While the entire nation and the entire world wait with bated breath for the declaration by the Japanese national government of a cold shutdown of Fukushima I Nuclear Power Plant (to be exact, as NY Times correctly reported on December 14, "state of a cold shutdown") later in the evening of December 16 Japan Standard Time, the working group of government radiation experts has declared that:
Annual radiation exposure of more than 100 millisieverts is known to raise risks for developing cancers, but nothing is known about annual radiation exposure of less than 100 millisieverts;
Annual cumulative radiation exposure (external only, it seems) of 20 millisieverts for the general public poses hardly any danger of developing cancer;
There is no difference between internal and external radiation exposure;
Low-dose radiation exposure over a long period of time is less risky than one-time episodic exposure to large-dose radiation;
The relationship between low-dose internal radiation exposure and bladder cancer cannot be proven.
Above points are from the article in Mainichi Shinbun 12/15/2011, the only paper that had any critical thinking on this issue. All the other large-circulation newspapers and NHK simply parroted what was said by the experts and the government officials.
Speaking of government officials, Asahi Shinbun reports (12/15/2011) that Minister in charge of the nuclear accident and Minister of the Environment Goshi Hosono explained the government's thinking in the press conference after the group meeting, saying:
"So, 20 millisieverts per year radiation means people can live there."
This working group of so-called experts met for about a month to discuss the risk of "low-level" radiation exposure (meaning less than 20 millisieverts per year) and make a decision. Now they have made the decision and submitted the report to the government, the government duly accepts the independent experts' opinion, declares 20 millisieverts radiation to be an acceptable guideline, and plan accordingly.
What's the plan, you ask?
The government is set to convene a cabinet meeting in the evening and declare a "cold shutdown state" and will soon declare certain municipalities within the 20-kilometer radius "no entry" zone to be now "safe" to return (see my previous post).
In that country, if the government declares "one plus one equals four", or "tomorrow the sun rises from the west", people are expected to say "of course", and the calculators would start showing one plus one equals 4 and the sun would rise from the west. Or at least they would try. The land of miracles.
20 millisieverts per year of radiation exposure for the general public. There is no mention of different standard for children, except for the "effort" that the government is supposed to exert to lower the radiation for children.
Radiation control zone is 1.3 millisieverts per 3 months (5.2 millisieverts per year).