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Sueoka, Shigeru; Shimada, Koji; Ishimaru, Tsuneari; Niwa, Masakazu; Yasue, Kenichi; Umeda, Koji; Danhara, Toru*; Iwano, Hideki*
no journal, ,
no abstracts in English
Tagami, Takahiro*; Sueoka, Shigeru; Kohn, B.*; Fukuda, Shoma*
no journal, ,
no abstracts in English
Shibata, Kenji; Shimizu, Mayuko; Suzuki, Kazuhiro; Sueoka, Shigeru; Niwa, Masakazu
no journal, ,
The CHIME (Chemical Th-U-total Pb isochron method) dating has been performed on JEOL JXA-8530F FE-EPMA introduced in Tono Geoscience Center of Japan Atomic Energy Agency. Analysis of Pb on conventional spectrometers have disadvantage in count rate. JXA-8530F equipped with three R=100 provides significant shortening in analyzing time. Spectral interferences peculiar to R=100 mm spectrometers are found to be collected on the monazite analyses. The intrinsic responses of the R=100 mm counting systems with a PET crystal and a sealed Xe detector for PbMb are around ten times higher than that of the JCXA-733 counting systems. The measurement time required for a spot is ca. 35 minutes. The advanced procedure carried out 425
25 Ma for monazite from Cooma granite in southeastern Australia, which had dated by SHRIMP as 432.83.5 Ma. The CHIME monazite age of the Kojaku granite in southwestern Japan is 685 Ma that accords well with the LA-ICP-MS U-Pb zircon ages of 68.50.7 Ma.
Kitamura, Akihiro; Kurikami, Hiroshi; Sakuma, Kazuyuki; Malins, A.; Okumura, Masahiko; Itakura, Mitsuhiro; Yamada, Susumu; Machida, Masahiko
no journal, ,
Radioactive cesium that was deposited over Fukushima after the accident at the FDNPP is one of the major concerns regarding health physics. In order to predict the future distribution of radioactive cesium and resulting air dose rate at any location in Fukushima, we have integrated a number of mathematical models covering different time and scales. 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 a dam reservoir using one and two dimensional river simulation models. We also present a tool for calculating air dose rates from arbitrary radio cesium depth profiles and spatial distributions. The predicted dose rates were compared against dose rates measured in the field with handheld survey meters and good correlation was found between the two.
Malins, A.; Sakuma, Kazuyuki; Kurikami, Hiroshi; Machida, Masahiko; Kitamura, Akihiro
no journal, ,
Yasue, Kenichi; Hirouchi, Daisuke*; Kokubu, Yoko; Matsubara, Akihiro; Furusawa, Akira*
no journal, ,
This study proposes the exact identification method of faulting events. Radiocarbon ages of the black soil collected continuously from lower to upper part clarify the timing of faulting events. We sampled the black soil without space from the excavated trench wall of the active fault. The soil ages in footwall varied from 9,500 to 2,000 years ago with depth. The soil deposited at approximately a constant rate. However, there are partially the anomalous ages. The anomalies are probably caused by fault displacements, which means the collapse of hanging wall with old soil and the making of depression at the footwall side. The anomalous ages may suggest that faulting events took place in about 7,500, 6,000, 3,500, and 2,000 years ago. Our future research will be to apply this method to the soil of other active fault trench wall to clarify the timing of faulting events.
Cs/
Cs ratio around the Fukushima Daiichi Nuclear Power Plant using an unmanned helicopter radiation monitoring systemNishizawa, Yukiyasu; Yoshida, Mami*; Sanada, Yukihisa; Torii, Tatsuo
no journal, ,
Torii, Tatsuo
no journal, ,
Energetic radiation caused by thunderstorm activity is observed at various places, such as the ground, high mountain areas, and artificial satellites. In order to investigate the radiation source and its energy distribution, we measured energetic radiation by a sounding balloon, and the ground observation. On the measurement inside/above the thundercloud, we conducted a sounding observation using a adiosonde mounted two GM tubes (for 
-rays, and for 
/-rays), in addition to meteorological instruments. The balloon passed through a region of strong echoes in a thundercloud shown by radar image, at which time an increase in counting rate of the GM tube about 2 orders of magnitude occurred at the altitude from 5 km to 7.5 km. Furthermore, the counting rate of two GM tubes indicated the tendency different depending on movement of a balloon. This result suggests that the ratio for the -rays (energetic photons) of the beta-rays (energetic electrons) varies according to the place in the thundercloud. Furthermore, we carried out a ground observation of the energetic rays during winter thunderstorm at a coastal area facing the Sea of Japan. Two types of the energetic radiation have been observed at this time. We report the outline of these measurements and analysis in the session of the AGU meeting.
Sakuma, Kazuyuki; Kurikami, Hiroshi; Malins, A.; Yamada, Susumu; Funaki, Hironori; Niizato, Tadafumi; Machida, Masahiko; Kitamura, Akihiro
no journal, ,
The environments of Fukushima near the Fukushima Dai-ichi Nuclear Power Plant have been contaminated by the explosion accident of the plant caused by the Great East Japan Earthquake on 11 March 2011. The contamination level and air-dose rate behavior at present and in future are significant concern for the people used to live nearby. Most dominant radioactive material is Cs at present and its migration is considered to be driven by soil erosion and subsequent transport. To estimate the amount of soil sedimentation and the Cs migration, a three-dimensional hydrological model of the catchment was developed focused on the Ogi-no-sawa catchment, located 15 km southwest of the Fukushima Dai-ichi Nuclear Power Plant. Base on the developed hydrological model, top soil transport and resulting radio-cesium movement was simulated. For the modeling and simulation, physics based code the General-purpose terrestrial fluid-flow simulator GETFLOWS model, which is one of the tools for watershed modeling, was applied. The simulation results were compared with monitored data of the amount of water discharge and concentration of suspended solids for model testing. As a result of the study, the soil and Cs redistribution patterns at various scales of flood events could be predicted based on the results of modeling and simulation.
Iijima, Kazuki
no journal, ,
JAEA has carried out "the project on the Long-term Assessment of Transport of Radioactive Contaminant in the Environment of Fukushima (F-TRACE project)" since the end of 2012. Radiocaesium has been widely distributed by the fallout from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, mainly to the coastal area of Fukushima Prefecture. In this project, the transport behavior of radiocaesium through seven water systems located in coastal areas of Fukushima was investigated to establish predictive modeling tools for distribution of radiocaesium and to estimate future effective dose of the residents. This paper provides understanding of transport behavior of radiocaesium lead by comparison among focused rivers and quantitative evaluation of mass flow in the water system based on the results of field observations. Especially, behavior and factors defining the concentrations of particulate and dissolved radiocaesium in the water systems will be discussed.