Afraid of a "chaos" in the harvest season, perhaps?After more than 4 months since the Fukushima I Nuclear Power Plant accident started, the Japanese government must be feeling it safe to admit to a far wider contamination by radioactive fallout.
The Ministry of Education and Science announced that it will conduct the aerial survey of 23 prefectures (out of total 47) to determine the level of soil contamination. For some reason, Hokkaido is excluded, but every prefecture from Aomori to Shiga, which is located about in the middle of the Honshu Island will be surveyed. It's all of Tohoku, Kanto, Chubu-Hokuriku.
(In the map, Hokuriku is bundled with Chubu; Hokuriku includes prefectures facing the Japan Sea. For more details within the regions, go to the web-japan.org page.)
If I were the official at the Ministry, I would test Hokkaido, too. I have seen too many radioactive plumes sweeping the island of Hokkaido in the simulation animations by several European meteorological institutions. (For the latest from the German Weather Bureau, go here. But even they will stop publishing the dispersion map on July 29... )
From NHK News Japanese (4:28AM JST 7/26/2011):
東京電力福島第一原子力発電所の事故の影響で広がった放射性物質の範囲を調べるため、文部科学省は、青森県から滋賀県までの２３の都と県で、ヘリコプターを使って上空から土壌の汚染状況の調査を行うことになりました。
The Ministry of Education and Science will conduct the aerial survey using helicopters to determine the level of soil contamination from radioactive materials released from Fukushima I Nuclear Power Plant. The survey will be conducted in 23 prefectures from Aomori to Shiga.
文部科学省は、福島第一原発の事故で拡散した放射性物質の状況を上空からヘリコプターを使って福島県や宮城県で調べていて、今月２０日には、宮城県の土壌汚染マップを公表しています。上空からの土壌汚染の調査は、ほかの県からも調査の要請が相次いだことから、文部科学省は、青森県から滋賀県までの２３の都と県で行うことになりました。調査は、自治体のヘリコプターを利用して行われ、上空１５０メートルから３００メートル付近より、大型の検出器を使ってガンマ線の量を測定し、地上付近の値を換算することにしています。調査は、２６日から茨城県でも始まる予定で、年内には予定している宮城、秋田、山形、岩手、福島、青森、東京、長野、新潟、山梨、神奈川、群馬、茨城、千葉、栃木、埼玉、愛知、石川、静岡、福井、冨山、岐阜、滋賀の２３都県すべてで終えたいとしています。
The Ministry has been conducting the aerial survey in Fukushima and Miyagi Prefectures, and on July 20 disclosed the soil contamination map of Miyagi Prefecture. There have been requests for the aerial survey for soil contamination, so the Ministry has decided to do it in 23 prefectures. The survey will be done using the helicopters owned by the prefectures. The gamma rays will be measured from a large gamma-ray detector on board the helicopter from 150 to 300 meters from the ground, and the radiation level near the ground surface will be calculated. The survey will start in Ibaraki Prefecture on July 26. The Ministry hopes to finish the survey in all 23 prefectures by the end of this year. The prefectures are: Miyagi, Akita, Yamagata, Iwate, Fukushima, Aomori, Tokyo Nagano, Niigata, Yamanashi, Kanagawa, Gunma, Ibaraki, Chiba, Tochigi, Saitama, Aichi, Ishikawa, Shizuoka, Fukui, Toyama, Gifu, Shiga.