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RE: Dirty bomb article (Nature)
typically the main purpose or focus of such presentations is risk assessment. in general when certain routes of exposure are assessed, a range of possible assumptions regarding exposure agent related parameters are considered in that the risk assessment is attempting to determine the probability, possibility, likelihood of outcome from different possible, likely, probable exposure conditions, for example time may run the gamut but, utilized only within the region of "realistic" possibilities or expectations or within the constraints to which the model is valid.
for example 1 second exposures are only relevant when in close proximity to the source but further out they are not.
these models then generate these types of discussions to sort out the desired aspects of the assessment. so our answers are in support of the risk model with the understanding that some scenarios are of little relevance due to the technical aspects of production; however the actual risk exists if the dispersion analysis presented indicates so. then perhaps discussions would revisit 100 u sand type particles released under non-explosive scenarios. ther is more to the importance of this scenario.
-----Original Message-----
From: joe alvarez [mailto:joea@auxier.com]
Sent: Thursday, May 06, 2004 5:29 AM
To: Fritz A. Seiler; Wright, Will (DHS-PSB);
radsafe@list.Vanderbilt.Edu; Bjorn Cedervall
Subject: RE: Dirty bomb article (Nature)
Having missed the first part of the discussion and not reading the
Nature article I am at a disadvantage as to the points discussed. Since
I was involved in tests of explosive dispersal of radioactive sources I
can comment on what I have heard. Explosives are not an efficient method
for dispersing sources for maximum radiological impact. The problems:
If the radionuclides are finely ground and mixed with the explosive and
the explosive detonated well above the surface you get too much
dispersion. The Iraqis tried this and could not find the radionuclide
(Co-60) after the explosion.
If the same system is detonated on the surface the dust and debris will
quickly settle the material in essentially the blast zone. The resulting
radioactive debris can be vacuumed up or washed away.
If the source is not finely ground the blast can be configured to
shatter or vaporize the source, but the amount of explosive apparatus
necessary will again quickly settle the material in the immediate area.
Anyone who inhales enough radionuclide to create a SIGNIFICANT internal
dose will likely inhale a fatal dose of NOX from the explosion. Of
course, there is the problem of a fatal dose of shrapnel so there is no
worry of the NOX.
Can the problems be overcome? Yes, with sufficient expertise and
practice. Do terrorist have the expertise? All the information you need
is on the internet. Practice at your own risk.
Does any of this matter? Since the public already fears radiation and
there are enough articles like the one in Nature (on the say so of
Fritz) to feed that fear and misinformation, a poorly constructed dirty
bomb will be very effective. EPA will ensure astronomical cleanup cost
down to ridiculously low levels.
Joe
Joseph L. Alvarez, PhD, CHP
Auxier & Associates, Inc.
9821 Cogdill Rd., Suite 1
Knoxville, TN 37932
Ph: (865)675-3669
Fax: (865)675-3677
email: jalvarez@auxier.com
-----Original Message-----
From: Fritz A. Seiler [mailto:faseiler@nmia.com]
Sent: Wednesday, May 05, 2004 7:41 PM
To: Wright, Will (DHS-PSB); radsafe@list.Vanderbilt.Edu; Bjorn Cedervall
Cc: joe alvarez
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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