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Journal Articles

Feasibility study of the one-dimensional radiation distribution sensing method using an optical fiber sensor based on wavelength spectrum unfolding

Terasaka, Yuta; Watanabe, Kenichi*; Uritani, Akira*; Yamazaki, Atsushi*; Sato, Yuki; Torii, Tatsuo; Wakaida, Ikuo

Journal of Nuclear Engineering and Radiation Science, 7(4), p.042002_1 - 042002_7, 2021/10

For the application in the measurement of the high dose rate hot spots inside the Fukushima Daiichi Nuclear Power Station (FDNPS) buildings, we propose a novel one-dimensional radiation distribution sensing method using an optical fiber sensor based on wavelength spectrum unfolding. The proposed method estimates the incident position of radiation to the fiber by the unfolding of the wavelength spectrum output from the fiber edge using the fact that the attenuation length of light along the fiber depends on the wavelength. Because this method measures the integrated light intensity, this method can avoid the problem of counting loss and signal pile-up, which occurs in the radiation detector with pulse counting mode under high dose rate field. Through basic experiments using the ultraviolet light source and $$^{90}$$Sr/$$^{90}$$Y radioactive point source, basic properties of source position detection were confirmed.

Journal Articles

Penetration factor and indoor deposition rate of elementary and particulate iodine in a Japanese house for assessing the effectiveness of sheltering for radiation exposures

Hirouchi, Jun; Takahara, Shogo; Komagamine, Hiroshi*; Kato, Nobuyuki*; Matsui, Yasuto*; Yoneda, Minoru*

Journal of Radiological Protection, 41(3), p.S139 - S149, 2021/09

 Times Cited Count:0 Percentile:0.02(Environmental Sciences)

Sheltering is one of the countermeasures for protection against radiation exposures in nuclear accidents. The effectiveness of sheltering is often expressed by the reduction factor, that is the ratio of the indoor to the outdoor cumulative radioactivity concentrations or doses. The indoor concentration is mainly controlled by the air exchange rate, penetration factor, and indoor deposition rate. The penetration factor and indoor deposition rate depend on the surface and opening materials. We investigated experimentally these parameters of I$$_{2}$$ and particles. The experiment was performed in two apartment houses, three single-family houses, and chambers. The obtained penetration factor ranged 0.3 $$sim$$ 1 for particles of 0.3 $$sim$$ 1 $$mu$$m and 0.15 $$sim$$ 0.7 for I$$_{2}$$ depending on the air exchange rate. The indoor deposition rate for a house room ranged 0.007 $$sim$$ 0.2 h$$^{-1}$$ for particles of 0.3$$sim$$1 $$mu$$m and 0.2$$sim$$1.5 h$$^{-1}$$ for I$$_{2}$$ depending on floor materials.

JAEA Reports

Database for corrosion under irradiation conditions (Contract research)

Sato, Tomonori; Hata, Kuniki; Kaji, Yoshiyuki; Ueno, Fumiyoshi; Inoue, Hiroyuki*; Taguchi, Mitsumasa*; Seito, Hajime*; Tada, Eiji*; Abe, Hiroshi*; Akiyama, Eiji*; et al.

JAEA-Review 2021-001, 123 Pages, 2021/06


In the implement of the decommissioning of Fukushima Daiichi Nuclear Power Station (1F), there are many problems to be solved. Specially, the mitigation of the aging degradation by the corrosion of the structural materials is important to implement the decommissioning safely and continuously. However, there are limited data for the environmental factors of corrosion in 1F, and the condition of 1F is continuously changing. So, the literature data for the water radiolysis and the corrosion under irradiation are listed as the database of corrosion under irradiation in this report. And the new obtained radiolysis and corrosion data, which have not been reported in the literature and will be required in the decommissioning of 1F, are reported.

JAEA Reports

Planning and implementation of environmental radiation monitoring

Takeishi, Minoru

JAEA-Review 2020-077, 388 Pages, 2021/05


Japan Atomic Energy Agency (JAEA) have implemented environmental radiation monitoring since 1960s around different kinds of nuclear facilities such as research reactors, MOX fuel fabrication development facilities and the first spent fuel reprocessing facility for commercial NPPs and so on. I summarize the environmental monitoring methodology from planning to evaluation comprehensively as a guide book based on our experience and referring to the latest information. This guide book contained various basic knowledge about history of environmental radiation surveillances, techniques of radiation measurement and analysis of environmental samples such as airborne materials, precipitation, fallout, soil, sediment in river and lake, drinking water, terrestrial water, vegetables, milk, pasture, sea water, seabed sediment, marine product, index samples, and including with related to fundamental knowledges like an exposure evaluation for the public and quality assurance(QA), and some regulations. In particular, I include the emergency environmental radiation monitoring with response to the accident of Chernobyl Nuclear Power Plant and Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Station. Finally, I note some topics on the environmental impact study that I have experienced.

Journal Articles

Meteorological aspects of gamma-ray glows in winter thunderstorms

Wada, Yuki*; Enoto, Teruaki*; Kubo, Mamoru*; Nakazawa, Kazuhiro*; Shinoda, Taro*; Yonetoku, Daisuke*; Sawano, Tatsuya*; Yuasa, Takayuki*; Ushio, Tomoo*; Sato, Yosuke*; et al.

Geophysical Research Letters, 48(7), 11 Pages, 2021/04

 Times Cited Count:0 Percentile:0(Geosciences, Multidisciplinary)

During three winter seasons from November 2016 to March 2019, 11 gamma-ray glows were detected at a single observation site of our ground-based gamma-ray monitoring network in Kanazawa, Japan. These events are analyzed with observations of an X-band radar network, a ceilometer, a disdrometer, and a weather monitor. All the detected glows were connected to convective high-reflectivity regions of more than 35 dBZ, developed up to an altitude of $$>$$2 km. They were also accompanied by heavy precipitation of graupels. Therefore, graupels in the lower layer of thunderclouds that correspond to high-reflectivity regions can form strong electric fields producing gamma-ray glows. Also, these events are compared with a limited sample of nondetection cases, but no significant differences in meteorological conditions were found between detection and nondetection cases in the present study.

Journal Articles

Evaluation of a one-dimensional position-sensitive quartz optical fiber sensor based on the time-of-flight method for high radiation dose rate applications

Terasaka, Yuta; Watanabe, Kenichi*; Uritani, Akira*

Nuclear Instruments and Methods in Physics Research A, 996, p.165151_1 - 165151_8, 2021/04

 Times Cited Count:0 Percentile:0.03(Instruments & Instrumentation)

For the measurement of radiation distribution inside the Fukushima Daiichi Nuclear Power Station (FDNPS) buildings, the evaluation of a small-diameter quartz optical fiber as a one-dimensional position-sensitive sensor was conducted. The sensor determines the incident position of radiation into the fiber using the time-of-flight information of emitted Cerenkov photons in the optical fiber. Compared with the conventional sensor using the plastic scintillating fiber, the quartz optical fiber has much higher position resolution, which may be the result of the improvement of timing characteristics caused by the prompt emission mechanism of the Cerenkov radiation. Additionally, the response of position-sensitive quartz optical fiber sensor under high radiation field was evaluated, and good count rate linearity was confirmed using the 10 m long quartz optical fiber with a diameter of 0.4 mm up to the dose rate at least 20 mSv/h, and the radiation tolerance property up to the accumulated dose of 1 kGy was evaluated.

Journal Articles

Study on gamma-ray-degradation of adsorbent for low pressure-loss extraction chromatography

Miyazaki, Yasunori; Sano, Yuichi; Okamura, Nobuo; Watanabe, Masayuki; Koka, Masashi*

QST-M-29; QST Takasaki Annual Report 2019, P. 72, 2021/03

no abstracts in English

Journal Articles

New method for visualizing the dose rate distribution around the Fukushima Daiichi Nuclear Power Plant using artificial neural networks

Sasaki, Miyuki; Sanada, Yukihisa; Katengeza, E. W.*; Yamamoto, Akio*

Scientific Reports (Internet), 11, p.1857_1 - 1857_11, 2021/01

 Times Cited Count:0 Percentile:0(Multidisciplinary Sciences)

This study proposed a new method to visualize the ambient dose rate distribution using artificial neural networks from the results of airborne radiation monitoring. The method used airborne radiation monitoring conducted around Fukushima Daiichi Nuclear Power Plant by an unmanned aerial vehicle. A lot of survey data which had obtained in the past was used as training data for building a network. The reliability of the artificial neural network method was evaluated by comparison with the ground-based survey data. The dose rate map that was created by the artificial neural networks method reproduced the ground-based survey results better than traditional methods.

Journal Articles

Distribution map of natural gamma-ray dose rates for studies of the additional exposure dose after the Fukushima Dai-ichi Nuclear Power Station accident

Sanada, Yukihisa; Yoshimura, Kazuya; Urabe, Yoshimi*; Iwai, Takeyuki*; Katengeza, E. W.*

Journal of Environmental Radioactivity, 223-224, p.106397_1 - 106397_9, 2020/11

 Times Cited Count:2 Percentile:42.4(Environmental Sciences)

Journal Articles

Construction of virtual reality system for radiation working environment reproduced by gamma-ray imagers combined with SLAM technologies

Sato, Yuki; Minemoto, Kojiro*; Nemoto, Makoto*; Torii, Tatsuo

Nuclear Instruments and Methods in Physics Research A, 976, p.164286_1 - 164286_6, 2020/10

 Times Cited Count:6 Percentile:91.19(Instruments & Instrumentation)

Journal Articles

Thundercloud project; Exploring high-energy phenomena in thundercloud and lightning

Yuasa, Takayuki*; Wada, Yuki*; Enoto, Teruaki*; Furuta, Yoshihiro; Tsuchiya, Harufumi; Hisadomi, Shohei*; Tsuji, Yuna*; Okuda, Kazufumi*; Matsumoto, Takahiro*; Nakazawa, Kazuhiro*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2020(10), p.103H01_1 - 103H01_27, 2020/10

 Times Cited Count:1 Percentile:34.55(Physics, Multidisciplinary)

JAEA Reports

Annual report of Nuclear Emergency Assistance and Training Center (April 1, 2019 - March 31, 2020)

Nuclear Emergency Assistance and Training Center

JAEA-Review 2020-016, 67 Pages, 2020/09


The Japan Atomic Energy Agency (JAEA) is one of the designated public institutions, which is an agency dealing with an emergency situation in cooperation with the Japanese and local governments under the Disaster Countermeasures Basic Act and under the Armed Attack Situation Response Law. JAEA has, therefore, responsibilities of providing technical assistances to the Japanese and local governments in case of nuclear or radiological emergencies based on these Acts. To fulfill the assistances, the JAEA has prepared the Nuclear Emergency Support Measures Regulation, Disaster Prevention Work Plan and Civil Protection Work Plan. The Nuclear Emergency Assistance and Training Center (NEAT) is the main center of the technical assistance in case of emergency, and dispatches experts of JAEA, supplies equipment and materials and gives technical advice and information, to the Japanese and local governments for emergency based on the regulation and plans. In normal time, the NEAT provides the technical assistances such as the exercises and training courses concerning the nuclear preparedness and response to the JAEA experts and also to emergency responders including the Japanese and local government officers. This report introduces the results of activities in Japanese Fiscal Year 2019, conducted by NEAT in accordance with the third medium and long-term plan for the period from Japanese Fiscal Year 2015 to 2021.

Journal Articles

Japanese population dose from natural radiation

Omori, Yasutaka*; Hosoda, Masahiro*; Takahashi, Fumiaki; Sanada, Tetsuya*; Hirao, Shigekazu*; Ono, Koji*; Furukawa, Masahide*

Journal of Radiological Protection, 40(3), p.R99 - R140, 2020/09

 Times Cited Count:6 Percentile:75.13(Environmental Sciences)

UNSCEAR and the Nuclear Safety Research Association report the annual effective doses from cosmic rays, terrestrial radiation, inhalation and ingestion from natural sources. In this study, radiation doses from natural radiation sources in Japan were reviewed with the latest knowledge and data. Total annual effective dose from cosmic-ray exposure can be evaluated as 0.29 mSv. The annual effective dose from external exposure to terrestrial radiation for Japanese population can be evaluated as 0.33 mSv using the data of nationwide survey by the National Institute of Radiological Sciences. The Japan Chemical Analysis Center (JCAC) performed the nationwide radon survey using a unified method for radon measurements in indoor, outdoor and workplace. The annual effective dose for radon inhalation was estimated using a current dose conversion factor, and the values were estimated to be 0.50 mSv. The annual effective dose from thoron was reported as 0.09 mSv by UNSCEAR and then the annual effective dose from inhalation can be described as 0.59 mSv. According to the report of large scale survey of foodstuff by JCAC, the effective dose from main radionuclides due to dietary intake can be evaluated to be 0.99 mSv. Finally, Japanese population dose from natural radiation can be assessed as 2.2 mSv which is near to the world average value of 2.4 mSv.

Journal Articles

Observation of morphological abnormalities in silkworm pupae after feeding $$^{137}$$CsCl-supplemented diet to evaluate the effects of low dose-rate exposure

Tanaka, Sota; Kinouchi, Tadatoshi*; Fujii, Tsuguru*; Imanaka, Tetsuji*; Takahashi, Tomoyuki*; Fukutani, Satoshi*; Maki, Daisuke*; Notomi, Akihiro*; Takahashi, Sentaro*

Scientific Reports (Internet), 10, p.16055_1 - 16055_7, 2020/09

 Times Cited Count:1 Percentile:42.76(Multidisciplinary Sciences)

Since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, morphological abnormalities of the lepidopteran insects have been reported. However, it is unclear whether the abnormalities were caused directly by radiation because they did not study on absorbed dose and dose-effect relationship. In this study, we conducted an internal exposure experiment on silkworm using $$^{137}$$CsCl-supplemented artificial diet and estimated the absorbed dose to evaluate the morphological abnormalities in silkworm. The ratio of wing to whole body of pupae was compared between the $$^{137}$$CsCl-exposured and control groups and no significant differences were observed between the groups. This result suggest that morphological abnormalities in lepidopterans are unlikely due to direct radiation effects from $$^{137}$$Cs contamination after the FDNPP accident.

Journal Articles

Tolerance of spin-Seebeck thermoelectricity against irradiation by swift heavy ions

Okayasu, Satoru; Harii, Kazuya*; Kobata, Masaaki; Yoshii, Kenji; Fukuda, Tatsuo; Ishida, Masahiko*; Ieda, Junichi; Saito, Eiji

Journal of Applied Physics, 128(8), p.083902_1 - 083902_7, 2020/08

 Times Cited Count:0 Percentile:0(Physics, Applied)

Journal Articles

Retracted article; Visualization and integration of images of radioactive substances as point cloud data in 3-D environment models

Sato, Yuki; Torii, Tatsuo

Nuclear Technology, 206(7), p.v - xvi, 2020/07

 Times Cited Count:2 Percentile:66.08(Nuclear Science & Technology)

Journal Articles

Concept of radiation protection for low-dose risks

Takahara, Shogo

Hoshasen Seibutsu Kenkyu, 55(2), p.162 - 172, 2020/06

no abstracts in English

Journal Articles

$$gamma$$-radiation and H$$_{2}$$O$$_{2}$$ induced oxidative dissolution of uranium(IV) oxide in aqueous solution containing phthalic acid

Kumagai, Yuta; Jonsson, M.*

Dalton Transactions (Internet), 49(6), p.1907 - 1914, 2020/02

 Times Cited Count:0 Percentile:0.01(Chemistry, Inorganic & Nuclear)

This study aims to reveal possible involvements of organic acids in the oxidative dissolution of UO$$_{2}$$. Using phthalic acid as a model compound, we have measured adsorption on UO$$_{2}$$ and investigated effects on the reaction between H$$_{2}$$O$$_{2}$$ and UO$$_{2}$$ and on oxidative dissolution induced by $$gamma$$-irradiation. Significant adsorption of phthalic acid was observed even at neutral pH. However, the reaction between H$$_{2}$$O$$_{2}$$ and UO$$_{2}$$ in phthalic acid solution induced oxidative dissolution of U(VI) similarly to aqueous bicarbonate solution. These results indicate that even though phthalic acid adsorbs on the UO$$_{2}$$ surface, it is not involved in the interfacial reaction by H$$_{2}$$O$$_{2}$$. In contrast, the dissolution of U by irradiation was inhibited in aqueous phthalic acid solution, whereas H$$_{2}$$O$$_{2}$$ generated by radiolysis was consumed by UO$$_{2}$$. The inhibition suggests that radical species derived from phthalic acid was involved in the redox reaction process of UO$$_{2}$$.

JAEA Reports

RADREMOTE 2018; Proceedings of The 5th Fukushima Research Conference (FRC) 2018; Radiation hardness, smartness and measurement in remote technology for the decommissioning of the Fukushima Daiichi Nuclear Power Station

Kaburagi, Masaaki; Torii, Tatsuo; Ogawa, Toru

JAEA-Review 2019-031, 251 Pages, 2020/01


There is high expectation for advanced remote technology and robotics to reduce the radiation exposure for workers in harsh nuclear environments such as the decommissioning of the Fukushima Daiichi Nuclear Power Station (FDNPS). However, the radiation tolerance of state-of-the-art key components, sensors and electronic devices, for remote operation is still limited. In order to extend the application of robotics in nuclear energy, it is pertinent to develop "Radiation hardness" of components and "Radiation smartness" in operation procedures. Furthermore, developments of "Radiation measurement" and "Technology to recognize the location and to grasp the surrounding environment", including the radiation imaging of the high dose-rate fields inside the FDNPS and the detection of nuclear fuel debris, are necessary for the future nuclear fuel debris retrieval. This Fukushima Research Conference aims to share the future vision for advancing the remote technology among experts from diverse fields.

2353 (Records 1-20 displayed on this page)