Shizuma K, Iwatani K, Hasai H, Hoshi M, Oka T, Okano M
Faculty of Engineering, Hiroshima University, Japan.
Health Phys. 1996 Sep;71(3):340-6. doi: 10.1097/00004032-199609000-00011.
Low background gamma-ray measurement has been performed to determine the 137Cs content in soil samples collected in a very early survey of the Hiroshima atomic bomb. These soil samples were collected just 3 d after the explosion within 5 km from the hypocenter and were not exposed to the global fallout from nuclear weapon tests. Out of 22 samples, 137Cs was detected for 11 samples, and their radioactivities ranged from 0.16-10.6 mBq g-1 at the time of the measurement. A comparison of the 137Cs deposition with the rainfall area within Hiroshima city indicates that the rainfall area was wider than the previously proposed one. Cumulative exposure by the fallout has been estimated to be 0.31 mC kg-1 (0.12 R) in Hiroshima city except for the heavy fallout area and at most 1.0 mC kg-1 (4 R) in the heavy fallout area.
为了测定在广岛原子弹早期调查中采集的土壤样本中的137Cs含量，进行了低本底伽马射线测量。这些土壤样本是在爆炸后仅3天，于距爆心5公里范围内采集的，且未受到核武器试验全球沉降物的影响。在22个样本中，有11个样本检测到了137Cs，测量时其放射性范围为0.16 - 10.6 mBq g-1。将广岛市内137Cs沉降与降雨区域进行比较表明，降雨区域比先前提出的范围更广。据估计，除重沉降区域外，广岛市沉降物的累积暴露量为0.31 mC kg-1（0.12 R），重沉降区域最多为1.0 mC kg-1（4 R）。
