NHKスペシャル『原爆初動調査 隠された真実』のグラフ作成に用いた残留放射線測定データと計算手法

In the evening of August 9th. 2021, the 76th anniversary of the Nagasaki atomic bomb, a documentary TV program titled “Atomic Bomb Initial Investigation: Hidden Truth” was broadcast by NHK. In the program, dynamic graphics of residual radiation dose rate after the atomic bombing were shown both in Hiroshima and Nagasaki. Following the request from NHK directors, the author estimated about 15 mSv/h of air dose rate due to neutron activation near the Hiroshima hypocenter at one hour after the explosion, while it was about 98 mSv/h in the Nishiyama area 2.5 km east from the Nagasaki hypocenter due to local radioactive fallout, using the data of historical measurements by Japanese and US scientists after the bombings. In this note, the data and the method used to make graphics of residual radiation dose rate are explained.