Corrosion-resistant coatings for beryllium oxide fuel elements (Project Pluto)
Declassified 26 Nov 1973. Coatings were studied as a means of reducing the water vapor corrosion of BeO fuel elements for an air-breathing ramjet reactor (Pluto). The fuel elements are BeO containing fuel as a secondphase solid solution of 1.06 UO/sub 2/: 1.00 Y/sub 2/O/sub 3/: 1.00 ZrO/sub 2/ ( mole ratios). Various potential coating materials were prepared and evaluated and different coating application techniques were used. The most consistent and successful coating was ZrO/sub 2/ stabilized with 15 wt% Y/sub 2/O/sub 3/, although this coating crazed because its thermal expansion exceeds that of BeO. Corrosion rates were shown to increase with increasing humidity and velocity, and so testing at-high velocity was necessary. An analytical model of the coated tube helped to correlate corrosion tests at various conditions. Several mechanisms of loss from coated tubes were considered. Corrosion rates of coated tubes at 165O deg C were measured in air containing 10 to 12 wt% water at reactor- like velocities (100,000 Reynolds number). Extrapolation of this and other data to a realistic reactor ambient humidity of 1 wt% gave losses near 0.1 mg/cm/sup 2/ -hour, or 0.00017 inch in 10 hours, which are considered satisfactorily low. The coating also reduced UO/sub 2/ loss to undetectable levels. The corrosion rates of uncoated BeO were also measured, and were slightly higher than but consistent with calculated predictions. (auth)
- Research Organization:
- California Univ., Livermore (USA). Lawrence Livermore Lab.
- DOE Contract Number:
- W-7405-ENG-48
- NSA Number:
- NSA-29-018809
- OSTI ID:
- 4341476
- Report Number(s):
- UCRL-14143
- Resource Relation:
- Other Information: Declassified 26 Nov 1973. Orig. Receipt Date: 30-JUN-74
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Ceramics
& Other Materials-Ceramics & Cermets-Corrosion & Erosion & Surface Phenomena
N79300 -Reactors-Reactor Fuels
N77800 -Reactors-Space
Mobile
Propulsion
Transportation & Package Reactors
*BERYLLIUM OXIDES- CORROSION PROTECTION
*PROPULSION REACTORS- FUEL ELEMENTS
*URANIUM DIOXIDE- CORROSION PROTECTION
*YTTRIUM OXIDES- PROTECTIVE COATINGS
*ZIRCONIUM OXIDES- PROTECTIVE COATINGS
AIR
RAMJET ENGINES
VELOCITY
WATER VAPOR