Neutron–nuclear data benchmark for copper and tungsten by slab assembly transmission experiments with DT neutrons

Fusion integral benchmark experiments have been carried out for copper and tungsten at FNS of JAERI. Leakage neutron spectra were measured with an NE213 detector by the TOF method to validate evaluated nuclear data files of JENDL-3.2, JENDL-fusion file, ENDF/B-VI, FENDL/E-1.0 and FENDL/E-2.0. From the result of comparison between experiments and calculations by MCNP-4B, below 1 MeV disagreement was observed for copper and it became remarkable with increase of the thickness. It was therefore, pointed out that there might be a problem in the evaluated (n, 2n) neutron spectrum for all the nuclear data libraries. For tungsten, the calculated result with JENDL-fusion file and FENDL/E-2.0 overpredicted the experimental values around 3–7 MeV. Near 10 MeV, underestimation of ENDF/B-VI was remarkably pronounced. For the whole energy range, JENDL-3.2 was preferable. However, there was a serious problem left that discrepancy between JENDL-fusion file and JENDL-3.2 was very large.