The Fission Cross Sections of Uranium-234 and Uranium-236 Relative to Uranium-235

Fission cross-section ratio measurements were made in the 2- to 3-MeV region using 235U samples with 234U and 236U samples containing ∼10% 235U. Atom ratios were obtained from measured thermal fission ratios and the isotopic analysis and also by alpha counting. Shape measurements were made from threshold to 10 MeV using pure samples and were normalized in the 2- to 3-MeV region. The present values for the 234U: 235U ratio are up to 5% greater than those previously reported. The results for 236U generally agree with those in the literature except for the values reported by Stein et al., which are also lower.