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Kinase, Sakae; Takahashi, Tomoyuki*; Saito, Kimiaki
Journal of Nuclear Science and Technology, 54(12), p.1345 - 1354, 2017/12
Times Cited Count:26 Percentile:92.78(Nuclear Science & Technology)Saegusa, Jun; Yoda, Tomoyuki; Murakami, Mitsuhiro; Takeishi, Minoru
Kankyo Hoshano Josen Gakkai-Shi, 5(2), p.79 - 93, 2017/06
After the Fukushima Daiichi Nuclear Power Plant (NPP) accident in March 2011, environmental radiation monitoring works have been continuously conducted throughout the Fukushima prefecture of Japan. Five-year transitions of ambient dose rates at 15 locations 20-60 km away from the NPPs were precisely analyzed to investigate their chronological change. Measured dose rates were successfully fitted into a function consisting of a factor reflecting the physical decay of radiocesium and the other component such as the weathering effect. The ecological half-lives derived from the function ranged from 3 to 27 years (average 10 years). The radiation shielding effect by snow covering was also studied with the obtained functions. Due to the effect, dose rates were lowered by 15-50% by 20-cm-deep snow covering, and the ambient doses integrated over the five years were found to decrease by up to 7% compared to those without the snow covering that can be predicted from the fit function.
Kinase, Sakae
Nihon Genshiryoku Gakkai-Shi ATOMO, 58(6), p.362 - 366, 2016/06
no abstracts in English
Kinase, Sakae; Takahashi, Tomoyuki*; Sato, Satoshi; Yamamoto, Hideaki; Saito, Kimiaki
Proceedings of 17th NSFS Conference (Internet), p.27 - 33, 2016/02
Kinase, Sakae; Sato, Satoshi; Sakamoto, Ryuichi*; Yamamoto, Hideaki; Saito, Kimiaki
Radiation Protection Dosimetry, 167(1-3), p.340 - 343, 2015/11
Times Cited Count:6 Percentile:45.92(Environmental Sciences)Kinase, Sakae; Takahashi, Tomoyuki*; Sato, Satoshi*; Yamamoto, Hideaki; Saito, Kimiaki
Proceedings of International Symposium on Radiological Issues for Fukushima's Revitalized Future, p.40 - 43, 2015/00
To support recovery and rehabilitation in Fukushima, prediction models have been developed for ambient dose equivalent rate distribution within the 80 km-radius around the Fukushima Daiichi Nuclear Power Plant. The prediction models that are based on bi-exponential functions characterized by ecological half-lives of radioactive caesium for land-use, enable Fukushima residents to obtain distribution maps of ambient dose equivalent rates for the next 30 years after the accident. Model parameters were evaluated using ambient dose equivalent rates through car-borne surveys. The model parameters in deciduous and evergreen forest areas were found to be different from those in other areas. In addition, it was found that distribution maps of ambient dose equivalent rates for the next 30 years after the accident, created by the prediction models would be useful for follow-up of the radiological situation.
Saito, Kimiaki; Yoshimura, Kazuya
no journal, ,
no abstracts in English
Kinase, Sakae; Sato, Satoshi; Sakamoto, Ryuichi*; Yamamoto, Hideaki; Saito, Kimiaki
no journal, ,
Saegusa, Jun; Yoda, Tomoyuki; Murakami, Mitsuhiro; Takeishi, Minoru
no journal, ,
no abstracts in English
Kinase, Sakae; Takahashi, Tomoyuki*; Sato, Satoshi*; Yamamoto, Hideaki; Saito, Kimiaki
no journal, ,
no abstracts in English
Kinase, Sakae
no journal, ,
no abstracts in English
Kinase, Sakae; Murakami, Yuko; Takahashi, Tomoyuki*; Suzuki, Tadakazu*; Sugita, Takeshi*; Ando, Masaki; Mikami, Satoshi; Yamamoto, Hideaki; Saito, Kimiaki
no journal, ,
no abstracts in English
Saegusa, Jun
no journal, ,
no abstracts in English
Katengeza, E.*; Sanada, Yukihisa; Yoshimura, Kazuya; Ochi, Kotaro; Iimoto, Takeshi*
no journal, ,
The rate of temporal change of radiocesium concentration in bottom sediments is governed not only by its physical decay but also by various ecological processes. In this study, the decreasing trend of radiocesium concentration over wide pond areas of surface sediments (up to 10 cm depth), due to ecological processes, was investigated using plastic scintillation fibers (PSF) and was quantified by the ecological half life. PSF measurements were conducted between 2013 and 2019. Their conversion factors ((Bq/kg)/cps) were obtained by comparison between detected radiation counting rate obtained by PSF and the concentration of radiocesium in sediment cores collected from coinciding positions within the same ponds. A forest catchment pond exhibited the longest ecological half life and may indicate catchment derived radiocesium input as was partly evident in the spatial temporal patterns of radiocesium concentration at this pond's inlet.
Machida, Masahiko; Uno, Shumpei*; Tanimura, Naoki*; Saito, Kimiaki; Yoshimura, Kazuya
no journal, ,
Air dose rates in urban areas decrease faster in residential areas than in evacuation zones. This suggests that human activities facilitate the reduction. However, since human activities include various factors such as decontamination and road wear caused by traffic, it is difficult to evaluate the effect of human activities by conventional analysis using monitoring data, except for the effect of decontamination. Then, this series of studies aim to evaluate the effects of human activities on the reduction. Among the series presentations, this one focuses on correlations between population dynamics characterized by mobile phone GPS information and ecological half life decays of air dose rates measured by KURAMA over a wide area with long-term monitoring using LASSO scheme.