Re: 1/2 kilo of Plutonium

[Steve Costigan <costigan@lanl.gov>]

 Cathy-

A rough calculation will show that a hazard equivalent to a pound of Pu
can be found from naturally occurring radioactivity in less than 3 square
miles of soil. This illustrates the argument that even through the
material present, a plausible route for exposing people must be
considered.

For the sake of simplicity, let's assume we're talking pure Pu-239 vs.
Th-232. Th-232 is naturally occurring. If one claims that one mass unit
(pound, kilogram, whatever) of Pu-239 can have some effect (such as
killing every human on earth), then it would take approximately 1E5 of
those mass units of Th-232 to have the same effect (factoring specific
activities and ALIs). Assuming that 1E5 lb Th-232 results in the same
dire outcome claimed for one lb of Pu-239, then using values in NCRP 94
for Th-232 in soil, one can show that this much Th-232 could be expected
in a plot of soil a little over 3 square miles to a depth of one
foot.   This plot of land should contain approximately 5 Ci
Th-232 or about 2E9 ALIs (enough to give two billion people the limit in
annual intake for radiological workers)! 

Keep in mind that this only considers a single radionuclide while many
other naturally occurring, so the hazard represented by naturally
occurring radionuclides in soil will be higher than this.  One could
refine this argument further but it should help illustrate the absurdity
of statements made on the gross toxicity of plutonium.

At 09:42 PM 06/05/2000 -0500, you wrote:
> This message is to thank those 
> scientists
> who responded to my enquiry regarding the
> possibility of 1/2 a kilo of plutonium giving
> everyone on the planet cancer.
>
> Your responses convinced my that the anti-nuclear
> authors I was reading are not to be trusted.
>
> I have been thinking of setting up a website
> addressing the claim, since it seem so widespread.
> I was wondering if any of you would like to contribute
> your own "view" of the claim for inclusion in the site.
> This would help educate the public and would
> be a worthwhile task, I think!
>
> One again, sorry for this intrusion of a layperson
> into your scientific domian!
>
> Cathy
>
>
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