The fact that the only serious accident that anti-nuclear campaigners can point to happened 25 years ago in a primitively designed reactor, incompetently run, in a highly secretive and dysfunctional state demonstrates that nuclear is far less dangerous than is widely believed – as does the fact that the fairly elderly reactors at Fukushima survived a massive earthquake and tsunami largely intact.
To place the radiation levels in context, today’s Wall Street Journal reports (pg A13) that the World Health Organization “reports [radiation] levels range between 0.0149 and 0.0235 millisieverts per hour [mSv/hr].” From the chart (click to show full size), taking the high end of the WHO numbers and the low end for average normal annual exposure, and one would need to spend over five days at the Fukushima site to equal what we all receive simply for being here on Planet Earth. Let me repeat that: at the Fukushima site.
Radiation levels fall off, generally proportional to the inverse square of the distance from the source. Could airborne radiation reach our shores? Certainly possible. Two factors mitigate against this. The most important is that any source from Fukushima would be dispersed in the atmosphere by winds. Also, a significant amount of the source, if they are from the reactors and not the spent fuel, will have relatively short half-lives, and hence be naturally diluted by the time any of it reaches a distance of 5,000 miles from the source.
Should residents of our West Coast be worried? Not about Fukushima. Worry about side effects from taking potassium iodide.