HOW LOCAL MEASUREMENTS INCREASE OUR UNDERSTANDING OF FISSION PRODUCT RELEASE
Results from several electron microprobe investigations of transient tested fuel are reviewed. Following a description of the radial and axial distributions of xenon in dished pellets, diffusion data derived from microprobe measurements in single grains of UO-2 are reported. At intermediate radial positions, the xenon and caesium profiles within the grains usually conform to a parabola. The effective diffusion coefficients for xenon and caesium varied between 10**- 15-cm**2s**-1 and 10**-12cm**2s**-1 depending on the radial position of the grain. Data from X-ray fluorescence analysis are also presented. This technique is being used in conjunction with microprobe analysis to obtain information about gas retention at grain boundaries. First results indicate that in transient tested fuel not all the grain boundary bubbles are vented at intermediate radial positions. Evidence for the accumulation of gas at boundaries in the outer region of the fuel between r/r-o = 0.6 and 0.75 was not found. Finally, the behaviour of caesium and xenon under transient conditions is compared. The radial and axial distributions of these two fission products were in most cases similar even though clear differences in diffusion rates were observed.
Bibliographic Reference: IAEA TECHNICAL COMMITTEE MEETING ON FUEL ROD INTERNAL CHEMISTRY AND FISSION PRODUCT BEHAVIOUR, KARLSRUHE (GERMANY, NOV. 11-15, 1985 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 32516 ORA
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Record Number: 1989124071500 / Last updated on: 1987-01-01
Available languages: en