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Validation and sensitivity of a simulated photograph technique for visibility modeling

Description: The Los Alamos Scientific Laboratory (LASL) visibility model is capable of producing simulated before and after pictures that illustrate visual effects of smoke plumes. Although the model has been under development for a few years, until recently there had been very little testing of the model against field experience or testing of sensitivity of the model results to numerical approximations used in the model. Further validation and sensitivity testing of the LASL model began in late 1979. The … more
Date: January 1, 1980
Creator: Williams, M.; Chan, L.Y. & Lewis, R.
Partner: UNT Libraries Government Documents Department
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Use of principal components analysis and three-dimensional atmospheric-transport models for reactor-consequence evaluation

Description: This work explores the use of principal components analysis coupled to three-dimensional atmospheric transport and dispersion models for evaluating the environmental consequences of reactor accidents. This permits the inclusion of meteorological data from multiple sites and the effects of topography in the consequence evaluation; features not normally included in such analyses. The technique identifies prevailing regional wind patterns and their frequencies for use in the transport and dispersi… more
Date: January 1, 1982
Creator: Gudiksen, P. H.; Walton, J. J.; Alpert, D. J. & Johnson, J. D.
Partner: UNT Libraries Government Documents Department
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Enhanced tritium transport and release by solids modification

Description: To improve the tritium release characteristics of lithium ceramics, we are investigating the effects of dopants on tritium transport and release. Prior work has suggested a correlation between tritium and lithium diffusion in lithium-containing ceramics. This correlation has led us to propose a mechanism for tritium diffusion in which the tritium diffuses in the form of a lithium vacancy-triton complex. If this is the case, one should be able to increase the tritium diffusivity by increasing th… more
Date: January 1, 1989
Creator: Kopasz, J. P.; Tam, S. W. & Johnson, C. E.
Partner: UNT Libraries Government Documents Department
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Review of Gaussian diffusion-deposition models

Description: The assumptions and predictions of several Gaussian diffusion-deposition models are compared. A simple correction to the Chamberlain source depletion model is shown to predict ground-level airborne concentrations and dry deposition fluxes in close agreement with the exact solution of Horst.
Date: January 1, 1979
Creator: Horst, T.W.
Partner: UNT Libraries Government Documents Department
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Transport, stability and relaxation of a spheromak

Description: We consider a zero-..beta.. spheromak contained in a rectangular region having perfectly conducting boundaries in its minimum energy state, and we calculate its evolution. Our results may be summarized as follows. Since this state is a stable equilibrium, the initial evolution of the plasma is caused by diffusion. We simulate this using a transport code. We find that q at the magnetic axis drops and q(r) becomes flat. When q on axis drops below 0.5, the spheromak becomes unstable to an n = 2 ki… more
Date: January 1, 1984
Creator: Sgro, A. G.; Marklin, G. & Mirin, A. A.
Partner: UNT Libraries Government Documents Department
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Neutron and gamma transport effects by heterogeneous core designs. [LMFBR]

Description: The use of diffusion theory for the prediction of power production near a reactor core-blanket interface and the assumption that gammas are absorbed in situ can lead to substantial errors. This is primarily due to the breakdown of Fick's law for neutron diffusion near the core-blanket boundary, and the gamma leakage from the core into the blanket. These considerations are more pronounced in a situation where a large number of internal blanket assemblies are present, such as in the large heterog… more
Date: January 1, 1977
Creator: Lam, S.K.
Partner: UNT Libraries Government Documents Department
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An optimized algorithm for solving the nodal diffusion method on shared memory multiprocessors

Description: Nodal methods play a special role in reactor physics calculations. In recent papers the high computational efficiency of nodal methods has been established and the development of more efficient algorithms tailored to the advanced architectures of modern day computers proposed. The rapidly changing architectures of today's computer influence the way codes have to be programmed so that reasonable speed up and efficiency are attained. We have applied these concepts in solving the one-group neutron… more
Date: January 1, 1990
Creator: Kirk, B.L. & Azmy, Y.Y.
Partner: UNT Libraries Government Documents Department
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Variational methods in steady state diffusion problems

Description: Classical variational techniques are used to obtain accurate solutions to the multigroup multiregion one dimensional steady state neutron diffusion equation. Analytic solutions are constructed for benchmark verification. Functionals with cubic trial functions and conservational lagrangian constraints are exhibited and compared with nonconservational functionals with respect to neutron balance and to relative flux and current at interfaces. Excellent agreement of the conservational functionals u… more
Date: January 1, 1983
Creator: Lee, C.E.; Fan, W.C.P. & Bratton, R.L.
Partner: UNT Libraries Government Documents Department
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Uranium hexafluoride: Safe handling, processing, and transporting: Conference proceedings

Description: This conference seeks to provide a forum for the exchange of information and ideas of the safety aspects and technical issue related to the handling of uranium hexafluoride. By allowing operators, engineers, scientists, managers, educators, and others to meet and share experiences of mutual concern, the conference is also intended to provide the participants with a more complete knowledge of technical and operational issues. The topics for the papers in the proceedings are widely varied and inc… more
Date: January 1, 1988
Creator: Strunk, W.D. & Thornton, S.G. (eds.)
Partner: UNT Libraries Government Documents Department
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Study of technetium uptake in vegetation in the vicinity of the Portsmouth Gaseous Diffusion Plant

Description: Technetium-99 was measured in vegetation and soil collected on and near the Portsmouth Gaseous Diffusion Plant to obtain an estimate of the soil-to-vegetation concentration factors. The concentration factors appear to be lognormally distributed with a geometric mean of 3.4 (Bq/kg dry wt. tissue per Bq/kg dry wt. soil) and a geometric standard deviation of 4.7. A dose commitment was calculated using a hypothetical 3.7 x 10/sup 10/ Bq Tc-99/year release and the actual CY-1981 concentration releas… more
Date: January 1, 1982
Creator: Acox, T.A.
Partner: UNT Libraries Government Documents Department
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Separation of tritium from gaseous and aqueous effluent systems

Description: Three processes are discussed for separating tritium from gaseous and aqueous effluent systems: separation in the gas phase using Pd-25 wt percent Ag alloy diffusion membranes; electrolytic separation in the aqueous phase using ''bipolar'' electrodes; and the countercurrent exchange of tritium-containing hydrogen gas with water on catalytic surfaces combined with separation by direct electrolysis. (LK)
Date: January 1, 1977
Creator: Kobisk, E. H.
Partner: UNT Libraries Government Documents Department
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Extracting maximal information on positive muon diffusion in metals

Description: It is discussed how combining zero- and longitudinal-field ..mu..SR can give more information on the motion of the ..mu../sup +/ in the target than zero-field studies alone.
Date: January 1, 1982
Creator: Leon, M.
Partner: UNT Libraries Government Documents Department
open access

The use of BaF sub 2 buffer layers for the sputter-deposition of TlCaBaCuO thin-film superconductors

Description: Thin films of the Tl-based superconductors often have relatively poor properties because of film/substrate interdiffusion which occurs during the anneal. We have therefore investigated the use of BaF{sub 2} as a diffusion barrier. TlCaBaCuO thin films were deposited by dc magnetron sputtering onto MgO <100> substrates, both with and without an evaporation-deposited BaF{sub 2} buffer layer, and post-annealed in a Tl over-pressure. Electrical properties of the films were determined by four-point … more
Date: January 1, 1989
Creator: Hubbard, K. M.; Arendt, P. N.; Brown, D. R.; Cooke, D. W.; Elliott, N. E.; Farr, J. D. et al.
Partner: UNT Libraries Government Documents Department
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D. phi. vertex drift chamber construction and test results

Description: A jet-cell based vertex chamber has been built for the D{O} experiment at Fermilab and operated in a test beam there. Low drift velocity and diffusion properties were achieved using CO{sub 2}(95%)-ethane(5%) at atmospheric pressure. The drift velocity is found to be consistent with (9.74+8.68( E -1.25)) {mu}m/nsec where E is the electric field strength in (kV/cm < E z 1.6 kV/cm.) An intrinsic spatial resolution of 60 {mu}m or better for drift distances greater than 2 mm is measured. The track p… more
Date: May 1, 1991
Creator: Clark, A.R.; Goozen, F.; Grudberg, P.; Klopfenstein, C.; Kerth, L.T.; Loken, S.C. et al.
Partner: UNT Libraries Government Documents Department
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Solving the uncommon reactor core neutronics problems

Description: The common reactor core neutronics problems have fundamental neutron space, energy spectrum solutions. Typically the most positive eigenvalue is associated with an all-positive flux for the pseudo-steady-state condition (k/sub eff/), or the critical state is to be effected by selective adjustment of some variable such as the fuel concentration. With sophistication in reactor analysis has come the demand for solutions of other, uncommon neutronics problems. Importance functionss are needed for s… more
Date: January 1, 1980
Creator: Vondy, D.R. & Fowler, T.B.
Partner: UNT Libraries Government Documents Department
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Temperature dependence of the fraction of re-emitted positrons, the positron work function, and the positronium fraction for Cu(III)+S

Description: A beam of 1 keV positrons incident on a Cu(111)+S surface has been used to study the dependence on temperature of the positron work function (phi/sub +/), the yield of re-emitted positrons (Y) and of the positronium (Ps) fraction. A positive dependence of the slow-positron yield on temperature is found which is attributed in part to a reduction in the magnitude of phi/sub +/ (approx. 25%) at 50 K relative to its value at 300 K. A similar, though weaker, positive dependence on temperature was se… more
Date: January 1, 1982
Creator: Schultz, P.J. & Lynn, K.G.
Partner: UNT Libraries Government Documents Department
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Solar opacity and equation of state

Description: The disadvantages of radiative diffusion over radiative transfer in the photosphere as used in structure calculations is reemphasized. Uncertainties in the opacity due to uncertainties in chemical composition and in approximations of the physics are described and estimated. Internal consistency of equation of state and opacity is recommended.
Date: January 1, 1978
Creator: Huebner, W.F.
Partner: UNT Libraries Government Documents Department
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Condensed-matter research at the Los Alamos pulsed neutron source (WNR)

Description: The experimental program at the WNR in condensed matter research at present is aimed principally at utilizing the high epithermal neutron flux available at a spallation neutron source. Interesting new results have been obtained in several areas including hydrogen vibrations in metals, chemical vibrational spectroscopy and the structure of liquids. For example, extensive vibrational spectra were obtained of hydrogen in Nb which could be described in terms of a three-dimensional localized anharmo… more
Date: January 1, 1982
Creator: Eckert, J.
Partner: UNT Libraries Government Documents Department
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Freely expanding detonation products: Scaling of rate processes

Description: Using the Los Alamos reactive hydrodynamics code KIVA, calculations have been made to simulate the free expansion of cylinders of detonation products into a high vacuum. The emphasis of this paper is on the scaling of rate processes with cylinder size and initial conditions as a function of position in the expanding mass. The processes considered include diffusion, unimolecular decomposition, biomolecular radical reactions, and vibrational relaxation. The calculations also give time-dependent v… more
Date: January 1, 1988
Creator: Greiner, N. R.
Partner: UNT Libraries Government Documents Department
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RETADDII: modeling long-range atmospheric transport of radionuclides

Description: A versatile model is described which estimates atmospheric dispersion based on plume trajectories calculated for the mixed layer. This model allows the treatment of the dispersal from a source at an arbitrary height while taking account of plume depletion by dry and wet deposition together with the decay of material to successor species. The plume depletion, decay and growth equations are solved in an efficient manner which can accommodate up to eight pollutants (i.e. a parent and seven serial … more
Date: January 1, 1982
Creator: Murphy, B. D.
Partner: UNT Libraries Government Documents Department
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