[ RadSafe ] [Fwd: RE: uranium combustion produces how much UO3(g)?]

[James Salsman]

Dear Colonel Daxon,

Again, to what data do you refer?

The only data I've been able to find which can answer the question
are the enthalpies of production of uranium oxide gases in table
V.4 on page 98 of H. Wanner and I. Forest, eds. (2004) "Chemical
Thermodynamics of Uranium" (Paris: OECD and French Nuclear Energy
Agency) -- http://www.nea.fr/html/dbtdb/pubs/uranium.pdf

Ask a physical chemist to interpret those figures if you don't
understand them (I had to.)  UO3 production at the burning
temperature (>2500 K) is more likely than UO2 production, and
UO2 is already established as 25% of the solid particulate product.
There is reason to believe that nearly all U3O8(s) particulate
product is produced from UO3(g) condensation and decomposition,
and not as a direct combustion product.  The French thermodynamic
table lacks the enthalpies for direct production of U3O8, but
common sense suggests that a large, eleven atom oxide is an
unlikely combustion product in comparison to the four atom UO3.

And by the way -- I forgot to mention these three important facts:

1.  If UO3(g) cools below about 400 deg. C before it condenses,
then it will not decompose further.

2.  "Health impact assessments for depleted uranium munitions
should take into account the presence of respiratory UO3"
according to Salbu, B. et al. (2005) "Oxidation states of uranium
in depleted uranium particles from Kuwait," Journal of
Environmental Radioactivity, 78, 125–135:
   http://www.bovik.org/du/Salbu-uranyl-detected.pdf

3.  Production of UO3 as a combustion product is documented in:

Army Environmental Policy Institute (1995) "Health and
Environmental Consequences of Depleted Uranium Use in the US
Army," Champaign, Illinois, June 1995; and

U.S. Army Center for Health Promotion and Preventive Medicine
(1998) "Interim Summary, Total Uranium and Isotope Uranium
Results," Project No. 47-EM-8111-98.

Sincerely,
James Salsman

Eric D wrote:
> The data presented do not support the conclusions in your statements.  The
> data to date (even in the articles you quote) support that it is not an
> issue.  The message conveyed in your last statement is incorrect.
> 
> Eric Daxon 
> 
> -----Original Message-----
> From: James Salsman [mailto:james at bovik.org] 
> Sent: Wednesday, May 10, 2006 10:37 PM
> To: Eric D
> Cc: alexandc at Battelle.org; radsafe at radlab.nl
> Subject: Re: [ RadSafe ] [Fwd: RE: uranium combustion produces how much
> UO3(g)?]
> 
> Dear Colonel Daxon,
> 
> You say the data don't support my conclusions, but there isn't any
> data, is there?  Nobody has ever even bothered to measure the gas
> combustion products, from Gilchrist's 1970s work through to the
> present, the people charged with quantifying the health risk of
> incendiary depleted uranium munitions have never even attempted to
> measure the gas products.
> 
> Your suggestion that air is "too cool for UO3" doesn't make any
> sense.  UO3(g) doesn't decompose at any temperature; it decomposes
> only if it has a chance to condense.  The proportion remaining
> dissolved in air won't decompose until it condenses.  I am told
> by Dr. Alexander that UO3(g) is quite stable.
> 
> Won't you please support an empirical measurement of the amount of
> UO3(g) produced by uranium burning in air to settle this question
> once and for all?  There is a pressing need, because the toxicology
> and appropriate means of treating inhaled UO3(g) is very different
> than that of the solid oxide particulates.
> 
> Sincerely,
> James Salsman
> 
> Eric D wrote:
> 
>>I stand by my statements.  The points make below were made in previous
> 
> posts
> 
>>and the data do not support the previous posts or the conclusions drawn.
> 
> I
> 
>>addressed the surfaces for condensation - particulates in the air.  I have
>>also addressed the temperature issue - too cool for UO3. The discussion of
>>"uranyl-oxide" and the discussion uranium isotope ratios below are
> 
> incorrect
> 
>>and the conclusions drawn are also incorrect.
>>
>>Eric Daxon
>>
>>-----Original Message-----
>>From: James Salsman [mailto:james at bovik.org] 
>>Sent: Wednesday, May 10, 2006 1:08 AM
>>To: edaxon at satx.rr.com
>>Cc: radsafe at radlab.nl
>>Subject: [ RadSafe ] [Fwd: RE: uranium combustion produceshowmuchUO3(g)?]
>>
>>
>>
>>>... The cooling causes it to change to U3O8.  The results of the
>>>Capstone Study are consistent with this.  The statement that UO3
>>>vapor poses a significant hazard is not.
>>
>>
>>It's not the cooling per se, but the condensation which occurs as
>>it cools -- if and only if there is a surface on which to condense
>>-- and then subsequent decomposition.  See p. 213 of Wilson (1961):
>>  http://www.bovik.org/du/Wilson61.pdf
>>
>>      1/3 U3O8(s) + 1/6 O2(g) --> UO3(g) at T1
>>      UO3(g) --> 1/3 U3O8(s) + 1/6 O2(g) at T2
>>      where T2 < T1
>>
>>This is why the Capstone and earlier studies don't distinguish
>>between UO3(s) and U3O8(s) -- the former becomes the latter.
>>
>>There is always going to be some fraction of UO3(g) which doesn't
>>condense, and for open-air combustion, it's a fairly substantial
>>amount.  Cool UO3(g) is still UO3(g), until it condenses.  If it
>>happens to reach lungs before condensing, it's absorbed
>>immediately without any corresponding trace of slowly-dissolving
>>UO2(s) which accompanies the particulate dust, which disperses
>>slower and less distant before settling.
>>
>>So, inhaled uranyl oxide will not leave as much of an obvious
>>isotope ratio signature in urine as the particulate dusts, not
>>just because of the lack of persistent UO2(s), but also because
>>the uranyl ion translocates to cellular nuclei (uranyl ions
>>are used to stain DNA, to which they have an affinity) and will
>>not appear in blood or urine as much as uranium(VI) ions, such
>>as are present from natural uranium.
>>
>>Again, I'm urging everyone I can to actually measure the
>>production of UO3(g) empirically, as well as the metabolic
>>absorption in potentially exposed populations.  Absorbed uranyl
>>ought to be detectable in white blood cell nuclei years and
>>maybe even decades after exposure.
>>
>>Sincerely,
>>James Salsman
>>
> 
>