The release of radioactive gases from uranium dioxide during irradiation

The steady-state release of radioactive rare gases has been measured during the isothermal irradiation of small-grained, largegrained and single-crystal UO₂. The experiment showed that (a) gases with half-lives less than five days exhibit no indication of enhanced grain-boundary diffusion; (b) the rate of release is a complex function of rating, but within the range of the experiment, the release rate was independent of rating; (c) the release kinetics for each gas are unique with no common relationship between fractional release and the gas decay constant; (d) the results show that the diffusion coefficient of xenon is ten times that for krypton at a temperature of 1450°C.