10 CFR 76.66 - Expiration and termination of certificates.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 76.66 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS... diffusion plants and other activities authorized under the certificate. (c) If the Corporation does not... specified in the existing certificate, terminate operation of the gaseous diffusion plants. [59 FR 48960...

10 CFR 76.66 - Expiration and termination of certificates.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 76.66 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS... diffusion plants and other activities authorized under the certificate. (c) If the Corporation does not... specified in the existing certificate, terminate operation of the gaseous diffusion plants. [59 FR 48960...

Analysis and evalaution in the production process and equipment area of the low-cost solar array project. [including modifying gaseous diffusion and using ion implantation

NASA Technical Reports Server (NTRS)

Goldman, H.; Wolf, M.

1979-01-01

The manufacturing methods for photovoltaic solar energy utilization are assessed. Economic and technical data on the current front junction formation processes of gaseous diffusion and ion implantation are presented. Future proposals, including modifying gaseous diffusion and using ion implantation, to decrease the cost of junction formation are studied. Technology developments in current processes and an economic evaluation of the processes are included.

Uncovering Implicit Assumptions: A Large-Scale Study on Students' Mental Models of Diffusion

ERIC Educational Resources Information Center

Stains, Marilyne; Sevian, Hannah

2015-01-01

Students' mental models of diffusion in a gas phase solution were studied through the use of the Structure and Motion of Matter (SAMM) survey. This survey permits identification of categories of ways students think about the structure of the gaseous solute and solvent, the origin of motion of gas particles, and trajectories of solute particles in…

Simulation of gaseous diffusion in partially saturated porous media under variable gravity with lattice Boltzmann methods

NASA Technical Reports Server (NTRS)

Chau, Jessica Furrer; Or, Dani; Sukop, Michael C.; Steinberg, S. L. (Principal Investigator)

2005-01-01

Liquid distributions in unsaturated porous media under different gravitational accelerations and corresponding macroscopic gaseous diffusion coefficients were investigated to enhance understanding of plant growth conditions in microgravity. We used a single-component, multiphase lattice Boltzmann code to simulate liquid configurations in two-dimensional porous media at varying water contents for different gravity conditions and measured gas diffusion through the media using a multicomponent lattice Boltzmann code. The relative diffusion coefficients (D rel) for simulations with and without gravity as functions of air-filled porosity were in good agreement with measured data and established models. We found significant differences in liquid configuration in porous media, leading to reductions in D rel of up to 25% under zero gravity. The study highlights potential applications of the lattice Boltzmann method for rapid and cost-effective evaluation of alternative plant growth media designs under variable gravity.

Update on Advection-Diffusion Purge Flow Model

NASA Technical Reports Server (NTRS)

Brieda, Lubos

2015-01-01

Gaseous purge is commonly used in sensitive spacecraft optical or electronic instruments to prevent infiltration of contaminants and/or water vapor. Typically, purge is sized using simplistic zero-dimensional models that do not take into account instrument geometry, surface effects, and the dependence of diffusive flux on the concentration gradient. For this reason, an axisymmetric computational fluid dynamics (CFD) simulation was recently developed to model contaminant infiltration and removal by purge. The solver uses a combined Navier-Stokes and Advection-Diffusion approach. In this talk, we report on updates in the model, namely inclusion of a particulate transport model.

Assessment of Remote Sensing Technologies for Location of Hydrogen and Helium Leaks

NASA Technical Reports Server (NTRS)

Sellar, R. Glenn; Wang, Danli

2000-01-01

The objective of this initial phase of this research effort is to: 1) Evaluate remote sensing technologies for location of leaks of gaseous molecular hydrogen (H2) and gaseous helium (He) in air, for space transportation applications; and 2) Develop a diffusion model that predicts concentration of H2 or He gas as a function of leak rate and distance from the leak.

Diffusion coefficients significant in modeling the absorption rate of carbon dioxide into aqueous blends of N-methyldiethanolamine and diethanolamine and of hydrogen sulfide into aqueous N-methyldiethanolamine

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

Adams, M.E.; Marshall, T.L.; Rowley, R.L.

1998-07-01

Absorption rates of gaseous CO{sub 2} into aqueous blends of N-methyldiethanolamine (MDEA) and diethanolamine (DEA) and of gaseous H{sub 2}S into aqueous MDEA were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. A numerical model for absorption, diffusion, and reaction of CO{sub 2} and H{sub 2}S in blends of MDEA, DEA, and water was developed. The model was used to regress diffusion coefficients of bicarbonate, carbamate, and MDEAH{sub 2}CO{sub 3} for the case of CO{sub 2} absorption and of bisulfide ion for the case of H{sub 2}S absorption from measured absorption rates. CO{sub 2} absorptionmore » rates and diffusion coefficients of bicarbonate, carbamate, and MDEAH{sub 2}CO{sub 3} were obtained at 298.2 K and 318.2 K in aqueous solutions containing 50 mass % total amine at DEA:MDEA mole ratios of 1:20, 1:4, 1L3, and 2:3. H{sub 2}S absorption rates and diffusion coefficients of bisulfide ion were obtained at 298.2 K and 318.2 K in aqueous solutions containing 20, 35, and 50 mass % MDEA.« less

Regression rate study of porous axial-injection, endburning hybrid fuel grains

NASA Astrophysics Data System (ADS)

Hitt, Matthew A.

This experimental and theoretical work examines the effects of gaseous oxidizer flow rates and pressure on the regression rates of porous fuels for hybrid rocket applications. Testing was conducted using polyethylene as the porous fuel and both gaseous oxygen and nitrous oxide as the oxidizer. Nominal test articles were tested using 200, 100, 50, and 15 micron fuel pore sizes. Pressures tested ranged from atmospheric to 1160 kPa for the gaseous oxygen tests and from 207 kPa to 1054 kPa for the nitrous oxide tests, and oxidizer injection velocities ranged from 35 m/s to 80 m/s for the gaseous oxygen tests and from 7.5 m/s to 16.8 m/s for the nitrous oxide tests. Regression rates were determined using pretest and posttest length measurements of the solid fuel. Experimental results demonstrated that the regression rate of the porous axial-injection, end-burning hybrid was a function of the chamber pressure, as opposed to the oxidizer mass flux typical in conventional hybrids. Regression rates ranged from approximately 0.75 mm/s at atmospheric pressure to 8.89 mm/s at 1160 kPa for the gaseous oxygen tests and 0.21 mm/s at 207 kPa to 1.44 mm/s at 1054 kPa for the nitrous oxide tests. The analytical model was developed based on a standard ablative model modified to include oxidizer flow through the grain. The heat transfer from the flame was primarily modeled using an empirically determined flame coefficient that included all heat transfer mechanisms in one term. An exploratory flame model based on the Granular Diffusion Flame model used for solid rocket motors was also adapted for comparison with the empirical flame coefficient. This model was then evaluated quantitatively using the experimental results of the gaseous oxygen tests as well as qualitatively using the experimental results of the nitrous oxide tests. The model showed agreement with the experimental results indicating it has potential for giving insight into the flame structure in this motor configuration. Results from the model suggested that both kinetic and diffusion processes could be relevant to the combustion depending on the chamber pressure.

POLUTE. Forest Air Pollutant Uptake Model

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

Murphy, C.E. Jr.; Sinclair, T.R.

1992-02-13

POLUTE is a computer model designed to estimate the uptake of air pollutants by forests. The model utilizes submodels to describe atmospheric diffusion immediately above and within the canopy, and into the sink areas within or on the trees. The program implementing the model is general and can be used, with only minor changes, for any gaseous pollutant. The model provides an estimate describing the response of the vegetarian-atmosphere system to the environment as related to three types of processes: atmospheric diffusion, diffusion near and inside the absorbing plant, and the physical and chemical processes at the sink on ormore » within the plant.« less

Favorite Demonstrations: Gaseous Diffusion: A Demonstration of Graham's Law.

ERIC Educational Resources Information Center

Kauffman, George B.; Ebner, Ronald D.

1985-01-01

Describes a demonstration in which gaseous ammonia and hydrochloric acid are used to illustrate rates of diffusion (Graham's Law). Simple equipment needed for the demonstration include a long tube, rubber stoppes, and cotton. Two related demonstrations are also explained. (DH)

Gaseous diffusion system

DOEpatents

Garrett, George A.; Shacter, John

1978-01-01

1. A gaseous diffusion system comprising a plurality of diffusers connected in cascade to form a series of stages, each of said diffusers having a porous partition dividing it into a high pressure chamber and a low pressure chamber, and means for combining a portion of the enriched gas from a succeeding stage with a portion of the enriched gas from the low pressure chamber of each stage and feeding it into one extremity of the high pressure chamber thereof.

10 CFR 76.1 - Purpose.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Purpose. 76.1 Section 76.1 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.1 Purpose. (a) This... Paducah Gaseous Diffusion Plants located in Piketon, Ohio, and Paducah, Kentucky, respectively, that are...

10 CFR 76.60 - Regulatory requirements which apply.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Regulatory requirements which apply. 76.60 Section 76.60 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification... requirements for certification of the Corporation for operation of the gaseous diffusion plants: (a) The...

10 CFR 76.1 - Purpose.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Purpose. 76.1 Section 76.1 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.1 Purpose. (a) This... Paducah Gaseous Diffusion Plants located in Piketon, Ohio, and Paducah, Kentucky, respectively, that are...

10 CFR 76.1 - Purpose.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Purpose. 76.1 Section 76.1 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.1 Purpose. (a) This... Paducah Gaseous Diffusion Plants located in Piketon, Ohio, and Paducah, Kentucky, respectively, that are...

10 CFR 76.1 - Purpose.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Purpose. 76.1 Section 76.1 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.1 Purpose. (a) This... Paducah Gaseous Diffusion Plants located in Piketon, Ohio, and Paducah, Kentucky, respectively, that are...

10 CFR 76.60 - Regulatory requirements which apply.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Regulatory requirements which apply. 76.60 Section 76.60 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification... requirements for certification of the Corporation for operation of the gaseous diffusion plants: (a) The...

10 CFR 76.1 - Purpose.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Purpose. 76.1 Section 76.1 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.1 Purpose. (a) This... Paducah Gaseous Diffusion Plants located in Piketon, Ohio, and Paducah, Kentucky, respectively, that are...

10 CFR 76.60 - Regulatory requirements which apply.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Regulatory requirements which apply. 76.60 Section 76.60 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification... requirements for certification of the Corporation for operation of the gaseous diffusion plants: (a) The...

10 CFR 76.60 - Regulatory requirements which apply.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Regulatory requirements which apply. 76.60 Section 76.60 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification... requirements for certification of the Corporation for operation of the gaseous diffusion plants: (a) The...

10 CFR 76.60 - Regulatory requirements which apply.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Regulatory requirements which apply. 76.60 Section 76.60 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification... requirements for certification of the Corporation for operation of the gaseous diffusion plants: (a) The...

Direct estimation of diffuse gaseous emissions from coal fires: current methods and future directions

USGS Publications Warehouse

Engle, Mark A.; Olea, Ricardo A.; O'Keefe, Jennifer M. K.; Hower, James C.; Geboy, Nicholas J.

2013-01-01

Coal fires occur in nature spontaneously, contribute to increases in greenhouse gases, and emit atmospheric toxicants. Increasing interest in quantifying coal fire emissions has resulted in the adaptation and development of specialized approaches and adoption of numerical modeling techniques. Overview of these methods for direct estimation of diffuse gas emissions from coal fires is presented in this paper. Here we take advantage of stochastic Gaussian simulation to interpolate CO2 fluxes measured using a dynamic closed chamber at the Ruth Mullins coal fire in Perry County, Kentucky. This approach allows for preparing a map of diffuse gas emissions, one of the two primary ways that gases emanate from coal fires, and establishing the reliability of the study both locally and for the entire fire. Future research directions include continuous and automated sampling to improve quantification of gaseous coal fire emissions.

A Study of the Gaseous Diffusion Plant for U$sup 235$ Enrichment; STUDI SU GLI IMPIANTI A DISSUFIONE GASOSA PER L'ARRICCHIMENTO DELL' U$sup 23$$sup 5$

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

Perona, G.

1959-04-01

The gaseous diffusion process for the enrichment of U/sup 235/ is discussed. The physical principles of the process, the cascades and selection of the pressures, temperatures, and barriers are described. The gaseous diffusion plant is discussed with a consideration of the preliminary calculation of the plant yields the diffusor, operating temperature, layout of the plants control, and cost analysis. The chemical properties of UF/sub 6/, its preparation and purification, and the transformation of UF/sub 6/ to UF/sub 4/ are reviewed. (J.S.R)

POLUTE; forest air pollutant uptake model. [IBM360,370; CSMP

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

Murphy, C.E.

POLUTE is a computer model designed to estimate the uptake of air pollutants by forests. The model utilizes submodels to describe atmospheric diffusion immediately above and within the canopy, and into the sink areas within or on the trees. The program implementing the model is general and can be used, with only minor changes, for any gaseous pollutant. The model provides an estimate describing the response of the vegetarian-atmosphere system to the environment as related to three types of processes: atmospheric diffusion, diffusion near and inside the absorbing plant, and the physical and chemical processes at the sink on ormore » within the plant.IBM360,370; CSMP; OS/370.« less

10 CFR 76.2 - Scope.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Scope. 76.2 Section 76.2 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.2 Scope. The regulations in this part apply only to those portions of the Portsmouth and Paducah Gaseous Diffusion Plants...

10 CFR 76.2 - Scope.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Scope. 76.2 Section 76.2 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.2 Scope. The regulations in this part apply only to those portions of the Portsmouth and Paducah Gaseous Diffusion Plants...

10 CFR 76.2 - Scope.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Scope. 76.2 Section 76.2 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.2 Scope. The regulations in this part apply only to those portions of the Portsmouth and Paducah Gaseous Diffusion Plants...

10 CFR 76.2 - Scope.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Scope. 76.2 Section 76.2 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.2 Scope. The regulations in this part apply only to those portions of the Portsmouth and Paducah Gaseous Diffusion Plants...

10 CFR 76.2 - Scope.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Scope. 76.2 Section 76.2 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.2 Scope. The regulations in this part apply only to those portions of the Portsmouth and Paducah Gaseous Diffusion Plants...

Navier-Stokes calculations for 3D gaseous fuel injection with data comparisons

NASA Technical Reports Server (NTRS)

Fuller, E. J.; Walters, R. W.

1991-01-01

Results from a computational study and experiments designed to further expand the knowledge of gaseous injection into supersonic cross-flows are presented. Experiments performed at Mach 6 included several cases of gaseous helium injection with low transverse angles and injection with low transverse angles coupled with a low yaw angle. Both experimental and computational data confirm that injector yaw has an adverse effect on the helium core decay rate. An array of injectors is found to give higher penetration into the freestream without loss of core injectant decay as compared to a single injector. Lateral diffusion plays a major role in lateral plume spreading, eddy viscosity, injectant plume, and injectant-freestream mixing. Grid refinement makes it possible to capture the gradients in the streamwise direction accurately and to vastly improve the data comparisons. Computational results for a refined grid are found to compare favorably with experimental data on injectant overall and core penetration provided laminar lateral diffusion was taken into account using the modified Baldwin-Lomax turbulence model.

Pore-scale lattice Boltzmann simulation of micro-gaseous flow considering surface diffusion effect

DOE PAGES

Wang, Junjian; Kang, Qinjun; Chen, Li; ...

2016-11-21

Some recent studies have shown that adsorbed gas and its surface diffusion have profound influence on micro-gaseous flow through organic pores in shale gas reservoirs. Here, a multiple-relaxation-time (MRT) LB model is adopted to estimate the apparent permeability of organic shale and a new boundary condition, which combines Langmuir adsorption theory with Maxwellian diffusive reflection boundary condition, is proposed to capture gas slip and surface diffusion of adsorbed gas. The simulation results match well with previous studies carried out using Molecular Dynamics (MD) and show that Maxwell slip boundary condition fails to characterize gas transport in the near wall regionmore » under the influence of the adsorbed gas. The total molar flux can be either enhanced or reduced depending on variations in adsorbed gas coverage and surface diffusion velocity. The effects of pore width, pressure as well as Langmuir properties on apparent permeability of methane transport in organic pores are further studied. It is found that the surface transport plays a significant role in determining the apparent permeability, and the variation of apparent permeability with pore size and pressure is affected by the adsorption and surface diffusion.« less

Correlation and prediction of gaseous diffusion coefficients.

NASA Technical Reports Server (NTRS)

Marrero, T. R.; Mason, E. A.

1973-01-01

A new correlation method for binary gaseous diffusion coefficients from very low temperatures to 10,000 K is proposed based on an extended principle of corresponding states, and having greater range and accuracy than previous correlations. There are two correlation parameters that are related to other physical quantities and that are predictable in the absence of diffusion measurements. Quantum effects and composition dependence are included, but high-pressure effects are not. The results are directly applicable to multicomponent mixtures.

DIFFUSIVE EXCHANGE OF GASEOUS POLYCYCLIC AROMATIC HYDROCARBONS AND POLYCHLORINATED BIPHENYLS ACROSS THE AIR-WATER INTERFACE OF THE CHESAPEAKE BAY. (R825245)

EPA Science Inventory

Dissolved and gas-phase concentrations of nine polycyclic aromatic hydrocarbons and 46 polychlorinated biphenyl congeners were measured at eight sites on the Chesapeake Bay at four different times of the year to estimate net diffusive air-water gas exchange rates. Gaseous PAHs ar...

Occupational radiation exposure experience: Paducah Gaseous Diffusion Plant

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

Baker, R.C.

1975-01-01

The potential for significant uranium exposure in gaseous diffusion plants is very low. The potential for significant radiation exposure in uranium hexafluoride manufacturing is very real. Exposures can be controlled to low levels only through the cooperation and commitment of facility management and operating personnel. Exposure control can be adequately monitored by a combination of air analyses, urinalyses, and measurements of internal deposition as obtained by the IVRML. A program based on control of air-borne uranium exposure has maintained the internal dose of the Paducah Gaseous Diffusion Plant workman to less than one-half the RPG dose to the lung (15more » rem/year) and probably to less than one-fourth that dose. (auth)« less

Preliminary study of PCBs in raccoons living on or near the Paducah Gaseous Diffusion Plant, Kentucky

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

Halbrook, Richard S.

2016-01-15

The “Ecological Monitoring at the Paducah Gaseous Diffusion Plant: Historical Evaluation and Guidelines for Future Monitoring” report (Halbrook, et al. 2007) recommended the raccoon as a species for study at the Paducah Gaseous Diffusion Plant (PGDP). This species was selected to fill data gaps in ecological resources and provide resource managers with knowledge that will be valuable in making decisions and implementing specific actions to safeguard ecological resources and reduce human exposure. The current paper reports results of a preliminary evaluation to establish protocols for collection of tissues and initial screening of polychlorinated biphenyls (PCBs) in raccoons collected near themore » PGDP. These data are useful in developing future more comprehensive studies.« less

Effect of lost charged particles on the breakdown characteristics of the gaseous electrical discharge in non-uniform axial electric field

NASA Astrophysics Data System (ADS)

Noori, H.; Ranjbar, A. H.

2017-10-01

The secondary emission coefficient is a valuable parameter for numerical modeling of the discharge process in gaseous insulation. A theoretical model has been developed to consider the effects of the radial electric field, non-uniformity of the axial electric field, and radial diffusion of charged particles on the secondary emission coefficient. In the model, a modified breakdown criterion is employed to determine the effective secondary electron emission, γeff. Using the geometry factor gi which is introduced based on the effect of radial diffusion of charged particles on the fraction of ions which arrive at the cathode, the geometry-independent term of γeff (Δi) was obtained as a function of the energy of the incident ions on the cathode. The results show that Δi is approximately a unique function of the ion energy for the ratios of d/R = 39, 50, 77, 115, and 200. It means that the considered mechanisms in the model are responsible for the deviation from Paschen's law.

Purging of a multilayer insulation with dacron tuft spacer by gas diffusion

NASA Technical Reports Server (NTRS)

Sumner, I. E.; Fisk, W. J.

1976-01-01

The time and purge gas usage required to purge a multilayer insulation (MLI) panel with gaseous helium by means of gas diffusion to obtain a condensable gas (nitrogen) concentration of less than 1 percent within the panel are stipulated. Two different, flat, rectangular MLI panels, one incorporating a butt joint, were constructed of of 11 double-aluminized Mylar (DAM) radiation shields separated by Dacron tuft spacers. The DAM/Dacron tuft concept is known commercially as Superfloc. The nitrogen gas concentration as a function of time within the MLI panel could be adequately predicted by using a simple, one dimensional gas diffusion model in which the boundary conditions at the edge of the MLI panel were time dependent. The time and purge gas usage required to achieve 1 percent nitrogen gas concentration within the MLI panel varied from 208 to 86 minutes and 34.1 to 56.5 MLI panel purge volumes, respectively, for gaseous helium purge rates from 10 to 40 MLI panel volumes per hour.

Carbon isotope exchange between gaseous CO2 and thin solution films: Artificial cave experiments and a complete diffusion-reaction model

NASA Astrophysics Data System (ADS)

Hansen, Maximilian; Scholz, Denis; Froeschmann, Marie-Louise; Schöne, Bernd R.; Spötl, Christoph

2017-08-01

Speleothem stable carbon isotope (δ13C) records provide important paleoclimate and paleo-environmental information. However, the interpretation of these records in terms of past climate or environmental change remains challenging because of various processes affecting the δ13C signals. A process that has only been sparsely discussed so far is carbon isotope exchange between the gaseous CO2 of the cave atmosphere and the dissolved inorganic carbon (DIC) contained in the thin solution film on the speleothem, which may be particularly important for strongly ventilated caves. Here we present a novel, complete reaction diffusion model describing carbon isotope exchange between gaseous CO2 and the DIC in thin solution films. The model considers all parameters affecting carbon isotope exchange, such as diffusion into, out of and within the film, the chemical reactions occurring within the film as well as the dependence of diffusion and the reaction rates on isotopic mass and temperature. To verify the model, we conducted laboratory experiments under completely controlled, cave-analogue conditions at three different temperatures (10, 20, 30 °C). We exposed thin (≈0.1 mm) films of a NaHCO3 solution with four different concentrations (1, 2, 5 and 10 mmol/l, respectively) to a nitrogen atmosphere containing a specific amount of CO2 (1000 and 3000 ppmV). The experimentally observed temporal evolution of the pH and δ13C values of the DIC is in good agreement with the model predictions. The carbon isotope exchange times in our experiments range from ca. 200 to ca. 16,000 s and strongly depend on temperature, film thickness, atmospheric pCO2 and the concentration of DIC. For low pCO2 (between 500 and 1000 ppmV, as for strongly ventilated caves), our time constants are substantially lower than those derived in a previous study, suggesting a potentially stronger influence of carbon isotope exchange on speleothem δ13C values. However, this process should only have an influence in case of very long drip intervals and slow precipitation rates.

Simulation of xenon, uranium vacancy and interstitial diffusion and grain boundary segregation in UO 2

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

Andersson, Anders D.; Tonks, Michael R.; Casillas, Luis

2014-10-31

In light water reactor fuel, gaseous fission products segregate to grain boundaries, resulting in the nucleation and growth of large intergranular fission gas bubbles. Based on the mechanisms established from density functional theory (DFT) and empirical potential calculations 1, continuum models for diffusion of xenon (Xe), uranium (U) vacancies and U interstitials in UO 2 have been derived for both intrinsic conditions and under irradiation. Segregation of Xe to grain boundaries is described by combining the bulk diffusion model with a model for the interaction between Xe atoms and three different grain boundaries in UO 2 ( Σ5 tilt, Σ5more » twist and a high angle random boundary),as derived from atomistic calculations. All models are implemented in the MARMOT phase field code, which is used to calculate effective Xe and U diffusivities as well as redistribution for a few simple microstructures.« less

DOE's Oak Ridge Site Kick Off Demolition of the K-27 Building

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

Cange, Sue; Rueter, Ken

2016-02-10

DOE's Oak Ridge Office of Environmental Management kicked off demolition of the K-27 Building this month, moving closer to fulfilling Vision 2016 — removal of all gaseous diffusion buildings from the site by year’s end. As the site's last uranium enrichment building falls, it will mark the first-ever demolition and cleanup of a gaseous diffusion complex anywhere.

Diffusion-based process for carbon dioxide uptake and isoprene emission in gaseous/aqueous two-phase photobioreactors by photosynthetic microorganisms.

PubMed

Bentley, Fiona K; Melis, Anastasios

2012-01-01

Photosynthesis for the generation of fuels and chemicals from cyanobacteria and microalgae offers the promise of a single host organism acting both as photocatalyst and processor, performing sunlight absorption and utilization, as well as CO(2) assimilation and conversion into product. However, there is a need to develop methods for generating, sequestering, and trapping such bio-products in an efficient and cost-effective manner that is suitable for industrial scale-up and exploitation. A sealed gaseous/aqueous two-phase photobioreactor was designed and applied for the photosynthetic generation of volatile isoprene (C(5)H(8)) hydrocarbons, which operates on the principle of spontaneous diffusion of CO(2) from the gaseous headspace into the microalgal or cyanobacterial-containing aqueous phase, followed by photosynthetic CO(2) assimilation and isoprene production by the transgenic microorganisms. Volatile isoprene hydrocarbons were emitted from the aqueous phase and were sequestered into the gaseous headspace. Periodic replacement (flushing) of the isoprene (C(5)H(8)) and oxygen (O(2)) content of the gaseous headspace with CO(2) allowed for the simultaneous harvesting of the photoproducts and replenishment of the CO(2) supply in the gaseous headspace. Reduction in practice of the gaseous/aqueous two-phase photobioreactor is offered in this work with a fed-batch and a semi-continuous culturing system using Synechocystis sp. PCC 6803 heterologously expressing the Pueraria montana (kudzu) isoprene synthase (IspS) gene. Constitutive isoprene production was observed over 192 h of experimentation, coupled with cyanobacterial biomass accumulation. The diffusion-based process in gaseous/aqueous two-phase photobioreactors has the potential to be applied to other high-value photosynthetically derived volatile molecules, emanating from a variety of photosynthetic microorganisms. Copyright © 2011 Wiley Periodicals, Inc.

Final Report: Seismic Hazard Assessment at the PGDP

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

Wang, Zhinmeng

2007-06-01

Selecting a level of seismic hazard at the Paducah Gaseous Diffusion Plant for policy considerations and engineering design is not an easy task because it not only depends on seismic hazard, but also on seismic risk and other related environmental, social, and economic issues. Seismic hazard is the main focus. There is no question that there are seismic hazards at the Paducah Gaseous Diffusion Plant because of its proximity to several known seismic zones, particularly the New Madrid Seismic Zone. The issues in estimating seismic hazard are (1) the methods being used and (2) difficulty in characterizing the uncertainties ofmore » seismic sources, earthquake occurrence frequencies, and ground-motion attenuation relationships. This report summarizes how input data were derived, which methodologies were used, and what the hazard estimates at the Paducah Gaseous Diffusion Plant are.« less

A novel enhanced diffusion sampler for collecting gaseous pollutants without air agitation.

PubMed

Pan, Xuelian; Zhuo, Shaojie; Zhong, Qirui; Chen, Yuanchen; Du, Wei; Cheng, Hefa; Wang, Xilong; Zeng, Eddy Y; Xing, Baoshan; Tao, Shu

2018-03-06

A novel enhanced diffusion sampler for collecting gaseous phase polycyclic aromatic hydrocarbons (PAHs) without air agitation is proposed. The diffusion of target compounds into a sampling chamber is facilitated by continuously purging through a closed-loop flow to create a large concentration difference between the ambient air and the air in the sampling chamber. A glass-fiber filter-based prototype was developed. It was demonstrated that the device could collect gaseous PAHs at a much higher rate (1.6 ± 1.4 L/min) than regular passive samplers, while the ambient air is not agitated. The prototype was also tested in both the laboratory and field for characterizing the concentration gradients over a short distance from the soil surface. The sampler has potential to be applied in other similar situations to characterize the concentration profiles of other chemicals.

Physics of Fresh Produce Safety: Role of Diffusion and Tissue Reaction in Sanitization of Leafy Green Vegetables with Liquid and Gaseous Ozone-Based Sanitizers.

PubMed

Shynkaryk, Mykola V; Pyatkovskyy, Taras; Mohamed, Hussein M; Yousef, Ahmed E; Sastry, Sudhir K

2015-12-01

Produce safety has received much recent attention, with the emphasis being largely on discovery of how microbes invade produce. However, the sanitization operation deserves more attention than it has received. The ability of a sanitizer to reach the site of pathogens is a fundamental prerequisite for efficacy. This work addresses the transport processes of ozone (gaseous and liquid) sanitizer for decontamination of leafy greens. The liquid sanitizer was ineffective against Escherichia coli K-12 in situations where air bubbles may be trapped within cavities. A model was developed for diffusion of sanitizer into the interior of produce. The reaction rate of ozone with the surface of a lettuce leaf was determined experimentally and was used in a numerical simulation to evaluate ozone concentrations within the produce and to determine the time required to reach different locations. For aqueous ozone, the penetration depth was limited to several millimeters by ozone self-decomposition due to the significant time required for diffusion. In contrast, gaseous sanitizer was able to reach a depth of 100 mm in several minutes without depletion in the absence of reaction with surfaces. However, when the ozone gas reacted with the produce surface, gas concentration was significantly affected. Simulation data were validated experimentally by measuring ozone concentrations at the bottom of a cylinder made of lettuce leaf. The microbiological test confirmed the relationship between ozone transport, its self-decomposition, reaction with surrounding materials, and the degree of inactivation of E. coli K-12. Our study shows that decontamination of fresh produce, through direct contact with the sanitizer, is more feasible with gaseous than with aqueous sanitizers. Therefore, sanitization during a high-speed washing process is effective only for decontaminating the wash water.

A model for estimating air-pollutant uptake by forests: calculation of absorption of sulfur dioxide from dispersed sources

Treesearch

C. E., Jr. Murphy; T. R. Sinclair; K. R. Knoerr

1977-01-01

The computer model presented in this paper is designed to estimate the uptake of air pollutants by forests. The model utilizes submodels to describe atmospheric diffusion immediately above and within the canopy, and into the sink areas within or on the trees. The program implementing the model is general and can be used with only minor changes for any gaseous pollutant...

DOE's Oak Ridge Site Kick Off Demolition of the K-27 Building

ScienceCinema

Cange, Sue; Rueter, Ken

2018-06-21

DOE's Oak Ridge Office of Environmental Management kicked off demolition of the K-27 Building this month, moving closer to fulfilling Vision 2016 — removal of all gaseous diffusion buildings from the site by year’s end. As the site's last uranium enrichment building falls, it will mark the first-ever demolition and cleanup of a gaseous diffusion complex anywhere.

Diffusion method of seperating gaseous mixtures

DOEpatents

Pontius, Rex B.

1976-01-01

A method of effecting a relatively large change in the relative concentrations of the components of a gaseous mixture by diffusion which comprises separating the mixture into heavier and lighter portions according to major fraction mass recycle procedure, further separating the heavier portions into still heavier subportions according to a major fraction mass recycle procedure, and further separating the lighter portions into still lighter subportions according to a major fraction equilibrium recycle procedure.

Fuel cell with interdigitated porous flow-field

DOEpatents

Wilson, Mahlon S.

1997-01-01

A polymer electrolyte membrane (PEM) fuel cell is formed with an improved system for distributing gaseous reactants to the membrane surface. A PEM fuel cell has an ionic transport membrane with opposed catalytic surfaces formed thereon and separates gaseous reactants that undergo reactions at the catalytic surfaces of the membrane. The fuel cell may also include a thin gas diffusion layer having first and second sides with a first side contacting at least one of the catalytic surfaces. A macroporous flow-field with interdigitated inlet and outlet reactant channels contacts the second side of the thin gas diffusion layer for distributing one of the gaseous reactants over the thin gas diffusion layer for transport to an adjacent one of the catalytic surfaces of the membrane. The porous flow field may be formed from a hydrophilic material and provides uniform support across the backside of the electrode assembly to facilitate the use of thin backing layers.

Fuel cell with interdigitated porous flow-field

DOEpatents

Wilson, M.S.

1997-06-24

A polymer electrolyte membrane (PEM) fuel cell is formed with an improved system for distributing gaseous reactants to the membrane surface. A PEM fuel cell has an ionic transport membrane with opposed catalytic surfaces formed thereon and separates gaseous reactants that undergo reactions at the catalytic surfaces of the membrane. The fuel cell may also include a thin gas diffusion layer having first and second sides with a first side contacting at least one of the catalytic surfaces. A macroporous flow-field with interdigitated inlet and outlet reactant channels contacts the second side of the thin gas diffusion layer for distributing one of the gaseous reactants over the thin gas diffusion layer for transport to an adjacent one of the catalytic surfaces of the membrane. The porous flow field may be formed from a hydrophilic material and provides uniform support across the backside of the electrode assembly to facilitate the use of thin backing layers. 9 figs.

Multiscale simulation of xenon diffusion and grain boundary segregation in UO₂

DOE PAGES

Andersson, David A.; Tonks, Michael R.; Casillas, Luis; ...

2015-07-01

In light water reactor fuel, gaseous fission products segregate to grain boundaries, resulting in the nucleation and growth of large intergranular fission gas bubbles. The segregation rate is controlled by diffusion of fission gas atoms through the grains and interaction with the boundaries. Based on the mechanisms established from earlier density functional theory (DFT) and empirical potential calculations, diffusion models for xenon (Xe), uranium (U) vacancies and U interstitials in UO₂ have been derived for both intrinsic (no irradiation) and irradiation conditions. Segregation of Xe to grain boundaries is described by combining the bulk diffusion model with a model formore » the interaction between Xe atoms and three different grain boundaries in UO₂ (Σ5 tilt, Σ5 twist and a high angle random boundary), as derived from atomistic calculations. The present model does not attempt to capture nucleation or growth of fission gas bubbles at the grain boundaries. The point defect and Xe diffusion and segregation models are implemented in the MARMOT phase field code, which is used to calculate effective Xe and U diffusivities as well as to simulate Xe redistribution for a few simple microstructures.« less

Four-component numerical simulation model of radiative convective interactions in large-scale oxygen-hydrogen turbulent fire balls

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

Surzhikov, S.T.

1996-12-31

Two-dimensional radiative gas dynamics model for numerical simulation of oxygen-hydrogen fire ball which may be generated by an explosion of a launch vehicle with cryogenic (LO{sub 2}-LH{sub 2}) fuel components is presented. The following physical-chemical processes are taken into account in the numerical model: and effective chemical reaction between the gaseous components (O{sub 2}-H{sub 2}) of the propellant, turbulent mixing and diffusion of the components, and radiative heat transfer. The results of numerical investigations of the following problems are presented: The influence of radiative heat transfer on fire ball gas dynamics during the first 13 sec after explosion, the effectmore » of the fuel gaseous components afterburning on fire ball gas dynamics, and the effect of turbulence on fire ball gas dynamics (in a framework of algebraic model of turbulent mixing).« less

Measurement of diffusion coefficients important in modeling the absorption rate of carbon dioxide into aqueous N-methyldiethanolamine

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

Rowley, R.L.; Adams, M.E.; Marshall, T.L.

1997-03-01

Natural gas processors use amine treating processes to remove the acid gases H{sub 2}S and CO{sub 2} from gas streams. Absorption rates of gaseous CO{sub 2} into aqueous N-methyldiethanolamine (MDEA) solutions were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. The absorption rate was found to be insensitive to the diffusion coefficient of CO{sub 2} in solution but very sensitive to the diffusion rate of bicarbonate and protonated MDEA ions. Evidence also suggested that chemical reaction equilibrium is rapid relative to diffusion. A numerical model was developed on the basis of these observations. The modelmore » was used to regress diffusion coefficients of bicarbonate and protonated amine, which must be equivalent by electroneutrality arguments, from measured absorption rates. Complete modeling of the absorption process also required data for the diffusion coefficient of MDEA in water. These were measured using a Taylor dispersion apparatus. CO{sub 2} absorption rates and diffusion coefficients of bicarbonate and protonated MDEA were obtained at 298.2 K and 318.2 K in solutions containing 20, 35, and 50 mass % MDEA in water.« less

Hydrogen adsorption and diffusion, and subcritical-crack growth in high strength steels and nickel base alloys

NASA Technical Reports Server (NTRS)

Wei, R. P.; Klier, K.; Simmons, G. W.; Chornet, E.

1973-01-01

Embrittlement, or the enhancement of crack growth by gaseous hydrogen in high strength alloys, is of primary interest in selecting alloys for various components in the space shuttle. Embrittlement is known to occur at hydrogen gas pressures ranging from fractions to several hundred atmospheres, and is most severe in the case of martensitic high strength steels. Kinetic information on subcritical crack growth in gaseous hydrogen is sparse at this time. Corroborative information on hydrogen adsorption and diffusion is inadequate to permit a clear determination of the rate controlling process and possible mechanism in hydrogen enhanced crack growth, and for estimating behavior over a range of temperatures and pressures. Therefore, coordinated studies of the kinetics of crack growth, and adsorption and diffusion of hydrogen, using identical materials, have been initiated. Comparable conditions of temperature and pressure will be used in the chemical and mechanical experiments. Inconel 718 alloy and 18Ni(200) maraging steel have been selected for these studies. Results from these studies are expected to provide not only a better understanding of the gaseous hydrogen embrittlement phenomenon itself, but also fundamental information on hydrogen adsorption and diffusion, and crack growth information that can be used directly for design.

Tc-99 Decontamination From Heat Treated Gaseous Diffusion Membrane -Phase I

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

Oji, L.; Wilmarth, B.; Restivo, M.

2017-03-13

Uranium gaseous diffusion cascades represent a significant environmental challenge to dismantle, containerize and dispose as low-level radioactive waste. Baseline technologies rely on manual manipulations involving direct access to technetium-contaminated piping and materials. There is a potential to utilize novel thermal decontamination technologies to remove the technetium and allow for on-site disposal of the very large uranium converters. Technetium entered these gaseous diffusion cascades as a hexafluoride complex in the same fashion as uranium. Technetium, as the isotope Tc-99, is an impurity that follows uranium in the first cycle of the Plutonium and Uranium Extraction (PUREX) process. The technetium speciation ormore » exact form in the gas diffusion cascades is not well defined. Several forms of Tc-99 compounds, mostly the fluorinated technetium compounds with varying degrees of volatility have been speculated by the scientific community to be present in these cascades. Therefore, there may be a possibility of using thermal desorption, which is independent of the technetium oxidation states, to perform an in situ removal of the technetium as a volatile species and trap the radionuclide on sorbent traps which could be disposed as low-level waste.« less

Apparatus and process for the separation of gases using supersonic expansion and oblique wave compression

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

VanOsdol, John G.

The disclosure provides an apparatus and method for gas separation through the supersonic expansion and subsequent deceleration of a gaseous stream. The gaseous constituent changes phase from the gaseous state by desublimation or condensation during the acceleration producing a collectible constituent, and an oblique shock diffuser decelerates the gaseous stream to a subsonic velocity while maintain the collectible constituent in the non-gaseous state. Following deceleration, the carrier gas and the collectible constituent at the subsonic velocity are separated by a separation means, such as a centrifugal, electrostatic, or impingement separator. In an embodiment, the gaseous stream issues from a combustionmore » process and is comprised of N.sub.2 and CO.sub.2.« less

Apparatus for diffusion separation

DOEpatents

Nierenberg, William A.; Pontius, Rex B.

1976-08-10

1. The method of testing the separation efficiency of porous permeable membranes which comprises causing a stream of a gaseous mixture to flow into contact with one face of a finely porous permeable membrane under such conditions that a major fraction of the mixture diffuses through the membrane, maintaining a rectangular cross section of the gaseous stream so flowing past said membrane, continuously recirculating the gas that diffuses through said membrane and continuously withdrawing the gas that does not diffuse through said membrane and maintaining the volume of said recirculating gas constant by continuously introducing into said continuously recirculating gas stream a mass of gas equivalent to that which is continuously withdrawn from said gas stream and comparing the concentrations of the light component in the entering gas, the withdrawn gas and the recirculated gas in order to determine the efficiency of said membrane.

Review of microfluidic cell culture devices for the control of gaseous microenvironments in vitro

NASA Astrophysics Data System (ADS)

Wu, H.-M.; Lee, T.-A.; Ko, P.-L.; Chiang, H.-J.; Peng, C.-C.; Tung, Y.-C.

2018-04-01

Gaseous microenvironments play important roles in various biological activities in vivo. However, it is challenging to precisely control gaseous microenvironments in vitro for cell culture due to the high diffusivity nature of gases. In recent years, microfluidics has paved the way for the development of new types of cell culture devices capable of manipulating cellular microenvironments, and provides a powerful tool for in vitro cell studies. This paper reviews recent developments of microfluidic cell culture devices for the control of gaseous microenvironments, and discusses the advantages and limitations of current devices. We conclude with suggestions for the future development of microfluidic cell culture devices for the control of gaseous microenvironments.

78 FR 65389 - United States Enrichment Corporation, Paducah Gaseous Diffusion Plant

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-31

..., USEC notified the NRC of its decision to permanently cease uranium enrichment activities at the PGDP... Accession Nos. ML13105A010 and ML13176A151, respectively. NRC's PDR: You may examine and purchase copies of... in Paducah, Kentucky, using the gaseous [[Page 65390

Strain-Rate-Free Diffusion Flames: Initiation, Properties, and Quenching

NASA Technical Reports Server (NTRS)

Fendell, Francis; Rungaldier, Harald; Gokoglu, Suleyman; Schultz, Donald

1997-01-01

For about a half century, the stabilization of a steady planar deflagration on a heat-sink-type flat-flame burner has been of extraordinary service for the theoretical modeling and diagnostic probing of combusting gaseous mixtures. However, most engineering devices and most unwanted fire involve the burning of initially unmixed reactants. The most vigorous burning of initially separated gaseous fuel and oxidizer is the diffusion flame. In this useful idealization (limiting case), the reactants are converted to product at a mathematically thin interface, so no interpenetration of fuel and oxidizer occurs. This limit is of practical importance because it often characterizes the condition of optimal performance (and sometimes environmentally objectionable operation) of a combustor. A steady planar diffusion flame is most closely approached in the laboratory in the counterflow apparatus. The utility of this simple-strain-rate flow for the modeling and probing of diffusion flames was noted by Pandya and Weinberg 35 years ago, though only in the last decade or so has its use become internationally common place. However, typically, as the strain rate a is reduced below about 20 cm(exp -1), and the diffusion-flame limit (reaction rate much faster than the flow rate) is approached, the burning is observed to become unstable in earth gravity. The advantageous steady planar flow is not available in the diffusion-flame limit in earth gravity. This is unfortunate because the typical spatial scale in a counterflow is (k/a)(sup 1/2), where k denotes a characteristic diffusion coefficient; thus, the length scale becomes large, and the reacting flow is particularly amenable to diagnostic probing, as the diffusion-flame limit is approached. The disruption of planar symmetry is owing the fact that, as the strain rate a decreases, the residence time (l/a) of the throughput in the counterflow burner increases. Observationally, when the residence time exceeds about 50 msec, the inevitably present convective (Rayleigh-Benard) instabilities, associated with hot-under-cold (flame-under-fresh-reactant) stratification of fluid in a gravitational field, have time to grow to finite amplitude during transit of the burner.

Laminar and Turbulent Gaseous Diffusion Flames. Appendix C

NASA Technical Reports Server (NTRS)

Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

2001-01-01

Recent measurements and predictions of the properties of homogeneous (gaseous) laminar and turbulent non-premixed (diffusion) flames are discussed, emphasizing results from both ground- and space-based studies at microgravity conditions. Initial considerations show that effects of buoyancy not only complicate the interpretation of observations of diffusion flames but at times mislead when such results are applied to the non-buoyant diffusion flame conditions of greatest practical interest. This behavior motivates consideration of experiments where effects of buoyancy are minimized; therefore, methods of controlling the intrusion of buoyancy during observations of non-premixed flames are described, considering approaches suitable for both normal laboratory conditions as well as classical microgravity techniques. Studies of laminar flames at low-gravity and microgravity conditions are emphasized in view of the computational tractability of such flames for developing methods of predicting flame structure as well as the relevance of such flames to more practical turbulent flames by exploiting laminar flamelet concepts.

Diffusional limits to the consumption of atmospheric methane by soils

USGS Publications Warehouse

Striegl, Robert G.

1993-01-01

Net transport of atmospheric gases into and out of soil systems is primarily controlled by diffusion along gas partial pressure gradients. Gas fluxes between soil and the atmosphere can therefore be estimated by a generalization of the equation for ordinary gaseous diffusion in porous unsaturated media. Consumption of CH4 by methylotrophic bacteria in the top several centimeters of soil causes the uptake of atmospheric CH4 by aerated soils. The capacity of the methylotrophs to consume CH4 commonly exceeds the potential of CH4 to diffuse from the atmosphere to the consumers. The maximum rate of uptake of atmospheric CH4 by soil is, therefore, limited by diffusion and can be calculated from soil physical properties and the CH4 concentration gradient. The CH4 concentration versus depth profile is theoretically described by the equation for gaseous diffusion with homogeneous chemical reaction in porous unsaturated media. This allows for calculation of the in situ rate of CH4 consumption within specified depth intervals.

Description of gas/particle sorption kinetics with an intraparticle diffusion model: Desorption experiments

USGS Publications Warehouse

Rounds, S.A.; Tiffany, B.A.; Pankow, J.F.

1993-01-01

Aerosol particles from a highway tunnel were collected on a Teflon membrane filter (TMF) using standard techniques. Sorbed organic compounds were then desorbed for 28 days by passing clean nitrogen through the filter. Volatile n-alkanes and polycyclic aromatic hydrocarbons (PAHs) were liberated from the filter quickly; only a small fraction of the less volatile ra-alkanes and PAHs were desorbed. A nonlinear least-squares method was used to fit an intraparticle diffusion model to the experimental data. Two fitting parameters were used: the gas/particle partition coefficient (Kp and an effective intraparticle diffusion coefficient (Oeff). Optimized values of Kp are in agreement with previously reported values. The slope of a correlation between the fitted values of Deff and Kp agrees well with theory, but the absolute values of Deff are a factor of ???106 smaller than predicted for sorption-retarded, gaseous diffusion. Slow transport through an organic or solid phase within the particles or preferential flow through the bed of particulate matter on the filter might be the cause of these very small effective diffusion coefficients. ?? 1993 American Chemical Society.

Atmospheric release model for the E-area low-level waste facility: Updates and modifications

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

None, None

The atmospheric release model (ARM) utilizes GoldSim® Monte Carlo simulation software (GTG, 2017) to evaluate the flux of gaseous radionuclides as they volatilize from E-Area disposal facility waste zones, diffuse into the air-filled soil pores surrounding the waste, and emanate at the land surface. This report documents the updates and modifications to the ARM for the next planned E-Area PA considering recommendations from the 2015 PA strategic planning team outlined by Butcher and Phifer.

Transport of elemental mercury in the unsaturated zone from a waste disposal site in an arid region

USGS Publications Warehouse

Walvoord, Michelle Ann; Andraski, Brian J.; Krabbenhoft, D.P.; Striegl, Robert G.

2008-01-01

Mercury contained in buried landfill waste may be released via upward emission to the atmosphere or downward leaching to groundwater. Data from the US Geological Survey’s Amargosa Desert Research Site (ADRS) in arid southwestern Nevada reveal another potential pathway of Hg release: long-distance (102 m) lateral migration of elemental Hg (Hg0) through the unsaturated zone. Gas collected from multiple depths from two instrumented boreholes that sample the entire 110-m unsaturated zone thickness and are located 100 and 160 m away from the closest waste burial trench exhibit gaseous Hg concentrations of up to 33 and 11 ng m−3, respectively. The vertical distribution of gaseous Hg in the borehole closest to the disposal site shows distinct subsurface peaks in concentration at depths of 1.5 and 24 m that cannot be explained by radial diffusive transport through a heterogeneous layered unsaturated zone. The inability of current models to explain gaseous Hg distribution at the ADRS highlights the need to advance the understanding of gas-phase contaminant transport in unsaturated zones to attain a comprehensive model of landfill Hg release.

Superfund record of decision (EPA Region 4): Paducah Gaseous Diffusion Plant (USDOE), Operable Unit 15, Paducah, KY, August 10, 1998

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

NONE

1998-12-01

This decision document presents the remedial action for the Solid Waste Management Unit (SWMU) 91 of the Waste Area Group (WAG) 27 at the Paducah Gaseous Diffusion Plant (PGDP) near Paducah, Kentucky. The primary objective of this remedial action is to reduce the level of TCE-contaminated soil thereby reducing the potential future concentrations in ground water that could pose a threat to human health and the environment at the POE (i.e., the DOE property boundary). The potential for migration of the contamination from the soil of the off-site aquifer is the concern associated with the SWMU.

A comparison of in-cloud HCl concentrations from the NASA/MSFC MDM to measurements for the space shuttle launch

NASA Technical Reports Server (NTRS)

Glasser, M. E.

1981-01-01

The Multilevel Diffusion Model (MDM) Version 5 was modified to include features of more recent versions. The MDM was used to predict in-cloud HCl concentrations for the April 12 launch of the space Shuttle (STS-1). The maximum centerline predictions were compared with measurements of maximum gaseous HCl obtained from aircraft passes through two segments of the fragmented shuttle ground cloud. The model over-predicted the maximum values for gaseous HCl in the lower cloud segment and portrayed the same rate of decay with time as the observed values. However, the decay with time of HCl maximum predicted by the MDM was more rapid than the observed decay for the higher cloud segment, causing the model to under-predict concentrations which were measured late in the life of the cloud. The causes of the tendency for the MDM to be conservative in over-estimating the HCl concentrations in the one case while tending to under-predict concentrations in the other case are discussed.

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

Simón, A.; et al.

Gaseous time projection chambers (TPC) are a very attractive detector technology for particle tracking. Characterization of both drift velocity and diffusion is of great importance to correctly assess their tracking capabilities. NEXT-White is a High Pressure Xenon gas TPC with electroluminescent amplification, a 1:2 scale model of the future NEXT-100 detector, which will be dedicated to neutrinoless double beta decay searches. NEXT-White has been operating at Canfranc Underground Laboratory (LSC) since December 2016. The drift parameters have been measured usingmore » $$^{83m}$$Kr for a range of reduced drift fields at two different pressure regimes, namely 7.2 bar and 9.1 bar. The results have been compared with Magboltz simulations. Agreement at the 5% level or better has been found for drift velocity, longitudinal diffusion and transverse diffusion.« less

Radiant Extinction Of Gaseous Diffusion Flames

NASA Technical Reports Server (NTRS)

Berhan, S.; Chernovsky, M.; Atreya, A.; Baum, Howard R.; Sacksteder, Kurt R.

2003-01-01

The absence of buoyancy-induced flows in microgravity (mu:g) and the resulting increase in the reactant residence time significantly alters the fundamentals of many combustion processes. Substantial differences between normal gravity (ng) and :g flames have been reported in experiments on candle flames [1, 2], flame spread over solids [3, 4], droplet combustion [5,6], and others. These differences are more basic than just in the visible flame shape. Longer residence times and higher concentration of combustion products in the flame zone create a thermochemical environment that changes the flame chemistry and the heat and mass transfer processes. Processes such as flame radiation, that are often ignored in ng, become very important and sometimes even controlling. Furthermore, microgravity conditions considerably enhance flame radiation by: (i) the build-up of combustion products in the high-temperature reaction zone which increases the gas radiation, and (ii) longer residence times make conditions appropriate for substantial amounts of soot to form which is also responsible for radiative heat loss. Thus, it is anticipated that radiative heat loss may eventually extinguish the Aweak@ (low burning rate per unit flame area) :g diffusion flame. Yet, space shuttle experiments on candle flames show that in an infinite ambient atmosphere, the hemispherical candle flame in :g will burn indefinitely [1]. This may be because of the coupling between the fuel production rate and the flame via the heat-feedback mechanism for candle flames, flames over solids and fuel droplet flames. Thus, to focus only on the gas-phase phenomena leading to radiative extinction, aerodynamically stabilized gaseous diffusion flames are examined. This enables independent control of the fuel flow rate to help identify conditions under which radiative extinction occurs. Also, spherical geometry is chosen for the :g experiments and modeling because: (i) It reduces the complexity by making the problem one-dimensional. (ii) The spherical diffusion flame completely encloses the soot which is formed on the fuel rich side of the reaction zone. This increases the importance of flame radiation because now both soot and gaseous combustion products co-exist inside the high temperature spherical diffusion flame. (iii) For small fuel injection velocities, as is usually the case for a pyrolyzing solid, the diffusion flame in :g around the solid naturally develops spherical symmetry. Thus, spherical diffusion flames are of interest to fires in :g and identifying conditions that lead to radiation-induced extinction is important for spacecraft fire safety.

Correlation of rates of tritium migration through porous concrete

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

Fukada, S.; Katayama, K.; Takeishi, T.

In a nuclear facility when tritium leaks from a glovebox to room accidentally, an atmosphere detritiation system (ADS) starts operating, and HTO released is recovered by ADS. ADS starts when tritium activity in air becomes higher than its controlled level. Before ADS operates, the laboratory walls are the final enclosure facing tritium and are usually made of porous concrete coated with a hydrophobic paint. In the present study, previous data on the diffusivity and adsorption coefficient of concrete and paints are reviewed. Tritium penetrates and migrates into concrete by following 3 ways. First, gaseous HT or T{sub 2} easily penetratesmore » into porous concrete. Its diffusivity is almost equal to that of H{sub 2}. When a gaseous molecule diffuses through pores with a smaller diameter than a mean free path, its migration rate is described by the Knudsen diffusion formula. The second mechanism is H{sub 2}O vapor diffusion in pores. Concrete holds a lot of structural water. Therefore, H{sub 2}O or HTO vapor can diffuse inside concrete pores along with adsorption-desorption and isotopic exchange with structural water, which is the third mechanism. Literature shows that the diffusivity of HTO through the epoxy-resin paint is determined as D(HTO)=1.0*10{sup -16} m{sup 2}/s. We have used this data to set a model and we have applied it to estimate residual tritium in laboratory walls. We have considered 2 accidental cases and a normal case: first, ADS starts operating 1 hour after 100 Ci HTO is released in the room, secondly, ADS starts 24 hours after 100 Ci HTO release and thirdly, when the walls are exposed to HTO for 10 years of normal operation. It appears that the immediate start up of ADS is indispensable for safety.« less

Process research of non-cz silicon material. Low cost solar array project, cell and module formation research area

NASA Technical Reports Server (NTRS)

1982-01-01

Liquid diffusion masks and liquid applied dopants to replace the CVD Silox masking and gaseous diffusion operations specified for forming junctions in the Westinghouse baseline process sequence for producing solar cells from dendritic web silicon were investigated.

Experimental and Numerical Study of Ammonium Perchlorate Counterflow Diffusion Flames

NASA Technical Reports Server (NTRS)

Smooke, M. D.; Yetter, R. A.; Parr, T. P.; Hanson-Parr, D. M.; Tanoff, M. A.

1999-01-01

Many solid rocket propellants are based on a composite mixture of ammonium perchlorate (AP) oxidizer and polymeric binder fuels. In these propellants, complex three-dimensional diffusion flame structures between the AP and binder decomposition products, dependent upon the length scales of the heterogeneous mixture, drive the combustion via heat transfer back to the surface. Changing the AP crystal size changes the burn rate of such propellants. Large AP crystals are governed by the cooler AP self-deflagration flame and burn slowly, while small AP crystals are governed more by the hot diffusion flame with the binder and burn faster. This allows control of composite propellant ballistic properties via particle size variation. Previous measurements on these diffusion flames in the planar two-dimensional sandwich configuration yielded insight into controlling flame structure, but there are several drawbacks that make comparison with modeling difficult. First, the flames are two-dimensional and this makes modeling much more complex computationally than with one-dimensional problems, such as RDX self- and laser-supported deflagration. In addition, little is known about the nature, concentration, and evolution rates of the gaseous chemical species produced by the various binders as they decompose. This makes comparison with models quite difficult. Alternatively, counterflow flames provide an excellent geometric configuration within which AP/binder diffusion flames can be studied both experimentally and computationally.

Construction and operation of an industrial solid waste landfill at Portsmouth Gaseous Diffusion Plant, Piketon, Ohio

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

NONE

1995-10-01

The US Department of Energy (DOE), Office of Waste Management, proposes to construct and operate a solid waste landfill within the boundary of the Portsmouth Gaseous Diffusion Plant (PORTS), Piketon, Ohio. The purpose of the proposed action is to provide PORTS with additional landfill capacity for non-hazardous and asbestos wastes. The proposed action is needed to support continued operation of PORTS, which generates non-hazardous wastes on a daily basis and asbestos wastes intermittently. Three alternatives are evaluated in this environmental assessment (EA): the proposed action (construction and operation of the X-737 landfill), no-action, and offsite shipment of industrial solid wastesmore » for disposal.« less

Model nebulae and determination of the chemical composition of the Magellanic Clouds

PubMed Central

Aller, L. H.; Keyes, C. D.; Czyzak, S. J.

1979-01-01

An analysis of previously presented photoelectric spectrophotometry of HII regions (emission-line diffuse nebulae) in the two Magellanic Clouds is carried out with the aid of theoretical nebular models, which are used primarily as interpolation devices. Some advantages and limitations of such theoretical models are discussed. A comparison of the finally obtained chemical compositions with those found by other observers shows generally a good agreement, suggesting that it is possible to obtain reliable chemical compositions from low excitation gaseous nebulae in our own galaxy as well as in distant stellar systems. PMID:16592633

Diffusion scrubber-ion chromatography for the measurement of trace levels of atmospheric HCl

NASA Astrophysics Data System (ADS)

Lindgren, Per F.

A diffusion scrubber-ion chromatographic (DS-IC) instrument has been characterized and employed for the measurement of trace levels of gaseous HCl in the atmosphere. The instrument operates with a temporal resolution of 5 min and the detection limit is estimated to be 5 pptv. Collection efficiencies for HCl with two identical diffusion scrubbers were 28±2% and 20±2%, respectively, at a sampling flow rate of 2 SLPM. Instrument response decreases with increased relative humidity. An equation, correction factor=2.45 × 10 -7 × %r.h 3 + 1.00, is used to correct for the relative humidity dependency. The instrument was tested in ambient air studies by measuring background mixing ratios between 0.02 and 0.5 ppbv at a suburban sampling site. Calibration of the instrument was carried out with a novel source of gaseous HCl based on sublimation of ammonium chloride.

Diffusive transport and reaction in clay rocks: A storage (nuclear waste, CO2, H2), energy (shale gas) and water quality issue

NASA Astrophysics Data System (ADS)

Charlet, Laurent; Alt-Epping, Peter; Wersin, Paul; Gilbert, Benjamin

2017-08-01

Clay rocks are low permeability sedimentary formations that provide records of Earth history, influence the quality of water resources, and that are increasingly used for the extraction or storage of energy resources and the sequestration of waste materials. Informed use of clay rock formations to achieve low-carbon or carbon-free energy goals requires the ability to predict the rates of diffusive transport processes for chemically diverse dissolved and gaseous species over periods up to thousands of years. We survey the composition, properties and uses of clay rock and summarize fundamental science challenges in developing confident conceptual and quantitative gas and solute transport models.

Field evaluation of a horizontal well recirculation system for groundwater treatment: Field demonstration at X-701B Portsmouth Gaseous Diffusion Plant, Piketon, Ohio

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

Korte, N.; Muck, M.; Kearl, P.

1998-08-01

This report describes the field-scale demonstration performed as part of the project, In Situ Treatment of Mixed Contaminants in Groundwater. This project was a 3{1/2} year effort comprised of laboratory work performed at Oak Ridge National Laboratory and fieldwork performed at the US Department of Energy (DOE) Portsmouth Gaseous Diffusion Plant (PORTS). The overall goal of the project was to evaluate in situ treatment of groundwater using horizontal recirculation coupled with treatment modules. Specifically, horizontal recirculation was tested because of its application to thin, interbedded aquifer zones. Mixed contaminants were targeted because of their prominence at DOE sites and becausemore » they cannot be treated with conventional methods. The project involved several research elements, including treatment process evaluation, hydrodynamic flow and transport modeling, pilot testing at an uncontaminated site, and full-scale testing at a contaminated site. This report presents the results of the work at the contaminated site, X-701B at PORTS. Groundwater contamination at X-701B consists of trichloroethene (TCE) (concentrations up to 1800 mg/L) and technetium-998 (Tc{sup 99}) (activities up to 926 pCi/L).« less

TC-99 Decontaminant from heat treated gaseous diffusion membrane -Phase I, Part B

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

Oji, L.; Restivo, M.; Duignan, M.

2017-11-01

Uranium gaseous diffusion cascades represent a significant environmental challenge to dismantle, containerize and dispose as low-level radioactive waste. Baseline technologies rely on manual manipulations involving direct access to technetium-contaminated piping and materials. There is a potential to utilize novel decontamination technologies to remove the technetium and allow for on-site disposal of the very large uranium converters. Technetium entered these gaseous diffusion cascades as a hexafluoride complex in the same fashion as uranium. Technetium, as the isotope Tc-99, is an impurity that follows uranium in the first cycle of the Plutonium and Uranium Extraction (PUREX) process. The technetium speciation or exactmore » form in the gaseous diffusion cascades is not well defined. Several forms of Tc-99 compounds, mostly the fluorinated technetium compounds with varying degrees of volatility have been speculated by the scientific community to be present in these cascades. Therefore, there may be a possibility of using thermal or leaching desorption, which is independent of the technetium oxidation states, to perform an insitu removal of the technetium as a volatile species and trap the radionuclide on sorbent traps which could be disposed as low-level waste. Based on the positive results of the first part of this work1 the use of steam as a thermal decontamination agent was further explored with a second piece of used barrier material from a different location. This new series of tests included exposing more of the material surface to the flow of high temperature steam through the change in the reactor design, subjecting it to alternating periods of stream and vacuum, as well as determining if a lower temperature steam, i.e., 121°C (250°F) would be effective, too. Along with these methods, one other simpler method involving the leaching of the Tc-99 contaminated barrier material with a 1.0 M aqueous solution of ammonium carbonate, with and without sonication, was evaluated.« less

Removal ratio of gaseous toluene and xylene transported from air to root zone via the stem by indoor plants.

PubMed

Kim, K J; Kim, H J; Khalekuzzaman, M; Yoo, E H; Jung, H H; Jang, H S

2016-04-01

This work was designed to investigate the removal efficiency as well as the ratios of toluene and xylene transported from air to root zone via the stem and by direct diffusion from the air into the medium. Indoor plants (Schefflera actinophylla and Ficus benghalensis) were placed in a sealed test chamber. Shoot or root zone were sealed with a Teflon bag, and gaseous toluene and xylene were exposed. Removal efficiency of toluene and total xylene (m, p, o) was 13.3 and 7.0 μg·m(-3)·m(-2) leaf area over a 24-h period in S. actinophylla, and was 13.0 and 7.3 μg·m(-3)·m(-2) leaf area in F. benghalensis. Gaseous toluene and xylene in a chamber were absorbed through leaf and transported via the stem, and finally reached to root zone, and also transported by direct diffusion from the air into the medium. Toluene and xylene transported via the stem was decreased with time after exposure. Xylene transported via the stem was higher than that by direct diffusion from the air into the medium over a 24-h period. The ratios of toluene transported via the stem versus direct diffusion from the air into the medium were 46.3 and 53.7% in S. actinophylla, and 46.9 and 53.1% in F. benghalensis, for an average of 47 and 53% for both species. The ratios of m,p-xylene transported over 3 to 9 h via the stem versus direct diffusion from the air into the medium was 58.5 and 41.5% in S. actinophylla, and 60.7 and 39.3% in F. benghalensis, for an average of 60 and 40% for both species, whereas the ratios of o-xylene transported via the stem versus direct diffusion from the air into the medium were 61 and 39%. Both S. actinophylla and F. benghalensis removed toluene and xylene from the air. The ratios of toluene and xylene transported from air to root zone via the stem were 47 and 60 %, respectively. This result suggests that root zone is a significant contributor to gaseous toluene and xylene removal, and transported via the stem plays an important role in this process.

NMR investigation of gaseous SF6 confinement into EPDM rubber.

PubMed

Neutzler, Sven; Terekhov, Maxim; Hoepfel, Dieter; Oellrich, Lothar Rainer

2005-02-01

The confinement process of gaseous sulphurhexafluoride (SF6) in ethylene-propylene-diene (EPDM) rubber was investigated by spectroscopic and spatially resolved NMR techniques. A strong elongation of T1 relaxation time of SF6 and a decrease of the diffusion coefficient were found. A possible explanation may be the strong restriction of molecular mobility due to interactions between SF6 and active centers of the EPDM.

Dynamical friction on hot bodies in opaque, gaseous media

NASA Astrophysics Data System (ADS)

Masset, Frédéric S.; Velasco Romero, David A.

2017-03-01

We consider the gravitational force exerted on a point-like perturber of mass M travelling within a uniform gaseous, opaque medium at constant velocity V. The perturber irradiates the surrounding gas with luminosity L. The diffusion of the heat released is modelled with a uniform thermal diffusivity χ. Using linear perturbation theory, we show that the force exerted by the perturbed gas on the perturber differs from the force without radiation (or standard dynamical friction). Hot, underdense gas trails the mass, which gives rise to a new force component, the heating force, with direction +V, thus opposed to the standard dynamical friction. In the limit of low Mach numbers, the heating force has expression F_heat=γ (γ -1)GML/(2χ c_s^2), cs being the sound speed and γ the ratio of specific heats. In the limit of large Mach numbers, Fheat = (γ - 1)GML/(χV2)f(rminV/4χ), where f is a function that diverges logarithmically as rmin tends to zero. Remarkably, the force in the low Mach number limit does not depend on the velocity. The equilibrium speed, when it exists, is set by the cancellation of the standard dynamical friction and heating force. In the low Mach number limit, it scales with the luminosity-to-mass ratio of the perturber. Using the above results suggests that Mars- to Earth-sized planetary embryos heated by accretion in a gaseous protoplanetary disc should have eccentricities and inclinations that amount to a sizeable fraction of the disc's aspect ratio, for conditions thought to prevail at a few astronomical units.

Pore network modeling to explore the effects of compression on multiphase transport in polymer electrolyte membrane fuel cell gas diffusion layers

NASA Astrophysics Data System (ADS)

Fazeli, Mohammadreza; Hinebaugh, James; Fishman, Zachary; Tötzke, Christian; Lehnert, Werner; Manke, Ingo; Bazylak, Aimy

2016-12-01

Understanding how compression affects the distribution of liquid water and gaseous oxygen in the polymer electrolyte membrane fuel cell gas diffusion layer (GDL) is vital for informing the design of improved porous materials for effective water management strategies. Pore networks extracted from synchrotron-based micro-computed tomography images of compressed GDLs were employed to simulate liquid water transport in GDL materials over a range of compression pressures. The oxygen transport resistance was predicted for each sample under dry and partially saturated conditions. A favorable GDL compression value for a preferred liquid water distribution and oxygen diffusion was found for Toray TGP-H-090 (10%), yet an optimum compression value was not recognized for SGL Sigracet 25BC. SGL Sigracet 25BC exhibited lower transport resistance values compared to Toray TGP-H-090, and this is attributed to the additional diffusion pathways provided by the microporous layer (MPL), an effect that is particularly significant under partially saturated conditions.

On the kinetics of the pack - Aluminization process

NASA Technical Reports Server (NTRS)

Sivakumar, R.; Seigle, L. L.

1976-01-01

An investigation has been made of the aluminization of unalloyed Ni in fluoride-activated packs of varying Al activity. In packs of low Al activity, in which the ratio of Al to Ni was less than 50 at. pct, the specimen surface quickly came to equilibrium with the pack and remained close to equilibrium for the duration of normal coating runs. In these packs the kinetics of aluminization was controlled by diffusion in the solid. In packs of higher Al activity the surface of the specimen did not come to equilibrium with the pack and the kinetics of the process was governed by a combination of solid and gas diffusion rates. Under most conditions however, the surface composition was time-invariant and a steady-state appeared to exist at the pack-coating interface. By combining Levine and Caves' model for gaseous diffusion in pure-Al packs with calculations of solid diffusion rates some success has been achieved in explaining the results.

Purging of multilayer insulation by gas diffusion

NASA Technical Reports Server (NTRS)

Sumner, I. E.; Spuckler, C. M.

1976-01-01

An experimental investigation was conducted to determine the time required to purge a multilayer insulation (MLI) panel with gaseous helium by means of gas diffusion to obtain a condensable (nitrogen) gas concentration of less than 1 percent within the panel. Two flat, rectangular MLI panel configurations, one incorporating a butt joint, were tested. The insulation panels consisted of 15 double-aluminized Mylar radiation shields separated by double silk net spacers. The test results indicated that the rate which the condensable gas concentration at the edge or at the butt joint of an MLI panel was reduced was a significant factor in the total time required to reduce the condensable gas concentration within the panel to less than 1 percent. The experimental data agreed well with analytical predictions made by using a simple, one-dimensional gas diffusion model in which the boundary conditions at the edge of the MLI panel were time dependent.

Variations in Gas and Water Pulses at an Arctic Seep: Fluid Sources and Methane Transport

NASA Astrophysics Data System (ADS)

Hong, W.-L.; Torres, M. E.; Portnov, A.; Waage, M.; Haley, B.; Lepland, A.

2018-05-01

Methane fluxes into the oceans are largely dependent on the methane phase as it migrates upward through the sediments. Here we document decoupled methane transport by gaseous and aqueous phases in Storfjordrenna (offshore Svalbard) and propose a three-stage evolution model for active seepage in the region where gas hydrates are present in the shallow subsurface. In a preactive seepage stage, solute diffusion is the primary transport mechanism for methane in the dissolved phase. Fluids containing dissolved methane have high 87Sr/86Sr ratios due to silicate weathering in the microbial methanogenesis zone. During the active seepage stage, migration of gaseous methane results in near-seafloor gas hydrate formation and vigorous seafloor gas discharge with a thermogenic fingerprint. In the postactive seepage stage, the high concentration of dissolved lithium points to the contribution of a deeper-sourced aqueous fluid, which we postulate advects upward following cessation of gas discharge.

Apparatus for diffusion separation

DOEpatents

Nierenberg, William A.

1976-08-10

1. A diffuser separator apparatus which comprises a plurality of flow channels in a single stage, each of said channels having an inlet port and an outlet port and a constant cross sectional area between said ports, at least a portion of the defining surface of each of said channels being a diffusion separation membrane, and each of said channels having a different cross sectional area, means for connecting said channels in series so that each successive channel of said series has a smaller cross sectional area than the previous channel of said series, a source of gaseous mixture, individual means for flowing said gaseous mixture to the inlet port of each of said channels, gas receiving and analyzing means, individual means for flowing gas passing from each of said outlet ports and means for flowing gas passing through said membranes to said receiving and analyzing means, and individual means for connecting the outlet port of each channel with the inlet port of the channel having the next smaller cross sectional area.

Apparatus for diffusion-gap thermal desalination

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

Lowenstein, Andrew

A thermal distillation apparatus including evaporation surfaces that are wetted with a solution, and from which at least some of the volatile solvent contained in the solution evaporates, condensers having an external surface in close proximity to, but not touching, a corresponding one of the one or more evaporation surfaces, and on which vapors of the solvent condense, releasing thermal energy that heats a flow of the solution moving upward within the condensers, spacers that prevent contact between the evaporating surfaces and the condensers, wherein spaces between the evaporating surfaces and the condensers are filled with a gaseous mixture composedmore » of solvent vapor and one or more non-condensable gases, and except for diffusion of the solvent vapor relative to the non-condensable gases, the gaseous mixture is stationary.« less

Significance of population centers as sources of gaseous and dissolved PAHs in the lower Great Lakes.

PubMed

McDonough, Carrie A; Khairy, Mohammed A; Muir, Derek C G; Lohmann, Rainer

2014-07-15

Polyethylene passive samplers (PEs) were used to measure concentrations of gaseous and dissolved polycyclic aromatic hydrocarbons (PAHs) in the air and water throughout the lower Great Lakes during summer and fall of 2011. Atmospheric Σ15PAH concentrations ranged from 2.1 ng/m3 in Cape Vincent (NY) to 76.4 ng/m3 in downtown Cleveland (OH). Aqueous Σ18PAH concentrations ranged from 2.4 ng/L at an offshore Lake Erie site to 30.4 ng/L in Sheffield Lake (OH). Gaseous PAH concentrations correlated strongly with population within 3-40 km of the sampling site depending on the compound considered, suggesting that urban centers are a primary source of gaseous PAHs (except retene) in the lower Great Lakes region. The significance of distant population (within 20 km) versus local population (within 3 km) increased with subcooled liquid vapor pressure. Most dissolved aqueous PAHs did not correlate significantly with population, nor were they consistently related to river discharge, wastewater effluents, or precipitation. Air-water exchange calculations implied that diffusive exchange was a source of phenanthrene to surface waters, while acenaphthylene volatilized out of the lakes. Comparison of air-water fluxes with temperature suggested that the significance of urban centers as sources of dissolved PAHs via diffusive exchange may decrease in warmer months.

Thaumatin crystallization aboard the International Space Station using liquid-liquid diffusion in the Enhanced Gaseous Nitrogen Dewar (EGN).

PubMed

Barnes, Cindy L; Snell, Edward H; Kundrot, Craig E

2002-05-01

This paper reports results from the first biological crystal-growth experiment on the International Space Station (ISS). Crystals of thaumatin were grown using liquid-liquid diffusion in Tygon tubing transported in the Enhanced Gaseous Nitrogen Dewar (EGN). Different volume ratios and concentrations of protein and precipitant were used to test different adaptations of the vapor-diffusion crystallization recipe to the liquid-liquid diffusion method. The EGN warmed up from 77 to 273 K in about 4 d, about the same time it took to warm from 273 to 293 K. The temperature within the EGN was 293-297 K for the majority of the experiment. Air gaps that blocked liquid-liquid diffusion formed in the tubes. Nonetheless, crystals were grown. Synchrotron diffraction data collected from the best space-grown crystal extended to 1.28 A, comparable to previous studies of space-grown thaumatin crystals. The resolution of the best ground-control crystal was only 1.47 A. It is not clear if the difference in diffraction limit arises from factors other than crystal size. Improvements in temperature control and the elimination of air gaps are needed, but the results show that the EGN on the ISS can be used to produce space-grown crystals that diffract to high resolution.

Thaumatin Crystallization Aboard the International Space Station Using Liquid-Liquid Diffusion in the Enhanced Gaseous Nitrogen Dewar (EGN)

NASA Technical Reports Server (NTRS)

Kundrot, Craig; Barnes, Cindy L.; Snell, Edward H.; Stinson, Thomas N. (Technical Monitor)

2002-01-01

This paper reports results from the first biological crystal growth experiment on the International Space Station (ISS). Crystals of thaumatin were grown using liquid-liquid diffusion in Tygon tubing transported in the Enhanced Gaseous Nitrogen Dewar (EGN). Different Volume ratios and concentrations of protein and precipitant were used to test different adaptations of the vapor diffusion crystallization recipe to the liquid-liquid diffusion method. The EGN warmed up from -196 C to 0 C in about four days, about the same time it took to warm from 0 C to 20 C. The temperature within the EGN was 20 - 24 C for the majority of the experiment. Air gaps that blocked liquid-liquid diffusion formed in the tubes. Nonetheless, crystals were grown. Synchrotron diffraction data collected from the best space grown crystal extended to 1.28 Angstroms, comparable to previous studies of space-grown thaumatin crystals. The resolution of the best ground control crystal was only 1.47 Angstroms. It is not clear if the difference in diffraction limit is due to factors other than crystal size. Improvements in temperature control and the elimination of air gaps are needed, but the results show that EGN on the ISS can be used to produce space grown crystals that diffract to high resolution.

The effect of soot modeling on thermal radiation in buoyant turbulent diffusion flames

NASA Astrophysics Data System (ADS)

Snegirev, A.; Kokovina, E.; Tsoy, A.; Harris, J.; Wu, T.

2016-09-01

Radiative impact of buoyant turbulent diffusion flames is the driving force in fire development. Radiation emission and re-absorption is controlled by gaseous combustion products, mainly CO2 and H2O, and by soot. Relative contribution of gas and soot radiation depends on the fuel sooting propensity and on soot distribution in the flame. Soot modeling approaches incorporated in big commercial codes were developed and calibrated for momentum-dominated jet flames, and these approaches must be re-evaluated when applied to the buoyant flames occurring in fires. The purpose of this work is to evaluate the effect of the soot models available in ANSYS FLUENT on the predictions of the radiative fluxes produced by the buoyant turbulent diffusion flames with considerably different soot yields. By means of large eddy simulations, we assess capability of the Moss-Brooks soot formation model combined with two soot oxidation submodels to predict methane- and heptane-fuelled fires, for which radiative flux measurements are available in the literature. We demonstrate that the soot oxidation models could be equally important as soot formation ones to predict the soot yield in the overfire region. Contribution of soot in the radiation emission by the flame is also examined, and predicted radiative fluxes are compared to published experimental data.

Gas mixture for diffuse-discharge switch

DOEpatents

Christophorou, Loucas G.; Carter, James G.; Hunter, Scott R.

1984-01-01

Gaseous medium in a diffuse-discharge switch of a high-energy pulse generator is formed of argon combined with a compound selected from the group consisting of CF.sub.4, C.sub.2 F.sub.6, C.sub.3 F.sub.8, n-C.sub.4 F.sub.10, WF.sub.6, (CF.sub.3).sub.2 S and (CF.sub.3).sub.2 O.

Gas mixture for diffuse-discharge switch

DOEpatents

Christophorou, L.G.; Carter, J.G.; Hunter, S.R.

1982-08-31

Gaseous medium in a diffuse-discharge switch of a high-energy pulse generator is formed of argon combined with a compound selected from the group consisting of CF/sub 4/, C/sub 2/F/sub 6/, C/sub 3/F/sub 8/, n-C/sub 4/F/sub 10/, WF/sub 6/, (CF/sub 3/)/sub 2/S and (CF/sub 3/)/sub 2/O.

Transport coefficients of gaseous ions in an electric field

NASA Technical Reports Server (NTRS)

Whealton, J. H.; Mason, E. A.

1974-01-01

A general theory of ion mobility formulated by Kihara (1953) is extended to ion diffusion and to mixtures of neutral gases. The theory assumes that only binary collisions between ions and neutral particles need to be taken into account and that the velocity distribution function of the neutral particles is Maxwellian. These assumptions make it possible to use a linearized Boltzmann equation. Questions of mobility are considered along with aspects of diffusion and deviations from Fick's law of diffusion.

Recent development of a jet-diffuser ejector

NASA Technical Reports Server (NTRS)

Alperin, M.; Wu, J. J.

1980-01-01

The paper considers thrust augmenting ejectors in which the processes of mixing and diffusion are partly carried out downstream of the ejector solid surfaces. A jet sheet surrounding the periphery of a widely diverging diffuser prevents separation and forms a gaseous, curved surface to provide effective diffuser ratio and additional length for mixing of primary and induced flows. Three-dimensional potential flow methods achieved a large reduction in the length of the associated solid surface; primary nozzle design further reduced the volume required by the jet-diffuser ejectors, resulting in thrust augmentation in excess of two, and an overall length of about 2 1/2 times the throat width.

Cavitation inception from bubble nuclei

PubMed Central

Mørch, K. A.

2015-01-01

The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid. The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure–time history of the water. A recent model and associated experiments throw new light on the effects of transient pressures on the tensile strength of water, which may be notably reduced or increased by such pressure changes. PMID:26442138

The Mailbox Computer System for the IAEA verification experiment on HEU downlending at the Portsmouth Gaseous Diffusion Plant

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

Aronson, A.L.; Gordon, D.M.

IN APRIL 1996, THE UNITED STATES (US) ADDED THE PORTSMOUTH GASEOUS DIFFUSION PLANT TO THE LIST OF FACILITIES ELIGIBLE FOR THE APPLICATION OF INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA) SAFEGUARDS. AT THAT TIME, THE US PROPOSED THAT THE IAEA CARRY OUT A ''VERIFICATION EXPERIMENT'' AT THE PLANT WITH RESPECT TO DOOWNBLENDING OF ABOUT 13 METRIC TONS OF HIGHLY ENRICHED URANIUM (HEU) IN THE FORM OF URANIUM HEXAFLUROIDE (UF6). DURING THE PERIOD DECEMBER 1997 THROUGH JULY 1998, THE IAEA CARRIED OUT THE REQUESTED VERIFICATION EXPERIMENT. THE VERIFICATION APPROACH USED FOR THIS EXPERIMENT INCLUDED, AMONG OTHER MEASURES, THE ENTRY OF PROCESS-OPERATIONAL DATA BYmore » THE FACILITY OPERATOR ON A NEAR-REAL-TIME BASIS INTO A ''MAILBOX'' COMPUTER LOCATED WITHIN A TAMPER-INDICATING ENCLOSURE SEALED BY THE IAEA.« less

Technology needs for environmental restoration remedial action

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

Watson, J.S.

1992-11-01

This report summarizes the current view of the most important technology needs for the US Department of Energy (DOE) facilities operated by Martin Marietta Energy Systems, Inc. These facilities are the Oak Ridge National Laboratory, the Oak Ridge K-25 Site, the Oak Ridge Y-12 Plant, the Paducah Gaseous Diffusion Plant, and the Portsmouth Gaseous Diffusion Plant. The sources of information used in this assessment were a survey of selected representatives of the Environmental Restoration (ER) programs at each facility, results from a questionnaire distributed by Geotech CWM, Inc., for DOE, and associated discussions with individuals from each facility. This ismore » not a final assessment, but a brief look at an ongoing assessment; the needs will change as the plans for restoration change and, it is hoped, as some technical problems are solved through successful development programs.« less

Apparatus and method for the acceleration of projectiles to hypervelocities

DOEpatents

Hertzberg, Abraham; Bruckner, Adam P.; Bogdanoff, David W.

1990-01-01

A projectile is initially accelerated to a supersonic velocity and then injected into a launch tube filled with a gaseous propellant. The projectile outer surface and launch tube inner surface form a ramjet having a diffuser, a combustion chamber and a nozzle. A catalytic coated flame holder projecting from the projectile ignites the gaseous propellant in the combustion chamber thereby accelerating the projectile in a subsonic combustion mode zone. The projectile then enters an overdriven detonation wave launch tube zone wherein further projectile acceleration is achieved by a formed, controlled overdriven detonation wave capable of igniting the gaseous propellant in the combustion chamber. Ultrahigh velocity projectile accelerations are achieved in a launch tube layered detonation zone having an inner sleeve filled with hydrogen gas. An explosive, which is disposed in the annular zone between the inner sleeve and the launch tube, explodes responsive to an impinging shock wave emanating from the diffuser of the accelerating projectile thereby forcing the inner sleeve inward and imparting an acceleration to the projectile. For applications wherein solid or liquid high explosives are employed, the explosion thereof forces the inner sleeve inward, forming a throat behind the projectile. This throat chokes flow behind, thereby imparting an acceleration to the projectile.

Performance Capability of Single-Cavity Vortex Gaseous Nuclear Rockets

NASA Technical Reports Server (NTRS)

Ragsdale, Robert G.

1963-01-01

An analysis was made to determine the maximum powerplant thrust-to-weight ratio possible with a single-cavity vortex gaseous reactor in which all the hydrogen propellant must diffuse through a fuel-rich region. An assumed radial temperature profile was used to represent conduction, convection, and radiation heat-transfer effects. The effect of hydrogen property changes due to dissociation and ionization was taken into account in a hydrodynamic computer program. It is shown that, even for extremely optimistic assumptions of reactor criticality and operating conditions, such a system is limited to reactor thrust-to-weight ratios of about 1.2 x 10(exp -3) for laminar flow. For turbulent flow, the maximum thrust-to-weight ratio is less than 10(exp -3). These low thrusts result from the fact that the hydrogen flow rate is limited by the diffusion process. The performance of a gas-core system with a specific impulse of 3000 seconds and a powerplant thrust-to-weight ratio of 10(exp -2) is shown to be equivalent to that of a 1000-second advanced solid-core system. It is therefore concluded that a single-cavity vortex gaseous reactor in which all the hydrogen must diffuse through the nuclear fuel is a low-thrust device and offers no improvement over a solid-core nuclear-rocket engine. To achieve higher thrust, additional hydrogen flow must be introduced in such a manner that it will by-pass the nuclear fuel. Obviously, such flow must be heated by thermal radiation. An illustrative model of a single-cavity vortex system employing supplementary flow of hydrogen through the core region is briefly examined. Such a system appears capable of thrust-to-weight ratios of approximately 1 to 10. For a high-impulse engine, this capability would be a considerable improvement over solid-core performance. Limits imposed by thermal radiation heat transfer to cavity walls are acknowledged but not evaluated. Alternate vortex concepts that employ many parallel vortices to achieve higher hydrogen flow rates offer the possibility of sufficiently high thrust-to-weight ratios, if they are not limited by short thermal-radiation path lengths.

An experimental investigation of reacting and nonreacting coaxial jet mixing in a laboratory rocket engine

NASA Astrophysics Data System (ADS)

Schumaker, Stephen Alexander

Coaxial jets are commonly used as injectors in propulsion and combustion devices due to both the simplicity of their geometry and the rapid mixing they provide. In liquid rocket engines it is common to use coaxial jets in the context of airblast atomization. However, interest exists in developing rocket engines using a full flow staged combustion cycle. In such a configuration both propellants are injected in the gaseous phase. In addition, gaseous coaxial jets have been identified as an ideal test case for the validation of the next generation of injector modeling tools. For these reasons an understanding of the fundamental phenomena which govern mixing in gaseous coaxial jets and the effect of combustion on these phenomena in coaxial jet diffusion flames is needed. A study was performed to better understand the scaling of the stoichiometric mixing length in reacting and nonreacting coaxial jets with velocity ratios greater than one and density ratios less than one. A facility was developed that incorporates a single shear coaxial injector in a laboratory rocket engine capable of ten atmospheres. Optical access allows the use of flame luminosity and laser diagnostic techniques such as Planar Laser Induced Fluorescence (PLIF). Stoichiometric mixing lengths (LS), which are defined as the distance along the centerline where the stoichiometric condition occurs, were measured using PLIF. Acetone was seeded into the center jet to provide direct PLIF measurement of the average and instantaneous mixture fraction fields for a range of momentum flux ratios for the nonreacting cases. For the coaxial jet diffusion flames, LS was measured from OH radical contours. For nonreacting cases the use of a nondimensional momentum flux ratio was found to collapse the mixing length data. The flame lengths of coaxial jet diffusion flames were also found to scale with the momentum flux ratio but different scaling constants are required which depended on the chemistry of the reaction. The effective density ratio was measured which allowed the flame lengths to be collapsed to the nonreacting scaling relation. The equivalence principle of Tacina and Dahm was utilized to compare the theoretical and measured effective density ratios.

Need-based activation of ammonium uptake in Escherichia coli

PubMed Central

Kim, Minsu; Zhang, Zhongge; Okano, Hiroyuki; Yan, Dalai; Groisman, Alexander; Hwa, Terence

2012-01-01

The efficient sequestration of nutrients is vital for the growth and survival of microorganisms. Some nutrients, such as CO2 and NH3, are readily diffusible across the cell membrane. The large membrane permeability of these nutrients obviates the need of transporters when the ambient level is high. When the ambient level is low, however, maintaining a high intracellular nutrient level against passive back diffusion is both challenging and costly. Here, we study the delicate management of ammonium (NH4+/NH3) sequestration by E. coli cells using microfluidic chemostats. We find that as the ambient ammonium concentration is reduced, E. coli cells first maximize their ability to assimilate the gaseous NH3 diffusing into the cytoplasm and then abruptly activate ammonium transport. The onset of transport varies under different growth conditions, but always occurring just as needed to maintain growth. Quantitative modeling of known interactions reveals an integral feedback mechanism by which this need-based uptake strategy is implemented. This novel strategy ensures that the expensive cost of upholding the internal ammonium concentration against back diffusion is kept at a minimum. PMID:23010999

77 FR 4799 - Environmental Management Site-Specific Advisory Board, Paducah

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-31

...] Recommendation 12-02: Pro Nuclear Future Use for Paducah Gaseous Diffusion Plant Site Public Comments Adjourn... clean-up science and technology activities). Comments outside of the scope may be submitted via written...

Evaluating BTEX concentration in soil using a simple one-dimensional vado zone model: application to a new fuel station in Valencia (Spain)

NASA Astrophysics Data System (ADS)

Rodrigo-Ilarri, Javier; Rodrigo-Clavero, María-Elena

2017-04-01

Specific studies of the impact of fuel spills on the vadose zone are currently required when trying to obtain the environmental permits for new fuel stations. The development of One-Dimensional mathematical models of fate and transport of BTEX on the vadose zone can therefore be used to understand the behavior of the pollutants under different scenarios. VLEACH - a simple One-Dimensional Finite Different Vadose Zone Leaching Model - uses an numerical approximation of the Millington Equation, a theoretical based model for gaseous diffusion in porous media. This equation has been widely used in the fields of soil physics and hydrology to calculate the gaseous or vapor diffusion in porous media. The model describes the movement of organic contaminants within and between three different phases: (1) as a solute dissolved in water, (2) as a gas in the vapor phase, and (3) as an absorbed compound in the soil phase. Initially, the equilibrium distribution of contaminant mass between liquid, gas and sorbed phases is calculated. Transport processes are then simulated. Liquid advective transport is calculated based on values defined by the user for infiltration and soil water content. The contaminant in the vapor phase migrates into or out of adjacent cells based on the calculated concentration gradients that exist between adjacent cells. After the mass is exchanged between the cells, the total mass in each cell is recalculated and re-equilibrated between the different phases. At the end of the simulation, (1) an overall area-weighted groundwater impact for the entire modeled area and (2) the concentration profile of BTEX on the vadose zone are calculated. This work shows the results obtained when applying VLEACH to analyze the contamination scenario caused by a BTEX spill coming from a set of future underground storage tanks located on a new fuel station in Aldaia (Valencia region - Spain).

Study on gas diffusion emitted from different height of point source.

PubMed

Yassin, Mohamed F

2009-01-01

The flow and dispersion of stack-gas emitted from different elevated point source around flow obstacles in an urban environment have been investigated, using computational fluid dynamics models (CFD). The results were compared with the experimental results obtained from the diffusion wind tunnel under different conditions of thermal stability (stable, neutral or unstable). The flow and dispersion fields in the boundary layer in an urban environment were examined with different flow obstacles. Gaseous pollutant was discharged in the simulated boundary layer over the flat area. The CFD models used for the simulation were based on the steady-state Reynolds-Average Navier-Stoke equations (RANS) with kappa-epsilon turbulence models; standard kappa-epsilon and RNG kappa-epsilon models. The flow and dispersion data measured in the wind tunnel experiments were compared with the results of the CFD models in order to evaluate the prediction accuracy of the pollutant dispersion. The results of the CFD models showed good agreement with the results of the wind tunnel experiments. The results indicate that the turbulent velocity is reduced by the obstacles models. The maximum dispersion appears around the wake region of the obstacles.

DETECTION OF A HOT GASEOUS HALO AROUND THE GIANT SPIRAL GALAXY NGC 1961

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

Anderson, Michael E.; Bregman, Joel N., E-mail: michevan@umich.edu, E-mail: jbregman@umich.edu

2011-08-10

Hot gaseous halos are predicted around all large galaxies and are critically important for our understanding of galaxy formation, but they have never been detected at distances beyond a few kpc around a spiral galaxy. We used the ACIS-I instrument on board Chandra to search for diffuse X-ray emission around an ideal candidate galaxy: the isolated giant spiral NGC 1961. We observed four quadrants around the galaxy for 30 ks each, carefully subtracting background and point-source emission, and found diffuse emission that appears to extend to 40-50 kpc. We fit {beta}-models to the emission and estimate a hot halo massmore » within 50 kpc of 5 x 10{sup 9} M{sub sun}. When this profile is extrapolated to 500 kpc (the approximate virial radius), the implied hot halo mass is 1-3 x 10{sup 11} M{sub sun}. These mass estimates assume a gas metallicity of Z = 0.5 Z{sub sun}. This galaxy's hot halo is a large reservoir of gas, but falls significantly below observational upper limits set by pervious searches, and suggests that NGC 1961 is missing 75% of its baryons relative to the cosmic mean, which would tentatively place it below an extrapolation of the baryon Tully-Fisher relationship of less massive galaxies. The cooling rate of the gas is no more than 0.4 M{sub sun} yr{sup -1}, more than an order of magnitude below the gas consumption rate through star formation. We discuss the implications of this halo for galaxy formation models.« less

Determination of 1-octanol-air partition coefficient using gaseous diffusion in the air boundary layer.

PubMed

Ha, Yeonjeong; Kwon, Jung-Hwan

2010-04-15

Exact determination of the partition coefficient between 1-octanol and air (K(OA)) is very important because it is a key descriptor for describing the thermodynamic partitioning between the air and organic phases. In spite of its importance, the number and quality of experimental K(OA) values for hydrophobic organic chemicals are limited because of experimental difficulties. Thus, to measure K(OA) values, a high-throughput method was developed that used liquid-phase extraction with 1-octanol drop at the tip of a microsyringe needle. The concentration in the headspace surrounding the 1 muL octanol drop was equilibrated with liquid octanol containing polycyclic aromatic hydrocarbons (PAHs). The change in concentrations of PAHs in the octanol drop was measured to obtain mass transfer rate constants, and these rate constants were then converted into K(OA) values using a film diffusion model. Thirteen polycyclic aromatic hydrocarbons with log K(OA) between 5 and 12 were chosen for the proof of the principle. Experimental determination of log K(OA) was accomplished in 30 h for PAHs with their log K(OA) less than 11. The measured log K(OA) values were very close to those obtained by various experimental and estimation methods in the literature, suggesting that this new method can provide a fast and easy determination of log K(OA) values for many chemicals of environmental interests. In addition, the applicability of the method can be extended to determine Henry's law constant for compounds with low vapor pressure and to estimate gaseous transfer rate of semivolatile compounds for environmental fate modeling.

77 FR 39899 - Technical Corrections

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-06

..., Nuclear material, Oil and gas exploration--well logging, Reporting and recordkeeping requirements... recordkeeping requirements, Source material, Uranium. 10 CFR Part 50 Antitrust, Classified information, Criminal... measures, Special nuclear material, Uranium enrichment by gaseous diffusion. 10 CFR Part 81 Administrative...

Technology needs for environmental restoration remedial action. Environmental Restoration Program

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

Watson, J.S.

1992-11-01

This report summarizes the current view of the most important technology needs for the US Department of Energy (DOE) facilities operated by Martin Marietta Energy Systems, Inc. These facilities are the Oak Ridge National Laboratory, the Oak Ridge K-25 Site, the Oak Ridge Y-12 Plant, the Paducah Gaseous Diffusion Plant, and the Portsmouth Gaseous Diffusion Plant. The sources of information used in this assessment were a survey of selected representatives of the Environmental Restoration (ER) programs at each facility, results from a questionnaire distributed by Geotech CWM, Inc., for DOE, and associated discussions with individuals from each facility. This ismore » not a final assessment, but a brief look at an ongoing assessment; the needs will change as the plans for restoration change and, it is hoped, as some technical problems are solved through successful development programs.« less

Simulating Isotope Enrichment by Gaseous Diffusion

NASA Astrophysics Data System (ADS)

Reed, Cameron

2015-04-01

A desktop-computer simulation of isotope enrichment by gaseous diffusion has been developed. The simulation incorporates two non-interacting point-mass species whose members pass through a cascade of cells containing porous membranes and retain constant speeds as they reflect off the walls of the cells and the spaces between holes in the membranes. A particular feature is periodic forward recycling of enriched material to cells further along the cascade along with simultaneous return of depleted material to preceding cells. The number of particles, the mass ratio, the initial fractional abundance of the lighter species, and the time between recycling operations can be chosen by the user. The simulation is simple enough to be understood on the basis of two-dimensional kinematics, and demonstrates that the fractional abundance of the lighter-isotope species increases along the cascade. The logic of the simulation will be described and results of some typical runs will be presented and discussed.

A multi-scalar PDF approach for LES of turbulent spray combustion

NASA Astrophysics Data System (ADS)

Raman, Venkat; Heye, Colin

2011-11-01

A comprehensive joint-scalar probability density function (PDF) approach is proposed for large eddy simulation (LES) of turbulent spray combustion and tests are conducted to analyze the validity and modeling requirements. The PDF method has the advantage that the chemical source term appears closed but requires models for the small scale mixing process. A stable and consistent numerical algorithm for the LES/PDF approach is presented. To understand the modeling issues in the PDF method, direct numerical simulation of a spray flame at three different fuel droplet Stokes numbers and an equivalent gaseous flame are carried out. Assumptions in closing the subfilter conditional diffusion term in the filtered PDF transport equation are evaluated for various model forms. In addition, the validity of evaporation rate models in high Stokes number flows is analyzed.

Unsteady Spherical Diffusion Flames in Microgravity

NASA Technical Reports Server (NTRS)

Atreya, Arvind; Berhan, S.; Chernovsky, M.; Sacksteder, Kurt R.

2001-01-01

The absence of buoyancy-induced flows in microgravity (mu-g) and the resulting increase in the reactant residence time significantly alters the fundamentals of many combustion processes. Substantial differences between normal gravity (ng) and (mu-g) flames have been reported in experiments on candle flames, flame spread over solids, droplet combustion, and others. These differences are more basic than just in the visible flame shape. Longer residence times and higher concentration of combustion products in the flame zone create a thermochemical environment that changes the flame chemistry and the heat and mass transfer processes. Processes such as flame radiation, that are often ignored in ng, become very important and sometimes even controlling. Furthermore, microgravity conditions considerably enhance flame radiation by: (i) the build-up of combustion products in the high-temperature reaction zone which increases the gas radiation, and (ii) longer residence times make conditions appropriate for substantial amounts of soot to form which is also responsible for radiative heat loss. Thus, it is anticipated that radiative heat loss may eventually extinguish the "weak" (low burning rate per unit flame area) mu-g diffusion flame. Yet, space shuttle experiments on candle flames show that in an infinite ambient atmosphere, the hemispherical candle flame in mu-g will burn indefinitely. This may be because of the coupling between the fuel production rate and the flame via the heat-feedback mechanism for candle flames, flames over solids and fuel droplet flames. Thus, to focus only on the gas-phase phenomena leading to radiative extinction, aerodynamically stabilized gaseous diffusion flames are examined. This enables independent control of the fuel flow rate to help identify conditions under which radiative extinction occurs. Also, spherical geometry is chosen for the mu-g experiments and modeling because: (i) It reduces the complexity by making the problem one-dimensional; (ii) The spherical diffusion flame completely encloses the soot which is formed on the fuel rich side of the reaction zone. This increases the importance of flame radiation because now both soot and gaseous combustion products co-exist inside the high temperature spherical diffusion flame. (iii) For small fuel injection velocities, as is usually the case for a pyrolyzing solid, the diffusion flame in mu-g around the solid naturally develops spherical symmetry. Thus, spherical diffusion flames are of interest to fires in mu-g and identifying conditions that lead to radiation-induced extinction is important for spacecraft fire safety.

The fate of solid particles in the Jovian circumplanetary disk : Implications for the formation of the Galilean satellites

NASA Astrophysics Data System (ADS)

Ronnet, Thomas; Mousis, Olivier; Vernazza, Pierre

2016-10-01

The Galilean satellites are thought to have formed within an accretion disk surrounding Jupiter at the late stages of its formation. However, the structure of the gaseous disk, as well as the size and origin of the solids that eventually formed the satellites are yet to be constrained.Here we model an evolving gaseous disk around Jupiter and investigate the fate of solid particles of different sizes submitted to aerodynamic drag, turbulent diffusion, and heated by the surrounding gas. The motion of the solid particles is integrated in the (r-z) plane, taking into account dust settling and radial drift. The evolution of their ice-to-rock ratio is tracked when they cross the snowline and start to sublimate. Sublimation is coupled to the equations of motion as it changes the radius of the particle and consequently acts on the drag force. The I/R ratio then serves as a comparison to the observed bulk compositions of Io and Europa.

Numerical modeling on air quality in an urban environment with changes of the aspect ratio and wind direction.

PubMed

Yassin, Mohamed F

2013-06-01

Due to heavy traffic emissions within an urban environment, air quality during the last decade becomes worse year by year and hazard to public health. In the present work, numerical modeling of flow and dispersion of gaseous emissions from vehicle exhaust in a street canyon were investigated under changes of the aspect ratio and wind direction. The three-dimensional flow and dispersion of gaseous pollutants were modeled using a computational fluid dynamics (CFD) model which was numerically solved using Reynolds-averaged Navier-Stokes (RANS) equations. The diffusion flow field in the atmospheric boundary layer within the street canyon was studied for different aspect ratios (W/H=1/2, 3/4, and 1) and wind directions (θ=90°, 112.5°, 135°, and 157.5°). The numerical models were validated against wind tunnel results to optimize the turbulence model. The numerical results agreed well with the wind tunnel results. The simulation demonstrated that the minimum concentration at the human respiration height within the street canyon was on the windward side for aspect ratios W/H=1/2 and 1 and wind directions θ=112.5°, 135°, and 157.5°. The pollutant concentration level decreases as the wind direction and aspect ratio increase. The wind velocity and turbulence intensity increase as the aspect ratio and wind direction increase.

Analysis and Modeling of a Two-Phase Jet Pump of a Flow Boiling Test Facility for Aerospace Applications

NASA Technical Reports Server (NTRS)

Sherif, S. A.; Steadham, Justin M.

1996-01-01

Jet pumps are devices capable of pumping fluids to a higher pressure employing a nozzle/diffuser/mixing chamber combination. A primary fluid is usually allowed to pass through a converging-diverging nozzle where it can accelerate to supersonic speeds at the nozzle exit. The relatively high kinetic energy that the primary fluid possesses at the nozzle exit is accompanied by a low pressure region in order to satisfy Bernoulli's equation. The low pressure region downstream of the nozzle exit permits a secondary fluid to be entrained into and mixed with the primary fluid in a mixing chamber located downstream of the nozzle. Several combinations may exist in terms of the nature of the primary and secondary fluids in so far as whether they are single or two-phase fluids. Depending on this, the jet pump may be classified as gas/gas, gas/liquid, liquid/liquid, two-phase/liquid, or similar combinations. The mixing chamber serves to create a homogeneous single-phase or two-phase mixture which enters a diffuser where the high kinetic energy of the fluid is converted into pressure energy. If the fluid mixture entering the diffuser is in the supersonic flow regime, a normal shock wave usually develops inside the diffuser. If the fluid mixture is one that can easily change phase, a condensation shock would normally develop. Because of the overall rise in pressure in the diffuser as well as the additional rise in pressure across the shock layer, condensation becomes more likely. Associated with the pressure rise across the shock is a velocity reduction from the supersonic to the subsonic range. If the two-phase flow entering the diffuser is predominantly gaseous with liquid droplets suspended in it, it will transform into a predominantly liquid flow containing gaseous bubbles (bubbly flow) somewhere in the diffuser. While past researchers have been able to model the two-phase flow jet pump using the one-dimensional assumption with no shock waves and no phase change, there is no research known to the authors apart from that of Anand (1992) which accounted for condensation shocks. One of the objectives of this research effort is to develop a comprehensive model in which the effects of phase slip and inter-phase heat transfer as well as the wall friction and shock waves are accounted for. While this modeling effort is predominantly analytical in nature and is primarily intended to provide a parametric understanding of the jet pump performance under different operating scenarios, another parallel effort employing a commercial CFD code is also implemented. The latter effort is primarily intended to model an axisymmetric counterpart of the problem in question. The viability of using the CFD code to model a two-phase flow jet pump will be assessed by attempting to recreate some of the existing performance data of similar jet pumps. The code will eventually be used to generate the jet pump performance characteristics of several scenarios involving jet pump geometries as well as flow regimes in order to be able to determine an optimum design which would be suitable for a two-phase flow boiling test facility at NASA-Marshall. Because of the extensive nature of the analytical model developed, the following section will only provide very brief highlights of it, while leaving the details to a more complete report submitted to the NASA colleague. This report will also contain some of the simulation results obtained using the CFD code.

Process for producing enriched uranium having a .sup.235 U content of at least 4 wt. % via combination of a gaseous diffusion process and an atomic vapor laser isotope separation process to eliminate uranium hexafluoride tails storage

DOEpatents

Horton, James A.; Hayden, Jr., Howard W.

1995-01-01

An uranium enrichment process capable of producing an enriched uranium, having a .sup.235 U content greater than about 4 wt. %, is disclosed which will consume less energy and produce metallic uranium tails having a lower .sup.235 U content than the tails normally produced in a gaseous diffusion separation process and, therefore, eliminate UF.sub.6 tails storage and sharply reduce fluorine use. The uranium enrichment process comprises feeding metallic uranium into an atomic vapor laser isotope separation process to produce an enriched metallic uranium isotopic mixture having a .sup.235 U content of at least about 2 wt. % and a metallic uranium residue containing from about 0.1 wt. % to about 0.2 wt. % .sup.235 U; fluorinating this enriched metallic uranium isotopic mixture to form UF.sub.6 ; processing the resultant isotopic mixture of UF.sub.6 in a gaseous diffusion process to produce a final enriched uranium product having a .sup.235 U content of at least 4 wt. %, and up to 93.5 wt. % or higher, of the total uranium content of the product, and a low .sup.235 U content UF.sub.6 having a .sup.235 U content of about 0.71 wt. % of the total uranium content of the low .sup.235 U content UF.sub.6 ; and converting this low .sup.235 U content UF.sub.6 to metallic uranium for recycle to the atomic vapor laser isotope separation process.

Process for producing enriched uranium having a {sup 235}U content of at least 4 wt. % via combination of a gaseous diffusion process and an atomic vapor laser isotope separation process to eliminate uranium hexafluoride tails storage

DOEpatents

Horton, J.A.; Hayden, H.W. Jr.

1995-05-30

An uranium enrichment process capable of producing an enriched uranium, having a {sup 235}U content greater than about 4 wt. %, is disclosed which will consume less energy and produce metallic uranium tails having a lower {sup 235}U content than the tails normally produced in a gaseous diffusion separation process and, therefore, eliminate UF{sub 6} tails storage and sharply reduce fluorine use. The uranium enrichment process comprises feeding metallic uranium into an atomic vapor laser isotope separation process to produce an enriched metallic uranium isotopic mixture having a {sup 235} U content of at least about 2 wt. % and a metallic uranium residue containing from about 0.1 wt. % to about 0.2 wt. % {sup 235} U; fluorinating this enriched metallic uranium isotopic mixture to form UF{sub 6}; processing the resultant isotopic mixture of UF{sub 6} in a gaseous diffusion process to produce a final enriched uranium product having a {sup 235}U content of at least 4 wt. %, and up to 93.5 wt. % or higher, of the total uranium content of the product, and a low {sup 235}U content UF{sub 6} having a {sup 235}U content of about 0.71 wt. % of the total uranium content of the low {sup 235}U content UF{sub 6}; and converting this low {sup 235}U content UF{sub 6} to metallic uranium for recycle to the atomic vapor laser isotope separation process. 4 figs.

Occupational exposure to trichloroethylene and cancer risk for workers at the Paducah Gaseous Diffusion Plant.

PubMed

Bahr, Debra E; Aldrich, Timothy E; Seidu, Dazar; Brion, Gail M; Tollerud, David J; Muldoon, Susan; Reinhart, Nancy; Youseefagha, Ahmed; McKinney, Paul; Hughes, Therese; Chan, Caroline; Rice, Carol; Brewer, David E; Freyberg, Ronald W; Mohlenkamp, Adriane Moser; Hahn, Kristen; Hornung, Richard; Ho, Mona; Dastidar, Aniruddha; Freitas, Samantha; Saman, Daniel; Ravdal, Hege; Scutchfield, Douglas; Eger, Kenneth J; Minor, Steve

2011-03-01

The Paducah Gaseous Diffusion Plant (PGDP) became operational in 1952; it is located in the western part of Kentucky. We conducted a mortality study for adverse health effects that workers may have suffered while working at the plant, including exposures to chemicals. We studied a cohort of 6820 workers at the PGDP for the period 1953 to 2003; there were a total of 1672 deaths to cohort members. Trichloroethylene (TCE) is a specific concern for this workforce; exposure to TCE occurred primarily in departments that clean the process equipment. The Life Table Analysis System (LTAS) program developed by NIOSH was used to calculate the standardized mortality ratios for the worker cohort and standardized rate ratio relative to exposure to TCE (the U.S. population is the referent for ageadjustment). LTAS calculated a significantly low overall SMR for these workers of 0.76 (95% CI: 0.72-0.79). A further review of three major cancers of interest to Kentucky produced significantly low SMR for trachea, bronchus, lung cancer (0.75, 95% CI: 0.72-0.79) and high SMR for Non-Hodgkin's lymphoma (NHL) (1.49, 95% CI: 1.02-2.10). No significant SMR was observed for leukemia and no significant SRRs were observed for any disease. Both the leukemia and lung cancer results were examined and determined to reflect regional mortality patterns. However, the Non-Hodgkin's Lymphoma finding suggests a curious amplification when living cases are included with the mortality experience. Further examination is recommended of this recurrent finding from all three U.S. Gaseous Diffusion plants.

Overhead Projector Demonstrations.

ERIC Educational Resources Information Center

Kolb, Doris, Ed.

1989-01-01

Described are three chemistry demonstrations: (1) a simple qualitative technique for taste pattern recognition in structure-activity relationships; (2) a microscale study of gaseous diffusion using bleach, HCl, ammonia, and phenolphthalein; and (3) the rotation of polarized light by stereoisomers of limonene. (MVL)

DOE-EM Science of Safety Robotics Challenge

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

Rimando, Rodrigo; Watts, Alex; Bobbitt, John

During the week of August 22nd, 2016, over 150 technologists, stakeholders, and Department of Energy, Office of Environmental Management workers, met at DOE’s Portsmouth Gaseous Diffusion Plant in Ohio, for the EM Science of Safety Robotics Challenge.

Status report on CIP/CUP progress

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

Larkin, W.J.

1975-01-01

Work on the Cascade Improvement Program (CIP) and the Cascade Uprating Program (CUP) continues basically on schedule. When completed the productive capability of the gaseous diffusion facilities at Paducah, Oak Ridge, and Portsmouth will be increased by 60 percent. (JGB)

Computed tomography measurement of gaseous fuel concentration by infrared laser light absorption

NASA Astrophysics Data System (ADS)

Kawazoe, Hiromitsu; Inagaki, Kazuhisa; Emi, Y.; Yoshino, Fumio

1997-11-01

A system to measure gaseous hydrocarbon distributions was devised, which is based on IR light absorption by C-H stretch mode of vibration and computed tomography method. It is called IR-CT method in the paper. Affection of laser light power fluctuation was diminished by monitoring source light intensity by the second IR light detector. Calibration test for methane fuel was carried out to convert spatial data of line absorption coefficient into quantitative methane concentration. This system was applied to three flow fields. The first is methane flow with lifted flame which is generated by a gourd-shaped fuel nozzle. Feasibility of the IR-CT method was confirmed through the measurement. The second application is combustion field with diffusion flame. Calibration to determine absorptivity was undertaken, and measured line absorption coefficient was converted spatial fuel concentration using corresponding temperature data. The last case is modeled in cylinder gas flow of internal combustion engine, where gaseous methane was led to the intake valve in steady flow state. The fuel gas flow simulates behavior of gaseous gasoline which is evaporated at intake valve tulip. Computed tomography measurement of inner flow is essentially difficult because of existence of surrounding wall. In this experiment, IR laser beam was led to planed portion by IR light fiber. It is found that fuel convection by airflow takes great part in air-fuel mixture formation and the developed IR-CT system to measure fuel concentration is useful to analyze air-fuel mixture formation process and to develop new combustors.

Effective gaseous diffusion coefficients of select ultra-fine, super-fine and medium grain nuclear graphite

DOE PAGES

Kane, Joshua J.; Matthews, Austin C.; Orme, Christopher J.; ...

2018-05-05

Understanding “Where?” and “How much?” oxidation has occurred in a nuclear graphite component is critical to predicting any deleterious effects to physical, mechanical, and thermal properties. A key factor in answering these questions is characterizing the effective mass transport rates of gas species in nuclear graphites. Effective gas diffusion coefficients were determined for twenty-six graphite specimens spanning six modern grades of nuclear graphite. A correlation was established for the majority of grades examined allowing a reasonable estimate of the effective diffusion coefficient to be determined purely from an estimate of total porosity. The importance of Knudsen diffusion to the measuredmore » diffusion coefficients is also shown for modern grades. Furthermore, Knudsen diffusion has not historically been considered to contribute to measured diffusion coefficients of nuclear graphite.« less

Effective gaseous diffusion coefficients of select ultra-fine, super-fine and medium grain nuclear graphite

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

Kane, Joshua J.; Matthews, Austin C.; Orme, Christopher J.

Understanding “Where?” and “How much?” oxidation has occurred in a nuclear graphite component is critical to predicting any deleterious effects to physical, mechanical, and thermal properties. A key factor in answering these questions is characterizing the effective mass transport rates of gas species in nuclear graphites. Effective gas diffusion coefficients were determined for twenty-six graphite specimens spanning six modern grades of nuclear graphite. A correlation was established for the majority of grades examined allowing a reasonable estimate of the effective diffusion coefficient to be determined purely from an estimate of total porosity. The importance of Knudsen diffusion to the measuredmore » diffusion coefficients is also shown for modern grades. Furthermore, Knudsen diffusion has not historically been considered to contribute to measured diffusion coefficients of nuclear graphite.« less

Effect of Normobaric versus Hypobaric Oxygenation on Gaseous Microemboli Removal in a Diffusion Membrane Oxygenator: An In Vitro Comparison

PubMed Central

Schuldes, Matthew; Riley, Jeffrey B.; Francis, Stephen G.; Clingan, Sean

2016-01-01

Abstract: Gaseous microemboli (GME) are an abnormal physiological occurrence during cardiopulmonary bypass and extracorporeal membrane oxygenation (ECMO). Several studies have correlated negative sequelae with exposure to increased amounts of GME. Hypobaric oxygenation is effective at eliminating GME in hollow-fiber microporous membrane oxygenators. However, hollow-fiber diffusion membrane oxygenators, which are commonly used for ECMO, have yet to be validated. The purpose of this study was to determine if hypobaric oxygenation, compared against normobaric oxygenation, can reduce introduced GME when used on diffusion membrane oxygenators. Comparison of a sealed Quadrox-iD with hypobaric sweep gas (.67 atm) vs. an unmodified Quadrox-iD with normal atmospheric sweep gas (1 atm) in terms of GME transmission during continuous air introduction (50 mL/min) in a recirculating in vitro circuit, over a range of flow rates (3.5, 5 L/min) and crystalloid prime temperatures (37°C, 28°C, and 18°C). GME were measured using three EDAC Doppler probes positioned pre-oxygenator, post-oxygenator, and at the arterial cannula. Hypobaric oxygenation vs. normobaric oxygenation significantly reduced hollow-fiber diffusion membrane oxygenator GME transmission at all combination of pump flows and temperatures. There was further significant reduction in GME count between the oxygenator outlet and at the arterial cannula. Hypobaric oxygenation used on hollow-fiber diffusion membrane oxygenators can further reduce GME compared to normobaric oxygenation. This technique may be a safe approach to eliminate GME during ECMO. PMID:27729706

Spectral separation of gaseous fluorocarbon mixtures and measurement of diffusion constants by 19F gas phase DOSY NMR.

PubMed

Marchione, Alexander A; McCord, Elizabeth F

2009-11-01

Diffusion-ordered (DOSY) NMR techniques have for the first time been applied to the spectral separation of mixtures of fluorinated gases by diffusion rates. A mixture of linear perfluoroalkanes from methane to hexane was readily separated at 25 degrees C in an ordinary experimental setup with standard DOSY pulse sequences. Partial separation of variously fluorinated ethanes was also achieved. The constants of self-diffusion of a set of pure perfluoroalkanes were obtained at pressures from 0.25 to 1.34 atm and temperatures from 20 to 122 degrees C. Under all conditions there was agreement within 20% of experimental self-diffusion constant D and values calculated by the semiempirical Fuller method.

Passive sampling for the isotopic fingerprinting of atmospheric mercury

NASA Astrophysics Data System (ADS)

Bergquist, B. A.; MacLagan, D.; Spoznar, N.; Kaplan, R.; Chandan, P.; Stupple, G.; Zimmerman, L.; Wania, F.; Mitchell, C. P. J.; Steffen, A.; Monaci, F.; Derry, L. A.

2017-12-01

Recent studies show that there are variations in the mercury (Hg) isotopic signature of atmospheric Hg, which demonstrates the potential for source tracing and improved understanding of atmospheric cycling of Hg. However, current methods for both measuring atmospheric Hg and collecting enough atmospheric Hg for isotopic analyses require expensive instruments that need power and expertise. Additionally, methods for collecting enough atmospheric Hg for isotopic analysis require pumping air through traps for long periods (weeks and longer). Combining a new passive atmospheric sampler for mercury (Hg) with novel Hg isotopic analyses will allow for the application of stable Hg isotopes to atmospheric studies of Hg. Our group has been testing a new passive sampler for gaseous Hg that relies on the diffusion of Hg through a diffusive barrier and adsorption onto a sulphur-impregnated activated carbon sorbent. The benefit of this passive sampler is that it is low cost, requires no power, and collects gaseous Hg for up to one year with linear, well-defined uptake, which allows for reproducible and accurate measurements of atmospheric gaseous Hg concentrations ( 8% uncertainty). As little as one month of sampling is often adequate to collect sufficient Hg for isotopic analysis at typical background concentrations. Experiments comparing the isotopic Hg signature in activated carbon samples using different approaches (i.e. by passive diffusion, by passive diffusion through diffusive barriers of different thickness, by active pumping) and at different temperatures confirm that the sampling process itself does not impose mass-independent fractionation (MIF). However, sampling does result in a consistent and thus correctable mass-dependent fractionation (MDF) effect. Therefore, the sampler preserves Hg MIF with very high accuracy and precision, which is necessary for atmospheric source tracing, and reasonable MDF can be estimated with some increase in error. In addition to experimental work, initial field data will be presented including a transect of increasing distance from a known strong source of Hg (Mt. Amiata mine, Italy), downwind of Kilauea volcano in Hawaii, and several other locales including the Arctic station Alert and various sites across Ontario, Canada.

An Experimental and Theoretical Study of Radiative Extinction of Diffusion Flames

NASA Technical Reports Server (NTRS)

Atreya, Arvind

1995-01-01

The objective of this research was to experimentally and theoretically investigate the radiation-induced extinction of gaseous diffusion flames in microgravity. The microgravity conditions were required because radiation-induced extinction is generally not possible in 1-g but is highly likely in microgravity. In 1-g, the flame-generated particulates (e.g. soot) and gaseous combustion products that are responsible for flame radiation, are swept away from the high temperature reaction zone by the buoyancy-induced flow and a steady state is developed. In microgravity, however, the absence of buoyancy-induced flow which transports the fuel and the oxidizer to the combustion zone and removes the hot combustion products from it enhances the flame radiation due to: (1) transient build-up of the combustion products in the flame zone which increases the gas radiation, and (2) longer residence time makes conditions appropriate for substantial amounts of soot to form which is usually responsible for most of the radiative heat loss. Numerical calculations conducted during the course of this work show that even non-radiative flames continue to become "weaker" (diminished burning rate per unit flame area) due to reduced rates of convective and diffusive transport. Thus, it was anticipated that radiative heat loss may eventually extinguish the already "weak" microgravity diffusion flame. While this hypothesis appears convincing and our numerical calculations support it, experiments for a long enough microgravity time could not be conducted during the course of this research to provide an experimental proof. Space shuttle experiments on candle flames show that in an infinite ambient atmosphere, the hemispherical candle flame in microgravity will burn indefinitely. It was hoped that radiative extinction can be experimentally shown by the aerodynamically stabilized gaseous diffusion flames where the fuel supply rate was externally controlled. While substantial progress toward this goal was made during this project, identifying the experimental conditions for which radiative extinction occurs for various fuels requires further study. Details concerning this research which are discussed in published articles are included in the appendices.

DOE-EM Science of Safety Robotics Challenge

ScienceCinema

Rimando, Rodrigo; Watts, Alex; Bobbitt, John; McLaughlin, Doug; Quigley, Morgan; Gladwell, Scott; McLoughlin, Mike; Kinnamon, Tony; Garcia, Joe; Ansari, Alex; Voyles, Richard; Chambers, David; Pryor, Mitch; Workman, Theresa; Mehling, Joshua; Browning, Kimberly; Deuel, Jake; Profitt, Bryan; Reibold, Marty

2018-06-12

During the week of August 22nd, 2016, over 150 technologists, stakeholders, and Department of Energy, Office of Environmental Management workers, met at DOE’s Portsmouth Gaseous Diffusion Plant in Ohio, for the EM Science of Safety Robotics Challenge.

10 CFR 76.5 - Communications.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Communications. 76.5 Section 76.5 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.5 Communications. Except where otherwise specified, all communications and reports concerning the regulations in...

10 CFR 76.5 - Communications.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Communications. 76.5 Section 76.5 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.5 Communications. Except where otherwise specified, all communications and reports concerning the regulations in...

Locally enhanced sampling molecular dynamics study of the dioxygen transport in human cytoglobin.

PubMed

Orlowski, Slawomir; Nowak, Wieslaw

2007-07-01

Cytoglobin (Cyg)--a new member of the vertebrate heme globin family--is expressed in many tissues of the human body but its physiological role is still unclear. It may deliver oxygen under hypoxia, serve as a scavenger of reactive species or be involved in collagen synthesis. This protein is usually six-coordinated and binds oxygen by a displacement of the distal HisE7 imidazole. In this paper, the results of 60 ns molecular dynamics (MD) simulations of dioxygen diffusion inside Cyg matrix are discussed. In addition to a classical MD trajectory, an approximate Locally Enhanced Sampling (LES) method has been employed. Classical diffusion paths were carefully analyzed, five cavities in dynamical structures were determined and at least four distinct ligand exit paths were identified. The most probable exit/entry path is connected with a large tunnel present in Cyg. Several residues that are perhaps critical for kinetics of small gaseous diffusion were discovered. A comparison of gaseous ligand transport in Cyg and in the most studied heme protein myoglobin is presented. Implications of efficient oxygen transport found in Cyg to its possible physiological role are discussed.

Polydisperse effects in jet spray flames

NASA Astrophysics Data System (ADS)

Weinberg, Noam; Greenberg, J. Barry

2018-01-01

A laminar jet polydisperse spray diffusion flame is analysed mathematically for the first time using an extension of classical similarity solutions for gaseous jet flames. The analysis enables a comparison to be drawn between conditions for flame stability or flame blow-out for purely gaseous flames and for spray flames. It is found that, in contrast to the Schmidt number criteria relevant to gas flames, droplet size and initial spray polydispersity play a critical role in determining potential flame scenarios. Some qualitative agreement for lift-off height is found when comparing predictions of the theory and sparse independent experimental evidence from the literature.

Laser-Excited Luminescent Tracers for Planar Concentration Measurements in Gaseous Jets

NASA Astrophysics Data System (ADS)

Lozano, Antonio

Tracers currently used in planar laser-induced fluorescence concentration measurements are not ideal for some experimental conditions, e.g., non-reacting turbulent gaseous flows at standard temperature and pressure. In this work, a number of chemicals have been evaluated, through consideration of their physical and photophysical properties, for use as luminescent concentration markers in turbulent gaseous flows. Two selected substances, biacetyl and acetone, have been studied in more detail. Acetone PLIF concentration images have been acquired in a non-reacting air jet, and the results have been compared to similar images obtained seeding with biacetyl. Acetone has proven to be a superior tracer when imaging fluorescence emission. Acetone has also been used as a fuel marker in hydrogen and methane diffusion flames. This single -laser technique enables simultaneous recording of the acetone and OH fluorescence emissions, as well as Mie scattering from ambient air dust particles. Acetone-sensitized, collisionally-induced biacetyl phosphorescence has been used to visualize molecular mixing in gaseous flows. Initial attempts to produce quantitative results with this method through simultaneous imaging of acetone fluorescence and collisionally-induced biacetyl emission, are described. Using laser-induced biacetyl phosphorescence imaging, a data set of cross-cut concentration images has been acquired in a nitrogen coflowing jet (Re = 5,000). The images have been statistically analyzed. Very simple models of the instantaneous concentration profile have been compared to the experimental data. Of all the tested models, a paraboloid has resulted to be the best approximation to the instantaneous 2-D profile. Finally, an experiment to study jet mixing in crossflow using acetone PLIF imaging has been designed. The flow facility has been constructed, and preliminary images obtained with a high quantum efficiency, thinned CCD detector have revealed the presence of jet structures inside the wake region that appear to be dependent on the jet/crossflow velocity ratio.

Stem Hydraulic Conductivity depends on the Pressure at Which It Is Measured and How This Dependence Can Be Used to Assess the Tempo of Bubble Pressurization in Recently Cavitated Vessels1[OPEN

PubMed Central

Liu, Jinyu; Tyree, Melvin T.

2015-01-01

Cavitation of water in xylem vessels followed by embolism formation has been authenticated for more than 40 years. Embolism formation involves the gradual buildup of bubble pressure (air) to atmospheric pressure as demanded by Henry’s law of equilibrium between gaseous and liquid phases. However, the tempo of pressure increase has not been quantified. In this report, we show that the rate of pressurization of embolized vessels is controlled by both fast and slow kinetics, where both tempos are controlled by diffusion but over different spatial scales. The fast tempo involves a localized diffusion from endogenous sources: over a distance of about 0.05 mm from water-filled wood to the nearest embolized vessels; this process, in theory, should take <2 min. The slow tempo involves diffusion of air from exogenous sources (outside the stem). The latter diffusion process is slower because of the increased distance of diffusion of up to 4 mm. Radial diffusion models and experimental measurements both confirm that the average time constant is >17 h, with complete equilibrium requiring 1 to 2 d. The implications of these timescales for the standard methods of measuring percentage loss of hydraulic conductivity are discussed in theory and deserve more research in future. PMID:26468516

Stem Hydraulic Conductivity depends on the Pressure at Which It Is Measured and How This Dependence Can Be Used to Assess the Tempo of Bubble Pressurization in Recently Cavitated Vessels.

PubMed

Wang, Yujie; Liu, Jinyu; Tyree, Melvin T

2015-12-01

Cavitation of water in xylem vessels followed by embolism formation has been authenticated for more than 40 years. Embolism formation involves the gradual buildup of bubble pressure (air) to atmospheric pressure as demanded by Henry's law of equilibrium between gaseous and liquid phases. However, the tempo of pressure increase has not been quantified. In this report, we show that the rate of pressurization of embolized vessels is controlled by both fast and slow kinetics, where both tempos are controlled by diffusion but over different spatial scales. The fast tempo involves a localized diffusion from endogenous sources: over a distance of about 0.05 mm from water-filled wood to the nearest embolized vessels; this process, in theory, should take <2 min. The slow tempo involves diffusion of air from exogenous sources (outside the stem). The latter diffusion process is slower because of the increased distance of diffusion of up to 4 mm. Radial diffusion models and experimental measurements both confirm that the average time constant is >17 h, with complete equilibrium requiring 1 to 2 d. The implications of these timescales for the standard methods of measuring percentage loss of hydraulic conductivity are discussed in theory and deserve more research in future. © 2015 American Society of Plant Biologists. All Rights Reserved.

10 CFR 76.87 - Technical safety requirements.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Technical safety requirements. 76.87 Section 76.87 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.87 Technical safety requirements. (a) The Corporation shall establish technical safety requirements. In...

10 CFR 76.6 - Interpretations.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Interpretations. 76.6 Section 76.6 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.6 Interpretations. Except as specifically authorized by the Commission in writing, no interpretation of the meaning...

10 CFR 76.87 - Technical safety requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Technical safety requirements. 76.87 Section 76.87 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.87 Technical safety requirements. (a) The Corporation shall establish technical safety requirements. In...

10 CFR 76.6 - Interpretations.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Interpretations. 76.6 Section 76.6 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.6 Interpretations. Except as specifically authorized by the Commission in writing, no interpretation of the meaning...

10 CFR 76.31 - Periodic application requirement.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Periodic application requirement. 76.31 Section 76.31 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.31 Periodic application requirement. The Corporation shall periodically apply to the Commission...

10 CFR 76.6 - Interpretations.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Interpretations. 76.6 Section 76.6 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.6 Interpretations. Except as specifically authorized by the Commission in writing, no interpretation of the meaning...

10 CFR 76.31 - Periodic application requirement.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Periodic application requirement. 76.31 Section 76.31 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.31 Periodic application requirement. The Corporation shall periodically apply to the Commission...

10 CFR 76.87 - Technical safety requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Technical safety requirements. 76.87 Section 76.87 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.87 Technical safety requirements. (a) The Corporation shall establish technical safety requirements. In...

10 CFR 76.120 - Reporting requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Reporting requirements. 76.120 Section 76.120 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.120 Reporting requirements. (a) Immediate report. The Corporation shall notify the NRC...

10 CFR 76.6 - Interpretations.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Interpretations. 76.6 Section 76.6 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.6 Interpretations. Except as specifically authorized by the Commission in writing, no interpretation of the meaning...

10 CFR 76.120 - Reporting requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Reporting requirements. 76.120 Section 76.120 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.120 Reporting requirements. (a) Immediate report. The Corporation shall notify the NRC...

10 CFR 76.87 - Technical safety requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Technical safety requirements. 76.87 Section 76.87 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.87 Technical safety requirements. (a) The Corporation shall establish technical safety requirements. In...

10 CFR 76.31 - Periodic application requirement.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Periodic application requirement. 76.31 Section 76.31 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.31 Periodic application requirement. The Corporation shall periodically apply to the Commission...

10 CFR 76.87 - Technical safety requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Technical safety requirements. 76.87 Section 76.87 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.87 Technical safety requirements. (a) The Corporation shall establish technical safety requirements. In...

10 CFR 76.120 - Reporting requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Reporting requirements. 76.120 Section 76.120 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.120 Reporting requirements. (a) Immediate report. The Corporation shall notify the NRC...

10 CFR 76.31 - Periodic application requirement.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Periodic application requirement. 76.31 Section 76.31 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.31 Periodic application requirement. The Corporation shall periodically apply to the Commission...

10 CFR 76.6 - Interpretations.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Interpretations. 76.6 Section 76.6 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.6 Interpretations. Except as specifically authorized by the Commission in writing, no interpretation of the meaning...

10 CFR 76.31 - Periodic application requirement.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Periodic application requirement. 76.31 Section 76.31 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.31 Periodic application requirement. The Corporation shall periodically apply to the Commission...

Investigation of the radiological safety concerns and medical history of the late Joseph T. Harding, former employee of the Paducah Gaseous Diffusion Plant

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

Vallario, E.J.; Wolfe, H.R.

1981-03-01

An ex-employee's claims that inadequate enforcement of radiation safety regulations allowed excess radiation exposure thereby causing his deteriorating health was not substantiated by a thorough investigation.

The influence of vertical sorbed phase transport on the fate of organic chemicals in surface soils.

PubMed

McLachlan, Michael S; Czub, Gertje; Wania, Frank

2002-11-15

Gaseous exchange between surface soil and the atmosphere is an important process in the environmental fate of many chemicals. It was hypothesized that this process is influenced by vertical transport of chemicals sorbed to soil particles. Vertical sorbed phase transport in surface soils occurs by many processes such as bioturbation, cryoturbation, and erosion into cracks formed by soil drying. The solution of the advection/diffusion equation proposed by Jury et al. to describe organic chemical fate in a uniformly contaminated surface soil was modified to include vertical sorbed phase transport This process was modeled using a sorbed phase diffusion coefficient, the value of which was derived from soil carbon mass balances in the literature. The effective diffusivity of the chemical in a typical soil was greater in the modified model than in the model without sorbed phase transport for compounds with log K(OW) > 2 and log K(OA) > 6. Within this chemical partitioning space, the rate of volatilization from the surface soil was larger in the modified model than in the original model by up to a factor of 65. The volatilization rate was insensitive to the value of the sorbed phase diffusion coefficient throughout much of this chemical partitioning space, indicating that the surface soil layer was essentially well-mixed and that the mass transfer coefficient was determined by diffusion through the atmospheric boundary layer only. When this process was included in a non-steady-state regional multimedia chemical fate model running with a generic emissions scenario to air, the predicted soil concentrations increased by upto a factor of 25,whilethe air concentrations decreased by as much as a factor of approximately 3. Vertical sorbed phase transport in the soil thus has a major impact on predicted air and soil concentrations, the state of equilibrium, and the direction and magnitude of the chemical flux between air and soil. It is a key process influencing the environmental fate of persistent organic pollutants (POPs).

Impact of height and shape of building roof on air quality in urban street canyons

NASA Astrophysics Data System (ADS)

Yassin, Mohamed F.

2011-09-01

A building's roof shape and roof height play an important role in determining pollutant concentrations from vehicle emissions and its complex flow patterns within urban street canyons. The impact of the roof shape and height on wind flow and dispersion of gaseous pollutants from vehicle exhaust within urban canyons were investigated numerically using a Computational Fluid Dynamics (CFD) model. Two-dimensional flow and dispersion of gaseous pollutants were analyzed using standard κ- ɛ turbulence model, which was numerically solved based on Reynolds Averaged Navier-Stokes (RANS) equations. The diffusion fields in the urban canyons were examined with three roof heights ( Z H/ H = 0.17, 0.33 and 0.5) and five roof shapes: (1) flat-shaped roof, (2) slanted-shaped roof, (3) downwind wedge-shaped roof, (4) upwind wedge-shaped roof, and (5) trapezoid-shaped roof. The numerical model was validated against the wind tunnels results in order to optimize the turbulence model. The numerical simulations agreed reasonably with the wind tunnel results. The results obtained indicated that the pollutant concentration increased as the roof height decreases. It also decreased with the slanted and trapezoid-shaped roofs but increased with the flat-shaped roof. The pollutant concentration distributions simulated in the present work, indicated that the variability of the roof shapes and roof heights of the buildings are important factors for estimating air quality within urban canyons.

OCCUPATIONAL EXPOSURE TO TRICHLOROETHYLENE AND CANCER RISK FOR WORKERS AT THE PADUCAH GASEOUS DIFFUSION PLANT

PubMed Central

BAHR, DEBRA E.; ALDRICH, TIMOTHY E.; SEIDU, DAZAR; BRION, GAIL M.; TOLLERUD, DAVID J.; MULDOON, SUSAN; REINHART, NANCY; YOUSEEFAGHA, AHMED; MCKINNEY, PAUL; HUGHES, THERESE; CHAN, CAROLINE; RICE, CAROL; BREWER, DAVID E.; FREYBERG, RONALD W.; MOHLENKAMP, ADRIANE MOSER; HAHN, KRISTEN; HORNUNG, RICHARD; HO, MONA; DASTIDAR, ANIRUDDHA; FREITAS, SAMANTHA; SAMAN, DANIEL; RAVDAL, HEGE; SCUTCHFIELD, DOUGLAS; EGER, KENNETH J.; MINOR, STEVE

2016-01-01

Objective The Paducah Gaseous Diffusion Plant (PGDP) became operational in 1952; it is located in the western part of Kentucky. We conducted a mortality study for adverse health effects that workers may have suffered while working at the plant, including exposures to chemicals. Materials and Methods We studied a cohort of 6820 workers at the PGDP for the period 1953 to 2003; there were a total of 1672 deaths to cohort members. Trichloroethylene (TCE) is a specific concern for this workforce; exposure to TCE occurred primarily in departments that clean the process equipment. The Life Table Analysis System (LTAS) program developed by NIOSH was used to calculate the standardized mortality ratios for the worker cohort and standardized rate ratio relative to exposure to TCE (the U.S. population is the referent for age-adjustment). LTAS calculated a significantly low overall SMR for these workers of 0.76 (95% CI: 0.72–0.79). A further review of three major cancers of interest to Kentucky produced significantly low SMR for trachea, bronchus, lung cancer (0.75, 95% CI: 0.72–0.79) and high SMR for Non-Hodgkin's lymphoma (NHL) (1.49, 95% CI: 1.02–2.10). Results No significant SMR was observed for leukemia and no significant SRRs were observed for any disease. Both the leukemia and lung cancer results were examined and determined to reflect regional mortality patterns. However, the Non-Hodgkin's Lymphoma finding suggests a curious amplification when living cases are included with the mortality experience. Conclusions Further examination is recommended of this recurrent finding from all three U.S. Gaseous Diffusion plants. PMID:21468904

10 CFR 76.121 - Inspections.

Code of Federal Regulations, 2010 CFR

2010-01-01

... REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.121 Inspections. (a) The Corporation shall afford to the Commission opportunity to inspect the premises and plants... the Corporation. The office must be convenient to and have full access to the plant, and must provide...

Thermophysical properties of gas phase uranium tetrafluoride

NASA Technical Reports Server (NTRS)

Watanabe, Yoichi; Anghaie, Samim

1993-01-01

Thermophysical data of gaseous uranium tetrafluoride (UF4) are theoretically obtained by taking into account dissociation of molecules at high temperatures (2000-6000 K). Determined quantities include specific heat, optical opacity, diffusion coefficient, viscosity, and thermal conductivity. A computer program is developed for the calculation.

10 CFR 76.93 - Quality assurance.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Quality assurance. 76.93 Section 76.93 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.93 Quality assurance. The Corporation shall establish, maintain, and execute a quality assurance program satisfying each of...

10 CFR 76.7 - Employee protection.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Employee protection. 76.7 Section 76.7 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.7 Employee protection. (a) Discrimination by the Corporation, a contractor, or a subcontractor of the...

10 CFR 76.89 - Criticality accident requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Criticality accident requirements. 76.89 Section 76.89 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.89 Criticality accident requirements. (a) The Corporation must maintain and operate a criticality monitoring and...

10 CFR 76.89 - Criticality accident requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Criticality accident requirements. 76.89 Section 76.89 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.89 Criticality accident requirements. (a) The Corporation must maintain and operate a criticality monitoring and...

10 CFR 76.72 - Miscellaneous procedural matters.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Miscellaneous procedural matters. 76.72 Section 76.72 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.72 Miscellaneous procedural matters. (a) The filing of any petitions for review or any responses...

10 CFR 76.131 - Violations.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Violations. 76.131 Section 76.131 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Enforcement § 76.131 Violations. (a) The Commission may obtain an injunction or other court order to prevent a violation of the...

10 CFR 76.51 - Conditions of certification.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Conditions of certification. 76.51 Section 76.51 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.51 Conditions of certification. The Corporation shall comply with the certificate of compliance, any approved...

10 CFR 76.93 - Quality assurance.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Quality assurance. 76.93 Section 76.93 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.93 Quality assurance. The Corporation shall establish, maintain, and execute a quality assurance program satisfying each of...

10 CFR 76.72 - Miscellaneous procedural matters.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Miscellaneous procedural matters. 76.72 Section 76.72 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.72 Miscellaneous procedural matters. (a) The filing of any petitions for review or any responses...

10 CFR 76.121 - Inspections.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Inspections. 76.121 Section 76.121 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.121 Inspections. (a) The Corporation shall afford to the Commission opportunity to inspect the premises and plants...

10 CFR 76.72 - Miscellaneous procedural matters.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Miscellaneous procedural matters. 76.72 Section 76.72 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.72 Miscellaneous procedural matters. (a) The filing of any petitions for review or any responses...

10 CFR 76.131 - Violations.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Violations. 76.131 Section 76.131 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Enforcement § 76.131 Violations. (a) The Commission may obtain an injunction or other court order to prevent a violation of the...

10 CFR 76.23 - Specific exemptions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Specific exemptions. 76.23 Section 76.23 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.23 Specific exemptions. The Commission may, upon its own initiative or upon application of the Corporation...

10 CFR 76.93 - Quality assurance.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Quality assurance. 76.93 Section 76.93 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.93 Quality assurance. The Corporation shall establish, maintain, and execute a quality assurance program satisfying each of...

10 CFR 76.131 - Violations.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Violations. 76.131 Section 76.131 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Enforcement § 76.131 Violations. (a) The Commission may obtain an injunction or other court order to prevent a violation of the...

10 CFR 76.95 - Training.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Training. 76.95 Section 76.95 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.95 Training. A training program must be established, implemented, and maintained for individuals relied upon to operate, maintain, or...

10 CFR 76.121 - Inspections.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Inspections. 76.121 Section 76.121 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.121 Inspections. (a) The Corporation shall afford to the Commission opportunity to inspect the premises and plants...

10 CFR 76.7 - Employee protection.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Employee protection. 76.7 Section 76.7 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.7 Employee protection. (a) Discrimination by the Corporation, a contractor, or a subcontractor of the...

10 CFR 76.131 - Violations.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Violations. 76.131 Section 76.131 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Enforcement § 76.131 Violations. (a) The Commission may obtain an injunction or other court order to prevent a violation of the...

10 CFR 76.23 - Specific exemptions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Specific exemptions. 76.23 Section 76.23 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.23 Specific exemptions. The Commission may, upon its own initiative or upon application of the Corporation...

10 CFR 76.72 - Miscellaneous procedural matters.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Miscellaneous procedural matters. 76.72 Section 76.72 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.72 Miscellaneous procedural matters. (a) The filing of any petitions for review or any responses...

10 CFR 76.72 - Miscellaneous procedural matters.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Miscellaneous procedural matters. 76.72 Section 76.72 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.72 Miscellaneous procedural matters. (a) The filing of any petitions for review or any responses...

10 CFR 76.95 - Training.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Training. 76.95 Section 76.95 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.95 Training. A training program must be established, implemented, and maintained for individuals relied upon to operate, maintain, or...

10 CFR 76.89 - Criticality accident requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Criticality accident requirements. 76.89 Section 76.89 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.89 Criticality accident requirements. (a) The Corporation must maintain and operate a criticality monitoring and...

10 CFR 76.93 - Quality assurance.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Quality assurance. 76.93 Section 76.93 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.93 Quality assurance. The Corporation shall establish, maintain, and execute a quality assurance program satisfying each of...

10 CFR 76.51 - Conditions of certification.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Conditions of certification. 76.51 Section 76.51 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.51 Conditions of certification. The Corporation shall comply with the certificate of compliance, any approved...

10 CFR 76.51 - Conditions of certification.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Conditions of certification. 76.51 Section 76.51 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.51 Conditions of certification. The Corporation shall comply with the certificate of compliance, any approved...

10 CFR 76.89 - Criticality accident requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Criticality accident requirements. 76.89 Section 76.89 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.89 Criticality accident requirements. (a) The Corporation must maintain and operate a criticality monitoring and...

10 CFR 76.51 - Conditions of certification.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Conditions of certification. 76.51 Section 76.51 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.51 Conditions of certification. The Corporation shall comply with the certificate of compliance, any approved...

10 CFR 76.131 - Violations.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Violations. 76.131 Section 76.131 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Enforcement § 76.131 Violations. (a) The Commission may obtain an injunction or other court order to prevent a violation of the...

10 CFR 76.23 - Specific exemptions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Specific exemptions. 76.23 Section 76.23 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.23 Specific exemptions. The Commission may, upon its own initiative or upon application of the Corporation...

10 CFR 76.121 - Inspections.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Inspections. 76.121 Section 76.121 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.121 Inspections. (a) The Corporation shall afford to the Commission opportunity to inspect the premises and plants...

10 CFR 76.7 - Employee protection.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Employee protection. 76.7 Section 76.7 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.7 Employee protection. (a) Discrimination by the Corporation, a contractor, or a subcontractor of the...

10 CFR 76.89 - Criticality accident requirements.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Criticality accident requirements. 76.89 Section 76.89 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.89 Criticality accident requirements. (a) The Corporation must maintain and operate a criticality monitoring and...

10 CFR 76.23 - Specific exemptions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Specific exemptions. 76.23 Section 76.23 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.23 Specific exemptions. The Commission may, upon its own initiative or upon application of the Corporation...

10 CFR 76.121 - Inspections.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Inspections. 76.121 Section 76.121 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.121 Inspections. (a) The Corporation shall afford to the Commission opportunity to inspect the premises and plants...

10 CFR 76.95 - Training.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Training. 76.95 Section 76.95 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.95 Training. A training program must be established, implemented, and maintained for individuals relied upon to operate, maintain, or...

10 CFR 76.51 - Conditions of certification.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Conditions of certification. 76.51 Section 76.51 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.51 Conditions of certification. The Corporation shall comply with the certificate of compliance, any approved...

10 CFR 76.93 - Quality assurance.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Quality assurance. 76.93 Section 76.93 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.93 Quality assurance. The Corporation shall establish, maintain, and execute a quality assurance program satisfying each of...

10 CFR 76.95 - Training.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Training. 76.95 Section 76.95 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.95 Training. A training program must be established, implemented, and maintained for individuals relied upon to operate, maintain, or...

10 CFR 76.23 - Specific exemptions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Specific exemptions. 76.23 Section 76.23 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.23 Specific exemptions. The Commission may, upon its own initiative or upon application of the Corporation...

An interim report to the manager of the Paducah Gaseous Diffusion Plant from the Paducah Environmental Advisory Committee

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

Jackson, G.D.

1987-10-01

The Paducah Environmental Advisory Committee was formed as: (1) an outgrowth of other Environmental Advisory Committees already in existence at Oak Ridge and other Martin Marietta Energy Systems plants; (2) a result of public concern following significant nuclear incidents at Bhopal and Chernobyl; (3) a result of the new direction and commitment of the management of the Paducah Gaseous Diffusion Plant following contract acquisition by Martin Marietta Energy Systems; and (4) a means of reducing and/or preventing local and/or public concern regarding the activities of and potential risks created by PGDP. This report discusses the following issues and concerns ofmore » the Committee arrived at through a series of meetings: (1) groundwater monitoring; (2) long-range tails storage; C-404, scrap yrads, and PCB and TCE cleanup; nuclear criticality plan and alarm systems; documentation of historical data regarding hazardous waste burial grounds; dosimeter badges; and asbestos handling and removal.« less

Report on the biological monitoring program at Paducah Gaseous Diffusion Plant December 1990 to November 1992

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

Kszos, L.A.

1994-03-01

On September 23, 1987, the Commonwealth of Kentucky Natural Resources and Environmental Protection Cabinet issued an Agreed Order that required the development of a Biological Monitoring Program (BMP) for the Paducah Gaseous Diffusion Plant (PGDP). Beginning in fall 1991, the Environmental Sciences Division (ESD) at Oak Ridge National Lab (ORNL) added data collection and report preparation to its responsibilities for the PGDP BMP. The BMP has been continued because it has proven to be extremely valuable in identifying those effluents with the potential for adversely affecting instream fauna, assessing the ecological health of receiving streams, guiding plans for remediation, andmore » protecting human health. In September 1992, a renewed permit was issued which requires toxicity monitoring of continuous and intermittent outfalls on a quarterly basis. The BMP for PGDP consists of three major tasks: (1) effluent and ambient toxicity monitoring, (2) bioaccumulation studies, and (3) ecological surveys of stream communities. This report includes ESD/ORNL activities occurring from December 1990 to November 1992.« less

Report on the Biological Monitoring Program at Paducah Gaseous Diffusion Plant December 1992--December 1993

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

Kszos, L.A.; Hinzman, R.L.; Peterson, M.J.

1995-06-01

On September 24, 1987, the Commonwealth of Kentucky Natural Resources and Environmental Protection Cabinet issued an Agreed Order that required the development of a Biological Monitoring Program (BMP) for the Paducah Gaseous Diffusion Plant (PGDP). The goals of BMP are to demonstrate that the effluent limitations established for PGDP protect and maintain the use of Little Bayou and Big Bayou creeks for growth and propagation of fish and other aquatic life, characterize potential health and environmental impacts, document the effects of pollution abatement facilities on stream biota, and recommend any program improvements that would increase effluent treatability. The BMP formore » PGDP consists of three major tasks: effluent and ambient toxicity monitoring, bioaccumulation studies, and ecological surveys of stream communities (i.e., benthic macroinvertebrates and fish). This report includes ESD activities occurring from December 1992 to December 1993, although activities conducted outside this time period are included as appropriate.« less

Modelling bioaccumulation of semi-volatile organic compounds (SOCs) from air in plants based on allometric principles.

PubMed

Steyaert, Nils L L; Hauck, Mara; Van Hulle, Stijn W H; Hendriks, A Jan

2009-10-01

A model was developed for gaseous plant-air exchange of semi-volatile organic compounds. Based on previous soil-plant modelling, uptake and elimination kinetics were scaled as a function of plant mass and octanol-air partition ratios. Exchange of chemicals was assumed to be limited by resistances encountered during diffusion through a laminar boundary layer of air and permeation through the cuticle of the leaf. The uptake rate constant increased and the elimination rate constant decreased with the octanol-air partition ratio both apparently levelling off at high values. Differences in kinetics between species could be explained by their masses. Validation on independent data showed that bio-concentration factors of PCBs, chlorobenzenes and other chemicals were predicted well by the model. For pesticides, polycyclic aromatic hydrocarbons and dioxins deviations occurred.

Electrochemical cell apparatus having an exterior fuel mixer nozzle

DOEpatents

Reichner, Philip; Doshi, Vinod B.

1992-01-01

An electrochemical apparatus (10) is made having a generator section (22) containing electrochemical cells (16), a fresh gaseous feed fuel inlet (28), a gaseous feed oxidant inlet (30), and at least one hot gaseous spent fuel recirculation channel (46), where the spent fuel recirculation channel (46), a portion of which is in contact with the outside of a mixer chamber (52), passes from the generator chamber (22) to combine with the fresh feed fuel inlet (28) at the entrance to the mixer chamber, and a mixer nozzle (50) is located at the entrance to the mixer chamber, where the mixer chamber (52) connects with the reforming chamber (54), and where the mixer-diffuser chamber (52) and mixer nozzle (50) are exterior to and spaced apart from the combustion chamber (24), and the generator chamber (22), and the mixer nozzle (50) can operate below 400.degree. C.

Multicomponent Gas Diffusion and an Appropriate Momentum Boundary Condition

NASA Technical Reports Server (NTRS)

Noever, David A.

1994-01-01

Multicomponent gas diffusion is reviewed with particular emphasis on gas flows near solid boundaries-the so-called Kramers-Kistemaker effect. The aim is to derive an appropriate momentum boundary condition which governs many gaseous species diffusing together. The many species' generalization of the traditional single gas condition, either as slip or stick (no-slip), is not obvious, particularly for technologically important cases of lower gas pressures and very dissimilar molecular weight gases. No convincing theoretical case exists for why two gases should interact with solid boundaries equally but in opposite flow directions, such that the total gas flow exactly vanishes. ln this way, the multicomponent no-slip boundary requires careful treatment The approaches discussed here generally adopt a microscopic model for gas-solid contact. The method has the advantage that the mathematics remain tractable and hence experimentally testable. Two new proposals are put forward, the first building in some molecular collision physics, the second drawing on a detailed view of surface diffusion which does not unphysically extrapolate bulk gas properties to govern the adsorbed molecules. The outcome is a better accounting of previously anomalous experiments. Models predict novel slip conditions appearing even for the case of equal molecular weight components. These approaches become particularly significant in view of a conceptual contradiction found to arise in previous derivations of the appropriate boundary conditions. The analogous case of three gases, one of which is uniformly distributed and hence non-diffusing, presents a further refinement which gives unexpected flow reversals near solid boundaries. This case is investigated alone and for aggregating gas species near their condensation point. In addition to predicting new physics, this investigation carries practical implications for controlling vapor diffusion in the growth of crystals used in medical diagnosis (e.g. mercuric iodide) and semiconductors.

Turbulent diffusion of chemically reacting flows: Theory and numerical simulations

NASA Astrophysics Data System (ADS)

Elperin, T.; Kleeorin, N.; Liberman, M.; Lipatnikov, A. N.; Rogachevskii, I.; Yu, R.

2017-11-01

The theory of turbulent diffusion of chemically reacting gaseous admixtures developed previously [T. Elperin et al., Phys. Rev. E 90, 053001 (2014), 10.1103/PhysRevE.90.053001] is generalized for large yet finite Reynolds numbers and the dependence of turbulent diffusion coefficient on two parameters, the Reynolds number and Damköhler number (which characterizes a ratio of turbulent and reaction time scales), is obtained. Three-dimensional direct numerical simulations (DNSs) of a finite-thickness reaction wave for the first-order chemical reactions propagating in forced, homogeneous, isotropic, and incompressible turbulence are performed to validate the theoretically predicted effect of chemical reactions on turbulent diffusion. It is shown that the obtained DNS results are in good agreement with the developed theory.

New method and installation for rapid determination of radon diffusion coefficient in various materials.

PubMed

Tsapalov, Andrey; Gulabyants, Loren; Livshits, Mihail; Kovler, Konstantin

2014-04-01

The mathematical apparatus and the experimental installation for the rapid determination of radon diffusion coefficient in various materials are developed. The single test lasts not longer than 18 h and allows testing numerous materials, such as gaseous and liquid media, as well as soil, concrete and radon-proof membranes, in which diffusion coefficient of radon may vary in an extremely wide range, from 1·10(-12) to 5·10(-5) m(2)/s. The uncertainty of radon diffusion coefficient estimation depends on the permeability of the sample and varies from about 5% (for the most permeable materials) to 40% (for less permeable materials, such as radon-proof membranes). Copyright © 2014. Published by Elsevier Ltd.

Turbulent diffusion of chemically reacting flows: Theory and numerical simulations.

PubMed

Elperin, T; Kleeorin, N; Liberman, M; Lipatnikov, A N; Rogachevskii, I; Yu, R

2017-11-01

The theory of turbulent diffusion of chemically reacting gaseous admixtures developed previously [T. Elperin et al., Phys. Rev. E 90, 053001 (2014)PLEEE81539-375510.1103/PhysRevE.90.053001] is generalized for large yet finite Reynolds numbers and the dependence of turbulent diffusion coefficient on two parameters, the Reynolds number and Damköhler number (which characterizes a ratio of turbulent and reaction time scales), is obtained. Three-dimensional direct numerical simulations (DNSs) of a finite-thickness reaction wave for the first-order chemical reactions propagating in forced, homogeneous, isotropic, and incompressible turbulence are performed to validate the theoretically predicted effect of chemical reactions on turbulent diffusion. It is shown that the obtained DNS results are in good agreement with the developed theory.

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

Arias-Zugasti, Manuel; High Temperature Chemical Reaction Engineering Laboratory and Yale Center for Combustion Studies, Department of Chemical Engineering, Yale University, New Haven, CT 06520-8286; Rosner, Daniel E.

Since, according to ideal gas kinetic theory, Ludwig-Soret species transport (temperature-gradient-driven mass transport) must be simultaneously included along with nonunity Lewis numbers [D.E. Rosner, R.S. Israel, B. La Mantia, Combust. Flame 123 (2000) 547-560], we formally consider here the influence of both effects on laminar, counterflow gaseous diffusion flames in the thin flame limit. Our deliberately idealized theoretical analysis includes cases of steady/unsteady, strained/unstrained flames and formally permits the prediction of trends for the combustion of either light or heavy fuel vapors in O{sub 2}-containing streams. Our results suggest that, in cases of low- or high-molecular-weight gaseous fuels, Ludwig-Soret transportmore » can itself introduce significant shifts in flame position and flame temperature, compared to results of the same mathematical model neglecting Soret fuel-vapor transport but including only nonunity fuel Lewis numbers. These systematic shifts (which in specific cases may have to be supplemented by additional corrections due to variable thermophysical properties) are expected to have important consequences for NO{sub x} production and/or infrared radiation emission. (author)« less

Gas transport in unsaturated porous media: the adequacy of Fick's law

USGS Publications Warehouse

Thorstenson, D.C.; Pollock, D.W.

1989-01-01

The increasing use of natural unsaturated zones as repositories for landfills and disposal sites for hazardous wastes (chemical and radioactive) requires a greater understanding of transport processes in the unsaturated zone. For volatile constituents an important potential transport mechanism is gaseous diffusion. Diffusion, however, cannot be treated as an independent isolated transport mechanism. A complete understanding of multicomponent gas transport in porous media (unsaturated zones) requires a knowledge of Knudsen transport, the molecular and nonequimolar components of diffusive flux, and viscous (pressure driven) flux. This review presents a brief discussion of the underlying principles and interrelationships among each of the above flux mechanisms. -from Authors

10 CFR Appendix A to Part 725 - Categories of Restricted Data Available

Code of Federal Regulations, 2011 CFR

2011-01-01

... centrifuge or gaseous diffusion processes. b. Design, construction, and operation of any plant, facility or..., design, criticality studies and operation of reactors, reactor systems and reactor components. d... aqueous lithium hydroxide solution in packed columns. Not included is information regarding plant design...

10 CFR Appendix A to Part 725 - Categories of Restricted Data Available

Code of Federal Regulations, 2012 CFR

2012-01-01

... centrifuge or gaseous diffusion processes. b. Design, construction, and operation of any plant, facility or..., design, criticality studies and operation of reactors, reactor systems and reactor components. d... aqueous lithium hydroxide solution in packed columns. Not included is information regarding plant design...

10 CFR Appendix A to Part 725 - Categories of Restricted Data Available

Code of Federal Regulations, 2010 CFR

2010-01-01

... centrifuge or gaseous diffusion processes. b. Design, construction, and operation of any plant, facility or..., design, criticality studies and operation of reactors, reactor systems and reactor components. d... aqueous lithium hydroxide solution in packed columns. Not included is information regarding plant design...

10 CFR Appendix A to Part 725 - Categories of Restricted Data Available

Code of Federal Regulations, 2014 CFR

2014-01-01

... centrifuge or gaseous diffusion processes. b. Design, construction, and operation of any plant, facility or..., design, criticality studies and operation of reactors, reactor systems and reactor components. d... aqueous lithium hydroxide solution in packed columns. Not included is information regarding plant design...

10 CFR 76.123 - Tests.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Tests. 76.123 Section 76.123 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.123 Tests. The Corporation shall perform, or permit the Commission to perform, any tests the Commission deems appropriate or...

10 CFR 76.123 - Tests.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Tests. 76.123 Section 76.123 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.123 Tests. The Corporation shall perform, or permit the Commission to perform, any tests the Commission deems appropriate or...

10 CFR 76.123 - Tests.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Tests. 76.123 Section 76.123 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.123 Tests. The Corporation shall perform, or permit the Commission to perform, any tests the Commission deems appropriate or...

10 CFR 76.123 - Tests.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Tests. 76.123 Section 76.123 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.123 Tests. The Corporation shall perform, or permit the Commission to perform, any tests the Commission deems appropriate or...

10 CFR 76.123 - Tests.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Tests. 76.123 Section 76.123 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Reports and Inspections § 76.123 Tests. The Corporation shall perform, or permit the Commission to perform, any tests the Commission deems appropriate or...

10 CFR 76.9 - Completeness and accuracy of information.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Completeness and accuracy of information. 76.9 Section 76.9 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General... Office within 2 working days of identifying the information. This requirement is not applicable to...

10 CFR 76.9 - Completeness and accuracy of information.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Completeness and accuracy of information. 76.9 Section 76.9 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General... Office within 2 working days of identifying the information. This requirement is not applicable to...

10 CFR 76.9 - Completeness and accuracy of information.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Completeness and accuracy of information. 76.9 Section 76.9 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General... Office within 2 working days of identifying the information. This requirement is not applicable to...

10 CFR 76.35 - Contents of application.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Contents of application. 76.35 Section 76.35 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.35...) The activities and locations involving special nuclear material and the general plan for carrying out...

10 CFR 76.9 - Completeness and accuracy of information.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Completeness and accuracy of information. 76.9 Section 76.9 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General... Office within 2 working days of identifying the information. This requirement is not applicable to...

10 CFR 76.36 - Renewals.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Renewals. 76.36 Section 76.36 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.36 Renewals. (a) The Corporation shall file periodic applications for renewal, as required by § 76.31. (b) Information contained in...

10 CFR 76.81 - Authorized use of radioactive material.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Authorized use of radioactive material. 76.81 Section 76.81 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.81 Authorized use of radioactive material. Unless otherwise authorized by law, the Corporation...

10 CFR 76.55 - Timely renewal.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Timely renewal. 76.55 Section 76.55 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.55 Timely renewal. In any case in which the Corporation has timely filed a sufficient application for a certificate...

10 CFR 76.53 - Consultation with Environmental Protection Agency.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Consultation with Environmental Protection Agency. 76.53 Section 76.53 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.53 Consultation with Environmental Protection Agency. In reviewing an application for a...

10 CFR 76.83 - Transfer of radioactive material.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Transfer of radioactive material. 76.83 Section 76.83 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.83 Transfer of radioactive material. (a) The Corporation may not transfer radioactive material except as...

10 CFR 76.55 - Timely renewal.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Timely renewal. 76.55 Section 76.55 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.55 Timely renewal. In any case in which the Corporation has timely filed a sufficient application for a certificate...

10 CFR 76.36 - Renewals.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Renewals. 76.36 Section 76.36 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.36 Renewals. (a) The Corporation shall file periodic applications for renewal, as required by § 76.31. (b) Information contained in...

10 CFR 76.81 - Authorized use of radioactive material.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Authorized use of radioactive material. 76.81 Section 76.81 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.81 Authorized use of radioactive material. Unless otherwise authorized by law, the Corporation...

10 CFR 76.83 - Transfer of radioactive material.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Transfer of radioactive material. 76.83 Section 76.83 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.83 Transfer of radioactive material. (a) The Corporation may not transfer radioactive material except as...

10 CFR 76.36 - Renewals.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Renewals. 76.36 Section 76.36 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.36 Renewals. (a) The Corporation shall file periodic applications for renewal, as required by § 76.31. (b) Information contained in...

10 CFR 76.65 - Inalienability of certificates.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Inalienability of certificates. 76.65 Section 76.65 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.65 Inalienability of certificates. The certificate granted under the regulations in this part may not be transferred...

10 CFR 76.70 - Post issuance.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Post issuance. 76.70 Section 76.70 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.70 Post issuance. (a) Amendment of certificate terms and conditions. The terms and conditions of a certificate of...

10 CFR 76.91 - Emergency planning.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Emergency planning. 76.91 Section 76.91 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.91 Emergency planning. The Corporation shall establish, maintain, and be prepared to follow a written emergency plan. The...

10 CFR 76.91 - Emergency planning.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Emergency planning. 76.91 Section 76.91 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.91 Emergency planning. The Corporation shall establish, maintain, and be prepared to follow a written emergency plan. The...

10 CFR 76.91 - Emergency planning.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Emergency planning. 76.91 Section 76.91 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.91 Emergency planning. The Corporation shall establish, maintain, and be prepared to follow a written emergency plan. The...

10 CFR 76.81 - Authorized use of radioactive material.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Authorized use of radioactive material. 76.81 Section 76.81 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.81 Authorized use of radioactive material. Unless otherwise authorized by law, the Corporation...

10 CFR 76.33 - Application procedures.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Application procedures. 76.33 Section 76.33 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.33 Application procedures. (a) Filing requirements. (1) An application for a certificate of compliance must be tendered by...

10 CFR 76.53 - Consultation with Environmental Protection Agency.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Consultation with Environmental Protection Agency. 76.53 Section 76.53 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.53 Consultation with Environmental Protection Agency. In reviewing an application for a...

10 CFR 76.33 - Application procedures.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Application procedures. 76.33 Section 76.33 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.33 Application procedures. (a) Filing requirements. (1) An application for a certificate of compliance must be tendered by...

10 CFR 76.65 - Inalienability of certificates.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Inalienability of certificates. 76.65 Section 76.65 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.65 Inalienability of certificates. The certificate granted under the regulations in this part may not be transferred...

10 CFR 76.45 - Application for amendment of certificate.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Application for amendment of certificate. 76.45 Section 76.45 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.45 Application for amendment of certificate. (a) Contents of an amendment application. In...

10 CFR 76.85 - Assessment of accidents.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Assessment of accidents. 76.85 Section 76.85 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.85 Assessment of accidents. The Corporation shall perform an analysis of potential accidents and consequences to...

10 CFR 76.45 - Application for amendment of certificate.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Application for amendment of certificate. 76.45 Section 76.45 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.45 Application for amendment of certificate. (a) Contents of an amendment application. In...

10 CFR 76.81 - Authorized use of radioactive material.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Authorized use of radioactive material. 76.81 Section 76.81 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.81 Authorized use of radioactive material. Unless otherwise authorized by law, the Corporation...

10 CFR 76.8 - Information collection requirements: OMB approval not required.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Information collection requirements: OMB approval not required. 76.8 Section 76.8 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.8 Information collection requirements: OMB approval not required...

10 CFR 76.53 - Consultation with Environmental Protection Agency.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Consultation with Environmental Protection Agency. 76.53 Section 76.53 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.53 Consultation with Environmental Protection Agency. In reviewing an application for a...

10 CFR 76.83 - Transfer of radioactive material.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Transfer of radioactive material. 76.83 Section 76.83 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.83 Transfer of radioactive material. (a) The Corporation may not transfer radioactive material except as...

10 CFR 76.83 - Transfer of radioactive material.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Transfer of radioactive material. 76.83 Section 76.83 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.83 Transfer of radioactive material. (a) The Corporation may not transfer radioactive material except as...

10 CFR 76.55 - Timely renewal.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Timely renewal. 76.55 Section 76.55 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.55 Timely renewal. In any case in which the Corporation has timely filed a sufficient application for a certificate...

10 CFR 76.8 - Information collection requirements: OMB approval not required.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Information collection requirements: OMB approval not required. 76.8 Section 76.8 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.8 Information collection requirements: OMB approval not required...

10 CFR 76.8 - Information collection requirements: OMB approval not required.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Information collection requirements: OMB approval not required. 76.8 Section 76.8 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.8 Information collection requirements: OMB approval not required...

10 CFR 76.53 - Consultation with Environmental Protection Agency.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Consultation with Environmental Protection Agency. 76.53 Section 76.53 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.53 Consultation with Environmental Protection Agency. In reviewing an application for a...

10 CFR 76.70 - Post issuance.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Post issuance. 76.70 Section 76.70 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.70 Post issuance. (a) Amendment of certificate terms and conditions. The terms and conditions of a certificate of...

10 CFR 76.33 - Application procedures.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Application procedures. 76.33 Section 76.33 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.33 Application procedures. (a) Filing requirements. (1) An application for a certificate of compliance must be tendered by...

10 CFR 76.65 - Inalienability of certificates.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Inalienability of certificates. 76.65 Section 76.65 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.65 Inalienability of certificates. The certificate granted under the regulations in this part may not be transferred...

10 CFR 76.55 - Timely renewal.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Timely renewal. 76.55 Section 76.55 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.55 Timely renewal. In any case in which the Corporation has timely filed a sufficient application for a certificate...

10 CFR 76.45 - Application for amendment of certificate.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Application for amendment of certificate. 76.45 Section 76.45 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.45 Application for amendment of certificate. (a) Contents of an amendment application. In...

10 CFR 76.33 - Application procedures.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Application procedures. 76.33 Section 76.33 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.33 Application procedures. (a) Filing requirements. (1) An application for a certificate of compliance must be tendered by...

10 CFR 76.83 - Transfer of radioactive material.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Transfer of radioactive material. 76.83 Section 76.83 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.83 Transfer of radioactive material. (a) The Corporation may not transfer radioactive material except as...

10 CFR 76.53 - Consultation with Environmental Protection Agency.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Consultation with Environmental Protection Agency. 76.53 Section 76.53 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.53 Consultation with Environmental Protection Agency. In reviewing an application for a...

10 CFR 76.85 - Assessment of accidents.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Assessment of accidents. 76.85 Section 76.85 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.85 Assessment of accidents. The Corporation shall perform an analysis of potential accidents and consequences to...

10 CFR 76.45 - Application for amendment of certificate.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Application for amendment of certificate. 76.45 Section 76.45 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.45 Application for amendment of certificate. (a) Contents of an amendment application. In...

10 CFR 76.85 - Assessment of accidents.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Assessment of accidents. 76.85 Section 76.85 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.85 Assessment of accidents. The Corporation shall perform an analysis of potential accidents and consequences to...

10 CFR 76.33 - Application procedures.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Application procedures. 76.33 Section 76.33 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.33 Application procedures. (a) Filing requirements. (1) An application for a certificate of compliance must be tendered by...

10 CFR 76.36 - Renewals.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Renewals. 76.36 Section 76.36 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.36 Renewals. (a) The Corporation shall file periodic applications for renewal, as required by § 76.31. (b) Information contained in...

10 CFR 76.85 - Assessment of accidents.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Assessment of accidents. 76.85 Section 76.85 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.85 Assessment of accidents. The Corporation shall perform an analysis of potential accidents and consequences to...

10 CFR 76.8 - Information collection requirements: OMB approval not required.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Information collection requirements: OMB approval not required. 76.8 Section 76.8 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.8 Information collection requirements: OMB approval not required...

10 CFR 76.70 - Post issuance.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Post issuance. 76.70 Section 76.70 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.70 Post issuance. (a) Amendment of certificate terms and conditions. The terms and conditions of a certificate of...

10 CFR 76.36 - Renewals.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Renewals. 76.36 Section 76.36 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.36 Renewals. (a) The Corporation shall file periodic applications for renewal, as required by § 76.31. (b) Information contained in...

10 CFR 76.65 - Inalienability of certificates.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Inalienability of certificates. 76.65 Section 76.65 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.65 Inalienability of certificates. The certificate granted under the regulations in this part may not be transferred...

10 CFR 76.85 - Assessment of accidents.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Assessment of accidents. 76.85 Section 76.85 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.85 Assessment of accidents. The Corporation shall perform an analysis of potential accidents and consequences to...

10 CFR 76.70 - Post issuance.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Post issuance. 76.70 Section 76.70 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.70 Post issuance. (a) Amendment of certificate terms and conditions. The terms and conditions of a certificate of...

10 CFR 76.45 - Application for amendment of certificate.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Application for amendment of certificate. 76.45 Section 76.45 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.45 Application for amendment of certificate. (a) Contents of an amendment application. In...

10 CFR 76.81 - Authorized use of radioactive material.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Authorized use of radioactive material. 76.81 Section 76.81 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safety § 76.81 Authorized use of radioactive material. Unless otherwise authorized by law, the Corporation...

10 CFR 76.65 - Inalienability of certificates.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Inalienability of certificates. 76.65 Section 76.65 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.65 Inalienability of certificates. The certificate granted under the regulations in this part may not be transferred...

10 CFR 76.55 - Timely renewal.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Timely renewal. 76.55 Section 76.55 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.55 Timely renewal. In any case in which the Corporation has timely filed a sufficient application for a certificate...

10 CFR 76.8 - Information collection requirements: OMB approval not required.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Information collection requirements: OMB approval not required. 76.8 Section 76.8 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.8 Information collection requirements: OMB approval not required...

10 CFR 76.35 - Contents of application.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Contents of application. 76.35 Section 76.35 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.35...) The activities and locations involving special nuclear material and the general plan for carrying out...

10 CFR 76.9 - Completeness and accuracy of information.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Completeness and accuracy of information. 76.9 Section 76.9 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General... Office within 2 working days of identifying the information. This requirement is not applicable to...

10 CFR 76.35 - Contents of application.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Contents of application. 76.35 Section 76.35 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.35...) The activities and locations involving special nuclear material and the general plan for carrying out...

10 CFR 76.35 - Contents of application.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Contents of application. 76.35 Section 76.35 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.35...) The activities and locations involving special nuclear material and the general plan for carrying out...

10 CFR 76.35 - Contents of application.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Contents of application. 76.35 Section 76.35 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.35...) The activities and locations involving special nuclear material and the general plan for carrying out...

Numerical simulations of detonation propagation in gaseous fuel-air mixtures

NASA Astrophysics Data System (ADS)

Honhar, Praveen; Kaplan, Carolyn; Houim, Ryan; Oran, Elaine

2017-11-01

Unsteady multidimensional numerical simulations of detonation propagation and survival in mixtures of fuel (hydrogen or methane) diluted with air were carried out with a fully compressible Navier-Stokes solver using a simplified chemical-diffusive model (CDM). The CDM was derived using a genetic algorithm combined with the Nelder-Mead optimization algorithm and reproduces physically correct laminar flame and detonation properties. Cases studied are overdriven detonations propagating through confined mediums, with or without gradients in composition. Results from simulations confirm that the survival of the detonation depends on the channel heights. In addition, the simulations show that the propagation of the detonation waves depends on the steepness in composition gradients.

Planar Strain-Rate-Free Diffusion Flames: Initiation, Properties, and Extinction

NASA Technical Reports Server (NTRS)

Fendell, Francis; Gokoglu, Suleyman; Rungaldier, Harald; Schultz, Donald

1999-01-01

An effectively strain-rate-free diffusion flame constitutes the most vigorous laminar combustion of initially unmixed reactive gases. Such a diffusion flame is characterized by a relatively long residence time and by a relatively large characteristic length scale. If such a flame were also planar, providing high symmetry, it would be particularly suitable for experimental and theoretical investigations of key combustion phenomena, such as multicomponent diffusion, chemical kinetics, and soot inception, growth, and oxidation. Unfortunately, a planar strain-rate-free diffusion flame is highly disrupted in earth-gravity (e.g., in a counterflow-diffusion-flame apparatus) because of the very rapid onset (approx. 100 ms) of gravity-induced instability. Accordingly, a specially dedicated apparatus was designed, fabricated, and initially checked out for the examination of a planar strain-rate-free diffusion flame in microgravity. Such a diffusion flame may be formed within a hollowed-out squat container (initially configured as 25 cm x 25 cm x 9 cm), with isothermal, noncatalytic, impervious walls. At test initiation, a thin metallic sheet (approx. 1 mm in thickness) that separates the internal volume into two equal portions, each of dimensions 25 cm x 25 cm x 4.5 cm, is withdrawn, by uniform translation (approx. 50 cm/s) in its own plane, through a tightly fitting slit in one side wall. Thereupon, diluted fuel vapor (initially confined to one half-volume of the container) gains access to diluted oxygen (initially with the same pressure, density, and temperature as the fuel, but initially confined to the other half-volume). After a brief delay (approx. 10 ms), to permit limited but sufficient-for-flammability diffusional interpenetration of fuel vapor and oxidizer, burning is initiated by discharge of a line igniter, located along that side wall from which the trailing edge of the separator withdraws. The ignition spawns a triple-flame propagation across the 25 cm x 25 cm centerplane. When a diffusion flame is emplaced in the centerplane, any subsequent travel, and change in temperature, of that planar diffusion flame may be tracked, along with the effectively spatially uniform but temporally evolving pressure within the container. Eventually, nearly complete depletion of the stoichiometrically deficient reactant, along with heat loss to the container surfaces, effects extinction. These data afford an opportunity to check theoretical models of diffusion and chemical kinetics under conditions ranging from intense burning to flame out, or, alternatively, to evolve simple empirical representations of these phenomena. Thus, the project sought to utilize microgravity testing to elucidate commonly encountered phenomenology, arising in the commonly-encountered mode of combustion (whether related to heating, manufacturing, boiling, and propulsion, or to uncontrolled, free-burning fire in structures and wildland vegetation), of those commonly utilized fuels usually categorized as gaseous fuels (such as hydrogen, natural gas, and propane, which are gaseous under atmospheric conditions).

The Mass and Absorption Columns of Galactic Gaseous Halos

NASA Astrophysics Data System (ADS)

Qu, Zhijie; Bregman, Joel N.

2018-03-01

The galactic gaseous halo is a gas reservoir for the interstellar medium in the galaxy disk, supplying materials for star formation. We developed a gaseous halo model connecting the galaxy disk and the gaseous halo by assuming that the star formation rate on the disk is balanced by the radiative cooling rate of the gaseous halo, including stellar feedback. In addition to a single-temperature gaseous halo in collisional ionization equilibrium, we also consider the photoionization effect and a steady-state cooling model. Photoionization is important for modifying the ion distribution in low-mass galaxies and in the outskirts of massive galaxies due to the low densities. The multiphase cooling model dominates the region within the cooling radius, where t cooling = t Hubble. Our model reproduces most of the observed high ionization state ions for a wide range of galaxy masses (i.e., O VI, O VII, Ne VIII, Mg X, and O VIII). We find that the O VI column density has a narrow range around ≈1014 cm‑2 for halo masses from M ⋆ ≈ 3 × 1010 M ⊙ to 6 × 1012 M ⊙, which is consistent with some but not all observational studies. For galaxies with halo masses ≲3 × 1011 M ⊙, photoionization produces most of the O VI, while for more massive galaxies, the O VI is from the medium that is cooling from higher temperatures. Fitting the Galactic (Milky-Way) O VII and O VIII suggests a gaseous halo model where the metallicity is ≈0.55 Z ⊙ and the gaseous halo has a maximum temperature of ≈1.9 × 106 K. This gaseous halo model does not close the census of baryonic material within R 200.

78 FR 66779 - United States Enrichment Corporation, Paducah Gaseous Diffusion Plant, Including On-Site Leased...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-06

..., KB Consultants, Henry, Meisenheimer, & Grende, SR Martin Group And CDI Corporation, Paducah, Kentucky.... Petter Supply, KB Consultants, Henry, Meisenheimer & Grende, SR Martin Group and CDI Corporation were... Services, Henry A. Petter Supply, KB Consultants, Henry, Meisenheimer & Grende, SR Martin Group and CDI...

Effect of chlorine dioxide gas on physical, thermal, mechanical, and barrier properties of p[olymeric packaging materials

USDA-ARS?s Scientific Manuscript database

In the first part of our study we determined permeability, diffusion, and solubility coefficients of gaseous chlorine dioxide (ClO2) through the following packaging material: biaxial-oriented polypropylene (BOPP); polyethylene terephthalate (PET); poly lactic acid (PLA); multilayer structure of ethy...

10 CFR 76.37 - Federal Register notice.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Federal Register notice. 76.37 Section 76.37 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.37 Federal Register notice. The Director may, at his or her discretion, publish in the Federal Register: (a...

10 CFR 76.41 - Record underlying decisions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Record underlying decisions. 76.41 Section 76.41 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.41 Record underlying decisions. (a) Any decision of the Commission or its designee under this part in any...

10 CFR 76.22 - Ineligibility of certain applicants.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Ineligibility of certain applicants. 76.22 Section 76.22 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.22 Ineligibility of certain applicants. A certificate of compliance may not be issued to the...

10 CFR 76.41 - Record underlying decisions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Record underlying decisions. 76.41 Section 76.41 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.41 Record underlying decisions. (a) Any decision of the Commission or its designee under this part in any...

10 CFR 76.133 - Criminal penalties.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Criminal penalties. 76.133 Section 76.133 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Enforcement § 76.133 Criminal penalties. (a) Section 223 of the Atomic Energy Act of 1954, as amended, provides for criminal sanctions for...

10 CFR 76.37 - Federal Register notice.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Federal Register notice. 76.37 Section 76.37 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.37 Federal Register notice. The Director may, at his or her discretion, publish in the Federal Register: (a...

10 CFR 76.133 - Criminal penalties.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Criminal penalties. 76.133 Section 76.133 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Enforcement § 76.133 Criminal penalties. (a) Section 223 of the Atomic Energy Act of 1954, as amended, provides for criminal sanctions for...

10 CFR 76.43 - Date for decision.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Date for decision. 76.43 Section 76.43 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.43 Date for decision. The Director will render a decision on an application within 6 months of the receipt of the...

10 CFR 76.43 - Date for decision.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Date for decision. 76.43 Section 76.43 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.43 Date for decision. The Director will render a decision on an application within 6 months of the receipt of the...

10 CFR 76.37 - Federal Register notice.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Federal Register notice. 76.37 Section 76.37 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.37 Federal Register notice. The Director may, at his or her discretion, publish in the Federal Register: (a...

10 CFR 76.133 - Criminal penalties.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Criminal penalties. 76.133 Section 76.133 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Enforcement § 76.133 Criminal penalties. (a) Section 223 of the Atomic Energy Act of 1954, as amended, provides for criminal sanctions for...

10 CFR 76.39 - Public meeting.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Public meeting. 76.39 Section 76.39 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.39 Public meeting. (a) A public meeting will be held on an application for renewal if the Director, in his or her...

10 CFR 76.37 - Federal Register notice.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Federal Register notice. 76.37 Section 76.37 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.37 Federal Register notice. The Director may, at his or her discretion, publish in the Federal Register: (a...

10 CFR 76.39 - Public meeting.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Public meeting. 76.39 Section 76.39 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.39 Public meeting. (a) A public meeting will be held on an application for renewal if the Director, in his or her...

10 CFR 76.22 - Ineligibility of certain applicants.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Ineligibility of certain applicants. 76.22 Section 76.22 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.22 Ineligibility of certain applicants. A certificate of compliance may not be issued to the...

10 CFR 76.133 - Criminal penalties.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Criminal penalties. 76.133 Section 76.133 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Enforcement § 76.133 Criminal penalties. (a) Section 223 of the Atomic Energy Act of 1954, as amended, provides for criminal sanctions for...

10 CFR 76.22 - Ineligibility of certain applicants.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Ineligibility of certain applicants. 76.22 Section 76.22 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.22 Ineligibility of certain applicants. A certificate of compliance may not be issued to the...

10 CFR 76.41 - Record underlying decisions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Record underlying decisions. 76.41 Section 76.41 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.41 Record underlying decisions. (a) Any decision of the Commission or its designee under this part in any...

10 CFR 76.39 - Public meeting.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Public meeting. 76.39 Section 76.39 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.39 Public meeting. (a) A public meeting will be held on an application for renewal if the Director, in his or her...

10 CFR 76.43 - Date for decision.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Date for decision. 76.43 Section 76.43 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.43 Date for decision. The Director will render a decision on an application within 6 months of the receipt of the...

10 CFR 76.37 - Federal Register notice.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Federal Register notice. 76.37 Section 76.37 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.37 Federal Register notice. The Director may, at his or her discretion, publish in the Federal Register: (a...

10 CFR 76.43 - Date for decision.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Date for decision. 76.43 Section 76.43 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.43 Date for decision. The Director will render a decision on an application within 6 months of the receipt of the...

10 CFR 76.22 - Ineligibility of certain applicants.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Ineligibility of certain applicants. 76.22 Section 76.22 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.22 Ineligibility of certain applicants. A certificate of compliance may not be issued to the...

10 CFR 76.41 - Record underlying decisions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Record underlying decisions. 76.41 Section 76.41 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.41 Record underlying decisions. (a) Any decision of the Commission or its designee under this part in any...

10 CFR 76.133 - Criminal penalties.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Criminal penalties. 76.133 Section 76.133 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Enforcement § 76.133 Criminal penalties. (a) Section 223 of the Atomic Energy Act of 1954, as amended, provides for criminal sanctions for...

10 CFR 76.22 - Ineligibility of certain applicants.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Ineligibility of certain applicants. 76.22 Section 76.22 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS General Provisions § 76.22 Ineligibility of certain applicants. A certificate of compliance may not be issued to the...

10 CFR 76.41 - Record underlying decisions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Record underlying decisions. 76.41 Section 76.41 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Application § 76.41 Record underlying decisions. (a) Any decision of the Commission or its designee under this part in any...

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

BEHAR, Christophe; GUIBERTEAU, Philippe; DUPERRET, Bernard

This paper describes the D&D program that is being implemented at France's High Enrichment Gaseous Diffusion Plant, which was designed to supply France's Military with Highly Enriched Uranium. This plant was definitively shut down in June 1996, following French President Jacques Chirac's decision to end production of Highly Enriched Uranium and dismantle the corresponding facilities.

20 CFR 30.214 - How does a claimant establish that the employee is a member of the Special Exposure Cohort?

Code of Federal Regulations, 2011 CFR

2011-04-01

..., Alaska, and was exposed to ionizing radiation in the performance of duty related to the Long Shot, Milrow... one gaseous diffusion plant. (c) Proof of employment by the DOE or a DOE contractor, or an atomic...

20 CFR 30.214 - How does a claimant establish that the employee is a member of the Special Exposure Cohort?

Code of Federal Regulations, 2010 CFR

2010-04-01

..., Alaska, and was exposed to ionizing radiation in the performance of duty related to the Long Shot, Milrow... one gaseous diffusion plant. (c) Proof of employment by the DOE or a DOE contractor, or an atomic...

20 CFR 30.214 - How does a claimant establish that the employee is a member of the Special Exposure Cohort?

Code of Federal Regulations, 2014 CFR

2014-04-01

..., Alaska, and was exposed to ionizing radiation in the performance of duty related to the Long Shot, Milrow... one gaseous diffusion plant. (c) Proof of employment by the DOE or a DOE contractor, or an atomic...

20 CFR 30.214 - How does a claimant establish that the employee is a member of the Special Exposure Cohort?

Code of Federal Regulations, 2013 CFR

2013-04-01

..., Alaska, and was exposed to ionizing radiation in the performance of duty related to the Long Shot, Milrow... one gaseous diffusion plant. (c) Proof of employment by the DOE or a DOE contractor, or an atomic...

20 CFR 30.214 - How does a claimant establish that the employee is a member of the Special Exposure Cohort?

Code of Federal Regulations, 2012 CFR

2012-04-01

..., Alaska, and was exposed to ionizing radiation in the performance of duty related to the Long Shot, Milrow... one gaseous diffusion plant. (c) Proof of employment by the DOE or a DOE contractor, or an atomic...

Recent Progress in the Remote Detection of Vapours and Gaseous Pollutants.

ERIC Educational Resources Information Center

Moffat, A. J.; And Others

Work has been continuing on the correlation spectrometry techniques described at previous remote sensing symposiums. Advances in the techniques are described which enable accurate quantitative measurements of diffused atmospheric gases to be made using controlled light sources, accurate quantitative measurements of gas clouds relative to…

10 CFR 76.117 - Special nuclear material of low strategic significance-Category III.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Special nuclear material of low strategic significance-Category III. 76.117 Section 76.117 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.117 Special nuclear material of low strategic...

10 CFR 76.115 - Special nuclear material of moderate strategic significance-Category II.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Special nuclear material of moderate strategic significance-Category II. 76.115 Section 76.115 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.115 Special nuclear material of moderate...

10 CFR 76.117 - Special nuclear material of low strategic significance-Category III.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Special nuclear material of low strategic significance-Category III. 76.117 Section 76.117 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.117 Special nuclear material of low strategic...

10 CFR 76.117 - Special nuclear material of low strategic significance-Category III.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Special nuclear material of low strategic significance-Category III. 76.117 Section 76.117 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.117 Special nuclear material of low strategic...

10 CFR 76.115 - Special nuclear material of moderate strategic significance-Category II.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Special nuclear material of moderate strategic significance-Category II. 76.115 Section 76.115 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.115 Special nuclear material of moderate...

10 CFR 76.115 - Special nuclear material of moderate strategic significance-Category II.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Special nuclear material of moderate strategic significance-Category II. 76.115 Section 76.115 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.115 Special nuclear material of moderate...

10 CFR 76.115 - Special nuclear material of moderate strategic significance-Category II.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Special nuclear material of moderate strategic significance-Category II. 76.115 Section 76.115 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.115 Special nuclear material of moderate...

10 CFR 76.117 - Special nuclear material of low strategic significance-Category III.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Special nuclear material of low strategic significance-Category III. 76.117 Section 76.117 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.117 Special nuclear material of low strategic...

10 CFR 76.115 - Special nuclear material of moderate strategic significance-Category II.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Special nuclear material of moderate strategic significance-Category II. 76.115 Section 76.115 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.115 Special nuclear material of moderate...

10 CFR 76.117 - Special nuclear material of low strategic significance-Category III.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Special nuclear material of low strategic significance-Category III. 76.117 Section 76.117 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.117 Special nuclear material of low strategic...

10 CFR 76.68 - Plant changes.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Plant changes. 76.68 Section 76.68 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.68 Plant changes. (a) The Corporation may make changes to the plant or to the plant's operations as described in...

10 CFR 76.68 - Plant changes.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Plant changes. 76.68 Section 76.68 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.68 Plant changes. (a) The Corporation may make changes to the plant or to the plant's operations as described in...

10 CFR 76.68 - Plant changes.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Plant changes. 76.68 Section 76.68 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.68 Plant changes. (a) The Corporation may make changes to the plant or to the plant's operations as described in...

10 CFR 76.68 - Plant changes.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Plant changes. 76.68 Section 76.68 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.68 Plant changes. (a) The Corporation may make changes to the plant or to the plant's operations as described in...

10 CFR 76.68 - Plant changes.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Plant changes. 76.68 Section 76.68 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.68 Plant changes. (a) The Corporation may make changes to the plant or to the plant's operations as described in...

Transient Evolution of a Planar Diffusion Flame Aft of a Translating Flat Plate

NASA Technical Reports Server (NTRS)

Gokoglu, Suleyman A.

2003-01-01

The high degree of spatial symmetry of a planar diffusion flame affords great simplifications for experimental and modeling studies of gaseous fuel combustion. Particularly, in a microgravity environment, where buoyancy effects are negligible, an effectively strain-rate-free, vigorous flame may be obtained. Such a flame can also provide long residence times and large length scales for practical probing of flame structures and soot processes. This 2-D numerical study explores the feasibility of establishing such a planar diffusion flame in an enclosed container utilizing a realistic test protocol for a microgravity experiment. Fuel and oxygen mixtures, initially segregated into two half-volumes of a squat rectangular container by a thin separator, are ignited as soon as a flammable mixture is formed in the wake of the separator withdrawn in the centerplane. A triple-flame ensues that propagates behind the trailing edge of the separator. The results of calculations show that the mechanically- and thermally-induced convection decays in about two seconds. The establishment of a planar diffusion flame after this period seems feasible in the central region of the container with sufficient quantities of reactants left over for subsequent studies. An analysis of the flame initiation and formation process suggests how the feasibility of creating such a flame can be further improved.

A Diffusive Homeostatic Signal Maintains Neural Heterogeneity and Responsiveness in Cortical Networks

PubMed Central

Sweeney, Yann; Hellgren Kotaleski, Jeanette; Hennig, Matthias H.

2015-01-01

Gaseous neurotransmitters such as nitric oxide (NO) provide a unique and often overlooked mechanism for neurons to communicate through diffusion within a network, independent of synaptic connectivity. NO provides homeostatic control of intrinsic excitability. Here we conduct a theoretical investigation of the distinguishing roles of NO-mediated diffusive homeostasis in comparison with canonical non-diffusive homeostasis in cortical networks. We find that both forms of homeostasis provide a robust mechanism for maintaining stable activity following perturbations. However, the resulting networks differ, with diffusive homeostasis maintaining substantial heterogeneity in activity levels of individual neurons, a feature disrupted in networks with non-diffusive homeostasis. This results in networks capable of representing input heterogeneity, and linearly responding over a broader range of inputs than those undergoing non-diffusive homeostasis. We further show that these properties are preserved when homeostatic and Hebbian plasticity are combined. These results suggest a mechanism for dynamically maintaining neural heterogeneity, and expose computational advantages of non-local homeostatic processes. PMID:26158556

Low cost solar array project. Cell and module formation research area. Process research of non-CZ silicon material

NASA Technical Reports Server (NTRS)

1983-01-01

Liquid diffusion masks and liquid dopants to replace the more expensive CVD SiO2 mask and gaseous diffusion processes were investigated. Silicon pellets were prepared in the silicon shot tower; and solar cells were fabricated using web grown where the pellets were used as a replenishment material. Verification runs were made using the boron dopant and liquid diffusion mask materials. The average of cells produced in these runs was 13%. The relationship of sheet resistivity, temperature, gas flows, and gas composition for the diffusion of the P-8 liquid phosphorus solution was investigated. Solar cells processed from web grown from Si shot material were evaluated, and results qualified the use of the material produced in the shot tower for web furnace feed stock.

Focused RBCC Experiments: Two-Rocket Configuration Experiments and Hydrocarbon/Oxygen Rocket Ejector Experiments

NASA Technical Reports Server (NTRS)

Santoro, Robert J.; Pal, Sibtosh

2003-01-01

This addendum report documents the results of two additional efforts for the Rocket Based Combined Cycle (RBCC) rocket-ejector mode research work carried out at the Penn State Propulsion Engineering Research Center in support of NASA s technology development efforts for enabling 3 d generation Reusable Launch Vehicles (RLV). The tasks reported here build on an earlier NASA MSFC funded research program on rocket ejector investigations. The first task investigated the improvements of a gaseous hydrogen/oxygen twin thruster RBCC rocket ejector system over a single rocket system. The second task investigated the performance of a hydrocarbon (liquid JP-7)/gaseous oxygen single thruster rocket-ejector system. To gain a systematic understanding of the rocket-ejector s internal fluid mechanic/combustion phenomena, experiments were conducted with both direct-connect and sea-level static diffusion and afterburning (DAB) configurations for a range of rocket operating conditions. For all experimental conditions, overall system performance was obtained through global measurements of wall static pressure profiles, heat flux profiles and engine thrust. Detailed mixing and combustion information was obtained through Raman spectroscopy measurements of major species (gaseous oxygen, hydrogen, nitrogen and water vapor) for the gaseous hydrogen/oxygen rocket ejector experiments.

General anesthesia with methoxyflurane given intravenously to the dog.

PubMed

Hilwig, R W

1976-03-01

Dogs were anesthetized with liquid methoxyflurane administered intravenously by gaseous diffusion through sealed medical grade silicone rubber tubing placed in the femoral vein. A similar catheter placed in the other femoral vein and connected to a pressure transducer measured the increase in intraluminal pressure due to methoxyflurane diffusion into the 2nd catheter from the bloodstream 20 seconds after the catheter was flushed with room air. These pressures were plotted against venous blood methoxyflurane concentration, as determined by gas chromatography, for increasing lengths of anesthetic-administering catheter exposed to the bloodstream.

Drying in porous media with gravity-stabilized fronts: experimental results.

PubMed

Yiotis, A G; Salin, D; Tajer, E S; Yortsos, Y C

2012-08-01

In a recent paper [Yiotis et al., Phys. Rev. E 85, 046308 (2012)] we developed a model for the drying of porous media in the presence of gravity. It incorporated effects of corner film flow, internal and external mass transfer, and the effect of gravity. Analytical results were derived when gravity opposes drying and hence leads to a stable percolation drying front. In this paper, we test the theory using laboratory experiments. A series of isothermal drying experiments in glass bead packings saturated with volatile hydrocarbons is conducted. The transparent glass cells containing the packing allow for the visual monitoring of the phase distribution patterns below the surface, including the formation of liquid films, as the gaseous phase invades the pore space, and for the control of the thickness of the diffusive mass boundary layer over the packing. The experimental results agree very well with theory, provided that the latter is generalized to account for the effects of corner roundness in the film region (which was neglected in the theoretical part). We demonstrate the existence of an early constant rate period (CRP), which lasts as long as the films saturate the surface of the packing, and of a subsequent falling rate period (FRP), which begins practically after the detachment of the film tips from the external surface. During the CRP, the process is controlled by diffusion within the stagnant gaseous phase in the upper part of the cells, yielding a Stefan tube problem solution. During the FRP, the process is controlled by diffusion within the packing, with a drying rate inversely proportional to the observed position of the film tips in the cell. Theoretical and experimental results compare favorably for a specific value of the roundness of the films, which is found to be constant and equal to 0.2 for various conditions, and verify the theoretical dependence on the capillary Ca(f), Bond Bo, and Sherwood Sh numbers.

The Light Side of Dark Matter

NASA Astrophysics Data System (ADS)

Cisneros, Sophia

2013-04-01

We present a new, heuristic, two-parameter model for predicting the rotation curves of disc galaxies. The model is tested on (22) randomly chosen galaxies, represented in 35 data sets. This Lorentz Convolution [LC] model is derived from a non-linear, relativistic solution of a Kerr-type wave equation, where small changes in the photon's frequencies, resulting from the curved space time, are convolved into a sequence of Lorentz transformations. The LC model is parametrized with only the diffuse, luminous stellar and gaseous masses reported with each data set of observations used. The LC model predicts observed rotation curves across a wide range of disk galaxies. The LC model was constructed to occupy the same place in the explanation of rotation curves that Dark Matter does, so that a simple investigation of the relation between luminous and dark matter might be made, via by a parameter (a). We find the parameter (a) to demonstrate interesting structure. We compare the new model prediction to both the NFW model and MOND fits when available.

Semi-annual report on strategic special nuclear material inventory differences

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

Not Available

1978-01-01

This periodic report of Inventory Differences covers the period October 1, 1976, through March 31, 1977 for Department of Energy (DOE) and DOE contractor facilities possessing significant quantities of Strategic Special Nuclear Material (SSNM). Included in this report are the low enriched uranium inventory differences for DOE's gaseous diffusion plant cascades. (LK)

10 CFR 76.64 - Denial of certificate or compliance plan.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Denial of certificate or compliance plan. 76.64 Section 76.64 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.64 Denial of certificate or compliance plan. (a) The Director may deny an application for a...

10 CFR 76.62 - Issuance of certificate and/or approval of compliance plan.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Issuance of certificate and/or approval of compliance plan. 76.62 Section 76.62 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.62 Issuance of certificate and/or approval of compliance plan. (a) Upon...

10 CFR 76.119 - Security facility approval and safeguarding of National Security Information and Restricted Data.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Security facility approval and safeguarding of National Security Information and Restricted Data. 76.119 Section 76.119 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.119 Security facility...

10 CFR 76.64 - Denial of certificate or compliance plan.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Denial of certificate or compliance plan. 76.64 Section 76.64 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.64 Denial of certificate or compliance plan. (a) The Director may deny an application for a...

10 CFR 76.111 - Physical security, material control and accounting, and protection of certain information.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Physical security, material control and accounting, and protection of certain information. 76.111 Section 76.111 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.111 Physical security, material control...

10 CFR 76.74 - Computation and extension of time.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Computation and extension of time. 76.74 Section 76.74 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.74 Computation and extension of time. (a) In computing any period of time, the day of the act...

10 CFR 76.74 - Computation and extension of time.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Computation and extension of time. 76.74 Section 76.74 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.74 Computation and extension of time. (a) In computing any period of time, the day of the act...

10 CFR 76.74 - Computation and extension of time.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Computation and extension of time. 76.74 Section 76.74 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.74 Computation and extension of time. (a) In computing any period of time, the day of the act...

10 CFR 76.119 - Security facility approval and safeguarding of National Security Information and Restricted Data.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Security facility approval and safeguarding of National Security Information and Restricted Data. 76.119 Section 76.119 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.119 Security facility...

10 CFR 76.119 - Security facility approval and safeguarding of National Security Information and Restricted Data.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Security facility approval and safeguarding of National Security Information and Restricted Data. 76.119 Section 76.119 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.119 Security facility...

10 CFR 76.64 - Denial of certificate or compliance plan.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Denial of certificate or compliance plan. 76.64 Section 76.64 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.64 Denial of certificate or compliance plan. (a) The Director may deny an application for a...

10 CFR 76.62 - Issuance of certificate and/or approval of compliance plan.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Issuance of certificate and/or approval of compliance plan. 76.62 Section 76.62 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.62 Issuance of certificate and/or approval of compliance plan. (a) Upon...

10 CFR 76.64 - Denial of certificate or compliance plan.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Denial of certificate or compliance plan. 76.64 Section 76.64 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.64 Denial of certificate or compliance plan. (a) The Director may deny an application for a...

10 CFR 76.119 - Security facility approval and safeguarding of National Security Information and Restricted Data.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Security facility approval and safeguarding of National Security Information and Restricted Data. 76.119 Section 76.119 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.119 Security facility...

10 CFR 76.62 - Issuance of certificate and/or approval of compliance plan.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Issuance of certificate and/or approval of compliance plan. 76.62 Section 76.62 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.62 Issuance of certificate and/or approval of compliance plan. (a) Upon...

10 CFR 76.74 - Computation and extension of time.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Computation and extension of time. 76.74 Section 76.74 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.74 Computation and extension of time. (a) In computing any period of time, the day of the act...

10 CFR 76.111 - Physical security, material control and accounting, and protection of certain information.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Physical security, material control and accounting, and protection of certain information. 76.111 Section 76.111 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.111 Physical security, material control...

10 CFR 76.119 - Security facility approval and safeguarding of National Security Information and Restricted Data.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Security facility approval and safeguarding of National Security Information and Restricted Data. 76.119 Section 76.119 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.119 Security facility...

10 CFR 76.74 - Computation and extension of time.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Computation and extension of time. 76.74 Section 76.74 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.74 Computation and extension of time. (a) In computing any period of time, the day of the act...

10 CFR 76.111 - Physical security, material control and accounting, and protection of certain information.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Physical security, material control and accounting, and protection of certain information. 76.111 Section 76.111 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.111 Physical security, material control...

10 CFR 76.111 - Physical security, material control and accounting, and protection of certain information.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Physical security, material control and accounting, and protection of certain information. 76.111 Section 76.111 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.111 Physical security, material control...

10 CFR 76.64 - Denial of certificate or compliance plan.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Denial of certificate or compliance plan. 76.64 Section 76.64 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.64 Denial of certificate or compliance plan. (a) The Director may deny an application for a...

10 CFR 76.62 - Issuance of certificate and/or approval of compliance plan.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Issuance of certificate and/or approval of compliance plan. 76.62 Section 76.62 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Certification § 76.62 Issuance of certificate and/or approval of compliance plan. (a) Upon...

10 CFR 76.113 - Formula quantities of strategic special nuclear material-Category I.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Formula quantities of strategic special nuclear material-Category I. 76.113 Section 76.113 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.113 Formula quantities of strategic special nuclear material...

10 CFR 76.113 - Formula quantities of strategic special nuclear material-Category I.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Formula quantities of strategic special nuclear material-Category I. 76.113 Section 76.113 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.113 Formula quantities of strategic special nuclear material...

10 CFR 76.113 - Formula quantities of strategic special nuclear material-Category I.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Formula quantities of strategic special nuclear material-Category I. 76.113 Section 76.113 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.113 Formula quantities of strategic special nuclear material...

10 CFR 76.113 - Formula quantities of strategic special nuclear material-Category I.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Formula quantities of strategic special nuclear material-Category I. 76.113 Section 76.113 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.113 Formula quantities of strategic special nuclear material...

10 CFR 76.113 - Formula quantities of strategic special nuclear material-Category I.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Formula quantities of strategic special nuclear material-Category I. 76.113 Section 76.113 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) CERTIFICATION OF GASEOUS DIFFUSION PLANTS Safeguards and Security § 76.113 Formula quantities of strategic special nuclear material...

Determination of Molecular Size and Avogadro's Number: A Student Experiment

ERIC Educational Resources Information Center

Alexandrakis, George C.

1978-01-01

Describes an experiment for estimating molecular size and Avogadro's number. Uses the diffusion length of iodine in air at 100 degrees Celsius as a function of time, and the change in volume of a small quantity of carbon dioxide as it goes from the solid to the gaseous state. (GA)

76 FR 43732 - Agency Information Collection Activities: Submission for the Office of Management and Budget (OMB...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-21

... NOED and relates to circumstances which may arise where a nuclear power plant licensee's compliance... without a corresponding health and safety benefit. Similarly, for a gaseous diffusion plant, circumstances...'s or certificate holder's conclusion that the request does not have a potential adverse impact on...

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

Schmoyer, RLS

The United States Department of Energy (DOE) currently manages the UF{sub 6} Cylinder Project. The project was formed to maintain and safely manage the depleted uranium hexafluoride (UF{sub 6}) stored in approximately 50,000 carbon steel cylinders. The cylinders are located at three DOE sites: the ETTP site (K-25) at Oak Ridge, Tennessee; the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The System Requirements Document (SRD) (LMES 1997a) delineates the requirements of the project. The appropriate actions needed to fulfill these requirements are then specified within the System Engineering Managementmore » Plan (SEMP) (LMES 1997b). This report documents activities that in whole or in part satisfy specific requirements and actions stated in the UF{sub 6} Cylinder Project SRD and SEMP with respect to forecasting cylinder conditions. The results presented here supercede those presented previously (Lyon 1995, 1996, 1997, 1998, 2000). Many of the wall thickness projections made in this report are conservative, because they are based on the assumption that corrosion trends will continue, despite activities such as improved monitoring, relocations to better storage, and painting.« less

Development of a passive sampler for gaseous mercury

NASA Astrophysics Data System (ADS)

Gustin, M. S.; Lyman, S. N.; Kilner, P.; Prestbo, E.

2011-10-01

Here we describe work toward development of the components of a cost effective passive sampling system for gaseous Hg that could be broadly deployed by nontechnical staff. The passive sampling system included an external shield to reduce turbulence and exposure to precipitation and dust, a diffusive housing that directly protects the collection surface during deployment and handling, and a collection surface. A protocol for cleaning and deploying the sampler and an analytical method were developed. Our final design consisted of a polycarbonate external shield enclosing a custom diffusive housing made from expanded PTFE tubing. Two collection surfaces were investigated, gold sputter-coated quartz plates and silver wires. Research showed the former would require extensive quality control for use, while the latter had interferences with other atmosphere constituents. Although the gold surface exhibited the best performance over space and time, gradual passivation would limit reuse. For both surfaces lack of contamination during shipping, deployment and storage indicated that the handling protocols developed worked well with nontechnical staff. We suggest that the basis for this passive sampling system is sound, but further exploration and development of a reliable collection surface is needed.

Characteristics of Gaseous Diffusion Flames with High Temperature Combustion Air in Microgravity

NASA Technical Reports Server (NTRS)

Ghaderi, M.; Gupta, A. K.

2003-01-01

The characteristics of gaseous diffusion flames have been obtained using high temperature combustion air under microgravity conditions. The time resolved flame images under free fall microgravity conditions were obtained from the video images obtained. The tests results reported here were conducted using propane as the fuel and about 1000 C combustion air. The burner included a 0.686 mm diameter central fuel jet injected into the surrounding high temperature combustion air. The fuel jet exit Reynolds number was 63. Several measurements were taken at different air preheats and fuel jet exit Reynolds number. The resulting hybrid color flame was found to be blue at the base of the flame followed by a yellow color flame. The length and width of flame during the entire free fall conditions has been examined. Also the relative flame length and width for blue and yellow portion of the flame has been examined under microgravity conditions. The results show that the flame length decreases and width increases with high air preheats in microgravity condition. In microgravity conditions the flame length is larger with normal temperature combustion air than high temperature air.

Seismic Velocity Measurements at Expanded Seismic Network Sites

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

Woolery, Edward W; Wang, Zhenming

2005-01-01

Structures at the Paducah Gaseous Diffusion Plant (PGDP), as well as at other locations in the northern Jackson Purchase of western Kentucky may be subjected to large far-field earthquake ground motions from the New Madrid seismic zone, as well as those from small and moderate-sized local events. The resultant ground motion a particular structure is exposed from such event will be a consequence of the earthquake magnitude, the structures' proximity to the event, and the dynamic and geometrical characteristics of the thick soils upon which they are, of necessity, constructed. This investigation evaluated the latter. Downhole and surface (i.e., refractionmore » and reflection) seismic velocity data were collected at the Kentucky Seismic and Strong-Motion Network expansion sites in the vicinity of the Paducah Gaseous Diffusion Plant (PGDP) to define the dynamic properties of the deep sediment overburden that can produce modifying effects on earthquake waves. These effects are manifested as modifications of the earthquake waves' amplitude, frequency, and duration. Each of these three ground motion manifestations is also fundamental to the assessment of secondary earthquake engineering hazards such as liquefaction.« less

Purging of a tank-mounted multilayer insulation system by gas diffusion

NASA Technical Reports Server (NTRS)

Sumner, I. E.

1978-01-01

The investigation was conducted on a multilayer insulation (MLI) system mounted on a spherical liquid hydrogen propellant tank. The MLI consisted of two blankets of insulation each containing 15 double-aluminized Mylar radiation shields separated by double silk net spacers. The gaseous nitrogen initially contained within the MLI system and vacuum chamber was purged with gaseous helium introduced both underneath the MLI and into the vacuum chamber. The MLI panels were assumed to be purged primarily by means of gas diffusion. Overall, test results indicated that nitrogen concentrations well below 1 percent could be achieved everywhere within the MLI system. Typical times to achieve 1 percent nitrogen concentration within the MLI panels ranged from 69 minutes at the top of the tank to 158 minutes at the bottom of the tank. Four space-hold thermal performance tests indicated no significant thermal degradation of the MLI system had occurred due to the purge tests conducted. The final measured heat input attributed to the MLI was 7.23 watts as compared to 7.18 watts for the initial baseline thermal performance test.

Report on the biological monitoring program at Paducah Gaseous Diffusion Plant, January--December 1996

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

Kszos, L.A.; Konetsky, B.K.; Peterson, M.J.

1997-06-01

On September 24, 1987, the Commonwealth of Kentucky Natural Resources and Environmental Protection Cabinet issued an Agreed Order that required the development of a Biological Monitoring Program (BMP) for the Paducah Gaseous diffusion Plant (PGDP). The PGDP BMP was conducted by the University of Kentucky Between 1987 and 1992 and by staff of the Environmental Sciences Division (ESD) at Oak Ridge National Laboratory (ORNL) from 1991 to present. The goals of BMP are to (1) demonstrate that the effluent limitations established for PGDP protect and maintain the use of Little Bayou and Big Bayou creeks for growth and propagation ofmore » fish and other aquatic life, (2) characterize potential environmental impacts, and (3) document the effects of pollution abatement facilities on stream. The BMP for PGDP consists of three major tasks: (1) effluent toxicity monitoring, (2) bioaccumulation studies, and (3) ecological surveys of stream communities (i.e., benthic macroinvertebrates and fish). This report focuses on ESD activities occurring from January 1996 to December 1996, although activities conducted outside this time period are included as appropriate.« less

Evaluation of volatilization as a natural attenuation pathway for MTBE

USGS Publications Warehouse

Lahvis, Matthew A.; Baehr, Arthur L.; Baker, Ronald J.

2004-01-01

Volatilization and diffusion through the unsaturated zone can be an important pathway for natural attenuation remediation of methyl tert-butyl ether (MTBE) at gasoline spill sites. The significance of this pathway depends primarily on the distribution of immiscible product within the unsaturated zone and the relative magnitude of aqueous-phase advection (ground water recharge) to gaseous-phase diffusion. At a gasoline spill site in Laurel Bay, South Carolina, rates of MTBE volatilization from ground water downgradient from the source are estimated by analyzing the distribution of MTBE in the unsaturated zone above a solute plume. Volatilization rates of MTBE from ground water determined by transport modeling ranged from 0.0020 to 0.0042 g m-2/year, depending on the assumed rate of ground water recharge. Although diffusive conditions at the Laurel Bay site are favorable for volatilization, mass loss of MTBE is insignificant over the length (230 m) of the solute plume. Based on this analysis, significant volatilization of MTBE from ground water downgradient from source areas at other sites is not likely. In contrast, model results indicate that volatilization coupled with diffusion to the atmosphere could be a significant mass loss pathway for MTBE in source areas where residual product resides above the capillary zone. Although not documented, mass loss of MTBE at the Laurel Bay site due to volatilization and diffusion to the atmosphere are predicted to be two to three times greater than mass loading of MTBE to ground water due to dissolution and recharge. This result would imply that volatilization in the source zone may be the critical natural attenuation pathway for MTBE at gasoline spill sites, especially when considering capillary zone limitations on volatilization of MTBE from ground water and the relative recalcitrance of MTBE to biodegradation.

Formation of a protocluster: A virialized structure from gravoturbulent collapse. II. A two-dimensional analytical model for a rotating and accreting system

NASA Astrophysics Data System (ADS)

Lee, Yueh-Ning; Hennebelle, Patrick

2016-06-01

Context. Most stars are born in the gaseous protocluster environment where the gas is reprocessed after the global collapse from the diffuse molecular cloud. The knowledge of this intermediate step gives more accurate constraints on star formation characteristics. Aims: We demonstrate that a virialized globally supported structure, in which star formation happens, is formed out of a collapsing molecular cloud, and we derive a mapping from the parent cloud parameters to the protocluster to predict its properties with a view to confront analytical calculations with observations and simulations. Methods: We decomposed the virial theorem into two dimensions to account for the rotation and the flattened geometry. Equilibrium was found by balancing rotation, turbulence, and self-gravity, while turbulence was maintained through accretion driving and it dissipates in one crossing time. We estimated the angular momentum and the accretion rate of the protocluster from the parent cloud properties. Results: The two-dimensional virial model predicts the size and velocity dispersion given the mass of the protocluster and that of the parent cloud. The gaseous protoclusters lie on a sequence of equilibrium with the trend R ~ M0.5 with limited variations, depending on the evolutionary stage, parent cloud, and parameters that are not well known, such as turbulence driving efficiency by accretion and turbulence anisotropy. The model reproduces observations and simulation results successfully. Conclusions: The properties of protoclusters follow universal relations and they can be derived from that of the parent cloud. The gaseous protocluster is an important primary stage of stellar cluster formation, and should be taken into account when studying star formation. Using simple estimates to infer the peak position of the core mass function (CMF) we find a weak dependence on the cluster mass, suggesting that the physical conditions inside protoclusters may contribute to set a CMF, and by extension an initial mass function (IMF), that appears to be independent of the environment.

Electrets and plant fluorometers used in field studies to measure hydrogen chloride produced during Space Shuttle launches

NASA Technical Reports Server (NTRS)

Milligan, J. E.; Swoboda, G. D.; Susko, M.

1985-01-01

The results of the field tests of two monitoring device techniques, electrets and plant fluorometers are analyzed in order to determine the environmental effects of launch by-products and the extent of these effects. The STS launches are used because the Shuttle emits 2 1/2 times more HCl than any previous systems, it produces a voluminous ground cloud and, most important, it produces near field HCl deposition and revolatilization, far-field acid washout/rainout, and gaseous HCl diffusion. Field evaluations of electrets at STS-5, STS-6, and STS-8 have shown that qualitative assessments can be made for areas lightly or moderately impacted by gaseous and aerosol HCl. Field evaluation of the plant productivity fluorometer at STS-8 has shown that this system is also useful for qualitative assessment in areas lightly, moderately, or heavily affected by gaseous and aerosol HCl. Quantitative prediction of HCl may be possible in lightly and moderately affected areas, given deposition rates correlation.

Combustion Processes in Hybrid Rocket Engines

NASA Technical Reports Server (NTRS)

Venkateswaran,S.; Merkle, C. L.

1996-01-01

In recent years, there has been a resurgence of interest in the development of hybrid rocket engines for advanced launch vehicle applications. Hybrid propulsion systems use a solid fuel such as hydroxyl-terminated polybutadiene (HTPB) along with a gaseous/liquid oxidizer. The performance of hybrid combustors depends on the convective and radiative heat fluxes to the fuel surface, the rate of pyrolysis in the solid phase, and the turbulent combustion processes in the gaseous phases. These processes in combination specify the regression rates of the fuel surface and thereby the utilization efficiency of the fuel. In this paper, we employ computational fluid dynamics (CFD) techniques in order to gain a quantitative understanding of the physical trends in hybrid rocket combustors. The computational modeling is tailored to ongoing experiments at Penn State that employ a two dimensional slab burner configuration. The coordinated computational/experimental effort enables model validation while providing an understanding of the experimental observations. Computations to date have included the full length geometry with and with the aft nozzle section as well as shorter length domains for extensive parametric characterization. HTPB is sed as the fuel with 1,3 butadiene being taken as the gaseous product of the pyrolysis. Pure gaseous oxygen is taken as the oxidizer. The fuel regression rate is specified using an Arrhenius rate reaction, which the fuel surface temperature is given by an energy balance involving gas-phase convection and radiation as well as thermal conduction in the solid-phase. For the gas-phase combustion, a two step global reaction is used. The standard kappa - epsilon model is used for turbulence closure. Radiation is presently treated using a simple diffusion approximation which is valid for large optical path lengths, representative of radiation from soot particles. Computational results are obtained to determine the trends in the fuel burning or regression rates as a function of the head-end oxidizer mass flux, G=rho(e)U(e), and the chamber pressure. Furthermore, computation of the full slab burner configuration has also been obtained for various stages of the burn. Comparisons with available experimental data from small scale tests conducted by General Dynamics-Thiokol-Rocketdyne suggest reasonable agreement in the predicted regression rates. Future work will include: (1) a model for soot generation in the flame for more quantitative radiative transfer modelling, (2) a parametric study of combustion efficiency, and (3) transient calculations to help determine the possible mechanisms responsible for combustion instability in hybrid rocket motors.

The Dynamical Evolution of a Tubular Leonid Persistent Train

NASA Astrophysics Data System (ADS)

Jenniskens, Peter; Nugent, David; Plane, John M. C.

The dynamical evolution of the persistent train of a bright Leonid meteor was examined for evidence of the source of the luminosity and the physical conditions in the meteor path. The train consisted of two parallel somewhat diffuse luminous tracks, interpreted as the walls of a tube. A general lack of wind shear along the trail allowed these structures to remain intact for nearly 200 s, from which it was possible to determine that the tubular structure expanded at a near constant 10.5 ms^-1, independent of altitude between 86 and 97 km. An initial fast decrease of train intensity below 90 km was followed by an increase in intensity and then a gradual decrease at longer times, whereas at high altitudes the integrated intensity was nearly constant with time. These results are compared to a model that describes the dynamical evolution of the train by diffusion, following an initial rapid expansion of the hot gaseous trail behind the meteoroid. The train luminosity is produced by O (^1S) emission at 557 nm, driven by elevated atomic O levels produced by the meteor impact, as well as chemiluminescent reactions of the ablated metals Na and Fe with O_3. Ozone is rapidly removed within the train, both by thermal decomposition and catalytic destruction by the metallic species. Hence, the brightest emission occurs at the edge of the train between outwardly diffusing metallic species and inwardly diffusing O_3. Although the model is able to account plausibly for a number of characteristic features of the train evolution, significant discrepancies remain that cannot casily be resolved.

The Dynamical Evolution of A Tubular Leonid Persistent Train

NASA Technical Reports Server (NTRS)

Jenniskens, Peter; Nugent, David; Plane, John M. C.; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

The dynamical evolution of the persistent train of a bright Leonid meteor was examined for evidence of the source of the luminosity and the physical conditions in the meteor path. The train consisted of two parallel somewhat diffuse luminous tracks, interpreted as the walls of a tube. A general lack of wind shear along the trail allowed these structures to remain intact for nearly 200 s, from which it was possible to determine that the tubular structure expanded at a near constant 10.5 m/s, independent of altitude between 86 and 97 km. An initial fast decrease of train intensity below 90 km was followed by an increase in intensity and then a gradual decrease at longer times, whereas at high attitudes the integrated intensity was nearly constant with time. These results are compared to a model that describes the dynamical evolution of the train by diffusion, following an initial rapid expansion of the hot gaseous trail behind the meteoroid. The train luminosity is produced by O ((sup 1)S) emission at 557 nm, driven by elevated atomic O levels produced by the meteor impact, as well as chemiluminescent reactions of the ablated metals Na and Fe with O3. Ozone is rapidly removed within the train, both by thermal decomposition and catalytic destruction by the metallic species. Hence, the brightest emission occurs at the edge of the train between outwardly diffusing metallic species and inwardly diffusing O3. Although the model is able to account plausibly for a number of characteristic features of the train evolution, significant discrepancies remain that cannot easily be resolved.

Sampling and Chemical Analysis Quality Assurance Requirements for the Navy Installation Restoration Program

DTIC Science & Technology

1988-06-01

Mencer Mitzi S. Miller Dist J. W. Zolyniak Prepared by the Oak Ridge Gaseous Diffusion Plant Oak Ridge, Tennessee 37831 operated by MARTIN MARIETTA...Drop A20 S Oak Ridge, TN 37830 * Mailing Address for Regular Mail: Martin Marietta Energy Systems, Inc. P.O. Box 2003 Oak Ridge, TN 37831-7440 Mitzi

Report on the Biological Monitoring Program at Paducah Gaseous Diffusion Plant, January--December 1995

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

Kszos, L.A.

1996-04-01

The BMP for PGDP consists of three major tasks: (1) effluent and ambient toxicity monitoring, (2) bioaccumulation studies, and (3) ecological surveys of stream communities (benthic macroinvertebrates, fish). This report focuses on ESD activities occurring from Jan. 1995 to Dec. 1995, although activities conducted outside this period are included as appropriate.

78 FR 53147 - Subcommittee for Dose Reconstruction Reviews (SDRR), Advisory Board on Radiation and Worker...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-28

... responsibility for funding, staffing, and operating the Advisory Board to HHS, which subsequently delegated this authority to CDC. NIOSH implements this responsibility for CDC. The charter was issued on August 3, 2001... Portsmouth Gaseous Diffusion Plants cases from sets 10-13). The agenda is subject to change as priorities...

Efficiency of radial transport of ices in protoplanetary disks probed with infrared observations: the case of CO2

NASA Astrophysics Data System (ADS)

Bosman, Arthur D.; Tielens, Alexander G. G. M.; van Dishoeck, Ewine F.

2018-04-01

Context. Radial transport of icy solid material from the cold outer disk to the warm inner disk is thought to be important for planet formation. However, the efficiency at which this happens is currently unconstrained. Efficient radial transport of icy dust grains could significantly alter the composition of the gas in the inner disk, enhancing the gas-phase abundances of the major ice constituents such as H2O and CO2. Aim. Our aim is to model the gaseous CO2 abundance in the inner disk and use this to probe the efficiency of icy dust transport in a viscous disk. From the model predictions, infrared CO2 spectra are simulated and features that could be tracers of icy CO2, and thus dust, radial transport efficiency are investigated. Methods: We have developed a 1D viscous disk model that includes gas accretion and gas diffusion as well as a description for grain growth and grain transport. Sublimation and freeze-out of CO2 and H2O has been included as well as a parametrisation of the CO2 chemistry. The thermo-chemical code DALI was used to model the mid-infrared spectrum of CO2, as can be observed with JWST-MIRI. Results: CO2 ice sublimating at the iceline increases the gaseous CO2 abundance to levels equal to the CO2 ice abundance of 10-5, which is three orders of magnitude more than the gaseous CO2 abundances of 10-8 observed by Spitzer. Grain growth and radial drift increase the rate at which CO2 is transported over the iceline and thus the gaseous CO2 abundance, further exacerbating the problem. In the case without radial drift, a CO2 destruction rate of at least 10-11 s-1 or a destruction timescale of at most 1000 yr is needed to reconcile model prediction with observations. This rate is at least two orders of magnitude higher than the fastest destruction rate included in chemical databases. A range of potential physical mechanisms to explain the low observed CO2 abundances are discussed. Conclusions: We conclude that transport processes in disks can have profound effects on the abundances of species in the inner disk such as CO2. The discrepancy between our model and observations either suggests frequent shocks in the inner 10 AU that destroy CO2, or that the abundant midplane CO2 is hidden from our view by an optically thick column of low abundance CO2 due to strong UV and/or X-rays in the surface layers. Modelling and observations of other molecules, such as CH4 or NH3, can give further handles on the rate of mass transport.

Numerical investigation of the effects of iron oxidation reactions on the fume formation mechanism in arc welding

NASA Astrophysics Data System (ADS)

Sanibondi, Paolo

2015-09-01

Fume formation during arc welding has been modelled using a stochastic approach taking into account iron oxidation reactions. The model includes the nucleation and condensation of Fe and FeO vapours, the reaction of gaseous O2 and O on the nanoparticle surface, the coagulation of the nanoparticles including a sintering time as a function of temperature and composition, assuming chemical equilibrium for species in the gaseous phase. Results suggest that fumes generated in gas metal arc welding with oxidizing shielding mixtures are composed of aggregates of primary particles that are nucleated from gas-phase FeO and further oxidized to Fe3O4 and Fe2O3 in the liquid and solid phase, respectively. The composition of the fumes at the end of the formation process depends on the relative initial concentration of Fe and O2 species in the gas mixture and on the diameter of the primary particles that compose the aggregates: as the oxidation reactions are driven by deposition of oxygen on nanoparticle surface, the oxidation of larger particles is slower than that of smaller particles because of their lower surface to volume ratio. Solid-state diffusion is limiting the oxidation process at temperatures lower than 1500 K, inducing the formation of not fully oxidized particles composed of Fe3O4.

Improved hatch rate in helium-oxygen by reducing shell diffusion area.

PubMed

Weiss, H S

1975-03-01

For eggs incubating in a He atmosphere (79% He/21% O2), covering approximately 50% of the shell with melted paraffin improves hatch rate to control values (from 20% to 74%) and decreases egg weight loss to control values (from 17% to 9%). In air (79% N2/21% O2) the same paraffin treatment depresses hatch rate. The role of the inert gases in incubation appears to be an indirect one related to their modification of the rate of gaseous flux across the shell with the adverse effects of He due to excessively rapid diffusion.

Dual-channel microreactor for gas-liquid syntheses.

PubMed

Park, Chan Pil; Kim, Dong-Pyo

2010-07-28

A microreactor consisting of two microfluidic channels that are separated by a thin membrane is devised for intimate contact between gas and liquid phases. Gas flowing in one microchannel can diffuse into the liquid flowing in the other microchannel through the thin membrane. An oxidative Heck reaction carried out in the dual-channel (DC) microreactor, in which gaseous oxygen plays a key role in the catalytic reaction, shows the significant improvement that can be made over the traditional batch reactor and the conventional segmental microreactor in terms of yield, selectivity, and reaction time. It also allows independent control of the flow of the gaseous reagent. The proposed DC microreactor should prove to be a powerful tool for fully exploring gas-liquid microchemistry.

Diffusion of magnetic field via turbulent reconnection

NASA Astrophysics Data System (ADS)

Santos de Lima, Reinaldo; Lazarian, Alexander; de Gouveia Dal Pino, Elisabete M.; Cho, Jungyeon

2010-05-01

The diffusion of astrophysical magnetic fields in conducting fluids in the presence of turbulence depends on whether magnetic fields can change their topology via reconnection in highly conducting media. Recent progress in understanding fast magnetic reconnection in the presence of turbulence is reassuring that the magnetic field behavior in computer simulations and turbulent astrophysical environments is similar, as far as magnetic reconnection is concerned. This makes it meaningful to perform MHD simulations of turbulent flows in order to understand the diffusion of magnetic field in astrophysical environments. Our studies of magnetic field diffusion in turbulent medium reveal interesting new phenomena. First of all, our 3D MHD simulations initiated with anti-correlating magnetic field and gaseous density exhibit at later times a de-correlation of the magnetic field and density, which corresponds well to the observations of the interstellar media. While earlier studies stressed the role of either ambipolar diffusion or time-dependent turbulent fluctuations for de-correlating magnetic field and density, we get the effect of permanent de-correlation with one fluid code, i.e. without invoking ambipolar diffusion. In addition, in the presence of gravity and turbulence, our 3D simulations show the decrease of the magnetic flux-to-mass ratio as the gaseous density at the center of the gravitational potential increases. We observe this effect both in the situations when we start with equilibrium distributions of gas and magnetic field and when we follow the evolution of collapsing dynamically unstable configurations. Thus the process of turbulent magnetic field removal should be applicable both to quasi-static subcritical molecular clouds and cores and violently collapsing supercritical entities. The increase of the gravitational potential as well as the magnetization of the gas increases the segregation of the mass and magnetic flux in the saturated final state of the simulations, supporting the notion that the reconnection-enabled diffusivity relaxes the magnetic field + gas system in the gravitational field to its minimal energy state. This effect is expected to play an important role in star formation, from its initial stages of concentrating interstellar gas to the final stages of the accretion to the forming protostar.

STATEQ: a nonlinear least-squares code for obtaining Martin thermodynamic representations of fluids in the gaseous and dense gaseous regions

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

Milora, S. L.

1976-02-01

The use of the code NLIN (IBM Share Program No. 1428) to obtain empirical thermodynamic pressure-volume-temperature (P-V-T) relationships for substances in the gaseous and dense gaseous states is described. When sufficient experimental data exist, the code STATEQ will provide least-squares estimates for the 21 parameters of the Martin model. Another code, APPROX, is described which also obtains parameter estimates for the model by making use of the approximate generalized behavior of fluids. Use of the codes is illustrated in obtaining thermodynamic representations for isobutane. (auth)

Low cost solar array project cell and module formation research area: Process research of non-CZ silicon material

NASA Technical Reports Server (NTRS)

1981-01-01

Liquid diffusion masks and liquid applied dopants to replace the CVD Silox masking and gaseous diffusion operations specified for forming junctions in the Westinghouse baseline process sequence for producing solar cells from dendritic web silicon were investigated. The baseline diffusion masking and drive processes were compared with those involving direct liquid applications to the dendritic web silicon strips. Attempts were made to control the number of variables by subjecting dendritic web strips cut from a single web crystal to both types of operations. Data generated reinforced earlier conclusions that efficiency levels at least as high as those achieved with the baseline back junction formation process can be achieved using liquid diffusion masks and liquid dopants. The deliveries of dendritic web sheet material and solar cells specified by the current contract were made as scheduled.

Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation

NASA Technical Reports Server (NTRS)

Daryabeigi, Kamran; Cunnington, George R.; Knutson, Jeffrey R.

2012-01-01

Combined radiation and conduction heat transfer through a high-temperature, high-porosity, rigid multiple-fiber fibrous insulation was modeled using a thermal model previously used to model heat transfer in flexible single-fiber fibrous insulation. The rigid insulation studied was alumina enhanced thermal barrier (AETB) at densities between 130 and 260 kilograms per cubic meter. The model consists of using the diffusion approximation for radiation heat transfer, a semi-empirical solid conduction model, and a standard gas conduction model. The relevant parameters needed for the heat transfer model were estimated from steady-state thermal measurements in nitrogen gas at various temperatures and environmental pressures. The heat transfer modeling methodology was evaluated by comparison with standard thermal conductivity measurements, and steady-state thermal measurements in helium and carbon dioxide gases. The heat transfer model is applicable over the temperature range of 300 to 1360 K, pressure range of 0.133 to 101.3 x 10(exp 3) Pa, and over the insulation density range of 130 to 260 kilograms per cubic meter in various gaseous environments.

ESTIMATING GASEOUS EXCHANGES BETWEEN THE ATMOSPHERE AND PLANTS USING A COUPLED BIOCHEMICAL DRY DEPOSITION MODEL

EPA Science Inventory

To study gaseous exchanges between the soil, biosphere and atmosphere, a biochemical model was coupled with the latest version of Meyers Multi-Layer Deposition Model. The biochemical model describes photosynthesis and respiration and their coupling with stomatal resistance for...

Oxidation-induced contraction and strengthening of boron fibers

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.; Wagner, T. C.

1981-01-01

An investigation was conducted to measure and understand the physical and mechanical effects that occur in boron fibers during and after thermal treatment in a controlled oxygen argon gaseous mixture. Of principal concern was the optimization of this treatment as a secondary processing method for significantly improving fiber tensile strength. Strengthening was accomplished by an oxidation induced axial contraction of the fiber and a resulting axial compression of strength limiting flaws within the fiber's tungsten boride core. Various physical observations were used to develop mechanistic models for oxidation, contraction, and flow formation. Processing guidelines are discussed for possibly exceeding the 5.5 GN/sq m strength limit and also for achieving fiber strengthening during application of boron containing diffusion barrier coatings.

Application of gas diffusion biocathode in microbial electrosynthesis from carbon dioxide.

PubMed

Bajracharya, Suman; Vanbroekhoven, Karolien; Buisman, Cees J N; Pant, Deepak; Strik, David P B T B

2016-11-01

Microbial catalysis of carbon dioxide (CO 2 ) reduction to multi-carbon compounds at the cathode is a highly attractive application of microbial electrosynthesis (MES). The microbes reduce CO 2 by either taking the electrons or reducing the equivalents produced at the cathode. While using gaseous CO 2 as the carbon source, the biological reduction process depends on the dissolution and mass transfer of CO 2 in the electrolyte. In order to deal with this issue, a gas diffusion electrode (GDE) was investigated by feeding CO 2 through the GDE into the MES reactor for its reduction at the biocathode. A combination of the catalyst layer (porous activated carbon and Teflon binder) and the hydrophobic gas diffusion layer (GDL) creates a three-phase interface at the electrode. So, CO 2 and reducing equivalents will be available to the biocatalyst on the cathode surface. An enriched inoculum consisting of acetogenic bacteria, prepared from an anaerobic sludge, was used as a biocatalyst. The cathode potential was maintained at -1.1 V vs Ag/AgCl to facilitate direct and/or hydrogen-mediated CO 2 reduction. Bioelectrochemical CO 2 reduction mainly produced acetate but also extended the products to ethanol and butyrate. Average acetate production rates of 32 and 61 mg/L/day, respectively, with 20 and 80 % CO 2 gas mixture feed were achieved with 10 cm 2 of GDE. The maximum acetate production rate remained 238 mg/L/day for 20 % CO 2 gas mixture. In conclusion, a gas diffusion biocathode supported bioelectrochemical CO 2 reduction with enhanced mass transfer rate at continuous supply of gaseous CO 2 . Graphical abstract ᅟ.

Determination of gaseous fission product behavior near the cerium dioxide Σ 3 (111)/[11 bar0] tilt grain boundary via first-principles study

NASA Astrophysics Data System (ADS)

Xi, Jianqi; Liu, Bin; Xu, Haixuan; Zhang, Yanwen; Weber, William J.

2018-02-01

Grain boundaries (GBs) are the most abundant structural defects in nanostructured nuclear fuels and play an important role in determining fission product behavior, which further affects the performance of nuclear fuels. In this work, cerium dioxide (CeO2) is used as a surrogate material for mixed oxide fuels to understand gaseous fission product behavior, specifically Xe. First-principles calculations are employed to comprehensively study the behavior of Xe and trap sites for Xe near the Σ 3 (111)/[11 bar0] grain boundary in CeO2, which will provide guidance on overall trends for Xe stability and diffusion at grain boundaries vs in the bulk. Significant segregation behavior of trap sites, regardless of charge states, is observed near the GB. This is mainly ascribed to the local atomic structure near the GB, which results in weaker bond strength and more negative segregation energies. For Xe, however, the segregation profile near the GB is different. Our calculations show that, as the size of trap sites increases, the segregation propensity of Xe is reduced. In addition, under hyper-stoichiometric conditions, the solubility of Xe trapped at the GB is significantly higher than that in the bulk, suggesting higher Xe concentration than that in the bulk. The results of this work demonstrate that the diffusion mechanism of Xe in CeO2 is comparable to that in UO2. The diffusion activation energies of Xe atoms in the Σ 3 GB are lower than that in the bulk CeO2. These results suggest that the diffusivity of Xe atoms is higher along the GB than that in the bulk, which enhances the aggregation of Xe atoms near the GB.

10 CFR Appendix C to Part 110 - Illustrative List of Gaseous Diffusion Enrichment Plant Assemblies and Components Under NRC...

Code of Federal Regulations, 2010 CFR

2010-01-01

... and instrumentation surfaces (that come in contact with the gas) must be made of materials that remain... into contact with the process gas are wholly made of, or lined with, UF6-resistant materials. For the... REGULATORY COMMISSION (CONTINUED) EXPORT AND IMPORT OF NUCLEAR EQUIPMENT AND MATERIAL Pt. 110, App. C...

Hydrogen adsorption and diffusion, and subcritical-crack growth in high-strength steels and nickel base alloys

NASA Technical Reports Server (NTRS)

Wei, R. P.; Klier, K.; Simmons, G. W.

1974-01-01

Coordinated studies of the kinetics of crack growth and of hydrogen adsorption and diffusion were initiated to develop information that is needed for a clearer determination of the rate controlling process and possible mechanism for hydrogen enhanced crack growth, and for estimating behavior over a range of temperatures and pressures. Inconel 718 alloy and 18Ni(200) maraging steel were selected for these studies. 18Ni(250) maraging steel, 316 stainless steel, and iron single crystal of (111) orientation were also included in the chemistry studies. Crack growth data on 18Ni(250) maraging steel from another program are included for comparison. No sustained-load crack growth was observed for the Inconel 718 alloy in gaseous hydrogen. Gaseous hydrogen assisted crack growth in the 18Ni maraging steels were characterized by K-independent (Stage 2) extension over a wide range of hydrogen pressures (86 to 2000 torr or 12 kN/m2 to 266 kN/m2) and test temperatures (-60 C to +100 C). The higher strength 18Ni(250) maraging steel was more susceptible than the lower strength 200 grade. A transition temperature was observed, above which crack growth rates became diminishingly small.

Portsmouth Gaseous Diffusion Plant environmental report for 1989

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

Turner, J.W.

1990-10-01

This calendar year 1989 annual report on environmental surveillance of the US Department of Energy's (DOE) Portsmouth Gaseous Diffusion Plant (PORTS) and its environs consists of two parts: the Summary, Discussion, and Conclusions (Part 1) and the Data Presentation (Part 2). The objectives of this report are the following: report 1989 monitoring data for the installation and its environs that may have been affected by operations on the plant site, provide reasonably detailed information about the plant site and plant operations, provide detailed information on input and assumptions used in all calculations, provide trend analyses (where appropriate) to indicate increasesmore » and decreases in environmental impact, and provide general information on plant quality assurance. Routine monitoring and sampling for radiation, radioactive materials, and chemical substances on and off the DOE site are used to document compliance with appropriate standards, to identify trends, to provide information for the public, and to contribute to general environmental knowledge. The surveillance program assists in fulfilling the DOE policy of protecting the public, employees, and environment from harm that could be caused by its activities and reducing negative environmental impacts to the greatest degree practicable. Environmental-monitoring information complements data on specific releases, trends, and summaries. 26 refs.« less

A wind tunnel study of gaseous tracer dispersion in the convective boundary layer capped by a temperature inversion

NASA Astrophysics Data System (ADS)

Fedorovich, E.; Thäter, J.

Results are presented from wind tunnel simulations of gaseous pollutant dispersion in the atmospheric convective boundary layer (CBL) capped by a temperature inversion. The experiments were performed in the thermally stratified wind tunnel of the University of Karlsruhe, Germany. In the tunnel, the case of horizontally evolving, sheared CBL is reproduced. This distinguishes the employed experimental setup from the preceding laboratory and numerical CBL dispersion studies. The diffusive and mixing properties of turbulence in the studied CBL case have been found to be essentially dependent on the stage of the CBL evolution. Effects of the point source elevation on the horizontal variability of the concentration field, and on the ground level concentration as function of distance from the source have been investigated. The applicability of bottom-up/top-down diffusion concept in the simulated CBL case has been evaluated. The influence of surface wind shear and capping inversion strength on the pollutant dispersion and turbulent exchange across the CBL top has been demonstrated. The imposed positive shear across the inversion has been identified as inhibitor of the CBL growth. Comparisons of concentration patterns from the wind tunnel with water tank data are presented.

Development of Detonation Modeling Capabilities for Rocket Test Facilities: Hydrogen-Oxygen-Nitrogen Mixtures

NASA Technical Reports Server (NTRS)

Allgood, Daniel C.

2016-01-01

The objective of the presented work was to develop validated computational fluid dynamics (CFD) based methodologies for predicting propellant detonations and their associated blast environments. Applications of interest were scenarios relevant to rocket propulsion test and launch facilities. All model development was conducted within the framework of the Loci/CHEM CFD tool due to its reliability and robustness in predicting high-speed combusting flow-fields associated with rocket engines and plumes. During the course of the project, verification and validation studies were completed for hydrogen-fueled detonation phenomena such as shock-induced combustion, confined detonation waves, vapor cloud explosions, and deflagration-to-detonation transition (DDT) processes. The DDT validation cases included predicting flame acceleration mechanisms associated with turbulent flame-jets and flow-obstacles. Excellent comparison between test data and model predictions were observed. The proposed CFD methodology was then successfully applied to model a detonation event that occurred during liquid oxygen/gaseous hydrogen rocket diffuser testing at NASA Stennis Space Center.

Experimental and simulation study of a Gaseous oxygen/Gaseous hydrogen vortex cooling thrust chamber

NASA Astrophysics Data System (ADS)

Yu, Nanjia; Zhao, Bo; Li, Gongnan; Wang, Jue

2016-01-01

In this paper, RNG k-ε turbulence model and PDF non-premixed combustion model are used to simulate the influence of the diameter of the ring of hydrogen injectors and oxidizer-to-fuel ratio on the specific impulse of the vortex cooling thrust chamber. The simulation results and the experimental tests of a 2000 N Gaseous oxygen/Gaseous hydrogen vortex cooling thrust chamber reveal that the efficiency of the specific impulse improves significantly with increasing of the diameter of the ring of hydrogen injectors. Moreover, the optimum efficiency of the specific impulse is obtained when the oxidizer-to-fuel ratio is near the stoichiometric ratio.

Dose Modeling Evaluations and Technical Support Document For the Authorized Limits Request for the DOE-Owned Property Outside the Limited Area, Paducah Gaseous Diffusion Plant Paducah, Kentucky

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

Boerner, A. J.; Maldonado, D. G.; Hansen, Tom

2012-09-01

Environmental assessments and remediation activities are being conducted by the U.S. Department of Energy (DOE) at the Paducah Gaseous Diffusion Plant (PGDP), Paducah, Kentucky. The Oak Ridge Institute for Science and Education (ORISE), a DOE prime contractor, was contracted by the DOE Portsmouth/Paducah Project Office (DOE-PPPO) to conduct radiation dose modeling analyses and derive single radionuclide soil guidelines (soil guidelines) in support of the derivation of Authorized Limits (ALs) for 'DOE-Owned Property Outside the Limited Area' ('Property') at the PGDP. The ORISE evaluation specifically included the area identified by DOE restricted area postings (public use access restrictions) and areas licensedmore » by DOE to the West Kentucky Wildlife Management Area (WKWMA). The licensed areas are available without restriction to the general public for a variety of (primarily) recreational uses. Relevant receptors impacting current and reasonably anticipated future use activities were evaluated. In support of soil guideline derivation, a Conceptual Site Model (CSM) was developed. The CSM listed radiation and contamination sources, release mechanisms, transport media, representative exposure pathways from residual radioactivity, and a total of three receptors (under present and future use scenarios). Plausible receptors included a Resident Farmer, Recreational User, and Wildlife Worker. single radionuclide soil guidelines (outputs specified by the software modeling code) were generated for three receptors and thirteen targeted radionuclides. These soil guidelines were based on satisfying the project dose constraints. For comparison, soil guidelines applicable to the basic radiation public dose limit of 100 mrem/yr were generated. Single radionuclide soil guidelines from the most limiting (restrictive) receptor based on a target dose constraint of 25 mrem/yr were then rounded and identified as the derived soil guidelines. An additional evaluation using the derived soil guidelines as inputs into the code was also performed to determine the maximum (peak) dose for all receptors. This report contains the technical basis in support of the DOE?s derivation of ALs for the 'Property.' A complete description of the methodology, including an assessment of the input parameters, model inputs, and results is provided in this report. This report also provides initial recommendations on applying the derived soil guidelines.« less

Investigation of fluorocarbon blowing agents in insulating polymer foams by 19F NMR imaging.

PubMed

Fyfe, C A; Mei, Z; Grondey, H

1996-01-01

Currently, there is no reliable and readily accessible technique with which the distribution and diffusion of blowing agents in rigid insulating foams can be detected and monitored. In this paper, we demonstrate that 19F NMR microscopic imaging together with 19F solid-state MAS NMR spectroscopy is ideally suited for such measurements and yield quantitatively reliable information that will be critical to the development and fabrication of optimized insulating materials with alternative blowing agents. Polystyrene (PS) and polyurethane (PU) foam samples were investigated with the objective of determining quantitatively the amount of blowing agents in the gaseous phase and dissolved in the polymer phase, and to determine and monitor the distribution of the blowing agents in aged foams as a function of time and temperature. The concentrations of the gaseous blowing agents in the cells and dissolved in the solid were simultaneously and quantitatively measured by 19F MAS NMR spectroscopy. An unfaced 1-yr-old PS foam filled with CH3CF2Cl has about 13% of total HCFCs dissolved in the solid; while there is about 24% of HCFCs in the solid of a faced 3-mos-old PU foam filled with CH3CCl2F. The data from 19F NMR imaging demonstrate that the distributions of the blowing agents in an aged foam are quite uniform around the center part (2 cm away from any edge) of a foam board; however, a gradient in blowing agent concentration was found as a function of distance from the initial factory cut edge. The effective diffusion coefficients of the blowing agents can be directly calculated from the imaging data. Quantitative diffusion constants and activation barriers were determined. Additionally, a foam treated with a second blowing agent was monitored with chemical shift selective imaging and the diffusion of the second gas into the foam and the out-diffusion of the original gas were determined.

Creeping gaseous flows through elastic tube and annulus micro-configurations

NASA Astrophysics Data System (ADS)

Elbaz, Shai; Jacob, Hila; Gat, Amir

2016-11-01

Gaseous flows in elastic micro-configurations is relevant to biological systems (e.g. alveolar ducts in the lungs) as well as to applications such as gas actuated soft micro-robots. We here examine the effect of low-Mach-number compressibility on creeping gaseous axial flows through linearly elastic tube and annulus micro-configurations. For steady flows, the leading-order effects of elasticity on the pressure distribution and mass-flux are obtained. For transient flow in a tube with small deformations, elastic effects are shown to be negligible in leading order due to compressibility. We then examine transient flows in annular configurations where the deformation is significant compared with the gap between the inner and outer cylinders defining the annulus. Both compressibility and elasticity are obtained as dominant terms interacting with viscosity. For a sudden flux impulse, the governing non-linear leading order diffusion equation is initially approximated by a porous-medium-equation of order 2.5 for the pressure square. However, as the fluid expand and the pressure decreases, the governing equation degenerates to a porous-medium-equation of order 2 for the pressure.

Experimental and computational data from a small rocket exhaust diffuser

NASA Astrophysics Data System (ADS)

Stephens, Samuel E.

1993-06-01

The Diagnostics Testbed Facility (DTF) at the NASA Stennis Space Center in Mississippi is a versatile facility that is used primarily to aid in the development of nonintrusive diagnostics for liquid rocket engine testing. The DTF consists of a fixed, 1200 lbf thrust, pressure fed, liquid oxygen/gaseous hydrogen rocket engine, and associated support systems. An exhaust diffuser has been fabricated and installed to provide subatmospheric pressures at the exit of the engine. The diffuser aerodynamic design was calculated prior to fabrication using the PARC Navier-Stokes computational fluid dynamics code. The diffuser was then fabricated and tested at the DTF. Experimental data from these tests were acquired to determine the operational characteristics of the system and to correlate the actual and predicted flow fields. The results show that a good engineering approximation of overall diffuser performance can be made using the PARC Navier-Stokes code and a simplified geometry. Correlations between actual and predicted cell pressure and initial plume expansion in the diffuser are good; however, the wall pressure profiles do not correlate as well with the experimental data.

Diffuser Test

NASA Image and Video Library

2007-09-13

Tests begun at Stennis Space Center's E Complex Sept. 13 evaluated a liquid oxygen lead for engine start performance, part of the A-3 Test Facility Subscale Diffuser Risk Mitigation Project at SSC's E-3 Test Facility. Phase 1 of the subscale diffuser project, completed Sept. 24, was a series of 18 hot-fire tests using a 1,000-pound liquid oxygen and gaseous hydrogen thruster to verify maximum duration and repeatability for steam generation supporting the A-3 Test Stand project. The thruster is a stand-in for NASA's developing J-2X engine, to validate a 6 percent scale version of A-3's exhaust diffuser. Testing the J-2X at altitude conditions requires an enormous diffuser. Engineers will generate nearly 4,600 pounds per second of steam to reduce pressure inside A-3's test cell to simulate altitude conditions. A-3's exhaust diffuser has to be able to withstand regulated pressure, temperatures and the safe discharge of the steam produced during those tests. Before the real thing is built, engineers hope to work out any issues on the miniature version. Phase 2 testing is scheduled to begin this month.

METHOD FOR REMOVAL OF LIGHT ISOTOPE PRODUCT FROM LIQUID THERMAL DIFFUSION UNITS

DOEpatents

Hoffman, J.D.; Ballou, J.K.

1957-11-19

A method and apparatus are described for removing the lighter isotope of a gaseous-liquid product from a number of diffusion columns of a liquid thermal diffusion system in two stages by the use of freeze valves. The subject liquid flows from the diffusion columns into a heated sloping capsule where the liquid is vaporized by the action of steam in a heated jacket surrounding the capsule. When the capsule is filled the gas flows into a collector. Flow between the various stages is controlled by freeze valves which are opened and closed by the passage of gas and cool water respectively through coils surrounding portions of the pipes through which the process liquid is passed. The use of the dual stage remover-collector and the freeze valves is an improvement on the thermal diffusion separation process whereby the fraction containing the lighter isotope many be removed from the tops of the diffusion columns without intercolumn flow, or prior stage flow while the contents of the capsule is removed to the final receiver.

Angular resolution of the gaseous micro-pixel detector Gossip

NASA Astrophysics Data System (ADS)

Bilevych, Y.; Blanco Carballo, V.; van Dijk, M.; Fransen, M.; van der Graaf, H.; Hartjes, F.; Hessey, N.; Koppert, W.; Nauta, S.; Rogers, M.; Romaniouk, A.; Veenhof, R.

2011-06-01

Gossip is a gaseous micro-pixel detector with a very thin drift gap intended for a high rate environment like at the pixel layers of ATLAS at the sLHC. The detector outputs not only the crossing point of a traversing MIP, but also the angle of the track, thus greatly simplifying track reconstruction. In this paper we describe a testbeam experiment to examine the angular resolution of the reconstructed track segments in Gossip. We used here the low diffusion gas mixture DME/CO 2 50/50. An angular resolution of 20 mrad for perpendicular tracks could be obtained from a 1.5 mm thin drift volume. However, for the prototype detector used at the testbeam experiment, the resolution of slanting tracks was worsened by poor time resolution of the pixel chip used.

Cool-Flame Burning and Oscillations of Envelope Diffusion Flames in Microgravity

NASA Astrophysics Data System (ADS)

Takahashi, Fumiaki; Katta, Viswanath R.; Hicks, Michael C.

2018-05-01

The two-stage combustion, local extinction, and flame-edge oscillations have been observed in single-droplet combustion tests conducted on the International Space Station. To understand such dynamic behavior of initially enveloped diffusion flames in microgravity, two-dimensional (axisymmetric) computation is performed for a gaseous n-heptane flame using a time-dependent code with a detailed reaction mechanism (127 species and 1130 reactions), diffusive transport, and a simple radiation model (for CO2, H2O, CO, CH4, and soot). The calculated combustion characteristics vary profoundly with a slight movement of air surrounding a fuel source. In a near-quiescent environment (≤ 2 mm/s), with a sufficiently large fuel injection velocity (1 cm/s), extinction of a growing spherical diffusion flame due to radiative heat losses is predicted at the flame temperature at ≈ 1200 K. The radiative extinction is typically followed by a transition to the "cool flame" burning regime (due to the negative temperature coefficient in the low-temperature chemistry) with a reaction zone (at ≈ 700 K) in close proximity to the fuel source. By contrast, if there is a slight relative velocity (≈ 3 mm/s) between the fuel source and the air, a local extinction of the envelope diffusion flame is predicted downstream at ≈ 1200 K, followed by periodic flame-edge oscillations. At higher relative velocities (4 to 10 mm/s), the locally extinguished flame becomes steady state. The present 2D computational approach can help in understanding further the non-premixed "cool flame" structure and flame-flow interactions in microgravity environments.

Isolated Liquid Droplet Combustion: Inhibition and Extinction Studies

NASA Technical Reports Server (NTRS)

Dryer, F. L.; Kroenlein, K. G.; Kazakov, A.; Williams, F. A.; Nayagam, V.

2004-01-01

Introduction of fire suppressants to the ambient environment surrounding a heterogeneous diffusion flame may be an inefficient technique for fire safety in systems without buoyant flows. Carbon dioxide substitution for nitrogen diluent leads to significant modifications of the sphero-symmetric burning behavior of isolated n-heptane droplets, partly through increased heat capacity within the gaseous diffusion flame, but mostly because of modifications in spectral radiative coupling in the gas phase. Effects of longer time scale phenomena such as sooting and slow gas-phase/droplet convection remain to be determined. Similar methodologies can be applied to evaluate the effects and efficacy of chemical inhibitors in the liquid and gas phases.

Thermodynamics and kinetics of pack aluminide coating formation on IN-100

NASA Technical Reports Server (NTRS)

Levine, S. R.; Caves, R. M.

1973-01-01

An investigation of the effects of pack variables on the formation of aluminide coatings on nickel-base superalloy IN-100 was conducted. Also, the thermodynamics and kinetics of coating formation were analyzed. Observed coating weights were in good agreement with predictions made from the analysis. Pack temperature rather than pack aluminum activity controls the principal coating phase formed. In 1 weight percent aluminum packs, aluminum weight gains were related to the halide pack activator. Solid-state nickel diffusion controlled coating formation from sodium fluoride and chloride and ammonium fluoride activated packs. In other ammonium and sodium halide activated 1 weight percent aluminum packs, gaseous diffusion controlled coating formation.

Neutral gas rotation in magnetron discharge

NASA Astrophysics Data System (ADS)

Pal, A. F.; Ryabinkin, A. N.; Serov, A. O.; Filippov, A. V.

2014-12-01

We have experimentally established the existence and determined the velocity of motion of the neutral component of plasma in a planar magnetron discharge, which takes place in the direction of drift of the charged plasma component in crossed electric and magnetic ( E × B) fields. For this purpose, we have studied the propagation of a small gaseous additive over the plasma ring of dc magnetron discharge in the diffusion regime. The obtained temporal dependences of the intensity of atomic emission spectra of the additive in various regions of the plasma ring are compared to the results of numerical solution of the diffusion equation for the experimental conditions studied.

Numerical models for the diffuse ionized gas in galaxies. I. Synthetic spectra of thermally excited gas with turbulent magnetic reconnection as energy source

NASA Astrophysics Data System (ADS)

Hoffmann, T. L.; Lieb, S.; Pauldrach, A. W. A.; Lesch, H.; Hultzsch, P. J. N.; Birk, G. T.

2012-08-01

Aims: The aim of this work is to verify whether turbulent magnetic reconnection can provide the additional energy input required to explain the up to now only poorly understood ionization mechanism of the diffuse ionized gas (DIG) in galaxies and its observed emission line spectra. Methods: We use a detailed non-LTE radiative transfer code that does not make use of the usual restrictive gaseous nebula approximations to compute synthetic spectra for gas at low densities. Excitation of the gas is via an additional heating term in the energy balance as well as by photoionization. Numerical values for this heating term are derived from three-dimensional resistive magnetohydrodynamic two-fluid plasma-neutral-gas simulations to compute energy dissipation rates for the DIG under typical conditions. Results: Our simulations show that magnetic reconnection can liberate enough energy to by itself fully or partially ionize the gas. However, synthetic spectra from purely thermally excited gas are incompatible with the observed spectra; a photoionization source must additionally be present to establish the correct (observed) ionization balance in the gas.

Theoretical and Numerical Investigation of Radiative Extinction of Diffusion Flames

NASA Technical Reports Server (NTRS)

Ray, Anjan

1996-01-01

The influence of soot radiation on diffusion flames was investigated using both analytical and numerical techniques. Soot generated in diffusion flames dominate the flame radiation over gaseous combustion products and can significantly lower the temperature of the flame. In low gravity situations there can be significant accumulation of soot and combustion products in the vicinity of the primary reaction zone owing to the absence of any convective buoyant flow. Such situations may result in substantial suppression of chemical activities in a flame, and the possibility of a radiative extinction may also be anticipated. The purpose of this work was to not only investigate the possibility of radiative extinction of a diffusion flame but also to qualitatively and quantitatively analyze the influence of soot radiation on a diffusion flame. In this study, first a hypothetical radiative loss profile of the form of a sech(sup 2) was assumed to influence a pure diffusion flame. It was observed that the reaction zone can, under certain circumstances, move through the radiative loss zone and locate itself on the fuel side of the loss zone contrary to our initial postulate. On increasing the intensity and/or width of the loss zone it was possible to extinguish the flame, and extinction plots were generated. In the presence of a convective flow, however, the movement of the temperature and reaction rate peaks indicated that the flame behavior is more complicated compared to a pure diffusional flame. A comprehensive model of soot formation, oxidation and radiation was used in a more involved analysis. The soot model of Syed, Stewart and Moss was used for soot nucleation and growth and the model of Nagle and Strickland-Constable was used for soot oxidation. The soot radiation was considered in the optically thin limit. An analysis of the flame structure revealed that the radiative loss term is countered both by the reaction term and the diffusion term. The essential balance for the soot volume fraction was found to be between the processes of soot convection and soot growth. Such a balance yielded to analytical treatment and the soot volume fraction could be expressed in the form of an integral. The integral was evaluated using two approximate methods and the results agreed very well with the numerical solutions for all cases examined.

Development of a high efficiency thin silicon solar cell

NASA Technical Reports Server (NTRS)

Lindmayer, J.; Wrigley, C. Y.

1977-01-01

A key to the success of this program was the breakthrough development of a technology for producing ultra-thin silicon slices which are very flexible, resilient, and tolerant of moderate handling abuse. Experimental topics investigated were thinning technology, gaseous junction diffusion, aluminum back alloying, internal reflectance, tantalum oxide anti-reflective coating optimization, slice flexibility, handling techniques, production rate limiting steps, low temperature behavior, and radiation tolerance.

Accelerating activity coefficient calculations using multicore platforms, and profiling the energy use resulting from such calculations.

NASA Astrophysics Data System (ADS)

Topping, David; Alibay, Irfan; Bane, Michael

2017-04-01

To predict the evolving concentration, chemical composition and ability of aerosol particles to act as cloud droplets, we rely on numerical modeling. Mechanistic models attempt to account for the movement of compounds between the gaseous and condensed phases at a molecular level. This 'bottom up' approach is designed to increase our fundamental understanding. However, such models rely on predicting the properties of molecules and subsequent mixtures. For partitioning between the gaseous and condensed phases this includes: saturation vapour pressures; Henrys law coefficients; activity coefficients; diffusion coefficients and reaction rates. Current gas phase chemical mechanisms predict the existence of potentially millions of individual species. Within a dynamic ensemble model, this can often be used as justification for neglecting computationally expensive process descriptions. Indeed, on whether we can quantify the true sensitivity to uncertainties in molecular properties, even at the single aerosol particle level it has been impossible to embed fully coupled representations of process level knowledge with all possible compounds, typically relying on heavily parameterised descriptions. Relying on emerging numerical frameworks, and designed for the changing landscape of high-performance computing (HPC), in this study we focus specifically on the ability to capture activity coefficients in liquid solutions using the UNIFAC method. Activity coefficients are often neglected with the largely untested hypothesis that they are simply too computationally expensive to include in dynamic frameworks. We present results demonstrating increased computational efficiency for a range of typical scenarios, including a profiling of the energy use resulting from reliance on such computations. As the landscape of HPC changes, the latter aspect is important to consider in future applications.

Atmospheric partitioning and the air-water exchange of polycyclic aromatic hydrocarbons in a large shallow Chinese lake (Lake Chaohu).

PubMed

Qin, Ning; He, Wei; Kong, Xiang-Zhen; Liu, Wen-Xiu; He, Qi-Shuang; Yang, Bin; Ouyang, Hui-Ling; Wang, Qing-Mei; Xu, Fu-Liu

2013-11-01

The residual levels of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere and in dissolved phase from Lake Chaohu were measured by (GC-MS). The composition and seasonal variation were investigated. The diffusive air-water exchange flux was estimated by a two-film model, and the uncertainty in the flux calculations and the sensitivity of the parameters were evaluated. The following results were obtained: (1) the average residual levels of all PAHs (PAH16) in the atmosphere from Lake Chaohu were 60.85±46.17 ng m(-3) in the gaseous phase and 14.32±23.82 ng m(-3) in the particulate phase. The dissolved PAH16 level was 173.46±132.89 ng L(-1). (2) The seasonal variation of average PAH16 contents ranged from 43.09±33.20 ng m(-3) (summer) to 137.47±41.69 ng m(-3) (winter) in gaseous phase, from 6.62±2.72 ng m(-3) (summer) to 56.13±22.99 ng m(-3) (winter) in particulate phase, and 142.68±74.68 ng L(-1) (winter) to 360.00±176.60 ng L(-1) (summer) in water samples. Obvious seasonal trends of PAH16 concentrations were found in the atmosphere and water. The values of PAH16 for both the atmosphere and the water were significantly correlated with temperature. (3) The monthly diffusive air-water exchange flux of total PAH16 ranged from -1.77×10(4) ng m(-2) d(-1) to 1.11×10(5) ng m(-2) d(-1), with an average value of 3.45×10(4) ng m(-2) d(-1). (4) The results of a Monte Carlo simulation showed that the monthly average PAH fluxes ranged from -3.4×10(3) ng m(-2) d(-1) to 1.6×10(4) ng m(-2) d(-1) throughout the year, and the uncertainties for individual PAHs were compared. (5) According to the sensitivity analysis, the concentrations of dissolved and gaseous phase PAHs were the two most important factors affecting the results of the flux calculations. Copyright © 2013 Elsevier Ltd. All rights reserved.

Uptake of gaseous formaldehyde by soil surfaces: a combination of adsorption/desorption equilibrium and chemical reactions

NASA Astrophysics Data System (ADS)

Li, Guo; Su, Hang; Li, Xin; Kuhn, Uwe; Meusel, Hannah; Hoffmann, Thorsten; Ammann, Markus; Pöschl, Ulrich; Shao, Min; Cheng, Yafang

2016-08-01

Gaseous formaldehyde (HCHO) is an important precursor of OH radicals and a key intermediate molecule in the oxidation of atmospheric volatile organic compounds (VOCs). Budget analyses reveal large discrepancies between modeled and observed HCHO concentrations in the atmosphere. Here, we investigate the interactions of gaseous HCHO with soil surfaces through coated-wall flow tube experiments applying atmospherically relevant HCHO concentrations of ˜ 10 to 40 ppbv. For the determination of uptake coefficients (γ), we provide a Matlab code to account for the diffusion correction under laminar flow conditions. Under dry conditions (relative humidity = 0 %), an initial γ of (1.1 ± 0.05) × 10-4 is determined, which gradually drops to (5.5 ± 0.4) × 10-5 after 8 h experiments. Experiments under wet conditions show a smaller γ that drops faster over time until reaching a plateau. The drop of γ with increasing relative humidity as well as the drop over time can be explained by the adsorption theory in which high surface coverage leads to a reduced uptake rate. The fact that γ stabilizes at a non-zero plateau suggests the involvement of irreversible chemical reactions. Further back-flushing experiments show that two-thirds of the adsorbed HCHO can be re-emitted into the gas phase while the residual is retained by the soil. This partial reversibility confirms that HCHO uptake by soil is a complex process involving both adsorption/desorption and chemical reactions which must be considered in trace gas exchange (emission or deposition) at the atmosphere-soil interface. Our results suggest that soil and soil-derived airborne particles can either act as a source or a sink for HCHO, depending on ambient conditions and HCHO concentrations.

Impact of the volume of gaseous phase in closed reactors on ANC results and modelling

NASA Astrophysics Data System (ADS)

Drapeau, Clémentine; Delolme, Cécile; Lassabatere, Laurent; Blanc, Denise

2016-04-01

The understanding of the geochemical behavior of polluted solid materials is often challenging and requires huge expenses of time and money. Nevertheless, given the increasing amounts of polluted solid materials and related risks for the environment, it is more and more crucial to understand the leaching of majors and trace metals elements from these matrices. In the designs of methods to quantify pollutant solubilization, the combination of experimental procedures with modeling approaches has recently gained attention. Among usual methods, some rely on the association of ANC and geochemical modeling. ANC experiments - Acid Neutralization Capacity - consists in adding known quantities of acid or base to a mixture of water and contaminated solid materials at a given liquid / solid ratio in closed reactors. Reactors are agitated for 48h and then pH, conductivity, redox potential, carbon, majors and heavy metal solubilized are quantified. However, in most cases, the amounts of matrix and water do not reach the total volume of reactors, leaving some space for air (gaseous phase). Despite this fact, no clear indication is given in standard procedures about the effect of this gaseous phase. Even worse, the gaseous phase is never accounted for when exploiting or modeling ANC data. The gaseous phase may exchange CO2 with the solution, which may, in turn, impact both pH and element release. This study lies within the most general framework for the use of geochemical modeling for the prediction of ANC results for the case of pure phases to real phase assemblages. In this study, we focus on the effect of the gaseous phase on ANC experiments on different mineral phases through geochemical modeling. To do so, we use PHREEQC code to model the evolution of pH and element release (including majors and heavy metals) when several matrices are put in contact with acid or base. We model the following scenarios for the gaseous phase: no gas, contact with the atmosphere (open system) and real reactors conditions (semi-closed systems). The solid phases tested are pure phases (calcite, sulfides, etc.) and synthetic assemblages mimicking complex polluted matrices. The modeling clearly shows that the systems are sensitive to the opening to the atmosphere. If the open system and the system with no gas are entirely different, "real" reactors also differ significantly from the other systems. Apparently, the presence of the gaseous phase in reactors greatly impacts pH and element release. This parameter should be accounted for in ANC experimental procedures and modeling. In addition to this numerical study, experimental results, previously obtained for urban polluted sediments, are analyzed in lights of the findings of the numerical study. This step allows us to strengthen conclusions and to pinpoint at the necessity to account for the gaseous phase when performing and modeling ANC experiments.

Effect of silane dilution on intrinsic stress in glow discharge hydrogenated amorphous silicon films

NASA Astrophysics Data System (ADS)

Harbison, J. P.; Williams, A. J.; Lang, D. V.

1984-02-01

Measurements of the intrinsic stress in hydrogenated amorphous silicon (a-Si : H) films grown by rf glow discharge decomposition of silane diluted to varying degrees in argon are presented. Films are found to grow under exceedingly high compressive stress. Low values of macroscopic film density and low stress values are found to correlate with high growth rate. An abrupt drop in stress occurs between 2 and 3% silane at precisely the point where columnar growth morphology appears. No corresponding abrupt change is noted in density, growth rate, or plasma species concentrations as determined by optical emissioin spectroscopy. Finally a model of diffusive incorporation of hydrogen or some gaseous impurity during growth into the bulk of the film behind the growing interface is proposed to explain the results.

The Three Sources of Gas in the Comae of Comets

NASA Technical Reports Server (NTRS)

Huebner, W. F.

1995-01-01

Surface water ice on a comet nucleus is the major source of coma gas. Dust, entrained by coma gas, fragments and vaporizes, forming a second, distributed source of coma gas constituents. Ice species more volatile than water ice below the surface of the nucleus are a third source of coma gas. Vapors from these ices, produced by heat penetrating into the nucleus, diffuse through pores outward into the coma. The second and third sources provide minor, but sometimes easily detectible, gaseous species in the coma. We present mixing ratios of observed minor coma constituents relative to water vapor as a function of heliocentric and cometocentric distances and compare these ratios with model predictions, assuming the sources of the minor species are either coma dust or volatile ices in the nucleus.

Diffusion of Magnetic Field and Removal of Magnetic Flux from Clouds Via Turbulent Reconnection

NASA Astrophysics Data System (ADS)

Santos-Lima, R.; Lazarian, A.; de Gouveia Dal Pino, E. M.; Cho, J.

2010-05-01

The diffusion of astrophysical magnetic fields in conducting fluids in the presence of turbulence depends on whether magnetic fields can change their topology via reconnection in highly conducting media. Recent progress in understanding fast magnetic reconnection in the presence of turbulence reassures that the magnetic field behavior in computer simulations and turbulent astrophysical environments is similar, as far as magnetic reconnection is concerned. This makes it meaningful to perform MHD simulations of turbulent flows in order to understand the diffusion of magnetic field in astrophysical environments. Our studies of magnetic field diffusion in turbulent medium reveal interesting new phenomena. First of all, our three-dimensional MHD simulations initiated with anti-correlating magnetic field and gaseous density exhibit at later times a de-correlation of the magnetic field and density, which corresponds well to the observations of the interstellar media. While earlier studies stressed the role of either ambipolar diffusion or time-dependent turbulent fluctuations for de-correlating magnetic field and density, we get the effect of permanent de-correlation with one fluid code, i.e., without invoking ambipolar diffusion. In addition, in the presence of gravity and turbulence, our three-dimensional simulations show the decrease of the magnetic flux-to-mass ratio as the gaseous density at the center of the gravitational potential increases. We observe this effect both in the situations when we start with equilibrium distributions of gas and magnetic field and when we follow the evolution of collapsing dynamically unstable configurations. Thus, the process of turbulent magnetic field removal should be applicable both to quasi-static subcritical molecular clouds and cores and violently collapsing supercritical entities. The increase of the gravitational potential as well as the magnetization of the gas increases the segregation of the mass and magnetic flux in the saturated final state of the simulations, supporting the notion that the reconnection-enabled diffusivity relaxes the magnetic field + gas system in the gravitational field to its minimal energy state. This effect is expected to play an important role in star formation, from its initial stages of concentrating interstellar gas to the final stages of the accretion to the forming protostar. In addition, we benchmark our codes by studying the heat transfer in magnetized compressible fluids and confirm the high rates of turbulent advection of heat obtained in an earlier study.

Process for photosynthetically splitting water

DOEpatents

Greenbaum, Elias

1984-01-01

The invention is an improved process for producing gaseous hydrogen and oxygen from water. The process is conducted in a photolytic reactor which contains a water-suspension of a photoactive material containing a hydrogen-liberating catalyst. The reactor also includes a volume for receiving gaseous hydrogen and oxygen evolved from the liquid phase. To avoid oxygen-inactivation of the catalyst, the reactor is evacuated continuously by an external pump which circulates the evolved gases through means for selectively recovering hydrogen therefrom. The pump also cools the reactor by evaporating water from the liquid phase. Preferably, product recovery is effected by selectively diffusing the hydrogen through a heated semipermeable membrane, while maintaining across the membrane a magnetic field gradient which biases the oxygen away from the heated membrane. This promotes separation, minimizes the back-reaction of hydrogen and oxygen, and protects the membrane.

Diffusive interaction of multiple surface nanobubbles: shrinkage, growth, and coarsening.

PubMed

Zhu, Xiaojue; Verzicco, Roberto; Zhang, Xuehua; Lohse, Detlef

2018-03-14

Surface nanobubbles are nanoscopic spherical-cap shaped gaseous domains on immersed substrates which are stable, even for days. After the stability of a single surface nanobubble has been theoretically explained, i.e. contact line pinning and gas oversaturation are required to stabilize it against diffusive dissolution [Lohse and Zhang, Phys. Rev. E, 2015, 91, 031003(R)], here we focus on the collective diffusive interaction of multiple nanobubbles. For that purpose we develop a finite difference scheme for the diffusion equation with the appropriate boundary conditions and with the immersed boundary method used to represent the growing or shrinking bubbles. After validation of the scheme against the exact results of Epstein and Plesset for a bulk bubble [J. Chem. Phys., 1950, 18, 1505] and of Lohse and Zhang for a surface bubble, the framework of these simulations is used to describe the coarsening process of competitively growing nanobubbles. The coarsening process for such diffusively interacting nanobubbles slows down with advancing time and increasing bubble distance. The present results for surface nanobubbles are also applicable for immersed surface nanodroplets, for which better controlled experimental results of the coarsening process exist.

[Measurement of Chemical Compounds in Indoor and Outdoor Air in Chiba City Using Diffusive Sampling Devices].

PubMed

Sakamoto, Hironari; Uchiyama, Shigehisa; Kihara, Akiko; Tsutake, Toyoshige; Bekki, Kanae; Inaba, Yohei; Nakagome, Hideki; Kunugita, Naoki

2015-01-01

Indoor air quality (IAQ) is a major concern, because people on average spend the vast majority of their time indoors and they are repeatedly exposed to indoor air pollutants. In this study, to assess indoor air quality in Chiba City, gaseous chemical compounds were surveyed using four types of diffusive sampler. Gaseous chemical compounds such as carbonyls, volatile organic compounds (VOC), acid gases, basic gases, and ozone were measured in indoor and outdoor air of 50 houses throughout Chiba City in winter and summer. Four types of diffusive sampler were used in this study: DSD-BPE/DNPH packed with 2,4-dinitrophenyl hydrazine and trans-1,2-bis(2-pyridyl)ethylene-coated silica for ozone and carbonyls; VOC-SD packed with Carboxen 564 particles for volatile organic compounds; DSD-TEA packed with triethanolamine-impregnated silica for acid gases; and DSD-NH3 packed with phosphoric acid-impregnated silica for basic gases. Almost all compounds in indoor air were detected at higher concentrations in summer than in winter. However, the nitrogen dioxide concentration in indoor air particularly increased only in winter, which well correlated with the formic acid concentration (correlation coefficient=0.974). The compound with the highest concentrations in indoor air was p-dichlorobenzene, with recorded levels of 13,000 μg m(-3) in summer and 1,100 μg m(-3) in winter in indoor air. p-Dichlorobenzene in summer and nitrogen dioxide in winter are detected at markedly high concentrations. Pollution control and continuous monitoring of IAQ are indispensable for human health.

Amoeba behavior of UO/sub 2/ coated particle fuel

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

Wagner-Loeffler, M.

1977-09-01

The data extracted from numerous irradiation tests were used to derive amoeba endurance parameters for UO/sub 2/. The data do not yet allow an unambiguous definition of the controlling mechanism, which may be due to either gaseous or solid-state diffusion processes. Adequate data on the amoeba effect are available for design of a steam-raising high-temperature gas-cooled reactor using UO/sub 2/ fuel.

Method of producing encapsulated thermonuclear fuel particles

DOEpatents

Smith, Warren H.; Taylor, William L.; Turner, Harold L.

1976-01-01

A method of producing a fuel particle is disclosed, which comprises forming hollow spheroids which have a mass number greater than 50, immersing said spheroids while under the presence of pressure and heat in a gaseous atmosphere containing an isotope, such as deuterium and tritium, so as to diffuse the gas into the spheroid and thereafter cooling said spheroids up to about 77.degree. Kelvin to about 4.degree. Kelvin.

Coupled isotopic and simulation modeling of gaseous nitrogen losses from tropical rainforests

NASA Astrophysics Data System (ADS)

Bai, E.; Houlton, B.

2008-12-01

Gaseous nitrogen (N) losses remove fixed N from the biosphere and play an important role in regulating Earth's climate system. Current techniques for directly measuring gaseous N fluxes are still limited, however, and many uncertainties remain. We combined natural isotopic and simulation modeling (DAYCENT; daily version of CENTURY) to examine the extent to which N isotopes offer meaningful constraint to estimates of large-scale gaseous N emissions from terrestrial ecosystems. The isotope model considers two scenarios: in the first, soil δ15N is a linear function of fraction of gaseous N losses; in the second, underexpression of the isotope effect of denitrification is considered and soil 15N/14N is determined by both the fraction of gaseous losses and the proportion of nitrate consumed locally by denitrification. We examined the coupled simulation and isotope-based model along two Hawaiian rainforest gradients which span a range of tropical rainfall climates, soil biogeochemical ages and ecosystem 15N/14N. Under most conditions (MAP < 4050 mm and age > 2100 yr), modeled soil 15N/14N ratios agreed reasonably well with measurements (r2 = 0.53), consistent with full expression of a field-calibrated isotope effect (scenario 1). In very wet sites (MAP > 4050 mm), locally complete consumption of nitrate appears to lower the effective isotope effect of denitrification at ecosystem levels, resulting in soil 15N/14N ratios that approach those of the N inputs (i.e., scenario 2). Replacing DAYCENT simulation results with field-based measures of N gas fluxes (NOx + N2O) yielded consistently lower estimates of soil 15N/14N ratios across the forests, pointing to a missing gas N loss term (i.e., N2), inadequate coverage of spatial and temporal heterogeneity by empirical measures or both. These results demonstrate the potential for soil N isotopes to constrain N gas fluxes at large geographic scales, implying a quantitative tracer for gaseous N losses from terrestrial ecosystems.

Prediction of external corrosion for steel cylinders at the Paducah Gaseous Diffusion Plant: Application of an empirical method

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

Lyon, B.F.

1996-02-01

During the summer of 1995, ultrasonic wall thickness data were collected for 100 steel cylinders containing depleted uranium (DU) hexafluoride located at Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky. The cylinders were selected for measurement to assess the condition of the more vulnerable portion of the cylinder inventory at PGDP. The purpose of this report is to apply the method used in Lyon to estimate the effects of corrosion for larger unsampled populations as a function of time. The scope of this report is limited and is not intended to represent the final analyses of available data. Future effortsmore » will include continuing analyses of available data to investigate defensible deviations from the conservative assumptions made to date. For each cylinder population considered, two basic types of analyses were conducted: (1) estimates were made of the number of cylinders as a function of time that will have a minimum wall thickness of either 0 mils (1 mil = 0.00 1 in.) or 250 mils and (2) the current minimum wall thickness distributions across cylinders were estimated for each cylinder population considered. Additional analyses were also performed investigating comparisons of the results for F and G yards with the results presented in Lyon (1995).« less

Environmental Survey preliminary report, Oak Ridge Gaseous Diffusion Plant, Oak Ridge, Tennessee

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

Not Available

1989-02-01

This report presents the preliminary findings from the first phase of the Environmental Survey of the US Department of Energy's (DOE) Oak Ridge Gaseous Diffusion Plant (ORGDP) conducted March 14 through 25, 1988. The Survey is being conducted by an interdisciplinary team of environmental specialists, led and managed by the Office of Environment, Safety and Health's Office of Environmental Audit. Individual team components are being supplied by a private contractor. The objective of the Survey is to identify environmental risk associated with ORGDP. The Survey covers all environmental media and all areas of environmental regulation. It is being performed inmore » accordance with the DOE Environmental Survey Manual. This phase of the Survey involves the review of existing site environmental data, observations of the operations carried on at ORGDP, and interviews with site personnel. The Survey team developed a Sampling and Analysis Plan to assist in further assessing certain of the environmental problems identified during is on-site activities. The Sampling and Analysis Plan will be executed by Idaho National Engineering Laboratory (INEL). When completed, the results will be incorporated into the ORGDP Survey findings for in inclusion into the Environmental Survey Summary Report. 120 refs., 41 figs., 74 tabs.« less

Composition and method for polymer moderated catalytic water formation

DOEpatents

Shepodd, Timothy Jon

1999-01-01

A composition suitable for safely removing hydrogen from gaseous mixtures containing hydrogen and oxygen, particularly those mixtures wherein the hydrogen concentration is within the explosive range. The composition comprises a hydrogenation catalyst, preferably Pd dispersed on carbon, wherein the concentration of Pd is from about 1-10 wt %, dispersed in a polymeric material matrix. As well as serving as a matrix to contain the hydrogenation catalyst, the polymeric material, which is substantially unreactive to hydrogen, provides both a diffusion restriction to hydrogen and oxygen, thereby limiting the rate at which the reactants (hydrogen and oxygen) can diffuse to the catalyst surface and thus, the production of heat from the recombination reaction and as a heat sink.

Experimental determination of turbulence in a GH2-GOX rocket combustion chamber

NASA Technical Reports Server (NTRS)

Tou, P.; Russell, R.; Ohara, J.

1974-01-01

The intensity of turbulence and the Lagrangian correlation coefficient for a gaseous rocket combustion chamber have been determined from the experimental measurements of the tracer gas diffusion. A combination of Taylor's turbulent diffusion theory and Spalding's numerical method for solving the conservation equations of fluid mechanics was used to calculate these quantities. Taylor's theory was extended to consider the inhomogeneity of the turbulence field in the axial direction of the combustion chamber. An exponential function was used to represent the Lagrangian correlation coefficient. The results indicate that the maximum value of the intensity of turbulence is about 15% and the Lagrangian correlation coefficient drops to about 0.12 in one inch of the chamber length.

Comparative Investigation on the Heat Transfer Characteristics of Gaseous CO2 and Gaseous Water Flowing Through a Single Granite Fracture

NASA Astrophysics Data System (ADS)

He, Yuanyuan; Bai, Bing; Li, Xiaochun

2017-11-01

CO2 and water are two commonly employed heat transmission fluids in several fields. Their temperature and pressure determine their phase states, thus affecting the heat transfer performance of the water/CO2. The heat transfer characteristics of gaseous CO2 and gaseous water flowing through fractured hot dry rock still need a great deal of investigation, in order to understand and evaluate the heat extraction in enhanced geothermal systems. In this work, we develop a 2D numerical model to compare the heat transfer performance of gaseous CO2 and gaseous water flowing through a single fracture aperture of 0.2 mm in a φ 50 × 50 mm cylindrical granite sample with a confining temperature of 200°C under different inlet mass flow rates. Our results indicate that: (1) the final outlet temperatures of the fluid are very close to the outer surface temperature under low inlet mass flow rate, regardless of the sample length. (2) Both the temperature of the fluid (gaseous CO2/gaseous water) and inner surface temperature rise sharply at the inlet, and the inner surface temperature is always higher than the fluid temperature. However, their temperature difference becomes increasingly small. (3) Both the overall heat transfer coefficient (OHTC) and local heat transfer coefficient (LHTC) of gaseous CO2 and gaseous water increase with increasing inlet mass flow rates. (4) Both the OHTC and LHTC of gaseous CO2 are lower than those of gaseous water under the same conditions; therefore, the heat mining performance of gaseous water is superior to gaseous CO2 under high temperature and low pressure.

Understanding the variation in the millimeter-wave emission of Venus

NASA Technical Reports Server (NTRS)

Fahd, Antoine K.; Steffes, Paul G.

1992-01-01

Recent observations of the millimeter-wave emission from Venus at 112 GHz (2.6 mm) have shown significant variations in the continuum flux emission that may be attributed to the variability in the abundances of absorbing constituents in the Venus atmosphere. Such constituents include gaseous H2SO4, SO2, and liquid sulfuric acid (cloud condensates). Recently, Fahd and Steffes have shown that the effects of liquid H, SO4, and gaseous SO2 cannot completely account for this measured variability in the millimeter-wave emission of Venus. Thus, it is necessary to study the effect of gaseous H2SO4 on the millimeter-wave emission of Venus. This requires knowledge of the millimeter-wavelength (MMW) opacity of gaseous H2SO4, which unfortunately has never been determined for Venus-like conditions. We have measured the opacity of gaseous H2SO4 in a CO2 atmosphere at 550, 570, and 590 K, at 1 and 2 atm total pressure, and at a frequency of 94.1 GHz. Our results, in addition to previous centimeter-wavelength results are used to verify a modeling formalism for calculating the expected opacity of this gaseous mixture at other frequencies. This formalism is incorporated into a radiative transfer model to study the effect of gaseous H2SO4 on the MMW emission of Venus.

Effect of Non-laminar Regime on the Efficiency of a Thermal Diffusion Column. Report No. 26; INFLUENCIA DEL REGIMEN NO LAMINAR SOBRE LA EFICIENCIA DE UNA COLUMNA DE DIFUSION TERMICA. Informe No. 26

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

Espanol, C.E.

1960-01-01

The effect of the appearance of localized perturbations on the separation factor and operation time of a thermal diffusion column is studied. The separation factor of a column was obtained experimentally and the enrichment was recorded continuously as a function of time by measurement of the thermal conductivity of the gaseous mixture at the foot and head of the column. A mixture of Ar and CO/sub 2/ was used as it behaves as an isotopic mixture. The results showed the linear decrease of the separation factor with the number of stages and the operation time practically does not vary. Themore » introduction of localized turbulences in a thermal diffusion column reduces the column yield. (J.S.R.)« less

One-Dimensional Modeling Studies of the Gaseous Electronics Conference RF Reference Cell

PubMed Central

Govindan, T. R.; Meyyappan, M.

1995-01-01

A review of the one-dimensional modeling studies in the literature of the Gaseous Electronics Conference (GEC) reference plasma reactor is presented. Most of the studies are based on the fluid model description of the discharge and some utilize hybrid fluid-kinetic schemes. Both models are discussed here briefly. The models provide a basic understanding of the discharge mechanisms and reproduce several critical discharge features observed experimentally. PMID:29151755

Determination of gaseous fission product behavior near the cerium dioxide Σ 3 (111)/[1 1 ¯ 0] tilt grain boundary via first-principles study

DOE PAGES

Xi, Jianqi; Liu, Bin; Xu, Haixuan; ...

2017-12-02

We presenmore » t that grain boundaries (GBs) are the most abundant structural defects in nanostructured nuclear fuels and play an important role in determining fission product behavior, which further affects the performance of nuclear fuels. In this work, cerium dioxide (CeO 2) is used as a surrogate material for mixed oxide fuels to understand gaseous fission product behavior, specifically Xe. First-principles calculations are employed to comprehensively study the behavior of Xe and trap sites for Xe near the Σ 3 (111)/[1 1 ¯ 0] grain boundary in CeO 2, which will provide guidance on overall trends for Xe stability and diffusion at grain boundaries vs in the bulk. Significant segregation behavior of trap sites, regardless of charge states, is observed near the GB. This is mainly ascribed to the local atomic structure near the GB, which results in weaker bond strength and more negative segregation energies. For Xe, however, the segregation profile near the GB is different. Our calculations show that, as the size of trap sites increases, the segregation propensity of Xe is reduced. In addition, under hyper-stoichiometric conditions, the solubility of Xe trapped at the GB is significantly higher than that in the bulk, suggesting higher Xe concentration than that in the bulk. The results of this work demonstrate that the diffusion mechanism of Xe in CeO 2 is comparable to that in UO 2. The diffusion activation energies of Xe atoms in the Σ3GB are lower than that in the bulk CeO 2. Lastly, these results suggest that the diffusivity of Xe atoms is higher along the GB than that in the bulk, which enhances the aggregation of Xe atoms near the GB.« less

Determination of gaseous fission product behavior near the cerium dioxide Σ 3 (111)/[1 1 ¯ 0] tilt grain boundary via first-principles study

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

Xi, Jianqi; Liu, Bin; Xu, Haixuan

We presenmore » t that grain boundaries (GBs) are the most abundant structural defects in nanostructured nuclear fuels and play an important role in determining fission product behavior, which further affects the performance of nuclear fuels. In this work, cerium dioxide (CeO 2) is used as a surrogate material for mixed oxide fuels to understand gaseous fission product behavior, specifically Xe. First-principles calculations are employed to comprehensively study the behavior of Xe and trap sites for Xe near the Σ 3 (111)/[1 1 ¯ 0] grain boundary in CeO 2, which will provide guidance on overall trends for Xe stability and diffusion at grain boundaries vs in the bulk. Significant segregation behavior of trap sites, regardless of charge states, is observed near the GB. This is mainly ascribed to the local atomic structure near the GB, which results in weaker bond strength and more negative segregation energies. For Xe, however, the segregation profile near the GB is different. Our calculations show that, as the size of trap sites increases, the segregation propensity of Xe is reduced. In addition, under hyper-stoichiometric conditions, the solubility of Xe trapped at the GB is significantly higher than that in the bulk, suggesting higher Xe concentration than that in the bulk. The results of this work demonstrate that the diffusion mechanism of Xe in CeO 2 is comparable to that in UO 2. The diffusion activation energies of Xe atoms in the Σ3GB are lower than that in the bulk CeO 2. Lastly, these results suggest that the diffusivity of Xe atoms is higher along the GB than that in the bulk, which enhances the aggregation of Xe atoms near the GB.« less

Examining Changes in Radioxenon Isotope Activity Ratios during Subsurface Transport

NASA Astrophysics Data System (ADS)

Annewandter, R.

2013-12-01

The Non-Proliferation Experiment (NPE) has demonstrated and modelled the usefulness of barometric pumping induced soil gas sampling during On-Site inspections. Gas transport has been widely studied with different numerical codes. However, gas transport of all radioxenons in the post-detonation regime and their possible fractionation is still neglected in the open literature. Atmospheric concentrations of the radioxenons Xe-135, Xe-133m, Xe-133 and Xe-131m can be used to discriminate between civilian releases (nuclear power plants or medical isotope facilities), and nuclear explosion sources. It is based on the isotopic activity ratio method. Yet it is not clear whether subsurface migration of the radioxenons, with eventual release into the atmosphere, can affect the activity ratios due to fractionation. Fractionation can be caused by different diffusivities due to mass differences between the radioxenons. A previous study showed surface arrival time of a chemically inert gaseous tracer is affected by its diffusivity. They observed detectable amount for SF6 50 days after detonation and 375 days for He-3. They predict 50 and 80 days for Xe-133 and Ar-37 respectively. Cyclical changes in atmospheric pressure can drive subsurface gas transport. This barometric pumping phenomenon causes an oscillatoric flow in upward trending fractures which, combined with diffusion into the porous matrix, leads to a net transport of gaseous components - a ratcheting effect. We use a general purpose reservoir simulator (Complex System Modelling Platform, CSMP++) which has been applied in a range of fields such as deep geothermal systems, three-phase black oil simulations , fracture propagation in fractured, porous media, Navier-Stokes pore-scale modelling among others. It is specifically designed to account for structurally complex geologic situation of fractured, porous media. Parabolic differential equations are solved by a continuous Galerkin finite-element method, hyperbolic differential equations by a complementary finite volume method. The parabolic and hyperbolic problem can be solved separately using the operator-splitting method (Implicit Pressure Explicit Saturation, IMPES). The resulting system of linear equations is solved by the algebraic multigrid library SAMG, developed at the Fraunhofer Institute for Algorithms and Scientific Computing. CSMP++ is developed at Montan University of Leoben, ETH Zuerich, Imperial College London and Heriot-Watt University in Edinburgh. To date, there has been no research investigating how subsurface transport impacts isotope activity ratios. The isotopic activity ratio method can be used to discriminate between civil release or nuclear explosion sources. This study examines possible fractionation of Xe-135, Xe-133m, Xe-133, Xe-131m during barometric pumping-driven subsurface migration, which can affect surface arrival times and isotopic activity ratios. Surface arrival times for the Noble gases Kr-81, Kr-85 and Ar-39 are also calculated.

Experiments versus modeling of buoyant drying of porous media

NASA Astrophysics Data System (ADS)

Salin, D.; Yiotis, A.; Tajer, E.; Yortsos, Y. C.

2012-12-01

Experiments versus modeling of buoyant drying of porous media D. Salin and A.G. Yiotis, Laboratoire FAST, Univ Pierre & Marie Curie, Univ. Paris-Sud, CNRS, Orsay 91405, France and E.S. Tajer and Y.C. Yortsos, Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1450 A series of isothermal drying experiments in packed glass beads saturated with volatile hydrocarbons (hexane or pentane) are conducted. The transparent glass cells containing the packing allow for the visual monitoring of the phase distribution patterns below the surface, including the formation of liquid films, as the gaseous phase invades the pore space, and for the control of the thickness of the diffusive mass boundary layer over the packing. We demonstrate the existence of an early Constant Rate Period, CRP, that lasts as long as the films saturate the surface of the packing, and of a subsequent Falling Rate Period, FRP, that begins practically after the detachment of the film tips from the external surface. During the CRP, the process is controlled by diffusion within the stagnant gaseous phase in the upper part of the cells, yielding a Stefan tube problem solution. During the FRP, the process is controlled by diffusion within the packing, with a drying rate inversely proportional to the observed position of the film tips in the cell. The critical residual liquid saturation that marks the transition between these two regimes is found to be a function of the average bead size in our packs and the incline of the cells with respect to the flat vertical, with larger beads and angles closer to the vertical position leading to earlier film detachment times and higher critical saturations. We developed a model for the drying of porous media in the presence of gravity. It incorporated effects of corner film flow, internal and external mass transfer and the effect of gravity. Analytical results were derived when gravity opposes drying and hence leads to a stable percolation drying front. We are thus able to obtain results for the drying rates, the critical saturation and the extent of the film region with respect to the various dimensionless numbers that describe the process; the Bond (Bo)number, a film-based Capillary (Ca) number and the dimensionless extent of the mass boundary layer (Sh). The experimental results agree very well with the theory, provided that the latter is generalized to account for the effects of corner roundness in the film region which were neglected in our analytical approach. The agreement is achieved for a specific value of the roundness of the films, which is found to be constant and equal to 0.2 for various conditions, and verify the theoretical dependence on Ca, Bo and Sh numbers.

Reduced chemical kinetic model of detonation combustion of one- and multi-fuel gaseous mixtures with air

NASA Astrophysics Data System (ADS)

Fomin, P. A.

2018-03-01

Two-step approximate models of chemical kinetics of detonation combustion of (i) one hydrocarbon fuel CnHm (for example, methane, propane, cyclohexane etc.) and (ii) multi-fuel gaseous mixtures (∑aiCniHmi) (for example, mixture of methane and propane, synthesis gas, benzene and kerosene) are presented for the first time. The models can be used for any stoichiometry, including fuel/fuels-rich mixtures, when reaction products contain molecules of carbon. Owing to the simplicity and high accuracy, the models can be used in multi-dimensional numerical calculations of detonation waves in corresponding gaseous mixtures. The models are in consistent with the second law of thermodynamics and Le Chatelier's principle. Constants of the models have a clear physical meaning. The models can be used for calculation thermodynamic parameters of the mixture in a state of chemical equilibrium.

Apparatus and process to eliminate diffusional limitations in a membrane biological reactor by pressure cycling

DOEpatents

Efthymiou, George S.; Shuler, Michael L.

1989-08-29

An improved multilayer continuous biological membrane reactor and a process to eliminate diffusional limitations in membrane reactors in achieved by causing a convective flux of nutrient to move into and out of an immobilized biocatalyst cell layer. In a pressure cycled mode, by increasing and decreasing the pressure in the respective layers, the differential pressure between the gaseous layer and the nutrient layer is alternately changed from positive to negative. The intermittent change in pressure differential accelerates the transfer of nutrient from the nutrient layers to the biocatalyst cell layer, the transfer of product from the cell layer to the nutrient layer and the transfer of byproduct gas from the cell layer to the gaseous layer. Such intermittent cycling substantially eliminates mass transfer gradients in diffusion inhibited systems and greatly increases product yield and throughput in both inhibited and noninhibited systems.

Ceramic with preferential oxygen reactive layer

NASA Technical Reports Server (NTRS)

Wang, Hongyu (Inventor); Luthra, Krishan Lal (Inventor)

2001-01-01

An article comprises a silicon-containing substrate and an external environmental/thermal barrier coating. The external environmental/thermal barrier coating is permeable to diffusion of an environmental oxidant and the silicon-containing substrate is oxidizable by reaction with oxidant to form at least one gaseous product. The article comprises an intermediate layer/coating between the silicon-containing substrate and the environmental/thermal barrier coating that is oxidizable to a nongaseous product by reaction with the oxidant in preference to reaction of the silicon-containing substrate with the oxidant. A method of forming an article, comprises forming a silicon-based substrate that is oxidizable by reaction with oxidant to at least one gaseous product and applying an intermediate layer/coating onto the substrate, wherein the intermediate layer/coating is oxidizable to a nongaseous product by reaction with the oxidant in preference to reaction of the silicon-containing substrate with the oxidant.

Method for detecting organic contaminants in water supplies

DOEpatents

Dooley, K.J.; Barrie, S.L.; Buttner, W.J.

1999-08-24

A system is described for detecting organic contaminants in water supplies. A sampling unit is employed which includes a housing having at least one opening therein and a tubular member positioned within the housing having a central passageway surrounded by a side wall. The side wall is made of a composition designed to absorb the contaminants. In use, the sampling unit is immersed in a water supply. The water supply contacts the tubular member through the opening in the housing, with any contaminants being absorbed into the side wall of the tubular member. A carrier gas is then passed through the central passageway of the tubular member. The contaminants will diffuse out of the side wall and into the central passageway where they will subsequently combine with the carrier gas, thereby yielding a gaseous product. The gaseous product is then analyzed to determine the amount and type of contaminants therein. 5 figs.

Method for detecting organic contaminants in water supplies

DOEpatents

Dooley, Kirk J.; Barrie, Scott L.; Buttner, William J.

1999-01-01

A system for detecting organic contaminants in water supplies. A sampling unit is employed which includes a housing having at least one opening therein and a tubular member positioned within the housing having a central passageway surrounded by a side wall. The side wall is made of a composition designed to absorb the contaminants. In use, the sampling unit is immersed in a water supply. The water supply contacts the tubular member through the opening in the housing, with any contaminants being absorbed into the side wall of the tubular member. A carrier gas is then passed through the central passageway of the tubular member. The contaminants will diffuse out of the side wall and into the central passageway where they will subsequently combine with the carrier gas, thereby yielding a gaseous product. The gaseous product is then analyzed to determine the amount and type of contaminants therein.

1 Reevaluation of the integrated horizontal flux approach

NASA Astrophysics Data System (ADS)

Neftel, Albrecht; Häni, Christoph; Hensen, Arjan

2017-04-01

The integrated horizontal flux (IHF) method is a simplified mass balance approach frequently used to determine emissions from confined source areas, e.g. NH3 emissions from slurry spread to a circular plot (Denmead, 2008). With a mast in the center of the circle with radius R, the total flux F of the upwind emitted NH3 is approximated from the measured vertical (z) profiles of concentration (c) and horizontal wind speed (u) as (Denmead 1983): F = 1/R\\intz=zplz=0\\overline{u(c - cbgd)}dz where cbgd is the ``background'' concentration upwind of the emitting area and zpl is the maximum height of the emission plume (where the concentration c equals cbgd).The IHF method is a robust approach, as it is independent of surface characteristics and the state of atmospheric diffusion (Denmead, 2008; Laubach,2010). Ryden and McNeill (1984) published guidelines on how to evaluate IHF measurements, which have been used in many investigations that followed. In the following we analyze systematic biases that might occur by applying different recipes to both modelled concentration profiles as well as measured profiles from a recent field experiment in the Netherlands. Typical differencs using the approach by Ryden et al. (1984) are in the order +10% to +30% compared to the reference values from the model or alternative determination of the emissions based on the experimental values. The positive biases consist of several contributions: horizontal diffusion, logarithmic fit of the concentration profile, displacement height. References Denmead, O. T., 1983. Micrometeorological methods for measuring gaseous losses of nitrogen in the field. In: Gaseous Loss of Nitrogen from Plum-Soil Systems (Freney, J. R.; Simpson, J. R., Eds) Martinus Nijhof/Dr W. Junk, The Hague, pp. 133-157. Denmead, O. T., 2008. Approaches to measuring fluxes of methane and nitrous oxide between landscapes and the atmosphere. Plant Soil 309 (1-2), 5a\\euro 24.Laubach, J., 2010. Testing of a lagrangian model of dispersion in the surface layer with cattle methane emissions. Agr. Forest Meteorol. 150 (11), 1428a \\euro 1442.Ryden, J., McNeill, J., 1984. Application of the Micrometeorological Mass Balance Method to the Determination of Ammonia Loss from a Grazed Sward. J. Sci. Food Agricult. 35 (12), 1297a\\euro 1310.

Modeling of carbon and nitrogen gaseous emissions from cattle manure compost windrows

USDA-ARS?s Scientific Manuscript database

Windrow composting of cattle manure is a significant source of gaseous emissions, which include ammonia (NH3) and the greenhouse gases (GHGs) of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). A manure compost model was developed to simulate carbon (C) and nitrogen (N) processes includ...

Multiple Paths of Deuterium Fractionation in Protoplanetary Disks

NASA Astrophysics Data System (ADS)

Aikawa, Yuri; Furuya, Kenji; Hincelin, Ugo; Herbst, Eric

2018-03-01

We investigate deuterium chemistry coupled with the nuclear spin-state chemistry of H2 and {{{H}}}3+ in protoplanetary disks. Multiple paths of deuterium fractionation are found; exchange reactions with D atoms, such as HCO+ + D, are effective in addition to those with HD. In a disk model with grain sizes appropriate for dark clouds, the freeze-out of molecules is severe in the outer midplane, while the disk surface is shielded from UV radiation. Gaseous molecules, including DCO+, thus become abundant at the disk surface, which tends to make their column density distribution relatively flat. If the dust grains have grown to millimeter size, the freeze-out rate of neutral species is reduced and the abundances of gaseous molecules, including DCO+ and N2D+, are enhanced in the cold midplane. Turbulent diffusion transports D atoms and radicals at the disk surface to the midplane, and stable ice species in the midplane to the disk surface. The effects of turbulence on chemistry are thus multifold; while DCO+ and N2D+ abundances increase or decrease depending on the regions, HCN and DCN in the gas and ice are greatly reduced at the innermost radii, compared to the model without turbulence. When cosmic rays penetrate the disk, the ortho-to-para ratio (OPR) of H2 is found to be thermal in the disk, except in the cold (≲10 K) midplane. We also analyze the OPR of {{{H}}}3+ and H2D+, as well as the main reactions of H2D+, DCO+, and N2D+, in order to analytically derive their abundances in the cold midplane.

Sensitivity Analysis of Fatigue Crack Growth Model for API Steels in Gaseous Hydrogen.

PubMed

Amaro, Robert L; Rustagi, Neha; Drexler, Elizabeth S; Slifka, Andrew J

2014-01-01

A model to predict fatigue crack growth of API pipeline steels in high pressure gaseous hydrogen has been developed and is presented elsewhere. The model currently has several parameters that must be calibrated for each pipeline steel of interest. This work provides a sensitivity analysis of the model parameters in order to provide (a) insight to the underlying mathematical and mechanistic aspects of the model, and (b) guidance for model calibration of other API steels.

Calculation of gas-flow in plasma reactor for carbon partial oxidation

NASA Astrophysics Data System (ADS)

Bespala, Evgeny; Myshkin, Vyacheslav; Novoselov, Ivan; Pavliuk, Alexander; Makarevich, Semen; Bespala, Yuliya

2018-03-01

The paper discusses isotopic effects at carbon oxidation in low temperature non-equilibrium plasma at constant magnetic field. There is described routine of experiment and defined optimal parameters ensuring maximum enrichment factor at given electrophysical, gas-dynamic, and thermodymanical parameters. It has been demonstrated that at high-frequency generator capacity of 4 kW, supply frequency of 27 MHz and field density of 44 mT the concentration of paramagnetic heavy nuclei 13C in gaseous phase increases up to 1.78 % compared to 1.11 % for natural concentration. Authors explain isotopic effect decrease during plasmachemical separation induced by mixing gas flows enriched in different isotopes at the lack of product quench. With the help of modeling the motion of gas flows inside the plasma-chemical reactor based on numerical calculation of Navier-Stokes equation authors determine zones of gas mixing and cooling speed. To increase isotopic effects and proportion of 13C in gaseous phase it has been proposed to use quench in the form of Laval nozzle of refractory steel. The article represents results on calculation of optimal Laval Nozzle parameters for plasma-chemical reactor of chosen geometry of. There are also given dependences of quench time of products on pressure at the diffuser output and on critical section diameter. Authors determine the location of quench inside the plasma-chemical reactor in the paper.

Hydrogen species motion in piezoelectrics: A quasi-elastic neutron scattering study

NASA Astrophysics Data System (ADS)

Alvine, K. J.; Tyagi, M.; Brown, C. M.; Udovic, T. J.; Jenkins, T.; Pitman, S. G.

2012-03-01

Hydrogen is known to damage or degrade piezoelectric materials, at low pressure for ferroelectric random access memory applications, and at high pressure for hydrogen-powered vehicle applications. The piezoelectric degradation is in part governed by the motion of hydrogen species within the piezoelectric materials. We present here quasi-elastic neutron scattering (QENS) measurements of the local hydrogen species motion within lead zirconate titanate (PZT) and barium titanate (BTO) on samples charged by exposure to high-pressure gaseous hydrogen (≈17 MPa). Neutron vibrational spectroscopy (NVS) studies of the hydrogen-enhanced vibrational modes are presented as well. Results are discussed in the context of theoretically predicted interstitial hydrogen lattice sites and compared to comparable bulk diffusion studies of hydrogen diffusion in lead zirconate titanate.

Laboratory Measurement of the Temperature Dependence of Gaseous Sulfur Dioxide (SO2) Microwave Absorption with Application to the Venus Atmosphere

NASA Technical Reports Server (NTRS)

Suleiman, Shady H.; Kolodner, Marc A.; Steffes, Paul G.

1996-01-01

High-accuracy laboratory measurements of the temperature dependence of the opacity from gaseous sulfur dioxide (SO2) in a carbon dioxide (CO2) atmosphere at temperatures from 290 to 505 K and at pressures from 1 to 4 atm have been conducted at frequencies of 2.25 GHz (13.3 cm), 8.5 GHz (3.5 cm), and 21.7 GHz (1.4 cm). Based on these absorptivity measurements, a Ben-Reuven (BR) line shape model has been developed that provides a more accurate characterization of the microwave absorption of gaseous S02 in the Venus atmosphere as compared with other formalisms. The developed BR formalism is incorporated into a radiative transfer model. The resulting microwave emission spectrum of Venus is then used to set an upper limit on the disk-averaged abundance of gaseous S02 below the main cloud layer. It is found that gaseous S02 has an upper limit of 150 ppm, which compares well with previous spacecraft in situ measurements and Earth-based radio astronomical observations.

CFD analyses of combustor and nozzle flowfields

NASA Astrophysics Data System (ADS)

Tsuei, Hsin-Hua; Merkle, Charles L.

1993-11-01

The objectives of the research are to improve design capabilities for low thrust rocket engines through understanding of the detailed mixing and combustion processes. A Computational Fluid Dynamic (CFD) technique is employed to model the flowfields within the combustor, nozzle, and near plume field. The computational modeling of the rocket engine flowfields requires the application of the complete Navier-Stokes equations, coupled with species diffusion equations. Of particular interest is a small gaseous hydrogen-oxygen thruster which is considered as a coordinated part of an ongoing experimental program at NASA LeRC. The numerical procedure is performed on both time-marching and time-accurate algorithms, using an LU approximate factorization in time, flux split upwinding differencing in space. The integrity of fuel film cooling along the wall, its effectiveness in the mixing with the core flow including unsteady large scale effects, the resultant impact on performance and the assessment of the near plume flow expansion to finite pressure altitude chamber are addressed.

Role of shell diffusion area in incubating eggs at simulated high altitude.

PubMed

Weiss, H S

1978-10-01

Embryonic development is inhibited when eggs are incubated at 9,100 m (0.3 atm) despite a normoxic environment. The problem apparently relates to respiratory gas exchange occurring by diffusion through gas-filled pores in the shell. Gaseous flux is therefore inversely proportional to ambient pressure and is affected by the physical characteristics of the ambient gas (Chapman-Enskog equation). Excess loss of H2O and CO2 occurs in eggs incubating at altitude and could be detrimental. Such increased loss should be correctable by decreasing diffusion area. This was tested by progressively increasing coverage of the shell with paraffin and incubating at simulated 0.3 ATA (225 Torr) in 100% O2. Uncoated eggs failed to hatch, but numbers of chicks increased with increased coverage. Maximum hatch was an extrapolated 90% of controls at 69% shell coverage. With further coverage, hatch size decreased. Egg weight loss, and estimate of H2O diffusion, was around three times controls in uncoated eggs but decreased linearly with paraffin coverage, reaching near normal at maximum hatch. Reduction of diffusion area to 0.3 normal at maximum hatch generally balanced the increased flux predicted for 0.3 ATA.

On the kinetics of pack aluminization

NASA Technical Reports Server (NTRS)

Gupta, B. K.; Sarkhel, A. K.; Seigle, L. L.

1975-01-01

A theory of pack aluminization has been formulated by combining gaseous and solid-state diffusion rates. This theory relates the surface composition of the coating and therefore, in principle, the phase morphology and the growth rate of the coating, to pack operating parameters such as pack aluminum density, type of activator, temperature and others. Experimental data on the aluminization of unalloyed nickel in pure aluminum packs obtained to date are in good agreement with the predictions of the theory.

Instability analysis of cosmic viscoelastic gyro-gravitating clouds in the presence of dark matter

NASA Astrophysics Data System (ADS)

Karmakar, Pralay Kumar; Das, Papari

2017-08-01

A classical formalism for the weakly nonlinear instability analysis of a gravitating rotating viscoelastic gaseous cloud in the presence of gyratory dark matter is presented on the cosmic Jeans flat scales of space and time. The constituent neutral gaseous fluid (NGF) and dark matter fluid (DMF) are inter-coupled frictionally via mutual gravity alone. Application of standard nonlinear perturbation techniques over the complex gyro-gravitating clouds results in a unique conjugated pair of viscoelastic forced Burgers (VFB) equations. The VFB pair is conjointly twinned by correlational viscoelastic effects. There is no regular damping term here, unlike, in the conventional Burgers equation for the luminous (bright) matter solely. Instead, an interesting linear self-consistent derivative force-term naturalistically appears. A numerical illustrative platform is provided to reveal the micro-physical insights behind the weakly non-linear natural diffusive eigen-modes. It is fantastically seen that the perturbed NGF evolves as extended compressive solitons and compressive shock-like structures. In contrast, the perturbed DMF grows as rarefactive extended solitons and hybrid shocks. The latter is micro-physically composed of rarefactive solitons and compressive shocks. The consistency and reliability of the results are validated in the panoptic light of the existing reports based on the preeminent nonlinear advection-diffusion-based Burgers fabric. At the last, we highlight the main implications and non-trivial futuristic applications of the explored findings.

Thermal discharges from Paducah Gaseous Diffusion Plant outfalls: Impacts on stream temperatures and fauna of Little Bayou and Big Bayou Creeks

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

Roy, W.K.; Ryon, M.G.; Hinzman, R.L.

1996-03-01

The development of a biological monitoring plan for the receiving streams of the Paducah Gaseous Diffusion Plant (PGDP) began in the late 1980s, because of an Agreed Order (AO) issued in September 1987 by the Kentucky Division of Water (KDOW). Five years later, in September 1992, more stringent effluent limitations were imposed upon the PGDP operations when the KDOW reissued Kentucky Pollutant Discharge Elimination System permit No. KY 0004049. This action prompted the US Department of Energy (DOE) to request a stay of certain limits contained in the permit. An AO is being negotiated between KDOW, the US Enrichment Corporationmore » (USEC), and DOE that will require that several studies be conducted, including this stream temperature evaluation study, in an effort to establish permit limitations. All issues associated with this AO have been resolved, and the AO is currently being signed by all parties involved. The proposed effluent temperature limit is 89 F (31.7 C) as a mean monthly temperature. In the interim, temperatures are not to exceed 95 F (35 C) as a monthly mean or 100 F (37.8 C) as a daily maximum. This study includes detailed monitoring of instream temperatures, benthic macroinvertebrate communities, fish communities, and a laboratory study of thermal tolerances.« less

Thermal Discharges from Paducah Gaseous Diffusion Plant Outfalls: Impacts on Stream Temperatures and Fauna of Little Bayou and Big Bayou Creeks

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

Roy, W.K.

1999-01-01

The development of a biological monitoring plan for the receiving streams of the Paducah Gaseous Diffusion Plant (PGDP) began in the late 1980s, because of an Agreed Order (AO) issued in September 1987 by the Kentucky Division of Water (KDOW). Five years later, in September 1992, more stringent effluent limitations were imposed upon the PGDP operations when the KDOW reissued Kentucky Pollutant Discharge Elimination System permit No. KY 0004049. This action prompted the US Department of Energy (DOE) to request a stay of certain limits contained in the permit. An AO is being negotiated between KDOW, the United States Enrichmentmore » Corporation (USEC), and DOE that will require that several studies be conducted, including this stream temperature evaluation study, in an effort to establish permit limitations. All issues associated with this AO have been resolved, and the AO is currently being signed by all parties involved. The proposed effluent temperature limit is 89 F (31.7C) as a mean monthly temperature. In the interim, temperatures are not to exceed 95 F (35 C) as a monthly mean or 100 F (37.8 C) as a daily maximum. This study includes detailed monitoring of instream temperatures, benthic macroinvertebrate communities, fish communities, and a laboratory study of thermal tolerances.« less

Thoron Mitigation System based on charcoal bed for applications in thorium fuel cycle facilities (part 1): Development of theoretical models for design considerations.

PubMed

Sahoo, B K; Sudeep Kumara, K; Karunakara, N; Gaware, J J; Sapra, B K; Mayya, Y S

2017-06-01

Regulating the environmental discharge of 220 Rn (historically known as thoron) and its decay products from thorium processing facilities is important for protection of environment and general public living in the vicinities. Activated charcoal provides an effective solution to this problem because of its high adsorption capacity to gaseous element like radon. In order to design and develop a charcoal based Thoron Mitigation System, a mathematical model has been developed in the present work for studying the 220 Rn transport and adsorption in a flow through charcoal bed and estimating the 220 Rn mitigation factor (MF) as a function of system and operating parameters. The model accounts for inter- and intra-grain diffusion, advection, radioactive decay and adsorption processes. Also, the effects of large void fluctuation and wall channeling on the mitigation factor have been included through a statistical model. Closed form solution has been provided for the MF in terms of adsorption coefficient, system dimensions, grain size, flow rate and void fluctuation exponent. It is shown that the delay effects due to intra grain diffusion plays a significant role thereby rendering external equilibrium assumptions unsuitable. Also, the application of the statistical model clearly demonstrates the transition from the exponential MF to a power-law form and shows how the occurrence of channels with low probability can lower mitigation factor by several orders of magnitude. As a part of aiding design, the model is further extended to optimise the bed dimensions in respect of pressure drop and MF. The application of the results for the design and development of a practically useful charcoal bed is discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Start Toward Micronucleus-Based Decompression Models; Altitude Decompression

NASA Technical Reports Server (NTRS)

Van Liew, H. D.; Conkin, Johnny

2007-01-01

Do gaseous micronuclei trigger the formation of bubbles in decompression sickness (DCS)? Most previous instructions for DCS prevention have been oriented toward supersaturated gas in tissue. We are developing a mathematical model that is oriented toward the expected behavior of micronuclei. The issue is simplified in altitude decompressions because the aviator or astronaut is exposed only to decompression, whereas in diving there is a compression before the decompression. The model deals with four variables: duration of breathing of 100% oxygen before going to altitude (O2 prebreathing), altitude of the exposure, exposure duration, and rate of ascent. Assumptions: a) there is a population of micronuclei of various sizes having a range of characteristics, b) micronuclei are stable until they grow to a certain critical nucleation radius, c) it takes time for gas to diffuse in or out of micronuclei, and d) all other variables being equal, growth of micronuclei upon decompression is more rapid at high altitude because of the rarified gas in the micronuclei. To estimate parameters, we use a dataset of 4,756 men in altitude chambers exposed to various combinations of the model s variables. The model predicts occurrence of DCS symptoms quite well. It is notable that both the altitude chamber data and the model show little effect of O2 prebreathing until it lasts more than 60 minutes; this is in contrast to a conventional idea that the benefit of prebreathing is directly due to exponential washout of tissue nitrogen. The delay in response to O2 prebreathing can be interpreted as time required for outward diffusion of nitrogen; when the micronuclei become small enough, they are disabled, either by crushing or because they cannot expand to a critical nucleation size when the subject ascends to altitude.

Long residence times of rapidly decomposable soil organic matter: application of a multi-phase, multi-component, and vertically-resolved model (TOUGHREACTv1) to soil carbon dynamics

NASA Astrophysics Data System (ADS)

Riley, W. J.; Maggi, F. M.; Kleber, M.; Torn, M. S.; Tang, J. Y.; Dwivedi, D.; Guerry, N.

2014-01-01

Accurate representation of soil organic matter (SOM) dynamics in Earth System Models is critical for future climate prediction, yet large uncertainties exist regarding how, and to what extent, the suite of proposed relevant mechanisms should be included. To investigate how various mechanisms interact to influence SOM storage and dynamics, we developed a SOM reaction network integrated in a one-dimensional, multi-phase, and multi-component reactive transport solver. The model includes representations of bacterial and fungal activity, multiple archetypal polymeric and monomeric carbon substrate groups, aqueous chemistry, aqueous advection and diffusion, gaseous diffusion, and adsorption (and protection) and desorption from the soil mineral phase. The model predictions reasonably matched observed depth-resolved SOM and dissolved organic carbon (DOC) stocks in grassland ecosystems as well as lignin content and fungi to aerobic bacteria ratios. We performed a suite of sensitivity analyses under equilibrium and dynamic conditions to examine the role of dynamic sorption, microbial assimilation rates, and carbon inputs. To our knowledge, observations do not exist to fully test such a complicated model structure or to test the hypotheses used to explain observations of substantial storage of very old SOM below the rooting depth. Nevertheless, we demonstrated that a reasonable combination of sorption parameters, microbial biomass and necromass dynamics, and advective transport can match observations without resorting to an arbitrary depth-dependent decline in SOM turnover rates, as is often done. We conclude that, contrary to assertions derived from existing turnover time based model formulations, observed carbon content and δ14C vertical profiles are consistent with a representation of SOM dynamics consisting of (1) carbon compounds without designated intrinsic turnover times, (2) vertical aqueous transport, and (3) dynamic protection on mineral surfaces.

Long residence times of rapidly decomposable soil organic matter: application of a multi-phase, multi-component, and vertically resolved model (BAMS1) to soil carbon dynamics

NASA Astrophysics Data System (ADS)

Riley, W. J.; Maggi, F.; Kleber, M.; Torn, M. S.; Tang, J. Y.; Dwivedi, D.; Guerry, N.

2014-07-01

Accurate representation of soil organic matter (SOM) dynamics in Earth system models is critical for future climate prediction, yet large uncertainties exist regarding how, and to what extent, the suite of proposed relevant mechanisms should be included. To investigate how various mechanisms interact to influence SOM storage and dynamics, we developed an SOM reaction network integrated in a one-dimensional, multi-phase, and multi-component reactive transport solver. The model includes representations of bacterial and fungal activity, multiple archetypal polymeric and monomeric carbon substrate groups, aqueous chemistry, aqueous advection and diffusion, gaseous diffusion, and adsorption (and protection) and desorption from the soil mineral phase. The model predictions reasonably matched observed depth-resolved SOM and dissolved organic matter (DOM) stocks and fluxes, lignin content, and fungi to aerobic bacteria ratios. We performed a suite of sensitivity analyses under equilibrium and dynamic conditions to examine the role of dynamic sorption, microbial assimilation rates, and carbon inputs. To our knowledge, observations do not exist to fully test such a complicated model structure or to test the hypotheses used to explain observations of substantial storage of very old SOM below the rooting depth. Nevertheless, we demonstrated that a reasonable combination of sorption parameters, microbial biomass and necromass dynamics, and advective transport can match observations without resorting to an arbitrary depth-dependent decline in SOM turnover rates, as is often done. We conclude that, contrary to assertions derived from existing turnover time based model formulations, observed carbon content and Δ14C vertical profiles are consistent with a representation of SOM consisting of carbon compounds with relatively fast reaction rates, vertical aqueous transport, and dynamic protection on mineral surfaces.

PolyPole-1: An accurate numerical algorithm for intra-granular fission gas release

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

Pizzocri, D.; Rabiti, C.; Luzzi, L.

2016-09-01

This paper describes the development of a new numerical algorithm (called PolyPole-1) to efficiently solve the equation for intra-granular fission gas release in nuclear fuel. The work was carried out in collaboration with Politecnico di Milano and Institute for Transuranium Elements. The PolyPole-1 algorithms is being implemented in INL's fuels code BISON code as part of BISON's fission gas release model. The transport of fission gas from within the fuel grains to the grain boundaries (intra-granular fission gas release) is a fundamental controlling mechanism of fission gas release and gaseous swelling in nuclear fuel. Hence, accurate numerical solution of themore » corresponding mathematical problem needs to be included in fission gas behaviour models used in fuel performance codes. Under the assumption of equilibrium between trapping and resolution, the process can be described mathematically by a single diffusion equation for the gas atom concentration in a grain. In this work, we propose a new numerical algorithm (PolyPole-1) to efficiently solve the fission gas diffusion equation in time-varying conditions. The PolyPole-1 algorithm is based on the analytic modal solution of the diffusion equation for constant conditions, with the addition of polynomial corrective terms that embody the information on the deviation from constant conditions. The new algorithm is verified by comparing the results to a finite difference solution over a large number of randomly generated operation histories. Furthermore, comparison to state-of-the-art algorithms used in fuel performance codes demonstrates that the accuracy of the PolyPole-1 solution is superior to other algorithms, with similar computational effort. Finally, the concept of PolyPole-1 may be extended to the solution of the general problem of intra-granular fission gas diffusion during non-equilibrium trapping and resolution, which will be the subject of future work.« less

Method and apparatus for producing oxygen and nitrogen and membrane therefor

DOEpatents

Roman, I.C.; Baker, R.W.

1985-09-17

Process and apparatus for the separation and purification of oxygen and nitrogen as well as a novel membrane useful therein are disclosed. The process utilizes novel facilitated transport membranes to selectively transport oxygen from one gaseous stream to another, leaving nitrogen as a byproduct. In the method, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a polar organic membrane which separates a gaseous feed stream such as atmospheric air and a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form at the interface of the feed stream with the membrane, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form at the interface of the product stream with the membrane. In an alternate mode of operation, the feed stream is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form at the interface of the feed stream with the membrane and the product stream is maintained at a sufficiently high temperature to keep the carrier in its deoxygenated form at the interface of the product stream with the membrane. Under such conditions, the carrier acts as a shuttle, picking up oxygen at the feed side of the membrane, diffusing across the membrane as the oxygenated complex, releasing oxygen to the product stream, and then diffusing back to the feed side to repeat the process. Exceptionally and unexpectedly high O[sub 2]/N[sub 2] selectivity, on the order of 10 to 30, is obtained, as well as exceptionally high oxygen permeability, on the order of 6 to 15 [times] 10[sup [minus]8] cm[sup 3]-cm/cm[sup 2]-sec-cmHg, as well as a long membrane life of in excess of 3 months, making the process commercially feasible. 2 figs.

Development of a coupled diffusion denuder system combined with gas chromatography/mass spectrometry for the separation and quantification of molecular iodine and the activated iodine compounds iodine monochloride and hypoiodous acid in the marine atmosphere.

PubMed

Huang, Ru-Jin; Hoffmann, Thorsten

2009-03-01

This study concerns the development of a coupled diffusion denuder system capable of separating and quantifying gaseous molecular iodine (I(2)) and two other highly reactive iodine species, ICl and HOI, which are collectively named activated iodine compounds (AIC). Both I(2) and AIC are key species in the atmospheric chemistry of iodine. 1,3,5-Trimethoxybenzene (1,3,5-TMB)- and alpha-cyclodextrin/(129)I(-) (alpha-CD/(129)I(-))-coated denuders proved to be suitable for the collection of gaseous AIC and I(2), respectively. The experimental collection efficiencies for AIC (tested as ICl) and I(2) agreed well with the theoretical values for gas flow rates in the range between 300 and 1800 mL min(-1). The coupled denuder system (1,3,5-TMB-coated denuder as front-denuder coupled upstream of an alpha-CD/(129)I(-)-coated denuder) was applied successfully to separate test gas mixtures of ICl and I(2) at various mixing ratios in the laboratory. The operation of both denuder systems was demonstrated to be independent of relative humidity (0-100%) and storage period (at least 2 weeks prior to and after sampling). Detection limits were achieved at sub-parts-per-trillion-by-volume (sub-pptv) level. The presented method provides a reliable and practical approach for the speciation of gaseous iodine compounds. In addition, we report for the first time ambient air measurements of AIC mixing ratios, carried out at the atmospheric research station in Mace Head, Ireland. A maximum concentration of AIC of 30.2 pptv was observed for nighttime measurements and 6.0 pptv for daytime measurements. A similar diurnal pattern was found for I(2) with an average concentration level of 23.2 pptv during daytime and 85.1 pptv during nighttime, indicating a strong correlation with AIC.

Method and apparatus for producing oxygen and nitrogen and membrane therefor

DOEpatents

Roman, Ian C.; Baker, Richard W.

1985-01-01

Process and apparatus for the separation and purification of oxygen and nitrogen as well as a novel membrane useful therein are disclosed. The process utilizes novel facilitated transport membranes to selectively transport oxygen from one gaseous stream to another, leaving nitrogen as a byproduct. In the method, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a polar organic membrane which separates a gaseous feed stream such as atmospheric air and a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form at the interface of the feed stream with the membrane, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form at the interface of the product stream with the membrane. In an alternate mode of operation, the feed stream is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form at the interface of the feed stream with the membrane and the product stream is maintained at a sufficiently high temperature to keep the carrier in its deoxygenated form at the interface of the product stream with the membrane. Under such conditions, the carrier acts as a shuttle, picking up oxygen at the feed side of the membrane, diffusing across the membrane as the oxygenated complex, releasing oxygen to the product stream, and then diffusing back to the feed side to repeat the process. Exceptionally and unexpectedly high O.sub.2 /N.sub.2 selectivity, on the order of 10 to 30, is obtained, as well as exceptionally high oxygen permeability, on the order of 6 to 15.times.10.sup.-8 cm.sup.3 -cm/cm.sup.2 -sec-cmHg, as well as a long membrane life of in excess of 3 months, making the process commercially feasible.

Quantum chemical approach for condensed-phase thermochemistry (IV): Solubility of gaseous molecules

NASA Astrophysics Data System (ADS)

Ishikawa, Atsushi; Kamata, Masahiro; Nakai, Hiromi

2016-07-01

The harmonic solvation model (HSM) was applied to the solvation of gaseous molecules and compared to a procedure based on the ideal gas model (IGM). Examination of 25 molecules showed that (i) the accuracy of ΔGsolv was similar for both methods, but the HSM shows advantages for calculating ΔHsolv and TΔSsolv; (ii) TΔSsolv contributes more than ΔHsolv to ΔGsolv in the HSM, i.e. the solvation of gaseous molecules is entropy-driven, which agrees well with experimental understanding (the IGM does not show this); (iii) the temperature dependence of Henry's law coefficient was correctly reproduced with the HSM.

Mechanisms of Inactivation of Dry Escherichia coli by High-Pressure Carbon Dioxide

PubMed Central

Chen, Yuan Yao; Temelli, Feral

2017-01-01

ABSTRACT High-pressure carbon dioxide processing is a promising technology for nonthermal food preservation. However, few studies have determined the lethality of high-pressure CO2 on dry bacterial cells, and the mechanism of inactivation remains unknown. This study explored the mechanisms of inactivation by using Escherichia coli AW1.7 and mutant strains differing in heat and acid resistance, in membrane composition based on disruption of the locus of heat resistance, and in genes coding for glutamate decarboxylases and cyclopropane fatty acid synthase. The levels of lethality of treatments with liquid, gaseous, and supercritical CO2 were compared. The cell counts of E. coli AW1.7 and mutants with a water activity (aW) of 1.0 were reduced by more than 3 log10 (CFU/ml) after supercritical CO2 treatment at 35°C for 15 min; increasing the pressure generally enhanced inactivation, except for E. coli AW1.7 ΔgadAB. E. coli AW1.7 Δcfa was more susceptible than E. coli AW1.7 after treatment at 10 and 40 MPa; other mutations did not affect survival. Dry cells of E. coli were resistant to treatments with supercritical and liquid CO2 at any temperature. Treatments with gaseous CO2 at 65°C were more bactericidal than those with supercritical CO2 or treatments at 65°C only. Remarkably, E. coli AW1.7 was more susceptible than E. coli AW1.7 Δcfa when subjected to the gaseous CO2 treatment. This study identified CO2-induced membrane fluidization and permeabilization as causes of supercritical mediated microbial inactivation, and diffusivity was a dominant factor for gaseous CO2. IMPORTANCE The safety of dry foods is of increasing concern for public health. Desiccated microorganisms, including pathogens, remain viable over long periods of storage and generally tolerate environmental insults that are lethal to the same organisms at high water activity. This study explored the use of high-pressure carbon dioxide to determine its lethality for dried Escherichia coli and to provide insight into the mechanisms of inactivation. The lethality of high-pressure CO2 and the mechanisms of CO2-mediated inactivation of dry E. coli depended on the physical state of CO2. Liquid and supercritical CO2 were ineffective in reducing the cell counts of dry E. coli isolates, and the effectiveness of gaseous CO2 was related to the diffusivity of CO2. Results provide a novel and alternative method for the food industry to enhance the safety of low aW products. PMID:28283526