Benchmark tests of principal fissile nuclide data in jendl-3 with simple fast critical assemblies

A series of benchmark tests was made to check the neutron nuclear data of main fissile nuclides (²³⁹Pu, ²³⁶U and ²³³U) of JENDL-3 for fast reactors. A total of nine critical assemblies were analyzed. They are assemblies of single material, high enrichment and simple geometry with small volume and therefore suitable for nuclear data testing. Criticality calculation was made by ANISN with S₁₆P₅ using the VITAMIN-J 175-energy-group. Discussions are made on ken, spectral indices at core center and leakage spectra. From the study, a problem was pointed out relating to the interpolation of secondary-neutron energy distributions for threshold reactions near the threshold energy point adopted in the original JENDL-3 and its remedy was proposed. By the benchmark tests of thus revised JENDL-3 (JENDL-3.1), it was shown that integral experiments for ²³⁹Pu and ²³⁵U cores were reproduced quite satisfactorily. On the contrary, it was revealed that large deviations for ²³³U cores from the experiment were due to uncertainties of the fission spectrum and the inelastic scattering cross sections, In the present work, sensitivity of “a” parameter (level density parameter) of Madland-Nix's fission spectrum formula to the integral data was extensively studied. Some recommendations are made to improve JENDL-3.1.