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POSTIRRADIATION RELEASE OF Xe$sup 133$ FROM PYROLYTIC CARBON

Technical Report ·
OSTI ID:4693975
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>Postirradiation measurements were made at 700 to 1500NoneDNoneEC of the release of Xe/sup 133/ recoiled into pyrolytic carbon during neutron irradiation in contact with uranium or UO/sub 2/ powder. The time-dependent release from two types of pyrolytic carbon coatings, laminar and columnar, and from two crystallographic directions in a sample of pyrolytic graphite having a quite perfect crystal structure was studied. Below 1200 deg C, the release pattern from all specimens was identical: a high rate of loss of Xe/sup 133/ for several minutes followed by a slower release, which was maintained for over 5 hr of heating. The slower process gave an integral fractional release which was linear with the square root of the heating time. At 1200 deg C and above the initial rapid release persisted for longer times. The release from the laminar coatings was higher than from the other specimens. On the basis of a diffusion model, the apparent diffusion coefficients for the laminar coatings were 10/sup 2/ to 10/sup 3/ times higher than those for the columnar coatings, with activation energies of 33 and 17 kcal per mole for the laminar and columnar coatings, respectively. There appeared to be a structural dependence to the release from the more perfect specimen. The xenon release in the a'' direction occurred with a higher apparent diffusion coefficient and lower activation energy for temperatures up to 1200 deg C as compared to the release in the c'' direction. The activation energy for the release in a'' direction was 15 kcal per mole and the value in the c'' direction was 50 kcal per mole. (auth)
Research Organization:
Battelle Memorial Inst., Columbus, Ohio
DOE Contract Number:
W-7405-ENG-92
NSA Number:
NSA-17-029372
OSTI ID:
4693975
Report Number(s):
BMI-1634
Country of Publication:
United States
Language:
English

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Related Subjects

CARBON
COATING
CRYSTALLIZATION
CRYSTALS
DIFFUSION
EXCITATION
HEATING
HIGH TEMPERATURE
IRRADIATION
LATTICES
MEASURED VALUES
METALS, CERAMICS, AND OTHER MATERIALS
NEUTRON BEAMS
POWDERS
PYROLYSIS
RADIATION EFFECTS
URANIUM
URANIUM DIOXIDE
XENON 133