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JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2020 (Contract research)

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

JAEA-Technology 2021-029, 132 Pages, 2022/02

JAEA-Technology-2021-029.pdf:24.58MB

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 of the airborne radiation monitoring and the evaluation for temporal change of dose rate in the fiscal 2020 were summarized in this report. Analysis considering topographical effects was applied to the result of the airborne monitoring to improve the accuracy of 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.

JAEA Reports

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.

JAEA Reports

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.

JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2019 (Contract research)

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

JAEA-Technology 2020-018, 121 Pages, 2021/02

JAEA-Technology-2020-018.pdf:15.15MB

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 2019 were summarized in this report. Analysis taken topographical effects into consideration was applied to the result of airborne monitoring to improve the precision of conventional method. In addition, discrimination method of gamma rays from Rn-progenies was also utilized to evaluate their effect on aerial radiation monitoring.

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.

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

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.

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.

JAEA Reports

Assessment report of research and development on "Nuclear Safety Research" in FY2014 (Post- and pre-review report)

Kudo, Tamotsu; Onizawa, Kunio*; Nakamura, Takehiko

JAEA-Evaluation 2015-011, 209 Pages, 2015/11

JAEA-Evaluation-2015-011.pdf:10.36MB

Japan Atomic Energy Agency (JAEA) consulted an assessment committee, "Evaluation Committee of Research and Development (R&D) Activities for Nuclear Safety", for post- and pre-review assessment of R&D on nuclear safety research. In response to JAEA's request, the Committee assessed mainly the progress of the R&D project according to guidelines, which addressed the rationale behind the R&D project, the relevance of the project outcome and the efficiency of the project implementation during the period of the current and next plan. As a result, the Committee concluded that the progress of the R&D project is satisfactory. This report describes the results of evaluation by the Committee. In addition, the appendix of this report contains presentations used for the evaluation, and responses from JAEA on the comments from the member of the Committee.

JAEA Reports

Assessment report of research and development on "Nuclear Safety Research" (Interim report)

Kudo, Tamotsu; Onizawa, Kunio; Nakamura, Takehiko

JAEA-Evaluation 2013-003, 253 Pages, 2014/02

JAEA-Evaluation-2013-003.pdf:30.6MB

JAEA consulted an assessment committee, "Evaluation Committee of Research and Development (R&D) Activities for Nuclear Safety", for interim assessment of R&D on nuclear safety research in accordance with "General Guideline for Evaluation of Government R&D Activities" by Cabinet Office, Government of Japan, "Guideline for Evaluation of R&D in MEXT" and so on. In response to JAEA's request, the Committee assessed mainly the progress of the R&D project according to guidelines, which addressed the rationale behind the R&D project, the relevance of the project outcome and the efficiency of the project implementation during the period of the current midterm plan. As a result, the Committee concluded that the progress of the R&D project is satisfactory. This report describes the results of evaluation by the Committee. In addition, the appendix of this report contains presentations used for the evaluation, and responses from JAEA on the comments from the member of the Committee.

Journal Articles

Releases of cesium and poorly volatile elements from UO$$_{2}$$ and MOX fuels under severe accident conditions

Kudo, Tamotsu; Kida, Mitsuko; Nakamura, Takehiko; Nagase, Fumihisa; Fuketa, Toyoshi

Journal of Nuclear Science and Technology, 44(11), p.1421 - 1427, 2007/11

 Times Cited Count:8 Percentile:53.84(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Effects of fuel oxidation and dissolution on volatile fission product release under severe accident conditions

Kudo, Tamotsu; Kida, Mitsuko; Nakamura, Takehiko; Nagase, Fumihisa; Fuketa, Toyoshi

Journal of Nuclear Science and Technology, 44(11), p.1428 - 1435, 2007/11

 Times Cited Count:12 Percentile:66.47(Nuclear Science & Technology)

Release of volatile fission product from high burnup UO$$_{2}$$ fuel was examined in a steam atmosphere under severe accident conditions as a part of VEGA program. Effects of fuel oxidation and dissolution were totally evaluated, by comparing the results with those from previous inert, hydrogen and steam atmosphere tests. It was shown that oxidation of UO$$_{2}$$ to UO$$_{2+x}$$ by steam generally enhances Cs and Kr release. However, the enhancement becomes smaller above the melting temperature of Zircaloy, about 2030 K, likely due to reduction of UO$$_{2+x}$$ by molten Zircaloy. Quick dissolution of the fuel by molten Zircaloy and consequent burst release of Cs occur above about 2300 K in a hydrogen atmosphere, while the release rate does not increase so significantly for the examined temperature range ($$<$$2800 K) in the steam atmosphere. This corresponds to decrease in fuel dissolution rate by a factor of about 1/1000.

Journal Articles

Radionuclide release from fuel under severe accident conditions

Kudo, Tamotsu

Proceedings of 3rd Korea-Japan Joint Summer School (JSS-3) for Students and Young Researchers, p.203 - 210, 2007/08

After the TMI-2 accident, a number of experimental data on radionuclide release from fuel have been obtained in the world. However, these data were obtained under only conditions with atmospheric pressure, fuel temperature below 2900 K. And data for radionuclide release from MOX, and interactive effect of fuel oxidation and dissolution were limited. Then, the VEGA program was conducted at JAEA at pressure of 0.1 and 1.0 MPa, temperature to about 3130 K, using UO$$_{2}$$ and MOX fuels, under inert and oxidized atmosphere. The VEGA program showed that the Cs release at 1.0 MPa was smaller by about 30 % than that at atmospheric pressure, and acceleration of Cs release rate was observed above 2800 K due to foaming and melting of fuel. This article mainly describes the radionuclide release from UO$$_{2}$$ and MOX fuels, and effects of fuel oxidation and dissolution.

JAEA Reports

Summary of fuel safety research meeting 2005; March 2-3, 2005, Tokyo

Fuketa, Toyoshi; Nakamura, Takehiko; Nagase, Fumihisa; Nakamura, Jinichi; Suzuki, Motoe; Sasajima, Hideo; Sugiyama, Tomoyuki; Amaya, Masaki; Kudo, Tamotsu; Chuto, Toshinori; et al.

JAEA-Review 2006-004, 226 Pages, 2006/03

JAEA-Review-2006-004.pdf:34.43MB

Fuel Safety Research Meeting 2005, which was organized by the Japan Atomic Energy Agency was held on March 2-3, 2005 at Toshi Center Hotel, Tokyo. The purposes of the meeting are to present and discuss the results of experiments and analyses on reactor fuel safety and to exchange views and experiences among the participants. The technical topics of the meeting covered the status of fuel safety research activities, fuel behavior under Reactivity Initiated Accident (RIA) and Loss of coolant accident (LOCA) conditions, high fuel behavior, and radionuclide release under severe accident conditions. This summary contains all the abstracts and sheets of viewgraph presented in the meeting.

Journal Articles

Enhancement of cesium release from fuel due to fuel oxidation and dissolution under severe accident conditions

Kudo, Tamotsu; Nakamura, Takehiko; Kida, Mitsuko; Fuketa, Toyoshi

Proceedings of Technical Meeting on Severe Accident and Accident Management (CD-ROM), 11 Pages, 2006/03

The radionuclide release from fuel under severe accident conditions was investigated in the VEGA program. In this program, the forth test VEGA-4 was performed in the steam atmosphere using a cladded fuel. The release of cesium from the fuel in the test was slightly larger than that in an inert helium atmosphere of test VEGA-1 which used the same fuel without cladding. Oxidation of UO$$_{2}$$ by steam has been known as an important mechanism, which could increase the volatile fission product release considerably. In addition, considerable amount of fuel liquefaction by the interaction with the cladding was observed in test VEGA-4. The fuel dissolution by molten zircaloy could also affect the fission product release. This report summarizes the test VEGA-4, and impacts on the cesium release from fuel by the UO$$_{2}$$ oxidation and the dissolution are discussed.

Journal Articles

Radionuclide releases from UO$$_{2}$$ and MOX fuel under severe accident conditions

Kida, Mitsuko; Kudo, Tamotsu; Nakamura, Takehiko; Fuketa, Toyoshi

Proceedings of Technical Meeting on Severe Accident and Accident Management (CD-ROM), 10 Pages, 2006/03

no abstracts in English

Journal Articles

VEGA; An Experimental study of radionuclides release from fuel under severe accident conditions

Kudo, Tamotsu; Hidaka, Akihide*; Fuketa, Toyoshi

Proceedings of 2005 Water Reactor Fuel Performance Meeting (CD-ROM), p.883 - 889, 2005/10

The VEGA program have been performed at Japan Atomic Energy Research Institute (JAERI). The program was comprised of series of experiments on radionuclides release from fuel under severe accident conditions and post-test evaluation with numerical calculations. Effects on the release of ambient pressure, fuel temperature, inert or steam environment and MOX-effect were studied in the program. These effects had been hardly investigated in previous studies due to difficulties in experiments with high temperature and pressure conditions. Release of cesium was mitigated at elevated pressure in comparison with atmospheric pressure. Cesium release was enhanced in the temperature region where fuel foaming occurred below the melting point of UO$$_{2}$$. Release of cesium and ruthenium under steam condition was greater than that under the inert helium condition. Released mass of plutonium above 2800 K was higher by nearly three orders of magnitude than that in lower temperature than 2800 K.

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