Cumulative fission yield measurements with 14.7 MeV neutrons on U-238*

The fission yield data in the 14 MeV energy neutron induced fission of U-238 play an important role in decay heat calculations and generation-IV reactor designs. In order to accurately measure fission product yields (FPYs) of U-238 induced by 14 MeV neutrons, the cumulative yields of fission products ranging from Sr-92 to Nd-147 in the U-238(n, f) reaction with a 14.7 MeV neutron were determined using an off-line gamma-ray spectrometric technique. The 14.7 MeV quasi-monoenergetic neutron beam was provided by the K-400 D-T neutron generator at China Academy of Engineering Physics (CAEP). Fission products were measured by a low background high purity germanium gamma spectrometer. The neutron flux was obtained from the Nb-93 (n, 2n)Nb-92m reaction, and the mean neutron energy was calculated using the cross-section ratios for the Zr-90(n, 2n)Zr-89 and Nb-93(n, 2n)Nb-92m reactions. With a series of corrections, high precision cumulative yields of 20 fission products were obtained. Our FPYs for the U-238(n, f) reaction at 14.7 MeV were compared with the existing experimental nuclear reaction data and evaluated nuclear data, respectively. The results will be helpful in the design of a generation-IV reactor and the construction of evaluated fission yield databases.