Behavior of mercury in the formic acid vent condenser. Final report

International Nuclear Information System (INIS)

Zamecnik, J.R.

1996-01-01

The concentrations of mercury at the FAVC inlet and exit were measured during the BL1 and PX6 runs of the Integrated DWPF Melter System (IDMS) with the HEME bypassed and without the ammonia scrubber. The results showed that mercury concentrations of approximately 1.02-12.7 (mean 5.74) times saturation occurred at the FAVC exit. The concentration of mercury at the FAVC inlet was found to be 0.66-6.2 times the saturation value (based on the SRAT condenser exit). In the PX7 run, the ammonia scrubber was used and the FAVC HEME was not bypassed. The results from this run showed that the FAVC inlet concentrations again were above saturation (1.45-15.5 times saturation), but that the FAVC exit concentrations were only 0.02-0.41 times saturation (except for one data point at 1.61 times saturation). Operation of the FAVC without the HEME could therefore result in FAVC exit mercury concentrations of greater than 5.74 times saturation, which would result in DWPF emitting greater than 405 lb/yr of mercury at 100 percent attainment; this quantity is well in excess of the permit limit of 175 lb/yr (for all of DWPF). However, with the HEME in place, the emissions are predicted to be only about 40 lb/yr for an FAVC exit temperature of 10 degrees C. The experimental results also indicate that the ammonia scrubbers have little effect on the removal of mercury

Venting krypton-85 from the Three Mile Island Unit 2 reactor building

International Nuclear Information System (INIS)

Burton, H.M.

1981-01-01

To permit the less restricted access to the reactor building necessary to maintain instrumentation and equipment, and to proceed towad the total decontamination of the facility, General Public Utilities, operators of the facility referred to hereafter as GPU, asked the United States Nuclear Regulatory Commission, or NRC, for permission to remove the 85 Kr from the reactor building by venting it to the environment. GPU supported their request with the Safety Analysis and Environmental Assessment Report on the proposed reactor building venting plan. On June 12, 1980, after seven months of licensing deliberations and numerous public hearings, the NRC granted GPU's request. The actual venting took place between June 28 and July 11, 1980. This report presents an overview of the detailed effort involved in the TMI-2 reactor building venting program. The findings reported here are condensed from a published report entitled TMI-2 Reactor Building Purge--Kr-85 Venting

24 CFR 3280.611 - Vents and venting.

Science.gov (United States)

2010-04-01

...) Materials—(1) Pipe. Vent piping shall be standard weight steel, wrought iron, brass, copper tube DWV, listed...) Size of vent piping—(1) Main vent. The drain piping for each toilet shall be vented by a 11/2 inch... venting cross section of a 11/2 inch diameter vent, connected to the toilet drain by one of the following...

BWR Passive Containment Cooling System by condensation-driven natural circulation

International Nuclear Information System (INIS)

Vierow, K.M.; Townsend, H.E.; Fitch, J.R.; Andersen, J.G.M.; Alamgir, M.; Schrock, V.E.

1991-01-01

A method of long-term decay heat removal which is safe, reliable, and passive has been incorporated into the design of the Simplified Boiling Water Reactor (SBWR). The primary functions of the Passive Containment Cooling System (PCCS) are to remove heat and maintain the containment pressure below allowable levels following a LOCA. A key component of the PCCS is the PCC condenser unit (PCC). By natural circulation, a steam-nitrogen mixture flows into the PCC heat exchanger, condensate drains to the reactor pressure vessel (RPV), and noncondensables are vented to the suppression chamber (S/C). This analysis focuses on three significant thermal-hydraulic phenomena which occur in the system. Specifically, steam condensation in the presence of a noncondensable, the PCC noncondensable venting and the natural circulation are discussed. Results of TRACG simulations are presented which show that the PCCS performs its intended functions. (author)

Preoperational test report, primary ventilation condensate system

Energy Technology Data Exchange (ETDEWEB)

Clifton, F.T.

1997-01-29

Preoperational test report for Primary Ventilation Condensate System, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides a collection point for condensate generated by the W-030 primary vent offgas cooling system serving tanks AYIOI, AY102, AZIOI, AZI02. The system is located inside a shielded ventilation equipment cell and consists of a condensate seal pot, sampling features, a drain line to existing Catch Tank 241-AZ-151, and a cell sump jet pump. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

ANALYSIS OF VENTING OF A RESIN SLURRY

Energy Technology Data Exchange (ETDEWEB)

Laurinat, J.; Hensel, S.

2012-03-27

A resin slurry venting analysis was conducted to address safety issues associated with overpressurization of ion exchange columns used in the Purex process at the Savannah River Site (SRS). If flow to these columns were inadvertently interrupted, an exothermic runaway reaction could occur between the ion exchange resin and the nitric acid used in the feed stream. The nitric acid-resin reaction generates significant quantities of noncondensable gases, which would pressurize the column. To prevent the column from rupturing during such events, rupture disks are installed on the column vent lines. The venting analysis models accelerating rate calorimeter (ARC) tests and data from tests that were performed in a vented test vessel with a rupture disk. The tests showed that the pressure inside the test vessel continued to increase after the rupture disk opened, though at a slower rate than prior to the rupture. Calculated maximum discharge rates for the resin venting tests exceeded the measured rates of gas generation, so the vent size was sufficient to relieve the pressure in the test vessel if the vent flow rate was constant. The increase in the vessel pressure is modeled as a transient phenomenon associated with expansion of the resin slurry/gas mixture upon rupture of the disk. It is postulated that the maximum pressure at the end of this expansion is limited by energy minimization to approximately 1.5 times the rupture disk burst pressure. The magnitude of this pressure increase is consistent with the measured pressure transients. The results of this analysis demonstrate the need to allow for a margin between the design pressure and the rupture disk burst pressure in similar applications.

40 CFR 63.693 - Standards: Closed-vent systems and control devices.

Science.gov (United States)

2010-07-01

... concentration level, design average temperature of the condenser exhaust vent stream, and the design average... requirements specified in paragraphs (d) through (h) of this section as applicable to the type and design of... paragraphs (d) through (h) of this section as applicable to the type and design of the control device...

Characterization of condensed phase nitric acid particles formed in the gas phase

Institute of Scientific and Technical Information of China (English)

Long Jia; Yongfu Xu

2011-01-01

The formation of nitric acid hydrates has been observed in a chamber during the dark reaction of NO2 with O3 in the presence of air.The size of condensed phase nitric acid was measured to be 40-100 nm and 20-65 nm at relative humidity (RH) ≤ 5％ and RH = 67％ under our experimental conditions, respectively.The nitric acid particles were collected on the glass fiber membrane and their chemical compositions were analyzed by infrared spectrum.The main components of nitric acid hydrates in particles are HNO3·3H2O and NO3-·xH2O (x≥ 4) at low RH, whereas at high RH HNO3·H2O, HNO3·2H2O, HNO3·3H2O and NO3-·xH2O (x≥ 4) all exist in the condensed phase.At high RH HNO3·xH2O (x ≤ 3) collected on the glass fiber membrane is greatly increased, while NO3-·xH2O (x ≥4) decreased, compared with low RH.To the best of our knowledge, this is the first time to report that condensed phase nitric acid can be generated in the gas phase at room temperature.

Multi-shell model of ion-induced nucleic acid condensation

Energy Technology Data Exchange (ETDEWEB)

Tolokh, Igor S. [Department of Computer Science, Virginia Tech, Blacksburg, Virginia 24061 (United States); Drozdetski, Aleksander V. [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States); Pollack, Lois [School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853-3501 (United States); Baker, Nathan A. [Advanced Computing, Mathematics, and Data Division, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Division of Applied Mathematics, Brown University, Providence, Rhode Island 02912 (United States); Onufriev, Alexey V. [Department of Computer Science, Virginia Tech, Blacksburg, Virginia 24061 (United States); Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States)

2016-04-21

We present a semi-quantitative model of condensation of short nucleic acid (NA) duplexes induced by trivalent cobalt(III) hexammine (CoHex) ions. The model is based on partitioning of bound counterion distribution around single NA duplex into “external” and “internal” ion binding shells distinguished by the proximity to duplex helical axis. In the aggregated phase the shells overlap, which leads to significantly increased attraction of CoHex ions in these overlaps with the neighboring duplexes. The duplex aggregation free energy is decomposed into attractive and repulsive components in such a way that they can be represented by simple analytical expressions with parameters derived from molecular dynamic simulations and numerical solutions of Poisson equation. The attractive term depends on the fractions of bound ions in the overlapping shells and affinity of CoHex to the “external” shell of nearly neutralized duplex. The repulsive components of the free energy are duplex configurational entropy loss upon the aggregation and the electrostatic repulsion of the duplexes that remains after neutralization by bound CoHex ions. The estimates of the aggregation free energy are consistent with the experimental range of NA duplex condensation propensities, including the unusually poor condensation of RNA structures and subtle sequence effects upon DNA condensation. The model predicts that, in contrast to DNA, RNA duplexes may condense into tighter packed aggregates with a higher degree of duplex neutralization. An appreciable CoHex mediated RNA-RNA attraction requires closer inter-duplex separation to engage CoHex ions (bound mostly in the “internal” shell of RNA) into short-range attractive interactions. The model also predicts that longer NA fragments will condense more readily than shorter ones. The ability of this model to explain experimentally observed trends in NA condensation lends support to proposed NA condensation picture based on the multivalent �

Condensation phenomena in BWR-pressure suppression containments under LOCA conditions

International Nuclear Information System (INIS)

Aust, E.; McCauley, E.W.; Niemann, H.R.

1983-01-01

Experimental studies on condensation phenomena in pressure suppression systems (PSS) have shown, that chugging produces the major dynamic loads in a PSS. Time correlation of digital and visual data have produced understanding of the essential physics of this phenomenon: chugging events are characterized by pipe outside and pipe inside condensation. Pipe outside condensation is smooth, sometimes accompanied by vent pipe acoustic frequency. Pipe inside condensation is ring-like and induces a strong pressure pulse with ringdown frequency. The steam ring is caused by the retreating steam front in the pipe exit, which acts as a BORDA-mouth. (orig.) [de

Safe venting of ''red oil'' runaway reactions

International Nuclear Information System (INIS)

Paddleford, D.F.; Fauske, H.K.

1994-01-01

Calorimetry testing of Tri-n-butyl phosphate (TBP) saturated with strong nitric acid was performed to determine the relationship between vent size and pressure buildup in the event of a runaway reaction. These experiments show that runaway can occur in an open system, but that even when runaway is induced in the TBP/HN0 3 system, dangerous pressure buildup will be prevented with practical vent size

GASFLOW simulations for containment venting system of Emsland nuclear power plant

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhanjie; Jordan, Thomas

2015-07-01

In a hypothetical core melt severe accident in nuclear power plants, a large amount of burnable gas, such as hydrogen and carbon monoxide, with certain amount of oxygen is released into the containment. In case of high containment pressure a filtered venting is designed as a mitigation measure. After aerosols and condensable portions of the gas mixture from the containment are purged, the remaining burnable gases flows into a chamber connected to horizontal venting pipes and further to a vertical stack, which is open to free atmosphere at the top. The main goal of the study is to investigate the chemical sensitivity of the burnable and potentially detonable gas mixture in the venting system by means of computational fluid dynamic computer simulations. Based on the calculations with different boundary conditions for different scenarios, it is concluded that the venting system has no risk of flame acceleration and detonation if the power supply of the ventilation fans can be maintained. In case of station blackout, the whole system has no risk of detonation if the scrubber - purging water pool - can get boiling in 10 minutes, owing to the heating effect resulted from the latent heat of the condensable gases into the water pool. It is because the injected steam from the boiling scrubber inerts the mixture of hydrogen, carbon monoxide plus oxygen, effectively and significantly. In this case, a gas mixture only in a very local region in the stack, as small as about 0.16 cubic meter, is in a risk of flame acceleration. It is in principle ignorable owing to the tiny volume and thus only a small amount of hydrogen and carbon monoxide.

Analytical applications of condensed phosphoric acid-I Determination of ferrous and total iron in iron ores after decomposition with condensed phosphoric acid.

Science.gov (United States)

Mizoguchi, T; Ishii, H

1978-06-01

A simple method is described for the determination of ferrous and total iron in iron ores. Iron ores are dissolved by condensed phosphoric acid (CPA) very rapidly without any tedious and time-consuming manipulations such as elimination of silica and filtration. Under the proposed conditions (amount of sample 100 mg, amount of CPA added 10 g, heating temperature 290 degrees , heating time 30 min), magnetite, limonite and hematite are completely dissolved. The iron content can be determined in the presence of condensed phosphoric acid by titration with dichromate solution, if a slight modification is made. The total iron in iron ores, determined by the present method, is in agreement with that found by the JIS method. The ferrous iron in iron ores can be determined by dissolving the samples with CPA in a nitrogen atmosphere and titrating with dichromate solution. Chelatometric titration of iron after solvent extraction with MIBK from solutions prepared by use of CPA is found to be accurate for samples such as pyrite cinder. The ability of CPA to dissolve various materials has been investigated.

Numerical Study of Severe Accidents on Containment Venting Conditions

Energy Technology Data Exchange (ETDEWEB)

Lee, Na Rae; Bang, Young Suk; Park, Tong Kyu; Lee, Doo Yong [FNC Technology Co., Yongin (Korea, Republic of); Choi, Yu Jung; Lee, Sang Won; Kim, Hyeong Taek [KHNP-CRI, Daejeon (Korea, Republic of)

2014-10-15

Under severe accident, the containment integrity can be challenged due to over-pressurization by steam and non-condensable gas generation. According to Seismic Probabilistic Safety Assessment (PSA) result, the late containment failure by over-pressurization has been identified as the most probable containment failure mode. In addition, the analyses of Fukushima nuclear power plant accident reveal the necessity of the proper containment depressurization to prevent the large release of the radionuclide to environment. Containment venting has been considered as an effective approach to maintain the containment integrity from over-pressurization. Basic idea of containment venting is to relieve the pressure inside of the containment by establishing a flow path to the external environment. To ensure the containment integrity under over-pressure conditions, it is crucial to conduct the containment vent in a timely manner with a sufficient discharge flow rate. It is also important to optimize the vent line size to prevent additional risk of leakage and to install at the site with limited space availability. The purpose of this study is to identify the effective venting conditions for preventing the containment over-pressurization and investigate the vent flow characteristics to minimize the consequence of the containment ventilation.. In order that, thermodynamic behavior of the containment and the discharged flow depending on different vent strategies are analyzed and compared. The representative accident scenarios are identified by reviewing the Level 2 PSA result and the sensitivity analyses with varying conditions (i.e. vent line size and vent initiation pressure) are conducted. MAAP5 model for the OPR1000 Korea nuclear power plant has been used for severe accident simulations. Containment venting can be an effective strategy to prevent the significant failure of the containment due to over-pressurization. However, it should be carefully conducted because the vented

Numerical Study of Severe Accidents on Containment Venting Conditions

International Nuclear Information System (INIS)

Lee, Na Rae; Bang, Young Suk; Park, Tong Kyu; Lee, Doo Yong; Choi, Yu Jung; Lee, Sang Won; Kim, Hyeong Taek

2014-01-01

Under severe accident, the containment integrity can be challenged due to over-pressurization by steam and non-condensable gas generation. According to Seismic Probabilistic Safety Assessment (PSA) result, the late containment failure by over-pressurization has been identified as the most probable containment failure mode. In addition, the analyses of Fukushima nuclear power plant accident reveal the necessity of the proper containment depressurization to prevent the large release of the radionuclide to environment. Containment venting has been considered as an effective approach to maintain the containment integrity from over-pressurization. Basic idea of containment venting is to relieve the pressure inside of the containment by establishing a flow path to the external environment. To ensure the containment integrity under over-pressure conditions, it is crucial to conduct the containment vent in a timely manner with a sufficient discharge flow rate. It is also important to optimize the vent line size to prevent additional risk of leakage and to install at the site with limited space availability. The purpose of this study is to identify the effective venting conditions for preventing the containment over-pressurization and investigate the vent flow characteristics to minimize the consequence of the containment ventilation.. In order that, thermodynamic behavior of the containment and the discharged flow depending on different vent strategies are analyzed and compared. The representative accident scenarios are identified by reviewing the Level 2 PSA result and the sensitivity analyses with varying conditions (i.e. vent line size and vent initiation pressure) are conducted. MAAP5 model for the OPR1000 Korea nuclear power plant has been used for severe accident simulations. Containment venting can be an effective strategy to prevent the significant failure of the containment due to over-pressurization. However, it should be carefully conducted because the vented

Modeling of zero gravity venting: Studies of two-phase heat transfer under reduced gravity

Science.gov (United States)

Merte, H., Jr.

1986-01-01

The objective is to predict the pressure response of a saturated liquid-vapor system when undergoing a venting or depressurization process in zero gravity at low vent rates. An experimental investigation of the venting of cylindrical containers partially filled with initially saturated liquids was previously conducted under zero-gravity conditions and compared with an analytical model which incorporated the effect of interfacial mass transfer on the ullage pressure response during venting. A new model is presented to improve the estimation of the interfacial mass transfer. Duhammel's superposition integral is incorporated to approximate the transient temperature response of the interface, treating the liquid as a semi-infinite solid with conduction heat transfer. Account is also taken of the condensation taking place within the bulk of a saturated vapor as isentropic expansion takes place. Computational results are presented for the venting of R-11 from a given vessel and initial state for five different venting rates over a period of three seconds, and compared to prior NASA experiments. An improvement in the prediction of the final pressure takes place, but is still considerably below the measurements.

14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

Science.gov (United States)

2010-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.975 Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

Science.gov (United States)

2010-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System § 29.975 Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel tank vents and carburetor vapor vents...

Design experiments for a vented containment

International Nuclear Information System (INIS)

Hesboel, R.

1985-01-01

A filtered containment venting system, operable late in 1985, is currently under installation at the Barsebaeck twin nuclear power station in Sweden. The filter unit, which communicates with the containments of both reactor units, but is separated from them by rupture discs, consists of a concrete bed, 40 m high and 20 m in diameter, filled with gravel of grain size 25-35 mm. The performance of the gravel bed under such accident conditions which might lead to an activation of this safeguard system has been the subject for investigation within the FILTRA project. These investigations have shown that the gravel bed acts as: an expansion volume for decreasing gas pressure and increasing gas residence time, a heat sink for condensing steam, an excellent filter medium for removing aerosols and elemental iodine, and a sump volume for collecting radioactive condensate. The results from iodine retention studies in gravel beds are mainly considered

Emergency condensator for BWR type reactor

International Nuclear Information System (INIS)

Ubakai, Yoichi; Narumi, Yuichi; Sakata, Yuji.

1992-01-01

An emergency condensator is constituted with heat transfer pipes, a steam chamber, an upper pipe plate, a lower pipe plate and a condensate chamber. The upper pipe plate is secured by supports, and a steam pipe is connected to the upper pipe plate. A condensate pipeline and a incondensible gas vent pipe are disposed to the condensate chamber. Taking thermal expansion of the steam pipes and thermal expansion of the heat transfer pipes into consideration, the heat transfer pipe is made as an L-shaped pipe having a vertical portion and a horizontal portion so as to absorb each of the thermal expansion smoothly. The L-shaped heat transfer pipes are constituted as a bundle of pipes having the end portions thereof secured to the upper pipe plate and the lower pipe plate. The emergency condensator is disposed in a emergency condensator pool chamber. Cooling water in contact with the outer side of the L-shaped heat transfer pipes is the pool water in the pool chamber, and the condensator chamber is disposed in concrete walls of the pool chamber. With such a constitution, stress due to thermal expansion of the heat transfer pipes is mitigated, and heat transfer performance, earth quake resistance and maintenancability are improved. (I.N.)

14 CFR 23.975 - Fuel tank vents and carburetor vapor vents.

Science.gov (United States)

2010-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Fuel System § 23.975 Fuel tank vents and carburetor vapor vents. (a) Each fuel tank must be vented... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel tank vents and carburetor vapor vents...

Condensation of the isoprenoid and amino precursors in the biosynthesis of domoic acid.

Science.gov (United States)

Savage, Thomas J; Smith, G Jason; Clark, Amy T; Saucedo, Portia N

2012-01-01

Understanding how environmental signals regulate production of domoic acid in blooms of Pseudo-nitzschia spp. at a molecular level requires description of the biochemical pathway to this kainoid neurotoxin. Precursor feeding studies have suggested domoic acid arises from the condensation of the C(10) isoprenoid geranyl diphosphate with glutamate, but the specific reactions leading to domoic acid from these precursors remain undescribed. Here, we develop a method to derivatize domoic acid with propyl chloroformate that enables gas chromatography-mass spectrometry (GC-MS) analysis to measure incorporation of stable isotopes into domoic acid generated in cultures incubated with isotopically-labeled substrates. We apply this method to demonstrate that both (2)H from [1-(2)H(2)]geraniol are incorporated into domoic acid, suggesting that the condensation of geranyl diphosphate with an amino group occurs by nucleophilic substitution of the diphosphate rather than by oxidation of geraniol to the aldehyde before reaction with an amino group to form an imine. Ultimately, these and similar studies will facilitate the identification of DA biosynthetic enzymes and genes which will enable the study of how environmental factors regulate DA biosynthesis at the molecular level. Copyright © 2011 Elsevier Ltd. All rights reserved.

Filtered atmospheric venting of light water reactor containments

International Nuclear Information System (INIS)

Hedgran, A.; Ahlstroem, P.E.; Nilsson, L.; Persson, Aa.

1982-11-01

The aim of filtered venting is to improve the function of the reactor containment in connection with very severe accidents. By equipping the containment with a safety valve for pressure relief and allowing the released gases to pass through an effective filter, it should be possible to achieve a considerable protective effect. The work has involved detailed studies of the core meltdown sequence, how the molten core material runs out of the reactor vessel, what effect it has on concrete and other structures and how final cooling of the molten core material takes place. On the basis of previous Swedish studies, the project has chosen to study a filter concept that consists of a gravel bed of large volume. This filter plant shall not only retain the radioactive particles that escape from the containment through the vent line, but shall also condense the accompanying steam. After the government decided in 1981 that Barsebaeck was to be equipped with filtered venting and issued specifications regarding its performance, the project aimed at obtaining results that could be used to design and verify a plant for filtered venting at the Barsebaeck nuclear power station. As far as the other Swedish nuclear power plants at Oskarshamn, Ringhals and Forsmark are concerned, the results are only applicable to a limited extent. Additional studies are required for these nuclear power plants before the value of filtered venting can be assessed. Based on the results of experiments and analyses, the project has made a safety analysis with Barsebaeck as a reference plant in order to study how the introduction of filtered venting affects the safety level at a station. In summary, the venting function appears to entail a not insignificant reduction of risks for boiling water reactors of the Barsebaeck type. For a number of types of such very severe core accident cases, the filter design studied ensures a substantial reduction of the releases. However it has not been possible within the

Corrosion mechanism of Z3 CN18.10 stainless steel in the presence of nitric acid condensates

International Nuclear Information System (INIS)

Balbaud, Fanny

1998-01-01

In installations handling concentrated boiling nitric acid, a severe intergranular corrosion can sometimes occur in condensation zones constituted of non-sensitized Z3 CN 18.10 stainless steel. Corrosion tests in reactors and in a specific loop, CIRCE, allowed to specify the conditions of occurrence of this type of corrosion and showed the similitude with the corrosion in non-renewed liquid nitric acid: the specific parameters linked to the condensate phase are the high ratio metallic surface area to volume of condensate and the low renewing rate which induce a concentration of oxidation products of the metal and of reduction products of nitric acid. The initiation of the intergranular corrosion is attributed to the increase in the reduction rate of nitric acid by an autocatalytic mechanism which was demonstrated by electrochemical measurements on platinum and on stainless steel. The reduction mechanism involves a charge transfer step where nitrous acid, the electro-active species, is reduced into nitrogen monoxide and a chemical regeneration reaction of nitrous acid. The thermodynamic study led to a representation of the chemical and electrochemical properties of nitric acid. This study allowed also to determine the Gibbs free energy of formation of nitrous acid in solution in concentrated nitric acid at 100 deg. C. The diagram, constructed in coordinates log(P O 2 ) / [-log(P HNO 3 )] or E eXperimental / [-log(P HNO 3 )], shows that the final reduction product of nitric acid depends on the concentration of nitric acid: at 100 deg. C, NO is obtained for concentrations lower than 8 mol.L -1 and NO 2 is obtained for higher concentrations. All these results allowed to propose a corrosion mechanism of Z3 CN 18.10 stainless steel in the presence of nitric acid condensates. [fr

Development of a submerged gravel scrubber for containment venting applications: summary

International Nuclear Information System (INIS)

Hilliard, R.K.; McCormack, J.D.; Postma, A.K.

1981-01-01

Although hypothetical core disruptive accidents (HCDAs) are not design basis accidents for breeder reactor plants, extensive assessments of HCDA consequences have been made and design features for providing margins beyond the design base have been considered for future fast reactor plants. One feature proposed for increasing the safety margin is a containment vent and/or purge system which would mitigate the challenge to containment integrity resulting from excessive temperature and pressure or excessive hydrogen. A cleanup system would be required for removal of vented aerosols and condensible vapors to mitigate radiological consequences to the environment. A study is in progress at HEDL to select and develop a suitable air cleaning system for use in potential breeder reactor containment venting applications. A concept was conceived whereby the passiveness and high loading capacity of a water pool scrubber was combined with the high efficiency of a sand and gravel bed. It was termed a Submerged Gravel Scrubber (SGS). A schematic drawing of the concept is shown. The SGS consists of a bed of gravel (or other packing) submerged in a pool of water

Collecting and recirculating condensate in a nuclear reactor containment

International Nuclear Information System (INIS)

Schultz, T.L.

1993-01-01

An arrangement passively cools a nuclear reactor in the event of an emergency, condensing and recycling vaporized cooling water. The reactor is surrounded by a containment structure and has a storage tank for cooling liquid, such as water, vented to the containment structure by a port. The storage tank preferably is located inside the containment structure and is thermally coupleable to the reactor, e.g. by a heat exchanger, such that water in the storage tank is boiled off to carry away heat energy. The water is released as a vapor (steam) and condenses on the cooler interior surfaces of the containment structure. The condensed water flows downwardly due to gravity and is collected and routed back to the storage tank. One or more gutters are disposed along the interior wall of the containment structure for collecting the condensate from the wall. Piping is provided for communicating the condensate from the gutters to the storage tank. 3 figures

Collecting and recirculating condensate in a nuclear reactor containment

Science.gov (United States)

Schultz, Terry L.

1993-01-01

An arrangement passively cools a nuclear reactor in the event of an emergency, condensing and recycling vaporized cooling water. The reactor is surrounded by a containment structure and has a storage tank for cooling liquid, such as water, vented to the containment structure by a port. The storage tank preferably is located inside the containment structure and is thermally coupleable to the reactor, e.g. by a heat exchanger, such that water in the storage tank is boiled off to carry away heat energy. The water is released as a vapor (steam) and condenses on the cooler interior surfaces of the containment structure. The condensed water flows downwardly due to gravity and is collected and routed back to the storage tank. One or more gutters are disposed along the interior wall of the containment structure for collecting the condensate from the wall. Piping is provided for communicating the condensate from the gutters to the storage tank.

Condensed tannins affect bacterial and fungal microbiomes and mycotoxin production during ensiling and upon aerobic exposure.

Science.gov (United States)

Peng, Kai; Jin, Long; Niu, Yan D; Huang, Qianqian; McAllister, Tim A; Yang, Hee Eun; Denise, Hubert; Xu, Zhongjun; Acharya, Surya; Wang, Shunxi; Wang, Yuxi

2017-12-15

Purple prairie clover (PPC; Dalea purpurea Vent.) containing 84.5 g/kg DM of condensed tannin (CT) was ensiled without (Control) or with polyethylene glycol (PEG) for 76 days, followed by 14 days of aerobic exposure. Changes in fermentation characteristics were determined and bacterial and fungal communities were assessed using metagenomic sequencing. Addition of PEG that deactivated CT at ensiling increased ( P aerobic exposure. The PEG treated silage exhibited higher ( P aerobic exposure, whereas it increased ( P aerobic exposure. Addition of PEG at ensiling increased ( P aerobic exposure, whereas the Bacillus were the dominate bacteria after aerobic exposure. In conclusion, CT decreased protein degradation and improved aerobic stability of silage. These desirable outcomes likely reflect the ability of PPC CT to inhibit those microorganisms involved in lowering silage quality and in the production of mycotoxins. IMPORTANCE The present study reports the effects of condensed tannins on the complex microbial communities involved in ensiling and aerobic exposure of purple prairie clover. This study documents the ability of condensed tannins to lower mycotoxin production and associated microbiome. Taxonomic bacterial community profiles were dominated by the Lactobacillales after fermentation, with a notable increase in Bacillus as a result of aerobic exposure. It is interesting to observe that condensed tannins decreased bacterial diversity during both ensiling and aerobic exposure but increased fungal diversity during aerobic exposure only. The present study indicates that the effects of condensed tannins on microbial communities lead to a reduced lactic acid and total volatile fatty acids production, proteolysis and mycotoxin concentration in the terminal silage and an improved aerobic stability. Condensed tannins could be used as additive to control unfavorable microbial development and maybe enhanced feed safety. © Crown copyright 2017.

Evaluation of RELAP5 MOD 3.1.1 code with GIRAFFE Test Facility: Phase 1, Step 2 nitrogen venting tests

International Nuclear Information System (INIS)

Boyer, B.D.; Slovik, G.C.; Rohatgl, U.S.

1995-01-01

The Simplified Boiling Water Reactor (SBWR) proposed by General Electric (GE) is an advanced light water reactor (ALWR) design that utilizes passive safety systems. The PCCS is a series of heat exchangers submerged in water and open to the containment. Since the containment is inerted with nitrogen during normal operation, the PCCS must condense the steam in the presence of noncondensable gases during an accident. To model the transient behavior of the SBWR with a system code, the code should properly simulate the expected phenomena. To validate the applicability of RELAP5 MOD 3.1.1, the data from three Phase 1, Step 2 nitrogen venting tests at Toshiba's Gravity-Driven Integral Full-Height Test for Passive Heat Removal facility and RELAP5 calculations of these tests were compared. The comparison of the GIRAFFE data against the results from the RELAP5 calculations showed that it can predict condensation and gas purging phenomena occurring in the long-term decay heat rejection phase. In this phase of the transient, condensation in the PCCS is the only means to reject heat from the SBWR containment. In the two tests where the nitrogen purge vent line was at its deepest submergence in the Suppression Pool (SIP), the RELAP5 results mirrored the behavior of the containment pressures and of the water levels in the Horizontal Vent (HV) and the nitrogen purge line tube of the GIRAFFE data. However, in the test with the shallowest purge line submergence, there was appreciable direct contact condensation on the pool surface of the HV despite modeling efforts to deter these phenomena. This surface condensation, unobserved in the GIRAFFE tests, was a major cause of RELAP5 predicting early containment depressurization and the subsequent early rise in HV and nitrogen purge line water levels. The present RELAP5 MOD3.1.1 interfacial heat and mass transfer model does not properly degrade direct contact steam condensation in the presence of noncondensable gases sitting on a pool

Impact of vent pipe diameter on characteristics of waste degradation in semi-aerobic bioreactor landfill.

Science.gov (United States)

Jiang, Guobin; Liu, Dan; Chen, Weiming; Ye, Zhicheng; Liu, Hong; Li, Qibin

2017-10-01

The evolution mechanism of a vent pipe diameter on a waste-stabilization process in semi-aerobic bioreactor landfills was analyzed from the organic-matter concentration, biodegradability, spectral characteristics of dissolved organic matter, correlations and principal-component analysis. Waste samples were collected at different distances from the vent pipe and from different landfill layers in semi-aerobic bioreactor landfills with different vent pipe diameters. An increase in vent pipe diameter favored waste degradation. Waste degradation in landfills can be promoted slightly when the vent pipe diameter increases from 25 to 50 mm. It could be promoted significantly when the vent pipe diameter was increased to 75 mm. The vent pipe diameter is important in waste degradation in the middle layer of landfills. The dissolved organic matter in the waste is composed mainly of long-wave humus (humin), short-wave humus (fulvic acid) and tryptophan. The humification levels of the waste that was located at the center of vent pipes with 25-, 50- and 75-mm diameters were 2.2682, 4.0520 and 7.6419 Raman units, respectively. The appropriate vent pipe diameter for semi-aerobic bioreactor landfills with an 800-mm diameter was 75 mm. The effect of different vent pipe diameters on the degree of waste stabilization is reflected by two main components. Component 1 is related mainly to the content of fulvic acid, biologically degradable material and organic matter. Component 2 is related mainly to the content of tryptophan and humin from the higher vascular plants.

A two staged condensation of vapors of an isobutane tower in installations for sulfuric acid alkylation

Energy Technology Data Exchange (ETDEWEB)

Smirnov, N.P.; Feyzkhanov, R.I.; Idrisov, A.D.; Navalikhin, P.G.; Sakharov, V.D.

1983-01-01

In order to increase the concentration of isobutane to greater than 72 to 76 percent in an installation for sulfuric acid alkylation, a system of two staged condensation of vapors from an isobutane tower is placed into operation. The first stage condenses the heavier part of the upper distillate of the tower, which is achieved through somewhat of an increase in the condensate temperature. The product which is condensed in the first stage is completely returned to the tower as a live irrigation. The vapors of the isobutane fraction which did not condense in the first stage are sent to two newly installed condensers, from which the product after condensation passes through intermediate tanks to further depropanization. The two staged condensation of vapors of the isobutane tower reduces the content of the inert diluents, the propane and n-butane in the upper distillate of the isobutane tower and creates more favorable conditions for the operation of the isobutane and propane tower.

Biaxial vent extruder

International Nuclear Information System (INIS)

Idemoto, A.; Maki, Y.; Oda, N.

1981-01-01

A biaxial vent extruder is described for processing of slurry-like waste fluids or radioactive waste fluids which have a hopper cylinger, a solidifying substance port and a solidified substance port. A plurality of vent cylinders each having a vent port are provided with a plunger type scraper. An extruding cylinder having a single opening for a main screw is connected to the assembled vent cylinders. The main screw extends to the upstream end of the extruding cylinder and a sub-screw extends to the extruding cylinder. The screws each having a full flight engaging the other and a set of rings are mounted on the screws near the respective vent port inlets. The screws are rotated in different directions and inwardly with respect to the vent ports. Rotors may be mounted on the screws to break down solid particles

Synthesis of condensed double rubidium manganese phosphates in melts of polyphosphoric acids

International Nuclear Information System (INIS)

Guzeeva, L.S.; Tananaev, I.V.

1988-01-01

The aim of this work was to study the character of the reaction of MnO 2 and Rb 2 O with melts of polyphosphoric acids, and to establish the composition and the conditions of formation of the condensed double rubidium manganese phosphates. In the reaction of manganese and rubidium oxides with melts of polyphosphoric acids at 140-350 degree C, three types of trivalent manganese and rubidium condensed double phosphates are formed - diphosphates RbMn(H 2 P 2 O 7 ) and Rb 2 MnH 3 (P 2 O 7 ) 2 , triphosphate RbMnHP 3 O 10 and diphosphate RbMnP 2 O 7 - in addition to a double cyclotriphosphate of divalent manganese with rubidium RbMnP 3 O 9 . The thermal transformations of the compound isolated were studied. It was shown that rubidium manganese cyclotriphosphate can be obtained by the thermal decomposition of the diphosphate RbMn(H 2 P 2 O 7 ) 2

Modified performance test of vented lead acid batteries for stationary applications

International Nuclear Information System (INIS)

Uhlir, K.W.; Fletcher, R.J.

1995-01-01

The concept of a modified performance test for vented lead acid batteries in stationary applications has been developed by the IEEE Battery Working Group. The modified performance test is defined as a test in the ''as found'' condition of the battery capacity and its ability to provide a high rate, short duration load (usually the highest rate of the duty cycle) that will confirm the battery's ability to meet the critical period of the load duty cycle, in addition to determining its percentage of rated capacity. This paper will begin by reviewing performance and service test requirements and concerns associated with both types of tests. The paper will then discuss the rationale for developing a modified performance test along with the benefits that can be derived from performing a modified performance test in lieu of a capacity test and/or a service test. The paper will conclude with an example on how to apply a modified performance test and test acceptance criteria

Vapor condensation device

International Nuclear Information System (INIS)

Sakurai, Manabu; Hirayama, Fumio; Kurosawa, Setsumi; Yoshikawa, Jun; Hosaka, Seiichi.

1992-01-01

The present invention enables to separate and remove 14 C as CO 3 - ions without condensation in a vapor condensation can of a nuclear facility. That is, the vapor condensation device of the nuclear facility comprises (1) a spray pipe for spraying an acidic aqueous solution to the evaporation surface of an evaporation section, (2) a spray pump for sending the acidic aqueous solution to the spray pipe, (3) a tank for storing the acidic aqueous solution, (4) a pH sensor for detecting pH of the evaporation section, (5) a pH control section for controlling the spray pump, depending on the result of the detection of the pH sensor. With such a constitution, the pH of liquid wastes on the vaporization surface is controlled to 7 by spraying an aqueous solution of dilute sulfuric acid to the evaporation surface, thereby enabling to increase the transfer rate of 14 C to condensates to 60 to 70%. If 14 C is separated and removed as a CO 2 gas from the evaporation surface, the pH of the liquid wastes returns to the alkaline range of 9 to 10 and the liquid wastes are returned to a heating section. The amount of spraying the aqueous solution of dilute sulfuric acid can be controlled till the pH is reduced to 5. (I.S.)

ITER vent filter conceptual study. Final report ITER Task S71 TD 70 (NID-9e) EU Task SEA 3-4

Energy Technology Data Exchange (ETDEWEB)

Blomquist, R; Johansson, Kjell; Natalizio, A; Nilsson, Lars; Shen, K; Sjoeberg, A

1995-02-01

The aim of this study is to investigate vent filter technologies that could be applied to ITER in accidental situations and to discuss how effective they could be in reducing accidental releases of gases, vapors and aerosols to the atmosphere. The study`s main contents are: A description of vent filter technologies as they are used for fission reactors; A review of appropriate tritium removal technologies. The vent filter part deals mainly with aerosol removal. The tritium part includes removal of both elemental and oxidized tritium from the vent flow. An important conclusion is that current fission reactor vent filter systems do not remove elemental tritium from the vent stream. A third part of the study is scoping thermal-hydraulic and aerosol transport analyses in order to find realistic vent flow rates and aerosol transport characteristics. Theses analyses, which are based on ITER design data assumed at the time of analysis, have been performed by means of the codes RELAP5 and CONTAIN. Release estimates are also included. Suggestions and recommendations are given regarding how to design a reliable vent filter system. Suggested vent systems include: Vent ducts from vacuum vessel and heat exchanger departments, a water pool for condensation of steam, and equipment for removal of aerosols, elemental tritium and oxidized tritium. 42 refs, 6 tabs, 34 figs.

ITER vent filter conceptual study. Final report ITER Task S71 TD 70 (NID-9e) EU Task SEA 3-4

International Nuclear Information System (INIS)

Blomquist, R.; Johansson, Kjell; Natalizio, A.; Nilsson, Lars; Shen, K.; Sjoeberg, A.

1995-02-01

The aim of this study is to investigate vent filter technologies that could be applied to ITER in accidental situations and to discuss how effective they could be in reducing accidental releases of gases, vapors and aerosols to the atmosphere. The study's main contents are: A description of vent filter technologies as they are used for fission reactors; A review of appropriate tritium removal technologies. The vent filter part deals mainly with aerosol removal. The tritium part includes removal of both elemental and oxidized tritium from the vent flow. An important conclusion is that current fission reactor vent filter systems do not remove elemental tritium from the vent stream. A third part of the study is scoping thermal-hydraulic and aerosol transport analyses in order to find realistic vent flow rates and aerosol transport characteristics. Theses analyses, which are based on ITER design data assumed at the time of analysis, have been performed by means of the codes RELAP5 and CONTAIN. Release estimates are also included. Suggestions and recommendations are given regarding how to design a reliable vent filter system. Suggested vent systems include: Vent ducts from vacuum vessel and heat exchanger departments, a water pool for condensation of steam, and equipment for removal of aerosols, elemental tritium and oxidized tritium. 42 refs, 6 tabs, 34 figs

Boehmite-An Efficient and Recyclable Acid-Base Bifunctional Catalyst for Aldol Condensation Reaction.

Science.gov (United States)

Reshma, P C Rajan; Vikneshvaran, Sekar; Velmathi, Sivan

2018-06-01

In this work boehmite was used as an acid-base bifunctional catalyst for aldol condensation reactions of aromatic aldehydes and ketones. The catalyst was prepared by simple sol-gel method using Al(NO3)3·9H2O and NH4OH as precursors. The catalyst has been characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), UV-visible spectroscopy (DRS), BET surface area analyses. Boehmite is successfully applied as catalyst for the condensation reaction between 4-nitrobenzaldehyde and acetone as a model substrate giving α, β-unsaturated ketones without any side product. The scope of the reaction is extended for various substituted aldehydes. A probable mechanism has been suggested to explain the cooperative behavior of the acidic and basic sites. The catalyst is environmentally friendly and easily recovered from the reaction mixture. Also the catalyst is reusable up to 3 catalytic cycles.

A model for the calculation of vent clearing transients in pressure suppression systems

International Nuclear Information System (INIS)

Brosche, D.

1975-01-01

For the layout of a pressure suppression system of a light water cooled reactor (boiling water reactor) it is important to know the time dependent behavior of the vent clearing transient after a loss-of-coolant accident for two main reasons: time of the end of the vent clearing transient influences strongly the pressure and temperature maxima in the drywell and wetwell. Time-dependent behavior of the vent clearing transient influences pressure loads in the condensation pool of the wetwell and therefore pressure induced stresses to the structure. The time-dependent behavior of the water masses in the vent pipes and wetwell are described by the basic equations for a nonstationary incompressible friction flow: momentum equation, continuity equation and a correlation for the variation of the state of the gas volume in the wetwell above the water level. After many algebraic operations and integrations along the flow path, a single ordinary nonlinear differential equation for the variations of the water levels in the vent pipes and wetwell is obtained. Therefore the time-dependent velocities and accelerations of the water levels and the moment of the end clearing transient are known. The time-dependent pressure behavior in the drywell, geometrical conditions, initial submergence depth of the vent pipes and different friction and pressure loss factors are presented. The theoretical model has been tested at corresponding experiments performed at a full scale 1/48 segment of the Humboldt Bay pressure suppression containment in the USA and at the pressure suppression containment at the Marviken nuclear power station in Sweden. All these comparisons have shown good agreement between theory and experiment

Condenser Design for the Proposed AM600 NPP

Energy Technology Data Exchange (ETDEWEB)

Rahman, Md. Mizanur; Abdallah, Khaled Atya Ahmed; Field, Robert M. [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

2015-10-15

The design goals are to make the condenser more robust and compact with a reduced component count. The AM600 condenser design also has new features as described below. Considering that the minimum heat sink temperature for potentially emergent nuclear countries is on the order of 21.deg. C or higher, a turbine design with a single low pressure rotor can be considered without sacrificing thermal efficiency. The condenser back pressure range for the considered markets is on the order of 2 to 3 in-HgA. With these boundary conditions, the AM600 condenser duty can be met with a single pressure zone design with a total of eight (8) titanium tube bundles (four (4) per pass) divided into four isolable sections. Due to the compact design (i.e., accepting exhaust from only one low pressure cylinder), both axial ends of the condenser are unobstructed and available for attachment of extended flash chambers, diverting inflows away from the tube bundles. The single shell design of this condenser then allows for an innovative design feature, namely the extended flash chambers. This permits the routing of dump, drain, vent, and bypass flows directly to these chambers, bypassing the condenser shell. Within the condenser shell, this design eliminates impingement plates, impingement boxes, and spargers. Failure of these components represents an ongoing source of condenser tube damage in operating nuclear units, requiring significant resources for outage inspections. The extended flash chamber approach also has a number of other advantages as delineated above.

Vision in hydrothermal vent shrimp.

OpenAIRE

Chamberlain, S C

2000-01-01

Bresiliid shrimp from hydrothermal vents on the Mid-Atlantic Ridge have non-imaging eyes adapted for photodetection in light environments of very low intensity. Comparison of retinal structures between both vent shrimp and surface-dwelling shrimp with imaging eyes, and between juvenile and adult vent shrimp, suggests that vent shrimp have evolved from ancestors that lived in a light environment with bright cyclic lighting. Whether the vent shrimp live in swarms and have large dorsal eyes or l...

Numerical simulation of condensation phase change flow in an inclined tube with bend

Energy Technology Data Exchange (ETDEWEB)

Jo, Jong Chull; Shin, Byung Soo; Do, Kyu Sik [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Lee, Yong Kap [Anflux Co., Seoul (Korea, Republic of)

2012-10-15

The new PWR design named APR+ incorporates a passive auxiliary feedwater system (PAFS) as shown in Fig.1. The PAFS consists of two separate divisions. Each division is equipped with one passive condensation heat exchanger (PCHX), isolation or drain or vent valves, check valves, instrumentation and control, and pipes. It is aligned to feed condensed water to its corresponding steam generator (SG). During the PAFS normal operation, steam being produced in the SG secondary side by the residual heat moves up due to buoyancy force and then flows into the PCHX where steam is condensed on the inner surface of the tubes of which the outer surfaces are cooled by the water stored in the passive condensation cooling tank (PCCT). The condensate is passively fed into the SG economizer by gravity. Because the thermal hydraulic characteristics in the PCHT determine the condensation mass rate and the possibility of system instability and water hammer, it is important to understand the condensation phase change flow in the PCHT. This paper presents a numerical simulation of the condensation phase change flow in the PCHX adopted for the APR+ PAFS.

Explosive Volcanic Eruptions from Linear Vents on Earth, Venus and Mars: Comparisons with Circular Vent Eruptions

Science.gov (United States)

Glaze, Lori S.; Baloga, Stephen M.; Wimert, Jesse

2010-01-01

Conditions required to support buoyant convective plumes are investigated for explosive volcanic eruptions from circular and linear vents on Earth, Venus, and Mars. Vent geometry (linear versus circular) plays a significant role in the ability of an explosive eruption to sustain a buoyant plume. On Earth, linear and circular vent eruptions are both capable of driving buoyant plumes to equivalent maximum rise heights, however, linear vent plumes are more sensitive to vent size. For analogous mass eruption rates, linear vent plumes surpass circular vent plumes in entrainment efficiency approximately when L(sub o) > 3r(sub o) owing to the larger entrainment area relative to the control volume. Relative to circular vents, linear vents on Venus favor column collapse and the formation of pyroclastic flows because the range of conditions required to establish and sustain buoyancy is narrow. When buoyancy can be sustained, however, maximum plume heights exceed those from circular vents. For current atmospheric conditions on Mars, linear vent eruptions are capable of injecting volcanic material slightly higher than analogous circular vent eruptions. However, both geometries are more likely to produce pyroclastic fountains, as opposed to convective plumes, owing to the low density atmosphere. Due to the atmospheric density profile and water content on Earth, explosive eruptions enjoy favorable conditions for producing sustained buoyant columns, while pyroclastic flows would be relatively more prevalent on Venus and Mars. These results have implications for the injection and dispersal of particulates into the planetary atmosphere and the ability to interpret the geologic record of planetary volcanism.

Understanding vented gas explosions

Energy Technology Data Exchange (ETDEWEB)

Lautkaski, R. [VTT Energy, Espoo (Finland). Energy Systems

1997-12-31

The report is an introduction to vented gas explosions for nonspecialists, particularly designers of plants for flammable gases and liquids. The phenomena leading to pressure generation in vented gas explosions in empty and congested rooms are reviewed. The four peak model of vented gas explosions is presented with simple methods to predict the values of the individual peaks. Experimental data on the external explosion of dust and gas explosions is discussed. The empirical equation relating the internal and external peak pressures in vented dust explosions is shown to be valid for gas explosion tests in 30 m{sup 3} and 550 m{sup 3} chambers. However, the difficulty of predicting the internal peak pressure in large chambers remains. Methods of explosion relief panel design and principles of vent and equipment layout to reduce explosion overpressures are reviewed. (orig.) 65 refs.

Understanding vented gas explosions

Energy Technology Data Exchange (ETDEWEB)

Lautkaski, R [VTT Energy, Espoo (Finland). Energy Systems

1998-12-31

The report is an introduction to vented gas explosions for nonspecialists, particularly designers of plants for flammable gases and liquids. The phenomena leading to pressure generation in vented gas explosions in empty and congested rooms are reviewed. The four peak model of vented gas explosions is presented with simple methods to predict the values of the individual peaks. Experimental data on the external explosion of dust and gas explosions is discussed. The empirical equation relating the internal and external peak pressures in vented dust explosions is shown to be valid for gas explosion tests in 30 m{sup 3} and 550 m{sup 3} chambers. However, the difficulty of predicting the internal peak pressure in large chambers remains. Methods of explosion relief panel design and principles of vent and equipment layout to reduce explosion overpressures are reviewed. (orig.) 65 refs.

Lipid Biomarkers and Molecular Carbon Isotopes for Elucidating Carbon Cycling Pathways in Hydrothermal Vents

Science.gov (United States)

Zhang, C. L.; Dai, J.; Campbell, B.; Cary, C.; Sun, M.

2003-12-01

Increasing molecular evidence suggests that hydrothermal vents in mid-ocean ridges harbor large populations of free-living bacteria, particularly the epsilon Proteobacteria. However, pathways for carbon metabolism by these bacteria are poorly known. We are addressing this question by analyzing the lipid biomarkers and their isotope signatures in environments where the epsilon Proteobacteria are likely predominant. Solid materials were collected from hydrothermal vents in the East Pacific Rise and at the Guaymas Basin in the Gulf of California. Fatty acids extracted from these samples are dominated by 16:0 (27-41%), 18:0 (16-48%), 18:1 (11-42%), 16:1 (7-12%), and 14:0 (5-28%). In addition, 15:0 and anteiso-15:0 are significantly present (2-3%) in samples from the Guaymas Basin. The isotopic compositions of these fatty acids range from -15.0\\permil to -33.1\\permil with the most positive values occurring only in monounsaturated fatty acids (16:1 and 18:1). We are currently unable to assign these biomarkers to any of the epsilon Proteobacteria because biomarkers are poorly known for these organisms isolated from the vents. However, no polyunsaturated fatty acids were detected in these samples, which are consistent with the absence of vent animals at the sampling sites. Signature biomarkers of 20:1 and cy21:0, which are characteristic of the thermophilic chemolithoautotrophs such as Aquificales, are also absent in these samples. These results imply that the deeply branched Aquificales species do not constitute the major microbial community in these vent environments. The large range of molecular isotopic compositions suggests that these lipids are synthesized from various carbon sources with different isotopic compositions or through different biosynthetic pathways, or both. We are currently measuring the isotopic compositions of the total organic carbon in the bulk samples and will determine the fractionations between lipid biomarkers and the total organic carbon

Microscopic bubble behaviour in suppression pool during wetwell venting

Science.gov (United States)

Zablackaite, G.; Nagasaka, H.; Kikura, H.

2017-10-01

During a severe accident PCV failure should be avoided and fission products inside PCV should be confined as much as possible. In order to minimize FPs release, Wetwell venting is conducted by releasing steam-non-condensable gas mixture carrying FPs from the Drywell to Suppression Pool. Steam is condensed by subcooled water in the pool, and most of FPs are retained into water. The removal of FP in the water pool is referred to as “Pool Scrubbing effect”. Hydrodynamic parameters of bubbles have impact on pool scrubbing effect. However, there is only few data available to evaluate quantitatively the bubble behaviour under depressurization and/or thermal stratification conditions. Series of experiments were conducted to evaluate the influence of temperature distribution, non-condensable gas content and pressure in the Wetwell on bubble behaviour. Bubbles were visualized using High Speed Camera and adopting shadowgraphy technique. Applying Particle Tracking Velocimetry, bubble velocity and size distribution were obtained from recorded images. Experimental results show that with increasing suppression pool temperature, bubbles reaching the pool surface decreased in size and traveling velocity became slower. In pressurized wetwell, bubble behaviour was similar to that in the heated up suppression pool case, although bubble parameters were similar to the low temperature case. Higher air content induced water surface movement and bubbles were smaller due to break up.

Highly sensitive avoidance plays a key role in sensory adaptation to deep-sea hydrothermal vent environments.

Directory of Open Access Journals (Sweden)

Tetsuya Ogino

Full Text Available The environments around deep-sea hydrothermal vents are very harsh conditions for organisms due to the possibility of exposure to highly toxic compounds and extremely hot venting there. Despite such extreme environments, some indigenous species have thrived there. Alvinellid worms (Annelida are among the organisms best adapted to high-temperature and oxidatively stressful venting regions. Although intensive studies of the adaptation of these worms to the environments of hydrothermal vents have been made, little is known about the worms' sensory adaptation to the severe chemical conditions there. To examine the sensitivity of the vent-endemic worm Paralvinella hessleri to low pH and oxidative stress, we determined the concentration of acetic acid and hydrogen peroxide that induced avoidance behavior of this worm, and compared these concentrations to those obtained for related species inhabiting intertidal zones, Thelepus sp. The concentrations of the chemicals that induced avoidance behavior of P. hessleri were 10-100 times lower than those for Thelepus sp. To identify the receptors for these chemicals, chemical avoidance tests were performed with the addition of ruthenium red, a blocker of transient receptor potential (TRP channels. This treatment suppressed the chemical avoidance behavior of P. hessleri, which suggests that TRP channels are involved in the chemical avoidance behavior of this species. Our results revealed for the first time hypersensitive detection systems for acid and for oxidative stress in the vent-endemic worm P. hessleri, possibly mediated by TRP channels, suggesting that such sensory systems may have facilitated the adaptation of this organism to harsh vent environments.

Characteristics of Sulfuric Acid Condensation on Cylinder Liners of Large Two-Stroke Marine Engines

DEFF Research Database (Denmark)

Cordtz, Rasmus Lage; Mayer, Stefan; Schramm, Jesper

. Formation of corrosive sulfuric acid in the cylinder gas is modeled with a cali-brated engine model that incorporates a detailed sulfur reaction mechanism. Condensation of sulfuric acid follows the analogy between heat and mass transfer. Average bulk gas acid dew points are calculated by applying two......-phase thermochemistry of the binary H2O-H2SO4 system. Max dew points of typically more than 200 °C are modeled close to max pressure and variations in terms of operating conditions are not large. However small increments of the dew point provided by e.g. the residual gas fraction, operating pressure, sulfur content...

Synthesis of condensed double cesium manganese phosphates in melts of polyphosphoric acids

International Nuclear Information System (INIS)

Guzeeva, L.S.; Tananaev, I.V.

1988-01-01

This work is a continuation of investigations to establish the composition and formation conditions of condensed double cesium manganese phosphates and obtain x-ray and other characteristics of the compounds isolated. We studied cross sections of Cs 2 O-MnO 2 -P 2 O 5 -H 2 O systems at 150-400 degree C and three initial P : Mn ratios - 5, 7.5, and 10 - and at a constant P : Mn ratio of 15. The reaction of manganese and cesium oxides with melts of polyphosphoric acids at 150-400 degree C leads to the separation of three types of trivalent manganese and cesium condensed double phosphates - Cs 2 MnH 3 (P 2 O 7 ) 2 , triphosphate CsMnHP 3 O 10 , and cyclohexaphosphate Cs 3 Mn 3 -(P 6 O 18 ) 2 - in addition to a divalent manganese double cyclotriphosphate CsMnP 3 O 9 . The compounds separated were characterized by chemical, x-ray phase analysis, IR spectroscopic, and thermogravimetric methods

Field Testing of an Unvented Roof with Fibrous Insulation, Tiles and Vapor Diffusion Venting

Energy Technology Data Exchange (ETDEWEB)

Ueno, K. [Building Science Corporation, Westford, MA (United States); Lstiburek, J. W. [Building Science Corporation, Westford, MA (United States)

2016-02-05

This research is a test implementation of an unvented tile roof assembly in a hot-humid climate (Orlando, FL; Zone 2A), insulated with air permeable insulation (netted and blown fiberglass). Given the localized moisture accumulation and failures seen in previous unvented roof field work, it was theorized that a 'diffusion vent' (water vapor open, but air barrier 'closed') at the highest points in the roof assembly might allow for the wintertime release of moisture, to safe levels. The 'diffusion vent' is an open slot at the ridge and hips, covered with a water-resistant but vapor open (500+ perm) air barrier membrane. As a control comparison, one portion of the roof was constructed as a typical unvented roof (self-adhered membrane at ridge). The data collected to date indicate that the diffusion vent roof shows greater moisture safety than the conventional, unvented roof design. The unvented roof had extended winter periods of 95-100% RH, and wafer (wood surrogate RH sensor) measurements indicating possible condensation; high moisture levels were concentrated at the roof ridge. In contrast, the diffusion vent roofs had drier conditions, with most peak MCs (sheathing) below 20%. In the spring, as outdoor temperatures warmed, all roofs dried well into the safe range (10% MC or less). Some roof-wall interfaces showed moderately high MCs; this might be due to moisture accumulation at the highest point in the lower attic, and/or shading of the roof by the adjacent second story. Monitoring will be continued at least through spring 2016 (another winter and spring).

Modeling the condensation of sulfuric acid and water on the cylinder liner of a large two-stroke marine diesel engine

DEFF Research Database (Denmark)

Cordtz, Rasmus Faurskov; Mayer, Stefan; Eskildsen, Svend S.

2018-01-01

Corrosive wear of cylinder liners in large two-stroke marine diesel engines that burn heavy fuel oil containing sulfur is coupled to the formation of gaseous sulfur trioxide (SO3) and subsequent combined condensation of sulfuric acid (H2SO4) and water (H2O) vapor. The present work seeks to address...... vapor liquid equilibrium. By assuming homogenous cylinder gas mixtures condensation is modeled using a convective heat and mass transfer analogy combined with realistic liner temperature profiles. Condensation of water is significantly altered by the liner temperature and charge air humidity while...... how fuel sulfur content, charge air humidity and liner temperature variations affects the deposition of water and sulfuric acid at low load operation. A phenomenological engine model is applied to simulate the formation of cylinder/bulk gas combustion products and dew points comply with H2O–H2SO4...

Measure Guideline: Passive Vents

Energy Technology Data Exchange (ETDEWEB)

Berger, David [Consortium for Advanced Residential Buildings, Norwalk, CT (United States); Neri, Robin [Consortium for Advanced Residential Buildings, Norwalk, CT (United States)

2016-02-05

This document addresses the use of passive vents as a source of outdoor air in multifamily buildings. The challenges associated with implementing passive vents and the factors affecting performance are outlined. A comprehensive design methodology and quantified performance metrics are provided. Two hypothetical design examples are provided to illustrate the process. This document is intended to be useful to designers, decision-makers, and contractors implementing passive ventilation strategies. It is also intended to be a resource for those responsible for setting high-performance building program requirements, especially pertaining to ventilation and outdoor air. To ensure good indoor air quality, a dedicated source of outdoor air is an integral part of high-performance buildings. Presently, there is a lack of guidance pertaining to the design and installation of passive vents, resulting in poor system performance. This report details the criteria necessary for designing, constructing, and testing passive vent systems to enable them to provide consistent and reliable levels of ventilation air from outdoors.

Heat transfer, erosion and acid condensation characteristics for novel H-type finned oval tube

International Nuclear Information System (INIS)

Wang, Y; Zhao, X; Tang, G

2015-01-01

Low efficiency of heat transfer, acid corrosion and erosion of economizers affect the economy and security in coal-fired power plants significantly. The H-type finned oval tube is proposed to alleviate these problems. Based on the H-type finned oval tube, we investigated three novel types of fins, including bleeding dimples, longitudinal vortex generators (LVGs), and compound dimple-LVG. We considered the three aspects together, and obtained the heat transfer, acid condensation rate and erosion loss. The results show that the tube bank with the new structured fins can improve the performance on the three aspects, and the compound dimple-LVG performs the highest comprehensive effect. (paper)

Synthesis of Fe Nanoparticles Functionalized with Oleic Acid Synthesized by Inert Gas Condensation

Directory of Open Access Journals (Sweden)

L. G. Silva

2014-01-01

Full Text Available In this work, we study the synthesis of monodispersed Fe nanoparticles (Fe-NPs in situ functionalized with oleic acid. The nanoparticles were self-assembled by inert gas condensation (IGC technique by using magnetron-sputtering process. Structural characterization of Fe-NPs was performed by transmission electron microscopy (TEM. Particle size control was carried out through the following parameters: (i condensation zone length, (ii magnetron power, and (iii gas flow (Ar and He. Typically the nanoparticles generated by IGC showed diameters which ranged from ~0.7 to 20 nm. Mass spectroscopy of Fe-NPs in the deposition system allowed the study of in situ nanoparticle formation, through a quadrupole mass filter (QMF that one can use together with a mass filter. When the deposition system works without quadrupole mass filter, the particle diameter distribution is around +/−20%. When the quadrupole is in line, then the distribution can be reduced to around +/−2%.

Airborne lidar detection of an underwater thermal vent

Science.gov (United States)

Roddewig, Michael R.; Churnside, James H.; Shaw, Joseph A.

2017-07-01

We report the lidar detection of an underwater feature that appears to be a thermal vent in Yellowstone Lake, Yellowstone National Park, USA, with the Montana State University Fish Lidar. The location of the detected vent was 30 m from the closest vent identified in a United States Geological Survey of Yellowstone Lake in 2008. A second possible vent is also presented, and the appearance of both vents in the lidar data is compared to descriptions of underwater thermal vents in Yellowstone Lake from the geological literature.

40 CFR 405.110 - Applicability; description of the condensed whey subcategory.

Science.gov (United States)

2010-07-01

... condensed whey subcategory. 405.110 Section 405.110 Protection of Environment ENVIRONMENTAL PROTECTION... Condensed Whey Subcategory § 405.110 Applicability; description of the condensed whey subcategory. The... whey and condensed acid whey. ...

Condensed phase preparation of 2,3-pentanedione

Science.gov (United States)

Miller, D.J.; Perry, S.M.; Fanson, P.T.; Jackson, J.E.

1998-11-03

A condensed phase process for the preparation of purified 2,3-pentanedione from lactic acid and an alkali metal lactate is described. The process uses elevated temperatures between about 200 to 360 C for heating a reaction mixture of lactic acid and an alkali metal lactate to produce the 2,3-pentanedione in a reaction vessel. The 2,3-pentanedione produced is vaporized from the reaction vessel and condensed with water. 5 figs.

Acidophiles of saline water at thermal vents of Vulcano, Italy.

Science.gov (United States)

Simmons, Susan; Norris, R

2002-06-01

DNA was extracted from samples taken from close to acidic hydrothermal vents on shore of the Aeolian Island of Vulcano (Italy). RNA gene sequences were amplified by PCR, cloned, and sequenced. A sequence with an origin in samples at 35 degrees and 45 degrees C corresponded to that of a novel Acidithiobacillus species that was isolated from water close to the vents. Novel, iron-oxidizing mesophilic acidophiles were isolated through enrichment cultures with ferrous iron but were not represented in the clone banks of environmental rDNA. These acidophiles were related to Thiobacillus prosperus, which was isolated previously from Vulcano. The archaeal sequences that comprised a clone bank representing a high-temperature sample (75 degrees C) corresponded to those of Acidianus brierleyi and of thermophiles previously isolated from Vulcano, Thermoplasma volcanium and Acidianus infernus.

Numerical Simulation of Condensation of Sulfuric Acid and Water in a Large Two-stroke Marine Diesel Engine

DEFF Research Database (Denmark)

Walther, Jens Honore; Karvounis, Nikolas; Pang, Kar Mun

2016-01-01

We present results from computational fluid dynamics simulations of the condensation of sulfuric acid (H2SO4) and water (H2O) in a large two-stroke marine diesel engine. The model uses a reduced n-heptane skeletal chemical mechanism coupled with a sulfur subsetto simulate the combustion process...

Venting of gas deflagrations through relief pipes

OpenAIRE

Ferrara, Gabriele

2006-01-01

Vent devices for gas and dust explosions are often ducted to safety locations by means of relief pipes for the discharge of hot combustion products or blast waves (NFPA 68, 2002). The presence of the duct is likely to increase the severity of the explosion with respect to simply vented vessels posing a problem for the proper design of this venting configuration. The phenomenology of the vented explosion is complicated as the interaction of combustion in the duct with primary combustion in...

Camphor-10-sulfonic acid catalyzed condensation of 2-naphthol with aromatic/aliphatic aldehydes to 14-aryl/alkyl-14H-dibenzo[a,j]xanthenes

Directory of Open Access Journals (Sweden)

Kundu Kshama

2014-01-01

Full Text Available (±-Camphor-10-sulfonic acid (CSA catalyzed condensation of 2-naphthol with both aliphatic/aromatic aldehydes at 80°C yielded 14-alkyl/aryl-dibenzoxanthenes as the sole product in high yields. However, the same condensation with benzaldehyde at 25°C afforded a mixture of intermediate 1,1-bis-(2-hydroxynaphthylphenylmethane and 14-phenyl-dibenzoxanthene while the condensation with aliphatic aldehydes at 25°C furnished the corresponding 14-alkyl-dibenzoxanthenes as the sole product. Moreover, condensation of 2-naphthol with aromatic/aliphatic aldehydes with low catalyst loading (2 mol% was greatly accelerated under microwave irradiation to afford the corresponding 14-aryl/alkyl-dibenzoxanthenes as the sole product in high yields.

Amino Acid Stability in the Early Oceans

Science.gov (United States)

Parker, E. T.; Brinton, K. L.; Burton, A. S.; Glavin, D. P.; Dworkin, J. P.; Bada, J. L.

2015-01-01

It is likely that a variety of amino acids existed in the early oceans of the Earth at the time of the origin and early evolution of life. "Primordial soup", hydrothermal vent, and meteorite based processes could have contributed to such an inventory. Several "protein" amino acids were likely present, however, based on prebiotic synthesis experiments and carbonaceous meteorite studies, non-protein amino acids, which are rare on Earth today, were likely the most abundant. An important uncertainty is the length of time these amino acids could have persisted before their destruction by abiotic and biotic processes. Prior to life, amino acid concentrations in the oceans were likely regulated by circulation through hydro-thermal vents. Today, the entire ocean circulates through vent systems every 10(exp 7) years. On the early Earth, this value was likely smaller due to higher heat flow and thus marine amino acid life-time would have been shorter. After life, amino acids in the oceans could have been assimilated by primitive organisms.

Ellagic Acid-Changed Epigenome of Ribosomal Genes and Condensed RPA194-Positive Regions of Nucleoli in Tumour Cells.

Science.gov (United States)

Legartová, S; Sbardella, G; Kozubek, S; Bártová, E

2015-01-01

We studied the effect of ellagic acid (EA) on the morphology of nucleoli and on the pattern of major proteins of the nucleolus. After EA treatment of HeLa cells, we observed condensation of nucleoli as documented by the pattern of argyrophilic nucleolar organizer regions (AgNORs). EA also induced condensation of RPA194-positive nucleolar regions, but no morphological changes were observed in nucleolar compartments positive for UBF1/2 proteins or fibrillarin. Studied morphological changes induced by EA were compared with the morphology of control, non-treated cells and with pronounced condensation of all nucleolar domains caused by actinomycin D (ACT-D) treatment. Similarly as ACT-D, but in a lesser extent, EA induced an increased number of 53BP1-positive DNA lesions. However, the main marker of DNA lesions, γH2AX, was not accumulated in body-like nuclear structures. An increased level of γH2AX was found by immunofluorescence and Western blots only after EA treatment. Intriguingly, the levels of fibrillarin, UBF1/2 and γH2AX were increased at the promoters of ribosomal genes, while 53BP1 and CARM1 levels were decreased by EA treatment at these genomic regions. In the entire genome, EA reduced H3R17 dimethylation. Taken together, ellagic acid is capable of significantly changing the nucleolar morphology and protein levels inside the nucleolus.

Biomolecular condensates: organizers of cellular biochemistry.

Science.gov (United States)

Banani, Salman F; Lee, Hyun O; Hyman, Anthony A; Rosen, Michael K

2017-05-01

Biomolecular condensates are micron-scale compartments in eukaryotic cells that lack surrounding membranes but function to concentrate proteins and nucleic acids. These condensates are involved in diverse processes, including RNA metabolism, ribosome biogenesis, the DNA damage response and signal transduction. Recent studies have shown that liquid-liquid phase separation driven by multivalent macromolecular interactions is an important organizing principle for biomolecular condensates. With this physical framework, it is now possible to explain how the assembly, composition, physical properties and biochemical and cellular functions of these important structures are regulated.

Recovery of Water from Boiler Flue Gas Using Condensing Heat Exchangers

Energy Technology Data Exchange (ETDEWEB)

Edward Levy; Harun Bilirgen; John DuPoint

2011-03-31

Most of the water used in a thermoelectric power plant is used for cooling, and DOE has been focusing on possible techniques to reduce the amount of fresh water needed for cooling. DOE has also been placing emphasis on recovery of usable water from sources not generally considered, such as mine water, water produced from oil and gas extraction, and water contained in boiler flue gas. This report deals with development of condensing heat exchanger technology for recovering moisture from flue gas from coal-fired power plants. The report describes: (1) An expanded data base on water and acid condensation characteristics of condensing heat exchangers in coal-fired units. This data base was generated by performing slip stream tests at a power plant with high sulfur bituminous coal and a wet FGD scrubber and at a power plant firing high-moisture, low rank coals. (2) Data on typical concentrations of HCl, HNO{sub 3} and H{sub 2}SO{sub 4} in low temperature condensed flue gas moisture, and mercury capture efficiencies as functions of process conditions in power plant field tests. (3) Theoretical predictions for sulfuric acid concentrations on tube surfaces at temperatures above the water vapor dewpoint temperature and below the sulfuric acid dew point temperature. (4) Data on corrosion rates of candidate heat exchanger tube materials for the different regions of the heat exchanger system as functions of acid concentration and temperature. (5) Data on effectiveness of acid traps in reducing sulfuric acid concentrations in a heat exchanger tube bundle. (6) Condensed flue gas water treatment needs and costs. (7) Condensing heat exchanger designs and installed capital costs for full-scale applications, both for installation immediately downstream of an ESP or baghouse and for installation downstream of a wet SO{sub 2} scrubber. (8) Results of cost-benefit studies of condensing heat exchangers.

Recovery of Water from Boiler Flue Gas Using Condensing Heat Exchangers

Energy Technology Data Exchange (ETDEWEB)

Levy, Edward; Bilirgen, Harun; DuPont, John

2011-03-31

Most of the water used in a thermoelectric power plant is used for cooling, and DOE has been focusing on possible techniques to reduce the amount of fresh water needed for cooling. DOE has also been placing emphasis on recovery of usable water from sources not generally considered, such as mine water, water produced from oil and gas extraction, and water contained in boiler flue gas. This report deals with development of condensing heat exchanger technology for recovering moisture from flue gas from coal-fired power plants. The report describes: • An expanded data base on water and acid condensation characteristics of condensing heat exchangers in coal-fired units. This data base was generated by performing slip stream tests at a power plant with high sulfur bituminous coal and a wet FGD scrubber and at a power plant firing highmoisture, low rank coals. • Data on typical concentrations of HCl, HNO{sub 3} and H{sub 2}SO{sub 4} in low temperature condensed flue gas moisture, and mercury capture efficiencies as functions of process conditions in power plant field tests. • Theoretical predictions for sulfuric acid concentrations on tube surfaces at temperatures above the water vapor dewpoint temperature and below the sulfuric acid dew point temperature. • Data on corrosion rates of candidate heat exchanger tube materials for the different regions of the heat exchanger system as functions of acid concentration and temperature. • Data on effectiveness of acid traps in reducing sulfuric acid concentrations in a heat exchanger tube bundle. • Condensed flue gas water treatment needs and costs. • Condensing heat exchanger designs and installed capital costs for full-scale applications, both for installation immediately downstream of an ESP or baghouse and for installation downstream of a wet SO{sub 2} scrubber. • Results of cost-benefit studies of condensing heat exchangers.

14 CFR 27.975 - Fuel tank vents.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel tank vents. 27.975 Section 27.975... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Fuel System § 27.975 Fuel tank vents. (a) Each fuel tank... system must be designed to minimize spillage of fuel through the vents to an ignition source in the event...

24 CFR 3280.710 - Venting, ventilation and combustion air.

Science.gov (United States)

2010-04-01

... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air systems...

40 CFR 63.1326 - Batch process vents-recordkeeping provisions.

Science.gov (United States)

2010-07-01

....1325(e) for aggregate batch vent streams; (ii) For a boiler or process heater, a description of the location at which the vent stream is introduced into the boiler or process heater; (iii) For a boiler or... process vents or halogenated aggregate batch vent streams, the percent reduction of total hydrogen halides...

Thermal hydraulic analysis of BWR containment venting system

International Nuclear Information System (INIS)

Baburajan, P.K.; Sharma, Prashant; Paul, U.K.; Gaikwad, Avinash

2015-01-01

Installation of additional containment filtered venting system (CFVS) is necessary to depressurize the containment to maintain its mechanical integrity due to over pressurization during severe accident condition. A typical venting system for BWR is modelled using RELAP5 and analysed to investigate the effect of various thermal hydraulic parameters on the operational parameters of the venting system. The venting system consists of piping from the containment to the scrubber tank and exit line from the scrubber tank. The scrubber tank is partially filled with water to enable the scrubbing action to remove the particulate radionuclides from the incoming containment air. The pipe line from the containment is connected to the venturi inlet and the throat of the venturi is open to the scrubber tank water inventory at designed submergence level. The exit of the venturi is open to scrubber tank water. Filters are used in the upper air space of the scrubber tank as mist separator before venting out the air into the atmosphere through the exit vent line. The effect of thermal hydraulic parameters such as inlet fluid temperature, inlet steam content and venturi submergence in the scrubber tank on the venting flow rate, exit steam content, scrubber tank inventory, overflow line and siphon breaker flow rate is analysed. Results show that inlet steam content and the venturi nozzle submergence influence the venting system parameters. (author)

40 CFR 61.356 - Recordkeeping requirements.

Science.gov (United States)

2010-07-01

... requirements specified in 40 CFR 60.18. (E) For a condenser, the design analysis shall consider the vent stream... concentration level, design average temperature of the condenser exhaust vent stream, and the design average... condenser exhaust vent stream is more than 6 °C (11 °F) above the design average exhaust vent stream...

Control of waste well casing vent gas from a thermal enhanced oil recovery operation

International Nuclear Information System (INIS)

Peavy, M.A.; Braun, J.E.

1991-01-01

This paper presents an overview of a waste gas treatment system designed to control emissions from thermally enhanced oil recovery wells. This case study discusses the need, design, installation and operations of the system. Oryx Energy Company (Oryx) operates approximately 940 wells in the Midway-Sunset (MWSS) field under casing vapor recovery systems. The emissions collected from well casing vent gas cotaining hydrocarbons and hydrogen sulfide that are collected and processed through casing vapor recovery skids. These skids are composed of condensers, compressors, and pumps that separate fluids from the waste gas stream. The non-condensible gas is then disposed of in incinerators that reduce the hydrocarbon and sulfur emissions into the atmosphere. Approximately 91,000 lbs/day of hydrocarbon and 10,116 lbs/day of sulfur dioxide are removed from the atmosphere from wells contained within these systems operated by Oryx. These hydrocarbons yield approximately 550 barrels of oil per day (BOPD). The system helps manage the pressure differential from the reservoir into each wellbore and contributes to improved ambient air quality in Kern County, California

Decoupling damage mechanisms in acid-fractured gas/condensate reservoirs

Energy Technology Data Exchange (ETDEWEB)

Bachman, R.C.; Walters, D.A. [Taurus Reservoir Solutions Ltd., Calgary, AB (Canada); Settari, A. [Calgary Univ., AB (Canada); Rahim, Z.; Ahmed, M.S. [Saudi Aramco, Dhahran (Saudi Arabia)

2006-07-01

The Khuff is a gas condensate field located 11,500 feet beneath the producing Ghawar oil field in Saudi Arabia. Wells are mainly acid fracture stimulated following drilling with excellent fracture conductivity and length properties. The wells experience a quick production loss however, after tie-in which eventually stabilizes after two to five months. In order to identify the source of productivity loss, such as near well liquid dropout, fracture conductivity loss, reservoir permeability loss due to increased effective stress, a study of a well in the Khuff field was conducted. The study reviewed basic geomechanical and reservoir properties and identified the mechanisms of production loss. The paper presented the methodology, data and preliminary analysis, relative permeability and results of the history matching. It was concluded that traditional production type curves in cases with changing skin may indicate that transient flow is occurring when boundary effects are felt. In addition, stress dependent fracture conductivity and reservoir permeability can be modeled with simpler pressure dependent functions for relatively low overall loss in reservoir pressure. 30 refs., 25 figs., 1 appendix.

Review of containment vent filter technology

International Nuclear Information System (INIS)

Kovach, J.L.

1989-01-01

The technology applied for the design and construction of containment vent filters is compiled and reviewed. The national positions leading to the selection of venting or method of filtration are extracted from position papers. Several areas of further information needs are identified

Food-web complexity across hydrothermal vents on the Azores triple junction

Science.gov (United States)

Portail, Marie; Brandily, Christophe; Cathalot, Cécile; Colaço, Ana; Gélinas, Yves; Husson, Bérengère; Sarradin, Pierre-Marie; Sarrazin, Jozée

2018-01-01

The assessment and comparison of food webs across various hydrothermal vent sites can enhance our understanding of ecological processes involved in the structure and function of biodiversity. The Menez Gwen, Lucky Strike and Rainbow vent fields are located on the Azores triple junction of the Mid-Atlantic Ridge. These fields have distinct depths (from 850 to 2320 m) and geological contexts (basaltic and ultramafic), but share similar faunal assemblages defined by the presence of foundation species that include Bathymodiolus azoricus, alvinocarid shrimp and gastropods. We compared the food webs of 13 faunal assemblages at these three sites using carbon and nitrogen stable isotope analyses (SIA). Results showed that photosynthesis-derived organic matter is a negligible basal source for vent food webs, at all depths. The contribution of methanotrophy versus autotrophy based on Calvin-Benson-Bassham (CBB) or reductive tricarboxylic acid (rTCA) cycles varied between and within vent fields according to the concentrations of reduced compounds (e.g. CH4, H2S). Species that were common to vent fields showed high trophic flexibility, suggesting weak trophic links to the metabolism of chemosynthetic primary producers. At the community level, a comparison of SIA-derived metrics between mussel assemblages from two vent fields (Menez Gwen & Lucky Strike) showed that the functional structure of food webs was highly similar in terms of basal niche diversification, functional specialization and redundancy. Coupling SIA to functional trait approaches included more variability within the analyses, but the functional structures were still highly comparable. These results suggest that despite variable environmental conditions (physico-chemical factors and basal sources) and faunal community structure, functional complexity remained relatively constant among mussel assemblages. This functional similarity may be favoured by the propensity of species to adapt to fluid variations and

Vented Capacitor

Science.gov (United States)

Brubaker, Michael Allen; Hosking, Terry Alan

2006-04-11

A technique of increasing the corona inception voltage (CIV), and thereby increasing the operating voltage, of film/foil capacitors is described. Intentional venting of the capacitor encapsulation improves the corona inception voltage by allowing internal voids to equilibrate with the ambient environment.

Experimental Investigation of Sulfuric Acid Condensation and Corrosion Rate in Motored Bukh DV24 Diesel Engine

DEFF Research Database (Denmark)

Kjemtrup, Lars; Cordtz, Rasmus Faurskov; Meyer, Martin

2017-01-01

The work conducted in this paper presents a novel experimental setup to study sulfuric acid cold corrosion of cylinder liners in large two-stroke marine diesel engines. The process is simulated in a motored light duty BUKH DV24 diesel engine where the charge air contain known amounts of H2SO4 and H......2O vapor. Liner corrosion is measured as iron accumulation in the lubeoil. Similarly sulfuric acid condensation is assessed by measuring the accumulation of sulfur in the lube oil. To clarify the corrosive effect of sulfuric acid the lube oil utilized for experiments is a sulfur free neutral oil...... without alkaline additives (Chevron Neutral Oil 600R). Iron and sulfur accumulation in the lube oil is analyzed withan Energy Dispersive X-Ray Fluorescence (ED-XRF) apparatus. Three test cases with different H2SO4 concentrations are run. Results reveal good agreement between sulfuric acid injection flow...

33 CFR 183.520 - Fuel tank vent systems.

Science.gov (United States)

2010-07-01

...) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Equipment Standards § 183.520 Fuel tank vent systems. (a) Each fuel tank must have a vent system that prevents pressure in the tank from exceeding 80... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Fuel tank vent systems. 183.520...

Food-Web Complexity in Guaymas Basin Hydrothermal Vents and Cold Seeps.

Directory of Open Access Journals (Sweden)

Marie Portail

Full Text Available In the Guaymas Basin, the presence of cold seeps and hydrothermal vents in close proximity, similar sedimentary settings and comparable depths offers a unique opportunity to assess and compare the functioning of these deep-sea chemosynthetic ecosystems. The food webs of five seep and four vent assemblages were studied using stable carbon and nitrogen isotope analyses. Although the two ecosystems shared similar potential basal sources, their food webs differed: seeps relied predominantly on methanotrophy and thiotrophy via the Calvin-Benson-Bassham (CBB cycle and vents on petroleum-derived organic matter and thiotrophy via the CBB and reductive tricarboxylic acid (rTCA cycles. In contrast to symbiotic species, the heterotrophic fauna exhibited high trophic flexibility among assemblages, suggesting weak trophic links to the metabolic diversity of chemosynthetic primary producers. At both ecosystems, food webs did not appear to be organised through predator-prey links but rather through weak trophic relationships among co-occurring species. Examples of trophic or spatial niche differentiation highlighted the importance of species-sorting processes within chemosynthetic ecosystems. Variability in food web structure, addressed through Bayesian metrics, revealed consistent trends across ecosystems. Food-web complexity significantly decreased with increasing methane concentrations, a common proxy for the intensity of seep and vent fluid fluxes. Although high fluid-fluxes have the potential to enhance primary productivity, they generate environmental constraints that may limit microbial diversity, colonisation of consumers and the structuring role of competitive interactions, leading to an overall reduction of food-web complexity and an increase in trophic redundancy. Heterogeneity provided by foundation species was identified as an additional structuring factor. According to their biological activities, foundation species may have the potential to

Sulfur Metabolism of Hydrogenovibrio thermophilus Strain S5 and Its Adaptations to Deep-Sea Hydrothermal Vent Environment

Directory of Open Access Journals (Sweden)

Lijing Jiang

2017-12-01

Full Text Available Hydrogenovibrio bacteria are ubiquitous in global deep-sea hydrothermal vents. However, their adaptations enabling survival in these harsh environments are not well understood. In this study, we characterized the physiology and metabolic mechanisms of Hydrogenovibrio thermophilus strain S5, which was first isolated from an active hydrothermal vent chimney on the Southwest Indian Ridge. Physiological characterizations showed that it is a microaerobic chemolithomixotroph that can utilize sulfide, thiosulfate, elemental sulfur, tetrathionate, thiocyanate or hydrogen as energy sources and molecular oxygen as the sole electron acceptor. During thiosulfate oxidation, the strain produced extracellular sulfur globules 0.7–6.0 μm in diameter that were mainly composed of elemental sulfur and carbon. Some organic substrates including amino acids, tryptone, yeast extract, casamino acids, casein, acetate, formate, citrate, propionate, tartrate, succinate, glucose and fructose can also serve as carbon sources, but growth is weaker than under CO2 conditions, indicating that strain S5 prefers to be chemolithoautotrophic. None of the tested organic carbons could function as energy sources. Growth tests under various conditions confirmed its adaption to a mesophilic mixing zone of hydrothermal vents in which vent fluid was mixed with cold seawater, preferring moderate temperatures (optimal 37°C, alkaline pH (optimal pH 8.0, microaerobic conditions (optimal 4% O2, and reduced sulfur compounds (e.g., sulfide, optimal 100 μM. Comparative genomics showed that strain S5 possesses more complex sulfur metabolism systems than other members of genus Hydrogenovibrio. The genes encoding the intracellular sulfur oxidation protein (DsrEF and assimilatory sulfate reduction were first reported in the genus Hydrogenovibrio. In summary, the versatility in energy and carbon sources, and unique physiological properties of this bacterium have facilitated its adaptation to deep

Containment venting sliding pressure venting process for PWR and BWR plants

International Nuclear Information System (INIS)

Eckardt, B.

1991-01-01

In order to reduce the residual risk associated with hypothetical severe nuclear accidents, nuclear power plants in Germany as well as in certain other European countries have been or will be backfitted with a system for filtered containment venting. During venting system process design, particular importance is attached to the requirements regarding, for example, high aerosol loading capability, provision for decay heat removal from the scrubber unit, the aerosol spectrum to be retained and entirely passive functioning of the scrubber unit. The aerosol spectrum relevant for process design and testing varies depending on aerosol concentrations, the time at which venting is commenced and whether there is an upstream wetwell, etc. Because of this the Reactor Safety Commission in Germany has specified that SnO 2 with a mass mean diameter of approximately 0.5 μm should be used as an enveloping test aerosol. To meet the above-mentioned requirements, a combined venturi scrubber system was developed which comprises a venturi section and a filter demister section and is operated in the sliding pressure mode. This scrubber system was tested using a full-scale model and has now been installed in 14 PWR and BWR plants in Germany and Finland

46 CFR 56.50-85 - Tank-vent piping.

Science.gov (United States)

2010-10-01

... of the tanks to vent pipes. (2) Tanks having a comparatively small surface, such as fuel oil settling... 46 Shipping 2 2010-10-01 2010-10-01 false Tank-vent piping. 56.50-85 Section 56.50-85 Shipping... APPURTENANCES Design Requirements Pertaining to Specific Systems § 56.50-85 Tank-vent piping. (a) This section...

Toward understanding of the role of Lewis acidity in aldol condensation of acetone and furfural using MOF and zeolite catalysts

Czech Academy of Sciences Publication Activity Database

Kikhtyanin, O.; Kubička, D.; Čejka, Jiří

2015-01-01

Roč. 243, APR 2015 (2015), s. 158-162 ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : metal organic framework * aldol condensation * acidic catalysis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.312, year: 2015

Acetic acid-promoted condensation of o-phenylenediamine with aldehydes into 2-aryl-1-(arylmethyl-1H-benzimidazoles under microwave irradiation

Directory of Open Access Journals (Sweden)

DAVOOD AZARIF

2010-09-01

Full Text Available An efficient and simple procedure was developed for the green synthesis of various 2-aryl-1-(arylmethyl-1H-benzimidazoles in high yields by acetic acid-promoted condensation of o-phenylenediamine with aldehydes in air under microwave irradiation and transition metal catalyst-free conditions.

Monitoring arrangement for vented nuclear fuel elements

International Nuclear Information System (INIS)

Campana, R.J.

1981-01-01

In a nuclear fuel reactor core, fuel elements are arranged in a closely packed hexagonal configuration, each fuel element having diametrically opposed vents permitting 180 0 rotation of the fuel elements to counteract bowing. A grid plate engages the fuel elements and forms passages for communicating sets of three, four or six individual vents with respective monitor lines in order to communicate vented radioactive gases from the fuel elements to suitable monitor means in a manner readily permitting detection of leakage in individual fuel elements

The stereochemistry of the condensation product of salicylaldehyde and n-butylbarbituric acid by NMR techniques

International Nuclear Information System (INIS)

Cruz, Elizabete R.; Villar, J. Daniel Figueroa

1995-01-01

Since the discovery of the 5-deazaflavin cofactor (coenzyme F 420 ) as a naturally occurring compound, a great attention has been focused on several iso steric flavin analogues. One of the simplest approaches towards the synthesis of oxadeazaflavin, compound which the nitrogen at the N-10 position of 5-deazaflavin is replaced by oxygen, is the direct condensation between barbituric acid and salicylaldehyde. In this paper, the use of some NMR techniques so as to determine the stereochemistry of the preformed isomer has been described and a possible mechanism for this isomerization discussed

Maintenir la continuité des collections à l'heure d'Internet : du catalogue de vente au site web de maison de vente

OpenAIRE

Jacquet , Françoise

2014-01-01

International audience; La Bibliothèque nationale de France conserve depuis des siècles une importante collection de catalogues de vente sur support papier. Cependant avec l’apparition d’Internet on assiste à une dématérialisation des données documentaires en art. Aujourd’hui les sites des maisons de vente offrent en ligne les adjudications des ventes, récentes ou archivées et certaines ventes sont désormais annoncées uniquement sur Internet. Ces informations qui ne se trouvent pas sur les ca...

Utilization of Condensed Distillers Solubles as Nutrient Supplement for Production of Nisin and Lactic Acid from Whey

Science.gov (United States)

Liu, Chuanbin; Hu, Bo; Chen, Shulin; Glass, Richard W.

The major challenge associated with the rapid growth of the ethanol industry is the usage of the coproducts, i.e., condensed distillers solubles (CDS) and distillers dried grains, which are currently sold as animal feed supplements. As the growth of the livestock industries remains flat, alternative usage of these coproducts is urgently needed. CDS is obtained after the removal of ethanol by distillation from the yeast fermentation of a grain or a grain mixture by condensing the thin stillage fraction to semisolid. In this work, CDS was first characterized and yeast biomass was proven to be the major component of CDS. CDS contained 7.50% crude protein but with only 42% of that protein being water soluble. Then, CDS was applied as a nutrient supplement for simultaneous production of nisin and lactic acid by Lactococcus lactis subsp. lactis (ATCC 11454). Although CDS was able to support bacteria growth and nisin production, a strong inhibition was observed when CDS was overdosed. This may be caused by the existence of the major ethanol fermentation byproducts, especially lactate and acetate, in CDS. In the final step, the CDS based medium composition for nisin and lactic acid production was optimized using response surface methodology.

Hydrogen is an energy source for hydrothermal vent symbioses.

Science.gov (United States)

Petersen, Jillian M; Zielinski, Frank U; Pape, Thomas; Seifert, Richard; Moraru, Cristina; Amann, Rudolf; Hourdez, Stephane; Girguis, Peter R; Wankel, Scott D; Barbe, Valerie; Pelletier, Eric; Fink, Dennis; Borowski, Christian; Bach, Wolfgang; Dubilier, Nicole

2011-08-10

The discovery of deep-sea hydrothermal vents in 1977 revolutionized our understanding of the energy sources that fuel primary productivity on Earth. Hydrothermal vent ecosystems are dominated by animals that live in symbiosis with chemosynthetic bacteria. So far, only two energy sources have been shown to power chemosynthetic symbioses: reduced sulphur compounds and methane. Using metagenome sequencing, single-gene fluorescence in situ hybridization, immunohistochemistry, shipboard incubations and in situ mass spectrometry, we show here that the symbionts of the hydrothermal vent mussel Bathymodiolus from the Mid-Atlantic Ridge use hydrogen to power primary production. In addition, we show that the symbionts of Bathymodiolus mussels from Pacific vents have hupL, the key gene for hydrogen oxidation. Furthermore, the symbionts of other vent animals such as the tubeworm Riftia pachyptila and the shrimp Rimicaris exoculata also have hupL. We propose that the ability to use hydrogen as an energy source is widespread in hydrothermal vent symbioses, particularly at sites where hydrogen is abundant.

40 CFR 63.1408 - Aggregate batch vent stream provisions.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Aggregate batch vent stream provisions... § 63.1408 Aggregate batch vent stream provisions. (a) Emission standards. Owners or operators of aggregate batch vent streams at a new or existing affected source shall comply with either paragraph (a)(1...

Coil spring venting arrangement

International Nuclear Information System (INIS)

McCugh, R.M.

1975-01-01

A simple venting device for trapped gas pockets in hydraulic systems is inserted through a small access passages, operated remotely, and removed completely. The device comprises a small diameter, closely wound coil spring which is pushed through a guide temporarily inserted in the access passage. The guide has a central passageway which directs the coil spring radially upward into the pocket, so that, with the guide properly positioned for depth and properly oriented, the coil spring can be pushed up into the top of the pocket to vent it. By positioning a seal around the free end of the guide, the spring and guide are removed and the passage is sealed

Gravitationally Driven Wicking for Enhanced Condensation Heat Transfer.

Science.gov (United States)

Preston, Daniel J; Wilke, Kyle L; Lu, Zhengmao; Cruz, Samuel S; Zhao, Yajing; Becerra, Laura L; Wang, Evelyn N

2018-04-17

Vapor condensation is routinely used as an effective means of transferring heat or separating fluids. Filmwise condensation is prevalent in typical industrial-scale systems, where the condensed fluid forms a thin liquid film due to the high surface energy associated with many industrial materials. Conversely, dropwise condensation, where the condensate forms discrete liquid droplets which grow, coalesce, and shed, results in an improvement in heat transfer performance of an order of magnitude compared to filmwise condensation. However, current state-of-the-art dropwise technology relies on functional hydrophobic coatings, for example, long chain fatty acids or polymers, which are often not robust and therefore undesirable in industrial conditions. In addition, low surface tension fluid condensates, such as hydrocarbons, pose a unique challenge because common hydrophobic condenser coatings used to shed water (with a surface tension of 73 mN/m) often do not repel fluids with lower surface tensions (condensation heat transfer using gravitationally driven flow through a porous metal wick, which takes advantage of the condensate's affinity to wet the surface and also eliminates the need for condensate-phobic coatings. The condensate-filled wick has a lower thermal resistance than the fluid film observed during filmwise condensation, resulting in an improved heat transfer coefficient of up to an order of magnitude and comparable to that observed during dropwise condensation. The improved heat transfer realized by this design presents the opportunity for significant energy savings in natural gas processing, thermal management, heating and cooling, and power generation.

Vents Pattern Analysis at Etna volcano (Sicily, Italy).

Science.gov (United States)

Brancato, Alfonso; Tusa, Giuseppina; Coltelli, Mauro; Proietti, Cristina; Branca, Stefano

2014-05-01

Mount Etna is a composite stratovolcano located along the Ionian coast of eastern Sicily. It is characterized by basaltic eruptions, both effusive and explosive, occurred during a complex eruptive history over the last 500 ka. Flank eruptions occur at an interval of decades, mostly concentrated along the NE, S and W rift zones. A vent clustering at various scales is a common feature in many volcanic settings. In order to identify the clusters within the studied area, a spatial point pattern analysis is undertaken using vent positions, both known and reconstructed. It reveals both clustering and spatial regularity in the Etna region at different distances. The visual inspection of the vent spatial distribution suggests a clustering on the rift zones of Etna volcano. To confirm this evidence, a coarse analysis is performed by the application of Ξ2- and t-test simple statistics. Then, a refined analysis is performed by using the Ripley K-function (Ripley, 1976), whose estimator K(d), knowing the area of the study region and the number of vents, allow us to calculate the distance among two different location of events. The above estimator can be easier transformed by using the Besag L-function (Besag, 1977); the peaks of positive L(d)=[K(d)/π]1/2 -d values indicate clustering while troughs of negative values stand for regularity for their corresponding distances d (L(d)=0 indicates complete spatial randomness). Spatial pattern of flank vents is investigated in order to model the spatial distribution of likely eruptive vents for the next event, basically in terms of relative probabilities. For this, a Gaussian kernel technique is used, and the L(d) function is adopted to generate an optimal smoothing bandwidth based on the clustering behaviour of the Etna volcano. A total of 154 vents (among which 36 are reconstructed), related to Etna flank activity of the last 4.0 ka, is used to model future vent opening. The investigated region covers an area of 850 km2, divided

46 CFR 182.450 - Vent pipes for fuel tanks.

Science.gov (United States)

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Vent pipes for fuel tanks. 182.450 Section 182.450... TONS) MACHINERY INSTALLATION Specific Machinery Requirements § 182.450 Vent pipes for fuel tanks. (a) Each unpressurized fuel tank must be fitted with a vent pipe connected to the highest point of the tank...

Bacterial Diets of Primary Consumers at Hydrothermal Vents

Science.gov (United States)

Govenar, B.; Shank, T. M.

2008-12-01

Chemical energy produced by mixing hydrothermal fluids and seawater supports dense biological communities on mid-ocean ridges. The base of the food web at deep-sea hydrothermal vents is formed by chemolithoautotrophic bacteria that use the energy from the oxidation of reduced chemicals to fix inorganic carbon into simple sugars. With the exception of a few species that have chemolithoautotropic bacterial symbionts, most of the vent-endemic macrofauna are heterotrophs that feed on free-living bacteria, protists, and other invertebrates. The most abundant and diverse group of primary consumers in hydrothermal vent communities belong to the Gastropoda, particularly the patellomorph limpets. Gastropod densities can be as high as 2000 individuals m-2, and there can be as many as 13 species of gastropods in a single aggregation of the siboglinid tubeworm Riftia pachyptila and more than 40 species along the East Pacific Rise. Some gastropods are ubiquitous and others are found in specific microhabitats, stages of succession, or associated with different foundation species. To determine the mechanisms of species coexistence (e.g. resource partitioning or competition) among hydrothermal vent primary consumers and to track the flow of energy in hydrothermal vent communities, we employed molecular genetic techniques to identify the gut contents of four species of co-occurring hydrothermal vent gastropods, Eulepetopsis vitrea, Lepetodrilus elevatus, Lepetodrilus ovalis and Lepetodrilus pustulosus, collected from a single diffuse-flow hydrothermal vent site on the East Pacific Rise. Unique haplotypes of the 16S gene that fell among the epsilon-proteobacteria were found in the guts of every species, and two species had gut contents that were similar only to epsilon-proteobacteria. Two species had gut contents that also included haplotypes that clustered with delta-proteobacteria, and one species had gut contents that clustered with alpha- proteobacteria. Differences in the diets

46 CFR 119.450 - Vent pipes for fuel tanks.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Vent pipes for fuel tanks. 119.450 Section 119.450... Specific Machinery Requirements § 119.450 Vent pipes for fuel tanks. (a) Each unpressurized fuel tank must... area of the vent pipe for diesel fuel tanks must be as follows: (1) Not less than the cross sectional...

The stereochemistry of the condensation product of salicylaldehyde and n-butylbarbituric acid by NMR techniques

Energy Technology Data Exchange (ETDEWEB)

Cruz, Elizabete R.; Villar, J. Daniel Figueroa [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Dept. de Quimica

1995-12-31

Since the discovery of the 5-deazaflavin cofactor (coenzyme F{sub 420}) as a naturally occurring compound, a great attention has been focused on several iso steric flavin analogues. One of the simplest approaches towards the synthesis of oxadeazaflavin, compound which the nitrogen at the N-10 position of 5-deazaflavin is replaced by oxygen, is the direct condensation between barbituric acid and salicylaldehyde. In this paper, the use of some NMR techniques so as to determine the stereochemistry of the preformed isomer has been described and a possible mechanism for this isomerization discussed 12 refs., 2 figs., 1 tab.

Solvent-Free Biginelli Condensation using Tungstate Sulfuric Acid: a Powerful and Reusable Catalyst for Selective Synthesis

Directory of Open Access Journals (Sweden)

Rezvan Rezaee Nasab

2014-07-01

Full Text Available Tungstate sulfuric acid (TSA has been prepared and used as a recyclable catalyst for the Biginelli syn-thesis of some biologically active quinazolinones/thiones under solvent-free conditions. This method has advantages such as the avoidance of organic solvents, high yield of pure products, short reaction times, and operational simplicity.  © 2014 BCREC UNDIP. All rightsReceived: 28th April 2014; Revised: 15th May 2014; Accepted: 26th May 2014[ How to Cite: Nasab, R.R., Karami, B., Khodabakhshi, S. (2014. Selective Solvent‐free Biginelli Condensation using Tungstate Sulfuric Acid as Powerful and Reusable Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 9 (2: 142-154. (doi:10.9767/bcrec.9.2.6794.148-154][ Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.2.6794.148-154

Assessing radioactive concentrates and waste vapor condensate in solidifying radioactive wastes by bituminization

International Nuclear Information System (INIS)

Tibensky, L.; Krejci, F.; Breza, M.; Timulak, J.; Hladky, E.

1986-01-01

A brief overview is presented of chemical and radiochemical methods used in the world for the analysis of the concentrate of liquid radioactive wastes from nuclear power plants destined for bituminization. Most methods are also suitable for an analysis of the condensate of waste vapors produced in bituminization. The methods of analysis of the radioactive concentrate from the V-1 nuclear power plant in Jaslovske Bohunice and of the waste vapors condensate were developed and tested in practice. Gross gamma activity was measured using a well-type Na(Tl) scintillation detector, the content of radionuclides was determined using semiconductor Ge(Li) spectrometry. The concentration of boric acid in the concentrate was determined by titration with mannite; in the condensate, using spectrophotometry with curcumine. The content of nitrates in both the concentrate and the condensate was determined spectrophotometrically using salicylic acid, the content of nitrites was determined by spectrophotometry using sulfanilic acid and α-naphthylamine. Carbonates and chlorides were determined by titration, sodium and potassium by flame photometry. The content of organic acids was measured by gravimetry of extracted methyl esters, the content of surfactants by spectrophotometry. Infrared spectrophotometry was used in determining hydrocarbons in the waste vapor condensate. The measured value range and the measurement errors are shown for each method. (A.K.)

Condensers

International Nuclear Information System (INIS)

Andrieux, M.B.

1984-01-01

Characteristics of the condenser cooling waters of various French 900 MW nuclear power plants. Design and description of various types of condensers: condensers feeded directly with river water, condensers feeded by cooling towers, condensers feeded with sea water of brackish water. Presentation of the main problems encountered with the brass bundles (ammoniacal corrosion, erosion of the peripheral tubes, vibrations of the tubes), with the titanium bundles, with the tubular plates, the tubes-tubular plates assemblies, the coatings of the condenser water chamber (sea water), the vapor by-pass and with the air inlet. Analysis of the in service performances such as condensation pressure, oxygen content and availability [fr

Characterizing the Morphology, Distribution, and Formation Geometry of Mercury's Pyroclastic Vents

Science.gov (United States)

Jozwiak, L. M.; Head, J. W.; Wilson, L.

2018-05-01

We present a final catalog of pyroclastic vents on Mercury, identifying 104 candidate pyroclastic vents. We then assess the vent distribution, morphologic variation, and probable formation geometries.

Explosion hazards of LPG-air mixtures in vented enclosure with obstacles.

Science.gov (United States)

Zhang, Qi; Wang, Yaxing; Lian, Zhen

2017-07-15

Numerical simulations were performed to study explosion characteristics of liquefied petroleum gas (LPG) explosion in enclosure with a vent. Unlike explosion overpressure and dynamic pressure, explosion temperature of the LPG-air mixture at a given concentration in a vented enclosure has very little variation with obstacle numbers for a given blockage ratio. For an enclosure without obstacle, explosion overpressures for the stoichiometric mixtures and the fuel-lean mixtures reach their maximum within the vent and that for fuel-rich mixture reaches its maximum beyond and near the vent. Dynamic pressures produced by an indoor LPG explosion reach their maximum always beyond the vent no matter obstacles are present or not in the enclosure. A LPG explosion in a vented enclosure with built-in obstacles is strong enough to make the brick and mortar wall with a thickness of 370mm damaged. If there is no obstacle in the enclosure, the lower explosion pressure of several kPa can not break the brick and mortar wall with a thickness of 370mm. For a LPG explosion produced in an enclosure with a vent, main hazards, within the vent, are overpressure and high temperature. However main hazards are dynamic pressure, blast wind, and high temperature beyond the vent. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessment of Literature Related to Combustion Appliance Venting Systems

Energy Technology Data Exchange (ETDEWEB)

Rapp, V. H.; Less, B. D.; Singer, B. C.; Stratton, J. C.; Wray, C. P.

2015-02-01

In many residential building retrofit programs, air tightening to increase energy efficiency is often constrained by safety concerns with naturally vented combustion appliances. Tighter residential buildings more readily depressurize when exhaust equipment is operated, making combustion appliances more prone to backdraft or spill combustion exhaust into the living space. Several measures, such as installation guidelines, vent sizing codes, and combustion safety diagnostics, are in place with the intent to prevent backdrafting and combustion spillage, but the diagnostics conflict and the risk mitigation objective is inconsistent. This literature review summarizes the metrics and diagnostics used to assess combustion safety, documents their technical basis, and investigates their risk mitigations. It compiles information from the following: codes for combustion appliance venting and installation; standards and guidelines for combustion safety diagnostics; research evaluating combustion safety diagnostics; research investigating wind effects on building depressurization and venting; and software for simulating vent system performance.

Filtered atmospheric venting of LWR containments

International Nuclear Information System (INIS)

Hoegberg, L.; Ahlstroem, P.E.; Bachofner, E.; Graeslund, C.; Johansson, K.; Nilsson, L.; Persson, Aa.; Eriksson, B.

1981-03-01

The FILTRA project is a cooperative Swedish programme which started in February 1980. It is aimed at investigating the possibility of reducing the risk for a large release of radioactivity, assuming a severe reactor accident. The project has been focused on filtered venting of the reactor containment. The first stage of the project has dealt with two types of severe accident sequences, namely core meltdown as a result of the complete loss of water supplies to the reactor pressure vessel and insufficient cooling of the reactor containment. Some important conclusion are the following. The applicability of computer models used to describe various phenomena in the accident sequence must be scrutinized. The details of the design of the containment are important and must be taken into consideration in a more accurate manner than in previous analyses. A pressure relief area of less than 1 m 2 appears to be adequate. The following principles should guide the technical design of filtered venting systems, namely reduction of the risk for the release of those radioactive substances which could cause long term land contamination, provision for a passive function of the vent filter system during the first 24 hours and achievement of filtering capabilities which make leakages in severe accidents comparable to the leakages of radioactive substances in less severe accidents, which do not necessarily actuate the pressure relief system. Nothing indicates that a system for filtered venting of a BWR containment would have a significant negative effect on the safety within the framework of the design basis. Efforts should be directed towards designing a filtered venting system for a BWR such as Barsebaeck. (authors)

Disposal of aqueous condensate from high efficiency gas boilers

Energy Technology Data Exchange (ETDEWEB)

Hardwick, G J; Pattison, J R

1984-01-01

If highly efficient gas-fired condensing heating appliances are installed in Britain, the aqueous condensate produced can be conveniently run into existing sewage drains. The part of the drainage system that is most vulnerable to corrosion from the mildly acid condensate is that portion adjacent to the domestic premises. The tests described indicate that this is not at risk and the only precaution that might be considered necessary is to avoid running the condensate over galvanized drain covers in order to prevent unsightly staining. Water authorities in Britain and detailed studies in the US and Holland confirm that the condensate - after dilution by domestic waste, sewage, and rainwater - would be harmless to municipal sewage systems and would not, either in volume or chemical composition, affect the working of existing sewage treatment plants.

Okadaic acid for radiation dose estimation using drug-induced premature chromosome condensation

International Nuclear Information System (INIS)

Wang Chunyan; Zhang Wei; Su Xu

2005-01-01

Objective: To establish simple biological method for high irradiation dose estimation using drug-induced prematurely condensed chromosomes (PCC) aberrations. Methods: Peripheral blood was taken from healthy adults and irradiated by 0, 1, 2, 5, 10, 15, 20 and 25 Gy 60 Co γ-rays. Then the blood samples were cultured for 48 hrs. One hr before the end of culture , okadaic acid was added into culture medium to induce PCC rings, which were counted for each dose point. Results: The yield of PCC rings was increased with the dose of radiation until 20 Gy. Within the range of 1 to 20 Gy, there was a good dose-response relationship between the yield of PCC rings and radiation dose. Conclusion: Compared with the analysis of frequency of dicentrics, the yield of PCC rings could be a good biodosimetry indicator for estimation of high dose irradiation. (authors)

Turbofan Engine Core Compartment Vent Aerodynamic Configuration Development Methodology

Science.gov (United States)

Hebert, Leonard J.

2006-01-01

This paper presents an overview of the design methodology used in the development of the aerodynamic configuration of the nacelle core compartment vent for a typical Boeing commercial airplane together with design challenges for future design efforts. Core compartment vents exhaust engine subsystem flows from the space contained between the engine case and the nacelle of an airplane propulsion system. These subsystem flows typically consist of precooler, oil cooler, turbine case cooling, compartment cooling and nacelle leakage air. The design of core compartment vents is challenging due to stringent design requirements, mass flow sensitivity of the system to small changes in vent exit pressure ratio, and the need to maximize overall exhaust system performance at cruise conditions.

Elucidation of polymer induced DNA condensation. Visualisation at the single molecular level

International Nuclear Information System (INIS)

Martin, Alison Laura

2002-01-01

DNA condensation is a phenomenon that has stimulated interest from biologists, physicists, and polymer chemists for decades. At the cellular level, this process is key to the packing of DNA within the nuclear envelope, and the exposure of the appropriate nucleic acid sequences in order for transcription to occur, and proteins to be produced. The advent of gene therapy has led to an invigoration of this subject area. In order to successfully deliver to, and transfect target cells, many delivery vectors condense the therapeutic DNA into small compact particles. The nature of these particles have a considerable influence on the ultimate expression of the administered nucleic acid material. In addition, at its most fundamental, DNA itself is a classical polyelectrolyte polymer, the behaviour of which has applicability to other charged polymeric systems. There are two core interwound themes to this investigation; the visualisation of DNA condensate morphology at ultra-resolution, and the elucidation of the mechanisms of formation of these structures. The technique of atomic force microscopy is central to these investigations. Methodologies have been devised allowing the visualisation of the tertiary structure and conformational behaviour of individual DNA condensates in near in situ conditions. Condensation of the nucleic acid material has been induced by two classes of cation; small molecular cations, like those found within eukaryotic cells, and a range of cationic polymers. The cationic polymers investigated all have considerable potential as gene delivery vectors. The resultant DNA condensates have been assessed and contrasted in terms of their tertiary morphology, lateral dimensions, and structural volume. Assessments have also been made regarding the influence of the molecular architecture of the cationic moiety and the nature of the input nucleic acid material on the resultant DNA condensates. With regard to the elucidation of the mechanisms of DNA condensate

On Small Disturbance Ascent Vent Behavior

Science.gov (United States)

Woronowicz, Michael

2015-01-01

As a spacecraft undergoes ascent in a launch vehicle, its ambient pressure environment transitions from one atmosphere to high vacuum in a matter of a few minutes. Venting of internal cavities is necessary to prevent the buildup of pressure differentials across cavity walls. These pressure differentials are often restricted to low levels to prevent violation of container integrity. Such vents usually consist of fixed orifices, ducts, or combinations of both. Duct conductance behavior is fundamentally different from that for orifices in pressure driven flows governing the launch vehicle ascent depressurization environment. Duct conductance is governed by the average pressure across its length, while orifice conductance is dictated by a pressure ratio. Hence, one cannot define a valid equivalent orifice for a given duct across a range of pressure levels. This presentation discusses development of expressions for these two types of vent elements in the limit of small pressure differentials, explores conditions for their validity, and compares their features regarding ascent depressurization performance.

Heavy metals from Kueishantao shallow-sea hydrothermal vents, offshore northeast Taiwan

Science.gov (United States)

Chen, Xue-Gang; Lyu, Shuang-Shuang; Garbe-Schönberg, Dieter; Lebrato, Mario; Li, Xiaohu; Zhang, Hai-Yan; Zhang, Ping-Ping; Chen, Chen-Tung Arthur; Ye, Ying

2018-04-01

Shallow water hydrothermal vents are a source of heavy metals leading to their accumulation in marine organisms that manage to live under extreme environmental conditions. This is the case at Kueishantao (KST) shallow-sea vents system offshore northeast Taiwan, where the heavy metal distribution in vent fluids and ambient seawater is poorly understood. This shallow vent is an excellent natural laboratory to understand how heavy and volatile metals behave in the nearby water column and ecosystem. Here, we investigated the submarine venting of heavy metals from KST field and its impact on ambient surface seawater. The total heavy metal concentrations in the vent fluids and vertical plumes were 1-3 orders of magnitude higher than the overlying seawater values. When compared with deep-sea hydrothermal systems, the estimated KST end-member fluids exhibited much lower concentrations of transition metals (e.g., Fe and Mn) but comparable concentrations of toxic metals such as Pb and As. This may be attributed to the lower temperature of the KST reaction zone and transporting fluids. Most of the heavy metals (Fe, Mn, As, Y, and Ba) in the plumes and seawater mainly originated from hydrothermal venting, while Cd and Pb were largely contributed by external sources such as contaminated waters (anthropogenic origin). The spatial distribution of heavy metals in the surface seawater indicated that seafloor venting impacts ambient seawater. The measurable influence of KST hydrothermal activity, however, was quite localized and limited to an area of heavy metals emanating from the yellow KST hydrothermal vent were: 430-2600 kg Fe, 24-145 kg Mn, 5-32 kg Ba, 10-60 kg As, 0.3-1.9 kg Cd, and 2-10 kg Pb. This study provides important data on heavy metals from a shallow-sea hydrothermal field, and it helps to better understand the environmental impact of submarine shallow hydrothermal venting.

Development of analytical model for condensation of vapor mixture of nitric acid and water affected volatilized ruthenium behavior in accident of evaporation to dryness by boiling of reprocessed high level liquid waste at fuel reprocessing facilities

International Nuclear Information System (INIS)

Yoshida, Kazuo

2016-08-01

An accident of evaporation to dryness by boiling of high level liquid waste is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, continuous vaporing of nitric acid and water leads to increase Ru volatilization in liquid waste temperature over 120degC at later boiling and dry out phases. It has been observed at the experiments with actual and synthetic liquid waste that some amount of Ru volatilizes and transfers into condensed nitric acid solution at those phases. The nitric acid and water vapor flowing from waste tank are expected to condense at compartments of actual facilities building. The volatilized Ru could transfer into condensed liquid. It is key issues for quantifying the amount of transferred Ru through the facility building to simulate these thermodynamic and chemical behaviors. An analytical model has been proposed in this report based on the condensation mechanisms of nitric acid and water in vapor-liquid equilibria. It has been also carried out for the proposed model being feasible to formulate the activity coefficients and to review the thermodynamic properties of nitric acid solution. Practicability of the proposed analytical model has been shown successfully through the feasibility study with simulation of an experiment result. (author)

An environmentally benign three component one-pot synthesis of ...

Indian Academy of Sciences (India)

Administrator

Abstract. One pot synthesis of amidoalkyl naphthol by condensation of aromatic aldehydes, 2-naphthol and amide/urea using silicotungstic acid as a catalyst is reported. The reaction was carried out under sol- vent-free reaction conditions. The method gave good yields of amidoalkyl naphthols in short reaction time.

Bioanalysis of underivatized amino acids in non-invasive exhaled breath condensate samples using liquid chromatography coupled with tandem mass spectrometry.

Science.gov (United States)

Konieczna, Lucyna; Pyszka, Magdalena; Okońska, Magdalena; Niedźwiecki, Maciej; Bączek, Tomasz

2018-03-23

Exhaled breath condensate (EBC) is receiving increased attention as a novel, entirely non-invasive technique for collecting biomarker samples. This increased attention is due to the fact that EBC is simple, effort independent, rapid, can be repeated frequently, and can be performed on young children and patients suffering from a variety of diseases. By having a subject breathe tidally through a cooling system for 15-20 min, a sufficient amount of condensate is collected for analysis of biomarkers in clinical studies. However, bioanalysis of EBC involves an unavoidable sample preparation step due to the low concentration of its components. Thus, there is a need for a new and more sensitive analytical method of assessing EBC samples. While researchers have considered analyses of single and small quantities of amino acids - for example, those connected with leukemia - no one has previously attempted to simultaneously analyze a panel of 23 amino acids. Moreover, the present study is well-justified, as prior studies focusing on single amino acids and leukemia at the moment of diagnosis and during chemotherapy (33 days of treatment) are inconsistent. In the present study, amino acids were separated using an XBridge Amide column (3 mm × 100 mm, 3.5 μm). The mobile phase consisted of 10 mM of ammonium buffer in water with a pH of 3 (Phase A) and 10 mM ammonium buffer in acetonitrile (Phase B) under gradient program elution. The analytes were detected in electrospray positive ionization mode. Under optimal conditions, the proposed method exhibited limits of quantification (LOQ) in the range of 0.05-0.5 ng/mL, and good linearity, with the determination coefficient (R 2 ) falling between 0.9904 and 0.9998. The accuracy in human exhaled breath condensate samples ranged between 93.3-113.3% for the 23 studied amino acids, with intra- and inter-day coefficient of variation (CVs) of 0.13-9.92% and 0.17-10.53%, respectively. To demonstrate the liquid

76 FR 19087 - Energy Conservation Program for Consumer Products: Publication of the Petition for Waiver and...

Science.gov (United States)

2011-04-06

... States and Poland. BSH markets highly efficient, advanced-design condenser (non- vented) clothes dryers... design characteristic produces a more complex drying process than the regular vented dryer. Condenser... comparative data. As discussed above, the BSH condenser clothes dryer contains a design characteristic--lack...

40 CFR 63.139 - Process wastewater provisions-control devices.

Science.gov (United States)

2010-07-01

... a condenser, the design evaluation shall consider the vent stream composition, constituent... compound concentration level, design average temperature of the condenser exhaust vent stream, and the design average temperatures of the coolant fluid at the condenser inlet and outlet. (v) For a carbon...

Physicochemical Quality, Fatty Acid Composition, and Sensory Analysis of Nellore Steers Meat Fed with Inclusion of Condensed Tannin in the Diet.

Science.gov (United States)

Gesteira, Susana M; Oliveira, Ronaldo L; Silva, Thadeu M; Ribeiro, Rebeca D X; Ribeiro, Cláudio V D M; Pereira, Elzania S; Lanna, Dante P D; Pinto, Luis F B; Rocha, Tiago C; Vieira, Jusaline F; Bezerra, Leilson R

2018-05-01

This study was conducted to test the effect of dietary tannin on the fatty acid profile and sensory attributes of meat from Nellore steers. Thirty-two Nellore bull male were distributed in a completely randomized design and fed diets with condensed tannin extract as follows: 0, 10, 30, and 50 g/kg total DM basis. The physicochemical composition of the meat, lipid oxidation, fatty acid profile, flavor, tenderness, and overall acceptance were evaluated. There was a linear decrease (P ≤ 0.05) on lipid content, tenderness, cooking weight loss, myristic, palmitic, and oleic acids in meat as tannin increased in the diets. The total saturated and monounsaturated fatty acids, the atherogenicity index decreased. However, a linear increase (P ≤ 0.05) was observed for linoleic, linolenic, arachidonic, eicosapentaenoic, and docosapentaenoic acids. The physicochemical characteristic of the meat, such as moisture, ash, and protein contents, water retention capacity, final pH, Warner-Bratzler shear force, collagen, and color indexes (lightness, redness, yellowness, and chrome) did not change with dietary tannin. Also, CLA, n-6:n-3 ratio, Δ 9 -desaturase, and elongase activity were not different among diets. In conclusion, condensed tannin linearly increases unsaturated fatty acids and decreases the atherogenicity index of meat; thus, it can be recommended at the highest level (50 g/kg DM) in the diet of Nellore steers. Agriculture byproducts plays an important part in the diet of ruminant animals and consequently on food chain and has implications for the composition and quality of the livestock products (milk, meat, and eggs) that people consume. Feeding tannin to steers increases the amount of unsaturated fatty acids and meat tenderness, with a concomitant reduction on saturated fatty acids and the atherogenicity index in meat. Thus, we recommend adding tannin to steer diets to reduce the risk factors for cardiovascular diseases in red meat for human consumption. �

Management of turbidity current venting in reservoirs under different bed slopes.

Science.gov (United States)

Chamoun, Sabine; De Cesare, Giovanni; Schleiss, Anton J

2017-12-15

The lifetime and efficiency of dams is endangered by the process of sedimentation. To ensure the sustainable use of reservoirs, many sediment management techniques exist, among which venting of turbidity currents. Nevertheless, a number of practical questions remain unanswered due to a lack of systematic investigations. The present research introduces venting and evaluates its performance using an experimental model. In the latter, turbidity currents travel on a smooth bed towards the dam and venting is applied through a rectangular bottom outlet. The combined effect of outflow discharge and bed slopes on the sediment release efficiency of venting is studied based on different criteria. Several outflow discharges are tested using three different bed slopes (i.e., 0%, 2.4% and 5.0%). Steeper slopes yield higher venting efficiency. Additionally, the optimal outflow discharge leading to the largest venting efficiency with the lowest water loss increases when moving from the horizontal bed to the inclined positions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Energy condensed packaged systems. Composition, production, properties

Directory of Open Access Journals (Sweden)

Igor L. Kovalenko

2015-03-01

Full Text Available In this paper it is presented the substantiation of choice of fuel phase composition and optimal technology of emulsion production on the basis of binary solution of ammonium and calcium nitrates, which provide the obtaining of energy condensed packaged systems with specified properties. The thermal decomposition of energy condensed systems on the basis of ammonium nitrate is investigated. It is shown that the fuel phase of emulsion systems should be based on esters of polyunsaturated acids or on combinations thereof with petroleum products. And ceresin or petroleum wax can be used as the structuring additive. The influence of the technology of energy condensed systems production on the physicochemical and detonation parameters of emulsion explosives is considered. It is shown the possibility of obtaining of emulsion systems with dispersion of 1.3...1.8 microns and viscosity higher than 103 Pa∙s in the apparatus of original design. The sensitizing effect of chlorinated paraffin CP-470 on the thermolysis of energy condensed emulsion system is shown. The composition and production technology of energy condensed packaged emulsion systems of mark Ukrainit-P for underground mining in mines not dangerous on gas and dust are developed.

Are vent crab behavioral preferences adaptations for habitat choice?

Science.gov (United States)

Dahms, Hans-Uwe; Tseng, Li-Chun; Hwang, Jiang-Shiou

2017-01-01

Hydrothermal vent organisms are adapted to their extreme and patchily distributed habitats. They are expected to have evolved mechanisms that keep them in their specific habitation. Since little is known about the recruitment or habitat selection of HV organisms such as brachyurans, we examined the properties of several hydrothermal vent-associated cues on the behavior of the hydrothermal vent (HV) crab Xenograpsus testudinatus in the laboratory that were contrasted by the offering of non-vent cues. This crab species is endemic and dominates the vent fauna of Turtle Island off the NE coast of Taiwan. HV crabs were separately and in combination offered the following vent-specific cues: (1) sulfuric sediment, (3) air-bubbling, (4) elevated temperature, (5) dead settled zooplankton, (7) other crabs, and (8) shade. The non-vent-specific cues were: (2) quarz sediment, (6) dead fish, (8) light. These cues were provided on either side of a two-choice chamber. The movement of individual crabs was monitored: as initial and final choices, and as the proportion of time the crabs spent in each compartment (resident time). Cues were offered alone and no such cue as a control in the same set-up. Sulfuric sediments and dead fish were significantly more attractive to females, and other crabs irrespective of gender were significantly more attractive to males. When compared to expected distributions, crabs, irrespective of gender, significantly avoided light and tended to select other crabs, air-bubbling, sulfuric sediment, elevated temperature, dead fish, dead zooplankton, and quarz sediments in the order of decreasing importance. Data do not support the hypothesis that dead settled zooplankton was particularly attractive nor that the other gender was selected. A combination of several vent-associated cues (sulfuric sediment, elevated temperature, air-bubbling) facilitated the strongest attraction to the crabs as reflected by all response variables. The 'first choice' responses

Study on biological dosimetry of premature chromosome condensation technique

International Nuclear Information System (INIS)

Jiang Bo

2005-01-01

The premature chromosome condensation technique has been applied for biological dosimetry purpose. Premature chromo-some condensation was induced by incubating unstimulated human peripheral blood lymphocytes in the presence of okadaic acid or calyculin A (a phosphatase inhibitor) which eliminated the need for fusion with mitotic cells. It is now possible to examine the early damage induced by radiation. It is simple, exact when it combines with fluorecence in situ hybridization. (authors)

Explosive volcanism on Mercury: Analysis of vent and deposit morphology and modes of eruption

Science.gov (United States)

Jozwiak, Lauren M.; Head, James W.; Wilson, Lionel

2018-03-01

The MESSENGER mission revealed, for the first time, conclusive evidence of explosive volcanism on Mercury. Several previous works have cataloged the appearance and location of explosive volcanism on the planet using a variety of identifying characteristics, including vent presence and deposit color as seen in multispectral image mosaics. We present here a comprehensive catalog of vents of likely volcanic origin; our classification scheme emphasizes vent morphology. We have analyzed the morphologies of all vents in our catalog, and recognize three main morphologies: "simple vent", "pit vent", and "vent-with-mound". The majority of vents we identify are located within impact craters. The spatial distribution of vents does not correlate with the locations of volcanic smooth plains deposits, in contrast to the Moon, nor do vents correlate with the locations of large impact basins (except for the Caloris and Tolstoj basins). Using the degradation state of the vent host crater as a proxy for maximum age, we suggest that vent formation has been active through the Mansurian and into the Kuiperian periods, although the majority of vents were likely formed much earlier in mercurian history. The morphologies and locations of vents are used to investigate a set of plausible formation geometries. We find that the most likely and most prevalent formation geometry is that of a dike, stalled at depth, which then explosively vents to the surface. We compare the vent and deposit size of mercurian pyroclastic deposits with localized and regional lunar pyroclastic deposits, and find a range of possible eruption energies and corresponding variations in eruption style. Localized lunar pyroclastic deposits and the majority of mercurian pyroclastic deposits show evidence for eruption that is consistent with the magmatic foam at the top of a dike reaching a critical gas volume fraction. A subset of mercurian vents, including the prominent Copland-Rachmaninoff vent to the northeast of the

Blood lead levels among rural Thai children exposed to lead-acid batteries from solar energy conversion systems.

Science.gov (United States)

Swaddiwudhipong, Witaya; Tontiwattanasap, Worawit; Khunyotying, Wanlee; Sanreun, Cherd

2013-11-01

We evaluate blood lead levels among Thai children to determine if exposure to lead-acid batteries is associated with elevated blood lead levels (EBLL). We screened 254 children aged 1-14 years old from 2 rural Thai villages for blood lead levels. We also screened 18 of 92 houses in these 2 villages for the presence of environmental lead. The overall prevalence of EBLL (> or = 10 microg/dl) was 43.3% and the mean lead level among study subjects was 9.8 +/- 5.1 microg/dl. The blood lead levels significantly decreased with increasing age. Fifty point eight percent of children who lived in a house with vented lead-acid batteries had EBLL while 23.3% of children who lived in a house without vented lead-acid batteries had EBLL. Multiple logistic regression analysis revealed a significant positive association between the presence of vented lead-acid batteries and EBLL, after adjusting for other variables. Forty-two point nine percent of house floor dust samples collected near the batteries had elevated lead levels, 7.1% of house floor dust samples collected from other areas in the house had elevated lead levels and 0% of the house floor dust samples collected in houses without vented lead-acid batteries had elevated lead levels. In the sampled houses with vented lead-acid batteries, lead contamination was found in the drinking-water kept in household containers, but not in the tap water or other village sources of water. Improper care and placement of vented lead-acid batteries can result in lead contamination in the home environment causing EBLL in exposed children.

The effect of the distance between acidic site and basic site immobilized on mesoporous solid on the activity in catalyzing aldol condensation

Science.gov (United States)

Yu, Xiaofang; Yu, Xiaobo; Wu, Shujie; Liu, Bo; Liu, Heng; Guan, Jingqi; Kan, Qiubin

2011-02-01

Acid-base bifunctional heterogeneous catalysts containing carboxylic and amine groups, which were immobilized at defined distance from one another on the mesoporous solid were synthesized by immobilizing lysine onto carboxyl-SBA-15. The obtained materials were characterized by X-ray diffraction (XRD), N 2 adsorption, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron micrographs (SEM), transmission electron micrographs (TEM), elemental analysis, and back titration. Proximal-C-A-SBA-15 with a proximal acid-base distance was more active than maximum-C-A-SBA-15 with a maximum acid-base distance in aldol condensation reaction between acetone and various aldehydes. It appears that the distance between acidic site and basic site immobilized on mesoporous solid should be an essential factor for catalysis optimization.

Tank vent processing system having a corrosion preventive device

International Nuclear Information System (INIS)

Ouchi, Shoichi; Sato, Hirofumi

1987-01-01

Purpose: To prevent corrosion of a tank vent processing device by injecting an oxygen gas. Constitution: Oxygen gas and phosphorous at high temperature are poured into a tank vent processing device and amorphous oxide layers optimum to the prevention of external corrosion are formed to the inner surface of the device. Since the corrosion preventive device using the oxygen gas injection can be constituted as a relatively simple device, it is more economical than constituting a relatively large tank vent processing device with corrosion resistant stainless steels. (Kamimura, M.)

Effects of venting on wind noise levels measured at the eardrum.

Science.gov (United States)

Chung, King

2013-01-01

Wind noise can be a nuisance to hearing aid users. With the advent of sophisticated feedback reduction algorithms, people with higher degrees of hearing loss are fit with larger vents than previously allowed, and more people with lesser degrees of hearing loss are fit with open hearing aids. The purpose of this study was to examine the effects of venting on wind noise levels in the ear canal for hearing aids with omnidirectional and directional microphones. Two behind-the-ear hearing aids were programmed when they were worn on a Knowles Electronics Manikin for Acoustic Research. The hearing aid worn on the right ear was programmed to the omnidirectional microphone mode and the one on the left to the directional microphone mode. The hearing aids were adjusted to linear amplification with flat frequency response in an anechoic chamber. Gains below 10 dB were used to avoid output limiting of wind noise levels at low input levels. Wind noise samples were recorded at the eardrum location in a wind tunnel at wind velocities ranging from a gentle to a strong breeze. The hearing aids were coupled to #13 tubings (i.e., open vent), or conventional skeleton earmolds with no vent, pressure vents, or 3mm vents. Polar and spectral characteristics of wind noise were analyzed off-line using MatLab programs. Wind noise levels in the ear canals were mostly predicted by vent-induced frequency response changes in the conventional earmold conditions for both omnidirectional and directional hearing aids. The open vent condition, however, yielded the lowest levels, which could not be entirely predicted by the frequency response changes of the hearing aids. This indicated that a wind-related vent effect permitted an additional amount of sound reduction in the ear canal, which could not be explained by known vent effects. For the microphone location, form factor, and gain settings tested, open fit hearing aids yielded lower noise levels at the eardrum location than conventional behind

40 CFR 63.772 - Test methods, compliance procedures, and compliance demonstrations.

Science.gov (United States)

2010-07-01

... introduced into the flame zone. (D) For a condenser, the design analysis shall include the vent stream... design outlet organic compound concentration level, design average temperature of the condenser exhaust vent stream, and the design average temperatures of the coolant fluid at the condenser inlet and outlet...

Natural Ventilation Effectiveness of Round Wall-Mounted Vent Caps in Residential Kitchens

Directory of Open Access Journals (Sweden)

Yi-Pin Lin

2018-05-01

Full Text Available This study explores the effect of different numbers of wall-mounted vent caps and their installation locations on the indoor air environment in residential kitchens, for which limited information is available. Wind tunnel tests were performed to study the induced ventilation rates of a vent cap, and the impact of vent caps on the natural ventilation efficiency in residential kitchens was examined using computational fluid dynamics (CFD numerical simulations. The results were then applied to determine the appropriate quantity of vent caps and their proper installation location. The wind tunnel test results indicated that outdoor winds with speeds of 0–6 m/s that flow parallel to the wall with a vent cap induce indoor air to exit through the cap with ventilation rates of 0–20 m3/h; when the wind blows perpendicular to the wall, outdoor air with 0–31.9 m3/h flows indoors. CFD numerical simulations showed that the installation of kitchen vent caps can reduce the average carbon monoxide concentration in the cook’s breathing zone. A sufficient quantity of vent caps and the proper installation location are required to ensure the natural ventilation effectiveness of wall-mounted vent caps.

Gas explosion in domestic buildings. The vented gas explosion[sub][/sub

Directory of Open Access Journals (Sweden)

Tadeusz Chyży

2014-08-01

Full Text Available In this paper, the basic information, related to the so-called vented gas explosion, has been presented. The vented explosion it is an explosion, during which the destruction of the weakest elements of the structure occurs. Through the resulting holes (decompressing surfaces can flow both combustion products and non-burned gas mixture. In consequence, reduction of the maximum explosion pressure[i] P[sub]red [/sub][/i] may be significant. Often, a gas explosion occurs inside residential buildings. In this case, natural vents are window and door openings.[b]Keywords[/b]: gas, explosion, combustion, explosion vents

On the global distribution of hydrothermal vent fields: One decade later

Science.gov (United States)

Beaulieu, S. E.; Baker, E. T.; German, C. R.

2012-12-01

Since the last global compilation one decade ago, the known number of active submarine hydrothermal vent fields has almost doubled. At the end of 2009, a total of 518 active vent fields was catalogued, with about half (245) visually confirmed and others (273) inferred active at the seafloor. About half (52%) of these vent fields are at mid-ocean ridges (MORs), 25% at volcanic arcs, 21% at back-arc spreading centers (BASCs), and 2% at intra-plate volcanoes and other settings. One third are in high seas, and the nations with the most known active vent fields within EEZs are Tonga, USA, Japan, and New Zealand. The increase in known vent fields reflects a number of factors, including increased national and commercial interests in seafloor hydrothermal deposits as mineral resources. Here, we have comprehensively documented the percentage of strike length at MORs and BASCs that has been systematically explored for hydrothermal activity. As of the end of 2009, almost 30% of the ~60,000 km of MORs had been surveyed at least with spaced vertical profiles to detect hydrothermal plumes. A majority of the vents discovered at MORs in the past decade occurred at segments with vs. weighted-average full spreading rate (u_s), we predicted 676 vent fields remaining to be discovered at MORs. Even accounting for the lower F_s at slower spreading rates, almost half of the vents that are predicted remaining to be discovered at MORs are at ultra-slow to slow spreading rates (explored tend to be at high latitudes, such as the ultra-slow to slow spreading Arctic MORs (e.g., Kolbeinsey and Mohns Ridges), the ultra-slow American-Antarctic Ridge, and the intermediate spreading Pacific-Antarctic Ridge. Although a greater percentage of the ~11,000 km of BASCs has been surveyed for hydrothermal activity, the discoveries at BASCs in the past decade were mainly at segments with intermediate to fast spreading rates. Using the same equation for F_s vs. u_s, we predicted 71 vent fields remaining to

Morphological transformation of soot: investigation of microphysical processes during the condensation of sulphuric acid and limonene ozonolysis products vapours

Science.gov (United States)

Pathak, R. K. P.; Pei, X.; Hallquist, M.; Pagels, J. H.

2017-12-01

Morphological transformation of soot particle by condensation of low volatility materials on it is a dominant atmospheric process with serious implications for its optical and hygroscopic properties, and atmospheric lifetime. In this study, the morphological transformation of soot agglomerate under the influence of condensation of vapours of sulphuric acid, and/or limonene ozonolysis products were investigated systematically using a Differential Mobility Analyser-Aerosol Particle Mass Analyser (DMA-APM) and the Tandem DMA techniques integrated with a laminar flow-tube system. We discovered that the morphology transformation of soot in general was a sequence of two-step process, i.e. (i) filling of void space within soot agglomerate; (ii) growth of particle diameter. These two steps followed and complimented each other. In the very beginning the filling was the dominant process followed by growth until it led to the accumulation of enough material that in turn exerted surface forces that eventually facilitated the further filling. The filling of void space was constrained by the initial morphology of fresh soot and the nature and amount of the material condensed. This process continued in several sequential steps until all void space within the soot agglomerate was filled completely and then growth of a spherical particle continued as long as mass was condensed on it. In this study, we developed a framework to quantify the microphysical transformation of soot upon the condensation of various materials. The framework utilized experimental data and hypothesis of ideal sphere growth and filling of voids to quantify the distribution of condensed materials in these two processes complimenting each other. Using this framework, we have quantified the percentage of material that went into processes of particle growth and void filling at each step. Using the same framework, we further estimated the fraction of internal voids and open voids and used this information to derive

Visualization of the air flow behind the automotive benchmark vent

OpenAIRE

Pech, Ondřej; Jedelský, Jan; Caletka, Petr; Jícha, Miroslav

2015-01-01

Passenger comfort in cars depends on appropriate function of the cabin HVAC system. A great attention is therefore paid to the effective function of automotive vents and proper formation of the flow behind the ventilation outlet. The article deals with the visualization of air flow from the automotive benchmark vent. The visualization was made for two different shapes of the inlet channel connected to the benchmark vent. The smoke visualization with the laser knife was used. The influence of ...

Genetic diversity of archaea in deep-sea hydrothermal vent environments.

Science.gov (United States)

Takai, K; Horikoshi, K

1999-08-01

Molecular phylogenetic analysis of naturally occurring archaeal communities in deep-sea hydrothermal vent environments was carried out by PCR-mediated small subunit rRNA gene (SSU rDNA) sequencing. As determined through partial sequencing of rDNA clones amplified with archaea-specific primers, the archaeal populations in deep-sea hydrothermal vent environments showed a great genetic diversity, and most members of these populations appeared to be uncultivated and unidentified organisms. In the phylogenetic analysis, a number of rDNA sequences obtained from deep-sea hydrothermal vents were placed in deep lineages of the crenarchaeotic phylum prior to the divergence of cultivated thermophilic members of the crenarchaeota or between thermophilic members of the euryarchaeota and members of the methanogen-halophile clade. Whole cell in situ hybridization analysis suggested that some microorganisms of novel phylotypes predicted by molecular phylogenetic analysis were likely present in deep-sea hydrothermal vent environments. These findings expand our view of the genetic diversity of archaea in deep-sea hydrothermal vent environments and of the phylogenetic organization of archaea.

Vent rate of superconducting magnets during quench in the Mirror Fusion Test Facility

International Nuclear Information System (INIS)

Slack, D.S.

1979-01-01

When a superconducting magnet goes normal, resistive heating in the conductor evaporates surrounding LHe, which must be vented. The nature and speed at which the magnet goes normal and He is vented are not subject to rigorous analysis. This paper presents vent data from an existing magnet. An approximate mathematical model is derived and fitted to the data to permit scaling of vent requirements to larger size magnets. The worst case models of the vent employed in Mirror Fusion Test Facility (MFTF) cryogenic system design are also presented

The filtered venting system under construction at barseback

International Nuclear Information System (INIS)

Persson, A.H.

1985-01-01

A filter venting containment system, bearing the acronym FILTRA will be installed at the Swedish nuclear power plant Barseback. The Barseback Power Plant is owned by the Southern Sweden Power Supply (Sydkraft AB) and has two 1700-MW boiling water reactors. The reactors are of ASEA-ATOM design with pressure suppression containments (Mark IItype). The installation of the filter venting system is a condition set by the Swedish government for a continued operating license after September 1, 1986. The construction work for the FILTRA plant, the first of its kind ever planned, will be completed at the end of 1985. The FILTRA is designed so that 99.9% of the core inventory of radioactivity, excluding inert gases, is retained in the reactor containment and filter system in the event of containment venting. Another design guideline is to achieve passive functioning of the FILTRA plant during the first 24 h of an accident. The FILTRA plant is common to the two reactors on the site and consists mainly of two systems, a venting system (pressure relief system) and a filtering system. The total cost is approximately U.S. $15 million

40 CFR 63.1282 - Test methods, compliance procedures, and compliance demonstrations.

Science.gov (United States)

2010-07-01

... the vent stream is introduced into the flame zone. (D) For a condenser, the design analysis shall... temperature of the condenser exhaust vent stream, and the design average temperatures of the coolant fluid at the condenser inlet and outlet. As an alternative to the design analysis, an owner or operator may...

Pressure suppression pool hydrodynamic studies for horizontal vent exit of Indian PHWR containment

International Nuclear Information System (INIS)

Mohan, N.; Bajaj, S.S.; Saha, P.

1994-01-01

The standard Indian PHWR incorporates a pressure suppression type of containment system with a suppression pool.The design of KAPS (Kakrapar Atomic Power Station) suppression pool system adopts a modified system of downcomers having horizontal vents as compared to vertical vents of NAPS (Narora Atomic Power Station). Hydrodynamic studies for vertical vents have been reported earlier. This paper presents hydrodynamic studies for horizontal type vent system during LOCA. These studies include the phenomenon of vent clearing (where the water slug standing in downcomer initially is injected to wetwell due to rapid pressurization of drywell) followed by pool swell (elevation of pool water due to formation of bubbles due to air mass entering pool at the exit of horizontal vents from drywell). The analysis performed for vent clearing and pool swell is based on rigorous thermal hydraulic calculation consisting of conservation of air-steam mixture mass, momentum and thermal energy and mass of air. Horizontal vent of downcomer is modelled in such a way that during steam-air flow, variation of flow area due to oscillating water surface in downcomer could be considered. Calculation predicts that the vent gets cleared in about 1.0 second and the corresponding downward slug velocity in the downcomer is 4.61 m/sec. The maximum pool swell for a conservative lateral expansion is calculated to be 0.56 m. (author). 3 refs., 12 figs

The ProVent model learns to speak French.

Science.gov (United States)

Cox, Christopher E

2014-10-20

Leroy and colleagues report on the accuracy of the Prolonged Mechanical Ventilation Prognostic Model ('ProVent') in a cohort study of patients ventilated for at least 21 days in one of three hospitals in the north of France. This study is noteworthy because it is the first to describe the performance of the ProVent model both outside the US and in a community hospital-based setting.

In-stack condensible particulate matter measurement and permitting issues

International Nuclear Information System (INIS)

Corio, L.A.; Sherwell, J.

1997-01-01

Based on the results of recent epidemiological studies and assessments of the causes of visibility degradation, EPA is proposing to regulate PM2.5 emissions. PM can be classified as either filterable or condensible PM. Condensible PM includes sulfates, such as sulfuric acid. Sulfates typically account for at least half of the total dry fine PM mass in the atmosphere. Power plant SO x -based emissions make a significant contribution to ambient fine PM levels in the eastern US. Although much of this mass is derived from secondary chemical reactions in the atmosphere, a portion of this sulfate is emitted directly from stacks as condensible PM. The potential condensible PM fraction associated with coal-burning boiler emissions is somewhat uncertain. The characterization of PM emissions from these sources has been, until recently, based on in-stack filterable PM measurements only. To determine the relative magnitude of condensible PM emissions and better understand condensible PM measurement issues, a review and analysis of actual EPA Method 202 results and state-developed hybrid condensible PM methods were conducted. A review of available Method 202 results for several coal-burning boilers showed that the condensible PM, on average, comprises 60% of the total PM10. A review of recent results for state-developed measurement methods for condensible PM for numerous coal-burning boilers indicated that condensible PM accounted for, on average, approximately 49% of total PM. Caution should be exercised in the use of these results because of the seemingly unresolved issue of artifact formation, which may bias the Method 202 and state-developed methods results on the high side. Condensible PM10 measurement results and issues, and potential ramifications of including condensible PM10 emissions in the PSD permit review process are discussed. Selected power plants in Maryland are discussed as examples

Macrofauna of shallow hydrothermal vents on the Arctic Mid-Ocean Ridge at 71N

Science.gov (United States)

Schander, C.; Rapp, H. T.; Pedersen, R. B.

2007-12-01

Deep-sea hydrothermal vents are usually associated with a highly specialized fauna and since their discovery in 1977, more than 400 species of animals have been described. Specialized vent fauna includes various animal phyla, but the most conspicuous and well known are annelids, mollusks and crustaceans. We have investigated the fauna collected around newly discovered hydrothermal vents on the Mohns Ridge north of Jan Mayen. The venting fields are located at 71°N and the venting takes place within two main areas separated by 5 km. The shallowest vent area is at 500-550 m water depth and is located at the base of a normal fault. This vent field stretches approximately 1 km along the strike of the fault, and it is composed of 10-20 major vent sites each with multiple chimney constructions discharging up to 260°C hot fluids. A large area of diffuse, low- temperature venting occurs in the area surrounding the high-temperature field. Here, partly microbial mediated iron-oxide-hydroxide deposits are abundant. The hydrothermal vent sites do not show any high abundance of specialized hydrothermal vent fauna. Single groups (i.e. Porifera and Mollusca) have a few representatives but groups otherwise common in hydrothermal vent areas (e.g. vestimentifera, Alvinellid worms, mussels, clams, galathaeid and brachyuran crabs) are absent. Up until now slightly more than 200 species have been identified from the vent area. The macrofauna found in the vent area is, with few exceptions, an assortment of bathyal species known in the area. One endemic, yet undescribed, species of mollusc has been found so far, an gastropod related to Alvania incognita Warén, 1996 and A. angularis Warén, 1996 (Rissoidae), two species originally described from pieces of sunken wood north and south of Iceland. It is by far the most numerous mollusc species at the vents and was found on smokers, in the bacterial mats, and on the ferric deposits. A single specimen of an undescribed tanaidacean has also

CONDENSATION OF WATER VAPOR IN A VERTICAL TUBE CONDENSER

Directory of Open Access Journals (Sweden)

Jan Havlík

2015-10-01

Full Text Available This paper presents an analysis of heat transfer in the process of condensation of water vapor in a vertical shell-and-tube condenser. We analyze the use of the Nusselt model for calculating the condensation heat transfer coefficient (HTC inside a vertical tube and the Kern, Bell-Delaware and Stream-flow analysis methods for calculating the shell-side HTC from tubes to cooling water. These methods are experimentally verified for a specific condenser of waste process vapor containing air. The operating conditions of the condenser may be different from the assumptions adopted in the basic Nusselt theory. Modifications to the Nusselt condensation model are theoretically analyzed.

14 CFR 34.11 - Standard for fuel venting emissions.

Science.gov (United States)

2010-01-01

... Emissions (New and In-Use Aircraft Gas Turbine Engines) § 34.11 Standard for fuel venting emissions. (a) No fuel venting emissions shall be discharged into the atmosphere from any new or in-use aircraft gas... include one of the following: (1) Incorporation of an FAA-approved system that recirculates the fuel back...

Pito Seamount revisited: the discovery and mapping of new black smoker vents

Science.gov (United States)

Cheadle, M. J.; John, B. E.; German, C. R.; Gee, J. S.; Coogan, L. A.; Gillis, K. M.; Swapp, S.

2017-12-01

In February 2017, the RV Atlantis PMaG (PaleoMagnetism and Gabbro) cruise re-visited a black smoker site originally discovered 24 years ago on Pito Seamount, by the submersible Nautile during the French Pito expedition (1993). Pito Seamount (111.639oW, 23.333oS) marks the northern tip of the propagating East Pacific Rise, bounding the east side of the Easter Microplate. There the seafloor rises to 2250mbsl and has a 900m wide, 50m deep axial valley, which hosts at least two separate fields of active hydrothermal vents. AUV Sentry mapping of the summit of Pito seamount (0.5-1m resolution) highlights over 50 active and inactive chimneys amid recent basaltic sheet flows, pillow mounds and ponded lava. The vents occur in two fields/sub-fields; the first covers an area of 800 x 200m, and lies parallel to the ridge axis, along incipient faults forming on the northeastern flank of the axial valley. The second field occurs in a 250m diameter area in the centre of the axial valley. Jason II dive 961 visited, sampled, measured vent orifice temperatures, and acquired 4k video of the chimneys, and re-discovered the active (Magnificent Village) vent first found by Nautile, in the now named Nautile vent field, together with five additional active hydrothermal vents (Jason, Medea, Sentry, Abe and Scotty's Castle). The Magnificent Village, the largest active vent, is 25m tall and has multiple active spires in three main groups surrounding a hollow amphitheater. Measured vent orifice temperatures ranged from 338oC (Magnificent Village) to 370oC (Jason). The vents host a fauna of alvinellid worms, bythograidid crabs, alvincardid shrimps, phymorhynchus gastropods, Corallimorphid anenomes and bathymodiolid mussels, but no vestimentiferan worms. Brisingid brittle stars colonize inactive chimneys.

A bestiary of ordinary vent activities at Stromboli (and what it tells us about vent conditions)

Science.gov (United States)

Gaudin, Damien; Taddeucci, Jacopo; Scarlato, Piergiorgio

2015-04-01

Normal active degassing at Stromboli (Aeolian Islands, Italy) is traditionally divided in two classes. Puffing correspond to the frequent (~1 Hz) release of small gas pockets (0.5 - 1 m of diameter) at low exit velocities (5 - 15 m/s). Whereas, Strombolian explosions occur at a frequency of 1 - 10 per hour, and are characterized the ejection of bombs and/or ash at high velocities (50 - 400 m/s). In order to get a broader overview of two types of degassing, we used a thermal high speed FLIR SC655 camera to monitor the temperature anomalies generated by the expelled gas, ash, and/or bombs. The enhanced time and spatial resolutions of the camera (200 frames per second, 15 cm wide pixels) enables to use numerical algorithms to distinguish and characterize individual ejection events. In particular, for each explosion and puff, we compute the temperature, the volume, the exit point and the rise velocities of the expelled material. These values, as well as the frequency of the release events, are used to portray a total of 12 vent activities, observed during three field campaigns in 2012, 2013 and 2014. Sustained puffing was visible on 7 cases, with an intensity ranging on at least two orders of magnitude. Although the released gas volume is sometimes highly variable, on some cases, constant sized puffs allows to define a typical discharge frequency ranging between 0.4 and 1.5 Hz. Regular Strombolian explosions, with various duration, intensity and ash contents, are reported in 6 cases, 2 of them simultaneously presenting a puffing activity. In some cases, we noticed modifications of the vent activity just before the explosions. These precursors, usually lasting about 1 second but occasionally reaching 10 seconds, can be sorted into 1) increase of the puffing activity ; 2) emission of gas plumes ; 3) inflation of the visible vent surface. Finally, one vent activity was hybrid between puffing and Strombolian explosions, with frequent explosions (1 Hz) ejecting numerous

A New Approach to Uncertainty Reduction in Launch Vehicle Compartment Venting

Data.gov (United States)

National Aeronautics and Space Administration — Launch vehicle compartments are vented to the external environment during ascent to minimize undesirable structural loading. Prediction of venting performance is an...

E-njoy the first CERN Global Network e-vent!

CERN Multimedia

CERN Bulletin

2010-01-01

Empowered by the considerable interest it received after it was launched, the CERN Global Network takes off and organizes the first e-vent, which will be a special talk on science communication that will be held on 29 June at 4.30 p.m. in the Council Chamber. You can experience it live on the Global Network site and, if you are a Member, provide feedback. Stay linked!   On the CERN Global Network webpage, you will be able to choose the topic of the next e-vents. Seven weeks after its launch, about 600 people have already joined the CERN Global Network and six thematic groups have been created. The whole idea of joining the Network is to stay connected or reconnect with life at CERN where seminars, talks and discussions are undoubtedly a very important and much appreciated part of it. This is where the e-vents come into play. “The e-vents enable members of the Global Network to participate in selected events taking place at CERN, such as lectures or panel discussions. They will...

Hydrothermal Vents and Methane Seeps: Rethinking the Sphere of Influence

Directory of Open Access Journals (Sweden)

Lisa Ann Levin

2016-05-01

Full Text Available Although initially viewed as oases within a barren deep ocean, hydrothermal vent and methane seep communities are now recognized to interact with surrounding ecosystems on the sea floor and in the water column, and to affect global geochemical cycles. The importance of understanding these interactions is growing as the potential rises for disturbance from oil and gas extraction, seabed mining and bottom trawling. Here we synthesize current knowledge of the nature, extent and time and space scales of vent and seep interactions with background systems. We document an expanded footprint beyond the site of local venting or seepage with respect to elemental cycling and energy flux, habitat use, trophic interactions, and connectivity. Heat and energy are released, global biogeochemical and elemental cycles are modified, and particulates are transported widely in plumes. Hard and biotic substrates produced at vents and seeps are used by benthic background fauna for attachment substrata, shelter, and access to food via grazing or through position in the current, while particulates and fluid fluxes modify planktonic microbial communities. Chemosynthetic production provides nutrition to a host of benthic and planktonic heterotrophic background species through multiple horizontal and vertical transfer pathways assisted by flow, gamete release, animal movements, and succession, but these pathways remain poorly known. Shared species, genera and families indicate that ecological and evolutionary connectivity exists among vents, seeps, organic falls and background communities in the deep sea; the genetic linkages with inactive vents and seeps and background assemblages however, are practically unstudied. The waning of venting or seepage activity generates major transitions in space and time that create links to surrounding ecosystems, often with identifiable ecotones or successional stages. The nature of all these interactions is dependent on water depth, as

Hydrothermal vents and methane seeps: Rethinking the sphere of influence

Science.gov (United States)

Levin, Lisa A.; Baco, Amy; Bowden, David; Colaco, Ana; Cordes, Erik E.; Cunha, Marina; Demopoulos, Amanda W.J.; Gobin, Judith; Grupe, Ben; Le, Jennifer; Metaxas, Anna; Netburn, Amanda; Rouse, Greg; Thurber, Andrew; Tunnicliffe, Verena; Van Dover, Cindy L.; Vanreusel, Ann; Watling, Les

2016-01-01

Although initially viewed as oases within a barren deep ocean, hydrothermal vent and methane seep communities are now recognized to interact with surrounding ecosystems on the sea floor and in the water column, and to affect global geochemical cycles. The importance of understanding these interactions is growing as the potential rises for disturbance from oil and gas extraction, seabed mining and bottom trawling. Here we synthesize current knowledge of the nature, extent and time and space scales of vent and seep interactions with background systems. We document an expanded footprint beyond the site of local venting or seepage with respect to elemental cycling and energy flux, habitat use, trophic interactions, and connectivity. Heat and energy are released, global biogeochemical and elemental cycles are modified, and particulates are transported widely in plumes. Hard and biotic substrates produced at vents and seeps are used by “benthic background” fauna for attachment substrata, shelter, and access to food via grazing or through position in the current, while particulates and fluid fluxes modify planktonic microbial communities. Chemosynthetic production provides nutrition to a host of benthic and planktonic heterotrophic background species through multiple horizontal and vertical transfer pathways assisted by flow, gamete release, animal movements, and succession, but these pathways remain poorly known. Shared species, genera and families indicate that ecological and evolutionary connectivity exists among vents, seeps, organic falls and background communities in the deep sea; the genetic linkages with inactive vents and seeps and background assemblages however, are practically unstudied. The waning of venting or seepage activity generates major transitions in space and time that create links to surrounding ecosystems, often with identifiable ecotones or successional stages. The nature of all these interactions is dependent on water depth, as well as

Preventing freezing of condensate inside tubes of air cooled condenser

International Nuclear Information System (INIS)

Joo, Jeong A; Hwang, In Hwan; Lee, Dong Hwan; Cho, Young Il

2012-01-01

An air cooled condenser is a device that is used for converting steam into condensate by using ambient air. The air cooled condenser is prone to suffer from a serious explosion when the condensate inside the tubes of a heat exchanger is frozen; in particular, tubes can break during winter. This is primarily due to the structural problem of the tube outlet of an existing conventional air cooled condenser system, which causes the backflow of residual steam and noncondensable gases. To solve the backflow problem in such condensers, such a system was simulated and a new system was designed and evaluated in this study. The experimental results using the simulated condenser showed the occurrence of freezing because of the backflow inside the tube. On the other hand, no backflow and freezing occurred in the advanced new condenser, and efficient heat exchange occurred

Condensate subcooling near tube exit during horizontal in-tube condensation

International Nuclear Information System (INIS)

Hashizume, K.; Abe, N.; Ozeki, T.

1992-01-01

In-tube condensation is encountered in various applications for heat exchangers, such as domestic air-conditioning equipment, industrial air-cooled condensers, and moisture separator reheaters (MSRs) for nuclear power pants. Numerous research work has been conducted to predict the condensation heat transfer coefficient, and we have now enough information for thermal design of heat exchangers with horizontal in-tube condensation. Most of the research is analytical and/or experimental work in the annular or stratified flow regime, or experimental work on bulk condensation, i.e., from saturated vapor to complete condensation. On the other hand, there exist few data about the heat transfer phenomena in the very lower-quality region near the tube exit. The purpose of this paper is to clarify the condensation heat transfer phenomena near the tube exit experimentally and analytically, and to predict the degree of condensate subcooling

Spatial scaling of bacterial community diversity at shallow hydrothermal vents: a global comparison

Science.gov (United States)

Pop Ristova, P.; Hassenrueck, C.; Molari, M.; Fink, A.; Bühring, S. I.

2016-02-01

Marine shallow hydrothermal vents are extreme environments, often characterized by discharge of fluids with e.g. high temperatures, low pH, and laden with elements toxic to higher organisms. They occur at continental margins around the world's oceans, but represent fragmented, isolated habitats of locally small areal coverage. Microorganisms contribute the main biomass at shallow hydrothermal vent ecosystems and build the basis of the food chain by autotrophic fixation of carbon both via chemosynthesis and photosynthesis, occurring simultaneously. Despite their importance and unique capacity to adapt to these extreme environments, little is known about the spatial scales on which the alpha- and beta-diversity of microbial communities vary at shallow vents, and how the geochemical habitat heterogeneity influences shallow vent biodiversity. Here for the first time we investigated the spatial scaling of microbial biodiversity patterns and their interconnectivity at geochemically diverse shallow vents on a global scale. This study presents data on the comparison of bacterial community structures on large (> 1000 km) and small (0.1 - 100 m) spatial scales as derived from ARISA and Illumina sequencing. Despite the fragmented global distribution of shallow hydrothermal vents, similarity of vent bacterial communities decreased with geographic distance, confirming the ubiquity of distance-decay relationship. Moreover, at all investigated vents, pH was the main factor locally structuring these communities, while temperature influenced both the alpha- and beta-diversity.

Visualization of the air flow behind the automotive benchmark vent

Science.gov (United States)

Pech, Ondrej; Jedelsky, Jan; Caletka, Petr; Jicha, Miroslav

2015-05-01

Passenger comfort in cars depends on appropriate function of the cabin HVAC system. A great attention is therefore paid to the effective function of automotive vents and proper formation of the flow behind the ventilation outlet. The article deals with the visualization of air flow from the automotive benchmark vent. The visualization was made for two different shapes of the inlet channel connected to the benchmark vent. The smoke visualization with the laser knife was used. The influence of the shape of the inlet channel to the airflow direction, its enlargement and position of air flow axis were investigated.

Visualization of the air flow behind the automotive benchmark vent

Directory of Open Access Journals (Sweden)

Pech Ondrej

2015-01-01

Full Text Available Passenger comfort in cars depends on appropriate function of the cabin HVAC system. A great attention is therefore paid to the effective function of automotive vents and proper formation of the flow behind the ventilation outlet. The article deals with the visualization of air flow from the automotive benchmark vent. The visualization was made for two different shapes of the inlet channel connected to the benchmark vent. The smoke visualization with the laser knife was used. The influence of the shape of the inlet channel to the airflow direction, its enlargement and position of air flow axis were investigated.

Arsenic speciation in food chains from mid-Atlantic hydrothermal vents

Science.gov (United States)

Taylor, Vivien F.; Jackson, Brian P.; Siegfried, Matthew R.; Navratilova, Jana; Francesconi, Kevin A.; Kirshtein, Julie; Voytek, Mary

2012-01-01

Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata, the vent chimney-dwelling mussel, Bathymodiolus azoricus, Branchipolynoe seepensis, a commensal worm of B. azoricus and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ13C and δ15N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata, whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a foodweb without algae or other photosynthetic life.

Arsenic speciation in food chains from mid-Atlantic hydrothermal vents.

Science.gov (United States)

Taylor, Vivien F; Jackson, Brian P; Siegfried, Matthew; Navratilova, Jana; Francesconi, Kevin A; Kirshtein, Julie; Voytek, Mary

2012-05-04

Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata , the vent chimney-dwelling mussel, Bathymodiolus azoricus , Branchipolynoe seepensis , a commensal worm of B. azoricus , and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ 13 C and δ 15 N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata , whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate, and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys, covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a food web without algae or other photosynthetic life.

Toward an integrated genetic model for vent-distal SEDEX deposits

Science.gov (United States)

Sangster, D. F.

2018-04-01

Although genetic models have been proposed for vent-proximal SEDEX deposits, an equivalent model for vent-distal deposits has not yet appeared. In view of this, it is the object of this paper to present a preliminary integrated vent-distal genetic model through exploration of four major components: (i) nature of the ore-forming fluid, (ii) role of density of the unconsolidated host sediments, (iii) dynamics of sulfate reduction and (iv) depositional environment. Two sub-groups of SEDEX Pb-Zn deposits, vent-proximal and vent-distal, are widely recognized today. Of the two, the latter is by far the largest in terms of metal content with each of the 13 largest containing in excess of 7.5 M (Zn+Pb) metal. In contrast, only one vent-proximal deposit (Sullivan) falls within this size range. Vent-proximal deposits are characteristically underlain by local networks of sulfide-filled veins (commonly regarded as feeder veins) surrounded by a discordant complex of host rock alteration. These attributes are missing in vent-distal deposits, which has led to the widespread view that vent-distal ore-forming fluids have migrated unknown distances away from their vent sites. Because of the characteristic fine grain size of ore minerals, critical fluid inclusion data are lacking for vent-distal ore-stage sulfides. Consequently, hypothetical fluids such as those which formed MVT deposits (120 °C, 20% NaCl equiv.) are considered to represent vent-distal fluids as well. Such high-salinity fluids are capable of carrying significant concentrations of Pb and Zn as chloride complexes while the relatively low temperatures preclude high Cu contents. Densities of such metalliferous brines result in bottom-hugging fluids that collect in shallow saucer-shaped depressions (collector basins). Lateral metal zoning in several deposits reveals the direction from which the brines came. Relative densities of the ore-forming fluid and sediment determine whether the ore-forming fluid stabilizes on top

40 CFR 63.113 - Process vent provisions-reference control technology.

Science.gov (United States)

2010-07-01

... § 63.113 Process vent provisions—reference control technology. (a) The owner or operator of a Group 1... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Process vent provisions-reference control technology. 63.113 Section 63.113 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...

40 CFR 63.1322 - Batch process vents-reference control technology.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Batch process vents-reference control technology. 63.1322 Section 63.1322 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Batch process vents—reference control technology. (a) Batch process vents. The owner or operator of a...

A numerical study of the effect of vent flow angle on the heat transfer rate from a cold window with a below-window hot-air vent

Energy Technology Data Exchange (ETDEWEB)

Oosthuizen, P.H. [Queen' s Univ., Kingston, ON (Canada). Dept. of Mechanical and Materials Engineering

2010-07-01

This study investigated the effects of the discharge angle on air leaving a hot air vent mounted below a window. The window was represented by a plane isothermal section recessed into a wall and was colder than air in the rest of the room. The vent was placed against the wall and had a uniform discharge velocity. Flow was assumed to be steady. Both laminar and turbulent flows were evaluated using a commercial computational fluid dynamics (CFD) simulation tool. A k-epsilon turbulence model was used to determine turbulent flow calculations. The study determined the Rayleigh number based on window height, the Reynolds number based on the vent discharge velocity, the angle of the vent discharge flow, the Prandtl number, and dimensionless vent discharge temperature differences. The study showed that a relatively thin layer of cold air adjacent to the floor is present at high Rayleigh numbers, where the downward natural convective flow over the window dominates the overall flow. At low Rayleigh numbers, the cold air flows upward towards the ceiling and temperatures in the room are nearly uniform. 47 refs., 11 figs.

Geophysical Signatures of cold vents on the northern Cascadia margin

Science.gov (United States)

Riedel, M.; Paull, C. K.; Spence, G.; Hyndman, R. D.; Caress, D. W.; Thomas, H.; Lundsten, E.; Ussler, W.; Schwalenberg, K.

2009-12-01

The accretionary prism of the northern Cascadia margin is a classic gas hydrate research area. Ocean Drilling Program Leg 146 and Integrated Ocean Drilling Program (IODP) Expedition 311 documented that gas hydrate is widely distributed across the margin. In recent years an increased research focus has been on cold vents, where methane gas is actively released. Two recent expeditions funded by the Monterey Bay Aquarium Research Institute (MBARI) were conducted in the area of IODP Sites U1327 and U1328. An autonomous underwater vehicle (AUV) was used to map the seafloor bathymetry followed by dives with the ROV Doc Ricketts for ground truth information of various seafloor morphological features identified. The two cruises revealed many new seafloor features indicative of methane venting that were previously unknown. Bullseye Vent (BV) has been extensively studied using seismic imaging, piston coring, heat-flow, controlled-source EM, and deep drilling. BV is seismically defined by a circular wipe-out zone but the new AUV data show that BV is rather an elongated depression. BV is associated with a shoaling in the BSR, but lacks evidence for the existence of an underlying fault in the previous data. Although a massive gas-hydrate plug was encountered within the top 40 mbsf in the IODP holes, the ROV observations only revealed some platy methane derived carbonate outcrops at the outer-most rim of the depressions, a few beds of Vesicomya clams, and no observed gas vents, which together do not indicate that BV is especially active now. Further northeast of BV, but along the same trend, active gas venting was found associated with seafloor blistering and bacterial mats suggesting that there is an underlying fault system providing a fluid flow conduit. The newly discovered vent area has few seismic line crossings; however the available seismic data surprisingly are not associated with wipe-out zones. Another prominent fault-related gas vent also was investigated during the

Emergency venting of pressure vessels

International Nuclear Information System (INIS)

Steinkamp, H.

1995-01-01

With the numerical codes developed for safety analysis the venting of steam vessel can be simulated. ATHLET especially is able to predict the void fraction depending on the vessel height. Although these codes contain a one-dimensional model they allow the description of complex geometries due to the detailed nodalization of the considered apparatus. In chemical reactors, however, the venting process is not only influenced by the flashing behaviour but additionally by the running chemical reaction in the vessel. Therefore the codes used for modelling have to consider the kinetics of the chemical reaction. Further multi-component systems and dissolving processes have to be regarded. In order to preduct the fluid- and thermodynamic process it could be helpful to use 3-dimensional codes in combination with the one-dimensional codes as used in nuclear industry to get a more detailed describtion of the running processes. (orig./HP)

Laboratory study of the effect of oxalic acid on the cloud condensation nuclei activity of mineral dust aerosol

Science.gov (United States)

Gierlus, Kelly M.; Laskina, Olga; Abernathy, Tricia L.; Grassian, Vicki H.

2012-01-01

Dicarboxylic acids, which make up a significant portion of the atmospheric organic aerosol, are emitted directly through biomass burning as well as produced through the oxidation of volatile organic compounds. Oxalic acid, the most abundant of the dicarboxylic acids, has been shown by recent field studies to be present in mineral dust aerosol particles. The presence of these internally mixed organic compounds can alter the water absorption and cloud condensation nuclei (CCN) abilities of mineral particles in the Earth's atmosphere. The University of Iowa's Multi-Analysis Aerosol Reactor System ( MAARS) was used to measure the CCN activity of internally mixed particles that were generated from a mixture of either calcite or polystyrene latex spheres (PSLs) in an aqueous solution of oxalic acid. Although PSL is not a mineral dust component, it is used here as a non-reactive, insoluble particle. CCN measurements indicate that the internally mixed oxalate/calcite particles showed nearly identical CCN activity compared to the original calcite particles whereas oxalic acid/PSL internally mixed particles showed much greater CCN activity compared to PSL particles alone. This difference is due to the reaction of calcite with oxalic acid, which produces a relatively insoluble calcium oxalate coating on the particle surface and not a soluble coating as it does on the PSL particle. Our results suggest that atmospheric processing of mineral dust aerosol through heterogeneous processes will likely depend on the mineralogy and the specific chemistry involved. Increase in the CCN activity by incorporation of oxalic acid are only expected for unreactive insoluble dust particles that form a soluble coating.

Analysis of sound absorption performance of an electroacoustic absorber using a vented enclosure

Science.gov (United States)

Cho, Youngeun; Wang, Semyung; Hyun, Jaeyub; Oh, Seungjae; Goo, Seongyeol

2018-03-01

The sound absorption performance of an electroacoustic absorber (EA) is primarily influenced by the dynamic characteristics of the loudspeaker that acts as the actuator of the EA system. Therefore, the sound absorption performance of the EA is maximum at the resonance frequency of the loudspeaker and tends to degrade in the low-frequency and high-frequency bands based on this resonance frequency. In this study, to adjust the sound absorption performance of the EA system in the low-frequency band of approximately 20-80 Hz, an EA system using a vented enclosure that has previously been used to enhance the radiating sound pressure of a loudspeaker in the low-frequency band, is proposed. To verify the usefulness of the proposed system, two acoustic environments are considered. In the first acoustic environment, the vent of the vented enclosure is connected to an external sound field that is distinct from the sound field coupled to the EA. In this case, the acoustic effect of the vented enclosure on the performance of the EA is analyzed through an analytical approach using dynamic equations and an impedance-based equivalent circuit. Then, it is verified through numerical and experimental approaches. Next, in the second acoustic environment, the vent is connected to the same external sound field as the EA. In this case, the effect of the vented enclosure on the EA is investigated through an analytical approach and finally verified through a numerical approach. As a result, it is confirmed that the characteristics of the sound absorption performances of the proposed EA system using the vented enclosure in the two acoustic environments considered in this study are different from each other in the low-frequency band of approximately 20-80 Hz. Furthermore, several case studies on the change tendency of the performance of the EA using the vented enclosure according to the critical design factors or vent number for the vented enclosure are also investigated. In the future

Researches of a thermodynamic behaviour of bubbling vacuum system bubble condenser NPP 'Mochovce'

International Nuclear Information System (INIS)

Rjeznikov, Iu.V.; Lifshitz, E.V.; Kouznetsov, M.V.; Antropov, V. N.; Doulepov, U. N.; Suchanek, M.

1997-01-01

During joint development and designing of the bubbling vacuum system (BVS) equipment for localization of under-loss of coolant accident (LOCA) consequences on NPPs with WWER 440/213, a large volume of experimental and calculational activities have been performed by VTI and SverdNIIchimmash for the substantiation of functionality of this system, and in particular, for bubbler-condenser (BC) design, as a part of BVS. However, not looking on broad introduction of BVS on 16-th NPP units with WWER 440/213, its functionality was subjected to a doubt from experts of different countries. Sequentially, that promoted issue of the IAEA, document and OECD document. Therefore, before commissioning of the NPP 'Mochovce' unit 1 it was decided to execute additional experimental and computational researches for Safety Analysis Report preparation. Within the framework of these BVS thermodynamic behavior researches, in particular the following problems were chosen: (1) The check of a capability of valves DN 250 blocking in an opened position, as a result of return pressure differential on BC, during vent clearing process of the hydro-lock, that can sequentially result in an a drop of efficiency of stem condensation in BC pool; (2) To provide by direct measurements the absence of pressure oscillations dangerous for strength of a BC design in different modes of steam condensation in BC and to execute computational researches of instability of steam condensation processes (for such mode as 'chugging'); (3) Study influences of pool swell and water carry over through check valves DN 500 in the air traps on a BVS functionality; (4) To determine by a computational way the maximum pressure in NPP premises during LOCA, with taking into consideration additional failures of the BC equipment: absence of a water on two and more BC plates and DN 250 valves have blocked in an opened position (conservative conditions). (authors)

40 CFR 63.765 - Glycol dehydration unit process vent standards.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Glycol dehydration unit process vent... Facilities § 63.765 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

40 CFR 63.1275 - Glycol dehydration unit process vent standards.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Glycol dehydration unit process vent... Facilities § 63.1275 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

Generating debate on issues surrounding the venting of containment in the event of LOCA to ensure an optimised safe outcome

International Nuclear Information System (INIS)

Chadwick, Chris; Jahouel, Xavier; Swain, Adam

2014-01-01

accommodation/removal, maximum temperature limitations in terms of metallurgy and the melting point of deposited materials (for instance, the melting of CsOH at 273 Celsius) as well the consequences of water condensation on pressure loss, solids removal efficiency and the blinding of the medium, and the structural design of the equipment to make it capable of withstanding the worst case pressure loss (a fully blocked system with full containment pressure across it). Extensive work done in the author's company shows clearly that no two event models coincide, to the extent that the company is concerned that there is an assumption in the NPP industry that a 'product' exists which will simply meet any need, taking account of solids load, temperature limits, pressure profiles, decay heat deposition and the gross condensation of water vapour. It is clear, and will be demonstrated, that no single catch-all solution will meet the myriad of needs examined by the company, and the company finds itself in a position where it feels it is compelled to at least present the argument to the industry, so that the industry can then at least have its deliberations informed by supported and fundamental fact. The purpose of the paper is to (hopefully) generate debate to ensure that solutions being provided to meet this most challenging and important of applications, meet the real need, and that the real need is properly modelled. The company has worked on several CV applications in the past years and can say with certainty that no two have been at all similar, suggesting that either the event modelling is wrong, or 'One Size Fits All' is definitely not the case where Containment Venting is concerned. (authors)

Effect of condensation product on electrodeposition of zinc on mild ...

Indian Academy of Sciences (India)

WINTEC

Abstract. Electrodeposition of zinc on steel was obtained from acid chloride bath containing condensation products (CP) of 3,4 ..... nucleation number and hence smaller grain size. The ... thesis, Bangalore University, Bangalore. Venkatesha ...

Abiotic condensation synthesis of glyceride lipids and wax esters under simulated hydrothermal conditions.

Science.gov (United States)

Rushdi, Ahmed I; Simoneit, Bernd R T

2006-04-01

Precursor compounds for abiotic proto cellular membranes are necessary for the origin of life. Amphipathic compounds such as fatty acids and acyl glycerols are important candidates for micelle/bilayer/vesicle formation. Two sets of experiments were conducted to study dehydration reactions of model lipid precursors in aqueous media to form acyl polyols and wax esters, and to evaluate the stability and reactions of the products at elevated temperatures. In the first set, mixtures of n-nonadecanoic acid and ethylene glycol in water, with and without oxalic acid, were heated at discrete temperatures from 150 ( composite function)C to 300 ( composite function)C for 72 h. The products were typically alkyl alkanoates, ethylene glycolyl alkanoates, ethylene glycolyl bis-alkanoates and alkanols. The condensation products had maximum yields between 150 ( composite function)C and 250 ( composite function)C, and were detectable and thus stable under hydrothermal conditions to temperatures acid and glycerol were heated using the same experimental conditions, with and without oxalic acid, between 100 ( composite function)C and 250 ( composite function)C. The main condensation products were two isomers each of monoacylglycerols and diacylglycerols at all temperatures, as well as minor amounts of the fatty acid anhydride and methyl ester. The yield of glyceryl monoheptanoates generally increased with increasing temperature and glyceryl diheptanoates decreased noticeably with increasing temperature. The results indicate that condensation reactions and abiotic synthesis of organic lipid compounds under hydrothermal conditions occur easily, provided precursor concentrations are sufficiently high.

Experimental investigation on No-Vent Fill (NVF) process using liquid Nitrogen

International Nuclear Information System (INIS)

Kim, Young Cheol; Seo, Man Su; Yoo, Dong Gyu; Jeong, Sang Kwon

2014-01-01

For a long-term space mission, filling process of cryogenic liquid propellant is operated on a space vehicle in space. A vent process during transfer and filling of cryogenic propellant is needed to maintain the fuel tank pressure at a safe level due to its volatile characteristic. It is possible that both liquid and vapor phases of the cryogenic propellant are released simultaneously to outer space when the vent process occurs under low gravity environment. As a result, the existing filling process with venting not only accompanies wasting liquid propellant, but also consumes extra fuel to compensate for the unexpected momentum originated from the vent process. No-Vent Fill (NVF) method, a filling procedure without a venting process of cryogenic liquid propellant, is an attractive technology to perform a long-term space mission. In this paper, the preliminary experimental results of the NVF process are described. The experimental set-up consists of a 9-liter cryogenic liquid receiver tank and a supply tank. Liquid nitrogen (LN2) is used to simulate the behavior of cryogenic propellant. The whole situation in the receiver tank during NVF is monitored. The major experimental parameter in the experiment is the mass flow rate of the liquid nitrogen. The experimental results demonstrate that as the mass flow rate is increased, NVF process is conducted successfully. The quality and the inlet temperature of the injected LN2 are affected by the mass flow rate. These parameters determine success of NVF.

Analysis of containment venting for the Peach Bottom Atomic Power Station

International Nuclear Information System (INIS)

Hanson, D.J.; Wright, R.E.; Jenkins, J.P.

1986-01-01

The effectiveness of containment venting as a means of preventing or mitigating the consequences of severe accidents was evaluated for Peach Bottom Atomic Power Station Units 2 and 3 (BWR-4s with Mark I containments). Results from this evaluation indicate that the effectiveness of venting in preventing containment failure is highly dependent on the severe accident sequence. Containment venting can be effective for several classes of sequences, including loss-of-coolant accidents with breaks in the containment and transients with a failure of containment heat removal. However, based on draft procedures and equipment in place at the time of the evaluation, containment venting has limited potential for further reducing the risk associated with several sequences currently identified as significant contributors to risk. Means of improving the potential for risk reduction were identified, but their influence on risk was not analyzed

Degassing during magma ascent in the Mule Creek vent (USA)

Science.gov (United States)

Stasiuk, M.V.; Barclay, J.; Carroll, M.R.; Jaupart, Claude; Ratte, J.C.; Sparks, R.S.J.; Tait, S.R.

1996-01-01

The structures and textures of the rhyolite in the Mule Creek vent (New Mexico, USA) indicate mechanisms by which volatiles escape from silicic magma during eruption. The vent outcrop is a 300-m-high canyon wall comprising a section through the top of a feeder conduit, vent and the base of an extrusive lava dome. Field relations show that eruption began with an explosive phase and ended with lava extrusion. Analyses of glass inclusions in quartz phenocrysts from the lava indicate that the magma had a pre-eruptive dissolved water content of 2.5-3.0 wt% and, during eruption, the magma would have been water-saturated over the vertical extent of the present outcrop. However, the vesicularity of the rhyolite is substantially lower than that predicted from closed-system models of vesiculation under equilibrium conditions. At a given elevation in the vent, the volume fraction of primary vesicles in the rhyolite increases from zero close to the vent margin to values of 20-40 vol.% in the central part. In the centre the vesicularity increases upward from approximately 20 vol.% at 300 m below the canyon rim to approximately 40 vol.% at 200 m, above which it shows little increase. To account for the discrepancy between observed vesicularity and measured water content, we conclude that gas escaped during ascent, probably beginning at depths greater than exposed, by flow through the vesicular magma. Gas escape was most efficient near the vent margin, and we postulate that this is due both to the slow ascent of magma there, giving the most time for gas to escape, and to shear, favouring bubble coalescence. Such shear-related permeability in erupting magma is supported by the preserved distribution of textures and vesicularity in the rhyolite: Vesicles are flattened and overlapping near the dense margins and become progressively more isolated and less deformed toward the porous centre. Local zones have textures which suggest the coalescence of bubbles to form permeable

Containment venting as a mitigation technique for BWR MARK I plant ATWS

International Nuclear Information System (INIS)

Harrington, R.M.

1987-01-01

Containment venting is studied as a mitigation strategy for preventing or delaying severe fuel damage following hypothetical BWR Anticipated Transient Without Scram (ATWS) accidents initiated by MSIV-closure, and compounded by failure of the Standby Liquid Control (SLC) system injection of sodium pentaborate solution and by the failure of manually initiated control rod insertion. The venting of primary containment after reaching 75 psia (0.52 MPa) is found to result in the release of the vented steam inside the reactor building, and to result in inadequate Net Positive Suction Head (NPSH) for any system pumping from the pressure suppression pool. CONTAIN code calculations show that personnel access to large portions of the reactor building would be lost soon after the initiation of venting and that the temperatures reached would be likely to result in independent equipment failures. It is concluded that containment venting would be more likely to cause or to hasten the onset of severe fuel damage than to prevent or to delay it. Two alternative strategies that do not require containment venting, but that could delay or prevent severe fuel damage, are analyzed. BWR-LTAS code results are presented for a successful mitigation strategy in which the reactor vessel is depressurized, and for one in which the reactor vessel remains at pressure

Water Condensation

DEFF Research Database (Denmark)

Jensen, Kasper Risgaard; Fojan, Peter; Jensen, Rasmus Lund

2014-01-01

The condensation of water is a phenomenon occurring in multiple situations in everyday life, e.g., when fog is formed or when dew forms on the grass or on windows. This means that this phenomenon plays an important role within the different fields of science including meteorology, building physics......, and chemistry. In this review we address condensation models and simulations with the main focus on heterogeneous condensation of water. The condensation process is, at first, described from a thermodynamic viewpoint where the nucleation step is described by the classical nucleation theory. Further, we address...

Provisions for containment venting in Germany

International Nuclear Information System (INIS)

Wilhelm, J.G.

1997-01-01

In this short paper an overlook is given of the systems developed in Germany for filtered containment venting and their implementation in nuclear power plants. More information on the development can be found in the Proceedings of the DOE/NRC Aircleaning Conferences. In Germany, 28.8 % of the electric energy is produced by 19 nuclear power reactors. No new power reactor is expected to be built at least within the next ten years, but France and Germany cooperate in the development of a future European Power Reactor (ERP). This reactor type will be fitted with a core catcher and passive cooling in order to avoid serious consequences of a hypothetical core meltdown accident so that provisions for containment venting are not required. 3 refs., 6 figs., 1 tab

Provisions for containment venting in Germany

Energy Technology Data Exchange (ETDEWEB)

Wilhelm, J.G.

1997-08-01

In this short paper an overlook is given of the systems developed in Germany for filtered containment venting and their implementation in nuclear power plants. More information on the development can be found in the Proceedings of the DOE/NRC Aircleaning Conferences. In Germany, 28.8 % of the electric energy is produced by 19 nuclear power reactors. No new power reactor is expected to be built at least within the next ten years, but France and Germany cooperate in the development of a future European Power Reactor (ERP). This reactor type will be fitted with a core catcher and passive cooling in order to avoid serious consequences of a hypothetical core meltdown accident so that provisions for containment venting are not required. 3 refs., 6 figs., 1 tab.

Current Status of Aerosol Generation and Measurement Facilities for the Verification Test of Containment Filtered Venting System in KAERI

Energy Technology Data Exchange (ETDEWEB)

Kim, Sung Il; An, Sang Mo; Ha, Kwang Soon; Kim, Hwan Yeol [KAERI, Daejeon (Korea, Republic of)

2016-05-15

In this study, the design of aerosol generation and measurement systems are explained and present circumstances are also described. In addition, the aerosol test plan is shown. Containment Filtered Venting System (FCVS) is one of the safety features to reduce the amount of released fission product into the environment by depressurizing the containment. Since Chernobyl accident, the regulatory agency in several countries in Europe such as France, Germany, Sweden, etc. have been demanded the installation of the CFVS. Moreover, the feasibility study on the CFVS was also performed in U.S. After the Fukushima accident, there is a need to improve a containment venting or installation of depressurizing facility in Korea. As a part of a Ministry of Trade, Industry and Energy (MOTIE) project, KAERI has been conducted the integrated performance verification test of CFVS. As a part of the test, aerosol generation system and measurement systems were designed to simulate the fission products behavior. To perform the integrated verification test of CFVS, aerosol generation and measurement system was designed and manufactured. The component operating condition is determined to consider the severe accident condition. The test will be performed in normal conditions at first, and will be conducted under severe condition, high pressure and high temperature. Undesirable difficulties which disturb the elaborate test are expected, such as thermophoresis on the pipe, vapor condensation on aerosol, etc.

GPE-BWR and the containment venting and filtering issue

International Nuclear Information System (INIS)

Palomo, J.; Santiago, J. de

1988-01-01

The Spanish Boiling Water Reactor Owner's Group (GPE-BWR) is formed by three utilities, owning four units: Santa Maria de Garona (46 MWe, BWR3, Mark I containment), Cofrentes (975 MWe, BWR6, Mark III containment) and Valdecaballeros (2x975 MWe, BWR6, Mark III containment) - all of the reactors having been supplied by General Electric. One of the GPE-BWR's several committees is the Safety and Licensing Committee, which follows up the evolution of severe accident topics and particularly the containment venting and filtering issue. In September 1987, the Consejo de Seguridad Nuclear (CSN), the Spanish Regulatory Body, asked the GPE-BWR to define its position on the installation of a containment venting system. The GPE-BWR created a Working Group which presented a Report on Containment Venting to the CSN in January 1987 gathered from: the US Nuclear Regulatory Commission (NRC); some US utilities; and several European countries, especially France, Germany and Sweden. CSN's review of the containment venting Report and the Action Plan proposed by the GPE-BWR finished in April 1988. The conclusion of the Report and the proposed Action Plan take into account the US NRC's identified open items on severe accidents and the R and D programs scheduled to close these items

CFD analysis of gas explosions vented through relief pipes.

Science.gov (United States)

Ferrara, G; Di Benedetto, A; Salzano, E; Russo, G

2006-09-21

Vent devices for gas and dust explosions are often ducted to safe locations by means of relief pipes. However, the presence of the duct increases the severity of explosion if compared to simply vented vessels (i.e. compared to cases where no duct is present). Besides, the identification of the key phenomena controlling the violence of explosion has not yet been gained. Multidimensional models coupling, mass, momentum and energy conservation equations can be valuable tools for the analysis of such complex explosion phenomena. In this work, gas explosions vented through ducts have been modelled by a two-dimensional (2D) axi-symmetric computational fluid dynamic (CFD) model based on the unsteady Reynolds Averaged Navier Stokes (RANS) approach in which the laminar, flamelet and distributed combustion models have been implemented. Numerical test have been carried out by varying ignition position, duct diameter and length. Results have evidenced that the severity of ducted explosions is mainly driven by the vigorous secondary explosion occurring in the duct (burn-up) rather than by the duct flow resistance or acoustic enhancement. Moreover, it has been found out that the burn-up affects explosion severity due to the reduction of venting rate rather than to the burning rate enhancement through turbulization.

Analysis of containment venting at the Peach Bottom atomic power station

International Nuclear Information System (INIS)

Hanson, D.J.; Blackman, H.S.; Nelson, W.R.; Wright, R.E.; Leonard, M.T.; DiSalvo, R.

1988-01-01

An analysis of the extent to which containment venting would be effective in preventing or mitigating the consequences of severe accidents has been completed for the Peach Bottom Units 2 and 3 (BWR-4s with Mark I containments). The analysis indicates that the effectiveness of venting in preventing containment overpressurization highly depends on the sequence of the severe accident. Containment venting can be effective for several classes of sequences, including transients with failure of long-term decay heat removal and loss-of-coolant accidents with breaks inside the containment. However, based on draft procedures and equipment in place at the time of the evaluation, containment venting has limited potential for further reducing the risk associated with three severe accident sequences currently identified as important risk contributors at Peach Bottom. Means of improving the potential for risk reduction is identified, but their influence on risk is not analyzed. (orig./HP)

Analysis of containment venting at the Peach Bottom Atomic Power Station

International Nuclear Information System (INIS)

Hanson, D.J.; Blackman, H.S.; Nelson, W.R.; Wright, R.E.; Leonard, M.T.; DiSalvo, R.

1986-01-01

An analysis of the extent to which containment venting would be effective in preventing or mitigating the consequences of severe accidents has been completed for the Peach Bottom Atomic Power Station, Units 2 and 3 (BWR-4s with Mark I containments). The analysis indicates that the effectiveness of venting in preventing containment overpressurization highly depends on the sequence of the severe accident. Containment venting can be effective for several classes of sequences, including transients with failure of long-term decay heat removal and loss-of-coolant accidents with breaks inside the containment. However, based on draft procedures and equipment in place at the time of the evaluation, containment venting has limited potential for further reducing the risk associated with three severe accident sequences currently identified as important risk contributors at Peach Bottom. Means of improving the potential for risk reduction is identified, but their influence on risk is not analyzed

The processing of simulated high-level radioactive waste sludges containing nitrites and mercury

International Nuclear Information System (INIS)

Zamecnik, J.R.; Hutson, N.D.; Ritter, J.A.; Carter, J.T.

1991-01-01

The reaction of formic acid with simulated alkaline sludge containing mercury and nitrite was studied in an engineering-scale facility. Quantification of offgas production was performed, with the major offgases being CO 2 and NO x . A small amount of CO was also found. The NO x was scrubbed in the offgas condenser and formed very acidic solutions of nitrous and nitric acids. These acids dissolved mercury that was stripped from the sludge. However, the overall efficiency of mercury stripping was greater than expected, and the final mercury concentration in the sludge was lower than expected. The NO x in the offgas also caused large temperature rises in the offgas system due to the exothermic reaction of NO with O 2 . This temperature rise had a detrimental effect on the performance of the Formic Acid Vent Condenser, such that redesign is being contemplated. 6 refs., 6 figs., 3 tabs

A finite element analysis of novel vented dental abutment geometries for cement-retained crown restorations.

Science.gov (United States)

Rodriguez, Lucas C; Saba, Juliana N; Meyer, Clark A; Chung, Kwok-Hung; Wadhwani, Chandur; Rodrigues, Danieli C

2016-11-01

Recent literature indicates that the long-term success of dental implants is, in part, attributed to how dental crowns are attached to their associated implants. The commonly utilized method for crown attachment - cementation, has been criticized because of recent links between residual cement and peri-implant disease. Residual cement extrusion from crown-abutment margins post-crown seating is a growing concern. This study aimed at (1) identifying key abutment features, which would improve dental cement flow characteristics, and (2) understanding how these features would impact the mechanical stability of the abutment under functional loads. Computational fluid dynamic modeling was used to evaluate cement flow in novel abutment geometries. These models were then evaluated using 3D-printed surrogate models. Finite element analysis also provided an understanding of how the mechanical stability of these abutments was altered after key features were incorporated into the geometry. The findings demonstrated that the key features involved in improved venting of the abutment during crown seating were (1) addition of vents, (2) diameter of the vents, (3) location of the vents, (4) addition of a plastic screw insert, and (5) thickness of the abutment wall. This study culminated in a novel design for a vented abutment consisting of 8 vents located radially around the abutment neck-margin plus a plastic insert to guide the cement during seating and provide retrievability to the abutment system.Venting of the dental abutment has been shown to decrease the risk of undetected residual dental cement post-cement-retained crown seating. This article will utilize a finite element analysis approach toward optimizing dental abutment designs for improved dental cement venting. Features investigated include (1) addition of vents, (2) diameter of vents, (3) location of vents, (4) addition of plastic screw insert, and (5) thickness of abutment wall.

A finite element analysis of novel vented dental abutment geometries for cement‐retained crown restorations

Science.gov (United States)

Rodriguez, Lucas C.; Saba, Juliana N.; Meyer, Clark A.; Chung, Kwok‐Hung; Wadhwani, Chandur

2016-01-01

Abstract Recent literature indicates that the long‐term success of dental implants is, in part, attributed to how dental crowns are attached to their associated implants. The commonly utilized method for crown attachment – cementation, has been criticized because of recent links between residual cement and peri‐implant disease. Residual cement extrusion from crown‐abutment margins post‐crown seating is a growing concern. This study aimed at (1) identifying key abutment features, which would improve dental cement flow characteristics, and (2) understanding how these features would impact the mechanical stability of the abutment under functional loads. Computational fluid dynamic modeling was used to evaluate cement flow in novel abutment geometries. These models were then evaluated using 3D‐printed surrogate models. Finite element analysis also provided an understanding of how the mechanical stability of these abutments was altered after key features were incorporated into the geometry. The findings demonstrated that the key features involved in improved venting of the abutment during crown seating were (1) addition of vents, (2) diameter of the vents, (3) location of the vents, (4) addition of a plastic screw insert, and (5) thickness of the abutment wall. This study culminated in a novel design for a vented abutment consisting of 8 vents located radially around the abutment neck‐margin plus a plastic insert to guide the cement during seating and provide retrievability to the abutment system.Venting of the dental abutment has been shown to decrease the risk of undetected residual dental cement post‐cement‐retained crown seating. This article will utilize a finite element analysis approach toward optimizing dental abutment designs for improved dental cement venting. Features investigated include (1) addition of vents, (2) diameter of vents, (3) location of vents, (4) addition of plastic screw insert, and (5) thickness of abutment wall. PMID

Detection of putatively thermophilic anaerobic methanotrophs in diffuse hydrothermal vent fluids.

Science.gov (United States)

Merkel, Alexander Y; Huber, Julie A; Chernyh, Nikolay A; Bonch-Osmolovskaya, Elizaveta A; Lebedinsky, Alexander V

2013-02-01

The anaerobic oxidation of methane (AOM) is carried out by a globally distributed group of uncultivated Euryarchaeota, the anaerobic methanotrophic arachaea (ANME). In this work, we used G+C analysis of 16S rRNA genes to identify a putatively thermophilic ANME group and applied newly designed primers to study its distribution in low-temperature diffuse vent fluids from deep-sea hydrothermal vents. We found that the G+C content of the 16S rRNA genes (P(GC)) is significantly higher in the ANME-1GBa group than in other ANME groups. Based on the positive correlation between the P(GC) and optimal growth temperatures (T(opt)) of archaea, we hypothesize that the ANME-1GBa group is adapted to thrive at high temperatures. We designed specific 16S rRNA gene-targeted primers for the ANME-1 cluster to detect all phylogenetic groups within this cluster, including the deeply branching ANME-1GBa group. The primers were successfully tested both in silico and in experiments with sediment samples where ANME-1 phylotypes had previously been detected. The primers were further used to screen for the ANME-1 microorganisms in diffuse vent fluid samples from deep-sea hydrothermal vents in the Pacific Ocean, and sequences belonging to the ANME-1 cluster were detected in four individual vents. Phylotypes belonging to the ANME-1GBa group dominated in clone libraries from three of these vents. Our findings provide evidence of existence of a putatively extremely thermophilic group of methanotrophic archaea that occur in geographically and geologically distinct marine hydrothermal habitats.

Investigations of a novel fauna from hydrothermal vents along the Arctic Mid-Ocean Ridge (AMOR) (Invited)

Science.gov (United States)

Rapp, H.; Schander, C.; Halanych, K. M.; Levin, L. A.; Sweetman, A.; Tverberg, J.; Hoem, S.; Steen, I.; Thorseth, I. H.; Pedersen, R.

2010-12-01

The Arctic deep ocean hosts a variety of habitats ranging from fairly uniform sedimentary abyssal plains to highly variable hard bottoms on mid ocean ridges, including biodiversity hotspots like seamounts and hydrothermal vents. Deep-sea hydrothermal vents are usually associated with a highly specialized fauna, and since their discovery in 1977 more than 400 species of animals have been described. This fauna includes various animal groups of which the most conspicuous and well known are annelids, mollusks and crustaceans. The newly discovered deep sea hydrothermal vents on the Mohns-Knipovich ridge north of Iceland harbour unique biodiversity. The Jan Mayen field consists of two main areas with high-temperature white smoker venting and wide areas with low-temperature seepage, located at 5-700 m, while the deeper Loki Castle vent field at 2400 m depth consists of a large area with high temperature black smokers surrounded by a sedimentary area with more diffuse low-temperature venting and barite chimneys. The Jan Mayen sites show low abundance of specialized hydrothermal vent fauna. Single groups have a few specialized representatives but groups otherwise common in hydrothermal vent areas are absent. Slightly more than 200 macrofaunal species have been identified from this vent area, comprising mainly an assortment of bathyal species known from the surrounding area. Analysis of stable isotope data also indicates that the majority of the species present are feeding on phytodetritus and/or phytoplankton. However, the deeper Loki Castle vent field contains a much more diverse vent endemic fauna with high abundances of specialized polychaetes, gastropods and amphipods. These specializations also include symbioses with a range of chemosynthetic microorganisms. Our data show that the fauna composition is a result of high degree of local specialization with some similarities to the fauna of cold seeps along the Norwegian margin and wood-falls in the abyssal Norwegian Sea

33 CFR 159.61 - Vents.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Vents. 159.61 Section 159.61 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE... to minimize clogging by either the contents of the tank or climatic conditions such as snow or ice. ...

Modelling hydrothermal venting in volcanic sedimentary basins: Impact on hydrocarbon maturation and paleoclimate

Science.gov (United States)

Iyer, Karthik; Schmid, Daniel W.; Planke, Sverre; Millett, John

2017-06-01

Vent structures are intimately associated with sill intrusions in sedimentary basins globally and are thought to have been formed contemporaneously due to overpressure generated by gas generation during thermogenic breakdown of kerogen or boiling of water. Methane and other gases generated during this process may have driven catastrophic climate change in the geological past. In this study, we present a 2D FEM/FVM model that accounts for 'explosive' vent formation by fracturing of the host rock based on a case study in the Harstad Basin, offshore Norway. Overpressure generated by gas release during kerogen breakdown in the sill thermal aureole causes fracture formation. Fluid focusing and overpressure migration towards the sill tips results in vent formation after only few tens of years. The size of the vent depends on the region of overpressure accessed by the sill tip. Overpressure migration occurs in self-propagating waves before dissipating at the surface. The amount of methane generated in the system depends on TOC content and also on the type of kerogen present in the host rock. Generated methane moves with the fluids and vents at the surface through a single, large vent structure at the main sill tip matching first-order observations. Violent degassing takes place within the first couple of hundred years and occurs in bursts corresponding to the timing of overpressure waves. The amount of methane vented through a single vent is only a fraction (between 5 and 16%) of the methane generated at depth. Upscaling to the Vøring and Møre Basins, which are a part of the North Atlantic Igneous Province, and using realistic host rock carbon content and kerogen values results in a smaller amount of methane vented than previously estimated for the PETM. Our study, therefore, suggests that the negative carbon isotope excursion (CIE) observed in the fossil record could not have been caused by intrusions within the Vøring and Møre Basins alone and that a contribution

Central extracorporeal membrane oxygenation requiring pulmonary arterial venting after near-drowning.

Science.gov (United States)

Kimura, Mitsutoshi; Kinoshita, Osamu; Fujimoto, Yoshifumi; Murakami, Arata; Shindo, Takahiro; Kashiwa, Koichi; Ono, Minoru

2014-02-01

Extracorporeal membrane oxygenation (ECMO) is an effective respiratory and circulatory support in patients in refractory cardiogenic shock or cardiac arrest. Peripheral ECMO sometimes requires left heart drainage; however, few reports state that pulmonary arterial (PA) venting is required during ECMO support. We present a case of a 14-year-old boy who required PA venting during ECMO support after resuscitation from near-drowning in freshwater. A biventricular assist device with an oxygenator implantation was intended on day 1; however, we were unable to proceed because of increasing of pulmonary vascular resistance from the acute lung injury. Central ECMO with PA venting was then performed. On day 13, central ECMO was converted to biventricular assist device with an oxygenator, which was removed on day 16. This case suggests that PA venting during ECMO support may be necessary in some cases of respiratory and circulatory failure with high pulmonary vascular resistance after near-drowning.

Vent clearing analysis of a Mark III pressure suppression containment

International Nuclear Information System (INIS)

Quintana, R.

1979-01-01

An analysis of the vent clearing transient in a Mark III pressure suppression containment after a hypothetical LOCA is carried out. A two-dimensional numerical model solving the transient fluid dynamic equations is used. The geometry of the pressure suppression pool is represented and the pressure and velocity fields in the pool are obtained from the moment the LOCA occurs until the first vent in the drywell wall clears. The results are compared to those obtained with the one-diemensional model used for containment design, with special interest on two-dimensional effects. Some conclusions concerning the effect of the water discharged into the suppression pool through the vents on submerged structures are obtained. Future improvements to the model are suggested. (orig.)

Assessment of Literature Related to Combustion Appliance Venting Systems

Energy Technology Data Exchange (ETDEWEB)

Rapp, Vi H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Singer, Brett C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Stratton, Chris [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wray, Craig P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2012-06-01

In many residential building retrofit programs, air tightening to increase energy efficiency is constrained by concerns about related impacts on the safety of naturally vented combustion appliances. Tighter housing units more readily depressurize when exhaust equipment is operated, making combustion appliances more prone to backdraft or spillage. Several test methods purportedly assess the potential for depressurization-induced backdrafting and spillage, but these tests are not robustly reliable and repeatable predictors of venting performance, in part because they do not fully capture weather effects on venting performance. The purpose of this literature review is to investigate combustion safety diagnostics in existing codes, standards, and guidelines related to combustion appliances. This review summarizes existing combustion safety test methods, evaluations of these test methods, and also discusses research related to wind effects and the simulation of vent system performance. Current codes and standards related to combustion appliance installation provide little information on assessing backdrafting or spillage potential. A substantial amount of research has been conducted to assess combustion appliance backdrafting and spillage test methods, but primarily focuses on comparing short-term (stress) induced tests and monitoring results. Monitoring, typically performed over one week, indicated that combinations of environmental and house operation characteristics most conducive to combustion spillage were rare. Research, to an extent, has assessed existing combustion safety diagnostics for house depressurization, but the objectives of the diagnostics, both stress and monitoring, are not clearly defined. More research is also needed to quantify the frequency of test “failure” occurrence throughout the building stock and assess the statistical effects of weather (especially wind) on house depressurization and in turn on combustion appliance venting

Performance of evaporative condensers

Energy Technology Data Exchange (ETDEWEB)

Ettouney, Hisham M.; El-Dessouky, Hisham T.; Bouhamra, Walid; Al-Azmi, Bader

2001-07-01

Experimental investigation is conducted to study the performance of evaporative condensers/coolers. The analysis includes development of correlations for the external heat transfer coefficient and the system efficiency. The evaporative condenser includes two finned-tube heat exchangers. The system is designed to allow for operation of a single condenser, two condensers in parallel, and two condensers in series. The analysis is performed as a function of the water-to-air mass flow rate ratio (L/G) and the steam temperature. Also, comparison is made between the performance of the evaporative condenser and same device as an air-cooled condenser. Analysis of the collected data shows that the system efficiency increases at lower L/G ratios and higher steam temperatures. The system efficiency for various configurations for the evaporative condenser varies between 97% and 99%. Lower efficiencies are obtained for the air-cooled condenser, with values between 88% and 92%. The highest efficiency is found for the two condensers in series, followed by two condensers in parallel and then the single condenser. The parallel condenser configuration can handle a larger amount of inlet steam and can provide the required system efficiency and degree of subcooling. The correlation for the system efficiency gives a simple tool for preliminary system design. The correlation developed for the external heat transfer coefficient is found to be consistent with the available literature data. (Author)

Condensation of steam

International Nuclear Information System (INIS)

Prisyazhniuk, V.A.

2002-01-01

An equation for nucleation kinetics in steam condensation has been derived, the equation taking into account the concurrent and independent functioning of two nucleation mechanisms: the homogeneous one and the heterogeneous one. The equation is a most general-purpose one and includes all the previously known condensation models as special cases. It is shown how the equation can be used in analyzing the process of steam condensation in the condenser of an industrial steam-turbine plant, and in working out new ways of raising the efficiency of the condenser, as well as of the steam-turbine plant as a whole. (orig.)

40 CFR 63.115 - Process vent provisions-methods and procedures for process vent group determination.

Science.gov (United States)

2010-07-01

... this section. (2) The gas volumetric flow rate shall be determined using Method 2, 2A, 2C, or 2D of 40... accepted chemical engineering principles, measurable process parameters, or physical or chemical laws or...)(3) of this section. (i) The vent stream volumetric flow rate (Qs), in standard cubic meters per...

Hydrogen venting characteristics of commercial carbon-composite filters and applications to TRU waste

International Nuclear Information System (INIS)

Callis, E.L.; Marshall, R.S.; Cappis, J.H.

1997-04-01

The generation of hydrogen (by radiolysis) and of other potentially flammable gases in radioactive wastes which are in contact with hydrogenous materials is a source of concern, both from transportation and on-site storage considerations. Because very little experimental data on the generation and accumulation of hydrogen was available in actual waste materials, work was initiated to experimentally determine factors affecting the concentration of hydrogen in the waste containers, such as the hydrogen generation rate, (G-values) and the rate of loss of hydrogen through packaging and commercial filter-vents, including a new design suitable for plastic bags. This report deals only with the venting aspect of the problem. Hydrogen venting characteristics of two types of commercial carbon-composite filter-vents, and two types of PVC bag closures (heat-sealed and twist-and-tape) were measured. Techniques and equipment were developed to permit measurement of the hydrogen concentration in various layers of actual transuranic (TRU) waste packages, both with and without filter-vents. A test barrel was assembled containing known configuration and amounts of TRU wastes. Measurements of the hydrogen in the headspace verified a hydrogen release model developed by Benchmark Environmental Corporation. These data were used to calculate revised wattage Emits for TRU waste packages incorporating the new bag filter-vent

Topotactic conversion of layered silicate RUB-15 to silica sodalite through interlayer condensation in N-methylformamide.

Science.gov (United States)

Koike, Masakazu; Asakura, Yusuke; Sugihara, Megumi; Kuroda, Yoshiyuki; Tsuzura, Hidehiro; Wada, Hiroaki; Shimojima, Atsushi; Kuroda, Kazuyuki

2017-08-08

Silica sodalite was obtained using topotactic conversion of layered silicate RUB-15 through stepwise processes that consisted of the control of stacking sequence of the layers, interlayer condensation by refluxing, and elimination of intercalated guest species. The interlayer condensation of RUB-15, in which acetic acid was pre-intercalated between the layers to control the stacking sequence, afforded a sodalite framework containing organic guest species by refluxing in N-methylformamide (NMF). The pre-intercalated acetic acid molecules were largely replaced with NMF. This formation process of silica sodalite containing large amounts of intercalated organic guest species is in clear contrast to the previously reported process that used direct calcination of an intercalation compound of layered RUB-15 accommodating acetic acid between the layers. Calcination of the condensed product provided sodalite with fewer defects than the directly calcined product, thus indicating the advantage of the stepwise process. The method reported here is useful for the preparation of pure silica sodalite with relatively low defects and plate-like morphology.

Analysis of design and operational effects of filtered containment venting on depressurization and fission product release

Energy Technology Data Exchange (ETDEWEB)

Park, Jong Woon; Seol, Wook-Cheol; Kim, Jisu [Dongguk Univ., Gyeongbuk (Korea, Republic of)

2017-03-15

Effects of design and operational parameters of filtered containment venting system during a specified containment depressurization and relative aero sol release amount are analyzed. The analyses is performed by using the MAAP4 code for the APR1400 reactor. Major results uniquely identified from the analyses can be noted as following: Even though containment depressurization is accelerated as the pipe size increases, the venting system solution is also depleted earlier. Elapsed times to reach lower end pressure of 2 bar are nearly identical regardless of the vent initiation pressure and thus early venting is not much beneficial than late venting. Stroke time of the isolation valves has no effect on the depressurization performance and thus slow opening is beneficial for load reduction from the vent effluent.

A model for vented deflagration of hydrogen in a volume

International Nuclear Information System (INIS)

Mulpuru, S.R.; Wilkin, G.B.

1982-02-01

A simple model was constructed to predict the property transients resulting from the deflagration of a combustible mixture in a sphere or cylinder with venting of the gas mixture to the environment. A computer program VENT, was written to solve the model equation. The model will be particularly useful for studying hydrogen burning effects in loss-of-coolant plus losss of emergency coolant accidents in CANDU reactors

Modelling of condensation phenomena

International Nuclear Information System (INIS)

Jeong, Jae Jun; Chang, Won Pyo

1996-07-01

Condensation occurs when vapor is cooled sufficiently below the saturation temperature to induce the nucleation of droplets. Such nucleation may occur homogeneously within the vapor or heterogeneously on entrained particular matter. Heterogeneous nucleation may occur on the walls of the system, where the temperature is below the saturation temperature. There are two forms of heterogeneous condensation, drop-wise and film-wise. Another form of condensation occurs when vapor directly contacts to subcooled liquid. In nuclear power plant systems, all forms of condensation may occur during normal operation or accident conditions. In this work the modelling of condensation is surveyed, including the Nusselts' laminar film condensation theory in 1916, Rohsenow's turbulent film condensation model in 1950s, and Chen's models in 1987. Major attention is paid on the film condensation models among various research results because of its importance in engineering applications. It is found that theory, experiment, and empirical correlations for film condensation are well established, but research for drop-wise and direct-contact condensation are not sufficient yet. Condensation models in the best-estimate system codes such as RELAP5/MOD3 and CATHARE2 are also investigated. 3 tabs., 11 figs., 36 refs. (Author)

Improved condenser design and condenser-fan operation for air-cooled chillers

International Nuclear Information System (INIS)

Yu, F.W.; Chan, K.T.

2006-01-01

Air-cooled chillers traditionally operate under head pressure control via staging constant-speed condenser fans. This causes a significant drop in their coefficient of performance (COP) at part load or low outdoor temperatures. This paper describes how the COP of these chillers can be improved by a new condenser design, using evaporative pre-coolers and variable-speed fans. A thermodynamic model for an air-cooled screw-chiller was developed, within which the condenser component considers empirical equations showing the effectiveness of an evaporative pre-cooler in lowering the outdoor temperature in the heat-rejection process. The condenser component also contains an algorithm to determine the number and speed of the condenser fans staged at any given set point of condensing temperature. It is found that the chiller's COP can be maximized by adjusting the set point based on any given chiller load and wet-bulb temperature of the outdoor air. A 5.6-113.4% increase in chiller COP can be achieved from the new condenser design and condenser fan operation. This provides important insights into how to develop more energy-efficient air-cooled chillers

Proceedings: Condenser technology conference

International Nuclear Information System (INIS)

Tsou, J.L.; Mussalli, Y.G.

1991-08-01

Seam surface condenser and associated systems performance strongly affects availability and heat rate in nuclear and fossil power plants. Thirty-six papers presented at a 1990 conference discuss research results, industry experience, and case histories of condenser problems and solutions. This report contains papers on life extension, performance improvement, corrosion and failure analysis, fouling prevention, and recommendation for future R ampersand D. The information represents recent work on condenser problems and solutions to improve the procurement, operation, and maintenance functions of power plant personnel. Several key points follow: A nuclear and a fossil power plant report show that replacing titanium tube bundles improves condenser availability and performance. One paper reports 10 years of experience with enhanced heat transfer tubes in utility condensers. The newly developed enhanced condenser tubes could further improve condensing heat transfer. A new resistance summation method improves the accuracy of condenser performance prediction, especially for stainless steel and titanium tubed condensers. Several papers describe improved condenser fouling monitoring techniques, including a review of zebra mussel issues

Vented nuclear fuel element

International Nuclear Information System (INIS)

Oguma, M.; Hirose, Y.

1976-01-01

A description is given of a vented nuclear fuel element having a plenum for accumulation of fission product gases and plug means for delaying the release of the fission product gases from the plenum, the plug means comprising a first porous body wettable with a liquid metal and a second porous body non-wettable with the liquid metal, the first porous body being impregnated with the liquid metal and in contact with the liquid metal

[The balance of harmful trace contaminants between the air humidity condensate and air in a simulator of the Mir orbit station moisture condensation unit].

Science.gov (United States)

Zlotopol'skiĭ, V M; Smolenskaia, T S

2000-01-01

Subject of the investigation was the balance of harmful trace contaminants (HTC) between the air moisture condensate and air in a simulator of the MIR moisture condensation unit. Experiments involved various classes of water-solvent compounds including alcohols (C1-C4), ketons (C1-C2), aldehydes (C1-C2), fatty acids (C2-C4), esters (acetates C4-C6), and ammonium. For most of the compounds, removal efficiency correlates with air humidity and virtually does not depend on the HTC concentration within the range of 0.25 to 59.1 mg/m3.

Description of steam-condensation phenomena during the loss-of-coolant accident

International Nuclear Information System (INIS)

McCauley, E.W.; Holman, G.S.; Aust, E.; Schwan, H.; Vollbrandt, J.; Fuerst, H.

1980-01-01

The development and verification of advanced computer models which describe the boiling water reactor (BWR) pressure suppression process for a hypothetical loss-of-coolant accident (LOCA) require a clear description of basic steam condensation phenomena. The GKSS Research Center, in coordination with interested institutions of West Germany and the United States, is currently conducting a test program for such basic research on a multivent BWR-related pressure suppression system. The Lawrence Livermore National Laboratory (LLNL) acts as the principal US NRC liaison for this test program, with particular emphasis on development of GKSS data for confirmatory use regarding US Mark II nuclear power plants as well as to advanced code development. The multivent test facility, placed in operation in February 1979, is a three-pipe full-scale vent system modelling main features of both the West German KWU and United States G.E. Mk II BWR pressure suppression systems. The test facility and testing programs are described

Lactic Acid Production from Pretreated Hydrolysates of Corn Stover by a Newly Developed Bacillus coagulans Strain

OpenAIRE

Jiang, Ting; Qiao, Hui; Zheng, Zhaojuan; Chu, Qiulu; Li, Xin; Yong, Qiang; Ouyang, Jia

2016-01-01

An inhibitor-tolerance strain, Bacillus coagulans GKN316, was developed through atmospheric and room temperature plasma (ARTP) mutation and evolution experiment in condensed dilute-acid hydrolysate (CDH) of corn stover. The fermentabilities of other hydrolysates with B. coagulans GKN316 and the parental strain B. coagulans NL01 were assessed. When using condensed acid-catalyzed steam-exploded hydrolysate (CASEH), condensed acid-catalyzed liquid hot water hydrolysate (CALH) and condensed acid-...

Condensate cleaning systems

International Nuclear Information System (INIS)

Yamamoto, Michiyoshi; Oosumi, Katsumi; Takashima, Yoshie; Mitani, Shinji.

1982-01-01

Purpose: To decrease the frequency for the backwash and regeneration operations due to the increase in the differential pressure resulted from claddings captured in a mixed floor type desalter, and decrease the amount of radioactive liquid wastes of claddings from the condensate systems by removing claddings with electromagnetic filters. Constitution: In an existent plant, a valves is disposed between a condensate pump and a mixed floor type desalter. A pipeway is branched from a condensate pipe between the condensate pipe and the valve, through which condensates are transferred by a pump to an electromagnetic filter such as of a high gradient type electromagntic filter to remove claddings, then returned to a condensate pipe between the valve and the mixed floor type desalter and, thereafter, are removed with ionic components in the mixed floor type desalter and fed to the reactor. (Yoshino, Y.)

Direct torus venting analysis for Chinshan BWR-4 plant with MARK-I containment

Energy Technology Data Exchange (ETDEWEB)

Yuann, Yng-Ruey, E-mail: ryyuann@iner.gov.tw

2017-03-15

Highlights: • Study the effectiveness of Direct Torus Venting System (DTVS) during extended SBO of 24 h for Chinshan MARK-I plant. • Containment response is analyzed by GOTHIC based on boundary conditions from RETRAN calculation. • Analyses are performed with and without DTVS, respectively. • Suppression pool is sub-divided and thermal stratification is observed. - Abstract: The Chinshan plant, owned by Taiwan Power Company, has twin units of BWR-4 reactor and MARK-I containment. Both units have been operating at rated core thermal power of 1840 MWt. The existing Direct Torus Venting System (DTVS) is the main system used for venting the containment during the extended station blackout event. The purpose of this paper is to study the effects of the DTVS venting on the response of the containment pressure and temperature. The reactor is depressurized by manually opening the safety relief valves (SRVs) during the SBO, which causes the mass and energy to be discharged into and heat up the suppression pool. The RETRAN model is used to calculate the Nuclear Steam Supply System (NSSS) response and generate the SRV blowdown conditions, including SRV pressure, enthalpy, and mass flow rate. These conditions are then used as the time-dependent boundary conditions for the GOTHIC code to calculate the containment pressure and temperature response. The DTVS model is established in the GOTHIC model based on the venting size, venting piping loss, venting initiation time, and venting source. The lumped volume model, 1-D coarse-mesh model, and 3-D coarse-mesh model are considered in the torus volume. The calculation is first done without DTVS venting to establish a reference basis. Then a case with DTVS available is performed. Comparison of the two cases shows that the existing DTVS design is effective in mitigating the severity of the containment pressure and temperature transients. The results also show that the 1-D coarse-mesh model may not be appropriate since a

Possible mechanism of structural incorporation of Al into diatomite during the deposition process I. Via a condensation reaction of hydroxyl groups.

Science.gov (United States)

Liu, Dong; Yu, Wenbin; Deng, Liangliang; Yuan, Weiwei; Ma, Lingya; Yuan, Peng; Du, Peixin; He, Hongping

2016-01-01

The structural incorporation of aluminium (Al) into diatomite is investigated by preparing several Al-diatomite composites by loading an Al precursor, hydroxyl aluminum polymer (Al13), onto the surface of diatomite and heating at various temperatures. The results indicate that Al was incorporated and implanted into the structure of diatomite by the condensation reaction of the hydroxyl groups of Al13 and diatomite, and the Si-O-Al(OH) groups were formed during the condensation reaction. Al incorporation by the condensation reaction of hydroxyl groups of Al13 with single silanols of diatomite occurred more readily than that with geminal silanols. The Al incorporation increased solid acidity of diatomite after Al incorporation. The acidity improvement was various for different types of acid sites, depending on the preparation temperature of the Al-incorporated diatomite. Both Brønsted and Lewis acid sites increased greatly after heating at 250 and 350 °C, but only L acid sites significantly improved after heating at 500 °C. These results demonstrate that the structural incorporation of Al(3+) ions into diatomite can occur by the condensation reaction of the hydroxyl groups of the Al precursors and diatomite. Moreover, the rich solid acid sites of Al-incorporated diatomite show its promising application as a solid acid catalyst. Copyright © 2015 Elsevier Inc. All rights reserved.

CFD application on IRWST hydrodynamic analysis during the sparger air venting

International Nuclear Information System (INIS)

Kim, Y. I.; Hwang, Y. D.; Kim, H. Y.; Bae, Y. Y.; Park, J. K.

1998-01-01

A numerical study was performed using preleased FLUENT V4.5 to investigate the applicability of the CFD model for IRWST hydrodynamic analysis during the sparger air venting. Transient calculations were performed with the compressible VOF model on the selected ABB-Atom Unit Cell Test data. This study was mainly focused on the simulation of the bubble formation process in the water pool and time varying pressure history during the air venting from the sparger. The simulated peak pressure was over-predicted in general, but the main frequency is in good agreement with the simulated data. It was shown that there was a strong dependence on the mass discharge rate of the air trapped in the vent line. The peak pressure acceptable for the conservative evaluation of the sparger performance was obtained by reducing the air discharge velocity. This indicates that the proper estimations of the air venting velocity consistent with the sparger design and operating conditions is essential for the application of FLUENT V4.5 to the sparger performance analysis of KNGR

Condensation coefficient of water in a weak condensation state

International Nuclear Information System (INIS)

Kobayashi, Kazumichi; Watanabe, Shunsuke; Yamano, Daigo; Yano, Takeru; Fujikawa, Shigeo

2008-01-01

The condensation coefficient of water at a vapor-liquid interface is determined by combining shock tube experiments and numerical simulations of the Gaussian-BGK Boltzmann equation. The time evolution in thickness of a liquid film, which is formed on the shock tube endwall behind the shock wave reflected at the endwall, is measured with an optical interferometer consisting of the physical beam and the reference one. The reference beam is utilized to eliminate systematic noises from the physical beam. The growth rate of the film is evaluated from the measured time evolution and it is incorporated into the kinetic boundary condition for the Boltzmann equation. From a numerical simulation using the boundary condition, the condensation coefficient of water is uniquely deduced. The results show that, in a condition of weak condensation near a vapor-liquid equilibrium state, the condensation coefficient of water is almost equal to the evaporation coefficient estimated by molecular dynamics simulations near a vapor-liquid equilibrium state and it decreases as the system becomes a nonequilibrium state. The condensation coefficient of water is nearly identical with that of methanol [Mikami, S., Kobayashi, K., Ota, T., Fujikawa, S., Yano, T., Ichijo, M., 2006. Molecular gas dynamics approaches to interfacial phenomena accompanied with condensation. Exp. Therm. Fluid Sci. 30, 795-800].

Condensation coefficient of water in a weak condensation state

Science.gov (United States)

Kobayashi, Kazumichi; Watanabe, Shunsuke; Yamano, Daigo; Yano, Takeru; Fujikawa, Shigeo

2008-07-01

The condensation coefficient of water at a vapor-liquid interface is determined by combining shock tube experiments and numerical simulations of the Gaussian-BGK Boltzmann equation. The time evolution in thickness of a liquid film, which is formed on the shock tube endwall behind the shock wave reflected at the endwall, is measured with an optical interferometer consisting of the physical beam and the reference one. The reference beam is utilized to eliminate systematic noises from the physical beam. The growth rate of the film is evaluated from the measured time evolution and it is incorporated into the kinetic boundary condition for the Boltzmann equation. From a numerical simulation using the boundary condition, the condensation coefficient of water is uniquely deduced. The results show that, in a condition of weak condensation near a vapor-liquid equilibrium state, the condensation coefficient of water is almost equal to the evaporation coefficient estimated by molecular dynamics simulations near a vapor-liquid equilibrium state and it decreases as the system becomes a nonequilibrium state. The condensation coefficient of water is nearly identical with that of methanol [Mikami, S., Kobayashi, K., Ota, T., Fujikawa, S., Yano, T., Ichijo, M., 2006. Molecular gas dynamics approaches to interfacial phenomena accompanied with condensation. Exp. Therm. Fluid Sci. 30, 795-800].

Arsenic speciation in shrimp and mussel from the Mid-Atlantic hydrothermal vents

DEFF Research Database (Denmark)

Larsen, Erik Huusfeldt; Quetel, C. R.; Munoz, R.

1997-01-01

Specimens of shrimp (Rimicaris exoculata) and mussel (Bathymodiolus puteoserpentis) were collected 3500 m below the ocean surface at the hydrothermal vents of the mid-Atlantic Ridge (TAG and Snake Pit sites, respectively). Arsenic, a potentially toxic element, is among the substances emitted...... by the hydrothermal vents. The hydrothermal vent shrimp, which are known to be a primary consumer of the primary producing chemolithoautotrophic bacteria, contained arsenic at 13 mu g g(-1) almost exclusively as arsenobetaine (AsB). Arsenic was present in the soft:issues of the mussel at 40 mu g g(-1) and the major...... of arsenic species found in the shrimp and mussel species in the deep-sea is similar to that found in their counterparts from the ocean surface. It is concluded that the autotrophic bacteria of the hydrothermal vent ecosystem and the symbiotic bacteria harboured in the mussel species are responsible...

Westinghouse containment filtered venting system wet scrubber technology

International Nuclear Information System (INIS)

Kristensson, S.; Nilsson, P-O.

2014-01-01

Following the Fukushima event Westinghouse has further developed and enhanced its filtered containment venting system (FCVS) product line. The filtration efficiency of the proven FILTRA-MVSS system installed at all Swedish NPPs as well as at the Muhelberg plant in Switzerland has been enhanced and a new wet scrubber design, SVEN (Safety Venting), based on the FILTRA-MVSS tradition, developed. To meet increased filtration requirements for organic iodine these two wet scrubber products have been complemented with a zeolite module. The offering of a select choice of products allows for a better adjustment to the specific constraints and needs of each nuclear power station that is planning for the installation of such a system. The FILTRA-MVSS (MVSS=Multi Venturi Scrubber System) is a wet containment filtered vent system that uses multiple venturies to create an interaction between the vent gases and the scrubber media allowing for removal of aerosols and gaseous iodines in a very efficient manner. The FILTRA-MVSS was originally developed to meet stringent requirements on autonomy and maintained filtration efficiency over a wide range of venting conditions. The system was jointly developed in the late 80's by ABB Atom and ABB Flaekt, today Westinghouse and Alstom. Following installations in Sweden and Switzerland the system was further developed by replacement of the gravel-bed moisture separator with a standard demister and by addition of a set of sintered metal fibre filter cartridges placed after the moisture separator step. The system is today offered as a modular steel tank design to simplify installation at site. To reduce complexity and delivery time Westinghouse has developed an alternative design in which the venturi module is replaced by a submerged metal fibre filter cartridges module. This new wet scrubber design, SVEN (patent pending), provides a flexible, compact, and lower weight system, while still preserving and even enhancing the filtration

Two-dimensional condensation of pyrimidine oligonucleotides during their self-assemblies at mercury based surfaces

Energy Technology Data Exchange (ETDEWEB)

Hason, Stanislav [Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i. Kralovopolska 135, CZ-612 65 Brno (Czech Republic)], E-mail: hasons@ibp.cz; Vetterl, Vladimir [Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i. Kralovopolska 135, CZ-612 65 Brno (Czech Republic); Fojta, Miroslav [Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i. Kralovopolska 135, CZ-612 65 Brno (Czech Republic)], E-mail: fojta@ibp.cz

2008-02-15

For the first time it is shown that homopyrimidine oligodeoxynucleotides (ODNs) adsorbed at mercury or amalgam electrode surface can condensate upon applying negative potentials (around -1.35 V vs. Ag/AgCl/3M KCl). This 2D condensation resulted in formation of capacitance pits on the C-E curves resembling those observed earlier with monomeric nucleic acid bases, nucleosides and nucleotides. Differences in behavior of the condensed layers of dT{sub 30} and dC{sub 30} ODNs, reflecting different physico-chemical and electrochemical properties of thymine and cytosine, were observed. Formation of the ODN condensed film involved reorientation of the oligonucleotide molecules firmly adsorbed at the electrode and took place even in the absence of any ODN in the bulk of solution. Homopurine ODNs did not form these two-dimensional (2D) condensed monolayers under the same conditions. A preliminary thermodynamic analysis of the condensed ODN layers is presented.

Abiotic and Biotic Formation of Amino Acids in the Enceladus Ocean.

Science.gov (United States)

Steel, Elliot L; Davila, Alfonso; McKay, Christopher P

2017-09-01

The active plume at Enceladus' south pole makes the indirect sampling of its global ocean possible. The partially resolved chemistry of the plume, which points to conditions that are seemingly compatible with life, has made orbital sampling missions a priority. We present a conceptual model of energy flux, hydrothermal H 2 production, and both abiotic and biotic production of amino acids. Based on the energy flux observed at the south pole and the inferred internal hydrothermal activity, we estimate an H 2 production of 0.6-34 mol/s from serpentinization, sufficient to sustain abiotic and biotic amino acid synthesis of 1.6-87 and 1-44 g/s, respectively. Two-dimensional (2D) numerical simulations of the hydrothermal vent suggest that the vent fluids could reach the ice-water boundary in less than 11-55 days for a 50 km deep ocean diluted by ambient ocean water 10 to 1. Concentrations of glycine, alanine, α-amino isobutyric acid, and glutamic acid in the plume and in the ambient ocean could all be above 0.01 μM just due to abiotic production. Biological synthesis, if occurring, could produce a maximum of 90 μM concentrations of amino acids based on a methanogenic ecosystem consuming H 2 and CO 2 . Racemization timescales in the ocean are short compared with production timescales. Thus, no enantiomeric excess is expected in the ambient ocean, and if biology is present, enantiomeric excess at the vent fluids is expected to be less than 10% in the plume. From vent H 2 concentrations of 7.8 mM (e.g., Lost City) and assuming complete H 2 use and conversion to chemical energy by methanogens, cell production is estimated. Annual biomass production in the methanogenic-based biology model is 4 × 10 4 -2 × 10 6 kg/year. This corresponds to cell concentrations ∼10 9 cells/cm 3 in the vents and ∼10 8 cells/cm 3 in the plume, and when diluted into the ambient ocean, we predict cell concentrations of 80-4250 cells/cm 3 . Key Words: Abiotic organic

Maintaining steam/condensate lines

International Nuclear Information System (INIS)

Russum, S.A.

1992-01-01

Steam and condensate systems must be maintained with the same diligence as the boiler itself. Unfortunately, they often are not. The water treatment program, critical to keeping the boiler at peak efficiency and optimizing operating life, should not stop with the boiler. The program must encompass the steam and condensate system as well. A properly maintained condensate system maximizes condensate recovery, which is a cost-free energy source. The fuel needed to turn the boiler feedwater into steam has already been provided. Returning the condensate allows a significant portion of that fuel cost to be recouped. Condensate has a high heat content. Condensate is a readily available, economical feedwater source. Properly treated, it is very pure. Condensate improves feedwater quality and reduces makeup water demand and pretreatment costs. Higher quality feedwater means more reliable boiler operation

SYNTHESIS OF FLAVANONE-6-CARBOXYLIC ACID DERIVATIVES FROM SALICYLIC ACID DERIVATIVE

Directory of Open Access Journals (Sweden)

Muhammad Idham Darussalam Mardjan

2012-02-01

Full Text Available Synthesis of flavanone-6-carboxylic acid derivatives had been conducted via the route of chalcone. The synthesis was carried out from salicylic acid derivative, i.e. 4-hydroxybenzoic acid, via esterification, Fries rearrangement, Claisen-Schmidt condensation and 1,4-nucleophilic addition reactions. Structure elucidation of products was performed using FT-IR, 1H-NMR, GC-MS and UV-Vis spectrometers. Reaction of 4-hydroxybenzoic acid with methanol catalyzed with sulfuric acid produced methyl 4-hydroxybenzoate in 87% yield. The acid-catalyzed-acetylation of the product using acetic anhydride gave methyl 4-acetoxybenzoate in 75% yield. Furthermore, solvent-free Fries rearrangement of methyl 4-acetoxybenzoate in the presence of AlCl3 produced 3-acetyl-4-hydroxybenzoic acid as the acetophenone derivatives in 67% yield. Then, Claisen-Schmidt condensation of the acetophenone and benzaldehyde derivatives of p-anisaldehyde and veratraldehyde in basic condition gave 2'-hydroxychalcone-5'-carboxylic acid derivatives  in 81 and 71 % yield, respectively. Finally, the ring closure reaction of the chalcone yielded the corresponding flavanone-6-carboxylic acids in 67 and 59% yield, respectively.

The discovery of new deep-sea hydrothermal vent communities in the southern ocean and implications for biogeography.

Directory of Open Access Journals (Sweden)

Alex D Rogers

2012-01-01

Full Text Available Since the first discovery of deep-sea hydrothermal vents along the Galápagos Rift in 1977, numerous vent sites and endemic faunal assemblages have been found along mid-ocean ridges and back-arc basins at low to mid latitudes. These discoveries have suggested the existence of separate biogeographic provinces in the Atlantic and the North West Pacific, the existence of a province including the South West Pacific and Indian Ocean, and a separation of the North East Pacific, North East Pacific Rise, and South East Pacific Rise. The Southern Ocean is known to be a region of high deep-sea species diversity and centre of origin for the global deep-sea fauna. It has also been proposed as a gateway connecting hydrothermal vents in different oceans but is little explored because of extreme conditions. Since 2009 we have explored two segments of the East Scotia Ridge (ESR in the Southern Ocean using a remotely operated vehicle. In each segment we located deep-sea hydrothermal vents hosting high-temperature black smokers up to 382.8°C and diffuse venting. The chemosynthetic ecosystems hosted by these vents are dominated by a new yeti crab (Kiwa n. sp., stalked barnacles, limpets, peltospiroid gastropods, anemones, and a predatory sea star. Taxa abundant in vent ecosystems in other oceans, including polychaete worms (Siboglinidae, bathymodiolid mussels, and alvinocaridid shrimps, are absent from the ESR vents. These groups, except the Siboglinidae, possess planktotrophic larvae, rare in Antarctic marine invertebrates, suggesting that the environmental conditions of the Southern Ocean may act as a dispersal filter for vent taxa. Evidence from the distinctive fauna, the unique community structure, and multivariate analyses suggest that the Antarctic vent ecosystems represent a new vent biogeographic province. However, multivariate analyses of species present at the ESR and at other deep-sea hydrothermal vents globally indicate that vent biogeography is more

Enhanced Condensation Heat Transfer

Science.gov (United States)

Rose, John Winston

The paper gives some personal observations on various aspects of enhanced condensation heat transfer. The topics discussed are external condensation (horizontal low-finned tubes and wire-wrapped tubes), internal condensation (microfin tubes and microchannels) and Marangoni condensation of binary mixtures.

Variations in deep-sea hydrothermal vent communities on the Mid-Atlantic Ridge near the Azores plateau

Science.gov (United States)

Desbruyères, D.; Biscoito, M.; Caprais, J.-C.; Colaço, A.; Comtet, T.; Crassous, P.; Fouquet, Y.; Khripounoff, A.; Le Bris, N.; Olu, K.; Riso, R.; Sarradin, P.-M.; Segonzac, M.; Vangriesheim, A.

2001-05-01

Near the Azores Triple Junction as the Azores Plateau is approached, the ridge axis becomes shallower; its depth decreases from ca. 2400 m in the R AINBOW vent field (36°13'N) to ca. 850 m in the M ENEZ G WEN vent field (37°35'N). In this area, extensive mussel beds of the mytilid Bathymodiolus azoricus dominate the hydrothermal vent fauna, along with populations of three shrimps ( Rimicaris exoculata, Mirocaris fortunata and Chorocaris chacei). The main physical and chemical characteristics of the vent habitat were studied by discrete sampling, in situ analysis and sediment trap moorings. The vent fauna is distributed along a variable band where the vent fluids and seawater mix, with R. exoculata living in the most concentrated areas and Bathymodiolus azoricus in the most diluted zones. Various non-endemic species live at the border of the vent field. The variations observed in structure and composition of the communities along the depth gradient are most likely due to changes in vent fluid toxicity (metallic and sulphide content) and suspended mineral particles, which render the fluids harsher for species living there. The main faunal differences observed between L UCKY S TRIKE and M ENEZ G WEN hydrothermal fields are due to an impoverishment in the hydrothermal endemic species and to the penetration of bathyal species. The comparison of the three studied vent fields suggests the existence of a succession of several biogeographic islands rather than a single province.

Arsenic bioaccumulation and biotransformation in deep-sea hydrothermal vent organisms from the PACMANUS hydrothermal field, Manus Basin, PNG

Science.gov (United States)

Price, Roy E.; Breuer, Christian; Reeves, Eoghan; Bach, Wolfgang; Pichler, Thomas

2016-11-01

As-Bet (42% As-Bet compared to 48% AsIII and 10% AsV), suggesting As-Bet is a metabolite. Trace arsenosugar (SO4-sug) was observed in digestive gland and gills only. The other snail, I. nautilei, was also dominated by AsIII and AsV in digestive glands (82, 10%) and gills (80, 10%), with 6-9% As-Bet, but its muscle contained 62% As-Bet and 32% AsIII, with 7% trimethylarsoniopropionate (TMAP). Trace dimethylarsinic acid (DMAV) was observed in its gills, and trace TMAP and arsenocholine (AC) was observed in digestive glands. The mussel B. manusensis was dominated by As-Bet in all three tissue types. Digestive gland and gills contained 22% AsIII, 5-10% AsV, 20-25% DMAV, along with some TMAP and tetramethylarsonium ion (TETRA). However, the muscle contained significantly more As-Bet (91.6%), with the only other species being AsIII (8.4%). Unfortunately, as is often the case in bioaccumulation and biotransformation studies, extraction efficiencies were low, limiting any rigorous interpretation of arsenic biotransformation patterns. Through process of elimination, we suggest that arsenosugars may be synthesized by H2S-oxidizing chemotrophic microbial mats, ultimately leading to the syntheses of As-Bet within vent organisms. However, because As-sugs rarely occur in deep-sea vent organisms, As-Bet, as well as TMAP, AC, and TETRA could also potentially be synthesized directly by the "Edmonds" pathway, the proposed arseno-analog to amino acid formation, without the necessity for arsenosugar formation as an intermediate. Future research should endeavor for more comprehensive extraction of organoarsenicals.

Analysis of Gas Vent System in Overseas LILW Disposal Facilities

Energy Technology Data Exchange (ETDEWEB)

Kim, Ju Yub; Kim, Ju Youl [FNC Technology Co., Yongin (Korea, Republic of); Jung, Hae Ryong; Ha, Jae Chul [Korea Radioactive Waste Management Corporation, Daejeon (Korea, Republic of)

2012-05-15

A Low- and Intermediate-Level Radioactive Waste (LILW) disposal facility is currently under construction in Korea. It is located in the aquifer, 80{approx}130 m below the ground surface. Thus, it is expected that disposal facility will be saturated after closure and various gases will be generated from metal corrosion, microbial degradation of organic materials and radiolysis. Generated gases will move up to the upper part of the silo, and it will increase the pressure of the silo. Since the integrity of the engineered barrier could be damaged, development of effective gas vent system which can prevent the gas accumulation in the silo is essential. In order to obtain basic data needed to develop site-specific gas vent system, gas vent systems of Sweden, Finland and Switzerland, which have the disposal concept of underground facility, were analyzed

Genetic diversity of archaea in deep-sea hydrothermal vent environments.

OpenAIRE

Takai, K; Horikoshi, K

1999-01-01

Molecular phylogenetic analysis of naturally occurring archaeal communities in deep-sea hydrothermal vent environments was carried out by PCR-mediated small subunit rRNA gene (SSU rDNA) sequencing. As determined through partial sequencing of rDNA clones amplified with archaea-specific primers, the archaeal populations in deep-sea hydrothermal vent environments showed a great genetic diversity, and most members of these populations appeared to be uncultivated and unidentified organisms. In the...

Venting processes: Effects on the vicinity

International Nuclear Information System (INIS)

Hattwig, M.

1980-01-01

In the case of venting as a protective measure against explosions a dangerous pressure wave and a large flame must be expected in the neighbourhood of the vent. Moreover the recoil force which is exerted on the protected vessel can be the cause for the destruction of the plant. Therefore experiments have been made on the dependence of the pressure wave and the recoil force from well-known or easily determinable parameters. The results of the investigations allow the estimation of the maximum overpressure which must be expected at a given point outside the vessel, if the reduced explosion pressure which will be reached in the interior of the vessel is known. Beyond that it could be shown that the maximum recoil force is nearly always considerably smaller than the value given by theory. Only very rarely the theoretical value is reached. Therefore it is totally sufficient for practical purposes when the maximum recoil to be expected is calculated from the theoretical equation. (orig.) [de

MAVEN Contamination Venting and Outgassing Analysis

Science.gov (United States)

Petro, Elaine M.; Hughes, David W.; Secunda, Mark S.; Chen, Philip T.; Morrissey, James R.; Riegle, Catherine A.

2014-01-01

Mars Atmosphere and Volatile EvolutioN (MAVEN) is the first mission to focus its study on the Mars upper atmosphere. MAVEN will study the evolution of the Mars atmosphere and climate, by examining the conduit through which the atmosphere has to pass as it is lost to the upper atmosphere. An analysis was performed for the MAVEN mission to address two distinct concerns. The first goal of the analysis was to perform an outgassing study to determine where species outgassed from spacecraft materials would redistribute to and how much of the released material might accumulate on sensitive surfaces. The second portion of the analysis serves to predict what effect, if any, Mars atmospheric gases trapped within the spacecraft could have on instrument measurements when re-released through vents. The re-release of atmospheric gases is of interest to this mission because vented gases from a higher pressure spacecraft interior could bias instrument measurements of the Mars atmosphere depending on the flow rates and directions.

CFD Simulation of rigid venting of the containment of a BWR-5 Mark-II reactor

International Nuclear Information System (INIS)

Galindo G, I. F.; Vazquez B, A. K.; Velazquez E, L.; Tijerina S, F.; Tapia M, R.

2016-09-01

In conditions of prolonged loss of external energy or a severe accident, venting to the atmosphere is an alternative to prevent overpressure and release of fission products from the primary containment of a nuclear reactor. Due to the importance of flow determination through rigid vents, a computational fluid dynamics (CFD) model is proposed to verify the capacity of rigid vents in the primary containment of a boiling water reactor (BWR) under different operating conditions (pressure, temperature and compositions of the fluids). The model predicts and provides detailed information on variables such as mass flow and velocity of the venting gases. In the proposed model the primary containment gas is vented to the atmosphere via rigid vents (pipes) from the dry and wet pit. Is assumed that the container is pressurized because is in a defined scenario, and at one point the venting is open and the gas released into the atmosphere. The objective is to characterize the flow and validate the CFD model for the overpressure conditions that occur in an accident such as a LOCA, Sbo, etc. The model is implemented with Ansys-Fluent general-purpose CFD software based on the geometry of the venting ducts of the containment of a BWR. The model is developed three-dimensional and resolves at steady state for compressible flow and includes the effects of the turbulence represented by the Reynolds stress model. The CFD results are compared with the values of a one-dimensional and isentropic model for compressible flow. The relative similarity of results leads to the conclusion that the proposed CFD model can help to predict the rigid venting capacity of the containment of a BWR, however more information is required for full validation of the proposed model. (Author)

40 CFR 63.487 - Batch front-end process vents-reference control technology.

Science.gov (United States)

2010-07-01

... § 63.487 Batch front-end process vents—reference control technology. (a) Batch front-end process vents... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Batch front-end process vents-reference control technology. 63.487 Section 63.487 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...

PERFORMANCE EVALUATION OF EMPIRICAL MODELS FOR VENTED LEAN HYDROGEN EXPLOSIONS

OpenAIRE

Anubhav Sinha; Vendra C. Madhav Rao; Jennifer X. Wen

2017-01-01

Explosion venting is a method commonly used to prevent or minimize damage to an enclosure caused by an accidental explosion. An estimate of the maximum overpressure generated though explosion is an important parameter in the design of the vents. Various engineering models (Bauwens et al., 2012, Molkov and Bragin, 2015) and European (EN 14994 ) and USA standards (NFPA 68) are available to predict such overpressure. In this study, their performance is evaluated using a number of published exper...

Blast venting through blanket material in the HYLIFE ICF reactor

International Nuclear Information System (INIS)

Liu, J.C.; Peterson, P.F.; Schrock, V.E.

1992-01-01

This work presents a numerical study of blast venting through various blanket configurations in the HYLIFE ICF reactor design. The study uses TSUNAMI -- a multi-dimensional, high-resolution, shock capturing code -- to predict the momentum exchange and gas dynamics for blast venting in complex geometries. In addition, the study presents conservative predictions of wall loading by gas shock and impulse delivered to the protective liquid blanket. Configurations used in the study include both 2700 MJ and 350 MJ fusion yields per pulse for 5 meter and 3 meter radius reactor chambers. For the former, an annular jet array is used for the blanket geometry, while in the latter, both annular jet array as well as slab geometries are used. Results of the study indicate that blast venting and wall loading may be manageable in the HYLIFE-II design by a judicious choice of blanket configuration

LH2 tank pressure control by thermodynamic vent system (TVS) at zero gravity

Science.gov (United States)

Wang, B.; Huang, Y. H.; Chen, Z. C.; Wu, J. Y.; Li, P.; Sun, P. J.

2017-02-01

Thermodynamic vent system (TVS) is employed for pressure control of propellant tanks at zero gravity. An analytical lumped parameter model is developed to predict pressure variation in an 18.09 m3 liquid hydrogen tank equipped with TVS. Mathematical simulations are carried out assuming tank is filled up to 75% volume (liquid mass equals to 945 kg) and is subjected to heat flux of 0.76 W/m2. Tank pressure controls at 165.5-172.4, 165.5-179.3 and 165.5-182.2 kPa are compared with reference to number of vent cycles, vent duration per cycle and loss of hydrogen. Analysis results indicate that the number of vent cycles significantly decreases from 62 to 21 when tank pressure control increases from 6.9 to 20.4 kPa. Also, duration of vent cycle increases from 63 to 152 and cycle duration decreases from 3920 to 3200 s. Further, the analysis result suggests that LH2 evaporation loss per day decreases from 0.17 to 0.14%. Based on the results of analysis, TVS is found effective in controlling the propellant tank pressure in zero gravity.

Severe accident consequence mitigation by filtered containment venting at Canadian nuclear power plants

International Nuclear Information System (INIS)

Lebel, Luke S.; Morreale, Andrew C.; Korolevych, Volodymyr; Brown, Morgan J.; Gyepi-Garbrah, Sam

2017-01-01

Highlights: • Use of filtered containment venting during a severe accident assessed. • Severe accident simulations performed using MAAP-CANDU and ADDAM. • Flow capacity, initiation protocols, efficiency, mass and thermal loading evaluated. • Efficient, robust system drastically reduces accident consequences. - Abstract: Having the capability to use filtered containment venting during a severe nuclear accident can significantly reduce its overall consequences. This study employs the MAAP-CANDU severe accident analysis code and the ADDAM atmospheric dispersion code to study the progression of: an unmitigated station blackout accident at a generic pressurized heavy water reactor, the release of radioactive material into the environment, the subsequent dispersion of the fission products through the atmosphere and the subsequent consequences (evacuation radius). The goal is to evaluate the application of filtered venting as an accident mitigation technology. Several aspects of filtered containment venting system design, like flow capacity, initiation protocols, filter efficiency, mass loading, and thermal loading are considered. An efficient and robust filtered containment venting system can reduce the amount of radiological materials emitted during an accident by 25 times or more, and as a result considerably reduce the off-site consequences of an accident.

Dynamics of hydrocarbon vents: Focus on primary porosity

Science.gov (United States)

Johansen, C.; Shedd, W.; Abichou, T.; Pineda-Garcia, O.; Silva, M.; MacDonald, I. R.

2012-12-01

This study investigated the dynamics of hydrocarbon release by monitoring activity of a single vent at a 1215m deep site in the Gulf of Mexico (GC600). An autonomous camera, deployed by the submersible ALVIN, was programmed to capture a close-up image every 4 seconds for approximately 3.5 hours. The images provided the ability to study the gas hydrate outcrop site (that measured 5.2x16.3cm3) in an undisturbed state. The outcrop included an array of 38 tube-like vents through which dark brown oil bubbles are released at a rate ranging from 8 bubbles per minute to 0 bubbles per minute. The average release of bubbles from all the separate vents was 59.5 bubbles per minute, equating the total volume released to 106.38cm per minute. The rate of bubble release decreased toward the end of the observation interval, which coincided approximately with the tidal minimum. Ice worms (Hesiocaeca methanicola, Desbruyères & Toulmond, 1998) were abundant at the vent site. The image sequence showed the ice-worms actively moving in and out of burrows in the mound. It has been speculated that Hesiocaeca methanicola contribute to gas hydrate decomposition by creating burrows and depressions in the gas hydrate matrix (Fisher et al, 2000). Ice worm burrows could generate pathways for the passage of oil and gas through the gas hydrate mound. Gas hydrates commonly occur along active and/or passive continental margins (Kennicutt et al, 1988a). The release of oil and gas at this particular hydrocarbon seep site is along a passive continental margin, and controlled primarily by active salt tectonics as opposed to the movement of continental tectonic plates (Salvador, 1987). We propose a descriptive model governing the release of gas and oil from deep sub-bottom reservoirs at depths of 3000-5000m (MacDonald, 1998), through consolidated and unconsolidated sediments, and finally through gas hydrate deposits at the sea floor. The oil and gas escape from the source rock and/or reservoir through

Process for retention of iodine and aerosols during containment venting

International Nuclear Information System (INIS)

Eckardt, B.; Betz, R.; Greger, G.U.; Werner, K.D.

1990-05-01

A process for retention of the majority of aerosols and iodine during containment venting was optimized. For this purpose, sections of a two-stage process comprising a venturi scrubber and a metal-fiber filter demister were tested under containment venting conditions assumed to prevail during a hypothetical core - melt accident and optimized with a view to achieving high decontamination factors and loading capacity while minimizing the size of the process. The loading and retention tests performed in a scrubber operating pressure range between 1 and 10 bar, at temperatures from 50 to 200degC (also boiling pools) and in air and steam atmospheres. Under these unfavorable conditions for aerosol retention, the retention efficiencies were determined at various flow rates with soluble and non-soluble aerosols as well as gaseous iodine. The retention efficiencies for BaSO 4 , uranine and SnO 2 aerosols were determined to be 99.95% to 99.99% for venturi scrubbers with metal-fiber filter demister. The retention efficiency for elemental iodine was determined to be ≥99% including revolatization effects over a 24-hour operating period. The high loading capacity of the venturi scrubber unit was verified after process modifications with various aerosols. The use of full-scale process section together with the best possible simulation of containment venting conditions by the test parameters ensured that the results can be transferred to real venting equipment. The aim of ensuring the retention of the majority of the aerosol-borne activity and of elemental iodine activity and minimizing the process size was clearly achieved and verified by means of this optimized venting equipment under an extremely wide range of hypothetical core-melt accident conditions. (orig.) With 17 refs., 3 tabs., 35 annexes [de

An abyssal mobilome: viruses, plasmids and vesicles from deep-sea hydrothermal vents.

Science.gov (United States)

Lossouarn, Julien; Dupont, Samuel; Gorlas, Aurore; Mercier, Coraline; Bienvenu, Nadege; Marguet, Evelyne; Forterre, Patrick; Geslin, Claire

2015-12-01

Mobile genetic elements (MGEs) such as viruses, plasmids, vesicles, gene transfer agents (GTAs), transposons and transpovirions, which collectively represent the mobilome, interact with cellular organisms from all three domains of life, including those thriving in the most extreme environments. While efforts have been made to better understand deep-sea vent microbial ecology, our knowledge of the mobilome associated with prokaryotes inhabiting deep-sea hydrothermal vents remains limited. Here we focus on the abyssal mobilome by reviewing accumulating data on viruses, plasmids and vesicles associated with thermophilic and hyperthermophilic Bacteria and Archaea present in deep-sea hydrothermal vents. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

The role of ß-ketoacyl-acyl carrier protein synthase III in the condensation steps of fatty acid biosynthesis in sunflower

DEFF Research Database (Denmark)

González-Mellado, Damián; von Wettstein, Penny; Garcés, Rafael

2010-01-01

The ß-ketoacyl-acyl carrier protein synthase III (KAS III; EC 2.3.1.180) is a condensing enzyme catalyzing the initial step of fatty acid biosynthesis using acetyl-CoA as primer. To determine the mechanisms involved in the biosynthesis of fatty acids in sunflower (Helianthus annuus L.) developing...... seeds, a cDNA coding for HaKAS III (EF514400) was isolated, cloned and sequenced. Its protein sequence is as much as 72% identical to other KAS III-like ones such as those from Perilla frutescens, Jatropha curcas, Ricinus communis or Cuphea hookeriana. Phylogenetic study of the HaKAS III homologous...... proteins infers its origin from cyanobacterial ancestors. A genomic DNA gel blot analysis revealed that HaKAS III is a single copy gene. Expression levels of this gene, examined by Q-PCR, revealed higher levels in developing seeds storing oil than in leaves, stems, roots or seedling cotyledons...

Bacterial and Archaeal Community Dynamics at CO2-RICH Shallow-Sea Hydrothermal Vents (panarea, Italy)

Science.gov (United States)

Schubotz, F.; Huang, C.; Meyerdierks, A.; Amend, J.; Price, R. E.; Amann, R.; Hinrichs, K.; Summons, R. E.

2013-12-01

Shallow marine hydrothermal vents are highly dynamic systems with unique habitats that can support both chemosynthetic and photosynthetic communities at steep temperature and geochemical gradients. Here, we present a combined organic geochemical and microbiological approach to describe the microbial community composition and their metabolism at the CO2-rich shallow hydrothermal vents off Panarea Island, in Sicily. We investigated two contrasting hydrothermal environments: Hot Lake, a depression filled with hydrothermal fluids diffusing gradually out of the seafloor, with temperatures ranging from 40 to 70°C, and Blackpoint, a site with vigorous venting of hydrothermal gasses and fluids with temperatures as high as 135°C. At Hot Lake, Bacteria dominate the microbial community composition in the sediments. 16S rRNA clone libraries revealed Bacteriodetes-, Epsilonproteobacteria- and Deltaproteobacteria-related sequences as the most abundant members. Bacterial intact polar membrane lipids (IPLs) were dominated by the non-phosphorous containing ornithine lipids throughout all depths, indicating an important role of this aminolipid at elevated temperatures and/or low pH. At Hot Lake, archaeal IPLs were comprised mainly of glycosidic tetraethers and increased up to 20% of total IPLs with increasing temperature and depth. At the same site, archaeal 16S rRNA clone libraries were mainly comprised of Euryarchaea-affiliated sequences; crenarchaeotal sequences were only found in deeper sediment layers with temperatures of ca. 70°C. In contrast to Hot Lake, Archaea dominated sediments at the much hotter site at Blackpoint. Here, novel methylated H-shaped archaeal tetraethers, with multiple sugars as head groups, were the most abundant membrane lipids. Reports on these lipids in cultures are very limited, but their abundant occurrence at elevated temperatures suggests an important role in membrane homeostastis in thermophilic Archaea. Stable carbon isotope values of -35‰ to

In situ Raman-based detections of the hydrothermal vent and cold seep fluids

Science.gov (United States)

Zhang, Xin; Du, Zengfeng; Zheng, Ronger; Luan, Zhendong; Qi, Fujun; Cheng, Kai; Wang, Bing; Ye, Wangquan; Liu, Xiaorui; Chen, Changan; Guo, Jinjia; Li, Ying; Yan, Jun

2016-04-01

Hydrothermal vents and cold seeps, and their associated biological communities play an important role in global carbon and sulphur biogeochemical cycles. Most of the studies of fluid composition geochemistry are based on recovered samples, both with gas-tight samplers and as open specimens, but the in situ conditions are difficult to maintain in recovered samples. Determination in situ of the chemical signals of the emerging fluids are challenging due to the high pressure, often strongly acidic and temperature in which few sensors can survive. Most of those sensors used so far are based on electrochemistry, and can typically detect only a few chemical species. Here we show that direct measurement of critical chemical species of hydrothermal vents and cold seeps can be made rapidly and in situ by means of a new hybrid version of earlier deep-sea pore water Raman probe carried on the ROV (Remote Operated Vehicle) Faxian. The fluid was drawn through the probe by actuating a hydraulic pump on the ROV, and measured at the probe optical cell through a sapphire window. We have observed the concentrations of H2S, HS-, SO42-, HSO4-, CO2, and H2 in hydrothermal vent fluids from the Pacmanus and Desmos vent systems in the Manus back-arc basin, Papua New Guinea. Two black smokers (279° C and 186° C) at the Pacmanus site showed the characteristic loss of SO42-, and the increase of CO2 and well resolved H2S and HS- peaks. At the white smoker of Onsen site the strong HSO4-peak observed at high temperature quickly dropped with strong accompanying increase of SO42-and H2 peaks when the sample contained in the Raman sensing cell was removed from the hot fluid due to rapid thermal deprotonation. We report here also the finding of a new lower temperature (88° C) white smoker "Kexue" field at the Desmos site with strong H2S, HS- and CO2 signals. We also have detected the concentrations of CH4,H2S, HS-, SO42-, and S8 in cold seep fluids and the surrounding sediment pore water from

A condensation experiment in the accumulated conditions of noncondensable gas in a vertical tube

International Nuclear Information System (INIS)

Lee, Kwon Yeong; Kim, Moo Hwan

2005-01-01

accumulated noncondensable gas in the vertical tube. The experimental facility consisted of steam generation part, steam flow rate control part, steam-noncondensable gas mixing part, test section with a condensing tube submerged in a water pool, and venting and draining part. The heat flux and heat transfer coefficient were estimated from two temperature differences between inner and outer wall temperature, and between inner wall and mixture bulk temperature. It was estimated that the system uncertainty could be mainly originated from the uncertainty of inner wall temperature. So the method using heater wire was developed to correct the depth of thermocouples inserted to measure the inner wall temperatures. The local condensation heat transfer coefficients inside the vertical tube were measured in the presence of accumulated nitrogen. The heat transfer coefficients decreased as the nitrogen volumetric fraction inside the condenser tube increased. The average heat flux increased as the inlet temperature and the inlet mixture Reynolds number increased. It could be roughly estimated the distribution of nitrogen inside the vertical tube from the local condensation heat transfer coefficients. (authors)

Feasibility and Safety Assessment for Advanced Reactor Concepts Using Vented Fuel

International Nuclear Information System (INIS)

Klein, Andrew; Lenhof, Renae; Deason, Wesley; Harter, Jackson

2015-01-01

Recent interest in fast reactor technology has led to renewed analysis of past reactor concepts such as Gas Fast Reactors and Sodium Fast Reactors. In an effort to make these reactors more economic, the fuel is required to stay in the reactor for extended periods of time; the longer the fuel stays within the core, the more fertile material is converted into usable fissile material. However, as burnup of the fuel-rod increases, so does the internal pressure buildup due to gaseous fission products. In order to reach the 30 year lifetime requirements of some reactor designs, the fuel pins must have a vented-type design to allow the buildup of fission products to escape. The present work aims to progress the understanding of the feasibility and safety issues related to gas reactors that incorporate vented fuel. The work was separated into three different work-scopes: 1. Quantitatively determine fission gas release from uranium carbide in a representative helium cooled fast reactor; 2. Model the fission gas behavior, transport, and collection in a Fission Product Vent System; and, 3. Perform a safety analysis of the Fission Product Vent System. Each task relied on results from the previous task, culminating in a limited scope Probabilistic Risk Assessment (PRA) of the Fission Product Vent System. Within each task, many key parameters lack the fidelity needed for comprehensive or accurate analysis. In the process of completing each task, the data or methods that were lacking were identified and compiled in a Gap Analysis included at the end of the report.

Feasibility and Safety Assessment for Advanced Reactor Concepts Using Vented Fuel

Energy Technology Data Exchange (ETDEWEB)

Klein, Andrew [Oregon State Univ., Corvallis, OR (United States). Nuclear Engineering and Radiation Health Physics; Matthews, Topher [Oregon State Univ., Corvallis, OR (United States); Lenhof, Renae [Oregon State Univ., Corvallis, OR (United States); Deason, Wesley [Oregon State Univ., Corvallis, OR (United States); Harter, Jackson [Oregon State Univ., Corvallis, OR (United States)

2015-01-16

Recent interest in fast reactor technology has led to renewed analysis of past reactor concepts such as Gas Fast Reactors and Sodium Fast Reactors. In an effort to make these reactors more economic, the fuel is required to stay in the reactor for extended periods of time; the longer the fuel stays within the core, the more fertile material is converted into usable fissile material. However, as burnup of the fuel-rod increases, so does the internal pressure buildup due to gaseous fission products. In order to reach the 30 year lifetime requirements of some reactor designs, the fuel pins must have a vented-type design to allow the buildup of fission products to escape. The present work aims to progress the understanding of the feasibility and safety issues related to gas reactors that incorporate vented fuel. The work was separated into three different work-scopes: 1. Quantitatively determine fission gas release from uranium carbide in a representative helium cooled fast reactor; 2. Model the fission gas behavior, transport, and collection in a Fission Product Vent System; and, 3. Perform a safety analysis of the Fission Product Vent System. Each task relied on results from the previous task, culminating in a limited scope Probabilistic Risk Assessment (PRA) of the Fission Product Vent System. Within each task, many key parameters lack the fidelity needed for comprehensive or accurate analysis. In the process of completing each task, the data or methods that were lacking were identified and compiled in a Gap Analysis included at the end of the report.

Summary of measurements with MicroVent

DEFF Research Database (Denmark)

Dreau, Jerome Le; Heiselberg, Per Kvols; Jensen, Rasmus Lund

This summary presents the main results when MicroVent is used in the cooling case, without heat recovery. Experiments have thus been performed with relatively low inlet air temperature (below 15°C). Different solutions have been compared to decrease the risk of draught in the occupied zone: ‐ usi...

Inerting of a Vented Aircraft Fuel Tank Test Article with Nitrogen-Enriched Air

National Research Council Canada - National Science Library

Burns, Michael

2001-01-01

...) required to inert a vented aircraft fuel tank. NEA, generated by a hollow fiber membrane gas separation system, was used to inert a laboratory fuel tank with a single vent on top designed to simulate a transport category airplane fuel tank...

Primary Formation Path of Formaldehyde in Hydrothermal Vents

Science.gov (United States)

Inaba, Satoshi

2018-03-01

Formaldehyde is abundant in the universe and one of the fundamental molecules for life. Hydrothermal vents produce a substantial amount of hydrogen molecules by serpentinization and promote reductive reactions of single carbon compounds. The abundance of formaldehyde is expected to be low due to the high Gibbs free energy in hydrothermal vents. We consider two competing formation pathways of formaldehyde: (1) the reduction of CO by H2 and (2) the reduction of HCOOH by H2 to form a methanediol, followed by the dehydration of the methanediol. We performed a number of quantum chemical simulations to examine the formation of formaldehyde in the gas phase as well as in aqueous solution. The energy barrier is significantly reduced by the catalytic effect of water molecules in aqueous solution and becomes lowest when a water cluster consisted of 5 water molecules catalyzes the reduction. The energy barrier to form a methanediol by the reduction of HCOOH is lower by 17.5 kcal/mol than that to form a formaldehyde by the reduction of CO. Considering the low energy barrier to dehydrate methanediol, the primary pathway to form formaldehyde in hydrothermal vents is concluded to be the reduction of HCOOH by H2, followed by the dehydration of methanediol.

Potential Flammable Gas Explosion in the TRU Vent and Purge Machine

International Nuclear Information System (INIS)

Vincent, A

2006-01-01

The objective of the analysis was to determine the failure of the Vent and Purge (V and P) Machine due to potential explosion in the Transuranic (TRU) drum during its venting and/or subsequent explosion in the V and P machine from the flammable gases (e.g., hydrogen and Volatile Organic Compounds [VOCs]) vented into the V and P machine from the TRU drum. The analysis considers: (a) increase in the pressure in the V and P cabinet from the original deflagration in the TRU drum including lid ejection, (b) pressure wave impact from TRU drum failure, and (c) secondary burns or deflagrations resulting from excess, unburned gases in the cabinet area. A variety of cases were considered that maximized the pressure produced in the V and P cabinet. Also, cases were analyzed that maximized the shock wave pressure in the cabinet from TRU drum failure. The calculations were performed for various initial drum pressures (e.g., 1.5 and 6 psig) for 55 gallon TRU drum. The calculated peak cabinet pressures ranged from 16 psig to 50 psig for various flammable gas compositions. The blast on top of cabinet and in outlet duct ranged from 50 psig to 63 psig and 12 psig to 16 psig, respectively, for various flammable gas compositions. The failure pressures of the cabinet and the ducts calculated by structural analysis were higher than the pressure calculated from potential flammable gas deflagrations, thus, assuring that V and P cabinet would not fail during this event. National Fire Protection Association (NFPA) 68 calculations showed that for a failure pressure of 20 psig, the available vent area in the V and P cabinet is 1.7 to 2.6 times the required vent area depending on whether hydrogen or VOCs burn in the V and P cabinet. This analysis methodology could be used to design the process equipment needed for venting TRU waste containers at other sites across the Department of Energy (DOE) Complex

Geomicrobiology of Hydrothermal Vents in Yellowstone Lake: Phylogenetic and Functional Analysis suggest Importance of Geochemistry (Invited)

Science.gov (United States)

Inskeep, W. P.; Macur, R.; Jay, Z.; Clingenpeel, S.; Tenney, A.; Lavalvo, D.; Shanks, W. C.; McDermott, T.; Kan, J.; Gorby, Y.; Morgan, L. A.; Yooseph, S.; Varley, J.; Nealson, K.

2010-12-01

Yellowstone Lake (Yellowstone National Park, WY, USA) is a large, high-altitude, fresh-water lake that straddles the most recent Yellowstone caldera, and is situated on top of significant hydrothermal activity. An interdisciplinary study is underway to evaluate the geochemical and geomicrobiological characteristics of several hydrothermal vent environments sampled using a remotely operated vehicle, and to determine the degree to which these vents may influence the biology of this young freshwater ecosystem. Approximately six different vent systems (locations) were sampled during 2007 and 2008, and included water obtained directly from the hydrothermal vents as well as biomass and sediment associated with these high-temperature environments. Thorough geochemical analysis of these hydrothermal environments reveals variation in pH, sulfide, hydrogen and other potential electron donors that may drive primary productivity. The concentrations of dissolved hydrogen and sulfide were extremely high in numerous vents sampled, especially the deeper (30-50 m) vents located in the Inflated Plain, West Thumb, and Mary Bay. Significant dilution of hydrothermal fluids occurs due to mixing with surrounding lake water. Despite this, the temperatures observed in many of these hydrothermal vents range from 50-90 C, and elevated concentrations of constituents typically associated with geothermal activity in Yellowstone are observed in waters sampled directly from vent discharge. Microorganisms associated with elemental sulfur mats and filamentous ‘streamer’ communities of Inflated Plain and West Thumb (pH range 5-6) were dominated by members of the deeply-rooted bacterial Order Aquificales, but also contain thermophilic members of the domain Archaea. Assembly of metagenome sequence from the Inflated Plain vent biomass and to a lesser extent, West Thumb vent biomass reveal the importance of Sulfurihydrogenibium-like organisms, also important in numerous terrestrial geothermal

Multiple-vent programme to test the pressure suppression system

International Nuclear Information System (INIS)

Aust, E.; Schwan, H.; Vollbrandt, I.

1979-01-01

Three pre-tests with a multiple vent configuration have been performed at the GKSS pressure suppression test facility. First test results indicate significant chugging events with occur periodically with 0.4 to 0.2 Hz. These events appear simultaneously in less than 10 ms at the exit of the three vent pipes and cause pressure pulses in the range of 3 bar. This report gives a short description of the test facility and presents the boundary conditions of the test facility and presents the boundary conditions of the three pre-tests, test results and a first valuation of the experimental informations. (orig.) [de

Measurement of liquid-liquid equilibria for condensate + glycol and condensate + glycol + water systems

DEFF Research Database (Denmark)

Riaz, Muhammad; Kontogeorgis, Georgios; Stenby, Erling Halfdan

2011-01-01

,2-ethanediol (MEG) + condensate and MEG + water + condensate systems at temperatures from (275 to 323) K at atmospheric pressure. The condensate used in this work is a stabilized natural gas condensate from an offshore field in the North Sea. Compositional analysis of the natural gas condensate was carried out...... by gas chromatography, and detailed separation of individual condensate's components has been carried out. Approximately 85 peaks eluting before nonane were identified by their retention time. Peak areas were converted to mass fraction using 1-heptene as an internal standard. The components were divided...... into boiling range groups from hexane to nonane. Paraffinic (P), naphthenic (N), and aromatic (A) distributions were obtained for the boiling point fractions up to nonane. The average molar mass and the overall density of the condensate were measured experimentally. For the mutual solubility of MEG...

Low pressure lithium condensation

International Nuclear Information System (INIS)

Wadkins, R.P.; Oh, C.H.

1985-01-01

A low pressure experiment to evaluate the laminar film condensation coefficients of lithium was conducted. Some thirty-six different heat transfer tests were made at system pressures ranging from 1.3 to 26 Pa. Boiled lithium was condensed on the inside of a 7.6-cm (ID), 409 stainless-steel pipe. Condensed lithium was allowed to reflux back to the pool boiling region below the condensing section. Fourteen chromel/alumel thermocouples were attached in various regions of the condensing section. The thermocouples were initially calibrated with errors of less than one degree Celsius

Examining Design Factors for Safe and Effective Hydrogen Vents for Waste Packages

International Nuclear Information System (INIS)

Herrmann, R.C.

2009-01-01

The possibility of a nuclear renaissance, and the possibility of large scale new build to meet both the concerns of the environmental lobby and the economic imperatives created by the political hostage taking of unreliable fossil fuel markets throughout the world, coupled with the need to resolve issues still outstanding from a previous generation of wastes create the need for a widely accepted understanding of the needs for venting waste packages which are being prepared for term storage. In the US the technologies to immobilising the legacy wastes are being developed, in the UK the NDA is gearing up to decommission a range of sites and throughout Europe facilities are being demolished and the wastes taken to term storage. In several cases, the waste containers require venting, both to allow the thermal relief of the container during climatic variation and to allow the venting of generated gases from radiolysis, decomposition and corrosion of the contents, including Hydrogen and Hydrocarbons. The paper will examine the disparate demands of the market place, and propose strategies to rationalise the specification of filter breathers so that both producers and users have a common framework from which to determine their individual venting needs. Examining the mutually exclusive demands of permeability (affecting both pressure differential and Hydrogen diffusion) and filtration efficiency, the paper will explore economic solutions in an attempt to provide a framework against which the large number of waste containers requiring venting in the future can have their vent filters designed to meet both the best possible combination of efficiency and permeability, as well as exploring the limits of knowledge of corrosion of the filter media and suggesting strategies to tackle the possibility of the filter media failing before the waste container, and the consequences of such an event. (authors)

An Assessment for A Filtered Containment Venting Strategy Using Decision Tree Models

International Nuclear Information System (INIS)

Shin, Hoyoung; Jae, Moosung

2016-01-01

In this study, a probabilistic assessment of the severe accident management strategy through a filtered containment venting system was performed by using decision tree models. In Korea, the filtered containment venting system has been installed for the first time in Wolsong unit 1 as a part of Fukushima follow-up steps, and it is planned to be applied gradually for all the remaining reactors. Filtered containment venting system, one of severe accident countermeasures, prevents a gradual pressurization of the containment building exhausting noncondensable gas and vapor to the outside of the containment building. In this study, a probabilistic assessment of the filtered containment venting strategy, one of the severe accident management strategies, was performed by using decision tree models. Containment failure frequencies of each decision were evaluated by the developed decision tree model. The optimum accident management strategies were evaluated by comparing the results. Various strategies in severe accident management guidelines (SAMG) could be improved by utilizing the methodology in this study and the offsite risk analysis methodology

An Assessment for A Filtered Containment Venting Strategy Using Decision Tree Models

Energy Technology Data Exchange (ETDEWEB)

Shin, Hoyoung; Jae, Moosung [Hanyang University, Seoul (Korea, Republic of)

2016-10-15

In this study, a probabilistic assessment of the severe accident management strategy through a filtered containment venting system was performed by using decision tree models. In Korea, the filtered containment venting system has been installed for the first time in Wolsong unit 1 as a part of Fukushima follow-up steps, and it is planned to be applied gradually for all the remaining reactors. Filtered containment venting system, one of severe accident countermeasures, prevents a gradual pressurization of the containment building exhausting noncondensable gas and vapor to the outside of the containment building. In this study, a probabilistic assessment of the filtered containment venting strategy, one of the severe accident management strategies, was performed by using decision tree models. Containment failure frequencies of each decision were evaluated by the developed decision tree model. The optimum accident management strategies were evaluated by comparing the results. Various strategies in severe accident management guidelines (SAMG) could be improved by utilizing the methodology in this study and the offsite risk analysis methodology.

SLAC synchronous condenser

International Nuclear Information System (INIS)

Corvin, C.

1995-06-01

A synchronous condenser is a synchronous machine that generates reactive power that leads real power by 90 degrees in phase. The leading reactive power generated by the condenser offsets or cancels the normal lagging reactive power consumed by inductive and nonlinear loads at the accelerator complex. The quality of SLAC's utility power is improved with the addition of the condenser. The inertia of the condenser's 35,000 pound rotor damps and smoothes voltage excursions on two 12 kilovolt master substation buses, improving voltage regulation site wide. The condenser absorbs high frequency transients and noise in effect ''scrubbing'' the electric system power at its primary distribution source. In addition, the condenser produces a substantial savings in power costs. Federal and investor owned utilities that supply electric power to SLAC levy a monthly penalty for lagging reactive power delivered to the site. For the 1993 fiscal year this totaled over $285,000 in added costs for the year. By generating leading reactive power on site, thereby reducing total lagging reactive power requirements, a substantial savings in electric utility bills is achieved. Actual savings of $150,000 or more a year are possible depending on experimental operations

Technology Solutions Case Study: Evaluation of Passive Vents in New-Construction Multifamily Buildings

Energy Technology Data Exchange (ETDEWEB)

S. Puttagunta, S. Maxwell, D. Berger, and M. Zuluaga

2015-10-01

The Consortium for Advanced Residential Buildings (CARB) conducted research to gain more insight into passive vents. Because passive vents are meant to operate in a general environment of negative apartment pressure, the research assessed whether these negative pressures prevail through a variety of environmental conditions.

Increased diversity of sessile epibenthos at subtidal hydrothermal vents: seven hypotheses based on observations at Milos Island, Aegean Sea

Directory of Open Access Journals (Sweden)

Carlo Nike Bianchi

2011-06-01

Full Text Available Research on subtidal hydrothermal vent ecosystems at Milos, Hellenic Volcanic Arc (Aegean Sea, suggested that vent activity increased the species richness of sessile epibenthic assemblages. Based on 303 species found in 6 sites (3 close to vents, 3 farther away, the present paper uses correspondence analysis and species/samples curves to examine the species composition and richness of these assemblages. Differences due to vent proximity were more important than those due to bottom depth and distance from the shore. Diversity was confirmed to be higher near the vents, although none of the 266 species found at the vent sites can be considered as obligate vent-associated species. Seven different, although not mutually exclusive, hypotheses are discussed to explain the pattern of increased epibenthic species diversity at the vent sites, namely: (i vents represent an intermediate disturbance, inducing mortality by the emission of toxic fluids; (ii higher winter temperature allows for the occurrence of warm-water species, which add to the regional background; (iii venting disrupts the homogeneity of the water bottom layer, increasing bottom roughness and hence habitat heterogeneity; (iv deposition of minerals and enhanced bioconstruction by Ca enrichment increment habitat provision; (v fluid emission induces advective mechanisms that favour recruitment; (vi vents emit CO2, nutrients and trace elements that enhance primary productivity; and (vii bacterial chemosynthesis add to photosynthesis to provide a diversity of food sources for the fauna.

Subseafloor Microbial Life in Venting Fluids from the Mid Cayman Rise Hydrothermal System

Science.gov (United States)

Huber, J. A.; Reveillaud, J.; Reddington, E.; McDermott, J. M.; Sylva, S. P.; Breier, J. A.; German, C. R.; Seewald, J.

2012-12-01

In hard rock seafloor environments, fluids emanating from hydrothermal vents are one of the best windows into the subseafloor and its resident microbial community. The functional consequences of an extensive population of microbes living in the subseafloor remains unknown, as does our understanding of how these organisms interact with one another and influence the biogeochemistry of the oceans. Here we report the abundance, activity, and diversity of microbes in venting fluids collected from two newly discovered deep-sea hydrothermal vents along the ultra-slow spreading Mid-Cayman Rise (MCR). Fluids for geochemical and microbial analysis were collected from the Von Damm and Piccard vent fields, which are located within 20 km of one another, yet have extremely different thermal, geological, and depth regimes. Geochemical data indicates that both fields are highly enriched in volatiles, in particular hydrogen and methane, important energy sources for and by-products of microbial metabolism. At both sites, total microbial cell counts in the fluids ranged in concentration from 5 x 10 4 to 3 x 10 5 cells ml-1 , with background seawater concentrations of 1-2 x 10 4 cells ml-1 . In addition, distinct cell morphologies and clusters of cells not visible in background seawater were seen, including large filaments and mineral particles colonized by microbial cells. These results indicate local enrichments of microbial communities in the venting fluids, distinct from background populations, and are consistent with previous enumerations of microbial cells in venting fluids. Stable isotope tracing experiments were used to detect utilization of acetate, formate, and dissolve inorganic carbon and generation of methane at 70 °C under anaerobic conditions. At Von Damm, a putatively ultra-mafic hosted site located at ~2200 m with a maximum temperature of 226 °C, stable isotope tracing experiments indicate methanogenesis is occurring in most fluid samples. No activity was detected

Conditions for maximum isolation of stable condensate during separation in gas-condensate systems

Energy Technology Data Exchange (ETDEWEB)

Trivus, N.A.; Belkina, N.A.

1969-02-01

A thermodynamic analysis is made of the gas-liquid separation process in order to determine the relationship between conditions of maximum stable condensate separation and physico-chemical nature and composition of condensate. The analysis was made by considering the multicomponent gas-condensate fluid produced from Zyrya field as a ternary system, composed of methane, an intermediate component (propane and butane) and a heavy residue, C/sub 6+/. Composition of 5 ternary systems was calculated for a wide variation in separator conditions. At each separator pressure there is maximum condensate production at a certain temperature. This occurs because solubility of condensate components changes with temperature. Results of all calculations are shown graphically. The graphs show conditions of maximum stable condensate separation.

Investigation of extractable organic compounds in deep-sea hydrothermal vent fluids along the Mid-Atlantic Ridge

Science.gov (United States)

McCollom, Thomas M.; Seewald, Jeffrey S.; German, Christopher R.

2015-05-01

The possibility that deep-sea hydrothermal vents may contain organic compounds produced by abiotic synthesis or by microbial communities living deep beneath the surface has led to numerous studies of the organic composition of vent fluids. Most of these studies have focused on methane and other light hydrocarbons, while the possible occurrence of more complex organic compounds in the fluids has remained largely unstudied. To address this issue, the presence of higher molecular weight organic compounds in deep-sea hydrothermal fluids was assessed at three sites along the Mid-Atlantic Ridge that span a range of temperatures (51 to >360 °C), fluid compositions, and host-rock lithologies (mafic to ultramafic). Samples were obtained at several sites within the Lucky Strike, Rainbow, and Lost City hydrothermal fields. Three methods were employed to extract organic compounds for analysis, including liquid:liquid extraction, cold trapping on the walls of a coil of titanium tubing, and pumping fluids through cartridges filled with solid phase extraction (SPE) sorbents. The only samples to consistently yield high amounts of extractable organic compounds were the warm (51-91 °C), highly alkaline fluids from Lost City, which contained elevated concentrations of C8, C10, and C12n-alkanoic acids and, in some cases, trithiolane, hexadecanol, squalene, and cholesterol. Collectively, the C8-C12 acids can account for about 15% of the total dissolved organic carbon in the Lost City fluids. The even-carbon-number predominance of the alkanoic acids indicates a biological origin, but it is unclear whether these compounds are derived from microbial activity occurring within the hydrothermal chimney proximal to the site of fluid discharge or are transported from deeper within the system. Hydrothermal fluids from the Lucky Strike and Rainbow fields were characterized by an overall scarcity of extractable dissolved organic compounds. Trace amounts of aromatic hydrocarbons including

Stereoscopic particle image velocimetry investigations of the mixed convection exchange flow through a horizontal vent

Science.gov (United States)

Varrall, Kevin; Pretrel, Hugues; Vaux, Samuel; Vauquelin, Olivier

2017-10-01

The exchange flow through a horizontal vent linking two compartments (one above the other) is studied experimentally. This exchange is here governed by both the buoyant natural effect due to the temperature difference of the fluids in both compartments, and the effect of a (forced) mechanical ventilation applied in the lower compartment. Such a configuration leads to uni- or bi-directional flows through the vent. In the experiments, buoyancy is induced in the lower compartment thanks to an electrical resistor. The forced ventilation is applied in exhaust or supply modes and three different values of the vent area. To estimate both velocity fields and flow rates at the vent, measurements are realized at thermal steady state, flush the vent in the upper compartment using stereoscopic particle image velocimetry (SPIV), which is original for this kind of flow. The SPIV measurements allows the area occupied by both upward and downward flows to be determined.

Venting device for nuclear reactor container

International Nuclear Information System (INIS)

Yamashita, Masahiro; Ogata, Ken-ichi.

1994-01-01

An airtight vessel of a venting device of a nuclear reactor container is connected with a reactor container by way of a communication pipeline. A feed water tank is disposed at a position higher than the liquid surface of scrubbing water in the airtight vessel for supplying scrubbing water to the airtight vessel. In addition, a scrubbing water storage tank is disposed at a position hither than the feed water tank for supplying scrubbing water to the feed water tank. Storage water in the feed water tank is introduced into the airtight vessel by the predetermined opening operation of a valve by the pressure exerted on the liquid surface and the own weight of the storage water. Further, the storage water in the scrubbing water storage tank is led into the feed water tank by the water head pressure. The scrubbing water for keeping the performance of the venting device of the reactor container can be supplied by a highly reliable method without using AC power source or the like as a driving source. (I.N.)

Simulating Electrochemistry of Hydrothermal Vents on Enceladus and Other Ocean Worlds

Science.gov (United States)

Barge, L. M.; Krause, F. C.; Jones, J. P.; Billings, K.; Sobron, P.

2017-12-01

Gradients generated in hydrothermal systems provide a significant source of free energy for chemosynthetic life, and may play a role in present-day habitability on ocean worlds such as Enceladus that are thought to host hydrothermal activity. Hydrothermal vents are similar in some ways to typical fuel cell devices: redox/pH gradients between seawater and hydrothermal fluid are analogous to the oxidant and fuel reservoirs; conductive natural mineral deposits are analogous to electrodes; and, in hydrothermal chimneys, the porous chimney wall can function as a separator or ion-exchange membrane. Electrochemistry, founded on quantitative study of redox and other chemical disequilibria as well as the chemistry of interfaces, is uniquely suited to studying these systems. We have performed electrochemical studies to better understand the catalytic potential of seafloor minerals and vent chimneys, using samples from a black smoker vent chimney as an initial demonstration. Fuel cell experiments with electrodes made from black smoker chimney material accurately simulated the redox reactions that occur in a geological setting with this particular catalyst. Similar methods with other geo-catalysts (natural or synthetic) could be utilized to test which redox reactions or metabolisms could be driven in other hydrothermal systems, including putative vent systems on other worlds.

Hunting for Hydrothermal Vents at the Local-Scale Using AUV's and Machine-Learning Classification in the Earth's Oceans

Science.gov (United States)

White, S. M.

2018-05-01

New AUV-based mapping technology coupled with machine-learning methods for detecting individual vents and vent fields at the local-scale raise the possibility of understanding the geologic controls on hydrothermal venting.

Airflow and Heat Transfer in the Slot-Vented Room with Radiant Floor Heating Unit

Directory of Open Access Journals (Sweden)

Xiang-Long Liu

2012-01-01

Full Text Available Radiant floor heating has received increasing attention due to its diverse advantages, especially the energy saving as compared to the conventional dwelling heating system. This paper presents a numerical investigation of airflow and heat transfer in the slot-vented room with the radiant floor heating unit. Combination of fluid convection and thermal radiation has been implemented through the thermal boundary conditions. Spatial distributions of indoor air temperature and velocity, as well as the heat transfer rates along the radiant floor and the outer wall, have been presented and analyzed covering the domains from complete natural convection to forced convection dominated flows. The numerical results demonstrate that the levels of average temperature in the room with lateral slot-ventilation are higher than those without slot-ventilation, but lower than those in the room with ceiling slot-ventilation. Overall, the slot-ventilation room with radiant floor heating unit could offer better indoor air quality through increasing the indoor air temperature and fresh air exchanging rate simultaneously. Concerning the airborne pollutant transports and moisture condensations, the performance of radiant floor heating unit will be further optimized in our future researches.

Ice condensation on sulfuric acid tetrahydrate: Implications for polar stratospheric ice clouds

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T. J. Fortin

2003-01-01

Full Text Available The mechanism of ice nucleation to form Type 2 PSCs is important for controlling the ice particle size and hence the possible dehydration in the polar winter stratosphere. This paper probes heterogeneous ice nucleation on sulfuric acid tetrahydrate (SAT. Laboratory experiments were performed using a thin-film, high-vacuum apparatus in which the condensed phase is monitored via Fourier transform infrared spectroscopy and water pressure is monitored with the combination of an MKS baratron and an ionization gauge. Results show that SAT is an efficient ice nucleus with a critical ice saturation ratio of S*ice = 1.3 to 1.02 over the temperature range 169.8-194.5 K. This corresponds to a necessary supercooling of 0.1-1.3 K below the ice frost point. The laboratory data is used as input for a microphysical/photochemical model to probe the effect that this heterogeneous nucleation mechanism could have on Type 2 PSC formation and stratospheric dehydration. In the model simulations, even a very small number of SAT particles (e.g., 10-3 cm-3 result in ice nucleation on SAT as the dominant mechanism for Type 2 PSC formation. As a result, Type 2 PSC formation is more widespread, leading to larger-scale dehydration. The characteristics of the clouds are controlled by the assumed number of SAT particles present, demonstrating that a proper treatment of SAT is critical for correctly modeling Type 2 PSC formation and stratospheric dehydration.

Modelling of particles collection by vented limiters

International Nuclear Information System (INIS)

Tsitrone, E.; Pegourie, B.; Granata, G.

1995-01-01

This document deals with the use of vented limiters for the collection of neutral particles in Tore Supra. The model developed for experiments is presented together with its experimental validation. Some possible improvements to the present limiter are also proposed. (TEC). 5 refs., 3 figs

Water column imaging on hydrothermal vent in Central Indian Ridge

Science.gov (United States)

Koh, J.; Park, Y.

2017-12-01

Water column imaging with Multibeam echosounder systems (MBES) is recently becoming of increasing interest for oceanographic studies. Especially gas bubbles and hot water exposed from hydrothermal vents make acoustic impedance anomalies in cold seawater, water column imaging is very useful for the researchers who want to detect some kinds of hydrothermal activity. We conducted a hydrothermal exploration program, called "INVENT17", using the MBES system, KONGBERG EM122 (12kHz, 1°×1°), mounted on R/V ISABU and we deployed other equipments including video guided hydraulic grab, tow-yo CTD and general CTD with MAPR (Miniature Autonomous Plume Recorder) in 2017. First, to evaluate its capabilities of detection of hydrothermal vent, the surveys using the MBES were conducted at the Solitaire Field, previously identified hydrothermal area of the Central Indian Ridge. The bathymetric data obtained from MBES provided information about detailed morphology of seafloor, but we were not able to achieve the information from the water column imaging data. But the clue of existence of active hydrothermal vent was detected through the values of ΔNTU, dEh/dt, and OPR gained from MAPR, the data means that the hydrothermal activity affects 100m from the seafloor. It could be the reason that we can't find the hydrothermal activity because the range resolution of water column imaging is pretty rough so that the size of 100m-scaled activity has low possibility to distinguish from seafloor. The other reason is there are no sufficient objects to cause strong scattering like as CO2 bubbles or droplets unlike in the mid-Okinawa Trough. And this suggests that can be a important standard to identify properties of hydrothermal vent sites depending on the presence of scattering objects in water mass. To justify this, we should perform more chemical analysis of hot water emanating from hydrothermal vent and collected several bottles of water sample to do that.

Potentially Prebiotic Syntheses of Condensed Phosphates

Science.gov (United States)

Keefe, Anthony D.; Miller, Stanley L.

1996-01-01

In view of the importance of a prebiotic source of high energy phosphates, we have investigated a number of potentially prebiotic processes to produce condensed phosphates from orthophosphate and cyclic trimetaphosphate from tripolyphosphate. The reagents investigated include polymerizing nitriles, acid anhydrides, lactones, hexamethylene tetramine and carbon suboxide. A number of these processes give substantial yields of pyrophosphate from orthophosphate and trimetaphosphate from tripolyphosphate. Although these reactions may have been applicable in local areas, they are not sufficiently robust to have been of importance in the prebiotic open ocean.

Environmental & Water Quality Operational Studies: Improvement of Hydropower Release Dissolved Oxygen with Turbine Venting.

Science.gov (United States)

1987-03-01

VENTED HYDROTURBINE .. 38 Model Development .......................................... 38 Model Application...mouth intake (Figures B26-B27). 37 A F -W V .0P V *W V *. V. VW . i. ~ ~ -% PART V: MODELING OF REAERATION THROUGH A VENTED HYDROTURBINE 75. Development

Adherence evaluation of vented chest seals in a swine skin model.

Science.gov (United States)

Arnaud, Françoise; Maudlin-Jeronimo, Eric; Higgins, Adam; Kheirabadi, Bijan; McCarron, Richard; Kennedy, Daniel; Housler, Greggory

2016-10-01

Perforation of the chest (open pneumothorax) with and without lung injury can cause air accumulation in the chest, positive intrapleural pressure and lead to tension pneumothorax if untreated. The performance of chest seals to prevent tension physiology depends partially on their ability to adhere to the skin and seal the chest wound. Novel non-occlusive vented chest seals were assessed for their adhesiveness on skin of live swine under normal and extreme environmental conditions to simulate austere battlefield conditions. Chest seals were applied on the back of the swine on skin that was soiled by various environmental contaminants to represent battlefield situations. A peeling (horizontal rim peeling) and detachment and breaching (vertical pulling) techniques were used to quantify the adhesive performance of vented chest seals. Among eight initially selected vented seals, five (Bolin, Russell, Fast breathe, Hyfin and SAM) were further down-selected based on their superior adherence scores at ambient temperatures. The adherence of these seals was then assessed after approximately 17h storage at extreme cold (-19.5°C) and hot (71.5°C) temperatures. Adherence scores for peeling (above 90%) and detachment scores (less than 25%) were comparable for four vented chest seals when tested at ambient temperature, except for the Bolin seal which had higher breaching. Under extreme storage temperatures, adherence peeling scores were comparable to those at ambient temperatures for four chest seals. Scores were significantly lower for the Bolin seal at extreme temperatures. This seal also had the highest detachment and breaching scores. In contrast, the Russell, Fast breathe, Hyfin and SAM seals showed similar ability to stay air tight without breaching after hot storage. No significant difference was found in skin adherence of the five vented chest seals at ambient temperature and the four seals (Russell, Fast breathe, Hyfin and SAM) maintained superior adherence even after

Effects of non-condensable gas on the condensation of steam

International Nuclear Information System (INIS)

Jackson, J.D.; An, P.; Reinert, A.; Ahmadinejad, M.

2000-01-01

The experimental work reported here was undertaken with the aim of extending the database currently available on the condensation of steam in the presence of non-condensable gases and thereby improving the empirical input to thermal-hydraulic codes which might be used for design and safety assessment of advanced water-cooled nuclear reactors. Heat was removed from flowing mixtures of steam and air in a test section by means of a water-cooled condensing plate. The test facility constructed for the study incorporates a degassing unit which supplies water to a boiler. This delivers steam steadily to a mixing chamber where it joins with a flow of preheated air. The mixture of steam and air is supplied to the bottom of a cylindrical test section in which it flows upwards over a double sided condensing plate which can be vertical, inclined or horizontal, The rate at which heat is removed by cooling water flowing through internal passages in the plate can de determined calorimetrically knowing the flow rate of the water and its temperature rise. After commissioning experiments had shown that reliable measurements of condensation heat transfer rate could be made using the test facility, a programme of development work followed in the course of which three different designs of condensing plate were evaluated in turn. The version eventually used in the main programme of experiments which followed was made from copper. However, its surfaces were coated with a thin layer of nickel and then with one of chromium. It was found that such a surface consistently promoted dropwise condensation and showed no signs of deterioration after lengthy periods of use. The rate of heat removal from pure steam and from mixtures of steam and air in varying proportions was measured as a function of plate sub-cooling for a variety of plate orientations. (author)

Purification method for condensate

International Nuclear Information System (INIS)

Shimoda, Akiyoshi.

1996-01-01

Condensates generated in secondary coolant circuits of a PWR type reactor are filtered using a hollow thread separation membranes comprising aromatic polyether ketone. Preferably, condensates after passing through a turbine are filtered at a place between a condensator and a steam generator at high temperature as close as a temperature of the steam generator. As the hollow thread membrane, partially crystalline membrane comprising aromatic polyether ketone is used. When it is used at high temperature, the crystallinity is preferably not less than 15wt%. Since a hollow thread membrane comprising the aromatic polyether ketone of excellent heat resistance is used, it can filter and purify the condensates at not lower than 70degC. Accordingly, impurities such as colloidal iron can be removed from the condensates, and the precipitation of cruds in the condensates to a steam generator and a turbine can be suppressed. (I.N.)

Hydrothermal vent fields discovered in the southern Gulf of California clarify role of habitat in augmenting regional diversity.

Science.gov (United States)

Goffredi, Shana K; Johnson, Shannon; Tunnicliffe, Verena; Caress, David; Clague, David; Escobar, Elva; Lundsten, Lonny; Paduan, Jennifer B; Rouse, Greg; Salcedo, Diana L; Soto, Luis A; Spelz-Madero, Ronald; Zierenberg, Robert; Vrijenhoek, Robert

2017-07-26

Hydrothermal vent communities are distributed along mid-ocean spreading ridges as isolated patches. While distance is a key factor influencing connectivity among sites, habitat characteristics are also critical. The Pescadero Basin (PB) and Alarcón Rise (AR) vent fields, recently discovered in the southern Gulf of California, are bounded by previously known vent localities (e.g. Guaymas Basin and 21° N East Pacific Rise); yet, the newly discovered vents differ markedly in substrata and vent fluid attributes. Out of 116 macrofaunal species observed or collected, only three species are shared among all four vent fields, while 73 occur at only one locality. Foundation species at basalt-hosted sulfide chimneys on the AR differ from the functional equivalents inhabiting sediment-hosted carbonate chimneys in the PB, only 75 km away. The dominant species of symbiont-hosting tubeworms and clams, and peripheral suspension-feeding taxa, differ between the sites. Notably, the PB vents host a limited and specialized fauna in which 17 of 26 species are unknown at other regional vents and many are new species. Rare sightings and captured larvae of the 'missing' species revealed that dispersal limitation is not responsible for differences in community composition at the neighbouring vent localities. Instead, larval recruitment-limiting habitat suitability probably favours species differentially. As scenarios develop to design conservation strategies around mining of seafloor sulfide deposits, these results illustrate that models encompassing habitat characteristics are needed to predict metacommunity structure. © 2017 The Authors.

The dry filter method for passive filtered venting of the containment

International Nuclear Information System (INIS)

Freis, Daniel; Tietsch, Wolfgang; Obenland, Ralf; Kroes, Bert; Martinsteg, Hans

2013-01-01

Filtered Venting is a mitigative emergency measure to protect the containment from pressure failure in case of a severe accident. Filtered vent systems which are based on the Dry Filter Method (DFM) are proven technology, work completely passive, meet all functional requirements and show excellent performance with respect to filter efficiency. With such a system the release of radioactive fission products to the environment can be effectively minimized. Short and long term land contaminations can be avoided. (orig.)

Characterization and Antioxidant Properties of the Condensed Tannins from Alaska Cedar Inner Bark

Directory of Open Access Journals (Sweden)

Martha Rosales-Castro

2014-05-01

Full Text Available The structure and antioxidant activity of condensed tannins isolated from Alaska Cedar inner bark have been investigated. Oligomers of flavan-3-ol were purified by column chromatography (Sephadex LH-20 and analyzed by 13CNMR and MALDI-TOF MS spectrometries. Their antioxidant activities were measured using 1,1’-diphenyl-2-picrylhydrazyl (DPPH, 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS free radicals scavenging, ferric reducing/antioxidant power (FRAP, and β-carotene-linoleic acid model system (β-CLAMS assays. Results showed that the condensed tannins consents of both homogeneous and heterogeneous oligomers of procyanidins (catechin/epicatechin and prodelphinidins (gallocatechin/ epigallocatechin flavan-3-ol units; and oligomers from trimmers to heptamers with dominant interflavan linkages B-type as it is most common in proanthocyanidins. Condensed tannins showed significant ntioxidant activity as the median inhibition capacity IC 50 is comparable to the catechin control response. Alaska Cedar inner bark oligomers show high antioxidant capacity, evaluated by both methods based on electron transfer mechanisms and hydrogen atom transfer reactions. This bark may be considered as a new source of natural antioxidants for nutraceutical ingredients.

Geomicrobiology of sublacustrine thermal vents in Yellowstone Lake: Geochemical controls on microbial community structure and function

Directory of Open Access Journals (Sweden)

William P. Inskeep

2015-10-01

Full Text Available Yellowstone Lake (Yellowstone National Park, WY, USA is a large high-altitude (2200 m, fresh-water lake, which straddles an extensive caldera and is the center of significant geothermal activity. The primary goal of this interdisciplinary study was to evaluate the microbial populations inhabiting thermal vent communities in Yellowstone Lake (Yellowstone Lake using 16S rRNA gene and random metagenome sequencing, and to determine how geochemical attributes of vent waters influence the distribution of specific microorganisms and their metabolic potential. Thermal vent waters and associated microbial biomass were sampled during two field seasons (2007 - 2008 using a remotely operated vehicle (ROV. Sublacustrine thermal vent waters (circa 50 - 90 oC contained elevated concentrations of numerous constituents associated with geothermal activity including dissolved hydrogen, sulfide, methane and carbon dioxide. Microorganisms associated with sulfur-rich filamentous ‘streamer’ communities of Inflated Plain and West Thumb (pH range 5 - 6 were dominated by bacteria from the Aquificales, but also contained thermophilic archaea from the Crenarchaeota and Euryarchaeota. Novel groups of methanogens and members of the Korarchaeota were observed in vents from West Thumb and Elliot’s Crater (pH 5 - 6. Conversely, metagenome sequence from Mary Bay vent sediments did not yield large assemblies, and contained diverse thermophilic and nonthermophilic bacterial relatives. Analysis of functional genes associated with the major vent populations indicated a direct linkage to high concentrations of carbon dioxide, reduced sulfur (sulfide and/or elemental S, hydrogen and methane in the deep thermal ecosystems. Our observations show that sublacustrine thermal vents in Yellowstone Lake support novel thermophilic communities, which contain microorganisms with functional attributes not found to date in terrestrial geothermal systems of YNP.

In-service inspection of condenser tubes by means of electrochemical methods

International Nuclear Information System (INIS)

Taelemans, G.

The commissioning of an increasing number of large nuclear power plants involves an increased significance of such condenser tube problems as: - erosion on tube ends, - generalized corrosion and pitting corrosion, - deposits in the tubes. In order to solve such problems, investigations were performed especially focused on a measurement technique that enables in-service behaviour of condenser tubes to be monitored. For such a purpose, measurement of the polarization resistance has been adopted. The existing corrosion products and scaled-off iron oxides were eliminated by means of a carborundum balls processing, as clearly appears from polarization resistance reduction. Then iron sulphate was injected in order to build a new and better protective layer. In addition, the tube was kept clean by means of foam rubber balls. There is a second implementation area: fouled condenser tubes. A significant polarization resistance reduction is noted during the acid cleaning. (orig.) [de

Seafloor geomorphic manifestations of gas venting and shallow subbottom gas hydrate occurrences

Science.gov (United States)

Paull, C K; Caress, D W; Thomas, Hans; Lundsten, Eve M.; Anderson, Kayce; Gwiazda, Roberto; Riedel, M; McGann, Mary; Herguera, J C

2015-01-01

High-resolution multibeam bathymetry data collected with an autonomous underwater vehicle (AUV) complemented by compressed high-intensity radar pulse (Chirp) profiles and remotely operated vehicle (ROV) observations and sediment sampling reveal a distinctive rough topography associated with seafloor gas venting and/or near-subsurface gas hydrate accumulations. The surveys provide 1 m bathymetric grids of deep-water gas venting sites along the best-known gas venting areas along the Pacific margin of North America, which is an unprecedented level of resolution. Patches of conspicuously rough seafloor that are tens of meters to hundreds of meters across and occur on larger seafloor topographic highs characterize seepage areas. Some patches are composed of multiple depressions that range from 1 to 100 m in diameter and are commonly up to 10 m deeper than the adjacent seafloor. Elevated mounds with relief of >10 m and fractured surfaces suggest that seafloor expansion also occurs. Ground truth observations show that these areas contain broken pavements of methane-derived authigenic carbonates with intervening topographic lows. Patterns seen in Chirp profiles, ROV observations, and core data suggest that the rough topography is produced by a combination of diagenetic alteration, focused erosion, and inflation of the seafloor. This characteristic texture allows previously unknown gas venting areas to be identified within these surveys. A conceptual model for the evolution of these features suggests that these morphologies develop slowly over protracted periods of slow seepage and shows the impact of gas venting and gas hydrate development on the seafloor morphology.

Simple Simulations of DNA Condensation

Energy Technology Data Exchange (ETDEWEB)

STEVENS,MARK J.

2000-07-12

Molecular dynamics simulations of a simple, bead-spring model of semiflexible polyelectrolytes such as DNA are performed. All charges are explicitly treated. Starting from extended, noncondensed conformations, condensed structures form in the simulations with tetravalent or trivalent counterions. No condensates form or are stable for divalent counterions. The mechanism by which condensates form is described. Briefly, condensation occurs because electrostatic interactions dominate entropy, and the favored Coulombic structure is a charge ordered state. Condensation is a generic phenomena and occurs for a variety of polyelectrolyte parameters. Toroids and rods are the condensate structures. Toroids form preferentially when the molecular stiffness is sufficiently strong.

10 CFR 50.46a - Acceptance criteria for reactor coolant system venting systems.

Science.gov (United States)

2010-01-01

... 10 Energy 1 2010-01-01 2010-01-01 false Acceptance criteria for reactor coolant system venting systems. 50.46a Section 50.46a Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF PRODUCTION AND... function of these systems. High point vents are not required for the tubes in U-tube steam generators...

Loki's Castle: Discovery and geology of a black smoker vent field at the Arctic Mid-Ocean Ridge

Science.gov (United States)

Pedersen, R.; Thorseth, I. H.; Lilley, M. D.; Barriga, F. J.; Früh-Green, G.; Nakamura, K.

2010-12-01

Previous attempts to locate hydrothermal vent fields and unravel the nature of venting at the ultraslow spreading and magma starved parts of the Arctic Mid Ocean Ridge (AMOR) have been unsuccessful. A black smoker vent field was eventually discovered at the Mohns-Knipovich bend at 73.5°N in 2008, and the field was revisited in 2009 and 2010. The Loki’s Castle vent field is located on the crest of an axial volcanic ridge that is bordered by a tectonic terrain dominated by core complexes to the NW, and a ridge flank that is buried by sediments from the Bear Island Fan to the SE. Fluid compositions are anomalous to other basalt-hosted fields and indicate interactions with sediments at depths. The vent field is associated with an unusually large hydrothermal deposit, which documents that extensive venting occurs at ultraslow spreading ridges despite the strongly reduced magmatic heat budget. ROV surveys have shown that venting occurs in two areas separated by around 100 m. Micro-bathymetry acquired by a Hugin AUV documents that two 20-30 tall mounds that coalesce at the base have developed around the vent sites. The micro-bathymetry also shows that the venting is located above two normal faults that define the NW margin of a rift that runs along the crest of the volcano. The black smoker fluids reach 317 °C, with an end-member SiO2 content of 16 mmol/kg. End-member chlorinity is around 85% of seawater suggesting that the fluids have phase-separated at depth. The fluid compositions indicate that the rock-water reactions occur around 2 km below the seafloor. The crustal thickness is estimated to be 4 +/- 0.5 km in the area. Whereas the depth of the reaction zone is comparable with faster spreading ridges, the fraction of crust cooled convectively by hydrothermal circulation is two times that of vent fields at ridges with normal crustal thickness.

Calculation and analysis of hydrogen volume concentrations in the vent pipe rigid proposed for NPP-L V

International Nuclear Information System (INIS)

Gomez T, A. M.; Xolocostli M, V.; Lopez M, R.; Filio L, C.; Royl, P.

2014-10-01

In 2012 was modeled of primary and secondary container of the nuclear power plant of Laguna Verde (NPP-L V) for the CFD Gas-Flow code. These models were used to calculate hydrogen volume concentrations run release the reactor building in case of a severe accident. The results showed that the venting would produce detonation conditions in the venting level (level 33) and flammability at ground level of reload. One of the solutions to avoid reaching critical concentrations (flammable or detonable) inside the reactor building and thus safeguard the contentions is to make a rigid venting. The rigid vent is a pipe connected to the primary container could go to the level 33 of the secondary container and style fireplace climb to the top of the reactor building. The analysis of hydrogen transport inside the vent pipe can be influenced by various environmental criteria and factors vent, so a logical consequence of the 2012 analysis is the analysis of the gases transport within said pipe to define vent ideal conditions. For these evaluations the vent pipe was modeled with a fine mesh of 32 radial interior nodes and a coarse mesh of 4 radial interior nodes. With three-dimensional models were realized calculations that allow observing the influence of heat transfer in the long term, i.e. a complete analysis of exhaust (approx. 700 seconds). However, the most interesting results focus on the first milliseconds, when the H 2 coming from the atmosphere of the primary container faces the air in the vent pipe. These first milliseconds besides allowing evaluating the detonation criteria in great detail in the different tubular sections similarly allow evaluating the pressure wave that occurs in the pipe and that at some point slows to the fluid on the last tubular section and could produce a detonation inside the pipe. Results are presented for venting fixed conditions, showing possible detonations into the pipe. (Author)

Community Structure Comparisons of Hydrothermal Vent Microbial Mats Along the Mariana Arc and Back-arc

Science.gov (United States)

Hager, K. W.; Fullerton, H.; Moyer, C. L.

2015-12-01

Hydrothermal vents along the Mariana Arc and back-arc represent a hotspot of microbial diversity that has not yet been fully recognized. The Mariana Arc and back-arc contain hydrothermal vents with varied vent effluent chemistry and temperature, which translates to diverse community composition. We have focused on iron-rich sites where the dominant primary producers are iron oxidizing bacteria. Because microbes from these environments have proven elusive in culturing efforts, we performed culture independent analysis among different microbial communities found at these hydrothermal vents. Terminal-restriction fragment length polymorphism (T-RFLP) and Illumina sequencing of small subunit ribosomal gene amplicons were used to characterize community members and identify samples for shotgun metagenomics. Used in combination, these methods will better elucidate the composition and characteristics of the bacterial communities at these hydrothermal vent systems. The overarching goal of this study is to evaluate and compare taxonomic and metabolic diversity among different communities of microbial mats. We compared communities collected on a fine scale to analyze the bacterial community based on gross mat morphology, geography, and nearby vent effluent chemistry. Taxa richness and evenness are compared with rarefaction curves to visualize diversity. As well as providing a survey of diversity this study also presents a juxtaposition of three methods in which ribosomal small subunit diversity is compared with T-RFLP, next generation amplicon sequencing, and metagenomic shotgun sequencing.

Condensation shocks in high momentum two-phase flows in condensing injectors

International Nuclear Information System (INIS)

Anand, G.; Christensen, R.N.

1993-01-01

This study presents a phenomenological and mathematical model of condensation shocks in high momentum two-phase flows in condensing injectors. The characteristics of the shock were related to the mode of vapor bubble collapse. Using cavitation terminology, the bubble collapse can be classified as inertially controlled or thermally controlled. Inertial bubble collapse occurs rapidly whereas, a thermally controlled collapse results in a significantly longer collapse time. The interdependence between the bubble collapse mode and the momentum and pressure of the flow, was analyzed in this study. For low-temperature-high-velocity flows a steep pressure rise with complete condensation was obtained. For a high-temperature-low velocity flow with noncondensables, low pressure recovery with incomplete condensation was observed. These trends are in agreement with previous experimental observations

Condensation in complex geometries

International Nuclear Information System (INIS)

Lauro, F.

1975-01-01

A mathematical evaluation of the condensation exchange coefficient can only succeds for well specified cases: small upright or inclined plates, horizontal tubes, small height vertical tubes. Among the main hypotheses accounted for this mathematical development in the case of the condensate, a laminar flow and uniform surface temperature are always considered. In practice certain shapes of surfaces significantly increase the heat transfer during the vapor condensation on a surface wet by the condensate. Such surfaces are rough surfaces such as the condensate is submitted to surface tension effects, negligeable for plane or large curvature surfaces, and the nature of the material may play an important role (temperature gradients). Results from tests on tubes with special shapes, performed in France or out of France, are given [fr

Computational and experimental studies on oxalic acid imprinted ...

Indian Academy of Sciences (India)

e-mail: rkkawadkar@chm.vnit.ac.in. MS received 13 ... vent or porogen to form a pre-polymerization complex, followed by .... tered off and the filtrate was analysed for oxalic acid by. UV/VIS ... The experimental binding data were fitted to the.

Sedimentary condensation and authigenesis

Science.gov (United States)

Föllmi, Karl

2016-04-01

Most marine authigenic minerals form in sediments, which are subjected to condensation. Condensation processes lead to the formation of well individualized, extremely thin ( 100ky), and which experienced authigenesis and the precipitation of glaucony, verdine, phosphate, iron and manganese oxyhydroxides, iron sulfide, carbonate and/or silica. They usually show complex internal stratigraphies, which result from an interplay of sediment accumulation, halts in sedimentation, sediment winnowing, erosion, reworking and bypass. They may include amalgamated faunas of different origin and age. Hardgrounds may be part of condensed beds and may embody strongly condensed beds by themselves. Sedimentary condensation is the result of a hydrodynamically active depositional regime, in which sediment accumulation, winnowing, erosion, reworking and bypass are processes, which alternate as a function of changes in the location and intensity of currents, and/or as the result of episodic high-energy events engendered by storms and gravity flow. Sedimentary condensation has been and still is a widespread phenomenon in past and present-day oceans. The present-day distribution of glaucony and verdine-rich sediments on shelves and upper slopes, phosphate-rich sediments and phosphorite on outer shelves and upper slopes, ferromanganese crusts on slopes, seamounts and submarine plateaus, and ferromanganese nodules on abyssal seafloors is a good indication of the importance of condensation processes today. In the past, we may add the occurrence of oolitic ironstone, carbonate hardgrounds, and eventually also silica layers in banded iron formations as indicators of the importance of condensation processes. Besides their economic value, condensed sediments are useful both as a carrier of geochemical proxies of paleoceanographic and paleoenvironmental change, as well as the product of episodes of paleoceanographic and paleoenvironmental change themselves.

40 CFR Table 4 to Subpart Vvvvvv... - Emission Limits and Compliance Requirements for Metal HAP Process Vents

Science.gov (United States)

2010-07-01

... Requirements for Metal HAP Process Vents 4 Table 4 to Subpart VVVVVV of Part 63 Protection of Environment... of Part 63—Emission Limits and Compliance Requirements for Metal HAP Process Vents As required in § 63.11496(f), you must comply with the requirements for metal HAP process vents as shown in the...

Kolanut (Cola Nitida Vent Schott of Endlicher)

African Journals Online (AJOL)

Kolanut (Cola Nitida Vent Schott of Endlicher). S.O. Agbeniyi, Otuonye, H.A. andAR. Adedeji Cocoa Research Institute of Nigeria. Abstract. The mycoflora associated with processing stages of kolanut post-harvest were evaluated at the Cocoa. Research Institute of Nigeria, Ibadan Nigeria. Several samples of healthy and ...

Reversible DNA condensation induced by a tetranuclear nickel(II) complex.

Science.gov (United States)

Dong, Xindian; Wang, Xiaoyong; He, Yafeng; Yu, Zhen; Lin, Miaoxin; Zhang, Changli; Wang, Jing; Song, Yajie; Zhang, Yangmiao; Liu, Zhipeng; Li, Yizhi; Guo, Zijian

2010-12-17

DNA condensing agents play a critical role in gene therapy. A tetranuclear nickel(II) complex, [Ni(II)(4)(L-2H)(H(2)O)(6)(CH(3)CH(2)OH)(2)]·6NO(3) (L=3,3',5,5'-tetrakis{[(2-hydroxyethyl)(pyridin-2-ylmethyl)amino]methyl}biphenyl-4,4'-diol), has been synthesized as a nonviral vector to induce DNA condensation. X-ray crystallographic data indicate that the complex crystallizes in the monoclinic system with space group P2(1)/n, a=10.291(9), b=24.15(2), c=13.896(11) Å, and β=98.175(13)°. The DNA condensation induced by the complex has been investigated by means of UV/Vis spectroscopy, fluorescence spectroscopy, circular dichroism spectroscopy, dynamic light scattering, atomic force microscopy, gel electrophoresis assay, and zeta potential analysis. The complex interacts strongly with DNA through electrostatic attraction and induces its condensation into globular nanoparticles at low concentration. The release of DNA from its compact state has been achieved using the chelator ethylenediaminetetraacetic acid (EDTA) for the first time. Other essential properties, such as DNA cleavage inactivity and biocompatibility, have also been examined in vitro. In general, the complex satisfies the requirements of a gene vector in all of these respects.

Tornado protection by venting

International Nuclear Information System (INIS)

Cavanagh, C.A.

1987-01-01

The purpose of this paper is to demonstrate the ability to protect a modern nuclear power plant from the effects of a tornado by the use of a system of venting in all safety-related structures outside of the containment. The paper demonstrates this by presenting a method of analysis and of equipment selection that fully complies with the intent and the letter of applicable federal regulatory guides. A report of an actual tornado in the City of Kalamazoo, Michigan, suggests that the concept of sealing a plant during a tornado may not always be applicable

Reversible Venting Stitch for Fenestrating Valve-less Glaucoma Shunts.

Science.gov (United States)

Akil, Handan; Vu, Priscilla Q; Nguyen, Anhtuan H; Nugent, Alexander; Chopra, Vikas; Francis, Brian A; Tan, James C

2017-12-01

The purpose of this is to describe a venting stitch modification for valveless glaucoma aqueous shunts and characterize early postoperative intraocular pressure (IOP) and glaucoma medication use following the modification. Retrospective chart review of 61 sequential patients undergoing Baerveldt glaucoma implant (BGI)-350 implantation at the Doheny Eye Institute. Twenty-four patients received a glaucoma shunt with venting stitch modification (modified BGI) and 37 patients received an unmodified shunt (BGI-only). IOP, number of glaucoma medications, and number of hypotony cases (intraocular pressure ≤5 mm Hg) were compared between the groups. T-tests were used for statistical analysis. At postoperative-day 1, mean IOP was significantly lower compared with preoperatively in the modified BGI group (14 mm Hg; reduced by 51%; P<0.0001) but not the BGI-only group (27 mm Hg; P=0.06). IOP difference between groups persisted till immediately before tube opening (P=0.005) and fewer IOP-lowering medications needed in the modified BGI group (P<0.0001). One case (4.2%) of postoperative hypotony was encountered with BGI modification, which resolved after the stitch was removed in clinic. The venting stitch valveless shunt modification allows for effective, reliable, and safe control of early postoperative IOP.

A helium venting model for a SSC half cell

International Nuclear Information System (INIS)

Carcagno, R.H.; McAshan, M.S.; Schiesser, W.E.

1991-01-01

When a Superconducting Super Collider (SSC) dipole magnet quenches, the quench protection system will intentionally quench other magnets in the half cell. The result is that the stored energy of all of these quenched magnets will be absorbed equally among them. These simultaneous quenches produce heat, which diffuses from the magnet coils to the main helium (He) coolant channels and thereby eventually causes an increase in the He pressure. When the quench is detected, vent valves open to minimize the He pressure increase and thus prevent damage to the magnets. The performance of the He venting system has been modeled and simulated to establish whether the venting will take place as required. The model consists of partial differential equation energy balances written radially for the magnet coils, collar, and yoke; and ordinary differential equations of energy and mass balance written for the He in the magnets and relief header. The basic algorithm is the numerical method of lines, with finite difference approximation of the spatial derivatives, and time integration by LSODES. Simulation results are presented for an SSC half cell of the Accelerator Systems String Test (ASST) facility. The results are also compared with recent string quench measurements performed at the Fermilab String Test Facility

Bayesian optimization analysis of containment-venting operation in a boiling water reactor severe accident

International Nuclear Information System (INIS)

Zheng, Xiaoyu; Ishikawa, Jun; Sugiyama, Tomoyuki; Maryyama, Yu

2017-01-01

Containment venting is one of several essential measures to protect the integrity of the final barrier of a nuclear reactor during severe accidents, by which the uncontrollable release of fission products can be avoided. The authors seek to develop an optimization approach to venting operations, from a simulation-based perspective, using an integrated severe accident code, THALES2/KICHE. The effectiveness of the containment-venting strategies needs to be verified via numerical simulations based on various settings of the venting conditions. The number of iterations, however, needs to be controlled to avoid cumbersome computational burden of integrated codes. Bayesian optimization is an efficient global optimization approach. By using a Gaussian process regression, a surrogate model of the “black-box” code is constructed. It can be updated simultaneously whenever new simulation results are acquired. With predictions via the surrogate model, upcoming locations of the most probable optimum can be revealed. The sampling procedure is adaptive. Compared with the case of pure random searches, the number of code queries is largely reduced for the optimum finding. One typical severe accident scenario of a boiling water reactor is chosen as an example. The research demonstrates the applicability of the Bayesian optimization approach to the design and establishment of containment-venting strategies during severe accidents

Bayesian optimization analysis of containment-venting operation in a boiling water reactor severe accident

Energy Technology Data Exchange (ETDEWEB)

Zheng, Xiaoyu; Ishikawa, Jun; Sugiyama, Tomoyuki; Maryyama, Yu [Nuclear Safety Research Center, Japan Atomic Energy Agency, Ibaraki (Japan)

2017-03-15

Containment venting is one of several essential measures to protect the integrity of the final barrier of a nuclear reactor during severe accidents, by which the uncontrollable release of fission products can be avoided. The authors seek to develop an optimization approach to venting operations, from a simulation-based perspective, using an integrated severe accident code, THALES2/KICHE. The effectiveness of the containment-venting strategies needs to be verified via numerical simulations based on various settings of the venting conditions. The number of iterations, however, needs to be controlled to avoid cumbersome computational burden of integrated codes. Bayesian optimization is an efficient global optimization approach. By using a Gaussian process regression, a surrogate model of the “black-box” code is constructed. It can be updated simultaneously whenever new simulation results are acquired. With predictions via the surrogate model, upcoming locations of the most probable optimum can be revealed. The sampling procedure is adaptive. Compared with the case of pure random searches, the number of code queries is largely reduced for the optimum finding. One typical severe accident scenario of a boiling water reactor is chosen as an example. The research demonstrates the applicability of the Bayesian optimization approach to the design and establishment of containment-venting strategies during severe accidents.

Microbial communities and chemosynthesis in Yellowstone Lake sublacustrine hydrothermal vent waters

Directory of Open Access Journals (Sweden)

Tingting eYang

2011-06-01

Full Text Available Abstract. Five sublacustrine hydrothermal vent locations from 1-109 m water depth in Yellowstone Lake were surveyed by ribosomal RNA sequencing in relation to their chemical composition and dark CO2 fixation rates. They harbor distinct chemosynthetic bacterial communities, depending on temperature (16 - 110ºC and electron donor supply (H2S <1 - >100µM; NH3 <0.5 - >10µM. Members of the Aquificales, most closely affiliated with the genus Sulfurihydrogenibium, are the most frequently recovered bacterial 16S rRNA gene phylotypes in the hottest samples; the detection of these thermophilic sulfur-oxidizing autotrophs coincided with maximal dark CO2 fixation rates reaching near 9 µM C h-1 at temperatures of 50 to 60°C. Vents at lower temperatures yielded mostly phylotypes related to the mesophilic gammaproteobacterial sulfur oxidizer Thiovirga. In contrast, cool vent water with low chemosynthetic activity yielded predominantly phylotypes related to freshwater Actinobacterial clusters with a cosmopolitan distribution.

An abyssal mobilome: Viruses, plasmids and vesicles from deep-sea hydrothermal vents

OpenAIRE

Lossouarn, Julien; Dupont, Samuel; Gorlas, Aurore; Mercier, Coraline; Bienvenu, Nadege; Marguet, Evelyne; Forterre, Patrick; Geslin, Claire

2015-01-01

Mobile genetic elements (MGEs) such as viruses, plasmids, vesicles, gene transfer agents (GTAs), transposons and transpovirions, which collectively represent the mobilome, interact with cellular organisms from all three domains of life, including those thriving in the most extreme environments. While efforts have been made to better understand deep-sea vent microbial ecology, our knowledge of the mobilome associated with prokaryotes inhabiting deep-sea hydrothermal vents remains limited. Here...

Light at deep sea hydrothermal vents

Science.gov (United States)

Van Dover, Cindy Lee; Cann, J. R.; Cavanaugh, Colleen; Chamberlain, Steven; Delaney, John R.; Janecky, David; Imhoff, Johannes; Tyson, J. Anthony

We usually think of the bottom of the sea as a dark environment, lit only by flashes of bioluminescent light. Discovery of light associated with geothermal processes at deep sea hydrothermal vents forces us to qualify our textbook descriptions of the seafloor as a uniformly dark environment. While a very dim glow emitted from high temperature (350°) vents (black smokers) at mid-oceanic ridge spreading centers has been documented [Van Dover et al, 1988], the source of this light and its role, if any, in the evolution and adaptation of photobiochemical processes have yet to be determined. Preliminary studies indicate that thermal radiation alone may account for the “glow” ]Smith and Delaney, 1989] and that a novel photoreceptor in shrimp-colonizing black smoker chimneys may detect this “glow” [Van Dover et al., 1989; Pelli and Chamberlain, 1989]. A more controversial question, posed by C. L. Van Dover, J. R. Cann, and J. R. Delaney at the 1993 LITE Workshop at the Woods Hole Oceanographic Institution in Massachusetts, is whether there may be sufficient light of appropriate wavelengths to support geothermally driven photosynthesis by microorganisms.

Synthesis of acid-base bifunctional mesoporous materials by oxidation and thermolysis

Energy Technology Data Exchange (ETDEWEB)

Yu, Xiaofang [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Zou, Yongcun [State Key Laboratory of Inoranic Synthesis and Preparative Chemistryg, College of Chemistry, Jilin University, Changchun 130012 (China); Wu, Shujie; Liu, Heng [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Guan, Jingqi, E-mail: guanjq@jlu.edu.cn [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Kan, Qiubin, E-mail: qkan@jlu.edu.cn [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China)

2011-06-15

Graphical abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst. The obtained sample of SO{sub 3}H-MCM-41-NH{sub 2} containing amine and sulfonic acids exhibits excellent catalytic activity in aldol condensation reaction. Research highlights: {yields} Synthesize acid-base bifunctional mesoporous materials SO{sub 3}H-MCM-41-NH{sub 2}. {yields} Oxidation and then thermolysis to generate acidic site and basic site. {yields} Exhibit good catalytic performance in aldol condensation reaction between acetone and various aldehydes. -- Abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst SO{sub 3}H-MCM-41-NH{sub 2}. This method was achieved by co-condensation of tetraethylorthosilicate (TEOS), 3-mercaptopropyltrimethoxysilane (MPTMS) and (3-triethoxysilylpropyl) carbamicacid-1-methylcyclohexylester (3TAME) in the presence of cetyltrimethylammonium bromide (CTAB), followed by oxidation and then thermolysis to generate acidic site and basic site. X-ray diffraction (XRD) and transmission electron micrographs (TEM) show that the resultant materials keep mesoporous structure. Thermogravimetric analysis (TGA), X-ray photoelectron spectra (XPS), back titration, solid-state {sup 13}C CP/MAS NMR and solid-state {sup 29}Si MAS NMR confirm that the organosiloxanes were condensed as a part of the silica framework. The bifunctional sample (SO{sub 3}H-MCM-41-NH{sub 2}) containing amine and sulfonic acids exhibits excellent acid-basic properties, which make it possess high activity in aldol condensation reaction between acetone and various aldehydes.

Possibility of removing condensate and scattered oil from gas-condensate field during bed flooding

Energy Technology Data Exchange (ETDEWEB)

Belkina, N.A.; Yagubov, M.S.

1984-01-01

The problem is set of evaluating the possible removal from the bed of scattered oil and condensate during flooding of the bed. For this purpose, an experimental study was made of the displacement by water from the porous medium of the oil and condensate saturating it. The obtained experimental results permit evaluation of the possible removal from the gas-condensate bed of scattered oil and condensate during flooding of the bed.

Exploring the Ecology of Deep-Sea Hydrothermal Vents in a Metacommunity Framework

Directory of Open Access Journals (Sweden)

Lauren S. Mullineaux

2018-02-01

Full Text Available Species inhabiting deep-sea hydrothermal vents are strongly influenced by the geological setting, as it provides the chemical-rich fluids supporting the food web, creates the patchwork of seafloor habitat, and generates catastrophic disturbances that can eradicate entire communities. The patches of vent habitat host a network of communities (a metacommunity connected by dispersal of planktonic larvae. The dynamics of the metacommunity are influenced not only by birth rates, death rates and interactions of populations at the local site, but also by regional influences on dispersal from different sites. The connections to other communities provide a mechanism for dynamics at a local site to affect features of the regional biota. In this paper, we explore the challenges and potential benefits of applying metacommunity theory to vent communities, with a particular focus on effects of disturbance. We synthesize field observations to inform models and identify data gaps that need to be addressed to answer key questions including: (1 what is the influence of the magnitude and rate of disturbance on ecological attributes, such as time to extinction or resilience in a metacommunity; (2 what interactions between local and regional processes control species diversity, and (3 which communities are “hot spots” of key ecological significance. We conclude by assessing our ability to evaluate resilience of vent metacommunities to human disturbance (e.g., deep-sea mining. Although the resilience of a few highly disturbed vent systems in the eastern Pacific has been quantified, these values cannot be generalized to remote locales in the western Pacific or mid Atlantic where disturbance rates are different and information on local controls is missing.

Research progress of control of condensate depression for condenser

Science.gov (United States)

Liu, Ying; Liang, Run; Li, Fengyu

2017-08-01

It is introduced that significance and structure of the condensate depression control system. In accordance with controller devised procedure, we analyze and elaborate how to construct the lumped parameter and dynamic mathematical model which possesses distinct physics significance. Neural network model being called black-box model is also introduced. We analyze and contrast the control technique of condensate depression as conventional PI control, fuzzy PI control and fuzzy control. It is indicated that if the controller of condensate depression were devised inappropriate, while the steam discharged of turbine varying by a large margin, would result in the rotation rate of cooling water circulating pump accelerating at a great lick even to trigger the galloping danger which is less impressive for the units operating safely.

Uniformity and diversity in the composition of mineralizing fluids from hydrothermal vents on the southern Juan de Fuca Ridge.

Science.gov (United States)

Philpotts, J.A.; Aruscavage, P. J.; Von Damm, Karen L.

1987-01-01

Abundances of Li, Na, K, Rb, Ca, Sr, Ba, Mn, Fe, Zn, and Si have been determined in fluid samples from 7 vents located in three areas on the southern Juan de Fuca Ridge. The hydrothermal component estimated from the Mg contents of the samples ranges from 7% to 76%. Concentrations of Fe and Si, among other elements, in acid-stabilized solutions appear to be generally representative of the parental hydrothermal fluids, but some Zn determinations and most Ba values appear to be too low.-from Authors

Zero Gravity Cryogenic Vent System Concepts for Upper Stages

Science.gov (United States)

Ravex, Alain; Flachbart, Robin; Holt, Barney

The capability to vent in zero gravity without resettling is a technology need that involves practically all uses of sub-critical cryogenics in space. Venting without resettling would extend cryogenic orbital transfer vehicle capabilities. However, the lack of definition regarding liquid/ullage orientation coupled with the somewhat random nature of the thermal stratification and resulting pressure rise rates, lead to significant technical challenges. Typically a zero gravity vent concept, termed a thermodynamic vent system (TVS), consists of a tank mixer to destratify the propellant, combined with a Joule-Thomson (J-T) valve to extract thermal energy from the propellant. Marshall Space Flight Center's (MSFC's) Multipurpose Hydrogen Test Bed (MHTB) was used to test both spray bar and axial jet TVS concepts. The axial jet system consists of a recirculation pump heat exchanger unit. The spray bar system consists of a recirculation pump, a parallel flow concentric tube, heat exchanger, and a spray bar positioned close to the longitudinal axis of the tank. The operation of both concepts is similar. In the mixing mode, the recirculation pump withdraws liquid from the tank and sprays it into the tank liquid, ullage, and exposed tank surfaces. When energy extraction is required, a small portion of the recirculated liquid is passed sequentially through the J-T expansion valve, the heat exchanger, and is vented overboard. The vented vapor cools the circulated bulk fluid, thereby removing thermal energy and reducing tank pressure. The pump operates alone, cycling on and off, to destratify the tank liquid and ullage until the liquid vapor pressure reaches the lower set point. At that point, the J-T valve begins to cycle on and off with the pump. Thus, for short duration missions, only the mixer may operate, thus minimizing or even eliminating boil-off losses. TVS performance testing demonstrated that the spray bar was effective in providing tank pressure control within a 6

Modelling of vented dust explosions – empirical foundation and prospects for future validation of CFD codes

OpenAIRE

Skjold, Trygve; Wingerden, Kees van; Hansen, Olav R.; Eckhoff, Rolf Kristian

2008-01-01

Presented at: HAZARDS XX, Manchester, 23–25 November 2008 Explosion venting is the most frequently used method for mitigating the effects from accidental dust explosions in the process industry. Optimal design of vent systems and credible execution of risk assessments in powder handling plants require practical and reliable ways of predicting the course and consequences of vented dust explosions. The main parameters of interest include flame propagation and pressure build-up ...

Universal Themes of Bose-Einstein Condensation

Science.gov (United States)

Proukakis, Nick P.; Snoke, David W.; Littlewood, Peter B.

2017-04-01

Foreword; List of contributors; Preface; Part I. Introduction: 1. Universality and Bose-Einstein condensation: perspectives on recent work D. W. Snoke, N. P. Proukakis, T. Giamarchi and P. B. Littlewood; 2. A history of Bose-Einstein condensation of atomic hydrogen T. Greytak and D. Kleppner; 3. Twenty years of atomic quantum gases: 1995-2015 W. Ketterle; 4. Introduction to polariton condensation P. B. Littlewood and A. Edelman; Part II. General Topics: Editorial notes; 5. The question of spontaneous symmetry breaking in condensates D. W. Snoke and A. J. Daley; 6. Effects of interactions on Bose-Einstein condensation R. P. Smith; 7. Formation of Bose-Einstein condensates M. J. Davis, T. M. Wright, T. Gasenzer, S. A. Gardiner and N. P. Proukakis; 8. Quenches, relaxation and pre-thermalization in an isolated quantum system T. Langen and J. Schmiedmayer; 9. Ultracold gases with intrinsic scale invariance C. Chin; 10. Berezinskii-Kosterlitz-Thouless phase of a driven-dissipative condensate N. Y. Kim, W. H. Nitsche and Y. Yamamoto; 11. Superfluidity and phase correlations of driven dissipative condensates J. Keeling, L. M. Sieberer, E. Altman, L. Chen, S. Diehl and J. Toner; 12. BEC to BCS crossover from superconductors to polaritons A. Edelman and P. B. Littlewood; Part III. Condensates in Atomic Physics: Editorial notes; 13. Probing and controlling strongly correlated quantum many-body systems using ultracold quantum gases I. Bloch; 14. Preparing and probing chern bands with cold atoms N. Goldman, N. R. Cooper and J. Dalibard; 15. Bose-Einstein condensates in artificial gauge fields L. J. LeBlanc and I. B. Spielman; 16. Second sound in ultracold atomic gases L. Pitaevskii and S. Stringari; 17. Quantum turbulence in atomic Bose-Einstein condensates N. G. Parker, A. J. Allen, C. F. Barenghi and N. P. Proukakis; 18. Spinor-dipolar aspects of Bose-Einstein condensation M. Ueda; Part IV. Condensates in Condensed Matter Physics: Editorial notes; 19. Bose

Assessment of TRACE Condensation Model Against Reflux Condensation Tests with Noncondensable Gases

Energy Technology Data Exchange (ETDEWEB)

Lee, Kyung Won; Cheong, Ae Ju; Shin, Andong; Suh, Nam Duk [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

2015-05-15

The TRACE is the latest in a series of advanced, best-estimated reactor systems code developed by U.S. Nuclear Regulatory Commission for analyzing transient and steady-state neutronic-thermal-hydraulic behavior in light water reactors. This special model is expected to replace the default model in a future code release after sufficient testing has been completed. This study assesses the special condensation model of TRACE 5.0-patch4 against the counter-current flow configuration. For this purpose, the predicted results of special model are compared to the experimental and to those of default model. The KAST reflux condensation test with NC gases are used in this assessment. We assessed the special model for film condensation of TRACE 5.0-patch4 against the data of the reflux condensation test in the presence of NC gases. The special condensation model of TRACE provides a reasonable estimate of HTC with good agreement at the low inlet steam flow rate.

Assessment of TRACE Condensation Model Against Reflux Condensation Tests with Noncondensable Gases

International Nuclear Information System (INIS)

Lee, Kyung Won; Cheong, Ae Ju; Shin, Andong; Suh, Nam Duk

2015-01-01

The TRACE is the latest in a series of advanced, best-estimated reactor systems code developed by U.S. Nuclear Regulatory Commission for analyzing transient and steady-state neutronic-thermal-hydraulic behavior in light water reactors. This special model is expected to replace the default model in a future code release after sufficient testing has been completed. This study assesses the special condensation model of TRACE 5.0-patch4 against the counter-current flow configuration. For this purpose, the predicted results of special model are compared to the experimental and to those of default model. The KAST reflux condensation test with NC gases are used in this assessment. We assessed the special model for film condensation of TRACE 5.0-patch4 against the data of the reflux condensation test in the presence of NC gases. The special condensation model of TRACE provides a reasonable estimate of HTC with good agreement at the low inlet steam flow rate

Formic acid

Energy Technology Data Exchange (ETDEWEB)

Nielsen, H; Laing, B

1921-12-03

The production of formic acid by the oxidation of methane with a metallic oxide or by the interaction of carbon monoxide and water vapor in the presence of a catalyst, preferably a metallic oxide, is described along with the destructive distillation of carbonaceous material in the preesnce of formic acid vapor for the purpose of increasing the yield of condensible hydrocarbons.

Blast from pressurized carbon dioxide released into a vented atmospheric chamber

Science.gov (United States)

Hansen, P. M.; Gaathaug, A. V.; Bjerketvedt, D.; Vaagsaether, K.

2018-03-01

This study describes the blast from pressurized carbon dioxide (CO2) released from a high-pressure reservoir into an openly vented atmospheric chamber. Small-scale experiments with pure vapor and liquid/vapor mixtures were conducted and compared with simulations. A motivation was to investigate the effects of vent size and liquid content on the peak overpressure and impulse response in the atmospheric chamber. The comparison of vapor-phase CO2 test results with simulations showed good agreement. This numerical code described single-phase gas dynamics inside a closed chamber, but did not model any phase transitions. Hence, the simulations described a vapor-only test into an unvented chamber. Nevertheless, the simulations reproduced the incident shock wave, the shock reflections, and the jet release inside the atmospheric chamber. The rapid phase transition did not contribute to the initial shock strength in the current test geometry. The evaporation rate was too low to contribute to the measured peak overpressure that was in the range of 15-20 kPa. The simulation results produced a calculated peak overpressure of 12 kPa. The liquid tests showed a significantly higher impulse compared to tests with pure vapor. Reducing the vent opening from 0.1 to 0.01 m2 resulted in a slightly higher impulse calculated at 100 ms. The influence of the vent area on the calculated impulse was significant in the vapor-phase tests, but not so clear in the liquid/vapor mixture tests.

Implementation of non-condensable gases condensation suppression model into the WCOBRA/TRAC-TF2 LOCA safety evaluation code

Energy Technology Data Exchange (ETDEWEB)

Liao, J.; Cao, L.; Ohkawa, K.; Frepoli, C. [LOCA Integrated Services I, Westinghouse Electric Company, 1000 Westinghouse Drive, Cranberry Township, PA 16066 (United States)

2012-07-01

The non-condensable gases condensation suppression model is important for a realistic LOCA safety analysis code. A condensation suppression model for direct contact condensation was previously developed by Westinghouse using first principles. The model is believed to be an accurate description of the direct contact condensation process in the presence of non-condensable gases. The Westinghouse condensation suppression model is further revised by applying a more physical model. The revised condensation suppression model is thus implemented into the WCOBRA/TRAC-TF2 LOCA safety evaluation code for both 3-D module (COBRA-TF) and 1-D module (TRAC-PF1). Parametric study using the revised Westinghouse condensation suppression model is conducted. Additionally, the performance of non-condensable gases condensation suppression model is examined in the ACHILLES (ISP-25) separate effects test and LOFT L2-5 (ISP-13) integral effects test. (authors)

Effect of flow velocity on the process of air-steam condensation in a vertical tube condenser

Science.gov (United States)

Havlík, Jan; Dlouhý, Tomáš

2018-06-01

This article describes the influence of flow velocity on the condensation process in a vertical tube. For the case of condensation in a vertical tube condenser, both the pure steam condensation process and the air-steam mixture condensation process were theoretically and experimentally analyzed. The influence of steam flow velocity on the value of the heat transfer coefficient during the condensation process was evaluated. For the condensation of pure steam, the influence of flow velocity on the value of the heat transfer coefficient begins to be seen at higher speeds, conversely, this effect is negligible at low values of steam velocity. On the other hand, for the air-steam mixture condensation, the influence of flow velocity must always be taken into account. The flow velocity affects the water vapor diffusion process through non-condensing air. The presence of air significantly reduces the value of the heat transfer coefficient. This drop in the heat transfer coefficient is significant at low velocities; on the contrary, the decrease is relatively small at high values of the velocity.

Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation

Directory of Open Access Journals (Sweden)

Henning Hopf

2014-08-01

Full Text Available Under basic conditions 4,5,12,13-tetraacetyl[2.2]paracyclophane (9 cyclizes by a double aldol condensation to provide the two aldols 12 and 15 in a 3:7 ratio. The structures of these compounds were obtained from X-ray structural analysis, spectroscopic data, and mechanistic considerations. On acid treatment 12 is dehydrated to a mixture of the condensed five-membered [2.2]paracyclophane derivatives 18–20, whereas 15 yields a mixture of the isomeric cyclopentadienones 21–23. The structures of these elimination products are also deduced from X-ray and spectroscopic data. The sequence presented here constitutes the simplest route so far to cyclophanes carrying an annelated five-membered ring.

Experimental investigation of passive thermodynamic vent system (TVS) with liquid nitrogen

Science.gov (United States)

Bae, Junhyuk; Yoo, Junghyun; Jin, Lingxue; Jeong, Sangkwon

2018-01-01

Thermodynamic vent system (TVS) is an attractive technology to maintain an allowable pressure level of a cryogenic propellant storage in a spacecraft under micro-gravity condition. There are two types of TVS; active or passive. In this paper, the passive TVS which does not utilize a cryogenic liquid circulation pump is experimentally investigated with liquid nitrogen and numerically analyzed by thermodynamic and heat transfer model. A cylindrical copper tank, which is 198 mm in inner diameter and 216 mm in height, is utilized to suppress a thermal-stratification effect of inside cryogenic fluid. A coil heat exchanger, which is 3 m in length and 6.35 mm in outer diameter, and a fixed size orifice of which diameter is 0.4 mm are fabricated to remove heat from the stored fluid to the vented flow. Each vent process is initiated at 140 kPa and ended at 120 kPa with liquid nitrogen fill levels which are 30%, 50% and 70%, respectively. In the numerical model, the fluid in the tank is assumed to be homogeneous saturated liquid-vapor. Mass and energy balance equations with heat transfer conditions suggested in this research are considered to calculate the transient pressure variation in the tank and the amount of heat transfer across the heat exchanger. We achieve the average heat rejection rate of more than 9 W by TVS and conclude that the passive TVS operates satisfactorily. In addition, the prediction model is verified by experimental results. Although the model has limitation in providing accurate results, it can surely predict the tendency of pressure and temperature changes in the tank. Furthermore, the model can suggest how we can improve the heat exchanger design to enhance an overall efficiency of passive TVS. Moreover, the performance of passive TVS is compared with other cryogenic vent systems (direct vent system and active TVS) by suggested performance indicator.

Condensation: the new deal; Condensation: la nouvelle donne

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-06-01

The principle of condensation boilers is based on the recovery of the latent heat of the steam generated by the combustion of natural gas. This technology was introduced in France at the end of the 80's but failed in its promise because of the complexity of the equipments available at that time. Today, constructors' offer is more mature and reliable and the context has changed. This technology can conciliate three goals: a mastery of energy consumptions, the comfort of the user and the respect of environment. This meeting organized by the research center of Gaz de France (Cegibat), was a good opportunity to makes a status of the market of individual condensation systems in France and in Europe, to present the situation of this technology today and the 10 golden rules for the fitting and maintenance of individual condensation boilers, and to present some technical references, examples and results of today's offer. (J.S.)

Dew point of gases with low sulfuric acid content

Energy Technology Data Exchange (ETDEWEB)

Fieg, J.

1981-07-01

Discusses control of air pollution caused by sulfur compounds in solid fuels during combustion. Excessive amount of oxygen during combustion leads to formation of sulfur trioxide. Sulfur trioxide reacts with water vapor and forms sulfuric acid. Chemical reactions which lead to formation of sulfuric acid are described. Conditions for sulfuric acid condensation are analyzed. Several methods for determining dew point of flue gases with low sulfuric acid content are reviewed: methods based on determination of electric conductivity of condensed sulfuric acid (Francis, Cheney, Kiyoure), method based on determination of sulfuric acid concentration in the gaseous phase and in the liquid phase after cooling (Lee, Lisle and Sensenbaugh, Ross and Goksoyr). (26 refs.) (In Polish)

Response of Cloud Condensation Nuclei (> 50 nm) to changes in ion-nucleation

DEFF Research Database (Denmark)

Svensmark, Henrik; Enghoff, Martin B.; Pedersen, Jens Olaf Pepke

2012-01-01

In experiments where ultraviolet light produces aerosols from trace amounts of ozone, sulphur dioxide, and water vapour, the number of additional small particles produced by ionization by gamma sources all grow up to diameters larger than 50 nm, appropriate for cloud condensation nuclei. This res......In experiments where ultraviolet light produces aerosols from trace amounts of ozone, sulphur dioxide, and water vapour, the number of additional small particles produced by ionization by gamma sources all grow up to diameters larger than 50 nm, appropriate for cloud condensation nuclei...... finding points to a process not included in current theoretical models, possibly an ion-induced formation of sulphuric acid in small clusters....

The invasive Red-vented bulbul (Pycnonotus cafer) outcompetes native birds in a tropical biodiversity hotspot.

Science.gov (United States)

Thibault, Martin; Vidal, Eric; Potter, Murray Alan; Sanchez, Thierry; Brescia, Fabrice

2018-01-01

Invasive alien species are a major cause of biodiversity loss globally, but especially on islands where high species richness and levels of endemism accentuate their impacts. The Red vented bulbul (Pycnonotus cafer), a tropical passerine bird that has been introduced widely across locations of high conservation value, is considered an extreme pest. It is currently expanding its range in New Caledonia, one of the world's biodiversity hotspots. Decisive recommendations on management strategies are required urgently to inform local managers and policy makers, but they should be based on quantitative local evidence, not just on expert opinion. The Red-vented bulbul is widely blamed for its impacts on biodiversity, especially through competition. We used data from 2,472 point counts to explore the abundance relationships between the Red-vented bulbul and 14 other species of bird. Our results revealed a negative relationship between the occurrence of the bulbul and the mean abundance of nine species, all native (or endemic, n = 3) to the New Caledonia archipelago. In contrast, the abundance of other introduced species such as Acridotheres tristis (Common myna), Passer domesticus (House sparrow) and Spilopelia chinensis (Spotted dove) were not affected by the Red-vented bulbul. Moreover, temporal trends in the abundance of impacted species suggest that the Red-vented bulbul may cause niche contractions rather than mortality for native species in man-modified habitats. Monitoring and control of the Red-vented bulbul is recommended to prevent on-going impacts on native bird communities throughout New Caledonia, and its impact on native bird communities elsewhere should be quantified.

The invasive Red-vented bulbul (Pycnonotus cafer outcompetes native birds in a tropical biodiversity hotspot.

Directory of Open Access Journals (Sweden)

Martin Thibault

Full Text Available Invasive alien species are a major cause of biodiversity loss globally, but especially on islands where high species richness and levels of endemism accentuate their impacts. The Red vented bulbul (Pycnonotus cafer, a tropical passerine bird that has been introduced widely across locations of high conservation value, is considered an extreme pest. It is currently expanding its range in New Caledonia, one of the world's biodiversity hotspots. Decisive recommendations on management strategies are required urgently to inform local managers and policy makers, but they should be based on quantitative local evidence, not just on expert opinion. The Red-vented bulbul is widely blamed for its impacts on biodiversity, especially through competition. We used data from 2,472 point counts to explore the abundance relationships between the Red-vented bulbul and 14 other species of bird. Our results revealed a negative relationship between the occurrence of the bulbul and the mean abundance of nine species, all native (or endemic, n = 3 to the New Caledonia archipelago. In contrast, the abundance of other introduced species such as Acridotheres tristis (Common myna, Passer domesticus (House sparrow and Spilopelia chinensis (Spotted dove were not affected by the Red-vented bulbul. Moreover, temporal trends in the abundance of impacted species suggest that the Red-vented bulbul may cause niche contractions rather than mortality for native species in man-modified habitats. Monitoring and control of the Red-vented bulbul is recommended to prevent on-going impacts on native bird communities throughout New Caledonia, and its impact on native bird communities elsewhere should be quantified.

Self-condensation of n-(N-propyl)butanimine: NMR and mass spectral analyses and investigation by theoretical calculation

Energy Technology Data Exchange (ETDEWEB)

Manfrini, Rozangela Magalhaes; Teixeira, Flavia Rodrigues; Pilo-Veloso, Dorila; Alcantara, Antonio Flavio de Carvalho, E-mail: aalcantara@zeus.qui.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Inst. de Ciencias Exatas. Dept. de Quimica; Nelson, David Lee [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Fac. de Farmacia. Dept. de Quimica; Siqueira, Ezequias Pessoa de [Centro de Pesquisas Rene Rachou (FIOCRUZ), Belo Horizonte, MG (Brazil)

2012-07-01

The stability of N-propylbutanimine (1) was investigated under different experimental conditions. The acid-catalyzed self-condensation that produced the E-enimine (4) and Z-inimine (5) was studied by experimental analyses and theoretical calculations. Since the calculations for the energy of 5 indicated that it had a lower energy than 4, yet 4 was the principal product, the self-condensation of 1 must be kinetically controlled. (author)

Spatial and Temporal Population Genetics at Deep-Sea Hydrothermal Vents Along the East Pacific Rise and Galapagos Rift

Science.gov (United States)

2008-09-01

frequent physical disturbance. Earval dispersal among disjunct vent sites facilitates the persistence of sessile invertebrate species in these...among disjunct vent sites facilitates the persistence of sessile invertebrate species in these geologically and chemically dynamic habitats despite...the reproductive biology of the hydrothermal vent tube worm Riftia pachyptila. Marine Ecology Progress Series, 52, 89-94. Chevaldonne P, Jollivet D

The effects of venting and decompression on Yellow Tang (Zebrasoma flavescens in the marine ornamental aquarium fish trade

Directory of Open Access Journals (Sweden)

Emily S. Munday

2015-02-01

Full Text Available Each year, over 45 countries export 30 million fish from coral reefs as part of the global marine ornamental aquarium trade. This catch volume is partly influenced by collection methods that cause mortality. Barotrauma in fish resulting from forced ascent from depth can contribute to post-collection mortality. However, implementing decompression stops during ascent can prevent barotrauma. Conversely, venting (puncturing the swim bladder to release expanded internal gas following ascent can mitigate some signs of barotrauma like positive buoyancy. Here, we evaluate how decompression and venting affect stress and mortality in the Yellow Tang (Zebrasoma flavescens. We examined the effects of three ascent treatments, each with decompression stops of varying frequency and duration, coupled with or without venting, on sublethal effects and mortality using histology and serum cortisol measurements. In fish subjected to ascent without decompression stops or venting, a mean post-collection mortality of 6.2% occurred within 24 h of capture. Common collection methods in the fishery, ascent without decompression stops coupled with venting, or one long decompression stop coupled with venting, resulted in no mortality. Histopathologic examination of heart, liver, head kidney, and swim bladder tissues in fish 0d and 21d post-collection revealed no significant barotrauma- or venting-related lesions in any treatment group. Ascent without decompression stops resulted in significantly higher serum cortisol than ascent with many stops, while venting alone did not affect cortisol. Future work should examine links in the supply chain following collection to determine if further handling and transport stressors affect survivorship and sublethal effects.

Antiradiation compounds XV: condensations of carbon disulfide with amino, chloro, cyanomethyl, and sulfonamido heterocycles

International Nuclear Information System (INIS)

Foye, W.O.; Kauffman, J.M.; Lanzillo, J.J.; LaSala, E.F.

1975-01-01

Condensations of carbon disulfide were carried out with amino, chloro, and diamino heterocycles to give condensed ring thiazoline-2-thiones and imidazoline-2-thiones, with cyanomethyl heterocycles to give dithio acid derivatives, and with heterocyclic sulfonamides to give sulfonyldithiocarbamates. Of several examples tested, pyrido[3,2-d]thiazoline-2-thione, disodium 2-(5-chloro-2-thienyl)-3,3-dimercaptoacrylonitrile, triethylammonium 4-sulfamoylphenyldithiocarbamate, ammonium β-phenethyldithiocarbamate, and methyl N-(thiophene-2-sulfonyl)dithiocarbamate, only the last-named compound showed any radiation protection for mice. Several compounds gave negative tests for antimalarial activity

Born-Kothari Condensation for Fermions

Directory of Open Access Journals (Sweden)

Arnab Ghosh

2017-09-01

Full Text Available In the spirit of Bose–Einstein condensation, we present a detailed account of the statistical description of the condensation phenomena for a Fermi–Dirac gas following the works of Born and Kothari. For bosons, while the condensed phase below a certain critical temperature, permits macroscopic occupation at the lowest energy single particle state, for fermions, due to Pauli exclusion principle, the condensed phase occurs only in the form of a single occupancy dense modes at the highest energy state. In spite of these rudimentary differences, our recent findings [Ghosh and Ray, 2017] identify the foregoing phenomenon as condensation-like coherence among fermions in an analogous way to Bose–Einstein condensate which is collectively described by a coherent matter wave. To reach the above conclusion, we employ the close relationship between the statistical methods of bosonic and fermionic fields pioneered by Cahill and Glauber. In addition to our previous results, we described in this mini-review that the highest momentum (energy for individual fermions, prerequisite for the condensation process, can be specified in terms of the natural length and energy scales of the problem. The existence of such condensed phases, which are of obvious significance in the context of elementary particles, have also been scrutinized.

Solution gas flaring and venting at Alberta primary crude bitumen operations

Energy Technology Data Exchange (ETDEWEB)

Ruff, C. [Alberta Energy and Utilities Board, Calgary, AB (Canada)

2005-11-01

The Alberta Energy and Utilities Board is mandated by the Government of Alberta to ensure fair, responsible development and delivery of energy resources and utilities services in Alberta while maintaining the best public interest. One of the agencies' priorities is the reduction of solution gas flaring and venting. The performance of solution gas flaring and venting in Alberta and best practices respecting solution gas conservation are discussed. Data was presented on solution gas production, solution gas conserved, and solution gas conservation efficiency. The paper described best practices solutions such as increased gas to oil (GOR) test frequency; predetermination of economic gas conservation; collaboration with county gas utilities; and utilization of portable and scalable gas compression. The paper also presents a discussion of the Clean Air Strategic Alliance (CASA), a non-profit multistakeholder that recommended enhancements to Guide 60. Requirements discussed include the requirement to conserve solution gas at certain sites exceeding established flare and vent volumes, gas conservation prebuild requirements, and enhanced economic evaluation process. 5 figs.

From cation to oxide: hydroxylation and condensation of aqueous complexes

International Nuclear Information System (INIS)

Jolivet, J.P.

1997-01-01

Hydroxylation, condensation and precipitation of metal cations in aqueous solution are briefly reviewed. Hydroxylation of aqueous complexes essentially depends on the format charge (oxidation state), the size and the pH of the medium. It is the step allowing the condensation reaction. Depending on the nature of complexes (aqua-hydroxo, oxo-hydroxo), the. mechanism of condensation is different, olation or ox-olation respectively. The first one leads to poly-cations or hydroxides more or less stable against dehydration. The second one leads to poly-anions or oxides. Oligomeric species (poly-cations, poly-anions) are form from charged monomer complexes while the formation of solid phases requires non-charged precursors. Because of their high lability, charged oligomers are never the precursors of solids phases. The main routes for the formation of solid phases from solution are studied with two important and representative elements, Al and Si. For Al 3+ ions, different methods (base addition in solution, thermo-hydrolysis, hydrothermal synthesis) are discussed in relation to the crystal structure of the solid phase obtained. For silicic species condensing by ox-olation, the role of acid or base catalysis on the morphology of gels is studied. The influence of complexing ligands on the processes and on the characteristics of solids (morphology of particles, basic salts and polymetallic oxides formation) is studied. (author)

Condensation in Nanoporous Packed Beds.

Science.gov (United States)

Ally, Javed; Molla, Shahnawaz; Mostowfi, Farshid

2016-05-10

In materials with tiny, nanometer-scale pores, liquid condensation is shifted from the bulk saturation pressure observed at larger scales. This effect is called capillary condensation and can block pores, which has major consequences in hydrocarbon production, as well as in fuel cells, catalysis, and powder adhesion. In this study, high pressure nanofluidic condensation studies are performed using propane and carbon dioxide in a colloidal crystal packed bed. Direct visualization allows the extent of condensation to be observed, as well as inference of the pore geometry from Bragg diffraction. We show experimentally that capillary condensation depends on pore geometry and wettability because these factors determine the shape of the menisci that coalesce when pore filling occurs, contrary to the typical assumption that all pore structures can be modeled as cylindrical and perfectly wetting. We also observe capillary condensation at higher pressures than has been done previously, which is important because many applications involving this phenomenon occur well above atmospheric pressure, and there is little, if any, experimental validation of capillary condensation at such pressures, particularly with direct visualization.

Comparison of Heat Transfer Coefficients of Silver Coated and Chromium Coated Copper Tubes of Condenser in Dropwise Condensation

OpenAIRE

Er. Shivesh Kumar; Dr. Amit Kumar

2016-01-01

Since centuries steam is being used in power generating system. The steam leaving the power unit is reconverted into water in a condenser designed to transfer heat from the steam to the cooling water as rapidly and as efficiently as possible. The efficiency of condenser depends on rate of condensation and mode of condensation of steam in the condenser. The increase in efficiency of the condenser enhances the heat transfer co-efficient which in turn results in economic design of condenser and ...

Bio-oil fractionation and condensation

Science.gov (United States)

Brown, Robert C; Jones, Samuel T; Pollard, Anthony

2013-07-02

A method of fractionating bio-oil vapors which involves providing bio-oil vapors comprising bio-oil constituents is described. The bio-oil vapors are cooled in a first stage which comprises a condenser having passages for the bio-oil separated by a heat conducting wall from passages for a coolant. The coolant in the condenser of the first stage is maintained at a substantially constant temperature, set at a temperature in the range of 75 to 100.degree. C., to condense a first liquid fraction of liquefied bio-oil constituents in the condenser of the first stage. The first liquid fraction of liquified bio-oil constituents from the condenser in the first stage is collected. Also described are steps for subsequently recovering further liquid fractions of liquefied bio-oil constituents. Particular compositions of bio-oil condensation products are also described.

Condenser performance monitoring and cleaning

International Nuclear Information System (INIS)

Walden, J.V.

1998-01-01

The main condenser at Ginna Station was retubed from admiralty brass to 316 stainless steel. A condenser performance monitoring spreadsheet was developed using EPRI guidelines after fouling was discovered. PEPSE computer models were used to determine the power loss and confirm the spreadsheet results. Cleaning of the condenser was performed using plastic scrubbers. Condenser performance improved dramatically following the cleaning. PEPSE, condenser spreadsheet performance, and actual observed plant data correlated well together. The fouling mechanism was determined to be a common lake bacteria and fungus growth which was combined with silt. Chlorination of the circulating water system at the allowable limits is keeping the biofouling under control

Chromosome condensation and segmentation

International Nuclear Information System (INIS)

Viegas-Pequignot, E.M.

1981-01-01

Some aspects of chromosome condensation in mammalians -humans especially- were studied by means of cytogenetic techniques of chromosome banding. Two further approaches were adopted: a study of normal condensation as early as prophase, and an analysis of chromosome segmentation induced by physical (temperature and γ-rays) or chemical agents (base analogues, antibiotics, ...) in order to show out the factors liable to affect condensation. Here 'segmentation' means an abnormal chromosome condensation appearing systematically and being reproducible. The study of normal condensation was made possible by the development of a technique based on cell synchronization by thymidine and giving prophasic and prometaphasic cells. Besides, the possibility of inducing R-banding segmentations on these cells by BrdU (5-bromodeoxyuridine) allowed a much finer analysis of karyotypes. Another technique was developed using 5-ACR (5-azacytidine), it allowed to induce a segmentation similar to the one obtained using BrdU and identify heterochromatic areas rich in G-C bases pairs [fr

Characteristic aspects of pion-condensed phases

International Nuclear Information System (INIS)

Takatsuka, Tatsuyuki; Tamagaki, Ryozo; Tatsumi, Toshitaka.

1993-01-01

Characteristic aspects of pion-condensed phases are described in a simple model, for the system involving only nucleons and pions which interact through the π-N P-wave interaction. We consider one typical version in each of three kinds of pion condensation; the one of neutral pions (π 0 ), the one of charged pions (π C ) and the combined one in which both the π 0 and π C condensations are coexistent. Emphasis is put on the description to clarify the novel structures of the nucleon system which are realized in the pion-condensed phases. At first, it is shown that the π 0 condensation is equivalent to the particular nucleonic phase realized by a structure change of the nucleon system, where the attractive first-order effect of the one-pion-exchange (OPE) tensor force is brought about coherently. The aspects of this phase are characterized by the layered structure with a specific spin-isospin order with one-dimensional localization (named the ALS structure in short), which provides the source function for the condensed π 0 field. We utilize both descriptions with use of fields and potentials for the π 0 condensation. Next, the π C condensation realized in neutron-rich matter is described by adopting a version of the traveling condensed wave. In this phase, the nucleonic structure becomes the Fermi gas consisting of quasi-neutrons described by a superposition of neutron and proton. In this sense the structure change of the nucleon system for the π C condensation is moderate, and the field description is suitable. Finally, we describe a coexistent pion condensation, in which both the π 0 and π C condensations coexist without interference in such a manner that the π C condensation develops in the ALS structure. The model adopted here provides us with the characteristic aspects of the pion-condensed phases persisting in the realistic situation, where other ingredients affecting the pion condensation are taken into account. (author)

Effect of surface etching on condensing heat transfer

Energy Technology Data Exchange (ETDEWEB)

Seok, Sung Chul; Park, Jae Won; Jung, Jiyeon; Choi, Chonggun; Choi, Gyu Hong; Hwang, Seung Sik; Chung, Tae Yong; Shin, Donghoon [Kookmin University, Seoul (Korea, Republic of); Kim, Jin Jun [Hoseo University, Asan (Korea, Republic of)

2016-02-15

This study conducted experiments on humid air condensation during heat transfer in an air preheating exchanger attached to a home condensing boiler to improve thermal efficiency. An etchant composed of sulfuric acid and sodium nitrate was used to create roughness on the heat exchanger surface made from STS430J1L. A counter flow heat exchanger was fabricated to test the performance of heat transfer. Results showed that the overall heat transfer coefficients of all specimens treated with etchant improved with respect to the original specimens (not treated with etchant), and the overall heat transfer coefficient of the 60 s etching specimen increased by up to 15%. However, the increasing rate of the heat transfer coefficient was disproportional to the etching time. When the etching time specifically increased above 60 s, the heat transfer coefficient decreased. This effect was assumed to be caused by surface characteristics such as contact angle. Furthermore, a smaller contact angle or higher hydrophilicity leads to higher heat transfer coefficient.

Technical note: In vitro total gas and methane production measurements from closed or vented rumen batch culture systems.

Science.gov (United States)

Cattani, M; Tagliapietra, F; Maccarana, L; Hansen, H H; Bailoni, L; Schiavon, S

2014-03-01

This study compared measured gas production (GP) and computed CH4 production values provided by closed or vented bottles connected to gas collection bags. Two forages and 3 concentrates were incubated. Two incubations were conducted, where the 5 feeds were tested in 3 replicates in closed or vented bottles, plus 4 blanks, for a total of 64 bottles. Half of the bottles were not vented, and the others were vented at a fixed pressure (6.8 kPa) and gas was collected into one gas collection bag connected to each bottle. Each bottle (317 mL) was filled with 0.4000 ± 0.0010 g of feed sample and 60 mL of buffered rumen fluid (headspace volume = 257 mL) and incubated at 39.0°C for 24 h. At 24 h, gas samples were collected from the headspace of closed bottles or from headspace and bags of vented bottles and analyzed for CH4 concentration. Volumes of GP at 24 h were corrected for the gas dissolved in the fermentation fluid, according to Henry's law of gas solubility. Methane concentration (mL/100mL of GP) was measured and CH4 production (mL/g of incubated DM) was computed using corrected or uncorrected GP values. Data were analyzed for the effect of venting technique (T), feed (F), interaction between venting technique and feed (T × F), and incubation run as a random factor. Closed bottles provided lower uncorrected GP (-18%) compared with vented bottles, especially for concentrates. Correction for dissolved gas reduced but did not remove differences between techniques, and closed bottles (+25 mL of gas/g of incubated DM) had a greater magnitude of variation than did vented bottles (+1 mL of gas/g of incubated DM). Feeds differed in uncorrected and corrected GP, but the ranking was the same for the 2 techniques. The T × F interaction influenced uncorrected GP values, but this effect disappeared after correction. Closed bottles provided uncorrected CH4 concentrations 23% greater than that of vented bottles. Correction reduced but did not remove this difference. Methane

Systematic text condensation

DEFF Research Database (Denmark)

Malterud, Kirsti

2012-01-01

To present background, principles, and procedures for a strategy for qualitative analysis called systematic text condensation and discuss this approach compared with related strategies.......To present background, principles, and procedures for a strategy for qualitative analysis called systematic text condensation and discuss this approach compared with related strategies....

40 CFR 63.457 - Test methods and procedures.

Science.gov (United States)

2010-07-01

... 60, appendix A, as appropriate. (4) The moisture content of the vent gas shall be measured using... as to not entrain liquid condensation from the vent gases. The other end shall be connected to the...

Steam generators, turbines, and condensers. Volume six

International Nuclear Information System (INIS)

Anon.

1986-01-01

Volume six covers steam generators (How steam is generated, steam generation in a PWR, vertical U-tube steam generators, once-through steam generators, how much steam do steam generators make?), turbines (basic turbine principles, impulse turbines, reaction turbines, turbine stages, turbine arrangements, turbine steam flow, steam admission to turbines, turbine seals and supports, turbine oil system, generators), and condensers (need for condensers, basic condenser principles, condenser arrangements, heat transfer in condensers, air removal from condensers, circulating water system, heat loss to the circulating water system, factors affecting condenser performance, condenser auxiliaries)

A CFD study of wave influence on film steam condensation in the presence of non-condensable gas

Energy Technology Data Exchange (ETDEWEB)

Wang, Xianmao, E-mail: xm-wang11@mails.tsinghua.edu.cn [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Chang, Huajian, E-mail: changhj@tsinghua.edu.cn [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Corradini, Michael, E-mail: corradini@engr.wisc.edu [Department of Engineering Physics, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, WI 53706 (United States)

2016-08-15

Highlights: • A condensation model is incorporated in the ANSYS FLUENT. • Different turbulence models are evaluated for flows over wavy surfaces. • Wavy surfaces with and without moving velocities are used to model the wave. • Various wavy surfaces with different wave heights and wavelengths are selected. • Wave influence on film steam condensation is investigated. - Abstract: Steam condensation plays an important role in removing heat from the containment of a nuclear plant during postulated accidents. However, due to the presence of non-condensable gases such as air and hydrogen in the containment, the condensation rate can decrease dramatically. Under certain conditions, the condensate film on the cold containment walls can affect the overall heat transfer rate. The wavy interface of the condensate film is a factor and is usually believed to enhance the condensation rate, since the waves can both increase the interfacial area and disturb the non-condensable gas boundary layer. However, it is not clear how to properly account for this factor and what is its quantitative influence in experiments. In this work, a CFD approach is applied to study the wave effects on film condensation in the presence of non-condensable gas. Wavy surfaces with and without moving velocities are used to replace the wavy interface of the falling film. A condensation model is incorporated in the ANSYS FLUENT simulation and a realizable k–ε turbulence model is applied. Various wavy surfaces with different wave heights and wavelengths are selected to conduct numerical experiments with a wide range of gas velocities. The results show that the wave structure can enhance condensation rate up to ten percent mainly due to the alteration of local flow structures in the gas phase. The increments of the condensation rate due to the wavy interface can vary with different gas velocities. The investigation shows that a multiplication factor accounts for the wave effects on film

Request for approval, vented container annual release fraction

International Nuclear Information System (INIS)

HILL, J.S.

1999-01-01

In accordance with the approval conditions for Modification to the Central Waste Complex (CWC) Radioactive Air Emissions Notice of Construction (NOC). dated August 24,1998, a new release fraction has been developed for submittal to the Washington State Department of Health (WDOH). The proposed annual release fraction of 2.50 E-14 is proposed for use in future NOCs involving the storage and handling operations associated with vented containers on the Hanford Site. The proposed annual release fraction was the largest release fraction calculated from alpha measurements of the NucFil filters from 10 vented containers consisting of nine 55-gallon drums and one burial box with dimensions of 9.3 x 5.7 x 6.4 feet. An annual release fraction of 2.0 E-09 was used in the modification to the CWC radioactive air emissions NOC. This study confirmed that the release fraction used in the CWC radioactive air emissions NOC was conservative

Population genetic structure of Rufous-Vented Prinia (Prinia burnesii ...

African Journals Online (AJOL)

Administrator

2010-12-27

Dec 27, 2010 ... INTRODUCTION. The Rufous-vented Prinia is an endemic species of the. Indian subcontinent that is ..... considerations in listing subspecies under the U.S. Endangered. Species Act. Cons. Biol. 6: 1584-1594. Heukeshoven J ...

Assessment of horizontal in-tube condensation models using MARS code. Part I: Stratified flow condensation

Energy Technology Data Exchange (ETDEWEB)

Jeon, Seong-Su [Department of Engineering Project, FNC Technology Co., Ltd., Bldg. 135-308, Seoul National University, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Department of Nuclear Engineering, Seoul National University, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Hong, Soon-Joon, E-mail: sjhong90@fnctech.com [Department of Engineering Project, FNC Technology Co., Ltd., Bldg. 135-308, Seoul National University, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Park, Ju-Yeop; Seul, Kwang-Won [Korea Institute of Nuclear Safety, 19 Kuseong-dong, Yuseong-gu, Daejon (Korea, Republic of); Park, Goon-Cherl [Department of Nuclear Engineering, Seoul National University, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

2013-01-15

Highlights: Black-Right-Pointing-Pointer This study collected 11 horizontal in-tube condensation models for stratified flow. Black-Right-Pointing-Pointer This study assessed the predictive capability of the models for steam condensation. Black-Right-Pointing-Pointer Purdue-PCCS experiments were simulated using MARS code incorporated with models. Black-Right-Pointing-Pointer Cavallini et al. (2006) model predicts well the data for stratified flow condition. Black-Right-Pointing-Pointer Results of this study can be used to improve condensation model in RELAP5 or MARS. - Abstract: The accurate prediction of the horizontal in-tube condensation heat transfer is a primary concern in the optimum design and safety analysis of horizontal heat exchangers of passive safety systems such as the passive containment cooling system (PCCS), the emergency condenser system (ECS) and the passive auxiliary feed-water system (PAFS). It is essential to analyze and assess the predictive capability of the previous horizontal in-tube condensation models for each flow regime using various experimental data. This study assessed totally 11 condensation models for the stratified flow, one of the main flow regime encountered in the horizontal condenser, with the heat transfer data from the Purdue-PCCS experiment using the multi-dimensional analysis of reactor safety (MARS) code. From the assessments, it was found that the models by Akers and Rosson, Chato, Tandon et al., Sweeney and Chato, and Cavallini et al. (2002) under-predicted the data in the main condensation heat transfer region, on the contrary to this, the models by Rosson and Meyers, Jaster and Kosky, Fujii, Dobson and Chato, and Thome et al. similarly- or over-predicted the data, and especially, Cavallini et al. (2006) model shows good predictive capability for all test conditions. The results of this study can be used importantly to improve the condensation models in thermal hydraulic code, such as RELAP5 or MARS code.

Preoperational test report, vent building ventilation system

International Nuclear Information System (INIS)

Clifton, F.T.

1997-01-01

This represents a preoperational test report for Vent Building Ventilation Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides Heating, Ventilation, and Air Conditioning (HVAC) for the W-030 Ventilation Building. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System

Diversity and distribution of microbes in deep-sea sub-vent systems, using newly designed in situ growth chambers

Science.gov (United States)

Higashi, Y.; Sunamura, M.; Utsumi, M.; Urabe, T.; Maruyama, A.

2004-12-01

Subsurface of deep-sea hydrothermal vent environments is one of the most difficult fields on the Earth to approach and collect reliable samples for microbiological study. In our Archaean Park project, we developed in situ incubation instruments to directly collect microbes from sub-vent fields through a drilled borehole. After excavation using a portable submarine driller (BMS) around deep-sea hydrothermal vents in the Suiyo Seamount on the Izu-Bonin Arc (2001, 2002) and the South Mariana (2003), microbial diversity was examined in samples collected from the boreholes, as well as natural vents, using catheter- and column-type in situ growth chambers. In the catheter samples collected from the Suiyo Seamount, several novel phylotypes of microbial SSU rRNA genes were assigned within epsilon-Proteobacteria and hyperthermophile-related Euryarchaea groups. The former novel epsilon group (SSSV-BE1) was also detected in the South Mariana, but they only appeared in the catheter samples collected just below the venting seafloor. These suggest that the group must be significant in warm, shallow and microaerobic sub-vent layers over the sea, at least in the northwest Pacific Ocean. The column-type in situ growth chamber was specially designed for creating and maintaining physico-chemical gradients in a ca. 40-cm-long column situated on an active vent. In Suiyo Seamount samples (vent temp.: ca. 30-100 degree C), a unique vertical profile was found in the diversity of Archaea. At the column bottom, most of the clones were assigned to be members within the lithoautotrophic thermophilic Ignicoccus, while heterotrophic thermophilic Thermococcus were abundant at the column top. Similar vertical profile has also been appeared in the column samples from the South Mariana. Further quantitative population analysis is now under going using these samples. Our approach to the sub-vent biosphere by the combination of drilling and in situ incubation is almost sure to give us important clues

Off gas condenser performance modelling

International Nuclear Information System (INIS)

Cains, P.W.; Hills, K.M.; Waring, S.; Pratchett, A.G.

1989-12-01

A suite of three programmes has been developed to model the ruthenium decontamination performance of a vitrification plant off-gas condenser. The stages of the model are: condensation of water vapour, NO x absorption in the condensate, RuO 4 absorption in the condensate. Juxtaposition of these stages gives a package that may be run on an IBM-compatible desktop PC. Experimental work indicates that the criterion [HNO 2 ] > 10 [RuO 4 ] used to determine RuO 4 destruction in solution is probably realistic under condenser conditions. Vapour pressures of RuO 4 over aqueous solutions at 70 o -90 o C are slightly lower than the values given by extrapolating the ln K p vs. T -1 relation derived from lower temperature data. (author)

Comparison of dehumidification and heat and vent drying of hem-fir softwood

Energy Technology Data Exchange (ETDEWEB)

Mackay, J F.G.; Nielson, R W

1988-03-01

The objective of this project was to demonstrate the performance of dehumidifier kilns, compared to gas-fired, hot-air kilns in drying a commercial grade of softwood lumber. To accomplish this, drying tests were conducted with matched loads of lumber in a new test facility which was constructed to operate as a conventional heat and vent kiln or as a dehumidifier kiln. Comparisons were made of drying times, shrinkage and quality of dried product and total drying energy consumptions. Data from these tests were used in conjunction with capital, energy and other costs obtained from suppliers and operators of existing kilns to make economic comparisons between commercial-sized dehumidifier and heat and vent kilns. These comparisons were made on the basis of equivalent uniform annual costs. Dehumidification drying took about 20% longer and used about 50% of energy compared to heat and vent drying. Analysis of the test runs indicated that further improvements in the energy utilization efficiencies of dehumidifier kilns are feasible since one run indicated an energy consumption of only 36% of that in heat and vent drying. No differences in shrinkage or degrade were apparent. Economic comparisons for three sizes of kilns showed total drying costs by dehumidification to be less for a small-size kiln but more for medium- and large-size operations. Sensitivity analyses were performed to observe the effect of alternate energy prices, dehumidifier energy consumptions, dehumidifier drying times, building costs and degrade. 9 refs., 7 figs., 36 tabs.

Stratigraphic architecture of hydromagmatic volcanoes that have undergone vent migration: a review of Korean case studies

Science.gov (United States)

Sohn, Y.

2011-12-01

Recent studies show that the architecture of hydromagmatic volcanoes is far more complex than formerly expected. A number of external factors, such as paleohydrology and tectonics, in addition to magmatic processes are thought to play a role in controlling the overall characteristics and architecture of these volcanoes. One of the main consequences of these controls is the migration of the active vent during eruption. Case studies of hydromagmatic volcanoes in Korea show that those volcanoes that have undergone vent migration are characterized by superposition or juxtaposition of multiple rim deposits of partial tuff rings and/or tuff cones that have contrasting lithofacies characteristics, bed attitudes, and paleoflow directions. Various causes of vent migration are inferred from these volcanoes. Large-scale collapse of fragile substrate is interpreted to have caused vent migration in the Early Pleistocene volcanoes of Jeju Island, which were built upon still unconsolidated continental shelf sediments. Late Pleistocene to Holocene volcanoes, which were built upon a stack of rigid, shield-forming lava flows, lack features due to large-scale substrate collapse and have generally simple and circular morphologies either of a tuff ring or of a tuff cone. However, ~600 m shift of the eruptive center is inferred from one of these volcanoes (Ilchulbong tuff cone). The vent migration in this volcano is interpreted to have occurred because the eruption was sourced by multiple magma batches with significant eruptive pauses in between. The Yangpori diatreme in a Miocene terrestrial half-graben basin in SE Korea is interpreted to be a subsurface equivalent of a hydromagmatic volcano that has undergone vent migration. The vent migration here is inferred to have had both vertical and lateral components and have been caused by an abrupt tectonic activity near the basin margin. In all these cases, rimbeds or diatreme fills derived from different source vents are bounded by either

The effects of borate minerals on the synthesis of nucleic acid bases, amino acids and biogenic carboxylic acids from formamide.

Science.gov (United States)

Saladino, Raffaele; Barontini, Maurizio; Cossetti, Cristina; Di Mauro, Ernesto; Crestini, Claudia

2011-08-01

The thermal condensation of formamide in the presence of mineral borates is reported. The products afforded are precursors of nucleic acids, amino acids derivatives and carboxylic acids. The efficiency and the selectivity of the reaction was studied in relation to the elemental composition of the 18 minerals analyzed. The possibility of synthesizing at the same time building blocks of both genetic and metabolic apparatuses, along with the production of amino acids, highlights the interest of the formamide/borate system in prebiotic chemistry.

Method of measuring interface area of activated carbons in condensed phase

Science.gov (United States)

Dmitriyev, D. S.; Agafonov, D. V.; Kiseleva, E. A.; Mikryukova, M. A.

2018-01-01

In this work, we investigated the correlation between the heat of wetting of super-capacitor electrode material (activated carbon) with condensed phases (electrolytes based on homologous series of phosphoric acid esters) and the capacity of the supercapacitor. The surface area of the electrode-electrolyte interface was calculated according to the obtained correlations using the conventional formula for calculating the capacitance of a capacitor.

Condensate from a two-stage gasifier

DEFF Research Database (Denmark)

Bentzen, Jens Dall; Henriksen, Ulrik Birk; Hindsgaul, Claus

2000-01-01

Condensate, produced when gas from downdraft biomass gasifier is cooled, contains organic compounds that inhibit nitrifiers. Treatment with activated carbon removes most of the organics and makes the condensate far less inhibitory. The condensate from an optimised two-stage gasifier is so clean...... that the organic compounds and the inhibition effect are very low even before treatment with activated carbon. The moderate inhibition effect relates to a high content of ammonia in the condensate. The nitrifiers become tolerant to the condensate after a few weeks of exposure. The level of organic compounds...... and the level of inhibition are so low that condensate from the optimised two-stage gasifier can be led to the public sewer....

Imprint of past environmental regimes on structure and succession of a deep-sea hydrothermal vent community.

Science.gov (United States)

Mullineaux, Lauren S; Micheli, Fiorenza; Peterson, Charles H; Lenihan, Hunter S; Markus, Nilauro

2009-08-01

Dramatic perturbations of ecological communities through rapid shifts in environmental regime do not always result in complete mortality of residents. Instead, legacy individuals may remain and influence the succession and composition of subsequent communities. We used a reciprocal transplant experiment to investigate whether a legacy effect is detectable in communities experiencing an abrupt increase or decrease in hydrothermal fluid flux at deep-sea vents. Vent habitats are characterized by strong gradients in productivity and physico-chemical stressors, both of which tend to increase with increasing vent fluid flux. In our experiments, many species survived transplantation from cool (water temperatures theory developed in the rocky intertidal that predicts the predominance of physical control at the high-stress end of an environmental gradient. Prediction of successional transitions in vents and other habitats experiencing regime shifts in which remnant species may survive must take into account the possible influence of historical effects.

Theoretical insights into the sites and mechanisms for base catalyzed esterification and aldol condensation reactions over Cu.

Science.gov (United States)

Neurock, Matthew; Tao, Zhiyuan; Chemburkar, Ashwin; Hibbitts, David D; Iglesia, Enrique

2017-04-28

Condensation and esterification are important catalytic routes in the conversion of polyols and oxygenates derived from biomass to fuels and chemical intermediates. Previous experimental studies show that alkanal, alkanol and hydrogen mixtures equilibrate over Cu/SiO 2 and form surface alkoxides and alkanals that subsequently promote condensation and esterification reactions. First-principle density functional theory (DFT) calculations were carried out herein to elucidate the elementary paths and the corresponding energetics for the interconversion of propanal + H 2 to propanol and the subsequent C-C and C-O bond formation paths involved in aldol condensation and esterification of these mixtures over model Cu surfaces. Propanal and hydrogen readily equilibrate with propanol via C-H and O-H addition steps to form surface propoxide intermediates and equilibrated propanal/propanol mixtures. Surface propoxides readily form via low energy paths involving a hydrogen addition to the electrophilic carbon center of the carbonyl of propanal or via a proton transfer from an adsorbed propanol to a vicinal propanal. The resulting propoxide withdraws electron density from the surface and behaves as a base catalyzing the activation of propanal and subsequent esterification and condensation reactions. These basic propoxides can readily abstract the acidic C α -H of propanal to produce the CH 3 CH (-) CH 2 O* enolate, thus initiating aldol condensation. The enolate can subsequently react with a second adsorbed propanal to form a C-C bond and a β-alkoxide alkanal intermediate. The β-alkoxide alkanal can subsequently undergo facile hydride transfer to form the 2-formyl-3-pentanone intermediate that decarbonylates to give the 3-pentanone product. Cu is unique in that it rapidly catalyzes the decarbonylation of the C 2n intermediates to form C 2n-1 3-pentanone as the major product with very small yields of C 2n products. This is likely due to the absence of Brønsted acid sites

Arrangement for the analysis of feed water- and condensate samples of power plants

International Nuclear Information System (INIS)

Mostofin, A.A.; Sorokina, N.S.

1979-01-01

The analysis of the feedwater- and condensate sample of condensation heat power plants and nuclear power plants results from the determination of the concentrations of salt and NH 3 . The sample is led through a multistep concentrator with evaporators. On the outlet of the evaporator are throttles for the outlet of the steam-gas-mixture. The throttle on the first evaporator is designed in a way that carbonic acid escapes from the sample, which is measured by a conductivity transmitter. A conductivity transmitter with an outlet signal that is proportional to the NH 3 content is also located on the throttle of the second evaporator. (RW) [de

Assessment of RELAP5/MOD3.3 condensation models for the tube bundle condensation in the PCCS of ESBWR

International Nuclear Information System (INIS)

Zhou, W.; Wolf, B.; Revankar, S.T.

2011-01-01

The passive containment condenser system (PCCS) in an ESBWR reactor consists of vertical tube bundle submerged in a large pool of water. The condensation model for the PCCS in a thermalhydraulics code RELAP5/MOD3.3 consists of the default Nusselt model and an alternate condensation model from UCB condensation correlation. An assessment of the PCCS condensation model in RELAP5/MOD3.3 was carried out using experiments conducted on a single tube and tube bundle PCCS tests at Purdue University. The experimental conditions were simulated with the default and the alternate condensation models in the REALP5/MOD3.3 beta version of the code. The default model and the UCB model (alternate model) give quite different results on condensation heat transfer for the PCCS. The default model predicts complete condensation well whereas the UCB model predicts the through flow condensation well. Based on this study it was found that none of the models in REALP5 can predict complete condensation as well as the through flow condensation well. (author)

Assessment of RELAP5/MOD3.3 condensation models for the tube bundle condensation in the PCCS of ESBWR

Energy Technology Data Exchange (ETDEWEB)

Zhou, W., E-mail: wenzzhou@cityu.edu.hk [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong (China); Wolf, B. [Purdue University, West Lafayette, IN 47907 (United States); Revankar, S. [Purdue University, West Lafayette, IN 47907 (United States); POSTECH, Pohang (Korea, Republic of)

2013-11-15

The passive containment condenser system (PCCS) in an ESBWR reactor consists of vertical tube bundle submerged in a large pool of water. The condensation model for the PCCS in a thermalhydraulics code RELAP5/MOD3.3 consists of the default Nusselt model and an alternate condensation model from UCB condensation correlation. An assessment of the PCCS condensation model in RELAP5/MOD3.3 was carried out using experiments conducted on a single tube and tube bundle PCCS tests at Purdue University. The experimental conditions were simulated with the default and the alternate condensation models in the REALP5/MOD3.3 beta version of the code. The default model and the UCB model (alternate model) give quite different results on condensation heat transfer for the PCCS. The default model predicts complete condensation well whereas the UCB model predicts the through flow condensation well. Based on this study it was found that none of the models in REALP5 can predict complete condensation as well as the through flow condensation well.

Shuttle Gaseous Hydrogen Venting Risk from Flow Control Valve Failure

Science.gov (United States)

Drummond, J. Philip; Baurle, Robert A.; Gafney, Richard L.; Norris, Andrew T.; Pellett, Gerald L.; Rock, Kenneth E.

2009-01-01

This paper describes a series of studies to assess the potential risk associated with the failure of one of three gaseous hydrogen flow control valves in the orbiter's main propulsion system during the launch of Shuttle Endeavour (STS-126) in November 2008. The studies focused on critical issues associated with the possibility of combustion resulting from release of gaseous hydrogen from the external tank into the atmosphere during assent. The Shuttle Program currently assumes hydrogen venting from the external tank will result in a critical failure. The current effort was conducted to increase understanding of the risk associated with venting hydrogen given the flow control valve failure scenarios being considered in the Integrated In-Flight Anomaly Investigation being conducted by NASA.

Population subdivision of hydrothermal vent polychaete Alvinella pompejana across equatorial and Easter Microplate boundaries.

Science.gov (United States)

Jang, Sook-Jin; Park, Eunji; Lee, Won-Kyung; Johnson, Shannon B; Vrijenhoek, Robert C; Won, Yong-Jin

2016-10-28

The Equator and Easter Microplate regions of the eastern Pacific Ocean exhibit geomorphological and hydrological features that create barriers to dispersal for a number of animals associated with deep-sea hydrothermal vent habitats. This study examined effects of these boundaries on geographical subdivision of the vent polychaete Alvinella pompejana. DNA sequences from one mitochondrial and eleven nuclear genes were examined in samples collected from ten vent localities that comprise the species' known range from 23°N latitude on the East Pacific Rise to 38°S latitude on the Pacific Antarctic Ridge. Multi-locus genotypes inferred from these sequences clustered the individual worms into three metapopulation segments - the northern East Pacific Rise (NEPR), southern East Pacific Rise (SEPR), and northeastern Pacific Antarctic Ridge (PAR) - separated by the Equator and Easter Microplate boundaries. Genetic diversity estimators were negatively correlated with tectonic spreading rates. Application of the isolation-with-migration (IMa2) model provided information about divergence times and demographic parameters. The PAR and NEPR metapopulation segments were estimated to have split roughly 4.20 million years ago (Mya) (2.42-33.42 Mya, 95 % highest posterior density, (HPD)), followed by splitting of the SEPR and NEPR segments about 0.79 Mya (0.07-6.67 Mya, 95 % HPD). Estimates of gene flow between the neighboring regions were mostly low (2 Nm  SEPR > PAR. Highly effective dispersal capabilities allow A. pompejana to overcome the temporal instability and intermittent distribution of active hydrothermal vents in the eastern Pacific Ocean. Consequently, the species exhibits very high levels of genetic diversity compared with many co-distributed vent annelids and mollusks. Nonetheless, its levels of genetic diversity in partially isolated populations are inversely correlated with tectonic spreading rates. As for many other vent taxa, this pioneering colonizer is

The Effect of Capillary Number on a Condensate Blockage in Gas Condensate Reservoirs

OpenAIRE

Saifon DAUNGKAEW; Alain C GRINGARTEN

2004-01-01

In the petroleum industry, gas condensate reservoirs are becoming more common as exploration targets. However, there is a lack of knowledge of the reservoir behaviour mainly due to its complexity in the near wellbore region, where two phases, i.e. reservoir gas and condensate coexist when the wellbore pressure drops below the dew point pressure. The condensation process causes a reduction of the gas productivity (1). It has been reported in the literature that there is an increasing gas mobil...

Investigating pyroclast ejection dynamics using shock-tube experiments: temperature, grain size and vent geometry effects.

Science.gov (United States)

Cigala, V.; Kueppers, U.; Dingwell, D. B.

2015-12-01

Explosive volcanic eruptions eject large quantities of gas and particles into the atmosphere. The portion directly above the vent commonly shows characteristics of underexpanded jets. Understanding the factors that influence the initial pyroclast ejection dynamics is necessary in order to better assess the resulting near- and far-field hazards. Field observations are often insufficient for the characterization of volcanic explosions due to lack of safe access to such environments. Fortunately, their dynamics can be simulated in the laboratory where experiments are performed under controlled conditions. We ejected loose natural particles from a shock-tube while controlling temperature (25˚ and 500˚C), overpressure (15MPa), starting grain size distribution (1-2 mm, 0.5-1 mm and 0.125-0.250 mm), sample-to-vent distance and vent geometry. For each explosion we quantified the velocity of individual particles, the jet spreading angle and the production of fines. Further, we varied the setup to allow for different sample-to-gas ratios and deployed four different vent geometries: 1) cylindrical, 2) funnel with a flaring of 30˚, 3) funnel with a flaring of 15˚ and 4) nozzle. The results showed maximum particle velocities up to 296 m/s, gas spreading angles varying from 21˚ to 37˚ and particle spreading angles from 3˚ to 40˚. Moreover we observed dynamically evolving ejection characteristics and variations in the production of fines during the course of individual experiments. Our experiments mechanistically mimic the process of pyroclast ejection. Thus the capability for constraining the effects of input parameters (fragmentation conditions) and conduit/vent geometry on ballistic pyroclastic plumes has been clearly established. These data obtained in the presence of well-documented conduit and vent conditions, should greatly enhance our ability to numerically model explosive ejecta in nature.

Structure-to-glass transition temperature relationships in high temperature stable condensation polyimides

Science.gov (United States)

Alston, W. B.; Gratz, R. F.

1985-01-01

The presence of a hexafluoroisopropylidene (6F) connecting group in aryl dianhydrides used to prepare aromatic condensation polyimides provides high glass transition temperature (T sub g) polyimides with excellent thermo-oxidative stability. The purpose of this study was to determine if a trifluorophenyl-ethylidene (3F) connecting group would have a similar effect on the T sub g of aromatic condensation polyimides. A new dianhydride containing the 3F connecting group was synthesized. This dianhydride and an aromatic diamine also containing the 3F connecting group were used together and in various combinations with known diamines or known dianhydrides, respectively, to prepare new 3F containing condensation polyimides. Known polyimides, including some with the 6F connecting linkage, were also prepared for comparison purposes. The new 3F containing polymers and the comparison polymers were prepared by condensation polymerization via the traditional amic-acid polymerization method in N,N-dimethylacetamide solvent. The solutions were characterized by determining their inherent viscosities and then were thermally converted into polyimide films under nitrogen atmosphere at 300 to 500 C, usually 350 C. The T sub g's of the films and resin discs were then determined by thermomechanical analysis and were correlated as a function of the final processing temperatures of the films and resin discs. The results showed that similarities existed in the T sub g's depending on the nature of the connecting linkage in the monomers used to prepare the condensation polyimides.

Reactions of 3-Formylchromone with Active Methylene and Methyl Compounds and Some Subsequent Reactions of the Resulting Condensation Products

Directory of Open Access Journals (Sweden)

M. Lácova

2005-08-01

Full Text Available This review presents a survey of the condensations of 3-formylchromone with various active methylene and methyl compounds, e.g. malonic or barbituric acid derivatives, five-membered heterocycles, etc. The utilisation of the condensation products for the synthesis of different heterocyclic systems, which is based on the ability of the γ-pyrone ring to be opened by the nucleophilic attack is also reviewed. Finally, the applications of microwave irradiation as an unconventional method of reaction activation in the synthesis of condensation products is described and the biological activity of some chromone derivatives is noted.

Ghost condensate and generalized second law

International Nuclear Information System (INIS)

Mukohyama, Shinji

2009-01-01

Dubovsky and Sibiryakov recently proposed a scenario in which particles of different species propagate with different speeds due to their direct couplings to ghost condensate. It was argued that this extended version of ghost condensate allows a gedanken experiment leading to violation of the generalized second law. However, in the original ghost condensate scenario, difference in propagation speeds is suppressed by M 2 /M Pl 2 , where M is the order parameter of spontaneous Lorentz breaking and M Pl is the Planck scale. In this case the energy transfer necessary for the gedanken experiment is so slow that the timescale of decrease of entropy, if any, is always longer than the Jeans timescale of ghost condensate. Hence the generalized second law is not violated by the gedanken experiment in the original ghost condensate scenario. This conclusion trivially extends to gauged ghost condensation by taking into account accretion of gauged ghost condensate into a black hole.

Black holes in the ghost condensate

International Nuclear Information System (INIS)

Mukohyama, Shinji

2005-01-01

We investigate how the ghost condensate reacts to black holes immersed in it. A ghost condensate defines a hypersurface-orthogonal congruence of timelike curves, each of which has the tangent vector u μ =-g μν ∂ ν φ. It is argued that the ghost condensate in this picture approximately corresponds to a congruence of geodesics. In other words, the ghost condensate accretes into a black hole just like a pressureless dust. Correspondingly, if the energy density of the ghost condensate at large distance is set to an extremely small value by cosmic expansion then the late-time accretion rate of the ghost condensate should be negligible. The accretion rate remains very small even if effects of higher derivative terms are taken into account, provided that the black hole is sufficiently large. It is also discussed how to reconcile the black-hole accretion with the possibility that the ghost condensate might behave like dark matter

Vented fuel experiment for gas-cooled fast reactor application

International Nuclear Information System (INIS)

Longest, A.W.; Gat, U.; Conlin, J.A.; Campana, R.J.

1976-01-01

A pressure-equalized and vented fuel rod is being irradiated in an instrumented capsule designated GB-10 to approximately 100MWd/kg-heavy metal. The fuel is a sol-gel-derived 88 at.% uranium (approximately 9% 235 U) and 12 at.% plutonium oxide, and the cladding is 20% cold-worked 316 stainless steel. The capsule is being irradiated in the Oak Ridge Research Reactor (ORR) and has exceeded a burnup of 70MWd/kg. The fuel has been operated at linear power rates of 39 and 44kW/m, and peak outer cladding temperature of 565 and 630 0 C respectively. A similar fuel rod in a previous capsule (GB-9) was subjected to 48kW/m (685 0 C). Helium gas sweeps through any portion of the three regions of the fuel rod, namely: fuel, blanket, and charcoal trap. The charcoal trap is operated at about 300 0 C. An on-line Ge(Li) detector is used to analyse release rates of several gamma-emitting noble gas isotopes. Analyses are performed primarily on sweep gas flowing through the entire fuel rod, and for sweeps over the top of the charcoal trap. Sweep gas samples are analyzed for stable noble gas isotopes. Results in the form of ratios of release rate over birth rate (R/B) and venting rate over birth rate (V/B) are derived. R/B rates range from 10 -4 % to 30% while V/B ranges from 10 -6 % to 30%. Flow conductance in the capsule was monitored by recording the flow rate and pressure drop across the fuel rod and inlet sweep line. The flow conductance has been falling with increasing burnup, currently restricting the flow to about 20ml (s.t.p.)/min at a pressure difference of about 1.5MPa. Venting rates of the gaseous fission products as a function of gas pressure in the range 6.9 to 1.4MPa have also been measured. Planned future experiments include the monitoring of tritium release, venting and cladding permeation rates, and its molecular form. First measurements have been made. A simulated leak experiment will determine the mixture of fission gases as a function of flow rate and the most

Human reliability analysis for venting a BWR Mark I during a severe accident

International Nuclear Information System (INIS)

Nelson, W.R.; Blackman, H.S.

1986-01-01

A Human Reliability Analysis (HRA) was performed for the operator actions necessary to achieve containment venting for the Peach Bottom Atomic Power Station. This study was funded by the United States Nuclear Regulatory Commission (USNRC) and performed by the Idaho National Engineering Laboratory (INEL). The goal of the analysis was to estimate Human Error Probabilities (HEPs) to determine the likelihood that operators would fail to complete the venting process. The analysis was performed for two generic accident sequences: anticipated transient without scram (ATWS) and station blackout. Two major methods were used to estimate the HEPs: Technique for Human Error rate Prediction (THERP) and Success Likelihood Index Methodology (SLIM). For the ATWS scenarios analyzed, the calculated HEPs ranged from 0.23 to 0.35, depending on the number of vent paths that are required to reduce the containment pressure. It should be noted that the confidence bounds around these HEPs are large, However, even when considering the large confidence range, the failure probabilities are larger than what is typical for normal operator actions. For station blackout, the HEP is 1.0, resulting from the dangerous environmental conditions that are present, assuming that plant management would not deliberately expose personnel to a potentially fatal environment. These results are based on the analysis of draft procedures for containment venting. It is probable that careful revision of the procedures could reduce the human error probabilities

Physics of condensed matter

CERN Document Server

Misra, Prasanta K

2012-01-01

Physics of Condensed Matter is designed for a two-semester graduate course on condensed matter physics for students in physics and materials science. While the book offers fundamental ideas and topic areas of condensed matter physics, it also includes many recent topics of interest on which graduate students may choose to do further research. The text can also be used as a one-semester course for advanced undergraduate majors in physics, materials science, solid state chemistry, and electrical engineering, because it offers a breadth of topics applicable to these majors. The book be

Influence of magmatic volatiles on boron isotope compositions in vent fluids from the Eastern Manus Basin, Papua New Guinea

Science.gov (United States)

Wilckens, F. K.; Kasemann, S.; Bach, W.; Reeves, E. P.; Meixner, A.; Seewald, J.

2016-12-01

In this study we present boron (B), lithium (Li) and strontium (Sr) concentrations and isotopic composition of submarine hydrothermal fluids collected in 2006 and 2011 from PACMANUS, DESMOS and SuSu Knolls vent fields located in the Eastern Manus Basin [1,2]. Hydrothermal vent fluids within the Eastern Manus Basin range from high-temperature black smoker fluids to low-temperature diffuse fluids and acid-sulfate fluids. In general, the different fluid types show variable water-rock ratios during water-rock interaction and different inputs of magmatic volatiles. End-member black smoker fluids, which have in general high temperatures (mostly higher than 280°C) and pH values higher than 2 (measured at 25°C) are characterized by low δ7Li values (3.9 to 5.9‰) and 87Sr/86Sr ratios (0.704 to 0.705) similar to the values for island arc basalts. These results suggest low water-rock ratios during hydrothermal circulation. B concentrations and isotopic compositions in these fluids range from 1.0 to 2.6μM and 13 to 20‰, respectively. These data match with other vent fluids from island arc settings in the Western Pacific and plot in a B versus δ11B diagram on a two-component mixing line between seawater and island arc basalts [3]. Sr and Li isotopic composition of white smoker and acid-sulfate fluids overlap generally with the isotopic ratios for the black smoker fluids. However, in some fluids Sr isotope ratios are up to 0.709 near seawater composition suggesting higher water-rock ratios during water-rock interaction. B concentrations and isotope ratios in the white smoker and acid-sulfate fluids range from 0.6 to 2.2μM and 9 to 16‰, respectively which are lower compared with the values of black smoker fluids. In addition, these fluids do not fit on the mixing line between seawater and island arc basalt, and define another mixing trend in a B versus δ11B diagram. To explain this contradictory trend, a third mixing endmember is required that shifts B concentrations

Analysis of the preliminary trajectory of emergency venting of the nuclear power plant of Laguna Verde using RELAP5

International Nuclear Information System (INIS)

Cecenas F, M.; Jimenez S, R.; Ovando C, R.; Tijerina S, F.; Tapia M, R. N.

2016-09-01

For a commercial nuclear plant, the availability of a vent line to the atmosphere is an improvement to achieve the prevention and mitigation of the consequences of a severe accident. The importance of this system received greater attention after the Fukushima accident in 2011. Subsequently, in 2012 and 2013, the United States Nuclear Regulatory Commission issued documents stating that the venting must be able to dislodge 1% of the rated thermal power of the core without over pressurizing the primary container. To analyze the venting of the nuclear power plant of Laguna Verde, the line and the primary container are modeled using the thermo-hydraulic code RELAP5, simulating a release of 1% of the nominal licensed power to the container in the form of saturated steam. The vent has no problem to evacuate the energy and manages to keep the container without exceeding its design limit, and the highest percentage of thermal power that can channel the vent to the outside is approximately 3%. A sensitivity analysis increasing the diameter of the line to 14 inches allows increasing in 10% the percentage of power that can be vented to the outside without problem for the containment. (Author)

Pion condensation and neutron star dynamics

International Nuclear Information System (INIS)

Kaempfer, B.

1983-01-01

The question of formation of pion condensate via a phase transition in nuclear matter, especially in the core of neutron stars is reviewed. The possible mechanisms and the theoretical restrictions of pion condensation are summarized. The effects of ultradense equation of state and density jumps on the possible condensation phase transition are investigated. The possibilities of observation of condensation process are described. (D.Gy.)

Microbial Community Structure of Deep-sea Hydrothermal Vents on the Ultraslow Spreading Southwest Indian Ridge

Directory of Open Access Journals (Sweden)

Jian Ding

2017-06-01

Full Text Available Southwest Indian Ridge (SWIR is a typical oceanic ultraslow spreading ridge with intensive hydrothermal activities. The microbial communities in hydrothermal fields including primary producers to support the entire ecosystem by utilizing geochemical energy generated from rock-seawater interactions. Here we have examined the microbial community structures on four hydrothermal vents from SWIR, representing distinct characteristics in terms of temperature, pH and metal compositions, by using Illumina sequencing of the 16S small subunit ribosomal RNA (rRNA genes, to correlate bacterial and archaeal populations with the nature of the vents influenced by ultraslow spreading features. Epsilon-, Gamma-, Alpha-, and Deltaproteobacteria and members of the phylum Bacteroidetes and Planctomycetes, as well as Thaumarchaeota, Woesearchaeota, and Euryarchaeota were dominant in all the samples. Both bacterial and archaeal community structures showed distinguished patterns compared to those in the fast-spreading East Pacific Ridge or the slow-spreading Mid-Atlantic Ridge as previously reported. Furthermore, within SWIR, the microbial communities are highly correlated with the local temperatures. For example, the sulfur-oxidizing bacteria were dominant within bacteria from low-temperature vents, but were not represented as the dominating group recovered from high temperature (over 300°C venting chimneys in SWIR. Meanwhile, Thaumarchaeota, the ammonium oxidizing archaea, only showed high relative abundance of amplicons in the vents with high-temperature in SWIR. These findings provide insights on the microbial community in ultraslow spreading hydrothermal fields, and therefore assist us in the understanding of geochemical cycling therein.

Antimutagenic activity of some naturally occurring compounds towards cigarette-smoke condensate and benzo(a)pyrene in the Salmonella/microsome assay

Energy Technology Data Exchange (ETDEWEB)

Terwel, L.; van der Hoeven, J.C.

1985-10-01

Several compounds, occurring in food, were tested for antimutagenic activity towards cigarette-smoke condensate (CSC) and benzo(a)pyrene (BaP). Antimutagenicity was determined in the Salmonella/microsome test, with tester strain TA98, in the presence of rat-liver homogenate. Dose-response curves did show reduction of CSC- and BaP-induced mutagenicity by ellagic acid, riboflavin and chlorophyllin. Chlorophyll a and chlorophyll b, although less distinct, also inhibited CSC- and BaP-induced mutagenicity. Ascorbic acid, beta-carotene, tocopherol acetate, chlorogenic acid and butyl hydroxyanisole did not have any influence on the mutagenicity of CSC and BaP. The similarity in results for cigarette-smoke condensate and for BaP indicates that a general mechanism may be involved in the inhibition of CSC- and BaP-induced mutagenicity.

An analysis of containment venting as a severe accident mitigation strategy for the BWR Mark II containment

International Nuclear Information System (INIS)

Kelly, D.L.; Galyean, W.J.

1990-01-01

An evaluation of a BWR/4 reactor with a Mark-II containment has identified the effects of containment venting on core damage frequency and containment failure mode, and has performed a limited evaluation of the effects on the off-site consequences. The analysis was founded upon an existing probabilistic risk assessment (PRA) with the addition of a proposed filtered containment venting system, based on the Swedish Filtra system installed at the Barseback nuclear power station in southern Sweden. Three different containment venting strategies were examined for their effects on plant risk. These are discussed

Chemical evolution studies: the radiolysis and thermal decomposition of malonic acid

International Nuclear Information System (INIS)

Cruz-Castaneda, J.; Negron-Mendoza, A.; Heredia, A.; Ramos-Bernal, S.; Villafane-Barajas, S.; Frias, D.; Colin-Garcia, M.

2015-01-01

In the context of chemical evolution a simulation of a hydrothermal vent was performed. The thermolysis and radiolysis of malonic acid in aqueous solution were studied. The thermolysis was done by heating the samples (95 deg C) and radiolysis using gamma radiation. Products were identified by gas chromatography and gas chromatography-mass spectrometry. The thermal treatment produced acetic acid and CO 2 . The radiolysis experiments yield carbon dioxide, acetic acid, and di- and tricarboxylic acids. A theoretical model of the chemical process occurring under irradiation was developed; this was able to reproduce formation of products and the consumption of malonic acid. (author)

Heat Source for Active Venting at the Lost City Hydrothermal Field

Science.gov (United States)

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

2014-12-01

Located at the inside corner high of the Mid-Atlantic Ridge (MAR), 30°N and the Atlantis Transform Fault (ATF), the Atlantis Massif has been uplifted over the past ~2 my. The Southern Ridge of this massif hosts the Lost City Hydrothermal Field (LCHF), an off-axis hydrothermal vent field with carbonate chimney ages surpassing 120,000 yrs. The fluids discharging at LCHF carry geochemical signals that show a direct interaction with serpentinites. However, mineralogical evidence suggests that peridotite hydration began early in the formation of oceanic core complexes and previous modeling results indicate that serpentinization is unlikely to generate the heat necessary to maintain current levels of discharge at LCHF. This work develops a model for the LCHF venting based on the evidence of tectonic strain, detachment faulting, serpentinization, and convective fluid flow. We constrain fluid flow at the LCHF by vent geochemistry, vent temperature, seismically inferred faulting, and expected geothermal gradient ≈100°C/km. Present understanding of tectonic processes at the intersection of MAR and ATF suggests that unroofing of the footwall and crustal flexing of the massif induced normal faults, which run parallel to the MAR, throughout the Southern Ridge. In the absence of the evidence of magmatism, we test the feasibility of the geothermal gradient to cause fluid circulation in the high-permeability, sub-vertical fault zone. Fluid circulation in the fault zone is complemented by the bulk porous flow driven through the Southern Ridge by the lateral temperature gradient between the cold water on the steep face along the ATF side and the hot interior of the massif. In this scenario, the high pH hydrothermal fluids pass through the serpentinized zone before discharging as both high-temperature focused flow (40°-91°C) and low-temperature (≈15°C) diffuse flow at the LCHF.

Optimal design of condenser weight

International Nuclear Information System (INIS)

Zheng Jing; Yan Changqi; Wang Jianjun

2011-01-01

The condenser is an important component in nuclear power plants, which dimension and weight will effect the economical performance and the arrangement of the nuclear power plants. In this paper, the calculation model is established according to the design experience. The corresponding codes are also developed, and the sensitivity of design parameters which influence the condenser weight is analyzed. The present design optimization of the condenser, taking the weight minimization as the objective, is carried out with the self-developed complex-genetic algorithm. The results show that the reference condenser design is far from the best scheme, and also verify the feasibility of the complex-genetic algorithm. (authors)

The physics of exciton-polariton condensates

CERN Document Server

Lagoudakis, Konstantinos

2013-01-01

In 2006 researchers created the first polariton Bose-Einstein condensate at 19K in the solid state. Being inherently open quantum systems, polariton condensates open a window into the unpredictable world of physics beyond the “fifth state of matter”: the limited lifetime of polaritons renders polariton condensates out-of-equilibrium and provides a fertile test-bed for non-equilibrium physics. This book presents an experimental investigation into exciting features arising from this non-equilibrium behavior. Through careful experimentation, the author demonstrates the ability of polaritons to synchronize and create a single energy delocalized condensate. Under certain disorder and excitation conditions the complete opposite case of coexisting spatially overlapping condensates may be observed. The author provides the first demonstration of quantized vortices in polariton condensates and the first observation of fractional vortices with full phase and amplitude characterization. Finally, this book investigate...

An Organic Puzzle Using Meldrum's Acid

Science.gov (United States)

Crouch, R. David; Holden, Michael S.

2002-04-01

Meldrum's acid or 2,2-dimethyl-1,3-dioxane-4,6-dione undergoes a Knoevenagel condensation with formaldehyde to form an active Michael acceptor for a second molecule of Meldrum's acid. The structure of the resulting product is determined by correlation of the products of possible reactions of Meldrum's acid and formaldehyde with the NMR spectrum of the product.

Adaptation to the deep-sea hydrothermal vents and cold seeps: Insights from the transcriptomes of Alvinocaris longirostris in both environments

Science.gov (United States)

Hui, Min; Cheng, Jiao; Sha, Zhongli

2018-05-01

Alvinocaris longirostris Kikuchi and Ohta, 1995 is one of the few species co-distributed in deep-sea hydrothermal vent and cold seep environments. We performed the transcriptome analysis for A. longirostris and identified differentially expressed genes (DEGs) between samples from the Iheya North hydrothermal vent (HV) and a methane seep in the South China Sea (MS). From the 57,801 annotated unigenes, multi-copies of enzyme family members for eliminating toxic xenobiotics were isolated and seven putatively duplicated gene clusters of cytochrome P450s were discovered, which may contribute to adaptation to the harsh conditions. Eight single amino acid substitutions of a Rhodopsin gene with low expression in two deep-sea alvinocaridid species were positively selected when compared with shallow water shrimps, which may be the result of adaptation to the dim-light environment in deep sea. 408 DEGs were identified with 53 and 355 up-regulated in HV and MS, respectively. Various genes associated with sulfur metabolism, detoxification and mitochondria were included, revealing different mechanisms of adaptation to the two types of extreme environments. All results are expected to serve as important basis for the further study.

Lactic Acid Production from Pretreated Hydrolysates of Corn Stover by a Newly Developed Bacillus coagulans Strain

Science.gov (United States)

Jiang, Ting; Qiao, Hui; Zheng, Zhaojuan; Chu, Qiulu; Li, Xin; Yong, Qiang; Ouyang, Jia

2016-01-01

An inhibitor-tolerance strain, Bacillus coagulans GKN316, was developed through atmospheric and room temperature plasma (ARTP) mutation and evolution experiment in condensed dilute-acid hydrolysate (CDH) of corn stover. The fermentabilities of other hydrolysates with B. coagulans GKN316 and the parental strain B. coagulans NL01 were assessed. When using condensed acid-catalyzed steam-exploded hydrolysate (CASEH), condensed acid-catalyzed liquid hot water hydrolysate (CALH) and condensed acid-catalyzed sulfite hydrolysate (CASH) as substrates, the concentration of lactic acid reached 45.39, 16.83, and 18.71 g/L by B. coagulans GKN316, respectively. But for B. coagulans NL01, only CASEH could be directly fermented to produce 15.47 g/L lactic acid. The individual inhibitory effect of furfural, 5-hydroxymethylfurfural (HMF), vanillin, syringaldehyde and p-hydroxybenzaldehyde (pHBal) on xylose utilization by B. coagulans GKN316 was also studied. The strain B. coagulans GKN316 could effectively convert these toxic inhibitors to the less toxic corresponding alcohols in situ. These results suggested that B. coagulans GKN316 was well suited to production of lactic acid from undetoxified lignocellulosic hydrolysates. PMID:26863012

Lactic Acid Production from Pretreated Hydrolysates of Corn Stover by a Newly Developed Bacillus coagulans Strain.

Science.gov (United States)

Jiang, Ting; Qiao, Hui; Zheng, Zhaojuan; Chu, Qiulu; Li, Xin; Yong, Qiang; Ouyang, Jia

2016-01-01

An inhibitor-tolerance strain, Bacillus coagulans GKN316, was developed through atmospheric and room temperature plasma (ARTP) mutation and evolution experiment in condensed dilute-acid hydrolysate (CDH) of corn stover. The fermentabilities of other hydrolysates with B. coagulans GKN316 and the parental strain B. coagulans NL01 were assessed. When using condensed acid-catalyzed steam-exploded hydrolysate (CASEH), condensed acid-catalyzed liquid hot water hydrolysate (CALH) and condensed acid-catalyzed sulfite hydrolysate (CASH) as substrates, the concentration of lactic acid reached 45.39, 16.83, and 18.71 g/L by B. coagulans GKN316, respectively. But for B. coagulans NL01, only CASEH could be directly fermented to produce 15.47 g/L lactic acid. The individual inhibitory effect of furfural, 5-hydroxymethylfurfural (HMF), vanillin, syringaldehyde and p-hydroxybenzaldehyde (pHBal) on xylose utilization by B. coagulans GKN316 was also studied. The strain B. coagulans GKN316 could effectively convert these toxic inhibitors to the less toxic corresponding alcohols in situ. These results suggested that B. coagulans GKN316 was well suited to production of lactic acid from undetoxified lignocellulosic hydrolysates.

Lactic Acid Production from Pretreated Hydrolysates of Corn Stover by a Newly Developed Bacillus coagulans Strain.

Directory of Open Access Journals (Sweden)

Ting Jiang

Full Text Available An inhibitor-tolerance strain, Bacillus coagulans GKN316, was developed through atmospheric and room temperature plasma (ARTP mutation and evolution experiment in condensed dilute-acid hydrolysate (CDH of corn stover. The fermentabilities of other hydrolysates with B. coagulans GKN316 and the parental strain B. coagulans NL01 were assessed. When using condensed acid-catalyzed steam-exploded hydrolysate (CASEH, condensed acid-catalyzed liquid hot water hydrolysate (CALH and condensed acid-catalyzed sulfite hydrolysate (CASH as substrates, the concentration of lactic acid reached 45.39, 16.83, and 18.71 g/L by B. coagulans GKN316, respectively. But for B. coagulans NL01, only CASEH could be directly fermented to produce 15.47 g/L lactic acid. The individual inhibitory effect of furfural, 5-hydroxymethylfurfural (HMF, vanillin, syringaldehyde and p-hydroxybenzaldehyde (pHBal on xylose utilization by B. coagulans GKN316 was also studied. The strain B. coagulans GKN316 could effectively convert these toxic inhibitors to the less toxic corresponding alcohols in situ. These results suggested that B. coagulans GKN316 was well suited to production of lactic acid from undetoxified lignocellulosic hydrolysates.

Vente d'artisanat

CERN Multimedia

Staff Associaiton

2014-01-01

  Éducation et Libération Vente d’artisanat du Tiers Monde Mardi 22 et mercredi 23 avril 2014 CERN, Bâtiment principal Togo, École Arc en ciel, construction des salles de classe. Appel pour le financement de ce chantier afin de libérer l’école de la charge des loyers payés pendant des années. Après nos réalisations en Amérique latine et au Bénin, nous mobilisons nos efforts pour l’école Arc en ciel de Kpémé, au Togo, sur les bords de l’Océan, à mi-chemin entre Lomé et la frontière entre le Bénin et le Togo. Il s’agit d’une école primaire privée, laïque qui a très bonne réputation en termes de résultats, notamment pour les écoliers en fin de scolar...

Population genetic structure of Rufous-Vented Prinia ( Prinia burnesii )

African Journals Online (AJOL)

The objective of the study is to ascertain genetic variation within Rufous-vented Prinia, Prinia burnesii an endemic species, by DNA fingerprinting applying random amplified polymorphic DNA (RAPD) technique. Genetic material was obtained from three distant sites along western bank of River Indus. These sites include ...

Request for approval, vented container annual release fraction; FINAL

International Nuclear Information System (INIS)

HILL, J.S.

1999-01-01

In accordance with the approval conditions for Modification to the Central Waste Complex (CWC) Radioactive Air Emissions Notice of Construction (NOC). dated August 24,1998, a new release fraction has been developed for submittal to the Washington State Department of Health (WDOH). The proposed annual release fraction of 2.50 E-14 is proposed for use in future NOCs involving the storage and handling operations associated with vented containers on the Hanford Site. The proposed annual release fraction was the largest release fraction calculated from alpha measurements of the NucFil filters from 10 vented containers consisting of nine 55-gallon drums and one burial box with dimensions of 9.3 x 5.7 x 6.4 feet. An annual release fraction of 2.0 E-09 was used in the modification to the CWC radioactive air emissions NOC. This study confirmed that the release fraction used in the CWC radioactive air emissions NOC was conservative

Electron microscopy study of microbial mat in the North Fiji basin hydrothermal vent

Science.gov (United States)

Park, H.; Kim, J. W.; Lee, J. W.

2017-12-01

Hydrothermal vent systems consisting of hydrothermal vent, hydrothermal sediment and microbial mat are widely spread around the ocean, particularly spreading axis, continental margin and back-arc basin. Scientists have perceived that the hydrothermal systems, which reflect the primeval earth environment, are one of the best places to reveal the origin of life and extensive biogeochemical process of microbe-mineral interaction. In the present study multiline of analytical methods (X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM)) were utilized to investigate the mineralogy/chemistry of microbe-mineral interaction in hydrothermal microbial mat. Microbial mat samples were recovered by Canadian scientific submersible ROPOS on South Pacific North Fiji basin KIOST hydrothermal vent expedition 1602. XRD analysis showed that red-colored microbial mat contains Fe-oxides and Fe-oxyhydroxides. Various morphologies of minerals in the red-colored microbial mat observed by SEM are mainly showed sheath shaped, resembled with Leptothrix microbial structure, stalks shaped, similar with Marioprofundus microbial structure and globule shaped microbial structures. They are also detected with DNA analysis. The cross sectional observation of microbial structures encrusted with Fe-oxide and Fe-oxyhydroxide at a nano scale by Transmission Electron Microscopy (TEM) and Focused Ion Beam (FIB) technique was developed to verify the structural/biogeochemical properties in the microbe-mineral interaction. Systematic nano-scale measurements on the biomineralization in the microbial mat leads the understandings of biogeochemical environments around the hydrothermal vent.

Liquid Transfer Cryogenic Test Facility: Initial hydrogen and nitrogen no-vent fill data

Science.gov (United States)

Moran, Matthew E.; Nyland, Ted W.; Papell, S. Stephen

1990-01-01

The Liquid Transfer Cryogenic Test Facility is a versatile testbed for ground-based cryogenic fluid storage, handling, and transfer experimentation. The test rig contains two well instrumented tanks, and a third interchangeable tank, designed to accommodate liquid nitrogen or liquid hydrogen testing. The internal tank volumes are approx. 18, 5, and 1.2 cu. ft. Tank pressures can be varied from 2 to 30 psia. Preliminary no vent fill tests with nitrogen and hydrogen were successfully completed with the test rig. Initial results indicate that no vent fills of nitrogen above 90 percent full are achievable using this test configuration, in a 1-g environment, and with inlet liquid temperatures as high as 143 R, and an average tank wall temperature of nearly 300 R. This inlet temperature corresponds to a saturation pressure of 19 psia for nitrogen. Hydrogen proved considerably more difficult to transfer between tanks without venting. The highest temperature conditions resulting in a fill level greater than 90 percent were with an inlet liquid temperature of 34 R, and an estimated tank wall temperature of slightly more than 100 R. Saturation pressure for hydrogen at this inlet temperature is 10 psia. All preliminary no vent fill tests were performed with a top mounted full cone nozzle for liquid injection. The nozzle produces a 120 degree conical droplet spray at a differential pressure of 10 psi. Pressure in the receiving tank was held to less than 30 psia for all tests.

Transient direct-contact condensation on liquid droplets

International Nuclear Information System (INIS)

Pasamehmetoglu, K.O.; Nelson, R.A.

1987-01-01

In this paper, direct-contact condensation on subcooled liquid droplets is studied in two parts. In the first part, simple design correlations for the condensation in a steady environment are developed based upon a conduction model. These correlations include the convective heat-transfer coefficient, condensation rate, total condensation, and the droplet-thermalization time. In the second part of the paper, the effect of a time-dependent saturation temperature on the condensation process is investigated. A rapid decrease in saturation temperature is typical of condensation environments in which the steam-supply rate is limited and condensation-induced depressurization becomes important. Design correlations are developed for condensation in an environment in which the saturation temperature decreases linearly with time. These correlations are graphically compared to the design correlations of the first part through a quasi-steady approach. The error associated with this approach is quantified as a function of the rate of change of the saturation temperature

Use of fundamental condensation heat transfer experiments for the development of a sub-grid liquid jet condensation model

Energy Technology Data Exchange (ETDEWEB)

Buschman, Francis X., E-mail: Francis.Buschman@unnpp.gov; Aumiller, David L.

2017-02-15

Highlights: • Direct contact condensation data on liquid jets up to 1.7 MPa in pure steam and in the presence of noncondensable gas. • Identified a pressure effect on the impact of noncondensables to suppress condensation heat transfer not captured in existing data or correlations. • Pure steam data is used to develop a new correlation for condensation heat transfer on subcooled liquid jets. • Noncondensable data used to develop a modification to the renewal time estimate used in the Young and Bajorek correlation for condensation suppression in the presence of noncondensables. • A jet injection boundary condition, using a sub-grid jet condensation model, is developed for COBRA-IE which provides a more detailed estimate of the condensation rate on the liquid jet and allows the use of jet specific closure relationships. - Abstract: Condensation on liquid jets is an important phenomenon for many different facets of nuclear power plant transients and analyses such as containment spray cooling. An experimental facility constructed at the Pennsylvania State University, the High Pressure Liquid Jet Condensation Heat Transfer facility (HPLJCHT), has been used to perform steady-state condensation heat transfer experiments in which the temperature of the liquid jet is measured at different axial locations allowing the condensation rate to be determined over the jet length. Test data have been obtained in a pure steam environment and with varying concentrations of noncondensable gas. This data extends the available jet condensation data from near atmospheric pressure up to a pressure of 1.7 MPa. An empirical correlation for the liquid side condensation heat transfer coefficient has been developed based on the data obtained in pure steam. The data obtained with noncondensable gas were used to develop a correlation for the renewal time as used in the condensation suppression model developed by Young and Bajorek. This paper describes a new sub-grid liquid jet

Use of fundamental condensation heat transfer experiments for the development of a sub-grid liquid jet condensation model

International Nuclear Information System (INIS)

Buschman, Francis X.; Aumiller, David L.

2017-01-01

Highlights: • Direct contact condensation data on liquid jets up to 1.7 MPa in pure steam and in the presence of noncondensable gas. • Identified a pressure effect on the impact of noncondensables to suppress condensation heat transfer not captured in existing data or correlations. • Pure steam data is used to develop a new correlation for condensation heat transfer on subcooled liquid jets. • Noncondensable data used to develop a modification to the renewal time estimate used in the Young and Bajorek correlation for condensation suppression in the presence of noncondensables. • A jet injection boundary condition, using a sub-grid jet condensation model, is developed for COBRA-IE which provides a more detailed estimate of the condensation rate on the liquid jet and allows the use of jet specific closure relationships. - Abstract: Condensation on liquid jets is an important phenomenon for many different facets of nuclear power plant transients and analyses such as containment spray cooling. An experimental facility constructed at the Pennsylvania State University, the High Pressure Liquid Jet Condensation Heat Transfer facility (HPLJCHT), has been used to perform steady-state condensation heat transfer experiments in which the temperature of the liquid jet is measured at different axial locations allowing the condensation rate to be determined over the jet length. Test data have been obtained in a pure steam environment and with varying concentrations of noncondensable gas. This data extends the available jet condensation data from near atmospheric pressure up to a pressure of 1.7 MPa. An empirical correlation for the liquid side condensation heat transfer coefficient has been developed based on the data obtained in pure steam. The data obtained with noncondensable gas were used to develop a correlation for the renewal time as used in the condensation suppression model developed by Young and Bajorek. This paper describes a new sub-grid liquid jet

Comparison of five methods for the estimation of methane production from vented in vitro systems.

Science.gov (United States)

Alvarez Hess, P S; Eckard, R J; Jacobs, J L; Hannah, M C; Moate, P J

2018-05-23

There are several methods for estimating methane production (MP) from feedstuffs in vented in vitro systems. One method (A; "gold standard") measures methane proportions in the incubation bottle's head space (HS) and in the vented gas collected in gas bags. Four other methods (B, C, D and E) measure methane proportion in a single gas sample from HS. Method B assumes the same methane proportion in the vented gas as in HS, method C assumes constant methane to carbon dioxide ratio, method D has been developed based on empirical data and method E assumes constant individual venting volumes. This study aimed to compare the MP predictions from these methods to that of the gold standard method under different incubation scenarios, to validate these methods based on their concordance with a gold standard method. Methods C, D and E had greater concordance (0.85, 0.88 and 0.81), lower root mean square error (RMSE) (0.80, 0.72 and 0.85) and lower mean bias (0.20, 0.35, -0.35) with the gold standard than did method B (concordance 0.67, RMSE 1.49 and mean bias 1.26). Methods D and E were simpler to perform than method C and method D was slightly more accurate than method E. Based on precision, accuracy and simplicity of implementation, it is recommended that, when method A cannot be used, methods D and E are preferred to estimate MP from vented in vitro systems. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Diversity and phylogenetic analyses of bacteria from a shallow-waterhydrothermal vent in Milos island (Greece

Directory of Open Access Journals (Sweden)

Donato eGiovannelli

2013-07-01

Full Text Available Studies of shallow-water hydrothermal vents have been lagging behind their deep-sea counterparts. Hence, the importance of these systems and their contribution to the local and regional diversity and biogeochemistry is unclear. This study analyzes the bacterial community along a transect at the shallow-water hydrothermal vent system of Milos island, Greece. The abundance and biomass of the prokaryotic community is comparable to areas not affected by hydrothermal activity and was, on average, 1.34×108 cells g-1. The abundance, biomass and diversity of the prokaryotic community increased with the distance from the center of the vent and appeared to be controlled by the temperature gradient rather than the trophic conditions. The retrieved 16S rRNA gene fragments matched sequences from a variety of geothermal environments, although the average similarity was low (94 %, revealing previously undiscovered taxa. Epsilonproteobacteria constituted the majority of the population along the transect, with an average contribution to the total diversity of 60%. The larger cluster of 16S rRNA gene sequences was related to chemolithoautotrophic Sulfurovum spp., an Epsilonproteobacterium so far detected only at deep-sea hydrothermal vents. The presence of previously unknown lineages of Epsilonproteobacteria could be related to the abundance of organic matter in these systems, which may support alternative metabolic strategies to chemolithoautotrophy. The relative contribution of Gammaproteobacteria to the Milos microbial community increased along the transect as the distance from the center of the vent increased. Further attempts to isolate key species from these ecosystems will be critical to shed light on their evolution and ecology.

Computations for a condenser. Experimental results

International Nuclear Information System (INIS)

Walden, Jean.

1975-01-01

Computations for condensers are presented with experimental results. The computations are concerned with the steam flux at the condenser input, and inside the tube bundle. Experimental results are given for the flux inside the condenser sleeve and the flow passing through the tube bundle [fr

Charge Screening in a Charged Condensate

International Nuclear Information System (INIS)

Gabadadze, Gregory; Rosen, Rachel A.

2009-01-01

We consider a highly dense system of helium-4 nuclei and electrons in which the helium-4 nuclei have condensed. We present the condensation mechanism in the framework of low energy effective field theory and discuss the screening of electric charge in the condensate.

Influence of Hydrodynamics on the Larval Supply to Hydrothermal Vents on the East Pacific Rise

Science.gov (United States)

2007-06-01

the species inhabiting the vents are endenic, sessile , benthic invertebrates , so recovery from large disturbances occurs primarily through the...Dubilier, N. (2007). Species identifi- cation of marine invertebrate early stages by whole-larvae in situ hybridisation of 18S ribosomal RNA. Marine Ecology...31] Tyler, P. A. & Young, C. M. (1999). Reproduction and dispersal at vents and cold seeps. Journal of the Marine Biological Association of the

Chemistry of a serpentinization-controlled hydrothermal system at the Lost City hydrothermal vent field

Science.gov (United States)

Ludwig, K. A.; Kelley, D. S.; Butterfield, D. A.; Nelson, B. K.; Karson, J. A.

2003-12-01

The Lost City Hydrothermal Field (LCHF), at 30° N near the Mid-Atlantic Ridge, is an off-axis, low temperature, high-pH, ultramafic-hosted vent system. Within the field, carbonate chimneys tower up to 60 m above the seafloor, making them the tallest vent structures known. The chemistry of the vent structures and fluids at the LCHF is controlled by reactions between seawater and ultramafic rocks beneath the Atlantis massif. Mixing of warm alkaline vent fluids with seawater causes precipitation of calcium carbonate and growth of the edifaces, which range from tall, graceful pinnacles to fragile flanges and colloform deposits. Geochemical and petrological analyses of the carbonate rocks reveal distinct differences between the active and extinct structures. Actively venting chimneys and flanges are extremely porous, friable formations composed predominantly of aragonite and brucite. These structures provide important niches for well-developed microbial communities that thrive on and within the chimney walls. Some of the active chimneys may also contain the mineral ikaite, an unstable, hydrated form of calcium carbonate. TIMS and ICP-MS analyses of the carbonate chimneys show that the most active chimneys have low Sr isotope values and that they are low in trace metals (e.g., Mn, Ti, Pb). Active structures emit high-pH, low-Mg fluids at 40-90° C. The fluids also have low Sr values, indicating circulation of hydrothermal solutions through the serpentinite bedrock beneath the field. In contrast to the active structures, extinct chimneys are less porous, are well lithified, and they are composed predominantly of calcite that yields Sr isotopes near seawater values. Prolonged lower temperature seawater-hydrothermal fluid interaction within the chimneys results in the conversion of aragonite to calcite and in the enrichment of some trace metals (e.g., Mn, Ti, Co, Zn). It also promotes the incorporation of foraminifera within the outer, cemented walls of the carbonate

Analyse du vent sur l'aérodrome de Brasov-Ghimbav (Roumanie

Directory of Open Access Journals (Sweden)

Marian Ilie Briceag

2011-01-01

Full Text Available Cette analyse du vent est destinée à préciser les conditions météorologiques locales qui conditionnent le fonctionnement de l'aérodrome de Brasov-Ghimbav. En aviation, la direction et l'intensité du vent sont très importantes pour le décollage et plus encore pour l'atterrissage des aéronefs. L'étude de cet élément météorologique est réalisée à partir d'une analyse climatologique portant sur 39 années, de 1971 à 2009, et d'une analyse aérologique sur 10 années, de 2000 à 2009 (les observations météorologiques ont été fournies par l'Administration Nationale de la Météorologie. Les résultats obtenus montrent la distribution prédominante du vent selon certaines directions, les directions nord-ouest et sud-ouest, pour les observations visuelles anciennes, et les directions ouest-nord-ouest et sud-sud-ouest, pour les observations automatiques au cours des six dernières années. Quelle que soit la méthode d'observation, c'est le vent de travers (directions ouest qui atteint les vitesses les plus élevées sur la piste principale de l'aérodrome de Brasov-Ghimbav, comme du reste sur la piste projetée pour le futur aéroport international de Brasov. Cela constitue un problème pour les aéronefs les plus légers, dont les valeurs limites pour le vent de travers sont faibles. Dans ce contexte, la prévision des vents violents est très importante. La distribution horaire des vents sur la période 2000­2009, montre notamment qu'au printemps et en été, les vents de nord-ouest sont largement dominants durant le jour, en particulier pour les vitesses [10-15 m/s, avec une fréquence maximale entre 10 et 15 heures. L'analyse aérologique des situations météorologiques apporte des éléments d'explication à certaines observations. Ainsi les vitesses du vent ≥ 20 m/s ont été enregistrées majoritairement en présence du cyclone Islandais, lors du passage du front atmosphérique froid, le contraste barrique étant �

Polariton condensates

International Nuclear Information System (INIS)

Snoke, David; Littlewood, Peter

2010-01-01

Most students of physics know about the special properties of Bose-Einstein condensates (BECs) as demonstrated in the two best-known examples: superfluid helium-4, first reported in 1938, and condensates of trapped atomic gases, first observed in 1995. (See the article by Wolfgang Ketterle in PHYSICS TODAY, December 1999, page 30.) Many also know that superfluid 3 He and superconducting metals contain BECs of fermion pairs. An underlying principle of all those condensed-matter systems, known as quantum fluids, is that an even number of fermions with half-integer spin can be combined to make a composite boson with integer spin. Such composite bosons, like all bosons, have the property that below some critical temperature--roughly the temperature at which the thermal de Broglie wavelength becomes comparable to the distance between the bosons--the total free energy is minimized by having a macroscopic number of bosons enter a single quantum state and form a macroscopic, coherent matter wave. Remarkably, the effect of interparticle repulsion is to lead to quantum mechanical exchange interactions that make that state robust, since the exchange interactions add coherently.

Comparison of condensation correlations in CATHARE for modelling isolation condenser experiment

International Nuclear Information System (INIS)

Sorjonen, J.; Kalli, H.

1996-01-01

CATHARE is a thermal-hydraulic computer code developed at the Centre d'Etudes Nucleaires de Grenoble (CENG) for nuclear power plant safety analysis. Behaviour of a new Cathare condensation correlation have been studied. The code has been applied to Isolation Condenser (IC) experiment conducted in PIPER-ONE facility. PIPER-ONE simulates a General Electric BWR-6 with volume and height scaling ratios 1/2200 and 1/1, respectively. The facility is installed at Dipartimento di Costruzioni Meccaniche e Nucleari of Pisa University. The facility was equipped with an once-through heat exchanger immersed in a pool of ambient temperature water, installed roughly 10 m above the core, in the aim to reproduce qualitatively the phenomenologies expected for Isolation Condenser in the Simplified BWR (SBWR). Experiment PO-IC-02 included two subsequent power levels with initial pressure of 5.1 MPa. The IC was active during the whole experiment except in the time period between the two different power levels. A previous calculation of above mentioned experiment by Cathare2 V1.3E showed some lacks in the condensation correlation of the code. A new correlation has been developed in Centre d'Etudes Nucleaires de Grenoble (CENG). The new calculation of the PO-IC-02 experiment by Cathare2 Vl.3U 1 with the new correlation gave results consistent with the experiment in the condensing zone of the IC. Also the overall pressure trend was reproduced with estimated heat losses to the environment. A comparison with previously obtained Relap5/Mod3. 1 results is also shown in the present document. (author) (18 refs.)

Technology Solutions Case Study: Design Guidance for Passive Vents in New Construction, Multifamily Buildings

Energy Technology Data Exchange (ETDEWEB)

None

2016-02-12

In an effort to improve indoor air quality in high-performance, new construction, multifamily buildings, dedicated sources of outdoor air are being implemented. Passive vents are being selected by some design teams over other strategies because of their lower first costs and operating costs. The U.S. Department of Energy’s Building America research team Consortium for Advanced Residential Buildings constructed eight steps, which outline the design and commissioning required for these passive vents to perform as intended.

Assessment and control design for steam vent noise in an oil refinery.

Science.gov (United States)

Monazzam, Mohammad Reza; Golmohammadi, Rostam; Nourollahi, Maryam; Momen Bellah Fard, Samaneh

2011-06-13

Noise is one of the most important harmful agents in work environment. Noise pollution in oil refinery industries is related to workers' health. This study aimed to determine the overall noise pollution of an oil refinery operation and its frequency analysis to determine the control plan for a vent noise in these industries. This experimental study performed in control unit of Tehran Oil Refinery in 2008. To determine the noise distributions, environmental noise measurements were carried out by lattice method according to basic information and technical process. The sound pressure level and frequency distribution was measured for each study sources subject separately was performed individually. According to the vent's specification, the measured steam noise characteristics reviewed and compared to the theoretical results of steam noise estimation. Eventually, a double expansion muffler was designed. Data analysis and graphical design were carried out using Excel software. The results of environmental noise measurements indicated that the level of sound pressure was above the national permitted level (85 dB (A)). The Mean level of sound pressure of the studied steam jet was 90.3 dB (L). The results of noise frequency analysis for the steam vents showed that the dominant frequency was 4000 Hz. To obtain 17 dB noise reductions, a double chamber aluminum muffler with 500 mm length and 200 mm diameter consisting pipe drilled was designed. The characteristics of steam vent noise were separated from other sources, a double expansion muffler was designed using a new method based on the level of steam noise, and principle sound frequency, a double expansion muffler was designed.

Solid‐Phase Synthesis of Structurally Diverse Heterocycles by an Amide–Ketone Condensation/N‐Acyliminium Pictet–Spengler Sequence

DEFF Research Database (Denmark)

Komnatnyy, Vitaly V.; Givskov, Michael Christian; Nielsen, Thomas Eiland

2012-01-01

An efficient approach for the solid‐phase synthesis of structurally diverse heterocyclic compounds is presented. Under acidic reaction conditions, peptidic levulinamides undergo intramolecular ketone–amide condensation reactions to form cyclic N‐acyliminium intermediates. In the presence...

Characterization of spacecraft humidity condensate

Science.gov (United States)

Muckle, Susan; Schultz, John R.; Sauer, Richard L.

1994-01-01

When construction of Space Station Freedom reaches the Permanent Manned Capability (PMC) stage, the Water Recovery and Management Subsystem will be fully operational such that (distilled) urine, spent hygiene water, and humidity condensate will be reclaimed to provide water of potable quality. The reclamation technologies currently baselined to process these waste waters include adsorption, ion exchange, catalytic oxidation, and disinfection. To ensure that the baseline technologies will be able to effectively remove those compounds presenting a health risk to the crew, the National Research Council has recommended that additional information be gathered on specific contaminants in waste waters representative of those to be encountered on the Space Station. With the application of new analytical methods and the analysis of waste water samples more representative of the Space Station environment, advances in the identification of the specific contaminants continue to be made. Efforts by the Water and Food Analytical Laboratory at JSC were successful in enlarging the database of contaminants in humidity condensate. These efforts have not only included the chemical characterization of condensate generated during ground-based studies, but most significantly the characterization of cabin and Spacelab condensate generated during Shuttle missions. The analytical results presented in this paper will be used to show how the composition of condensate varies amongst enclosed environments and thus the importance of collecting condensate from an environment close to that of the proposed Space Station. Although advances were made in the characterization of space condensate, complete characterization, particularly of the organics, requires further development of analytical methods.

46 CFR 56.50-35 - Condensate pumps.

Science.gov (United States)

2010-10-01

... APPURTENANCES Design Requirements Pertaining to Specific Systems § 56.50-35 Condensate pumps. Two means shall be provided for discharging the condensate from the main condenser, one of which shall be mechanically... suction from the condenser and a discharge to the feed tank, it may be accepted as an independent...

Field Testing of an Unvented Roof with Fibrous Insulation, Tiles, and Vapor Diffusion Venting

Energy Technology Data Exchange (ETDEWEB)

Ueno, K. [Building Science Corporation, Westford, MA (United States); Lstiburek, J. W. [Building Science Corporation, Westford, MA (United States)

2016-02-01

This research is a test implementation of an unvented tile roof assembly in a hot-humid climate (Orlando, FL; Zone 2A), insulated with air permeable insulation (netted and blown fiberglass). Given the localized moisture accumulation and failures seen in previous unvented roof field work, it was theorized that a 'diffusion vent' (water vapor open, but air barrier 'closed') at the highest points in the roof assembly might allow for the wintertime release of moisture, to safe levels. The 'diffusion vent' is an open slot at the ridge and hips, covered with a water-resistant but vapor open (500+ perm) air barrier membrane. As a control comparison, one portion of the roof was constructed as a typical unvented roof (self-adhered membrane at ridge). The data collected to date indicate that the diffusion vent roof shows greater moisture safety than the conventional, unvented roof design.

Temperature-Dependent Change of Packing Structure of Condensed-Phase in a Micro-Phase Separated Langmuir Monolayer Studied by Grazing-Incidence X-ray Diffraction

Energy Technology Data Exchange (ETDEWEB)

Iimura, Ken-ichi [Department of Applied Chemisty, Faculty of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya 321-8585, Utsunomiya (Japan); Kato, Teiji [Department of Applied Chemisty, Faculty of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya 321-8585, Utsunomiya (Japan); Brezesinski, Gerald [Max-Planck Instutite of Colloids and Interfaces, Research Campus Golm, D-14476 Potsdam (Germany)

2007-10-15

Packing structure of condensed-phase in a binary mixed Langmuir monolayer of behenic acid (C22) and perfluoro-2,5,8-trimethyl-3,6,9-trioxadodecanoic acid (PFPE) on a cadmium acetate aqueous solution was studied by grazing incidence X-ray diffraction (GIXD) as a function of the subphase temperature. The measurements were made during temperature scan at a fixed molecular area to explain the morphological change of the condensed-phase domains due to a thermal treatment reported previously. Analysis of GIXD data implies that the condensed-phase domains are composed of only the C22 molecules perpendicularly oriented and very closely packed in a centered rectangular unit cell with orthorhombic distortion at low temperatures. As the temperature increases the area occupied by molecule increases, and above 25 deg. C the lattice becomes disordered, which would allow morphological transformation of the condensed-phase domains. The process of packing structure change is almost reversible except for non-equilibrium phases observed for the monolayer spread at a low temperature, 5.5 deg. C.

Temperature-Dependent Change of Packing Structure of Condensed-Phase in a Micro-Phase Separated Langmuir Monolayer Studied by Grazing-Incidence X-ray Diffraction

International Nuclear Information System (INIS)

Iimura, Ken-ichi; Kato, Teiji; Brezesinski, Gerald

2007-01-01

Packing structure of condensed-phase in a binary mixed Langmuir monolayer of behenic acid (C22) and perfluoro-2,5,8-trimethyl-3,6,9-trioxadodecanoic acid (PFPE) on a cadmium acetate aqueous solution was studied by grazing incidence X-ray diffraction (GIXD) as a function of the subphase temperature. The measurements were made during temperature scan at a fixed molecular area to explain the morphological change of the condensed-phase domains due to a thermal treatment reported previously. Analysis of GIXD data implies that the condensed-phase domains are composed of only the C22 molecules perpendicularly oriented and very closely packed in a centered rectangular unit cell with orthorhombic distortion at low temperatures. As the temperature increases the area occupied by molecule increases, and above 25 deg. C the lattice becomes disordered, which would allow morphological transformation of the condensed-phase domains. The process of packing structure change is almost reversible except for non-equilibrium phases observed for the monolayer spread at a low temperature, 5.5 deg. C

A vented pump limiter for the reversed field pinch RFX

International Nuclear Information System (INIS)

Sonato, P.

1998-01-01

The reversed field pinch (RFP) plasma performance, as in the Tokamak, is strongly correlated with the edge neutral particle control. The drawbacks of the conventional magnetic divertors and throat limiters on the RFP plasma have slackened the application of an active particle control system in existing devices. An advanced solution, based on the idea of the 'vented pump limiter' experimented on Tore Supra, has been conceived for RFX. This type of pump limiter is very attractive for a RFP. In this paper, the design of a 'vented limiter' prototype for RFX is presented. Up to six modules of this limiter can be installed at the equatorial plane of RFX, allowing a particle exhaust efficiency comparable with a divertor or a throat limiter working in a Tokamak. Finally, the optimization of this concept for the next step RFP device is presented. (orig.)

Radiological Design Summary Report for TRU Vent and Purge Process

International Nuclear Information System (INIS)

Taus, L.B.

2004-01-01

This report contains top-level requirements for the various areas of radiological protection for workers. Detailed quotations of the requirements for applicable regulatory documents can be found in the accompanying Implementation Guide. For the purposes of demonstrating compliance with these requirements, per Engineering Standard 01064, shall consider / shall evaluate indicates that the designer must examine the requirement for the design and either incorporate or provide a technical justification as to why the requirement is not incorporated. The Transuranic Vent and Purge process is not a project, but is considered a process change. This process has been performed successfully by Solid Waste on lower activity TRU drums. This summary report applies a graded approach and describes how the Transuranic Vent and Purge process meets each of the applicable radiological design criteria and requirements specified in Manual WSRC-TM-95-1, Engineering Standard Number 01064

A conservation vent is not a safe substitute for a flame arrester

Energy Technology Data Exchange (ETDEWEB)

Siestrup, Francisco Hubertus Grosse [Protego Leser do Brasil Ltda., Rio de Janeiro, RJ (Brazil)

2009-07-01

For several decades state organizations and engineering societies have published strict engineering guidelines for the design and safe management of storage tanks. Storage tanks in refineries and chemical plants can contain flammable and hazardous chemicals. Accidents in these systems resulting from explosions can cause million dollar property loss and production interruption. In severe cases lawsuits may result and companies can even be driven into bankruptcy. This article focuses on tests which have been conducted by the PROTEGO Research and Development Group in Braunschweig, Germany. Latest research, in which conservation vents have been tested in accordance to the new ISO 16852 test method, have proven that conservation vents cannot be used to substitute a flame arrester if potentially explosive atmospheres are present in storage tanks. This research was conducted during the development of ISO 28300 and the test results are considered in this standard. This paper will prove that the use of conservation vents to protect tanks from atmospheric explosion is not a reliable protection method when the vapor/air mixtures in the tank have a concentration between the Upper and Lower Explosive Limits (UEL and LEL). This is very common for Ethanol storage which is globally in evidence. (author)

Organic evaporator steam valve failure

International Nuclear Information System (INIS)

Jacobs, R.A.

1992-01-01

Defense Waste Processing Facility (DWPF) Technical has requested an analysis of the capacity of the Organic Evaporator (OE) condenser (OEC) be performed to determine its capability in the case where the OE steam flow control valve fails open. Calculations of the OE boilup and the OEC heat transfer coefficient indicate the OEC will have more than enough capacity to remove the heat at maximum OE boilup. In fact, the Salt Cell Vent Condenser (SCVC) should also have sufficient capacity to handle the maximum OE boilup. Therefore, it would require simultaneous loss of OEC and/or SCVC condensing capacity for the steam valve failure to cause high benzene in the Process Vessel Vent System (PVVS)

Numerical investigation of convective condensation with the presence of non-condensable gases in a vertical tube

Energy Technology Data Exchange (ETDEWEB)

Fu, Wen [Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Li, Xiaowei, E-mail: lixiaowei@tsinghua.edu.cn [Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Wu, Xinxin [Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Corradini, Michael L. [Department of Engineering Physics, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, WI 53706 (United States)

2016-02-15

Highlights: • Gas mixture convective condensation in vertical tubes were simulated using FLUENT code. • The simulation results matched well with experimental data. • The detailed velocity field and species distribution were investigated. • The suction factors predicted by CFD models were compared with the classical correlations. • The effects of air and helium on steam condensation were compared. - Abstract: Steam condensation is degraded when non-condensable gases are present. Convective condensation of steam–air mixture and steam–helium mixture in vertical tubes were simulated using the CFD code FLUENT. The condensation process was modeled by defining source terms for the mass, momentum, species and energy conservation equations. Several cases with various steam mass fractions were simulated, the results matched well with the experimental data. Detailed velocity field and species distribution were investigated. The radial velocity was clearly represented, and the suction effect was modeled, which needs to be accounted for when using the heat and mass transfer analogy theory. The Nusselt and Sherwood numbers predicted by CFD models were compared with the classical correlations, and the suction effects were analyzed. The suction effect is proportional to steam mass fraction, while the suction factor is little affected by the Reynolds number. For forced convection flow in this work, the buoyant force can be neglected, so the larger diffusion coefficient of steam–helium mixture would improve the steam condensation compared to steam–air mixture. The condensation mass fluxes of steam–helium mixture and steam–air mixture are almost the same at relatively high steam inlet molar fraction (≥90%).

Program plan for the investigation of vent-filtered containment conceptual designs for light water reactors

International Nuclear Information System (INIS)

Benjamin, A.S.

1979-10-01

The implementation of a containment venting and filtration capability has been suggested as a means for reducing the risk from fuel melt accidents in light water reactors. The risk reduction potential of such systems depends upon the dual function of venting containment to prevent overpressurization from the generation of steam and noncondensibles and filtering the effluent to limit the release of radioactive materials. This report addresses the major issues involved in such an accident mitigation system and discusses the engineering, technical, and economic questions that will have to be studied before judgments can be made regarding feasibility and effectiveness. A program plan is presented for research leading to the formulation of design requirements for vent-filter containment systems and to a comprehensive assessment of the values versus impacts of such systems

The application of condensate water as an additional cooling media intermittently in condenser of a split air conditioning

Science.gov (United States)

Ardita, I. N.; Subagia, I. W. A.

2018-01-01

The condensate water produced by indoor a split air conditioning is usually not utilized and thrown away into the environment. The result of measurement shows that the temperature of condensate water produced by split air conditioning is quite low, that is 19-22 °C at the rate of 16-20 mL / min and it has PH balance. Under such conditions, Air Condensate produced by split air conditioning should still be recovered as an additional cooling medium on the condenser. This research will re-investigate the use of condensate water as an intermittent additional cooling of the condenser to increase the cooling capacity and performance of the air conditioning system. This research is done by experimental method whose implementation includes; designing and manufacturing of experimental equipment, mounting measuring tools, experimental data retrieval, data processing and yield analysis. The experimental results show that the use of condensate water as an intermittent additional cooling medium on split air conditioning condenser can increase the refrigeration effect about 2%, cooling capacity about 4% and 7% of COP system. Experimental results also show a decrease in power consumption in the system compressor about 3%

Effect of condenser water in-leakage on steam generator water chemistry

International Nuclear Information System (INIS)

Balakrishnan, P.V.

1978-01-01

Corrosive environments may be generated within steam genrators from condenser cooling water in-leakage. Theoretical as well as experimental evaluation of the aggressiveness of such environments is being carried out for the condenser-cooling waters used at CANDU-PHW nuclear power stations. Calculations have shown that highly concentrated chloride solutions - acidic in the case of sea-water in-leakage, and alkaline in the rest of the cases considered - would be produced within the steam generator. Experiments in a model boiler showed that sea-water in-leakage caused rapid corrosion of carbon steel components when only AVT (all volatile treatment) was used for water chemistry control. Use of a non-volatile reagent, as in the congruent phosphate treatment, avoided the rapid corrosion of carbon steel. On the basis of our studies, congruent phosphate treatment during sea water in-leakage appears desirable. (author)

Copepod colonization of organic and inorganic substrata at a deep-sea hydrothermal vent site on the Mid-Atlantic Ridge

Science.gov (United States)

Plum, Christoph; Pradillon, Florence; Fujiwara, Yoshihiro; Sarrazin, Jozée

2017-03-01

The few existing studies on deep-sea hydrothermal vent copepods indicate low connectivity with surrounding environments and reveal high endemism among vents. However, the finding of non-endemic copepod species in association with engineer species at different reduced ecosystems poses questions about the dispersal of copepods and the colonization of hydrothermal vents as well as their ecological connectivity. The objective of this study is to understand copepod colonization patterns at a hydrothermal vent site in response to environmental factors such as temperature and fluid flow as well as the presence of different types of substrata. To address this objective, an in situ experiment was deployed using both organic (woods, pig bones) and inorganic (slates) substrata along a gradient of hydrothermal activity at the Lucky Strike vent field (Eiffel Tower, Mid-Atlantic Ridge). The substrata were deployed in 2011 during the MoMARSAT cruise and were recovered after two years in 2013. Overall, copepod density showed significant differences between substrata types, but was similar among different hydrothermal activity regimes. Highest densities were observed on woods at sites with moderate or low fluid input, whereas bones were the most densely colonized substrata at the 2 sites with higher hydrothermal influence. Although differences in copepod diversity were not significant, the observed trends revealed overall increasing diversity with decreasing temperature and fluid input. Slates showed highest diversity compared to the organic substrata. Temperature and fluid input had a significant influence on copepod community composition, resulting in higher similarity among stations with relatively high and low fluid inputs, respectively. While vent-specialists such as dirivultids and the tegastid Smacigastes micheli dominated substrata at high vent activity, the experiment demonstrated increasing abundance and dominance of non-vent taxa with decreasing temperature and fluid

Coupled Photochemical and Condensation Model for the Venus Atmosphere

Science.gov (United States)

Bierson, Carver; Zhang, Xi; Mendonca, Joao; Liang, Mao-Chang

2017-10-01

Ground based and Venus Express observations have provided a wealth of information on the vertical and latitudinal distribution of many chemical species in the Venus atmosphere [1,2]. Previous 1D models have focused on the chemistry of either the lower [3] or middle atmosphere [4,5]. Photochemical models focusing on the sulfur gas chemistry have also been independent from models of the sulfuric acid haze and cloud formation [6,7]. In recent years sulfur-bearing particles have become important candidates for the observed SO2 inversion above 80 km [5]. To test this hypothesis it is import to create a self-consistent model that includes photochemistry, transport, and cloud condensation.In this work we extend the domain of the 1D chemistry model of Zhang et al. (2012) [5] to encompass the region between the surface to 110 km. This model includes a simple sulfuric acid condensation scheme with gravitational settling. It simultaneously solves for the chemistry and condensation allowing for self-consistent cloud formation. We compare the resulting chemical distributions to observations at all altitudes. We have also validated our model cloud mass against pioneer Venus observations [8]. This updated full atmosphere chemistry model is also being applied in our 2D solver (altitude and altitude). With this 2D model we can model how the latitudinal distribution of chemical species depends on the meridional circulation. This allows us to use the existing chemical observations to place constraints on Venus GCMs [9-11].References: [1] Arney et al., JGR:Planets, 2014 [2] Vandaele et al., Icarus 2017 (pt. 1 & 2) [3] Krasnopolsky, Icarus, 2007 [4] Krasnopolsky, Icarus, 2012 [5] Zhang et al., Icarus 2012 [6] Gao et al., Icarus, 2014 [7] Krasnopolsky, Icarus, 2015 [8] Knollenberg and Hunten, JGR:Space Physics, 1980 [9] Lee et al., JGR:Planets, 2007 [10] Lebonnois et al., Towards Understanding the Climate of Venus, 2013 [11] Mendoncca and Read, Planetary and Space Science, 2016

A Local Condensation Analysis Representing Two-phase Annular Flow in Condenser/radiator Capillary Tubes

Science.gov (United States)

Karimi, Amir

1991-01-01

NASA's effort for the thermal environmental control of the Space Station Freedom is directed towards the design, analysis, and development of an Active Thermal Control System (ATCS). A two phase, flow through condenser/radiator concept was baselined, as a part of the ATCS, for the radiation of space station thermal load into space. The proposed condenser rejects heat through direct condensation of ATCS working fluid (ammonia) in the small diameter radiator tubes. Analysis of the condensation process and design of condenser tubes are based on the available two phase flow models for the prediction of flow regimes, heat transfer, and pressure drops. The prediction formulas use the existing empirical relationships of friction factor at gas-liquid interface. An attempt is made to study the stability of interfacial waves in two phase annular flow. The formulation is presented of a stability problem in cylindrical coordinates. The contribution of fluid viscosity, surface tension, and transverse radius of curvature to the interfacial surface is included. A solution is obtained for Kelvin-Helmholtz instability problem which can be used to determine the critical and most dangerous wavelengths for interfacial waves.

An experimental study of high pressure steam condensation in a vertical tube of passive secondary condensation system

Energy Technology Data Exchange (ETDEWEB)

Kim, Sang Jae; No, Hee Cheon [KAIST, Taejon (Korea, Republic of)

1998-07-01

To investigate the physical parameters of PSCS (Passive Secondary Condensation System) which is a passive residual heat removal system of CP-1300, the high pressure condensation experiments are performed in a small scale experimental facility. The experimental parameters are the local heat flux and the transfer coefficient and the pressure drop in a condensation heat trasnfer. The film condensation heat transfer coefficients in a vertical tube are calculated from the measured wall temperature difference and compared with the analytical models. A new analytical condensation model is developed based on the annular film flow model. The present model gives marginally better results than those from the Shah model in comparison with the experimental data in the database. Also, experimental data are compared with the results of the RELAP5/MOD3.2 thermal hydraulic code. The RELAP5/MOD3.2 underpredicts the condensation heat transfer coefficients of the present experiment by 50 %.

Condensing boiler applications in the process industry

International Nuclear Information System (INIS)

Chen, Qun; Finney, Karen; Li, Hanning; Zhang, Xiaohui; Zhou, Jue; Sharifi, Vida; Swithenbank, Jim

2012-01-01

Major challenging issues such as climate change, energy prices and fuel security have focussed the attention of process industries on their energy efficiency and opportunities for improvement. The main objective of this research study was to investigate technologies needed to exploit the large amount of low grade heat available from a flue gas condensing system through industrial condensing boilers. The technology and application of industrial condensing boilers in various heating systems were extensively reviewed. As the condensers require site-specific engineering design, a case study was carried out to investigate the feasibility (technically and economically) of applying condensing boilers in a large scale district heating system (40 MW). The study showed that by recovering the latent heat of water vapour in the flue gas through condensing boilers, the whole heating system could achieve significantly higher efficiency levels than conventional boilers. In addition to waste heat recovery, condensing boilers can also be optimised for emission abatement, especially for particle removal. Two technical barriers for the condensing boiler application are corrosion and return water temperatures. Highly corrosion-resistant material is required for condensing boiler manufacture. The thermal design of a 'case study' single pass shell-and-tube condensing heat exchanger/condenser showed that a considerable amount of thermal resistance was on the shell-side. Based on the case study calculations, approximately 4900 m 2 of total heat transfer area was required, if stainless steel was used as a construction material. If the heat transfer area was made of carbon steel, then polypropylene could be used as the corrosion-resistant coating material outside the tubes. The addition of polypropylene coating increased the tube wall thermal resistance, hence the required heat transfer area was approximately 5800 m 2 . Net Present Value (NPV) calculations showed that the choice of a carbon

50 CFR 697.21 - Gear identification and marking, escape vent, maximum trap size, and ghost panel requirements.

Science.gov (United States)

2010-10-01

... vent, maximum trap size, and ghost panel requirements. 697.21 Section 697.21 Wildlife and Fisheries... identification and marking, escape vent, maximum trap size, and ghost panel requirements. (a) Gear identification... Administrator finds to be consistent with paragraph (c) of this section. (d) Ghost panel. (1) Lobster traps not...

Deuterium labelling studies with unsaturated acids and nitriles

International Nuclear Information System (INIS)

Desai, U.V.; Mane, R.B.

1986-01-01

α-Deuteriated α,β-unsaturated acids have been prepared by Knoevenagel condensation of aldehydes with deuteriated malonic acid. The decarboxylation of α,β-unsaturated cyano acid with pyridine/D 2 O yields α- and γ-labelled nitriles. The deuterium incorporation is studied by pmr spectroscopy. (author). 8 refs

Kinetics and mechanism of the condensation of pyridoxal hydrochloride with L-tryptophan and D-tryptophan, and the chemical transformation of their products

Science.gov (United States)

Pishchugin, F. V.; Tuleberdiev, I. T.

2017-10-01

The kinetics and mechanism of interaction between pyridoxal and L-tryptophan, D-tryptophan, and their derivatives are studied. It is found that condensation reactions proceed via three kinetically distinguishable stages: (1) the rapid intraplanar addition of the NH2 groups of the amino acids to pyridoxal with the formation of amino alcohols; (2) the rotational isomerism of amino alcohol fragments with their subsequent dehydration and the formation of a Schiff base with a specific configuration; (3) the abstraction of α-hydrogen in the product of condensation of pyridoxal with L-tryptophan, or the abstraction of CO2 in the product of condensation of pyridoxal with D-tryptophan with the formation of quinoid structures, hydrolysis of which results in the preparation of pyridoxamine and keto acid or pyridoxal and tryptamine, respectively. Schiff bases resistant to further chemical transformations are formed in the reaction with tryptophan methyl ester.

Design analysis of a Helium re-condenser

Science.gov (United States)

Muley, P. K.; Bapat, S. L.; Atrey, M. D.

2017-02-01

Modern helium cryostats deploy a cryocooler with a re-condenser at its II stage for in-situ re-condensation of boil-off vapor. The present work is a vital step in the ongoing research work of design of cryocooler based 100 litre helium cryostat with in-situ re-condensation. The cryostat incorporates a two stage Gifford McMahon cryocooler having specified refrigerating capacity of 40 W at 43 K for I stage and 1 W at 4.2 K for II stage. Although design of cryostat ensures thermal load for cryocooler below its specified refrigerating capacity at the second stage, successful in-situ re-condensation depends on proper design of re-condenser which forms the objective of this work. The present work proposes design of helium re-condenser with straight rectangular fins. Fins are analyzed for optimization of thermal performance parameters such as condensation heat transfer coefficient, surface area for heat transfer, re-condensing capacity, efficiency and effectiveness. The present work provides design of re-condenser with 19 integral fins each of 10 mm height and 1.5 mm thickness with a gap of 1.5 mm between two fins, keeping in mind the manufacturing feasibility, having efficiency of 80.96 % and effectiveness of 10.34.

Release of organics from BWR condensate demineralizer resins

International Nuclear Information System (INIS)

Ohira, Taku; Furukawa, Makoto; Sekiguchi, Masahiko; Takiguchi, Hideki; Deguchi, Tatsuya; Ino, Takao; Izumi, Takeshi; Hagiwara, Masahiro

1998-01-01

In BWRs, one of major factors to affect water chemistry in reactor is the organics leaching from condensate demineralizer. Especially, the organics from cation ion exchange resin (described CER hereafter) is intaken to reactor and changes to the sulfuric acid due to thermal decomposition and radiolysis, because CER contains sulfuric groups. In this paper, the influence of environmental parameters and structure of ion exchange resin (described IER hereafter) on the organics leaching are clarified by using 'the new method' developed for accurate measurement organics leaching from IER. Based on these results, the mechanism of the organics leaching from IER is discussed. (author)

Fluegas condensation of domestic fuels. Kotimaisten polttoaineiden savukaasulauhdutus

Energy Technology Data Exchange (ETDEWEB)

Kankkunen, A; Fagerholm, N E

1988-01-01

The suitability of domestic fuel for condensation heat recovery was studied. With the developed computer program, enthalpies of flue gas as function of temperature were computed and also the theoretical advandages aquired by condensation were compared with different fuels. The maximal advantages of condensation were 39 % with wooden chips and 31 % with peat. The domestic fuels were found to be useful for condensation heat recovery because of the high water content and the high dewpoint of flu egas. Condensation was found to have a purifying effect on flue gases. It was found experimentaly that 30 % the sulfur of the peat dissolved to the condensed liquid. The composition of condensed liquid of peat- and wooden chip flue gases was studied to find out the corrosion and enviromental effects. The risk of corrosion to metallic heat exhanger was concluded from the compositio of peat condensat. Chip condensate was found to be almost neutral. Normally the condensate liquids were fit for sewering without aftertreatment. Heat transfer coefficient from flue gases to the wall of the condenser was measured to be 150-170 W/Km{sup 2}. Heat transfer coefficients were three times higher compared to condensing heat transfer.

Capillary-Condenser-Pumped Heat-Transfer Loop

Science.gov (United States)

Silverstein, Calvin C.

1989-01-01

Heat being transferred supplies operating power. Capillary-condenser-pumped heat-transfer loop similar to heat pipe and to capillary-evaporator-pumped heat-transfer loop in that heat-transfer fluid pumped by evaporation and condensation of fluid at heat source and sink, respectively. Capillary condenser pump combined with capillary evaporator pump to form heat exchanger circulating heat-transfer fluids in both loops. Transport of heat more nearly isothermal. Thermal stress in loop reduced, and less external surface area needed in condenser section for rejection of heat to heat sink.

40 CFR 63.7187 - What performance tests and other compliance procedures must I use?

Science.gov (United States)

2010-07-01

..., gases, and liquids, other than fuels, received by the control device. (1) For a condenser, the design... condenser exhaust vent stream, and the design average temperatures of the coolant fluid at the condenser... emission reduction limitation in § 63.7184(c)(1) or (d)(1) by conducting a design evaluation as specified...

Experimental investigation of non-condensable gases effect on operation of VVER steam generator in condensation mode

International Nuclear Information System (INIS)

Efanov, A. D.; Kalyakin, S. G.; Morozov, A. V.; Remizov, O. V.; Tsyganok, A. A.; Generalov, V. N.; Berkovich, V. M.; Taranov, G. S.

2008-01-01

To provide the safety in new Russian NPP designs, protection passive systems which don't depend upon human errors are widely used. In terms of safety, the design of NPP of new generation (NPP-2006) falls into the class of advanced NPPs. In the event of an beyond design basis accident with the rupture of the reactor primary circuit and accompanied by the loss of ac sources, the use of passive safety systems are provided for necessary core cooling. Among these is passive heat removal system (PHRS). In the case of leakage in the primary circuit this system ensures the transition of steam generators (SG) to operation in the mode of condensation of the primary circuit steam coming to SG piping from the reactor. As a result, the condensate from steam generators arrives at the core providing its additional cooling. The SG condensation capacity can be adversely affected by the presence of non-condensable gases in the primary circuit of the reactor. Their main sources are nitrogen arriving at the circuit, as hydro accumulators actuate, products of radiolysis of water and air drawn in from the containment through the pipeline rupture. The accumulation of non-condensable gases in SG piping can result in degradation of its condensation capacity to the extent that condensation completely terminates. In this case, the core cooling conditions may be impaired. To experimental investigation of the condensation mode of operation of WER steam generator, a large scale HA2M-SG test rig was constructed at the SSC RF IPPE. The test rig incorporates: buffer tank, equipped by steam supply system; SG model with volumetric-power scale is 1:46; PHRS heat exchanger imitator, cooling by process water. The rig main equipment connected by pipelines and equipped by valves. The elevations of the main equipment correspond to those of reactor project. The rig maximum operating parameters: steam pressure - 1.6 MPa, temperature - 200 Celsius degrees. Experiments at the HA2M-SG test rig have been

The uptake and excretion of partially oxidized sulfur expands the repertoire of energy resources metabolized by hydrothermal vent symbioses.

Science.gov (United States)

Beinart, R A; Gartman, A; Sanders, J G; Luther, G W; Girguis, P R

2015-05-07

Symbiotic associations between animals and chemoautotrophic bacteria crowd around hydrothermal vents. In these associations, symbiotic bacteria use chemical reductants from venting fluid for the energy to support autotrophy, providing primary nutrition for the host. At vents along the Eastern Lau Spreading Center, the partially oxidized sulfur compounds (POSCs) thiosulfate and polysulfide have been detected in and around animal communities but away from venting fluid. The use of POSCs for autotrophy, as an alternative to the chemical substrates in venting fluid, could mitigate competition in these communities. To determine whether ESLC symbioses could use thiosulfate to support carbon fixation or produce POSCs during sulfide oxidation, we used high-pressure, flow-through incubations to assess the productivity of three symbiotic mollusc genera-the snails Alviniconcha spp. and Ifremeria nautilei, and the mussel Bathymodiolus brevior-when oxidizing sulfide and thiosulfate. Via the incorporation of isotopically labelled inorganic carbon, we found that the symbionts of all three genera supported autotrophy while oxidizing both sulfide and thiosulfate, though at different rates. Additionally, by concurrently measuring their effect on sulfur compounds in the aquaria with voltammetric microelectrodes, we showed that these symbioses excreted POSCs under highly sulfidic conditions, illustrating that these symbioses could represent a source for POSCs in their habitat. Furthermore, we revealed spatial disparity in the rates of carbon fixation among the animals in our incubations, which might have implications for the variability of productivity in situ. Together, these results re-shape our thinking about sulfur cycling and productivity by vent symbioses, demonstrating that thiosulfate may be an ecologically important energy source for vent symbioses and that they also likely impact the local geochemical regime through the excretion of POSCs.

Titanium application to power plant condensers

International Nuclear Information System (INIS)

Itoh, H.

1987-01-01

Recently, the growth of operating performance and construction plan of titanium-tubed condensers in thermal and unclear power plants has been very impressive. High-quality, thinner welded titanium tubes used for cooling tubes, matching design specifications of condensers, have been stably supplied through mass production. It now can be said that various technical problems for titanium-tubed condensers have been solved, but data on operating performance in large-scale commercial plants are still scarce, and site-by-site information needs be exchanged more frequently and on a larger scale. Projects to replace existing condenser cooling tubes with those of corrosion-resistant titanium have been actively furthered, with the only remaining barrier to full employment being cost effectiveness. It is hoped that condenser and tube manufacturers will conduct more joint value analyses

Multilayer Insulation Ascent Venting Model

Science.gov (United States)

Tramel, R. W.; Sutherlin, S. G.; Johnson, W. L.

2017-01-01

The thermal and venting transient experienced by tank-applied multilayer insulation (MLI) in the Earth-to-orbit environment is very dynamic and not well characterized. This new predictive code is a first principles-based engineering model which tracks the time history of the mass and temperature (internal energy) of the gas in each MLI layer. A continuum-based model is used for early portions of the trajectory while a kinetic theory-based model is used for the later portions of the trajectory, and the models are blended based on a reference mean free path. This new capability should improve understanding of the Earth-to-orbit transient and enable better insulation system designs for in-space cryogenic propellant systems.

Bose Condensate in He II

International Nuclear Information System (INIS)

Svensson, E.C.

1984-01-01

The Condensate Saga, now halfway through its fifth decade, is reviewed. The recent neutron-scattering work which has at last convincingly established that there is indeed a Bose Condensate in He II is described

Comparative composition, diversity and trophic ecology of sediment macrofauna at vents, seeps and organic falls.

Directory of Open Access Journals (Sweden)

Angelo F Bernardino

Full Text Available Sediments associated with hydrothermal venting, methane seepage and large organic falls such as whale, wood and plant detritus create deep-sea networks of soft-sediment habitats fueled, at least in part, by the oxidation of reduced chemicals. Biological studies at deep-sea vents, seeps and organic falls have looked at macrofaunal taxa, but there has yet to be a systematic comparison of the community-level attributes of sediment macrobenthos in various reducing ecosystems. Here we review key similarities and differences in the sediment-dwelling assemblages of each system with the goals of (1 generating a predictive framework for the exploration and study of newly identified reducing habitats, and (2 identifying taxa and communities that overlap across ecosystems. We show that deep-sea seep, vent and organic-fall sediments are highly heterogeneous. They sustain different geochemical and microbial processes that are reflected in a complex mosaic of habitats inhabited by a mixture of specialist (heterotrophic and symbiont-associated and background fauna. Community-level comparisons reveal that vent, seep and organic-fall macrofauna are very distinct in terms of composition at the family level, although they share many dominant taxa among these highly sulphidic habitats. Stress gradients are good predictors of macrofaunal diversity at some sites, but habitat heterogeneity and facilitation often modify community structure. The biogeochemical differences across ecosystems and within habitats result in wide differences in organic utilization (i.e., food sources and in the prevalence of chemosynthesis-derived nutrition. In the Pacific, vents, seeps and organic-falls exhibit distinct macrofaunal assemblages at broad-scales contributing to ß diversity. This has important implications for the conservation of reducing ecosystems, which face growing threats from human activities.

Condenser: a statistical aggregation tool for multi-sample quantitative proteomic data from Matrix Science Mascot Distiller™.

Science.gov (United States)

Knudsen, Anders Dahl; Bennike, Tue; Kjeldal, Henrik; Birkelund, Svend; Otzen, Daniel Erik; Stensballe, Allan

2014-05-30

We describe Condenser, a freely available, comprehensive open-source tool for merging multidimensional quantitative proteomics data from the Matrix Science Mascot Distiller Quantitation Toolbox into a common format ready for subsequent bioinformatic analysis. A number of different relative quantitation technologies, such as metabolic (15)N and amino acid stable isotope incorporation, label-free and chemical-label quantitation are supported. The program features multiple options for curative filtering of the quantified peptides, allowing the user to choose data quality thresholds appropriate for the current dataset, and ensure the quality of the calculated relative protein abundances. Condenser also features optional global normalization, peptide outlier removal, multiple testing and calculation of t-test statistics for highlighting and evaluating proteins with significantly altered relative protein abundances. Condenser provides an attractive addition to the gold-standard quantitative workflow of Mascot Distiller, allowing easy handling of larger multi-dimensional experiments. Source code, binaries, test data set and documentation are available at http://condenser.googlecode.com/. Copyright © 2014 Elsevier B.V. All rights reserved.

Modelling of film condensation in presence of non condensable gases

International Nuclear Information System (INIS)

Genevieve Geffraye; Dominique Bestion; Vladimir Kalitvianski

2005-01-01

Full text of publication follows: This paper presents recent developments in the modelling of the condensation due to heat removal from a wall with a possible presence of hydrogen, nitrogen, or air. This work is mainly concerned with nuclear reactor safety with particular reference to situations related to new reactor design, cold shutdown state and severe accident analysis. Film condensation of steam in presence of nitrogen and helium in a tube has been investigated in the COTURNE experiment in a rather large range of parameters, pressure (from 0.1 to 7 Mpa), heat flux (0.1 to 6 W/cm 2 ), mass fraction of noncondensable gas (0 to 1) and also in presence of superheated steam. The experiment represents a Steam Generator tube of a Pressurised Water Reactor and can simulate both co-current or countercurrent flow of steam and water.The models are implemented in the CATHARE code used for nuclear reactor thermal-hydraulics. The code uses two mass balance equations for liquid and gas, two momentum balance equations for liquid and gas and two energy balance equations for liquid and gas. Additional mass transport equations can be added for each non condensable gas. Heat transfers from wall to liquid film, from liquid to interface and gas to interface are modelled. The liquid film heat transfer coefficient is first investigated in pure saturated steam conditions in the pressure range from 0.1 to 7 Mpa. The CATHARE film condensation model in pure steam conditions is derived from Chen's correlation. Chen proposes a general correlation for the film condensation, covering the wavy-laminar and the turbulent film regimes and taking into account the interfacial friction effect. A large data base of laminar film regime was used including COTURNE data other available data found in the literature. The analysis of these data base suggests an influence of the liquid Reynolds number, according to the Nusselt theory, and also of the Eoetvoes number, with surface tension effects. A

HPLC, NMR and MALDI-TOF MS Analysis of Condensed Tannins from Lithocarpus glaber Leaves with Potent Free Radical Scavenging Activity