Transmission measurements of ⁶¹Ni in the energy range from 40 eV up to 100 keV

The importance of the structure material cross sections in nuclear technology is due to the fact that about 20 - 25% of a large fast power reactor volume is allocated to stainless steel with typical composition: 60 - 70% Fe; 18 - 20% Cr; 10 -13% Ni; 2% Mo, Mn. These materials influence: - core neutronics; - neutron transport and shielding; - gamma decay heating; - activation and corrosion. The most stringent requirement on the accuracy comes from the neutron balance which is, up to about 0.5 MeV, mainly affected by the radiative capture of neutrons. The commonly accepted goals for the design accuracy in the k_eff and in the breeding gain lead to a request of the capture cross section uncertainty of 5 - 10% for Fe, Cr, Ni and 10% for Mo and Mn.