[ RadSafe ] Detecting DU at a distance via beta particle emission.

Mon Jan 7 18:17:23 CST 2008

Radsafers

This is an interesting discussion, but it helps to remember that DU is a 
byproduct of getting U-235 out of U-Nat. I think the discussion would be 
different if  it was the "prime" product.

***************
John R Johnson, PhD
CEO, IDIAS, Inc.
4535 West 9th Ave
Vancouver, B. C.
V6R 2E2, Canada
(604) 222-9840
idias at interchange.ubc.ca

----- Original Message ----- 
From: "Emer, Dudley" <EMERDF at nv.doe.gov>
To: "Geo>K0FF" <GEOelectronics at netscape.com>; "Edmond Baratta" 
<edmond0033 at comcast.net>; <radsafe at radlab.nl>
Sent: Monday, January 07, 2008 2:48 PM
Subject: RE: [ RadSafe ] Detecting DU at a distance via beta particle 
emission.

> George,
> DU typically contains:
> U-238 99.8 wt%   87% by activity
> U-235  0.2 wt%    1.1% by activity
> U-234  0.001 wt% 15.2% by activity
>
> Natural
> U-238 99.3 wt%   48.8% by activity
> U-235  0.72 wt%   2.4% by activity
> U-234  0.0057 wt% 48.8% by activity
>
> The activity contribution of U-234 to the DU is 15% of the total
> activity which is not insignificant.
>
> In your 2 lb DU cylinder you'd have 303 uCi U-238 and 56 uCi of U-234.
>
> In-growth of the U-234 in 30 years from the 303 uCi of U-238 would be
> about 25 nCi.
>
> Dudley Emer
> Geophysicist
> NATIONAL SECURITY TECHNOLOGIES, LLC
> Nevada Test Site - Mercury, Nv  M/S NTS306
> Tel:  (702) 295-7808 - Fax:  (702) 295-7761
> Pager: 7027945824 at nv.doe.gov
>
>
> -----Original Message-----
> From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
> Behalf Of Geo>K0FF
> Sent: Monday, January 07, 2008 12:56 PM
> To: Edmond Baratta; radsafe at radlab.nl
> Subject: Re: [ RadSafe ] Detecting DU at a distance via beta particle
> emission.
>
> ">I have a simple question:  If U-235 is removed in the separation from
> U-238,
>> why isn't U-234 removed at the same time???
>>
>> Ed Baratta"
>
> Not all the U-235 is removed, only down to 0.2-0.3%. Sometimes only down
> to
> 0.4% from 0.711 %. ANY reduction
> from the natural ratio of U-238/U-235 qualifies the end product to be
> called
> DU. Probably not all the U-234 is removed either, but the U-234 comes
> back
> (decay daughter), the U-235 never does . Someone else will have to
> comment
> on the U-234 levels initially left in DU metal, if any, I don't know.
>
> Every atom of Pa-234m that decays, turns into U-234. Because of the
> great
> disparity between the two half-lives, 1.2 minutes vs. 240,000 years, the
>
> contribution of U-234 to the radiation from DU is minimal.
>
> Bottom line, if you have U-238, you will son have Th-234, Pa-234m and
> U-234.
>
> These used to be called Uranium I, Uranium  X1, Uranium X2 and Uranium
> II.(Glasstone)
>
> Yes there are X-ray produced by the beta particles due Bremsstrahlung
> that
> can be detected using low energy gamma scintillator probes. That is
> another
> subject and I would like to hear from someone who has used this method
> in
> practice.
> Alpha spectroscopy is the main method for detecting small amounts of DU,
> but
> that is not at a distance, therefore yet another (and interesting)
> subject.
>
>
> Same deal with Radium. Assuming a 100% efficient refinement, all the
> lower
> daughters will again reach equilibrium in a period of time.
> It is inevitable in a decay chain where the parent has a long half-life
> compared to the daughters.
>
> DU will never reach equilibrium in human time scale because U-238 has a
> long
> half-life yes, but the daughter U0234 and Th-230 also have long half
> lives,
> so the refinement will only result in partial equilibrium.
>
> My interest in DU is only scientific, not political. I am not
> anti-radiation
> in any way.
>
> George Dowell
> GEOelectronics at netscape.com
>
>
> ----- Original Message ----- 
> From: "Edmond Baratta" <edmond0033 at comcast.net>
> To: "Geo>K0FF" <GEOelectronics at netscape.com>; <radsafe at radlab.nl>
> Sent: Monday, January 07, 2008 2:11 PM
> Subject: Re: [ RadSafe ] Detecting DU at a distance via beta particle
> emission.
>
>
>>I have a simple question:  If U-235 is removed in the separation from
>>U-238, why isn't U-234 removed at the same time???
>>
>> Ed Baratta
>>
>> edmond0033 at comcast.net
>> ----- Original Message ----- 
>> From: "Geo>K0FF" <GEOelectronics at netscape.com>
>> To: <radsafe at radlab.nl>
>> Sent: Monday, January 07, 2008 1:06 PM
>> Subject: [ RadSafe ] Detecting DU at a distance via beta particle
>> emission.
>>
>>
>>
>> Detecting DU at a distance via beta particle emission.
>>
>>
>> DU (Depleted Uranium) is uranium with the majority of the U-235
> removed,
>> leaving behind U-238 and U-234.
>> I prefer to think of DU as refined U-238. The metal has many
> industrial
>> and scientific uses, mainly because of its high density, being 1.7
> times
>> as dense as lead. A few common uses would be counterweights and
> radiation
>> shielding. DU is used in projectiles because of its unique density,
>> pyrophoricity and "self-sharpening" characteristics.
>>
>> The only progeny present that can be detected at a distance would be
>> Pa-234m, a beta emitter.
>> With a maximum energy of  2.28 MeV, the betas would travel
> approximately
>> 20-25 feet in air, using the rule of thumb of 10-12 feet per MeV.
>> A sensor would have to be appreciably closer than the maximum distance
> to
>> detect the beta particles.
>>
>> Because of self-shielding, DU metal's surface beta rate is in ratio of
> the
>> surface size, not the thickness or
>> volume of the sample. In other words a thin sheet would have the same
> beta
>> surface emission rate as a thick sheet.
>> Indeed, DU Slabs are used in the lab to calibrate probes.
>>
>> The best "calculations" are done in the lab with a DU slab and a
> detector!
>> Using a 2 pound cylinder of DU metal and
>> a pancake probe, about 6 feet is as far as you can get and still
> obtain
>> usable (statistically significant) readings. Any closer and the
> readings
>> ramp up quickly. With a 100 Cm^2 alpha-beta scintillator on a Thermo
>> ELECTRA alpha-beta meter, the range is extended to about 10 to 12
> feet.
>>
>> George Dowell
>> GEOelectronics at netscape.com
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>
>
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