RE: thorium abundance? -Reply

[melissa (M. Woo)]

> Care to provide the further details so we can have some fun? i.e is
> it in the ground (if so the concentrations of the thorium and uranium
> are needed), is it a lantern mantle (if so, the time was produced is
> needed e.g. 1, 5, 10 years ago)?  etc

Well...

This is really more of a hypothetical exercise than anything else, as we
only have verbal statements from people who are relaying second- or
third-hand information on research that was conducted in the 1930's or so.
Heck, I'll bet that other universities might be facing a similar problem,
so maybe this will be of use to others.

One emeritus professor indicated that he remembered being told of
experiments being performed with "rare earths" back in the 30's and 40's.
At that time, the only sources available for the separation and study of
rare earths were uranium and thorium.  The professor thinks that the
techniques used for separation were fractional distillation and fractional
crystallation.   He doesn't really know if the material was in the form of
ores or whatever.

However, we sent a sample of unknown material from the former research site
in question to a lab which does a lot of analysis of NORM, and the results
don't show elevated levels of thorium (which is why I am saying that all
this stuff with the thorium is probably a hypothetical exercise, but I
figured I'd be rigorous about things), but do show uranium in
naturally-occurring amounts (isotopic ratios).

So, I looked at the thorium isotopes resulting from the uranium decay scheme,
but couldn't find the natural isotopic abundances for thorium itself,
leading to my question.

That's about as much of the story as I can probably relate in this forum. :-)
Other universities might want to look out for stashes of NORM -- you never
know where or when they'll pop up!

I definitely appreciate all of the help that radsafers have been able to
provide on this!  THANKS!!!

Melissa

-- 
Melissa Woo                       | University of Illinois at Urbana-Champaign
Health Physicist                  | Environmental Health & Safety Bldg., MC225
office phone: 1.217.244.7233      | 101 S. Gregory St., Urbana, IL  61801
m-woo@uiuc.edu                    | http://www.cso.uiuc.edu/ph/www/m-woo