There has been much concern and media hype about the radiation leaks from Japan’s Fukushima nuclear reactor damage. One of the best summaries I’ve seen is from the Nuclear Science and Engineering department at M.I.T. Their short article explains radiation units and the health consequences of various exposure doses, and it discusses how much radiation actually leaked from the Japanese reactors. See the article here.
Another source is an article from the Health Physics Society at the University of Michigan. See their article here.
According to reports from Japanese officials, radiation readings outside the reactor site are “hardly above background.” They said that the highest dose detected briefly at the boundary of the evacuation zone was 17 millirems. The average background dose we all get from natural sources is about 360 millirems per year. One odd fact I ran into during research for this post is that bananas are radioactive enough to cause false alarms in the very sensitive detectors at ports of entry when scanning for smuggled nuclear material. Bananas are high in potassium, and potassium-40 is radioactive. One average banana will expose you to 0.01 millirem of radiation.
The political fallout is likely to last longer than the fallout of radiation.