Spatial distribution of dose equivalent due to natural neutrons in a ferroconcrete building

Measurement of natural neutrons has been performed in order to estimate the dose equivalent due to such neutrons in a ferroconcrete building. The spatial distribution has been revealed through the present study. The neutron intensity decreased exponentially as the measuring point was moved to the lower floors. Along the horizontal direction, the weaker neutron intensity was obtained at the farther measuring point from the outer wall. The attenuation of neutrons in the building was analyzed and the attenuation length was estimated to be 0.66 m in the vertical direction and 5.2 m in the horizontal direction. (author)