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Torii, Tatsuo
no journal, ,
Nishizawa, Yukiyasu; Sugita, Takeshi*; Sanada, Yukihisa; Torii, Tatsuo
no journal, ,
For a precise assessment of the distribution of radioactive cesium dispersed over a wide area, one must accurately evaluate the background radiation due to natural radionuclides. We have developed a new method that accurately evaluates the spatial distribution of the background radiation in areas contaminated by radioactive cesium. Using the data from aerial monitoring, we analyzed such distribution while excluding the effect of radioactive cesium. This method made it possible to evaluate not only the precipitation of radioactive cesium with quite well accuracy, but also the spatial distribution of the natural radionuclides all over Japan.
Yamada, Susumu; Kitamura, Akihiro; Kurikami, Hiroshi; Machida, Masahiko
no journal, ,
no abstracts in English
Kitamura, Akihiro; Kurikami, Hiroshi; Oda, Yoshihiro; Nakama, Shigeo; Malins, A.; Yamada, Susumu; Okumura, Masahiko; Machida, Masahiko
no journal, ,
Radioactive cesium, which strongly adheres to soils, is one of the major concerns regarding health physics in Fukushima today. It migrates mainly by soil erosion and subsequent sediment transport within surface water during times of widespread flooding. In order to predict the future distribution and resulting air dose rate at any location in Fukushima, we have prepared a number of mathematical models for radioactive cesium transport with different space and time scales. In this presentation we cover our prediction methodology, ranging from sediment and radioactive cesium movement to resulting long term air dose rate changes. Specifically, we present simulation results of sediment movement and radioactive cesium migration using semi-empirical and physics based watershed models, and that of sediment and radioactive cesium behavior in dam reservoirs using one and two dimensional water system simulation models. We also present some simulation results on air dose rate at a particular location and compared with direct measurement value.