Estimation of the Air Dose from the Atomic Bombs in Hiroshima and Nagasaki

Abstract

The air dose outside of buildings due to primary and scattered radiation released by atomic bombs in Hiroshima and Nagasaki was estimated as a function of distance from the hypocenter. Neutron dose was estimated from 60Co activity in iron imbedded in concrete and gamma dose from thermoluminescence in bricks and tiles. The precision (coefficient of variation) of estimation was less than 0.11 for gamma-rays and less than 0,15 for neutrons, The results as compared with York's values show only a minor difference for gamma and agree with that for neutrons in Nagasaki, but a large difference of approximately 50 per cent for neutrons and 30–70 per cent for gamma-rays at distances from 500 to 1500 m from the hypocenter for Hiroshima. Therefore the total air dose was almost equal to York's value in Nagasaki, but less than half in Hiroshima.