Revision of Dosimetry System of Atomic Bomb Radiation from DS86 to DS02

Revision of Dosimetry System of Atomic Bomb Radiation from DS86 to DS02

It is necessary to estimate the exposed atomic bomb initial radiation dose of survivors
for the epidemiological studies by the ABCC and RERF. For this purpose the US had
made an estimation of radiation dose, the T57D (Tentative Dose 1957) and the T65D
(Tentative Dose 1965), on the basis of nuclear tests. The atomic bomb dosimetry system
DS86 is the first computer calculated estimation of the initial radiation dose from the
Hiroshima and Nagasaki atomic bombs. The DS86 put emphasis on the initial radiation
reached at short distances and showed little concern for, or neglected, residual radiation
from fallout and induced radioactive matter.
The Dosimetry System 2002 (DS02), a substitute of the DS86, was published in
2005. In the DS02 in order to rectify an over estimate of initial radiation doses at short
distances in the DS86 the height of explosion of Hiroshima bomb is changed from
580m to 600m and the yield of explosion from 15 ktTNT to 16 ktTNT. Leaving aside
the problem of a discrepancy between estimated values from the DS86 system and
experimentally measured values in the distant region without further explanation, the
preparation of DS02 is justified by a US side argument that measured values at greater
distances include natural background radiation effects other than bomb radiation. The
DS02 did not contain a single description of the residual radiation.
Since the estimation of initial radiation (both of gamma rays and neutrons) from
measurements systematically exceed the estimation of the DS86 and DS02 in the region
more distant than 1.5 km from the hypocenter and the discrepancies increase with
distance, the DS86 and DS02 estimates cannot be applied to the distance beyond 1.5 km
from the hypocenter of atomic bombing even confined to the initial radiation.