Estimation of close-in fallout 137Cs deposition level due to the Hiroshima atomic bomb from soil samples under houses built 1–4 years after the explosion

Masayoshi Yamamoto
Low Level Radioactivity Laboratory (LLRL), Kanazawa University
Masaharu Hoshi, Kassym Zhumadilov
Research Institute for Radiation Biology and Medicine, Hiroshima University
Satoru Endo
Graduate School of Engineering, Hiroshima University
Aya Sakaguchi
Graduate School of Science, Hiroshima University, Graduate School of Science, Hiroshima University
Tetsuji Imanaka
Research Reactor Institute, Kyoto University
Yutaka Miyamoto
Radiochemical Laboratory, Nuclear Science and Engineering Directorate,
Japan Atomic Energy Agency (JAEA)

 

Abstract

Cesium-137 and Pu isotopes in under-floor soil samples from about 20 houses built 1–4 years after 1945 were measured in an attempt to evaluate the close-in fallout deposition at the time of the Hiroshima atomic explosion. 239,240Pu was used to distinguish global fallout 137Cs from Hiroshima A-bomb derived 137Cs. In all samples measured, low levels of 137Cs (range: 6.4–843 Bq/m2, but mostly in the range 10–50 Bq/m2) and traces of 239,240Pu (0.1–24 Bq/m2, but mostly less than 1 Bq/m2) were detected. The results by considering the contribution form the global fallout suggest that 137Cs deposition due to the Hiroshima A-bomb was in the range of 50–100 Bq/m2 in the areas studied.

 

 
Copyright (c) Masayoshi Yamamoto, Masaharu Hoshi, Kassym Zhumadilov, Satoru Endo, Aya Sakaguchi, Tetsuji Imanaka, Yutaka Miyamoto. All rights reserved.