Fw: [ RadSafe ] funniest DU scare story ever !

[Stewart Farber]

For detailed info showing graphs of the drop in dose rate from a slab of DU 
with various mass thickness [from which you can derive a decline of  about 
10 for beta dose within 1 meter in air], as part of an American Board of 
Health Physics exam question on the subject, see:

http://www.hps1.org/aahp/abhp/exams/1997/97exam-1.htm#ques5

Stewart Farber


----- Original Message ----- 
From: "Stewart Farber" <farbersa at optonline.net>
To: "John Andrews" <andrewsjp at chartertn.net>; <denison8 at wowway.com>
Cc: "RADSAFE" <radsafe at radlab.nl>
Sent: Thursday, May 25, 2006 1:28 AM
Subject: Re: [ RadSafe ] funniest DU scare story ever !


> Hello all,
>
> For authoritative information on this point, see the HPS "Ask the Experts" 
> [link and text below]  to see that the 7 mg/cm2 (dermal) dose rate at 
> CONTACT [emphasis added] with a thick [depleted] uranium slab in metal 
> form, which includes both beta and gamma contribution, is generally 
> assumed to be in the range of 200 to 230 mrad/h--depending on depletion or 
> enrichment.
>
> As distance from the slab increases, the  4 and 7 mR/hr for gamma at the 
> surface of the slab will quickly fall away to insignificant levels.
>
> Stewart Farber
> =======================
>
> http://www.hps.org/publicinformation/ate/q161.html
>
> Answer to Question #161 Submitted to "Ask the Experts"
> Category: Radiation Basics - Beta Radiation
>
> The following question was answered by an expert in the appropriate field:
>
>      Q: I'm having a very hard time finding solid information about the 
> radiation field intensities expected at the surface of a depleted uranium 
> slab. We are hoping to use such a slab to test and calibrate beta 
> detectors to establish their beta dose rate response. Such a technique is 
> often mentioned in the literature, but I find very little said about what 
> sort of beta-dose rate to expect at the surface of such a slab. Obviously 
> the exact alpha, beta, and gamma intensities will depend on the precise 
> makeup of this particular batch of depleted uranium, but it would be nice 
> to find a discussion of the general ranges expected for each as well as 
> some examples of how others perform such calibrations. The few mentions I 
> see of this range in the area of 210 to 235 mR/hr beta-dose rate at the 
> surface and somewhere between 4 and 7 mR/hr for gamma at the surface of 
> the slab. (The alpha will be unimportant since we'll have the slab covered 
> by thin (5 mil) mylar to minimize potential contamination). If someone has 
> a good reference for this, or a site URL which discusses this, I'd really 
> appreciate any information. Thanks.
>
>      A: The 7 mg/cm2 (dermal) dose rate at contact with a thick uranium 
> slab in metal form, which includes both beta and gamma contribution, is 
> generally assumed to be in the range of 200 to 230 mrad/h--depending on 
> depletion or enrichment. The value is mostly dependent on the beta 
> contribution and will therefore vary depending on additional layers of 
> absorber. The following is an excellent reference for published data on 
> natural and depleted uranium (no, I am not the author of the paper):
>
>      Preferred Reference:
>        a.. Coleman, R.L.; Hudson, C. G.; Plato, P. A. Depth-dose curves 
> for 90SR and natural and depleted uranium in mylar. Health Phys. 44(4): 
> 395-402; 1983.
>      Other References:
>        a.. Handbook of Safety Procedures for Processing Depleted Uranium, 
> Army Material Command Handbook, No. AMCHDBK-385-1.1-89, Department of the 
> Army, Washington, D.C. The relevant charts from the handbook are shown in 
> Question #5 of the 1997 ABHP Exam (the view at this Web site is in a 
> not-completely-clear format).
>
>        b.. Radiological Health Handbook, Bureau of Radiological Health, 
> Jan. 1970, Page 204. Rules of thumb for dose rates at the surface of 
> uranium materials (no supporting data).
>      Robert L. Coleman
>      Oak Ridge National Laboratory
>
> ----- Original Message ----- 
> From: "John Andrews" <andrewsjp at chartertn.net>
> To: <denison8 at wowway.com>
> Cc: "RADSAFE" <radsafe at radlab.nl>
> Sent: Thursday, May 25, 2006 12:38 AM
> Subject: Re: [ RadSafe ] funniest DU scare story ever !
>
>
>> denison8 at wowway.com wrote:
>>
>>> Anybody got a ref for the exposure rate from a kilo of DU (I'm at home 
>>> without my books).  Off the top of my head I'd guess no more than a 
>>> couple of mrem.
>>>
>>> At 20:55 -0400 5/24/06, Jaro wrote:
>>>
>>>> http://www.space.com/astronotes/astronotes.html
>>>> May 24
>>>> Florida Couple Finds Depleted Uranium in Old NASA Tool Box
>
> 



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