Release of short-lived fission products from UO2 fuel: Effects of operating conditions

Under normal operating conditions, release of the short-lived xenons and kryptons was described by a lambda (decay constant)sup(-0.5) relationship, characteristic of diffusion; there was a strong temperature-dependence of release in the thermally-activated diffusion range. Release during shutdown and startup transients was dependent on prior operating temperature, while under oxidizing conditions enhancement of release up to a factor of 4.5 was observed. Under loss-of-coolant conditions, release was described by a lambda-1 relationship, characteristic of movement of stored inventory. Most release accompanied the re-wet portion of the transient, consistent with enhancement due to fuel cracking. No iodines exited from the fuel elements under normal, oxidizing or loss-of-coolant conditions. (orig./RK)