I just wanted to point out something about the footage I have seen with regard to monitoring the public in the area of the nuclear disaster in Japan. I only mention this because to the best of my knowledge it has not been stated elsewhere.
A number of years ago I used to work in the nuclear industry measuring radiation levels. I am wondering why the monitors have plastic bags over their radiation detectors whilst measuring radiation levels. It is well known that different radioactive particles have different abilities to penetrate materials. The three main types are Alpha, Beta and Gamma. Gamma is the most penetrating followed by Beta and then Alpha. Alpha is unable to penetrate even a piece of paper, so I doubt it will be able to penetrate a plastic bag either, unless the bag is made from a "special material."
My point is that using a covering device over the detector will mean that people will not be aware of high levels of Alpha contamination and could be used as a way of giving the public false readings especially if there is alot of Alpha contamination about. Although Alpha radiation is the least penetrating it is also the MOST ionising radiation and so is more serious from a health point of view. If people inhale or are otherwise contaminated with an Alpha emitting material they run a much higher risk of developing cancers or other health problems.
It would be necessary to consult an expert in Radiological Protection to get their views on this topic as they will be up to date on the use of modern instrumentation and techniques. Also how much Alpha emitting material is likely to be involved in the disaster. Personally I believe it will be quite alot.