INTERDIFFUSION BETWEEN URANIUM-BEARING REACTOR FUELS AND REFRACTORY-METAL THERMIONIC EMITTERS

Journal Article · Tue Jan 01 04:00:00 EST 1963 · Advanced Energy Conversion

DOI:https://doi.org/10.1016/0365-1789(63)90080-8· OSTI ID:4687229

Weinberg, A F; Yang, L

Material compatibility as related to the marriage'' of reactor fuels to refractory metal thermionic emitters is under investigation. Four fuel materials, UC, UC/sub 2/, UCZrC, and UO/sub 2/, are studied in combination with W, Mo, Ta, and Nb over the temperature range 1200 to 2000 deg C. A technique was developed for simultaneously studying the interdiifusion between a gtven uranium- bearing material and each of the four refractory metals. UC in contact with Nb and Ta at 1875 deg plus or minus 20 deg C and 1925 plus or minus 30 deg C, respectively, reacted to form a liquld phase identified as almost pure uranium metal. Mo also reacted with UC at 1800 plus or minus 20 deg C, while at the same temperature W appeared relatively unaffected. However, after being contacted with UC at 2000 deg plus or minus 20 deg C for 30 hr, W exhibited a mild reaction. The reaction mechanism for all of these metals appears to be UC + M = MC + U. Formation of this liquid phase was suppressed at 1800 deg C when UC- UC/sub 2/ mixtures were substituted for the UC. The kinetics of uniform metal carbide layer formation were studied for UC-UC/sub 2/ mixtures in contact with the four refractory metals at 1800 deg C. In addition to the uniform carbide layers formed, severe carbide penetration of the grain boundaries was observed in Nb, Ta, and Mo. Investigation of the interaction between UZrC (6.0 mole% U; 45.8 mole% Zr; 48.2 mole% C) and the same four refractory metals at 1800 deg C for 50 hr showed that the stabilization of the carbide phase by the addition of Zr dramatically improves the diffusion characteristics. Electron micro-probe analyses of these diffusion couples were made and the results are discussed. Preliminary investigations of UO/sub 2/-refractory metal compatibility were completed for three temperatures: 1200, 1800, and 2000 deg C. Indications of transport of one or more of the fuel components through grain boundaries were observed. (auth)

• Research Organization: General Atomic Div., General Dynamics Corp., San Diego, Calif.
• NSA Number: NSA-17-027961
• OSTI ID: 4687229
• Journal Information: Advanced Energy Conversion, Journal Name: Advanced Energy Conversion Vol. Vol: 3
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

CARBIDES
CHEMICAL REACTIONS
DIFFUSION
EMISSION
FUELS
GRAIN BOUNDARIES
HIGH TEMPERATURE
INTERACTIONS
LAYERS
LIQUIDS
METALS
MIXING
MOLYBDENUM
NIOBIUM
PHYSICS
REACTORS
REFRACTORIES
STABILITY
TANTALUM
TEMPERATURE
THERMIONICS
TRANSPORT
TUNGSTEN
URANIUM
URANIUM CARBIDES
URANIUM DIOXIDE
ZIRCONIUM CARBIDES