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Thermodynamic performance of ceramic tritium breeding blanket material

Description: Thermodynamic calculations have been made to compare the thermochemical performance of three candidate breeder blanket materials, Li/sub 2/O, LiAlO/sub 2/, and Li/sub 4/SiO/sub 4/. These calculations were done for the temperature range of 900 to 1300/sup 0/K and the oxygen activity range of 10/sup -25/ to 10/sup -5/. Oxygen activity is an influential variable for these materials and must be considered in the diffusion of tritiated species, determining the chemical form of the released tritium, … more
Date: June 1, 1986
Creator: Johnson, C. E. & Fischer, A. K.
Partner: UNT Libraries Government Documents Department
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The effect of head-on beam-beam compensation on the stochastic boundaries and particle diffusion in RHIC.

Description: To compensate the effects from the head-on beam-beam interactions in the polarized proton operation in the Relativistic Heavy Ion Collider (RHIC), an electron lens (elens) is proposed to collide head-on with the proton beam. We used an extended version of SixTrack for multiparticle beam-beam simulation in order to study the effect of the e-lens on the stochastic boundary and also on diffusion. The stochastic boundary was analyzed using Lyapunov exponents and the diffusion was characterized as t… more
Date: June 23, 2008
Creator: Abreu,N.; Beebe-Wang, J.; FischW; Luo, Y. & Robert-Demolaize, G.
Partner: UNT Libraries Government Documents Department
open access

Isotopic mass-dependence of noble gas diffusion coefficients inwater

Description: Noble gas isotopes are used extensively as tracers inhydrologic and paleoclimatic studies. These applications requireknowledge of the isotopic mass (m) dependence of noble gas diffusioncoefficients in water (D), which has not been measured but is estimatedusing experimental D-values for the major isotopes along with an untestedrelationship from kinetic theory, D prop m-0.5. We applied moleculardynamics methods to determine the mass dependence of D for four noblegases at 298 K, finding that D pr… more
Date: June 25, 2007
Creator: Bourg, I.C. & Sposito, G.
Partner: UNT Libraries Government Documents Department
open access

Long-term Variations of CO2 Trapped in Different Mechanisms in Deep Saline Formations: A Case Study of the Songliao Basin, China

Description: The geological storage of CO{sub 2} in deep saline formations is increasing seen as a viable strategy to reduce the release of greenhouse gases to the atmosphere. There are numerous sedimentary basins in China, in which a number of suitable CO{sub 2} geologic reservoirs are potentially available. To identify the multi-phase processes, geochemical changes and mineral alteration, and CO{sub 2} trapping mechanisms after CO{sub 2} injection, reactive geochemical transport simulations using a simple… more
Date: June 10, 2008
Creator: Zhang, Wei; Li, Yilian; Xu, Tianfu; Cheng, Huilin; Zheng, Yan & Xiong, Peng
Partner: UNT Libraries Government Documents Department
open access

The Soret Effect in Naturally Propagating, Premixed, Lean, Hydrogen-Air Flames

Description: Comparatively little attention has been given to multicomponent diffusion effects in lean hydrogen-air flames, in spite of the importance of these flames in safety and their potential importance to future energy technologies. Prior direct numerical simulations either have considered only the mixture-averaged transport model, or have been limited to stabilized flames that do not exhibit the thermo-diffusive instability. The so-called full, multicomponent transport model with cross-diffusion is f… more
Date: June 30, 2008
Creator: Grcar, Joseph F.; Grcar, Joseph F.; Bell, John B. & Day, Marcus S.
Partner: UNT Libraries Government Documents Department
open access

THERMOSTATICS AND KINETICS OF TRANSFORMATIONS IN PU-BASED ALLOYS

Description: CALPHAD assessment of the thermodynamic properties of a series of Pu-based alloys is briefly presented together with some results on the kinetics of phase formation and transformations in Pu-Ga alloys.
Date: June 30, 2006
Creator: Turchi, P; Kaufman, L & Liu, Z
Partner: UNT Libraries Government Documents Department
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Proceedings of RIKEN BNL Research Center Workshop: Understanding QGP through Spectral Functions and Euclidean Correlators (Volume 89)

Description: In the past two decades, one of the most important goals of the nuclear physics community has been the production and characterization of the new state of matter--Quark-Gluon Plasma (QGP). Understanding how properties of hadrons change in medium, particularly, the bound state of a very heavy quark and its antiquark, known as quarkonium, as well as determining the transport coefficients is crucial for identifying the properties of QGP and for the understanding of the experimental data from RHIC.… more
Date: June 27, 2008
Creator: Mocsy, A. & Petreczky, P.
Partner: UNT Libraries Government Documents Department
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Isotopically controlled semiconductors

Description: The following article is an edited transcript based on the Turnbull Lecture given by Eugene E. Haller at the 2005 Materials Research Society Fall Meeting in Boston on November 29, 2005. The David Turnbull Lectureship is awarded to recognize the career of a scientist who has made outstanding contributions to understanding materials phenomena and properties through research, writing, and lecturing, as exemplified by the life work of David Turnbull. Haller was named the 2005 David Turnbull Lecture… more
Date: June 19, 2006
Creator: Haller, Eugene E.
Partner: UNT Libraries Government Documents Department
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Development of a High Fidelity System Analysis Code for Generation IV Reactors

Description: Traditional nuclear reactor system analysis codes such as RELAP and TRAC employ an operator split methodology. In this approach, each of the physics (fluid flow, heat conduction and neutron diffusion) is solved separately and the coupling terms are done explicitly. This approach limits accuracy (first order in time at best) and makes the codes slow in running since the explicit coupling imposes stability restrictions on the time step size. These codes have been extensively tested and validated … more
Date: June 1, 2008
Creator: Zhang, Hongbin; Mousseau, Vincent & Zhao, Haihua
Partner: UNT Libraries Government Documents Department
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Timescales of spherulite crystallization in obsidian inferred from water concentration profiles

Description: We determined the kinetics of spherulite growth in obsidians from Krafla volcano, Iceland. We measured water concentration profiles around spherulites in obsidian by synchrotron Fourier transform infrared spectroscopy. The distribution of OH? groups surrounding spherulites decreases exponentially away from the spherulite-glass border, reflecting expulsion of water during crystallization of an anhydrous paragenesis (plagioclase + SiO2 + clinopyroxene + magnetite). This pattern is controlled by a… more
Date: June 25, 2008
Creator: Castro, Jonathan M.; Beck, Pierre; Tuffen, Hugh; Nichols, Alexander R.L.; Dingwell, Donald B. & Martin, Michael C
Partner: UNT Libraries Government Documents Department
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Interactions of Oxygen and Hydrogen on Pd(111) surface

Description: The coadsorption and interactions of oxygen and hydrogen on Pd(1 1 1) was studied by scanning tunneling microscopy and density functional theory calculations. In the absence of hydrogen oxygen forms a (2 x 2) ordered structure. Coadsorption of hydrogen leads to a structural transformation from (2 x 2) to a ({radical}3 x {radical}3)R30 degree structure. In addition to this transformation, hydrogen enhances the mobility of oxygen. To explain these observations, the interaction of oxygen and hydro… more
Date: June 25, 2008
Creator: Demchenko, D.O.; Sacha, G.M.; Salmeron, M. & Wang, L.-W.
Partner: UNT Libraries Government Documents Department
open access

An Arbitrary Lagrangian-Eulerian Discretization of MHD on 3D Unstructured Grids

Description: We present an arbitrary Lagrangian-Eulerian (ALE) discretization of the equations of resistive magnetohydrodynamics (MHD) on unstructured hexahedral grids. The method is formulated using an operator-split approach with three distinct phases: electromagnetic diffusion, Lagrangian motion, and Eulerian advection. The resistive magnetic dynamo equation is discretized using a compatible mixed finite element method with a 2nd order accurate implicit time differencing scheme which preserves the diverg… more
Date: June 12, 2006
Creator: Rieben, R. N.; White, D. A.; Wallin, B. K. & Solberg, J. M.
Partner: UNT Libraries Government Documents Department
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Implications of Air Ingress Induced by Density-Difference Driven Stratified Flow

Description: One of the design basis accidents for the Next Generation Nuclear Plant (NGNP), a high temperature gas-cooled reactor, is air ingress subsequent to a pipe break. Following a postulated double-ended guillotine break in the hot duct, and the subsequent depressurization to nearly reactor cavity pressure levels, air present in the reactor cavity will enter the reactor vessel via density-gradient-driven-stratified flow. Because of the significantly higher molecular weight and lower initial temperatu… more
Date: June 1, 2008
Creator: Oh, Chang; Kim, Eung Soo; Schultz, Richard; Petti, David & Liou, C. P.
Partner: UNT Libraries Government Documents Department
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Continuous time random walk analysis of solute transport in fractured porous media

Description: The objective of this work is to discuss solute transport phenomena in fractured porous media, where the macroscopic transport of contaminants in the highly permeable interconnected fractures can be strongly affected by solute exchange with the porous rock matrix. We are interested in a wide range of rock types, with matrix hydraulic conductivities varying from almost impermeable (e.g., granites) to somewhat permeable (e.g., porous sandstones). In the first case, molecular diffusion is the only… more
Date: June 1, 2008
Creator: Cortis, Andrea; Cortis, Andrea & Birkholzer, Jens
Partner: UNT Libraries Government Documents Department
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Differencing asymptotic diffusion theory

Description: A diffusion theory is presented which extends asymptotic diffusion to non-uniform material properties. Finite difference methods for the diffusion theory naturally result in jump conditions on interfaces when appropriate.
Date: June 7, 1979
Creator: Zimmerman, G.B.
Partner: UNT Libraries Government Documents Department
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Waste dissolution with chemical reaction, diffusion and advection

Description: This paper extends the mass-transfer analysis to include the effect of advective transport in predicting the steady-state dissolution rate, with a chemical-reaction-rate boundary condition at the surface of a waste form of arbitrary shape. This new theory provides an analytic means of predicting the ground-water velocities at which dissolution rate in a geologic environment will be governed entirely to the chemical reaction rate. As an illustration, we consider the steady-state potential flow o… more
Date: June 1, 1987
Creator: Chambre, P. L.; Kang, C. H.; Lee, W. W. L. & Pigford, T. H.
Partner: UNT Libraries Government Documents Department
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Ion mixing of Ti/C and Fe/C bilayers

Description: Bilayer samples of Ti/C and Fe/C have been ion beam mixed with 400-keV Xe ions to a dose of 1 x 10/sup 16/ ions/cm/sup 2/. Mixing experiments were performed at 77, 300, 573, and 723/sup 0/K. The transition between the temperature-independent and temperature-dependent mixing occurred between 300 and 573/sup 0/K in Fe/C samples and between 573 and 723/sup 0/K in Ti/C sample. In the temperature-independent mixing regime, mixing is reasonably well explained by a thermodynamic model of ion mixing wh… more
Date: June 1, 1987
Creator: Nastasi, M.; Tesmer, J.R. & Hirvonen, J.P.
Partner: UNT Libraries Government Documents Department
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Diffusion studies in amorphous NiZr alloys

Description: Tracer impurity and self diffusion measurements have been made on amorphous (a-) NiZr alloys using radioactive tracer, Secondary Ion Mass Spectrometry and Rutherford backscattering techniques. The temperature dependence of diffusion in a-NiZr can be represented in the form D = D/sub 0/exp(-Q/kT), with no structural relaxation effects being observed. The mobility of an atom in a-NiZr increased dramatically with decreasing atomic radius of the diffusing atom and also with decreasing Ni content fo… more
Date: June 1, 1987
Creator: Hahn, H.; Averback, R. S.; Hoshino, K. & Rothman, S. J.
Partner: UNT Libraries Government Documents Department
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Gas-bubble growth mechanisms in the analysis of metal fuel swelling

Description: During steady-state irradiation, swelling rates associated with growth of fission-gas bubbles in metallic fast reactor fuels may be expected to remain small. As a consequence, bubble-growth mechanisms are not a major consideration in modeling the steady-state fuel behavior, and it is usually adequate to consider the gas pressure to be in equilibrium with the external pressure and surface tension restraint. On transient time scales, however, various bubble-growth mechanisms become important comp… more
Date: June 1, 1986
Creator: Gruber, E. E. & Kramer, J. M.
Partner: UNT Libraries Government Documents Department
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Tracer surface diffusion on UO/sub 2/

Description: Surface diffusion on UO/sub 2/ was measured by the spreading of U-234 tracer on the surface of a duplex diffusion couple consisting of wafers of depleted and enriched UO/sub 2/ joined by a bond of uranium metal.
Date: June 1, 1983
Creator: Zhou, S.Y. & Olander, D.R.
Partner: UNT Libraries Government Documents Department
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Geometry-independent approach to coarse-mesh neutron diffusion calculations

Description: Powerful coarse-mesh and nodal methods have been recently developed to calculate accurate node-average fluxes and eigenvalues. The nodal methods solve for the node-average flux by reducing the multidimensional diffusion problem to a coupled system of 1-D equations. These schemes are mainly limited to rectangular (xyz) nodes and cannot easily be extended to other geometries. The polynomial-based coarse-mesh methods have been applied to thetaRZ and HEXZ geometries. This summary describes the deve… more
Date: June 1, 1985
Creator: Kohut, P.
Partner: UNT Libraries Government Documents Department
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Sintering kinetics of pure and doped boron carbide

Description: The sintering of pure and doped boron carbide was investigated over the temperature range 1898 to 2380/sup 0/K and at additive levels ranging from 0.75 to 10.0%. The addition of 0.75 and 3.8 wt% of AlF/sub 3/, Ni, Fe, and Cu deactivated the sintering of B/sub 4/C at all temperatures. In contrast, the addition of 10.0 wt% these additives resulted in enhanced shrinkage in B/sub 4/C for the temperatures 1898 and 2133/sup 0/K. At the highest temperature, 2380/sup 0/K, the addition of 10.0 wt% AlF/s… more
Date: June 11, 1979
Creator: Lange, R. G.; Munir, Z. A. & Holt, J. B.
Partner: UNT Libraries Government Documents Department
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Modeling a multiple tracer release experiment during nocturnal drainage flow in complex terrain

Description: The complex conditions posed by very localized winds and turbulence, rugged topography, variable surface roughness, strong vertical motions and gravity flow require a three-dimensional modeling approach to realistically simulate the dispersal of hydrogen sulfide injected into the atmosphere at the Geysers geothermal area. In this study the three-dimensional particle-in-cell numerical diffusion model ADPIC (Lange, 1973 and 1978) was used to simulate the transport and diffusion of two simultaneou… more
Date: June 1, 1981
Creator: Lange, R.
Partner: UNT Libraries Government Documents Department
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