Re: Dirty bomb predictions

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

John -



Sounds like you're talking about our beloved RSI event here in Decatur, GA. Yeah, I'd have to concur that not all the Cs is gonna just "wash away" after the first rain. The Cs IS very water soluble, but anything ... and I emphasize ANYTHING ... that's the least bit porous, will wind up getting Cs contamination deeply embedded within it ... roadways, building surfaces, etc. The unfortunate thing is (as you remember) that once the Cs-contaminated water gets in the pores, and then perhaps evaporates, it's DAMN DIFFICULT to get the Cs back out.  As you might remember, we spent YEARS looking at absorption / desorbtion of cesium choride between contaminated water and stainless steel. 



Most of the environmental models that we use related to major radionuclide releases include some "guess" as to weathering half-times, but that's the best characterization of them. The Russians probably have as much experience as anyone regarding the behavior of cesium in the environment ... and trust me, 15 years after Chernobyl, it's still there.



Also, our nice clay soils here in Georgia will provide for some amount of absorption.



I have a little trouble with the cobalt scenario ... it's hard for me to see how even explosive dispersal is going to make inhalable particles out of cobalt metal. Seems to me that the cobalt scenario is a direct radiation and contamination scenario only ... not an inhalation scenario. Ingestion perhaps, but not inhalation.



Jim Hardeman, Manager

Environmental Radiation Program

Georgia Environmental Protection Division

4244 International Parkway, Suite 114

Atlanta, GA 30354

(404) 362-2675

Fax: (404) 362-2653

E-mail: Jim_Hardeman@mail.dnr.state.ga.us





>>> <AndrewsJP@AOL.COM> 3/7/2002 15:22:12 >>>

In a message dated 3/7/02 11:34:19 AM Pacific Standard Time, blc+@PITT.EDU 

writes:





> 

> 

> 

>     The cesium would be mostly washed away by the first rain, going

> down sewers. A little work with hoses along with radiation detection

> meters would be even more efficient. On soil, as in parks, it could be

> covered with dirt, but that would be a very small part of the exposure.

> 

> Bernard L. Cohen

> 



Maybe, maybe not.  The one I cleaned up after was a spill of the material to 

be placed into a sealed source.  It got blown around by the air conditioning 

and thourouly contaminated the building containing the operation.  Years 

later, when I got involved, some of the Cs-137 was deeply imbeded in the 

concrete where the grains of CsCl(?) were overlooked.  Decontamination 

required drilling or coring to remove the spots.  All in all, there was no 

risk to the occasional occupants. The material was really fixed in place. I 

guess the issue with sealed sources in dirty bombs is that the material will 

be dispersed in the existing form and not necessarily pulverized into 

breathable sized fractions.  A typical Cs-137 Hastalloy C single encapsulated 

source may even survive the explosion.  The same is true for bare cobalt 

rods.  The hype on NPR this morning started out OK, then went downhill from 

there.



John Andrews

Knoxville, Tennessee



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