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Re: Dirty bomb article (Nature)
jjcohen wrote:
> Fritz et al,
> This technique is an old ploy used by anti's and fundseekers to
>stimulate concern over nuclear power. It simply assumes that ,in a nuclear
>accident, radioactivity will be released with an aerosol dispersal
>efficiency so high that it would be unattainable even if it we tried
>engineer its occurance.
> I believe the approach was first used in the 1960's when BNL produced
>the WASH-740 report on nuclear accidents. They were uncertain as to what the
>"source term", or fractional release of radionuclides would be in case of a
>reactor accident. They knew it had to be greater than 0% and less than 100%,
>so they compromised and assumed 50%. (Isn't science wonderful). Perhaps for
>the more volitile nuclides, this assumption wasn't so bad, but for the
>transuranics and most fission product it was a gross overestimate. Anyway,
>using this source term estimate and detailed meteorological calculations
>they estimated several thousands of deaths would result. Despite the
>Rasmussen Study, TMI, and Chernobyl , many people still believe this would
>be the case.
> Jerry
>
>
>
>
> ----- Original Message -----
> From: Fritz A. Seiler <faseiler@NMIA.COM>
> To: Wright, Will (DHS-PSB) <WWright2@DHS.CA.GOV>;
><radsafe@list.vanderbilt.edu>; Bjorn Cedervall <bcradsafers@HOTMAIL.COM>
> Cc: Joseph L. Alvarez <jalvarez@auxier.com>
> Sent: Wednesday, May 05, 2004 7:40 PM
> Subject: RE: Dirty bomb article (Nature)
>
>
> > Hi All,
> >
> > Having spent 10 years in an aerosol science environment at the
> > old Lovelace ITRI, I am aware of all your points. However, that is
> > not the main aim of my comment. My main point of attack was the fact
> > that the physicists quoted did not take the basic facts of aerosol
> > science into account and their support sounds to me like a knee jerk
> > reaction. There was no indication that they were aware of any points
> > in your answer.
> > Your answer sounds a little bit like an agreement with the trend
> > of the article but the fact is that we don't know anything about the
> > aerosols involved. Being honest, we therefore have to say that we just
> > don't know how dangerous the aerosolized portion of a dirty bomb would
> > be.
> >
> > Best
> >
> > Fritz
> >
> > *****************************************************
> > Fritz A. Seiler, Ph.D.
> > Sigma Five Consulting: Private:
> > P.O. Box 1709 P.O. Box 437
> > Los Lunas, NM 87031 Tome', NM 87060
> > Tel.: 505-866-5193 Tel. 505-866-6976
> > Fax: 505-866-5197 USA
> > *****************************************************
> >
> >
> >
> > -----Original Message-----
> > From: owner-radsafe@list.Vanderbilt.Edu
> > [mailto:owner-radsafe@list.Vanderbilt.Edu]On Behalf Of Wright, Will
> > (DHS-PSB)
> > Sent: Wednesday, May 05, 2004 4:55 PM
> > To: Fritz A. Seiler; radsafe@list.Vanderbilt.Edu; Bjorn Cedervall
> > Cc: Joseph L. Alvarez
> > Subject: RE: Dirty bomb article (Nature)
> >
> >
> > you are correct regarding the behavior of the particle at 100(some
>pollen)
> > which by definition is not an aerosol as well as the 10 u which is an
> > aerosol. however, they are both readily inhalable and 10 remains perhaps
> > suspended for some time, but they differ in that the 100 is easily
>removed
> > through clearance mechanisms because they get no further than the throat
>or
> > nasal passage but 10 gets deeper and many remain in lower respiratory
>tract.
> >
> > the 100 is readily swallowed.
> > these particles may not be as dense as sand and thus demonstrate
>different
> > aerodynamic behavors due to nonspherical shape. from a risk assessment
>point
> > of view this size particle is a problem especially under the
>circumstances
> > under discussion.
> >
> > -----Original Message-----
> > From: Fritz A. Seiler [mailto:faseiler@NMIA.COM]
> > Sent: Wednesday, May 05, 2004 3:25 PM
> > To: radsafe@list.vanderbilt.edu; Bjorn Cedervall
> > Cc: Joseph L. Alvarez
> > Subject: RE: Dirty bomb article (Nature)
> >
> >
> > Hi All,
> >
> > Here again is a beautiful example of knowing just enough to be
> > dangerous! In my career as a nuclear physicist I did not come
> > into real contact with aerosol science until I leaned about it
> > as an NBC(Nuclear, Biological, and Chemical warfare) officer in
> > the Swiss Army. Due to its 'National Guard' nature, we had all
> > kinds of scientists in the NBC defense service. I doubt very
> > much that the physicists cited in Nature were aware just how
> > difficult it is to make an inhalable aerosol even in a powerful
> > chemical explosion. In the Goiana incident we obviously had to
> > deal with a ready made powder with an unknown spectrum of particle
> > sizes, and the dirty bomb would produce an equally unkown spectrum.
> > The two cases can, therefore, not be used to evaluate each other's
> > consequences. Remember, a particle of about 100 micrometers or more
> > is a fine grain of sand that has a tendency to fall right past your
> > face without negotiating the turn needed to enter your mouth or nose.
> > The best size for inhalation lies at aerodynamic diameters below 10
> > micrometers or so. In the book Joe Alvarez and I are writing, we
> > present the reader with a dirty bomb problem that hinges on his
> > ability to aerosolize a monelclad RaBe source by a shaped explosion.
> > You can have quite a bit of fun with that! What you need essentially
> > is the knowledge of an explosive specialist and those do not grow on
> > trees.
> >
> > Funny how little expertise you need to scare many people!
> >
> > Best
> >
> > Fritz
> >
> > *****************************************************
> > Fritz A. Seiler, Ph.D.
> > Sigma Five Consulting: Private:
> > P.O. Box 1709 P.O. Box 437
> > Los Lunas, NM 87031 Tome', NM 87060
> > Tel.: 505-866-5193 Tel. 505-866-6976
> > Fax: 505-866-5197 USA
> > *****************************************************
> >
> > -----Original Message-----
> > From: owner-radsafe@list.Vanderbilt.Edu
> > [mailto:owner-radsafe@list.Vanderbilt.Edu]On Behalf Of Bjorn Cedervall
> > Sent: Wednesday, May 05, 2004 2:51 PM
> > To: radsafe@list.Vanderbilt.Edu
> > Subject: Dirty bomb article (Nature)
> >
> >
> > http://www.nature.com/nsu/040503/040503-3.html
> >
> > FYI & best regards,
> >
> > Bjorn Cedervall bcradsafers@hotmail.com
> >
> > ************************************************************************
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>
Many years ago when we were designing our fuel fabrication facility one
of our groups tasks was to test respirators for protection factors from
uranium. We built a chamber with a robotic manequin on which to place
the respirator or hood. We manufactured 10 micron uranium dust to use
as a test aerosol. Yes, really 10 microns. Our testing device failed.
We could not keep 10 micron uranium airborne. It fell to the floor of
the chamber, no matter what we did. It is really hard to keep heavy
materials airborne. I had a similar experience with Ir-192.
John Andrews, Knoxville, Tennessee
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