IPSHU Research Report Series 28号
2012-03 発行

What is the origin of ^<137>Cs detected in under-floor soil samples of houses built in 1-3 years after the Hiroshima atomic bomb ?

Yamamoto, Masayoshi
Sakaguchi, Aya
Hoshi, Masaharu
Imanaka, Tetsuji
Miyamoto, Yutaka
Since 2008, we have measured 137Cs and 239,240Pu isotopes in about 60 soil samples from the under-floor of 20 houses built within 1-3 years after 1945, in order to evaluate the close-in fallout deposition due to the "Black rain" at the time of Hiroshima atomic explosion. 239,240Pu was used as indicator to evaluate the contamination from global fallout 137Cs other than Hiroshima A-bomb derived 137Cs.

As a result, it seems likely that 137Cs deposition at that time due to the Hiroshima A-bomb is 50-100 Bq/m2.
Copyright (c) 2012 Institute for Peace Science, Hiroshima University