RE: Dirty Bomb

["Jim Hardeman" <Jim_Hardeman@MAIL.DNR.STATE.GA.US>]

Mark —



We've been trying to get that message across now for some 20 years or more. The Conference of Radiation Control Program Directors, Inc. (CRCPD - the professional organization for state, tribal and local radiation protection professionals) distributed a video tape several years back with EXACTLY that same message ... a tape designed for use by local police, fire and emergency medical personnel. The main message ... no emergency responder (at least, in this country) has been harmed by responding to a radiological incident ... the patients are not harmful to response personnel and (unless other hazards are present) conditions do not warrant the use of anything but minimal protective clothing ... gloves,  etc. ... the same sorts of things you as a medical responder would do to protect yourself from the blood and other bodily fluids of the victim(s). I don't know how widely that video was distributed.



Will contamination control be a problem? You bet it will. Is it possible that buildings and lands might be interdicted for a while? Certainly ... it's pretty likely, as a matter of fact. Is the public going to be scared ****less? Of course ... just get Jose Rozental to describe the public reaction in Goiania, Brazil during the response to and recovery from the cesium source incident there.



Bottom line — emergency responders (including medical) should be prepared to deal with a LOT of hysterical, potentially contaminated people ... none of whom are likely to have inhaled or ngested enough radioactive material to be of any short-term or long-term detriment, or to have been exposed to high-enough direct radiation levels to exhibit any symptoms. These people may, however, exhibit symptoms common to stress (which in some cases, could mimic the symptoms of early-state radiation sickness).



As always, my $0.02 worth ...



Jim Hardeman

Jim_Hardeman@mail.dnr.state.ga.us 



>>> Sonter Mark <sonterm@EPA.NSW.GOV.AU> 5/14/2002 19:14:18 >>>

Hi All,



Reality Check - "dirty bombs"



Comments continue to circulate about the possibility for terrorists to

explode a 'dirty bomb' or a radiological bomb'.  Indeed, even Warren

Buffett, the 'Sage of Omaha' has the other day been reported as saying that

a radiological attack is not a question of 'if', but of 'when'.



There is however very little written about just what the possible health

impact of such an action might be.



It is not difficult to make some very general estimates of what the

radiation consequences might be, and the findings that I here present

indicate that the health effects would probably be very small, although the

disruption and the cleanup task might be a serious cost.



Let us assume that a stolen source wrapped with explosives has been

detonated in a large office block or shopping mall.  There would certainly

be serious damage from the explosive, and injuries resulting from flying

debris, building collapse and so forth.



But I thought I might try to estimate potential radiation doses and hence

health risks from such a release... 



So, here's a little calculation of possible doses to emergency responders or

to members of the public who might remain trapped in the building:





Example 1.



Assume a stolen Cs-137 source of Activity 100 millicuries (= 3.7 GBq).



Assume it is exploded and all the caesium disperses into a building of

volume 500,000 cubic metres as a fine respirable powder.



This implies an in-air concentration of about 8000 Bq/m3.



IAEA BSS  (Safety Series 115) Tables II-III and II-VII indicate dose per

unit activity by inhalation for Cs-137 is in the order of 5 * 10-9 Sv/Bq.



So a person breathing the contaminated air for 1 hour without respiratory

protection will incur about  (1 m3 * 8000 * 5 * 10-9 ) Sv or 40

microsieverts.  



This amount is essentially trivial in this context.





Example 2.

Assume that an Iridium-192 source of Activity 1 Terabecquerel (approx 30

Curies) is dispersed in the same building.

The airborne activity concentration will then be 2 * 106 Bq/m3 and the total

activity breathed in in one hour will be approx 2 * 106 Bq.

This will incur (using data from IAEA BSS as above) a dose of   (2 * 106 * 5

* 10-9) = 10 mSv,  which is about equivalent to a 'CAT scan'.  In other

words, not that much.

Please note that in actual fact, it will be quite difficult to get all of

the radioactive material into the air in respirable form: it will want to

plate out on its surroundings.  So the above calculations are almost

certainly unduly pessimistic, and exaggerating the actual doses that would

be incurred.

So we can say that any injuries or deaths will be from the explosive blast,

mechanical injury, or any resulting fire, or from the panic, eg in hasty and

ill-disciplined (not to mention ill-advised) evacuation traffic accidents)

rather than from the radiation dose.



Responding emergency agencies should be informed beforehand, i.e., NOW, that

dose control requirements are thus NOT an overriding issue, but rather the

control of panic.  Responders should be reassured, NOW, that 'moonsuits are

not required', but rather, that first aid and fire control are the essential

requirements.



Mark Sonter 





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