THE FABRICATION AND PROPERTIES OF URANIUM DIOXIDE FUEL
The decision was made to use uranium dioxide as the fuel core for the Canadian heavy-water-cooled Nuclear Power Demonstration reactor. Since a high mass ratio of fuel to sheath was required in order to minimize sheathing cost, research and development were directed to the fabrication of uranium dioxide fuel elements up to 2.5 cm diameter. In addition, a high fuel density was required to produce a high thermal conductivity and to aid in the retention of fission- product gases by the fuel. Uranium dioxide samples prepared by different chemical routes and fabricated under identical conditions have densities ranging from 71 to 98% of theoretical. The fabrication of uranium dioxide bodies by cold pressing followed by sintering in hydrogen was developed to a commercial scale. Densities of 93 to 96% of theoretical are achieved by cold pressing uranium dioxide powder at 3 tons/cm/sup 2/ followed by sintering for 1 hour at 1600 deg C in hydrogen. The use of neutral and oxidizing atmospheres during the sintering of uranium dioxide was investigated to evolve a more economical fabrication cycle. Relative densities up to 98% were achieved by sintering in a steam atmosphere at 1400 deg C. The effect of additives on the sinterability of uranium dioxide bodies was also investigated. Marked increases in sintered density were noted for small additions of titanium dioxide, vanadium pentoxide, and niobium pentoxide. Conversely, carbon additions have a deleterious effect on the sinterability of uranium dioxide. Integral fabrication of fuel elements by cold swaging uranium dioxide powder inside Zircaloy tubing to densities of up to 95% of theoretical was demonstrated. The relation of swaged density to tap density and particle density of the uranium dioxide as well as to the section reduction in swaging and the mcchanical properties of the sheathing material are being determined. (auth)
- Research Organization:
- Atomic Energy of Canada Ltd., Chalk River, Ont.; Dept. of Mines and Technical Surveys, Can.; Canadian Westinghouse Co., Ltd., Hamilton, Ont.
- NSA Number:
- NSA-13-006776
- OSTI ID:
- 4287222
- Report Number(s):
- A/CONF.15/P/192; AECL-602
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
CARBON
COLD WORKING
COMPACTING
DENSITY
ECONOMICS
EXTRUSION
FABRICATION
FISSION PRODUCTS
FUEL ELEMENTS
FUELS
HEAVY WATER COOLANT
HIGH TEMPERATURE
HYDROGEN
INERT GASES
MECHANICAL PROPERTIES
METALLURGY AND CERAMICS
NIOBIUM OXIDES
OXYGEN
REACTOR CORE
SAMPLING
SINTERING
STEAM
SWAGING
THERMAL CONDUCTIVITY
TITANIUM OXIDES
TRACE AMOUNTS
TUBES
URANIUM DIOXIDE
VANADIUM OXIDES
ZIRCALOY