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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.
Nakada, Akira; Kanai, Katsuta; Seya, Natsumi; Nishimura, Shusaku; Futagawa, Kazuo; Nemoto, Masashi; Tobita, Keiji; Yamada, Ryohei*; Uchiyama, Rei; Yamashita, Daichi; et al.
JAEA-Review 2022-078, 164 Pages, 2023/03
JAEA-Review-2022-078.pdf:2.64MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2021 to March 2022. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.
Nakada, Akira; Nakano, Masanao; Kanai, Katsuta; Seya, Natsumi; Nishimura, Shusaku; Nemoto, Masashi; Tobita, Keiji; Futagawa, Kazuo; Yamada, Ryohei; Uchiyama, Rei; et al.
JAEA-Review 2021-062, 163 Pages, 2022/02
JAEA-Review-2021-062.pdf:2.87MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2020 to March 2021. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.
Nakano, Masanao; Fujii, Tomoko; Nemoto, Masashi; Tobita, Keiji; Seya, Natsumi; Nishimura, Shusaku; Hosomi, Kenji; Nagaoka, Mika; Yokoyama, Hiroya; Matsubara, Natsumi; et al.
JAEA-Review 2020-069, 163 Pages, 2021/02
JAEA-Review-2020-069.pdf:4.78MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2019 to March 2020. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.
Okuno, Mitsuru*; Nagaoka, Shinji*; Kokubu, Yoko; Nakamura, Toshio*; Kobayashi, Tetsuo*
Fukuoka Daigaku Rigaku Shuho, 48(1), p.1 - 5, 2018/03
Kuju volcanic group, located in central Kyushu, Japan, consists of over twenty volcanoes (lava domes as well as small stratovolcanoes). The Kurodake is largest lava dome with a volume of 1.6 km
, and generated Kurodake pyroclastic-flow (Kj-Kd) and ash-fall (Kj-KdA) deposits. To refine age of the Kurodake eruption, we conducted radiocarbon dating of a charcoal fragment in the Kj-Kd with an AMS system at Tono Geoscience Center, JAEA. The obtained 
C date, 1505
40 BP, can correspond to 1310-1423 cal BP (probability= 74.6%), 1430-1442 cal BP (2.4%) and 1456-1521 cal BP (23.0%) in 2
confidence level. The medium probability date, 1391 cal BP, is consistent with the stratigraphy and gives the reliable age for the Kj-Kd.
Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Nemoto, Masashi; Tobita, Keiji; Hosomi, Kenji; Nagaoka, Mika; Hokama, Tomonori; Nishimura, Tomohiro; Koike, Yuko; et al.
JAEA-Review 2017-028, 177 Pages, 2018/01
JAEA-Review-2017-028.pdf:3.61MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2016 to March 2017. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Electric Power Company Holdings, Inc. in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and were exceeded the normal range of fluctuation in the monitoring, were evaluated.
Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Hosomi, Kenji; Nagaoka, Mika; Hokama, Tomonori; Yokoyama, Hiroya; Nishimura, Tomohiro; Matsubara, Natsumi; Maehara, Yushi; et al.
JAEA-Review 2016-035, 179 Pages, 2017/03
JAEA-Review-2016-035.pdf:4.2MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2015 to March 2016. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Electric Power Company Holdings, Inc. in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and were exceeded the normal range of fluctuation in the monitoring, were evaluated.
Okuno, Mitsuru*; Nagaoka, Shinji*; Kokubu, Yoko; Nakamura, Toshio*; Kobayashi, Tetsuo*
Radiocarbon, 59(2), p.483 - 488, 2017/00
Times Cited Count：3 Percentile：14.08(Geochemistry & Geophysics)We present here results of AMS C dating to refine the history of the middle and western parts of the Kuju Volcanic Group, located in middle Kyushu, Japan, which consists of more than 20 lava domes and cones. C dating has conducted by AMS (JAEA-AMS-TONO) under the Common-Use Facility Program of JAEA. The Handa PF deposits, which are products of the largest eruption of the group, were dated to 
53.5 ka BP. The Shirani and Muro PF deposits, which are block-and-ash flows, were dated to 44 to 
50 cal ka BP and 3539 cal ka BP, respectively. These ages can be correlated with the TL ages for the lava domes. Therefore, both TL and C methods can be useful tools in establishing the eruptive sequence of lava domes and pyroclastic flows. This study also demonstrates that these eruptive activities occurred after the Handa pfl, the biggest eruption during the last 150 kyrs without a significant time interval.
Watanabe, Hitoshi; Nakano, Masanao; Fujita, Hiroki; Takeyasu, Masanori; Mizutani, Tomoko; Isozaki, Tokuju*; Nagaoka, Mika; Hokama, Tomonori; Yokoyama, Hiroya; Nishimura, Tomohiro; et al.
JAEA-Review 2015-034, 175 Pages, 2016/03
JAEA-Review-2015-034.pdf:8.13MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2014 to March 2015. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co. in March 2011.
Nagaoka, Mika; Yokoyama, Hiroya; Matsubara, Natsumi; Fujita, Hiroki; Nakano, Masanao; Watanabe, Hitoshi
KEK Proceedings 2015-4, p.214 - 218, 2015/11
The radiological impact of the radionuclides released from the Fukushima Daiichi Nuclear Power Station to the sea offshore of Ibaraki has been studied in this research. Fifty-one seabed sediments were collected in 2012, 2013 and 2014, respectively. Then, all samples were measured for the activities of 
Cs and 
Cs and some samples were analyzed for the activities of 
Sr. The results indicated that the activities of Cs and Cs were elevated by the accident and showed a decreasing tendency between 2012 and 2014. The tendency of activity in Kuji Riverestuary area was different from Ibaraki coast area. The difference could be caused by geological feature and grain size of seabed sediment etc. On the other hand, Sr activities were ND-0.26 Bq/kg dry. It was no correlation between Sr and Cs activity. The Sr activity released by the accident was small influence on seabed sediment collected around sea offshore of Ibaraki.
Nagaoka, Mika; Yokoyama, Hiroya; Fujita, Hiroki; Nakano, Masanao; Watanabe, Hitoshi; Sumiya, Shuichi
Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1305 - 1308, 2015/02
Times Cited Count：16 Percentile：79.46(Chemistry, Analytical)Various kinds of radionuclides were released into the atmosphere and the sea from the Fukushima Daiichi Nuclear Power Plant on Tokyo Electric Power Co. (TEPCO) by the accident and then reached around our laboratories. Therefore the accident influence on our environment was investigated to measure the concentrations of cesium-134 (Cs), cesium-137 Cs, strontium-90 (Sr) and plutonium isotopes in seabed sediments. The values for Cs ranged from 6.1 to 300 Bq/kg (dry wt) and the ratio of Cs /Cs ranged from 0.48 to 0.77. The highest point of Cs concentration was observed at the northernmost station near Kitaibaraki City and the concentration was similar to report by MEXT.
Watanabe, Hitoshi; Nakano, Masanao; Fujita, Hiroki; Takeyasu, Masanori; Mizutani, Tomoko; Isozaki, Tokuju; Morisawa, Masato; Nagaoka, Mika; Hokama, Tomonori; Yokoyama, Hiroya; et al.
JAEA-Review 2014-042, 175 Pages, 2015/01
JAEA-Review-2014-042.pdf:10.89MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2013 to March 2014. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Co. in March 2011.
Nagaoka, Mika; Yokoyama, Hiroya; Fujita, Hiroki; Nakano, Masanao; Watanabe, Hitoshi; Sumiya, Shuichi
KEK Proceedings 2014-7, p.194 - 200, 2014/11
no abstracts in English
Sumiya, Shuichi; Watanabe, Hitoshi; Miyagawa, Naoto; Nakano, Masanao; Nakada, Akira; Fujita, Hiroki; Takeyasu, Masanori; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; et al.
JAEA-Review 2013-056, 181 Pages, 2014/03
JAEA-Review-2013-056.pdf:6.22MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2012 to March 2013. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Co. in March 2011.
Nagaoka, Mika; Fujita, Hiroki; Nakano, Masanao; Watanabe, Hitoshi; Sumiya, Shuichi
Hoken Butsuri, 48(4), p.165 - 166, 2013/12
no abstracts in English
Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Nagaoka, Mika; et al.
JAEA-Review 2013-009, 195 Pages, 2013/06
JAEA-Review-2013-009.pdf:3.35MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2011 to March 2012. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant on Tokyo Electric Power Co. in March 2011.
Nagaoka, Mika; Fujita, Hiroki; Nakano, Masanao; Watanabe, Hitoshi; Sumiya, Shuichi
Hoken Butsuri, 48(2), p.104 - 113, 2013/06
Monthly deposition samples were collected in the NCL which is located at about 115km south of the Fukushima Daiichi NPP, and the radioactive nuclides were analyzed. Although radionuclides such as 
I (T
=8.02 days), 
Te-
Te (T=33.6 days) and 
Te-I (T=3.2 days) with Cs and Cs were observed by 
spectrometry at the early time of the Fukushima Daiichi NPP accident, only Cs and Cs were detected as of September 2012. The annual deposition of Cs and Cs were about 19,000 and 17,000 Bq/m
, respectively in March 2011 - February 2012 after the accident. Moreover, Sr was detected in some samples. Monthly Sr deposition in March 2011 was 5.1 Bq/m month and then decreased after that. On the other hand, 
Pu concentration was the same level with the concentration before the accident.
Nagaoka, Mika; Nakano, Masanao; Fujita, Hiroki; Watanabe, Hitoshi; Sumiya, Shuichi
Dai-55-Kai Kankyo Hoshano Chosa Kenkyu Seika Rombun Shorokushu (Heisei-23-Nendo), p.7 - 8, 2013/03
no abstracts in English
Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Kokubun, Yuji; et al.
JAEA-Review 2012-015, 166 Pages, 2012/05
JAEA-Review-2012-015.pdf:3.53MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2010 to March 2011. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant on Tokyo Electric Power Co. in 2011 March. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data exceeded the normal range of fluctuation by the accidental release was evaluated in the appendices.
Furuta, Sadaaki; Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Imaizumi, Kenji; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Mizutani, Tomoko; Morisawa, Masato; et al.
JAEA-Review 2011-035, 89 Pages, 2011/08
JAEA-Review-2011-035.pdf:2.97MB
As a correspondence to the accident at the Fukushima Daiichi Nuclear Power Plant, the environmental radiation monitoring was performed at the Nuclear Fuel Cycle Engineering Laboratories, JAEA. This report presented the measurement results of ambient radiation dose rate, radioactivity concentration in the air and radioactivity concentration in fallout and meteorological observation result until May 31, 2011. The ambient radiation dose rate increased, with the peak dose rate of several thousand nGy/h at 7 o'clock in March 15, at 5 o'clock in March 16, and at 4 o'clock in March 21. The variation on the radioactivity concentration in the air and in fallout showed the almost same tendency as that of the dose rate. The concentration ratio of I-131/Cs-137 in the air increased to about 100. The dose was estimated resulting from internal exposure due to inhalation.
