Estimation of neutron doses in Hiroshima and Nagasaki atomic bombings

For the radiation doses in the Hiroshima and the Nagasaki atomic bombings, the estimated values of T65D (in the United States) have been used. In recent years, however, these values are being restudied. On the basis of the neutron spectra from atomic bombings published from LANL in 1976, the neutron doses in the Hiroshima and Nagasaki atomic bombings were estimated. It was pointed out that the neutron doses of T65D were overestimated. The results of calculation in this estimation were that at the distance from 1 km to 2 km, the neutron doses in Hiroshima and Nagasaki were from 1/5 to 1/9 and about 1/3, respectively, as compared with those in T65D. The estimation of the neutron doses in the atomic bombings by calculation, the difference from T65D and the comparison with the measured radioactivities immediately after atomic bombings are described. (Mori, K.)