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FW: DU and ICRP - an activists view





> -----Original Message-----
> From:	Bradshaw, Keith 
> Sent:	Tuesday, January 16, 2001 1:28 PM
> To:	'radsafe@romulus.ehs.uiuc.edu'
> Subject:	RE: DU and ICRP - an activists view
> 
> 
> 
> -----Original Message-----
> From:	ruth_weiner [SMTP:ruth_weiner@email.msn.com]
> Sent:	Monday, January 15, 2001 9:31 PM
> To:	Multiple recipients of list
> Subject:	Re: DU and ICRP - an activists view
> 
> >Interesting and confused.  Depleted uranium (DU) is uranium that has less
> than 0.7% U-235.  THAT IS THE DEFINITION!  Uranium tailings contain U-235,
> U-238, and U-234 -- the only naturally found U isotopes (except in places
> like Oklo).  DU from recycling and reprocessing can contain U-232 and
> U-236,
> and any radiological health effect would, it seems to me, probably be from
> U-232, which has a 72 year half life.
> 
> The limited info I've got to hand puts the U-232 alpha activity at less
> than 0.1% that of U-238 in 'used' uranium.  The dose coeffs of the two
> isotopes is of a similar order.  U-236 builds up more than U-232 in
> recycled uranium, but is still a minor component.
> 
> >In any case DU is at least 98% U-238;
> natural DU is >99% U-238.  So any exposure would be mostly to U-238
> anyway.
> The Heff for U-238 for inhalation and exposure to deposition on the ground
> are five  and four orders of magnitude smaller, respectively, than for any
> other U isotopes.  Anyone inhaling enough DU to get any radiological
> effect
> would have some kind of heavy metal effect which would most likely
> overshadow the radiological effect.
> 
> Don't know about the ACTUAL effects, but from a legislative point of view,
> the ACGIH limit of 200 microgram U/m3 air would appear to translate to a
> radiation dose of 58mSv/year with insoluble DU.  So the rad limit of
> 20mSv/year beats the chemical limit for insoluble U in air.
> 
> <SNIP>
> 
> >Just my thoughts
> 
> Me too!
> 
> >Ruth Weiner
> 
> keith.bradshaw@nnc.co.uk
> 
> END


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