Mt St Helens and Reactor Releases

[rkathren@tricity.wsu.edu (Ron L. Kathren)]

For those interested, Soldat et al (Science213:434, July 31, 1981)
calculated doses from the Mt. St. Helens eruption and and concluded they
were insignficant when compared with natural background.  For example, the
50 committed dose equivalent to the lung was calculated as 0.2 mrem (2
microSv).  Bone dose was on the same order.

I would be very much more concerned about the release of fission products,
particularly the radioiodines and radiostrontiums, and perhaps even
plutonium,from a power reactor with an operating history, as compared with
the natural radioactivity  released in  a volcanic eruption.  One needs only
to compare the Chernobyl release with that from Mount St. Helens to get the
perspective.  Remember, an operating power reactor will accumulate
megacuries of fission products. 

Ron Kathren


   "At 10:47 AM 8/5/98 -0500, Andrew Karam wrote:
>Siting criteria not being met because of the facility being located on a
>volcano?  Seems like we need to step back and look at the big picture.
>Should that volcano erupt, wouldn't the overall environmental impact
>from the eruption itself far exceed any impact from the destroyed
>(buried?) power plant?  One might even make the same argument for a
>catastrophic earthquake in a populated area, although its impact may not
>be as global.  Maybe the major risk from siting an expensive nuclear
>power plant on a volcano is on the investors only...
>
>At the risk of delving into geology rather than health physics, not
>necessarily.  This is reaching back several years to my Volcanology class,
>but I think the basics are correct.  It would depend on the type of
>eruption and the location of the plant with respect to the eruption.  A
>Hawaiian-type eruption (lots of non-viscous lava) would probably just bury
>the plant, but a more explosive eruption could launch pretty hefty
>projectiles.  Really explosive eruptions (a la Krakatoa) could also throw
>pieces of the plant quite a distance if they happened to take place
>directly beneath the plant.  A large number of volcanic eruptions originate
>in the main crater, but a lot of them also take place in secondary craters,
>side fissures, and so forth.  So it's really hard to make any blanket
>statement about what we could expect from a volcanic eruption unless we
>know the style of the volcanic activity expected from a specific volcano,
>the location of the magma chamber and vents with respect to the power
>plant, and other, similar factors.  
>
>There are a lot of greenhouse gasses, ozone-depleting gasses, and other
>things vented during an eruption (including U, Th, Rn, and K if the lava is
>silica-rich).  The amount and type of gas emitted will vary depending on
>the type of volcano you have and the eruptive style.  In general, more
>explosive eruptions are associated with higher levels of gas dissolved in
>the lava.  A lot of the gas is steam, but you get a lot of others, too.
>Hawaiian volcanos are pretty well-behaved while Pinatubo threw ash into the
>stratosphere.  It's unique for each volcano.  In general, however, I agree
>that more people are at risk from lack of electrical power than geologic
>concerns, even in close proximity to a volcano.
>
>Andy
>
>Andrew Karam, MS, CHP				
>RSO, University of Rochester			  
>(716) 275-3781 (voice)						
>(716) 256-0365 (fax)
>akaram@safety.rochester.edu
>
>"The mind is not a vessel to be filled  but a fire to be lighted" 
> Plutarch
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