Results of Airborne Monitoring Survey by MEXT in Tokyo Metropolitan and Kanagawa Prefecture

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Theodore Dickerson
5 years ago
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1 October 6, 2011 Results of Airborne Monitoring Survey by MEXT in Tokyo Metropolitan and Kanagawa Prefecture The results of the airborne monitoring survey by MEXT in Tokyo Metropolitan and Kanagawa Prefecture (announced on September 13, 2011) were summarized today, so they are provided here. 1. Objective of the monitoring MEXT has conducted airborne monitoring * within a 100 km zone from the Fukushima Dai-ichi NPP (up to around 120 km in the southern area of the Fukushima Dai-ichi NPP), so as to ascertain the wide-area distribution of radioactive substances and assess future doses and deposition of radioactive substances in evacuation zones, etc. In addition, airborne monitoring was also conducted in Tokyo Metropolitan and Kanagawa Prefecture, where airborne monitoring has never been conducted, for the purpose of ascertaining the effects of radioactive substances over a wider area. This monitoring was conducted by the staff of the FUGRO Airborne Surveys (Australian company) and the Japan Atomic Energy Agency using the FUGRO Airborne Surveys airborne monitoring system installed in a private helicopter. The results were analyzed by the Japan Atomic Energy Agency. *Airborne monitoring is a technique in which highly sensitive, large radiation detectors are installed in an aircraft, and gamma rays from radioactive substances accumulated in the ground are quickly measured over a large area, in order to check the surface deposition. 2. Details of this monitoring Monitoring period: 14 September to18 September Aircraft: A private helicopter (AS350B1) Items covered: Air dose rate at 1 m above the ground surface in Tokyo Metropolitan and Kanagawa Prefecture, and deposition of radioactive cesium on the ground surface

2 3. Results of the monitoring Maps showing the distribution of air dose rates at 1 m above the ground surface and maps showing the deposition of radioactive substances on the soil surface in Tokyo Metropolitan and Kanagawa Prefecture (Attachments 1 to 8) are based on the results of this monitoring survey. Furthermore, to verify the spread of radioactive substances, we also prepared maps combining this result and the past results of airborne monitoring surveys that MEXT had conducted so far. The results are as shown in References 1 to 4. Maps were prepared under the following conditions. The monitoring survey was based on the measurement results obtained through eight flights by one helicopter from September 14 to September 18. The flight altitudes were from 150 to 300 m above the ground surface, and the measured values were the averages of the measurements in circles with a diameter of around 300 to 600 m (varies according to flight altitude) below the aircraft. The spacing of flights was around 3 km in this monitoring survey. In the map of air dose rates in Tokyo Metropolitan and Kanagawa Prefecture (Attachment 1 and 5), decay corrections were performed according to the final day of the monitoring (September 18). The values of the concentration of Cs-134 and Cs-137 deposited on the ground surface in Tokyo Metropolitan and Kanagawa Prefecture, as shown in Attachments 2 to 4 and 6 to 8, were calculated based on the results of this monitoring survey, as well as the correlation between air dose rates and the results of the in-situ measurement using germanium semiconductor detectors that was conducted by the Japan Chemical Analysis Center in the course of the project under the 2011 Strategic Funds for the Promotion of Science and Technology, entitled Establishment of the Base for Taking Measures for Environmental Impact of Radioactive Substances Study on Distribution of Radioactive Substances. Maps as shown in References 1 to 4 were prepared by combining the following results. Within 80 km from the Fukushima Dai-ichi NPP: The third airborne monitoring survey Within 80 to 100 km from the Fukushima Dai-ichi NPP (regarding the southern area of Fukushima Dai-ichi NPP, up to around 120 km): The second airborne monitoring survey Other prefectures, excluding Tokyo and Kanagawa prefectures: The airborne monitoring surveys conducted so far in respective prefectures Tokyo Metropolitan and Kanagawa Prefecture: This monitoring survey In the maps, decay corrections were performed according to the final day of the monitoring (September 18).

3 Emergency Operation Center Horita, Oku Tel : Ex.4604, 4605

4 別紙 1 文部科学省による東京都及び神奈川県の航空機モニタリングの測定結果について ( 東京都内の地表面から 1m 高さの空間線量率 )

5 別紙 2 文部科学省による東京都及び神奈川県の航空機モニタリングの測定結果について ( 東京都内の地表面へのセシウムの沈着量の合計 )

6 別紙 3 文部科学省による東京都及び神奈川県の航空機モニタリングの測定結果について ( 東京都内の地表面へのセシウム 134 の沈着量 )

7 別紙 4 文部科学省による東京都及び神奈川県の航空機モニタリングの測定結果について ( 東京都内の地表面へのセシウム 137 の沈着量 )

8 別紙 5 文部科学省による東京都及び神奈川県の航空機モニタリングの測定結果について ( 神奈川県内の地表面から 1m 高さの空間線量率 )

9 別紙 6 文部科学省による東京都及び神奈川県の航空機モニタリングの測定結果について ( 神奈川県内の地表面へのセシウムの沈着量の合計 )

10 別紙 7 文部科学省による東京都及び神奈川県の航空機モニタリングの測定結果について ( 神奈川県内の地表面へのセシウム134の沈着量 )

11 別紙 8 文部科学省による東京都及び神奈川県の航空機モニタリングの測定結果について ( 神奈川県内の地表面へのセシウム 137 の沈着量 )

12 ( 参考 1) 文部科学省による東京都及び神奈川県の航空機モニタリングの測定結果について ( 文部科学省がこれまでに測定してきた範囲及び東京都及び神奈川県内における地表面から1m 高さの空間線量率 )

13 ( 参考 2) 文部科学省による東京都及び神奈川県の航空機モニタリングの測定結果について ( 文部科学省がこれまでに測定してきた範囲及び東京都及び神奈川県内の地表面へのセシウムの沈着量の合計 )

14 ( 参考 3) 文部科学省による東京都及び神奈川県の航空機モニタリングの測定結果について ( 文部科学省がこれまでに測定してきた範囲及び東京都及び神奈川県内の地表面へのセシウム134の沈着量 )

15 ( 参考 4) 文部科学省による東京都及び神奈川県の航空機モニタリングの測定結果について ( 文部科学省がこれまでに測定してきた範囲及び東京都及び神奈川県内の地表面へのセシウム137の沈着量 )

Results of Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefectures

November 25, 2011 Results of Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefectures The results of the airborne monitoring survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui