Good topic - damn little, if any, research.
What IS the magnitude of radioactivity release into the Environment from Vulcanism ? If this is a topic of serious scientific enquiry ... have yet to find them through (admittedly not exhaustive) searches.
My gut says that the amount of 'natural radioactive pollution and isotope release' will dwarf anything that comes from Fukushima by several (hundreds imo) magnitudes. (A 'magnitude' is logarithmic - each one is a 10x - when using the decimal scale ... )
ALL VULCANISM IS CAUSED BY RADIOACTIVITY. period.
All magma contains SIGNIFICANT amounts of radioactivity - THAT IS WHY IT IS MOLTEN IN THE FIRST PLACE. So, the next time someone talks about 'the china syndrome' - At least try to keep a straight face when realizing that 'core meltdowns - with molten material going through solid rock' ... have been occurring NATURALLY for hundreds, thousands, millions, billions of years. Man has 'invented' nothing new here.
Here is an 'interesting take' on Uranium Mining - and how it can REDUCE, long term, the 'deaths from radiation' ....
By far the most important aspect of radon from uranium mining is yet to be discussed.2 When uranium is mined out of the ground to make nuclear fuel, it is no longer there as a source of radon emission. This is a point which has not been recognized until recently because the radon that percolates out of the ground originates largely within 1 meter of the surface; anything coming from much farther down will decay away before reaching the surface. Since the great majority of uranium mined comes from depths well below 1 meter, the radon emanating from it was always viewed as harmless. The fallacy of this reasoning is that it ignores erosion. As the ground erodes away at a rate of 1 meter every 22,000 years, any uranium in it will eventually approach the surface, spending its 22,000 years in the top meter, where it will presumably do great damage. The magnitude of this damage is calculated in the Chapter 12 Appendix, where it is shown that mining uranium to fuel one large nuclear power plant for one year will eventually save 420 lives! This completely overshadows all other health impacts of the nuclear industry, making it one of the greatest lifesaving enterprises of all time if one adopts a very long-term viewpoint.
http://www.phyast.pitt.edu/~blc/book/chapter12.html
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