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Yamashita, Takuya
no journal, ,
JAEA has been conducting decontamination simulations and calculating the future air dose rates for the purpose of providing information to the government and local governments that are in the process of reconstruction. The restoration support system for environment "RESET" is used for decontamination simulation, and "two component model of air dose rate attenuation" is used for prediction of future air dose rate after decontamination. Since the "two-component model of air dose rate attenuation" has not been sufficiently confirmed for the measurement data after decontamination, the applicability to the area after decontamination was verified. Since the prediction by the two-component model has good agreement with the measured air dose rate after the decontamination model demonstration project conducted by the Ministry of the Environment and the variation of the parameters, it is judged that there is no problem in applying to prediction.
Nagao, Fumiya; Kitamura, Akihiro
no journal, ,
JAEA published new information website in March 2019 about radiocesium in the environment in Fukushima, which named "Fukushima Comprehensive Environmental Information Site". This site aggregates survey data gained by JAEA, results of analytical studies about air dose rate and dynamics of radiocesium, and answers for questions JAEA received.
Matsueda, Makoto; Yanagisawa, Kayo*; Fujiwara, Kenso; Kitamura, Akihiro
no journal, ,
Strontium-90 (
Sr) is one of the fission products and required a long time in the conventional radioactivity analysis (about a month). Therefore, we introduced the mass spectrometry analysis system combined inductively coupled plasma mass spectrometry (ICP-MS) and pretreatment units to determine Sr more quickly. This system was mainly used for low matrix samples such as rainwater, but this time we report the measurement results of Sr in fishes containing a lot of matrix (such as calcium).
Fujiwara, Kenso; Kuwata, Haruka*; Misono, Toshiharu; Kitamura, Akihiro
no journal, ,
Since various radionuclides including tritium was released into the ocean by the Fukushima Dai-ichi Nuclear Power Station accident, transfer of those to marine products has been concerned. In case of tritium, Organically Bound Tritium (OBT) was considered to be relatively important for the transfer due to its longer biological half-life. However, analysis of organically bound tritium (OBT), which is one of beta-emitting radionuclides, requires complicated pretreatment and takes a long time conventionally. Therefore, in this method, the time per combustion could be shortened compared to the conventional method by reviewing the combustion process in the analysis of OBT. As a result of comparing the amount and composition of water recovered after combustion, almost no difference between the two methods was observed. The analysis results of tritium in tissue free water (TFWT) and OBT in the conventional method are all below the lower limit of detection, Both TFWT and OBT were at the nSv level even if internal exposure was evaluated using these values.
Nakama, Shigeo
no journal, ,
Decrease in air dose rate in decontaminated area is essential information to estimate external exposure and to facilitate return of local residents. To clarify the effect of ground surface type (i.e. paved and soil surfaces) on the decrease in air dose rate at 1 m above the ground, surface dose rate at 1 cm above the ground and the air dose rate were monitored for four years since decontamination in 2011, and their decrease rates were compared relating to the ground surface type. Decrease in the air dose rate and the surface dose rate on the asphalt pavement showed faster rates than those on the soil surface. Ratio of decrease in the air dose rate and surface dose rate (decrease rate ratio) was distributed between 0.8 and 1.2 on open place not affected by surrounding environment. Therefore, decrease in the air dose rate was in agreement with the decrease of the surface dose rate, which is greatly affected by the ground surface. It became clear that the decrease rate constant of the air dose rate differs depending on the difference in the ground surface.
Ochi, Kotaro
no journal, ,
no abstracts in English
Funaki, Hironori; Nakanishi, Takahiro; Tsuruta, Tadahiko
no journal, ,
We examined the migration behavior of radiocaesium derived from the Fukushima Daiichi Nuclear Power Plant accident in hydrosphere.
Sakuma, Kazuyuki
no journal, ,
Cesium-137 discharge and discharge ratio from river systems in Fukushima coastal region into the ocean were simulated using a physically based watershed modeling. We reported that amounts of the cesium-137 discharge was depending on the river catchment areas and cesium-137 deposition in catchments, however the cesium-137 discharge ratio tended to depend on the presence of dam reservoirs and the initial fallout distribution within the catchments.
Hagiwara, Hiroki
no journal, ,
no abstracts in English
Ito, Satomi; Sasaki, Yoshito; Niizato, Tadafumi; Watanabe, Takayoshi; Mitachi, Katsuaki*
no journal, ,
no abstracts in English
Niizato, Tadafumi; Arai, Hirotsugu*; Hayashi, Seiji*
no journal, ,
The inventory of Cs-137 on the forest floor suffered from the wildfire in the Juman-yama region show no clear difference between the burnt and unburnt areas. The monitoring results of Cs-137 outflow from the mountain slope show high outflow rate one year after the wildfire, but restoration of forest floor cover results in the lower outflow rate next year after the wildfire.
Watanabe, Takayoshi; Sasaki, Yoshito; Niizato, Tadafumi; Mitachi, Katsuaki*; Ito, Satomi
no journal, ,
no abstracts in English
Machida, Masahiko; Yamada, Susumu
no journal, ,
no abstracts in English
Dohi, Terumi
no journal, ,
no abstracts in English
Niizato, Tadafumi; Hayashi, Seiji*; Arai, Hirotsugu*
no journal, ,
In this paper, we present an outline of Phase 1 investigation results and next Phase 2 research plans conducting in the Sector of Environmental dynamic research of Fukushima Prefectural Centre for Environmental Creation.