'The areas to be kept off-limits will likely include parts of Futabamachi and Okumamachi, both in Fukushima Prefecture. They are within three kilometers of the nuclear plant crippled by March 11 disaster.
The areas could be kept off-limits for "several decades," according to government sources.
In April, the government designated the 20-kilometer no-entry zone around the Fukushima No. 1 power plant. The government had planned to lift the no-entry zone after the reactors at the nuclear plant are brought to a stable condition known as cold shutdown by mid-January.
However, the Education, Culture, Sports, Science and Technology Ministry estimated that cumulative radiation levels during the year since the accidents at the plant would greatly exceed 20 millisieverts--the benchmark for designating an expanded evacuation zone--at 35 locations mainly in Okumamachi and Futabamachi in the no-entry zone.
The annual cumulative radiation level was calculated to reach 508.1 millisieverts in the Koirino district of Okumamachi, which is three kilometers west-southwest of the nuclear plant, and 393.7 millisieverts in Ottozawa in the town.
The ministry measured radiation levels at 50 locations in the no-entry zone. It estimated annual cumulative radiation levels on the assumption that residents are outside for eight hours a day and inside wooden homes for 16 hours a day.
The government decided that areas very close to the Fukushima No. 1 nuclear plant will be uninhabitable for an extended period because they are heavily contaminated with radioactive substances and could suffer further serious damage if another major problem occurs at the plant.'http://www.yomiuri.co.jp/dy/national/T110821002920.htm