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Title: Computer modeling of single-cell and multicell thermionic fuel elements

Abstract

Modeling efforts are undertaken to perform coupled thermal-hydraulic and thermionic analysis for both single-cell and multicell thermionic fuel elements (TFE). The analysis--and the resulting MCTFE computer code (multicell thermionic fuel element)--is a steady-state finite volume model specifically designed to analyze cylindrical TFEs. It employs an interactive successive overrelaxation solution technique to solve for the temperatures throughout the TFE and a coupled thermionic routine to determine the total TFE performance. The calculated results include temperature distributions in all regions of the TFE, axial interelectrode voltages and current densities, and total TFE electrical output parameters including power, current, and voltage. MCTFE-generated results compare experimental data from the single-cell Topaz-II-type TFE and multicell data from the General Atomics 3H5 TFE to benchmark the accuracy of the code methods.

Authors:
;  [1]
  1. Oregon State Univ., Corvallis, OR (United States). Dept. of Nuclear Engineering
Publication Date:
OSTI Identifier:
248112
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nuclear Technology; Journal Volume: 114; Journal Issue: 2; Other Information: PBD: May 1996
Country of Publication:
United States
Language:
English
Subject:
21 NUCLEAR POWER REACTORS AND ASSOCIATED PLANTS; SPACE POWER REACTORS; THERMIONIC FUEL ELEMENTS; COMPUTERIZED SIMULATION; TOPAZ REACTOR; HEAT TRANSFER; HYDRAULICS; M CODES; COMPARATIVE EVALUATIONS; THEORETICAL DATA; NESDPS Office of Nuclear Energy Space and Defense Power Systems

Citation Formats

Dickinson, J.W., and Klein, A.C.. Computer modeling of single-cell and multicell thermionic fuel elements. United States: N. p., 1996. Web.
Dickinson, J.W., & Klein, A.C.. Computer modeling of single-cell and multicell thermionic fuel elements. United States.
Dickinson, J.W., and Klein, A.C.. Wed . "Computer modeling of single-cell and multicell thermionic fuel elements". United States. doi:.
@article{osti_248112,
title = {Computer modeling of single-cell and multicell thermionic fuel elements},
author = {Dickinson, J.W. and Klein, A.C.},
abstractNote = {Modeling efforts are undertaken to perform coupled thermal-hydraulic and thermionic analysis for both single-cell and multicell thermionic fuel elements (TFE). The analysis--and the resulting MCTFE computer code (multicell thermionic fuel element)--is a steady-state finite volume model specifically designed to analyze cylindrical TFEs. It employs an interactive successive overrelaxation solution technique to solve for the temperatures throughout the TFE and a coupled thermionic routine to determine the total TFE performance. The calculated results include temperature distributions in all regions of the TFE, axial interelectrode voltages and current densities, and total TFE electrical output parameters including power, current, and voltage. MCTFE-generated results compare experimental data from the single-cell Topaz-II-type TFE and multicell data from the General Atomics 3H5 TFE to benchmark the accuracy of the code methods.},
doi = {},
journal = {Nuclear Technology},
number = 2,
volume = 114,
place = {United States},
year = {Wed May 01 00:00:00 EDT 1996},
month = {Wed May 01 00:00:00 EDT 1996}
}
  • A two-dimensional transient model is developed to simulate steady-state and transient operations of single-cell thermionic fuel elements (TFEs). Model predictions are in good agreement with published data to within 4.5 and 5.5% for fission and electrically heated TFEs of the TOPAZ-II type, respectively. In addition, the results of a transient analysis simulating the startup of an electrically heated TFE, following a step function increase in thermal power, are in presented and discussed.
  • This paper investigated the accuracy of simulating fission heated single-cell Thermionic Fuel Elements (TFEs) using uniform electric heating in the presence of oxygen in the interelectrode gap. The electrodes temperatures current densities, and the tungsten loss rates from the emitter surface were calculated and compared for both heating options. The effect of oxygen presence in the interelectrode gap on the TFE performance was also compared for fission and electrically heating TFE. Electrical heating results in a more uniform axial distributions of emitter temperature, current density, and tungsten loss rate distributions in the central part of the TFE compared to fissionmore » heating. Results show that introducing oxygen into the interelectrode gap reduces the output electric power for both fission and electrically heated TFEs. For example, at an effective oxygen pressure of 5{times}10{sup {minus}9}torr and O/W atom ratio in the tungsten oxides deposits on the collector surface of 0.66, the electric power output at Q{sub th}=3500W{sub th} was about 38W{sub e} less than in the absence of oxygen, for both electrically and fission heated TFEs. {copyright} {ital 1997 American Institute of Physics.}« less
  • This paper investigated the accuracy of simulating fission heated single-cell Thermionic Fuel Elements (TFEs) using uniform electric heating in the presence of oxygen in the interelectrode gap. The electrodes temperatures current densities, and the tungsten loss rates from the emitter surface were calculated and compared for both heating options. The effect of oxygen presence in the interelectrode gap on the TFE performance was also compared for fission and electrically heating TFE. Electrical heating results in a more uniform axial distributions of emitter temperature, current density, and tungsten loss rate distributions in the central part of the TFE compared to fissionmore » heating. Results show that introducing oxygen into the interelectrode gap reduces the output electric power for both fission and electrically heated TFEs. For example, at an effective oxygen pressure of 5x10{sup -9} torr and O/W atom ratio in the tungsten oxides deposits on the collector surface of 0.66, the electric power output at Q{sub th}=3500 W{sub th} was about 38 W{sub e} less than in the absence of oxygen, for both electrically and fission heated TFEs.« less
  • This paper addresses the conceptual design of a Russian thermionic fuel element (TFE) in support of the S-PRIME 40 kWe in-core thermionic space power reactor studies sponsored by the U.S. Department of Energy TI-SNPS program. The design responds to requirements specified by the U.S. component of the S-PRIME team and is based on the multicell ``flashlight`` TFE approach. Following a general description of the TFE design, the considerations leading to several key design decisions are discussed. These include nuclear and thermionic performance, cesium management, fission product management, materials selection, fuel system, and lifetime. {copyright}American Institute of Physics 1995
  • The paper discusses principle of operation and applications of a pulse method of heating multi-cell thermionic fuel elements. Some experimental results are given for a cylindrical single-cell thermionic energy converter that simulates conditions close to that of multi-cell TFE operation. Basic requirements for technical parameters are stated that should be observed when testing TFE on thermal facilities. The means to improve the method are described, including both a computer-aided experiment and modifications in individual components of the test facility. {copyright} {ital 1996 American Institute of Physics.}