Aerial monitoring around TEPCO's Fukushima Daiichi Nuclear Power Station and development of radiation monitoring technology for unmanned airplanes in fiscal year 2023 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Nakama, Shigeo; Sasaki, Miyuki; Ochi, Kotaro; Nagakubo, Azusa; Sawahata, Yoshiro*; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; et al.

JAEA-Technology 2024-021, 232 Pages, 2025/03

JAEA-Technology-2024-021.pdf:25.79MB

The 2011 off the Pacific coast of Tohoku Earthquake on March 11, 2011, caused a tsunami that led to the TEPCO's Fukushima Daiichi Nuclear Power Station (FDNPS) accident, releasing a large amount of radioactive material into the surrounding environment. Since the accident, Aerial Radiation Monitoring (ARM) has been used to quickly and widely measure radiation distribution. As a commissioned project from the Nuclear Regulation Authority, the Japan Atomic Energy Agency (JAEA) has continuously conducted ARM around FDNPS using manned and unmanned helicopters. This report summarizes the monitoring results for fiscal year 2023, evaluates changes in dose rate from past results, and discusses the factors contributing to these changes. Additionally, an analysis considering terrain undulation was conducted to improve accuracy for converting ARM data into dose rate. Furthermore, a method to discriminate airborne radon progeny was applied for ARM results to evaluate its impact. Moreover, to perform wide-area monitoring more efficiently, we advanced the development of unmanned airplane monitoring technology.

Background radiation monitoring via manned helicopter and development of technology for radiation monitoring via unmanned airplane for application of nuclear emergency response technique in the fiscal year 2022 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Sasaki, Miyuki; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Haginoya, Masashi*; Matsunaga, Yuki*; Akutsu, Yuichiro*; Arai, Yoshinori*; et al.

JAEA-Technology 2023-026, 161 Pages, 2024/03

JAEA-Technology-2023-026.pdf:14.66MB

By the accident at Tokyo Electric Power Company's (TEPCO's) Fukushima Daiichi Nuclear Power Station (FDNPS), caused by tsunami triggered by the 2011 off the Pacific coast of Tohoku Earthquake, a large amount of radioactive material was released into the surrounding environment. After the accident, Airborne Radiation Monitoring (ARM) via manned helicopter has been utilized as a method to quickly and extensively measure radiation distribution surrounding FDNPS. In order to utilize ARM and to promptly provide the results during a nuclear emergency, information on background radiation levels, topographical features, and controlled airspace surrounding nationwide nuclear facilities have been prepared in advance. In the fiscal year 2022, we conducted ARM around the Mihama Nuclear Power Station of Kansai Electric Power Company (KEPCO), the Tsuruga Power Station of Japan Atomic Power Company (JAPC), and the Ikata Power Station of Shikoku Electric Power Company (YONDEN), and prepared information on background radiation doses and controlled airspace. In addition, we have developed an aerial radiation detection system via unmanned airplane, which is expected to be an alternative to ARM, during a nuclear emergency. This report summarizes the results and technical issues identified.

Radiation monitoring via manned helicopter around the Nuclear Power Station in the fiscal year 2021 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Nagakubo, Azusa; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Haginoya, Masashi*; Matsunaga, Yuki*; Akutsu, Yuichiro*; Urabe, Yoshimi*; et al.

JAEA-Technology 2022-027, 148 Pages, 2023/02

JAEA-Technology-2022-027.pdf:19.64MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the FDNPS. After the nuclear disaster, airborne radiation monitoring via manned helicopter has been conducted around FDNPS. The results of the airborne radiation monitoring and the evaluation for temporal change of dose rate in the fiscal 2021 were summarized in this report. Analysis considering topographical effects was applied to the result of the airborne monitoring to improve the accuracy of the conventional method. In addition, technique for discriminating gamma rays from the ground and those from the airborne Rn-progenies was also utilized to evaluate their effect on airborne radiation monitoring.

Background radiation monitoring using manned helicopter for application of technique of nuclear emergency response in the fiscal year 2020 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Sasaki, Miyuki; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Sato, Kazuhiko*; Haginoya, Masashi*; Matsunaga, Yuki*; Kikuchi, Hikaru*; et al.

JAEA-Technology 2021-020, 138 Pages, 2021/11

JAEA-Technology-2021-020.pdf:17.11MB

A large amount of radioactive material was released by the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company, caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011. After the nuclear disaster, airborne radiation monitoring via manned helicopter has been utilized to grasp rapidly and widely the distribution of the radioactive materials surrounding FDNPS. We prepare the data of background radiation dose, geomorphic characteristics and the controlled airspace surrounding nuclear facilities of the whole country in order to make effective use of the monitoring technique as a way of emergency radiation monitoring and supply the results during an accident of a facility. This report is summarized that the knowledge as noted above achieved by the aerial radiation monitoring around Tsuruga and Mihama nuclear power station, research reactors in Kindai University Atomic Energy Research Institute and Institute for Integrated Radiation and Nuclear Science, Kyoto University. In addition, examination's progress aimed at introduction of airborne radiation monitoring via unmanned plane during nuclear disaster and the technical issues are summarized in this report.

Background radiation monitoring using manned helicopter for application of technique of nuclear emergency response in the fiscal year 2019 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Sato, Kazuhiko*; Haginoya, Masashi*; Matsunaga, Yuki*; Kikuchi, Hikaru*; Ishizaki, Azusa; et al.

JAEA-Technology 2020-019, 128 Pages, 2021/02

JAEA-Technology-2020-019.pdf:15.75MB

A large amount of radioactive material was released by the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company, caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011. After the nuclear disaster, airborne radiation monitoring using manned helicopter has been utilized to grasp rapidly and widely the distribution of the radioactive materials around FDNPS. We prepare the data of background radiation dose, geomorphic characteristics and the controlled airspace around nuclear facilities of the whole country in order to make effective use of the monitoring technique as a way of emergency radiation monitoring and supply the results during accidents of the facilities. Furthermore, the airborne radiation monitoring has been conducted in Integrated Nuclear Emergency Response Drill to increase effectiveness of the monitoring. This report is summarized that the knowledge as noted above achieved by the aerial radiation monitoring around Higashidori nuclear power station, the nuclear fuel reprocessing plant in Rokkasho village and Shika nuclear power station, the full details of the aerial radiation monitoring in Integrated Nuclear Emergency Response Drill in the fiscal 2019. In addition, examination's progress aimed at introduction of airborne radiation monitoring using unmanned helicopter during nuclear disaster and the technical issues are summarized in this report.

Spontaneous formation of suboxidic coordination around Co in ferromagnetic rutile TiCoO film

Hu, W.*; Hayashi, Koichi*; Fukumura, Tomoteru*; Akagi, Kazuto*; Tsukada, Masaru*; Happo, Naohisa*; Hosokawa, Shinya*; Owada, Kenji; Takahashi, Masamitsu; Suzuki, Motohiro*; et al.

Applied Physics Letters, 106(22), p.222403_1 - 222403_5, 2015/06

https://doi.org/10.1063/1.4921847

In-situ corrosion test of carbon steel overpacks at Horonobe Underground Research Facility

Taniguchi, Naoki; Kitayama, Ayami; Kawasaki, Manabu*; Nakayama, Masashi; Ono, Hirokazu; Mitsui, Seiichiro; Suzuki, Hiroyuki*

no journal, , 

no abstracts in English

Corrosion monitoring of carbon steel in bentonite at deep underground

Taniguchi, Naoki; Kawasaki, Manabu; Nakayama, Masashi; Sugita, Yutaka; Tachi, Yukio; Honda, Akira

no journal, , 

In previous study, a corrosion sensor has been developed and its appicability to monitoring of the corrosion behavior of carbon steel overpack has been confirmed. In this study, a simulated overpack was placed with buffer material composed mainly of bentonite in test tunnel of 350m deep underground constructed at Horonobe underground research laboratory. The corrosion monitoring was performed by AC impedance method using the corrosion sensors embeded in the buffer material.