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Futagawa, Kazuo; Kashimura, Keita; Sato, Daiki*; Kawasaki, Masatsugu
JAEA-Data/Code 2022-011, 75 Pages, 2023/03
JAEA-Data-Code-2022-011.pdf:1.49MB
These statistical results are based on the meteorological data observed at the Nuclear Science Research Institute in Japan Atomic Energy Agency and statistically processed according to "The guideline of meteorological statistics for the safety analysis of nuclear power reactor" (Nuclear Safety Commission on January 28, 1982; revised on March 29, 2001). The statistics are based on 5 years of meteorological data, from January 2017 to December 2021. These are statistical results of wind direction, wind speed, atmospheric stability, etc., which are used for dose assessment of the general public due to radioactive materials discharged into the atmosphere from nuclear reactor facilities.
Kashimura, Keita; Shoro, Takuya*; Futagawa, Kazuo; Kawasaki, Masatsugu
JAEA-Data/Code 2021-020, 218 Pages, 2022/03
JAEA-Data-Code-2021-020.pdf:2.51MB
These statistical results are based on the meteorological data observed at the Nuclear Science Research Institute in Japan Atomic Energy Agency and statistically processed according to "The guideline of meteorological statistics for the safety analysis of nuclear power reactor" (Nuclear Safety Commission on January 28, 1982; revised on March 29, 2001). The statistics are based on 15 years of meteorological data, from January 2006 to December 2020, processed into five-year periods. These are statistical results of wind direction, wind speed, atmospheric stability, etc., which are used for dose assessment of the general public due to radioactive materials discharged into the atmosphere from nuclear reactor facilities.
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
Nakano, Masanao; Hosomi, Kenji; Nishimura, Shusaku; Matsubara, Natsumi; Okura, Takehisa; Kuramochi, Akihiko; Kawasaki, Masatsugu; Takeuchi, Erina; Fujii, Yutaka*; Jinno, Tsukasa*; et al.
Hoken Butsuri (Internet), 55(2), p.102 - 109, 2020/06
After the Fukushima-Daiichi Nuclear Power Station (1F) Accident in March 2011, the increase was significantly observed in a part of the result of the environmental radiation monitoring in Ibaraki prefecture. "The review meeting of the environmental effect from 1F accident" was established to discuss technically the fluctuation of monitoring data. The review meeting collected the monitoring data from the four nuclear operators, and discussed a fluctuating trend, 
Cs/
Cs activity ratio, and so on. In this report, the results of the dose rate and Cs in fallout, surface soil, flatfish and seabed sediment are introduced. Also the problem solving in the review meeting is introduced.
Kawasaki, Masatsugu; Nakajima, Junya; Yoshida, Keisuke; Kato, Saori; Nishino, Sho; Nozaki, Teo; Nakagawa, Masahiro; Tsunoda, Junichi; Sugaya, Yuki; Hasegawa, Rie; et al.
JAEA-Data/Code 2017-004, 57 Pages, 2017/03
JAEA-Data-Code-2017-004.pdf:2.34MB
In emergency situation of nuclear facilities, we need to estimate the radiation dose due to radiation and radioactivity to grasp the influence range of the accident in the early stage. Therefore, we prepare the case studies of dose assessment for public exposure dose and personal exposure dose and contribute them to emergency procedures. This document covers about accidents of nuclear facilities in Nuclear Science Research Institute and past accident of nuclear power plant, and it can be used for inheritance of techniques of emergency dose assessment.
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.
Kawasaki, Masatsugu; Watanabe, Yoko
Hoken Butsuri, 47(2), p.124 - 129, 2012/06
no abstracts in English
Okura, Takehisa; Oishi, Tetsuya; Taki, Mitsumasa; Shibanuma, Yukio; Kikuchi, Masamitsu; Akino, Hitoshi; Kikuta, Yasuaki; Kawasaki, Masatsugu; Saegusa, Jun; Tsutsumi, Masahiro; et al.
JAEA-Data/Code 2012-010, 37 Pages, 2012/05
JAEA-Data-Code-2012-010.pdf:2.28MB
Due to the accident at Fukushima Daiichi Nuclear Power Plant caused by the 2011 off the Pacific coast of Tohoku Earthquake occurred at 11th March 2011, the emergency environmental radiation monitoring was conducted at Nuclear Science Research Institute, Japan Atomic Energy Agency (JAEA). This report provides the monitoring results of ambient 
-ray dose rate and atmospheric radioactivity concentration until the beginning of June 2011. Some anthropogenic radionuclides such as Cs-134, Cs-137, I-131, I-132, Te-132, Xe-133 and others were detected from air samples. The atmospheric radioactivity concentrations varied with some peaks corresponded with that of ambient -ray dose rate after 15th March 2011. Composition of each peak showed various characteristic. Internal exposure caused by inhalation was estimated from the observed atmospheric radioactivity.
Fujita, Hiroki; Nagaoka, Mika; Kono, Takahiko; Takeyasu, Masanori; Kawasaki, Masatsugu; Okura, Takehisa; Tsujimura, Norio; Sumiya, Shuichi; Momose, Takumaro; Furuta, Sadaaki
Proceedings of 13th International Congress of the International Radiation Protection Association (IRPA-13) (Internet), 7 Pages, 2012/05
The nuclear accident at Fukushima Dai-ichi Nuclear Power Station of Tokyo Electric Power Co. (TEPCO) was caused by the Tohoku District-off the Pacific Ocean Earthquake. Various kinds of radionuclides were released from the power station right after the accident occurred and then reached our laboratories. Therefore, environmental monitoring was reinforced by observation of air absorbed dose rate, periodic collection of airborne dust, precipitation. The collected samples were used to determine radioactivity of ray emitters by High pure Germanium semiconductor detector. Moreover, rainwater and humidity were collected to do the usual routine monitoring. In some samples, 
Sr, 
I, Cs and Cs were detected with radioactivity released from the Fukushima station. In other samples such as seawater, seabed soil and etc., similar radionuclides were detected including the influence of the accident.
Yamasoto, Kotaro; Kawasaki, Masatsugu; Kawamatsu, Yorimitsu
no journal, ,
no abstracts in English
for the determination of radiostrontium in leafy vegetablesWatanabe, Yoko; Kawasaki, Masatsugu
no journal, ,
no abstracts in English
Kawasaki, Masatsugu; Watanabe, Yoko; Shimizu, Rumi
no journal, ,
no abstracts in English
Watanabe, Yoko; Kawasaki, Masatsugu
no journal, ,
no abstracts in English
Kawasaki, Masatsugu; Watanabe, Yoko; Yamamoto, Hideaki
no journal, ,
no abstracts in English
Oishi, Tetsuya; Kikuchi, Masamitsu; Takahashi, Kenichi; Okura, Takehisa; Akino, Hitoshi; Kawasaki, Masatsugu; Kikuta, Yasuaki; Saegusa, Jun; Shibanuma, Yukio; Yamamoto, Hideaki
no journal, ,
no abstracts in English
Kawasaki, Masatsugu; Omori, Shuhei; Taki, Mitsumasa; Oishi, Tetsuya
no journal, ,
no abstracts in English
Okura, Takehisa; Omori, Shuhei; Kawasaki, Masatsugu
no journal, ,
Ambient gamma dose rate has monitored at the several sites around nuclear facilities of Nuclear Science Research Center, JAEA in Tokai, Ibaraki. Effect of the Fukushima accident prevents from monitoring of influence from the nuclear facilities. Chronicle variation of ambient gamma dose rate for 5 years after the Fukushima accident was analyzed statistically by dividing components of the Fukushima accident and extracting environmental factor of it. Variation of the environmental factor was evaluated quantitatively and verified. This result will be basic material to optimize the monitoring of the dose rate by distinguishing influence from nuclear facilities from the effect of the Fukushima accident.
Kashimura, Keita; Kawasaki, Masatsugu; Okura, Takehisa
no journal, ,
In nuclear emergency response involving atmospheric release, the supplementary reference materials of the Nuclear Emergency Response Guideline require dust monitor to monitor radiation situation in the environment to be able to detect facility-induced releases of about 5 Bq/m
for detecting unexpected releases earlier, and to determine the spatial distribution of radioactive materials in the air during emergencies, the difference in the gross beta activity concentration measured every 10 minutes is used. In this study, method of monitoring radioactive plume by dust monitor was investigated, and it was confirmed that the method can discriminate facility-induced releases of about 5 Bq/ m against variation of natural radionuclides. Furthermore, capability of the dust monitor corresponding to radioactive plume was confirmed. According to the time series comparison between the gross beta radioactivity concentration measured by the dust monitor and the radioactive concentration analyzed from gamma-ray emitted nuclides in the air following the Fukushima Daiichi Nuclear Power Plant accident (1F accident), a good correlation was observed and it was found that the dust monitor responded accurately to the fluctuation of the concentration in the radioactive plume. And it was confirmed that it was possible to discriminate the incremental difference in gross beta radioactivity caused by the facility of about 5 Bq/ m against the slight increase in concentration caused by the 1F accident.
