High precision measurements of spectrum averaged total neutron cross section for chromium

The intense neutron beams formed by composite neutron filters at reactor horizontal channels give the fluxes of about 10⁶ - 10⁸ neutron/cm²·s at the fixed neutron energies and it makes it possible to measure te neutron cross sections with accuracy better than 0.1%. The need of such measurements is formulated in the document The NEA High Priority Nuclear Data Request List, May 1998 (for Cr in the energy range 0.1 keV - 5 MeV and for Cr-52 in 10 eV - 20 MeV). Cr is one of the important structural materials for NPP and research reactors just as for fusion technology. These precise cross section data may be used also in the practice of work for evaluated nuclear data libraries. Now the discrepancies in total cross section for Cr in evaluated nuclear data libraries are in the range 3 - 50% for energies up to 200 keV. At Kyiv Research Reactor now we have the set of neutron filters for the fixed energies in the range 0 - 600 keV, here we present the transmission measurements at the energies 24.3 and 58.8 keV for Cr and Cr-52 (99.3% enrichment) samples. The results of measurements are presented together with the analysis of the known previous experimental data and the evaluated nuclear data from ENDF/B-VI, JEF-2.2 JENDL-3.2, BROND-2 and CENDL-2 libraries. (author)