Analysis of benchmark experiment for neutron transport in sodium, stainless steel and iron

For the purpose of estimating calculation uncertainties for the prototype FBR shielding design, analyses of benchmark experiments have been attempted. The experiments were performed at the Tower Shielding Facility (TSF) of ORNL on neutron penetration in sodium, stainless steel and iron using neutron spectrometers and ''Bonner Ball'' detectors. The analyses have been made for the following six experimental configurations; 1) sodium of 30 in., 120 in. and 180 in. thickness, 2) stainless steel of 12 in. and 18 in. thickness, 3) iron of 12 in. thickness. Comparison between calculations and measurements for neutron spectra and ''Bonner Ball'' counting rates has been performed. The agreements between calculations and measurements for fast neutrons and ''Bonner Ball'' counting rates are within a factor of two except the iron results. Further investigations to the iron results have been attempted. Through the sensitivity analysis, these results can be used to predict uncertainty of neutron flux calculation for LMFBR shields. (author)