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.

2016 Professional Engineer (PE) test preparation course "Nuclear and Radiation Technical Disciplines"

Takahashi, Naoki; Yoshinaka, Kazuyuki; Harada, Akio; Yamanaka, Atsushi; Ueno, Takashi; Kurihara, Ryoichi; Suzuki, Soju; Takamatsu, Misao; Maeda, Shigetaka; Iseki, Atsushi; et al.

Nihon Genshiryoku Gakkai Homu Peji (Internet), 64 Pages, 2016/00

no abstracts in English

Environmental radiation monitoring resulting from the accident at the Fukushima Daiichi Nuclear Power Plant, conducted by Oarai Research and Development Center, JAEA; Results of ambient gamma-ray dose rate, atmospheric radioactivity and meteorological observation

Yamada, Junya; Seya, Natsumi; Haba, Risa; Muto, Yasunobu; Numari, Hideyuki*; Sato, Naomitsu*; Nemoto, Koji*; Takasaki, Hiroichi*; Shimizu, Takehiko; Takasaki, Koji

JAEA-Data/Code 2013-006, 100 Pages, 2013/06

JAEA-Data-Code-2013-006.pdf:12.04MB

This report presents the results of emergency radiation monitoring, including ambient -ray dose rate, atmospheric radioactivity, meteorological observation and estimation of internal exposure resulting from the accident at the Fukushima Daiichi Nuclear Power Plant triggered by the earthquake off the pacific coast of Tohoku on 11th March 2011, conducted by Oarai Research and Development Center (ORDC), Japan Atomic Energy Agency (JAEA) from March to May, 2011. ORDC is located in the central part of Ibaraki prefecture and approximately 130 km southwest of the Fukushima Daiichi Nuclear Power Plant. From around 15th to 21st March, 2011, the ambient -ray dose rate increased and many radioactive nuclides were detected in the atmosphere.

Development of a Real-Time Environmental Radiation Dose Evaluation System for the Vicinity of a Nuclear Facility; A Study of a Real-Time Environmental Radiation Dose Evaluation System

Takeyasu, Masanori; Takeishi, Minoru; Shimizu, Takehiko; Iida, Takao*

Hoken Butsuri, 39(4), p.382 - 390, 2004/00

https://doi.org/10.5453/jhps.39.382

A computer code system was developed to evaluate a real-time environmental radiation dose when radioactive substances were accidentally released from a nuclear facility. The examination of the system was performed by using the data of air absorbed dose rate observed at monitoring stations and monitoring posts around the Tokai Reprocessing Plant when Kr was discharged during its normal operation.

Countermeasure of Electromagnetic Wave Noise at Ionization Chamber Used Monitoring Posts

Hosotani, Risa; Sato, Naomitsu*; Shimizu, Takehiko; KOBAYASHI, Hideo

Saikuru Kiko Giho, (25), p.25 - 32, 2004/00

https://rdreview.jaea.go.jp/gihou/pdf3/n25-03.pdf

To observe the airborne gamma radiation dose rate, monitoring posts are set up to a border of supervised area of JNC-OEC. Measurement values of some ionization chambers set at monitoring posts were increased by unknown origin signal at random times. To probe the cause, measurement of electric field intensity at the ionization chamber and immunity test at anechoic chamber are carry out. Result of examination made clear that measurement values are increased by specific frequency band electromagnetic wave. They were also clearly that ferrite cores and shield tube are effective as eliminate of an electromagnetic wave noise. When ferrite cores are attached to cables of ionization chambers, unknown increase of measurement value doesn't occur.

The 3rd technological meeting of Tokai reprocessing plant

Maki, Akira; ; Taguchi, Katsuya; ; Shimizu, Ryo; Shoji, Kenji;

JNC TN8410 2001-012, 185 Pages, 2001/04

JNC-TN8410-2001-012.pdf:9.61MB

"The third technological meeting of Tokai Reprocessing plant (TRP)" was held in JNFL Rokkasyo site on March 14, 2001. The technical meetings have been held in the past two times. The first one was about the present status and future plan of the TRP and second one was about safety evaluation work on the TRP. At this time, the meeting focussed on the corrosion experrience, in-service inspection technology and future maintenance plan. The report contains the proceedings, transparancies and questionnaires of the meeting are contained.

Annual report on the environmental radiation monitoring around Tokai reprocessing plant FY 1999

; Shinohara, Kunihiko; ; ; ; Takeyasu, Masanori;

JNC TN8440 2000-007, 141 Pages, 2000/06

JNC-TN8440-2000-007.pdf:3.02MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed since 1975, based on "Safety Regulations for the Tokai Reprocessing Plant, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitants due to the radioactivity discharged from the plant during April 1999 to March 2000. Appendices present comprehensive information, such as monitoring program, monitoring results, meteorological data and annual discharges from the plant.

Evaluation of incident mitigation systems in Tokai reprocessing plant

Omori, Eiichi; Sudo, Toshiyuki; ; Kosaka, Ichiro; ; ;

JNC TN8410 99-005, 274 Pages, 1999/02

JNC-TN8410-99-005.pdf:19.02MB

Through the investigation of the cause of the fire and explosion incident at Bituminization Demonstration Facility of JNC Tokai Works, the lesson learned is that the safety assessment is necessary even for the licensed facilities by recent knowledge. The safety assessment has been conducted for the facilities in Tokai Reprocessing Plant by recent knowledge and operational experience. This report describes the evaluation results of the incident mitigation systems and the hypothetical accidents. In the evaluation of the incident mitigation system, supposed incidents were solvent fire, rapid reaction of hydrazine decomposition, leakage of radioactive material and loss of power supply. The evaluation was focused on the integrity of the filters in case of the fire and the rapid leaction, the availability of the recovery system in case of the radioactive leakage, and so on. As a result of evaluation, several improvements were pointed out to be necessary for the prevention of incident magnification. In the evaluation of the hypothetical accidents, criticality at a dissolver and fire at solvent extraction mixer-settlers were hypothesized. It was confirmed that the Tokai Reprocessing Plant is still distant enough from the population.

Annual report on the environmental radiation monitoring around Tokai Reprocessing Plant FY 1997

; ; Takeyasu, Masanori; ; ; ;

PNC TN8440 98-022, 140 Pages, 1998/06

PNC-TN8440-98-022.pdf:3.03MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed since 1975, based on "Safety Regulations for the Tokai Reprocessing Plant, Chapter VII - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitants due to the radioactivity discharged from the plant during April 1997 to March 1998. Appendices present comprehensive information, such as monitoring program, monitoring results, meteorological data and annual discharges from the plant.

Estimation of amount of released radioactivities and exposure dose equivalents of workers and the public due to the fire and explosion incident at the bituminization demonstration facility

; Noda, Kimio; *; *; ; ; *

PNC TN8410 98-048, 176 Pages, 1998/02

PNC-TN8410-98-048.pdf:12.9MB

On the fire and explosion incident at the bituminization demonstration facility on March 11, 1997, thirty-seven workers were internally exposed due to activity leakage from the filling room. Maximum committed effective dose equivalent from internal exposure was estimated and found to be approximately 0.4 to 1.6 mSv based on the results of whole body counting and nuclides analysis of nose-smear samples and air-sampler filters. Maximum effective dose equivalent from external exposure was estimated and found to be approximately 4SV. The explosion broke many windows and shutters of the facility and the radioactive material was released from the openings to outside. Radionuclides of Cs, Sr, Pu, and Am were detected by the environment monitoring within the site. In Oarai site (about 20 km away from the facility), a little amount of Cs radionuclides were detected from the air-dust sample. Some soot within the facility was sampled and radionuclides were analyzed. Based on the above information, the amount of released activities by the incident was evaluated and found to be approximately 1 to 4 GBq activity (principally Cs with 10% Cs excluding C) and 610910 GBq activity. Maximum committed effective dose equivalent to the public by the above amount of activity release was evaluated and found to be approximately 110 to 2 10 mSv.