The Ministry of Education and Science announced the annual cumulative radiation levels within the no-entry evacuation zone within the 20-kilometer radius from the Fukushima I Nuclear Power Plant, and at the highest place - 3 kilometers west by southwest of the plant - it would be 508 millisieverts in one year from March 11, 2011.
From Asahi Shinbun (8/20/2011):
文部科学省は東京電力福島第一原発から２０キロ圏内の警戒区域の積算放射線量を、１９日に公表した。原発事故発生から１年間の推計値の最高は、西南西３キロにある福島県大熊町小入野で５０８．１ミリシーベルトにのぼり、除染作業の困難さが改めて示された。最低は南相馬市小高区の３ミリシーベルト台で、数値にばらつきがあった。
On August 19 the Ministry of Education and Science announced the amount of cumulative radiation within the no-entry evacuation zone within the 20-kilometer radius from Fukushima I Nuclear Power Plant. The highest estimated cumulative radiation in one year from the day of the accident would be 508.1 millisieverts in Koirino in Okuma-machi in Fukushima Prefecture, located at 3 kilometers west by southwest of the plant. It reinforces the fear that decontamination effort would be difficult. The lowest was 3-plus millisieverts in Kodaka-ku in Minami Soma City. The numbers differ significantly within the 20-kilometer radius.
立ち入りが禁止された警戒区域９市町村のうち、８市町村の５０地点を調査。事故から来年３月１１日までの１年間、毎日、屋外に８時間、木造家屋内に１６時間いたと仮定して積算量を推計した。
Of 9 municipalities within the no-entry zone, 50 locations in 8 municipalities were surveyed. The cumulative radiation levels were estimated by assuming people would spend 8 hours outdoors, and stay 16 hours indoors in wooden houses everyday for 1 year until March 11 of 2012.
計画的避難区域指定などの際に目安とされた年２０ミリシーベルトを超えたのは、５０地点のうち３５地点。第一原発のある大熊町では全１２地点が２０ミリシーベルトを超え、うち７地点で１００ミリシーベルト以上となった。最も高い同町小入野の５０８．１ミリシーベルトは、一般の人が浴びる人工の放射線量の限度１ミリシーベルトの５００年分にあたる。
35 locations out of 50 would exceed 20 millisieverts per year, which was used to determine the planned evacuation zone. In Okuma-machi where Fukushima I Nuke Plant is located, all 12 locations surveyed would exceed 20 millisieverts, with 7 exceeding 100 millisieverts. The highest number in Koirino in Okuma-machi is 508.1 millisieverts, which is equal to 500 years worth of the annual radiation exposure limit for non-nuclear workers (1 millisievert).
浪江町では最高が北西２０キロの川房で２２３．７ミリシーベルト、最低は北８キロ地点の４．１ミリシーベルト。
In Namie-machi, the highest would be 223.7 millisieverts per year at Kawafusa, 20 kilometers northwest of the plant. The lowest would be 4.1 millisieverts at a location 8 kilometers north of the plant.
文科省によると、原発から３キロ圏内の避難住民の一時帰宅が検討されており、参考にするという。
The temporary return of residents within the 3-kilometer radius from the plant is being discussed, and this result will be consulted, according to the Ministry of Education and Science.
The national government is planning to allow the residents temporarily returning to their homes within the 20-kilometer radius to bring in their cars and load up whatever they can from their homes.