depended on die-to-collector distance (DCD, polymer hardness and fiber ODF. A strong relationship between the tensile strength and die-to-collector distance was identified and attributed to reduced interfiber adhesion in the web with increasing DCD. The reduction in adhesion was attributed to greater extents of solidification before reaching the forming belt for longer DCDs. This paper is the first in a series relating the influence of the melt blowing process parameters on the polymer properties and the nonwoven fabric properties for block thermoplastic elastomers.

  4. Melt electrospinning of biodegradable polyurethane scaffolds

    Science.gov (United States)

    Karchin, Ari; Simonovsky, Felix I.; Ratner, Buddy D.; Sanders, Joan E.

    2014-01-01

    Electrospinning from the melt, in contrast to from solution, is an attractive tissue engineering scaffold manufacturing process as it allows for the formation of small diameter fibers while eliminating potentially cytotoxic solvents. Despite this, there is a dearth of literature on scaffold formation via melt electrospinning. This is likely due to the technical challenges related to the need for a well-controlled high temperature setup and the difficulty in developing an appropriate polymer. In this paper, a biodegradable and thermally stable polyurethane (PU) is described specifically for use in melt electrospinning. Polymer formulations of aliphatic PUs based on (CH2)4-content diisocyanates, polycaprolactone (PCL), 1,4-butanediamine and 1,4-butanediol (BD) were evaluated for utility in the melt electrospinning process. The final polymer formulation, a catalyst-purified PU based on 1,4-butane diisocyanate, PCL and BD in a 4/1/3 molar ratio with a weight-average molecular weight of about 40 kDa, yielded a nontoxic polymer that could be readily electrospun from the melt. Scaffolds electrospun from this polymer contained point bonds between fibers and mechanical properties analogous to many in vivo soft tissues. PMID:21640853

  5. Intra-cratonic melting as a result of delamination of mantle lithosphere - insight from numerical modelling

    Science.gov (United States)

    Gorczyk, W.; Vogt, K.; Gerya, T.; Hobbs, B. E.

    2012-12-01

    It is becoming increasingly apparent that intense deformation, metamorphism and metasomatism occur within continental cratonic blocks far removed form subducting margins Such changes may occur intra-cratonically arising from lithospheric thickening and the development of gravitational instabilities, but mostly occur at the boundary of cratonic blocks. The contact of two cratons is characterized by rheological lateral variations within mantle-lithosphere and overlying crust. Tectonic stresses acting on craton/craton boundaries may lead to thinning or thickening due to delamination of the mantle lithosphere. This is reflected in tectonic deformation, topography evolution, melting and crustal metamorphism. To understand the controls on these processes a number of 2D, coupled petrological thermo-mechanical numerical experiments has been performed to test the response of a laterally weakened zone to a compressional regime. The results indicate that the presence of water-bearing minerals in the lithosphere and lower crust is essential to initiate melting, which in the later stages may expand to dry melting of crust and mantle. In the case of anhydrous crust and lithosphere, no melting occurs. Thus a variety of instabilities, melting behaviour and topographic responses occurs at the base of the lithosphere as well as intensive faulting and buckling in the crust dependent on the strength and "water" content of the lithosphere.

  6. Study of Using Solar Thermal Power for the Margarine Melting Heat Process.

    Science.gov (United States)

    Sharaf Eldean, Mohamed A; Soliman, A M

    2015-04-01

    The heating process of melting margarine requires a vast amount of thermal energy due to its high melting point and the size of the reservoir it is contained in. Existing methods to heat margarine have a high hourly cost of production and use fossil fuels which have been shown to have a negative impact on the environment. Thus, we perform an analytical feasibility study of using solar thermal power as an alternative energy source for the margarine melting process. In this study, the efficiency and cost effectiveness of a parabolic trough collector (PTC) solar field are compared with that of a steam boiler. Different working fluids (water vapor and Therminol-VP1 heat transfer oil (HTO)) through the solar field are also investigated. The results reveal the total hourly cost ($/h) by the conventional configuration is much greater than the solar applications regardless of the type of working fluid. Moreover, the conventional configuration causes a negative impact to the environment by increasing the amount of CO2, CO, and NO2 by 117.4 kg/day, 184 kg/day, and 74.7 kg/day, respectively. Optimized period of melt and tank volume parameters at temperature differences not exceeding 25 °C are found to be 8-10 h and 100 m(3), respectively. The solar PTC operated with water and steam as the working fluid is recommended as a vital alternative for the margarine melting heating process.

  7. The impact of melt ponds on summertime microwave brightness temperatures and sea-ice concentrations

    Science.gov (United States)

    Kern, Stefan; Rösel, Anja; Toudal Pedersen, Leif; Ivanova, Natalia; Saldo, Roberto; Tage Tonboe, Rasmus

    2016-09-01

    Sea-ice concentrations derived from satellite microwave brightness temperatures are less accurate during summer. In the Arctic Ocean the lack of accuracy is primarily caused by melt ponds, but also by changes in the properties of snow and the sea-ice surface itself. We investigate the sensitivity of eight sea-ice concentration retrieval algorithms to melt ponds by comparing sea-ice concentration with the melt-pond fraction. We derive gridded daily sea-ice concentrations from microwave brightness temperatures of summer 2009. We derive the daily fraction of melt ponds, open water between ice floes, and the ice-surface fraction from contemporary Moderate Resolution Spectroradiometer (MODIS) reflectance data. We only use grid cells where the MODIS sea-ice concentration, which is the melt-pond fraction plus the ice-surface fraction, exceeds 90 %. For one group of algorithms, e.g., Bristol and Comiso bootstrap frequency mode (Bootstrap_f), sea-ice concentrations are linearly related to the MODIS melt-pond fraction quite clearly after June. For other algorithms, e.g., Near90GHz and Comiso bootstrap polarization mode (Bootstrap_p), this relationship is weaker and develops later in summer. We attribute the variation of the sensitivity to the melt-pond fraction across the algorithms to a different sensitivity of the brightness temperatures to snow-property variations. We find an underestimation of the sea-ice concentration by between 14 % (Bootstrap_f) and 26 % (Bootstrap_p) for 100 % sea ice with a melt-pond fraction of 40 %. The underestimation reduces to 0 % for a melt-pond fraction of 20 %. In presence of real open water between ice floes, the sea-ice concentration is overestimated by between 26 % (Bootstrap_f) and 14 % (Bootstrap_p) at 60 % sea-ice concentration and by 20 % across all algorithms at 80 % sea-ice concentration. None of the algorithms investigated performs best based on our investigation of data from summer 2009. We suggest that those algorithms which are

  8. Investigating sulfur partitioning between nominally volatile-free minerals and silicate melts

    Science.gov (United States)

    Marzoli, A.; Callegaro, S.; Baker, D. R.; Geraki, K.; Maneta, V.

    2015-12-01

    Despite the key role played by volatile species in magmatic systems, it is still challenging to quantify their concentrations in ancient melts. We suggested a quantitative approach for estimating S contents in basaltic melts (Callegaro et al., 2014), based on direct measurement of S on clinopyroxene and calculation of its concentration in the melt through an experimentally determined partition coefficient (KD). We further investigated the partitioning of sulfur between silicate melts and nominally volatile-free minerals (olivine, orthopyroxene, clinopyroxene, and plagioclase), as well as between melt and amphibole. Partitioning experiments were performed with basaltic, andesitic and dacitic bulk compositions, at hydrous and anhydrous conditions, and at high and low oxygen fugacities (fO2), where sulfur in the melt is dominantly present as an S6+ or S2- species, respectively (Wilke et al., 2011). Sulfur concentrations in melts were measured by electron microprobe and in crystals by synchrotron X-ray fluorescence. At low fO2 the average crystal/liquid KDs for sulfur vary from 0.0004 (at a maximum) for olivine, to 0.003 (another maximum) for orthopyroxene, to 0.03 for clinopyroxene, and to 0.07 for plagioclase. The KDs correlate positively with the cation-oxygen bond lengths in the crystals. At high fO2 the KDs drop to approximately one-third of those observed at low fO2. These observations suggest that S2- replaces oxygen in the crystal structure. Water has no measureable influence on the crystal/melt partitioning of sulfur. Clinopyroxene/melt KDs are correlated with the Mg/(Mg+Fe) ratio of the crystal, but appear insensitive to the IVAl in the structure. Plagioclase/melt S partitioning appears unaffected by anorthite content and iron concentration in the crystal. These new KDs allow the determination of sulfur concentration in the igneous melts co-existing with these crystals and provide insights into the volatile concentrations of ancient magmas and their possible

  9. Evaporative Heat Transfer Mechanisms within a Heat Melt Compactor

    Science.gov (United States)

    Golliher, Eric L.; Gotti, Daniel J.; Rymut, Joseph Edward; Nguyen, Brian K; Owens, Jay C.; Pace, Gregory S.; Fisher, John W.; Hong, Andrew E.

    2013-01-01

    This paper will discuss the status of microgravity analysis and testing for the development of a Heat Melt Compactor (HMC). Since fluids behave completely differently in microgravity, the evaporation process for the HMC is expected to be different than in 1-g. A thermal model is developed to support the design and operation of the HMC. Also, low-gravity aircraft flight data is described to assess the point at which water may be squeezed out of the HMC during microgravity operation. For optimum heat transfer operation of the HMC, the compaction process should stop prior to any water exiting the HMC, but nevertheless seek to compact as much as possible to cause high heat transfer and therefore shorter evaporation times.

  10. Efficiencies of metal separation and recovery in ash-melting of municipal solid waste under non-oxidative atmospheres with different reducing abilities.

    Science.gov (United States)

    Okada, Takashi; Tomikawa, Hiroki

    2016-01-15

    Ash-melting of municipal solid waste produces molten metal that contains Fe and Cu, and melting furnace fly ash (MFA) that contains Pb and Zn. To recover the metal from the fly ash, Pb and Zn are extracted from the ash by water or enriched in the ash by washing out salts; this separation depends on their leachability. In this study, we investigated the effects of the reducing ability of the atmosphere on the efficiencies of metal separation during melting and metal recovery in water treatment. Different feedstocks (incineration residues) were melted under N2 or CO + N2 atmospheres. In some of the feedstock materials, volatilization of metallic Cu into MFA was promoted under the atmosphere with greater reducing ability (CO + N2). This increased volatilization inhibited the metal separation in the ash-melting process. Moreover, the higher reducing ability inhibited the formation of water-soluble lead chlorides and decreased the efficiency of metal recovery from the MFA because of the water leaching of the lead compounds. The reducing ability of the atmosphere is difficult to control uniformly in actual ash-melting plants, and we investigated appropriate melting conditions under which the effect of the reducing ability was minimized to promote metal separation and recovery. This minimization was achieved by melting incineration fly ash without additives with Cl gas treatment at 1400 °C.

  11. Melt Dispersion and Direct Containment Heating (DCH) Experiments für KONVOI reactors (KIT Scientific Reports ; 7567)

    OpenAIRE

    Meyer, Leonhard

    2010-01-01

    The DISCO-H test facility was used to perform scaled experiments that simulate melt ejection scenarios under low system pressure in Severe Accidents in Pressurized Water Reactors (PWR). These experiments are designed to investigate the fluid-dynamic, thermal and chemical processes during melt ejection out of a breach in the lower head of a PWR pressure vessel at pressures around and below 2 MPa with an iron-alumina melt and steam. The report presents results from a test series with the geomet...

  12. Analysis of picosecond pulsed laser melted graphite

    Energy Technology Data Exchange (ETDEWEB)

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M.S.; Huang, C.Y.; Malvezzi, A.M.; Bloembergen, N.

    1986-01-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm/sup -1/ and the disorder-induced mode at 1360 cm/sup -1/, the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nonosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence.

  13. Analysis of Picosecond Pulsed Laser Melted Graphite

    Science.gov (United States)

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M. S.; Huang, C. Y.; Malvezzi, A. M.; Bloembergen, N.

    1986-12-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm{sup -1} and the disorder-induced mode at 1360 cm{sup -1}, the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nanosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence.

  14. Stress Relaxation in Entangled Polymer Melts

    DEFF Research Database (Denmark)

    Hou, Ji-Xuan; Svaneborg, Carsten; Everaers, Ralf

    2010-01-01

    We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements and into the t......We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements...... and into the terminal relaxation regime for Z=10. Using the known (Rouse) mobility of unentangled chains and the melt entanglement length determined via the primitive path analysis of the microscopic topological state of our systems, we have performed parameter-free tests of several different tube models. We find...

  15. A model for melting of confined DNA

    CERN Document Server

    Werner, E; Ambjörnsson, T; Mehlig, B

    2015-01-01

    When DNA molecules are heated they denature. This occurs locally so that loops of molten single DNA strands form, connected by intact double-stranded DNA pieces. The properties of this "melting" transition have been intensively investigated. Recently there has been a surge of interest in this question, caused by experiments determining the properties of partially bound DNA confined to nanochannels. But how does such confinement affect the melting transition? To answer this question we introduce, and solve a model predicting how confinement affects the melting transition for a simple model system by first disregarding the effect of self-avoidance. We find that the transition is smoother for narrower channels. By means of Monte-Carlo simulations we then show that a model incorporating self-avoidance shows qualitatively the same behaviour and that the effect of confinement is stronger than in the ideal case.

  16. Scleral melt following Retisert intravitreal fluocinolone implant

    Directory of Open Access Journals (Sweden)

    Georgalas I

    2014-11-01

    Full Text Available Ilias Georgalas,1 Chrysanthi Koutsandrea,1 Dimitrios Papaconstantinou,1 Dimitrios Mpouritis,1 Petros Petrou1,2 1Ophthalmology Department, University of Athens, Athens, Greece; 2Moorfields Eye Hospital, London, UKAbstract: Intravitreal fluocinolone acetonide implant (Retisert has a high potency, a low solubility, and a very short duration of action in the systemic circulation, enabling the steroid pellet to be small and reducing the risk of systemic side effects. Scleral melt has not been reported as a possible complication of Retisert implant. The authors describe the occurrence of scleral melt 18 months after the implantation of fluocinolone acetonide implant in a 42-year-old Caucasian woman. To the authors’ knowledge, this is the first report of this possible complication.Keywords: Retisert, scleral melt, complication, surgical management

  17. Monitoring and Modelling Glacier Melt and Runoff on Juncal Norte Glacier, Aconcagua River Basin, Central Chile

    Science.gov (United States)

    Pellicciotti, F.; Helbing, J. F.; Araos, J.; Favier, V.; Rivera, A.; Corripio, J.; Sicart, J. M.

    2006-12-01

    Results from a recent glacio-meteorological experiment on the Juncal Norte glacier, in central Chile, are presented. Melt water is a crucial resource in the Central Andes, as it provides drinking water, water for agriculture and for industrial uses. There is also increasing competition for water use and allocation, as water demands from mining and industry are rising. Assessing water availability in this region and its relation with climatic variations is therefore crucial. The Dry Central Andes are characterised by a climatic setting different from that of the Alps and the subtropical Andes of Bolivia and Peru. Summers are very dry and stable, with precipitation close to zero and low relative humidity. Solar radiation is very intense, and plays a key role in the energy balance of snow covers and glaciers. The main aim of this study is to investigate the glacier-climate interaction in this area, with particular attention devoted to advanced modelling techniques for the spatial redistribution of meteorological variables, in order to gain an accurate picture of the ablation processes typical of these latitudes. During the ablation season 2005/2006, an extensive field campaign was conducted on the Juncal Norte glacier, aimed at monitoring the melt and runoff generation processes on this remote glacier in the dry Andes. Melt rates, runoff at the snout, meteorological variables over and near the glacier, GPS data and glacier topography were recorded over the entire ablation season. Using this extensive and accurate data set, the spatial and temporal variability of the meteorological variables that drive the melt process on the glacier is investigated, together with the process of runoff generation. An energy balance model is used to simulate melt across the glacier, and special attention is devoted to the modelling of the solar radiation energy flux. The components of the energy balance are compared with those of Alpine basins. The validity of parameterisations of the

  18. Fluxed-melting of shallow and hot high-grade metamorphic rocks in the Namcha Barwa Massif: A new mechanism for the generation of adakitic melts

    Science.gov (United States)

    Zeng, L.; Liu, J.; Hou, Z.; Gao, L.; Xie, K.

    2008-12-01

    Extremely rapid exhumation has been a major factor leading to rapid advection of relatively hot crustal rocks into shallow crustal levels in the Namcha Barwa massif. In such a hot tectonic regime, it is conceivable that hot crustal material can undergo partial melting assisted by excessive water. Previous studies indeed have documented extremely young Na-rich granitic rocks (63.5 and up to 237.1), consistent with garnet either as a non-reactant phase or as a residue phase; (2) these leucosomes have similar Sr isotope compositions to their host rocks, but some of them have Nd isotope compositions significantly deviated from their host by ~4-5 epsilon units. Since high-grade metamorphic rocks in the Namcha Barwa were already shallower than 10 km in the past 5 million years, these data is best explained by water- fluxed melting of granitic components in the source rocks. This interpretation is also consistent with at water- present and relatively lower temperature conditions, both apatite and garnet behaves as non-reactant phases during a partial melting event, which could lead to depletion of garnet-compatible elements as well as negative shift in Nd isotope compositions in the amphibolite- or metapelite-derived melts. Our data emphasize that at rapidly exhumed and relatively hot tectonic regimes (e.g. the Nanga Parbat and Namcha Barwa areas), fluxed-melting of high-graded metamorphic rocks at relatively shallower crustal levels could be another important mechanism to produced adakitic magma and associated porphyritic Cu-Au deposits.

  19. How to identify garnet lherzolite melts and distinguish them from pyroxenite melts

    Science.gov (United States)

    Grove, T. L.; Holbig, E.; Barr, J. A.; Till, C.; Krawczynski, M. J.

    2013-12-01

    Liquids form in equilibrium with garnet lherzolite sources when the Earth's mantle melts at depths of greater than ~ 60 km. We present a phase equilibrium investigation of Tibetan plateau olivine leucitites from 2.2 to 2.8 GPa and 1380 to 1480 °C. The resulting liquids were multiply saturated with spinel and garnet lherzolite assemblages (olivine, orthopyroxene, clinopyroxene and spinel +/-garnet) under nominally anhydrous conditions. These SiO2-undersaturated liquids and published experimental data have been used to develop a new model that parameterizes the major element compositions of garnet lherzolite partial melts, allowing the prediction of melt compositions from depleted to metasomatically enriched peridotite. The model is calibrated over the pressure range of 1.9 to 6 GPa. The model also predicts the suprasolidus pressure and temperature of the spinel to garnet lherzolite phase transition for natural peridotite compositions. Combined with the recent parameterization of melting in the plagioclase- and spinel- lherzolite facies (Till et al., 2012, JGR, 117, B06206), the new model distinguishes between melts of garnet vs. spinel vs. plagioclase lherzolites, but can also be used to distinguish between melts of lherzolitic vs. pyroxenitic source regions, allowing source lithology to be uniquely identified. Pyroxenite melts fall into two compositionally distinct groups; an olivine-normative, SiO2-undersaturated group and quartz-normative, SiO2-oversaturated group. Melts of plagioclase, spinel, and garnet lherzolite plot between these two types of pyroxenitic melts in mineral normative composition space. When our model is applied to high-K lavas erupted in the Tibetan plateau, we find that these magmas are derived from both pyroxenite and lherzolite source regions. Distinctive enrichments in compatible trace elements (Ni, Cr) are observed in the lherzolite-derived magmas. Applied to Hawaiian basalts, our model suggests the transitional and weakly alkaline pre

  20. Chemical reactions in solvents and melts

    CERN Document Server

    Charlot, G

    1969-01-01

    Chemical Reactions in Solvents and Melts discusses the use of organic and inorganic compounds as well as of melts as solvents. This book examines the applications in organic and inorganic chemistry as well as in electrochemistry. Organized into two parts encompassing 15 chapters, this book begins with an overview of the general properties and the different types of reactions, including acid-base reactions, complex formation reactions, and oxidation-reduction reactions. This text then describes the properties of inert and active solvents. Other chapters consider the proton transfer reactions in

  1. Thermal melting studies of ligand DNA interactions.

    Science.gov (United States)

    Guédin, Aurore; Lacroix, Laurent; Mergny, Jean-Louis

    2010-01-01

    A simple thermal melting experiment may be used to demonstrate the stabilization of a given structure by a ligand (usually a small molecule, sometimes a peptide). Preparation of the sample is straightforward, and the experiment itself requires an inexpensive apparatus. Furthermore, reasonably low amounts of sample are required. A qualitative analysis of the data is simple: An increase in the melting temperature (T(m)) indicates preferential binding to the folded form as compared to the unfolded form. However, it is perilous to derive an affinity constant from an increase in T(m) as other factors play a role.

  2. Experimental observation of Minkowski spacetime melting

    CERN Document Server

    Smolyaninov, Igor I

    2015-01-01

    Cobalt nanoparticle-based ferrofluid in the presence of an external magnetic field forms a self-assembled hyperbolic metamaterial, which may be described as an effective 3D Minkowski spacetime for extraordinary photons. If the magnetic field is not strong enough, this effective Minkowski spacetime gradually melts under the influence of thermal fluctuations. On the other hand, it may restore itself if the magnetic field is increased back to its original value. Here we present direct microscopic visualization of such a Minkowski spacetime melting/crystallization, which is somewhat similar to hypothesized formation of the Minkowski spacetime in loop quantum cosmology.

  3. Influence of Grain Boundary on Melting

    Institute of Scientific and Technical Information of China (English)

    王暾; 周富信; 刘曰武

    2001-01-01

    The temperature behaviour of an Al bicrystal with surfaces consisting of (110) and (111) crystals is simulated using molecular dynamics. The result shows that the (110) crystal losses its crystalline order at 820K, whereas the disorder does not propagate through the (111) crystal at this temperature. Instead, some disordered atoms are recrystallized into the (111) crystal and the initial grain boundary changes into a stable order-disorder interface. Thus, it was discovered that at a temperature near its melting point, the (111) crystal grew and obstructed the propagation of disorder. Such an obstruction is helpfulfor understanding melting.

  4. Stress Relaxation in Entangled Polymer Melts

    DEFF Research Database (Denmark)

    Hou, Ji-Xuan; Svaneborg, Carsten; Everaers, Ralf

    2010-01-01

    and into the terminal relaxation regime for Z=10. Using the known (Rouse) mobility of unentangled chains and the melt entanglement length determined via the primitive path analysis of the microscopic topological state of our systems, we have performed parameter-free tests of several different tube models. We find......We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements...

  5. 3He melting pressure temperature scale

    DEFF Research Database (Denmark)

    Halperin, W.P.; Archie, C.N.; Richardson, R.C.;

    1976-01-01

    The latent heat for solidification of **3He has been measured along the **3He melting curve between 23 and 1 mK. A temperature scale is established which depends only on measurements of heat, pressure and volume, and on the condition that the entropy of solid **3He approaches R ln 2 at high...... temperatures. The A feature of the melting curve which suggests itself as a thermometric fixed point is found to be T//A equals 2. 75 plus or minus 0. 11 mK. The agreement between this value and independent measurements of T//A, based on nuclear or electronic paramagnetism, Johnson noise thermometry...

  6. Solubility and dissolution enhancement of HPMC - based solid dispersions of carbamazepine by hot-melt extrusion technique

    OpenAIRE

    Sharadchandra Dagadu Javeer; Purnima Dhanraj Amin

    2014-01-01

    The objective of this study was to investigate solid dispersions (SDs) of poorly water soluble drug carbamazepine (CBZ), prepared using low viscosity grade hydroxypropyl methyl cellulose (HPMC) (Methocel® E3 LV and Methocel® E5 LV) by hot-melt extrusion (HME) technology. Saturation solubility and dissolution profile of CBZ was studied. Characterization of hot-melt extruded samples was done by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray di...

  7. Additive manufacturing of 316L stainless steel by electron beam melting for nuclear fusion applications

    Science.gov (United States)

    Zhong, Yuan; Rännar, Lars-Erik; Liu, Leifeng; Koptyug, Andrey; Wikman, Stefan; Olsen, Jon; Cui, Daqing; Shen, Zhijian

    2017-04-01

    A feasibility study was performed to fabricate ITER In-Vessel components by one of the metal additive manufacturing methods, Electron Beam Melting® (EBM®). Solid specimens of SS316L with 99.8% relative density were prepared from gas atomized precursor powder granules. After the EBM® process the phase remains as austenite and the composition has practically not been changed. The RCC-MR code used for nuclear pressure vessels provides guidelines for this study and tensile tests and Charpy-V tests were carried out at 22 °C (RT) and 250 °C (ET). This work provides the first set of mechanical and microstructure data of EBM® SS316L for nuclear fusion applications. The mechanical testing shows that the yield strength, ductility and toughness are well above the acceptance criteria and only the ultimate tensile strength of EBM® SS316L is below the RCC-MR code. Microstructure characterizations reveal the presence of hierarchical structures consisting of solidified melt pools, columnar grains and irregular shaped sub-grains. Lots of precipitates enriched in Cr and Mo are observed at columnar grain boundaries while no sign of element segregation is shown at the sub-grain boundaries. Such a unique microstructure forms during a non-equilibrium process, comprising rapid solidification and a gradient 'annealing' process due to anisotropic thermal flow of accumulated heat inside the powder granule matrix. Relations between process parameters, specimen geometry (total building time) and sub-grain structure are discussed. Defects are formed mainly due to the large layer thickness (100 μm) which generates insufficient bonding between a few of the adjacently formed melt pools during the process. Further studies should focus on adjusting layer thickness to improve the strength of EBM® SS316L and optimizing total building time.

  8. Dendrite Array Disruption by Bubbles during Re-melting in a Microgravity Environment

    Science.gov (United States)

    Grugel, Richard N.

    2012-01-01

    As part of the Pore Formation and Mobility Investigation (PFMI), Succinonitrile Water alloys consisting of aligned dendritic arrays were re-melted prior to conducting directional solidification experiments in the microgravity environment aboard the International Space Station. Thermocapillary convection initiated by bubbles at the solid-liquid interface during controlled melt back of the alloy was observed to disrupt the initial dendritic alignment. Disruption ranged from detaching large arrays to the transport of small dendrite fragments at the interface. The role of bubble size and origin is discussed along with subsequent consequences upon reinitiating controlled solidification.

  9. Vacuum Arc Melting Processes for Biomedical Ni-Ti Shape Memory Alloy

    Directory of Open Access Journals (Sweden)

    Tsai De-Chang

    2015-01-01

    Full Text Available This study primarily involved using a vacuum arc remelting (VAR process to prepare a nitinol shape-memory alloy with distinct ratios of alloy components (nitinol: 54.5 wt% to 57 wt%. An advantage of using the VAR process is the adoption of a water-cooled copper crucible, which effectively prevents crucible pollution and impurity infiltration. Optimising the melting production process enables control of the alloy component and facilitates a uniformly mixed compound during subsequent processing. This study involved purifying nickel and titanium and examining the characteristics of nitinol alloy after alloy melt, including its microstructure, mechanical properties, phase transition temperature, and chemical components.

  10. Recent Changes in Arctic Sea Ice Melt Onset, Freeze-Up, and Melt Season Length

    Science.gov (United States)

    Markus, Thorsten; Stroeve, Julienne C.; Miller, Jeffrey

    2010-01-01

    In order to explore changes and trends in the timing of Arctic sea ice melt onset and freeze-up and therefore melt season length, we developed a method that obtains this information directly from satellite passive microwave data, creating a consistent data set from 1979 through present. We furthermore distinguish between early melt (the first day of the year when melt is detected) and the first day of continuous melt. A similar distinction is made for the freeze-up. Using this method we analyze trends in melt onset and freeze-up for 10 different Arctic regions. In all regions except for the Sea of Okhotsk, which shows a very slight and statistically insignificant positive trend (O.4 days/decade), trends in melt onset are negative, i.e. towards earlier melt. The trends range from -1.0day/decade for the Bering Sea to -7.3 days/decade for the East Greenland Sea. Except for the Sea of Okhotsk all areas also show a trend towards later autumn freeze onset. The Chukchi/Beaufort Seas and Laptev/East Siberian Seas observe the strongest trends with 7 days/decade. For the entire Arctic, the melt season length has increased by about 20 days over the last 30 years. Largest trends of over 1O days/decade are seen for Hudson Bay, the East Greenland Sea the Laptev/East Siberian Seas, and the Chukchi/Beaufort Seas. Those trends are statistically significant a1 the 99% level.

  11. Recent Changes in Arctic Sea Ice Melt Onset, Freeze-Up, and Melt Season Length

    Science.gov (United States)

    Markus, Thorsten; Stroeve, Julienne C.; Miller, Jeffrey

    2010-01-01

    In order to explore changes and trends in the timing of Arctic sea ice melt onset and freeze-up and therefore melt season length, we developed a method that obtains this information directly from satellite passive microwave data, creating a consistent data set from 1979 through present. We furthermore distinguish between early melt (the first day of the year when melt is detected) and the first day of continuous melt. A similar distinction is made for the freeze-up. Using this method we analyze trends in melt onset and freeze-up for 10 different Arctic regions. In all regions except for the Sea of Okhotsk, which shows a very slight and statistically insignificant positive trend (O.4 days/decade), trends in melt onset are negative, i.e. towards earlier melt. The trends range from -1.0day/decade for the Bering Sea to -7.3 days/decade for the East Greenland Sea. Except for the Sea of Okhotsk all areas also show a trend towards later autumn freeze onset. The Chukchi/Beaufort Seas and Laptev/East Siberian Seas observe the strongest trends with 7 days/decade. For the entire Arctic, the melt season length has increased by about 20 days over the last 30 years. Largest trends of over 1O days/decade are seen for Hudson Bay, the East Greenland Sea the Laptev/East Siberian Seas, and the Chukchi/Beaufort Seas. Those trends are statistically significant a1 the 99% level.

  12. Asia's water balance

    NARCIS (Netherlands)

    Immerzeel, W.W.; Bierkens, M.F.P.

    The availability of water for human consumption and agriculture can no longer be taken for granted. Various facets of water stress at different spatial scales, such as groundwater depletion1,2, climate change and population increase3, and glacier and s