[ RadSafe ] [Fwd: RE: uranium combustion produceshowmuchUO3(g)?]

[James Salsman]

>... 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