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

[Geo>K0FF]

.711 should read .72. The range is 0.7202 to 0.7198% U-235 in natural U. .

George Dowell
----- Original Message ----- 
From: "Geo>K0FF" <GEOelectronics at netscape.com>
To: "Edmond Baratta" <edmond0033 at comcast.net>; <radsafe at radlab.nl>
Sent: Monday, January 07, 2008 2:56 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"
>
> 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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