A-bomb radiation dose estimation using dosimetry system 1986 (DS86)

Tentative 1965 Dose (T65D) has been used extensively in the calculation of exposure doses for A-bomb survivors; however, problems of T65D itself have been pointed out in the late 1970's. To modify the T65D, the US-Japan joint group has attempted to reassess atomic bomb radiation dosimetry in Hiroshima and Nagasaki. In 1987, it has established a new dosimetry system, Dosimetry System 86 (DS86), based on the ten items reassessed. Among these ten items, the following nine items are outlined in this article: (1) A-bomb power in Hiroshima and Nagasaki; (2) energy spectra of radiation source; (3) calculation of penetrating power of radiation in air; (4) actual measurement of gamma radiation using thermoluminescence dosimeter; (5) comparison between measurement and calculation of neutron radioactivity; (6) exposure to residual radioactivity; (7) geographic and house shielding; (8) organ exposure doses; and (9) DS86 for exposure dose estimates of A-bomb survivors. DS86 has two unsolved problems: the DS86 estimates disagree with both radiation doses measured from neutron radiation data and those measured by thermoluminescence dosimeter at areas approximately 1,500 m or farther from the hypocenter. The issue of neutrons seems to be involved in these problems. (N.K.)