THE YIELDS OF 129I IN NATURAL AND IN NEUTRON-INDUCED FISSION OF URANIUM

Measurements have been made, by a radioactivation technique, of the 129I formed in uranium by pile-neutron-induced fission, and in pitchblende by the natural fission of uranium. The amount found in the pile-neutron-irradiated uranium corresponds to a fission yield of 0.90% at mass 129. The natural production of 129I in pitchblende is discussed in the light of the mass-spectrometric measurements of spontaneous fission xenon made by Thode and his collaborators. An upper limit of 1 part in 108 can be set for the occurrence of 129I in natural iodine. The pile neutron capture cross section of 129I has been measured as 35 barns.