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

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1 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 prefectures (Aichi announced on October 13, 2011; Aomori announced on October 6, 2011; Ishikawa announced on October 14, 2011; and Fukui announced on October 14, 2011) were concluded today, so they are provided here. 1. Objective of the monitoring in Aichi, Aomori, Ishikawa, and Fukui Prefectures MEXT has conducted airborne monitoring* within the 100 km zone from the Fukushima Dai-ichi NPP (up to around 120 km in the southern part of the Fukushima Dai-ichi NPP) and in neighboring prefectures so as to ascertain the wide-area distribution of radioactive substances and evalute future doses and deposition of radioactive substances in evacuation zones, etc. In addition, airborne monitoring was also conducted in Aichi, Aomori, Ishikawa, and Fukui prefectures, for the first time in order to ascertain influences of radioactive substances in wider areas. This monitoring was conducted under the following systems in respective prefectures The airborne monitoring survey in Aichi was conducted by the staff of the Japan Atomic Energy Agency using a private helicopter with an airborne monitoring system borrowed from the U.S. Department of Energy. The airborne monitoring survey in Aomori was conducted by the staff of the Nuclear Safety Technology Center using a private helicopter equipped with an airborne monitoring system of MEXT. The airborne monitoring survey in Ishikawa was conducted by the staff of the OYO Corporation and the Japan Atomic Energy Agency using a dedicated private helicopter that can be equipped with an airborne monitoring system of the OYO Corporation. The airborne monitoring survey in Fukui was conducted by the staff of the FUGRO Airborne Surveys (Australian company) and the Japan Atomic Energy Agency using a private helicopter equipped with an airborne monitoring system owned by the FUGRO Airborne Surveys. These measurement results were analyzed by the Japan Atomic Energy Agency. *Airborne monitoring is a method to measure gamma rays from radioactive substance

2 accumulated in the ground quickly over a large area by using aircraft equipped with highly sensitive, large radiation detectors in order to confirm the influences from the surface deposition. 2. Details of the monitoring Monitoring periods: (i) Aichi: October 16 to October 20 (8 flights in total) (ii) Aomori: October 7 to November 1 (17 flights in total) (iii) Ishikawa: October 17 to October 24 (16 flights in total) (iv) Fukui: October 17 to October 20 (7 flights in total) Aircraft: (i) Aichi: a private helicopter (BELL412SP) (ii) Aomori: a private helicopter (BELL412) (iii) Ishikawa: a private helicopter (AS350B3) (iv) Fukui: a private helicopter (AS350B1) Items covered: Air dose rate at 1 m above the ground surface and deposition of radioactive cesium on the ground surface in Aichi, Aomori, Ishikawa, and Fukui prefectures 3. Results of the monitoring and revision of the past monitoring results 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 Aichi, Aomori, Ishikawa, and Fukui prefectures (Attachments 1 to 16) 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 flight altitudes were from 150 to 300 m above the ground and the values of this monitoring survey are the averages of the measured values in circles with a diameter of around 300 to 600m (varies by flight altitude) below the aircraft. The width of the track is around 3 km in this monitoring survey. As flights are difficult in mountainous areas over 2,000 m in height, there were no data available for such areas. When preparing maps of air dose rates and maps of deposition amounts of radioactive cesium (Attachments 1 to 16), the attenuation-compensated values as of the final day of the monitoring in respective prefectures were used. Maps as shown in References 1 to 4 were comprehensively based on the following results. When preparing these maps, the attenuation-compensated values as of the final day of the monitoring in Aomori (November 1) were used.

3 Within 80 km from the Fukushima Dai-ichi NPP: Results of the third airborne monitoring survey Within 80 to 100 km from the Fukushima Dai-ichi NPP (regarding the southern part of Fukushima Dai-ichi NPP, up to around 120 km): Results of the second airborne monitoring survey Prefectures other than Aichi, Aomori, Ishikawa, and Fukui: Results of airborne monitoring survey conducted in respective prefectures so far Aichi, Aomori, Ishikawa, and Fukui: Results of this monitoring survey As attenuation compensation methods, air dose rates are calculated by subtracting the average air dose rates due to natural radionuclides throughout all of East Japan from the measured values and further considering physical attenuation of Cs-134 and Cs-137 from the measurement time up to a specified time. On the other hand, deposition amounts of Cs-134 and Cs-137are evaluated by taking into account physical attenuation from the measurement time up to a specified time. The new method adopted for compiling the results of airborne monitoring in Iwate prefecture, etc. (already publicized on November 11) was again used to prepare maps of the deposition of radioactive cesium, that is, to assess the characteristics of energy spectra of gamma-rays measured in the air with respect to each type of helicopter and measuring instruments used, to sort out areas according to whether energy spectra of radioactive cesium (Cs-134 and Cs-137) were detected significantly or not, and then to prepare maps of the deposition of radioactive cesium. The details are as follows. (i) With regard to areas where energy spectra of radioactive cesium were detected significantly, the deposition amounts of Cs-134 and Cs-137 on the ground surface were calculated by subtracting the average air dose rates due to natural radionuclides throughout all of East Japan from the values measured at respective airborne monitoring points, and were based on the correlation between air dose rates and the results of the in-situ measurement using germanium semiconductor detectors, which was conducted by the Japan Chemical Analysis Center in the course of the project, 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. (ii) Areas where energy spectra of radioactive cesium were not detected significantly are indicated on maps as areas showing the minimum range of radioactive cesium ( 10kBq/m 2 ) for the sake of simplicity. This method is effective in identifying 99.7% of the areas where energy spectra of radioactive cesium were not detected significantly, but the remaining 0.3% of such areas cannot be identified. Therefore, some of these areas are indicated as areas where the deposition of radioactive cesium is 10kBq/m 2 or higher due to the influences of natural

4 radionuclides, although energy spectra of radioactive cesium were not actually detected significantly. 4. Considerations on the results of the past airborne monitoring surveys The results of the past airborne monitoring surveys show the influences of radiation throughout all of East Japan (Tokyo and 21 other prefectures), through which we could ascertain the distribution of air dose rates and deposition amounts of radioactive cesium in each region. This monitoring survey further clarifies the influences of natural radionuclides in East Japan, for which no detailed measurement data had been available. Examining the past airborne monitoring survey results, while taking land forms into consideration, we confirmed that radioactive cesium has been deposited alongside of the Ou Mountain Range, Iide Mountain Range, Echigo Mountain Range, Shimotsuke Mountains, and Kanto Mountains (see Reference 5). As explained above, the results of this airborne monitoring survey are expected to be utilized for assessment of radiation exposure doses, provision for decontamination, examining the current status of radioactive plumes, elucidation of the route for radioactive substances were deposited on the ground surface, and ascertaining changes with the passage of time in the deposition of radioactive substances in the future. 5. Future plans With this publication, compilation of the results of airborne monitoring survey for all of East Japan (Tokyo and other 21 prefectures) was completed, and we were able to ascertain the effects of radioactive substances emitted from the Fukushima Dai-ichi NPP over a wide area. On the other hand, monthly measurements of fallout by MEXT shows that radioactive cesium has fallen down in Hokkaido and West Japan, as well, although in a small amount (see Reference 6). Therefore, MEXT will conduct an airborne monitoring survey also in Hokkaido and West Japan, which have not been covered so far, so as to ascertain that the deposition of radioactive cesium is small in these regions. Emergency Operation Center Horita, Oku Tel : Ex.4604, 4605

Readings of the Airborne Monitoring Survey by MEXT in

rates at 1 m above the ground surface in Aichi

the ground level ( Sv/hr) [Compensated value as of

5 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Air dose rates at 1 m above the ground surface in Aichi prefecture) Attachment 1 Air dose rate at 1 meter above the ground level ( Sv/hr) [Compensated value as of October 20] This map includes air dose rates due to natural radionuclides.

6 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Total accumulation of Cs-134 and Cs-137 on the ground surface in Aichi prefecture) 2 Attachment 2 Total deposition of Cs-134 and Cs-137 Bq/m2 [Compensated value as of October 20]

7 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Deposition of Cs-134 on the ground surface in Aichi prefecture) 3 Attachment 3 Deposition of Cs-134 Bq/m2 [Compensated value as of October 20]

8 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Deposition of Cs-137 on the ground surface in Aichi prefecture) 4 Attachment 4 Deposition of Cs-137 Bq/m2 [Compensated value as of October 20]

9 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Air dose rates at 1 m above the ground surface in Aomori prefecture) 5 Attachment 5 Air dose rate at 1 meter above the ground level ( Sv/hr) [Compensated value as of November 1] This map lncludes air dose rates due to natural radionuclides.

10 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Total deposition of Cs-134 and Cs-137 on the ground surface in Aomori prefecture) Total deposition of Cs-134 and Cs-137 Bq/m2 [Compensated value as of November 1] 6 Attachment 6

11 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Deposition of Cs-134 on the ground surface in Aomori prefecture) 7 Attachment 7 Deposition of Cs-134 Bq/m2 [Compensated value as of November 1]

surface in Aomori prefecture) Deposition

12 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Deposition of Cs-137 on the ground surface in Aomori prefecture) Deposition of Cs-137 Bq/m2 [Compensated value as of November 1] 8 Attachment 8

Attachment 9 Air dose rate at 1 meter above the ground level ( Sv/hr) [Compensated value

13 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Air dose rates at 1 m above the ground surface in Ishikawa prefecture) 9 Attachment 9 Air dose rate at 1 meter above the ground level ( Sv/hr) [Compensated value as of October 24] were not obtained This map includes air dose rates due to natural radionuclides.

14 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Total deposition of Cs-134 and Cs-137 on the ground surface in Ishikawa prefecture) 10 Attachment 10 Total deposition of Cs-134 and Cs-137 Bq/m2 [Compensated value as of October 24] were not obtained

15 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Deposition of Cs-134 on the ground surface in Ishikawa prefecture) Attachment 1111 Deposition of Cs-134 (Bq/m2) [Compensated value as of October 24]

16 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Deposition of Cs-137 on the ground surface in Ishikawa prefecture) Attachment 1212 Deposition of Cs-137 (Bq/m2) [Compensated value as of October 24] were not obtained

17 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Air dose rates at 1 m above the ground surface in Fukui prefecture) 13 Attachment 13 Air dose rate at 1 meter above the ground level (μsv/hr) [Compensated value as of October 20] This map includes air dose rates due to natural radionuclides.

18 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Total deposition of Cs-134 and Cs-137 on the ground surface in Fukui prefecture) Attachment Total deposition of Cs-134 and Cs-137 (Bq/m2) [Compensated value as of October 20]

19 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Deposition of Cs-134 on the ground surface in Fukui prefecture) Deposition of Cs-134 Bq/m2 [Compensated value as of October 20] Attachment Maps in the background: by Denshi Kokudo

20 Attachment 1616 Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa, and Fukui Prefecture (Deposition of Cs-137 on the ground surface in Fukui prefecture) Deposition of Cs-137 Bq/m2 [Compensated value as of October 20]

(Reference 1) Readings of the Airborne Monitoring Survey

(Air dose rates at the height of 1 m above the ground

and other areas where MEXT has conducted airborne

) Fukushima Dai-ichi NPP Legend Air dose rate at 1 m

21 (Reference 1) Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa and Toyama Prefecture. (Air dose rates at the height of 1 m above the ground surface in Aichi, Aomori, Ishikawa and Toyama Prefecture and other areas where MEXT has conducted airborne monitoring surveys.) Fukushima Dai-ichi NPP Legend Air dose rate at 1 m above ground level ( Sv/h) [Converted into the value as of November 1] Involving air dose rates of natural nuclides

22 (Reference 2) Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa and Toyama Prefecture. (Total accumulation of Cs-134 and Cs-137 on the ground surface in Aichi, Aomori, Ishikawa and Toyama Prefecture and other areas where MEXT has conducted airborne monitoring surveys.) Fukushima Dai-ichi NPP Legend Total accumulation of Cs-134 and Cs-137 (Bq/m 2 ) [Converted into the value as of November 1]

23 (Reference 3) Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa and Toyama Prefecture. (Accumulation of Cs-134 on the ground surface in Aichi, Aomori, Ishikawa and Toyama Prefecture and other areas where MEXT has conducted airborne monitoring surveys.) Fukushima Dai-ichi NPP Legend Accumulation of Cs-134 (Bq/m 2 ) [Converted into the value as of November 1]

(Accumulation of Cs-137 on the ground surface in Aichi, Aomori, Ishikawa and Toyama Prefecture

24 (Reference 4) Readings of the Airborne Monitoring Survey by MEXT in Aichi, Aomori, Ishikawa and Toyama Prefecture. (Accumulation of Cs-137 on the ground surface in Aichi, Aomori, Ishikawa and Toyama Prefecture and other areas where MEXT has conducted airborne monitoring surveys.) Fukushima Dai-ichi NPP Legend Accumulation of Cs-137 (Bq/m 2 ) [Converted into the value as of November 1]

(Reference 5) Relation between Landform and Deposition of

confirmed that radioactive cesium has been deposited

Mountain Range, Shimotsuke Mountains, and Kanto Mountains

Iide Mountains Ou Mountain Range Legend Total accumulation of

13] From 250km above in the air 170km offshore Fukushima

*Vertically enlarged ( 5) *Measurement results of 10kBq/m 2

25 (Reference 5) Relation between Landform and Deposition of Radioactive Cesium Measured by Airborne Monitoring It is confirmed that radioactive cesium has been deposited alongside the Ou Mountain Range, Iide Mountain Range, Echigo Mountain Range, Shimotsuke Mountains, and Kanto Mountains Kanto Mountains Echigo Mountain Range Shimotsuke Mountains Iide Mountains Ou Mountain Range Legend Total accumulation of Cs-134 and Cs-137 [Converted to values as of Oct. 13] From 250km above in the air 170km offshore Fukushima Fukushima Dai-ichi NPP Areas without measurement results *Vertically enlarged ( 5) *Measurement results of 10kBq/m 2 or less (the total deposition of Cs-134 and Cs-137) are omitted from the map to clarify the relevant relations.

26 Relation between Landform and Deposition of Radioactive Cesium Measured by Airborne Monitoring (Enlarged) Tochigi Prefecture Ou Mountain Range Fukushima Prefecture Fukushima Prefecture Yamagata Prefecture Iide Mountains [Enlarged] Fukushima Prefecture, Nakadori [Enlarged] Border between Fukushima and Yamagata (Iide Mountains) Nagano Prefecture Nagano Prefecture Gunma Prefecture Echigo Mountain Range Kanto Mountains Yamanashi Prefecture Gunma Prefecture Saitama Prefecture [Enlarged] Southern end of the Echigo Mountain Range [Enlarged] Kanto Mountains

1. Objective of this monitoring in Hokkaido

1. Objective of this monitoring in Hokkaido July 27, 2012 (i) Results of Airborne Monitoring Survey in Hokkaido and (ii) Revision to the Results of Airborne Monitoring Survey over the Eastern Part of Japan with Detailed Consideration of the Influence