[ RadSafe ] Salsman's uranium trioxide gas proof

[James Salsman]

Dear Dr. Raabe,

I read your 1978 Health Physics article on plutonium (cited in full
below) carefully and with great interest.

I note that you measured condensation in a very small enclosed space.
How would you compare the condensation rate of metal oxide vapors in
such a space with the rate in open air?

I was unable to find any mention that you had matched the mass of the
plutonium in the recovered combustion product with the mass consumed
by the combustion.  Did you or your colleagues make that comparison?

I note that you, like others from Jofu Mishima through Maryanne
Parkhurst, have used mass impactors to collect particulate combustion
product.  Isn't it true that mass impactors force excess condensation,
and allow gases to escape collection?

Would your apparatus have been able to detect any plutonium oxide gas?  How?

Sincerely,
James Salsman

On 1/24/07, Otto Raabe <ograabe at ucdavis.edu> wrote:
>
>  At 12:59 PM 1/24/2007, you wrote:
>
> Are you suggesting that as a gas diffuses and cools below the point at
>  which it is volatile, more than half of it will condense
>  "instantaneously?" That is absurd.
> *******************************************
>  When the oxide molecule forms by "burning" liquified plutonium or uranium
> it has different chemical and physical characteristics that the pure metal.
> Cooling is virtually instantaneous even near the combustion process and
> results in all (not half) of the vapor being converted to solid oxide
> particles. These particles rapidly coalesce into chain aggregates as shown
> in the micrographs in the paper by Carter and Stewart or my own studies
> referenced below. This is virtually an instantaneous process since the
> melting and vaporization temperatures of the oxides are much higher than
> those of the pure metals. Hence, the "vapor" form of the oxides only exists
> momentarily, if at all,and only if the reaction is hot enough to reach the
> oxide melting point.
>
>  I have conducted these types of experiments and characterized the particles
> produced by laser vaporization of plutonium. The vapor oxidation and
> particle formation is virtually instantaneous. The vapor phase exists only
> in the superheated zone. [Raabe, O.G., S.V. Teague, N.L. Richardson and L.S.
> Nelson. Aerodynamic and dissolution behavior of fume aerosols produced
> during the combustion of laser-ignited plutonium droplets in air. Health
> Physics 35: 663-674 1978.].
>
>  Otto
>
>
>
>
>  **********************************************
>  Prof. Otto G. Raabe, Ph.D., CHP
>  Center for Health & the Environment
>  University of California
>  One Shields Avenue
>  Davis, CA 95616
>  E-Mail: ograabe at ucdavis.edu
>  Phone: (530) 752-7754   FAX: (530) 758-6140
>  ***********************************************