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Sasaki, Miyuki; Sanada, Yukihisa
Journal of Advanced Simulation in Science and Engineering (Internet), 9(1), p.30 - 39, 2022/01
This study presents the evaluation results of the validity of the visualization map of the ambient dose rate at 1 m above the ground level using an artificial neural network. The dose rate map created using the artificial neural network-based method is found to reproduce ground-based survey results better than conventional methods. Suggested to improve the validity of the airborne radiation survey visualization, applying the color data obtained using a photogrammetry system is a new experience.
-ray spectra obtained via aerial radiation monitoring using an unmanned helicopterOchi, Kotaro; Sasaki, Miyuki; Ishida, Mutsushi*; Hamamoto, Shoichiro*; Nishimura, Taku*; Sanada, Yukihisa
International Journal of Environmental Research and Public Health, 14(8), p.926_1 - 926_14, 2017/08
Times Cited Count：4 Percentile：22.71(Environmental Sciences)After the Fukushima Daiichi Nuclear Power Plant accident, the vertical distribution of radiocesium in soil has been investigated to better understand the behavior of radiocesium in the environment. The typical method used for measuring the vertical distribution of radiocesium is troublesome because it requires collection and measurement of the activity of soil samples. In this study, we established a method of estimating the vertical distribution of radiocesium by focusing on the characteristics of -ray spectra obtained via aerial radiation monitoring using an unmanned helicopter. In this method, the change in the ratio of direct rays to scattered rays at various depths in the soil was utilized to quantify the vertical distribution of radiocesium. The results show a positive correlation between the abovementioned and the actual vertical distributions of radiocesium measured in the soil samples.
(Al,Ga)
O
scintillator Compton camera mounted on an unmanned helicopterShikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, J.*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Yoshino, Masao*; Ito, Shigeki*; Endo, Takanori*; et al.
Journal of Nuclear Science and Technology, 53(12), p.1907 - 1918, 2016/12
Times Cited Count：37 Percentile：96.48(Nuclear Science & Technology)The Compton camera was improved for use with the unmanned helicopter. Increase of the scintillator array from 4
4 to 88 and expanse of the distance between the two layers contributed to the improvements of detection efficiency and angular resolution, respectively. Measurements were performed over the riverbed of the Ukedo river of Namie town in Fukushima Prefecture. By programming of flight path and speed, the areas of 65 m 60 m and 65 m 180 m were measured during about 20 and 30 minutes, respectively. By the analysis the air dose rate maps at 1 m height were obtained precisely with the angular resolution corresponding to the position resolution of about 10 m from 10 m height. Hovering flights were executed over the hot spot areas for 10-20 minutes at 5-20 m height. By using the reconstruction software the -ray images including the hot spots were obtained with the angular resolution same as that evaluated in the laboratory (about 10
).
Urabe, Yoshimi; Nishihara, Katsuya; Sato, Yoshiharu; Ishibashi, Satoshi; Sanada, Yukihisa; Torii, Tatsuo
no journal, ,
no abstracts in English
Nishizawa, Yukiyasu; Yoshida, Mami; Sanada, Yukihisa; Torii, Tatsuo
no journal, ,
Many radioactive substances were released by the Fukushima Daiichi Nuclear Power Plant accident occurred on March 11, 2011 in the atmosphere. A lot of short half-life nuclides which are 
I, 
Te, etc., in addition to longer half- lived nuclides such as 
Cs and 
Cs. The estimated release amount of these nuclides from the reactor 1st to 3rd unit is reported, but it's found to be quite different in the short half-lived nuclides by the reactor units. Because the radioactivity ratio of Cs and Cs was slight different between the reactor units, it can be considered that the valuable source is obtained by the measurement of Cs/Cs ratio in the environment around the Fukushima Daiichi Nuclear Power Station at the present stage when the nuclides with short half-lives had already decayed. We have measured high-resolution -ray spectrum using an unmanned helicopter equipped with LaBr(Ce) detector in a 3-km range from the power station which was near to the release source of the radioactive cesium. Because the LaBr(Ce) detector has high resolution of rays, the discrimination of many nuclides is possible. In addition, there is extremely much number of the data provided by the distribution measurement with the unmanned helicopter. Because a new map was illustrated by the analysis of the Cs/Cs ratio, we report the outline.
Nishizawa, Yukiyasu; Yoshida, Mami*; Sanada, Yukihisa; Torii, Tatsuo
no journal, ,
no abstracts in English
Yoshimura, Kazuya; Saito, Kimiaki; Fujiwara, Kenso; Nakama, Shigeo; Mikami, Satoshi
no journal, ,
no abstracts in English
(Ce) detector for estimating radiocesium distribution in soilOchi, Kotaro; Malins, A.; Ishida, Mutsushi*; Yamada, Tsutomu*; Nakasone, Takamasa*; Sanada, Yukihisa
no journal, ,
no abstracts in English
Sasaki, Miyuki; Sanada, Yukihisa; Yamamoto, Akio*
no journal, ,
no abstracts in English
Shikaze, Yoshiaki
no journal, ,
no abstracts in English
Joung, S.*; Ji, Y.-Y.*; Choi, Y.*; Lee, E.*; Ji, W.*; Sasaki, Miyuki; Ochi, Kotaro; Sanada, Yukihisa
no journal, ,
KAERI (Korea Atomic Energy Research Institute) has developed the MARK A1 aerial survey system for unmanned aerial vehicles for use in contaminated areas. The MARK A1 system consists of a CZT detector, signal processing unit, and positioning and interface units to a PC on the ground. To validate the effectiveness of the detectors, field tests were conducted in high dose rate environments near the Fukushima Daiichi Nuclear Power Station. The JAEA and KAERI detectors were each mounted on an unmanned helicopter to make measurements at different altitudes. For both systems, the air dose rates obtained from the airborne survey gave results with a similar trend to the air dose rates obtained from the walking survey. Therefore, it is expected that MARK A1 can be used to quickly scan large and highly contaminated areas that are difficult for humans to access in the event of a nuclear accident.
