(235)U(n, f), ^(233)U(n, f) and ^(239)Pu(n, f) Prompt Fission Neutron Spectra

New prompt fission neutron spectra (PFNS) matrices for the n+^(235)U, n+^(233)U, and n+^(239)Pu systems are prepared. Present and previous PFNS shapes are drastically different from each other, the former being consistent with measured data base. A combined generalized least-squares fit of n_(th)+^(235)U, n_(th)+^(233)U, n_(th)+^(239)Pu, and ^(252)Cf(sf) measured data base is accomplished. The solution of the longstanding problem of inconsistency of ^(235)U integral data testing and differential prompt fission neutron spectra data (PFNS) is proposed. Similar problems for the n+^(233)U and n+^(239)Pu are envisaged, revealing arbitrary tweaking of relevant neutron cross sections. Fast ^(235)U integral critical assemblies like Godiva or Flattop benchmarks are reproduced with the same accuracy as with the PFNS of the major data libraries. That reveals a rather delicate compensation effect, tracking the success of the distorted PFNS of the major data libraries to the excessive number of neutrons at energies of 1-3 MeV. Thermal assembly benchmarking reveals positive biases in k_(eff), which might be attributed to the in fluence of a soft energy tail of the present PFNS. For some of Valduc's LCT benchmarks biases in k_(eff) are less than 20 pcm. Fast ^(239)Pu integral critical experiments like Jezebel reveal the in fluence of overestimated inelastic scattering for ^(239)Pu, arbitrarily introduced previously to diminish the in fluence on the k_(eff) of the distortion of the PFNS. KCI Citation Count: 0