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Sphere-cal process: fabrication of fuel pellets from gel microspheres

Technical Report ·
DOI:https://doi.org/10.2172/5929983· OSTI ID:5929983
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The sphere-cal process uses gel-derived microspheres as feed material for fuel pellet fabrication. The basic sphere-cal process consists of microsphere gelation, drying, and calcining followed by pellet pressing and sintering. Each of these process steps were studied to try to determine the important parameters for the production of high quality UO/sub 2/, ThO/sub 2/, and (Th,U)O/sub 2/ fuel pellets. UO/sub 2/ sintered pellet densities increase both with decreasing calcination temperature (1000 to 600/sup 0/C) and with decreasing forming pressure (414 to 138 MPa). Thermogravimetric analysis indicate that a minimum calcination temperature of 600/sup 0/C is necessary for complete reduction of the UO/sub 3/ gel microspheres to UO/sub 2/. Batch screening suggests that use of minimum gel aging, fine-sized microspheres (50 to 400 ..mu..m), and fast drying (warm air or oven) will produce the highest quality UO/sub 2/ pellets. Thoria and thoria-urania microspheres produced by internal gelation or by external gelation (KFA method) were hard and compacted poorly, resulting in pellets with a remnant sphere structure. However, thoria-urania microspheres produced by the SNAM external gelation process were softer, resulting in more homogeneous pellets.

Research Organization:
Oak Ridge National Lab., TN (USA)
DOE Contract Number:
W-7405-ENG-26
OSTI ID:
5929983
Report Number(s):
ORNL/TM-6906
Country of Publication:
United States
Language:
English

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Related Subjects

050700* -- Nuclear Fuels-- Fuels Production & Properties
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
36 MATERIALS SCIENCE
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
ACTINIDE COMPOUNDS
CALCINATION
CHALCOGENIDES
CHEMICAL REACTIONS
COLLOIDS
DECOMPOSITION
DISPERSIONS
DRYING
FABRICATION
FUEL PELLETS
GELATIN
MATERIALS WORKING
MICROSPHERES
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PELLETS
PRESSING
PROTEINS
PYROLYSIS
SINTERING
THERMOCHEMICAL PROCESSES
THORIUM COMPOUNDS
THORIUM OXIDES
URANIUM COMPOUNDS
URANIUM DIOXIDE
URANIUM OXIDES