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

Tue Apr 25 13:45:11 CDT 2006

James,

     At what temperture and pressure would you expect gaseous UO3 to condense to the solid U3O8?

  Roy Herren

James Salsman <james at bovik.org> wrote:
  Bob Wilson wrote:

>... I simply would like to see the exposure to depleted uranium
> treated like any other medical condition....

Such a situation may never occur as long as DU exposure is
assumed to involve only exposure to mostly insoluble particulate
dusts, and not uranyl oxide gas. The toxicology and
appropriate treatments are very different between the two. But
so far, the assumption has been that the risk of DU combustion
products is from the particulate oxides alone, and the gas
products have been completely ignored.

I recently sent the message below to Dr. Carl Alexander, who
has been active in uranium chemistry for more than half a
century, and is a famous scientist in other fields, participating
in the Voyager space probe program and currently working on
missile defense systems. He published a paper last year on the
vapor pressure of uranium trioxide gas in the Journal of Nuclear
Materials, vol. 346, pp. 312-318:
http://www.bovik.org/du/Alexander2005.pdf

His reply follows.

Sincerely,
James Salsman

-------- Forwarded Message --------
Subject: RE: uranium combustion produces how much UO3(g)?
Date: Thu, 20 Apr 2006 16:31:15 -0400
From: Alexander, Carl A 
To: James Salsman 

... I would expect that gaseous UO3 would be the major product of
such “burning” in air. I consulted and reviewed Wendell Wilson’s
paper prior to publication so I am familiar with it although I
haven’t seen it in a good many years. I don’t know the health hazard
of gaseous UO3 but chemically it behaves a lot like WO3 and WO3 is
certainly a bad actor. Gaseous UO3 is quite stable and you are
correct that upon condensing it would likely become U3O8.

-----Original Message-----
From: James Salsman [mailto:james at bovik.org]
Sent: Thursday, April 20, 2006 4:11 PM
To: Alexander, Carl A
Subject: uranium combustion produces how much UO3(g)?

Dear Dr. Alexander:

Thank you for publishing your paper, "Volatilization of urania
under strongly oxidizing conditions," which I recently read
with great interest. I have been trying to determine the amount
of UO3(g) produced from combustion of uranium. I have recently
been corresponding with the famous coordination chemist Prof.
Simon Cotton, who suggested that I contact you with my question.

Depleted uranium munitions such as those used for 20-30 mm and
larger antitank ordnance are incendiary due to the pyrophoric
nature of uranium. More than 30% of such bullets' uranium metal
burns in air when they are fired against hard targets. It
seems that the burning temperature should usually be above 2500
Kelvin, because the bullets are described as fragmenting into a
spray of tiny particles as they pass through armor. (Mouradian
and Baker (1963) "Burning Temperatures of Uranium and Zirconium
in Air," Nuclear Science and Engineering, vol. 15, pp. 388-394.)

Inhalation of uranium combustion fumes is suspected in major
illnesses reported in veterans and civilians of the February,
1991 Gulf War. However, none of the people responsible for
determining the health hazards has yet reported measurements of
the gas vapors produced, only the particulate aerosol fumes,
which are described as 25% UO2 and 75% U3O8 (Gilchrist R.L.,
et al. (1979) "Characterization of Airborne Uranium from Test
Firings of XM774 Ammunition," Technical report no. PNL-2944
Richland, WA: Battelle Pacific Northwest Laboratory.) Based on
the thermodynamic formation energy data I have been able to
find (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
-- see table V.4 on p. 98) it seems like production of UO3
would be much more likely than UO2 or U3O8. Moreover,
condensation and subsequent decomposition of UO3(g) can
explain the U3O8(s) product: see Wilson, W.B. (1961)
"High-Pressure High-Temperature Investigation of the
Uranium-Oxygen System," Journal of Inorganic Nuclear Chemistry,
vol. 19, pp. 212-222, at the bottom of p. 213.

If there are substantial amounts of UO3(g) produced in uranium
fires, that could explain discrepancies in both troop exposure
patterns and the solubility and resulting pharmokinetics of
those exposed. Most people have been assuming that only the
particulate aerosols present any exposure risk. But those
settle out of the atmosphere much more quickly than gas, which
is absorbed immediately if inhaled in contrast to the great
length of time which it takes for UO2 and U3O8 particles to
dissolve in the lungs. Urine tests intended to determine
exposure which measure the ratio of uranium 238 and 235
isotopes assume that only particulate aerosols and not quickly
absorbed and dissolving gas have been encountered. Those urine
tests have been negative for exposure in patients who have the
symptoms of uranyl poisoning.

Can you please help shed any light on the amount of UO3(g)
produced when uranium burns in air? Thank you.

Sincerely,
James Salsman

-------- Earlier Message --------
Subject: Re: [ RadSafe ] Sen Cantwell's Letter on Depleted Uranium Aerosols!
Date: Wed, 19 Apr 2006 12:39:11 -0700
From: James Salsman 
To: rhelbig at california.com, radsafe at radlab.nl

Roger Helbig wrote:

> I hope that some of you choose to let the good Senator know that
> DU aerosols really do not exist! At least not outside of the
> kill zone inside the tank that is hit by the projectile.

Even those who completely ignore the production of uranyl oxide
gas are careful to explain that the aerosols can and do travel
several kilometers from uranium combustion sites. E.g., see
Mitsakou et al. (2003) "Modeling the Dispersion of Depleted
Uranium Aerosol," Health Physics, vol. 84, pp. 538-544:
http://www.bovik.org/du/aerosol.pdf

Furthermore, implying that tanks are hit by "the projectile" is
disingenuous because most of the DU ammunition used has been as
20, 25, and 30 mm rounds from rapid-fire machine guns, not as
single-shot antitank ordnance.

And what about uranyl oxide gas? Does anyone still think I'm
wrong to say it gets produced in quantity? If so, please see:

Alexander, C.A. (2005) "Volatilization of urania under strongly
oxidizing conditions," Journal of Nuclear Materials, vol. 346,
pp. 312-318: http://www.bovik.org/du/Alexander2005.pdf
In particular, the vapor pressures reported in Table 6, in light
of the fact that the burning temperature usually exceeds 2500
Kelvin for the small particles involved in munitions fires.
(Mouradian and Baker (1963) "Burning Temperatures of Uranium and
Zirconium in Air," Nuclear Science and Engineering, vol. 15, pp.
388-394.)

It's clear that large quantities of UO3 gas are produced. Of
course much of it quickly condenses and decomposes to U3O8 --
so much so that UO3(g) may be the sole source of the U3O8 which
comprises 75% of the particulate combustion product. (Wilson,
W.B. (1961) "High-Pressure High-Temperature Investigation of the
Uranium-Oxygen System," Journal Inorganic Nuclear Chemistry,
vol. 19, pp. 212-222.)

But the portion of UO3 which doesn't condense disperses further
and faster than the aerosols, and are absorbed directly into the
bloodstream if inhaled, dissolving immediately to uranyl ions
which cause chromosome damage leading to immunological disorders
and congenital malformations in the children of the exposed.

Again I ask: Why have the authorities responsible for
determining the toxicological profile for uranium munition fume
inhalation never measured the gases produced; only the particulates?

Sincerely,
James Salsman

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Roy Herren

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