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Journal Articles

Development of an external radiation dose estimation model for children returning to their homes in areas affected by the Fukushima Nuclear Accident

Mori, Airi; Takahara, Shogo; Yoshida, Hiroko*; Sanada, Yukihisa; Munakata, Masahiro

Health Physics, 117(6), p.606 - 617, 2019/12

 Times Cited Count:0 Percentile:100(Environmental Sciences)

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

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

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

Examination of decontamination of various materials at houses in difficult-to-return zone

Mori, Airi; Tanabe, Tsutomu; Wada, Takao; Kato, Mitsugu

JAEA-Technology 2017-006, 38 Pages, 2017/03

JAEA-Technology-2017-006.pdf:2.98MB

Large quantities of radioactive materials were released into the environment as a result of the Fukushima Daiichi Nuclear Power Station accident. Residential areas and forest areas near the power station were contaminated with the radioactive materials. Outside of the houses, schools and the other buildings are being decontaminated by national authority and local government. On the other hand, the materials (such as walls, floors, or windows) which constitute the houses are not decontaminated officially. In order to prepare decontamination methods that can be applied easily, we conducted examinations of decontamination for various materials in houses. Fibrous materials, woods, glasses, concretes, plastics, vinyl chloride materials, metals and synthetic leathers were used in our examinations. These materials were collected from houses in difficult-to-return zone, and were contaminated by radioactive materials released by the accident. Dry methods (suction, wiping, adsorption and peelable coating), wet methods (wiping, brushing, polishing and washing) and physical method (peeling of materials) were used for decontamination. As a result of our examinations, materials with low water permeability, such as glasses, concretes, vinyl chloride materials and metals, were able to be decontaminated efficiently (about 90% reduction) by using wet methods. Materials with high water permeability like woods were relatively well decontaminated by peelable coating (about 60%-70% reduction). In addition to the examination described above, the difference of contamination reduction effect between chemical properties of detergents and the effect of rubbing of peelable coating were also examined. Finally, the most effective method was summarized based on these examinations.

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:63.24(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:69.54(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.

JAEA Reports

Radiation monitoring using manned helicopter around the Fukushima Daiichi Nuclear Power Station in the fiscal year 2014 (Contract research)

Sanada, Yukihisa; Mori, Airi; Ishizaki, Azusa; Munakata, Masahiro; Nakayama, Shinichi; Nishizawa, Yukiyasu; Urabe, Yoshimi; Nakanishi, Chika; Yamada, Tsutomu; Ishida, Mutsushi; et al.

JAEA-Research 2015-006, 81 Pages, 2015/07

JAEA-Research-2015-006.pdf:22.96MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (NPS), 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 NPP. These results of the aerial radiation monitoring using the manned helicopter in the fiscal 2014 were summarized in the report.

Journal Articles

$$mu$$SR study of impurity effects on the Cu-spin fluctuations in the overdoped regime of La$$_{2-x}$$Sr$$_x$$Cu$$_{1-y}$$Zn$$_y$$O$$_4$$

Risdiana*; Adachi, Tadashi*; Oki, Naoki*; Yairi, Satoshi*; Tanabe, Yoichi*; Omori, Keisuke*; Suzuki, Takao*; Watanabe, Isao*; Koda, Akihiro*; Higemoto, Wataru; et al.

Physica C, 460-462(2), p.874 - 875, 2007/09

 Times Cited Count:3 Percentile:80.45(Physics, Applied)

Zero-field muon-spin-relaxation measurements have been carried out for La$$_{2-x}$$Sr$$_x$$Cu$$_{1-y}$$Zn$$_y$$O$$_4$$ (LSCO)with $$y$$ = 0-0.10 in the overdoped regime up to $$x$$ = 0.30, in order to investigate whether the dynamical stripe correlations are pinned and stabilized even for the overdoped LSCO or not. It has been found that the Zn-induced slowing down of the Cu-spin fluctuations is weakened with increasing $$x$$ but takes place in the overdoped regime and disappears at $$x$$ = 0.30. This suggests that the stripe-pinning model holds good in the whole superconducting regime of LSCO and that there is no quantum critical point at $$x$$ $$sim$$ 0.19.

Oral presentation

Investigation and utilization of removal factors of the various materials constituting the houses in areas to which evacuation orders

Mori, Airi; Ishizaki, Azusa; Imura, Mitsuo*; Munakata, Masahiro

no journal, , 

no abstracts in English

Oral presentation

Assessment of doses from the contamination inside house in evacuation area

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

no journal, , 

no abstracts in English

Oral presentation

Advancement of airborne radiation measurement technology, 4; Investigation of snow effects on aerial monitoring

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

no journal, , 

no abstracts in English

Oral presentation

Development of dose assessment model for children after returning to evacuation areas

Mori, Airi; Takahara, Shogo; Sanada, Yukihisa; Munakata, Masahiro

no journal, , 

Inhabitants residing in part of Fukushima Prefecture are now exposed to radiation due to radioactive materials released by the Fukushima Daiichi Nuclear Power Station accident. To mitigate the radiation doses, an additional dose of 1 mSv/y was adopted as a long-term dosimetric target, and some municipalities were designated as the evacuation area. The evacuation area has been narrowing along with the decreasing of air dose rate. It was decided that evacuation orders in parts of 5 municipalities are lifted in 2016-2017. Radiation dose will be an important information for the inhabitants to make a decision on whether to return or not. Many inhabitants are concerned about radiation doses, particularly doses to their children. In this study, we developed the dose assessment model for children to estimate radiation doses to children that returned to their hometown. As a result of our calculation, it was revealed that the doses will not cause any health effect but continual efforts to achieve the dosimetric target of 1 mSv/y are necessary.

Oral presentation

Estimation of dose reduction factor before and after decontamination

Ishizaki, Azusa; Mori, Airi; Kawase, Keiichi; Kato, Mitsugu; Watanabe, Masanori; Aoki, Isao; Munakata, Masahiro

no journal, , 

Oral presentation

Advancement of airborne radiation measurement technology, 1; Contribution of position precision by GPS for manned helicopter monitoring

Mori, Airi; Sanada, Yukihisa; Seguchi, Eisaku; Kawabata, Tomoki; Munakata, Masahiro

no journal, , 

Count rates of radiation and the positional information (latitude, longitude, and height) are acquired simultaneously in airborne monitoring. The precision of positional information affects the air dose rates at 1 m height because air dose rates at 1 m height are calculated by correction of height. In this study, 3 GPS devices are used in addition to 1 GPS device which has been used in previous airborne monitoring. The most appropriate GPS device were determined by comparing precisions of positional information and influences on air dose rates at 1 m height.

Oral presentation

Characterization of removal factor of materials used for smear method on house material

Hamazaki, Masaaki; Mori, Airi; Abe, Haruka; Goibuchi, Shota; Iwasa, Atsutoshi; Ishida, Keiichi; Usui, Toshihide; Eguchi, Kazutoshi; Nakada, Akira

no journal, , 

no abstracts in English

21 (Records 1-20 displayed on this page)