Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Kato, Shingo; Ishizuka, Akihiro; Okuyama, Shinichi; Nozaki, Tatsuo; Hayashi, Gaku*; Yasuda, Nakahiro*; Torii, Tatsuo*; Ando, Takasuke*
no journal, ,
no abstracts in English
Sanada, Yukihisa; Sam Koh, B. K.*; Hirao, Shigekazu*; Torii, Tatsuo*
no journal, ,
Radon-222, an inert radioactive gas with a half-life of 3.82 days that is widely present in the environment, is often used to study atmospheric processes. Measurements of radon at high altitudes are scarce and its regional behaviour is not clear. On the other hand, radon in the air interferes with airborne radiological survey (ARS) for measuring surface radiation distribution, which has been conducted since the Fukushima Daiichi NPP accident. In this study, to elucidate radon dynamics and ARS disturbance corrections, the ARS system was simulated by EGS5, a Monte Carlo Simulation, to calculate the response of radon progeny and the simulation results were applied to actual ARS data.
Kawahara, Rika*; Ochi, Kotaro; Yamaguchi, Katsuhiko*; Torii, Tatsuo*
no journal, ,
As a result of the Fukushima Daiichi Nuclear Power Station accident, radioactive materials were dispersed into the environment from inside the nuclear reactor. Now that the difficult-to-return zone is being lifted, it is important to understand the radiation distribution in the surrounding area. At two locations in the difficult-to-return zone (Okuma Town), measurements were taken with a Compton camera and video was recorded with an optical camera. The locations of radionuclides were confirmed by combining the measurement data and video. The measurement equipment used included a Compton camera using a CZT (CdZnTe) semiconductor (H420 manufactured by H3D), a survey meter with a wand-type GPS (Gamma Plotter H manufactured by Japan Radiation Engineering Co., Ltd.) and an optical camera. Air dose rates at 1 m above ground level ranged from 4 to 46 
Sv/h at the first location and from 6 to 12 Sv/h at the second location. By photographing the high-dose points from various positions and angles, the three-dimensional spatial extent of the radiation source could be confirmed.