Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2022

Kokubun, Yuji; Nakada, Akira; Seya, Natsumi; Nagaoka, Mika; Koike, Yuko; Kubota, Tomohiro; Hirao, Moe; Yoshii, Hideki*; Otani, Kazunori*; Hiyama, Yoshinori*; et al.

JAEA-Review 2023-052, 118 Pages, 2024/03

JAEA-Review-2023-052.pdf:3.67MB

Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and by law of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2022. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.

Historical changes and Correspondence to Research and Test Reactors New Regulatory Standards for Monitoring Post in Oarai Research and Development Institute, JAEA

Hamaguchi, Takumi; Yamada, Junya; Komatsuzaki, Naoya*; Hatakeyama, Takumi; Seya, Natsumi; Muto, Yasunobu; Miyauchi, Hideaki; Hashimoto, Makoto

JAEA-Technology 2022-038, 65 Pages, 2023/03

JAEA-Technology-2022-038.pdf:4.3MB

New regulatory requirements were developed taking into account the lessons-learnt from the accident at Fukushima Daiichi Nuclear Power Station on March 2011. The new regulatory standards required that monitoring posts should be diversified in transmission systems and equipped with backup power supply equipment for design basis accidents. In this report, we look back on the history of monitoring posts in Oarai Research and Development Institute, explained the application for the permission of reactor installment license, application for approval of the design and construction method, pre-use operator's inspection and improvement design of monitoring posts. This report also includes about inspection based on act on special measures concerning nuclear emergency preparedness and the installation of KURAMA-II, which was carried out in conjunction with the improvement of monitoring post for new regulatory standards. As an appendix, application document for approval of the design and construction method are included.

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2020

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.

Improvement of estimation of I concentrations in the air using data measured by monitoring posts applied by determination of passing-through time of plume using noble gas counts

Yamada, Junya; Hashimoto, Makoto; Seya, Natsumi; Haba, Risa; Muto, Yasunobu; Shimizu, Takehiko; Takasaki, Koji; Yokoyama, Sumi*; Shimo, Michikuni*

Hoken Butsuri, 52(1), p.5 - 12, 2017/03

https://doi.org/10.5453/jhps.52.5

The purpose of this study is to improve a quick method for estimation of I concentrations in the air using data measured by monitoring posts in case that a nuclear disaster occurs. In this method, I concentrations were estimated by multiplying I count rates of cloud-shine measured with NaI (Tl) detector by concentration conversion factor. A previous study suggested that it was difficult to determine passing-through time of plume from temporal change of I count rates or dose rate. Our study applies the method for estimating passing-through time of plume from temporal change of noble gas counts. The I concentrations in the air at Oarai center, Japan Atomic Energy Agency resulting from the accident at the Fukushima Daiichi Nuclear Power Plant were estimated by proposal technique. The result of comparison of this method with sampling method for I concentrations in the air were within factor 3.

Applicability of meteorological statistics over a 5-year period to evaluation of annual average of radionuclide concentration in surface air; Based on meteorological statistics for 20 years at Oarai Research and Development Center, JAEA

Seya, Natsumi; Hashimoto, Makoto; Nemoto, Koji*; Shimizu, Takehiko; Takasaki, Koji

Hoken Butsuri, 49(1), p.29 - 38, 2014/03

http://doi.org/10.5453/jhps.49.29

http://doi.org/10.5453/jhps.49.1

Evaluation of annual average of radionuclide concentration in surface air obtained from atmospheric dispersion factor is intended to determine a public dose as a primary source for the safety analysis of nuclear facilities in normal operation. Oarai Research and Development Center (ORDC) of the JAEA have used fixed 5-year meteorological statistics for derivation of atmospheric dispersion factors as average conditions. To show that the meteorological statistics for any 5-year period could be used as representative data for evaluation of average conditions, annual average (1-year average) and 5-year average of evaluated radionuclide concentrations derived from the meteorological data observed from 1991 to 2010 at ORDC were analyzed. The fluctuations of evaluated radionuclide concentrations of any 5-year averages were smaller than those of 1-year averages during 20 years, and any 5-year averages contained no rejections by the F-test (5% significance level). It means that any 5-year averages of radionuclide concentration evaluations are well representative for the safety analysis under normal condition in ORDC.

Consideration of the rising count rate of the water monitor at rainfall time

Haba, Risa; Yamada, Junya; Seya, Natsumi; Muto, Yasunobu; Shimizu, Takehiko; Takasaki, Koji

no journal, , 

no abstracts in English

Environmental radiation monitoring in JAEA O-arai after Fukushima Daiichi NPP accident; Measuring results of monitoring post

Yamada, Junya; Seya, Natsumi; Haba, Risa; Muto, Yasunobu; Shimizu, Takehiko; Takasaki, Koji

no journal, , 

no abstracts in English

Regional contribution through the environmental monitoring which was conducted by JAEA Oarai, followed by the Fukushima Dai-ichi Nuclear Disaster

Muto, Yasunobu; Yamada, Junya; Seya, Natsumi; Shimizu, Takehiko; Takasaki, Koji; Nakajima, Akemi

no journal, , 

no abstracts in English

Actual effect on the radiation dose rate caused by difference of the detector height above the ground in nuclear emergency monitoring

Haba, Risa; Yamada, Junya; Seya, Natsumi; Muto, Yasunobu; Hashimoto, Makoto; Shimizu, Takehiko; Takasaki, Koji

no journal, , 

no abstracts in English

Comparison of I-131 concentrations in atmosphere estimated from pulse-height distribution observed by NaI(Tl) detector at monitoring posts and evaluated from air sampling

Yamada, Junya; Seya, Natsumi; Haba, Risa; Muto, Yasunobu; Hashimoto, Makoto; Shimizu, Takehiko; Takasaki, Koji; Yokoyama, Sumi*; Shimo, Michikuni*

no journal, , 

no abstracts in English

Latest situation and future targets of radiation countermeasures around water and woods environments in a priority investigation area on radioactive materials contamination

Iimoto, Takeshi*; Maedera, Ikuhiko*; Nunokawa, Jun*; Matsuzawa, Hajime*; Kurokawa, Sumihiko*; Yanagawa, Yukihide*; Someya, Seiichi*; Hashimoto, Makoto; Seya, Natsumi; Okawa, Yasuhisa; et al.

no journal, , 

no abstracts in English