Grain growth in thoria and thoria-base fuel pellets (LWBR development program)

Technical Report · Thu Jan 01 04:00:00 EST 1976

DOI:https://doi.org/10.2172/7296702· OSTI ID:7296702

Smid, R. J.

The kinetics of grain growth in ThO/sub 2/-base sintered compacts were investigated to determine the cause of a nonuniform microstructural cross section. It was concluded that trace impurities which inhibit continuous grain growth at the pellet interior were removed by vaporization at the pellet exterior. This resulted in relatively normal grain growth at the pellet surface and discontinuous grain growth at the pellet interior. Calcining the starting ThO/sub 2/ powder to a slightly higher temperature removed inhibiting impurities but also decreased the driving force for grain growth by reducing the surface area of the powder. Mixing high and low temperature calcined ThO/sub 2/ resulted in improved grain growth. Increased oxygen partial pressure and temperature during sintering increased grain boundary mobility in spite of the inhibiting impurity. The specific inhibiting impurity was not isolated during this investigation.

• Research Organization: Bettis Atomic Power Lab., West Mifflin, Pa. (USA)
• DOE Contract Number: EY-76-C-11-0014
• OSTI ID: 7296702
• Report Number(s): WAPD-TM-1311
• Country of Publication: United States
• Language: English

Related Subjects

050700* -- Nuclear Fuels-- Fuels Production & Properties
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ACTINIDE COMPOUNDS
BREEDER REACTORS
CALCINATION
CHALCOGENIDES
CHEMICAL REACTIONS
COMPACTS
CRYSTAL STRUCTURE
DECOMPOSITION
FABRICATION
FUEL PELLETS
GRAIN GROWTH
IMPURITIES
LWBR TYPE REACTORS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PELLETS
POWDERS
PYROLYSIS
REACTORS
SINTERING
THERMAL REACTORS
THORIUM COMPOUNDS
THORIUM OXIDES
WATER COOLED REACTORS
WATER MODERATED REACTORS