Systematic Analysis of Uranium Isotopes

We describe recent nuclear model calculations and evaluations of neutron reactions on the uranium isotopes 232–241U in the keV to 30‐MeV energy range. This work makes use of extensive sets of measurements for fission, elastic, inelastic, (n,xn) and capture, as well as fission probability data. The 235U(n.f) standard cross section was revised, and the fission cross sections of the uranium isotopes, as well as 237Np and 239Pu, were updated using the revised standard. Nuclear reaction model calculations were performed for the whole suite of uranium isotopes to allow us to take advantage of the systematical properties from isotope‐to‐isotope, which is especially useful for nuclides where few measurements exist. In addition to improving the neutron cross sections and energy‐angle distributions, new prompt fission neutron spectra and prompt/delayed neutron multiplicity evaluations are included for several isotopes. These evaluations are among the pre‐ENDF/B‐VII evaluations that are currently being considered fo...