THE FISSION YIELDS OF ISOTOPES OF XENON AND KRYPTON IN THE NEUTRON FISSION OF U236 AND U238

Abstract

Several uranium samples have been irradiated under various conditions in the Chalk River N.R.X. reactor and in the Los Alamos fast reactor. The fission gases, xenon and krypton, have been extracted from the irradiated material and the relative isotopic abundances determined mass spectrometrically. Fine structure in the mass – fission yield curve has been found in both the xenon and krypton mass ranges for U235 + n and U238 + n fission. It is observed that this fine structure shifts to lower masses, as predicted, for neutron fission of U238. The proportions of U235 and U238 fission that have occurred in the irradiated samples have been estimated from the percentage change in fine structure.