Neutron-Attenuation Experiments in Iron-Water Configurations

Fast-, epithermal-, and thermal-neutron penetration has been measured in the ETNA facility (plane fission neutron source) for some simple shield configurations (all water or a composite of water, iron, and water slabs with iron thickness of 6.2, 10, and 19.6 cm)., Experimental results are presented as thermal fluxes or activation-detector reaction rates for the water-only configuration and as the ratios of the reaction rates observed in the other configurations to those obtained with water only. These results are compared to calculations performed with a multigroup-removal diffusion code (MAC-RAD) and a semi-empirical diffusion code (FOG-S) to test their ability to predict the influence of an iron slab on the neutron spectrum and the neutron attenuation.