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Uranium diffusion in H-451 graphite

Journal Article · · Nucl. Technol.; (United States)
OSTI ID:5096930
The transport or diffusion of uranium (as a standin for plutonium) was investigated under conditions approximating those of the primary coolant loop in a high-temperature gas-cooled reactor. Profiles were obtained for uranium penetration in H-451 graphite at temperatures ranging from 900 to 1400/sup 0/C. Profile data for given temperatures were considered in terms of the following expression: (erf/sup -1/(1-C/C /SUB o/ ))/sup 2/=X/sup 2//4Dt, where C is the concentration of uranium at time t, for distance x, into the pellet; C /SUB o/ is a constant representing the uranium concentration at x = 0 for all t, and D is the diffusion coefficient. Diffusion coefficients for uranium initially present as dicarbide at 1000 and 1400/sup 0/C were found to be defined by Duc/sub 2/ = 3.5 X 10/sup -3/ exp(-4.8 X 10/sup 4//RT) cm/sup 2//s. For uranium initially present as dioxide at 900, 1000, and 1400/sup 0/C, diffusion coefficients are defined by Duo/sub 2/ = 2.34 X 10/sup -6/ exp(-3.2 X 10/sup 4//RT) cm/sup 2//s, where R is the gas constant and T is the temperature in degrees Kelvin.
Research Organization:
Oak Ridge National Laboratory, Chemical Technology Division, Oak Ridge, Tennessee
OSTI ID:
5096930
Journal Information:
Nucl. Technol.; (United States), Journal Name: Nucl. Technol.; (United States) Vol. 68:3; ISSN NUTYB
Country of Publication:
United States
Language:
English