[ RadSafe ] Detecting DU at a distance via beta particle emission.
GEOelectronics at netscape.com
Mon Jan 7 15:47:42 CST 2008
.711 should read .72. The range is 0.7202 to 0.7198% U-235 in natural U. .
----- 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
>">I have a simple question: If U-235 is removed in the separation from
>> 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
> 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
> These used to be called Uranium I, Uranium X1, Uranium X2 and Uranium
> 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)
> 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
>>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
>> 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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