Cumulative fission yield measurements with 14.7 MeV neutrons on 238U

The fission yield data in the 14 MeV energy neutron induced fission of238U play an important role in decay heat calculations and generation-Ⅳ reactor designs.In order to accurately measure fission product yields(FPYs)of238U induced by 14 MeV neutrons,the cumulative yields of fission products ranging from92Sr to147Nd in the239U(n,f) reaction with a 14.7 MeV neutron were determined using an off-line γ-ray spectrometric technique.The14.7 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 the93Nb(n.2n)92mNb reaction,and the mean neutron energy was calculated using the cross-section ratios for the90Zr(n,2n)89Zr and93Nb(n,2n)92mNb reactions.With a series of corrections,high precision cumulative yields of 20 fission products were obtained.Our FPYs for the238U(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.