Removal of human pathogenic viruses in a down-flow hanging sponge (DHS) reactor treating municipal wastewater and health risks associated with utilization of the effluent for agricultural irrigation.

PubMed

Kobayashi, Naohiro; Oshiki, Mamoru; Ito, Toshihiro; Segawa, Takahiro; Hatamoto, Masashi; Kato, Tsuyoshi; Yamaguchi, Takashi; Kubota, Kengo; Takahashi, Masanobu; Iguchi, Akinori; Tagawa, Tadashi; Okubo, Tsutomu; Uemura, Shigeki; Harada, Hideki; Motoyama, Toshiki; Araki, Nobuo; Sano, Daisuke

2017-03-01

A down-flow hanging sponge (DHS) reactor has been developed as a cost-effective wastewater treatment system that is adaptable to local conditions in low-income countries. A pilot-scale DHS reactor previously demonstrated stable reduction efficiencies for chemical oxygen demand (COD) and ammonium nitrogen over a year at ambient temperature, but the pathogen reduction efficiency of the DHS reactor has yet to be investigated. In the present study, the reduction efficiency of a pilot-scale DHS reactor fed with municipal wastewater was investigated for 10 types of human pathogenic viruses (norovirus GI, GII and GIV, aichivirus, astrovirus, enterovirus, hepatitis A and E viruses, rotavirus, and sapovirus). DHS influent and effluent were collected weekly or biweekly for 337 days, and concentrations of viral genomes were determined by microfluidic quantitative PCR. Aichivirus, norovirus GI and GII, enterovirus, and sapovirus were frequently detected in DHS influent, and the log 10 reduction (LR) of these viruses ranged from 1.5 to 3.7. The LR values for aichivirus and norovirus GII were also calculated using a Bayesian estimation model, and the average LR (±standard deviation) values for aichivirus and norovirus GII were estimated to be 1.4 (±1.5) and 1.8 (±2.5), respectively. Quantitative microbial risk assessment was conducted to calculate a threshold reduction level for norovirus GII that would be required for the use of DHS effluent for agricultural irrigation, and it was found that LRs of 2.6 and 3.7 for norovirus GII in the DHS effluent were required in order to not exceed the tolerable burden of disease at 10 -4 and 10 -6 disability-adjusted life years loss per person per year, respectively, for 95% of the exposed population during wastewater reuse for irrigation. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Phase Behavior Effect on the Reaction Engineering of Transesterification Reactions and Reactor Design for Continuous Biodiesel Production

NASA Astrophysics Data System (ADS)

Csernica, Stephen N.

The demand for renewable forms of energy has increased tremendously over the past two decades. Of all the different forms of renewable energy, biodiesel, a liquid fuel, has emerged as one of the more viable possibilities. This is in large part due to the fact that biodiesel can readily be used in modern day diesel engines with nearly no engine modifications. It is commonly blended with conventional petroleum-derived diesel but it can also be used neat. As a result of the continued growth of the industry, there has been a correspondingly large increase in the scientific and technical research conducted on the subject. Much of the research has been conducted on the feasibility of using different types of feedstocks, which generally vary with respect to geographic locale, as well as different types of catalysts. Much of the work of the present study was involved with the investigation of the binary liquid-liquid nature of the system and its effects on the reaction kinetics. Initially, the development of an analytical method for the analysis of the compounds present in transesterification reaction mixtures using high performance liquid chromatography (HPLC) was developed. The use of UV(205 nm) as well as refractive index detection (RID) were shown capable to detect the various different types of components associated with transesterification reactions. Reversed-phase chromatography with isocratic elution was primarily used. Using a unique experimental apparatus enabling the simultaneous analysis of both liquid phases throughout the reaction, an experimental method was developed for measuring the reaction rate under both mass transfer control and reaction control. The transesterification reaction rate under each controlling mechanism was subsequently evaluated and compared. It was determined that the reaction rate is directly proportional to the concentration of triglycerides in the methanol phase. Furthermore, the reaction rate accelerates rapidly as the system transitions from two phases to a single phase, or pseudo-single phase. The transition to a single phase or pseudo-single phase is a function of the methanol content. Regardless, the maximum observed reaction rate occurs at the point of the phase transition, when the concentration of triglycerides in the methanol phase is largest. The phase transition occurs due to the accumulation of the primary product, biodiesel methyl esters. Through various experiments, it was determined that the rate of the triglyceride mass transfer into the methanol phase, as well as the solubility of triglycerides in methanol, increases with increasing methyl ester concentration. Thus, there exists some critical methyl ester concentration which favors the formation of a single or pseudo-single phase system. The effect of the by-product glycerol on the reaction kinetics was also investigated. It was determined that at low methanol to triglyceride molar ratios, glycerol acts to inhibit the reaction rate and limit the overall triglyceride conversion. This occurs because glycerol accumulates in the methanol phase, i.e. the primary reaction volume. When glycerol is at relatively high concentrations within the methanol phase, triglycerides become excluded from the reaction volume. This greatly reduces the reaction rate and limits the overall conversion. As the concentration of methanol is increased, glycerol becomes diluted and the inhibitory effects become dampened. Assuming pseudo-homogeneous phase behavior, a simple kinetic model incorporating the inhibitory effects of glycerol was proposed based on batch reactor data. The kinetic model was primarily used to theoretically compare the performance of different types of continuous flow reactors for continuous biodiesel production. It was determined that the inhibitory effects of glycerol result in the requirement of very large reactor volumes when using continuous stirred tank reactors (CSTR). The reactor volume can be greatly reduced using tubular style plug flow reactors (PFR). Despite this fact, the use of CSTRs is more common than the use of PFRs. This is mostly due to the fact that the two initial reactant phases are relatively immiscible and significant agitation is generally supplied to initiate the reaction. Based on the theoretical results, however, the use of a packed-bed tubular flow reactor was investigated experimentally. A series of two tubular flow reactors was built in the laboratory. The first reactor was of the shell and tube variety and also functioned as a preheater. The second reactor was larger and contained a packed-bed. Two different flow configurations were invested, upflow-upflow and downflow-downflow. It was determined that the downflow-downflow configuration provided significantly better triglyceride conversions that the upflow-upflow configuration.

Combining UASB and the "fourth generation" down-flow hanging sponge reactor for municipal wastewater treatment.

PubMed

Tandukar, M; Uemura, S; Ohashi, A; Harada, H

2006-01-01

A "fourth generation" down-flow hanging sponge (DHS) Reactor has been developed and proposed as an improved variant of post-treatment system for UASB treating domestic wastewater. This paper evaluates the potential of the proposed combination of UASB and DHS as a sewage treatment system, especially for developing countries. A pilot-scale UASB (1.15 m3) and DHS (0.38 m3; volume of sponge) was installed in a municipal sewage treatment site and constantly monitored for 2 years. UASB was operated at an HRT of 6 h corresponding to an organic load of 2.15 kg-COD/m3 per day. Subsequently, the organic load in DHS was 2.35 kg-COD/m3 per day, operated at an HRT of 2 h. Organic removal by the whole system was satisfactory, accomplishing 96% of unfiltered BOD removal and 91% of unfiltered COD removal. However, nitrification decreased from 56% during the startup period to 28% afterwards. Investigation on DHS sludge was made by quantifying it and evaluating oxygen uptake rates with various substrates. Average concentration of trapped biomass was 26 g-VSS/L of sponge volume, increasing the SRT of the system to 100-125 d. Removal of coliforms obtained was 3-4 log10 with the final count of 10(3) to 10(4) MPN/100 ml in DHS effluent.

Statistical Investigation of Supersonic Downflows in the Transition Region above Sunspots

NASA Astrophysics Data System (ADS)

Samanta, Tanmoy; Tian, Hui; Prasad Choudhary, Debi

2018-06-01

Downflows at supersonic speeds have been observed in the transition region (TR) above sunspots for more than three decades. These downflows are often seen in different TR spectral lines above sunspots. We have performed a statistical investigation of these downflows using a large sample that was missing previously. The Interface Region Imaging Spectrograph (IRIS) has provided a wealth of observational data of sunspots at high spatial and spectral resolutions in the past few years. We have identified 60 data sets obtained with IRIS raster scans. Using an automated code, we identified the locations of strong downflows within these sunspots. We found that around 80% of our sample shows supersonic downflows in the Si IV 1403 Å line. These downflows mostly appear in the penumbral regions, though some of them are found in the umbrae. We also found that almost half of these downflows show signatures in chromospheric lines. Furthermore, a detailed spectral analysis was performed by selecting a small spectral window containing the O IV 1400/1401 Å and Si IV 1403 Å lines. Six Gaussian functions were simultaneously fitted to these three spectral lines and their satellite lines associated with the supersonic downflows. We calculated the intensity, Doppler velocity, and line width for these lines. Using the O IV 1400/1401 Å line ratio, we find that the downflow components are around one order of magnitude less dense than the regular components. Results from our statistical analysis suggest that these downflows may originate from the corona and that they are independent of the background TR plasma.

Anaerobic digestion of corn ethanol thin stillage in batch and by high-rate down-flow fixed film reactors.

PubMed

Wilkinson, A; Kennedy, K J

2012-01-01

Thin stillage (CTS) from a dry-grind corn ethanol plant was evaluated as a carbon source for anaerobic digestion (AD) by batch and high rate semi-continuous down-flow stationary fixed film (DSFF) reactors. Biochemical methane potential (BMP) assays were carried out with CTS concentrations ranging from approximately 2,460-27,172 mg total chemical oxygen demand (TCOD) per litre, achieved by diluting CTS with clean water or a combination of clean water and treated effluent. High TCOD, SCOD and volatile solids (VS) removal efficiencies of 85 ± 2, 94 ± 0 and 82 ± 1% were achieved for CTS diluted with only clean water at an organic concentration of 21,177 mg TCOD per litre, with a methane yield of 0.30 L methane per gram TCOD(removed) at standard temperature and pressure (STP, 0 °C and 1 atmosphere). Batch studies investigating the use of treated effluent for dilution showed promising results. Continuous studies employed two mesophilic DSFF anaerobic digesters treating thin stillage, operated at hydraulic retention times (HRT) of 20, 14.3, 8.7, 6.3, 5 and 4.2 d. Successful digestion was achieved up to an organic loading rate (OLR) of approximately 7.4 g TCOD L(-1)d(-1) at a 5 d HRT with a yield of 2.05 LCH(4) L(-1)d(-1) (at STP) and TCOD and VS removal efficiencies of 89 ± 3 and 85 ± 3%, respectively.

Kinetics of resid hydrodesulfurization reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohammed, A.H.A.K.; Abbas, A.A.A.; Al'-Maiya, A.S.K.

1987-07-01

In this article the authors examine the results obtained in hydrodesulfurizing an atmospheric resis from Bai-Hassan crude on Ni-Mo/Al/sub 2/O/sub 3/ catalyst at 320-420/sup 0/C, feedstock space velocity 0.37-2.6 h/sup -1/, pressure 6.1 MPa, and hydrogen/feed ratio 300 liters/liter, in a single-pass downflow reactor with a stationary bed of catalyst. Also, they give certain thermodynamic characteristics for desulfurization, demetalization, and deasphalting of this resid. The kinetic model describing most accurately the kinetics of the different reactions will be examined.

BMP FILTERS: UPFLOW VS. DOWNFLOW

EPA Science Inventory

Stormwater filters are typically operated in a downflow mode. This research had two objectives: 1) to determine the increased life of a filter operated in an upflow mode, and 2) to determine if the operation of a downflow, mixed-media filter could be modeled using the power equat...

High-rate anaerobic treatment system for solid/lipid-rich wastewater using anaerobic baffled reactor with scum recovery.

PubMed

Fujihira, Takuya; Seo, Shogo; Yamaguchi, Takashi; Hatamoto, Masashi; Tanikawa, Daisuke

2018-04-27

A laboratory scale experiment was conducted to investigate the treatment of solid/lipid-rich wastewater with an anaerobic baffled reactor (ABR) and a down-flow hanging sponge (DHS) reactor. In this study, experimental periods were divided into three phases to explore efficient treatment of solids and lipids in wastewater. In ABR, >90% of the influent chemical oxygen demand (COD) was removed and >70% of the removed COD was converted to methane under steady-state conditions during each phase. During this period, >4.5 kg COD m -3  d -1 was achieved on an average in Phases 1 and 3. Biogas contributed to scum formation, and the scum was categorized into lipid-rich and sludge-containing types, which have energy potentials of 53.4 and 212 kcal/kg-wet weight, respectively. Therefore, by recovering solids and lipids, which formed persistent scum, ABR can be applied as a high-rate treatment for solid/lipid-rich wastewater. Copyright © 2018 Elsevier Ltd. All rights reserved.

Distinguishing Between Supra-Arcade Downflows and Plasmoids

NASA Technical Reports Server (NTRS)

Savage, Sabrina

2015-01-01

Supra-arcade downflows (SADs) and downflowing loops (SADLs), observed as sunward-traveling voids and thin flux tubes in the current sheet region above developing flare arcades, are considered indicators of magnetic reconnection fueling long­-duration solar eruptions. These flows are located in regions of very low signal-­to-noise in the corona where high cadence magnetic field measurements are not yet achievable, making observations difficult to fully interpret with respect to reconnection. Several models have been developed to explain their characteristics and behaviors, but most do not successfully recreate the observations. We will present a variety of downflow observations and provide comparisons to a number of the more prominent models.

Performance evaluation of mobile downflow booths for reducing airborne particles in the workplace.

PubMed

Lo, Li-Ming; Hocker, Braden; Steltz, Austin E; Kremer, John; Feng, H Amy

2017-11-01

Compared to other common control measures, the downflow booth is a costly engineering control used to contain airborne dust or particles. The downflow booth provides unidirectional filtered airflow from the ceiling, entraining released particles away from the workers' breathing zone, and delivers contained airflow to a lower level exhaust for removing particulates by filtering media. In this study, we designed and built a mobile downflow booth that is capable of quick assembly and easy size change to provide greater flexibility and particle control for various manufacturing processes or tasks. An experimental study was conducted to thoroughly evaluate the control performance of downflow booths used for removing airborne particles generated by the transfer of powdered lactose between two containers. Statistical analysis compared particle reduction ratios obtained from various test conditions including booth size (short, regular, or extended), supply air velocity (0.41 and 0.51 m/s or 80 and 100 feet per minute, fpm), powder transfer location (near or far from the booth exhaust), and inclusion or exclusion of curtains at the booth entrance. Our study results show that only short-depth downflow booths failed to protect the worker performing powder transfer far from the booth exhausts. Statistical analysis shows that better control performance can be obtained with supply air velocity of 0.51 m/s (100 fpm) than with 0.41 m/s (80 fpm) and that use of curtains for downflow booths did not improve their control performance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwak, Hannah; Chae, Jongchul; Song, Donguk

We report three-minute oscillations in the solar chromosphere driven by a strong downflow event in a sunspot. We used the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope and the Interface Region Imaging Spectrograph (IRIS). The strong downflow event is identified in the chromospheric and transition region lines above the sunspot umbra. After the event, oscillations occur at the same region. The amplitude of the Doppler velocity oscillations is 2 km s{sup −1} and gradually decreases with time. In addition, the period of the oscillations gradually increases from 2.7 to 3.3 minutes. In the IRIS 1330 Åmore » slit-jaw images, we identify a transient brightening near the footpoint of the downflow detected in the H α +0.5 Å image. The characteristics of the downflowing material are consistent with those of sunspot plumes. Based on our findings, we suggest that the gravitationally stratified atmosphere came to oscillate with a three-minute period in response to the impulsive downflow event as was theoretically investigated by Chae and Goode.« less

Magnetic activity in the Galactic Centre region - fast downflows along rising magnetic loops

NASA Astrophysics Data System (ADS)

Kakiuchi, Kensuke; Suzuki, Takeru K.; Fukui, Yasuo; Torii, Kazufumi; Enokiya, Rei; Machida, Mami; Matsumoto, Ryoji

2018-06-01

We studied roles of the magnetic field on the gas dynamics in the Galactic bulge by a three-dimensional global magnetohydrodynamical simulation data, particularly focusing on vertical flows that are ubiquitously excited by magnetic activity. In local regions where the magnetic field is stronger, it is frequently seen that fast downflows slide along inclined magnetic field lines that are associated with buoyantly rising magnetic loops. The vertical velocity of these downflows reaches ˜100 km s-1 near the footpoint of the loops by the gravitational acceleration towards the Galactic plane. The two footpoints of rising magnetic loops are generally located at different radial locations and the field lines are deformed by the differential rotation. The angular momentum is transported along the field lines, and the radial force balance breaks down. As a result, a fast downflow is often observed only at the one footpoint located at the inner radial position. The fast downflow compresses the gas to form a dense region near the footpoint, which will be important in star formation afterwards. Furthermore, the horizontal components of the velocity are also fast near the footpoint because the downflow is accelerated along the magnetic sliding slope. As a result, the high-velocity flow creates various characteristic features in a simulated position-velocity diagram, depending on the viewing angle.

Characteristics of DO, organic matter, and ammonium profile for practical-scale DHS reactor under various organic load and temperature conditions.

PubMed

Nomoto, Naoki; Ali, Muntjeer; Jayaswal, Komal; Iguchi, Akinori; Hatamoto, Masashi; Okubo, Tsutomu; Takahashi, Masanobu; Kubota, Kengo; Tagawa, Tadashi; Uemura, Shigeki; Yamaguchi, Takashi; Harada, Hideki

2018-04-01

Profile analysis of the down-flow hanging sponge (DHS) reactor was conducted under various temperature and organic load conditions to understand the organic removal and nitrification process for sewage treatment. Under high organic load conditions (3.21-7.89 kg-COD m -3  day -1 ), dissolved oxygen (DO) on the upper layer of the reactor was affected by organic matter concentration and water temperature, and sometimes reaches around zero. Almost half of the COD Cr was removed by the first layer, which could be attributed to the adsorption of organic matter on sponge media. After the first layer, organic removal proceeded along the first-order reaction equation from the second to the fourth layers. The ammoniacal nitrogen removal ratio decreased under high organic matter concentration (above 100 mg L -1 ) and low DO (less than 1 mg L -1 ) condition. Ammoniacal nitrogen removal proceeded via a zero-order reaction equation along the reactor height. In addition, the profile results of DO, COD Cr , and NH 3 -N were different in the horizontal direction. Thus, it is thought the concentration of these items and microbial activities were not in a uniform state even in the same sponge layer of the DHS reactor.

Mapping and DOWNFLOW simulation of recent lava flow fields at Mount Etna

NASA Astrophysics Data System (ADS)

Tarquini, Simone; Favalli, Massimiliano

2011-07-01

In recent years, progress in geographic information systems (GIS) and remote sensing techniques have allowed the mapping and studying of lava flows in unprecedented detail. A composite GIS technique is introduced to obtain high resolution boundaries of lava flow fields. This technique is mainly based on the processing of LIDAR-derived maps and digital elevation models (DEMs). The probabilistic code DOWNFLOW is then used to simulate eight large flow fields formed at Mount Etna in the last 25 years. Thanks to the collection of 6 DEMs representing Mount Etna at different times from 1986 to 2007, simulated outputs are obtained by running the DOWNFLOW code over pre-emplacement topographies. Simulation outputs are compared with the boundaries of the actual flow fields obtained here or derived from the existing literature. Although the selected fields formed in accordance with different emplacement mechanisms, flowed on different zones of the volcano over different topographies and were fed by different lava supplies of different durations, DOWNFLOW yields results close to the actual flow fields in all the cases considered. This outcome is noteworthy because DOWNFLOW has been applied by adopting a default calibration, without any specific tuning for the new cases considered here. This extensive testing proves that, if the pre-emplacement topography is available, DOWNFLOW yields a realistic simulation of a future lava flow based solely on a knowledge of the vent position. In comparison with deterministic codes, which require accurate knowledge of a large number of input parameters, DOWNFLOW turns out to be simple, fast and undemanding, proving to be ideal for systematic hazard and risk analyses.

Properties of Supersonic Evershed Downflows

NASA Astrophysics Data System (ADS)

Esteban Pozuelo, S.; Bellot Rubio, L. R.; de la Cruz Rodríguez, J.

2016-12-01

We study supersonic Evershed downflows in a sunspot penumbra by means of high spatial resolution spectropolarimetric data acquired in the Fe I 617.3 nm line with the CRISP instrument at the Swedish 1 m Solar Telescope. Physical observables, such as Dopplergrams calculated from line bisectors and Stokes V zero-crossing wavelengths, and Stokes V maps in the far red-wing, are used to find regions where supersonic Evershed downflows may exist. We retrieve the line-of-sight velocity and the magnetic field vector in these regions using two-component inversions of the observed Stokes profiles with the help of the SIR code. We follow these regions during their lifetime to study their temporal behavior. Finally, we carry out a statistical analysis of the detected supersonic downflows to characterize their physical properties. Supersonic downflows are contained in compact patches moving outward, which are located in the mid- and outer penumbra. They are observed as bright, roundish structures at the outer end of penumbral filaments that resemble penumbral grains. The patches may undergo fragmentations and mergings during their lifetime; some of them are recurrent. Supersonic downflows are associated with strong and rather vertical magnetic fields with a reversed polarity compared to that of the sunspot. Our results suggest that downflows returning back to the solar surface with supersonic velocities are abruptly stopped in dense deep layers and produce a shock. Consequently, this shock enhances the temperature and is detected as a bright grain in the continuum filtergrams, which could explain the existence of outward-moving grains in the mid- and outer penumbra.

PROPERTIES OF SUPERSONIC EVERSHED DOWNFLOWS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pozuelo, S. Esteban; Rubio, L. R. Bellot; Rodríguez, J. de la Cruz, E-mail: sara.esteban@astro.su.se

We study supersonic Evershed downflows in a sunspot penumbra by means of high spatial resolution spectropolarimetric data acquired in the Fe i 617.3 nm line with the CRISP instrument at the Swedish 1 m Solar Telescope. Physical observables, such as Dopplergrams calculated from line bisectors and Stokes  V zero-crossing wavelengths, and Stokes  V maps in the far red-wing, are used to find regions where supersonic Evershed downflows may exist. We retrieve the line-of-sight velocity and the magnetic field vector in these regions using two-component inversions of the observed Stokes profiles with the help of the SIR code. We follow these regionsmore » during their lifetime to study their temporal behavior. Finally, we carry out a statistical analysis of the detected supersonic downflows to characterize their physical properties. Supersonic downflows are contained in compact patches moving outward, which are located in the mid- and outer penumbra. They are observed as bright, roundish structures at the outer end of penumbral filaments that resemble penumbral grains. The patches may undergo fragmentations and mergings during their lifetime; some of them are recurrent. Supersonic downflows are associated with strong and rather vertical magnetic fields with a reversed polarity compared to that of the sunspot. Our results suggest that downflows returning back to the solar surface with supersonic velocities are abruptly stopped in dense deep layers and produce a shock. Consequently, this shock enhances the temperature and is detected as a bright grain in the continuum filtergrams, which could explain the existence of outward-moving grains in the mid- and outer penumbra.« less

Core cooling under accident conditions at the high-flux beam reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tichler, P.; Cheng, L.; Fauske, H.

The High-Flux Beam Reactor (HFBR) at Brookhaven National Laboratory (BNL) is cooled and moderated by heavy water and contains {sup 235}U in the form of narrow-channel, parallel-plate-type fuel elements. During normal operation, the flow direction is downward through the core. This flow direction is maintained at a reduced flow rate during routine shutdown and on loss of commercial power by means of redundant pumps and power supplies. However, in certain accident scenarios, e.g. loss-of-coolant accidents (LOCAs), all forced-flow cooling is lost. Although there was experimental evidence during the reactor design period (1958-1963) that the heat removal capacity in the fullymore » developed natural circulation cooling mode was relatively high, it was not possible to make a confident prediction of the heat removal capacity during the transition from downflow to natural circulation. Accordingly, a test program was initiated using an electrically heated section to simulate the fuel channel and a cooling loop to simulate the balance of the primary cooling system.« less

A nitrogen removal system to limit water exchange for recirculating freshwater aquarium using DHS-USB reactor.

PubMed

Adlin, Nur; Matsuura, Norihisa; Ohta, Yuki; Hirakata, Yuga; Maki, Shinya; Hatamoto, Masashi; Yamaguchi, Takashi

2018-06-01

This study proposes a biological nitrogen removal system for freshwater aquaria consisting of a down-flow hanging sponge (DHS) and an up-flow sludge blanket (USB). DHS-USB systems can perform nitrification and denitrification simultaneously, reducing ammonia (NH 3 ) and nitrate (NO 3 - ) toxicity in the water. The performance of the system was evaluated using on-site fresh water aquaria at ambient temperature (23-34°C) over 192 days. NH 3 and nitrite (NO 2 - ) were maintained at a detection limit of 0.01 mg N L -1 and NO 3 - was maintained below 10 mg N L -1 , despite limited water exchange. The 16S rRNA gene of microorganisms from the sludge retained in the bioreactors was sequenced to identify the microbial communities present. Microbial community analysis revealed that ammonia oxidizing archaea (AOA), Ca. Nitrososphaera and Nitrosopumilus, played an important role in nitrification in the DHS reactor, while denitrifying bacteria Thauera played an important role in denitrification in the USB reactor. The proposed DHS-USB system is a promising technological advancement in the development of lower maintenance aquaria.

Molecular characterization of anaerobic sulfur-oxidizing microbial communities in up-flow anaerobic sludge blanket reactor treating municipal sewage.

PubMed

Aida, Azrina A; Hatamoto, Masashi; Yamamoto, Masamitsu; Ono, Shinya; Nakamura, Akinobu; Takahashi, Masanobu; Yamaguchi, Takashi

2014-11-01

A novel wastewater treatment system consisting of an up-flow anaerobic sludge blanket (UASB) reactor and a down-flow hanging sponge (DHS) reactor with sulfur-redox reaction was developed for treatment of municipal sewage under low-temperature conditions. In the UASB reactor, a novel phenomenon of anaerobic sulfur oxidation occurred in the absence of oxygen, nitrite and nitrate as electron acceptors. The microorganisms involved in anaerobic sulfur oxidation have not been elucidated. Therefore, in this study, we studied the microbial communities existing in the UASB reactor that probably enhanced anaerobic sulfur oxidation. Sludge samples collected from the UASB reactor before and after sulfur oxidation were used for cloning and terminal restriction fragment length polymorphism (T-RFLP) analysis of the 16S rRNA genes of the bacterial and archaeal domains. The microbial community structures of bacteria and archaea indicated that the genus Smithella and uncultured bacteria within the phylum Caldiserica were the dominant bacteria groups. Methanosaeta spp. was the dominant group of the domain archaea. The T-RFLP analysis, which was consistent with the cloning results, also yielded characteristic fingerprints for bacterial communities, whereas the archaeal community structure yielded stable microbial community. From these results, it can be presumed that these major bacteria groups, genus Smithella and uncultured bacteria within the phylum Caldiserica, probably play an important role in sulfur oxidation in UASB reactors. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Lateral Downflows in Sunspot Penumbral Filaments and their Temporal Evolution

NASA Astrophysics Data System (ADS)

Esteban Pozuelo, S.; Bellot Rubio, L. R.; de la Cruz Rodríguez, J.

2015-04-01

We study the temporal evolution of downflows observed at the lateral edges of penumbral filaments in a sunspot located very close to the disk center. Our analysis is based on a sequence of nearly diffraction-limited scans of the Fe i 617.3 nm line taken with the CRisp Imaging Spectro-Polarimeter instrument at the Swedish 1 m Solar Telescope. We compute Dopplergrams from the observed intensity profiles using line bisectors and filter the resulting velocity maps for subsonic oscillations. Lateral downflows appear everywhere in the center-side penumbra as small, weak patches of redshifts next to or along the edges of blueshifted flow channels. These patches have an intermittent life and undergo mergings and fragmentations quite frequently. The lateral downflows move together with the hosting filaments and react to their shape variations, very much resembling the evolution of granular convection in the quiet Sun. There is a good relation between brightness and velocity in the center-side penumbra, with downflows being darker than upflows on average, which is again reminiscent of quiet Sun convection. These results point to the existence of overturning convection in sunspot penumbrae, with elongated cells forming filaments where the flow is upward but very inclined, and weak lateral downward flows. In general, the circular polarization profiles emerging from the lateral downflows do not show sign reversals, although sometimes we detect three-lobed profiles that are suggestive of opposite magnetic polarities in the pixel.

Flow reversal and thermal limit in a heated rectangular channel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, L.Y.; Tichler, P.R.; Yang, B.W.

The thermal limit in a vertical rectangular channel was determined in a series of experiments whereby the internal coolant underwent a change in flow direction from forced downflow to upward natural circulation. The tests were designed to simulate the flow reversal transient in the High Flux Beam Reactor. A number of parameters were varied in the flow reversal experiments to examine their effects on the thermal limit. Among the parameters varied were the rate of flow coastdown, inlet subcooling, water level in the upper plenum, bypass ratio (ratio of initial flow through the heated section to initial flow through themore » bypass orifice), and single- verses double-sided heating.« less

Data and Summaries for Catalytic Destruction of a Surrogate Organic Hazardous Air Pollutant as a Potential Co-benefit for Coal-Fired Selective Catalytic Reduction Systems

EPA Pesticide Factsheets

Table 1 summarizes and explanis the Operating Conditions of the SCR Reactor used in the Benzene-Destruction.Table 2 summarizes and explains the Experimental Design and Test Results.Table 3 summarizes and explains the Estimates for Individual Effects and Cross Effects Obtained from the Linear Regression Models for Destruction of C6H6 and Reduction of NO.Fig. 1 shows the Down-flow SCR reactor system in detail.Fig. 2 shows the graphical summary of the Effect of the inlet C6H6 concentration to the SCR reactor on the destruction of C6H6.Fig.3 shows the summary of Carbon mass balance for C6H6 destruction promoted by the V2O5-WO3/TiO2 catalyst.This dataset is associated with the following publication:Lee , C., Y. Zhao, S. Lu, and W.R. Stevens. Catalytic Destruction of a Surrogate Organic Hazardous Air Polutant as a Potential Co-benefit for Coal-fired Selective Catalyst Reduction Systems. AMERICAN CHEMICAL SOCIETY. American Chemical Society, Washington, DC, USA, 30(3): 2240-2247, (2016).

Occurrence rate of ion upflow and downflow observed by the Poker Flat Incoherent Scatter Radar (PFISR)

NASA Astrophysics Data System (ADS)

Zou, S.; Lu, J.; Varney, R. H.

2017-12-01

This study aims to investigate the occurrence rate of ion upflow and downflow events in the auroral ionosphere, using a full 3-year (2011-2013) dataset collected by the Poker Flat Incoherent Scatter Radar (PFISR) at 65.5° magnetic latitude. Ion upflow and downflow events are defined if there are three consecutive data points larger/smaller than 100/-100 m/s in the ion field-aligned velocity altitude profile. Their occurrence rates have been evaluated as a function of magnetic local time (MLT), season, geomagnetic activity, solar wind and interplanetary magnetic field (IMF). We found that the ion upflows are twice more likely to occur on the nightside than the dayside, and have slightly higher occurrence rate near Fall equinox. In contrast, the ion downflow events are more likely to occur in the afternoon sector but also during Fall equinox. In addition, the occurrence rate of ion upflows on the nightside increases when the aurora electrojet index (AE) and planetary K index (Kp) increase, while the downflows measured on the dayside clearly increase as the AE and Kp increase. In general, the occurrence rate of ion upflows increases with enhanced solar wind and IMF drivers. This correlation is particularly strong between the upflows on the nightside and the solar wind dynamic pressure and IMF Bz. The lack of correlation of upflows on the dayside with these parameters is due to the location of PFISR, which is usually equatorward of the dayside auroral zone and within the nightside auroral zone under disturbed conditions. The occurrence rate of downflow at all MLTs does not show strong dependence on the solar wind and IMF conditions. However, it occurs much more frequently on the dayside when the IMF By is strongly positive, i.e., >10 nT and the IMF Bz is strongly negative, i.e., < -10 nT. We suggest that the increased occurrence rate of downflows on the dayside is associated with dayside storm-enhanced density and the plume.

Cultivation of methanogenic community from subseafloor sediments using a continuous-flow bioreactor

PubMed Central

Imachi, Hiroyuki; Aoi, Ken; Tasumi, Eiji; Saito, Yumi; Yamanaka, Yuko; Saito, Yayoi; Yamaguchi, Takashi; Tomaru, Hitoshi; Takeuchi, Rika; Morono, Yuki; Inagaki, Fumio; Takai, Ken

2011-01-01

Microbial methanogenesis in subseafloor sediments is a key process in the carbon cycle on the Earth. However, the cultivation-dependent evidences have been poorly demonstrated. Here we report the cultivation of a methanogenic microbial consortium from subseafloor sediments using a continuous-flow-type bioreactor with polyurethane sponges as microbial habitats, called down-flow hanging sponge (DHS) reactor. We anaerobically incubated methane-rich core sediments collected from off Shimokita Peninsula, Japan, for 826 days in the reactor at 10 °C. Synthetic seawater supplemented with glucose, yeast extract, acetate and propionate as potential energy sources was provided into the reactor. After 289 days of operation, microbiological methane production became evident. Fluorescence in situ hybridization analysis revealed the presence of metabolically active microbial cells with various morphologies in the reactor. DNA- and RNA-based phylogenetic analyses targeting 16S rRNA indicated the successful growth of phylogenetically diverse microbial components during cultivation in the reactor. Most of the phylotypes in the reactor, once it made methane, were more closely related to culture sequences than to the subsurface environmental sequence. Potentially methanogenic phylotypes related to the genera Methanobacterium, Methanococcoides and Methanosarcina were predominantly detected concomitantly with methane production, while uncultured archaeal phylotypes were also detected. Using the methanogenic community enrichment as subsequent inocula, traditional batch-type cultivations led to the successful isolation of several anaerobic microbes including those methanogens. Our results substantiate that the DHS bioreactor is a useful system for the enrichment of numerous fastidious microbes from subseafloor sediments and will enable the physiological and ecological characterization of pure cultures of previously uncultivated subseafloor microbial life. PMID:21654849

Cultivation of methanogenic community from subseafloor sediments using a continuous-flow bioreactor.

PubMed

Imachi, Hiroyuki; Aoi, Ken; Tasumi, Eiji; Saito, Yumi; Yamanaka, Yuko; Saito, Yayoi; Yamaguchi, Takashi; Tomaru, Hitoshi; Takeuchi, Rika; Morono, Yuki; Inagaki, Fumio; Takai, Ken

2011-12-01

Microbial methanogenesis in subseafloor sediments is a key process in the carbon cycle on the Earth. However, the cultivation-dependent evidences have been poorly demonstrated. Here we report the cultivation of a methanogenic microbial consortium from subseafloor sediments using a continuous-flow-type bioreactor with polyurethane sponges as microbial habitats, called down-flow hanging sponge (DHS) reactor. We anaerobically incubated methane-rich core sediments collected from off Shimokita Peninsula, Japan, for 826 days in the reactor at 10 °C. Synthetic seawater supplemented with glucose, yeast extract, acetate and propionate as potential energy sources was provided into the reactor. After 289 days of operation, microbiological methane production became evident. Fluorescence in situ hybridization analysis revealed the presence of metabolically active microbial cells with various morphologies in the reactor. DNA- and RNA-based phylogenetic analyses targeting 16S rRNA indicated the successful growth of phylogenetically diverse microbial components during cultivation in the reactor. Most of the phylotypes in the reactor, once it made methane, were more closely related to culture sequences than to the subsurface environmental sequence. Potentially methanogenic phylotypes related to the genera Methanobacterium, Methanococcoides and Methanosarcina were predominantly detected concomitantly with methane production, while uncultured archaeal phylotypes were also detected. Using the methanogenic community enrichment as subsequent inocula, traditional batch-type cultivations led to the successful isolation of several anaerobic microbes including those methanogens. Our results substantiate that the DHS bioreactor is a useful system for the enrichment of numerous fastidious microbes from subseafloor sediments and will enable the physiological and ecological characterization of pure cultures of previously uncultivated subseafloor microbial life.

A steady-state supersonic downflow in the transition region above a sunspot umbra

NASA Astrophysics Data System (ADS)

Straus, Thomas; Fleck, Bernhard; Andretta, Vincenzo

2015-10-01

We investigate a small-scale (~1.5 Mm along the slit), supersonic downflow of about 90 km s-1 in the transition region above the lightbridged sunspot umbra in AR 11836. The observations were obtained with the Interface Region Spectrograph (IRIS) on 2013 September 2 from 16:40 to 17:59 UT. The downflow shows up as redshifted "satellite" lines of the Si iv and O iv transition region lines and is remarkably steady over the observing period of nearly 80 min. The downflow is not visible in the chromospheric lines, which only show an intensity enhancement at the location of the downflow. The density inferred from the line ratio of the redshifted satellites of the O iv lines (Ne = 1010.6 ± 0.25 cm-3) is only a factor 2 smaller than the one inferred from the main components (Ne = 1010.95 ± 0.20 cm-3). Consequently, this implies a substantial mass flux (~5 × 10-7 g cm-2 s-1), which would evacuate the overlying corona on timescales close to 10 s. We interpret these findings as evidence of a stationary termination shock of a supersonic siphon flow in a cool loop that is rooted in the central umbra of the spot. The movie is available in electronic form at http://www.aanda.org

Intermittent Reconnection Downflow Enhancements In A Simulated Flux Rope Eruption

NASA Astrophysics Data System (ADS)

Kliem, Bernhard; Linton, M. G.

2009-05-01

Supra-arcade downflows in X-ray and EUV flare emissions and post-eruption inflows in coronagraph data have been interpreted to be signatures of the downward reconnection outflow from a vertical (flare) current sheet. These downflows show an intermittent occurrence pattern, indicating that the reconnection is bursty in time or patchy in space, or both. We present MHD simulations of such reconnection in the realistic configuration of a vertical current sheet formed beneath and driven by an erupting flux rope. The reconnection is found to develop bursty outflows, both upward and downward, with the upward outflows generally showing the stronger variablity. While the reconnection starts early in the rise of the flux rope and its peak upward outflow velocity is closely correlated with the rope's rise velocity, the burstiness develops in a clear fashion only as the rope's height has increased from the initial position by about an order of magnitude, so that the current sheet has reached a sufficient vertical extent. The reconnection downflow shows a series of enhancements, each of them starting at a successively greater height from a newly developed magnetic X line. The plasma temporarily accelerated downward in such an enhancement soon turns into a gradual deceleration and then eventually comes to rest on top of previously accelerated plasma. These findings are consistent with the observations of intermittent downflows.

HAZARDOUS WASTE INCINERATION: THE IN-SITU CAPTURE OF LEAD BY SORBENTS IN A LABORATORY DOWNFLOW COMBUSTOR

EPA Science Inventory

The paper discusses experiments on a 17-kW downflow combustor to determine how sorbent injection into the postflame influenced the particle size distribution of a lead (Pb) aerosol formed from a surrogate Pb-containing waste. n the absence of chlorine (CI), the Pb aerosol size di...

A Hot Downflowing Model Atmosphere for Umbral Flashes and the Physical Properties of Their Dark Fibrils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henriques, V. M. J.; Mathioudakis, M.; Socas-Navarro, H.

We perform non-LTE inversions in a large set of umbral flashes, including the dark fibrils visible within them, and in the quiescent umbra by using the inversion code NICOLE on a set of full Stokes high-resolution Ca ii λ 8542 observations of a sunspot at disk center. We find that the dark structures have Stokes profiles that are distinct from those of the quiescent and flashed regions. They are best reproduced by atmospheres that are more similar to the flashed atmosphere in terms of velocities, even if with reduced amplitudes. We also find two sets of solutions that finely fitmore » the flashed profiles: a set that is upflowing, featuring a transition region that is deeper than in the quiescent case and preceded by a slight dip in temperature, and a second solution with a hotter atmosphere in the chromosphere but featuring downflows close to the speed of sound at such heights. Such downflows may be related, or even dependent, on the presence of coronal loops, rooted in the umbra of sunspots, as is the case in the region analyzed. Similar loops have been recently observed to have supersonic downflows in the transition region and are consistent with the earlier “sunspot plumes,” which were invariably found to display strong downflows in sunspots. Finally, we find, on average, a magnetic field reduction in the flashed areas, suggesting that the shock pressure is moving field lines in the upper layers.« less

Validation of cross-contamination control in biological safety cabinet for biotech/pharmaceutical manufacturing process.

PubMed

Hu, Shih-Cheng; Shiue, Angus; Tu, Jin-Xin; Liu, Han-Yang; Chiu, Rong-Ben

2015-12-01

For class II, type A2 biological safety cabinets (BSC), NSF/ANSI Standard 49 should be conformed in cabinet airflow velocity derivation, particle contamination, and aerodynamic flow properties. However, there exists a potential problem. It has been built that the cabinet air flow stabilize is influenced by the quantity of downflow of air and the height above the cabinet exhaust opening. Three air downflow quantities were compared as an operating apparatus was placed from 20 to 40 cm above the bench of the cabinet. The results show that the BSC air downflow velocity is a function of increased sampling height, displaying that containment is improvingly permitted over product protection as the sampling height decreases. This study investigated the concentration gradient of particles at various heights and downflow air quantity from the bench of the BSC. Experiment results indicate that performance near the bench was better than in the rest of the BSC. In terms of height, the best cleanliness was measured at a height of 10 cm over the bench; it reduced actually with add in height. The empirical curves accommodate, founded on the concentration gradient of particle created was elaborated for evaluating the particle concentration at different heights and downflow air quantity from the source of the bench of the BSC. The particle image velocimetry system applied for BSC airflow research to fix amount of airflow patterns and air distribution measurement and results of measurements show how obstructions can greatly influence the airflow and contaminant transportation in a BSC.

The Small-scale Structure of Photospheric Convection Retrieved by a Deconvolution Technique Applied to Hinode/SP Data

NASA Astrophysics Data System (ADS)

Oba, T.; Riethmüller, T. L.; Solanki, S. K.; Iida, Y.; Quintero Noda, C.; Shimizu, T.

2017-11-01

Solar granules are bright patterns surrounded by dark channels, called intergranular lanes, in the solar photosphere and are a manifestation of overshooting convection. Observational studies generally find stronger upflows in granules and weaker downflows in intergranular lanes. This trend is, however, inconsistent with the results of numerical simulations in which downflows are stronger than upflows through the joint action of gravitational acceleration/deceleration and pressure gradients. One cause of this discrepancy is the image degradation caused by optical distortion and light diffraction and scattering that takes place in an imaging instrument. We apply a deconvolution technique to Hinode/SP data in an attempt to recover the original solar scene. Our results show a significant enhancement in both the convective upflows and downflows but particularly for the latter. After deconvolution, the up- and downflows reach maximum amplitudes of -3.0 km s-1 and +3.0 km s-1 at an average geometrical height of roughly 50 km, respectively. We found that the velocity distributions after deconvolution match those derived from numerical simulations. After deconvolution, the net LOS velocity averaged over the whole field of view lies close to zero as expected in a rough sense from mass balance.

High-resolution Observations of Downflows at One End of a Pre-eruption Filament

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Qin; Deng, Na; Jing, Ju

Studying the dynamics of filaments at the pre-eruption phase can shed light on the precursor of eruptive events. Such high-resolution studies (of the order of 0.″1) are highly desirable yet very rare. In this work, we present a detailed observation of a pre-eruption evolution of a filament obtained by the 1.6 m New Solar Telescope (NST) at the Big Bear Solar Observatory (BBSO). One end of the filament is anchored at the sunspot in the NOAA active region (AR) 11515, which is well observed by NST H α off-bands from four hours before to one hour after the filament eruption.more » A M1.6 flare is associated with the eruption. We observed persistent downflowing materials along the H α multi-threaded component of the loop toward the AR end during the pre-eruption phase. We traced the trajectories of plasma blobs along the H α threads and obtained a plane-of-sky velocity of 45 km s{sup −1} on average. Furthermore, we estimated the real velocities of the downflows and the altitude of the filament by matching the observed H α threads with magnetic field lines extrapolated from a nonlinear force-free field model. Observations of chromospheric brightenings at the footpoints of the falling plasma blobs are also presented. The lower limit of the kinetic energy per second of the downflows through the brightenings is found to be ∼10{sup 21} erg. Larger FOV observations from BBSO full-disk H α images show that the AR end of the filament started ascending four hours before the flare. We attribute the observed downflows at the AR end of the filament to the draining effect of the filament rising prior to its eruption. During the slow-rise phase, the downflows continuously drained away ∼10{sup 15}g mass from the filament over a few hours, which is believed to be essential for the instability, and could be an important precursor of eruptive events.« less

A novel observational test of momentum balance in a solar flare

NASA Technical Reports Server (NTRS)

Canfield, Richard C.; Metcalf, Thomas R.; Strong, Keith T.; Zarro, Dominic M.

1987-01-01

A unique combination of SMM X-ray spectra and Sacramento Peak Observatory H-alpha imaging spectra has been used, for the first time, to measure and compare momentum values of upflowing and downflowing plasmas during the impulsive phase of a solar flare. The well-known blue asymmetry of X-ray spectral lines, indicative of upflow, was observed in the coronal Ca XIX line. The red asymmetry of H-alpha line profiles, indicative of downflow, was simultaneously observed in bright H-alpha kernels. It is found that, to within observational uncertainty, the momentum transported by the upflowing X-ray plasma was the same as that of the downflowing H-alpha material. Of the several physical mechanisms advanced to explain the observed blue asymmetry of X-ray lines, only explosive chromospheric evaporation predicts oppositely directed momenta of equal magnitude.

Suitability assessment of grey water quality treated with an upflow-downflow siliceous sand/marble waste filtration system for agricultural and industrial purposes.

PubMed

Chaabane, Safa; Riahi, Khalifa; Hamrouni, Hédi; Thayer, Béchir Ben

2017-04-01

The present study examines the suitability assessment of an upflow-downflow siliceous sand/marble waste filtration system for treatment and reuse of grey water collected from bathrooms of the student residential complex at the Higher Institute of Engineering Medjez El Bab (Tunisia). Once the optimization of grey water pre-treatment system has been determined, the filtration system was operated at different hydraulic loading rate and media filter proportions in order to assess the suitability of treated grey water for irrigational purpose according to salinity hazard, sodium hazard, magnesium hazard, permeability index, water infiltration rate, and widely used graphical methods. Suitability of the treated grey water for industrial purpose was evaluated in terms of foaming, corrosion, and scaling. Under optimal operational conditions, results reveals that treated grey water samples with an upflow-downflow siliceous sand/marble waste filtration system may be considered as a good and an excellent water quality suitable for irrigation purpose. However, treated grey water was found not appropriate for industrial purpose due to high concentrations of calcium and sodium that can generate foaming and scaling harm to boilers. These results suggest that treated grey water with an upflow-downflow siliceous sand/marble waste filtration system would support production when used as irrigation water.

The Small-scale Structure of Photospheric Convection Retrieved by a Deconvolution Technique Applied to Hinode /SP Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oba, T.; Riethmüller, T. L.; Solanki, S. K.

Solar granules are bright patterns surrounded by dark channels, called intergranular lanes, in the solar photosphere and are a manifestation of overshooting convection. Observational studies generally find stronger upflows in granules and weaker downflows in intergranular lanes. This trend is, however, inconsistent with the results of numerical simulations in which downflows are stronger than upflows through the joint action of gravitational acceleration/deceleration and pressure gradients. One cause of this discrepancy is the image degradation caused by optical distortion and light diffraction and scattering that takes place in an imaging instrument. We apply a deconvolution technique to Hinode /SP data inmore » an attempt to recover the original solar scene. Our results show a significant enhancement in both the convective upflows and downflows but particularly for the latter. After deconvolution, the up- and downflows reach maximum amplitudes of −3.0 km s{sup −1} and +3.0 km s{sup −1} at an average geometrical height of roughly 50 km, respectively. We found that the velocity distributions after deconvolution match those derived from numerical simulations. After deconvolution, the net LOS velocity averaged over the whole field of view lies close to zero as expected in a rough sense from mass balance.« less

Momentum balance in four solar flares

NASA Technical Reports Server (NTRS)

Canfield, Richard C.; Metcalf, Thomas R.; Zarro, Dominic M.; Lemen, James R.

1990-01-01

Solar Maximum Mission soft X-ray spectra and National Solar Observatory (Sacramento Peak) H-alpha spectra were combined in a study of high-speed flows during the impulsive phase of four solar flares. In all events, a blue asymmetry (indicative of upflows) was observed in the coronal Ca XIX line during the soft X-ray rise phase. In all events a red asymmetry (indicative of downflows) was observed simultaneously in chromospheric H-alpha. These oppositely directed flows were concurrent with impulsive hard X-ray emission. Combining the velocity data with estimates of the density based on emission measurements and volume estimates, it is shown that for the impulsive phase as a whole the total momentum of upflowing soft X-ray plasma equaled that of the downflowing H-alpha plasma, to within an order of magnitude, in all four events. Only the chromospheric evaporation model predicts equal total momentum in the upflowing soft X-ray-emitting and downflowing H-alphba-emitting materials.

Color and Morphology of Lava Flows on Io

NASA Astrophysics Data System (ADS)

Piatek, Jennifer L.; McElfresh, Sarah B. Z.; Byrnes, Jeffrey M.; Hale, Amy Snyder; Crown, David A.

2000-12-01

Analyses of color and morphologic changes in Voyager images of lava flows on Io were conducted to extend previous flow studies to additional volcanoes in preparation for comparison to Galileo data. Blue and orange filter images of Atar, Daedalus, and Ra Paterae were examined to identify systematic downflow decreases in blue/orange reflectivity suggested in earlier studies as diagnostic of color changes in cooled sulfur flows. Analyses of the color and morphology of 21 lava flows were conducted at these volcanoes, with additional morphologic analysis of lava flows at Agni, Masaaw, Mbali, Shoshu, and Talos Paterae. A total of 66 lava flows of up to 245 km in length were mapped to identify morphologic changes consistent with the rheologic changes expected to occur in sulfur flows. Although downflow color changes are observed, the trends are not consistent, even at the same edifice. Individual flows exhibit a statistically significant increase in blue/orange ratio, decrease in blue/orange ratio, or a lack of progressive downflow color variation. Color changes have similar magnitudes downflow and across flow, and the color ranges observed are similar from volcano to volcano, suggesting that similar processes are controlling color ratios at these edifices. In addition, using flow widening and branching as an indicator of the low viscosity exhibited by sulfur cooling from high temperatures, these flows do not exhibit morphologic changes consistent with the systematic behavior expected from the simple progressive cooling of sulfur.

Core cooling under accident conditions at the high flux beam reactor (HFBR)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tichler, P.; Cheng, L.; Fauske, H.

In certain accident scenarios, e.g. loss of coolant accidents (LOCA) all forced flow cooling is lost. Decay heating causes a temperature increase in the core coolant and the resulting thermal buoyancy causes a reversal of the flow direction to a natural circulation mode. Although there was experimental evidence during the reactor design period (1958--1963) that the heat removal capacity in the fully developed natural circulation cooling mode was relatively high, it was not possible to make a confident prediction of the heat removal capacity during the transition from downflow to natural circulation. In a LOCA scenario where even limited fuelmore » damage occurs and natural circulation is established, fission product gases could be carried from the damaged fuel by steam into areas where operator access is required to maintain the core in a coolable configuration. This would force evacuation of the building and lead to extensive core damage. As a result the HFBR was shut down by the Department of Energy (DOE) and an extensive review of the HFBR was initiated. In an effort to address this issue BNL developed a model designed to predict the heat removal limit during flow reversal that was found to be in good agreement with the test results. Currently a thermal-hydraulic test program is being developed to provide a more realistic and defensible estimate of the flow reversal heat removal limit so that the reactor power level can be increased.« less

Observational Signatures of Magnetic Reconnection in the Extended Corona

NASA Technical Reports Server (NTRS)

Savage, Sabrina; West, Matthew J.; Seaton, Daniel B.; Kobelski, Adam

2016-01-01

Observational signatures of reconnection have been studied extensively in the lower corona for decades, successfully providing insight into energy release mechanisms in the region above post-flare arcade loops and below 1.5 solar radii. During large eruptive events, however, energy release continues to occur well beyond the presence of reconnection signatures at these low heights. Supra-Arcade Downflows (SADs) and Supra-Arcade Downflowing Loops (SADLs) are particularly useful measures of continual reconnection in the corona as they may indicate the presence and path of retracting post-reconnection loops. SADs and SADLs have been faintly observed up to 18 hours beyond the passage of coronas mass ejections through the SOHO/LASCO field of view, but a recent event from 2014 October 14 associated with giant arches provides very clear observations of these downflows for days after the initial eruption. We report on this unique event and compare these findings with observational signatures of magnetic reconnection in the extended corona for more typical eruptions.

Observational Signatures of Magnetic Reconnection in the Extended Corona

NASA Technical Reports Server (NTRS)

Savage, Sabrina; West, Matthew J.; Seaton, Danial B.; Kobelski, Adam

2016-01-01

Observational signatures of reconnection have been studied extensively in the lower corona for decades, successfully providing insight into energy release mechanisms in the region above post-flare arcade loops and below 1.5 solar radii. During large eruptive events, however, energy release continues to occur well beyond the presence of reconnection signatures at these low heights. Supra-Arcade Downflows (SADs) and Supra-Arcade Downflowing Loops (SADLs) are particularly useful measures of continual reconnection in the corona as they may indicate the presence and path of retracting post-reconnection loops. SADs and SADLs have been faintly observed up to 18 hours beyond the passage of corona mass ejections through the SOHO/LASCO field of view, but a recent event from 2014 October 14 associated with giant arches provides very clear observations of these downflows for days after the initial eruption. We report on this unique event and compare these findings with observational signatures of magnetic reconnection in the extended corona for more typical eruptions.

Observational Signatures of Magnetic Reconnection in the Extended Corona

NASA Technical Reports Server (NTRS)

Savage, Sabrina; West, Matthew J.; Seaton, Daniel B.; Kobelski, Adam

2017-01-01

Observational signatures of reconnection have been studied extensively in the lower corona for decades, successfully providing insight into energy release mechanisms in the region above post-flare arcade loops and below 1.5 solar radii. During large eruptive events, however, energy release continues to occur well beyond the presence of reconnection signatures at these low heights. Supra-Arcade Downflows (SADs) and Supra-Arcade Downflowing Loops (SADLs) are particularly useful measures of continual reconnection in the corona as they may indicate the presence and path of retracting post-reconnection loops. SADs and SADLs have been faintly observed up to 18 hours beyond the passage of corona mass ejections through the SOHO/LASCO field of view, but a recent event from 2014 October 14 associated with giant arches provides very clear observations of these downflows for days after the initial eruption. We report on this unique event and compare these findings with observational signatures of magnetic reconnection in the extended corona for more typical eruptions.

Quantitative Examination of a Large Sample of Supra-Arcade Downflows in Eruptive Solar Flares

NASA Technical Reports Server (NTRS)

Savage, Sabrina L.; McKenzie, David E.

2011-01-01

Sunward-flowing voids above post-coronal mass ejection flare arcades were first discovered using the soft X-ray telescope aboard Yohkoh and have since been observed with TRACE (extreme ultraviolet (EUV)), SOHO/LASCO (white light), SOHO/SUMER (EUV spectra), and Hinode/XRT (soft X-rays). Supra-arcade downflow (SAD) observations suggest that they are the cross-sections of thin flux tubes retracting from a reconnection site high in the corona. Supra-arcade downflowing loops (SADLs) have also been observed under similar circumstances and are theorized to be SADs viewed from a perpendicular angle. Although previous studies have focused on dark flows because they are easier to detect and complementary spectral data analysis reveals their magnetic nature, the signal intensity of the flows actually ranges from dark to bright. This implies that newly reconnected coronal loops can contain a range of hot plasma density. Previous studies have presented detailed SAD observations for a small number of flares. In this paper, we present a substantial SADs and SADLs flare catalog. We have applied semiautomatic detection software to several of these events to detect and track individual downflows thereby providing statistically significant samples of parameters such as velocity, acceleration, area, magnetic flux, shrinkage energy, and reconnection rate. We discuss these measurements (particularly the unexpected result of the speeds being an order of magnitude slower than the assumed Alfven speed), how they were obtained, and potential impact on reconnection models.

Influence of gravity on transport and retention of representative engineered nanoparticles in quartz sand.

PubMed

Cai, Li; Zhu, Jinghan; Hou, Yanglong; Tong, Meiping; Kim, Hyunjung

2015-10-01

Four types of NPs: carbon nanotubes and graphene oxide (carbon-based NPs), titanium dioxide and zinc oxide metal-oxide NPs, were utilized to systematically determine the influence of gravity on the transport of NPs in porous media. Packed column experiments for two types of carbon-based NPs were performed under unfavorable conditions in both up-flow (gravity-negative) and down-flow (gravity-positive) orientations, while for two types of metal-oxide NPs, experiments were performed under both unfavorable and favorable conditions in both up-flow and down-flow orientations. Both breakthrough curves and retained profiles of two types of carbon-based NPs in up-flow orientation were equivalent to those in down-flow orientation, indicating that gravity had negligible effect on the transport and retention of carbon-based NPs under unfavorable conditions. In contrast, under both unfavorable and favorable conditions, the breakthrough curves for two types of metal-oxide NPs in down-flow orientation were lower relative to those in up-flow orientation, indicating that gravity could decrease the transport of metal-oxide NPs in porous media. The distinct effect of gravity on the transport and retention of carbon-based and metal-oxide NPs was mainly attributed to the contribution of gravity to the force balance on the NPs in quartz sand. The contribution of gravity was determined by the interplay of the density and sizes of NP aggregates under examined solution conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Vigorous convection in a sunspot granular light bridge

NASA Astrophysics Data System (ADS)

Lagg, Andreas; Solanki, Sami K.; van Noort, Michiel; Danilovic, Sanja

2014-08-01

Context. Light bridges are the most prominent manifestation of convection in sunspots. The brightest representatives are granular light bridges composed of features that appear to be similar to granules. Aims: An in-depth study of the convective motions, temperature stratification, and magnetic field vector in and around light bridge granules is presented with the aim of identifying similarities and differences to typical quiet-Sun granules. Methods: Spectropolarimetric data from the Hinode Solar Optical Telescope were analyzed using a spatially coupled inversion technique to retrieve the stratified atmospheric parameters of light bridge and quiet-Sun granules. Results: Central hot upflows surrounded by cooler fast downflows reaching 10 km s-1 clearly establish the convective nature of the light bridge granules. The inner part of these granules in the near surface layers is field free and is covered by a cusp-like magnetic field configuration. We observe hints of field reversals at the location of the fast downflows. The quiet-Sun granules in the vicinity of the sunspot are covered by a low-lying canopy field extending radially outward from the spot. Conclusions: The similarities between quiet-Sun and light bridge granules point to the deep anchoring of granular light bridges in the underlying convection zone. The fast, supersonic downflows are most likely a result of a combination of invigorated convection in the light bridge granule due to radiative cooling into the neighboring umbra and the fact that we sample deeper layers, since the downflows are immediately adjacent to the slanted walls of the Wilson depression. The two movies are available in electronic form at http://www.aanda.org

Explosive plasma flows in a solar flare

NASA Technical Reports Server (NTRS)

Zarro, Dominic M.; Canfield, Richard C.; Metcalf, Thomas R.; Strong, Keith T.

1988-01-01

Solar Maximum Mission soft X-ray data and Sacramento Peak Observatory H-alpha observations are combined in a study of the impulsive phase of a solar flare. A blue asymmetry, indicative of upflows, was observed in the coronal Ca XIX line during the soft X-ray rise phase. A red asymmetry, indicative of downflows, was observed simultaneously in chromospheric H-alpha emitted from bright flare kernels during the period of hard X-ray emission. Combining the velocity data with a measurement of coronal electron density, it is shown that the impulsive phase momentum of upflowing soft X-ray-emitting plasma equalled that of the downflowing H-alpha-emitting plasma to within one order of magnitude. In particular, the momentum of the upflowing plasma was 2 x 10 to the 21st g cm/s while that of the downflowing plasma was 7 x 10 to the 21st g cm/s, with a factor of 2 uncertainty on each value. This equality supports the explosive chromospheric evaporation model of solar flares, in which a sudden pressure increase at the footprint of a coronal loop produces oppositely directed flows in the heated plasma.

Non-catalytic steam hydrolysis of fats. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deibert, M.C.

1992-08-28

Hydrolysis of fats and oils produces fatty acid and glycerol. The catalyzed, liquid phase Colgate-Emry process, state-of-the-art, produces impure products that require extensive energy investment for their purification to commercial grade. Non-catalytic steam hydrolysis may produce products more easily purified. A bench-scale hydrolyzer was designed and constructed to contact descending liquid fat or oil with rising superheated steam. Each of the five stages in the reactor was designed similar to a distillation column stage to promote intimate liquid-gas contact. Degree of hydrolysis achieved in continuous tests using tallow feed were 15% at 280C and 35% at 300C at a tallow-to-steammore » mass feed ratio of 4.2. At a feed ratio of 9.2, the degree of hydrolysis was 21% at 300C. Decomposition was strongly evident at 325C but not at lower temperatures. Soybean oil rapidly polymerized under reaction conditions. Batch tests at 320C produced degrees of hydrolyses of between 44% and 63% using tallow and palm oil feeds. Over 95% fatty acids were present in a clean, readily separated organic portion of the overhead product from most tests. The test reactor had serious hydraulic resistance to liquid down-flow which limited operation to very long liquid residence times. These times are in excess of those that tallow and palm oil are stable at the reaction temperature. Little glycerol and extensive light organics were produced indicating that unexplained competing reactions to hydrolysis occurred in the experimental system. Further tests using an improved reactor will be required.« less

Non-catalytic steam hydrolysis of fats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deibert, M.C.

1992-08-28

Hydrolysis of fats and oils produces fatty acid and glycerol. The catalyzed, liquid phase Colgate-Emry process, state-of-the-art, produces impure products that require extensive energy investment for their purification to commercial grade. Non-catalytic steam hydrolysis may produce products more easily purified. A bench-scale hydrolyzer was designed and constructed to contact descending liquid fat or oil with rising superheated steam. Each of the five stages in the reactor was designed similar to a distillation column stage to promote intimate liquid-gas contact. Degree of hydrolysis achieved in continuous tests using tallow feed were 15% at 280C and 35% at 300C at a tallow-to-steammore » mass feed ratio of 4.2. At a feed ratio of 9.2, the degree of hydrolysis was 21% at 300C. Decomposition was strongly evident at 325C but not at lower temperatures. Soybean oil rapidly polymerized under reaction conditions. Batch tests at 320C produced degrees of hydrolyses of between 44% and 63% using tallow and palm oil feeds. Over 95% fatty acids were present in a clean, readily separated organic portion of the overhead product from most tests. The test reactor had serious hydraulic resistance to liquid down-flow which limited operation to very long liquid residence times. These times are in excess of those that tallow and palm oil are stable at the reaction temperature. Little glycerol and extensive light organics were produced indicating that unexplained competing reactions to hydrolysis occurred in the experimental system. Further tests using an improved reactor will be required.« less

Cultivation of methanogenic community from 2-km deep subseafloor coalbeds using a continuous-flow bioreactor

NASA Astrophysics Data System (ADS)

Imachi, H.; Tasumi, E.; Morono, Y.; Ito, M.; Takai, K.; Inagaki, F.

2013-12-01

Deep subseafloor environments associated with hydrocarbon reservoirs have been least explored by previous scientific drilling and hence the nature of deep subseafloor life and its ecological roles in the carbon cycle remain largely unknown. In this study, we performed cultivation of subseafloor methanogenic communities using a continuous-flow bioreactor with polyurethane sponges, called down-flow hanging sponge (DHS) reactor. The sample used for the reactor cultivation was obtained from 2 km-deep coalbeds off the Shimokita Peninsula of Japan, the northwestern Pacific, during the Integrated Ocean Drilling Program (IODP) Expedition 337 using a riser drilling technology of the drilling vessel Chikyu. The coalbed samples were incubated anaerobically in the DHS reactor at the in-situ temperature of 40°C. Synthetic seawater supplemented with a tiny amount of yeast extract, acetate, propionate and butyrate was provided into the DHS reactor. After 34 days of the bioreactor operation, a small production of methane was observed. The methane concentration was gradually increased and the stable carbon isotopic composition of methane was consistency 13C-depleted during the bioreactor operation, indicating the occurrence of microbial methanogenesis. Microscopic observation showed that the enrichment culture contained a variety of microorganisms, including methanogen-like rod-shaped cells with F420 auto-fluorescence. Interestingly, many spore-like particles were observed in the bioreactor enrichment. Phylogenetic analysis of 16S rRNA genes showed the growth of phylogenetically diverse bacteria and archaea in the DHS reactor. Predominant archaeal components were closely related to hydrogenotrophic methanogens within the genus Methanobacterium. Some predominant bacteria were related to the spore-formers within the class Clostridia, which are overall in good agreement with microscopic observations. By analyzing ion images using a nano-scale secondary ion mass spectrometry (NanoSIMS), 13C-bicarbonate incorporation of rod-shaped methanogens, as well as 13C-acetate incorporation of other cells, was observed. These microbiological data obtained from the DHS reactor generally support a geochemical indication that microbial processes contribute to the biogeochemical carbon cycle associated with 2 km-coalbeds in the deep subseafloor biosphere.

Driving Solar Giant Cells through the Self-organization of Near-surface Plumes

NASA Astrophysics Data System (ADS)

Nelson, Nicholas J.; Featherstone, Nicholas A.; Miesch, Mark S.; Toomre, Juri

2018-06-01

Global 3D simulations of solar giant-cell convection have provided significant insight into the processes which yield the Sun’s observed differential rotation and cyclic dynamo action. However, as we move to higher-resolution simulations a variety of codes have encountered what has been termed the convection conundrum. As these simulations increase in resolution and hence the level of turbulence achieved, they tend to produce weak or even anti-solar differential rotation patterns associated with a weak rotational influence (high Rossby number) due to large convective velocities. One potential culprit for this convection conundrum is the upper boundary condition applied in most simulations, which is generally impenetrable. Here we present an alternative stochastic plume boundary condition which imposes small-scale convective plumes designed to mimic near-surface convective downflows, thus allowing convection to carry the majority of the outward solar energy flux up to and through our simulated upper boundary. The use of a plume boundary condition leads to significant changes in the convective driving realized in the simulated domain and thus to the convective energy transport, the dominant scale of the convective enthalpy flux, and the relative strength of the strongest downflows, the downflow network, and the convective upflows. These changes are present even far from the upper boundary layer. Additionally, we demonstrate that, in spite of significant changes, giant cell morphology in the convective patterns is still achieved with self-organization of the imposed boundary plumes into downflow lanes, cellular patterns, and even rotationally aligned banana cells in equatorial regions. This plume boundary presents an alternative pathway for 3D global convection simulations where driving is non-local and may provide a new approach toward addressing the convection conundrum.

NUMERICAL SIMULATIONS OF SUNSPOT DECAY: ON THE PENUMBRA–EVERSHED FLOW–MOAT FLOW CONNECTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rempel, M., E-mail: rempel@ucar.edu

We present a series of high-resolution sunspot simulations that cover a timespan of up to 100 hr. The simulation domain extends about 18 Mm in depth beneath the photosphere and 98 Mm horizontally. We use open boundary conditions that do not maintain the initial field structure against decay driven by convective motions. We consider two setups: a sunspot simulation with penumbra, and a “naked-spot” simulation in which we removed the penumbra after 20 hr through a change in the magnetic top boundary condition. While the sunspot has an Evershed outflow of 3–4 km s{sup −1}, the naked spot is surroundedmore » by an inflow of 1–2 km s{sup −1} in close proximity. However, both spots are surrounded by an outflow on larger scales with a few 100 m s{sup −1} flow speed in the photosphere. While the sunspot has an almost constant magnetic flux content for the simulated timespan of three to four days, the naked spot decays steadily at a rate of 10{sup 21} Mx day{sup −1}. A region with reduced downflow filling factor, which is more extended for the sunspot, surrounds both spots. The absence of downflows perturbs the upflow/downflow mass flux balance and leads to a large-scale radially overturning flow system; the photospheric component of this flow is the observable moat flow. The reduction of the downflow filling factor also inhibits the submergence of magnetic field in the proximity of the spots, which stabilizes them against decay. While this effect is present for both spots, it is more pronounced for the sunspot and explains the almost stationary magnetic flux content.« less

Down-flow moving-bed gasifier with catalyst recycle

DOEpatents

Halow, John S.

1999-01-01

The gasification of coal and other carbonaceous materials by an endothermic gasification reaction is achieved in the presence of a catalyst in a down-flow, moving-bed gasifier. Catalyst is removed along with ash from the gasifier and is then sufficiently heated in a riser/burner by the combustion of residual carbon in the ash to volatilize the catalyst. This volatilized catalyst is returned to the gasifier where it uniformly contacts and condenses on the carbonaceous material. Also, the hot gaseous combustion products resulting from the combustion of the carbon in the ash along with excess air are introduced into the gasifier for providing heat energy used in the endothermic reaction.

Combined buoyancy and flow direction effects on saturated boiling critical heat flux in liquid nitrogen

NASA Technical Reports Server (NTRS)

Papell, S. S.

1972-01-01

Buoyancy effects on the critical heat flux and general data trends for a liquid nitrogen internal flow system were determined by comparison of upflow and downflow data under identical test conditions. The test section had a 1.28 cm diameter flow passage and a 30.5 cm heated length which was subjected to uniform heat fluxes through resistance heating. Test conditions covered a range of pressures from 3.4 to 10.2 atm, inlet velocities from 0.23 to 3.51 m/sec, with the liquid nitrogen temperature at saturated inlet conditions. Data comparisons showed that the critical heat flux for downflow could be up to 36 percent lower than for upflow. A nonmonotonic relationship between the critical heat flux and velocity was determined for upflow but not for downflow. A limiting inlet velocity of 4.12 m/sec was determined to be the minimum velocity required to completely suppress the influence of buoyancy on the critical heat flux for this saturated inlet flow system. A correlation of this limiting fluid velocity is presented that was developed from previously published subcooled liquid nitrogen data and the saturated data of this investigation.

Supra Arcade Downflows with XRT Informed by Dipolarization Fronts with THEMIS

NASA Technical Reports Server (NTRS)

Kobelski, Adam; Savage, Sabrina Leah; Malaspina, David

2016-01-01

Magnetic reconnection can rapidly reconfigure the magnetic field of the corona, accelerating plasma through the site of reconnection. Ambiguities due to the nature of remote sensing have complicated the interpretation of observations of the inflowing and outflowing plasma in reconnecting regions. In particular, the interpretation of sunward moving density depletions above flare arcades (known as Supra Arcade Downflows - SADs) is still debated. Hinode/XRT has provided a wealth of observations for SADs and helped inform our current understanding of these structures. SADs have been interpreted as wakes behind newly reconnected and outflowing loops (Supra Arcade Downflowing Loops - SADLs). Models have shown the plausibility of this interpretation, though this interpretation has not yet been fully accepted. We present here observations of newly reconnected outflowing loops observed via in situ instruments in the magnetosphere. These observations, provided by five THEMIS spacecraft, show that around retracting loops (dipolarization fronts in this context) similar dynamic temperature and density structures are found as seen in SADs. We compare data from multiple SADs and dipolarization fronts to show that the observational signatures implied in the corona can be directly observed in similar plasma regimes in the magnetosphere, strongly favoring the interpretation of SADs as wakes behind retracting loops.

Down-flow moving-bed gasifier with catalyst recycle

DOEpatents

Halow, J.S.

1999-04-20

The gasification of coal and other carbonaceous materials by an endothermic gasification reaction is achieved in the presence of a catalyst in a down-flow, moving-bed gasifier. Catalyst is removed along with ash from the gasifier and is then sufficiently heated in a riser/burner by the combustion of residual carbon in the ash to volatilize the catalyst. This volatilized catalyst is returned to the gasifier where it uniformly contacts and condenses on the carbonaceous material. Also, the hot gaseous combustion products resulting from the combustion of the carbon in the ash along with excess air are introduced into the gasifier for providing heat energy used in the endothermic reaction. 1 fig.

MHD SIMULATIONS OF CORONAL SUPRA-ARCADE DOWNFLOWS INCLUDING ANISOTROPIC THERMAL CONDUCTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zurbriggen, E.; Costa, A.; Schneiter, M.

2016-11-20

Coronal supra-arcade downflows (SADs) are observed as dark trails descending toward hot turbulent-fan-shaped regions. Due to the large temperature values and gradients in these fan regions, the thermal conduction (TC) should be very efficient. While several models have been proposed to explain the triggering and the evolution of SADs, none of these scenarios address a systematic consideration of TC. Thus, we accomplish this task numerically simulating the evolution of SADs within this framework. That is, SADs are conceived as voided (subdense) cavities formed by nonlinear waves triggered by downflowing bursty localized reconnection events in a perturbed hot fan. We generatemore » a properly turbulent fan, obtained by a stirring force that permits control of the energy and vorticity input in the medium where SADs develop. We include anisotropic TC and consider plasma properties consistent with observations. Our aim is to study whether it is possible to prevent SADs from vanishing by thermal diffusion. We find that this will be the case, depending on the turbulence parameters, in particular if the magnetic field lines are able to envelope the voided cavities, thermally isolating them from the hot environment. Velocity shear perturbations that are able to generate instabilities of the Kelvin–Helmholtz type help to produce magnetic islands, extending the lifetime of SADs.« less

Spectroscopic Observations of a Solar Flare and the Associated Coronal Mass Ejection

NASA Astrophysics Data System (ADS)

Murray, S.; Tian, H.; McKillop, S.

2013-12-01

We used data from the EUV Imaging Spectrometer (EIS) on board Hinode to examine a coronal mass ejection and a preceding flare observed on 21 November 2012 between 15:00 and 17:00 UT. Images from the Atmospheric Imaging Assembly on the Solar Dynamics Observatory were used to align the data from EIS with specific events occurring. We analyzed spectra of a few emission lines at three locations on the flare site and one location in the erupting prominence. On the flare site, we found line profiles showing typical characteristics of chromospheric evaporation: downflows at cooler lines and upflows at hotter lines. At one particular location on the flare site, we clearly identified dominant downflows on the order of 100 km/s in lines through Fe VIII to Fe XVI. To the best of our knowledge, this is the first time that such strong high-speed downflows have been spectroscopically observed in the impulsive phase of solar flares. The profile of the Fe VIII 184.54 line reveals two peaks and we were able to use the double Gaussian fit to separate the rapid downflows of dense material from the nearly stationary coronal background emission. For the erupting prominence, we were able to analyze multiple lines, cooler and warmer, of interest using this double Gaussian fit to separate the background emission from the emission of the ejected material. Our results show that the LOS velocities of the ejected material are about 100 km/s in the lower corona. Additionally, in each region of interest, we used the ratio of the density-sensitive line pair FeXII 195/186 to determine the electron density. Our results clearly show that the coronal densities were greatly enhanced during the flare. The density of the ejected material is also much larger than the typical coronal density. This research was supported by the NSF grant for the Solar Physics REU Program at the Smithsonian Astrophysical Observatory (AGS-1263241).

Experimental Study of Combined Forced and Free Laminar Convection in a Vertical Tube

NASA Technical Reports Server (NTRS)

Hallman, Theodore M.

1961-01-01

An apparatus was built to verify an analysis of combined forced and free convection in a vertical tube with uniform wall heat flux and to determine the limits of the analysis. The test section was electrically heated by resistance heating of the tube wall and was instrumented with thermocouples in such a way that detailed thermal entrance heat-transfer coefficients could be obtained for both upflow and downflow and any asymmetry in wall temperature could be detected. The experiments showed that fully developed heat-transfer results, predicted by a previous analysis, were confirmed over the range of Rayleigh numbers investigated. The concept of "locally fully developed" heat transfer was established. This concept involves the assumption that the fully developed heat-transfer analysis can be applied locally even though the Rayleigh number is varying along the tube because of physical-property variations with temperature. Thermal entrance region data were obtained for pure forced convection and for combined forced and free convection. The analysis of laminar pure forced convection in the thermal entrance region conducted by Siegel, Sparrow, and Hallman was experimentally confirmed. A transition to an eddy motion, indicated by a fluctuation in wall temperature was found in many of the upflow runs. A stability correlation was found. The fully developed Nusselt numbers in downflow were below those for pure forced convection but fell about 10 percent above the analytical curve. Quite large circumferential variations in wall temperature were observed in downflow as compaired with those encountered in upflow, and the fully developed Nussalt numbers reported are based on average wall temperatures determined by averaging the readings of two diametrically opposite wall thermocouples at each axial position. With larger heating rates in downflow the wall temperature distributions strongly suggested a cell flow near the bottom. At still larger heating rates the wall temperatures varied in a periodic way.

Changes in CSF flow after one-stage posterior vertebral column resection in scoliosis patients with syringomyelia and Chiari malformation type I.

PubMed

Wang, Yingsong; Xie, Jingming; Zhao, Zhi; Zhang, Ying; Li, Tao; Si, Yongyu

2013-05-01

Phase contrast-cine MRI (PC-cine MRI) studies in patients with syringomyelia and Chiari malformation Type I (CM-I) have demonstrated abnormal CSF flow across the foramen magnum, which can revert to normal after craniocervical decompression with syrinx shrinkage. In order to investigate the mechanisms leading to postoperative syringomyelia shrinkage, the authors studied the hydrodynamic changes of CSF flow in the craniocervical junction and spinal canal in patients with scoliosis associated with syringomyelia after one-stage deformity correction by posterior vertebral column resection. Preoperative and postoperative CSF flow dynamics at the levels of the foramen magnum, C-7, T-7 (or apex), and L-1 were assessed by electrocardiogram-synchronized cardiac-gated PC-cine MRI in 8 adolescent patients suffering from severe scoliosis with syringomyelia and CM-I (scoliosis group) and undergoing posterior vertebral column resection. An additional 8 patients with syringomyelia and CM-I without spinal deformity (syrinx group) and 8 healthy volunteers (control group) were also enrolled. Mean values were obtained for the following parameters: the duration of a CSF cycle, the duration of caudad CSF flow (CSF downflow [DF]) and cephalad CSF flow (CSF upflow [UF]), the ratio of DF duration to CSF cycle duration (DF%), and the ratio of UF duration to CSF cycle duration (UF%). The ratio of the stationary phase (SP) duration to CSF cycle duration was calculated (SP%). The maximum downflow velocities (VD max) and maximum upflow velocities (VU max) were measured. SPSS (version 14.0) was used for all statistical analysis. Patients in the scoliosis group underwent one-stage posterior vertebral column resection for deformity correction without suboccipital decompression. The mean preoperative coronal Cobb angle was 102.4° (range 76°-138°). The mean postoperative Cobb angle was 41.7° (range 12°-75°), with an average correction rate of 59.3%. During the follow-up, 1 patient with hypermyotonia experienced a significant decrease of muscle tension and 1 patient with reduced anal sphincter tone manifested recovery. A total of 5 patients demonstrated a significant decrease (> 30%) in syrinx size. With respect to changes in CSF flow dynamics, the syrinx group was characterized by slower and shorter downflow than the control group, and the difference was more significant at the foramen magnum and C-7 levels. In patients with scoliosis, CSF downflow at the foramen magnum level was significantly restricted, and a prolonged stationary phase indicated increased obstruction of CSF flow. After posterior vertebral column resection, the peak velocity of CSF flow at the foramen magnum increased, and the downflow phase duration was markedly prolonged. The parameters showed a return to almost normal CSF dynamics at the craniocervical region, and this improvement was maintained for 6-12 months of follow-up. There were distinct abnormalities of CSF flow at the craniocervical junction in patients with syringomyelia. Abnormal dynamics of downflow could be aggravated by associated severe spinal deformity and improved by correction via posterior vertebral column resection.

Removal of Iron and Manganese from Natural Groundwater by Continuous Reactor Using Activated and Natural Mordenite Mineral Adsorption

NASA Astrophysics Data System (ADS)

Zevi, Y.; Dewita, S.; Aghasa, A.; Dwinandha, D.

2018-01-01

Mordenite minerals derived from Sukabumi natural green stone founded in Indonesia was tested in order to remove iron and manganese from natural groundwater. This research used two types of adsorbents which were consisted of physically activated and natural mordenite. Physical activation of the mordenite was carried out by heating at 400-600°C for two hours. Batch system experiments was also conducted as a preliminary experiment. Batch system proved that both activated and natural mordenite minerals were capable of reducing iron and manganese concentration from natural groundwater. Then, continuous experiment was conducted using down-flow system with 45 ml/minute of constant flow rate. The iron & manganese removal efficiency using continuous reactor for physically activated and natural mordenite were 1.38-1.99%/minute & 0.8-1.49%/minute and 2.26%/minute & 1.37-2.26%/minute respectively. In addition, the regeneration treatment using NH4Cl solution managed to improve the removal efficiency of iron & manganese to 1.98%/minute & 1.77-1.90%/minute and 2.25%/minute & 2.02-2.21%/minute on physically activated mordenite and natural mordenite respectively. Subsequently, the activation of the new mordenite was carried out by immersing mordenite in NH4Cl solution. This chemical activation showed 2.42-2.75%/minute & 0.96 - 2.67 %/minute and 2.66 - 2.78 %/minute & 1.34 - 2.32 %/minute of iron & manganese removal efficiency per detention time for chemically activated and natural mordenite respectively.

CHROMOSPHERIC AND CORONAL WAVE GENERATION IN A MAGNETIC FLUX SHEATH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kato, Yoshiaki; Hansteen, Viggo; Gudiksen, Boris

2016-08-10

Using radiation magnetohydrodynamic simulations of the solar atmospheric layers from the upper convection zone to the lower corona, we investigate the self-consistent excitation of slow magneto-acoustic body waves (slow modes) in a magnetic flux concentration. We find that the convective downdrafts in the close surroundings of a two-dimensional flux slab “pump” the plasma inside it in the downward direction. This action produces a downflow inside the flux slab, which encompasses ever higher layers, causing an upwardly propagating rarefaction wave. The slow mode, excited by the adiabatic compression of the downflow near the optical surface, travels along the magnetic field inmore » the upward direction at the tube speed. It develops into a shock wave at chromospheric heights, where it dissipates, lifts the transition region, and produces an offspring in the form of a compressive wave that propagates further into the corona. In the wake of downflows and propagating shock waves, the atmosphere inside the flux slab in the chromosphere and higher tends to oscillate with a period of ν ≈ 4 mHz. We conclude that this process of “magnetic pumping” is a most plausible mechanism for the direct generation of longitudinal chromospheric and coronal compressive waves within magnetic flux concentrations, and it may provide an important heat source in the chromosphere. It may also be responsible for certain types of dynamic fibrils.« less

OBSERVATION AND ANALYSIS OF BALLISTIC DOWNFLOWS IN AN M-CLASS FLARE WITH THE INTERFACE REGION IMAGING SPECTROGRAPH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brannon, Sean R.

Despite significant advances in instrumentation, there remain no studies that analyze observations of on-disk flare loop plasma flows covering the entire evolution from chromospheric evaporation, through plasma cooling, to draining downflows. We present results from an imaging and spectroscopic observation from the Interface Region Imaging Spectrograph ( IRIS ) of the SOL2015–03–12T11:50:00 M-class flare, at high spatial resolution and time cadence. Our analysis of this event reveals initial plasma evaporation at flare temperatures indicated by 100–200 km s{sup −1} blueshifts in the Fe xxi line. We subsequently observe plasma cooling into chromospheric lines (Si iv and O iv) with ∼11more » minute delay, followed by loop draining at ∼40 km s{sup −1} as indicated by a “C”-shaped redshift structure and significant (∼60 km s{sup −1}) non-thermal broadening. We use density-sensitive lines to calculate a plasma density for the flare loops, and estimate a theoretical cooling time approximately equal to the observed delay. Finally, we use a simple elliptical free-fall draining model to construct synthetic spectra, and perform what we believe to be the first direct comparison of such synthetic spectra to observations of draining downflows in flare loops.« less

Distribution Functions of Sizes and Fluxes Determined from Supra-Arcade Downflows

NASA Technical Reports Server (NTRS)

McKenzie, D.; Savage, S.

2011-01-01

The frequency distributions of sizes and fluxes of supra-arcade downflows (SADs) provide information about the process of their creation. For example, a fractal creation process may be expected to yield a power-law distribution of sizes and/or fluxes. We examine 120 cross-sectional areas and magnetic flux estimates found by Savage & McKenzie for SADs, and find that (1) the areas are consistent with a log-normal distribution and (2) the fluxes are consistent with both a log-normal and an exponential distribution. Neither set of measurements is compatible with a power-law distribution nor a normal distribution. As a demonstration of the applicability of these findings to improved understanding of reconnection, we consider a simple SAD growth scenario with minimal assumptions, capable of producing a log-normal distribution.

3D MHD SIMULATION OF FLARE SUPRA-ARCADE DOWNFLOWS IN A TURBULENT CURRENT SHEET MEDIUM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cécere, M.; Zurbriggen, E.; Costa, A.

2015-07-01

Supra-arcade downflows (SADs) are sunward, generally dark, plasma density depletions originated above posteruption flare arcades. In this paper, using 3D MHD simulations we investigate whether the SAD cavities can be produced by a direct combination of the tearing mode and Kelvin–Helmholtz instabilities leading to a turbulent current sheet (CS) medium or if the current sheet is merely the background where SADs are produced, triggered by an impulsive deposition of energy. We find that to give an account of the observational dark lane structures an addition of local energy, provided by a reconnection event, is required. We suggest that there maymore » be a closed relation between characteristic SAD sizes and CS widths that must be satisfied to obtain an observable SAD.« less

3D MHD Simulation of Flare Supra-Arcade Downflows in a Turbulent Current Sheet Medium

NASA Astrophysics Data System (ADS)

Cécere, M.; Zurbriggen, E.; Costa, A.; Schneiter, M.

2015-07-01

Supra-arcade downflows (SADs) are sunward, generally dark, plasma density depletions originated above posteruption flare arcades. In this paper, using 3D MHD simulations we investigate whether the SAD cavities can be produced by a direct combination of the tearing mode and Kelvin-Helmholtz instabilities leading to a turbulent current sheet (CS) medium or if the current sheet is merely the background where SADs are produced, triggered by an impulsive deposition of energy. We find that to give an account of the observational dark lane structures an addition of local energy, provided by a reconnection event, is required. We suggest that there may be a closed relation between characteristic SAD sizes and CS widths that must be satisfied to obtain an observable SAD.

Extended Subadiabatic Layer in Simulations of Overshooting Convection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Käpylä, Petri J.; Arlt, Rainer; Rheinhardt, Matthias

2017-08-20

We present numerical simulations of hydrodynamic overshooting convection in local Cartesian domains. We find that a substantial fraction of the lower part of the convection zone (CZ) is stably stratified according to the Schwarzschild criterion while the enthalpy flux is outward directed. This occurs when the heat conduction profile at the bottom of the CZ is smoothly varying, based either on a Kramers-like opacity prescription as a function of temperature and density or a static profile of a similar shape. We show that the subadiabatic layer arises due to nonlocal energy transport by buoyantly driven downflows in the upper partsmore » of the CZ. Analysis of the force balance of the upflows and downflows confirms that convection is driven by cooling at the surface. We find that the commonly used prescription for the convective enthalpy flux being proportional to the negative entropy gradient does not hold in the stably stratified layers where the flux is positive. We demonstrate the existence of a non-gradient contribution to the enthalpy flux, which is estimated to be important throughout the convective layer. A quantitative analysis of downflows indicates a transition from a tree-like structure where smaller downdrafts merge into larger ones in the upper parts to a structure in the deeper parts where a height-independent number of strong downdrafts persist. This change of flow topology occurs when a substantial subadiabatic layer is present in the lower part of the CZ.« less

Time evolution of fine structures in the solar chromosphere.

NASA Astrophysics Data System (ADS)

Tsiropoula, G.; Alissandrakis, C. E.; Schmieder, B.

1994-10-01

We have studied the temporal evolution of two quiet chromospheric regions, one with a typical rosette and another with chains of mottles at the junction of three supergranules. The observations were obtained during 15 minutes with the Multichannel Subtractive Double Pass spectrograph (MSDP) operating in Hα at the Pic du Midi Observatory. We derived intensity maps and Doppler shift velocities at different wavelengths along the Hα profile over a two dimensional field of view. The observed contrast profiles were matched with theoretical contrast profiles using Beckers' cloud model for a more accurate determination of the line of sight velocity. A statistical analysis with cross correlation functions showed that the fine structures were stable in intensity over the observation period (15 min), but the line of sight velocity showed important changes within a few minutes. A detailed analysis of the velocities along the axes of dark mottles showed that the predominant pattern of bulk motion is that of downflow at their footpoints and alternating phases of upflow and downflow at their tops. This motion is consistent with Pikel'ner's model for spicules, which attributes this pattern to the reconnection of opposite magnetic filed lines. This picture is also consistent with the velocity reversals with time observed in spicules and may be associated to the systematic downflows observed in the transition region. Doppler shift velocities in dark mottles are too low compared to those derived with the cloud model; the latter are comparable to those reported for spicules, strengthening the view that these structures are identical.

DETECTION OF SUPERSONIC DOWNFLOWS AND ASSOCIATED HEATING EVENTS IN THE TRANSITION REGION ABOVE SUNSPOTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleint, L.; Martínez-Sykora, J.; Antolin, P.

Interface Region Imaging Spectrograph data allow us to study the solar transition region (TR) with an unprecedented spatial resolution of 0.''33. On 2013 August 30, we observed bursts of high Doppler shifts suggesting strong supersonic downflows of up to 200 km s{sup –1} and weaker, slightly slower upflows in the spectral lines Mg II h and k, C II 1336, Si IV 1394 Å, and 1403 Å, that are correlated with brightenings in the slitjaw images (SJIs). The bursty behavior lasts throughout the 2 hr observation, with average burst durations of about 20 s. The locations of these short-lived events appear to bemore » the umbral and penumbral footpoints of EUV loops. Fast apparent downflows are observed along these loops in the SJIs and in the Atmospheric Imaging Assembly, suggesting that the loops are thermally unstable. We interpret the observations as cool material falling from coronal heights, and especially coronal rain produced along the thermally unstable loops, which leads to an increase of intensity at the loop footpoints, probably indicating an increase of density and temperature in the TR. The rain speeds are on the higher end of previously reported speeds for this phenomenon, and possibly higher than the free-fall velocity along the loops. On other observing days, similar bright dots are sometimes aligned into ribbons, resembling small flare ribbons. These observations provide a first insight into small-scale heating events in sunspots in the TR.« less

MHD simulations of coronal dark downflows considering thermal conduction

NASA Astrophysics Data System (ADS)

Zurbriggen, E.; Costa, A.; Esquivel, A.; Schneiter, M.; Cécere, M.

2017-10-01

While several scenarios have been proposed to explain supra-arcade downflows (SADs) observed descending through turbulent hot regions, none of them have systematically addressed the consideration of thermal conduction. The SADs are known to be voided cavities. Our model assumes that SADs are triggered by bursty localized reconnection events that produce non-linear waves generating the voided cavity. These subdense cavities are sustained in time because they are hotter than their surrounding medium. Due to the low density and large temperature values of the plasma we expect the thermal conduction to be an important process. Our main aim here is to study if it is possible to generate SADs in the framework of our model considering thermal conduction. We carry on 2D MHD simulations including anisotropic thermal conduction, and find that if the magnetic lines envelope the cavities, they can be isolated from the hot environment and be identified as SADs.

Magnetic loops, downflows, and convection in the solar corona

NASA Technical Reports Server (NTRS)

Foukal, P.

1978-01-01

Optical and extreme-ultraviolet observations of solar loop structures show that flows of cool plasma from condensations near the loop apex are a common property of loops associated with radiations whose maximum temperature is greater than approximately 7000 K and less than approximately 3,000,000 K. It is suggested that the mass balance of these structures indicates reconnection by means of plasma motion across field lines under rather general circumstances (not only after flares). It is shown that the cool material has lower gas pressure than the surrounding coronal medium. The density structure of the bright extreme ultraviolet loops suggests that downflows of cool gas result from isobaric condensation of plasma that is either out of thermal equilibrium with the local energy deposition rate into the corona, or is thermally unstable. The evidence is thought to indicate that magnetic fields act to induce a pattern of forced convection.

BMP FILTERS: UPFLOW VS. DOWNFLOW

EPA Science Inventory

Filtration methods have been found to be effective in reducing pollutant levels in stormwater. The main drawback of these methods is that the filters get clogged frequently and require periodical maintenance. In stormwater treatment, because of the cost of pumping, the filters ar...

Downflow dryout in a heated ribbed vertical annulus with a cosine power profile (Results from test series ECS-2, WSR, and ECS-2cE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larson, T.K.; Anderson, J.L.; Condie, K.G.

Experiments designed to investigate surface dryout in a heated, ribbed annulus test section simulating one of the annular coolant channels of a Savannah River Plant production reactor Mark 22 fuel assembly have been conducted at the Idaho National Engineering Laboratory. The inner surface of the annulus was constructed of aluminum and was electrically heated to provide an axial cosine power profile and a flat azimuthal power shape. Data presented in this report are from the ECS-2, WSR, and ECS-2cE series of tests. These experiments were conducted to examine the onset of wall thermal excursion for a range of flow, inletmore » fluid temperature, and annulus outlet pressure. Hydraulic boundary conditions on the test section represent flowrates (0.1--1.4 1/s), inlet fluid temperatures (293--345 K), and outlet pressures (-18--139.7 cm of water relative to the bottom of the heated length (61--200 cm of water relative to the bottom of the lower plenum)) expected to occur during the Emergency Coolant System (ECS) phase of postulated Loss-of-Coolant Accident in a production reactor. The onset of thermal excursion based on the present data is consistent with data gathered in test rigs with flat axial power profiles. The data indicate that wall dryout is primarily a function of liquid superficial velocity. Air entrainment rate was observed to be a strong function of the boundary conditions (primarily flowrate and liquid temperature), but had a minor effect on the power at the onset of thermal excursion for the range of conditions examined. 14 refs., 33 figs., 13 tabs.« less

Evolution of Fine-scale Penumbral Magnetic Structure and Formation of Penumbral Jets

NASA Astrophysics Data System (ADS)

Tiwari, S. K.; Moore, R. L.; Rempel, M.; Winebarger, A. R.

2015-12-01

Sunspot penumbra consists of spines (more vertical field) and penumbral filaments (interspines). Spines are outward extension of umbra. Penumbral filaments are recently found, both in observations and magnetohydrodynamic (MHD) simulations, to be magnetized stretched granule-like convective cells, with strong upflows near the head that continues along the central axis with weakening strength of the flow. Strong downflows are found at the tails of filaments and weak downflows along the sides of it. These lateral downflows often contain opposite polarity magnetic field to that of spines; most strongly near the heads of filaments. In spite of this advancement in understanding of small-scale structure of sunspot penumbra, how the filaments and spines evolve and interact remains uncertain. Penumbral jets, bright, transient features, seen in the chromosphere, are one of several dynamic events in sunspot penumbra. It has been proposed that these penumbral microjets result from component (acute angle) reconnection of the magnetic field in spines with that in interspines and could contribute to transition-region and coronal heating above sunspots. In a recent investigation, it was proposed that the jets form as a result of reconnection between the opposite polarity field at edges of filaments with spine field, and it was found that these jets do not significantly directly heat the corona above sunspots. We discuss how the proposed formation of penumbral jets is integral to the formation mechanism of penumbral filaments and spines, and may explain why penumbral jets are few and far between. We also point out that the generation of the penumbral jets could indirectly drive coronal heating via generation of MHD waves or braiding of the magnetic field.

ANAEROBIC COMPOST CONSTRUCTED WETLANDS SYSTEM TECHNOLOGY - SITE ITER

EPA Science Inventory

In Fall 1994, anaerobic compost wetlands in both upflow and downflow configurations were constructed adjacent to and received drainage from the Burleigh Tunnel, which forms part of the Clear Creek/Central City Superfund site. The systems were operated over a 3 year period. The e...

Signatures of coronal rain observed in the chromosphere of an Active Region Filament

NASA Astrophysics Data System (ADS)

Pillet, V. M.; McAteer, J.

2016-12-01

Using He 10830A spectropolarimetric data from the Tenerife Infrared Polarimeter (TIP) in a rather compact active region neutral line, we observe a persistent chromospheric downflow on both sides of the neutral line that we interpret as the signature of rain from the Corona. The photospheric Si I line also present in this spectral region allows studying the continuation of the chromospheric downflow into the deeper areas dominated by granulation. Full reconstruction of the photospheric and chromospheric vector magnetic field showed that the active region filament was the central, axial, part of a magnetic flux rope. These observations demonstrate the potential of this spectral region to monitor the magnetic field and plasma motions in solar filaments. NMSU and NSO are teaming to start a synoptic program at the DST (Sac Peak) that uses this spectral region to track the evolution of magnetic fields and flows in solar filaments. We briefly present the characteristics of the synoptic program.

Electricity generation in a membrane-less microbial fuel cell with down-flow feeding onto the cathode.

PubMed

Zhu, Feng; Wang, Wancheng; Zhang, Xiaoyan; Tao, Guanhong

2011-08-01

A novel membrane-less microbial fuel cell (MFC) with down-flow feeding was constructed to generate electricity. Wastewater was fed directly onto the cathode which was horizontally installed in the upper part of the MFC. Oxygen could be utilized readily from the air. The concentration of dissolved oxygen in the influent wastewater had little effect on the power generation. A saturation-type relationship was observed between the initial COD and the power generation. The influent flow rate could affect greatly the power density. Fed by the synthetic glucose wastewater with a COD value of 3500 mg/L at a flow rate of 4.0 mL/min, the developed MFC could produce a maximum power density of 37.4 mW/m(2). Its applicability was further evaluated by the treatment of brewery wastewater. The system could be scaled up readily due to its simple configuration, easy operation and relatively high power density. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effect of gravity on colloid transport through water-saturated columns packed with glass beads: modeling and experiments.

PubMed

Chrysikopoulos, Constantinos V; Syngouna, Vasiliki I

2014-06-17

The role of gravitational force on colloid transport in water-saturated columns packed with glass beads was investigated. Transport experiments were performed with colloids (clays: kaolinite KGa-1b, montmorillonite STx-1b). The packed columns were placed in various orientations (horizontal, vertical, and diagonal) and a steady flow rate of Q = 1.5 mL/min was applied in both up-flow and down-flow modes. All experiments were conducted under electrostatically unfavorable conditions. The experimental data were fitted with a newly developed, analytical, one-dimensional, colloid transport model. The effect of gravity is incorporated in the mathematical model by combining the interstitial velocity (advection) with the settling velocity (gravity effect). The results revealed that flow direction influences colloid transport in porous media. The rate of particle deposition was shown to be greater for up-flow than for down-flow direction, suggesting that gravity was a significant driving force for colloid deposition.

Peculiarities of heat transfer at the liquid metal flow in a vertical channel in a coplanar magnetic field

NASA Astrophysics Data System (ADS)

Razuvanov, N. G.; Poddubnyi, I. I.; Kostychev, P. V.

2017-11-01

The research of hydrodynamics and heat transfer at the liquid metal (LM) downward flow and upflow in a vertical duct of a rectangular cross section with a ratio of sides ˜1/3 in a coplanar magnetic field (MF) under conditions of bilateral symmetrical heating is performed. The problem simulates the LM flow in the heat exchange channels for cooling the liquid metal module of the blanket of the thermonuclear reactor (TNR) of the TOKAMAK type. The experiments were carried out on the basis of the mercury magnetohydrodynamic test-bed (MHD) Moscow Power Engineering Institute (MPEI) - Joint Institute for High Temperatures of the Russian Academy of Sciences (JIHT RAS). The probe measurement technique was used in the flow. Profiles of averaged velocity and averaged temperature, as well as profiles of temperature pulsations in the axial planes of the channel cross-section, are obtained; the distribution of the dimensionless wall temperature along the perimeter unfolding of the channel in the section and along the length of the channel. A significant effect of thermogravitational convection (TGC), which leads to unexpected effects, is found. At the downflow in a magnetic field, in some modes, low-frequency pulsations of anomalously high intensity occur.

Stabilization of Softwood-Derived Pyrolysis Oils for Continuous Bio-oil Hydroprocessing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olarte, Mariefel V.; Zacher, Alan H.; Padmaperuma, Asanga B.

The use of fast pyrolysis as a potential renewable liquid transportation fuel alternative to crude oil depends on successful catalytic upgrading to produce a refinery-ready product with oxygen content and qualities (i.e. specific functional group or compound content) that is compatible with the product’s proposed insertion point. Catalytic upgrading of bio-oil requires high temperature and pressure, while similar to crude oil hydrotreating, is not as straightforward for the thermally unstable pyrolysis oil. For years, a two-temperature zone, downflow trickle bed reactor was the state-of-the art for continuous operation. However, pressure excursion due to plug formation still occurred, typically at themore » high temperature transition zone, leading to a process shutdown within 140 h. Recently, a bio-oil pre-treatment process, together with a robust commercial catalyst, was found to be enabling the continuous operation of the two-zone hydroprocessing system. Here, we report the results on pre-treating bio-oil at 413 K and 8.4 MPa of flowing H2 (500 L H2/L bio-oil, 0.5 L bio-oil/L catalyst bed) and the attempts to characterize this oil product to understand the chemistry which enabled the long-term processing of bio-oil.« less

EFFECT OF ANAEROBIOSIS ON FILTER MEDIA POLLUTANT RETENTION

EPA Science Inventory

One of the primary problems with downflow filtration of stormwater runoff is the clogging of the filter prior to the medium's exhaustion of its chemical capacity. Upflow filtration using a siphon control may be a possibility for improving the life of the filters. However, for upf...

Modeling In Situ Bioremediation of Perchlorate-Contaminated Groundwater

DTIC Science & Technology

2007-03-01

PERCHLORATE DETECTIONS UNDER THE UCMR PROGRAM ( BRANDHUBER , 2005...AQUIFER WHERE UPFLOW WELL (U) EXTRACTS AND DOWNFLOW WELL ( D ) INJECTS WATER. ASTERISKS REPRESENT STAGNATION POINTS (CUNNINGHAM ET AL., 2004...1 Figure 1.1 Known Perchlorate Releases and Perchlorate Detections under the UCMR Program ( Brandhuber , 2005) Perchlorate is a

Three-dimensional numerical simulations of local scouring around bridge piers

USDA-ARS?s Scientific Manuscript database

This paper presents a novel numerical method for simulating local scouring around bridge piers using a three-dimensional free-surface RANS turbulent flow model. Strong turbulent fluctuations and the down-flows around the bridge pier are considered important factors in scouring the bed. The turbulent...

Downflow limestone beds for treatment of net-acidic, oxic, iron-laden drainage from a flooded Anthracite Mine, Pennsylvania, USA: 1. Field evaluation

USGS Publications Warehouse

Cravotta, C.A.; Ward, S.J.

2008-01-01

Passive-treatment systems that route acidic mine drainage (AMD) through crushed limestone and/or organic-rich substrates have been used to remove the acidity and metals from various AMD sources, with a wide range of effects. This study evaluates treatment of net-acidic, oxic, iron-laden AMD with limestone alone, and with organic-rich compost layered with the limestone. In the fall of 2003, a treatment system consisting of two parallel, 500-m2 downflow cells followed by a 400-m2 aerobic settling pond and wetland was installed to neutralize the AMD from the Bell Mine, a large source of AMD and baseflow to the Schuylkill River in the Southern Anthracite Coalfield, in east-central Pennsylvania. Each downflow cell consisted of a lower substrate layer of 1,090 metric tons (t) of dolomitic limestone (60 wt% CaCO3) and an upper layer of 300 t of calcitic limestone (95 wt% CaCO3); one of the downflow cells also included a 0.3 m thick layer of mushroom compost over the limestone. AMD with pH of 3.5-4.3, dissolved oxygen of 6.6-9.9 mg/L, iron of 1.9-5.4 mg/L, and aluminum of 0.8-1.9 mg/L flooded each cell to a depth 0.65 m above the treatment substrates, percolated through the substrates to underlying, perforated outflow pipes, and then flowed through the aerobic pond and wetland before discharging to the Schuylkill River. Data on the flow rates and chemistry of the effluent for the treatment system indicated substantial neutralization by the calcitic limestone but only marginal effects from the dolomitic limestone or compost. Because of its higher transmissivity, the treatment cell containing only limestone neutralized greater quantities of acidity than the cell containing compost and limestone. On average, the treatment system removed 62% of the influent acidity, 47% of the dissolved iron, 34% of the dissolved aluminum, and 8% of the dissolved manganese. Prior to treatment of the Bell Discharge, the Schuylkill River immediately below its confluence with the discharge had pH as low as 4.1 and supported few, if any, fish. However, within the first year of treatment, the pH was maintained at values of 5.0 or greater and native brook trout were documented immediately below the treatment system, though not above. ?? 2008 Springer-Verlag.

Combination downflow-upflow vapor-liquid separator

DOEpatents

Kidwell, John H.; Prueter, William P.; Eaton, Andrew M.

1987-03-10

An improved vapor-liquid separator having a vertically disposed conduit for flow of a mixture. A first, second and third plurality of curved arms penetrate and extend within the conduit. A cylindrical member is radially spaced from the conduit forming an annulus therewith and having perforations and a retaining lip at its upper end.

Dynamical Thermal Structure of Super-arcade Downflows in Solar Flares

NASA Astrophysics Data System (ADS)

Chen, Xin; Liu, Rui; Deng, Na; Wang, Haimin

2015-04-01

Super­-arcade downflows (SADs) have been frequently observed during the gradual phase of flares near the limb. In coronal emission lines sensitive to flaring plasmas, they appear as tadpole-like dark voids against the bright fan-shape “haze” above the well-defined flare arcade and flow toward the arcade. We carefully studied several selected SADs from two flare events using data observed by Solar Dynamic Observatory / Atmospheric Imaging Assembly and calculated their differential emission measures (DEMs) as well as the DEM-weighted temperature. Our analysis shows that SADs are associated with a substantially decreased DEMs, by 1~3 order of magnitude, compared with the surrounding plasma. None of the SADs indicate DEM solutions above 20 MK, which implies that SADs are indeed density depletion rather than very hot plasma. This depression in DEMs rapidly recovers as SADs pass through, generally in a few minutes. In addition, we found that SADs in one event appear spatio-temporally associated with the formation of postflare loops. These results are examined against models and numerical simulations.

Active region flows

NASA Technical Reports Server (NTRS)

Foukal, Peter

1987-01-01

A wide range of observations has shown that active region phenomena in the photospheric, chromospheric and coronal temperature regimes are dynamical in nature. At the photosphere, recent observations of full line profiles place an upper limit of about + or - 20/msec on any downflows at supergranule cell edges. Observations of the full Stokes 5 profiles in the network show no evidence for downflows in magnetic flux tubes. In the area of chromospheric dynamics, several models were put forward recently to reproduce the observed behavior of spicules. However, it is pointed out that these adiabatic models do not include the powerful radiative dissipation which tend to damp out the large amplitude disturbances that produce the spicular acceleration in the models. In the corona, loop flows along field lines clearly transport mass and energy at rates important for the dynamics of these structures. However, advances in understanding the heating and mass balance of the loop structures seem to require new kinds of observations. Some results are presented using a remote sensing diagnostic of the intensity and orientation of macroscopic plasma electric fields predicted by models of reconnective heating and also wave heating.

Magnetic shuffling of coronal downdrafts

NASA Astrophysics Data System (ADS)

Petralia, A.; Reale, F.; Orlando, S.

2017-02-01

Context. Channelled fragmented downflows are ubiquitous in magnetized atmospheres, and have recently been addressed based on an observation after a solar eruption. Aims: We study the possible back-effect of the magnetic field on the propagation of confined flows. Methods: We compared two 3D magnetohydrodynamic simulations of dense supersonic plasma blobs that fall down along a coronal magnetic flux tube. In one, the blobs move strictly along the field lines; in the other, the initial velocity of the blobs is not perfectly aligned with the magnetic field and the field is weaker. Results: The aligned blobs remain compact while flowing along the tube, with the generated shocks. The misaligned blobs are disrupted and merge through the chaotic shuffling of the field lines. They are structured into thinner filaments. Alfvén wave fronts are generated together with shocks ahead of the dense moving front. Conclusions: Downflowing plasma fragments can be chaotically and efficiently mixed if their motion is misaligned with field lines, with broad implications for disk accretion in protostars, coronal eruptions, and rain, for example. Movies associated to Figs. 2 and 3 are available at http://www.aanda.org

Effects of disintegration on anaerobic degradation of sewage excess sludge in downflow stationary fixed film digesters.

PubMed

Engelhart, M; Krüger, M; Kopp, J; Dichtl, N

2000-01-01

The effects of mechanical disintegration on anaerobic digestibility of sewage excess sludge in downflow stationary fixed film (DSFF) digesters were investigated on laboratory scale. Mechanical pretreatment using a high pressure homogenizer led to significantly enhanced concentrations of soluble proteins and carbohydrates in the feed sludge. Using DSFF digesters with two different tubular plastic media as support material it was shown that a stable digestion process could be achieved at hydraulic retention times (HRT) down to 5 days. Compared to conventional digesters at 10 d and 15 d HRT respectively, the degradation of volatile solids was enhanced up to 25%, also resulting in a higher specific biogas production. Further investigations on degradation of soluble proteins and carbohydrates showed that a slowly degradable fraction of carbohydrates was released via disintegration. Using the distribution of chain length and the concentrations of volatile fatty acids as process parameters, the dependability on the HRT and the degree of disintegration (the release of soluble COD) predominated the effects of specific surface area of the support media.

Velocity Measurements for a Solar Active Region Fan Loop from Hinode/EIS Observations

NASA Astrophysics Data System (ADS)

Young, P. R.; O'Dwyer, B.; Mason, H. E.

2012-01-01

The velocity pattern of a fan loop structure within a solar active region over the temperature range 0.15-1.5 MK is derived using data from the EUV Imaging Spectrometer (EIS) on board the Hinode satellite. The loop is aligned toward the observer's line of sight and shows downflows (redshifts) of around 15 km s-1 up to a temperature of 0.8 MK, but for temperatures of 1.0 MK and above the measured velocity shifts are consistent with no net flow. This velocity result applies over a projected spatial distance of 9 Mm and demonstrates that the cooler, redshifted plasma is physically disconnected from the hotter, stationary plasma. A scenario in which the fan loops consist of at least two groups of "strands"—one cooler and downflowing, the other hotter and stationary—is suggested. The cooler strands may represent a later evolutionary stage of the hotter strands. A density diagnostic of Mg VII was used to show that the electron density at around 0.8 MK falls from 3.2 × 109 cm-3 at the loop base, to 5.0 × 108 cm-3 at a projected height of 15 Mm. A filling factor of 0.2 is found at temperatures close to the formation temperature of Mg VII (0.8 MK), confirming that the cooler, downflowing plasma occupies only a fraction of the apparent loop volume. The fan loop is rooted within a so-called outflow region that displays low intensity and blueshifts of up to 25 km s-1 in Fe XII λ195.12 (formed at 1.5 MK), in contrast to the loop's redshifts of 15 km s-1 at 0.8 MK. A new technique for obtaining an absolute wavelength calibration for the EIS instrument is presented and an instrumental effect, possibly related to a distorted point-spread function, that affects velocity measurements is identified.

VELOCITY MEASUREMENTS FOR A SOLAR ACTIVE REGION FAN LOOP FROM HINODE/EIS OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, P. R.; O'Dwyer, B.; Mason, H. E.

2012-01-01

The velocity pattern of a fan loop structure within a solar active region over the temperature range 0.15-1.5 MK is derived using data from the EUV Imaging Spectrometer (EIS) on board the Hinode satellite. The loop is aligned toward the observer's line of sight and shows downflows (redshifts) of around 15 km s{sup -1} up to a temperature of 0.8 MK, but for temperatures of 1.0 MK and above the measured velocity shifts are consistent with no net flow. This velocity result applies over a projected spatial distance of 9 Mm and demonstrates that the cooler, redshifted plasma is physicallymore » disconnected from the hotter, stationary plasma. A scenario in which the fan loops consist of at least two groups of 'strands'-one cooler and downflowing, the other hotter and stationary-is suggested. The cooler strands may represent a later evolutionary stage of the hotter strands. A density diagnostic of Mg VII was used to show that the electron density at around 0.8 MK falls from 3.2 Multiplication-Sign 10{sup 9} cm{sup -3} at the loop base, to 5.0 Multiplication-Sign 10{sup 8} cm{sup -3} at a projected height of 15 Mm. A filling factor of 0.2 is found at temperatures close to the formation temperature of Mg VII (0.8 MK), confirming that the cooler, downflowing plasma occupies only a fraction of the apparent loop volume. The fan loop is rooted within a so-called outflow region that displays low intensity and blueshifts of up to 25 km s{sup -1} in Fe XII {lambda}195.12 (formed at 1.5 MK), in contrast to the loop's redshifts of 15 km s{sup -1} at 0.8 MK. A new technique for obtaining an absolute wavelength calibration for the EIS instrument is presented and an instrumental effect, possibly related to a distorted point-spread function, that affects velocity measurements is identified.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Xiaolei; Rink, Nancy

This report presents the results of the research and development conducted on an Advanced Hydrogasification Process (AHP) conceived and developed by Arizona Public Service Company (APS) under U.S. Department of Energy (DOE) contract: DE-FC26-06NT42759 for Substitute Natural Gas (SNG) production from western coal. A double-wall (i.e., a hydrogasification contained within a pressure shell) down-flow hydrogasification reactor was designed, engineered, constructed, commissioned and operated by APS, Phoenix, AZ. The reactor is ASME-certified under Section VIII with a rating of 1150 pounds per square inch gage (psig) maximum allowable working pressure at 1950 degrees Fahrenheit (°F). The reaction zone had a 1.75more » inch inner diameter and 13 feet length. The initial testing of a sub-bituminous coal demonstrated ~ 50% carbon conversion and ~10% methane yield in the product gas under 1625°F, 1000 psig pressure, with a 11 seconds (s) residence time, and 0.4 hydrogen-to-coal mass ratio. Liquid by-products mainly contained Benzene, Toluene, Xylene (BTX) and tar. Char collected from the bottom of the reactor had 9000-British thermal units per pound (Btu/lb) heating value. A three-dimensional (3D) computational fluid dynamic model simulation of the hydrodynamics around the reactor head was utilized to design the nozzles for injecting the hydrogen into the gasifier to optimize gas-solid mixing to achieve improved carbon conversion. The report also presents the evaluation of using algae for carbon dioxide (CO 2) management and biofuel production. Nannochloropsis, Selenastrum and Scenedesmus were determined to be the best algae strains for the project purpose and were studied in an outdoor system which included a 6-meter (6M) radius cultivator with a total surface area of 113 square meters (m 2) and a total culture volume between 10,000 to 15,000 liters (L); a CO 2 on-demand feeding system; an on-line data collection system for temperature, pH, Photosynthetically Activate Radiation (PAR) and dissolved oxygen (DO); and a ~2 gallons per minute (gpm) algae culture dewatering system. Among the three algae strains, Scenedesmus showed the most tolerance to temperature and irradiance conditions in Phoenix and the best self-settling characteristics. Experimental findings and operational strategies determined through these tests guided the operation of the algae cultivation system for the scale-up study. Effect of power plant flue gas, especially heavy metals, on algae growth and biomass adsorption were evaluated as well.« less

Integrating powdered activated carbon into wastewater tertiary filter for micro-pollutant removal.

PubMed

Hu, Jingyi; Aarts, Annelies; Shang, Ran; Heijman, Bas; Rietveld, Luuk

2016-07-15

Integrating powdered activated carbon (PAC) into wastewater tertiary treatment is a promising technology to reduce organic micro-pollutant (OMP) discharge into the receiving waters. To take advantage of the existing tertiary filter, PAC was pre-embedded inside the filter bed acting as a fixed-bed adsorber. The pre-embedding (i.e. immobilization) of PAC was realized by direct dosing a PAC solution on the filter top, which was then promoted to penetrate into the filter media by a down-flow of tap water. In order to examine the effectiveness of this PAC pre-embedded filter towards OMP removal, batch adsorption tests, representing PAC contact reactor (with the same PAC mass-to-treated water volume ratio as in the PAC pre-embedded filter) were performed as references. Moreover, as a conventional dosing option, PAC was dosed continuously with the filter influent (i.e. the wastewater secondary effluent with the investigated OMPs). Comparative results confirmed a higher OMP removal efficiency associated with the PAC pre-embedded filter, as compared to the batch system with a practical PAC residence time. Furthermore, over a filtration period of 10 h (approximating a realistic filtration cycle for tertiary filters), the continuous dosing approach resulted in less OMP removal. Therefore, it was concluded that the pre-embedding approach can be preferentially considered when integrating PAC into the wastewater tertiary treatment for OMP elimination. Copyright © 2016 Elsevier Ltd. All rights reserved.

Spatial Inhomogeneity of Kinetic and Magnetic Dissipations in Thermal Convection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hotta, H.

We investigate the inhomogeneity of kinetic and magnetic dissipations in thermal convection using high-resolution calculations. In statistically steady turbulence, the injected and dissipated energies are balanced. This means that a large amount of energy is continuously converted into internal energy via dissipation. As in thermal convection, downflows are colder than upflows and the inhomogeneity of the dissipation potentially changes the convection structure. Our investigation of the inhomogeneity of the dissipation shows the following. (1) More dissipation is seen around the bottom of the calculation domain, and this tendency is promoted with the magnetic field. (2) The dissipation in the downflowmore » is much larger than that in the upflow. The dissipation in the downflow is more than 80% of the total at maximum. This tendency is also promoted with the magnetic field. (3) Although 2D probability density functions of the kinetic and magnetic dissipations versus the vertical velocity are similar, the kinetic and magnetic dissipations are not well correlated. Our result suggests that the spatial inhomogeneity of the dissipation is significant and should be considered when modeling a small-scale strong magnetic field generated with an efficient small-scale dynamo for low-resolution calculations.« less

Βiocolloid and colloid transport through water-saturated columns packed with glass beads: Effect of gravity

NASA Astrophysics Data System (ADS)

Chrysikopoulos, C. V.; Syngouna, V. I.

2013-12-01

The role of gravitational force on biocolloid and colloid transport in water-saturated columns packed with glass beads was investigated. Transport experiments were performed with biocolloids (bacteriophages: ΦΧ174, MS2) and colloids (clays: kaolinite KGa-1b, montmorillonite STx-1b). The packed columns were placed in various orientations (horizontal, vertical, and diagonal) and a steady flow rate of Q=1.5 mL/min was applied in both up-flow and down-flow modes. All experiments were conducted under electrostatically unfavorable conditions. The experimental data were fitted with a newly developed, analytical, one dimensional, colloid transport model, accounting for gravity effects. The results revealed that flow direction has a significant influence on particle deposition. The rate of particle deposition was shown to be greater for up-flow than for down-flow direction, suggesting that gravity was a significant driving force for biocolloid and colloid deposition. Schematic illustration of a packed column with up-flow velocity having orientation (-i) with respect to gravity. The gravity vector components are: g(i)= g(-z) sinβ i, and g(-j)= -g(-z) cosβ j. Experimental setup showing the various column arrangements: (a) horizontal, (b) diagonal, and (c) vertical.

Study of cluster behavior in the riser of CFB by the DSMC method

NASA Astrophysics Data System (ADS)

Liu, H. P.; Liu, D. Y.; Liu, H.

2010-03-01

The flow behaviors of clusters in the riser of a two-dimensional (2D) circulating fluidized bed was numerically studied based on the Euler-Lagrangian approach. Gas turbulence was modeled by means of Large Eddy Simulation (LES). Particle collision was modeled by means of the direct simulation Monte Carlo (DSMC) method. Clusters' hydrodynamic characteristics are obtained using a cluster identification method proposed by sharrma et al. (2000). The descending clusters near the wall region and the up- and down-flowing clusters in the core were studied separately due to their different flow behaviors. The effects of superficial gas velocity on the cluster behavior were analyzed. Simulated results showed that near wall clusters flow downward and the descent velocity is about -45 cm/s. The occurrence frequency of the up-flowing cluster is higher than that of down-flowing cluster in the core of riser. With the increase of superficial gas velocity, the solid concentration and occurrence frequency of clusters decrease, while the cluster axial velocity increase. Simulated results were in agreement with experimental data. The stochastic method used in present paper is feasible for predicting the cluster flow behavior in CFBs.

Testing the performance of microbiological safety cabinets used in microbiology laboratories in South Korea.

PubMed

Hwang, S H; Yi, T W; Cho, K H; Lee, I M; Yoon, C S

2011-09-01

To test a performance of the microbiological safety cabinets (MSCs) according to the type of MSCs in microbial laboratories. Tests were carried out to assess the performance of 31 MSCs in 14 different facilities, including six different biological test laboratories in six hospitals and eight different laboratories in three universities. The following tests were performed on the MSCs: the downflow test, intake velocity test, high-efficiency particulate air filter leak test and the airflow smoke pattern test. These performance tests were carried out in accordance with the standard procedures. Only 23% of Class II A1 (8), A2 (19) and unknown MSCs (4) passed these performance tests. The main reasons for the failure of MSCs were inappropriate intake velocity (65%), leakage in the HEPA filter sealing (50%), unbalanced airflow smoke pattern in the cabinets (39%) and inappropriate downflow (27%). This study showed that routine checks of MSCs are important to detect and strengthen the weak spots that frequently develop, as observed during the evaluation of the MSCs of various institutions. Routine evaluation and maintenance of MSCs are critical for optimizing performance. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

Optimization of operating parameters of hybrid vertical down-flow constructed wetland systems for domestic sewerage treatment.

PubMed

Huang, Zhujian; Zhang, Xianning; Cui, Lihua; Yu, Guangwei

2016-09-15

In this work, three hybrid vertical down-flow constructed wetland (HVDF-CW) systems with different compound substrates were fed with domestic sewage and their pollutants removal performance under different hydraulic loading and step-feeding ratio was investigated. The results showed that the hydraulic loading and step-feeding ratio were two crucial factors determining the removal efficiency of most pollutants, while substrate types only significantly affected the removal of COD and NH4(+)-N. Generally, the lower the hydraulic loading, the better removal efficiency of all contaminants, except for TN. By contrast, the increase of step-feeding ratio would slightly reduce the removal rate of ammonium and TP but obviously promoted the TN removal. Therefore, the optimal operation of this CWs could be achieved with low hydraulic loading combined with 50% of step-feeding ratio when TN removal is the priority, whereas medium or low hydraulic loading without step-feeding would be suitable when TN removal is not taken into consideration. The obtained results in this study can provide us with a guideline for design and optimization of hybrid vertical flow constructed wetland systems to improve the pollutants removal from domestic sewage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Observation and numerical modeling of chromospheric evaporation during the impulsive phase of a solar flare

DOE Office of Scientific and Technical Information (OSTI.GOV)

Imada, Shinsuke, E-mail: shinimada@stelab.nagoya-u.ac.jp; Murakami, Izumi, E-mail: murakami.izumi@nifs.ac.jp; Department of Fusion Science, SOKENDAI

2015-10-15

We have studied the chromospheric evaporation flow during the impulsive phase of the flare by using the Hinode/EUV Imaging Spectrometer observation and 1D hydrodynamic numerical simulation coupled to the time-dependent ionization. The observation clearly shows that the strong redshift can be observed at the base of the flaring loop only during the impulsive phase. We performed two different numerical simulations to reproduce the strong downflows in FeXII and FeXV during the impulsive phase. By changing the thermal conduction coefficient, we carried out the numerical calculation of chromospheric evaporation in the thermal conduction dominant regime (conductivity coefficient κ{sub 0} = classical value) andmore » the enthalpy flux dominant regime (κ{sub 0} = 0.1 × classical value). The chromospheric evaporation calculation in the enthalpy flux dominant regime could reproduce the strong redshift at the base of the flare during the impulsive phase. This result might indicate that the thermal conduction can be strongly suppressed in some cases of flare. We also find that time-dependent ionization effect is important to reproduce the strong downflows in Fe XII and Fe XV.« less

Serial lantern-shaped draft tube enhanced flashing light effect for improving CO2 fixation with microalgae in a gas-lift circumflux column photobioreactor.

PubMed

Ye, Qing; Cheng, Jun; Guo, Wangbiao; Xu, Junchen; Li, Ke; Zhou, Junhu

2018-05-01

A novel serial lantern-shaped draft tube (LDT) that generates vortices is proposed to increase radial velocity between dark and light regions for improving CO 2 fixation with microalgae in a gas-lift circumflux column (GCC) photobioreactor. Clockwise vortices are generated in the downflow outerloop of the GCC photobioreactor with LDT. Radial velocity was improved from 1.50 to 4.35 × 10 -2  m/s, thereby decreased liquid cycle period between dark and light regions by 1.9 times. Mixing time decreased by 21%, and mass transfer coefficient increased by 26% with LDT. Liquid radial velocity in the downflow outerloop and mass transfer coefficient in the GCC photobioreactor both first increased and then decreased when single-lantern height was increased. Peak CO 2 fixation rate increased from 0.62 to 0.87 g/L/d, microalgal biomass yield increased by 50%. Removal efficiencies of pollutants (chemical oxygen demand, ammonium, tilmicosin, and ethinylestradiol) in wastewater were 62-90% with microalgae growth in GCC photobioreactor with LDT. Copyright © 2018 Elsevier Ltd. All rights reserved.

Small-Scale Activity Above the Penumbra of a Fast-Rotating Sunspot

NASA Astrophysics Data System (ADS)

Bharti, L.; Quintero Noda, C.; Rakesh, S.; Sobha, B.; Pandya, A.; Joshi, C.

2018-03-01

High-resolution observations of small-scale activity above the filamentary structure of a fast-rotating sunspot of NOAA Active Region 10930 are presented. The penumbral filament that intrudes into the umbra shows a central dark core and substructures. It almost approached another end of the umbra, like a light bridge. The chromospheric Ca ii H images show many jet-like structures with a bright leading edge above it. These bright jets move across the filament tips and show coordinated up and down motions. Transition region images also show brightening at the same location above the intrusion. Coronal 195 Å images suggest that one end of the bright coronal loop footpoints resides in this structure. The intrusion has opposite polarity with respect to the umbra. Strong downflows are observed at the edges along the length of the intrusion where the opposite-polarity field is enhanced. We also observe a counter-Evershed flow in the filamentary structure that also displays brightening and energy dissipation in the upper atmosphere. This scenario suggests that the jets and brightenings are caused by low-altitude reconnection driven by opposite-polarity fields and convective downflows above such structures.

Significance of dissolved methane in effluents of anaerobically treated low strength wastewater and potential for recovery as an energy product: A review.

PubMed

Crone, Brian C; Garland, Jay L; Sorial, George A; Vane, Leland M

2016-11-01

The need for energy efficient Domestic Wastewater (DWW) treatment is increasing annually with population growth and expanding global energy demand. Anaerobic treatment of low strength DWW produces methane which can be used to as an energy product. Temperature sensitivity, low removal efficiencies (Chemical Oxygen Demand (COD), Suspended Solids (SS), and Nutrients), alkalinity demand, and potential greenhouse gas (GHG) emissions have limited its application to warmer climates. Although well designed anaerobic Membrane Bioreactors (AnMBRs) are able to effectively treat DWW at psychrophilic temperatures (10-30 °C), lower temperatures increase methane solubility leading to increased energy losses in the form of dissolved methane in the effluent. Estimates of dissolved methane losses are typically based on concentrations calculated using Henry's Law but advection limitations can lead to supersaturation of methane between 1.34 and 6.9 times equilibrium concentrations and 11-100% of generated methane being lost in the effluent. In well mixed systems such as AnMBRs which use biogas sparging to control membrane fouling, actual concentrations approach equilibrium values. Non-porous membranes have been used to recover up to 92.6% of dissolved methane and well suited for degassing effluents of Upflow Anaerobic Sludge Blanket (UASB) reactors which have considerable solids and organic contents and can cause pore wetting and clogging in microporous membrane modules. Microporous membranes can recover up to 98.9% of dissolved methane in AnMBR effluents which have low COD and SS concentrations. Sequential Down-flow Hanging Sponge (DHS) reactors have been used to recover between 57 and 88% of dissolved methane from Upflow Anaerobic Sludge Blanket (UASB) reactor effluent at concentrations of greater than 30% and oxidize the rest for a 99% removal of total dissolved methane. They can also remove 90% of suspended solids and COD in UASB effluents and produce a high quality effluent. In situ degassing can increase process stability, COD removal, biomass retention, and headspace methane concentrations. A model for estimating energy consumption associated with membrane-based dissolved methane recovery predicts that recovered dissolved and headspace methane may provide all the energy required for operation of an anaerobic system treating DWW at psychrophilic temperatures. Copyright © 2016 Elsevier Ltd. All rights reserved.

Observational Evidence of Shallow Origins for the Magnetic Fields of Solar Cycles - a review

NASA Astrophysics Data System (ADS)

Martin, Sara F.

2018-05-01

Observational evidence for the origin of active region magnetic fields has been sought from published information on extended solar cycles, statistical distributions of active regions and ephemeral regions, helioseismology results, positional relationships to supergranules, and fine-scale magnetic structure of active regions and their sunspots during their growth. Statistical distributions of areas of ephemeral and active regions blend together to reveal a single power law. The shape of the size distribution in latitude of all active regions is independent of time during the solar cycle, yielding further evidence that active regions of all sizes belong to the same population. Elementary bipoles, identified also by other names, appear to be the building blocks of active regions; sunspots form from elementary bipoles and are therefore deduced to develop from the photosphere downward, consistent with helioseismic detection of downflows to 3-4 Mm below sunspots as well as long-observed downflows from chromospheric/coronal arch filaments into sunspots from their earliest appearance. Time-distance helioseismology has been effective in revealing flows related to sunspots to depths of 20 Mm. Ring diagram analysis shows a statistically significant preference for upflows to precede major active region emergence and downflows after flux emergence but both are often observed together or sometimes not detected. From deep-focus helioseismic techniques for seeking magnetic flux below the photosphere prior major active regions, there is evidence of acoustic travel-time perturbation signatures rising in the limited range of depths of 42-75 Mm but these have not been verified or found at more shallow depths by helioseismic holographic techniques. The development of active regions from clusters of elementary bipoles appears to be the same irrespective of how much flux an active region eventually develops. This property would be consistent with the magnetic fields of large active regions being generated in the same way and close the same depth as small active regions in a shallow zone below the photosphere. All evidence considered together, understanding the origins of the magnetic fields of solar cycles boils down to learning how and where elementary bipoles are generated beneath the photosphere.

Biofiltration of gasoline and ethanol-amended gasoline vapors.

PubMed

Soares, Marlene; Woiciechowski, Adenise L; Kozliak, Evguenii I; Paca, Jan; Soccol, Carlos R

2012-01-01

Assuming the projected increase in use of ethanol as a biofuel, the current study was conducted to compare the biofiltration efficiencies for plain and 25% ethanol-containing gasoline. Two biofilters were operated in a downflow mode for 7 months, one of them being compost-based whereas the other using a synthetic packing material, granulated tire rubber, inoculated with gasoline-degrading microorganisms. Inlet concentrations measured as total hydrocarbon (TH) ranged from 1.9 to 5.8 g m(-3) at a constant empty bed retention time of 6.84 min. Contrary to the expectations based on microbiological considerations, ethanol-amended gasoline was more readily biodegraded than plain hydrocarbons, with the respective steady state elimination capacities of 26-43 and 14-18 gTH m(-3) h(-1) for the compost biofilter. The efficiency of both biofilters significantly declined upon the application of higher loads of plain gasoline, yet immediately recovering when switched back to ethanol-blended gasoline. The unexpected effect of ethanol in promoting gasoline biodegradation was explained by increasing hydrocarbon partitioning into the aqueous phase, with mass transfer being rate limiting for the bulk of components. The tire rubber biofilter, after a long acclimation, surpassed the compost biofilter in performance, presumably due to the 'buffering' effect of this packing material increasing the accessibility of gasoline hydrocarbons to the biofilm. With improved substrate mass transfer, biodegradable hydrocarbons were removed in the tire rubber biofilter's first reactor stage, with most of the remaining poorly degradable smaller-size hydrocarbons being degraded in the second stage.

Effect of hydraulic retention time on the performance of down-flow hanging sponge system treating grey wastewater.

PubMed

Tawfik, Ahmed; Wahab, Rifaat Abdel; Al-Asmer, Azza; Matary, Fatma

2011-08-01

Grey wastewater (GW) treatment via down-flow hanging sponge (DHS) system was the subject of the study. The reactor was operated at different hydraulic retention times (HRTs) of 11.7, 5.8 and 2.9 h, corresponding to organic loading rates (OLRs) of 1.9, 3.6 and 6.8 kgCOD/m3 day, respectively. The results obtained revealed that decreasing the HRT from 11.7 to 2.9 h negatively affected on the performance of the DHS system. COD(total), COD(soluble), COD(particulate) and detergent removal efficiency were reduced from 96 ± 2.4 to 90 ± 2.3%, from 83 ± 10 to 69 ± 8%, from 98 ± 2 to 94 ± 3% and from 96 ± 12 to 88 ± 6.9%, respectively. However, the removal efficiency of the distinguished COD fractions and detergent remained unaffected when decreasing the HRT from 11.7 to 5.8 h. The DHS system provided a removal efficiency of 95 ± 1% for COD(total), 79 ± 8% for COD(soluble), 98 ± 2 for COD(particulate) and 94.7% for detergent at an HRT of 5.8 h. Based on these results, it is recommended to operate such a system at an HRT of 5.8 h and OLR not exceeding 3.6 kgCOD/m3 day for producing an effluent quality complying for reuse in unrestricted irrigation purposes. The removal of TKj-N and nitrification efficiency in the DHS system was significantly affected by increasing the OLR from 1.9 to 3.6 kgCOD/m3 day and from 3.6 to 6.8 kgCOD/m3 day. At an OLR of 1.9 kgCOD/m3 day, the DHS system removed 80 ± 12% of TKj-N and 91 ± 22% of ammonia which is significantly higher than that at an OLR of 3.6 (58.5 ± 13%) and 6.8 kgCOD/m3 day (26.8 ± 16%). Similar results were recorded for the removal of total coliform (TC), viz., the efficiencies dropped for TC from 99.8 ± 0.2 to 99.4 ± 0.8% and from 99.4 ± 0.8 to 90.0 ± 7.6%, respectively. DHS profile results showed that the major part of COD was removed in the upper portion of the system while the nitrification process was taken place in the lower part of the DHS system at OLR of 1.9 kgCOD/m3 day and HRT of 11.7 h.

Solar Flare Termination Shock and Synthetic Emission Line Profiles of the Fe xxi 1354.08 Å Line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Lijia; Li, Gang; Reeves, Kathy

Solar flares are among the most energetic phenomena that occur in the solar system. In the standard solar flare model, a fast mode shock, often referred to as the flare termination shock (TS), can exist above the loop-top source of hard X-ray emissions. The existence of the TS has been recently related to spectral hardening of a flare’s hard X-ray spectra at energies >300 keV. Observations of the Fe xxi 1354.08 Å line during solar flares by the Interface Region Imaging Spectrograph ( IRIS ) spacecraft have found significant redshifts with >100 km s{sup −1}, which is consistent with amore » reconnection downflow. The ability to detect such a redshift with IRIS suggests that one may be able to use IRIS observations to identify flare TSs. Using a magnetohydrodynamic simulation to model magnetic reconnection of a solar flare and assuming the existence of a TS in the downflow of the reconnection plasma, we model the synthetic emission of the Fe xxi 1354.08 line in this work. We show that the existence of the TS in the solar flare may manifest itself in the Fe xxi 1354.08 Å line.« less

Active Region Formation and Subsurface Structure

NASA Astrophysics Data System (ADS)

Stein, F.; Nordlund, Robert A.

2016-10-01

We present results from emerging magnetic flux simulations showing how several different active regions form and their very different subsurface structures. The simulations assumed an infinite sheet of uniform, untwisted, horizontal field advected into the computational domain by inflows at a depth of 20 Mm. Results from two different horizontal field strengths, 1 and 5 kG, will be presented. Convective up and down flows buckle the horizontal field into Omega and U loops. Upflows and magnetic buoyancy carry the field toward the surface, while fast downflows pin down the field. Small (granular) convective motions, near the surface, shred the emerging field into fine filaments that emerge as the observed "pepper and salt" pattern. The large (supergranular) motions, at depth, keep the overall loop structure intact, so that as the overall omega-loop emerges through the surface the opposite polarity fields counter-stream into large unipolar flux concentrations producing first pores which then coalesce into spots. These tend to be located over the supergranular downflow lanes near the bottom of the domain. The pores and spots exhibit a great variety of subsurface field structures - from monolithic but twisted bundles to intertwined separate spaghetti sturctures. We will show movies of the surface evolution of the field and emergent continuum intensity and of the subsurface evolution of the magnetic field lines.

Solar Flare Termination shock and the Synthetic Fe XXI 1354.08 Å line

NASA Astrophysics Data System (ADS)

Guo, L.; Li, G.; Reeves, K.; Raymond, J. C.

2017-12-01

Solar flares are one of the most energetic phenomena occurred in the solar system. In the standard solar flare model, a fast mode shock, which is often referred to as the flare termination shock (TS), can exist above the loop-top source of hard X-ray emissions. The existence of the termination shock has been recently related to spectral hardening of flare hard X-ray spectrum at energies > 300 keV. Observations of the Fe XXI 1354.08 Å line during solar flares by the IRIS spacecraft have found significant redshift with >100 km/s, which is consistent with a reconnection downflow. The ability to identify such a redshift by IRIS is made possible by IRIS's high time resolution, high spatial resolution, high sensitivity and cadence spectral observations. The ability to identify such a redshift by IRIS suggests that one may be able to use IRIS observations to identify flare termination shocks. Using a MHD simulation to model magnetic reconnection of a solar flare and assuming the existence of a TS in the downflow of the reconnection plasma, we model the synthetic emission of the Fe XXI 1354.08 Å line in this work. We show that the existence of the TS in the solar flare may manifest itself from the Fe XXI 1354.08 Å line.

Removal of diclofenac and sulfamethoxazole from synthetic municipal waste water in microcosm downflow constructed wetlands: Start-up results.

PubMed

Nowrotek, Monika; Sochacki, Adam; Felis, Ewa; Miksch, Korneliusz

2016-01-01

The objectives of this study were to investigate the start-up removal of pharmaceutical compounds diclofenac and sulfamethoxazole in microcosm downflow constructed wetlands and their effect on the performance of the studied constructed wetlands, and also to assess the effect of plants on the removal of these compounds. The experimental system that was used in this 86-day experiment consisted of 24 columns filled up to 70 cm with predominantly sandy material. Four types of columns were used (six replicates) depending on the presence of plants (Phalaris arundinacea L. var. picta L.) and the presence of pharmaceutical compounds in the influent. The influent was synthetic municipal waste water to which a mixture of 5 mg/L of diclofenac and 5 mg/L of sulfamethoxazole was added. The observed removal of diclofenac was moderate (approx. 50%) and the removal of sulfamethoxazole was relatively low (24-30%). It was found that the removal of diclofenac and sulfamethoxazole was not affected by the vegetation. The presence of diclofenac and sulfamethoxazole in the influent had significant effect on the effluent concentration of N-NO3 and the water loss in the columns, which in both cases were lower than in the control columns. The scope for further research was discussed.

Analysis of up-flow aerated biological activated carbon filter technology in drinking water treatment.

PubMed

Lu, Shaoming; Liu, Jincui; Li, Shaowen; Biney, Elizabeth

2013-01-01

Problems have been found in the traditional post-positioned down-flow biological activated carbon filter (DBACF), such as microorganism leakage and low biodegradability. A pilot test was carried out to place a BACF between the sediment tank and the sand filter; a new technology of dual media up-flow aerated biological activated carbon filter (UBACF) was developed. Results showed that in terms of the new process, the up-flow mode was better than the down-flow. Compared with the DBACF, the problem of microorganism leakage could be well resolved with the UBACF process by adding disinfectant before the sand filtration, and a similar adsorption effect could be obtained. For the tested raw water, the COD(Mn) and NH3-N removal rate was 54.6% and 85.0%, respectively, similar to the waterworks with the DBACF process. The UBACF greatly enhanced oxygen supply capability and mass transfer rate via aeration, and the NH3-N removal ability was significantly improved from 1.5 mg/L to more than 3 mg/L. Influent to the UBACF with higher turbidity could be coped with through the primary filtration of the ceramisite layer combined with fluid-bed technology, which gave the carbon bed a low-turbidity environment of less than 1.0 NTU. The backwashing parameters and carbon abrasion rate of the two processes were almost the same.

Reconnection Outflows in the Extended Corona and Magnetotail

NASA Astrophysics Data System (ADS)

Savage, Sabrina; Kobelski, Adam

2017-08-01

Observational signatures of reconnection have been studied extensively in the lower corona for decades, successfully providing insight into energy release mechanisms in the region above post-flare arcade loops and below 1.5 solar radii. During large eruptive events, however, energy release continues to occur well beyond the presence of reconnection signatures at these low heights. Supra-arcade downflows (SADs) and downflowing loops (SADLs) are particularly useful measures of continual reconnection in the corona as they may indicate the presence and path of retracting post-reconnection loops. SADs and SADLs have been observed for days beyond the passage of corona mass ejections through the SOHO/LASCO field of view and for nearly a week after an eruption on 14 October 2014. The association of these features with magnetic reconnection increases the significance of understanding their genesis. SADs have been interpreted as wakes behind newly reconnected and outflowing loops (SADLs). Models have shown the plausibility of this interpretation, though this interpretation has not yet been fully accepted. We will present a preliminary study of complementary observations of magnetic reconnection detected via in situ instruments in the magnetosphere. These observations, provided by five THEMIS spacecraft, reveal similar structures and conditions to those related to SADs. We compare data from multiple SADs and dipolarization fronts to test the similarity between these plasma regimes, strongly favoring the interpretation of SADs as instabilities trailing retracting loops. We will also use these observations to strengthen the case for the development of an EUV wide-field coronal imager.

Application of novel Modified Biological Aerated Filter (MBAF) as a promising post-treatment for water reuse: Modification in configuration and backwashing process.

PubMed

Nikoonahad, Ali; Ghaneian, Mohammad Taghi; Mahvi, Amir Hossein; Ehrampoush, Mohammad Hassan; Ebrahimi, Ali Asghar; Lotfi, Mohammad Hassan; Salamehnejad, Sima

2017-12-01

Biological Aerated Filter (BAF) reactors due to their plentiful biomass, high shockability, high efficiency, good filtration, availability and lack of need for large land areas, are enjoying from great importance in advanced wastewater treatment. Therefore, in this study, Polystyrene Coated by Sand (PCS) was produced as a novel media and its application in a modified down-flow BAF structure for advanced wastewater treatment was assessed in two steps. In step one, the backwash effluent did not return to the system, while in step two backwash effluent returned to increase the water reuse efficiency. The backwash process was also studied through three methods of Top Backwashing (TB), Bottom Backwashing (BB), as well as Top and Bottom Backwashing Simultaneously (TBBS). The results showed that return of backwash effluent had no significant effect on the BAF effluent quality. In the second step similar to the first one with slight differences, the residual average concentrations of TSS, BOD 5 , and COD at the effluent were about 2.5, 8.2, and 25.5 mg/L, respectively. Additionally, in step two, the mean volume of disposal sludge/volume of treated water (v ds /v tw ) decreased a large extent to about 0.088%. In other words, the water reuse has increased to more than 99.91%. The backwash time in methods of TB and BB were 65 and 35 min, respectively; however, it decreased in TBBS methods to 25 min. The concentrations of most effluent parameters in this system are in concordance with the 2012 EPA Agriculture Standards, even for irrigation of Non-processed agricultural crops and livestock water consumption. Copyright © 2017 Elsevier Ltd. All rights reserved.

Combustion characterization of carbonized RDF, Joint Venture Task No. 7. Topical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

1995-04-30

The overall objective of this research program was to demonstrate EnerTech's and the Energy & Environmental Research Center's (EERC) process of slurry carbonization for producing homogeneous, pumpable titels from refuse-derived fuel (RDF) with continuous pilot plant facilities, and to characterize flue gas and ash emissions from combustion of the carbonizd RDF slurry fuel. Please note that "Wet Thermal Oxidation" is EnerTech's trademark mme for combustion of the carbonized RDF slurry fuel. Carbonized RDF slurry fuels were produced with the EERC'S 7.5-tpd (wet basis) pilot plant facility. A hose diaphragm pump pressurized a 7- lo-wt% feed RDF slurry, with a viscositymore » of 500 cP, to approximately 2500 psig. The pressurized RDF slurry was heated by indirect heat exchangers to between 5850 -626°F, and its temperature and pressure was maintained in a downflow reactor. The carbonized slurry was flashed, concentrated in a filter press, and ground in an attritor. During operation of the pilot plant, samples of the feed RDF slurry, carbonization gas, condensate, carbonized solids, and filtrate were taken and analyzed. Pilot-scale slurry carbonization experiments with RDF produced a homogeneous pumpable slurry fuel with a higher heating value (HHV) of 3,000-6,600 Btu/lb (as-received basis), at a viscosity of 500 CP at 100 Hz decreasing, and ambient temperature. Greater-heating-value slurry fuels were produced at higher slurry carbonization temperatures. During slurry carbonization, polyvinyl chloride (PVC) plastics in the feed RDF also decompose to form hydrochloric acid and salts. Pilot-scale slurty carbonization experiments extracted 82-94% of the feed RDF chlorine content as chloride salts. Higher carbonization temperatures and higher alkali additions to the feed slurry produced a higher chlorine extraction.« less

ON THE CAUSE OF SUPRA-ARCADE DOWNFLOWS IN SOLAR FLARES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cassak, P. A.; Shepherd, L. S.; Drake, J. F.

2013-09-20

A model of supra-arcade downflows (SADs), dark low density regions also known as tadpoles that propagate sunward during solar flares, is presented. It is argued that the regions of low density are flow channels carved by sunward-directed outflow jets from reconnection. The solar corona is stratified, so the flare site is populated by a lower density plasma than that in the underlying arcade. As the jets penetrate the arcade, they carve out regions of depleted plasma density which appear as SADs. The present interpretation differs from previous models in that reconnection is localized in space but not in time. Reconnectionmore » is continuous in time to explain why SADs are not filled in from behind as they would if they were caused by isolated descending flux tubes or the wakes behind them due to temporally bursty reconnection. Reconnection is localized in space because outflow jets in standard two-dimensional reconnection models expand in the normal (inflow) direction with distance from the reconnection site, which would not produce thin SADs as seen in observations. On the contrary, outflow jets in spatially localized three-dimensional reconnection with an out-of-plane (guide) magnetic field expand primarily in the out-of-plane direction and remain collimated in the normal direction, which is consistent with observed SADs being thin. Two-dimensional proof-of-principle simulations of reconnection with an out-of-plane (guide) magnetic field confirm the creation of SAD-like depletion regions and the necessity of density stratification. Three-dimensional simulations confirm that localized reconnection remains collimated.« less

RE-INTERPRETATION OF SUPRA-ARCADE DOWNFLOWS IN SOLAR FLARES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Savage, Sabrina L.; McKenzie, David E.; Reeves, Katharine K.

Following the eruption of a filament from a flaring active region, sunward-flowing voids are often seen above developing post-eruption arcades. First discovered using the soft X-ray telescope aboard Yohkoh, these supra-arcade downflows (SADs) are now an expected observation of extreme ultra-violet and soft X-ray coronal imagers and spectrographs (e.g, TRACE, SOHO/SUMER, Hinode/XRT, SDO/AIA). Observations made prior to the operation of AIA suggested that these plasma voids (which are seen in contrast to bright, high-temperature plasma associated with current sheets) are the cross-sections of evacuated flux tubes retracting from reconnection sites high in the corona. The high temperature imaging afforded bymore » AIA's 131, 94, and 193 Angstrom-Sign channels coupled with the fast temporal cadence allows for unprecedented scrutiny of the voids. For a flare occurring on 2011 October 22, we provide evidence suggesting that SADs, instead of being the cross-sections of relatively large, evacuated flux tubes, are actually wakes (i.e., trailing regions of low density) created by the retraction of much thinner tubes. This re-interpretation is a significant shift in the fundamental understanding of SADs, as the features once thought to be identifiable as the shrinking loops themselves now appear to be 'side effects' of the passage of the loops through the supra-arcade plasma. In light of the fact that previous measurements have attributed to the shrinking loops characteristics that may instead belong to their wakes, we discuss the implications of this new interpretation on previous parameter estimations and on reconnection theory.« less

An Investigation of the Sources of Earth-directed Solar Wind during Carrington Rotation 2053

NASA Astrophysics Data System (ADS)

Fazakerley, A. N.; Harra, L. K.; van Driel-Gesztelyi, L.

2016-06-01

In this work we analyze multiple sources of solar wind through a full Carrington Rotation (CR 2053) by analyzing the solar data through spectroscopic observations of the plasma upflow regions and the in situ data of the wind itself. Following earlier authors, we link solar and in situ observations by a combination of ballistic backmapping and potential-field source-surface modeling. We find three sources of fast solar wind that are low-latitude coronal holes. The coronal holes do not produce a steady fast wind, but rather a wind with rapid fluctuations. The coronal spectroscopic data from Hinode’s Extreme Ultraviolet Imaging Spectrometer show a mixture of upflow and downflow regions highlighting the complexity of the coronal hole, with the upflows being dominant. There is a mix of open and multi-scale closed magnetic fields in this region whose (interchange) reconnections are consistent with the up- and downflows they generate being viewed through an optically thin corona, and with the strahl directions and freeze-in temperatures found in in situ data. At the boundary of slow and fast wind streams there are three short periods of enhanced-velocity solar wind, which we term intermediate based on their in situ characteristics. These are related to active regions that are located beside coronal holes. The active regions have different magnetic configurations, from bipolar through tripolar to quadrupolar, and we discuss the mechanisms to produce this intermediate wind, and the important role that the open field of coronal holes adjacent to closed-field active regions plays in the process.

THE NAKED EMERGENCE OF SOLAR ACTIVE REGIONS OBSERVED WITH SDO/HMI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Centeno, Rebecca

We take advantage of the HMI/SDO instrument to study the naked emergence of active regions (ARs) from the first imprints of the magnetic field on the solar surface. To this end, we followed the first 24 hr in the life of two rather isolated ARs that appeared on the surface when they were about to cross the central meridian. We analyze the correlations between Doppler velocities and the orientation of the vector magnetic field, consistent finding that the horizontal fields connecting the main polarities are dragged to the surface by relatively strong upflows and are associated with elongated granulation thatmore » is, on average, brighter than its surroundings. The main magnetic footpoints, on the other hand, are dominated by vertical fields and downflowing plasma. The appearance of moving dipolar features (MDFs, of opposite polarity to that of the AR) in between the main footpoints is a rather common occurrence once the AR reaches a certain size. The buoyancy of the fields is insufficient to lift up the magnetic arcade as a whole. Instead, weighted by the plasma that it carries, the field is pinned down to the photosphere at several places in between the main footpoints, giving life to the MDFs and enabling channels of downflowing plasma. MDF poles tend to drift toward each other, merge and disappear. This is likely to be the signature of a reconnection process in the dipped field lines, which relieves some of the weight allowing the magnetic arcade to finally rise beyond the detection layer of the Helioseismic and Magnetic Imager spectral line.« less

Velocity Characteristics of Evaporated Plasma using Hinode/EIS

NASA Technical Reports Server (NTRS)

Milligan, Ryan O.; Dennis, Brian R.

2009-01-01

This paper presents a detailed study of chromospheric evaporation using the EUV Imaging Spectrometer (EIS) onboard Hinode in conjunction with HXR observat,ions from RHESSI. The advanced capabilities of EIS were used to measure Doppler shifts in 15 emission lines covering the temperature range T=0.05-16 MK during the impulsive phase of a C-class flare on 2007 December 14. Blueshifts indicative of the evaporated material were observed in six emission lines from Fe XIV-XXIV (2-16 MK). Upflow velocity was found to scale with temperature as v(sub up) (kilometers per second) approximately equal to 5-17 T (MK). Although the hottest emission lines, Fe XXIII and Fe XXIV, exhibited upflows of greater than 200 kilometers per second, their line profiles were found to be dominated by a stationary component in stark contrast to the predictions of the standard flare model. Emission from O VI-Fe XIII lines (0.5-1.5 MK) was found to be redshifted by v(sub down) (kilometers per second) approximately equal to 60-17 T (MK) and was interpreted as the downward-moving 'plug' characteristic of explosive evaporation. These downflows occur at temperatures significantly higher than previously expected. Both upflows and downflows were spatially and temporally correlated with HXR emission observed by RHESSI that provided the properties of the electron beam deemed to be the driver of the evaporation. The energy contained in the electron beam was found to be greater than or equal to 10(sup 11) ergs per square centimeter per second consistent with the value required to drive explosive chromospheric evaporation from hydrodynamic simulations.

IRIS Observations of Coronal Rain and Prominences: Return Flows of the Chromosphere-Corona Mass Cycle

NASA Astrophysics Data System (ADS)

Liu, Wei; Berger, Thomas; Antolin, Patrick; Schrijver, Karel

2014-06-01

It has recently been recognized that a mass cycle (e.g., Berger et al. 2011; McIntosh et al. 2012) between the hot, tenuous solar corona and the cool, dense chromosphere underneath it plays an important role in the mass budget and dynamic evolution of the solar atmosphere. Although the corona ultimately loses mass through the solar wind and coronal mass ejections, a fraction of its mass returns to the chromosphere in coronal rain, downflows of prominences, and other as-yet unidentified processes. We present here analysis of joint observations of IRIS, SDO/AIA, and Hinode/SOT of such phenomena. By utilizing the wide temperature coverage (logT: 4 - 7) provided by these instruments combined, we track the coronal cooling sequence (e.g., Schrijver 2001; Liu et al. 2012; Berger et al. 2012) leading to the formation of such material at transition region or chromospheric temperatures (logT: 4 - 5) in the million-degree corona. We compare the cooling times with those expected from the radiative cooling instability. We also measure the kinematics and densities of such downflows and infer their mass fluxes, which are compared to the upward mass fluxes into the corona, e.g., those associated with spicules and flux emergence. Special attention is paid to coronal rain formed near cusp-shaped portions of coronal loops, funnel-shaped prominences at dips of coronal loops, and their respective magnetic environments. With the information about where and when such catastrophic cooling events take place, we discuss the implications for the enigmatic coronal heating mechanisms (e.g., Antolin et al. 2010).

Thermodynamic Properties of the Inverse Evershed Flow at Its Downflow Points

NASA Astrophysics Data System (ADS)

Choudhary, D. P.; Beck, C.

2018-06-01

We used spectropolarimetric observations of a sunspot in the active region NOAA 11809 in the Ca II line at 854.2 nm taken with the SpectroPolarimeter for Optical and Infrared Regions at the Dunn Solar Telescope to infer thermodynamic parameters along 100 super-penumbral fibrils that harbor the inverse Evershed flow. The fibrils were identified in line-of-sight (LOS) velocity and line–core intensity maps. The chromospheric LOS velocity abruptly decreases from 3 to 15 km s‑1 to zero at the inner footpoints of the fibrils that are located from the mid penumbra to about 1.4 spot radii. The spectra often show multiple absorption components, indicating spatially or vertically unresolved structures. Synthetic spectra with a 100% fill factor of a flow channel in the upper atmosphere yield strongly asymmetric profiles but no multiple separate components. The line–core intensity always peaks slightly closer to the umbra than the LOS velocity. Using the CAlcium Inversion using a Spectral ARchive code, we find that the fibrils make an angle of 30°–60° to the local vertical away from the umbra. The temperature near the downflow points is enhanced by 200 K at log τ ∼ -2 and up to 2000 K at log τ ∼ (‑6) compared to the quiet Sun, without any signature in the low photosphere. Our results are consistent with a critical, i.e., sonic, or supersonic siphon flow along super-penumbral flux tubes in which accelerating plasma abruptly attains subcritical velocity through a standing shock in or near the penumbra.

Flowmeter for determining average rate of flow of liquid in a conduit

DOEpatents

Kennerly, J.M.; Lindner, G.M.; Rowe, J.C.

1981-04-30

This invention is a compact, precise, and relatively simple device for use in determining the average rate of flow of a liquid through a conduit. The liquid may be turbulent and contain bubbles of gas. In a preferred embodiment, the flowmeter includes an electrical circuit and a flow vessel which is connected as a segment of the conduit conveying the liquid. The vessel is provided with a valved outlet and is partitioned by a vertical baffle into coaxial chambers whose upper regions are vented to permit the escape of gas. The inner chamber receives turbulent downflowing liquid from the conduit and is sized to operate at a lower pressure than the conduit, thus promoting evolution of gas from the liquid. Lower zones of the two chambers are interconnected so that the downflowing liquid establishes liquid levels in both chambers. The liquid level in the outer chamber is comparatively calm, being to a large extent isolated from the turbulence in the inner chamber once the liquid in the outer chamber has risen above the liquid-introduction zone for that chamber. Lower and upper probes are provided in the outer chamber for sensing the liquid level therein at points above its liquid-introduction zone. An electrical circuit is connected to the probes to display the time required for the liquid level in the outer chamber to successively contact the lower and upper probes. The average rate of flow through the conduit can be determined from the above-mentioned time and the vessel volume filled by the liquid during that time.

Flowmeter for determining average rate of flow of liquid in a conduit

DOEpatents

Kennerly, John M.; Lindner, Gordon M.; Rowe, John C.

1982-01-01

This invention is a compact, precise, and relatively simple device for use in determining the average rate of flow of a liquid through a conduit. The liquid may be turbulent and contain bubbles of gas. In a preferred embodiment, the flowmeter includes an electrical circuit and a flow vessel which is connected as a segment of the conduit conveying the liquid. The vessel is provided with a valved outlet and is partitioned by a vertical baffle into coaxial chambers whose upper regions are vented to permit the escape of gas. The inner chamber receives turbulent downflowing liquid from the conduit and is sized to operate at a lower pressure than the conduit, thus promoting evolution of gas from the liquid. Lower zones of the two chambers are interconnected so that the downflowing liquid establishes liquid levels in both chambers. The liquid level in the outer chamber is comparatively calm, being to a large extent isolated from the turbulence in the inner chamber once the liquid in the outer chamber has risen above the liquid-introduction zone for that chamber. Lower and upper probes are provided in the outer chamber for sensing the liquid level therein at points above its liquid-introduction zone. An electrical circuit is connected to the probes to display the time required for the liquid level in the outer chamber to successively contact the lower and upper probes. The average rate of flow through the conduit can be determined from the above-mentioned time and the vessel volume filled by the liquid during that time.

SUMER observations detecting downward propagating waves in the solar transition region

NASA Technical Reports Server (NTRS)

Wikstol, O.; Judge, P. G.; Hansteen, V.; Wilhelm, K.; Schuehle, U.; Moran, T.

1997-01-01

The O IV density sensitive emission lines around 1400 A, using the solar ultraviolet measurement of emitted radiation (SUMER) instrument onboard the Solar and Heliospheric Observatory (SOHO), are reported on. The data for the quiet sun, obtained close to the disk center and the solar limb were acquired. A systematic correlation between a density sensitive emission line ratio and Doppler shift across the same emission profiles was obtained. The correlation is such that the density is higher in the downflowing than in the upflowing plasma. The results are in good agreement with the simulations of downward propagating waves.

Measuring the seeds of ion outflow: auroral sounding rocket observations of low-altitude ion heating and circulation

DOE PAGES

Fernandes, P. A.; Lynch, K. A.; Zettergren, M.; ...

2016-01-25

Here, we present an analysis of in situ measurements from the MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) nightside auroral sounding rocket with comparisons to a multifluid ionospheric model. MICA made observations at altitudes below 325 km of the thermal ion kinetic particle distributions that are the origins of ion outflow. Late flight, in the vicinity of an auroral arc, we observe frictional processes controlling the ion temperature. Upflow of these cold ions is attributed to either the ambipolar field resulting from the heated electrons or possibly to ion-neutral collisions. We measure E →xB → convection away from the arcmore » (poleward) and downflows of hundreds of m s -1 poleward of this arc, indicating small-scale low-altitude plasma circulation. In the early flight we observe DC electromagnetic Poynting flux and associated ELF wave activity influencing the thermal ion temperature in regions of Alfvénic aurora. We observe enhanced, anisotropic ion temperatures which we conjecture are caused by transverse heating by wave-particle interactions (WPI) even at these low altitudes. Throughout this region we observe several hundred m s -1 upflow of the bulk thermal ions colocated with WPI; however, the mirror force is negligible at these low energies; thus, the upflow is attributed to ambipolar fields (or possibly neutral upwelling drivers). Moreover, the low-altitude MICA observations serve to inform future ionospheric modeling and simulations of (a) the need to consider the effects of heating by WPI at altitudes lower than previously considered viable and (b) the occurrence of structured and localized upflows/downflows below where higher-altitude heating rocesses are expected.« less

Thermodynamics of supra-arcade downflows in solar flares

NASA Astrophysics Data System (ADS)

Chen, Xin; Liu, Rui; Deng, Na; Wang, Haimin

2017-10-01

Context. Supra-arcade downflows (SADs) have been frequently observed during the gradual phase of solar flares near the limb. In coronal emission lines sensitive to flaring plasmas, they appear as tadpole-like dark voids against the diffuse fan-shaped "haze" above, flowing toward the well-defined flare arcade. Aims: We aim to investigate the evolution of SADs' thermal properties, and to shed light on the formation mechanism and physical processes of SADs. Methods: We carefully studied several selected SADs from two flare events and calculated their differential emission measures (DEMs) as well as DEM-weighted temperatures using data obtained by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamic Observatory. Results: Our analysis shows that SADs are associated with a substantial decrease in DEM above 4 MK, which is 1-3 orders of magnitude smaller than the surrounding haze as well as the region before or after the passage of SADs, but comparable to the quiet corona. There is no evidence for the presence of the SAD-associated hot plasma (>20 MK) in the AIA data, and this decrease in DEM does not cause any significant change in the DEM distribution as well as the DEM-weighted temperature, which supports this idea that SADs are density depletion. This depression in DEM rapidly recovers in the wake of the SADs studied, generally within a few minutes, suggesting that they are discrete features. In addition, we found that SADs in one event are spatio-temporally associated with the successive formation of post-flare loops along the flare arcade. Movies associated to Figs. A.1 and A.2 are available at http://www.aanda.org

Contagious Coronal Heating from Recurring Emergence of Magnetic Flux

NASA Astrophysics Data System (ADS)

Moore, R. L.; Falconer, D. A.; Sterling, A. C.

2002-01-01

For each of six old bipolar active regions, we present and interpret Yohkoh/SXT and SOHO/MDI observations of the development, over several days, of enhanced coronal heating in and around the old bipole in response to new magnetic flux emergence within the old bipole. The observations show: 1. In each active region, new flux emerges in the equatorward side of the old bipole, around a lone remaining leading sunspot and/or on the equatorward end of the neutral line of the old bipole. 2. The emerging field is marked by intense internal coronal heating, and enhanced coronal heating occurs in extended loops stemming from the emergence site. 3. In five of the six cases, a "rooster tail" of coronal loops in the poleward extent of the old bipole also brightens in response to the flux emergence. 4. There are episodes of enhanced coronal heating in surrounding magnetic fields that are contiguous with the old bipole but are not directly connected to the emerging field. From these observations, we suggest that the accommodation of localized newly emerged flux within an old active region entails far reaching adjustments in the 3D magnetic field throughout the active region and in surrounding fields in which the active region is embedded, and that these adjustments produce the extensive enhanced coronal heating. We Also Note That The Reason For The recurrence of flux emergence in old active regions may be that active-region flux tends to emerge in giant-cell convection downflows. If so, the poleward "rooster tail" is a coronal flag of a long-lasting downflow in the convection zone. This work was funded by NASA's Office of Space Science through the Solar Physics Supporting Research and Technology Program and the Sun-Earth Connection Guest Investigator Program.

Low-altitude ion heating with downflowing and upflowing ions

NASA Astrophysics Data System (ADS)

Shen, Y.; Knudsen, D. J.; Burchill, J. K.; Howarth, A. D.; Yau, A. W.; James, G.; Miles, D.; Cogger, L. L.; Perry, G. W.

2017-12-01

Mechanisms that energize ions at the initial stage of ion upflow are still not well understood. We statistically investigate ionospheric ion energization and field-aligned motion at very low altitudes (330-730 km) using simultaneous plasma, magnetic field, wave electric field and optical data from the e-POP satellite. The high-time-resolution (10 ms) dataset enables us to study the micro-structures of ion heating and field-aligned ion motion. The ion temperature and field-aligned bulk flow velocity are derived from 2-D ion distribution functions measured by the SEI instrument. From March 2015 to March 2016, we've found 17 orbits (in total 24 ion heating periods) with clear ion heating signatures passing across the dayside cleft or the nightside auroral regions. Most of these events have consistent ion heating and flow velocity characteristics observed from both the SEI and IRM instruments. The perpendicular ion temperature goes up to 4.5 eV within a 2 km-wide region in some cases, in which the Radio Receiver Instrument (RRI) sees broadband extremely low frequency (BBELF) waves, demonstrating significant wave-ion heating down to as low as 350 km. The e-POP Fast Auroral Imager (FAI) and Magnetic Field (MGF) instruments show that many events are associated with active aurora and are within downward current regions. Contrary to what would be expected from mirror-force acceleration of heated ions, the majority of these heating events (17 out of 24) are associated with the core ion downflow rather than upflow. These statistical results provide us with new sights into ion heating and field-aligned flow processes at very low altitudes.

Supra Arcade Downflows in the Earth's Magnetotail

NASA Astrophysics Data System (ADS)

Kobelski, A.; Savage, S. L.; Malaspina, D.

2017-12-01

Pinpointing the location of a single reconnection event in the corona is difficult due to observational constraints, although features directly resulting from this rapid reconfiguration of the field lines can be observed beyond the reconnection site. One set of such features are outflows in the form of post-reconnection loops, which have been linked to observations of supra-arcade downflows (SADs). SADs appear as sunward-traveling, density-depleted regions above flare arcades that develop during long duration eruptions. The limitations of remote sensing methods inherently results in ambiguities regarding the interpretation of SAD formation. Of particular interest is how these features are related to post-reconnection retracting magnetic field lines. In planetary magnetospheres, similar events to solar flares occur in the form of substorms, where reconnection in the anti-sunward tail of the magnetosphere causes field lines to retract toward the planet. Using data from the Time History of Events and Macroscopic Interactions during Substorms (THEMIS), we compare one particular aspect of substorms, dipolarization fronts, to SADs. Dipolarization fronts are observed as rapid but temporary changes in the magnetic field of the magnetotail plasma sheet into a more potential-like dipolar shape. These dipolarization fronts are believed to be retracting post-reconnection field lines. We combine data sets to show that the while the densities and magnetic fields involved vary greatly between the regimes, the plasma βs and Alfvén speeds are similar. These similarities allow direct comparison between the retracting field lines and their accompanying wakes of rarified plasma observed with THEMIS around the Earth to the observed morphological density depletions visible with XRT and AIA on the Sun. These results are an important source of feedback for models of coronal current sheets.

Fluid flow in the resurgent dome of Long Valley Caldera: Implications from thermal data and deep electrical sounding

USGS Publications Warehouse

Pribnow, D.F.C.; Schutze, C.; Hurter, S.J.; Flechsig, C.; Sass, J.H.

2003-01-01

Temperatures of 100??C are measured at 3 km depth in a well located on the resurgent dome in the center of Long Valley Caldera, California, despite an assumed >800??C magma chamber at 6-8 km depth. Local downflow of cold meteoric water as a process for cooling the resurgent dome is ruled out by a Pecle??t-number analysis of temperature logs. These analyses reveal zones with fluid circulation at the upper and lower boundaries of the Bishop Tuff, and an upflow zone in the metasedimentary rocks. Vertical Darcy velocities range from 10 to 70 cm a-1. A 21-km-long geoelectrical profile across the caldera provides resistivity values to the order of 100 to >103 ??m down to a depth of 6 km, as well as variations of self-potential. Interpretation of the electrical data with respect to hydrothermal fluid movement confirms that there is no downflow beneath the resurgent dome. To explain the unexpectedly low temperatures in the resurgent dome, we challenge the common view that the caldera as a whole is a regime of high temperatures and the resurgent dome is a local cold anomaly. Instead, we suggest that the caldera was cooled to normal thermal conditions by vigorous hydrothermal activity in the past, and that a present-day hot water flow system is responsible for local hot anomalies, such as Hot Creek and the area of the Casa Diablo geothermal power plant. The source of hot water has been associated with recent shallow intrusions into the West Moat. The focus of planning for future power plants should be to locate this present-day flow system instead of relying on heat from the old magma chamber. ?? 2003 Elsevier B.V. All rights reserved.

Contagious Coronal Heating from Recurring Emergence of Magnetic Flux

NASA Technical Reports Server (NTRS)

Moore, Ronald L.; Falconer, David; Sterling, Alphonse; Whitaker, Ann F. (Technical Monitor)

2001-01-01

For each of six old bipolar active regions, we present and interpret Yohkoh/SXT and SOHO/MDI observations of the development, over several days, of enhanced coronal heating in and around the old bipole in response to new magnetic flux emerge= within the old bipole. The observations show: 1. In each active region, new flux emerges in the equatorward side of the old bipole, around a lone remaining leading sunspot and/or on the equatorward end of the neutral line of the old bipole. 2. The emerging field is marked by intense internal coronal heating, and enhanced coronal heating occurs in extended loops stemming from the emergence site. 3. In five of the six cases, a "rooster tail" of coronal loops in the poleward extent of the old bipole also brightens in response to the flux emergence. 4. There are episodes of enhanced coronal heating in surrounding magnetic fields that are contiguous with the old bipole but are not directly connected to the emerging field. From these observations, we suggest that the accommodation of localized newly emerged flux within an old active region entails far reaching adjustments in the 3D magnetic field throughout the active region and in surrounding fields in which the active region is embedded, and that these adjustments produce the extensive enhanced coronal heating. We also note that the reason for the recurrence of flux emergence in old active regions may be that active region flux tends to emerge in giant-cell convection downflows. If so, the poleward "rooster tail" is a coronal flag of a long-lasting downflow in the convection zone. This work was funded by NASA's Office of Space Science through the Solar Physics Supporting Research and Technology Program and the Sun-Earth Connection Guest Investigator Program.

Effect of switching off unidirectional downflow systems of operating theaters during prolonged inactivity on the period before the operating theater can safely be used.

PubMed

Traversari, A A L; Bottenheft, C; van Heumen, S P M; Goedhart, C A; Vos, M C

2017-02-01

Switching off air handling systems in operating theaters during periods of prolonged inactivity (eg, nights, weekends) can produce a substantial reduction of energy expenditure. However, little evidence is available regarding the effect of switching off the air handling system during periods of prolonged inactivity on the air quality in operating theaters during operational periods. The aim of this study is to determine the amount of time needed after restarting the ventilation system to return to a stable situation, with air quality at least equal to the situation before switching off the system. Measurements were performed in 3 operating theaters, all of them equipped with a unidirectional downflow (UDF) system. Measurements (particle counts of emitted particles with a particle size ≥0.5 µm) were taken during the start-up of the ventilation system to determine when prespecified degrees of protection were achieved. Temperature readings were taken to determine when a stable temperature difference between the periphery and the protected area was reached, signifying achievement of a stable condition. After starting up the system, the protected area achieved the required degrees of protection within 20 minutes (95% upper confidence limit). A stable temperature difference was achieved within 23 minutes (95% upper confidence limit). Both findings lie well within the period of 25 minutes normally required for preparations before the start of surgical procedures. Switching off the ventilation system during prolonged inactivity (during the night and weekend) has no negative effect on the air quality in UDF operating theaters during normal operational hours. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Abundance Variations and Flows in Plage Regions Observed with CDS/SOHO

NASA Astrophysics Data System (ADS)

Rank, G.; Bagalá, L. G.; Czaykowska, A.; Haerendel, G.

1999-10-01

We present results from CDS/SOHO observations of the spotless active region NOAA-8208, obtained on 28th April 1998 near disk center. MDI images show a bipolar magnetic configuration. The regions of enhanced He I emission correspond to the areas with strong magnetic flux and also with bright plage areas seen in Ca II and H-alpha images. A high correlation is found between intensity maps of the transition region lines He I (logTmax = 4.3), O III (logTmax = 5.0), and O V (logTmax = 5.4). The line-of-sight velocities of He I reveal a strong downflow in the plage areas. Further, the line-of-sight velocities of He I, O III, and O V are well correlated, showing that the downflow pattern exists up to temperatures of about 0.25 MK. At higher temperatures (Mg VIII at logTmax = 5.8) this flow is not detected, suggesting that material streams into the plage region from sideways in the high transition region. Maps of the electron density in the transition region have been constructed from several line ratios yielding densities of about 9.0 cm-3 in the plage regions, about dex 0.5 cm-3 higher compared to the surrounding. To study the spatial variation of the first ionization potential (FIP) effect, the abundance ratio has been mapped for the ion ratio MgVI/NeVI. The ratio is highly variable on spatial scales down to a few arcsec from photospheric values to enhancements of a factor of 10. The strongest FIP enhancements are not correlated with transition region line emission, but are found outside of the plage regions. Some areas of strong FIP enhancement appear stretched and elongated, suggesting that the material is confined in loop-like structures.

Fluid flow in the resurgent dome of Long Valley Caldera: implications from thermal data and deep electrical sounding

NASA Astrophysics Data System (ADS)

Pribnow, Daniel F. C.; Schütze, Claudia; Hurter, Suzanne J.; Flechsig, Christina; Sass, John H.

2003-10-01

Temperatures of 100°C are measured at 3 km depth in a well located on the resurgent dome in the center of Long Valley Caldera, California, despite an assumed >800°C magma chamber at 6-8 km depth. Local downflow of cold meteoric water as a process for cooling the resurgent dome is ruled out by a Peclét-number analysis of temperature logs. These analyses reveal zones with fluid circulation at the upper and lower boundaries of the Bishop Tuff, and an upflow zone in the metasedimentary rocks. Vertical Darcy velocities range from 10 to 70 cm a -1. A 21-km-long geoelectrical profile across the caldera provides resistivity values to the order of 10 0 to >10 3 Ωm down to a depth of 6 km, as well as variations of self-potential. Interpretation of the electrical data with respect to hydrothermal fluid movement confirms that there is no downflow beneath the resurgent dome. To explain the unexpectedly low temperatures in the resurgent dome, we challenge the common view that the caldera as a whole is a regime of high temperatures and the resurgent dome is a local cold anomaly. Instead, we suggest that the caldera was cooled to normal thermal conditions by vigorous hydrothermal activity in the past, and that a present-day hot water flow system is responsible for local hot anomalies, such as Hot Creek and the area of the Casa Diablo geothermal power plant. The source of hot water has been associated with recent shallow intrusions into the West Moat. The focus of planning for future power plants should be to locate this present-day flow system instead of relying on heat from the old magma chamber.

Magnetic structure of an activated filament in a flaring active region

NASA Astrophysics Data System (ADS)

Sasso, C.; Lagg, A.; Solanki, S. K.

2014-01-01

Aims: While the magnetic field in quiescent prominences has been widely investigated, less is known about the field in activated prominences. We report observational results on the magnetic field structure of an activated filament in a flaring active region. In particular, we studied its magnetic structure and line-of-sight flows during its early activated phase, shortly before it displayed signs of rotation. Methods: We inverted the Stokes profiles of the chromospheric He i 10 830 Å triplet and the photospheric Si i 10 827 Å line observed in this filament by the Vacuum Tower Telescope on Tenerife. Using these inversion results, we present and interpret the first maps of the velocity and magnetic field obtained in an activated filament, both in the photosphere and the chromosphere. Results: Up to five different magnetic components are found in the chromospheric layers of the filament, while outside the filament a single component is sufficient to reproduce the observations. Magnetic components displaying an upflow are preferentially located towards the centre of the filament, while the downflows are concentrated along its periphery. Moreover, the upflowing gas is associated with an opposite-polarity magnetic configuration with respect to the photosphere, while the downflowing gas is associated with a same-polarity configuration. Conclusions: The activated filament has a very complex structure. Nonetheless, it is compatible with a flux rope, albeit a distorted one, in the normal configuration. The observations are best explained by a rising flux rope in which part of the filament material is still stably stored (upflowing material, rising with the field), while the rest is no longer stably stored and flows down along the field lines. The movie is available in electronic form at http://www.aanda.org

Supra Arcade Downflows in the Earth's Magnetotail

NASA Technical Reports Server (NTRS)

Kobelski, Adam; Savage, Sabrina L.; Malaspina, David M.

2017-01-01

Pinpointing the location of a single reconnection event in the corona is difficult due to observational constraints, although features directly resulting from this rapid reconfiguration of the field lines can be observed beyond the reconnection site. One set of such features are outflows in the form of post-reconnection loops, which have been linked to observations of supra-arcade downflows (SADs). SADs appear as sunward-traveling, density-depleted regions above flare arcades that develop during long duration eruptions. The limitations of remote sensing methods inherently results in ambiguities regarding the interpretation of SAD formation. Of particular interest is how these features are related to post-reconnection retracting magnetic field lines. In planetary magnetospheres, similar events to solar flares occur in the form of substorms, where reconnection in the anti-sunward tail of the magnetosphere causes field lines to retract toward the planet. Using data from the Time History of Events and Macroscopic Interactions during Substorms (THEMIS), we compare one particular aspect of substorms, dipolarization fronts, to SADs. Dipolarization fronts are observed as rapid but temporary changes in the magnetic field of the magnetotail plasma sheet into a more potential-like dipolar shape. These dipolarization fronts are believed to be retracting post-reconnection field lines. We combine data sets to show that the while the densities and magnetic fields involved vary greatly between the regimes, the plasma betas and Alfvén speeds are similar. These similarities allow direct comparison between the retracting field lines and their accompanying wakes of rarified plasma observed with THEMIS around the Earth to the observed morphological density depletions visible with XRT and AIA on the Sun. These results are an important source of feedback for models of coronal current sheets.

Measuring the seeds of ion outflow: auroral sounding rocket observations of low-altitude ion heating and circulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernandes, P. A.; Lynch, K. A.; Zettergren, M.

Here, we present an analysis of in situ measurements from the MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) nightside auroral sounding rocket with comparisons to a multifluid ionospheric model. MICA made observations at altitudes below 325 km of the thermal ion kinetic particle distributions that are the origins of ion outflow. Late flight, in the vicinity of an auroral arc, we observe frictional processes controlling the ion temperature. Upflow of these cold ions is attributed to either the ambipolar field resulting from the heated electrons or possibly to ion-neutral collisions. We measure E →xB → convection away from the arcmore » (poleward) and downflows of hundreds of m s -1 poleward of this arc, indicating small-scale low-altitude plasma circulation. In the early flight we observe DC electromagnetic Poynting flux and associated ELF wave activity influencing the thermal ion temperature in regions of Alfvénic aurora. We observe enhanced, anisotropic ion temperatures which we conjecture are caused by transverse heating by wave-particle interactions (WPI) even at these low altitudes. Throughout this region we observe several hundred m s -1 upflow of the bulk thermal ions colocated with WPI; however, the mirror force is negligible at these low energies; thus, the upflow is attributed to ambipolar fields (or possibly neutral upwelling drivers). Moreover, the low-altitude MICA observations serve to inform future ionospheric modeling and simulations of (a) the need to consider the effects of heating by WPI at altitudes lower than previously considered viable and (b) the occurrence of structured and localized upflows/downflows below where higher-altitude heating rocesses are expected.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhattacharyya, D.; Turton, R.; Zitney, S.

In this presentation, development of a plant-wide dynamic model of an advanced Integrated Gasification Combined Cycle (IGCC) plant with CO2 capture will be discussed. The IGCC reference plant generates 640 MWe of net power using Illinois No.6 coal as the feed. The plant includes an entrained, downflow, General Electric Energy (GEE) gasifier with a radiant syngas cooler (RSC), a two-stage water gas shift (WGS) conversion process, and two advanced 'F' class combustion turbines partially integrated with an elevated-pressure air separation unit (ASU). A subcritical steam cycle is considered for heat recovery steam generation. Syngas is selectively cleaned by a SELEXOLmore » acid gas removal (AGR) process. Sulfur is recovered using a two-train Claus unit with tail gas recycle to the AGR. A multistage intercooled compressor is used for compressing CO2 to the pressure required for sequestration. Using Illinois No.6 coal, the reference plant generates 640 MWe of net power. The plant-wide steady-state and dynamic IGCC simulations have been generated using the Aspen Plus{reg_sign} and Aspen Plus Dynamics{reg_sign} process simulators, respectively. The model is generated based on the Case 2 IGCC configuration detailed in the study available in the NETL website1. The GEE gasifier is represented with a restricted equilibrium reactor model where the temperature approach to equilibrium for individual reactions can be modified based on the experimental data. In this radiant-only configuration, the syngas from the Radiant Syngas Cooler (RSC) is quenched in a scrubber. The blackwater from the scrubber bottom is further cleaned in the blackwater treatment plant. The cleaned water is returned back to the scrubber and also used for slurry preparation. The acid gas from the sour water stripper (SWS) is sent to the Claus plant. The syngas from the scrubber passes through a sour shift process. The WGS reactors are modeled as adiabatic plug flow reactors with rigorous kinetics based on the mid-life activity of the shift-catalyst. The SELEXOL unit consists of the H2S and CO2 absorbers that are designed to meet the stringent environmental limits and requirements of other associated units. The model also considers the stripper for recovering H2S that is sent as a feed to a split-flow Claus unit. The tail gas from the Claus unit is recycled to the SELEXOL unit. The cleaned syngas is sent to the GE 7FB gas turbine. This turbine is modeled as per published data in the literature. Diluent N2 is used from the elevated-pressure ASU for reducing the NOx formation. The heat recovery steam generator (HRSG) is modeled by considering generation of high-pressure, intermediate-pressure, and low-pressure steam. All of the vessels, reactors, heat exchangers, and the columns have been sized. The basic IGCC process control structure has been synthesized by standard guidelines and existing practices. The steady-state simulation is solved in sequential-modular mode in Aspen Plus{reg_sign} and consists of more than 300 unit operations, 33 design specs, and 16 calculator blocks. The equation-oriented dynamic simulation consists of more than 100,000 equations solved using a multi-step Gear's integrator in Aspen Plus Dynamics{reg_sign}. The challenges faced in solving the dynamic model and key transient results from this dynamic model will also be discussed.« less

SOHO reveals how sunspots take a stranglehold on the Sun

NASA Astrophysics Data System (ADS)

2001-11-01

Bernhard Fleck, ESA's project scientist for SOHO, comments, "The origin and stability of sunspots has been one of the long-standing mysteries in solar physics. I am delighted to see that with SOHO we are beginning to crack this problem." The gas flows around and beneath a sunspot have been detected by a team of scientists in the USA, using the Michelsen Doppler Imager (MDI) on SOHO. The instrument explores the solar interior by detecting natural sound waves at a million points on the Sun's surface. "After many years of contradictory theories about sunspots, MDI on SOHO is at last telling us what really happens," comments Junwei Zhao of Stanford University, California, lead author of a report published in the Astrophysical Journal. Inflows and downflows similar to those now detected with SOHO were envisaged in 1974 by Friedrich Meyer of Germany's Max-Planck- Institut für Physik und Astrophysik, and his colleagues. A similar expectation figured in a theory of sunspots advanced in 1979 by Eugene Parker of Chicago. "Our observation seems to provide strong evidence for both predictions," Zhao says. Sunspots have fascinated scientists since Galileo's time, 400 years ago, when they shattered a belief that the Sun was divinely free of any blemish. As symptoms of intense magnetic activity, sunspots are often associated with solar flares and mass ejections that affect space weather and the Earth itself. The Sun's activity peaks roughly every 11 years, and the latest maximum in the sunspot count occurred in 2000. Even with huge advances in helioseismology, which deduces layers and flows inside the Sun by analysis of sound waves that travel through it and agitate the surface, seeing behind the scenes in sunspots was never going to be easy. The MDI team refined a method of measuring the travel time of sound waves, invented in 1993 by Thomas Duvall of NASA Goddard, called solar tomography. It is like deducing what obstacles cross-country runners have faced, just by seeing in what order the contestants arrive at the finish. Here the runners are packets of sound waves, and the obstacles are local variations in temperature, magnetic fields and gas flows beneath the Sun's surface. "We needed better mathematical tricks," comments Duvall. "So we put together ideas from classical and quantum physics, and also from a recent advance in seismology on the Earth." In an earlier application of solar tomography, the team examined in detail the ante-natal events for an important group of sunspots born on 12 January 1998. They found sound waves beginning to travel faster and faster through the region where sunspots were about to form. Less than half a day elapsed between signs of unusual magnetic activity in the Sun's interior and the appearance of the dark spots on a previously unblemished surface. "Sunspots form when intense magnetic fields break through the visible surface," says Alexander Kosovichev of Stanford. "We could see the magnetic field shooting upwards like a fountain, faster than we expected." Even late on the previous day there was little hint of anything afoot, either at the surface or in the interior. By midnight (Universal Time) a region of strong magnetic field had risen from a depth of 18 000 kilometres and was already half way to the surface, travelling at 4500 km/hr. Sound speeds were increasing above the perturbed zone. By 8:00 a.m. an intense, rope-like magnetic field was in possession of a column of gas 20 000 kilometres wide and reaching almost to the visible surface. In the uppermost layer beneath the surface, the magnetic rope divided itself into strands that made the individual sunspots of the group. Under a large, well-established sunspot, in June 1998, the sound waves revealed a persistent column of hot, magnetised gas rising from deep in the interior. At a depth of 4000 kilometres it spread fingers towards neighbouring parts of the surface where it sustained some smaller sunspots. The magnetic column was not connected to another nearby spot where the magnetic field went in the opposite direction. Immediately below the large spot was a cushion of cooler, less intensely magnetised gas. A closer look at the gas flows, during the development of that June 1998 sunspot, led to the further findings now reported. The inflows and downflows in the immediate vicinity of the sunspot reach downwards for only a few thousand kilometres from the surface, which means less than one per cent of the distance to the Sun's centre. The discovery therefore depended on MDI's unique ability to explore just below the surface. The whirlpool of gas is responsible for the persistence of a sunspot. The cooling due to the magnetic field of the sunspot provokes the down-flow, and the gas disappearing downwards is replaced by more gas flowing inwards towards the spot. It brings with it its own associated magnetic field and prevents the strong magnetic field of the sunspot from dissipating. So the cooling and downflow continue, and the process is self-sustaining. The downflow of gas may also help to explain the puzzling fact that the Sun is actually brighter when it is freckled with dark spots. The VIRGO instrument on SOHO, operated by a Swiss-led team, confirmed the observations of earlier solar spacecraft, showing that sunshine is slightly more intense at sunspot maximum. Douglas Gough of Cambridge University, a leading solar theorist, notes that the downflow of gas seen by MDI on SOHO can redistribute energy bottled up by a sunspot. "What is interesting from the physical point of view is that, being cool, the descending flow is readily able to extract the heat that accumulates beneath the spot," Gough says. "It then spreads the heat away from the sunspot and eventually brings it to the surface of the Sun far from the spot, from where it is radiated into space." Note to editors The SOHO project is an international cooperation between ESA and NASA. The spacecraft was built in Europe for ESA and equipped with instruments by teams of scientists in Europe and the USA. NASA launched SOHO in December 1995, and in 1998 ESA and NASA decided to extend its highly successful operations until 2003.

Three-dimensional instabilities of mantle convection with multiple phase transitions

NASA Technical Reports Server (NTRS)

Honda, S.; Yuen, D. A.; Balachandar, S.; Reuteler, D.

1993-01-01

The effects of multiple phase transitions on mantle convection are investigated by numerical simulations that are based on three-dimensional models. These simulations show that cold sheets of mantle material collide at junctions, merge, and form a strong downflow that is stopped temporarily by the transition zone. The accumulated cold material gives rise to a strong gravitational instability that causes the cold mass to sink rapidly into the lower mantle. This process promotes a massive exchange between the lower and upper mantles and triggers a global instability in the adjacent plume system. This mechanism may be cyclic in nature and may be linked to the generation of superplumes.

Large-scale horizontal flows from SOUP observations of solar granulation

NASA Technical Reports Server (NTRS)

November, L. J.; Simon, G. W.; Tarbell, T. D.; Title, A. M.; Ferguson, S. H.

1987-01-01

Using high resolution time sequence photographs of solar granulation from the SOUP experiment on Spacelab 2, large scale horizontal flows were observed in the solar surface. The measurement method is based upon a local spatial cross correlation analysis. The horizontal motions have amplitudes in the range 300 to 1000 m/s. Radial outflow of granulation from a sunspot penumbra into surrounding photosphere is a striking new discovery. Both the supergranulation pattern and cellular structures having the scale of mesogranulation are seen. The vertical flows that are inferred by continuity of mass from these observed horizontal flows have larger upflow amplitudes in cell centers than downflow amplitudes at cell boundaries.

Oxic limestone drains for treatment of dilute, acidic mine drainage

USGS Publications Warehouse

Cravotta, Charles A.

1998-01-01

Limestone treatment systems can be effective for remediation of acidic mine drainage (AMD) that contains moderate concentrations of dissolved O2 , Fe3+ , or A13+ (1‐5 mg‐L‐1 ). Samples of water and limestone were collected periodically for 1 year at inflow, outflow, and intermediate points within underground, oxic limestone drains (OLDs) in Pennsylvania to evaluate the transport of dissolved metals and the effect of pH and Fe‐ and Al‐hydrolysis products on the rate of limestone dissolution. The influent was acidic and relatively dilute (pH <4; acidity < 90 mg‐L‐1 ) but contained 1‐4 mg‐L‐1 Of O2 , Fe3+ , A13+ , and Mn2+ . The total retention time in the OLDs ranged from 1.0 to 3.1 hours. Effluent remained oxic (02 >1 mg‐L‐1 ) but was near neutral (pH = 6.2‐7.0); Fe and Al decreased to less than 5% of influent concentrations. As pH increased near the inflow, hydrous Fe and Al oxides precipitated in the OLDs. The hydrous oxides, nominally Fe(OH)3 and AI(OH)3, were visible as loosely bound, orange‐yellow coatings on limestone near the inflow. As time elapsed, Fe(OH)3 and AI(OH)3 particles were transported downflow. During the first 6 months of the experiment, Mn 2+ was transported conservatively through the OLDs; however, during the second 6 months, concentrations of Mn in effluent decreased by about 50% relative to influent. The accumulation of hydrous oxides and elevated pH (>5) in the downflow part of the OLDs promoted sorption and coprecipitation of Mn as indicated by its enrichment relative to Fe in hydrous‐oxide particles and coatings on limestone. Despite thick (~1 mm) hydrous‐oxide coatings on limestone near the inflow, CaCO3 dissolution was more rapid near the inflow than at downflow points within the OLD where the limestone was not coated. The rate of limestone dissolution decreased with increased residence time, pH, and concentrations of Ca2+ and HCO3‐ and decreased PCO2. The following overall reaction shows alkalinity as an ultimate product of the iron hydrolysis reaction in an OLD:Fe2+ + 0.25 O2 +CaCO3 + 2.5 H2O --> Fe(OH)3 + 2 Ca2+ + 2 HCO3-where 2 moles of CaCO3 dissolve for each mole of Fe(OH)3 produced. Hence, in an OLD, rapidly dissolving limestone surfaces are not stable substrates for Fe(OH)3 attachment and armoring. Because overall efficiency is increased by combining neutralization and hydrolysis reactions, an OLD followed by a settling pond requires less land area than needed for a two‐stage treatment system consisting of an anoxic limestone drain an oxidation‐settling pond or wetland. To facilitate removal of hydrous‐oxide sludge, a perforated‐pipe subdrain can be installed within an OLD.

Large-scale horizontal flows from SOUP observations of solar granulation

NASA Astrophysics Data System (ADS)

November, L. J.; Simon, G. W.; Tarbell, T. D.; Title, A. M.; Ferguson, S. H.

1987-09-01

Using high-resolution time-sequence photographs of solar granulation from the SOUP experiment on Spacelab 2 the authors observed large-scale horizontal flows in the solar surface. The measurement method is based upon a local spatial cross correlation analysis. The horizontal motions have amplitudes in the range 300 to 1000 m/s. Radial outflow of granulation from a sunspot penumbra into the surrounding photosphere is a striking new discovery. Both the supergranulation pattern and cellular structures having the scale of mesogranulation are seen. The vertical flows that are inferred by continuity of mass from these observed horizontal flows have larger upflow amplitudes in cell centers than downflow amplitudes at cell boundaries.

THE FLARE-ONA OF EK DRACONIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayres, Thomas R., E-mail: Thomas.Ayres@Colorado.edu

2015-07-15

EK Draconis (HD 129333: G1.5 V) is a well-known young (50 Myr) solar analog. In 2012, Hubble Space Telescope returned to EK Dra to follow up a far-ultraviolet (FUV) SNAPshot visit by Cosmic Origins Spectrograph (COS) two years earlier. The brief SNAP pointing had found surprisingly redshifted, impulsively variable subcoronal “hot-line” emission of Si iv 1400 Å (T ∼ 8 × 10{sup 4} K). Serendipitously, the 2012 follow-on program witnessed one of the largest FUV flares ever recorded on a sunlike star, which again displayed strong redshifts (downflows) of 30–40 km s{sup −1}, even after compensating for small systematics inmore » the COS velocity scales, uncovered through a cross-calibration by Space Telescope Imaging Spectrograph (STIS). The (now reduced, but still substantial) ∼10 km s{sup −1} hot-line redshifts outside the flaring interval did not vary with rotational phase, so cannot be caused by “Doppler imaging” (bright surface patches near a receding limb). Density diagnostic O iv] 1400 Å multiplet line ratios of EK Dra suggest n{sub e} ∼ 10{sup 11} cm{sup −3}, an order of magnitude larger than in low-activity solar twin α Centauri A, but typical of densities inferred in large stellar soft X-ray events. The self-similar FUV hot-line profiles between the flare decay and the subsequent more quiet periods, and the unchanging but high densities, reinforce a long-standing idea that the coronae of hyperactive dwarfs are flaring all the time, in a scale-free way; a flare-ona if you will. In this picture, the subsonic hot-line downflows probably are a byproduct of the post-flare cooling process, something like “coronal rain” on the Sun. All in all, the new STIS/COS program documents a complex, energetic, dynamic outer atmosphere of the young sunlike star.« less

Field and experimental constraints on the rheology of arc basaltic lavas: the January 2014 Eruption of Pacaya (Guatemala)

NASA Astrophysics Data System (ADS)

Soldati, A.; Sehlke, A.; Chigna, G.; Whittington, A.

2016-06-01

We estimated the rheology of an active basaltic lava flow in the field, and compared it with experimental measurements carried out in the laboratory. In the field we mapped, sampled, and recorded videos of the 2014 flow on the southern flank of Pacaya, Guatemala. Velocimetry data extracted from videos allowed us to determine that lava traveled at ˜2.8 m/s on the steep ˜45° slope 50 m from the vent, while 550 m further downflow it was moving at only ˜0.3 m/s on a ˜4° slope. Estimates of effective viscosity based on Jeffreys' equation increased from ˜7600 Pa s near the vent to ˜28,000 Pa s downflow. In the laboratory, we measured the viscosity of a representative lava composition using a concentric cylinder viscometer, at five different temperatures between 1234 and 1199 °C, with crystallinity increasing from 0.1 to 40 vol%. The rheological data were best fit by power law equations, with the flow index decreasing as crystal fraction increased, and no detectable yield strength. Although field-based estimates are based on lava characterized by a lower temperature, higher crystal and bubble fraction, and with a more complex petrographic texture, field estimates and laboratory measurements are mutually consistent and both indicate shear-thinning behavior. The complementary field and laboratory data sets allowed us to isolate the effects of different factors in determining the rheological evolution of the 2014 Pacaya flows. We assess the contributions of cooling, crystallization, and changing ground slope to the 3.7-fold increase in effective viscosity observed in the field over 550 m, and conclude that decreasing slope is the single most important factor over that distance. It follows that the complex relations between slope, flow velocity, and non-Newtonian lava rheology need to be incorporated into models of lava flow emplacement.

Construction and demolition waste: Comparison of standard up-flow column and down-flow lysimeter leaching tests.

PubMed

Butera, Stefania; Hyks, Jiri; Christensen, Thomas H; Astrup, Thomas F

2015-09-01

Five samples of construction and demolition waste (C&DW) were investigated in order to quantify leaching of inorganic elements under percolation conditions according to two different experimental setups: standardised up-flow saturated columns (<4mm particle size) and unsaturated, intermittent down-flow lysimeters (<40mm particle size). While standardised column tests are meant primarily to provide basic information on characteristic leaching properties and mechanisms and not to reproduce field conditions, the lysimeters were intended to mimic the actual leaching conditions when C&DW is used in unbound geotechnical layers. In practice, results from standardised percolation tests are often interpreted as estimations of actual release from solid materials in percolation scenarios. In general, the two tests yielded fairly similar results in terms of cumulative release at liquid-to-solid ratio (L/S) 10l·kgTS; however, significant differences were observed for P, Pb, Ba, Mg and Zn. Further differences emerged in terms of concentration in the early eluates (L/S<5l·kg(-1)TS) for Al, As, Ba, Cd, Cu, DOC, Mg, Mn, Ni, P, Pb, Sb, Se, Si, Zn. Observed differences between tests are likely to be due to differences in pH related to crushing and exposure of fresh particle surfaces, as well as in equilibrium conditions. In the case of C&DW, the standardised column tests, which are more practical, are considered to acceptably describe cumulative releases at L/S 10l·kg(-1)TS in percolation scenarios. However, when the focus is on estimation of initial concentrations for (for example) risk assessment, data from standardised column tests may not be fully applicable, and data from lysimeters may be used for validation purposes. Se, Cr and, to a lesser extent, SO4 and Sb were leaching from C&DW in critical amounts compared with existing limit values. Copyright © 2015 Elsevier Ltd. All rights reserved.

3D architecture of cyclic-step and antidune deposits in glacigenic subaqueous fan and delta settings: Integrating outcrop and ground-penetrating radar data

NASA Astrophysics Data System (ADS)

Lang, Jörg; Sievers, Julian; Loewer, Markus; Igel, Jan; Winsemann, Jutta

2017-12-01

Bedforms related to supercritical flows are increasingly recognised as important constituents of many depositional environments, but outcrop studies are commonly hampered by long bedform wavelengths and complex three-dimensional geometries. We combined outcrop-based facies analysis with ground-penetrating radar (GPR) surveys to analyse the 3D facies architecture of subaqueous ice-contact fan and glacifluvial delta deposits. The studied sedimentary systems were deposited at the margins of the Middle Pleistocene Scandinavian ice sheets in Northern Germany. Glacifluvial Gilbert-type deltas are characterised by steeply dipping foreset beds, comprising cyclic-step deposits, which alternate with antidune deposits. Deposits of cyclic steps consist of lenticular scours infilled by backset cross-stratified pebbly sand and gravel. The GPR sections show that the scour fills form trains along the delta foresets, which can locally be traced for up to 15 m. Perpendicular and oblique to palaeoflow direction, these deposits appear as troughs with concentric or low-angle cross-stratified infills. Downflow transitions from scour fills into sheet-like low-angle cross-stratified or sinusoidally stratified pebbly sand, deposited by antidunes, are common. Cyclic steps and antidunes were deposited by sustained and surge-type supercritical density flows, which were related to hyperpycnal flows, triggered by major meltwater discharge or slope-failure events. Subaqueous ice-contact fan deposits include deposits of progradational scour fills, isolated hydraulic jumps, antidunes and (humpback) dunes. The gravel-rich fan succession consists of vertical stacks of laterally amalgamated pseudo-sheets, indicating deposition by pulses of waning supercritical flows under high aggradation rates. The GPR sections reveal the large-scale architecture of the sand-rich fan succession, which is characterised by lobe elements with basal erosional surfaces associated with scours filled with backsets related to hydraulic jumps, passing upwards and downflow into deposits of antidunes and (humpback) dunes. The recurrent facies architecture of the lobe elements and their prograding and retrograding stacking pattern are interpreted as related to autogenic flow morphodynamics.

Chromospheric Inversions of a Micro-flaring Region

NASA Astrophysics Data System (ADS)

Reid, A.; Henriques, V.; Mathioudakis, M.; Doyle, J. G.; Ray, T.

2017-08-01

We use spectropolarimetric observations of the Ca II 8542 Å line, taken from the Swedish 1 m Solar Telescope, in an attempt to recover dynamic activity in a micro-flaring region near a sunspot via inversions. These inversions show localized mean temperature enhancements of ˜1000 K in the chromosphere and upper photosphere, along with co-spatial bi-directional Doppler shifting of 5-10 km s-1. This heating also extends along a nearby chromospheric fibril, which is co-spatial to 10-15 km s-1 downflows. Strong magnetic flux cancellation is also apparent in one of the footpoints, and is concentrated in the chromosphere. This event more closely resembles that of an Ellerman Bomb, though placed slightly higher in the atmosphere than what is typically observed.

Performance Evaluation and Adaptability Research of Flowing Gel System Prepared with Re-injected Waste Water

NASA Astrophysics Data System (ADS)

Shi, Lei; You, Jing; Liu, Na; Liu, Xinmin; Wang, Zhiqiang; Zhang, Tiantian; Gu, Yi; Guo, Suzhen; Gao, Shanshan

2017-12-01

The crosslinking intensity and stability of flowing gel system prepared with re-injected waste water are seriously affected as the high salinity waste water contains a high concentration of Na+, Fe2+, S2-, Ca2+, etc. The influence of various ions on the flowing gel system can be reduced by increasing polymer concentration, adding new ferric ion stabilizing agent (MQ) and calcium ion eliminating agent (CW). The technique of profile controlling and oil-displacing is carried out in Chanan multi-purpose station, Chabei multi-purpose station and Chayi multi-purpose station of Huabei Oilfield. The flowing gel system is injected from 10 downflow wells and the 15 offsetting production wells have increased the yield by 1770 tons.

Analysis of a dusty wall jet

NASA Technical Reports Server (NTRS)

Lim, Hock-Bin; Roberts, Leonard

1991-01-01

An analysis is given for the entrainment of dust into a turbulent radial wall jet. Equations are solved based on incompressible flow of a radial wall jet into which dust is entrained from the wall and transported by turbulent diffusion and convection throughout the flow. It is shown that the resulting concentration of dust particles in the flow depends on the difference between the applied shear stress at the surface and the maximum level of shear stress that the surface can withstand (varies as rho(sub d)a(sub g)D) i.e., the pressure due to the weight of a single layer of dust. The analysis is expected to have application to the downflow that results from helicopter and VTOL aircraft.

The structure, energy balance, and winds of cool stars

NASA Technical Reports Server (NTRS)

Linsky, J. L.

1982-01-01

The phenomena associated with magnetic fields in the Sun are summarized and it is shown that similar phenomena occur in cool stars. High dispersion spectra are providing unique information concerning densities, atmospheric extension, and emission line widths. A recent unanticipated discovery is that the transition lines are redshifted (an antiwind) in beta Dra (G2 Ib) and perhaps other stars. This is interpreted as indicating downflows in closed magnetic flux tubes as are seen in the solar flux tubes above sunspots. The G and K giants and supergiants are classified as active stars, quiet stars, or hybrid stars depending on whether their atmospheres are dominated by closed magnetic flux tubes, open field geometries, or a predominately open geometry with a few closed flux tubes embedded.

Tomographic Imaging of the Suns Interior

NASA Technical Reports Server (NTRS)

Kosovichev, A. G.

1996-01-01

A new method is presented of determining the three-dimensional sound-speed structure and flow velocities in the solar convection zone by inversion of the acoustic travel-time data recently obtained by Duvall and coworkers. The initial inversion results reveal large-scale subsurface structures and flows related to the active regions, and are important for understanding the physics of solar activity and large-scale convection. The results provide evidence of a zonal structure below the surface in the low-latitude area of the magnetic activity. Strong converging downflows, up to 1.2 km/s, and a substantial excess of the sound speed are found beneath growing active regions. In a decaying active region, there is evidence for the lower than average sound speed and for upwelling of plasma.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Requerey, Iker S.; Cobo, B. Ruiz; Iniesta, J. C. Del Toro

We study the dynamics and topology of an emerging magnetic flux concentration using high spatial resolution spectropolarimetric data acquired with the Imaging Magnetograph eXperiment on board the sunrise balloon-borne solar observatory. We obtain the full vector magnetic field and the line of sight (LOS) velocity through inversions of the Fe i line at 525.02 nm with the SPINOR code. The derived vector magnetic field is used to trace magnetic field lines. Two magnetic flux concentrations with different polarities and LOS velocities are found to be connected by a group of arch-shaped magnetic field lines. The positive polarity footpoint is weakermore » (1100 G) and displays an upflow, while the negative polarity footpoint is stronger (2200 G) and shows a downflow. This configuration is naturally interpreted as a siphon flow along an arched magnetic flux tube.« less

Studies on the pretreatment of zeolite clinoptilolite in packed beds.

PubMed

Inglezakis, V J; Loizidou, M D; Grigoropoulou, H P

2004-02-01

The effect of volumetric flow rate, ranging from 5 to 45 Bed Volumes per hour (BV h(-1)) and temperature, ranging from 25 to 59 degrees C, during pretreatment of clinoptilolite on its effective capacity has been investigated. Pretreatment tests have been performed in an upflow ion exchange bed. Increased temperatures were found to increase the effective capacity of clinoptilolite. Effective capacity was maximal at low volumetric flow rates, indicating an influence of contact time and complete saturation of the zeolite bed at flow rates lower than 10 BV h(-1). Furthermore, a comparison between upflow and downflow operation at the same operating conditions showed that better results are obtained in upflow conditions, probably due to the better wetting of the material and the absence of liquid maldistribution.

Two-dimensional magnetohydrodynamic model of emerging magnetic flux in the solar atmosphere

NASA Technical Reports Server (NTRS)

Shibata, K.; Tajima, T.; Steinolfson, R. S.; Matsumoto, R.

1989-01-01

The nonlinear undular mode of the magnetic buoyancy instability in an isolated horizontal magnetic flux embedded in a two-temperature layered atmosphere (solar corona-chromosphere/photosphere) is investigated using a two-dimensional magnetohydrodynamic code. The results show that the flux sheet with beta of about 1 is initially located at the bottom of the photosphere, and that the gas slides down the expanding loop as the instability develops, with the evacuated loop rising as a result of enhanced magnetic buoyancy. The expansion of the magnetic loop in the nonlinear regime displays self-similar behavior. The rise velocity of the magnetic loop in the high chromosphere (10-15 km/s) and the velocity of downflow noted along the loop (30-50 km/s) are consistent with observed values for arch filament systems.

Non-slag co-gasification of biomass and coal in entrained-bed furnace

NASA Astrophysics Data System (ADS)

Itaya, Yoshinori; Suami, Akira; Kobayashi, Nobusuke

2018-02-01

Gasification is a promising candidate of processes to upgrade biomass and to yield clean gaseous fuel for utilization of renewable energy resources. However, a sufficient amount of biomass is not always available to operate a large scale of the plant. Co-gasification of biomass with coal is proposed as a solution of the problem. Tar emission is another subject during operation in shaft or kiln type of gasifiers employed conventionally for biomass. The present authors proposed co-gasification of biomass and coal in entrained-bed furnace, which is a representative process without tar emission under high temperature, but operated so to collect dust as flyash without molten slag formation. This paper presents the works performed on co-gasification performance of biomass and pulverized coal to apply to entrained-bed type of furnaces. At first, co-gasification of woody powder and pulverized coal examined using the lab-scale test furnace of the down-flow entrained bed showed that the maximum temperatures in the furnace was over 1500 K and the carbon conversion to gas achieved at higher efficiency than 80-90 percent although the residence time in the furnace was as short as a few seconds. Non-slag co-gasification was carried out successfully without slag formation in the furnace if coal containing ash with high fusion temperature was employed. The trend suggesting the effect of reaction rate enhancement of co-gasification was also observed. Secondary, an innovative sewage sludge upgrading system consisting of self-energy recovery processes was proposed to yield bio-dried sludge and to sequentially produce char without adding auxiliary fuel. Carbonization behavior of bio-dried sludge was evaluated through pyrolysis examination in a lab-scale quartz tube reactor. The thermal treatment of pyrolysis of sludge contributed to decomposition and removal of contaminant components such as nitrogen and sulfur. The gasification kinetics of sludge and coal was also determined by a thermogravimetric analysis. It was revealed that co-gasification rate of sludge and coal chars was influenced negatively due to high ash content in sludge.

The role of the thermal convection of fluids in the formation of unconformity-type uranium deposits: the Athabasca Basin, Canada

NASA Astrophysics Data System (ADS)

Pek, A. A.; Malkovsky, V. I.

2017-05-01

In the global production of uranium, 18% belong to the unconformity-type Canadian deposits localized in the Athabasca Basin. These deposits, which are unique in terms of their ore quality, were primarily studied by Canadian and French scientists. They have elaborated the diagenetic-hydrothermal hypothesis of ore formation, which suggests that (1) the deposits were formed within a sedimentary basin near an unconformity surface dividing the folded Archean-Proterozoic metamorphic basement and a gently dipping sedimentary cover, which is not affected by metamorphism; (2) the spatial accommodation of the deposits is controlled by the rejuvenated faults in the basement at their exit into the overlying sedimentary sequence; the ore bodies are localized above and below the unconformity surface; (3) the occurrence of graphite-bearing rocks is an important factor in controlling the local structural mineralization; (4) the ore bodies are the products of uranium precipitation on a reducing barrier. The mechanism that drives the circulation of ore-forming hydrothermal solutions has remained one of the main unclear questions in the general genetic concept. The ore was deposited above the surface of the unconformity due to the upflow discharge of the solution from the fault zones into the overlying conglomerate and sandstone. The ore formation below this surface is a result of the downflow migration of the solutions along the fault zones from sandstone into the basement rocks. A thermal convective system with the conjugated convection cells in the basement and sedimentary fill of the basin may be a possible explanation of why the hydrotherms circulate in the opposite directions. The results of our computations in the model setting of the free thermal convection of fluids are consistent with the conceptual reasoning about the conditions of the formation of unique uranium deposits in the Athabasca Basin. The calculated rates of the focused solution circulation through the fault zones in the upflow and downflow branches of a convection cell allow us to evaluate the time of ore formation up to the first hundreds of thousands years.

Investigation of Body Force Effects on Flow Boiling Critical Heat Flux

NASA Technical Reports Server (NTRS)

Zhang, Hui; Mudawar, Issam; Hasan, Mohammad M.

2002-01-01

The bubble coalescence and interfacial instabilities that are important to modeling critical heat flux (CHF) in reduced-gravity systems can be sensitive to even minute body forces. Understanding these complex phenomena is vital to the design and safe implementation of two-phase thermal management loops proposed for space and planetary-based thermal systems. While reduced gravity conditions cannot be accurately simulated in 1g ground-based experiments, such experiments can help isolate the effects of the various forces (body force, surface tension force and inertia) which influence flow boiling CHF. In this project, the effects of the component of body force perpendicular to a heated wall were examined by conducting 1g flow boiling experiments at different orientations. FC-72 liquid was boiled along one wall of a transparent rectangular flow channel that permitted photographic study of the vapor-liquid interface at conditions approaching CHF. High-speed video imaging was employed to capture dominant CHF mechanisms. Six different CHF regimes were identified: Wavy Vapor Layer, Pool Boiling, Stratification, Vapor Counterflow, Vapor Stagnation, and Separated Concurrent Vapor Flow. CHF showed great sensitivity to orientation for flow velocities below 0.2 m/s, where very small CHF values where measured, especially with downflow and downward-facing heated wall orientations. High flow velocities dampened the effects of orientation considerably. Figure I shows representative images for the different CHF regimes. The Wavy Vapor Layer regime was dominant for all high velocities and most orientations, while all other regimes were encountered at low velocities, in the downflow and/or downward-facing heated wall orientations. The Interfacial Lift-off model was modified to predict the effects of orientation on CHF for the dominant Wavy Vapor Layer regime. The photographic study captured a fairly continuous wavy vapor layer travelling along the heated wall while permitting liquid contact only in wetting fronts, located in the troughs of the interfacial waves. CHF commenced when wetting fronts near the outlet were lifted off the wall. The Interfacial Lift-off model is shown to be an effective tool for predicting the effects of body force on CHF at high velocities.

FLARE FOOTPOINT REGIONS AND A SURGE OBSERVED BY HINODE/EIS, RHESSI, AND SDO/AIA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doschek, G. A.; Warren, H. P.; Dennis, B. R.

2015-11-01

The Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft observed flare footpoint regions coincident with a surge for an M3.7 flare observed on 2011 September 25 at N12 E33 in active region 11302. The flare was observed in spectral lines of O vi, Fe x, Fe xii, Fe xiv, Fe xv, Fe xvi, Fe xvii, Fe xxiii, and Fe xxiv. The EIS observations were made coincident with hard X-ray bursts observed by RHESSI. Overlays of the RHESSI images on the EIS raster images at different wavelengths show a spatial coincidence of features in the RHESSI images with the EIS upflowmore » and downflow regions, as well as loop-top or near-loop-top regions. A complex array of phenomena were observed, including multiple evaporation regions and the surge, which was also observed by the Solar Dynamics Observatory/Atmospheric Imaging Assembly telescopes. The slit of the EIS spectrometer covered several flare footpoint regions from which evaporative upflows in Fe xxiii and Fe xxiv lines were observed with Doppler speeds greater than 500 km s{sup −1}. For ions such as Fe xv both evaporative outflows (∼200 km s{sup −1}) and downflows (∼30–50 km s{sup −1}) were observed. Nonthermal motions from 120 to 300 km s{sup −1} were measured in flare lines. In the surge, Doppler speeds are found from about 0 to over 250 km s{sup −1} in lines from ions such as Fe xiv. The nonthermal motions could be due to multiple sources slightly Doppler-shifted from each other or turbulence in the evaporating plasma. We estimate the energetics of the hard X-ray burst and obtain a total flare energy in accelerated electrons of ≥7 × 10{sup 28} erg. This is a lower limit because only an upper limit can be determined for the low-energy cutoff to the electron spectrum. We find that detailed modeling of this event would require a multithreaded model owing to its complexity.« less

Patchy reconnection in the solar corona

NASA Astrophysics Data System (ADS)

Guidoni, Silvina Esther

2011-05-01

Magnetic reconnection in plasmas, a process characterized by a change in connectivity of field lines that are broken and connected to other ones with different topology, owes its usefulness to its ability to unify a wide range of phenomena within a single universal principle. There are newly observed phenomena in the solar corona that cannot be reconciled with two-dimensional or steady-state standard models of magnetic reconnection. Supra-arcade downflows (SADs) and supra-arcade downflowing loops (SADLs) descending from reconnection regions toward solar post-flare arcades seem to be two different observational signatures of retracting, isolated reconnected flux tubes with irreducible three-dimensional geometries. This dissertation describes work in refining and improving a novel model of patchy reconnection, where only a small bundle of field lines is reconnected across a current sheet (magnetic discontinuity) and forms a reconnected thin flux tube. Traditional models have not been able to explain why some of the observed SADs appear to be hot and relatively devoid of plasma. The present work shows that plasma depletion naturally occurs in flux tubes that are reconnected across nonuniform current sheets and slide trough regions of decreasing magnetic field magnitude. Moreover, through a detailed theoretical analysis of generalized thin flux tube equations, we show that the addition to the model of pressure-driven parallel dynamics, as well as temperature-dependent, anisotropic viscosity and thermal conductivity is essential for self-consistently producing gas-dynamic shocks inside reconnected tubes that heat and compress plasma to observed temperatures and densities. The shock thickness can be as long as the entire tube and heat can be conducted along tube's legs, possibly driving chromospheric evaporation. We developed a computer program that solves numerically the thin flux tube equations that govern the retraction of reconnected tubes. Simulations carried out with this program corroborate our theoretical predictions. A comparison of these simulations with fully three-dimensional magnetohydrodynamic simulations is presented to assess the validity of the thin flux tube model. We also present an observational method based on total emission measure and mean temperature to determine where in the current sheet a tube was reconnected.

Chromospheric Inversions of a Micro-flaring Region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reid, A.; Henriques, V.; Mathioudakis, M.

2017-08-20

We use spectropolarimetric observations of the Ca ii 8542 Å line, taken from the Swedish 1 m Solar Telescope, in an attempt to recover dynamic activity in a micro-flaring region near a sunspot via inversions. These inversions show localized mean temperature enhancements of ∼1000 K in the chromosphere and upper photosphere, along with co-spatial bi-directional Doppler shifting of 5–10 km s{sup −1}. This heating also extends along a nearby chromospheric fibril, which is co-spatial to 10–15 km s{sup −1} downflows. Strong magnetic flux cancellation is also apparent in one of the footpoints, and is concentrated in the chromosphere. This eventmore » more closely resembles that of an Ellerman Bomb, though placed slightly higher in the atmosphere than what is typically observed.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaithakkal, A. J.; Riethmüller, T. L.; Solanki, S. K.

Spectropolarimetric observations from Sunrise/IMaX, obtained in 2013 June, are used for a statistical analysis to determine the physical properties of moving magnetic features (MMFs) observed near a pore. MMFs of the same and opposite polarity, with respect to the pore, are found to stream from its border at an average speed of 1.3 km s{sup −1} and 1.2 km s{sup −1}, respectively, with mainly same-polarity MMFs found further away from the pore. MMFs of both polarities are found to harbor rather weak, inclined magnetic fields. Opposite-polarity MMFs are blueshifted, whereas same-polarity MMFs do not show any preference for up- or downflows.more » Most of the MMFs are found to be of sub-arcsecond size and carry a mean flux of ∼1.2 × 10{sup 17} Mx.« less

Concepts for a theoretical and experimental study of lifting rotor random loads and vibrations (further experiments with progressing/regressing rotor flapping modes), Phase 7-C

NASA Technical Reports Server (NTRS)

Hohenemser, K. H.; Crews, S. T.

1973-01-01

The experiments with progressing/regressing forced rotor flapping modes have been extended in several directions and the data processing method has been considerably refined. The 16 inch hingeless 2-bladed rotor model was equipped with a new set of high precision blades which removed previously encountered tracking difficulties at high advance ratio, so that tests up to .8 rotor advance ratio could be conducted. In addition to data with 1.20 blade natural flapping frequency data at 1.10 flapping frequency were obtained. Outside the wind tunnel, tests with a ground plate located at different distances below the rotor were conducted while recording the dynamic downflow at a station .2R below the rotor plane with a hot wire anemometer.

Solar Prominence Fine Structure and Dynamics

NASA Astrophysics Data System (ADS)

Berger, Thomas

2014-01-01

We review recent observational and theoretical results on the fine structure and dynamics of solar prominences, beginning with an overview of prominence classifications, the proposal of possible new ``funnel prominence'' classification, and a discussion of the recent ``solar tornado'' findings. We then focus on quiescent prominences to review formation, down-flow dynamics, and the ``prominence bubble'' phenomena. We show new observations of the prominence bubble Rayleigh-Taylor instability triggered by a Kelvin-Helmholtz shear flow instability occurring along the bubble boundary. Finally we review recent studies on plasma composition of bubbles, emphasizing that differential emission measure (DEM) analysis offers a more quantitative analysis than photometric comparisons. In conclusion, we discuss the relation of prominences to coronal magnetic flux ropes, proposing that prominences can be understood as partially ionized condensations of plasma forming the return flow of a general magneto-thermal convection in the corona.

Intraflow width variations in Martian and terrestrial lava flows

NASA Astrophysics Data System (ADS)

Peitersen, Matthew N.; Crown, David A.

1997-03-01

Flow morphology is used to interpret emplacement processes for lava flows on Earth and Mars. Accurate measurements of flow geometry are essential, particularly for planetary flows where neither compositional sampling nor direct observations of active flows may be possible. Width behavior may indicate a flow's response to topography, its emplacement regime, and its physical properties. Variations in width with downflow distance from the vent may therefore provide critical clues to flow emplacement processes. Flow width is also one of the few characteristics that can be readily measured from planetary mission data with accuracy. Recent analyses of individual flows at two terrestrial and four Martian sites show that widths within an individual flow vary by up to an order of magnitude. Width is generally thought to be correlated to topography; however, recent studies show that this relationship is neither straightforward nor easily quantifiable.

Observational Evidence for Small-Scale Mixture of Weak and Strong Fields in the Quiet Sun

NASA Astrophysics Data System (ADS)

Socas-Navarro, H.; Lites, B. W.

2004-11-01

Three different maps of the quiet Sun, observed with the Advanced Stokes Polarimeter (ASP) and the Diffraction-Limited Stokes Polarimeter (DLSP), show evidence of strong (~=1700 G) and weak (<500 G) fields coexisting within the resolution element at both network and internetwork locations. The angular resolution of the observations is of 1" (ASP) and 0.6" (DLSP). Even at the higher DLSP resolution, a significant fraction of the network magnetic patches harbor a mixture of strong and weak fields. Internetwork elements that exhibit kG fields when analyzed with a single-component atmosphere are also shown to harbor considerable amounts of weak fields. Only those patches for which a single-component analysis yields weak fields do not show this mixture of field strengths. Finally, there is a larger fractional area of weak fields in the convective upflows than in the downflows.

ALFVÉN WAVES IN SIMULATIONS OF SOLAR PHOTOSPHERIC VORTICES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shelyag, S.; Cally, P. S.; Reid, A.

Using advanced numerical magneto-hydrodynamic simulations of the magnetized solar photosphere, including non-gray radiative transport and a non-ideal equation of state, we analyze plasma motions in photospheric magnetic vortices. We demonstrate that apparent vortex-like motions in photospheric magnetic field concentrations do not exhibit 'tornado'-like behavior or a 'bath-tub' effect. While at each time instance the velocity field lines in the upper layers of the solar photosphere show swirls, the test particles moving with the time-dependent velocity field do not demonstrate such structures. Instead, they move in a wave-like fashion with rapidly changing and oscillating velocity field, determined mainly by magnetic tensionmore » in the magnetized intergranular downflows. Using time-distance diagrams, we identify horizontal motions in the magnetic flux tubes as torsional Alfvén perturbations propagating along the nearly vertical magnetic field lines with local Alfvén speed.« less

OSO-8 observations of the impulsive phase of solar flares in the transition-zone and corona

NASA Technical Reports Server (NTRS)

Lites, B. W.; Bruner, E. C., Jr.; Wolfson, C. J.

1981-01-01

Several solar flares were observed from their onset in C IV 1548.2 A and 1-8 A X-rays using instruments on OSO-8. It is found that impulsive brightening in C IV is often accompanied by redshifts, interpreted as downflows, of the order of 80 km/s. The maximum soft X-ray intensity usually arrives several minutes after the maximum C IV intensity. The most energetic C IV event observed shows a small blueshift just before reaching maximum intensity; estimates of the mass flux associated with this upflow through the transition zone are consistent with the increase of mass in the coronal loops as observed in soft X-rays. Finally, it is suggested that the frequent occurrence of violent dynamical processes at the onset of the flare is associated with the initial energy release mechanism.

Evidence of redshifts in the average solar line profiles of C IV and Si IV from OSO-8 observations

NASA Technical Reports Server (NTRS)

Roussel-Dupre, D.; Shine, R. A.

1982-01-01

Line profiles of C IV and Si V obtained by the Colorado spectrometer on OSO-8 are presented. It is shown that the mean profiles are redshifted with a magnitude varying from 6-20 km/s, and with a mean of 12 km/s. An apparent average downflow of material in the 50,000-100,000 K temperature range is measured. The redshifts are observed in the line center positions of spatially and temporally averaged profiles and are measured either relative to chromospheric Si I lines or from a comparison of sun center and limb profiles. The observations of 6-20 km/s redshifts place constraints on the mechanisms that dominate EUV line emission since it requires a strong weighting of the emission in regions of downward moving material, and since there is little evidence for corresponding upward moving materials in these lines.

Observations of the Formation, Development, and Structure of a Current Sheet in an Eruptive Solar Flare

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seaton, Daniel B.; Darnel, Jonathan M.; Bartz, Allison E., E-mail: daniel.seaton@noaa.gov

2017-02-01

We present Atmospheric Imaging Assembly observations of a structure we interpret as a current sheet associated with an X4.9 flare and coronal mass ejection that occurred on 2014 February 25 in NOAA Active Region 11990. We characterize the properties of the current sheet, finding that the sheet remains on the order of a few thousand kilometers thick for much of the duration of the event and that its temperature generally ranged between 8 and 10 MK. We also note the presence of other phenomena believed to be associated with magnetic reconnection in current sheets, including supra-arcade downflows and shrinking loops.more » We estimate that the rate of reconnection during the event was M{sub A} ≈ 0.004–0.007, a value consistent with model predictions. We conclude with a discussion of the implications of this event for reconnection-based eruption models.« less

Hexagonal convection patterns and their evolutionary scenarios in electroconvection induced by a strong unipolar injection

NASA Astrophysics Data System (ADS)

Luo, Kang; Wu, Jian; Yi, Hong-Liang; Liu, Lin-Hua; Tan, He-Ping

2018-05-01

A regular hexagonal pattern of three-dimensional electroconvective flow induced by unipolar injection in dielectric liquids is numerically observed by solving the fully coupled governing equations using the lattice Boltzmann method. A small-amplitude perturbation in the form of a spatially periodic pattern of hexagonal cells is introduced initially. The transient development of convective cells that undergo a sequence of transitions agrees with the idea of flow seeking an optimal scale. Stable hexagonal convective cells and their subcritical bifurcation together with a hysteresis loop are clearly observed. In addition, the stability of the hexagonal flow pattern is analyzed in a wide range of relevant parameters, including the electric Rayleigh number T , nondimensional mobility M , and wave number k . It is found that centrally downflowing hexagonal cells, which are characterized by the central region being empty of charge, are preferred in the system.

Measurements of solar transition zone velocities and line broadening using the ultraviolet spectrometer and polarimeter on the Solar Maximum Mission

NASA Technical Reports Server (NTRS)

Simon, G.; Mein, P.; Vial, J. C.; Shine, R. A.; Woodgate, B. E.

1982-01-01

The UVSP instrument on SMM is able to observe solar regions at two wavelengths in the same line with a band-pass of 0.3 A. Intensity and Doppler velocity maps are derived. It is shown that the numerical values are sensitive to the adopted Doppler width and the range of velocities is limited to within 30 km/sec. A method called Double Dopplergram Determination (DDD) is described for deriving both the Doppler width and the velocity (up to 80 km/sec), and the main sources of uncertainties are discussed. To illustrate the method, a set of C IV 1548 A observations is analyzed according to this procedure. The mean C IV Doppler width measured (0.15 A) is comparable to previous determinations. A relation is found between bright regions and down-flows. Large Doppler widths correspond to strong velocity gradients.

A mechanism for crustal recycling on Venus

NASA Technical Reports Server (NTRS)

Lenardic, A.; Kaula, W. M.; Bindschadler, D. L.

1993-01-01

Entrainment of lower crust by convective mantle downflows is proposed as a crustal recycling mechanism on Venus. The mechanism is characterized by thin sheets of crust being pulled into the mantle by viscous flow stresses. Finite element models of crust/mantle interaction are used to explore tectonic conditions under which crustal entrainment may occur. The recycling scenarios suggested by the numerical models are analogous to previously studied problems for which analytic and experimental relationships assessing entrainment rates have been derived. We use these relationships to estimate crustal recycling rates on Venus. Estimated rates are largely determined by (1) strain rate at the crust/mantle interface (higher strain rate leads to greater entrainment); and (2) effective viscosity of the lower crust (viscosity closer to that of mantle lithosphere leads to greater entrainment). Reasonable geologic strain rates and available crustal flow laws suggest entrainment can recycle approximately equal 1 cu km of crust per year under favorable conditions.

Vorticity and divergence in the solar photosphere

NASA Technical Reports Server (NTRS)

Wang, YI; Noyes, Robert W.; Tarbell, Theodore D.; Title, Alan M.

1995-01-01

We have studied an outstanding sequence of continuum images of the solar granulation from Pic du Midi Observatory. We have calculated the horizontal vector flow field using a correlation tracking algorithm, and from this determined three scalar field: the vertical component of the curl; the horizontal divergence; and the horizontal flow speed. The divergence field has substantially longer coherence time and more power than does the curl field. Statistically, curl is better correlated with regions of negative divergence - that is, the vertical vorticity is higher in downflow regions, suggesting excess vorticity in intergranular lanes. The average value of the divergence is largest (i.e., outflow is largest) where the horizontal speed is large; we associate these regions with exploding granules. A numerical simulation of general convection also shows similar statistical differences between curl and divergence. Some individual small bright points in the granulation pattern show large local vorticities.

Design criterion for the heat-transfer coefficient in opposing flow, mixed convention heat transfer in a vertical tube

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joye, D.D.

1996-07-01

Mixed convection heat transfer in a vertical tube with opposing flow (downflow heating) was studied experimentally for Reynolds numbers ranging from about 1,000 to 30,000 at constant Grashof numbers ranging about 1{1/2} orders of magnitude under constant wall temperature (CWT) conditions. Three correlations developed for opposing mixed convection flows in vertical conduits predicted the data reasonably well, except near and into the asymptote region for which these equations were not designed. A critical Reynolds number is developed here, above which these equations can be used for design purposes regardless of the boundary condition. Below Re{sub crit}, the correlations, the asymptotemore » equation should be used for the CWT boundary condition, which is more prevalent in process situations than the uniform heat flux (UHF) boundary condition.« less

Late Holocene lava flow morphotypes of northern Harrat Rahat, Kingdom of Saudi Arabia: Implications for the description of continental lava fields

NASA Astrophysics Data System (ADS)

Murcia, H.; Németh, K.; Moufti, M. R.; Lindsay, J. M.; El-Masry, N.; Cronin, S. J.; Qaddah, A.; Smith, I. E. M.

2014-04-01

A "lava morphotype" refers to the recognizable and distinctive characteristics of the surface morphology of a lava flow after solidification, used in a similar way to a sedimentary facies. This classification method is explored on an example volcanic field in the Kingdom of Saudi Arabia, where copious lava outpourings may represent an important transition between monogenetic and flood basalt fields. Here, young and well-preserved mafic lava fields display a wide range of surface morphologies. We focussed on four post-4500 yrs. BP lava flow fields in northern Harrat Rahat (<10 Ma) and propose a framework for describing systematic changes in morphotypes down-flow. The morphotypes give insight into intrinsic and extrinsic parameters of emplacement, rheology and dominant flow behavior, as well as the occurrence and character of other lava structures. The Harrat Rahat lava flow fields studied extend up to 23 km from the source, and vary between 1-2 m and 12 m in thickness. Areas of the lava flow fields are between ˜32 and ˜61 km2, with individual flow field volumes estimated between ˜0.085 and ˜0.29 km3. They exhibit Shelly-, Slabby-, and Rubbly-pahoehoe, Platy-, Cauliflower-, and Rubbly-a'a, and Blocky morphotypes. Morphotypes reflect the intrinsic parameters of: composition, temperature, crystallinity and volatile-content/vesicularity; along with external influences, such as: emission mechanism, effusion rate, topography and slope control of flow velocity. One morphotype can transition to another in individual flow-units or lobes and they may dominate zones. Not all morphotypes were found in a single lava flow field. Pahoehoe morphotypes are related to the simple mechanical disaggregation of the crust, whereas a'a morphotypes are related to the transitional emergence and subsequent transitional disappearance of clinker. Blocky morphotypes result from fracturing and auto-brecciation. A'a morphotypes (i.e. platy-, cauliflower-, rubbly-a'a) dominate the lava flow field surfaces in northern Harrat Rahat, which suggests that core-dominated flows were predominant during flow movement. Lava structures are well-developed and well-preserved and some may be related to some morphotypes. Down-flow changes exhibit key illustrative and easy recognizable features in the lava flow fields and might provide insights into real-time monitoring of future flows in this region.

Venus tectonic styles and crustal differentiation

NASA Technical Reports Server (NTRS)

Kaula, W. M.; Lenardic, A.

1992-01-01

Two of the most important constraints are known from Pioneer Venus data: the lack of a system of spreading rises, indicating distributed deformation rather than plate tectonics; and the high gravity/topography ratio, indicating the absence of an asthenosphere. In addition, the high depth/diameter ratios of craters on Venus indicate that Venus probably has no more crust than Earth. The problems of the character of tectonics and crustal formation and recycling are closely coupled. Venus appears to lack a recycling mechanism as effective as subduction, but may also have a low rate of crustal differentiation because of a mantle convection pattern that is more distributed, less concentrated, than Earth's. Distributed convection, coupled with the nonlinear dependence of volcanism on heat flow, would lead to much less magmatism, despite only moderately less heat flow, compared to Earth. The plausible reason for this difference in convective style is the absence of water in the upper mantle of Venus. We have applied finite element modeling to problems of the interaction of mantle convection and crust on Venus. The main emphasis has been on the tectonic evolution of Ishtar Terra, as the consequence of convergent mantle flow. The early stage evolution is primarily mechanical, with crust being piled up on the down-stream side. Then the downflow migrates away from the center. In the later stages, after more than 100 m.y., thermal effects develop due to the insulating influence of the thickened crust. An important feature of this modeling is the entrainment of some crustal material in downflows. An important general theme in both convergent and divergent flows is that of mixing vs. stratification. Models of multicomponent solid-state flow obtain that lower-density crustal material can be entrained and recycled, provided that the ration of low-density to high-density material is small enough (as in subducted slabs on Earth). The same considerations should apply in upflows; a small percent of partial melt may be carried along with its matrix and never escape to the surface. Models that assume melt automatically rising to the crust and no entrainment or other mechanism of recycling lower-density material obtain oscillatory behavior, because it takes a long time for heat to build up enough to overcome a Mg-rich low-density residuum. However, these models develop much thicker crust than consistent with estimates from crater depth/diameter ratios.

Flow instabilities of magnetic flux tubes. IV. Flux storage in the solar overshoot region

NASA Astrophysics Data System (ADS)

Işık, E.; Holzwarth, V.

2009-12-01

Context: Flow-induced instabilities of magnetic flux tubes are relevant to the storage of magnetic flux in the interiors of stars with outer convection zones. The stability of magnetic fields in stellar interiors is of importance to the generation and transport of solar and stellar magnetic fields. Aims: We consider the effects of material flows on the dynamics of toroidal magnetic flux tubes located close to the base of the solar convection zone, initially within the overshoot region. The problem is to find the physical conditions in which magnetic flux can be stored for periods comparable to the dynamo amplification time, which is of the order of a few years. Methods: We carry out nonlinear numerical simulations to investigate the stability and dynamics of thin flux tubes subject to perpendicular and longitudinal flows. We compare the simulations with the results of simplified analytical approximations. Results: The longitudinal flow instability induced by the aerodynamic drag force is nonlinear in the sense that the growth rate depends on the perturbation amplitude. This result is consistent with the predictions of linear theory. Numerical simulations without friction show that nonlinear Parker instability can be triggered below the linear threshold of the field strength, when the difference in superadiabaticity along the tube is sufficiently large. A localised downflow acting on a toroidal tube in the overshoot region leads to instability depending on the parameters describing the flow, as well as the magnetic field strength. We determined ranges of the flow parameters for which a linearly Parker-stable magnetic flux tube is stored in the middle of the overshoot region for a period comparable to the dynamo amplification time. Conclusions: The longitudinal flow instability driven by frictional interaction of a flux tube with its surroundings is relevant to determining the storage time of magnetic flux in the solar overshoot region. The residence time for magnetic flux tubes with 2 × 1021 Mx in the convective overshoot layer can be comparable to the dynamo amplification time, provided that the average speed and the duration of an external downflow do not exceed about 50 m s -1 and 100 days, respectively, and that the lateral extension of the flow is smaller than about 10°. Appendix C and movies are only available in electronic form at http://www.aanda.org

Study of Critical Heat Flux and Two-Phase Pressure Drop Under Reduced Gravity

NASA Technical Reports Server (NTRS)

Abdollahian, Davood; Quintal, Joseph; Barez, Fred; Zahm, Jennifer; Lohr, Victor

1996-01-01

The design of the two-phase flow systems which are anticipated to be utilized in future spacecraft thermal management systems requires a knowledge of two-phase flow and heat transfer phenomena in reduced gravities. This program was funded by NASA headquarters in response to NRA-91-OSSA-17 and was managed by Lewis Research Center. The main objective of this program was to design and construct a two-phase test loop, and perform a series of normal gravity and aircraft trajectory experiments to study the effect of gravity on the Critical Heat Flux (CHF) and onset of instability. The test loop was packaged on two aircraft racks and was also instrumented to generate data for two-phase pressure drop. The normal gravity tests were performed with vertical up and downflow configurations to bound the effect of gravity on the test parameters. One set of aircraft trajectory tests was performed aboard the NASA DC-9 aircraft. These tests were mainly intended to evaluate the test loop and its operational performance under actual reduced gravity conditions, and to produce preliminary data for the test parameters. The test results were used to demonstrate the applicability of the normal gravity models for prediction of the two-phase friction pressure drop. It was shown that the two-phase friction multipliers for vertical upflow and reduced gravity conditions can be successfully predicted by the appropriate normal gravity models. Limited critical heat flux data showed that the measured CHF under reduced gravities are of the same order of magnitude as the test results with vertical upflow configuration. A simplified correlation was only successful in predicting the measured CHF for low flow rates. Instability tests with vertical upflow showed that flow becomes unstable and critical heat flux occurs at smaller powers when a parallel flow path exists. However, downflow tests and a single reduced gravity instability experiment indicated that the system actually became more stable with a parallel single-phase flow path. Several design modifications have been identified which will improve the system performance for generating reduced gravity data. The modified test loop can provide two-phase flow data for a range of operating conditions and can serve as a test bed for component evaluation.

Downflow limestone beds for treatment of net-acidic, oxic, iron-laden drainage from a flooded anthracite mine, Pennsylvania, USA: 2. Laboratory evaluation

USGS Publications Warehouse

Cravotta, C.A.; Ward, S.J.; Hammarstrom, J.M.

2008-01-01

Acidic mine drainage (AMD) containing elevated concentrations of dissolved iron and other metals can be neutralized to varying degrees by reactions with limestone in passive treatment systems. We evaluated the chemical and mineralogical characteristics and the effectiveness of calcitic and dolomitic limestone for the neutralization of net-acidic, oxic, iron-laden AMD from a flooded anthracite mine. The calcitic limestone, with CaCO3 and MgCO3 contents of 99.8 and <0.1 wt%, respectively, and the dolomitic limestone, with CaCO3 and MgCO3 contents of 60.3 and 40.2 wt%, were used to construct a downflow treatment system in 2003 at the Bell Mine, a large source of AMD and baseflow to the Schuylkill River in the Southern Anthracite Coalfield, in east-central Pennsylvania. In the winter of 2002-2003, laboratory neutralization-rate experiments evaluated the evolution of effluent quality during 2 weeks of continuous contact between AMD from the Bell Mine and the crushed calcitic or dolomitic limestone in closed, collapsible containers (cubitainers). The cubitainer tests showed that: (1) net-alkaline effluent could be achieved with detention times greater than 3 h, (2) effluent alkalinities and associated dissolution rates were equivalent for uncoated and Fe(OH)3-coated calcitic limestone, and (3) effluent alkalinities and associated dissolution rates for dolomitic limestone were about half those for calcitic limestone. The dissolution rate data for the cubitainer tests were used with data on the volume of effuent and surface area of limestone in the treatment system at the Bell Mine to evaluate the water-quality data for the first 1.5 years of operation of the treatment system. These rate models supported the interpretation of field results and indicated that treatment benefits were derived mainly from the dissolution of calcitic limestone, despite a greater quantity of dolomitic limestone within the treatment system. The dissolution-rate models were extrapolated on a decadal scale to indicate the expected decreases in the mass of limestone and associated alkalinities resulting from the long-term reaction of AMD with the treatment substrate. The models indicated the calcitic limestone would need to be replenished approaching the 5-year anniversary of treatment operations to maintain net-alkaline effluent quality. ?? 2008 Springer-Verlag.

Spatial gradients in stream power and the implications for lateral and downstream transport of material during the 2013 Floods in Colorado and 2011 Irene Floods in Vermont, USA

NASA Astrophysics Data System (ADS)

Gartner, J. D.; Renshaw, C. E.; Magilligan, F. J.; Buraas, E. M.; Dethier, E.; Dade, W. B.

2014-12-01

Classic approaches to understand sediment transport and channel-hillslope coupling focus on magnitudes of forces at a point location or reach. Yet often overlooked are downstream gradients in forces along a river. Here we show a physical rationale supported by field evidence that downstream spatial gradients in sediment transport capacity affect lateral exchange of material in the form of landslides, bank failures and floodplain deposition. Taking advantage of the strong signals of near-channel deposition and erosion during the record-high 2011 Irene floods in Vermont and 2013 floods in Colorado, USA, we test if these spatial gradients can predict geomorphic response in flood events. Total stream power, an indicator of total sediment transport capacity, was mapped using GIS analysis along the Saxtons River (190 km2) and West Branch of White River (112 km2) in Vermont and Fourmile Creek (20 km2) and an unnamed creek on Mt Sanitas (7 km2) in Boulder, CO. These mountainous streams exhibit reach slopes of 0.5 to > 10%, with less steep reaches interspersed among steeper reaches. Near-channel erosion and deposition were quantified along 52 river km by pre/post satellite imagery, field surveys, and, when available, differencing of pre/post topography measured by aerial LiDAR. Zones of abundant mass wasting inputs—up to 11,000 m3 per km—were generally distinct from zones of abundant floodplain deposition—up to 30,000 m3 per km. Spatial patterns indicate that zones of abundant mass wasting into the channels align approximately with zones of down-flow increasing stream power. These reaches can convey material delivered from upstream plus additional lateral inputs of sediment. Conversely, reaches of abundant lateral flux out of the channel via near-channel deposition occur predominantly where mapped total stream power declines in the down-flow direction. These reaches appear unable to convey material supplied from upstream, which induces lateral deposition. The demonstrated interaction between downstream and lateral fluxes of material provides insight on physical controls on broad-scale geomorphic processes at channel margins as well as the sources and fates of matter transported by rivers, with implications for flood recovery and long-term river management.

Borehole-geophysical investigation of the University of Connecticut landfill, Storrs, Connecticut

USGS Publications Warehouse

Johnson, Carole D.; Haeni, F.P.; Lane, John W.; White, Eric A.

2002-01-01

A borehole-geophysical investigation was conducted to help characterize the hydrogeology of the fractured-rock aquifer and the distribution of unconsolidated glacial deposits near the former landfill and chemical waste-disposal pits at the University of Connecticut in Storrs, Connecticut. Eight bedrock boreholes near the landfill and three abandoned domestic wells located nearby were logged using conventional and advanced borehole-geophysical methods from June to October 1999. The conventional geophysical-logging methods included caliper, gamma, fluid temperature, fluid resistivity, and electromagnetic induction. The advanced methods included deviation, optical and acoustic imaging of the borehole wall, heat-pulse flowmeter, and directional radar reflection. Twenty-one shallow piezometers (less than 50-feet deep) were logged with gamma and electromagnetic induction tools to delineate unconsolidated glacial deposits. Five additional shallow bedrock wells were logged with conventional video camera, caliper, electromagnetic induction, and fluid resistivity and temperature tools. The rock type, foliation, and fracturing of the site were characterized from high-resolution optical-televiewer (OTV) images of rocks penetrated by the boreholes. The rocks are interpreted as fine- to medium-grained quartz-feldspar-biotite-garnet gneiss and schist with local intrusions of quartz diorite and pegmatite and minor concentrations of sulfide mineralization similar to rocks described as the Bigelow Brook Formation on regional geologic maps. Layers containing high concentrations of sulfide minerals appear as high electrical conductivity zones on electromagnetic-induction and borehole-radar logs. Foliation in the rocks generally strikes to the northeast-southwest and dips to the west, consistent with local outcrop observations. The orientation of foliation and small-scale gneissic layering in the rocks, however, varies locally and with depth in some of the boreholes. In two of the boreholes, the foliation strikes predominantly to the northwest and dips to the northeast. Although small-scale faults and lithologic discontinuities were observed in the OTV data, no large-scale faults were observed that appear on regional geologic maps. Fractures were located and characterized through the use of conventional geophysical, OTV, acoustic-televiewer (ATV), and borehole-radar logs. The orientation of fractures varies considerably across the site; some fractures are parallel to the foliation, whereas others cross-cut the foliation. Many of the transmissive fractures in the bedrock boreholes strike about N170?E and N320?E with dips of less than 45?. Other transmissive fractures strike about N60?E with dips of more than 60?. Most of the transmissive fractures in the domestic wells strike about N60?E and N22?E with dips of more than 45?. The strike of N60?E is parallel to the trend of a thrust fault that appears on regional geologic maps. Vertical flow in the boreholes was measured with the heat-pulse flowmeter under ambient and (or) pumping conditions. Results of ATV, OTV, and conventional logs were used to locate specific zones for flowmeter testing. Ambient downflow was measured in three boreholes, ambient upflow was measured in two other boreholes, and both ambient downflow and upflow were measured in a sixth borehole. The other five bedrock boreholes and domestic wells did not have measurable vertical flow. The highest rate of ambient flow was measured in the background borehole in which upflow and downflow converged and exited the borehole at a fracture zone near a depth of 62 feet. Ambient flow of about 340 gallons per day was measured. In the other five wells, ambient flow of about 20 to 35 gallons per day was measured. Under low-rate pumping (0.25 to 1 gallon per minute), one to six inflow zones were identified in each well. Usually the fractures that are active under ambient conditions contribute to the well under pumping conditions. To prevent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zou, P.; Fang, C.; Chen, P. F.

Solar filaments can be formed via chromospheric evaporation followed by condensation in the corona or by the direct injection of cool plasma from the chromosphere to the corona. We here confirm with high-resolution H α data observed by the 1.6 m New Solar Telescope of the Big Bear Solar Observatory on 2015 August 21 that an active-region filament is maintained by the continuous injection of cold chromospheric plasma. We find that the filament is rooted along a bright ridge in H α , which corresponds to the intersection of a magnetic quasi-separatrix layer with the solar surface. This bright ridgemore » consists of many small patches whose sizes are comparable to the width of the filament threads. It is found that upflows originate from the brighter patches of the ridge, whereas the downflows move toward the weaker patches of the ridge. The whole filament is composed of two opposite-direction streams, implying that longitudinal oscillations are not the only cause of the counterstreamings, and unidirectional siphon flows with alternative directions are another possibility.« less

Magnetic pattern at supergranulation scale: the void size distribution

NASA Astrophysics Data System (ADS)

Berrilli, F.; Scardigli, S.; Del Moro, D.

2014-08-01

The large-scale magnetic pattern observed in the photosphere of the quiet Sun is dominated by the magnetic network. This network, created by photospheric magnetic fields swept into convective downflows, delineates the boundaries of large-scale cells of overturning plasma and exhibits "voids" in magnetic organization. These voids include internetwork fields, which are mixed-polarity sparse magnetic fields that populate the inner part of network cells. To single out voids and to quantify their intrinsic pattern we applied a fast circle-packing-based algorithm to 511 SOHO/MDI high-resolution magnetograms acquired during the unusually long solar activity minimum between cycles 23 and 24. The computed void distribution function shows a quasi-exponential decay behavior in the range 10-60 Mm. The lack of distinct flow scales in this range corroborates the hypothesis of multi-scale motion flows at the solar surface. In addition to the quasi-exponential decay, we have found that the voids depart from a simple exponential decay at about 35 Mm.

Sorbent control of trace metals in sewage sludge combustion and incineration

NASA Astrophysics Data System (ADS)

Naruse, I.; Yao, H.; Mkilaha, I. S. N.

2003-05-01

Coal and wastes combustion have become an important issue not only in terms of energy generation but also environmental conservation. The need for alternative fuels and wastes management has made the two energy sources of importance. However, the utilization of the two is faced with problems of impurity trace metals in the fuel. These metals usually speciate during combustion or incineration leading to generation of fumes and subsequently particles. This paper reports on the study aimed at understanding the speciation of trace metals and their emission from combustion systems as particulates. Experiments carried out using a down-flow furnace and theoretical study carried out using lead, chromium and cadmium as basic metals had shown that their speciation and subsequent emission is controlled by both chemical composition and physical properties of the fuel. The physical and chemical and physical properties of the fuel and their respective compounds and the operating conditions of the incineration and combustion system control the enrichment of the particles with trace metals.

Modeling the Solar Convective Dynamo and Emerging Flux

NASA Astrophysics Data System (ADS)

Fan, Y.

2017-12-01

Significant advances have been made in recent years in global-scale fully dynamic three-dimensional convective dynamo simulations of the solar/stellar convective envelopes to reproduce some of the basic features of the Sun's large-scale cyclic magnetic field. It is found that the presence of the dynamo-generated magnetic fields plays an important role for the maintenance of the solar differential rotation, without which the differential rotation tends to become anti-solar (with a faster rotating pole instead of the observed faster rotation at the equator). Convective dynamo simulations are also found to produce emergence of coherent super-equipartition toroidal flux bundles with a statistically significant mean tilt angle that is consistent with the mean tilt of solar active regions. The emerging flux bundles are sheared by the giant cell convection into a forward leaning loop shape with its leading side (in the direction of rotation) pushed closer to the strong downflow lanes. Such asymmetric emerging flux pattern may lead to the observed asymmetric properties of solar active regions.

Interaction of pyroclastic density currents with human settlements: Evidence from ancient Pompeii

NASA Astrophysics Data System (ADS)

Gurioli, Lucia; Pareschi, M. Teresa; Zanella, Elena; Lanza, Roberto; Deluca, Enrico; Bisson, Marina

2005-06-01

Integrating field observations and rock-magnetic measurements, we report how a turbulent pyroclastic density current interacted with and moved through an urban area. The data are from the most energetic, turbulent pyroclastic density current of the A.D. 79 eruption of Vesuvius, Italy, which partially destroyed the Roman city of Pompeii. Our results show that the urban fabric was able to divide the lower portion of the current into several streams that followed the city walls and the intracity roads. Vortices, revealed by upstream particle orientations and decreases in deposit temperature, formed downflow of obstacles or inside cavities. Although these perturbations affected only the lower part of the current and were localized, they could represent, in certain cases, cooler zones within which chances of human survival are increased. Our integrated field data for pyroclastic density current temperature and flow direction, collected for the first time across an urban environment, enable verification of coupled thermodynamic numerical models and their hazard simulation abilities.

Sunspot dynamics - Gravitational draining - A cooling mechanism

NASA Technical Reports Server (NTRS)

Schatten, K. H.

1981-01-01

The inward and downward flow of cooled material below sunspots is considered as a possible explanation of the stability, temperature and heat flow characteristics of sunspots. It is suggested that the flow of material inwards towards the center of the sunspot and then downwards towards the center of the sun through magnetic field conduits plays a role in the cooling of sunspots as it does in pores and magnetic knots, although due to the larger size of a sunspot the downflow takes place below the photosphere. In this view, the inflow and cooling of sunspots are sustained by the release of energy by the convecting gas, which then becomes cooler and denser as it returns to the heat source. The lack of a bright ring around sunspots is explained by the entrainment of upward moving heat flux by the downward moving gases. The temperature and density distributions predicted by the present model are shown to be satisfactory agreement with the empirical model of Van't Veer (Tandberg-Hansen, 1966).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nash, C.; Williams, M.; Restivo, M.

All prior testing with SuperLig® 639 has been done with the aqueous concentration of LAW at ~5 M [Na+], where the resin sinks, and can be used in a conventional down-flow column orientation. However, the aqueous LAW stream from the Waste Treatment Plant is expected to be ~8 M [Na+]. The resin would float in this higher density liquid, potentially disrupting the ability to achieve a good decontamination due to poor packing of the resin that leads to channeling. Testing was completed with a higher salt concentration in the feed simulant (7.8 M [Na+]) in an engineering-scale apparatus with twomore » columns, each containing ~0.9 L of resin. Testing of this system used a simulant of the LAW solution, and substituted ReO4 - as a surrogate for TcO4 -. Results were then compared using computer modeling. Bench-scale testing was also performed, and examined an unconstrained resin bed, while engineering-scale tests used both constrained and unconstrained beds in a two-column, lead and lag sequential arrangement.« less

Effects of Gravity on Cocurrent Two-Phase Gas-Liquid Flows Through Packed Columns

NASA Technical Reports Server (NTRS)

Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro

2001-01-01

This work presents the experimental results of research on the influence of gravity on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid two-phase flow through packed columns. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under reduced gravity conditions compared to normal gravity cocurrent down-flow. This is illustrated by comparing the flow regime transitions found in reduced gravity with the transitions predicted by Talmor. Next, the effect of gravity on the total pressure drop in a packed column is shown to depend on the flow regime. The difference is roughly equivalent to the liquid static head for bubbly flow but begins to decrease at the onset of pulse flow. As the spray flow regime is approached by increasing the gas to liquid ratio, the effect of gravity on pressure drop becomes negligible. Finally, gravity tends to suppress the amplitude of each pressure pulse. An example of this phenomenon is presented.

The Anatomy of the Blue Dragon: Changes in Lava Flow Morphology and Physical Properties Observed in an Open Channel Lava Flow as a Planetary Analogue

NASA Astrophysics Data System (ADS)

Sehlke, A.; Kobs-Nawotniak, S. E.; Hughes, S. S.; Sears, D. W. G.; Downs, M.; Whittington, A. G.; Lim, D. S. S.; Heldmann, J. L.

2017-12-01

Lava terrains on other planets and moons exhibit morphologies similar to those found on Earth, such as smooth pāhoehoe transitioning to rough `a`ā terrains based on the viscosity - strain rate relationship of the lava. Therefore, the morphology of lava flows is governed by eruptive conditions such as effusion rate, underlying slope, and the fundamental thermo-physical properties of the lava, including temperature (T), composition (X), viscosity (η), fraction of crystals (φc) and vesicles (φb), as well as bulk density (ρ). These textural and rheological changes were previously studied for Hawaiian lava, where the lava flow started as channelized pāhoehoe and transitioned into `a`ā, demonstrating a systematic trend in T, X, η, φc, φb, and ρ. NASA's FINESSE focuses on Science and Exploration through analogue research. One of the field sites is Craters of the Moon, Idaho. We present field work done at a 3.0 km long lava flow belonging to the Blue Dragon lavas erupted from a chain of spatter cones, which then coalesced into channelized flows. We acquired UAV imagery along the entire length of the flow, and generated a high resolution DTM of 5 cm/pixel, from which we derived height profiles and surface roughness values. Field work included mapping the change in surface morphology and sample collection every 150 meters. In the laboratory, we measured φc, φb, and ρ for all collected samples. Viscosity measurements were carried out by concentric cylinder viscometry at subliquidus temperatures between 1310ºC to 1160ºC to study the rheology of the lava, enabling us to relate changes in flow behavior to T and φc. Our results are consistent with observations made for Hawaiian lava, including increasing bulk density downflow, and porosity changing from connected to isolated pore space. Crystallinity increases downflow, and the transition from pāhoehoe to `a`ā occurs between 1230ºC to 1150ºC, which is prompted by nucleation and growth of plagioclase microcrystals, strongly increasing the viscosity of the lava several orders of magnitude. The results of this study allows us to correlate T, X, η, φc, φb, and ρ to the lava flow morphology expressed as surface roughness, which can then be used as a tool to infer these physical properties of the rocks for open channel lava flows on other airless bodies, such as the Moon and Mercury, based on DTMs.

Investigation of Critical Heat Flux in Reduced Gravity Using Photomicrographic Techniques

NASA Technical Reports Server (NTRS)

Mudawar, Issam; Zhang, Hui

2003-01-01

Experiments were performed to examine the effects of body force on flow boiling critical heat flux (CHF). FC-72 was boiled along one wall of a transparent rectangular flow channel that permitted photographic study of the vapor-liquid interface just prior to CHF. High-speed video imaging techniques were used to identify dominant CHF mechanisms corresponding to different flow orientations and liquid velocities. Six different CHF regimes were identified: Wavy Vapor Layer, Pool Boiling, Stratification, Vapor Counterflow, Vapor Stagnation, and Separated Concurrent Vapor Flow. CHF showed significant sensitivity to orientation for flow velocities below 0.2 m/s, where extremely low CHF values where measured, especially with downward-facing heated wall and downflow orientations. High flow velocities dampened the effects of orientation considerably. The CHF data were used to assess the suitability of previous CHF models and correlations. It is shown the Interfacial Lift-off Model is very effective at predicting CHF for high velocities at all orientations. The flooding limit, on the other hand, is useful at estimating CHF at low velocities and for downflow orientations. A new method consisting of three dimensionless criteria is developed for determining the minimum flow velocity required to overcome body force effects on near-saturated flow boiling CHF. Vertical upflow boiling experiments were performed in pursuit of identifying the trigger mechanism for subcooled flow boiling CHF. While virtually all prior studies on flow boiling CHF concern the prediction or measurement of conditions that lead to CHF, this study was focused on events that take place during the CHF transient. High-speed video imaging and photomicrographic techniques were used to record the transient behavior of interfacial features from the last steady-state power level before CHF until the moment of power cut-off following CHF. The video records show the development of a wavy vapor layer which propagates along the heated wall, permitting cooling prior to CHF only in wetting fronts corresponding to the wave troughs. Image analysis software was developed to estimate void fraction from the individual video images. The void fraction records for subcooled flow boiling show the CHF transient is accompanied by gradual lift-off of wetting fronts culminating in some maximum vapor layer mean thickness, following which the vapor layer begins to thin down as the transition to film boiling ensues. This study proves the Interfacial Lift-off Model, which has been validated for near-saturated flow boiling CHF, is equally valid for subcooled conditions.

High Resolution Observations of Solar Quiescent Prominences with the Hinode Solar Optical Telescope: an Open Challenge to 21st Century Ground-based Solar Telescopes (Invited)

NASA Astrophysics Data System (ADS)

Berger, T. E.

2009-12-01

The Solar Optical Telescope (SOT) on the Japanese Hinode satellite is a 0.5-meter diameter Gregorian solar telescope in a 600 km Sun-synchronous orbit. The telescope achieves diffraction-limited imaging with no atmospheric seeing in a wavelength range from 380 nm to 660 nm. Using both the Broadband Filter Imager (BFI) Ca II H-line channel at 389.6 nm and the tunable Narrowband Filter Imager (NFI) H-alpha channel at 656.3 nm we have observed many quiescent solar prominences since the satellite launch in September 2006. The excellent optical quality and low scattering of the SOT telescope combined with the lack of atmospheric scattering and seeing enables us to capture multi-hour diffraction-limited movies of quiescent prominences above the limb that achieve 200 km spatial resolution and 15--30 second temporal resolution. These SOT observations have led to the discovery of new flows in the solar outer atmosphere in the form of buoyant small-scale (2--6 Mm) plumes and large-scale (10--50 Mm) "bubbles" or arches that originate below quiescent prominences and rise with speeds of 10--30 km/sec to heights of 10--30+ Mm above the solar limb. In this talk we review the kinematic properties of these new flows in combination with the long-observed filamentary downflows to show that quisecent prominences are not magnetostatic structures "suspended against gravity" but are rather entirely dynamic structures in which mass is continually drained in the downflows while being resupplied largely by condensation from the coronal cavity above and episodic buoyant flows from below. The Hinode/SOT instrument has definitively shown the value of flying high-resolution visible-light solar telescopes in space by acheiving in its first six months what had been a long-standing goal of ground-based solar prominence research for the past 50 years. However many key quiescent prominence characteristics cannot be measured by the limited instrumentation on the Hinode satellite. Primary among these is vector magnetic field in prominences at high spatial and temporal resolution and the thermodynamic and magnetic characteristics of the new plume and bubble flows. It is hoped that the new generation of adaptive-optics ground-based telescopes such as the 1.6-m NST can make progress in these areas while we await the next solar space telescope missions.

Internal tides in the Northern Gulf of California

NASA Astrophysics Data System (ADS)

Filonov, Anatoliy E.; LavíN, M. F.

2003-05-01

The characteristics of the internal tide in the Northern Gulf of California are described using data from two moored arrays of temperature and current sensors, one for summer and one for winter, located between Angel de la Guarda Island and the mainland. From the summer six-sensor mooring it was found that: (1) the current fluctuations are dominated by the semidiurnal frequency band, while the quarterdiurnal frequency dominated the temperature fluctuations. (2) The baroclinic semidiurnal horizontal current fluctuations are aligned with the gulf axis, and have amplitudes of 10-15 cm s-1; the vertical displacements reached 4 m in this frequency band. (3) The vertical modal structure for the temperature and velocity oscillations was dominated by the first and third modes. (4) The energy of the semidiurnal internal tide is 45% of that of the barotropic tide. (5) Vertical wave number spectra showed slightly asymmetric peaks in the high wave number components, indicating that their downflowing energy is larger than that flowing upward. From the winter two-sensor mooring, it was found that the vertical oscillations were mainly semidiurnal, with root mean square amplitudes of 7 m.

Deep burial dolomitization driven by plate collision: Evidence from strontium-isotopes of Jurassic Arab IV dolomites from offshore Qatar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vahrenkamp, V.C.; Taylor, S.R.

The use of strontium-isotope ratios of dolomites to constrain timing and mechanism of diagenesis has been investigated on Jurassic Arab IV dolomites from offshore Qatar. Reservoir quality is determined by two types of dolomites, which were differentiated geochemically (cathodoluminescence, fluid inclusions, and carbon and oxygen stable isotopes): (1) stratigraphically concordant sucrosic dolomites with high porosity formed during early near-surface diagenesis (Jurassic) and (2) stratigraphically discordant cylindrical bodies of massive, porosity-destroying dolomites formed late during deep burial diagenesis (Eocene-Pliocene). Detailed Sr-isotope analysis of dolomites from the Arab IV confirms an Early Jurassic age of the sucrosic, high porosity dolomites ({sup 87}Sr/{supmore » 86}SR = 0.70707 for NBS 987 = 0.71024) with magnesium and strontium being derived from Jurassic seawater. Late Tertiary compressional orogeny of the Zagros belt to the north is proposed to have caused large-scale squeezing of fluids from the pore system of sedimentary rocks. A regional deep fluid flow system developed dissolving infra-Cambrian evaporites upflow and causing large-scale deep burial dolomitization downflow.« less

Real-time measurement of dust in the workplace using video exposure monitoring: Farming to pharmaceuticals

NASA Astrophysics Data System (ADS)

Walsh, P. T.; Forth, A. R.; Clark, R. D. R.; Dowker, K. P.; Thorpe, A.

2009-02-01

Real-time, photometric, portable dust monitors have been employed for video exposure monitoring (VEM) to measure and highlight dust levels generated by work activities, illustrate dust control techniques, and demonstrate good practice. Two workplaces, presenting different challenges for measurement, were used to illustrate the capabilities of VEM: (a) poultry farming activities and (b) powder transfer operations in a pharmaceutical company. For the poultry farm work, the real-time monitors were calibrated with respect to the respirable and inhalable dust concentrations using cyclone and IOM reference samplers respectively. Different rankings of exposure for typical activities were found on the small farm studied here compared to previous exposure measurements at larger poultry farms: these were mainly attributed to the different scales of operation. Large variations in the ratios of respirable, inhalable and real-time monitor TWA concentrations of poultry farm dust for various activities were found. This has implications for the calibration of light-scattering dust monitors with respect to inhalable dust concentration. In the pharmaceutical application, the effectiveness of a curtain barrier for dust control when dispensing powder in a downflow booth was rapidly demonstrated.

Emission of magnetosound from MHD-unstable shear flow boundaries

NASA Astrophysics Data System (ADS)

Turkakin, H.; Rankin, R.; Mann, I. R.

2016-09-01

The emission of propagating MHD waves from the boundaries of flow channels that are unstable to the Kelvin-Helmholtz Instability (KHI) in magnetized plasma is investigated. The KHI and MHD wave emission are found to be two competing processes. It is shown that the fastest growing modes of the KHI surface waves do not coincide with efficient wave energy transport away from a velocity shear boundary. MHD wave emission is found to be inefficient when growth rates of KHI surface waves are maximum, which corresponds to the situation where the ambient magnetic field is perpendicular to the flow channel velocity vector. The efficiency of wave emission increases with increasing magnetic field tension, which in Earth's magnetosphere likely dominates along the nightside magnetopause tailward of the terminator, and within earthward Bursty Bulk Flows (BBFs) in the inner plasma sheet. MHD wave emission may also dominate in Supra-Arcade Downflows (SADs) in the solar corona. Our results suggest that efficient emission of propagating MHD waves along BBF and SAD boundaries can potentially explain observations of deceleration and stopping of BBFs and SADs.

Thermal Structure of Supra-Arcade Plasma in Two Solar Flares

NASA Technical Reports Server (NTRS)

Reeves, Katharine K.; Savage, Sabrina; McKenzie, David E.; Weber, Mark A.

2012-01-01

In this work, we use Hinode/XRT and SDO/AIA data to determine the thermal structure of supra-arcade plasma in two solar flares. The first flare is a Ml.2 flare that occurred on November 5, 2010 on the east limb. This flare was one of a series of flares from AR 11121, published in Reeves & Golub (2011). The second flare is an XI.7 flare that occurred on January 27, 2012 on the west limb. This flare exhibits visible supra-arcade downflows (SADs), where the November 2010 flare does not. For these two flares we combine XRT and AlA data to calculate DEMs of each pixel in the supra-arcade plasma, giving insight into the temperature and density structures in the fan of plasma above the post-flare arcade. We find in each case that the supra-arcade plasma is around 10 MK, and there is a marked decrease in the emission measure in the SADs. We also compare the DEMs calculated with the combined AIA/XRT dataset to those calculated using AIA alone.

A simple, analytic 3-dimensional downburst model based on boundary layer stagnation flow

NASA Technical Reports Server (NTRS)

Oseguera, Rosa M.; Bowles, Roland L.

1988-01-01

A simple downburst model is developed for use in batch and real-time piloted simulation studies of guidance strategies for terminal area transport aircraft operations in wind shear conditions. The model represents an axisymmetric stagnation point flow, based on velocity profiles from the Terminal Area Simulation System (TASS) model developed by Proctor and satisfies the mass continuity equation in cylindrical coordinates. Altitude dependence, including boundary layer effects near the ground, closely matches real-world measurements, as do the increase, peak, and decay of outflow and downflow with increasing distance from the downburst center. Equations for horizontal and vertical winds were derived, and found to be infinitely differentiable, with no singular points existent in the flow field. In addition, a simple relationship exists among the ratio of maximum horizontal to vertical velocities, the downdraft radius, depth of outflow, and altitude of maximum outflow. In use, a microburst can be modeled by specifying four characteristic parameters, velocity components in the x, y and z directions, and the corresponding nine partial derivatives are obtained easily from the velocity equations.

Turbulent Compressible Convection with Rotation. 2; Mean Flows and Differential Rotation

NASA Technical Reports Server (NTRS)

Brummell, Nicholas H.; Hurlburt, Neal E.; Toomre, Juri

1998-01-01

The effects of rotation on turbulent, compressible convection within stellar envelopes are studied through three-dimensional numerical simulations conducted within a local f-plane model. This work seeks to understand the types of differential rotation that can be established in convective envelopes of stars like the Sun, for which recent helioseismic observations suggest an angular velocity profile with depth and latitude at variance with many theoretical predictions. This paper analyzes the mechanisms that are responsible for the mean (horizontally averaged) zonal and meridional flows that are produced by convection influenced by Coriolis forces. The compressible convection is considered for a range of Rayleigh, Taylor, and Prandtl (and thus Rossby) numbers encompassing both laminar and turbulent flow conditions under weak and strong rotational constraints. When the nonlinearities are moderate, the effects of rotation on the resulting laminar cellular convection leads to distinctive tilts of the cell boundaries away from the vertical. These yield correlations between vertical and horizontal motions that generate Reynolds stresses that can drive mean flows, interpretable as differential rotation and meridional circulations. Under more vigorous forcing, the resulting turbulent convection involves complicated and contorted fluid particle trajectories, with few clear correlations between vertical and horizontal motions, punctuated by an evolving and intricate downflow network that can extend over much of the depth of the layer. Within such networks are some coherent structures of vortical downflow that tend to align with the rotation axis. These yield a novel turbulent alignment mechanism, distinct from the laminar tilting of cellular boundaries, that can provide the principal correlated motions and thus Reynolds stresses and subsequently mean flows. The emergence of such coherent structures that can persist amidst more random motions is a characteristic of turbulence with symmetries broken by rotation and stratification. Such structure is here found to play a crucial role in defining the mean zonal and meridional flows that coexist with the convection. Though they are subject to strong inertial oscillations, the strength and type of the mean flows are determined by a combination of the laminar tilting and the turbulent alignment mechanisms. Varying the parameters produces a wide range of mean motions. Among these, some turbulent solutions exhibit a mean zonal velocity profile that is nearly constant with depth, much as deduced by helioseismology at midlatitudes within the Sun. The solutions exhibit a definite handedness, with the direction of the persistent mean flows often prescribing a spiral with depth near the boundaries, also in accord with helioseismic deductions. The mean helicity has a profile that is positive in the upper portion of the domain and negative in the lower portion, a property bearing on magnetic dynamo processes that may be realized within such rotating layers of turbulent convection.

Disentangling flows in the solar transition region

NASA Astrophysics Data System (ADS)

Zacharias, P.; Hansteen, V. H.; Leenaarts, J.; Carlsson, M.; Gudiksen, B. V.

2018-06-01

Context. The measured average velocities in solar and stellar spectral lines formed at transition region temperatures have been difficult to interpret. The dominant redshifts observed in the lower transition region naturally leads to the question of how the upper layers of the solar (and stellar) atmosphere can be maintained. Likewise, no ready explanation has been made for the average blueshifts often found in upper transition region lines. However, realistic three-dimensional radiation magnetohydrodynamics (3D rMHD) models of the solar atmosphere are able to reproduce the observed dominant line shifts and may thus hold the key to resolve these issues. Aims: These new 3D rMHD simulations aim to shed light on how mass flows between the chromosphere and corona and on how the coronal mass is maintained. These simulations give new insights into the coupling of various atmospheric layers and the origin of Doppler shifts in the solar transition region and corona. Methods: The passive tracer particles, so-called corks, allow the tracking of parcels of plasma over time and thus the study of changes in plasma temperature and velocity not only locally, but also in a co-moving frame. By following the trajectories of the corks, we can investigate mass and energy flows and understand the composition of the observed velocities. Results: Our findings show that most of the transition region mass is cooling. The preponderance of transition region redshifts in the model can be explained by the higher percentage of downflowing mass in the lower and middle transition region. The average upflows in the upper transition region can be explained by a combination of both stronger upflows than downflows and a higher percentage of upflowing mass. The most common combination at lower and middle transition region temperatures are corks that are cooling and traveling downward. For these corks, a strong correlation between the pressure gradient along the magnetic field line and the velocity along the magnetic field line has been observed, indicating a formation mechanism that is related to downward propagating pressure disturbances. Corks at upper transition region temperatures are subject to a rather slow and highly variable but continuous heating process. Conclusions: Corks are shown to be an essential tool in 3D rMHD models in order to study mass and energy flows. We have shown that most transition region plasma is cooling after having been heated slowly to upper transition region temperatures several minutes before. Downward propagating pressure disturbances are identified as one of the main mechanisms responsible for the observed redshifts at transition region temperatures. The movie associated to Fig. 3 is available at http://www.aanda.org

Comparison of solar photospheric bright points between Sunrise observations and MHD simulations

NASA Astrophysics Data System (ADS)

Riethmüller, T. L.; Solanki, S. K.; Berdyugina, S. V.; Schüssler, M.; Martínez Pillet, V.; Feller, A.; Gandorfer, A.; Hirzberger, J.

2014-08-01

Bright points (BPs) in the solar photosphere are thought to be the radiative signatures (small-scale brightness enhancements) of magnetic elements described by slender flux tubes or sheets located in the darker intergranular lanes in the solar photosphere. They contribute to the ultraviolet (UV) flux variations over the solar cycle and hence may play a role in influencing the Earth's climate. Here we aim to obtain a better insight into their properties by combining high-resolution UV and spectro-polarimetric observations of BPs by the Sunrise Observatory with 3D compressible radiation magnetohydrodynamical (MHD) simulations. To this end, full spectral line syntheses are performed with the MHD data and a careful degradation is applied to take into account all relevant instrumental effects of the observations. In a first step it is demonstrated that the selected MHD simulations reproduce the measured distributions of intensity at multiple wavelengths, line-of-sight velocity, spectral line width, and polarization degree rather well. The simulated line width also displays the correct mean, but a scatter that is too small. In the second step, the properties of observed BPs are compared with synthetic ones. Again, these are found to match relatively well, except that the observations display a tail of large BPs with strong polarization signals (most likely network elements) not found in the simulations, possibly due to the small size of the simulation box. The higher spatial resolution of the simulations has a significant effect, leading to smaller and more numerous BPs. The observation that most BPs are weakly polarized is explained mainly by the spatial degradation, the stray light contamination, and the temperature sensitivity of the Fe i line at 5250.2 Å. Finally, given that the MHD simulations are highly consistent with the observations, we used the simulations to explore the properties of BPs further. The Stokes V asymmetries increase with the distance to the center of the mean BP in both observations and simulations, consistent with the classical picture of a production of the asymmetry in the canopy. This is the first time that this has been found also in the internetwork. More or less vertical kilogauss magnetic fields are found for 98% of the synthetic BPs underlining that basically every BP is associated with kilogauss fields. At the continuum formation height, the simulated BPs are on average 190 K hotter than the mean quiet Sun, the mean BP field strength is found to be 1750 G, and the mean inclination is 17°, supporting the physical flux-tube paradigm to describe BPs. On average, the synthetic BPs harbor downflows increasing with depth. The origin of these downflows is not yet understood very well and needs further investigation.

Combination of granular activated carbon adsorption and deep-bed filtration as a single advanced wastewater treatment step for organic micropollutant and phosphorus removal.

PubMed

Altmann, Johannes; Rehfeld, Daniel; Träder, Kai; Sperlich, Alexander; Jekel, Martin

2016-04-01

Adsorption onto granular activated carbon (GAC) is an established technology in water and advanced wastewater treatment for the removal of organic substances from the liquid phase. Besides adsorption, the removal of particulate matter by filtration and biodegradation of organic substances in GAC contactors has frequently been reported. The application of GAC as both adsorbent for organic micropollutant (OMP) removal and filter medium for solids retention in tertiary wastewater filtration represents an energy- and space saving option, but has rarely been considered because high dissolved organic carbon (DOC) and suspended solids concentrations in the influent of the GAC adsorber put a significant burden on this integrated treatment step and might result in frequent backwashing and unsatisfactory filtration efficiency. This pilot-scale study investigates the combination of GAC adsorption and deep-bed filtration with coagulation as a single advanced treatment step for simultaneous removal of OMPs and phosphorus from secondary effluent. GAC was assessed as upper filter layer in dual-media downflow filtration and as mono-media upflow filter with regard to filtration performance and OMP removal. Both filtration concepts effectively removed suspended solids and phosphorus, achieving effluent concentrations of 0.1 mg/L TP and 1 mg/L TSS, respectively. Analysis of grain size distribution and head loss within the filter bed showed that considerable head loss occurred in the topmost filter layer in downflow filtration, indicating that most particles do not penetrate deeply into the filter bed. Upflow filtration exhibited substantially lower head loss and effective utilization of the whole filter bed. Well-adsorbing OMPs (e.g. benzotriazole, carbamazepine) were removed by >80% up to throughputs of 8000-10,000 bed volumes (BV), whereas weakly to medium adsorbing OMPs (e.g. primidone, sulfamethoxazole) showed removals <80% at <5,000 BV. In addition, breakthrough behavior was also determined for gabapentin, an anticonvulsant drug recently detected in drinking water resources for which suitable removal technologies are still largely unknown. Gabapentin showed poor adsorptive removal, resulting in rapid concentration increases. Whereas previous studies classified gabapentin as not readily biodegradable, sustained removal was observed after prolonged operation and points at biological elimination of gabapentin within the GAC filter. The application of GAC as filter medium was compared to direct addition of powdered activated carbon (PAC) to deep-bed filtration as a direct process alternative. Both options yielded comparable OMP removals for most compounds at similar carbon usage rates, but GAC achieved considerably higher removals for biodegradable OMPs. Based on the results, the application of GAC in combination with coagulation/filtration represents a promising alternative to powdered activated carbon and ozone for advanced wastewater treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Miniature Distillation Column for Producing LOX From Air

NASA Technical Reports Server (NTRS)

Rozzi, Jay C.

2006-01-01

The figure shows components of a distillation column intended for use as part of a system that produces high-purity liquid oxygen (LOX) from air by distillation. (The column could be easily modified to produce high-purity liquid nitrogen.) Whereas typical industrial distillation columns for producing high-purity liquid oxygen and/or nitrogen are hundreds of feet tall, this distillation column is less than 3 ft (less than about 0.9 m) tall. This column was developed to trickle-charge a LOX-based emergency oxygen system (EOS) for a large commercial aircraft. A description of the industrial production of liquid oxygen and liquid nitrogen by distillation is prerequisite to a meaningful description of the present miniaturized distillation column. Typically, such industrial production takes place in a chemical processing plant in which large quantities of high-pressure air are expanded in a turboexpander to (1) recover a portion of the electrical power required to compress the air and (2) partially liquefy the air. The resulting two-phase flow of air is sent to the middle of a distillation column. The liquid phase is oxygen-rich, and its oxygen purity increases as it flows down the column. The vapor phase is nitrogen-rich and its nitrogen purity increases as it flows up the column. A heater or heat exchanger, commonly denoted a reboiler, is at the bottom of the column. The reboiler is so named because its role is to reboil some of the liquid oxygen collected at the bottom of the column to provide a flow of oxygen-rich vapor. As the oxygen-rich vapor flows up the column, it absorbs the nitrogen in the down-flowing liquid by mass transfer. Once the vapor leaves the lower portion of the column, it interacts with down-flowing nitrogen liquid that has been condensed in a heat exchanger, commonly denoted a condenser, at the top of the column. Liquid oxygen and liquid nitrogen products are obtained by draining some of the purified product at the bottom and top of the column, respectively. Because distillation is a mass-transfer process, the purity of the product(s) can be increased by increasing the effectiveness of the mass-transfer process (increasing the mass-transfer coefficient) and/or by increasing the available surface area for mass transfer through increased column height. The diameter of a distillation column is fixed by pressure-drop and mass-flow requirements. The approach taken in designing the present distillation column to be short yet capable of yielding a product of acceptably high purity was to pay careful attention to design details that affect mass-transfer processes.

JPRS Report, Science & Technology, China: Energy.

DTIC Science & Technology

1992-03-30

breeder reactors should become...the primary type of reactors . In developing breeder reactors , we should follow the path of using metal fuel. Breeder reactors give us more time to...first reactor used for power generation was a fast reactor : the " Breeder 1" reactor at the Idaho National Reactor Test Center which was used to

Biofilm reactors for industrial bioconversion processes: employing potential of enhanced reaction rates

PubMed Central

Qureshi, Nasib; Annous, Bassam A; Ezeji, Thaddeus C; Karcher, Patrick; Maddox, Ian S

2005-01-01

This article describes the use of biofilm reactors for the production of various chemicals by fermentation and wastewater treatment. Biofilm formation is a natural process where microbial cells attach to the support (adsorbent) or form flocs/aggregates (also called granules) without use of chemicals and form thick layers of cells known as "biofilms." As a result of biofilm formation, cell densities in the reactor increase and cell concentrations as high as 74 gL-1 can be achieved. The reactor configurations can be as simple as a batch reactor, continuous stirred tank reactor (CSTR), packed bed reactor (PBR), fluidized bed reactor (FBR), airlift reactor (ALR), upflow anaerobic sludge blanket (UASB) reactor, or any other suitable configuration. In UASB granular biofilm particles are used. This article demonstrates that reactor productivities in these reactors have been superior to any other reactor types. This article describes production of ethanol, butanol, lactic acid, acetic acid/vinegar, succinic acid, and fumaric acid in addition to wastewater treatment in the biofilm reactors. As the title suggests, biofilm reactors have high potential to be employed in biotechnology/bioconversion industry for viable economic reasons. In this article, various reactor types have been compared for the above bioconversion processes. PMID:16122390

Control of reactor coolant flow path during reactor decay heat removal

DOEpatents

Hunsbedt, Anstein N.

1988-01-01

An improved reactor vessel auxiliary cooling system for a sodium cooled nuclear reactor is disclosed. The sodium cooled nuclear reactor is of the type having a reactor vessel liner separating the reactor hot pool on the upstream side of an intermediate heat exchanger and the reactor cold pool on the downstream side of the intermediate heat exchanger. The improvement includes a flow path across the reactor vessel liner flow gap which dissipates core heat across the reactor vessel and containment vessel responsive to a casualty including the loss of normal heat removal paths and associated shutdown of the main coolant liquid sodium pumps. In normal operation, the reactor vessel cold pool is inlet to the suction side of coolant liquid sodium pumps, these pumps being of the electromagnetic variety. The pumps discharge through the core into the reactor hot pool and then through an intermediate heat exchanger where the heat generated in the reactor core is discharged. Upon outlet from the heat exchanger, the sodium is returned to the reactor cold pool. The improvement includes placing a jet pump across the reactor vessel liner flow gap, pumping a small flow of liquid sodium from the lower pressure cold pool into the hot pool. The jet pump has a small high pressure driving stream diverted from the high pressure side of the reactor pumps. During normal operation, the jet pumps supplement the normal reactor pressure differential from the lower pressure cold pool to the hot pool. Upon the occurrence of a casualty involving loss of coolant pump pressure, and immediate cooling circuit is established by the back flow of sodium through the jet pumps from the reactor vessel hot pool to the reactor vessel cold pool. The cooling circuit includes flow into the reactor vessel liner flow gap immediate the reactor vessel wall and containment vessel where optimum and immediate discharge of residual reactor heat occurs.

Neutron fluxes in test reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Youinou, Gilles Jean-Michel

Communicate the fact that high-power water-cooled test reactors such as the Advanced Test Reactor (ATR), the High Flux Isotope Reactor (HFIR) or the Jules Horowitz Reactor (JHR) cannot provide fast flux levels as high as sodium-cooled fast test reactors. The memo first presents some basics physics considerations about neutron fluxes in test reactors and then uses ATR, HFIR and JHR as an illustration of the performance of modern high-power water-cooled test reactors.

Reactor engineering support of operations at the Davis-Besse nuclear power station

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelley, D.B.

1995-12-31

Reactor engineering functions differ greatly from unit to unit; however, direct support of the reactor operators during reactor startups and operational transients is common to all units. This paper summarizes the support the reactor engineers provide the reactor operators during reactor startups and power changes through the use of automated computer programs at the Davis-Besse nuclear power station.

10 CFR 2.337 - Evidence at a hearing.

Code of Federal Regulations, 2011 CFR

2011-01-01

... chapter by the Director, Office of Nuclear Reactor Regulation, Director, Office of New Reactors, or... the Director, Office of Nuclear Reactor Regulation, Director, Office of New Reactors, or Director... the Director, Office of Nuclear Reactor Regulation, Director, Office of New Reactors, or Director...

Nuclear Reactors. Revised.

ERIC Educational Resources Information Center

Hogerton, John F.

This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Among the topics discussed are: How Reactors Work; Reactor Design; Research, Teaching, and Materials Testing; Reactors (Research, Teaching and Materials); Production Reactors; Reactors for Electric Power…

10 CFR 2.337 - Evidence at a hearing.

Code of Federal Regulations, 2012 CFR

2012-01-01

... chapter by the Director, Office of Nuclear Reactor Regulation, Director, Office of New Reactors, or... the Director, Office of Nuclear Reactor Regulation, Director, Office of New Reactors, or Director... the Director, Office of Nuclear Reactor Regulation, Director, Office of New Reactors, or Director...

Nuclear reactor construction with bottom supported reactor vessel

DOEpatents

Sharbaugh, John E.

1987-01-01

An improved liquid metal nuclear reactor construction has a reactor core and a generally cylindrical reactor vessel for holding a large pool of low pressure liquid metal coolant and housing the core within the pool. The reactor vessel has an open top end, a closed flat bottom end wall and a continuous cylindrical closed side wall interconnecting the top end and bottom end wall. The reactor also has a generally cylindrical concrete containment structure surrounding the reactor vessel and being formed by a cylindrical side wall spaced outwardly from the reactor vessel side wall and a flat base mat spaced below the reactor vessel bottom end wall. A central support pedestal is anchored to the containment structure base mat and extends upwardly therefrom to the reactor vessel and upwardly therefrom to the reactor core so as to support the bottom end wall of the reactor vessel and the lower end of the reactor core in spaced apart relationship above the containment structure base mat. Also, an annular reinforced support structure is disposed in the reactor vessel on the bottom end wall thereof and extends about the lower end of the core so as to support the periphery thereof. In addition, an annular support ring having a plurality of inward radially extending linear members is disposed between the containment structure base mat and the bottom end of the reactor vessel wall and is connected to and supports the reactor vessel at its bottom end on the containment structure base mat so as to allow the reactor vessel to expand radially but substantially prevent any lateral motions that might be imposed by the occurrence of a seismic event. The reactor construction also includes a bed of insulating material in sand-like granular form, preferably being high density magnesium oxide particles, disposed between the containment structure base mat and the bottom end wall of the reactor vessel and uniformly supporting the reactor vessel at its bottom end wall on the containment structure base mat so as to insulate the reactor vessel bottom end wall from the containment structure base mat and allow the reactor vessel bottom end wall to freely expand as it heats up while providing continuous support thereof. Further, a deck is supported upon the side wall of the containment structure above the top open end of the reactor vessel, and a plurality of serially connected extendible and retractable annular bellows extend between the deck and the top open end of the reactor vessel and flexibly and sealably interconnect the reactor vessel at its top end to the deck. An annular guide ring is disposed on the containment structure and extends between its side wall and the top open end of the reactor vessel for providing lateral support of the reactor vessel top open end by limiting imposition of lateral loads on the annular bellows by the occurrence of a lateral seismic event.

Request for Naval Reactors Comment on Proposed Prometheus Space Flight Nuclear Reactor High Tier Reactor Safety Requirements and for Naval Reactors Approval to Transmit These Requirements to JPL

DOE Office of Scientific and Technical Information (OSTI.GOV)

D. Kokkinos

2005-04-28

The purpose of this letter is to request Naval Reactors comments on the nuclear reactor high tier requirements for the PROMETHEUS space flight reactor design, pre-launch operations, launch, ascent, operation, and disposal, and to request Naval Reactors approval to transmit these requirements to Jet Propulsion Laboratory to ensure consistency between the reactor safety requirements and the spacecraft safety requirements. The proposed PROMETHEUS nuclear reactor high tier safety requirements are consistent with the long standing safety culture of the Naval Reactors Program and its commitment to protecting the health and safety of the public and the environment. In addition, the philosophymore » on which these requirements are based is consistent with the Nuclear Safety Policy Working Group recommendations on space nuclear propulsion safety (Reference 1), DOE Nuclear Safety Criteria and Specifications for Space Nuclear Reactors (Reference 2), the Nuclear Space Power Safety and Facility Guidelines Study of the Applied Physics Laboratory.« less

Heat transfer analysis of cylindrical anaerobic reactors with different sizes: a heat transfer model.

PubMed

Liu, Jiawei; Zhou, Xingqiu; Wu, Jiangdong; Gao, Wen; Qian, Xu

2017-10-01

The temperature is the essential factor that influences the efficiency of anaerobic reactors. During the operation of the anaerobic reactor, the fluctuations of ambient temperature can cause a change in the internal temperature of the reactor. Therefore, insulation and heating measures are often used to maintain anaerobic reactor's internal temperature. In this paper, a simplified heat transfer model was developed to study heat transfer between cylindrical anaerobic reactors and their surroundings. Three cylindrical reactors of different sizes were studied, and the internal relations between ambient temperature, thickness of insulation, and temperature fluctuations of the reactors were obtained at different reactor sizes. The model was calibrated by a sensitivity analysis, and the calibrated model was well able to predict reactor temperature. The Nash-Sutcliffe model efficiency coefficient was used to assess the predictive power of heat transfer models. The Nash coefficients of the three reactors were 0.76, 0.60, and 0.45, respectively. The model can provide reference for the thermal insulation design of cylindrical anaerobic reactors.

Solvent refined coal reactor quench system

DOEpatents

Thorogood, Robert M.

1983-01-01

There is described an improved SRC reactor quench system using a condensed product which is recycled to the reactor and provides cooling by evaporation. In the process, the second and subsequent reactors of a series of reactors are cooled by the addition of a light oil fraction which provides cooling by evaporation in the reactor. The vaporized quench liquid is recondensed from the reactor outlet vapor stream.

Solvent refined coal reactor quench system

DOEpatents

Thorogood, R.M.

1983-11-08

There is described an improved SRC reactor quench system using a condensed product which is recycled to the reactor and provides cooling by evaporation. In the process, the second and subsequent reactors of a series of reactors are cooled by the addition of a light oil fraction which provides cooling by evaporation in the reactor. The vaporized quench liquid is recondensed from the reactor outlet vapor stream. 1 fig.

Nuclear reactor neutron shielding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Speaker, Daniel P; Neeley, Gary W; Inman, James B

A nuclear reactor includes a reactor pressure vessel and a nuclear reactor core comprising fissile material disposed in a lower portion of the reactor pressure vessel. The lower portion of the reactor pressure vessel is disposed in a reactor cavity. An annular neutron stop is located at an elevation above the uppermost elevation of the nuclear reactor core. The annular neutron stop comprises neutron absorbing material filling an annular gap between the reactor pressure vessel and the wall of the reactor cavity. The annular neutron stop may comprise an outer neutron stop ring attached to the wall of the reactormore » cavity, and an inner neutron stop ring attached to the reactor pressure vessel. An excore instrument guide tube penetrates through the annular neutron stop, and a neutron plug comprising neutron absorbing material is disposed in the tube at the penetration through the neutron stop.« less

Reactor pressure vessel head vents and methods of using the same

DOEpatents

Gels, John L; Keck, David J; Deaver, Gerald A

2014-10-28

Internal head vents are usable in nuclear reactors and include piping inside of the reactor pressure vessel with a vent in the reactor upper head. Piping extends downward from the upper head and passes outside of the reactor to permit the gas to escape or be forcibly vented outside of the reactor without external piping on the upper head. The piping may include upper and lowers section that removably mate where the upper head joins to the reactor pressure vessel. The removable mating may include a compressible bellows and corresponding funnel. The piping is fabricated of nuclear-reactor-safe materials, including carbon steel, stainless steel, and/or a Ni--Cr--Fe alloy. Methods install an internal head vent in a nuclear reactor by securing piping to an internal surface of an upper head of the nuclear reactor and/or securing piping to an internal surface of a reactor pressure vessel.

Proposed Advanced Reactor Adaptation of the Standard Review Plan NUREG-0800 Chapter 4 (Reactor) for Sodium-Cooled Fast Reactors and Modular High-Temperature Gas-Cooled Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belles, Randy; Poore, III, Willis P.; Brown, Nicholas R.

2017-03-01

This report proposes adaptation of the previous regulatory gap analysis in Chapter 4 (Reactor) of NUREG 0800, Standard Review Plan (SRP) for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR [Light Water Reactor] Edition. The proposed adaptation would result in a Chapter 4 review plan applicable to certain advanced reactors. This report addresses two technologies: the sodium-cooled fast reactor (SFR) and the modular high temperature gas-cooled reactor (mHTGR). SRP Chapter 4, which addresses reactor components, was selected for adaptation because of the possible significant differences in advanced non-light water reactor (non-LWR) technologies compared with the current LWR-basedmore » description in Chapter 4. SFR and mHTGR technologies were chosen for this gap analysis because of their diverse designs and the availability of significant historical design detail.« less

10 CFR 52.167 - Issuance of manufacturing license.

Code of Federal Regulations, 2010 CFR

2010-01-01

... proposed reactor(s) can be incorporated into a nuclear power plant and operated at sites having... design and manufacture the proposed nuclear power reactor(s); (5) The proposed inspections, tests... the construction of a nuclear power facility using the manufactured reactor(s). (2) A holder of a...

A novel plant protection strategy for transient reactors

NASA Astrophysics Data System (ADS)

Bhattacharyya, Samit K.; Lipinski, Walter C.; Hanan, Nelson A.

A novel plant protection system designed for use in the TREAT Upgrade (TU) reactor is described. The TU reactor is designed for controlled transient operation in the testing of reactor fuel behavior under simulated reactor accident conditions. Safe operation of the reactor is of paramount importance and the Plant Protection System (PPS) had to be designed to exacting requirements. Researchers believe that the strategy developed for the TU has potential application to the multimegawatt space reactors and represents the state of the art in terrestrial transient reactor protection systems.

Process and apparatus for adding and removing particles from pressurized reactors

DOEpatents

Milligan, John D.

1983-01-01

A method for adding and removing fine particles from a pressurized reactor is provided, which comprises connecting the reactor to a container, sealing the container from the reactor, filling the container with particles and a liquid material compatible with the reactants, pressurizing the container to substantially the reactor pressure, removing the seal between the reactor and the container, permitting particles to fall into or out of the reactor, and resealing the container from the reactor. An apparatus for adding and removing particles is also disclosed.

Effects of imperfect mixing on low-density polyethylene reactor dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Villa, C.M.; Dihora, J.O.; Ray, W.H.

1998-07-01

Earlier work considered the effect of feed conditions and controller configuration on the runaway behavior of LDPE autoclave reactors assuming a perfectly mixed reactor. This study provides additional insight on the dynamics of such reactors by using an imperfectly mixed reactor model and bifurcation analysis to show the changes in the stability region when there is imperfect macroscale mixing. The presence of imperfect mixing substantially increases the range of stable operation of the reactor and makes the process much easier to control than for a perfectly mixed reactor. The results of model analysis and simulations are used to identify somemore » of the conditions that lead to unstable reactor behavior and to suggest ways to avoid reactor runaway or reactor extinction during grade transitions and other process operation disturbances.« less

Startup of reactors for anoxic ammonium oxidation: experiences from the first full-scale anammox reactor in Rotterdam.

PubMed

van der Star, Wouter R L; Abma, Wiebe R; Blommers, Dennis; Mulder, Jan-Willem; Tokutomi, Takaaki; Strous, Marc; Picioreanu, Cristian; van Loosdrecht, Mark C M

2007-10-01

The first full-scale anammox reactor in the world was started in Rotterdam (NL). The reactor was scaled-up directly from laboratory-scale to full-scale and treats up to 750 kg-N/d. In the initial phase of the startup, anammox conversions could not be identified by traditional methods, but quantitative PCR proved to be a reliable indicator for growth of the anammox population, indicating an anammox doubling time of 10-12 days. The experience gained during this first startup in combination with the availability of seed sludge from this reactor, will lead to a faster startup of anammox reactors in the future. The anammox reactor type employed in Rotterdam was compared to other reactor types for the anammox process. Reactors with a high specific surface area like the granular sludge reactor employed in Rotterdam provide the highest volumetric loading rates. Mass transfer of nitrite into the biofilm is limiting the conversion of those reactor types that have a lower specific surface area. Now the first full-scale commercial anammox reactor is in operation, a consistent and descriptive nomenclature is suggested for reactors in which the anammox process is employed.

A small, 1400 K, reactor for Brayton space power systems.

NASA Technical Reports Server (NTRS)

Lantz, E.; Mayo, W.

1972-01-01

An investigation was conducted to determine minimum dimensions and minimum weight obtainable in a design for a reactor using uranium-233 nitride or plutonium-239 nitride as fuel. Such a reactor had been considered by Krasner et al. (1971). Present space power status is discussed, together with questions of reactor design and power distribution in the reactor. The characteristics of various reactor types are compared, giving attention also to a zirconium hydride reactor.

Alternative approaches to fusion. [reactor design and reactor physics for Tokamak fusion reactors

NASA Technical Reports Server (NTRS)

Roth, R. J.

1976-01-01

The limitations of the Tokamak fusion reactor concept are discussed and various other fusion reactor concepts are considered that employ the containment of thermonuclear plasmas by magnetic fields (i.e., stellarators). Progress made in the containment of plasmas in toroidal devices is reported. Reactor design concepts are illustrated. The possibility of using fusion reactors as a power source in interplanetary space travel and electric power plants is briefly examined.

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

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 1 2010-01-01 2010-01-01 false Acceptance criteria for reactor coolant system venting... criteria for reactor coolant system venting systems. Each nuclear power reactor must be provided with high point vents for the reactor coolant system, for the reactor vessel head, and for other systems required...

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

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 1 2011-01-01 2011-01-01 false Acceptance criteria for reactor coolant system venting... criteria for reactor coolant system venting systems. Each nuclear power reactor must be provided with high point vents for the reactor coolant system, for the reactor vessel head, and for other systems required...

KINETICS OF TREAT USED AS A TEST REACTOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dickerman, C.E.; Johnson, R.D.; Gasidlo, J.

1962-05-01

An analysis is presented concerning the reactor kinetics of TREAT used as a pulsed, engineering test reactor for fast reactor fuel element studies. A description of the reactor performance is given for a wide range of conditions associated with its use as a test reactor. Supplemental information on meltdown experimentation is included. (J.R.D.)

Generating unstructured nuclear reactor core meshes in parallel

DOE PAGES

Jain, Rajeev; Tautges, Timothy J.

2014-10-24

Recent advances in supercomputers and parallel solver techniques have enabled users to run large simulations problems using millions of processors. Techniques for multiphysics nuclear reactor core simulations are under active development in several countries. Most of these techniques require large unstructured meshes that can be hard to generate in a standalone desktop computers because of high memory requirements, limited processing power, and other complexities. We have previously reported on a hierarchical lattice-based approach for generating reactor core meshes. Here, we describe efforts to exploit coarse-grained parallelism during reactor assembly and reactor core mesh generation processes. We highlight several reactor coremore » examples including a very high temperature reactor, a full-core model of the Korean MONJU reactor, a ¼ pressurized water reactor core, the fast reactor Experimental Breeder Reactor-II core with a XX09 assembly, and an advanced breeder test reactor core. The times required to generate large mesh models, along with speedups obtained from running these problems in parallel, are reported. A graphical user interface to the tools described here has also been developed.« less

Nuclear reactor having a polyhedral primary shield and removable vessel insulation

DOEpatents

Ekeroth, Douglas E.; Orr, Richard

1993-01-01

A nuclear reactor is provided having a generally cylindrical reactor vessel disposed within an opening in a primary shield. The opening in the primary shield is defined by a plurality of generally planar side walls forming a generally polyhedral-shaped opening. The reactor vessel is supported within the opening in the primary shield by reactor vessel supports which are in communication and aligned with central portions of some of the side walls. The reactor vessel is connected to the central portions of the reactor vessel supports. A thermal insulation polyhedron formed from a plurality of slidably insertable and removable generally planar insulation panels substantially surrounds at least a portion of the reactor vessel and is disposed between the reactor vessel and the side walls of the primary shield. The shape of the insulation polyhedron generally corresponds to the shape of the opening in the primary shield. Reactor monitoring instrumentation may be mounted in the corners of the opening in the primary shield between the side walls and the reactor vessel such that insulation is not disposed between the instrumentation and the reactor vessel.

Nuclear reactor having a polyhedral primary shield and removable vessel insulation

DOEpatents

Ekeroth, D.E.; Orr, R.

1993-12-07

A nuclear reactor is provided having a generally cylindrical reactor vessel disposed within an opening in a primary shield. The opening in the primary shield is defined by a plurality of generally planar side walls forming a generally polyhedral-shaped opening. The reactor vessel is supported within the opening in the primary shield by reactor vessel supports which are in communication and aligned with central portions of some of the side walls. The reactor vessel is connected to the central portions of the reactor vessel supports. A thermal insulation polyhedron formed from a plurality of slidably insertable and removable generally planar insulation panels substantially surrounds at least a portion of the reactor vessel and is disposed between the reactor vessel and the side walls of the primary shield. The shape of the insulation polyhedron generally corresponds to the shape of the opening in the primary shield. Reactor monitoring instrumentation may be mounted in the corners of the opening in the primary shield between the side walls and the reactor vessel such that insulation is not disposed between the instrumentation and the reactor vessel. 5 figures.

Boiling water neutronic reactor incorporating a process inherent safety design

DOEpatents

Forsberg, C.W.

1985-02-19

A boiling-water reactor core is positioned within a prestressed concrete reactor vessel of a size which will hold a supply of coolant water sufficient to submerge and cool the reactor core by boiling for a period of at least one week after shutdown. Separate volumes of hot, clean (nonborated) water for cooling during normal operation and cool highly borated water for emergency cooling and reactor shutdown are separated by an insulated wall during normal reactor operation with contact between the two water volumes being maintained at interfaces near the top and bottom ends of the reactor vessel. Means are provided for balancing the pressure of the two water volumes at the lower interface zone during normal operation to prevent entry of the cool borated water into the reactor core region, for detecting the onset of excessive power to coolant flow conditions in the reactor core and for detecting low water levels of reactor coolant. Cool borated water is permitted to flow into the reactor core when low reactor coolant levels or excessive power to coolant flow conditions are encountered.

Boiling water neutronic reactor incorporating a process inherent safety design

DOEpatents

Forsberg, Charles W.

1987-01-01

A boiling-water reactor core is positioned within a prestressed concrete reactor vessel of a size which will hold a supply of coolant water sufficient to submerge and cool the reactor core by boiling for a period of at least one week after shutdown. Separate volumes of hot, clean (non-borated) water for cooling during normal operation and cool highly borated water for emergency cooling and reactor shutdown are separated by an insulated wall during normal reactor operation with contact between the two water volumes being maintained at interfaces near the top and bottom ends of the reactor vessel. Means are provided for balancing the pressure of the two volumes at the lower interface zone during normal operation to prevent entry of the cool borated water into the reactor core region, for detecting the onset of excessive power to coolant flow conditions in the reactor core and for detecting low water levels of reactor coolant. Cool borated water is permitted to flow into the reactor core when low reactor coolant levels or excessive power to coolant flow conditions are encountered.

Summary of NR Program Prometheus Efforts

DOE Office of Scientific and Technical Information (OSTI.GOV)

J Ashcroft; C Eshelman

2006-02-08

The Naval Reactors Program led work on the development of a reactor plant system for the Prometheus space reactor program. The work centered on a 200 kWe electric reactor plant with a 15-20 year mission applicable to nuclear electric propulsion (NEP). After a review of all reactor and energy conversion alternatives, a direct gas Brayton reactor plant was selected for further development. The work performed subsequent to this selection included preliminary nuclear reactor and reactor plant design, development of instrumentation and control techniques, modeling reactor plant operational features, development and testing of core and plant material options, and development ofmore » an overall project plan. Prior to restructuring of the program, substantial progress had been made on defining reference plant operating conditions, defining reactor mechanical, thermal and nuclear performance, understanding the capabilities and uncertainties provided by material alternatives, and planning non-nuclear and nuclear system testing. The mission requirements for the envisioned NEP missions cannot be accommodated with existing reactor technologies. Therefore concurrent design, development and testing would be needed to deliver a functional reactor system. Fuel and material performance beyond the current state of the art is needed. There is very little national infrastructure available for fast reactor nuclear testing and associated materials development and testing. Surface mission requirements may be different enough to warrant different reactor design approaches and development of a generic multi-purpose reactor requires substantial sacrifice in performance capability for each mission.« less

BIDIRECTIONAL OUTFLOWS AS EVIDENCE OF MAGNETIC RECONNECTION LEADING TO A SOLAR MICROFLARE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Jie; Ding, M. D.; Li, Ying

2016-03-20

Magnetic reconnection is a rapid energy release process that is believed to be responsible for flares on the Sun and stars. Nevertheless, such flare-related reconnection is mostly detected to occur in the corona, while there have been few studies concerning the reconnection in the chromosphere or photosphere. Here, we present both spectroscopic and imaging observations of magnetic reconnection in the chromosphere leading to a microflare. During the flare peak time, chromospheric line profiles show significant blueshifted/redshifted components on the two sides of the flaring site, corresponding to upflows and downflows with velocities of ±(70–80) km s{sup −1}, comparable with the localmore » Alfvén speed as expected by the reconnection in the chromosphere. The three-dimensional nonlinear force-free field configuration further discloses twisted field lines (a flux rope) at a low altitude, cospatial with the dark threads in He i 10830 Å images. The instability of the flux rope may initiate the flare-related reconnection. These observations provide clear evidence of magnetic reconnection in the chromosphere and show the similar mechanisms of a microflare to those of major flares.« less

Dynamics and thermodynamics of a tornado: Rotation effects

NASA Astrophysics Data System (ADS)

Ben-Amots, N.

2016-09-01

This paper investigates the relevant processes in the tornado including the dynamics of rotation and thermodynamics as well as condensation. The main novelty of this paper is the explanation of the phenomena occurring in the central downflow. The reduced pressure in the tornado's funnel sucks air and water vapor from the cloud above the tornado. The latent heat of condensation is released in the funnel. The centrifugal force drives the generated water drops out of the funnel. The latent heat of condensation released is also transferred out of the funnel, and supplies the helically ascending air flow surrounding the tornado with additional buoyancy energy. This process gives the tornado increased strength compared to the dust devil type of flow, thus explaining why tornadoes occur always under a cloud, and why the tornado pipe can reach a height of a kilometer and more. To sustain a tornado, the temperature of water vapor at the cloud's base should be higher than the surroundings by a certain minimal value. Remote infrared temperature measurements of clouds' bases may provide indications of the probability that a cloud can spawn a tornado, which may increase the lead time.

A simple model of chromospheric evaporation and condensation driven conductively in a solar flare

DOE Office of Scientific and Technical Information (OSTI.GOV)

Longcope, D. W.

2014-11-01

Magnetic energy released in the corona by solar flares reaches the chromosphere where it drives characteristic upflows and downflows known as evaporation and condensation. These flows are studied here for the case where energy is transported to the chromosphere by thermal conduction. An analytic model is used to develop relations by which the density and velocity of each flow can be predicted from coronal parameters including the flare's energy flux F. These relations are explored and refined using a series of numerical investigations in which the transition region (TR) is represented by a simplified density jump. The maximum evaporation velocity,more » for example, is well approximated by v{sub e} ≅ 0.38(F/ρ{sub co,} {sub 0}){sup 1/3}, where ρ{sub co,} {sub 0} is the mass density of the pre-flare corona. This and the other relations are found to fit simulations using more realistic models of the TR both performed in this work, and taken from a variety of previously published investigations. These relations offer a novel and efficient means of simulating coronal reconnection without neglecting entirely the effects of evaporation.« less

High performance constructed wetlands for cold climates.

PubMed

Jenssen, Petter D; Maehlum, Trend; Krogstad, Tore; Vråle, Lasse

2005-01-01

In 1991, the first subsurface flow constructed wetland for treatment of domestic wastewater was built in Norway. Today, this method is rapidly becoming a popular method for wastewater treatment in rural Norway. This is due to excellent performance even during winter and low maintenance. The systems can be constructed regardless of site conditions. The Norwegian concept for small constructed wetlands is based on the use of a septic tank followed by an aerobic vertical down-flow biofilter succeeded by a subsurface horizontal-flow constructed wetland. The aerobic biofilter, prior to the subsurface flow stage, is essential to remove BOD and achieve nitrification in a climate where the plants are dormant during the cold season. When designed according to present guidelines a consistent P-removal of > 90% can be expected for 15 years using natural iron or calcium rich sand or a new manufactured lightweight aggregate with P-sorption capacities, which exceeds most natural media. When the media is saturated with P it can be used as soil conditioner and P-fertilizer. Nitrogen removal in the range of 40-60% is achieved. Removal of indicator bacteria is high and < 1000 thermotolerant coliforms/100 ml is normally achieved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kitiashvili, I. N.; Mansour, N. N.; Wray, A. A.

Magnetic fields are usually observed in the quiet Sun as small-scale elements that cover the entire solar surface (the “salt-and-pepper” patterns in line-of-sight magnetograms). By using 3D radiative MHD numerical simulations, we find that these fields result from a local dynamo action in the top layers of the convection zone, where extremely weak “seed” magnetic fields (e.g., from a 10{sup −6} G) can locally grow above the mean equipartition field to a stronger than 2000 G field localized in magnetic structures. Our results reveal that the magnetic flux is predominantly generated in regions of small-scale helical downflows. We find thatmore » the local dynamo action takes place mostly in a shallow, about 500 km deep, subsurface layer, from which the generated field is transported into the deeper layers by convective downdrafts. We demonstrate that the observed dominance of vertical magnetic fields at the photosphere and horizontal fields above the photosphere can be explained by small-scale magnetic loops produced by the dynamo. Such small-scale loops play an important role in the structure and dynamics of the solar atmosphere and their detection in observations is critical for understanding the local dynamo action on the Sun.« less

Note On The Ross Sea Shelf Water Downflow Processes (antarctica)

NASA Astrophysics Data System (ADS)

Bergamasco, A.; Defendi, V.; Spezie, G.; Budillon, G.; Carniel, S.

In the framework of the CLIMA Project of the Italian National Program for Research in Antarctica, three different experimental data sets were acquired along the continental shelf break; two of them (in 1997 and 2001) close to Cape Adare, the 1998 one in the middle of the Ross Sea (i.e. 75 S, 177 W). The investigations were chosen in order to explore the downslope flow of the bottom waters produced in the Ross Sea, namely the High Salinity Shelf Water (HSSW, the densest water mass of the southern ocean coming from its formation site in the polynya region in Terra Nova bay), and the Ice Shelf Water (ISW, originated below the Ross Ice Shelf and outflowing northward). Both bottom waters spill over the shelf edge and mix with the Circumpolar Deep Water (CDW) contributing to the formation of the Antarctic Bottom Waters (AABW). Interpreting temperature, salinity and density maps in terms of cascading processes, both HSSW and ISW overflows are evidenced during, respectively, 1997 and 1998. During the 2001 acquisition there is no presence of HSSW along the shelf break, nevertheless distribution captures the evidence of a downslope flow process.

CUSP-SHAPED STRUCTURE OF A JET OBSERVED BY IRIS AND SDO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yuzong; Zhang, Jun, E-mail: yuzong@nao.cas.cn, E-mail: zjun@nao.cas.cn

2017-01-01

On 2014 August 29, the trigger and evolution of a cusp-shaped jet were captured in detail at 1330 Å by the Interface Region Imaging Spectrograph . At first, two neighboring mini-prominences arose in turn from the low solar atmosphere and collided with a loop-like system over them. The collisions between the loop-like system and the mini-prominences lead to the blowout, and then a cusp-shaped jet formed with a spire and an arch-base. In the spire, many brightening blobs originating from the junction between the spire and the arch-base moved upward in a rotating manner and then in a straight line inmore » the late phase of the jet. In the arch-base, dark and bright material simultaneously tracked in a fan-like structure, and the majority of the material moved along the fan's threads. At the later phase of the jet's evolution, bidirectional flows emptied the arch-base, while downflows emptied the spire, thus making the jet entirely vanish. The extremely detailed observations in this study shed new light on how magnetic reconnection alters the inner topological structure of a jet and provides a beneficial complement for understanding current jet models.« less

TEMPORAL EVOLUTION OF MULTIPLE EVAPORATING RIBBON SOURCES IN A SOLAR FLARE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graham, D. R.; Cauzzi, G., E-mail: dgraham@arcetri.astro.it

2015-07-10

We present new results from the Interface Region Imaging Spectrograph (IRIS) showing the dynamic evolution of chromospheric evaporation and condensation in a flare ribbon, with the highest temporal and spatial resolution to date. IRIS observed the entire impulsive phase of the X-class flare SOL2014-09-10T17:45 using a 9.4 s cadence “sit-and-stare” mode. As the ribbon brightened successively at new positions along the slit, a unique impulsive phase evolution was observed for many tens of individual pixels in both coronal and chromospheric lines. Each activation of a new footpoint displays the same initial coronal upflows of up to ∼300 km s{sup −1}more » and chromospheric downflows up to 40 km s{sup −1}. Although the coronal flows can be delayed by over 1 minute with respect to those in the chromosphere, the temporal evolution of flows is strikingly similar between all pixels and consistent with predictions from hydrodynamic flare models. Given the large sample of independent footpoints, we conclude that each flaring pixel can be considered a prototypical, “elementary” flare kernel.« less

Spatial discrimination of persistent EUV oscillations in a hot waning light bridge

NASA Astrophysics Data System (ADS)

Walsh, D.; Yuan, R. W.

2016-10-01

A light bridge is usually formed as a lower atmospheric structure in nascent or decaying sunspots; it divides the umbra into separate regions. Convection, which is normally suppressed by a sunspot's strong magnetic field, is partially restored and upflows are usually observed at the spine of a bridge with downflows (or return flows) at the two flanks. This study outlines observations a light bridge unusually sustained at coronal temperatures. Viewed in AR11520 on 12th July 2012 by the High Resolution Coronal Imager (HiC) and AIA/SDO, the EUV emission intensity exhibits two persistent oscillations. The approximate 5-minute oscillations are distributed along the spine of the light bridge whereas sub-minute oscillations are distinctively co-spatial along each bridge flank (though there is a distinct time-lag between them). This indicates strongly that (i) the oscillatory driver at the flanks is connected with the collective interactions between magnetic fields of the bridge and the sunspot itself and (ii) the internal magnetic structure of the bridge is twisted. The presentation will outline the distinct oscillatory maps generated and provide insight into determining the magnetic morphology until the bridge wans several hours later.

Theoretical study on bubble formation and flow condensation in downflow channel with horizontal gas injection

NASA Astrophysics Data System (ADS)

Zhu, Kang; Li, Yanzhong; Wang, Jiaojiao; Ma, Yuan; Wang, Lei; Xie, Fushou

2018-05-01

Bubble formation and condensation in liquid pipes occur widely in industrial systems such as cryogenic propellant feeding system. In this paper, an integrated theoretical model is established to give a comprehensive description of the bubble formation, motion and condensation process. The model is validated by numerical simulations and bubble condensation experiments from references, and good agreements are achieved. The bubble departure diameter at the orifice and the flow condensation length in the liquid channel are predicted by the model, and effects of various influencing parameters on bubble behaviors are analyzed. Prediction results indicate that the orifice diameter, the gas feeding rate, and the liquid velocity are the primary influence factors on the bubble departure diameter. The interfacial heat transfer as well as the bubble departure diameter has a direct impact on the bubble flow condensation length, which increases by 2.5 times over a system pressure range of 0.1 0.4 MPa, and decreases by 85% over a liquid subcooling range of 5 30 K. This work could be beneficial to the prediction of bubble formation and flow condensation processes and the design of cryogenic transfer pipes.

A Long-Term Cultivation of an Anaerobic Methane-Oxidizing Microbial Community from Deep-Sea Methane-Seep Sediment Using a Continuous-Flow Bioreactor

PubMed Central

Aoki, Masataka; Ehara, Masayuki; Saito, Yumi; Yoshioka, Hideyoshi; Miyazaki, Masayuki; Saito, Yayoi; Miyashita, Ai; Kawakami, Shuji; Yamaguchi, Takashi; Ohashi, Akiyoshi; Nunoura, Takuro; Takai, Ken; Imachi, Hiroyuki

2014-01-01

Anaerobic oxidation of methane (AOM) in marine sediments is an important global methane sink, but the physiological characteristics of AOM-associated microorganisms remain poorly understood. Here we report the cultivation of an AOM microbial community from deep-sea methane-seep sediment using a continuous-flow bioreactor with polyurethane sponges, called the down-flow hanging sponge (DHS) bioreactor. We anaerobically incubated deep-sea methane-seep sediment collected from the Nankai Trough, Japan, for 2,013 days in the bioreactor at 10°C. Following incubation, an active AOM activity was confirmed by a tracer experiment using 13C-labeled methane. Phylogenetic analyses demonstrated that phylogenetically diverse Archaea and Bacteria grew in the bioreactor. After 2,013 days of incubation, the predominant archaeal components were anaerobic methanotroph (ANME)-2a, Deep-Sea Archaeal Group, and Marine Benthic Group-D, and Gammaproteobacteria was the dominant bacterial lineage. Fluorescence in situ hybridization analysis showed that ANME-1 and -2a, and most ANME-2c cells occurred without close physical interaction with potential bacterial partners. Our data demonstrate that the DHS bioreactor system is a useful system for cultivating fastidious methane-seep-associated sedimentary microorganisms. PMID:25141130

METHOD AND APPARATUS FOR CONTROLLING DIRECT-CYCLE NEUTRONIC REACTORS

DOEpatents

Reed, G.A.

1961-01-10

A control arrangement is offered for a boiling-water reactor. Boric acid is maintained in the water in the reactor and the amount in the reactor is controlled by continuously removing a portion of the water from the reactor, concentrating the boric acid by evaporating the water therefrom, returning a controlled amount of the acid to the reactor, and simultaneously controlling the water level by varying the rate of spent steam return to the reactor.

Control Means for Reactor

DOEpatents

Manley, J. H.

1961-06-27

An apparatus for controlling a nuclear reactor includes a tank just below the reactor, tubes extending from the tank into the reactor, and a thermally expansible liquid neutron absorbent material in the tank. The liquid in the tank is exposed to a beam of neutrons from the reactor which heats the liquid causing it to expand into the reactor when the neutron flux in the reactor rises above a predetermincd danger point. Boron triamine may be used for this purpose.

10 CFR 2.621 - Acceptance and docketing of application for early review of site suitability issues in a combined...

Code of Federal Regulations, 2014 CFR

2014-01-01

... Reactors or the Director of the Office of Nuclear Reactor Regulation, as appropriate, will inform the... Reactors or the Director of the Office of Nuclear Reactor Regulation, as appropriate, will accept for... New Reactors or the Director of the Office of Nuclear Reactor Regulation, as appropriate, that they...

10 CFR 2.621 - Acceptance and docketing of application for early review of site suitability issues in a combined...

Code of Federal Regulations, 2013 CFR

2013-01-01

... Reactors or the Director of the Office of Nuclear Reactor Regulation, as appropriate, will inform the... Reactors or the Director of the Office of Nuclear Reactor Regulation, as appropriate, will accept for... New Reactors or the Director of the Office of Nuclear Reactor Regulation, as appropriate, that they...

Low temperature pre-treatment of domestic sewage in an anaerobic hybrid or an anaerobic filter reactor.

PubMed

Elmitwalli, Tarek A; Sklyar, Vladimir; Zeeman, Grietje; Lettinga, Gatze

2002-05-01

The pre-treatment of domestic sewage for removal of suspended solids (SS) at a process temperature of 13 degrees C and an hydraulic retention time (HRT) of 4 h was investigated in an anaerobic filter (AF) and anaerobic hybrid (AH) reactor. The AF and the top of the AH reactor consisted of vertical sheets of reticulated polyurethane foam (RPF) with knobs. All biomass in the AF was only in attached form to avoid clogging and sludge washout. The AF reactor showed a significantly higher removal of total and suspended chemical oxygen demand (COD) than the AH reactor, respectively, 55% and 82% in the AF reactor and 34% and 53% in the AH reactor. Because the reactors were operated at a short HRT and low temperature, the hydrolysis, acidification and methanogenesis based on the influent COD were limited to, respectively, 12%, 21% and 23% for the AF reactor and 12%, 17% and 16% for the AH reactor. The excess sludge from the AH reactor was more stabilised and had a better settling capacity and dewaterability. However, the excess sludge from both the AH and AF reactors needed stabilisation. Therefore, the AF reactor is recommended for the pretreatment of domestic sewage at low temperatures.

Nuclear reactor cavity floor passive heat removal system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edwards, Tyler A.; Neeley, Gary W.; Inman, James B.

A nuclear reactor includes a reactor core disposed in a reactor pressure vessel. A radiological containment contains the nuclear reactor and includes a concrete floor located underneath the nuclear reactor. An ex vessel corium retention system includes flow channels embedded in the concrete floor located underneath the nuclear reactor, an inlet in fluid communication with first ends of the flow channels, and an outlet in fluid communication with second ends of the flow channels. In some embodiments the inlet is in fluid communication with the interior of the radiological containment at a first elevation and the outlet is in fluidmore » communication with the interior of the radiological containment at a second elevation higher than the first elevation. The radiological containment may include a reactor cavity containing a lower portion of the pressure vessel, wherein the concrete floor located underneath the nuclear reactor is the reactor cavity floor.« less

Methods and apparatuses for deoxygenating pyrolysis oil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baird, Lance Awender; Brandvold, Timothy A.; Frey, Stanley Joseph

Methods and apparatuses are provided for deoxygenating pyrolysis oil. A method includes contacting a pyrolysis oil with a deoxygenation catalyst in a first reactor at deoxygenation conditions to produce a first reactor effluent. The first reactor effluent has a first oxygen concentration and a first hydrogen concentration, based on hydrocarbons in the first reactor effluent, and the first reactor effluent includes an aromatic compound. The first reactor effluent is contacted with a dehydrogenation catalyst in a second reactor at conditions that deoxygenate the first reactor effluent while preserving the aromatic compound to produce a second reactor effluent. The second reactormore » effluent has a second oxygen concentration lower than the first oxygen concentration and a second hydrogen concentration that is equal to or lower than the first hydrogen concentration, where the second oxygen concentration and the second hydrogen concentration are based on the hydrocarbons in the second reactor effluent.« less

Methanation assembly using multiple reactors

DOEpatents

Jahnke, Fred C.; Parab, Sanjay C.

2007-07-24

A methanation assembly for use with a water supply and a gas supply containing gas to be methanated in which a reactor assembly has a plurality of methanation reactors each for methanating gas input to the assembly and a gas delivery and cooling assembly adapted to deliver gas from the gas supply to each of said methanation reactors and to combine water from the water supply with the output of each methanation reactor being conveyed to a next methanation reactor and carry the mixture to such next methanation reactor.

When Do Commercial Reactors Permanently Shut Down?

EIA Publications

2011-01-01

For those wishing to obtain current data, the following resources are available: U.S. reactors, go to the Energy Information Administration's nuclear reactor shutdown list. (Note: As of April 30, 2010, the last U.S. reactor to permanently shut down was Big Rock Point in 1997.) Foreign Reactors, go to the Power Reactor Information System (PRIS) on the International Atomic Energy Agency's website.

10 CFR 140.11 - Amounts of financial protection for certain reactors.

Code of Federal Regulations, 2014 CFR

2014-01-01

...,000,000 for each nuclear reactor he is authorized to operate at a thermal power level not exceeding ten kilowatts; (2) In the amount of $1,500,000 for each nuclear reactor he is authorized to operate at... amount of $2,500,000 for each nuclear reactor other than a testing reactor or a reactor licensed under...

10 CFR 2.603 - Acceptance and docketing of application for early review of site suitability issues in a...

Code of Federal Regulations, 2013 CFR

2013-01-01

... Office of New Reactors or the Director of the Office of Nuclear Reactor Regulation, as appropriate, will... Office of New Reactors or the Director of the Office of Nuclear Reactor Regulation, as appropriate, will... Reactors or the Director of the Office of Nuclear Reactor Regulation, as appropriate, that they are...

10 CFR 140.11 - Amounts of financial protection for certain reactors.

Code of Federal Regulations, 2012 CFR

2012-01-01

...,000,000 for each nuclear reactor he is authorized to operate at a thermal power level not exceeding ten kilowatts; (2) In the amount of $1,500,000 for each nuclear reactor he is authorized to operate at... amount of $2,500,000 for each nuclear reactor other than a testing reactor or a reactor licensed under...

10 CFR 2.603 - Acceptance and docketing of application for early review of site suitability issues in a...

Code of Federal Regulations, 2014 CFR

2014-01-01

... Office of New Reactors or the Director of the Office of Nuclear Reactor Regulation, as appropriate, will... Office of New Reactors or the Director of the Office of Nuclear Reactor Regulation, as appropriate, will... Reactors or the Director of the Office of Nuclear Reactor Regulation, as appropriate, that they are...

10 CFR 140.11 - Amounts of financial protection for certain reactors.

Code of Federal Regulations, 2013 CFR

2013-01-01

...,000,000 for each nuclear reactor he is authorized to operate at a thermal power level not exceeding ten kilowatts; (2) In the amount of $1,500,000 for each nuclear reactor he is authorized to operate at... amount of $2,500,000 for each nuclear reactor other than a testing reactor or a reactor licensed under...

Determination of the Sensitivity of the Antineutrino Probe for Reactor Core Monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cormon, S.; Fallot, M., E-mail: fallot@subatech.in2p3.fr; Bui, V.-M.

This paper presents a feasibility study of the use of the detection of reactor-antineutrinos (ν{sup ¯}{sub e}) for non proliferation purpose. To proceed, we have started to study different reactor designs with our simulation tools. We use a package called MCNP Utility for Reactor Evolution (MURE), initially developed by CNRS/IN2P3 labs to study Generation IV reactors. The MURE package has been coupled to fission product beta decay nuclear databases for studying reactor antineutrino emission. This method is the only one able to predict the antineutrino emission from future reactor cores, which don't use the thermal fission of {sup 235}U, {supmore » 239}Pu and {sup 241}Pu. It is also the only way to include off-equilibrium effects, due to neutron captures and time evolution of the fission product concentrations during a reactor cycle. We will present here the first predictions of antineutrino energy spectra from innovative reactor designs (Generation IV reactors). We will then discuss a summary of our results of non-proliferation scenarios involving the latter reactor designs, taking into account reactor physics constraints.« less

Bioaugmentation of activated sludge towards 3-chloroaniline removal with a mixed bacterial population carrying a degradative plasmid.

PubMed

Bathe, Stephan; Schwarzenbeck, Norbert; Hausner, Martina

2009-06-01

A bioaugmentation approach combining several strategies was applied to achieve degradation of 3-chloroaniline (3CA) in semicontinuous activated sludge reactors. In a first step, a 3CA-degrading Comamonas testosteroni strain carrying the degradative plasmid pNB2 was added to a biofilm reactor, and complete 3CA degradation together with spread of the plasmid within the indigenous biofilm population was achieved. A second set of reactors was then bioaugmented with either a suspension of biofilm cells removed from the carrier material or with biofilm-containing carrier material. 3CA degradation was established rapidly in all bioaugmented reactors, followed by a slow adaptation of the non-bioaugmented control reactors. In response to variations in 3CA concentration, all reactors exhibited temporary performance breakdowns. Whereas duplicates of the control reactors deviated in their behaviour, the bioaugmented reactors appeared more reproducible in their performance and population dynamics. Finally, the carrier-bioaugmented reactors showed an improved performance in the presence of high 3CA influent concentrations over the suspension-bioaugmented reactors. In contrast, degradation in one control reactor failed completely, but was rapidly established in the remaining control reactor.

A comparative study of thermophilic and mesophilic anaerobic co-digestion of food waste and wheat straw: Process stability and microbial community structure shifts.

PubMed

Shi, Xuchuan; Guo, Xianglin; Zuo, Jiane; Wang, Yajiao; Zhang, Mengyu

2018-05-01

Renewable energy recovery from organic solid waste via anaerobic digestion is a promising way to provide sustainable energy supply and eliminate environmental pollution. However, poor efficiency and operational problems hinder its wide application of anaerobic digestion. The effects of two key parameters, i.e. temperature and substrate characteristics on process stability and microbial community structure were studied using two lab-scale anaerobic reactors under thermophilic and mesophilic conditions. Both the reactors were fed with food waste (FW) and wheat straw (WS). The organic loading rates (OLRs) were maintained at a constant level of 3 kg VS/(m 3 ·d). Five different FW:WS substrate ratios were utilized in different operational phases. The synergetic effects of co-digestion improved the stability and performance of the reactors. When FW was mono-digested, both reactors were unstable. The mesophilic reactor eventually failed due to volatile fatty acid accumulation. The thermophilic reactor had better performance compared to mesophilic one. The biogas production rate of the thermophilic reactor was 4.9-14.8% higher than that of mesophilic reactor throughout the experiment. The shifts in microbial community structures throughout the experiment in both thermophilic and mesophilic reactors were investigated. With increasing FW proportions, bacteria belonging to the phylum Thermotogae became predominant in the thermophilic reactor, while the phylum Bacteroidetes was predominant in the mesophilic reactor. The genus Methanosarcina was the predominant methanogen in the thermophilic reactor, while the genus Methanothrix remained predominant in the mesophilic reactor. The methanogenesis pathway shifted from acetoclastic to hydrogenotrophic when the mesophilic reactor experienced perturbations. Moreover, the population of lignocellulose-degrading microorganisms in the thermophilic reactor was higher than those in mesophilic reactor, which explained the better performance of the thermophilic reactor. Copyright © 2018. Published by Elsevier Ltd.

Coupled reactor kinetics and heat transfer model for heat pipe cooled reactors

NASA Astrophysics Data System (ADS)

Wright, Steven A.; Houts, Michael

2001-02-01

Heat pipes are often proposed as cooling system components for small fission reactors. SAFE-300 and STAR-C are two reactor concepts that use heat pipes as an integral part of the cooling system. Heat pipes have been used in reactors to cool components within radiation tests (Deverall, 1973); however, no reactor has been built or tested that uses heat pipes solely as the primary cooling system. Heat pipe cooled reactors will likely require the development of a test reactor to determine the main differences in operational behavior from forced cooled reactors. The purpose of this paper is to describe the results of a systems code capable of modeling the coupling between the reactor kinetics and heat pipe controlled heat transport. Heat transport in heat pipe reactors is complex and highly system dependent. Nevertheless, in general terms it relies on heat flowing from the fuel pins through the heat pipe, to the heat exchanger, and then ultimately into the power conversion system and heat sink. A system model is described that is capable of modeling coupled reactor kinetics phenomena, heat transfer dynamics within the fuel pins, and the transient behavior of heat pipes (including the melting of the working fluid). This paper focuses primarily on the coupling effects caused by reactor feedback and compares the observations with forced cooled reactors. A number of reactor startup transients have been modeled, and issues such as power peaking, and power-to-flow mismatches, and loading transients were examined, including the possibility of heat flow from the heat exchanger back into the reactor. This system model is envisioned as a tool to be used for screening various heat pipe cooled reactor concepts, for designing and developing test facility requirements, for use in safety evaluations, and for developing test criteria for in-pile and out-of-pile test facilities. .

Technical Application of Nuclear Fission

NASA Astrophysics Data System (ADS)

Denschlag, J. O.

The chapter is devoted to the practical application of the fission process, mainly in nuclear reactors. After a historical discussion covering the natural reactors at Oklo and the first attempts to build artificial reactors, the fundamental principles of chain reactions are discussed. In this context chain reactions with fast and thermal neutrons are covered as well as the process of neutron moderation. Criticality concepts (fission factor η, criticality factor k) are discussed as well as reactor kinetics and the role of delayed neutrons. Examples of specific nuclear reactor types are presented briefly: research reactors (TRIGA and ILL High Flux Reactor), and some reactor types used to drive nuclear power stations (pressurized water reactor [PWR], boiling water reactor [BWR], Reaktor Bolshoi Moshchnosti Kanalny [RBMK], fast breeder reactor [FBR]). The new concept of the accelerator-driven systems (ADS) is presented. The principle of fission weapons is outlined. Finally, the nuclear fuel cycle is briefly covered from mining, chemical isolation of the fuel and preparation of the fuel elements to reprocessing the spent fuel and conditioning for deposit in a final repository.

Optimally moderated nuclear fission reactor and fuel source therefor

DOEpatents

Ougouag, Abderrafi M [Idaho Falls, ID; Terry, William K [Shelley, ID; Gougar, Hans D [Idaho Falls, ID

2008-07-22

An improved nuclear fission reactor of the continuous fueling type involves determining an asymptotic equilibrium state for the nuclear fission reactor and providing the reactor with a moderator-to-fuel ratio that is optimally moderated for the asymptotic equilibrium state of the nuclear fission reactor; the fuel-to-moderator ratio allowing the nuclear fission reactor to be substantially continuously operated in an optimally moderated state.

Flow rate analysis of wastewater inside reactor tanks on tofu wastewater treatment plant

NASA Astrophysics Data System (ADS)

Mamat; Sintawardani, N.; Astuti, J. T.; Nilawati, D.; Wulan, D. R.; Muchlis; Sriwuryandari, L.; Sembiring, T.; Jern, N. W.

2017-03-01

The research aimed to analyse the flow rate of the wastewater inside reactor tanks which were placed a number of bamboo cutting. The resistance of wastewater flow inside reactor tanks might not be occurred and produce biogas fuel optimally. Wastewater from eleven tofu factories was treated by multi-stages anaerobic process to reduce its organic pollutant and produce biogas. Biogas plant has six reactor tanks of which its capacity for waste water and gas dome was 18 m3 and 4.5 m3, respectively. Wastewater was pumped from collecting ponds to reactors by either serial or parallel way. Maximum pump capacity, head, and electrical motor power was 5m3/h, 50m, and 0.75HP, consecutively. Maximum pressure of biogas inside the reactor tanks was 55 mbar higher than atmosphere pressure. A number of 1,400 pieces of cutting bamboo at 50-60 mm diameter and 100 mm length were used as bacteria growth media inside each reactor tank, covering around 14,287 m2 bamboo area, and cross section area of inner reactor was 4,9 m2. In each reactor, a 6 inches PVC pipe was installed vertically as channel. When channels inside reactor were opened, flow rate of wastewater was 6x10-1 L.sec-1. Contrary, when channels were closed on the upper part, wastewater flow inside the first reactor affected and increased gas dome. Initially, wastewater flowed into each reactor by a gravity mode with head difference between the second and third reactor was 15x10-2m. However, head loss at the second reactor was equal to the third reactor by 8,422 x 10-4m. As result, wastewater flow at the second and third reactors were stagnant. To overcome the problem pump in each reactor should be installed in serial mode. In order to reach the output from the first reactor and the others would be equal, and biogas space was not filled by wastewater, therefore biogas production will be optimum.

Operators in the Plum Brook Reactor Facility Control Room

NASA Image and Video Library

1970-03-21

Donald Rhodes, left, and Clyde Greer, right, monitor the operation of the National Aeronautics and Space Administration’s (NASA) Plum Brook Reactor Facility from the control room. The 60-megawatt test reactor, NASA’s only reactor, was the eighth largest test reactor in the world. The facility was built by the Lewis Research Center in the late 1950s to study the effects of radiation on different materials that could be used to construct nuclear propulsion systems for aircraft or rockets. The reactor went critical for the first time in 1961. For the next two years, two operators were on duty 24 hours per day working on the fission process until the reactor reached its full-power level in 1963. Reactor Operators were responsible for monitoring and controlling the reactor systems. Once the reactor was running under normal operating conditions, the work was relatively uneventful. Normally the reactor was kept at a designated power level within certain limits. Occasionally the operators had to increase the power for a certain test. The shift supervisor and several different people would get together and discuss the change before boosting the power. All operators were required to maintain a Reactor Operator License from the Atomic Energy Commission. The license included six months of training, an eight-hour written exam, a four-hour walkaround, and testing on the reactor controls.

10 CFR 50.70 - Inspections.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Director, Office of Nuclear Reactor Regulation or Director, Office of New Reactors, as appropriate, provide... New Reactors, or the Director, Office of Nuclear Reactor Regulation. All furniture, supplies and... construction permit holder (nuclear power reactor only) shall ensure that the arrival and presence of an NRC...

10 CFR 50.70 - Inspections.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Director, Office of Nuclear Reactor Regulation or Director, Office of New Reactors, as appropriate, provide... New Reactors, or the Director, Office of Nuclear Reactor Regulation. All furniture, supplies and... construction permit holder (nuclear power reactor only) shall ensure that the arrival and presence of an NRC...

10 CFR 50.70 - Inspections.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Director, Office of Nuclear Reactor Regulation or Director, Office of New Reactors, as appropriate, provide... New Reactors, or the Director, Office of Nuclear Reactor Regulation. All furniture, supplies and... construction permit holder (nuclear power reactor only) shall ensure that the arrival and presence of an NRC...

10 CFR 50.70 - Inspections.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Director, Office of Nuclear Reactor Regulation or Director, Office of New Reactors, as appropriate, provide... New Reactors, or the Director, Office of Nuclear Reactor Regulation. All furniture, supplies and... construction permit holder (nuclear power reactor only) shall ensure that the arrival and presence of an NRC...

10 CFR 50.70 - Inspections.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Director, Office of Nuclear Reactor Regulation or Director, Office of New Reactors, as appropriate, provide... New Reactors, or the Director, Office of Nuclear Reactor Regulation. All furniture, supplies and... construction permit holder (nuclear power reactor only) shall ensure that the arrival and presence of an NRC...

10 CFR 2.101 - Filing of application.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Reactors, the Director, Office of Nuclear Reactor Regulation, the Director, Office of Nuclear Material... Nuclear Reactor Regulation, Director, Office of New Reactors, Director, Office of Federal and State... be requested to: (i) Submit to the Director, Office of Nuclear Reactor Regulation, Director, Office...

10 CFR 2.101 - Filing of application.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Reactors, the Director, Office of Nuclear Reactor Regulation, the Director, Office of Nuclear Material... Nuclear Reactor Regulation, Director, Office of New Reactors, Director, Office of Federal and State... be requested to: (i) Submit to the Director, Office of Nuclear Reactor Regulation, Director, Office...

An Analysis of Ionospheric Thermal Ions Using a SIMION-based Forward Instrument Model: In Situ Observations of Vertical Thermal Ion Flows as Measured by the MICA Sounding Rocket

NASA Astrophysics Data System (ADS)

Fernandes, P. A.; Lynch, K. A.; Zettergren, M. D.; Hampton, D. L.; Fisher, L. E.; Powell, S. P.

2013-12-01

The MICA sounding rocket launched on 19 Feb. 2012 into several discrete, localized arcs in the wake of a westward traveling surge. In situ and ground-based observations provide a measured response of the ionosphere to preflight and localized auroral drivers. In this presentation we focus on in situ measurements of the thermal ion distribution. We observe thermal ions flowing both up and down the auroral field line, with upflows concentrated in Alfvénic and downward current regions. The in situ data are compared with recent ionospheric modeling efforts (Zettergren et al., this session) which show structured patterns of ion upflow and downflow consistent with these observations. In the low-energy thermal plasma regime, instrument response to the measured thermal ion population is very sensitive to the presence of the instrument. The plasma is shifted and accelerated in the frame of the instrument due to flows, ram, and acceleration through the payload sheath. The energies associated with these processes are large compared to the thermal energy. Rigorous quantitative analysis of the instrument response is necessary to extract the plasma properties which describe the full 3D distribution function at the instrument aperture. We introduce an instrument model, developed in the commercial software package SIMION, to characterize instrument response at low energies. The instrument model provides important insight into how we would modify our instrument for future missions, including fine-tuning parameters such as the analyzer sweep curve, the geometry factor, and the aperture size. We use the results from the instrument model to develop a forward model, from which we can extract anisotropic ion temperatures, flows, and density of the thermal plasma at the aperture. Because this plasma has transited a sheath to reach the aperture, we must account for the acceleration due to the sheath. Modeling of this complex sheath is being conducted by co-author Fisher, using a PIC code created with the Spacecraft Plasma Interaction Software (SPIS). Once we have coupled the instrument and forward models to this sophisticated sheath model, we can rigorously extract the properties of the background thermal plasma. These thermal plasma measurements are used to address questions of ionospheric-thermospheric coupling. These questions for MICA and its modeling efforts include the following: is the state of the ionosphere during the rocket flight a remnant of the westward traveling surge, or is it a direct response to localized drivers? How do the calculated ion flows compare to the flows derived from the electric field data, and what do these flows tell us about the state of the ionosphere? How do the MICA measurements of ion upflows and downflows tie into the broader sounding rocket ion parallel flow study presented by Lynch et al. (this session) and into the Zettergren and Semeter, [2012] 2D, ionospheric fluid/electrostatic model?

Delayed Neutrino-Driven Supernova Explosions Aided by the Standing Accretion-Shock Instability

NASA Astrophysics Data System (ADS)

Marek, A.; Janka, H.-Th.

2009-03-01

We present two-dimensional hydrodynamic simulations of stellar core collapse and develop the framework for a detailed analysis of the energetic aspects of neutrino-powered supernova explosions. Our results confirm that the neutrino-heating mechanism remains a viable explanation of the explosion of a wider mass range of supernova progenitors with iron cores, but the explosion sets in later and develops differently than thought so far. The calculations were performed with an energy-dependent treatment of the neutrino transport based on the "ray-by-ray plus" approximation, in which the neutrino number, energy, and momentum equations are closed with a variable Eddington factor obtained by iteratively solving a model Boltzmann equation. We focus here on the evolution of a 15 M sun progenitor and provide evidence that shock revival and an explosion are initiated at about 600 ms after core bounce, powered by neutrino energy deposition. This is significantly later than previously found for an 11.2 M sun star, for which we also present a continuation of the explosion model published by Buras et al. The onset of the blast is fostered in both cases by the standing accretion-shock instability. This instability exhibits highest growth rates for the dipole and quadrupole modes, which lead to large-amplitude bipolar shock oscillations and push the shock to larger radii, thus increasing the time accreted matter is exposed to neutrino heating in the gain layer. As a consequence, also convective overturn behind the shock is strengthened, which otherwise is suppressed or damped because of the small shock stagnation radius. When the explosion sets in, the shock reveals a pronounced global deformation with a dominant dipolar component. In both the 11.2 M sun and 15 M sun explosions long-lasting equatorial downflows supply the gain layer with fresh gas, of which a sizable fraction is heated by neutrinos and leads to the build-up of the explosion energy of the ejecta over possibly hundreds of milliseconds. A "soft" nuclear equation of state that causes a rapid contraction, and a smaller radius of the forming neutron star and thus a fast release of gravitational binding energy, seems to be more favorable for the development of an explosion. Rotation has the opposite effect because in the long run it leads to a more extended and cooler neutron star and thus lower neutrino luminosities and mean energies and overall less neutrino heating. Neutron star g-mode oscillations, although we see their presence, and the acoustic mechanism play no important role in our simulations. While numerical tests show that our code is also well able to follow large-amplitude core g-modes if they are instigated; the amplitude of such oscillations remains small in our supernova runs and the acoustic energy flux injected by the ringing neutron star and by the deceleration of supersonic downflows near the neutron star surface is small compared to the neutrino energy deposition.

Subaqueous ice-contact fans: Depositional systems characterised by highly aggradational supercritical flow conditions

NASA Astrophysics Data System (ADS)

Lang, Joerg; Winsemann, Jutta

2015-04-01

Subaqueous ice-contact fans are deposited by high-energy plane-wall jets from subglacial conduits into standing water bodies. Highly aggradational conditions during flow expansion and deceleration allow for the preservation of bedforms related to supercritical flows, which are commonly considered rare in the depositional record. We present field examples from gravelly and sandy subaqueous ice-contact fan successions, which indicate that deposition by supercritical flows might be considered as a characteristic feature of these depositional systems. The studied successions were deposited in deep ice-dammed lakes, which formed along the margins of the Middle Pleistocene Scandinavian ice sheets across Northern Germany. The gravel-rich subaqueous fan deposits are dominated by large scour-fills (up to 25 m wide and 3 m) deep and deposits of turbulent hyperconcentrated flows, which are partly attributed to supercritical flow conditions (Winsemann et al., 2009). Scours (up to 4.5 m wide and 0.9 m deep) infilled by gravelly backsets are observed above laterally extensive erosional surfaces and are interpreted as deposits of cyclic steps. Laterally discontinuous beds of low-angle cross-stratified gravel are interpreted as antidune deposits. Downflow and up-section the gravel-rich deposits pass into sand-rich successions, which include deposits of chutes-and-pools, breaking antidunes, stationary antidunes and humpback dunes (Lang and Winsemann, 2013). Deposits of chutes-and-pools and breaking antidunes are characterised by scour-fills (up to 4 m wide and 1.2 m deep) comprising backsets or gently dipping sigmoidal foresets. Stationary antidune deposits consist of laterally extensive sinusoidal waveforms with long wavelengths (1-12 m) and low amplitudes (0.1-0.5 m), which formed under quasi-steady flows at the lower limit of the supercritical flow stage and high rates of sedimentation. Humpback dunes are characterised by divergent sigmoidal foresets and are interpreted as bedforms related to transcritical flow conditions. Deposits of aggrading stationary antidunes and humpback dunes represent a characteristic facies association of the distal zone of flow transition. Downflow the succession passes into deposits of large 3D dunes and climbing ripples. The large-scale lateral and vertical successions of bedforms are interpreted as representing the temporal and spatial evolution of the supercritical meltwater jets, which was affected by hydraulic jumps. Small-scale facies changes and the formation of individual bedforms are interpreted as controlled by fluctuating discharge, pulsating unstable flows and bed topography. References: Lang, J., Winsemann, J. (2013) Lateral and vertical facies relationships of bedforms deposited by aggrading supercritical flows: from cyclic steps to humpback dunes. Sedimentary Geology 296, 36-54. Winsemann, J., Hornung, J.J., Meinsen, J., Asprion, U., Polom, U., Brandes, C., Bussmann, M., Weber, C., (2009) Anatomy of a subaqueous ice-contact fan and delta complex, Middle Pleistocene, North-west Germany, Sedimentology 56, 1041-1076.

Weld monitor and failure detector for nuclear reactor system

DOEpatents

Sutton, Jr., Harry G.

1987-01-01

Critical but inaccessible welds in a nuclear reactor system are monitored throughout the life of the reactor by providing small aperture means projecting completely through the reactor vessel wall and also through the weld or welds to be monitored. The aperture means is normally sealed from the atmosphere within the reactor. Any incipient failure or cracking of the weld will cause the environment contained within the reactor to pass into the aperture means and thence to the outer surface of the reactor vessel where its presence is readily detected.

Demonstration of Robustness and Integrated Operation of a Series-Bosch System

NASA Technical Reports Server (NTRS)

Abney, Morgan B.; Mansell, Matthew J.; Stanley, Christine; Barnett, Bill; Junaedi, Christian; Vilekar, Saurabh A.; Ryan, Kent

2016-01-01

Manned missions beyond low Earth orbit will require highly robust, reliable, and maintainable life support systems that maximize recycling of water and oxygen. Bosch technology is one option to maximize oxygen recovery, in the form of water, from metabolically-produced carbon dioxide (CO2). A two stage approach to Bosch, called Series-Bosch, reduces metabolic CO2 with hydrogen (H2) to produce water and solid carbon using two reactors: a Reverse Water-Gas Shift (RWGS) reactor and a carbon formation (CF) reactor. Previous development efforts demonstrated the stand-alone performance of a NASA-designed RWGS reactor designed for robustness against carbon formation, two membrane separators intended to maximize single pass conversion of reactants, and a batch CF reactor with both transit and surface catalysts. In the past year, Precision Combustion, Inc. (PCI) developed and delivered a RWGS reactor for testing at NASA. The reactor design was based on their patented Microlith® technology and was first evaluated under a Phase I Small Business Innovative Research (SBIR) effort in 2010. The RWGS reactor was recently evaluated at NASA to compare its performance and operating conditions with NASA's RWGS reactor. The test results will be provided in this paper. Separately, in 2015, a semi-continuous CF reactor was designed and fabricated at NASA based on the results from batch CF reactor testing. The batch CF reactor and the semi-continuous CF reactor were individually integrated with an upstream RWGS reactor to demonstrate the system operation and to evaluate performance. Here, we compare the performance and robustness to carbon formation of both RWGS reactors. We report the results of the integrated operation of a Series-Bosch system and we discuss the technology readiness level.

Reactor water cleanup system

DOEpatents

Gluntz, Douglas M.; Taft, William E.

1994-01-01

A reactor water cleanup system includes a reactor pressure vessel containing a reactor core submerged in reactor water. First and second parallel cleanup trains are provided for extracting portions of the reactor water from the pressure vessel, cleaning the extracted water, and returning the cleaned water to the pressure vessel. Each of the cleanup trains includes a heat exchanger for cooling the reactor water, and a cleaner for cleaning the cooled reactor water. A return line is disposed between the cleaner and the pressure vessel for channeling the cleaned water thereto in a first mode of operation. A portion of the cooled water is bypassed around the cleaner during a second mode of operation and returned through the pressure vessel for shutdown cooling.

The role of nuclear reactors in space exploration and development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lipinski, R.J.

2000-07-01

The United States has launched more than 20 radioisotopic thermoelectric generators (RTGs) into space over the past 30 yr but has launched only one nuclear reactor, and that was in 1965. Russia has launched more than 30 reactors. The RTGs use the heat of alpha decay of {sup 238}Pu for power and typically generate <1 kW of electricity. Apollo, Pioneer, Voyager, Viking, Galileo, Ulysses, and Cassini all used RTGs. Space reactors use the fission energy of {sup 235}U; typical designs are for 100 to 1000 kW of electricity. The only US space reactor launch (SNAP-10A) was a demonstration mission. Onemore » reason for the lack of space reactor use by the United States was the lack of space missions that required high power. But, another was the assumed negative publicity that would accompany a reactor launch. The net result is that all space reactor programs after 1970 were terminated before an operating space reactor could be developed, and they are now many years from recovering the ability to build them. Two major near-term needs for space reactors are the human exploration of Mars and advanced missions to and beyond the orbit of Jupiter. To help obtain public acceptance of space reactors, one must correct some of the misconceptions concerning space reactors and convey the following facts to the public and to decision makers: Space reactors are 1000 times smaller in power and size than a commercial power reactor. A space reactor at launch is only as radioactive as a pile of dirt 60 m (200 ft) across. A space reactor contains no plutonium at launch. It does not become significantly radioactive until it is turned on, and it will be engineered so that no launch accident can turn it on, even if that means fueling it after launch. The reactor will not be turned on until it is in a high stable orbit or even on an earth-escape trajectory for some missions. The benefits of space reactors are that they give humanity a stairway to the planets and perhaps the stars. They open a new frontier for their children and their grandchildren. They pave the way for all life on earth to move out into the solar system. At one time, humans built and flew space reactors; it is time to do so again.« less

Degradation of Acid Orange 7 Dye in Two Hybrid Plasma Discharge Reactors

NASA Astrophysics Data System (ADS)

Shen, Yongjun; Lei, Lecheng; Zhang, Xingwang; Ding, Jiandong

2014-11-01

To get an optimized pulsed electrical plasma discharge reactor and to increase the energy utilization efficiency in the removal of pollutants, two hybrid plasma discharge reactors were designed and optimized. The reactors were compared via the discharge characteristics, energy transfer efficiency, the yields of the active species and the energy utilization in dye wastewater degradation. The results showed that under the same AC input power, the characteristics of the discharge waveform of the point-to-plate reactor were better. Under the same AC input power, the two reactors both had almost the same peak voltage of 22 kV. The peak current of the point-to-plate reactor was 146 A, while that of the wire-to-cylinder reactor was only 48.8 A. The peak powers of the point-to-plate reactor and the wire-to-cylinder reactor were 1.38 MW and 1.01 MW, respectively. The energy per pulse of the point-to-plate reactor was 0.2221 J, which was about 29.4% higher than that of the wire-to-cylinder reactor (0.1716 J). To remove 50% Acid Orange 7 (AO7), the energy utilizations of the point-to-plate reactor and the wire-to-cylinder reactor were 1.02 × 10-9 mol/L and 0.61 × 10-9 mol/L, respectively. In the point-to-plate reactor, the concentration of hydrogen peroxide in pure water was 3.6 mmol/L after 40 min of discharge, which was higher than that of the wire-to-cylinder reactor (2.5 mmol/L). The concentration of liquid phase ozone in the point-to-plate reactor (5.7 × 10-2 mmol/L) was about 26.7% higher than that in the wire-to-cylinder reactor (4.5 × 10-2 mmol/L). The analysis results of the variance showed that the type of reactor and reaction time had significant impacts on the yields of the hydrogen peroxide and ozone. The main degradation intermediates of AO7 identified by gas chromatography and mass spectrometry (GCMS) were acetic acid, maleic anhydride, p-benzoquinone, phenol, benzoic acid, phthalic anhydride, coumarin and 2-naphthol. Proposed degradation pathways were elucidated in light of the analyzed degradation products.

10 CFR 72.1 - Purpose.

Code of Federal Regulations, 2011 CFR

2011-01-01

... RADIOACTIVE WASTE, AND REACTOR-RELATED GREATER THAN CLASS C WASTE General Provisions § 72.1 Purpose. The... receive, transfer, and possess power reactor spent fuel, power reactor-related Greater than Class C (GTCC... reactor spent fuel, high-level radioactive waste, power reactor-related GTCC waste, and other radioactive...

10 CFR 72.1 - Purpose.

Code of Federal Regulations, 2010 CFR

2010-01-01

... RADIOACTIVE WASTE, AND REACTOR-RELATED GREATER THAN CLASS C WASTE General Provisions § 72.1 Purpose. The... receive, transfer, and possess power reactor spent fuel, power reactor-related Greater than Class C (GTCC... reactor spent fuel, high-level radioactive waste, power reactor-related GTCC waste, and other radioactive...

Unmixed fuel processors and methods for using the same

DOEpatents

Kulkarni, Parag Prakash; Cui, Zhe

2010-08-24

Disclosed herein are unmixed fuel processors and methods for using the same. In one embodiment, an unmixed fuel processor comprises: an oxidation reactor comprising an oxidation portion and a gasifier, a CO.sub.2 acceptor reactor, and a regeneration reactor. The oxidation portion comprises an air inlet, effluent outlet, and an oxygen transfer material. The gasifier comprises a solid hydrocarbon fuel inlet, a solids outlet, and a syngas outlet. The CO.sub.2 acceptor reactor comprises a water inlet, a hydrogen outlet, and a CO.sub.2 sorbent, and is configured to receive syngas from the gasifier. The regeneration reactor comprises a water inlet and a CO.sub.2 stream outlet. The regeneration reactor is configured to receive spent CO.sub.2 adsorption material from the gasification reactor and to return regenerated CO.sub.2 adsorption material to the gasification reactor, and configured to receive oxidized oxygen transfer material from the oxidation reactor and to return reduced oxygen transfer material to the oxidation reactor.

Thermionic switched self-actuating reactor shutdown system

DOEpatents

Barrus, Donald M.; Shires, Charles D.; Brummond, William A.

1989-01-01

A self-actuating reactor shutdown system incorporating a thermionic switched electromagnetic latch arrangement which is responsive to reactor neutron flux changes and to reactor coolant temperature changes. The system is self-actuating in that the sensing thermionic device acts directly to release (scram) the control rod (absorber) without reference or signal from the main reactor plant protective and control systems. To be responsive to both temperature and neutron flux effects, two detectors are used, one responsive to reactor coolant temperatures, and the other responsive to reactor neutron flux increase. The detectors are incorporated into a thermionic diode connected electrically with an electromagnetic mechanism which under normal reactor operating conditions holds the the control rod in its ready position (exterior of the reactor core). Upon reaching either a specified temperature or neutron flux, the thermionic diode functions to short-circuit the electromagnetic mechanism causing same to lose its holding power and release the control rod, which drops into the reactor core region under gravitational force.

Thermal insulating barrier and neutron shield providing integrated protection for a nuclear reactor vessel

DOEpatents

Schreiber, R.B.; Fero, A.H.; Sejvar, J.

1997-12-16

The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel to form a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive valving also includes bistable vents at the upper end of the thermal insulating barrier for releasing steam. A removable, modular neutron shield extending around the upper end of the reactor cavity below the nozzles forms with the upwardly and outwardly tapered transition on the outer surface of the reactor vessel, a labyrinthine channel which reduces neutron streaming while providing a passage for the escape of steam during a severe accident, and for the cooling air which is circulated along the reactor cavity walls outside the thermal insulating barrier during normal operation of the reactor. 8 figs.

Thermal insulating barrier and neutron shield providing integrated protection for a nuclear reactor vessel

DOEpatents

Schreiber, Roger B.; Fero, Arnold H.; Sejvar, James

1997-01-01

The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel to form a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive valving also includes bistable vents at the upper end of the thermal insulating barrier for releasing steam. A removable, modular neutron shield extending around the upper end of the reactor cavity below the nozzles forms with the upwardly and outwardly tapered transition on the outer surface of the reactor vessel, a labyrinthine channel which reduces neutron streaming while providing a passage for the escape of steam during a severe accident, and for the cooling air which is circulated along the reactor cavity walls outside the thermal insulating barrier during normal operation of the reactor.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soldevilla, M.; Salmons, S.; Espinosa, B.

The new application BDDR (Reactor database) has been developed at CEA in order to manage nuclear reactors technological and operating data. This application is a knowledge management tool which meets several internal needs: -) to facilitate scenario studies for any set of reactors, e.g. non-proliferation assessments; -) to make core physics studies easier, whatever the reactor design (PWR-Pressurized Water Reactor-, BWR-Boiling Water Reactor-, MAGNOX- Magnesium Oxide reactor-, CANDU - CANada Deuterium Uranium-, FBR - Fast Breeder Reactor -, etc.); -) to preserve the technological data of all reactors (past and present, power generating or experimental, naval propulsion,...) in a uniquemore » repository. Within the application database are enclosed location data and operating history data as well as a tree-like structure containing numerous technological data. These data address all kinds of reactors features and components. A few neutronics data are also included (neutrons fluxes). The BDDR application is based on open-source technologies and thin client/server architecture. The software architecture has been made flexible enough to allow for any change. (authors)« less

Propellant actuated nuclear reactor steam depressurization valve

DOEpatents

Ehrke, Alan C.; Knepp, John B.; Skoda, George I.

1992-01-01

A nuclear fission reactor combined with a propellant actuated depressurization and/or water injection valve is disclosed. The depressurization valve releases pressure from a water cooled, steam producing nuclear reactor when required to insure the safety of the reactor. Depressurization of the reactor pressure vessel enables gravity feeding of supplementary coolant water through the water injection valve to the reactor pressure vessel to prevent damage to the fuel core.

NEUTRONIC REACTOR CONSTRUCTION AND OPERATION

DOEpatents

West, J.M.; Weills, J.T.

1960-03-15

A method is given for operating a nuclear reactor having a negative coefficient of reactivity to compensate for the change in reactor reactivity due to the burn-up of the xenon peak following start-up of the reactor. When it is desired to start up the reactor within less than 72 hours after shutdown, the temperature of the reactor is lowered prior to start-up, and then gradually raised after start-up.

Thermal-hydraulic interfacing code modules for CANDU reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, W.S.; Gold, M.; Sills, H.

1997-07-01

The approach for CANDU reactor safety analysis in Ontario Hydro Nuclear (OHN) and Atomic Energy of Canada Limited (AECL) is presented. Reflecting the unique characteristics of CANDU reactors, the procedure of coupling the thermal-hydraulics, reactor physics and fuel channel/element codes in the safety analysis is described. The experience generated in the Canadian nuclear industry may be useful to other types of reactors in the areas of reactor safety analysis.

97. ARAIII. ML1 reactor has been moved into GCRE reactor ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

97. ARA-III. ML-1 reactor has been moved into GCRE reactor building (ARA-608) for examination of corrosion on its underside and repair. May 24, 1963. Ineel photo no. 63-3485. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

NEUTRONIC REACTOR MANIPULATING DEVICE

DOEpatents

Ohlinger, L.A.

1962-08-01

A cable connecting a control rod in a reactor with a motor outside the reactor for moving the rod, and a helical conduit in the reactor wall, through which the cable passes are described. The helical shape of the conduit prevents the escape of certain harmful radiations from the reactor. (AEC)

40 CFR 63.1406 - Reactor batch process vent provisions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 11 2011-07-01 2011-07-01 false Reactor batch process vent provisions... § 63.1406 Reactor batch process vent provisions. (a) Emission standards. Owners or operators of reactor... reactor batch process vent located at a new affected source shall control organic HAP emissions by...

78 FR 73898 - Operator Licensing Examination Standards for Power Reactors

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-09

... Reactors AGENCY: Nuclear Regulatory Commission. ACTION: Draft NUREG; request for comment. SUMMARY: The U.S..., Revision 10, ``Operator Licensing Examination Standards for Power Reactors.'' DATES: Submit comments [email protected] . Both of the Office of New Reactors; or Timothy Kolb, Office of Nuclear Reactor Regulation, U...

76 FR 55718 - Advisory Committee on Reactor Safeguards (ACRS); Meeting of the ACRS Subcommittee on Materials...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-08

... NUCLEAR REGULATORY COMMISSION Advisory Committee on Reactor Safeguards (ACRS); Meeting of the ACRS Subcommittee on Materials, Metallurgy & Reactor Fuels The ACRS Subcommittee on Materials, Metallurgy & Reactor...'' for reactor coolant system (RCS) components, as mentioned in 10 CFR 50 Appendix A, GDC-4. The...

40 CFR 63.1406 - Reactor batch process vent provisions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Reactor batch process vent provisions... § 63.1406 Reactor batch process vent provisions. (a) Emission standards. Owners or operators of reactor... reactor batch process vent located at a new affected source shall control organic HAP emissions by...

75 FR 58449 - Advisory Committee on Reactor Safeguards (ACRS); Meeting of the ACRS Subcommittee on Materials...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-24

... NUCLEAR REGULATORY COMMISSION Advisory Committee on Reactor Safeguards (ACRS); Meeting of the ACRS Subcommittee on Materials, Metallurgy & Reactor Fuels The ACRS Subcommittee on Materials, Metallurgy & Reactor... would result in a major inconvenience. Dated: September 17, 2010. Antonio Dias, Chief, Reactor Safety...

151. ARAIII Reactor building (ARA608) Details of reactor pit and ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

151. ARA-III Reactor building (ARA-608) Details of reactor pit and instrument plan. Aerojet-general 880-area/GCRE-608-T-19. Date: November 1958. Ineel index code no. 063-0608-25-013-102678. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

10 CFR 72.120 - General considerations.

Code of Federal Regulations, 2010 CFR

2010-01-01

... NUCLEAR FUEL, HIGH-LEVEL RADIOACTIVE WASTE, AND REACTOR-RELATED GREATER THAN CLASS C WASTE General Design... reactor-related GTCC waste in an ISFSI or to store spent fuel, high-level radioactive waste, or reactor... be designed to store spent fuel and/or solid reactor-related GTCC waste. (1) Reactor-related GTCC...

ADVANCED REACTIVITY MEASUREMENT FACILITY, TRA660, INTERIOR. REACTOR INSIDE TANK. METAL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

ADVANCED REACTIVITY MEASUREMENT FACILITY, TRA-660, INTERIOR. REACTOR INSIDE TANK. METAL WORK PLATFORM ABOVE. THE REACTOR WAS IN A SMALL WATER-FILLED POOL. INL NEGATIVE NO. 66-6373. Unknown Photographer, ca. 1966 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

10 CFR 50.30 - Filing of application; oath or affirmation.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Reactor Regulation, Director, Office of New Reactors, or Director, Office of Nuclear Material Safety and... Director, Office of New Reactors, or the Director, Office of Nuclear Reactor Regulation, or the Director..., operating license, early site permit, combined license, or manufacturing license for a nuclear power reactor...

10 CFR 50.30 - Filing of application; oath or affirmation.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Reactor Regulation, Director, Office of New Reactors, or Director, Office of Nuclear Material Safety and... Director, Office of New Reactors, or the Director, Office of Nuclear Reactor Regulation, or the Director..., operating license, early site permit, combined license, or manufacturing license for a nuclear power reactor...

10 CFR 50.30 - Filing of application; oath or affirmation.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Reactor Regulation, Director, Office of New Reactors, or Director, Office of Nuclear Material Safety and... Director, Office of New Reactors, or the Director, Office of Nuclear Reactor Regulation, or the Director..., operating license, early site permit, combined license, or manufacturing license for a nuclear power reactor...

10 CFR 50.30 - Filing of application; oath or affirmation.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Reactor Regulation, Director, Office of New Reactors, or Director, Office of Nuclear Material Safety and... Director, Office of New Reactors, or the Director, Office of Nuclear Reactor Regulation, or the Director..., operating license, early site permit, combined license, or manufacturing license for a nuclear power reactor...

A Review of Gas-Cooled Reactor Concepts for SDI Applications

DTIC Science & Technology

1989-08-01

710 program .) Wire- Core Reactor (proposed by Rockwell). The wire- core reactor utilizes thin fuel wires woven between spacer wires to form an open...reactor is based on results of developmental studies of nuclear rocket propulsion systems. The reactor core is made up of annular fuel assemblies of...XE Addendum to Volume II. NERVA Fuel Development , Westinghouse Astronuclear Laboratory, TNR-230, July 15’ 1972. J I8- Rover Program Reactor Tests

Computer study of emergency shutdowns of a 60-kilowatt reactor Brayton space power system

NASA Technical Reports Server (NTRS)

Tew, R. C.; Jefferies, K. S.

1974-01-01

A digital computer study of emergency shutdowns of a 60-kWe reactor Brayton power system was conducted. Malfunctions considered were (1) loss of reactor coolant flow, (2) loss of Brayton system gas flow, (3)turbine overspeed, and (4) a reactivity insertion error. Loss of reactor coolant flow was the most serious malfunction for the reactor. Methods for moderating the reactor transients due to this malfunction are considered.

Function of university reactors in operator licensing training for nuclear utilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wicks, F.

1985-11-01

The director of the Division of the US Nuclear Regulatory Commission in generic letter 84-10, dated April 26, 1984, spoke the requirement that applicants for senior reactor operator licenses for power reactors shall have performed then reactor startups. Simulator startups were not acknowledged. Startups performed on a university reactor are acceptable. The content and results of a five-day program combining instruction and experiments with the Rensselaer reactor are summarized.

Numerical Simulations of a 96-rod Polysilicon CVD Reactor

NASA Astrophysics Data System (ADS)

Guoqiang, Tang; Cong, Chen; Yifang, Cai; Bing, Zong; Yanguo, Cai; Tihu, Wang

2018-05-01

With the rapid development of the photovoltaic industry, pressurized Siemens belljar-type polysilicon CVD reactors have been enlarged from 24 rods to 96 rods in less than 10 years aimed at much greater single-reactor productivity. A CFD model of an industry-scale 96-rod CVD reactor was established to study the internal temperature distribution and the flow field of the reactor. Numerical simulations were carried out and compared with actual growth results from a real CVD reactor. Factors affecting polysilicon depositions such as inlet gas injections, flow field, and temperature distribution in the CVD reactor are studied.

Reactor water cleanup system

DOEpatents

Gluntz, D.M.; Taft, W.E.

1994-12-20

A reactor water cleanup system includes a reactor pressure vessel containing a reactor core submerged in reactor water. First and second parallel cleanup trains are provided for extracting portions of the reactor water from the pressure vessel, cleaning the extracted water, and returning the cleaned water to the pressure vessel. Each of the cleanup trains includes a heat exchanger for cooling the reactor water, and a cleaner for cleaning the cooled reactor water. A return line is disposed between the cleaner and the pressure vessel for channeling the cleaned water thereto in a first mode of operation. A portion of the cooled water is bypassed around the cleaner during a second mode of operation and returned through the pressure vessel for shutdown cooling. 1 figure.

Characteristics and Dose Levels for Spent Reactor Fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coates, Cameron W

2007-01-01

Current guidance considers highly radioactive special nuclear materials to be those materials that, unshielded, emit a radiation dose [rate] measured at 1 m which exceeds 100 rem/h. Smaller, less massive fuel assemblies from research reactors can present a challenge from the point of view of self protection because of their size (lower dose, easier to handle) and the desirability of higher enrichments; however, a follow-on study to cross-compare dose trends of research reactors and power reactors was deemed useful to confirm/verify these trends. This paper summarizes the characteristics and dose levels of spent reactor fuels for both research reactors andmore » power reactors and extends previous studies aimed at quantifying expected dose rates from research reactor fuels worldwide.« less

Comparing the new generation accelerator driven subcritical reactor system (ADS) to traditional critical reactors

NASA Astrophysics Data System (ADS)

Kemah, Elif; Akkaya, Recep; Tokgöz, Seyit Rıza

2017-02-01

In recent years, the accelerator driven subcritical reactors have taken great interest worldwide. The Accelerator Driven System (ADS) has been used to produce neutron in subcritical state by the external proton beam source. These reactors, which are hybrid systems, are important in production of clean and safe energy and conversion of radioactive waste. The ADS with the selection of reliability and robust target materials have been the new generation of fission reactors. In addition, in the ADS Reactors the problems of long-lived radioactive fission products and waste actinides encountered in the fission process of the reactor during incineration can be solved, and ADS has come to the forefront of thorium as fuel for the reactors.

Reactor operation environmental information document

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haselow, J.S.; Price, V.; Stephenson, D.E.

1989-12-01

The Savannah River Site (SRS) produces nuclear materials, primarily plutonium and tritium, to meet the requirements of the Department of Defense. These products have been formed in nuclear reactors that were built during 1950--1955 at the SRS. K, L, and P reactors are three of five reactors that have been used in the past to produce the nuclear materials. All three of these reactors discontinued operation in 1988. Currently, intense efforts are being extended to prepare these three reactors for restart in a manner that protects human health and the environment. To document that restarting the reactors will have minimalmore » impacts to human health and the environment, a three-volume Reactor Operations Environmental Impact Document has been prepared. The document focuses on the impacts of restarting the K, L, and P reactors on both the SRS and surrounding areas. This volume discusses the geology, seismology, and subsurface hydrology. 195 refs., 101 figs., 16 tabs.« less

Auxiliary reactor for a hydrocarbon reforming system

DOEpatents

Clawson, Lawrence G.; Dorson, Matthew H.; Mitchell, William L.; Nowicki, Brian J.; Bentley, Jeffrey M.; Davis, Robert; Rumsey, Jennifer W.

2006-01-17

An auxiliary reactor for use with a reformer reactor having at least one reaction zone, and including a burner for burning fuel and creating a heated auxiliary reactor gas stream, and heat exchanger for transferring heat from auxiliary reactor gas stream and heat transfer medium, preferably two-phase water, to reformer reaction zone. Auxiliary reactor may include first cylindrical wall defining a chamber for burning fuel and creating a heated auxiliary reactor gas stream, the chamber having an inlet end, an outlet end, a second cylindrical wall surrounding first wall and a second annular chamber there between. The reactor being configured so heated auxiliary reactor gas flows out the outlet end and into and through second annular chamber and conduit which is disposed in second annular chamber, the conduit adapted to carry heat transfer medium and being connectable to reformer reaction zone for additional heat exchange.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lister, Tedd E; Parkman, Jacob A; Diaz Aldana, Luis A

A method of recovering metals from electronic waste comprises providing a powder comprising electronic waste in at least a first reactor and a second reactor and providing an electrolyte comprising at least ferric ions in an electrochemical cell in fluid communication with the first reactor and the second reactor. The method further includes contacting the powders within the first reactor and the second reactor with the electrolyte to dissolve at least one base metal from each reactor into the electrolyte and reduce at least some of the ferric ions to ferrous ions. The ferrous ions are oxidized at an anodemore » of the electrochemical cell to regenerate the ferric ions. The powder within the second reactor comprises a higher weight percent of the at least one base metal than the powder in the first reactor. Additional methods of recovering metals from electronic waste are also described, as well as an apparatus of recovering metals from electronic waste.« less

High-intensity power-resolved radiation imaging of an operational nuclear reactor.

PubMed

Beaumont, Jonathan S; Mellor, Matthew P; Villa, Mario; Joyce, Malcolm J

2015-10-09

Knowledge of the neutron distribution in a nuclear reactor is necessary to ensure the safe and efficient burnup of reactor fuel. Currently these measurements are performed by in-core systems in what are extremely hostile environments and in most reactor accident scenarios it is likely that these systems would be damaged. Here we present a compact and portable radiation imaging system with the ability to image high-intensity fast-neutron and gamma-ray fields simultaneously. This system has been deployed to image radiation fields emitted during the operation of a TRIGA test reactor allowing a spatial visualization of the internal reactor conditions to be obtained. The imaged flux in each case is found to scale linearly with reactor power indicating that this method may be used for power-resolved reactor monitoring and for the assay of ongoing nuclear criticalities in damaged nuclear reactors.

Exploratory study of several advanced nuclear-MHD power plant systems.

NASA Technical Reports Server (NTRS)

Williams, J. R.; Clement, J. D.; Rosa, R. J.; Yang, Y. Y.

1973-01-01

In order for efficient multimegawatt closed cycle nuclear-MHD systems to become practical, long-life gas cooled reactors with exit temperatures of about 2500 K or higher must be developed. Four types of nuclear reactors which have the potential of achieving this goal are the NERVA-type solid core reactor, the colloid core (rotating fluidized bed) reactor, the 'light bulb' gas core reactor, and the 'coaxial flow' gas core reactor. Research programs aimed at developing these reactors have progressed rapidly in recent years so that prototype power reactors could be operating by 1980. Three types of power plant systems which use these reactors have been analyzed to determine the operating characteristics, critical parameters and performance of these power plants. Overall thermal efficiencies as high as 80% are projected, using an MHD turbine-compressor cycle with steam bottoming, and slightly lower efficiencies are projected for an MHD motor-compressor cycle.

High-intensity power-resolved radiation imaging of an operational nuclear reactor

PubMed Central

Beaumont, Jonathan S.; Mellor, Matthew P.; Villa, Mario; Joyce, Malcolm J.

2015-01-01

Knowledge of the neutron distribution in a nuclear reactor is necessary to ensure the safe and efficient burnup of reactor fuel. Currently these measurements are performed by in-core systems in what are extremely hostile environments and in most reactor accident scenarios it is likely that these systems would be damaged. Here we present a compact and portable radiation imaging system with the ability to image high-intensity fast-neutron and gamma-ray fields simultaneously. This system has been deployed to image radiation fields emitted during the operation of a TRIGA test reactor allowing a spatial visualization of the internal reactor conditions to be obtained. The imaged flux in each case is found to scale linearly with reactor power indicating that this method may be used for power-resolved reactor monitoring and for the assay of ongoing nuclear criticalities in damaged nuclear reactors. PMID:26450669

Design and manufacture of a D-shape coil-based toroid-type HTS DC reactor using 2nd generation HTS wire

NASA Astrophysics Data System (ADS)

Kim, Kwangmin; Go, Byeong-Soo; Sung, Hae-Jin; Park, Hea-chul; Kim, Seokho; Lee, Sangjin; Jin, Yoon-Su; Oh, Yunsang; Park, Minwon; Yu, In-Keun

2014-09-01

This paper describes the design specifications and performance of a real toroid-type high temperature superconducting (HTS) DC reactor. The HTS DC reactor was designed using 2G HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The target inductance of the HTS DC reactor was 400 mH. The expected operating temperature was under 20 K. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. Performances of the toroid-type HTS DC reactor were analyzed through experiments conducted under the steady-state and charge conditions. The fundamental design specifications and the data obtained from this research will be applied to the design of a commercial-type HTS DC reactor.

A comparison of the technological effectiveness of dairy wastewater treatment in anaerobic UASB reactor and anaerobic reactor with an innovative design.

PubMed

Jedrzejewska-Cicinska, M; Kozak, K; Krzemieniewski, M

2007-10-01

The present research was an investigation of the influence of an innovative design of reactor filled with polyethylene (PE) granulate on model dairy wastewater treatment efficiency under anaerobic conditions compared to that obtained in a typical UASB reactor. The experiment was conducted at laboratory scale. An innovative reactor was designed with the reaction chamber inclined 30 degrees in relation to the ground with upward waste flow and was filled with PE granular material. Raw model dairy wastewater was fed to two anaerobic reactors of different design at the organic loading rate of 4 kg COD m(-3)d(-1). Throughout the experiment, a higher removal efficiency of organic compounds was observed in the reactor with an innovative design and it was higher by 7.1% on average than in the UASB reactor. The total suspended solids was lower in the wastewater treated in the anaerobic reactor with the innovative design. Applying a PE granulated filling in the chamber of the innovative reactor contributed to an even distribution of sludge biomass in the reactor, reducing washout of anaerobic sludge biomass from the reaction chamber and giving a higher organic compounds removal efficiency.

Thorium Fuel Utilization Analysis on Small Long Life Reactor for Different Coolant Types

NASA Astrophysics Data System (ADS)

Permana, Sidik

2017-07-01

A small power reactor and long operation which can be deployed for less population and remote area has been proposed by the IAEA as a small and medium reactor (SMR) program. Beside uranium utilization, it can be used also thorium fuel resources for SMR as a part of optimalization of nuclear fuel as a “partner” fuel with uranium fuel. A small long-life reactor based on thorium fuel cycle for several reactor coolant types and several power output has been evaluated in the present study for 10 years period of reactor operation. Several key parameters are used to evaluate its effect to the reactor performances such as reactor criticality, excess reactivity, reactor burnup achievement and power density profile. Water-cooled types give higher criticality than liquid metal coolants. Liquid metal coolant for fast reactor system gives less criticality especially at beginning of cycle (BOC), which shows liquid metal coolant system obtains almost stable criticality condition. Liquid metal coolants are relatively less excess reactivity to maintain longer reactor operation than water coolants. In addition, liquid metal coolant gives higher achievable burnup than water coolant types as well as higher power density for liquid metal coolants.

Development of toroid-type HTS DC reactor series for HVDC system

NASA Astrophysics Data System (ADS)

Kim, Kwangmin; Go, Byeong-Soo; Park, Hea-chul; Kim, Sung-kyu; Kim, Seokho; Lee, Sangjin; Oh, Yunsang; Park, Minwon; Yu, In-Keun

2015-11-01

This paper describes design specifications and performance of a toroid-type high-temperature superconducting (HTS) DC reactor. The first phase operation targets of the HTS DC reactor were 400 mH and 400 A. The authors have developed a real HTS DC reactor system during the last three years. The HTS DC reactor was designed using 2G GdBCO HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. The total system has been successfully developed and tested in connection with LCC type HVDC system. Now, the authors are studying a 400 mH, kA class toroid-type HTS DC reactor for the next phase research. The 1500 A class DC reactor system was designed using layered 13 mm GdBCO 2G HTS wire. The expected operating temperature is under 30 K. These fundamental data obtained through both works will usefully be applied to design a real toroid-type HTS DC reactor for grid application.

Experiences in utilization of research reactors in Yugoslavia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Copic, M.; Gabrovsek, Z.; Pop-Jordanov, J.

1971-06-15

The nuclear institutes in Yugoslavia possess three research reactors. Since 1958, two heavy-water reactors have been in operation at the 'Boris Kidric' Institute, a zero-power reactor RB and a 6. 5-MW reactor RA. At the Jozef Stefan Institute, a 250-kW TRIGA Mark II reactor has been operating since 1966. All reactors are equipped with the necessary experimental facilities. The main activities based on these reactors are: (1) fundamental research in solid-state and nuclear physics; (2) R and D activities related to nuclear power program; and (3) radioisotope production. In fundamental physics, inelastic neutron scattering and diffraction phenomena are studied bymore » means of the neutron beam tubes and applied to investigations of the structures of solids and liquids. Valuable results are also obtained in n - γ reaction studies. Experiments connected with the fuel -element development program, owing to the characteristics of the existing reactors, are limited to determination of the fuel element parameters, to studies on the purity of uranium, and to a small number of capsule irradiations. All three reactors are also used for the verification of different methods applied in the analysis of power reactors, particularly concerning neutron flux distributions, the optimization of reactor core configurations and the shielding effects. An appreciable irradiation space in the reactors is reserved for isotope production. Fruitful international co-operation has been established in all these activities, on the basis of either bilateral or multilateral arrangements. The paper gives a critical analysis of the utilization of research reactors in a developing country such as Yugoslavia. The investments in and the operational costs of research reactors are compared with the benefits obtained in different areas of reactor application. The impact on the general scientific, technological and educational level in the country is also considered. In particular, an attempt is made ro envisage the role of research reactors in the promotion of nuclear power programs in relation to the size of the program, the competence of domestic industries and the degree of independence where fuel supply is concerned. (author)« less

Nuclear Reactor Physics

NASA Astrophysics Data System (ADS)

Stacey, Weston M.

2001-02-01

An authoritative textbook and up-to-date professional's guide to basic and advanced principles and practices Nuclear reactors now account for a significant portion of the electrical power generated worldwide. At the same time, the past few decades have seen an ever-increasing number of industrial, medical, military, and research applications for nuclear reactors. Nuclear reactor physics is the core discipline of nuclear engineering, and as the first comprehensive textbook and reference on basic and advanced nuclear reactor physics to appear in a quarter century, this book fills a large gap in the professional literature. Nuclear Reactor Physics is a textbook for students new to the subject, for others who need a basic understanding of how nuclear reactors work, as well as for those who are, or wish to become, specialists in nuclear reactor physics and reactor physics computations. It is also a valuable resource for engineers responsible for the operation of nuclear reactors. Dr. Weston Stacey begins with clear presentations of the basic physical principles, nuclear data, and computational methodology needed to understand both the static and dynamic behaviors of nuclear reactors. This is followed by in-depth discussions of advanced concepts, including extensive treatment of neutron transport computational methods. As an aid to comprehension and quick mastery of computational skills, he provides numerous examples illustrating step-by-step procedures for performing the calculations described and chapter-end problems. Nuclear Reactor Physics is a useful textbook and working reference. It is an excellent self-teaching guide for research scientists, engineers, and technicians involved in industrial, research, and military applications of nuclear reactors, as well as government regulators who wish to increase their understanding of nuclear reactors.

SELF-REGULATING BOILING-WATER NUCLEAR REACTORS

DOEpatents

Ransohoff, J.A.; Plawchan, J.D.

1960-08-16

A boiling-water reactor was designed which comprises a pressure vessel containing a mass of water, a reactor core submerged within the water, a reflector tank disposed within the reactor, the reflector tank being open at the top to the interior of the pressure vessel, and a surge tank connected to the reflector tank. In operation the reflector level changes as a function of the pressure witoin the reactor so that the reactivity of the reactor is automatically controlled.

REACTOR-FLASH BOILER-FLYWHEEL POWER PLANT

DOEpatents

Loeb, E.

1961-01-17

A power generator in the form of a flywheel with four reactors positioned about its rim is described. The reactors are so positioned that steam, produced in the reactor, exists tangentially to the flywheel, giving it a rotation. The reactors are incompletely moderated without water. The water enters the flywheel at its axis, under sufficient pressure to force it through the reactors, where it is converted to steam. The fuel consists of parallel twisted ribbons assembled to approximate a cylinder.

System and method for air temperature control in an oxygen transport membrane based reactor

DOEpatents

Kelly, Sean M

2016-09-27

A system and method for air temperature control in an oxygen transport membrane based reactor is provided. The system and method involves introducing a specific quantity of cooling air or trim air in between stages in a multistage oxygen transport membrane based reactor or furnace to maintain generally consistent surface temperatures of the oxygen transport membrane elements and associated reactors. The associated reactors may include reforming reactors, boilers or process gas heaters.

System and method for temperature control in an oxygen transport membrane based reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelly, Sean M.

A system and method for temperature control in an oxygen transport membrane based reactor is provided. The system and method involves introducing a specific quantity of cooling air or trim air in between stages in a multistage oxygen transport membrane based reactor or furnace to maintain generally consistent surface temperatures of the oxygen transport membrane elements and associated reactors. The associated reactors may include reforming reactors, boilers or process gas heaters.

Navy Nuclear-Powered Surface Ships: Background, Issues, and Options for Congress

DTIC Science & Technology

2010-09-29

to design a smaller scale version of a naval pressurized water reactor , or to design a new reactor type potentially using a thorium liquid salt...integrated nuclear power system capable of use on destroyer- sized vessels either using a pressurized water reactor or a thorium liquid salt reactor ...nuclear reactors for Navy surface ships. The text of Section 246 is as follows: SEC. 246. STUDY ON THORIUM -LIQUID FUELED REACTORS FOR NAVAL FORCES

Laboratory instrumentation modernization at the WPI Nuclear Reactor Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1995-01-01

With partial funding from the Department of Energy (DOE) University Reactor Instrumentation Program several laboratory instruments utilized by students and researchers at the WPI Nuclear Reactor Facility have been upgraded or replaced. Designed and built by General Electric in 1959, the open pool nuclear training reactor at WPI was one of the first such facilities in the nation located on a university campus. Devoted to undergraduate use, the reactor and its related facilities have been since used to train two generations of nuclear engineers and scientists for the nuclear industry. The low power output of the reactor and an ergonomicmore » facility design make it an ideal tool for undergraduate nuclear engineering education and other training. The reactor, its control system, and the associate laboratory equipment are all located in the same room. Over the years, several important milestones have taken place at the WPI reactor. In 1969, the reactor power level was upgraded from 1 kW to 10 kW. The reactor`s Nuclear Regulatory Commission operating license was renewed for 20 years in 1983. In 1988, under DOE Grant No. DE-FG07-86ER75271, the reactor was converted to low-enriched uranium fuel. In 1992, again with partial funding from DOE (Grant No. DE-FG02-90ER12982), the original control console was replaced.« less

Modification of UASB reactor by using CFD simulations for enhanced treatment of municipal sewage.

PubMed

Das, Suprotim; Sarkar, Supriya; Chaudhari, Sanjeev

2018-02-01

Up-flow anaerobic sludge blanket (UASB) has been in use since last few decades for the treatment of organic wastewaters. However, the performance of UASB reactor is quite low for treatment of low strength wastewaters (LSWs) due to less biogas production leading to poor mixing. In the present research work, a modification was done in the design of UASB to improve mixing of reactor liquid which is important to enhance the reactor performance. The modified UASB (MUASB) reactor was designed by providing a slanted baffle along the height of the reactor having an angle of 5.7° with the vertical wall. A two-dimensional computational fluid dynamics (CFD) simulation of three phase gas-liquid-solid flow in MUASB reactor was performed and compared with conventional UASB reactor. The CFD study indicated better mixing in terms of vorticity magnitude in MUASB reactor as compared to conventional UASB, which was reflected in the reactor performance. The performance of MUASB was compared with conventional UASB reactor for the onsite treatment of domestic sewage as LSW. Around 16% higher total chemical oxygen demand removal efficiency was observed in MUASB reactor as compared to conventional UASB during this study. Therefore, this MUASB model demonstrates a qualitative relationship between mixing and performance during the treatment of LSW. From the study, it seems that MUASB holds promise for field applications.

10 CFR 50.60 - Acceptance criteria for fracture prevention measures for lightwater nuclear power reactors for...

Code of Federal Regulations, 2010 CFR

2010-01-01

... lightwater nuclear power reactors for normal operation. 50.60 Section 50.60 Energy NUCLEAR REGULATORY... lightwater nuclear power reactors for normal operation. (a) Except as provided in paragraph (b) of this section, all light-water nuclear power reactors, other than reactor facilities for which the...

10 CFR 73.60 - Additional requirements for physical protection at nonpower reactors.

Code of Federal Regulations, 2010 CFR

2010-01-01

... nonpower reactors. 73.60 Section 73.60 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PHYSICAL PROTECTION... requirements for physical protection at nonpower reactors. Each nonpower reactor licensee who, pursuant to the... nonpower reactors licensed to operate at or above a power level of 2 megawatts thermal. [38 FR 35430, Dec...

10 CFR 50.60 - Acceptance criteria for fracture prevention measures for lightwater nuclear power reactors for...

Code of Federal Regulations, 2011 CFR

2011-01-01

... lightwater nuclear power reactors for normal operation. 50.60 Section 50.60 Energy NUCLEAR REGULATORY... lightwater nuclear power reactors for normal operation. (a) Except as provided in paragraph (b) of this section, all light-water nuclear power reactors, other than reactor facilities for which the...

10 CFR 73.60 - Additional requirements for physical protection at nonpower reactors.

Code of Federal Regulations, 2011 CFR

2011-01-01

... nonpower reactors. 73.60 Section 73.60 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PHYSICAL PROTECTION... requirements for physical protection at nonpower reactors. Each nonpower reactor licensee who, pursuant to the... nonpower reactors licensed to operate at or above a power level of 2 megawatts thermal. [38 FR 35430, Dec...

78 FR 26811 - Dow Chemical Company, Dow TRIGA Research Reactor; License Renewal for the Dow Chemical TRIGA...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-08

... Research Reactor; License Renewal for the Dow Chemical TRIGA Research Reactor; Supplemental Information and... 20, 2012 (77 FR 42771), ``License Renewal for the Dow Chemical TRIGA Research Reactor,'' to inform... Chemical Company which would authorize continued operation of the Dow TRIGA Research Reactor. The notice...

10 CFR 140.12 - Amount of financial protection required for other reactors.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Amount of financial protection required for other reactors... reactors. (a) Each licensee is required to have and maintain financial protection for each nuclear reactor... of financial protection required for any nuclear reactor under this section be less than $4,500,000...

10 CFR 140.12 - Amount of financial protection required for other reactors.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Amount of financial protection required for other reactors... reactors. (a) Each licensee is required to have and maintain financial protection for each nuclear reactor... of financial protection required for any nuclear reactor under this section be less than $4,500,000...

PBF Reactor Building (PER620). Camera faces north into highbay/reactor pit ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PBF Reactor Building (PER-620). Camera faces north into high-bay/reactor pit area. Inside from for reactor enclosure is in place. Photographer: John Capek. Date: March 15, 1967. INEEL negative no. 67-1769 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

Reactor safety method

DOEpatents

Vachon, Lawrence J.

1980-03-11

This invention relates to safety means for preventing a gas cooled nuclear reactor from attaining criticality prior to start up in the event the reactor core is immersed in hydrogenous liquid. This is accomplished by coating the inside surface of the reactor coolant channels with a neutral absorbing material that will vaporize at the reactor's operating temperature.

155. ARAIII Reactor building (ARA608) Details of reactor pit showing ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

155. ARA-III Reactor building (ARA-608) Details of reactor pit showing tray supports and fuel element storage rack. Aerojet-general 880-area/GCRE-608-MS-2. Date: November 1958. Ineel index code no. 063-0608-40-013-102625. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

World Energy Data System (WENDS). Volume XI. Nuclear fission program summaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1979-06-01

Brief management and technical summaries of nuclear fission power programs are presented for nineteen countries. The programs include the following: fuel supply, resource recovery, enrichment, fuel fabrication, light water reactors, heavy water reactors, gas cooled reactors, breeder reactors, research and test reactors, spent fuel processing, waste management, and safety and environment. (JWR)

Breeder Reactors, Understanding the Atom Series.

ERIC Educational Resources Information Center

Mitchell, Walter, III; Turner, Stanley E.

The theory of breeder reactors in relationship to a discussion of fission is presented. Different kinds of reactors are characterized by the cooling fluids used, such as liquid metal, gas, and molten salt. The historical development of breeder reactors over the past twenty-five years includes specific examples of reactors. The location and a brief…

10 CFR 140.12 - Amount of financial protection required for other reactors.

Code of Federal Regulations, 2013 CFR

2013-01-01

... reactors. (a) Each licensee is required to have and maintain financial protection for each nuclear reactor... of financial protection required for any nuclear reactor under this section be less than $4,500,000... chapter to operate two or more nuclear reactors at the same location, the total financial protection...

10 CFR 2.103 - Action on applications for byproduct, source, special nuclear material, facility and operator...

Code of Federal Regulations, 2011 CFR

2011-01-01

..., Office of Nuclear Reactor Regulation, Director, Office of New Reactors, Director, Office of Federal and..., Office of Nuclear Reactor Regulation, Director, Office of New Reactors, Director, Office of Nuclear... of this chapter, see § 2.106(d). (b) If the Director, Office of Nuclear Reactor Regulation, Director...

10 CFR 140.12 - Amount of financial protection required for other reactors.

Code of Federal Regulations, 2014 CFR

2014-01-01

... reactors. (a) Each licensee is required to have and maintain financial protection for each nuclear reactor... of financial protection required for any nuclear reactor under this section be less than $4,500,000... chapter to operate two or more nuclear reactors at the same location, the total financial protection...

10 CFR 140.12 - Amount of financial protection required for other reactors.

Code of Federal Regulations, 2012 CFR

2012-01-01

... reactors. (a) Each licensee is required to have and maintain financial protection for each nuclear reactor... of financial protection required for any nuclear reactor under this section be less than $4,500,000... chapter to operate two or more nuclear reactors at the same location, the total financial protection...

10 CFR 2.103 - Action on applications for byproduct, source, special nuclear material, facility and operator...

Code of Federal Regulations, 2012 CFR

2012-01-01

..., Office of Nuclear Reactor Regulation, Director, Office of New Reactors, Director, Office of Federal and..., Office of Nuclear Reactor Regulation, Director, Office of New Reactors, Director, Office of Nuclear... of this chapter, see § 2.106(d). (b) If the Director, Office of Nuclear Reactor Regulation, Director...

Computer model of catalytic combustion/Stirling engine heater head

NASA Technical Reports Server (NTRS)

Chu, E. K.; Chang, R. L.; Tong, H.

1981-01-01

The basic Acurex HET code was modified to analyze specific problems for Stirling engine heater head applications. Specifically, the code can model: an adiabatic catalytic monolith reactor, an externally cooled catalytic cylindrical reactor/flat plate reactor, a coannular tube radiatively cooled reactor, and a monolithic reactor radiating to upstream and downstream heat exchangers.

Analysis of the Gas Core Actinide Transmutation Reactor (GCATR)

NASA Technical Reports Server (NTRS)

Clement, J. D.; Rust, J. H.

1977-01-01

Design power plant studies were carried out for two applications of the plasma core reactor: (1) As a breeder reactor, (2) As a reactor able to transmute actinides effectively. In addition to the above applications the reactor produced electrical power with a high efficiency. A reactor subsystem was designed for each of the two applications. For the breeder reactor, neutronics calculations were carried out for a U-233 plasma core with a molten salt breeding blanket. A reactor was designed with a low critical mass (less than a few hundred kilograms U-233) and a breeding ratio of 1.01. The plasma core actinide transmutation reactor was designed to transmute the nuclear waste from conventional LWR's. The spent fuel is reprocessed during which 100% of Np, Am, Cm, and higher actinides are separated from the other components. These actinides are then manufactured as oxides into zirconium clad fuel rods and charged as fuel assemblies in the reflector region of the plasma core actinide transmutation reactor. In the equilibrium cycle, about 7% of the actinides are directly fissioned away, while about 31% are removed by reprocessing.

MONTE CARLO SIMULATIONS OF PERIODIC PULSED REACTOR WITH MOVING GEOMETRY PARTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Yan; Gohar, Yousry

2015-11-01

In a periodic pulsed reactor, the reactor state varies periodically from slightly subcritical to slightly prompt supercritical for producing periodic power pulses. Such periodic state change is accomplished by a periodic movement of specific reactor parts, such as control rods or reflector sections. The analysis of such reactor is difficult to perform with the current reactor physics computer programs. Based on past experience, the utilization of the point kinetics approximations gives considerable errors in predicting the magnitude and the shape of the power pulse if the reactor has significantly different neutron life times in different zones. To accurately simulate themore » dynamics of this type of reactor, a Monte Carlo procedure using the transfer function TRCL/TR of the MCNP/MCNPX computer programs is utilized to model the movable reactor parts. In this paper, two algorithms simulating the geometry part movements during a neutron history tracking have been developed. Several test cases have been developed to evaluate these procedures. The numerical test cases have shown that the developed algorithms can be utilized to simulate the reactor dynamics with movable geometry parts.« less

Pressurized fluidized bed reactor

DOEpatents

Isaksson, J.

1996-03-19

A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine. 1 fig.

Pressurized fluidized bed reactor

DOEpatents

Isaksson, Juhani

1996-01-01

A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine.

Reactor vibration reduction based on giant magnetostrictive materials

NASA Astrophysics Data System (ADS)

Rongge, Yan; Weiying, Liu; Yuechao, Wu; Menghua, Duan; Xiaohong, Zhang; Lihua, Zhu; Ling, Weng; Ying, Sun

2017-05-01

The vibration of reactors not only produces noise pollution, but also affects the safe operation of reactors. Giant magnetostrictive materials can generate huge expansion and shrinkage deformation in a magnetic field. With the principle of mutual offset between the giant magnetostrictive force produced by the giant magnetostrictive material and the original vibration force of the reactor, the vibration of the reactor can be reduced. In this paper, magnetization and magnetostriction characteristics in silicon steel and the giant magnetostrictive material are measured, respectively. According to the presented magneto-mechanical coupling model including the electromagnetic force and the magnetostrictive force, reactor vibration is calculated. By comparing the vibration of the reactor with different inserted materials in the air gaps between the reactor cores, the vibration reduction effectiveness of the giant magnetostrictive material is validated.

Preliminary analysis of loss-of-coolant accident in Fukushima nuclear accident

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su'ud, Zaki; Anshari, Rio

Loss-of-Coolant Accident (LOCA) in Boiling Water Reactor (BWR) especially on Fukushima Nuclear Accident will be discussed in this paper. The Tohoku earthquake triggered the shutdown of nuclear power reactors at Fukushima Nuclear Power station. Though shutdown process has been completely performed, cooling process, at much smaller level than in normal operation, is needed to remove decay heat from the reactor core until the reactor reach cold-shutdown condition. If LOCA happen at this condition, it will cause the increase of reactor fuel and other core temperatures and can lead to reactor core meltdown and exposure of radioactive material to the environmentmore » such as in the Fukushima Dai Ichi nuclear accident case. In this study numerical simulation has been performed to calculate pressure composition, water level and temperature distribution on reactor during this accident. There are two coolant regulating system that operational on reactor unit 1 at this accident, Isolation Condensers (IC) system and Safety Relief Valves (SRV) system. Average mass flow of steam to the IC system in this event is 10 kg/s and could keep reactor core from uncovered about 3,2 hours and fully uncovered in 4,7 hours later. There are two coolant regulating system at operational on reactor unit 2, Reactor Core Isolation Condenser (RCIC) System and Safety Relief Valves (SRV). Average mass flow of coolant that correspond this event is 20 kg/s and could keep reactor core from uncovered about 73 hours and fully uncovered in 75 hours later. There are three coolant regulating system at operational on reactor unit 3, Reactor Core Isolation Condenser (RCIC) system, High Pressure Coolant Injection (HPCI) system and Safety Relief Valves (SRV). Average mass flow of water that correspond this event is 15 kg/s and could keep reactor core from uncovered about 37 hours and fully uncovered in 40 hours later.« less

Preliminary analysis of loss-of-coolant accident in Fukushima nuclear accident

NASA Astrophysics Data System (ADS)

Su'ud, Zaki; Anshari, Rio

2012-06-01

Loss-of-Coolant Accident (LOCA) in Boiling Water Reactor (BWR) especially on Fukushima Nuclear Accident will be discussed in this paper. The Tohoku earthquake triggered the shutdown of nuclear power reactors at Fukushima Nuclear Power station. Though shutdown process has been completely performed, cooling process, at much smaller level than in normal operation, is needed to remove decay heat from the reactor core until the reactor reach cold-shutdown condition. If LOCA happen at this condition, it will cause the increase of reactor fuel and other core temperatures and can lead to reactor core meltdown and exposure of radioactive material to the environment such as in the Fukushima Dai Ichi nuclear accident case. In this study numerical simulation has been performed to calculate pressure composition, water level and temperature distribution on reactor during this accident. There are two coolant regulating system that operational on reactor unit 1 at this accident, Isolation Condensers (IC) system and Safety Relief Valves (SRV) system. Average mass flow of steam to the IC system in this event is 10 kg/s and could keep reactor core from uncovered about 3,2 hours and fully uncovered in 4,7 hours later. There are two coolant regulating system at operational on reactor unit 2, Reactor Core Isolation Condenser (RCIC) System and Safety Relief Valves (SRV). Average mass flow of coolant that correspond this event is 20 kg/s and could keep reactor core from uncovered about 73 hours and fully uncovered in 75 hours later. There are three coolant regulating system at operational on reactor unit 3, Reactor Core Isolation Condenser (RCIC) system, High Pressure Coolant Injection (HPCI) system and Safety Relief Valves (SRV). Average mass flow of water that correspond this event is 15 kg/s and could keep reactor core from uncovered about 37 hours and fully uncovered in 40 hours later.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wichman, K.; Tsao, J.; Mayfield, M.

The regulatory application of leak before break (LBB) for operating and advanced reactors in the U.S. is described. The U.S. Nuclear Regulatory Commission (NRC) has approved the application of LBB for six piping systems in operating reactors: reactor coolant system primary loop piping, pressurizer surge, safety injection accumulator, residual heat removal, safety injection, and reactor coolant loop bypass. The LBB concept has also been applied in the design of advanced light water reactors. LBB applications, and regulatory considerations, for pressurized water reactors and advanced light water reactors are summarized in this paper. Technology development for LBB performed by the NRCmore » and the International Piping Integrity Research Group is also briefly summarized.« less

Solution of heat removal from nuclear reactors by natural convection

NASA Astrophysics Data System (ADS)

Zitek, Pavel; Valenta, Vaclav

2014-03-01

This paper summarizes the basis for the solution of heat removal by natural convection from both conventional nuclear reactors and reactors with fuel flowing coolant (such as reactors with molten fluoride salts MSR).The possibility of intensification of heat removal through gas lift is focused on. It might be used in an MSR (Molten Salt Reactor) for cleaning the salt mixture of degassed fission products and therefore eliminating problems with iodine pitting. Heat removal by natural convection and its intensification increases significantly the safety of nuclear reactors. Simultaneously the heat removal also solves problems with lifetime of pumps in the primary circuit of high-temperature reactors.

Imaging Fukushima Daiichi reactors with muons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyadera, Haruo; Borozdin, Konstantin N.; Greene, Steve J.

2013-05-15

A study of imaging the Fukushima Daiichi reactors with cosmic-ray muons to assess the damage to the reactors is presented. Muon scattering imaging has high sensitivity for detecting uranium fuel and debris even through thick concrete walls and a reactor pressure vessel. Technical demonstrations using a reactor mockup, detector radiation test at Fukushima Daiichi, and simulation studies have been carried out. These studies establish feasibility for the reactor imaging. A few months of measurement will reveal the spatial distribution of the reactor fuel. The muon scattering technique would be the best and probably the only way for Fukushima Daiichi tomore » make this determination in the near future.« less

Imaging Fukushima Daiichi reactors with muons

NASA Astrophysics Data System (ADS)

Miyadera, Haruo; Borozdin, Konstantin N.; Greene, Steve J.; Lukić, Zarija; Masuda, Koji; Milner, Edward C.; Morris, Christopher L.; Perry, John O.

2013-05-01

A study of imaging the Fukushima Daiichi reactors with cosmic-ray muons to assess the damage to the reactors is presented. Muon scattering imaging has high sensitivity for detecting uranium fuel and debris even through thick concrete walls and a reactor pressure vessel. Technical demonstrations using a reactor mockup, detector radiation test at Fukushima Daiichi, and simulation studies have been carried out. These studies establish feasibility for the reactor imaging. A few months of measurement will reveal the spatial distribution of the reactor fuel. The muon scattering technique would be the best and probably the only way for Fukushima Daiichi to make this determination in the near future.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fitzpatrick, F.C.; Gray, D.D.; Hyndman, J.R.

The thermal, ecological, and social impacts of a 40-reactor NEC are compared to impacts from four 10-reactor NECs and ten 4-reactor power plants. The comparison was made for surrogate sites in western Tennessee. The surrogate site for the 40-reactor NEC is located on Kentucky Lake. A layout is postulated for ten clusters of four reactors each with 2.5-mile spacing between clusters. The plants use natural-draft cooling towers. A transmission system is proposed for delivering the power (48,000 MW) to five load centers. Comparable transmission systems are proposed for the 10-reactor NECs and the 4-reactor dispersed sites delivering power to themore » same load centers. (auth)« less

Digital computer study of nuclear reactor thermal transients during startup of 60-kWe Brayton power conversion system

NASA Technical Reports Server (NTRS)

Jefferies, K. S.; Tew, R. C.

1974-01-01

A digital computer study was made of reactor thermal transients during startup of the Brayton power conversion loop of a 60-kWe reactor Brayton power system. A startup procedure requiring the least Brayton system complication was tried first; this procedure caused violations of design limits on key reactor variables. Several modifications of this procedure were then found which caused no design limit violations. These modifications involved: (1) using a slower rate of increase in gas flow; (2) increasing the initial reactor power level to make the reactor respond faster; and (3) appropriate reactor control drum manipulation during the startup transient.

Hybrid adsorptive membrane reactor

NASA Technical Reports Server (NTRS)

Tsotsis, Theodore T. (Inventor); Sahimi, Muhammad (Inventor); Fayyaz-Najafi, Babak (Inventor); Harale, Aadesh (Inventor); Park, Byoung-Gi (Inventor); Liu, Paul K. T. (Inventor)

2011-01-01

A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

Hybrid adsorptive membrane reactor

DOEpatents

Tsotsis, Theodore T [Huntington Beach, CA; Sahimi, Muhammad [Altadena, CA; Fayyaz-Najafi, Babak [Richmond, CA; Harale, Aadesh [Los Angeles, CA; Park, Byoung-Gi [Yeosu, KR; Liu, Paul K. T. [Lafayette Hill, PA

2011-03-01

A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

Neutron Fluence And DPA Rate Analysis In Pebble-Bed HTR Reactor Vessel Using MCNP

NASA Astrophysics Data System (ADS)

Hamzah, Amir; Suwoto; Rohanda, Anis; Adrial, Hery; Bakhri, Syaiful; Sunaryo, Geni Rina

2018-02-01

In the Pebble-bed HTR reactor, the distance between the core and the reactor vessel is very close and the media inside are carbon and He gas. Neutron moderation capability of graphite material is theoretically lower than that of water-moderated reactors. Thus, it is estimated much more the fast neutrons will reach the reactor vessel. The fast neutron collisions with the atoms in the reactor vessel will result in radiation damage and could be reducing the vessel life. The purpose of this study was to obtain the magnitude of neutron fluence in the Pebble-bed HTR reactor vessel. Neutron fluence calculations in the pebble-bed HTR reactor vessel were performed using the MCNP computer program. By determining the tally position, it can be calculated flux, spectrum and neutron fluence in the position of Pebble-bed HTR reactor vessel. The calculations results of total neutron flux and fast neutron flux in the reactor vessel of 1.82x108 n/cm2/s and 1.79x108 n/cm2/s respectively. The fast neutron fluence in the reactor vessel is 3.4x1017 n/cm2 for 60 years reactor operation. Radiation damage in stainless steel material caused by high-energy neutrons (> 1.0 MeV) will occur when it has reached the neutron flux level of 1.0x1024 n/cm2. The neutron fluence results show that there is no radiation damage in the Pebble-bed HTR reactor vessel, so it is predicted that it will be safe to operate at least for 60 years.

Reactor performances and microbial communities of biogas reactors: effects of inoculum sources.

PubMed

Han, Sheng; Liu, Yafeng; Zhang, Shicheng; Luo, Gang

2016-01-01

Anaerobic digestion is a very complex process that is mediated by various microorganisms, and the understanding of the microbial community assembly and its corresponding function is critical in order to better control the anaerobic process. The present study investigated the effect of different inocula on the microbial community assembly in biogas reactors treating cellulose with various inocula, and three parallel biogas reactors with the same inoculum were also operated in order to reveal the reproducibility of both microbial communities and functions of the biogas reactors. The results showed that the biogas production, volatile fatty acid (VFA) concentrations, and pH were different for the biogas reactors with different inocula, and different steady-state microbial community patterns were also obtained in different biogas reactors as reflected by Bray-Curtis similarity matrices and taxonomic classification. It indicated that inoculum played an important role in shaping the microbial communities of biogas reactor in the present study, and the microbial community assembly in biogas reactor did not follow the niche-based ecology theory. Furthermore, it was found that the microbial communities and reactor performances of parallel biogas reactors with the same inoculum were different, which could be explained by the neutral-based ecology theory and stochastic factors should played important roles in the microbial community assembly in the biogas reactors. The Bray-Curtis similarity matrices analysis suggested that inoculum affected more on the microbial community assembly compared to stochastic factors, since the samples with different inocula had lower similarity (10-20 %) compared to the samples from the parallel biogas reactors (30 %).

A novel plant protection strategy for transient reactors

NASA Astrophysics Data System (ADS)

Bhattacharyya, Samit K.; Lipinski, Walter C.; Hanan, Nelson A.

The present plant protection system (PPS) has been defined for use in the TREAT-upgrade (TU) reactor for controlled transient operation of reactor-fuel behavior testing under simulated reactor-accident conditions. A PPS with energy-dependent trip set points lowered worst-case clad temperatures by as much as 180 K, relative to the use of conventional fixed-level trip set points. The multilayered multilevel protection strategy represents the state-of-the-art in terrestrial transient reactor protection systems, and should be applicable to multi-MW space reactors.

Nuclear Energy Policy

DTIC Science & Technology

2009-12-10

Small Modular Reactors Rising cost estimates for large conventional nuclear power plants—widely projected to be $6 billion or more—have contributed to growing interest in proposals for smaller, modular reactors. Ranging from about 40 to 350 megawatts of electrical capacity, such reactors would be only a fraction of the size of current commercial reactors. Several modular reactors would be installed together to make up a power block with a single control room, under most concepts. Modular reactor concepts would use a variety of technologies,

Research and proposal on selective catalytic reduction reactor optimization for industrial boiler.

PubMed

Yang, Yiming; Li, Jian; He, Hong

2017-08-24

The advanced computational fluid dynamics (CFD) software STAR-CCM+ was used to simulate a denitrification (De-NOx) project for a boiler in this paper, and the simulation result was verified based on a physical model. Two selective catalytic reduction (SCR) reactors were developed: reactor 1 was optimized and reactor 2 was developed based on reactor 1. Various indicators, including gas flow field, ammonia concentration distribution, temperature distribution, gas incident angle, and system pressure drop were analyzed. The analysis indicated that reactor 2 was of outstanding performance and could simplify developing greatly. Ammonia injection grid (AIG), the core component of the reactor, was studied; three AIGs were developed and their performances were compared and analyzed. The result indicated that AIG 3 was of the best performance. The technical indicators were proposed for SCR reactor based on the study. Flow filed distribution, gas incident angle, and temperature distribution are subjected to SCR reactor shape to a great extent, and reactor 2 proposed in this paper was of outstanding performance; ammonia concentration distribution is subjected to ammonia injection grid (AIG) shape, and AIG 3 could meet the technical indicator of ammonia concentration without mounting ammonia mixer. The developments above on the reactor and the AIG are both of great application value and social efficiency.

REACTOR PHYSICS MODELING OF SPENT RESEARCH REACTOR FUEL FOR TECHNICAL NUCLEAR FORENSICS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nichols, T.; Beals, D.; Sternat, M.

2011-07-18

Technical nuclear forensics (TNF) refers to the collection, analysis and evaluation of pre- and post-detonation radiological or nuclear materials, devices, and/or debris. TNF is an integral component, complementing traditional forensics and investigative work, to help enable the attribution of discovered radiological or nuclear material. Research is needed to improve the capabilities of TNF. One research area of interest is determining the isotopic signatures of research reactors. Research reactors are a potential source of both radiological and nuclear material. Research reactors are often the least safeguarded type of reactor; they vary greatly in size, fuel type, enrichment, power, and burn-up. Manymore » research reactors are fueled with highly-enriched uranium (HEU), up to {approx}93% {sup 235}U, which could potentially be used as weapons material. All of them have significant amounts of radiological material with which a radioactive dispersal device (RDD) could be built. Therefore, the ability to attribute if material originated from or was produced in a specific research reactor is an important tool in providing for the security of the United States. Currently there are approximately 237 operating research reactors worldwide, another 12 are in temporary shutdown and 224 research reactors are reported as shut down. Little is currently known about the isotopic signatures of spent research reactor fuel. An effort is underway at Savannah River National Laboratory (SRNL) to analyze spent research reactor fuel to determine these signatures. Computer models, using reactor physics codes, are being compared to the measured analytes in the spent fuel. This allows for improving the reactor physics codes in modeling research reactors for the purpose of nuclear forensics. Currently the Oak Ridge Research reactor (ORR) is being modeled and fuel samples are being analyzed for comparison. Samples of an ORR spent fuel assembly were taken by SRNL for analytical and radiochemical analysis. The fuel assembly was modeled using MONTEBURNS(MCNP5/ ORIGEN2.2) and MCNPX/CINDER90. The results from the models have been compared to each other and to the measured data.« less

10 CFR Appendix A to Part 110 - Illustrative List of Nuclear Reactor Equipment Under NRC Export Licensing Authority

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Illustrative List of Nuclear Reactor Equipment Under NRC... List of Nuclear Reactor Equipment Under NRC Export Licensing Authority Note—A nuclear reactor basically includes the items within or attached directly to the reactor vessel, the equipment which controls the...

78 FR 20959 - Advisory Committee on Reactor Safeguards (ACRS); Meeting of the ACRS Subcommittee on Advanced...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-08

... NUCLEAR REGULATORY COMMISSION Advisory Committee on Reactor Safeguards (ACRS); Meeting of the ACRS Subcommittee on Advanced Boiling Water Reactor The ACRS Subcommittee on Advanced Boiling Water Reactor (ABWR... Committee on Reactor Safeguards. [FR Doc. 2013-08131 Filed 4-5-13; 8:45 am] BILLING CODE 7590-01-P ...

10 CFR Appendix A to Part 110 - Illustrative List of Nuclear Reactor Equipment Under NRC Export Licensing Authority

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Illustrative List of Nuclear Reactor Equipment Under NRC... List of Nuclear Reactor Equipment Under NRC Export Licensing Authority Note—A nuclear reactor basically includes the items within or attached directly to the reactor vessel, the equipment which controls the...

10 CFR 50.46 - Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors.

Code of Federal Regulations, 2011 CFR

2011-01-01

... light-water nuclear power reactors. 50.46 Section 50.46 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... reactors. (a)(1)(i) Each boiling or pressurized light-water nuclear power reactor fueled with uranium oxide... behavior of the reactor system during a loss-of-coolant accident. Comparisons to applicable experimental...

NEUTRONIC REACTOR

DOEpatents

Fermi, E.; Zinn, W.H.; Anderson, H.L.

1958-09-16

Means are presenied for increasing the reproduction ratio of a gaphite- moderated neutronic reactor by diminishing the neutron loss due to absorption or capture by gaseous impurities within the reactor. This means comprised of a fluid-tight casing or envelope completely enclosing the reactor and provided with a valve through which the casing, and thereby the reactor, may be evacuated of atmospheric air.

76 FR 70331 - List of Approved Spent Fuel Storage Casks: MAGNASTOR ® System, Revision 2

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-14

... various boron-10 areal densities for use with Pressurized Water Reactor and Boiling Water Reactor baskets... add various boron-10 areal densities for use with Pressurized Water Reactor and Boiling Water Reactor....1.1 to add various boron-10 areal densities for use with Pressurized Water Reactor and Boiling Water...

10 CFR 50.46 - Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors.

Code of Federal Regulations, 2014 CFR

2014-01-01

... light-water nuclear power reactors. 50.46 Section 50.46 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... reactors. (a)(1)(i) Each boiling or pressurized light-water nuclear power reactor fueled with uranium oxide... evaluation model. This section does not apply to a nuclear power reactor facility for which the...

10 CFR Appendix A to Part 110 - Illustrative List of Nuclear Reactor Equipment Under NRC Export Licensing Authority

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Illustrative List of Nuclear Reactor Equipment Under NRC... List of Nuclear Reactor Equipment Under NRC Export Licensing Authority Note: A nuclear reactor... core of a nuclear reactor and capable of withstanding the operating pressure of the primary coolant. (2...

10 CFR 50.46 - Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors.

Code of Federal Regulations, 2013 CFR

2013-01-01

... light-water nuclear power reactors. 50.46 Section 50.46 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... reactors. (a)(1)(i) Each boiling or pressurized light-water nuclear power reactor fueled with uranium oxide... evaluation model. This section does not apply to a nuclear power reactor facility for which the...

10 CFR 50.46 - Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors.

Code of Federal Regulations, 2012 CFR

2012-01-01

... light-water nuclear power reactors. 50.46 Section 50.46 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... reactors. (a)(1)(i) Each boiling or pressurized light-water nuclear power reactor fueled with uranium oxide... evaluation model. This section does not apply to a nuclear power reactor facility for which the...

NEUTRONIC REACTOR

DOEpatents

Wigner, E.P.

1958-04-22

A nuclear reactor for isotope production is described. This reactor is designed to provide a maximum thermal neutron flux in a region adjacent to the periphery of the reactor rather than in the center of the reactor. The core of the reactor is generally centrally located with respect tn a surrounding first reflector, constructed of beryllium. The beryllium reflector is surrounded by a second reflector, constructed of graphite, which, in tune, is surrounded by a conventional thermal shield. Water is circulated through the core and the reflector and functions both as a moderator and a coolant. In order to produce a greatsr maximum thermal neutron flux adjacent to the periphery of the reactor rather than in the core, the reactor is designed so tbat the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the materials in the reflector is approximately twice the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the material of the core of the reactor.

Next generation fuel irradiation capability in the High Flux Reactor Petten

NASA Astrophysics Data System (ADS)

Fütterer, Michael A.; D'Agata, Elio; Laurie, Mathias; Marmier, Alain; Scaffidi-Argentina, Francesco; Raison, Philippe; Bakker, Klaas; de Groot, Sander; Klaassen, Frodo

2009-07-01

This paper describes selected equipment and expertise on fuel irradiation testing at the High Flux Reactor (HFR) in Petten, The Netherlands. The reactor went critical in 1961 and holds an operating license up to at least 2015. While HFR has initially focused on Light Water Reactor fuel and materials, it also played a decisive role since the 1970s in the German High Temperature Reactor (HTR) development program. A variety of tests related to fast reactor development in Europe were carried out for next generation fuel and materials, in particular for Very High Temperature Reactor (V/HTR) fuel, fuel for closed fuel cycles (U-Pu and Th-U fuel cycle) and transmutation, as well as for other innovative fuel types. The HFR constitutes a significant European infrastructure tool for the development of next generation reactors. Experimental facilities addressed include V/HTR fuel tests, a coated particle irradiation rig, and tests on fast reactor, transmutation and thorium fuel. The rationales for these tests are given, results are provided and further work is outlined.

Using thermal balance model to determine optimal reactor volume and insulation material needed in a laboratory-scale composting reactor.

PubMed

Wang, Yongjiang; Pang, Li; Liu, Xinyu; Wang, Yuansheng; Zhou, Kexun; Luo, Fei

2016-04-01

A comprehensive model of thermal balance and degradation kinetics was developed to determine the optimal reactor volume and insulation material. Biological heat production and five channels of heat loss were considered in the thermal balance model for a representative reactor. Degradation kinetics was developed to make the model applicable to different types of substrates. Simulation of the model showed that the internal energy accumulation of compost was the significant heat loss channel, following by heat loss through reactor wall, and latent heat of water evaporation. Lower proportion of heat loss occurred through the reactor wall when the reactor volume was larger. Insulating materials with low densities and low conductive coefficients were more desirable for building small reactor systems. Model developed could be used to determine the optimal reactor volume and insulation material needed before the fabrication of a lab-scale composting system. Copyright © 2016 Elsevier Ltd. All rights reserved.

Utilization of Stop-flow Micro-tubing Reactors for the Development of Organic Transformations.

PubMed

Toh, Ren Wei; Li, Jie Sheng; Wu, Jie

2018-01-04

A new reaction screening technology for organic synthesis was recently demonstrated by combining elements from both continuous micro-flow and conventional batch reactors, coined stop-flow micro-tubing (SFMT) reactors. In SFMT, chemical reactions that require high pressure can be screened in parallel through a safer and convenient way. Cross-contamination, which is a common problem in reaction screening for continuous flow reactors, is avoided in SFMT. Moreover, the commercially available light-permeable micro-tubing can be incorporated into SFMT, serving as an excellent choice for light-mediated reactions due to a more effective uniform light exposure, compared to batch reactors. Overall, the SFMT reactor system is similar to continuous flow reactors and more superior than batch reactors for reactions that incorporate gas reagents and/or require light-illumination, which enables a simple but highly efficient reaction screening system. Furthermore, any successfully developed reaction in the SFMT reactor system can be conveniently translated to continuous-flow synthesis for large scale production.

Employing ISRU Models to Improve Hardware Design

NASA Technical Reports Server (NTRS)

Linne, Diane L.

2010-01-01

An analytical model for hydrogen reduction of regolith was used to investigate the effects of several key variables on the energy and mass performance of reactors for a lunar in-situ resource utilization oxygen production plant. Reactor geometry, reaction time, number of reactors, heat recuperation, heat loss, and operating pressure were all studied to guide hardware designers who are developing future prototype reactors. The effects of heat recuperation where the incoming regolith is pre-heated by the hot spent regolith before transfer was also investigated for the first time. In general, longer reaction times per batch provide a lower overall energy, but also result in larger and heavier reactors. Three reactors with long heat-up times results in similar energy requirements as a two-reactor system with all other parameters the same. Three reactors with heat recuperation results in energy reductions of 20 to 40 percent compared to a three-reactor system with no heat recuperation. Increasing operating pressure can provide similar energy reductions as heat recuperation for the same reaction times.

NEUTRONIC REACTOR SYSTEM

DOEpatents

Treshow, M.

1959-02-10

A reactor system incorporating a reactor of the heterogeneous boiling water type is described. The reactor is comprised essentially of a core submerged adwater in the lower half of a pressure vessel and two distribution rings connected to a source of water are disposed within the pressure vessel above the reactor core, the lower distribution ring being submerged adjacent to the uppcr end of the reactor core and the other distribution ring being located adjacent to the top of the pressure vessel. A feed-water control valve, responsive to the steam demand of the load, is provided in the feedwater line to the distribution rings and regulates the amount of feed water flowing to each distribution ring, the proportion of water flowing to the submerged distribution ring being proportional to the steam demand of the load. This invention provides an automatic means exterior to the reactor to control the reactivity of the reactor over relatively long periods of time without relying upon movement of control rods or of other moving parts within the reactor structure.

Oak Ridge National Laboratory Support of Non-light Water Reactor Technologies: Capabilities Assessment for NRC Near-term Implementation Action Plans for Non-light Water Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belles, Randy; Jain, Prashant K.; Powers, Jeffrey J.

The Oak Ridge National Laboratory (ORNL) has a rich history of support for light water reactor (LWR) and non-LWR technologies. The ORNL history involves operation of 13 reactors at ORNL including the graphite reactor dating back to World War II, two aqueous homogeneous reactors, two molten salt reactors (MSRs), a fast-burst health physics reactor, and seven LWRs. Operation of the High Flux Isotope Reactor (HFIR) has been ongoing since 1965. Expertise exists amongst the ORNL staff to provide non-LWR training; support evaluation of non-LWR licensing and safety issues; perform modeling and simulation using advanced computational tools; run laboratory experiments usingmore » equipment such as the liquid salt component test facility; and perform in-depth fuel performance and thermal-hydraulic technology reviews using a vast suite of computer codes and tools. Summaries of this expertise are included in this paper.« less

The IRIS Spool-Type Reactor Coolant Pump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kujawski, J.M.; Kitch, D.M.; Conway, L.E.

2002-07-01

IRIS (International Reactor Innovative and Secure) is a light water cooled, 335 MWe power reactor which is being designed by an international consortium as part of the US DOE NERI Program. IRIS features an integral reactor vessel that contains all the major reactor coolant system components including the reactor core, the coolant pumps, the steam generators and the pressurizer. This integral design approach eliminates the large coolant loop piping, and thus eliminates large loss-of-coolant accidents (LOCAs) as well as the individual component pressure vessels and supports. In addition, IRIS is being designed with a long life core and enhanced safetymore » to address the requirements defined by the US DOE for Generation IV reactors. One of the innovative features of the IRIS design is the adoption of a reactor coolant pump (called 'spool' pump) which is completely contained inside the reactor vessel. Background, status and future developments of the IRIS spool pump are presented in this paper. (authors)« less

10 CFR 171.3 - Scope.

Code of Federal Regulations, 2010 CFR

2010-01-01

... holding an operating license for a power reactor, test reactor or research reactor issued under part 50 of... authorizes operation of a power reactor. The regulations in this part also apply to any person holding a...

Advanced Test Reactor Tour

ScienceCinema

Miley, Don

2017-12-21

The Advanced Test Reactor at Idaho National Laboratory is the foremost nuclear materials test reactor in the world. This virtual tour describes the reactor, how experiments are conducted, and how spent nuclear fuel is handled and stored.

Looking Southwest at Reactor Box Furnaces With Reactor Boxes and ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Looking Southwest at Reactor Box Furnaces With Reactor Boxes and Repossessed Uranium in Recycle Recovery Building - Hematite Fuel Fabrication Facility, Recycle Recovery Building, 3300 State Road P, Festus, Jefferson County, MO

Development of a high-temperature durable catalyst for use in catalytic combustors for advanced automotive gas turbine engines

NASA Astrophysics Data System (ADS)

Tong, H.; Snow, G. C.; Chu, E. K.; Chang, R. L. S.; Angwin, M. J.; Pessagno, S. L.

1981-09-01

Durable catalytic reactors for advanced gas turbine engines were developed. Objectives were: to evaluate furnace aging as a cost effective catalytic reactor screening test, measure reactor degradation as a function of furnace aging, demonstrate 1,000 hours of combustion durability, and define a catalytic reactor system with a high probability of successful integration into an automotive gas turbine engine. Fourteen different catalytic reactor concepts were evaluated, leading to the selection of one for a durability combustion test with diesel fuel for combustion conditions. Eight additional catalytic reactors were evaluated and one of these was successfully combustion tested on propane fuel. This durability reactor used graded cell honeycombs and a combination of noble metal and metal oxide catalysts. The reactor was catalytically active and structurally sound at the end of the durability test.

Moving bed reactor setup to study complex gas-solid reactions.

PubMed

Gupta, Puneet; Velazquez-Vargas, Luis G; Valentine, Charles; Fan, Liang-Shih

2007-08-01

A moving bed scale reactor setup for studying complex gas-solid reactions has been designed in order to obtain kinetic data for scale-up purpose. In this bench scale reactor setup, gas and solid reactants can be contacted in a cocurrent and countercurrent manner at high temperatures. Gas and solid sampling can be performed through the reactor bed with their composition profiles determined at steady state. The reactor setup can be used to evaluate and corroborate model parameters accounting for intrinsic reaction rates in both simple and complex gas-solid reaction systems. The moving bed design allows experimentation over a variety of gas and solid compositions in a single experiment unlike differential bed reactors where the gas composition is usually fixed. The data obtained from the reactor can also be used for direct scale-up of designs for moving bed reactors.

Development of a high-temperature durable catalyst for use in catalytic combustors for advanced automotive gas turbine engines

NASA Technical Reports Server (NTRS)

Tong, H.; Snow, G. C.; Chu, E. K.; Chang, R. L. S.; Angwin, M. J.; Pessagno, S. L.

1981-01-01

Durable catalytic reactors for advanced gas turbine engines were developed. Objectives were: to evaluate furnace aging as a cost effective catalytic reactor screening test, measure reactor degradation as a function of furnace aging, demonstrate 1,000 hours of combustion durability, and define a catalytic reactor system with a high probability of successful integration into an automotive gas turbine engine. Fourteen different catalytic reactor concepts were evaluated, leading to the selection of one for a durability combustion test with diesel fuel for combustion conditions. Eight additional catalytic reactors were evaluated and one of these was successfully combustion tested on propane fuel. This durability reactor used graded cell honeycombs and a combination of noble metal and metal oxide catalysts. The reactor was catalytically active and structurally sound at the end of the durability test.

Spinning fluids reactor

DOEpatents

Miller, Jan D; Hupka, Jan; Aranowski, Robert

2012-11-20

A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.

Plum Brook Reactor Facility Control Room during Facility Startup

NASA Image and Video Library

1961-02-21

Operators test the National Aeronautics and Space Administration’s (NASA) Plum Brook Reactor Facility systems in the months leading up to its actual operation. The “Reactor On” signs are illuminated but the reactor core was not yet ready for chain reactions. Just a couple weeks after this photograph, Plum Brook Station held a media open house to unveil the 60-megawatt test reactor near Sandusky, Ohio. More than 60 members of the print media and radio and television news services met at the site to talk with community leaders and representatives from NASA and Atomic Energy Commission. The Plum Brook reactor went critical for the first time on the evening of June 14, 1961. It was not until April 1963 that the reactor reached its full potential of 60 megawatts. The reactor control room, located on the second floor of the facility, was run by licensed operators. The operators manually operated the shim rods which adjusted the chain reaction in the reactor core. The regulating rods could partially or completely shut down the reactor. The control room also housed remote area monitoring panels and other monitoring equipment that allowed operators to monitor radiation sensors located throughout the facility and to scram the reactor instantly if necessary. The color of the indicator lights corresponded with the elevation of the detectors in the various buildings. The reactor could also shut itself down automatically if the monitors detected any sudden irregularities.

Research Program of a Super Fast Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oka, Yoshiaki; Ishiwatari, Yuki; Liu, Jie

2006-07-01

Research program of a supercritical-pressure light water cooled fast reactor (Super Fast Reactor) is funded by MEXT (Ministry of Education, Culture, Sports, Science and Technology) in December 2005 as one of the research programs of Japanese NERI (Nuclear Energy Research Initiative). It consists of three programs. (1) development of Super Fast Reactor concept; (2) thermal-hydraulic experiments; (3) material developments. The purpose of the concept development is to pursue the advantage of high power density of fast reactor over thermal reactors to achieve economic competitiveness of fast reactor for its deployment without waiting for exhausting uranium resources. Design goal is notmore » breeding, but maximizing reactor power by using plutonium from spent LWR fuel. MOX will be the fuel of the Super Fast Reactor. Thermal-hydraulic experiments will be conducted with HCFC22 (Hydro chlorofluorocarbons) heat transfer loop of Kyushu University and supercritical water loop at JAEA. Heat transfer data including effect of grid spacers will be taken. The critical flow and condensation of supercritical fluid will be studied. The materials research includes the development and testing of austenitic stainless steel cladding from the experience of PNC1520 for LMFBR. Material for thermal insulation will be tested. SCWR (Supercritical-Water Cooled Reactor) of GIF (Generation-4 International Forum) includes both thermal and fast reactors. The research of the Super Fast Reactor will enhance SCWR research and the data base. The research period will be until March 2010. (authors)« less

Experiment for search for sterile neutrino at SM-3 reactor

NASA Astrophysics Data System (ADS)

Serebrov, A. P.; Ivochkin, V. G.; Samoylov, R. M.; Fomin, A. K.; Zinoviev, V. G.; Neustroev, P. V.; Golovtsov, V. L.; Gruzinsky, N. V.; Solovey, V. A.; Cherniy, A. V.; Zherebtsov, O. M.; Martemyanov, V. P.; Zinoev, V. G.; Tarasenkov, V. G.; Aleshin, V. I.; Petelin, A. L.; Pavlov, S. V.; Izhutov, A. L.; Sazontov, S. A.; Ryazanov, D. K.; Gromov, M. O.; Afanasiev, V. V.; Matrosov, L. N.; Matrosova, M. Yu.

2016-11-01

In connection with the question of possible existence of sterile neutrino the laboratory on the basis of SM-3 reactor was created to search for oscillations of reactor antineutrino. A prototype of a neutrino detector with scintillator volume of 400 l can be moved at the distance of 6-11 m from the reactor core. The measurements of background conditions have been made. It is shown that the main experimental problem is associated with cosmic radiation background. Test measurements of dependence of a reactor antineutrino flux on the distance from a reactor core have been made. The prospects of search for oscillations of reactor antineutrino at short distances are discussed.

Zirconium Hydride Space Power Reactor design.

NASA Technical Reports Server (NTRS)

Asquith, J. G.; Mason, D. G.; Stamp, S.

1972-01-01

The Zirconium Hydride Space Power Reactor being designed and fabricated at Atomics International is intended for a wide range of potential applications. Throughout the program a series of reactor designs have been evaluated to establish the unique requirements imposed by coupling with various power conversion systems and for specific applications. Current design and development emphasis is upon a 100 kilowatt thermal reactor for application in a 5 kwe thermoelectric space power generating system, which is scheduled to be fabricated and ground tested in the mid 70s. The reactor design considerations reviewed in this paper will be discussed in the context of this 100 kwt reactor and a 300 kwt reactor previously designed for larger power demand applications.

A document review to characterize Atomic International SNAP fuels shipped to INEL 1966--1973

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wahnschaffe, S.D.; Lords, R.E.; Kneff, D.W.

1995-09-01

This report provides the results of a document search and review study to obtain information on the spent fuels for the following six Nuclear Auxiliary Power (SNAP) reactor cores now stored at the Idaho National Engineering Laboratory (INEL): SNAP-2 Experimental Reactor, SNAP-2 Development Reactor, SNAP-10A Ground Test Reactor, SNAP-8 Experimental Reactor, SNAP-8 Development Reactor, and Shield Test Reactor. The report also covers documentation on SNAP fuel materials from four in-pile materials tests: NAA-82-1, NAA-115-2, NAA-117-1, and NAA-121. Pieces of these fuel materials are also stored at INEL as part of the SNAP fuel shipments.

A Roadmap of Innovative Nuclear Energy System

NASA Astrophysics Data System (ADS)

Sekimoto, Hiroshi

2017-01-01

Nuclear is a dense energy without CO2 emission. It can be used for more than 100,000 years using fast breeder reactors with uranium from the sea. However, it raises difficult problems associated with severe accidents, spent fuel waste and nuclear threats, which should be solved with acceptable costs. Some innovative reactors have attracted interest, and many designs have been proposed for small reactors. These reactors are considered much safer than conventional large reactors and have fewer technical obstructions. Breed-and-burn reactors have high potential to solve all inherent problems for peaceful use of nuclear energy. However, they have some technical problems with materials. A roadmap for innovative reactors is presented herein.

SNAP 10A FS-3 reactor performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hawley, J.P.; Johnson, R.A.

1966-08-15

SNAP 10FS-3 was the first flight-qualified SNAP reactor system to be operated in a simulated space environment. Prestart-up qualification testing, automatic start-up, endurance period performance, extended operation test and reactor shutdown are described as they affected, or were affected by, overall reactor performance. Performance of the reactor control system and the diagnostic instrumentation is critically evaluted.

10 CFR Appendix A to Part 110 - Illustrative List of Nuclear Reactor Equipment Under NRC Export Licensing Authority

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Illustrative List of Nuclear Reactor Equipment Under NRC... List of Nuclear Reactor Equipment Under NRC Export Licensing Authority Note—A nuclear reactor basically... nuclear reactor and capable of withstanding the operating pressure of the primary coolant. (2) On-line (e...

10 CFR Appendix A to Part 110 - Illustrative List of Nuclear Reactor Equipment Under NRC Export Licensing Authority

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Illustrative List of Nuclear Reactor Equipment Under NRC... List of Nuclear Reactor Equipment Under NRC Export Licensing Authority Note—A nuclear reactor basically... nuclear reactor and capable of withstanding the operating pressure of the primary coolant. (2) On-line (e...

Method for passive cooling liquid metal cooled nuclear reactors, and system thereof

DOEpatents

Hunsbedt, Anstein; Busboom, Herbert J.

1991-01-01

A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of partitions surrounding the reactor vessel in spaced apart relation forming intermediate areas for circulating heat transferring fluid which remove and carry away heat from the reactor vessel.

10 CFR 2.621 - Acceptance and docketing of application for early review of site suitability issues in a combined...

Code of Federal Regulations, 2012 CFR

2012-01-01

... Director of the Office of New Reactors or the Director of the Office of Nuclear Reactor Regulation, as...) The Director of the Office of New Reactors or the Director of the Office of Nuclear Reactor Regulation... of Nuclear Reactor Regulation, as appropriate, that they are complete. (c) If part one of the...

High yields of hydrogen production from methanol steam reforming with a cross-U type reactor

PubMed Central

Zhang, Shubin; Chen, Junyu; Zhang, Xuelin; Liu, Xiaowei

2017-01-01

This paper presents a numerical and experimental study on the performance of a methanol steam reformer integrated with a hydrogen/air combustion reactor for hydrogen production. A CFD-based 3D model with mass and momentum transport and temperature characteristics is established. The simulation results show that better performance is achieved in the cross-U type reactor compared to either a tubular reactor or a parallel-U type reactor because of more effective heat transfer characteristics. Furthermore, Cu-based micro reformers of both cross-U and parallel-U type reactors are designed, fabricated and tested for experimental validation. Under the same condition for reforming and combustion, the results demonstrate that higher methanol conversion is achievable in cross-U type reactor. However, it is also found in cross-U type reactor that methanol reforming selectivity is the lowest due to the decreased water gas shift reaction under high temperature, thereby carbon monoxide concentration is increased. Furthermore, the reformed gas generated from the reactors is fed into a high temperature proton exchange membrane fuel cell (PEMFC). In the test of discharging for 4 h, the fuel cell fed by cross-U type reactor exhibits the most stable performance. PMID:29121067

High yields of hydrogen production from methanol steam reforming with a cross-U type reactor.

PubMed

Zhang, Shubin; Zhang, Yufeng; Chen, Junyu; Zhang, Xuelin; Liu, Xiaowei

2017-01-01

This paper presents a numerical and experimental study on the performance of a methanol steam reformer integrated with a hydrogen/air combustion reactor for hydrogen production. A CFD-based 3D model with mass and momentum transport and temperature characteristics is established. The simulation results show that better performance is achieved in the cross-U type reactor compared to either a tubular reactor or a parallel-U type reactor because of more effective heat transfer characteristics. Furthermore, Cu-based micro reformers of both cross-U and parallel-U type reactors are designed, fabricated and tested for experimental validation. Under the same condition for reforming and combustion, the results demonstrate that higher methanol conversion is achievable in cross-U type reactor. However, it is also found in cross-U type reactor that methanol reforming selectivity is the lowest due to the decreased water gas shift reaction under high temperature, thereby carbon monoxide concentration is increased. Furthermore, the reformed gas generated from the reactors is fed into a high temperature proton exchange membrane fuel cell (PEMFC). In the test of discharging for 4 h, the fuel cell fed by cross-U type reactor exhibits the most stable performance.

Pressurized fluidized bed reactor and a method of operating the same

DOEpatents

Isaksson, J.

1996-02-20

A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine. 1 fig.

Pressurized fluidized bed reactor and a method of operating the same

DOEpatents

Isaksson, Juhani

1996-01-01

A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine.

Operating characteristic analysis of a 400 mH class HTS DC reactor in connection with a laboratory scale LCC type HVDC system

NASA Astrophysics Data System (ADS)

Kim, Sung-Kyu; Kim, Kwangmin; Park, Minwon; Yu, In-Keun; Lee, Sangjin

2015-11-01

High temperature superconducting (HTS) devices are being developed due to their advantages. Most line commutated converter based high voltage direct current (HVDC) transmission systems for long-distance transmission require large inductance of DC reactor; however, generally, copper-based reactors cause a lot of electrical losses during the system operation. This is driving researchers to develop a new type of DC reactor using HTS wire. The authors have developed a 400 mH class HTS DC reactor and a laboratory scale test-bed for line-commutated converter type HVDC system and applied the HTS DC reactor to the HVDC system to investigate their operating characteristics. The 400 mH class HTS DC reactor is designed using a toroid type magnet. The HVDC system is designed in the form of a mono-pole system with thyristor-based 12-pulse power converters. In this paper, the investigation results of the HTS DC reactor in connection with the HVDC system are described. The operating characteristics of the HTS DC reactor are analyzed under various operating conditions of the system. Through the results, applicability of an HTS DC reactor in an HVDC system is discussed in detail.

Potential of Electric Power Production from Microbial Fuel Cell (MFC) in Evapotranspiration Reactor for Leachate Treatment Using Alocasia macrorrhiza Plant and Eleusine indica Grass

NASA Astrophysics Data System (ADS)

Zaman, Badrus; Wardhana, Irawan Wisnu

2018-02-01

Microbial fuel cell is one of attractive electric power generator from nature bacterial activity. While, Evapotranspiration is one of the waste water treatment system which developed to eliminate biological weakness that utilize the natural evaporation process and bacterial activity on plant roots and plant media. This study aims to determine the potential of electrical energy from leachate treatment using evapotranspiration reactor. The study was conducted using local plant, namely Alocasia macrorrhiza and local grass, namely Eleusine Indica. The system was using horizontal MFC by placing the cathodes and anodes at different chamber (i.e. in the leachate reactor and reactor with plant media). Carbon plates was used for chatode-anodes material with size of 40 cm x 10 cm x1 cm. Electrical power production was measure by a digital multimeter for 30 days reactor operation. The result shows electric power production was fluctuated during reactor operation from all reactors. The electric power generated from each reactor was fluctuated, but from the reactor using Alocasia macrorrhiza plant reach to 70 μwatt average. From the reactor using Eleusine Indica grass was reached 60 μwatt average. Electric power production fluctuation is related to the bacterial growth pattern in the soil media and on the plant roots which undergo the adaptation process until the middle of the operational period and then in stable growth condition until the end of the reactor operation. The results indicate that the evapotranspiration reactor using Alocasia macrorrhiza plant was 60-95% higher electric power potential than using Eleusine Indica grass in short-term (30-day) operation. Although, MFC system in evapotranspiration reactor system was one of potential system for renewable electric power generation.

Assessment of the Technical Maturity of Generation IV Concepts for Test or Demonstration Reactor Applications, Revision 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gougar, Hans David

2015-10-01

The United States Department of Energy (DOE) commissioned a study the suitability of different advanced reactor concepts to support materials irradiations (i.e. a test reactor) or to demonstrate an advanced power plant/fuel cycle concept (demonstration reactor). As part of the study, an assessment of the technical maturity of the individual concepts was undertaken to see which, if any, can support near-term deployment. A Working Group composed of the authors of this document performed the maturity assessment using the Technical Readiness Levels as defined in DOE’s Technology Readiness Guide . One representative design was selected for assessment from of each ofmore » the six Generation-IV reactor types: gas-cooled fast reactor (GFR), lead-cooled fast reactor (LFR), molten salt reactor (MSR), supercritical water-cooled reactor (SCWR), sodium-cooled fast reactor (SFR), and very high temperature reactor (VHTR). Background information was obtained from previous detailed evaluations such as the Generation-IV Roadmap but other technical references were also used including consultations with concept proponents and subject matter experts. Outside of Generation IV activity in which the US is a party, non-U.S. experience or data sources were generally not factored into the evaluations as one cannot assume that this data is easily available or of sufficient quality to be used for licensing a US facility. The Working Group established the scope of the assessment (which systems and subsystems needed to be considered), adapted a specific technology readiness scale, and scored each system through discussions designed to achieve internal consistency across concepts. In general, the Working Group sought to determine which of the reactor options have sufficient maturity to serve either the test or demonstration reactor missions.« less

Preliminary study on aerobic granular biomass formation with aerobic continuous flow reactor

NASA Astrophysics Data System (ADS)

Yulianto, Andik; Soewondo, Prayatni; Handajani, Marissa; Ariesyady, Herto Dwi

2017-03-01

A paradigm shift in waste processing is done to obtain additional benefits from treated wastewater. By using the appropriate processing, wastewater can be turned into a resource. The use of aerobic granular biomass (AGB) can be used for such purposes, particularly for the processing of nutrients in wastewater. During this time, the use of AGB for processing nutrients more reactors based on a Sequencing Batch Reactor (SBR). Studies on the use of SBR Reactor for AGB demonstrate satisfactory performance in both formation and use. SBR reactor with AGB also has been applied on a full scale. However, the use use of SBR reactor still posses some problems, such as the need for additional buffer tank and the change of operation mode from conventional activated sludge to SBR. This gives room for further reactor research with the use of a different type, one of which is a continuous reactor. The purpose of this study is to compare AGB formation using continuous reactor and SBR with same operation parameter. Operation parameter are Organic Loading Rate (OLR) set to 2,5 Kg COD/m3.day with acetate as substrate, aeration rate 3 L/min, and microorganism from Hospital WWTP as microbial source. SBR use two column reactor with volumes 2 m3, and continuous reactor uses continuous airlift reactor, with two compartments and working volume of 5 L. Results from preliminary research shows that although the optimum results are not yet obtained, AGB can be formed on the continuous reactor. When compared with AGB generated by SBR, then the characteristics of granular diameter showed similarities, while the sedimentation rate and Sludge Volume Index (SVI) characteristics showed lower yields.

Assessment of Sensor Technologies for Advanced Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korsah, Kofi; Kisner, R. A.; Britton Jr., C. L.

This paper provides an assessment of sensor technologies and a determination of measurement needs for advanced reactors (AdvRx). It is a summary of a study performed to provide the technical basis for identifying and prioritizing research targets within the instrumentation and control (I&C) Technology Area under the Department of Energy’s (DOE’s) Advanced Reactor Technology (ART) program. The study covered two broad reactor technology categories: High Temperature Reactors and Fast Reactors. The scope of “High temperature reactors” included Gen IV reactors whose coolant exit temperatures exceed ≈650 °C and are moderated (as opposed to fast reactors). To bound the scope formore » fast reactors, this report reviewed relevant operating experience from US-operated Sodium Fast Reactor (SFR) and relevant test experience from the Fast Flux Test Facility (FFTF). For high temperature reactors the study showed that in many cases instrumentation have performed reasonably well in research and demonstration reactors. However, even in cases where the technology is “mature” (such as thermocouples), HTGRs can benefit from improved technologies. Current HTGR instrumentation is generally based on decades-old technology and adapting newer technologies could provide significant advantages. For sodium fast reactors, the study found that several key research needs arise around (1) radiation-tolerant sensor design for in-vessel or in-core applications, where possible non-invasive sensing approaches for key parameters that minimize the need to deploy sensors in-vessel, (2) approaches to exfiltrating data from in-vessel sensors while minimizing penetrations, (3) calibration of sensors in-situ, and (4) optimizing sensor placements to maximize the information content while minimizing the number of sensors needed.« less

Shutdown system for a nuclear reactor

DOEpatents

Groh, E.F.; Olson, A.P.; Wade, D.C.; Robinson, B.W.

1984-06-05

An ultimate shutdown system is provided for termination of neutronic activity in a nuclear reactor. The shutdown system includes bead chains comprising spherical containers suspended on a flexible cable. The containers are comprised of mating hemispherical shells which provide a ruggedized enclosure for reactor poison material. The bead chains, normally suspended above the reactor core on storage spools, are released for downward travel upon command from an external reactor monitor. The chains are capable of horizontal movement, so as to flow around obstructions in the reactor during their downward motion. 8 figs.

Reactor vessel support system. [LMFBR

DOEpatents

Golden, M.P.; Holley, J.C.

1980-05-09

A reactor vessel support system includes a support ring at the reactor top supported through a box ring on a ledge of the reactor containment. The box ring includes an annular space in the center of its cross-section to reduce heat flow and is keyed to the support ledge to transmit seismic forces from the reactor vessel to the containment structure. A coolant channel is provided at the outside circumference of the support ring to supply coolant gas through the keyways to channels between the reactor vessel and support ledge into the containment space.

NUCLEAR REACTOR AS THE OBJECT OF CONTROL. AUTOMATIC CONTROL OF AIRCRAFT ENGINES . B.S. Voronkev Collection of Articles

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

BS> The dynamics of a power reactor is treated in some detail. Although the reactor is described by a nonlinear differential equation of the seventh order, a two-group approximstion with prompt neutrons and one averaged group of delayed neutrons may be used. When the reactor is in equilibrium, the reactor equation may be linearized in two ways. The effects of positive and negative coefficients of tins of the reactor are discussed. The nonlinear character of the control rods is trested. (D.L.C.)

Shutdown system for a nuclear reactor

DOEpatents

Groh, Edward F.; Olson, Arne P.; Wade, David C.; Robinson, Bryan W.

1984-01-01

An ultimate shutdown system is provided for termination of neutronic activity in a nuclear reactor. The shutdown system includes bead chains comprising spherical containers suspended on a flexible cable. The containers are comprised of mating hemispherical shells which provide a ruggedized enclosure for reactor poison material. The bead chains, normally suspended above the reactor core on storage spools, are released for downward travel upon command from an external reactor monitor. The chains are capable of horizontal movement, so as to flow around obstructions in the reactor during their downward motion.

Passive cooling safety system for liquid metal cooled nuclear reactors

DOEpatents

Hunsbedt, Anstein; Boardman, Charles E.; Hui, Marvin M.; Berglund, Robert C.

1991-01-01

A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of partitions surrounding the reactor vessel in spaced apart relation forming intermediate areas for circulating heat transferring fluid which remove and carry away heat from the reactor vessel. The passive cooling system includes a closed primary fluid circuit through the partitions surrounding the reactor vessel and a partially adjoining secondary open fluid circuit for carrying transferred heat out into the atmosphere.

Special features of the inverse-beta-decay reaction proceeding on a proton in a reactor-antineutrino flux

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kopeikin, V. I., E-mail: kopeikin46@yandex.ru; Skorokhvatov, M. D., E-mail: skorokhvatov-md@nrcki.ru

2017-03-15

The evolution of the reactor-antineutrino spectrum and the evolution of the spectrum of positrons from the inverse-beta-decay reaction in the course of reactor operation and after reactor shutdown are considered. The present-day status in determining the initial reactor-antineutrino spectrum on the basis of spectra of beta particles from mixtures of products originating from uranium and plutonium fission is described. A local rise of the experimental spectrum of reactor antineutrinos with respect to the expected spectrum is studied.

An atmospheric pressure flow reactor: Gas phase kinetics and mechanism in tropospheric conditions without wall effects

NASA Technical Reports Server (NTRS)

Koontz, Steven L.; Davis, Dennis D.; Hansen, Merrill

1988-01-01

A new type of gas phase flow reactor, designed to permit the study of gas phase reactions near 1 atm of pressure, is described. A general solution to the flow/diffusion/reaction equations describing reactor performance under pseudo-first-order kinetic conditions is presented along with a discussion of critical reactor parameters and reactor limitations. The results of numerical simulations of the reactions of ozone with monomethylhydrazine and hydrazine are discussed, and performance data from a prototype flow reactor are presented.

DOE/NNSA perspective safeguard by design: GEN III/III+ light water reactors and beyond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Paul Y

2010-12-10

An overview of key issues relevant to safeguards by design (SBD) for GEN III/IV nuclear reactors is provided. Lessons learned from construction of typical GEN III+ water reactors with respect to SBD are highlighted. Details of SBD for safeguards guidance development for GEN III/III+ light water reactors are developed and reported. This paper also identifies technical challenges to extend SBD including proliferation resistance methodologies to other GEN III/III+ reactors (except HWRs) and GEN IV reactors because of their immaturity in designs.

Nuclear engine flow reactivity shim control

DOEpatents

Walsh, J.M.

1973-12-11

A nuclear engine control system is provided which automatically compensates for reactor reactivity uncertainties at the start of life and reactivity losses due to core corrosion during the reactor life in gas-cooled reactors. The coolant gas flow is varied automatically by means of specially provided control apparatus so that the reactor control drums maintain a predetermined steady state position throughout the reactor life. This permits the reactor to be designed for a constant drum position and results in a desirable, relatively flat temperature profile across the core. (Official Gazette)

Nuclear Thermal Propulsion: A Joint NASA/DOE/DOD Workshop

NASA Technical Reports Server (NTRS)

Clark, John S. (Editor)

1991-01-01

Papers presented at the joint NASA/DOE/DOD workshop on nuclear thermal propulsion are compiled. The following subject areas are covered: nuclear thermal propulsion programs; Rover/NERVA and NERVA systems; Low Pressure Nuclear Thermal Rocket (LPNTR); particle bed reactor nuclear rocket; hybrid propulsion systems; wire core reactor; pellet bed reactor; foil reactor; Droplet Core Nuclear Rocket (DCNR); open cycle gas core nuclear rockets; vapor core propulsion reactors; nuclear light bulb; Nuclear rocket using Indigenous Martian Fuel (NIMF); mission analysis; propulsion and reactor technology; development plans; and safety issues.

Control rod drive for reactor shutdown

DOEpatents

McKeehan, Ernest R.; Shawver, Bruce M.; Schiro, Donald J.; Taft, William E.

1976-01-20

A means for rapidly shutting down or scramming a nuclear reactor, such as a liquid metal-cooled fast breeder reactor, and serves as a backup to the primary shutdown system. The control rod drive consists basically of an in-core assembly, a drive shaft and seal assembly, and a control drive mechanism. The control rod is driven into the core region of the reactor by gravity and hydraulic pressure forces supplied by the reactor coolant, thus assuring that common mode failures will not interfere with or prohibit scramming the reactor when necessary.

Indirect passive cooling system for liquid metal cooled nuclear reactors

DOEpatents

Hunsbedt, Anstein; Boardman, Charles E.

1990-01-01

A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of partitions surrounding the reactor vessel in spaced apart relation forming intermediate areas for circulating heat transferring fluid which remove and carry away heat from the reactor vessel. The passive cooling system includes a closed primary fluid circuit through the partitions surrounding the reactor vessel and a partially adjoining secondary open fluid circuit for carrying transferred heat out into the atmosphere.

Self isolating high frequency saturable reactor

DOEpatents

Moore, James A.

1998-06-23

The present invention discloses a saturable reactor and a method for decoupling the interwinding capacitance from the frequency limitations of the reactor so that the equivalent electrical circuit of the saturable reactor comprises a variable inductor. The saturable reactor comprises a plurality of physically symmetrical magnetic cores with closed loop magnetic paths and a novel method of wiring a control winding and a RF winding. The present invention additionally discloses a matching network and method for matching the impedances of a RF generator to a load. The matching network comprises a matching transformer and a saturable reactor.

Thorium fueled reactor

NASA Astrophysics Data System (ADS)

Sipaun, S.

2017-01-01

Current development in thorium fueled reactors shows that they can be designed to operate in the fast or thermal spectrum. The thorium/uranium fuel cycle converts fertile thorium-232 into fissile uranium-233, which fissions and releases energy. This paper analyses the characteristics of thorium fueled reactors and discusses the thermal reactor option. It is found that thorium fuel can be utilized in molten salt reactors through many configurations and designs. A balanced assessment on the feasibility of adopting one reactor technology versus another could lead to optimized benefits of having thorium resource.

A Basic LEGO Reactor Design for the Provision of Lunar Surface Power

DOE Office of Scientific and Technical Information (OSTI.GOV)

John Darrell Bess

2008-06-01

A final design has been established for a basic Lunar Evolutionary Growth-Optimized (LEGO) Reactor using current and near-term technologies. The LEGO Reactor is a modular, fast-fission, heatpipe-cooled, clustered-reactor system for lunar-surface power generation. The reactor is divided into subcritical units that can be safely launched with lunar shipments from Earth, and then emplaced directly into holes drilled into the lunar regolith to form a critical reactor assembly. The regolith would not just provide radiation shielding, but serve as neutron-reflector material as well. The reactor subunits are to be manufactured using proven and tested materials for use in radiation environments, suchmore » as uranium-dioxide fuel, stainless-steel cladding and structural support, and liquid-sodium heatpipes. The LEGO Reactor system promotes reliability, safety, and ease of manufacture and testing at the cost of an increase in launch mass per overall rated power level and a reduction in neutron economy when compared to a single-reactor system. A single unshielded LEGO Reactor subunit has an estimated mass of approximately 448 kg and provides approximately 5 kWe. The overall envelope for a single subunit with fully extended radiator panels has a height of 8.77 m and a diameter of 0.50 m. Six subunits could provide sufficient power generation throughout the initial stages of establishing a lunar outpost. Portions of the reactor may be neutronically decoupled to allow for reduced power production during unmanned periods of base operations. During later stages of lunar-base development, additional subunits may be emplaced and coupled into the existing LEGO Reactor network, subject to lunar base power demand. Improvements in reactor control methods, fuel form and matrix, shielding, as well as power conversion and heat rejection techniques can help generate an even more competitive LEGO Reactor design. Further modifications in the design could provide power generative opportunities for use on other extraterrestrial surfaces.« less

Small space reactor power systems for unmanned solar system exploration missions

NASA Technical Reports Server (NTRS)

Bloomfield, Harvey S.

1987-01-01

A preliminary feasibility study of the application of small nuclear reactor space power systems to the Mariner Mark II Cassini spacecraft/mission was conducted. The purpose of the study was to identify and assess the technology and performance issues associated with the reactor power system/spacecraft/mission integration. The Cassini mission was selected because study of the Saturn system was identified as a high priority outer planet exploration objective. Reactor power systems applied to this mission were evaluated for two different uses. First, a very small 1 kWe reactor power system was used as an RTG replacement for the nominal spacecraft mission science payload power requirements while still retaining the spacecraft's usual bipropellant chemical propulsion system. The second use of reactor power involved the additional replacement of the chemical propulsion system with a small reactor power system and an electric propulsion system. The study also provides an examination of potential applications for the additional power available for scientific data collection. The reactor power system characteristics utilized in the study were based on a parametric mass model that was developed specifically for these low power applications. The model was generated following a neutronic safety and operational feasibility assessment of six small reactor concepts solicited from U.S. industry. This assessment provided the validation of reactor safety for all mission phases and generatad the reactor mass and dimensional data needed for the system mass model.

A brief history of design studies on innovative nuclear reactors

NASA Astrophysics Data System (ADS)

Sekimoto, Hiroshi

2014-09-01

In a short period after the success of CP1, many types of nuclear reactors were proposed and investigated. However, soon only a small number of reactors were selected for practical use. Around 1970, only LWRs with small number of CANDUs were operated in the western world, and FBRs were under development. It was about the time when Apollo moon landing was accomplished. However, at the same time, the future of human being was widely considered pessimistic and Limits to Growth was published. In the end of 1970's the TMI accident occurred and many nuclear reactor contracts were cancelled in USA and any more contracts had not been concluded until recent years. From the reflection of this accident, many Inherent Safe Reactors (ISRs) were proposed, though none of them were constructed. A common idea of ISRs is smallness of their size. Tokyo Institute of Technology (TokyoTech) held a symposium on small reactors, SR/TIT, in 1991, where many types of small ISRs were presented. Recently small reactors attract interest again. The most ideas employed in these reactors were the same discussed in SR/TIT. In 1980's the radioactive wastes from fuel cycle became a severe problem around the world. In TokyoTech, this issue was discussed mainly from the viewpoint of nuclear transmutations. The neutron economy became inevitable for these innovative nuclear reactors especially small long-life reactors and transmutation reactors.

WORKER STACKS GRAPHITE BLOCKS AGAINST INNER SOUTH WALL OF REACTOR. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

WORKER STACKS GRAPHITE BLOCKS AGAINST INNER SOUTH WALL OF REACTOR. INL NEGATIVE NO. 3925. Unknown Photographer, 12/14/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

Looking Northeast in Oxide Building at Reactors on Second Floor ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Looking Northeast in Oxide Building at Reactors on Second Floor Including Reactor One (Left) and Reactor Two (Right) - Hematite Fuel Fabrication Facility, Oxide Building & Oxide Loading Dock, 3300 State Road P, Festus, Jefferson County, MO

Preliminary Comparison of Radioactive Waste Disposal Cost for Fusion and Fission Reactors

NASA Astrophysics Data System (ADS)

Seki, Yasushi; Aoki, Isao; Yamano, Naoki; Tabara, Takashi

1997-09-01

The environmental and economic impact of radioactive waste (radwaste) generated from fusion power reactors using five types of structural materials and a fission reactor has been evaluated and compared. Possible radwaste disposal scenario of fusion radwaste in Japan is considered. The exposure doses were evaluated for the skyshine of gamma-ray during the disposal operation, groundwater migration scenario during the institutional control period of 300 years and future site use scenario after the institutional period. The radwaste generated from a typical light water fission reactor was evaluated using the same methodology as for the fusion reactors. It is found that radwaste from the fusion reactors using F82H and SiC/SiC composites without impurities could be disposed by the shallow land disposal presently applied to the low level waste in Japan. The disposal cost of radwaste from five fusion power reactors and a typical light water reactor were roughly evaluated and compared.

High throughput semiconductor deposition system

DOEpatents

Young, David L.; Ptak, Aaron Joseph; Kuech, Thomas F.; Schulte, Kevin; Simon, John D.

2017-11-21

A reactor for growing or depositing semiconductor films or devices. The reactor may be designed for inline production of III-V materials grown by hydride vapor phase epitaxy (HVPE). The operating principles of the HVPE reactor can be used to provide a completely or partially inline reactor for many different materials. An exemplary design of the reactor is shown in the attached drawings. In some instances, all or many of the pieces of the reactor formed of quartz, such as welded quartz tubing, while other reactors are made from metal with appropriate corrosion resistant coatings such as quartz or other materials, e.g., corrosion resistant material, or stainless steel tubing or pipes may be used with a corrosion resistant material useful with HVPE-type reactants and gases. Using HVPE in the reactor allows use of lower-cost precursors at higher deposition rates such as in the range of 1 to 5 .mu.m/minute.

Nuclear reactor vessel fuel thermal insulating barrier

DOEpatents

Keegan, C. Patrick; Scobel, James H.; Wright, Richard F.

2013-03-19

The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel that has a hemispherical lower section that increases in volume from the center line of the reactor to the outer extent of the diameter of the thermal insulating barrier and smoothly transitions up the side walls of the vessel. The space between the thermal insulating harrier and the reactor vessel forms a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive inlet valve for the cooling water includes a buoyant door that is normally maintained sealed under its own weight and floats open when the cavity is Hooded. Passively opening steam vents are also provided.

Nuclear reactors built, being built, or planned, 1991

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simpson, B.

1992-07-01

This document contains unclassified information about facilities built, being built, or planned in the United States for domestic use or export as of December 31, 1991. The book is divided into three major sections: Section 1 consists of a reactor locator map and reactor tables; Section 2 includes nuclear reactors that are operating, being built, or planned; and Section 3 includes reactors that have been shut down permanently or dismantled. Sections 2 and 3 contain the following classification of reactors: Civilian, Production, Military, Export, and Critical Assembly. Export reactor refers to a reactor for which the principal nuclear contractor ismore » an American company -- working either independently or in cooperation with a foreign company (Part 4, in each section). Critical assembly refers to an assembly of fuel and assembly of fuel and moderator that requires an external source of neutrons to initiate and maintain fission. A critical assembly is used for experimental measurements (Part 5).« less

Nuclear component horizontal seismic restraint

DOEpatents

Snyder, Glenn J.

1988-01-01

A nuclear component horizontal seismic restraint. Small gaps limit horizontal displacement of components during a seismic occurrence and therefore reduce dynamic loadings on the free lower end. The reactor vessel and reactor guard vessel use thicker section roll-forged rings welded between the vessel straight shell sections and the bottom hemispherical head sections. The inside of the reactor guard vessel ring forging contains local vertical dovetail slots and upper ledge pockets to mount and retain field fitted and installed blocks. As an option, the horizontal displacement of the reactor vessel core support cone can be limited by including shop fitted/installed local blocks in opposing alignment with the reactor vessel forged ring. Beams embedded in the wall of the reactor building protrude into apertures in the thermal insulation shell adjacent the reactor guard vessel ring and have motion limit blocks attached thereto to provide to a predetermined clearance between the blocks and reactor guard vessel ring.

Safety control circuit for a neutronic reactor

DOEpatents

Ellsworth, Howard C.

2004-04-27

A neutronic reactor comprising an active portion containing material fissionable by neutrons of thermal energy, means to control a neutronic chain reaction within the reactor comprising a safety device and a regulating device, a safety device including means defining a vertical channel extending into the reactor from an aperture in the upper surface of the reactor, a rod containing neutron-absorbing materials slidably disposed within the channel, means for maintaining the safety rod in a withdrawn position relative to the active portion of the reactor including means for releasing said rod on actuation thereof, a hopper mounted above the active portion of the reactor having a door disposed at the bottom of the hopper opening into the vertical channel, a plurality of bodies of neutron-absorbing materials disposed within the hopper, and means responsive to the failure of the safety rod on actuation thereof to enter the active portion of the reactor for opening the door in the hopper.

Eastern Europe Research Reactor Initiative nuclear education and training courses - Current activities and future challenges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snoj, L.; Sklenka, L.; Rataj, J.

2012-07-01

The Eastern Europe Research Reactor Initiative was established in January 2008 to enhance cooperation between the Research Reactors in Eastern Europe. It covers three areas of research reactor utilisation: irradiation of materials and fuel, radioisotope production, neutron beam experiments, education and training. In the field of education and training an EERRI training course was developed. The training programme has been elaborated with the purpose to assist IAEA Member States, which consider building a research reactor (RR) as a first step to develop nuclear competence and infrastructure in the Country. The major strength of the reactor is utilisation of three differentmore » research reactors and a lot of practical exercises. Due to high level of adaptability, the course can be tailored to specific needs of institutions with limited or no access to research reactors. (authors)« less

Eddy Current Flow Measurements in the FFTF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nielsen, Deborah L.; Polzin, David L.; Omberg, Ronald P.

2017-02-02

The Fast Flux Test Facility (FFTF) is the most recent liquid metal reactor (LMR) to be designed, constructed, and operated by the U.S. Department of Energy (DOE). The 400-MWt sodium-cooled, fast-neutron flux reactor plant was designed for irradiation testing of nuclear reactor fuels and materials for liquid metal fast breeder reactors. Following shut down of the Clinch River Breeder Reactor Plant (CRBRP) project in 1983, FFTF continued to play a key role in providing a test bed for demonstrating performance of advanced fuel designs and demonstrating operation, maintenance, and safety of advanced liquid metal reactors. The FFTF Program provides valuablemore » information for potential follow-on reactor projects in the areas of plant system and component design, component fabrication, fuel design and performance, prototype testing, site construction, and reactor control and operations. This report provides HEDL-TC-1344, “ECFM Flow Measurements in the FFTF Using Phase-Sensitive Detectors”, March 1979.« less

Transmutation of actinides in power reactors.

PubMed

Bergelson, B R; Gerasimov, A S; Tikhomirov, G V

2005-01-01

Power reactors can be used for partial short-term transmutation of radwaste. This transmutation is beneficial in terms of subsequent storage conditions for spent fuel in long-term storage facilities. CANDU-type reactors can transmute the main minor actinides from two or three reactors of the VVER-1000 type. A VVER-1000-type reactor can operate in a self-service mode with transmutation of its own actinides.

Double-clad nuclear fuel safety rod

DOEpatents

McCarthy, William H.; Atcheson, Donald B.; Vaidyanathan, Swaminathan

1984-01-01

A device for shutting down a nuclear reactor during an undercooling or overpower event, whether or not the reactor's scram system operates properly. This is accomplished by double-clad fuel safety rods positioned at various locations throughout the reactor core, wherein melting of a secondary internal cladding of the rod allows the fuel column therein to shift from the reactor core to place the reactor in a subcritical condition.

Double-clad nuclear-fuel safety rod

DOEpatents

McCarthy, W.H.; Atcheson, D.B.

1981-12-30

A device for shutting down a nuclear reactor during an undercooling or overpower event, whether or not the reactor's scram system operates properly. This is accomplished by double-clad fuel safety rods positioned at various locations throughout the reactor core, wherein melting of a secondary internal cladding of the rod allows the fuel column therein to shift from the reactor core to place the reactor in a subcritical condition.

NEUTRONIC REACTOR POWER PLANT

DOEpatents

Metcalf, H.E.

1962-12-25

This patent relates to a nuclear reactor power plant incorporating an air-cooled, beryllium oxide-moderated, pebble bed reactor. According to the invention means are provided for circulating a flow of air through tubes in the reactor to a turbine and for directing a sidestream of the circu1ating air through the pebble bed to remove fission products therefrom as well as assist in cooling the reactor. (AEC)

U.S. Nuclear Cooperation with India: Issues for Congress

DTIC Science & Technology

2008-11-03

separation list: ! 8 indigenous Indian power reactors ! Fast Breeder test Reactor (FTBR) and Prototype Fast Breeder Reactors (PFBR) under construction...facilities like reprocessing and enrichment plants and breeder reactors could be viewed as providing a significant nonproliferation benefit because the... breeder reactors would support the 2002 U.S. National Strategy to Combat Weapons of Mass Destruction, in which the United States pledged to “continue to

U.S. Nuclear Cooperation with India: Issues for Congress

DTIC Science & Technology

2008-10-02

8 indigenous Indian power reactors ! Fast Breeder test Reactor (FTBR) and Prototype Fast Breeder Reactors (PFBR) under construction ! Enrichment... breeder reactors could be viewed as providing a significant nonproliferation benefit because the materials produced by these plants are a few steps closer...to potential use in a bomb. In addition, safeguards on enrichment, reprocessing plants, and breeder reactors would support the 2002 U.S. National

BUILDING FOR THE EXPERIMENTAL SWIMMING POOL REACTOR OF 3Mw OF THE JUNTA DE ENERGIA NUCLEAR (in Spanish)

DOE Office of Scientific and Technical Information (OSTI.GOV)

de la Camara, S.N.

1958-10-01

The Spanish experimental swimming pool reactor is constructed on the grounds of the Ciudad Universitaria de Madrid. A general layout of the reactor building and its annexes is given, and the reactor building itself is described. The construction of the reactor building and the characteristics of the annex building are discussed. (J.S.R.)

PRELIMINARY HAZARDS SUMMARY REPORT FOR THE VALLECITOS SUPERHEAT REACTOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, J.L.

1961-02-01

BS>The Vallecitos Superheat Reactor (VSR) is a light-watermoderated, thermal-spectrum reactor, cooled by a combination of moderator boiling and forced convection cooling with saturated steam. The reactor core consists of 32 fuel hurdles containing 5300 lb of UO/sub 2/ enriched in U/sub 235/ to 3.6%. The fuel elements are arranged in individual process tubes that direct the cooling steam flow and separate the steam from the water moderator. The reactor vessel is designed for 1250 psig and operates at 960 to 1000 psig. With the reactor operating at 12.5 Mw(t), the maximum fuel cladding temperature is 1250 deg F and themore » cooling steam is superheated to an average temperature of about 810 deg F at 905 psig. Nu clear operation of the reactor is controlled by 12 control rods, actuated by drives mounted on the bottom of the reactor vessel. The water moderator recirculates inside the reactor vessel and through the core region by natural convection. Inherent safety features of the reactor include the negative core reactivity effects upon heating the UO/sub 2/ fuel (Doppler effect), upon increasing the temperature or void content of the moderator in the operating condition, and upon unflooding the fuel process tubes in the hot condition. Snfety features designed into the reactor and plant systems include a system of sensors and devices to detect petentially unsafe operating conditions and to initiate automatically the appropriate countermeasures, a set of fast and reliable control rods for scramming the reactor if a potentially unsafe condition occurs, a manually-actuated liquid neutron poison system, and an emergency cooling system to provide continued steam flow through the reactor core in the event the reactor becomes isolated from either its normal source of steam supply or discharge. The release of radioactivity to unrestricted areas is maintained within permissible limits by monitoring the radioactivity of wastes and controlling their release. The reactor and many of its auxiliaries are housed within a high-integrity essentially leak-tight containment vessel. (auth)« less

Fast formation of aerobic granules by combining strong hydraulic selection pressure with overstressed organic loading rate.

PubMed

Liu, Yong-Qiang; Tay, Joo-Hwa

2015-09-01

The combined strong hydraulic selection pressure (HSP) with overstressed organic loading rate (OLR) as a fast granulation strategy was used to enhance aerobic granulation. To investigate the wide applicability of this strategy to different scenarios and its relevant mechanism, different settling times, different inoculums, different exchange ratios, different reactor configurations, and different shear force were used in this study. It was found that clear granules were formed within 24 h and steady state reached within three days when the fast granulation strategy was used in a lab-scale reactor seeded with well settled activated sludge (Reactor 2). However, granules appeared after 2-week operation and reached steady state after one month at the traditional step-wise decreased settling time from 20 to 2 min with OLR of 6 g COD/L·d (Reactor 1). With the fast granulation strategy, granules appeared within 24 h even with bulking sludge as seed to start up Reactor 3, but 6-day lag phase was observed compared with Reactor 2. Both Reactor 2 and Reactor 3 experienced sigmoidal growth curve in terms of biomass accumulation and granule size increase after granulation. In addition, the reproducible results in pilot-scale reactors (Reactor 5 and Reactor 6) with diameter of 20 cm and height/diameter ratio (H/D) of 4 further proved that reactor configuration and fluid flow pattern had no effect on the aerobic granulation when the fast granulation strategy was employed, but biomass accumulation experienced a short lag phase too in Reactor 5 and Reactor 6. Although overstressed OLR was favorable for fast granulation, it also led to the fluffy granules after around two-week operation. However, the stable 6-month operation of Reactor 3 demonstrated that the rapidly formed granules were able to maintain long-term stability by reducing OLR from 12 g COD/L·d to 6 g COD/L·d. A mechanism of fast granulation with the strategy of combined strong HSP and OLR was proposed to explain results and guide the operation with this fast strategy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Application of ATHLET/DYN3D coupled codes system for fast liquid metal cooled reactor steady state simulation

NASA Astrophysics Data System (ADS)

Ivanov, V.; Samokhin, A.; Danicheva, I.; Khrennikov, N.; Bouscuet, J.; Velkov, K.; Pasichnyk, I.

2017-01-01

In this paper the approaches used for developing of the BN-800 reactor test model and for validation of coupled neutron-physic and thermohydraulic calculations are described. Coupled codes ATHLET 3.0 (code for thermohydraulic calculations of reactor transients) and DYN3D (3-dimensional code of neutron kinetics) are used for calculations. The main calculation results of reactor steady state condition are provided. 3-D model used for neutron calculations was developed for start reactor BN-800 load. The homogeneous approach is used for description of reactor assemblies. Along with main simplifications, the main reactor BN-800 core zones are described (LEZ, MEZ, HEZ, MOX, blankets). The 3D neutron physics calculations were provided with 28-group library, which is based on estimated nuclear data ENDF/B-7.0. Neutron SCALE code was used for preparation of group constants. Nodalization hydraulic model has boundary conditions by coolant mass-flow rate for core inlet part, by pressure and enthalpy for core outlet part, which can be chosen depending on reactor state. Core inlet and outlet temperatures were chosen according to reactor nominal state. The coolant mass flow rate profiling through the core is based on reactor power distribution. The test thermohydraulic calculations made with using of developed model showed acceptable results in coolant mass flow rate distribution through the reactor core and in axial temperature and pressure distribution. The developed model will be upgraded in future for different transient analysis in metal-cooled fast reactors of BN type including reactivity transients (control rods withdrawal, stop of the main circulation pump, etc.).

How to Produce a Reactor Neutron Spectrum Using a Proton Accelerator

DOE PAGES

Burns, Kimberly A.; Wootan, David W.; Gates, Robert O.; ...

2015-06-18

A method for reproducing the neutron energy spectrum present in the core of an operating nuclear reactor using an engineered target in an accelerator proton beam is proposed. The protons interact with a target to create neutrons through various (p,n) type reactions. Spectral tailoring of the emitted neutrons can be used to modify the energy of the generated neutron spectrum to represent various reactor spectra. Through the use of moderators and reflectors, the neutron spectrum can be modified to reproduce many different spectra of interest including spectra in small thermal test reactors, large pressurized water reactors, and fast reactors. Themore » particular application of this methodology is the design of an experimental approach for using an accelerator to measure the betas produced during fission to be used to reduce uncertainties in the interpretation of reactor antineutrino measurements. This approach involves using a proton accelerator to produce a neutron field representative of a power reactor, and using this neutron field to irradiate fission foils of the primary isotopes contributing to fission in the reactor, creating unstable, neutron rich fission products that subsequently beta decay and emit electron antineutrinos. A major advantage of an accelerator neutron source over a neutron beam from a thermal reactor is that the fast neutrons can be slowed down or tailored to approximate various power reactor spectra. An accelerator based neutron source that can be tailored to match various reactor neutron spectra provides an advantage for control in studying how changes in the neutron spectra affect parameters such as the resulting fission product beta spectrum.« less

Biological hydrogen production by Clostridium acetobutylicum in an unsaturated flow reactor.

PubMed

Zhang, Husen; Bruns, Mary Ann; Logan, Bruce E

2006-02-01

A mesophilic unsaturated flow (trickle bed) reactor was designed and tested for H2 production via fermentation of glucose. The reactor consisted of a column packed with glass beads and inoculated with a pure culture (Clostridium acetobutylicum ATCC 824). A defined medium containing glucose was fed at a flow rate of 1.6 mL/min (0.096 L/h) into the capped reactor, producing a hydraulic retention time of 2.1 min. Gas-phase H2 concentrations were constant, averaging 74 +/- 3% for all conditions tested. H2 production rates increased from 89 to 220 mL/hL of reactor when influent glucose concentrations were varied from 1.0 to 10.5 g/L. Specific H2 production rate ranged from 680 to 1270 mL/g glucose per liter of reactor (total volume). The H2 yield was 15-27%, based on a theoretical limit by fermentation of 4 moles of H2 from 1 mole of glucose. The major fermentation by-products in the liquid effluent were acetate and butyrate. The reactor rapidly (within 60-72 h) became clogged with biomass, requiring manual cleaning of the system. In order to make long-term operation of the reactor feasible, biofilm accumulation in the reactor will need to be controlled through some process such as backwashing. These tests using an unsaturated flow reactor demonstrate the feasibility of the process to produce high H2 gas concentrations in a trickle-bed type of reactor. A likely application of this reactor technology could be H2 gas recovery from pre-treatment of high carbohydrate-containing wastewaters.

Fail-safe reactivity compensation method for a nuclear reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nygaard, Erik T.; Angelo, Peter L.; Aase, Scott B.

The present invention relates generally to the field of compensation methods for nuclear reactors and, in particular to a method for fail-safe reactivity compensation in solution-type nuclear reactors. In one embodiment, the fail-safe reactivity compensation method of the present invention augments other control methods for a nuclear reactor. In still another embodiment, the fail-safe reactivity compensation method of the present invention permits one to control a nuclear reaction in a nuclear reactor through a method that does not rely on moving components into or out of a reactor core, nor does the method of the present invention rely on themore » constant repositioning of control rods within a nuclear reactor in order to maintain a critical state.« less

HORIZONTAL BOILING REACTOR SYSTEM

DOEpatents

Treshow, M.

1958-11-18

Reactors of the boiling water type are described wherein water serves both as the moderator and coolant. The reactor system consists essentially of a horizontal pressure vessel divided into two compartments by a weir, a thermal neutronic reactor core having vertical coolant passages and designed to use water as a moderator-coolant posltioned in one compartment, means for removing live steam from the other compartment and means for conveying feed-water and water from the steam compartment to the reactor compartment. The system further includes auxiliary apparatus to utilize the steam for driving a turbine and returning the condensate to the feed-water inlet of the reactor. The entire system is designed so that the reactor is self-regulating and has self-limiting power and self-limiting pressure features.

Low-power lead-cooled fast reactor loaded with MOX-fuel

NASA Astrophysics Data System (ADS)

Sitdikov, E. R.; Terekhova, A. M.

2017-01-01

Fast reactor for the purpose of implementation of research, education of undergraduate and doctoral students in handling innovative fast reactors and training specialists for atomic research centers and nuclear power plants (BRUTs) was considered. Hard neutron spectrum achieved in the fast reactor with compact core and lead coolant. Possibility of prompt neutron runaway of the reactor is excluded due to the low reactivity margin which is less than the effective fraction of delayed neutrons. The possibility of using MOX fuel in the BRUTs reactor was examined. The effect of Keff growth connected with replacement of natural lead coolant to 208Pb coolant was evaluated. The calculations and reactor core model were performed using the Serpent Monte Carlo code.

Extension of the TRANSURANUS burnup model to heavy water reactor conditions

NASA Astrophysics Data System (ADS)

Lassmann, K.; Walker, C. T.; van de Laar, J.

1998-06-01

The extension of the light water reactor burnup equations of the TRANSURANUS code to heavy water reactor conditions is described. Existing models for the fission of 235U and the buildup of plutonium in a heavy water reactor are evaluated. In order to overcome the limitations of the frequently used RADAR model at high burnup, a new model is presented. After verification against data for the radial distributions of Xe, Cs, Nd and Pu from electron probe microanalysis, the model is used to analyse the formation of the high burnup structure in a heavy water reactor. The new model allows the analysis of light water reactor fuel rod designs at high burnup in the OECD Halden Heavy Water Reactor.

METHOD FOR SENSING DEGREE OF FLUIDIZATION IN FLUIDIZED BED

DOEpatents

Levey, R.P. Jr.; Fowler, A.H.

1961-12-12

A method is given for detecting, indicating, and controlling the degree of fluidization in a fluid-bed reactor into which powdered material is fed. The method comprises admitting of gas into the reactor, inserting a springsupported rod into the powder bed of the reactor, exciting the rod to vibrate at its resonant frequency, deriving a signal responsive to the amplitude of vibi-ation of the rod and spring, the signal being directiy proportional to the rate of flow of the gas through the reactor, displaying the signal to provide an indication of the degree of fluidization within the reactor, and controlling the rate of gas flow into the reactor until said signal stabilizes at a constant value to provide substantially complete fluidization within the reactor. (AEC)

Fuel Cycle Performance of Thermal Spectrum Small Modular Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Worrall, Andrew; Todosow, Michael

2016-01-01

Small modular reactors may offer potential benefits, such as enhanced operational flexibility. However, it is vital to understand the holistic impact of small modular reactors on the nuclear fuel cycle and fuel cycle performance. The focus of this paper is on the fuel cycle impacts of light water small modular reactors in a once-through fuel cycle with low-enriched uranium fuel. A key objective of this paper is to describe preliminary reactor core physics and fuel cycle analyses conducted in support of the U.S. Department of Energy Office of Nuclear Energy Fuel Cycle Options Campaign. Challenges with small modular reactors include:more » increased neutron leakage, fewer assemblies in the core (and therefore fewer degrees of freedom in the core design), complex enrichment and burnable absorber loadings, full power operation with inserted control rods, the potential for frequent load-following operation, and shortened core height. Each of these will impact the achievable discharge burn-up in the reactor and the fuel cycle performance. This paper summarizes the results of an expert elicitation focused on developing a list of the factors relevant to small modular reactor fuel, core, and operation that will impact fuel cycle performance. Preliminary scoping analyses were performed using a regulatory-grade reactor core simulator. The hypothetical light water small modular reactor considered in these preliminary scoping studies is a cartridge type one-batch core with 4.9% enrichment. Some core parameters, such as the size of the reactor and general assembly layout, are similar to an example small modular reactor concept from industry. The high-level issues identified and preliminary scoping calculations in this paper are intended to inform on potential fuel cycle impacts of one-batch thermal spectrum SMRs. In particular, this paper highlights the impact of increased neutron leakage and reduced number of batches on the achievable burn-up of the reactor. Fuel cycle performance metrics for a small modular reactor are compared to a conventional three-batch light water reactor in the following areas: nuclear waste management, environmental impact, and resource utilization. Metrics performance for a small modular reactor are degraded for mass of spent nuclear fuel and high level waste disposed, mass of depleted uranium disposed, land use per energy generated, and carbon emission per energy generated« less

Aerosol reactor production of uniform submicron powders

NASA Technical Reports Server (NTRS)

Flagan, Richard C. (Inventor); Wu, Jin J. (Inventor)

1991-01-01

A method of producing submicron nonagglomerated particles in a single stage reactor includes introducing a reactant or mixture of reactants at one end while varying the temperature along the reactor to initiate reactions at a low rate. As homogeneously small numbers of seed particles generated in the initial section of the reactor progress through the reactor, the reaction is gradually accelerated through programmed increases in temperature along the length of the reactor to promote particle growth by chemical vapor deposition while minimizing agglomerate formation by maintaining a sufficiently low number concentration of particles in the reactor such that coagulation is inhibited within the residence time of particles in the reactor. The maximum temperature and minimum residence time is defined by a combination of temperature and residence time that is necessary to bring the reaction to completion. In one embodiment, electronic grade silane and high purity nitrogen are introduced into the reactor and temperatures of approximately 770.degree. K. to 1550.degree. K. are employed. In another embodiment silane and ammonia are employed at temperatures from 750.degree. K. to 1800.degree. K.

Improvement of anaerobic digestion performance by continuous nitrogen removal with a membrane contactor treating a substrate rich in ammonia and sulfide.

PubMed

Lauterböck, B; Nikolausz, M; Lv, Z; Baumgartner, M; Liebhard, G; Fuchs, W

2014-04-01

The effect of reduced ammonia levels on anaerobic digestion was investigated. Two reactors were fed with slaughterhouse waste, one with a hollow fiber membrane contractor for ammonia removal and one without. Different organic loading rates (OLR) and free ammonia and sulfide concentrations were investigated. In the reactor with the membrane contactor, the NH4-N concentration was reduced threefold. At a moderate OLR (3.1 kg chemical oxygen demand - COD/m(3)/d), this reactor performed significantly better than the reference reactor. At high OLR (4.2 kg COD/m(3)/d), the reference reactor almost stopped producing methane (0.01 Nl/gCOD). The membrane reactor also showed a stable process with a methane yield of 0.23 Nl/g COD was achieved. Both reactors had predominantly a hydrogenotrophic microbial consortium, however in the membrane reactor the genus Methanosaeta (acetoclastic) was also detected. In general, all relevant parameters and the methanogenic consortium indicated improved anaerobic digestion of the reactor with the membrane. Copyright © 2014 Elsevier Ltd. All rights reserved.

Control console replacement at the WPI Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-01-01

With partial funding from the Department of Energy (DOE) University Reactor Instrumentation Upgrade Program (DOE Grant No. DE-FG02-90ER12982), the original control console at the Worcester Polytechnic Institute (WPI) Reactor has been replaced with a modern system. The new console maintains the original design bases and functionality while utilizing current technology. An advanced remote monitoring system has been added to augment the educational capabilities of the reactor. Designed and built by General Electric in 1959, the open pool nuclear training reactor at WPI was one of the first such facilities in the nation located on a university campus. Devoted to undergraduatemore » use, the reactor and its related facilities have been since used to train two generations of nuclear engineers and scientists for the nuclear industry. The reactor power level was upgraded from 1 to 10 kill in 1969, and its operating license was renewed for 20 years in 1983. In 1988, the reactor was converted to low enriched uranium. The low power output of the reactor and ergonomic facility design make it an ideal tool for undergraduate nuclear engineering education and other training.« less

Aerosol reactor production of uniform submicron powders

DOEpatents

Flagan, Richard C.; Wu, Jin J.

1991-02-19

A method of producing submicron nonagglomerated particles in a single stage reactor includes introducing a reactant or mixture of reactants at one end while varying the temperature along the reactor to initiate reactions at a low rate. As homogeneously small numbers of seed particles generated in the initial section of the reactor progress through the reactor, the reaction is gradually accelerated through programmed increases in temperature along the length of the reactor to promote particle growth by chemical vapor deposition while minimizing agglomerate formation by maintaining a sufficiently low number concentration of particles in the reactor such that coagulation is inhibited within the residence time of particles in the reactor. The maximum temperature and minimum residence time is defined by a combination of temperature and residence time that is necessary to bring the reaction to completion. In one embodiment, electronic grade silane and high purity nitrogen are introduced into the reactor and temperatures of approximately 770.degree. K. to 1550.degree. K. are employed. In another embodiment silane and ammonia are employed at temperatures from 750.degree. K. to 1800.degree. K.

Oxidative coupling of methane using inorganic membrane reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Y.H.; Moser, W.R.; Dixon, A.G.

1995-12-31

The goal of this research is to improve the oxidative coupling of methane in a catalytic inorganic membrane reactor. A specific target is to achieve conversion of methane to C{sub 2} hydrocarbons at very high selectivity and relatively higher yields than in fixed bed reactors by controlling the oxygen supply through the membrane. A membrane reactor has the advantage of precisely controlling the rate of delivery of oxygen to the catalyst. This facility permits balancing the rate of oxidation and reduction of the catalyst. In addition, membrane reactors minimize the concentration of gas phase oxygen thus reducing non selective gasmore » phase reactions, which are believed to be a main route for formation of CO{sub x} products. Such gas phase reactions are a cause for decreased selectivity in oxidative coupling of methane in conventional flow reactors. Membrane reactors could also produce higher product yields by providing better distribution of the reactant gases over the catalyst than the conventional plug flow reactors. Modeling work which aimed at predicting the observed experimental trends in porous membrane reactors was also undertaken in this research program.« less

Stimulation of the hydrolytic stage for biogas production from cattle manure in an electrochemical bioreactor.

PubMed

Samani, Saeed; Abdoli, Mohammad Ali; Karbassi, Abdolreza; Amin, Mohammad Mehdi

Electrical current in the hydrolytic phase of the biogas process might affect biogas yield. In this study, four 1,150 mL single membrane-less chamber electrochemical bioreactors, containing two parallel titanium plates were connected to the electrical source with voltages of 0, -0.5, -1 and -1.5 V, respectively. Reactor 1 with 0 V was considered as a control reactor. The trend of biogas production was precisely checked against pH, oxidation reduction potential and electrical power at a temperature of 37 ± 0.5°C amid cattle manure as substrate for 120 days. Biogas production increased by voltage applied to Reactors 2 and 3 when compared with the control reactor. In addition, the electricity in Reactors 2 and 3 caused more biogas production than Reactor 4. Acetogenic phase occurred more quickly in Reactor 3 than in the other reactors. The obtained results from Reactor 4 were indicative of acidogenic domination and its continuous behavior under electrical stimulation. The results of the present investigation clearly revealed that phasic electrical current could enhance the efficiency of biogas production.

Comparative study between single core model and detail core model of CFD modelling on reactor core cooling behaviour

NASA Astrophysics Data System (ADS)

Darmawan, R.

2018-01-01

Nuclear power industry is facing uncertainties since the occurrence of the unfortunate accident at Fukushima Daiichi Nuclear Power Plant. The issue of nuclear power plant safety becomes the major hindrance in the planning of nuclear power program for new build countries. Thus, the understanding of the behaviour of reactor system is very important to ensure the continuous development and improvement on reactor safety. Throughout the development of nuclear reactor technology, investigation and analysis on reactor safety have gone through several phases. In the early days, analytical and experimental methods were employed. For the last four decades 1D system level codes were widely used. The continuous development of nuclear reactor technology has brought about more complex system and processes of nuclear reactor operation. More detailed dimensional simulation codes are needed to assess these new reactors. Recently, 2D and 3D system level codes such as CFD are being explored. This paper discusses a comparative study on two different approaches of CFD modelling on reactor core cooling behaviour.

Void effect analysis of Pb-208 of fast reactors with modified CANDLE burn-up scheme

DOE Office of Scientific and Technical Information (OSTI.GOV)

Widiawati, Nina, E-mail: nina-widiawati28@yahoo.com; Su’ud, Zaki, E-mail: szaki@fi.itb.ac.id

Void effect analysis of Pb-208 as coolant of fast reactors with modified candle burn-up scheme has been conducted. Lead cooled fast reactor (LFR) is one of the fourth-generation reactor designs. The reactor is designed with a thermal power output of 500 MWt. Modified CANDLE burn-up scheme allows the reactor to have long life operation by supplying only natural uranium as fuel cycle input. This scheme introducing discrete region, the fuel is initially put in region 1, after one cycle of 10 years of burn up it is shifted to region 2 and region 1 is filled by fresh natural uraniummore » fuel. The reactor is designed for 100 years with 10 regions arranged axially. The results of neutronic calculation showed that the void coefficients ranged from −0.6695443 % at BOC to −0.5273626 % at EOC for 500 MWt reactor. The void coefficients of Pb-208 more negative than Pb-nat. The results showed that the reactors with Pb-208 coolant have better level of safety than Pb-nat.« less

Five Lectures on Nuclear Reactors Presented at Cal Tech

DOE R&D Accomplishments Database

Weinberg, Alvin M.

1956-02-10

The basic issues involved in the physics and engineering of nuclear reactors are summarized. Topics discussed include theory of reactor design, technical problems in power reactors, physical problems in nuclear power production, and future developments in nuclear power. (C.H.)

10 CFR 2.102 - Administrative review of application.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Director, Office of Nuclear Reactor Regulation, Director, Office of New Reactors, Director, Office of...) The Director, Office of Nuclear Reactor Regulation, Director, Office of New Reactors, Director, Office... Energy NUCLEAR REGULATORY COMMISSION AGENCY RULES OF PRACTICE AND PROCEDURE Procedure for Issuance...

10 CFR 2.102 - Administrative review of application.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Director, Office of Nuclear Reactor Regulation, Director, Office of New Reactors, Director, Office of...) The Director, Office of Nuclear Reactor Regulation, Director, Office of New Reactors, Director, Office... Energy NUCLEAR REGULATORY COMMISSION AGENCY RULES OF PRACTICE AND PROCEDURE Procedure for Issuance...

Proceedings of the 1992 topical meeting on advances in reactor physics. Volume 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-04-01

This document, Volume 2, presents proceedings of the 1992 Topical Meeting on Advances in Reactor Physics on March 8--11, 1992 at Charleston, SC. Session topics were as follows: Transport Theory; Fast Reactors; Plant Analyzers; Integral Experiments/Measurements & Analysis; Core Computational Systems; Reactor Physics; Monte Carlo; Safety Aspects of Heavy Water Reactors; and Space-Time Core Kinetics. The individual reports have been cataloged separately. (FI)

Navy Nuclear-Powered Surface Ships: Background, Issues, and Options for Congress

DTIC Science & Technology

2010-06-10

scale pressurized water reactors suitable for destroyer-sized vessels or for alternative nuclear power systems using thorium liquid salt technology...or to design a new reactor type potentially using a thorium liquid salt reactor developed for maritime use. The committee recommends an increase of...either using a pressurized water reactor or a thorium liquid salt reactor . (Page 158) Senate The Senate Armed Services Committee, in its report

Reactor monitoring using antineutrino detectors

NASA Astrophysics Data System (ADS)

Bowden, N. S.

2011-08-01

Nuclear reactors have served as the antineutrino source for many fundamental physics experiments. The techniques developed by these experiments make it possible to use these weakly interacting particles for a practical purpose. The large flux of antineutrinos that leaves a reactor carries information about two quantities of interest for safeguards: the reactor power and fissile inventory. Measurements made with antineutrino detectors could therefore offer an alternative means for verifying the power history and fissile inventory of a reactor as part of International Atomic Energy Agency (IAEA) and/or other reactor safeguards regimes. Several efforts to develop this monitoring technique are underway worldwide.

CONVECTION REACTOR

DOEpatents

Hammond, R.P.; King, L.D.P.

1960-03-22

An homogeneous nuclear power reactor utilizing convection circulation of the liquid fuel is proposed. The reactor has an internal heat exchanger looated in the same pressure vessel as the critical assembly, thereby eliminating necessity for handling the hot liquid fuel outside the reactor pressure vessel during normal operation. The liquid fuel used in this reactor eliminates the necessity for extensive radiolytic gas rocombination apparatus, and the reactor is resiliently pressurized and, without any movable mechanical apparatus, automatically regulates itself to the condition of criticality during moderate variations in temperature snd pressure and shuts itself down as the pressure exceeds a predetermined safe operating value.

Chip-based device for parallel sorting, amplification, detection, and identification of nucleic acid subsequences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beer, Neil Reginald; Colston, Jr, Billy W.

An apparatus for chip-based sorting, amplification, detection, and identification of a sample having a planar substrate. The planar substrate is divided into cells. The cells are arranged on the planar substrate in rows and columns. Electrodes are located in the cells. A micro-reactor maker produces micro-reactors containing the sample. The micro-reactor maker is positioned to deliver the micro-reactors to the planar substrate. A microprocessor is connected to the electrodes for manipulating the micro-reactors on the planar substrate. A detector is positioned to interrogate the sample contained in the micro-reactors.

Design and evaluation of experimental ceramic automobile thermal reactors

NASA Technical Reports Server (NTRS)

Stone, P. L.; Blankenship, C. P.

1974-01-01

The paper summarizes the results obtained in an exploratory evaluation of ceramics for automobile thermal reactors. Candidate ceramic materials were evaluated in several reactor designs using both engine dynamometer and vehicle road tests. Silicon carbide contained in a corrugated metal support structure exhibited the best performance, lasting 1100 hours in engine dynamometer tests and for more than 38,600 kilimeters (24,000 miles) in vehicle road tests. Although reactors containing glass-ceramic components did not perform as well as silicon carbide, the glass-ceramics still offer good potential for reactor use with improved reactor designs.

Design and evaluation of experimental ceramic automobile thermal reactors

NASA Technical Reports Server (NTRS)

Stone, P. L.; Blankenship, C. P.

1974-01-01

The results obtained in an exploratory evaluation of ceramics for automobile thermal reactors are summarized. Candidate ceramic materials were evaluated in several reactor designs by using both engine-dynamometer and vehicle road tests. Silicon carbide contained in a corrugated-metal support structure exhibited the best performance, lasting 1100 hr in engine-dynamometer tests and more than 38,600 km (24000 miles) in vehicle road tests. Although reactors containing glass-ceramic components did not perform as well as those containing silicon carbide, the glass-ceramics still offer good potential for reactor use with improved reactor designs.

On Study of Application of Micro-reactor in Chemistry and Chemical Field

NASA Astrophysics Data System (ADS)

Zhang, Yunshen

2018-02-01

Serving as a micro-scale chemical reaction system, micro-reactor is characterized by high heat transfer efficiency and mass transfer, strictly controlled reaction time and good safety performance; compared with the traditional mixing reactor, it can effectively shorten reaction time by virtue of these advantages and greatly enhance the chemical reaction conversion rate. However, problems still exist in the process where micro-reactor is used for production in chemistry and chemical field, and relevant researchers are required to optimize and perfect the performance of micro-reactor. This paper analyzes specific application of micro-reactor in chemistry and chemical field.

The results of systems tests of the 500 kV busbar controllable shunting reactor in the Tavricheskaya substation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gusev, S. I.; Karpov, V. N.; Kiselev, A. N.

2009-09-15

The results of systems tests of the 500 kV busbar magnetization-controllable shunting reactor (CSR), set up in the Tavricheskaya substation, including measurements of the quality of the electric power, the harmonic composition of the network currents of the reactor for different values of the reactive power consumed, the determination of the regulating characteristics of the reactor, the speed of response of the shunting reactor in the current and voltage stabilization modes, and also the operation of the reactor under dynamic conditions for different perturbations, are presented. The results obtained are analyzed.