It's all about money. The national and prefectural governments don't want to spend on the residents, decontamination, compensation. So what do they do? They return the residents to their high-radiation homes and schools by telling them Fukushima I Nuclear Power Plant is broken in a stable way, so carry on with your lives and stay there.
In addition to Yomiuri's information in the previous post, here's a bit from Asahi Shinbun (11:20PM JST 8/9/2011):
To pave way for the lifting of the "emergency evacuation-ready zone" designation in Fukushima Prefecture, the Nuclear Disaster Countermeasures Headquarters announced the result (provisional) of the survey of the air radiation levels in 1,424 locations in the 5 municipalities in the zone. The survey was done in schools, on commute routes to schools and in other public facilities. The highest and lowest readings were both in Minami Soma City, 5.5 microsieverts/hr and 0.1 microsievert/hr respectively. The house that measured 5.5 microsieverts/hr radiation has already been designated as "specific evacuation recommendation spot".
The survey was conducted in mid July. By disclosing the result, the government wants the residents to decide whether to return. The range of radiation in the other 4 municipalities were (highest, lowest, in microsievert/hour):
Tamura City: 4.0, 0.2
Kawauchi-mura: 4.7, 0.2
Hirono-machi: 1.8, 0.3
Naraha-machi: 1.6, 0.6
According to the government, if the radiation level exceeds 3 microsieverts/hour, the annual cumulative radiation exposure may exceed 20 millisieverts, the number that the government pays close attention to as it will require thorough decontamination of radioactive materials.
So, each of these 5 municipalities may have annual cumulative radiation levels of:
Minami Soma City: 0.88 to 48.18 millisieverts
Tamura City: 1.75 to 35.04 millisieverts
Kawauchi-mura: 1.75 to 41.17 millisieverts
Hirono-machi: 2.63 to 15.77 millisieverts
Naraha-machi: 5.26 to 14.02 millisieverts
That will be on top of added internal radiation and natural radiation exposure (which in Japan is 1.5 millisievert/year).
What's more unconscionable than returning the residents to these municipalities is that the governments, both national and Fukushima, never bothered to evacuate people, not even warn them, in higher radiation areas much further away from the plant, like Fukushima City, Date City, Koriyama City, and many more. They are 50 to 60 kilometers from the plant, and everyone was told their city was safe because it was so far away from the plant.
What the government didn't bother to tell them was that it was not an atomic bomb explosion where distance may have mattered, but it was a nuclear power plant explosion where weather played a much greater role than the distance.
But from early on, the government must have known that those distant cities were in big trouble. Recall that it was to Fukushima City first, that Dr. Shunichi "100 millisieverts are safe" Yamashita was dispatched on his very first assignment as Fukushima Prefecture radiation risk management advisor on March 21, one day after he was appointed.
But what was he instructed to do? We all know now that he was sent to tell everyone in those cities it was safe, nothing to worry about. Proud descendant of Byakko-tai, he addressed the Fukushima City residents. As if it were their noble duty to die, fighting the invisible radiation.
The Japanese government has become so much alike the government in the US, where they try to accomplish the task of governing by talking. A sign of a bankrupt government, both fiscally and morally.
Oh, and to make sure the residents who are not well-to-do have no choice but to come back, the Fukushima prefectural government has been closing the official evacuation shelters and cutting off the subsidies to the residents who fled to other prefectures, now that the nuke plant is "stable".