[ RadSafe ] query

Jaro jaro-10kbq at sympatico.ca
Fri Mar 6 13:47:34 CST 2009

Yes, the Canadian Defence Research Establishment Ottawa did a study back in
2002, which included a "Case Scenario : Radiological Dispersal Weapon in
Downtown Montreal"

Scenario - RDW
• radioisotope of choice Am-241 (T 1/2 458 years)
– activity 3700 GBq (100 Ci, 30 g)
– this amount is transparent to conventional security surveillance
– produced in MCi/yr
– 100 Ci = 10 oil well logging sources (Am/Be)

• domestic terrorist group
• Am-241/Be (stolen)
• conventional explosive
• prevailing winds westerly, 30 km/h

• peak rush hour AM, traffic tied up
• car bomb near Peel and Sherbrooke
• reports of multiple blast injuries
• 10 cars and 4 buildings on fire
• radiological weapon is claimed, but
conventional gamma detectors indicate nothing

Post-event Summary
• Reality
– deaths due to blast 20
– injuries due to blast 500
– 50% mortality due to burns 100
– immediate deaths due to radiation 0
• heavy metal toxicity irrelevant
– deaths due to combined effects 200
– predicted excess cancers ~ 100
• Public perception
– “exposed” people ~ 300,000
– immediate costs ?? M $
– radiophobia ?? M $

• RDW is easy to build
• Radioactive material is accessible in sufficient quantities to make a
dangerous RDW
• Large areas could be contaminated
• Large number of people “exposed”
• Clean-up costs could be enormous


I have a copy of the presentations, but there doesn't seem to be anything
posted on the Defence Research and Development Canada web site:

The report made a great big splash in local media back in June 2002 -- with
full color graphics of radioisotope dispertion isopleths right across the
front page.
It was media scaremongering at its loudest.
At the time, I sent a letter to the paper in response (see below).


From: Franta, Jaroslav
Sent: Thursday, June 13, 2002 10:03 AM
To: 'Editor of The Gazette'
Subject: RE: "Is Montreal ready to handle a dirty-bomb attack ?"

To the Editor,

While I was pleased to learn that DND is conducting training courses for
emergency workers in Montreal ("Is Montreal ready to handle a dirty-bomb
attack ?" 12 June 2002), I am amazed that such a story can make front-page
news with fancy color graphics etc.

Although it is true that "many radioactive materials are stored in
non-secure facilities," it is completely misleading to go on from there to
imply that these common types of radiation sources can cause the kind of
devastation claimed in the article.

Its like saying that "many explosive materials are stored in non-secure
facilities," therefore terrorists can wipe out a couple of downtown blocks
with a 100-tonne bomb.

If you don't believe me, think of the sodium azide in your car's air bag,
definitely a "non-secure facility": Just because everyone has a gram of the
stuff in their garage, that can hardly be interpreted to mean that its
trivial to get 100 tons of it and blow up downtown Montreal.

This absurdity is only more true of radiation sources. We all have a few
kilobecquerels of naturally-occurring radioactive potassium-40 and carbon-14
in our bodies (another "non-secure facility"). But that doesn't make it easy
to obtain radioactive sources comprising many terabecquerels - that's
billions of times more - the kind of quantity which might pose a
radiological threat when dispersed over a not-too-large area. (Those
particularly at risk in such an event would be people immobilized in that
area by the initial explosion and emergency workers trying to dig survivors
out of the rubble left by the explosion).

I suspect that somewhat more sophistication would be required than the
knives and forks used by the 9-11 highjackers. Those of us working in the
nuclear business know for a fact that when not shielded, radioactive sources
are at their most hazardous when they are concentrated in one spot. Any
dispersal or dilution weakens them just as it does any other poison or drug.
Of course its easier to keep them safely shielded when they are contained in
one spot rather than spread around.

In fact, multi-terabecquerel gamma radiation sources require large, heavy
shielding containers - often weighing a tonne or more - which make handling,
transport and weaponization (i.e. pulverization of the radioactive metal or
ceramic) extremely difficult.

Handling it without the shielding would be lethal within hours, but simply
attaching explosives to the side of the shielding vessel or even the source
itself would do little more than launch it on a random trajectory. The
result would be one or more dangerous "hot spots" somewhere in the vicinity,
but no general area contamination in and around the city, as depicted in the
Gazette graphics.

Moreover, such powerful radiation sources are - contrary to the quoted
Greenpeace claims - fairly rare. They are typically part of large, fixed
industrial or medical irradiation facilities. They are NOT the "every day
shipment" radiopharmaceutical variety used in diagnostic and treatment
procedures of every hospital's nuclear medicine department.

This latter, while hazardous when concentrated in their flask and
unshielded, would likely not even require site decontamination if dispersed
over a few blocks. After all, patients who receive such radiopharmaceuticals
eventually urinate them into the same sewer system as everyone else. Rain
would tend to have a similar cleansing effect on outdoor contamination.
These radioactive materials are short-lived isotopes, which loose their
radioactivity within days or less - that's why they need to be shipped
around by suppliers all the time – in contrast to the large fixed gamma
radiation sources, which typically last for years. Radiopharmaceuticals tend
not to be strong gamma sources, but rather beta radiation sources, which are
of little concern unless ingested or left unwashed on one's skin.

Nor is it as though we had no knowledge of what the consequences of
radioactive contamination with large sources can be.

The 1987 radiation incident in Goiania, Brazil, is particularly relevant to
this issue. In this case, some scavengers got hold of a large Cesium-137
source [ 1375 Ci = 51 TBq ]  from a medical facility, an abandoned medical
clinic. They carted the heavy shielded container home, and after a few days
succeeded in opening it partially using various power tools. Later they
spread small amounts of the Cesium-137 on their bodies and distributed it to
their family and friends because it looked interesting (it glowed a pretty
blue color in the dark). A total of about 250 people were exposed to it, but
of those people, only four actually died from radiation exposure. Close to a
quarter million people demanded the government test them to make sure that
they weren’t contaminated. Its public fear that is the worst enemy.

This was an extreme example, which subsequently led to increased regulation
and security measures around the world. Details of it appeared in the
January 1991 special issue of Health Physics journal, a 100-plus page (solid
text) volume subtitled "The Goiania Radiation Accident."

As the specialist physicians of the Instituo de Radioprotecao e Dosimetria
of Brazil explained, "participation of the doctors of the city of Goiania
and the Hospital's medical staff itself... was greatly reduced due to fear
or misinformation... instead of helping us by explaining exactly what was
happening, and printing integral interviews with scientists working on the
project... irresponsible yellow journalism stirred fear in the population
...hysteria instigated by the media was very expensive for the government
and extremely painful to those involved... the victims of Cesium 137 were
rejected by an entire city and its population... as much discriminated
against by society (as are) AIDS patients."

How many times have reporters gotten burned trying to get technical
information from bogus sources like Greenpeace ? Yet they keep doing it !
How about debunking this nonsense in another front-page article ? Not
likely, huh ?

Jaro Franta, P.Eng.


-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl]On
Behalf Of Bernard L. Cohen
Sent: Friday, March 06, 2009 2:25 PM
To: RadiatSafety
Subject: [ RadSafe ] query

Does anyone know of studies to estimate how widely the radioactivity
would be spread if a dirty bomb were detonated in a large city?

Bernard L. Cohen
Physics Dept., University of Pittsburgh
Pittsburgh, PA 15260
Tel: (412)624-9245  Fax: (412)624-9163
e-mail: blc at pitt.edu  web site: http://www.phyast.pitt.edu/~blc

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