Dosimetry - A. Physical Dose Estimates for A-bomb Survivors - Studies at Oak Ridge, U.S.A.

Abstract

The radiation exposures for the survivors of the nuclear bombings of Hiroshima and Nagasaki have been determined in the course of studies conducted since the mid-1950's at the Oak Ridge National Laboratory. An extensive series of experiments in Japan, at weapons tests, and in the laboratory were supported by a comprehensive calculational effort to produce the "air dose" distributions and the shielding factors. The absorbed doses to tissues of the body have been calculated for the ease of homogeneous tissue cylinders, and studies of dose distribution in heterogeneous, anthropomorphic configurations are under way. Because the device detonated over Hiroshima was never test fired before or after the bombing, the greatest difficulties were associated with the normalization of the radiation yield of this device. However, after several years of study, the "air dose" curves were obtained to an accuracy of 2 15% for Hiroshima and 2 10% for Nagasaki. Subsequently, the shielding factors for typical dwellings in both cities were determined to a comparable accuracy. Continuing work is focused on obtaining shielding factors for the heavily shielded survivors, the doses to survivors who are now located in the United States and more comprehensive depth dose distributions.