The Experts below are selected from a list of 100473 Experts worldwide ranked by ideXlab platform
Yuichi Onda - One of the best experts on this subject based on the ideXlab platform.
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Detailed deposition density maps constructed by large-scale Soil Sampling for gamma-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant accident
Journal of Environmental Radioactivity, 2015Co-Authors: Kimiaki Saito, Yoshihiro Ikeuchi, Susumu Shimoura, Mamoru Fujiwara, Isao Tanihata, Takaharu Otsuka, Yuichi Onda, Masaharu Hoshi, Fumiaki TakahashiAbstract:Soil deposition density maps of gamma-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant (NPP) accident were constructed on the basis of results from large-scale Soil Sampling. In total 10,915 Soil samples were collected at 2168 locations. Gamma rays emitted from the samples were measured by Ge detectors and analyzed using a reliable unified method. The determined radioactivity was corrected to that of June 14, 2011 by considering the intrinsic decay constant of each nuclide. Finally the deposition maps were created for134Cs,137Cs,131I,129mTe and110mAg. The radioactivity ratio of134Cs-137Cs was almost constant at 0.91 regardless of the locations of Soil Sampling. The radioactivity ratios of131I and129mTe-137Cs were relatively high in the regions south of the Fukushima NPP site. Effective doses for 50y after the accident were evaluated for external and inhalation exposures due to the observed radioactive nuclides. The radiation doses from radioactive cesium were found to be much higher than those from the other radioactive nuclides.
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Soil Sampling and analytical strategies for mapping fallout in nuclear emergencies based on the fukushima dai ichi nuclear power plant accident
Journal of Environmental Radioactivity, 2015Co-Authors: Yuichi Onda, Hiroaki Kato, Masaharu Hoshi, Yoshio Takahashi, Minhlong NguyenAbstract:Abstract The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident resulted in extensive radioactive contamination of the environment via deposited radionuclides such as radiocesium and 131 I. Evaluating the extent and level of environmental contamination is critical to protecting citizens in affected areas and to planning decontamination efforts. However, a standardized Soil Sampling protocol is needed in such emergencies to facilitate the collection of large, tractable samples for measuring gamma-emitting radionuclides. In this study, we developed an emergency Soil Sampling protocol based on preliminary Sampling from the FDNPP accident-affected area. We also present the results of a preliminary experiment aimed to evaluate the influence of various procedures (e.g., mixing, number of samples) on measured radioactivity. Results show that sample mixing strongly affects measured radioactivity in Soil samples. Furthermore, for homogenization, shaking the plastic sample container at least 150 times or disaggregating Soil by hand-rolling in a disposable plastic bag is required. Finally, we determined that five Soil samples within a 3 m × 3-m area are the minimum number required for reducing measurement uncertainty in the emergency Soil Sampling protocol proposed here.
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vertical distribution of radiocesium in coniferous forest Soil after the fukushima nuclear power plant accident
Journal of Environmental Radioactivity, 2014Co-Authors: Mengistu T Teramage, Hiroaki Kato, Yuichi Onda, Takashi Gomi, Jeremy Patin, Sooyoun NamAbstract:Abstract This study deals with the description of the vertical distribution of radiocaesium ( 137 Cs and 134 Cs) in a representative coniferous forest Soil, investigated 10 months after the Fukushima radioactive fallout. During Soil Sampling, the forest floor components (understory plants, litter (Ol-) and fermented layers (Of)) were collected and treated separately. The results indicate that radiocesium is concentrated in the forest floor, and high radiocesium transfer factor observed in the undergrowth plants (3.3). This made the forest floor an active exchanging interphase for radiocesium. The raw organic layer (Ol + Of) holds 52% (5.3 kBq m −2 ) of the Fukushima-derived and 25% (0.7 kBq m −2 ) of the pre-Fukushima 137 Cs at the time of the Soil Sampling. Including the pre-Fukushima 137 Cs, 99% of the total Soil inventory was in the upper 10 cm, in which the organic matter (OM) content was greater than 10%, suggesting the subsequent distribution most likely depends on the OM turnover. However, the small fraction of the Fukushima-derived 137 Cs at a depth of 16 cm is most likely due to the infiltration of radiocesium-circumscribed rainwater during the fallout before that selective adsorption prevails and reduces the migration of soluble 137 Cs. The values of the depth distribution parameters revealed that the distribution of the Fukushima-derived 137 Cs was somewhat rapid.
Minhlong Nguyen - One of the best experts on this subject based on the ideXlab platform.
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Soil Sampling and analytical strategies for mapping fallout in nuclear emergencies based on the fukushima dai ichi nuclear power plant accident
Journal of Environmental Radioactivity, 2015Co-Authors: Yuichi Onda, Hiroaki Kato, Masaharu Hoshi, Yoshio Takahashi, Minhlong NguyenAbstract:Abstract The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident resulted in extensive radioactive contamination of the environment via deposited radionuclides such as radiocesium and 131 I. Evaluating the extent and level of environmental contamination is critical to protecting citizens in affected areas and to planning decontamination efforts. However, a standardized Soil Sampling protocol is needed in such emergencies to facilitate the collection of large, tractable samples for measuring gamma-emitting radionuclides. In this study, we developed an emergency Soil Sampling protocol based on preliminary Sampling from the FDNPP accident-affected area. We also present the results of a preliminary experiment aimed to evaluate the influence of various procedures (e.g., mixing, number of samples) on measured radioactivity. Results show that sample mixing strongly affects measured radioactivity in Soil samples. Furthermore, for homogenization, shaking the plastic sample container at least 150 times or disaggregating Soil by hand-rolling in a disposable plastic bag is required. Finally, we determined that five Soil samples within a 3 m × 3-m area are the minimum number required for reducing measurement uncertainty in the emergency Soil Sampling protocol proposed here.
Masaharu Hoshi - One of the best experts on this subject based on the ideXlab platform.
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Detailed deposition density maps constructed by large-scale Soil Sampling for gamma-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant accident
Journal of Environmental Radioactivity, 2015Co-Authors: Kimiaki Saito, Yoshihiro Ikeuchi, Susumu Shimoura, Mamoru Fujiwara, Isao Tanihata, Takaharu Otsuka, Yuichi Onda, Masaharu Hoshi, Fumiaki TakahashiAbstract:Soil deposition density maps of gamma-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant (NPP) accident were constructed on the basis of results from large-scale Soil Sampling. In total 10,915 Soil samples were collected at 2168 locations. Gamma rays emitted from the samples were measured by Ge detectors and analyzed using a reliable unified method. The determined radioactivity was corrected to that of June 14, 2011 by considering the intrinsic decay constant of each nuclide. Finally the deposition maps were created for134Cs,137Cs,131I,129mTe and110mAg. The radioactivity ratio of134Cs-137Cs was almost constant at 0.91 regardless of the locations of Soil Sampling. The radioactivity ratios of131I and129mTe-137Cs were relatively high in the regions south of the Fukushima NPP site. Effective doses for 50y after the accident were evaluated for external and inhalation exposures due to the observed radioactive nuclides. The radiation doses from radioactive cesium were found to be much higher than those from the other radioactive nuclides.
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Soil Sampling and analytical strategies for mapping fallout in nuclear emergencies based on the fukushima dai ichi nuclear power plant accident
Journal of Environmental Radioactivity, 2015Co-Authors: Yuichi Onda, Hiroaki Kato, Masaharu Hoshi, Yoshio Takahashi, Minhlong NguyenAbstract:Abstract The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident resulted in extensive radioactive contamination of the environment via deposited radionuclides such as radiocesium and 131 I. Evaluating the extent and level of environmental contamination is critical to protecting citizens in affected areas and to planning decontamination efforts. However, a standardized Soil Sampling protocol is needed in such emergencies to facilitate the collection of large, tractable samples for measuring gamma-emitting radionuclides. In this study, we developed an emergency Soil Sampling protocol based on preliminary Sampling from the FDNPP accident-affected area. We also present the results of a preliminary experiment aimed to evaluate the influence of various procedures (e.g., mixing, number of samples) on measured radioactivity. Results show that sample mixing strongly affects measured radioactivity in Soil samples. Furthermore, for homogenization, shaking the plastic sample container at least 150 times or disaggregating Soil by hand-rolling in a disposable plastic bag is required. Finally, we determined that five Soil samples within a 3 m × 3-m area are the minimum number required for reducing measurement uncertainty in the emergency Soil Sampling protocol proposed here.
Hiroaki Kato - One of the best experts on this subject based on the ideXlab platform.
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Soil Sampling and analytical strategies for mapping fallout in nuclear emergencies based on the fukushima dai ichi nuclear power plant accident
Journal of Environmental Radioactivity, 2015Co-Authors: Yuichi Onda, Hiroaki Kato, Masaharu Hoshi, Yoshio Takahashi, Minhlong NguyenAbstract:Abstract The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident resulted in extensive radioactive contamination of the environment via deposited radionuclides such as radiocesium and 131 I. Evaluating the extent and level of environmental contamination is critical to protecting citizens in affected areas and to planning decontamination efforts. However, a standardized Soil Sampling protocol is needed in such emergencies to facilitate the collection of large, tractable samples for measuring gamma-emitting radionuclides. In this study, we developed an emergency Soil Sampling protocol based on preliminary Sampling from the FDNPP accident-affected area. We also present the results of a preliminary experiment aimed to evaluate the influence of various procedures (e.g., mixing, number of samples) on measured radioactivity. Results show that sample mixing strongly affects measured radioactivity in Soil samples. Furthermore, for homogenization, shaking the plastic sample container at least 150 times or disaggregating Soil by hand-rolling in a disposable plastic bag is required. Finally, we determined that five Soil samples within a 3 m × 3-m area are the minimum number required for reducing measurement uncertainty in the emergency Soil Sampling protocol proposed here.
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vertical distribution of radiocesium in coniferous forest Soil after the fukushima nuclear power plant accident
Journal of Environmental Radioactivity, 2014Co-Authors: Mengistu T Teramage, Hiroaki Kato, Yuichi Onda, Takashi Gomi, Jeremy Patin, Sooyoun NamAbstract:Abstract This study deals with the description of the vertical distribution of radiocaesium ( 137 Cs and 134 Cs) in a representative coniferous forest Soil, investigated 10 months after the Fukushima radioactive fallout. During Soil Sampling, the forest floor components (understory plants, litter (Ol-) and fermented layers (Of)) were collected and treated separately. The results indicate that radiocesium is concentrated in the forest floor, and high radiocesium transfer factor observed in the undergrowth plants (3.3). This made the forest floor an active exchanging interphase for radiocesium. The raw organic layer (Ol + Of) holds 52% (5.3 kBq m −2 ) of the Fukushima-derived and 25% (0.7 kBq m −2 ) of the pre-Fukushima 137 Cs at the time of the Soil Sampling. Including the pre-Fukushima 137 Cs, 99% of the total Soil inventory was in the upper 10 cm, in which the organic matter (OM) content was greater than 10%, suggesting the subsequent distribution most likely depends on the OM turnover. However, the small fraction of the Fukushima-derived 137 Cs at a depth of 16 cm is most likely due to the infiltration of radiocesium-circumscribed rainwater during the fallout before that selective adsorption prevails and reduces the migration of soluble 137 Cs. The values of the depth distribution parameters revealed that the distribution of the Fukushima-derived 137 Cs was somewhat rapid.
Fumiaki Takahashi - One of the best experts on this subject based on the ideXlab platform.
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Detailed deposition density maps constructed by large-scale Soil Sampling for gamma-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant accident
Journal of Environmental Radioactivity, 2015Co-Authors: Kimiaki Saito, Yoshihiro Ikeuchi, Susumu Shimoura, Mamoru Fujiwara, Isao Tanihata, Takaharu Otsuka, Yuichi Onda, Masaharu Hoshi, Fumiaki TakahashiAbstract:Soil deposition density maps of gamma-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant (NPP) accident were constructed on the basis of results from large-scale Soil Sampling. In total 10,915 Soil samples were collected at 2168 locations. Gamma rays emitted from the samples were measured by Ge detectors and analyzed using a reliable unified method. The determined radioactivity was corrected to that of June 14, 2011 by considering the intrinsic decay constant of each nuclide. Finally the deposition maps were created for134Cs,137Cs,131I,129mTe and110mAg. The radioactivity ratio of134Cs-137Cs was almost constant at 0.91 regardless of the locations of Soil Sampling. The radioactivity ratios of131I and129mTe-137Cs were relatively high in the regions south of the Fukushima NPP site. Effective doses for 50y after the accident were evaluated for external and inhalation exposures due to the observed radioactive nuclides. The radiation doses from radioactive cesium were found to be much higher than those from the other radioactive nuclides.