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Nagai, Haruyasu; Furuta, Yoshihiro*; Nakayama, Hiromasa; Satoh, Daiki
Journal of Nuclear Science and Technology, 60(11), p.1345 - 1360, 2023/11
Times Cited Count：2 Percentile：59.55(Nuclear Science & Technology)A novel monitoring method for the quantitative visualization of 3D distribution of a radioactive plume and source term estimation of released radionuclides is proposed and its feasibility is demonstrated by preliminary test. The proposed method is the combination of gamma-ray imaging spectroscopy with the Electron Tracking Compton Camera (ETCC) and real-time high-resolution atmospheric dispersion simulation based on 3D wind observation with Doppler lidar. The 3D distribution of a specific radionuclide in a target radioactive plume is inversely reconstructed from line gamma-ray images from each radionuclide by several ETCCs located around the target by harmonizing with the air concentration distribution pattern of the plume predicted by real-time atmospheric dispersion simulation. A prototype of the analysis method was developed, showing a sufficient performance in several test cases using hypothetical data generated by numerical simulations of atmospheric dispersion and radiation transport.
Togawa, Orihiko; Okura, Takehisa; Kimura, Masanori; Nagai, Haruyasu
JAEA-Review 2021-021, 61 Pages, 2021/11
JAEA-Review-2021-021.pdf:3.72MB
Triggered by the Fukushima Daiichi Nuclear Power Station accident, there have been a lot of arguments among various situations and levels about utilization of atmospheric dispersion models for a nuclear emergency preparedness and response. Most of these arguments, however, were alternative and extreme discussions on whether predictions by computational models could be applied or not for protective measures in a nuclear emergency, and it was hard to say that these arguments were politely conducted, based on scientific verification in an emergency response. It was known, on the other hand, that there were not a few potential users of atmospheric dispersion models and/or calculation results by the models within the Japan Atomic Energy Agency (JAEA) and outside. However, they seemed to have a lack of understanding and a misunderstanding on proper use of different kinds of atmospheric dispersion models. This report compares an outline of models and calculation method in atmospheric dispersion models for a nuclear emergency preparedness and response, with a central focus on the models which have been developed and used in the JAEA. Examples of calculations by these models are also described in the report. This report aims at contributing to future consideration and activities for potential users of atmospheric dispersion models within the JAEA and outside.
Hirayama, Hideo*; Kawasaki, Masatsugu; Matsumura, Hiroshi*; Okura, Takehisa; Namito, Yoshihito*; Sanami, Toshiya*; Taki, Mitsumasa; Oishi, Tetsuya; Yoshizawa, Michio
Insights Concerning the Fukushima Daiichi Nuclear Accident, Vol.4; Endeavors by Scientists, p.295 - 307, 2021/10
Sanada, Yukihisa; Ochi, Kotaro; Ishizaki, Azusa
JAEA-Research 2020-006, 60 Pages, 2020/07
JAEA-Research-2020-006.pdf:4.84MB
At the accident of nuclear facilities, a prediction of the behavior of released radioactive plume is indispensable to make a decision on a refuge plan of inhabitants. Currently, prediction system which is based on atmospheric dispersion simulation has been implemented as a tool of the atomic energy disaster prevention. However, the direct measurement method of the radioactive plume has not existed. In this study, some component technologies were developed for the establishment of direct measurement methods of radioactive plume using unmanned aerial vehicle whose technological innovation is remarkable. In addition, the spray test using mock aerosol was conducted to obtaining the deposition rate to the airplane body. The algorism of making a flight plan was developed based on a prediction model of the radioactive plume. This report summarized the outcome of the last year of the three-year plan.
Sanada, Yukihisa; Nishizawa, Yukiyasu*; Ochi, Kotaro; Yuki, Yoichi*; Ishizaki, Azusa; Osada, Naoyuki*
JAEA-Research 2018-009, 48 Pages, 2019/01
JAEA-Research-2018-009.pdf:14.77MB
At the accident of nuclear facilities, a prediction of the behavior of released radioactive plume is indispensable to make a decision on a refuge plan of inhabitants. Currently, prediction system which is based on atmospheric dispersion simulation has been implemented as a tool of the atomic energy disaster prevention. However, the direct measurement method of the radioactive plume has not existed. In this study, some component technologies were developed for the establishment of direct measurement methods of radioactive plume using unmanned aerial vehicle whose technological innovation is remarkable. In addition, the spray test using mock aerosol was conducted to obtaining the deposition rate to the airplane body. The algorism of making a flight plan was developed based on a prediction model of the radioactive plume. This report summarized the outcome of the second year of the three-year plan.
Oba, Masaki; Miyabe, Masabumi; Akaoka, Katsuaki; Wakaida, Ikuo
Japanese Journal of Applied Physics, 55(2), p.022401_1 - 022401_4, 2016/02
Times Cited Count：3 Percentile：13.98(Physics, Applied)We used laser-induced fluorescence imaging with a varying beam focal point to observe ablation plumes from metal and oxide samples of gadolinium. The plumes expand vertically when the focal point is far from the sample surface. In contrast, the plume becomes hemispherical when the focal point is on the sample surface. In addition, the internal plume structure and the composition of the ablated atomic and ionic particles also vary significantly. The fluorescence intensity of a plume from a metal sample is greater than that from an oxide sample, which suggests that the number of monatomic species produced in each plume differs. For both the metal and oxide samples, the most intense fluorescence from atomic (ionic) species is observed with the beam focal point at 3-4 mm (2 mm) from the sample surface.
Hirayama, Hideo*; Kawasaki, Masatsugu; Matsumura, Hiroshi*; Okura, Takehisa; Namito, Yoshihito*; Sanami, Toshiya*; Taki, Mitsumasa; Oishi, Tetsuya; Yoshizawa, Michio
Nihon Genshiryoku Gakkai Wabun Rombunshi, 13(3), p.119 - 126, 2014/09
A method of deducing the I-131 concentration in a radioactive plume from the time history of peak count rates determined from pulse height spectra obtained from an NaI(Tl)scintillation detector employed as a detector of a monitoring post was presented. The concentrations of I-131 in the plumes were estimated from the count rates using the calculated response of the NaI(Tl) detector with egs5 for a model of a plume uniformly containing I-131. This method was applied to the data from the monitoring posts at Nuclear Science Research Institutes of Japan Atomic Energy Agency (JAEA). The estimated time history variation of I-131 concentrations in plumes was in fair agreement with those measured directly by an air sampling method. The difference was less than a factor of 4 for plumes that arrived on March 15 and March 21, indicating relatively high I-131 concentrations among the plumes studied in this work.
Oba, Hironori; Saeki, Morihisa; Yokoyama, Atsushi
Proceedings of Plasma Science Symposium 2005/22nd Symposium on Plasma Processing (PSS-2005/SPP-22), p.331 - 332, 2005/01
A plasma produced by a XeCl laser ablation of boron compound was investigated using ion probes and a quadrupole mass spectrometer. Although the ablated neutral boron atoms had a natural abundance ratio, the isotope ratio of singly ionized boron atoms having a greatly different from the natural abundance ratio was observed. The observed isotope ratio of boron ions was different from the natural abundance.
; Kunugi, Tomoaki;
Dai-32-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu, 0, p.633 - 634, 1995/05
no abstracts in English
Hidaka, Akihide;
Nihon Genshiryoku Gakkai-Shi, 29(11), p.1023 - 1029, 1987/11
no abstracts in English
; ; Yamazawa, Hiromi;
JAERI-M 86-142, 65 Pages, 1986/10
no abstracts in English
Hidaka, Akihide;
Hoken Butsuri, 20, p.33 - 42, 1985/00
no abstracts in English
Radiat.Prot.Dosim., 11(2), p.91 - 94, 1985/00
no abstracts in English
JAERI-M 7127, 14 Pages, 1977/06
no abstracts in English
El-Asaad, H.; Chirayath, S.*; Hecker, S.*; Fuhrmann, M.*
no journal, ,
Oba, Masaki; Miyabe, Masabumi; Akaoka, Katsuaki; Wakaida, Ikuo
no journal, ,
Ablation plume of oxide samples of gadolinium was observed by means of laser-induced fluorescence imaging technique for varying the beam focal point. The observed plume was vertically expanded when the focal point was far from the sample surface; in contrast, it varied to be hemispherical shape when the focal point was on the sample surface. In addition, the internal plume structure and the composition of the ablated atomic and ionic species were also varied significantly.
Nakayama, Hiromasa; Takemi, Tetsuya*; Nagai, Haruyasu
no journal, ,
A significant amount of radioactive material was accidentally discharged into the atmosphere from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) from March 12, 2011. In conducting regional-scale atmospheric dispersion simulations, the nuclear emergency response system based on a meso-scale meteorological model (MM) was used. However, it is impossible to conduct detailed simulations of plume dispersion considering the turbulent effects in a local-scale because buildings, structures, and local terrain variability are not explicitly represented at high grid resolutions in those models. Therefore, an approach to couple an LES-based CFD model with a MM model should be promising. In this study, first we conduct LESs of plume dispersion around the FDNPP under a constant meteorological condition by prescribing constant mean wind velocities and directions at the inlet boundary condition, and then do them under a varying meteorological condition by coupling with a MM model. Our objective is to compare plume dispersion patterns under those different meteorological conditions and evaluate the effectiveness of the coupling computational method.
