Re: Simple little total activity question...

[rkathren@tricity.wsu.edu (Ron L. Kathren)]

There is an obsolete unit -- the special curie for uranium --that was
defined in 1959 in the old NBS Handbook 69.  This unit was used as a basis
for internal dosimetry; it was defined as 3.7 x 10E10 dps from U-238 plus an
identical amount from U-234, plus 9 x 10E8 dps from U-235.  Please note that
it is a practical impossibility for uranium to exist in equilibrium with all
of its daughters, and also to obtain 100% pure U-238.  However,
theoretically in the example you give, decay kinetics would dictate (by
definition) that there would be 1 Bq of activity from each radioactive
daughter of U-238.

Ron Kathren
Director, US Transuranium andUranium Registries

  At 03:00 PM 6/19/98 -0500, Clement, Christopher wrote:
>Radsafers:
>
>This one has been bugging me for a while.
>
>Say you have a sample which contains 1 Bq of U-238, plus all of it's
>progeny in equilibrium, and no other radionuclides.  What is the total
>activity of the sample?  Is it 14 Bq or 15 Bq?  I'm not really clear on
>whether or not one should count Pa-234m and Pa-234 separately or as one.
>
>------------------------------------------------------------
>Christopher H. Clement
>Scientific Specialist / Radiation Protection Program Manager
>Low-Level Radioactive Waste Management Office
>Atomic Energy of Canada Limited
>clementc@aecl.ca
>
>