Japan imposes ban on nuclear zone not based on radiation dose

"Japan's government announced Thursday it is creating a formal ban on entry into the 20-kilometer evacuation zone around the quake-hit Fukushima Daiichi nuclear-power plant after some residents ignored pleas to stay away from the potentially hazardous areas.

The announcement came as workers at the plant are pumping water that is flooding the basement of the turbine building for reactor No. 2, which contains more than 30 million times Japan's allowable level of Cesium-137, a long-lived radioactive isotope." The Wall Street Journal

"Japanese authorities have decided to revise a marginal portion of the Fukushima evacuation zone and police the area more strictly. The government said the zone is not forced by dose rates within it, but remains a precaution until the plant comes under full control." World Nuclear News