With a view to reassessing the currently established neutron cross sections for Fe,
Ni and Cr, which are the main constituent elements of stainless steel, electron linac time-of-flight experiments were conducted to determine the energy spectra of neutrons in sample piles of the respective elements, in the energy range covering 10
010
3keV levels.
The spherical symmetry of neutron distribution in the piles was verified by determining through specimen activation the spatial distribution of neutrons in several radial directions around the target.
The neutron spectra thus determined experimentally were compared with theoretical values derived by one-dimensional transport calculation using data contained in JENDL-2
and ENDF/B-IV. The resulting findings are as follows: (1) Both files call for revising the resonance parameters of Fe and Ni in the energy range below 100 keV. (2) For Fe,
ENDF/B-IV requires supplementation in the range below 840 keV with additional cross section data on inelastic scattering. (3) For Cr, both files need reevaluation of the total cross section, notably in the energy range of 48 keV characterized by a series of large resonances. A neutron transmission measurement, performed additionally, proved the total cross section for Cr to be 30 to 40% higher than derived from JENDL-2 and from ENDF/B-IV.
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