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JAEA Reports

Development of measurement system of radioactive plume using unmanned airplane in the fiscal year 2018 (Contract research)

Sanada, Yukihisa; Ochi, Kotaro; Ishizaki, Azusa

JAEA-Research 2020-006, 60 Pages, 2020/07

JAEA-Research-2020-006.pdf:4.84MB

At the accident of nuclear facilities, a prediction of the behavior of released radioactive plume is indispensable to make a decision on a refuge plan of inhabitants. Currently, prediction system which is based on atmospheric dispersion simulation has been implemented as a tool of the atomic energy disaster prevention. However, the direct measurement method of the radioactive plume has not existed. In this study, some component technologies were developed for the establishment of direct measurement methods of radioactive plume using unmanned aerial vehicle whose technological innovation is remarkable. In addition, the spray test using mock aerosol was conducted to obtaining the deposition rate to the airplane body. The algorism of making a flight plan was developed based on a prediction model of the radioactive plume. This report summarized the outcome of the last year of the three-year plan.

JAEA Reports

Background radiation monitoring using manned helicopter for application of technique of nuclear emergency response in the fiscal year 2018 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Komiya, Tomokazu; Iwai, Takeyuki*; Seguchi, Eisaku*; Matsunaga, Yuki*; Kawabata, Tomoki*; Haginoya, Masashi*; Hiraga, Shogo*; Sato, Kazuhiko*; et al.

JAEA-Technology 2019-017, 95 Pages, 2019/11

JAEA-Technology-2019-017.pdf:12.09MB

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 using manned helicopter was conducted around FDNPS. We have carried out the background radiation monitoring around the nuclear power stations of the whole country to apply the airborne radiation monitoring technique that has been cultivated in the aerial monitoring around FDNPS against nuclear emergency response. The results of monitoring around Shimane and Hamaoka Nuclear Power Stations in the fiscal 2018 were summarized in this report. In addition, technical issues were described.

JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2018 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Ishizaki, Azusa; Komiya, Tomokazu; Iwai, Takeyuki*; Seguchi, Eisaku*; Matsunaga, Yuki*; Kawabata, Tomoki*; Haginoya, Masashi*; Hiraga, Shogo*; et al.

JAEA-Technology 2019-016, 116 Pages, 2019/11

JAEA-Technology-2019-016.pdf:14.09MB

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 using manned helicopter has been conducted around FDNPS. The results in the fiscal 2018 were summarized in this report. Discrimination method of gamma rays from Rn-progenies was also utilized to evaluate their effect on aerial radiation monitoring. In addition, analysis taken topographical effects into consideration was applied to previous results of airborne monitoring to improve the precision of conventional method.

Journal Articles

Evaluation of the radiation protection capability in shelter facilities with positive pressure ventilation

Ishizaki, Azusa; Nakanishi, Chika*; Takubo, Kazuya*; Munakata, Masahiro

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 9 Pages, 2019/05

Journal Articles

Investigation of removal factors of various materials inside houses after Nuclear Power Station Accident

Mori, Airi; Ishizaki, Azusa; Futemma, Akira; Tanabe, Tsutomu; Wada, Takao; Kato, Mitsugu; Munakata, Masahiro

Hoken Butsuri (Internet), 54(1), p.45 - 54, 2019/04

JAEA Reports

Photon transmittance data collection of building materials for evaluating radiation protection capability of buildings (Contract research)

Ishizaki, Azusa; Futemma, Akira; Takubo, Kazuya*; Nakanishi, Chika*; Munakata, Masahiro

JAEA-Data/Code 2018-022, 20 Pages, 2019/03

JAEA-Data-Code-2018-022.pdf:2.05MB

If a nuclear disaster occurs, we may evacuate indoor escape facilities and buildings such as houses as avoid extra exposure doses. In order to evaluate exposure doses, it is necessary to estimate shielding capabilities of the building materials constituting the sheltering facility. Therefore, photon irradiation tests with three kinds of photon energy were carried out for Japanese familiar building materials in Japan, and photon transmittance of each building material is acquired and summarized. As a result, it was found that the shielding capabilities of composite walls and roofs which are widely used in a tree structure and a steel structure were relatively low. And, difference of materials used for composite walls and roofs resulted in a difference in shielding capabilities. For example, in the case of composite walls, compared with the photon transmittance of wall with ceramic-based siding materials, those of wall with lightweight concrete were lower. Furthermore, photon transmittance was also measured for building materials with relatively low shielding performance added shielding materials as additional measures to enhance shielding capabilities.

JAEA Reports

Background radiation monitoring using manned helicopter for establishment of technique of nuclear emergency response in the fiscal year 2017 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Iwai, Takeyuki*; Seguchi, Eisaku; Matsunaga, Yuki*; Kawabata, Tomoki; Toyoda, Masayuki*; Tobita, Shinichiro*; Hiraga, Shogo*; Sato, Kazuhiko*; et al.

JAEA-Technology 2018-016, 98 Pages, 2019/02

JAEA-Technology-2018-016.pdf:18.64MB

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 NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. We have carried out the background monitoring around the nuclear power stations of the whole country to apply the airborne radiation monitoring technique that has been cultivated in Fukushima against nuclear emergency response. The results of monitoring around Tomari, Kashiwazaki-Kariwa and Genkai Nuclear Power Station in the fiscal 2017 were summarized in this report. In addition, technical issues were described.

JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2017 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Ishizaki, Azusa; Iwai, Takeyuki*; Seguchi, Eisaku; Matsunaga, Yuki*; Kawabata, Tomoki; Toyoda, Masayuki*; Tobita, Shinichiro*; Hiraga, Shogo*; et al.

JAEA-Technology 2018-015, 120 Pages, 2019/02

JAEA-Technology-2018-015.pdf:15.01MB

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 NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. The results in the fiscal 2017 were summarized in this report. In addition, we developed and systemized the discrimination technique of the Rn-progenies. The accuracy of aerial radiation monitoring was evaluated by taking into consideration GPS data error.

JAEA Reports

Development of measurement system of radioactive plume using unmanned airplane in the fiscal year 2017 (Contract research)

Sanada, Yukihisa; Nishizawa, Yukiyasu*; Ochi, Kotaro; Yuki, Yoichi*; Ishizaki, Azusa; Osada, Naoyuki*

JAEA-Research 2018-009, 48 Pages, 2019/01

JAEA-Research-2018-009.pdf:14.77MB

At the accident of nuclear facilities, a prediction of the behavior of released radioactive plume is indispensable to make a decision on a refuge plan of inhabitants. Currently, prediction system which is based on atmospheric dispersion simulation has been implemented as a tool of the atomic energy disaster prevention. However, the direct measurement method of the radioactive plume has not existed. In this study, some component technologies were developed for the establishment of direct measurement methods of radioactive plume using unmanned aerial vehicle whose technological innovation is remarkable. In addition, the spray test using mock aerosol was conducted to obtaining the deposition rate to the airplane body. The algorism of making a flight plan was developed based on a prediction model of the radioactive plume. This report summarized the outcome of the second year of the three-year plan.

Journal Articles

Development of analysis method for airborne radiation monitoring using the inverse problem solutions

Sasaki, Miyuki; Ishizaki, Azusa; Sanada, Yukihisa

Progress in Nuclear Science and Technology (Internet), 6, p.63 - 67, 2019/01

Since the accident at Fukushima Daiichi Nuclear Power Station (FDNPS), some unmanned vehicles (UAVs) are applied to airborne radiation measurement in around FDNPS. In conventional analysis methods, count rate that is obtained in the sky is converted to air dose rate at 1 m above the ground (agl.) under following premises. (1) Topography under the UAV is a plane (plane source model). (2) The air dose rate at 1 m agl. under the UAV is constant inside approximately 10 m radius. (3) Relationship of altitude and count rate is exponential correlation. Therefore, it is difficult that dose rate by airborne radiation measurement is precisely measured at the mountains and uneven place of dose rate by the conventional method. In this study, Maximum Likelihood-Expectation Maximization (ML-EM) method which is used in the medical radiation such as Positron Emission Tomography (PET) is attempted to apply to environmental radiation measurement using UAV.

JAEA Reports

Development of measurement system of radioactive plume using unmanned airplane in the fiscal year 2016 (Contract research)

Ishizaki, Azusa; Sanada, Yukihisa; Nishizawa, Yukiyasu*; Futemma, Akira; Munakata, Masahiro

JAEA-Research 2017-012, 58 Pages, 2018/03

JAEA-Research-2017-012.pdf:9.36MB

At the accident of nuclear facilities, a prediction of behavior of released radioactive plume is indispensable for the decision of the refuge plan of inhabitants. Currently, prediction system which is based on atmospheric dispersion simulation has been implemented for as a tool of the atomic energy disaster prevention. However, direct measurement method of radioactive plume has not existed. In this study, some component technologies were developed for establishment of direct measurement methods of radioactive plume using unmanned aerial vehicle whose technological innovation is remarkable. In addition, algorism of making flight plan was developed based on prediction model of radioactive plume. This report summarized the outcome of the first year with plan of three years.

JAEA Reports

Background radiation monitoring using manned helicopter for establishment of technique of nuclear emergency response in the fiscal year 2016 (Contract research)

Sanada, Yukihisa; Mori, Airi; Iwai, Takeyuki; Seguchi, Eisaku; Matsunaga, Yuki*; Kawabata, Tomoki; Toyoda, Masayuki*; Tobita, Shinichiro*; Hiraga, Shogo; Sato, Yoshiharu; et al.

JAEA-Technology 2017-035, 69 Pages, 2018/02

JAEA-Technology-2017-035.pdf:32.92MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. We carried out the background monitoring around the nuclear power stations of the whole country to apply a technique of the airborne radiation monitoring that is cultivated in Fukushima as a technology of nuclear emergency response. This result of the aerial radiation monitoring using the manned helicopter around Ooi, Takahama and Ikata Nuclear Power Station and in the fiscal 2016 were summarized in the report. In addition, technical issues were described.

JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2016 (Contract research)

Sanada, Yukihisa; Mori, Airi; Iwai, Takeyuki; Seguchi, Eisaku; Matsunaga, Yuki*; Kawabata, Tomoki; Toyoda, Masayuki*; Tobita, Shinichiro*; Hiraga, Shogo; Sato, Yoshiharu; et al.

JAEA-Technology 2017-034, 117 Pages, 2018/02

JAEA-Technology-2017-034.pdf:25.18MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. This result of the aerial radiation monitoring using the manned helicopter in the fiscal 2016 were summarized in the report. In addition, we developed the discrimination technique of the Rn-progenies. The accuracy of aerial radiation monitoring was evaluated by taking into consideration GPS position error.

Journal Articles

Application of topographical source model for air dose rates conversions in aerial radiation monitoring

Ishizaki, Azusa; Sanada, Yukihisa; Ishida, Mutsushi; Munakata, Masahiro

Journal of Environmental Radioactivity, 180, p.82 - 89, 2017/12

 Times Cited Count:5 Percentile:64.11(Environmental Sciences)

After the Fukushima Daiichi Nuclear Power Station (FDNPS) accident in 2011, aerial radiation monitoring (ARM) using a manned helicopter was conducted to rapidly measure air dose rates and the deposition of radioactive nuclides over a large area. Typically, the air dose rate is obtained by conversion from the count rate using the conventional flat source model (FSM). The converted dose rate via aerial monitoring poorly matches the results of ground measurement in the mountain and forest areas because the FSM does not consider topographical effects. To improve the conversion accuracy, we developed new methods to analyze aerial monitoring data using the topographical source model (TSM) based on the analytical calculation of the $$gamma$$-ray flux. The ARM results converted using both the FSM as well as TSM were compared with ground measurement data obtained after the FDNPS accident. By using TSM, the conversion accuracy was improved.

Journal Articles

Study for estimation of snow depth by using DSM made by SfM method

Miyasaka, Satoshi*; Unome, Sota*; Tamura, Ayako*; Ito, Yoshiaki*; Ishizaki, Azusa; Sanada, Yukihisa

Nippon Rimoto Senshingu Gakkai Dai-63-Kai (Heisei-29-Nendo Shuki) Gakujutsu Koenkai Rombunshu (CD-ROM), p.81 - 84, 2017/11

Information of snow depth is important to improve the airborne radiation measurement in the winter. The snow depth is enable to estimate by the aerial photograph which is obtained at the same time with the radiation measurement before and after the snowfall. We attempted optimization parameters which used to make a Digital Surface Model (DSM) using Structure from Motion (SfM) method for estimation of the snow depth. As a result, to enable to measure precisely the snow depth was indicated. However, the estimated snow depth in the forest area was relatively not so accurate because fallen leaves and a tree move were prevented to measure DSM precisely.

Journal Articles

Bioaccessibility of Fukushima-accident-derived Cs in soils and the contribution of soil ingestion to radiation doses in children

Takahara, Shogo; Ikegami, Maiko*; Yoneda, Minoru*; Kondo, Hitoshi*; Ishizaki, Azusa; Iijima, Masashi; Shimada, Yoko*; Matsui, Yasuto*

Risk Analysis, 37(7), p.1256 - 1267, 2017/07

AA2015-0445.pdf:0.53MB

 Times Cited Count:4 Percentile:36.59(Public, Environmental & Occupational Health)

Journal Articles

Airborne radiation monitoring using a manned helicopter

Sanada, Yukihisa; Ishizaki, Azusa; Nishizawa, Yukiyasu; Urabe, Yoshimi*

Bunseki Kagaku, 66(3), p.149 - 162, 2017/03

 Times Cited Count:7 Percentile:51.56(Chemistry, Analytical)

The Great East Japan Earthquake that occurred on 11 March 2011 generated a series of large tsunami waves that caused serious damage to the Fukushima Dai-ichi Nuclear Power Station, following which a large amount of radioactive material was discharged from the nuclear power plant into the environment. The airborne radiation measurement using a manned helicopter was applied to measure the radiation distribution immediately after accident of the Fukushima Dai-ichi Nuclear Power Station as technique to quickly measure the radiation distribution in the wide area. In Japan, this technique was researched and developed in the 1980s. However, this technique and system were not applied immediately after the accident because standardization of analysis was not established and the Japanese system became deteriorated. This technique is important for post-accident of nuclear facility. We summarized the methods of the airborne radiation measurement using a manned helicopter. In addition, measurement results of dose rate distribution at the Fukushima Dai-ichi Nuclear Power Station was shown in this paper.

Journal Articles

Assessment of residual doses to population after decontamination in Fukushima Prefecture

Mori, Airi; Takahara, Shogo; Ishizaki, Azusa; Iijima, Masashi; Sanada, Yukihisa; Munakata, Masahiro

Journal of Environmental Radioactivity, 166(Part 1), p.74 - 82, 2017/01

 Times Cited Count:5 Percentile:64.11(Environmental Sciences)

Large quantities of radioactive materials were released into the environment as a result of the Fukushima Daiichi Nuclear Power Station accident. Many inhabitants residing in the affected areas are now exposed to radiation in their daily lives. In an attempt to manage this radiation dose, an additional radiation dose of 1 mSv/y was adopted as a long-term dosimetric target. An activity level reading of 0.23 $$mu$$Sv/h was then determined as a guidance value to achieve the target by implementing decontamination measures. The objectives of this study are to assess the effects of decontamination based on this guidance value and to predict any possible future problems with the decontamination strategy. Using a probabilistic approach, we assessed the annual effective dose of indoor workers, outdoor workers, and pensioners in the Fukushima Prefecture. Our probabilistic model considers the variabilities in behavioral patterns and Cs-137 surface-activity levels. Five years after the initial contamination, the 95th percentiles of indoor workers and pensioners in 53 of the 59 municipalities were found to receive annual effective doses of below 1 mSv/y (0.026-0.73 mSv/y). However, for outdoor workers in 25 municipalities, the annual doses were over 1 mSv/y (1.0-35 mSv/y). Therefore, the guidance value is effective for indoor workers and pensioners; to determine whether additional countermeasures for outdoor workers should be implemented, a detailed assessment that uses more realistic assumptions is required.

Journal Articles

Investigation of snow cover effects and attenuation correction of $$gamma$$ ray in aerial radiation monitoring

Ishizaki, Azusa; Sanada, Yukihisa; Mori, Airi; Imura, Mitsuo; Ishida, Mutsushi; Munakata, Masahiro

Remote Sensing, 8(11), p.892_1 - 892_12, 2016/11

 Times Cited Count:4 Percentile:69.94(Remote Sensing)

In aerial radiation monitoring (ARM), the air dose rate cannot be appropriately estimated under snowy conditions due to attenuation of $$gamma$$ ray by the snow layer. A technique to address this issue is required for ARM to obtain enough signals for air dose rate. To develop this technique, we investigated the relationship between snow depth and ARM measurement results using ARM, laser imaging detection and ranging, and ground measurement before and after snowfall. From the measured data, the results obtained using three different correction factors were examined and compared. An appropriate correction improved the underestimation of the air dose rate. However, further improvement in the accuracy of the analysis require accurate estimation of the snow water equivalent.

JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2015 (Contract research)

Sanada, Yukihisa; Munakata, Masahiro; Mori, Airi; Ishizaki, Azusa; Shimada, Kazumasa; Hirouchi, Jun; Nishizawa, Yukiyasu; Urabe, Yoshimi; Nakanishi, Chika*; Yamada, Tsutomu*; et al.

JAEA-Research 2016-016, 131 Pages, 2016/10

JAEA-Research-2016-016.pdf:20.59MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. In addition, background dose rate monitoring was conducted around Sendai Nuclear Power Station. These results of the aerial radiation monitoring using the manned helicopter in the fiscal 2015 were summarized in the report.

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