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Journal Articles

Application of the forest shielding factor to the maximum-likelihood expectation maximization method for airborne radiation monitoring

Sasaki, Miyuki; Sanada, Yukihisa; Yamamoto, Akio*

Radiation Protection Dosimetry, 184(3-4), p.400 - 404, 2019/10

 Times Cited Count:1 Percentile:23.13(Environmental Sciences)

The maximum-likelihood expectation maximization (ML-EM) method is expected to improve the accuracy of airborne radiation monitoring using an unmanned aerial vehicle. The accuracy of the ML-EM method depends on various parameters, including detector efficiency, attenuation factor, and shielding factor. In this study, we evaluate the shielding factor of trees based on several field radiation measurements. From the actual measurement, the shielding factors were well correlated with the heights of the trees. The evaluated shielding factors were applied to the ML-EM method in conjunction with the measured data obtained from above the Fukushima forest. Compared with the conventional methods used for calculating the dose rate, the proposed method is found to be more reliable.

Journal Articles

Journal Articles

Evaluation of ecological half-life of dose rate based on airborne radiation monitoring following the Fukushima Dai-ichi Nuclear Power Plant accident

Sanada, Yukihisa; Urabe, Yoshimi*; Sasaki, Miyuki; Ochi, Kotaro; Torii, Tatsuo

Journal of Environmental Radioactivity, 192, p.417 - 425, 2018/12

 Times Cited Count:16 Percentile:72.78(Environmental Sciences)

Journal Articles

Study for estimation of snow depth by using DSM made by SfM method

Miyasaka, Satoshi*; Unome, Sota*; Tamura, Ayako*; Ito, Yoshiaki*; Ishizaki, Azusa; Sanada, Yukihisa

Nihon Rimoto Senshingu Gakkai Dai-63-Kai (Heisei-29-Nendo Shuki) Gakujutsu Koenkai Rombunshu (CD-ROM), p.81 - 84, 2017/11

Information of snow depth is important to improve the airborne radiation measurement in the winter. The snow depth is enable to estimate by the aerial photograph which is obtained at the same time with the radiation measurement before and after the snowfall. We attempted optimization parameters which used to make a Digital Surface Model (DSM) using Structure from Motion (SfM) method for estimation of the snow depth. As a result, to enable to measure precisely the snow depth was indicated. However, the estimated snow depth in the forest area was relatively not so accurate because fallen leaves and a tree move were prevented to measure DSM precisely.

Journal Articles

Challenges for enhancing Fukushima environmental resilience, 3; Development of measurement and evaluation techniques for the environmental radiation monitoring

Sanada, Yukihisa

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 59(7), p.418 - 422, 2017/07

no abstracts in English

Oral presentation

Estimation of depth profile of radiocesium in soil based on characteristics of $$gamma$$-ray spectra obtained by airborne radiation monitoring

Ochi, Kotaro; Sasaki, Miyuki; Ishida, Mutsushi*; Sato, Tomohiko*; Hamamoto, Shoichiro*; Nishimura, Taku*; Sanada, Yukihisa

no journal, , 

A large amount of radiocesium ($$^{134}$$Cs & $$^{137}$$Cs) were released into the atmosphere as a result of 2011 Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. To estimate the impact of the accident to the environment, dose rate around FDNPP have been measured by MEXT. Dose rate nearby FDNPP, however, still stay high even though decontamination work was carried out, which means it is necessary to develop an effective decontamination method promptly. Information of depth profile of radiocesium in soil is required to realize it, though, most of measurement methods have trouble due to collection and measurement of soil samples. As we have developed the radiation measurement techniques using unmanned aerial vehicle to measure dose rate distribution over wide areas for years, we attempt to establish the estimation method of depth profile of radiocesium in soil based on characteristics of $$gamma$$-ray spectra obtained by airborne radiation monitoring in this paper.

Oral presentation

Experience of airborne radiation monitoring after the Fukushima Dai-ichi Nuclear Station accident

Sanada, Yukihisa

no journal, , 

This article presents the methods and the results of manned helicopter radiation monitoring and unmanned helicopter radiation monitoring carried out around Fukushima Dai-ichi Nuclear Power Station after the accident.

Oral presentation

Environmental radiation monitoring in Fukushima, 1; Large-scale survey

Sanada, Yukihisa; Mikami, Satoshi

no journal, , 

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