Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Nagai, Haruyasu; Chino, Masamichi*
Ten Hasseigen Karano Mesosukeru Kakusan Shumireshon; Fukushima Daiichi Genshiryoku Hatsudensho Jiko O Fumaete (Kisho Kenkyu Noto Dai-248-Go), p.1 - 58, 2023/09
no abstracts in English
Suzuki, Gen*; Ishikawa, Tetsuo*; Oba, Takashi*; Hasegawa, Arifumi*; Nagai, Haruyasu; Miyatake, Hirokazu*; Yoshizawa, Nobuaki*
Journal of Radiation Research (Internet), 63(6), p.796 - 804, 2022/11
Times Cited Count：2 Percentile：42.05(Biology)To elucidate the association between radiation dose and thyroid cancer after the 2011 Fukushima Daiichi Nuclear Power Station (FDNPS) accident, it is essential to estimate individual thyroid equivalent doses (TEDs) to children. In a previous study, we reported a methodology for reconstructing TEDs from inhalation based on individual behavioural survey sheets combined with a spatiotemporal radionuclides database constructed by an atmospheric transport, diffusion, and deposition model (ATDM). In the present study, we further refined our methodology and estimated the combined TEDs from inhalation and ingestion among children in 16 municipalities around the nuclear power station utilizing 3,256 individual whereabouts questionnaire survey sheets. Distributions of estimated TEDs were similar to estimates based on direct thyroid measurements in 1080 children in Iwaki City, Kawamata Town, Iitate Village, and Minamisoma City. Mean TEDs in 1-year-old children ranged from 1.3 mSv in Date City to 14.9 mSv in Odaka Ward in Minamisoma City, and the 95th percentiles varied from 2.3 mSv in Date City to 28.8 mSv in Namie Town. In the future, this methodology can be useful for a case-control study of thyroid cancer after the FDNPS accident.
Nagai, Haruyasu
Fission Product Behavior under Severe Accident, p.112 - 116, 2021/05
no abstracts in English
Nagai, Haruyasu; Katata, Genki; Terada, Hiroaki; Chino, Masamichi
no journal, ,
JAEA has been developing simulation system to predict the environmental transport of radionuclide. SPEEDI was developed and it is currently operational as a emergency response system of Japan. By expanding SPEEDI, WSPEEDI was constructed with a combination of atmospheric model MM5 and particle dispersion model GEARN. WSPEEDI has been applied for analysis on the environmental impact by the Fukushima Daiichi NPP accident. At first, the source term of radionuclide discharged into the atmosphere was estimated by coupling monitoring data with atmospheric dispersion simulations. By using this source term, detailed analysis on the local and regional atmospheric dispersion has been carried out. The source term was also used by the UNSCEAR for the atmospheric dispersion analysis and dose estimation. Recently, we re-estimated source term by using newly released data and modified WSPEEDI. The simulation well reproduced the local and regional deposition pattern of 
I and 
Cs.
Nagai, Haruyasu
no journal, ,
no abstracts in English
Nagai, Haruyasu; Terada, Hiroaki; Tsuzuki, Katsunori; Katata, Genki; Ota, Masakazu; Furuno, Akiko; Kadowaki, Masanao; Akari, Shusaku*
no journal, ,
no abstracts in English
Terada, Hiroaki; Nagai, Haruyasu
no journal, ,
no abstracts in English
Cs due to the Fukushima Daiichi Nuclear Power Station accident based on the intercomparison of atmospheric dispersion modelsMorino, Yu*; Kitayama, Kyo*; Takigawa, Masayuki*; Nakajima, Teruyuki*; Hayami, Hiroshi*; Nagai, Haruyasu; Terada, Hiroaki; Saito, Kazuo*; Shimbori, Toshiki*; Kajino, Mizuo*; et al.
no journal, ,
For the evaluation of the validity and variability of atmospheric transport model results, we compared results of seven models submitted for the model inter-comparison project of Science Council of Japan to simulate Cs released from the Fukushima Daiichi Nuclear Power Plant. Model reproducibility was assessed with the observed hourly atmospheric concentrations of Cs in Tohoku and Kanto regions. Among nine plumes from 12 to 21 in March 2011, performance of the models was the best for the plume which dispersed over the Kanto region in 15 March. The models generally reproduced the observed Cs concentrations in plumes which widely spread inland of Tohoku or Kanto regions. By contrast, the models largely underestimated the observed Cs concentrations for the case which passed coastal areas of Japan. Ensemble average of seven models showed reasonable performance for most of plumes, and no individual models reproduced better than the ensemble average.
Terada, Hiroaki; Nagai, Haruyasu
no journal, ,
For the assessment of the radiological doses to the public due to the atmospheric discharge of radioactive materials during the Fukushima Daiichi Nuclear Power Station accident, the spatiotemporal distribution of radioactive materials in the environment are reconstructed by atmospheric dispersion simulation with the improved WSPEEDI. In this study, the influence of chemical form of I (particle, inorganic and organic gas) in source term on the simulated results was analyzed to assess the uncertainty of the simulation. From the sensitivity test with the chemical form composition, surface deposition distribution of I was influenced according to the property of the chemical forms to deposition processes, whereas time-integrated air concentration was less influenced. From the comparison with the measurement, the surface deposition simulated with the source term in Katata et al. (2015) had a good reproducibility compared with those with extreme gas to particle ratios.
Nagai, Haruyasu; Terada, Hiroaki
no journal, ,
no abstracts in English
Terada, Hiroaki; Nagai, Haruyasu
no journal, ,
no abstracts in English
Nagai, Haruyasu; Terada, Hiroaki; Tanimori, Toru*
no journal, ,
no abstracts in English
Oba, Takashi*; Ishikawa, Tetsuo*; Nagai, Haruyasu; Tokonami, Shinji*; Hasegawa, Arifumi*; Suzuki, Gen*
no journal, ,
no abstracts in English
Oba, Takashi*; Ishikawa, Tetsuo*; Nagai, Haruyasu; Hasegawa, Arifumi*; Fukaya, Kigen*; Suzuki, Gen*
no journal, ,
no abstracts in English
Furuno, Akiko; Kijima, Yuichi; Tomita, Yutaka; Yamamoto, Yoichi
no journal, ,
This research aims at source term estimations of high-concentration detection events of Xe-133, which were observed at the CTBT IMS (International Monitoring System) Takasaki radionuclide monitoring station from the viewpoint of atmospheric dispersion analysis. Japan Atomic Energy Agency operates JPX38 in the Takasaki radionuclide station for noble gas monitoring, and conducts temporary measurement project of radioxenon at Horonobe in Hokkaido (JPX81) and Mutsu in Aomori (MUX88) as a part of the noble gas joint measurement project with CTBTO. The high-concentration detection events were frequently occurred not only at the JPX38 but also at the JPX81from the end of 2020 to January 2021. In the presentation, we will describe the source term estimation analysis of these high-concentration detection events, and discuss the relationship of the events between two stations.
Oba, Takashi*; Ishikawa, Tetsuo*; Miyatake, Hirokazu*; Nagai, Haruyasu; Hasegawa, Arifumi*; Yoshizawa, Nobuaki*; Suzuki, Gen*
no journal, ,
no abstracts in English
Suzuki, Gen*; Oba, Takashi*; Ishikawa, Tetsuo*; Hasegawa, Arifumi*; Nagai, Haruyasu; Yoshizawa, Nobuaki*; Miyatake, Hirokazu*
no journal, ,
no abstracts in English
Miyatake, Hirokazu*; Yoshizawa, Nobuaki*; Suzuki, Gen*; Nagai, Haruyasu; Oba, Takashi*; Hasegawa, Arifumi*; Ishikawa, Tetsuo*; Regalado, Mariko*
no journal, ,
no abstracts in English
Nagai, Haruyasu
no journal, ,
no abstracts in English
