ELECTRON PROBE MICROANALYSIS IN THE STUDY OF FISSION GAS RELEASE
This extended abstract describes the results of a number of electron microprobe investigations on transient tested fuel from the First Risoe Fission Gas Project. The work focused on three points. (i) The level of the gas release in the base irradiation. (ii) The effects of the transient terminal power and transient duration on the level of the gas release. (iii) The behaviour of caesium during a power transient. It was found that above about 300 Wcm**-1, the fractional gas release increased with the power at the transient terminal level (TTL). The interlinkage of gas bubbles on grain boundaries determined the magnitude of release. At TTLs in the range 300-420 Wcm**-1, increasing the hold time from 24 to 72 h did not significantly increase the level of gas release. Under the transient conditions investigated, the cross-sectional release values for xenon and caesium were almost the same. No caesium release occurred in the outer region of the fuel, whereas in the central region the released level exceeded 90 %. At all radial positions the Xe to Cs ratio was close to 1.8 and therefore corresponded to the ratio of the fission yields. In addition to radial variations in the concentrations of retained xenon and caesium, axial variations within a pellet were observed for the first time. It was established that in dished UO-2 pellets the release levels for xenon and caesium can be appreciably lower at the pellet ends.
Bibliographic Reference: ANS. WINTER MEETING LOS ANGELES, CA. (USA) NOV. 10-14 1985 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 32186 ORA
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Record Number: 1989123062300 / Last updated on: 1987-01-01
Available languages: en