RE: human-human K-40 dose- Reduction due to shielding of

["Heinmiller, Bruce" <heinmillerb@aecl.ca>]

The water was a Monte Carlo expediency, but the base case is sleeping alone
on the same bed, so it's not relevant to the problem modeled.

Someone mentioned the second person acting as a shield from the natural
radiation background, which is a valid question.  The code was run to
demonstrate an upper bound and tentative average annual dose from a spouse's
K-40 alone, so this was not considered.  My feeling is that the shielding
effect is small for a typical source-target distance.  Terrestrial radiation
and that from building materials would be the thing to look at.  I would
think a crude first estimate of the dose spared could be made from, say,
taking the average annual terrestrial dose (and assume house shielding is
offset by activity in building materials, that is to say I haven't the
slightest idea), times 8/24, times an estimate of the fraction of the
relevant space eclipsed, divided by about 2 for transmission, and ignore an
add-back-in for the second person as a source of scatter.  Somebody want to
run (or correct) those numbers?

I believe shielding from cosmic rays can safely be ignored.  The muon flux
goes roughly as the square of the cosine of the angle from vertical, but
let's not go there.  Besides, most of the cosmic-ray dose is from muons with
prodigious energies, and they don't stop for anybody.

Bruce Heinmiller CHP
heinmillerb@aecl.ca

> ----------
> From: 	Zack Clayton[SMTP:zack.clayton@epa.state.oh.us]
> Reply To: 	radsafe@romulus.ehs.uiuc.edu
> Sent: 	Wednesday, December 08, 1999 1:33 PM
> To: 	Multiple recipients of list
> Subject: 	RE: human-human K-40 dose- Reduction due to shielding of
> 
> I can't help myself.  Has anyone floated an estimate of shielding by
> sleeping on a water bed?  
> 
> I don't think this would be in the FAQ. 
> 
> Zack Clayton
> Ohio EPA - DERR
> email:  zack.clayton@epa.state.oh.us
> voice:  614-644-3066
> fax:        614-460-8249
> 
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