Validation of the VITAMIN-B6 and BUGLE-96 cross-section libraries for moderate-energy neutron and photon transport calculations

Newly produced multigroup cross-section libraries require detailed testing to ensure that they are suitable for the applications intended. This requires that the libraries be tested against approved experimental benchmarks and/or well-posed calculational benchmarks. Following this tradition, the recently produced fine-group VITAMIN-B6 library and its derivative BUGLE-96 broad-group library have been tested against calculational and experimental benchmarks that are sensitive to neutrons with energies in the moderate-energy range (10.0 to 20.0 MeV). Iron is prominent in each benchmark as it is in many shielding configurations, and iron cross-section data have posed significant problems in many shielding designs. These benchmarks provide stringent tests for the iron cross sections. Calculated results obtained using the new libraries were compared to measured results or results from other calculations. In some cases, results were in good agreement. In other cases, there were significant discrepancies between results due to deficient measurements in a few comparisons and to method or data deficiencies in other comparisons. It is concluded that there is still need for further measurements and evaluations of the iron cross-section data in the energy region below 6.0 MeV. While fluxes in the moderate-energy range and the associated downscatter sources may be calculated adequately, the inadequate low-energy cross sections can lead to rather large discrepancies in integral quantities such as dose or heating.