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Implicit Eulerian method for analyzing transient phenomena in fast reactors

Description: An Eulerian compressible hydrodynamic method is presented for analyzing transient phenomena in nuclear reactors following hypothetical excursions. The method uses the implicit integration scheme to solve nonlinear equations of fluid dynamics in conjunction with a thin-shell analysis to calculate the response of the wall boundary. Detailed formulations are given. Results are presented for two example problems and compared with available experimental data. 6 references. (auth)
Date: October 1, 1975
Creator: Wang, C.Y.
Partner: UNT Libraries Government Documents Department

Structural and seismic analyses of waste facility reinforced concrete storage vaults

Description: Facility 317 of Argonne National Laboratory consists of several reinforced concrete waste storage vaults designed and constructed in the late 1940`s through the early 1960`s. In this paper, structural analyses of these concrete vaults subjected to various natural hazards are described, emphasizing the northwest shallow vault. The natural phenomenon hazards considered include both earthquakes and tornados. Because these vaults are deeply embedded in the soil, the SASSI (System Analysis of Soil-Structure Interaction) code was utilized for the seismic calculations. The ultimate strength method was used to analyze the reinforced concrete structures. In all studies, moment and shear strengths at critical locations of the storage vaults were evaluated. Results of the structural analyses show that almost all the waste storage vaults meet the code requirements according to ACI 349--85. These vaults also satisfy the performance goal such that confinement of hazardous materials is maintained and functioning of the facility is not interrupted.
Date: July 1995
Creator: Wang, C. Y.
Partner: UNT Libraries Government Documents Department

Mitigation of earthquake hazards using seismic isolation systems

Description: This paper describes mitigation of earthquake hazards using seismic base isolation systems. A numerical algorithm for analyzing system response of base-isolated structures with laminated elastomer bearings is briefly described. Seismic response analyses of both base- isolated and unisolated buildings under earthquakes {number_sign}42 and {number_sign}44 are performed and the results are compared to illustrate the mitigating effect of base-isolated systems.
Date: June 1, 1996
Creator: Wang, C.-Y.
Partner: UNT Libraries Government Documents Department

ICECO-CEL: A Coupled Eulerian-Lagrangian Code for Analyzing Primary System Response in Fast Reactors

Description: This report describes a coupled Eulerian-Lagrangian code, ICECO-CEL, for analyzing the response of the primary system during hypothetical core disruptive accidents. The implicit Eulerian method is used to calculate the fluid motion so that large fluid distortion, two-dimensional sliding interface, flow around corners, flow through coolant passageways, and out-flow boundary conditions can be treated. The explicit Lagrangian formulation is employed to compute the response of the containment vessel and other elastic-plastic solids inside the reactor containment. Large displacements, as well as geometrical and material nonlinearities are considered in the analysis. Marker particles are utilized to define the free surface or the material interface and to visualize the fluid motion. The basic equations and numerical techniques used in the Eulerian hydrodynamics and Lagrangian structural dynamics are described. Treatment of the above-core hydrodynamics, sodium spillage, fluid cavitation, free-surface boundary conditions and heat transfer are also presented. Examples are given to illustrate the capabilities of the computer code. Comparisons of the code predictions with available experimental data are also made.
Date: February 1981
Creator: Wang, C. Y.
Partner: UNT Libraries Government Documents Department

Analysis of LMFBR primary system response to an HCDA using an Eulerian computer code

Description: Applications of an Eulerian code to predict the response of LMFBR containment and primary piping systems to hypothetical core disruptive accidents (HCDA), and to analyze sodium spillage problems, are described. The computer code is an expanded version of the ICECO code. Sample problems are presented for slug impact and sodium spillage, dynamics of the HCDA bubbles, and response of a piping loop. (JWR)
Date: January 1, 1975
Creator: Chang, Y.W.; Wang, C.Y.; Chu, H.Y.; Abdel-Moneim, M.T. & Gvildys, J.
Partner: UNT Libraries Government Documents Department

Computational fluid dynamics modeling of proton exchange membrane fuel cells

Description: A transient, multi-dimensional model has been developed to simulate proton exchange membrane (PEM) fuel cells. The model accounts simultaneously for electrochemical kinetics, current distribution, hydrodynamics and multi-component transport. A single set of conservation equations valid for flow channels, gas-diffusion electrodes, catalyst layers and the membrane region are developed and numerically solved using a finite-volume-based computational fluid dynamics (CFD) technique. The numerical model is validated against published experimental data with good agreement. Subsequently, the model is applied to explore hydrogen dilution effects in the anode feed. The predicted polarization cubes under hydrogen dilution conditions are found to be in qualitative agreement with recent experiments reported in the literature. The detailed two-dimensional electrochemical and flow/transport simulations further reveal that in the presence of hydrogen dilution in the fuel stream, hydrogen is depleted at the reaction surface resulting in substantial kinetic polarization and hence a lower current density that is limited by hydrogen transport from the fuel stream to the reaction site.
Date: February 11, 2000
Partner: UNT Libraries Government Documents Department

Two-phase flow and transport in the air cathode of proton exchange membrane fuel cells

Description: Two-phase flow and transport of reactants and products in the air cathode of proton exchange membrane (PEM) fuel cells is studied analytically and numerically. Four regimes of water distribution and transport are classified by defining three threshold current densities and a maximum current density. They correspond to first appearance of liquid water at the membrane/cathode interface, extension of the gas-liquid two-phase zone to the cathode/channel interface, saturated moist air exiting the gas channel, and complete consumption of oxygen by the electrochemical reaction. When the cell operates above the first threshold current density, liquid water appears and a two-phase zone forms within the porous cathode. A two-phase, multi-component mixture model in conjunction with a finite-volume-based computational fluid dynamics (CFD) technique is applied to simulate the cathode operation in this regime. The model is able to handle the situation where a single-phase region co-exists with a two-phase zone in the air cathode. For the first time, the polarization curve as well as water and oxygen concentration distributions encompassing both single- and two-phase regimes of the air cathode are presented. Capillary action is found to be the dominant mechanism for water transport inside the two-phase zone. The liquid water saturation within the cathode is predicted to reach 6.3% at 1.4 A/cm{sup 2}.
Date: March 20, 2000
Creator: WANG,Z.H.; WANG,C.Y. & CHEN,KEN S.
Partner: UNT Libraries Government Documents Department

Three-dimensional antenna models for fusion experiments

Description: The development of the RANT3D code has permitted the systematic study Of the effect of three-dimensional structures on the launched power spectrum for antennas in the ion cyclotron range of frequencies. The code allows the septa between current straps to be modeled with arbitrary heights and permits the antenna to interact with other structures in the tokamak. In this paper we present comparisons of calculated loading with the Tokamak Fusion Test Reactor and Tore Supra experiments, demonstrate the effects on loading caused by positioning uncertainties for an antenna in Tore Supra, and show electric field patterns near the Tore Supra antenna. A poloidal component in the static magnetic field for the plasma response is included in the near-field calculations using the warm plasma code, GLOSI. Preliminary estimates for the heat flux on the bumper limiters during typical operation in Tore Supra are also presented.
Date: July 1995
Creator: Carter, M. D.; Wang, C. Y. & Hogan, J. T.
Partner: UNT Libraries Government Documents Department

Three-dimensional antenna coupling to core plasma in fusion devices

Description: A complete understanding of the RF physics from the launcher to the plasma core is required to fully analyze RF experiments and to evaluate the performance of RF antenna designs in ITER. This understanding requires a consistent model for the RF power launching system, propagation and absorption through the edge region, and the response of the core plasma to the RF power. As a first step toward such a model, the three-dimensional (3D) antenna modeling code, RANT3D, has been coupled with the reduced order full wave code, PICES. Preliminary results from this model are presented in this paper for parameters similar to those found in the DIII-D experiment.
Date: September 1, 1995
Creator: Carter, M.D.; Jaeger, E.F.; Stallings, D.C.; Galambos, J.D.; Batchelor, D.B. & Wang, C.Y.
Partner: UNT Libraries Government Documents Department