Independent Yields of Mass-135 Xenons in the Thermal Neutron Fission of 233U, 235U,239Pu, and 241Pu

Abstract

The ratio of the independent yield of 135Xe to the cumulative chain yield of 135I in thermal neutron fission of 233U, 235U, 239Pu, and 241Pu has been measured using radiochemical techniques. 135Xe and 135Xem were recovered quantitatively after short irradiations and compared with 135Xe grown from 135I in the same sample. Corrections were applied for interference from other fission-product gases in the NaI(Tl) γ-ray spectrometry of the rare gas fractions. If the independent yield for 135Xem is assumed to be zero, the ratio of the independent yield of 135Xe to the cumulative chain yield to 135I is found to be 0.2790 ± 0.0069 for 233U, 0.0357 ± 0.0019 for 235U, 0.1782 ± 0.0023 for 239Pu, and 0.0332 ± 0.0016 for 241Pu.The ratio of the cumulative chain yield to 135I for thermal fission of 239Pu to that for 241Pu was found to be 0.966 ± 0.054.