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Kokubun, Yuji; Hosomi, Kenji; Nagaoka, Mika; Seya, Natsumi; Inoue, Kazumi; Koike, Yuko; Uchiyama, Rei; Sasaki, Kazuki; Maehara, Yushi; Matsuo, Kazuki; et al.
JAEA-Review 2024-054, 168 Pages, 2025/03
JAEA-Review-2024-054.pdf:2.73MB
The Nuclear Fuel Cycle Engineering Laboratories conducts environmental radiation monitoring around the reprocessing plant in accordance with the "Safety Regulations for Reprocessing Plant of JAEA, Part IV: Environmental Monitoring". This report summarizes the results of environmental radiation monitoring conducted during the period from April 2023 to March 2024 and the results of dose calculations for the surrounding public due to the release of radioactive materials from the plant into the atmosphere and ocean. In the results of the above environmental radiation monitoring, several items were affected by radioactive materials emitted from the accident at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company, Incorporated (changed to Tokyo Electric Power Holdings, Inc. on April 1, 2016), which occurred in March 2011. In addition, environmental monitoring plan, analysis and measurement methods, monitoring data and their chronological change, meteorological data after statistical processing, status of radioactive waste release and evaluation results of the data over the normal range are included as appendices.
Tsubota, Yoichi; Kimura, Yasuhisa; Nagai, Yuya; Kojima, Sho*; Tokonami, Shinji*; Nakagawa, Takahiro
Proceedings of International Conference on Decommissioning Challenges; Role and importance of innovations (DEM 2024) (Internet), 7 Pages, 2024/05
An in-situ monitoring system for the 
-aerosol in the harsh (high humidity, high 
/
-ray background) environment expected inside the 1F-PCV was developed. A part of the system was installed at the glovebox dismantling site of a MOX fuel facility, and its fast response performance and long-term operation capability were demonstrated.
Kokubun, Yuji; Nakada, Akira; Seya, Natsumi; Koike, Yuko; Nemoto, Masashi; Tobita, Keiji; Yamada, Ryohei*; Uchiyama, Rei; Yamashita, Daichi; Nagai, Shinji; et al.
JAEA-Review 2023-046, 164 Pages, 2024/03
JAEA-Review-2023-046.pdf:4.2MB
The Nuclear Fuel Cycle Engineering Laboratories conducts environmental radiation monitoring around the reprocessing plant in accordance with the "Safety Regulations for Reprocessing Plant of JAEA, Part IV: Environmental Monitoring". This report summarizes the results of environmental radiation monitoring conducted during the period from April 2022 to March 2023 and the results of dose calculations for the surrounding public due to the release of radioactive materials into the atmosphere and ocean. In the results of the above environmental radiation monitoring, many items were affected by radioactive materials emitted from the accident at the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company, Incorporated (changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016), which occurred in March 2011. Also included as appendices are an overview of the environmental monitoring plan, an overview of measurement methods, measurement results and their changes over time, meteorological statistics results, radioactive waste release status, and an evaluation of the data which deviated of the normal range.
Oba, Takashi*; Ishikawa, Tetsuo*; Nagai, Haruyasu; Tokonami, Shinji*; Hasegawa, Arifumi*; Suzuki, Gen*
Scientific Reports (Internet), 10(1), p.3639_1 - 3639_11, 2020/02
Times Cited Count：20 Percentile：78.26(Multidisciplinary Sciences)Internal doses of residents after the Fukushima Daiichi Nuclear Power Station accident have been reconstructed. In total 896 behaviour records in the Fukushima Health Management Survey were analysed to estimate thyroid doses via inhalation, using a spatiotemporal radionuclides concentration database constructed by atmospheric dispersion simulations. After a decontamination factor for sheltering and a modifying factor for the dose coefficient were applied, estimated thyroid doses were close to those estimated on the basis of direct thyroid measurement. The median and 95th percentile of thyroid doses of 1-year-old children ranged from 1.2 to 15 mSv and from 7.5 to 30 mSv, respectively.
Cs (TRACs) for Fukushima Nuclear Power Plant accidentNagai, Yasuki; Makii, Hiroyuki; Namiki, Shinji; Iwamoto, Osamu; Iwamoto, Nobuyuki; Sawahata, Hiroyuki*
Journal of the Physical Society of Japan, 81(8), p.085003_1 - 085003_2, 2012/08
Times Cited Count：1 Percentile：10.43(Physics, Multidisciplinary)We propose to use the radionuclide Cs as a tracer. -ray energy of the most intense line from the decay of Cs is 668 keV, which is very near to that of the 662 keV from the decay of 
Cs, while the half-life of Cs is 6.5 d. Cs can be produced by nuclear reactions such as 
Cs(n,2n)Cs, Cs(r,n)Cs or Xe(p,n)Cs. The Cs tracer would be useful in the quantitative studies of radionuclide Cs contaminant in human, and in any experimental studies in the minimization of radionuclide Cs contamination in agricultural and stock farming products.
Nagai, Niro*; Yoshikawa, Shinji
no journal, ,
The helically coiled tube of heat exchanger is used for the evaporator of prototype fast breeder reactor "Monju". This report aims at the grasp of two-phase flow phenomena of forced convective boiling of water inside helically coiled tube, especially focusing on oscillation of dryout point. A shell & tube structure made of glass is used as heat exchanger. Water flows up inside helical tube and the high temperature oil flows down in the outside tube. The oscillation of the dryout point was observed, that is mainly caused by intensive nucleate boiling near the dryout point and evaporation of thin liquid film flowing along the surface. The effects of experimental parameters, such as oil temperature, water temperature, water flow rate, diameter and curvature of the tube, on amplitude and cycle of oscillation were experimentally grasped.
Oba, Takashi*; Ishikawa, Tetsuo*; Nagai, Haruyasu; Tokonami, Shinji*; Hasegawa, Arifumi*; Suzuki, Gen*
no journal, ,
no abstracts in English
alpha air monitor in a harsh environmentTsubota, Yoichi; Kimura, Yasuhisa; Nagai, Yuya; Kojima, Sho*; Tokonami, Shinji*; Nakagawa, Takahiro
no journal, ,
