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Title: PYROLYTIC-CARBON-COATED CARBIDE FUEL PARTICLES AND THEIR USE IN GRAPHITE- MATRIX FUEL COMPACTS

Abstract

A summary of the development and evaluation of pyrolytic-carbon-coated carbide fuel particles and graphitematrix fuel compacts is presented. A process that was developed for the preparation of particles of thorium-uranium dicarbide is described. Granulated particles composed of powdered UO/sub 2/, ThO/sub 2/, and carbon are suspended in a bed of graphite flour and heated to convert the oxides to dicarbides. The particles are then melted to densify and spheroidize them, while the graphite flour keeps them separated so they will not flow together. Coating the (Th, U)C/sub 2/ particles with pyrolytic carbon is accomplished in a fluidizedbed apparatus using a methane--helium mixture at a temperature of approximates 1400 deg C. Data are presented on the properties of coatings deposited at temperatures to 2400 deg C. Graphitematrix fuel compacts of high density are prepared by a hotpressing process. Graphfte flour is used as the filler and pitch as the binder; the use of graphite flour, rather than coke, permtts the attainment of good thermal properties In the compacts wtthout the necessity for high processing temperatures. The hot-pressing process is described and the properties of the compacts are given. The thermal stability of coated fuel particles was evaluated at temperatures to 2000more » deg C and for times up to one year. Some coated particles were found to fail in thermal gradient tests because of the movement of the particle through the coating on the high- temperature side; this was named the amoeba effect.'' Tests of coated particles show that there should be no thermal instability at temperatures up to 1500 deg C for periods of at least three years. Results of extensive irradiation tests of graphite-matrix fuel compacts prepared by the hot-pressing process are presented. The compacts containing uncoated (Th, U)C/sub 2/ particles were dimensionally stable after burnups of 6.9 x 10/sup 19/ fissions/cm/sup 3/ at 1100 to 1500 deg C. Compacts cortaining coated particles were tested to burnups of 1.2 x 10/sup 20/ fissions/cm/sup 3/ at temperatures as high as 2000 deg C. A few per cent of the particle coatings were found to be broken after these tests. Possible explanations for these failures are presented. (auth)« less

Authors:
Publication Date:
Research Org.:
General Atomic Div., General Dynamics Corp., San Diego, Calif.
OSTI Identifier:
4769881
Report Number(s):
GA-3588
NSA Number:
NSA-17-001929
DOE Contract Number:  
AT(04-3)-314
Resource Type:
Technical Report
Resource Relation:
Other Information: Orig. Receipt Date: 31-DEC-63
Country of Publication:
United States
Language:
English
Subject:
METALS, CERAMICS, AND OTHER MATERIALS; AMOEBA; BURNUP; CARBIDES; CARBON; CEMENTS; COATING; COMPACTING; DENSITY; FAILURES; FISSION; FUELS; GRAPHITE; HEATING; HELIUM; HIGH TEMPERATURE; HOT WORKING; IRRADIATION; LABORATORY EQUIPMENT; MATERIALS TESTING; MECHANICAL PROPERTIES; MELTING; METHANE; MICROORGANISMS; POWDERS; PREPARATION; PYROLYSIS; SOLUTIONS; SPHERES; STABILITY; TENSILE PROPERTIES; THERMODYNAMICS; THORIUM ALLOYS; URANIUM CARBIDES; USES

Citation Formats

Goeddel, W.V. ed. PYROLYTIC-CARBON-COATED CARBIDE FUEL PARTICLES AND THEIR USE IN GRAPHITE- MATRIX FUEL COMPACTS. United States: N. p., 1962. Web.
Goeddel, W.V. ed. PYROLYTIC-CARBON-COATED CARBIDE FUEL PARTICLES AND THEIR USE IN GRAPHITE- MATRIX FUEL COMPACTS. United States.
Goeddel, W.V. ed. Tue . "PYROLYTIC-CARBON-COATED CARBIDE FUEL PARTICLES AND THEIR USE IN GRAPHITE- MATRIX FUEL COMPACTS". United States.
@article{osti_4769881,
title = {PYROLYTIC-CARBON-COATED CARBIDE FUEL PARTICLES AND THEIR USE IN GRAPHITE- MATRIX FUEL COMPACTS},
author = {Goeddel, W.V. ed.},
abstractNote = {A summary of the development and evaluation of pyrolytic-carbon-coated carbide fuel particles and graphitematrix fuel compacts is presented. A process that was developed for the preparation of particles of thorium-uranium dicarbide is described. Granulated particles composed of powdered UO/sub 2/, ThO/sub 2/, and carbon are suspended in a bed of graphite flour and heated to convert the oxides to dicarbides. The particles are then melted to densify and spheroidize them, while the graphite flour keeps them separated so they will not flow together. Coating the (Th, U)C/sub 2/ particles with pyrolytic carbon is accomplished in a fluidizedbed apparatus using a methane--helium mixture at a temperature of approximates 1400 deg C. Data are presented on the properties of coatings deposited at temperatures to 2400 deg C. Graphitematrix fuel compacts of high density are prepared by a hotpressing process. Graphfte flour is used as the filler and pitch as the binder; the use of graphite flour, rather than coke, permtts the attainment of good thermal properties In the compacts wtthout the necessity for high processing temperatures. The hot-pressing process is described and the properties of the compacts are given. The thermal stability of coated fuel particles was evaluated at temperatures to 2000 deg C and for times up to one year. Some coated particles were found to fail in thermal gradient tests because of the movement of the particle through the coating on the high- temperature side; this was named the amoeba effect.'' Tests of coated particles show that there should be no thermal instability at temperatures up to 1500 deg C for periods of at least three years. Results of extensive irradiation tests of graphite-matrix fuel compacts prepared by the hot-pressing process are presented. The compacts containing uncoated (Th, U)C/sub 2/ particles were dimensionally stable after burnups of 6.9 x 10/sup 19/ fissions/cm/sup 3/ at 1100 to 1500 deg C. Compacts cortaining coated particles were tested to burnups of 1.2 x 10/sup 20/ fissions/cm/sup 3/ at temperatures as high as 2000 deg C. A few per cent of the particle coatings were found to be broken after these tests. Possible explanations for these failures are presented. (auth)},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1962},
month = {10}
}

Technical Report:
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