Uranium colors

[mcnaught@lanl.gov (Mike McNaughton)]

I am editing a uranium safety course for use throughout the DOE complex,
and I have a question about colors.  The course that I inherited contained
the following statement about yellowcake.

"The final color [of yellowcake] can actually range from yellow to orange
to black depending on the chemicals used and the drying temperature. The
final color is important when determining biological effects if uranium in
this form is taken into the body, as the darker color indicates that the
material will have a lower solubility, meaning the uranium will stay in our
body longer.  A lighter color indicates that the material has a higher
solubility meaning the uranium is more quickly removed by normal body
functions."

Is it really possible to make such a broad generalization about color and
solubility?  Is this paragraph helpful?  Does anyone know where this
information comes from?

There are many other threads that could be pulled from this quote, eg
obviously low solubility implies low absorption rate as well as low
clearance rate, so it depends if the intake is inhalation or ingestion.
Also, the color of materials containing uranium is extremely complicated,
depending on many things, including impurities, the particle size, and the
oxidation state or states.

Thanks to several RadSafers who made comments on the draft DOE uranium
safety course.  If  anyone else would like to see a copy of the draft
course, please reply to me directly.

"Shlala gashle" (Zulu greeting, meaning "Stay safe")
mike (mcnaught@LANL.GOV)