Re[2]: Caveman NORM doses

[rick_strickert@pc.radian.com]

In response to my posting:

>The long U-238 and Th-232 half-lives limit the equilibrium rates of their
>respective decay products.

Alex Zapantis queried:

> Isn't the ingrowth of daughter products a function of the daughter half
> life not the parent (for secular equilibrium)? At least the first few
> daughters of the natural series have half lives much shorter than U-238
> or Th-232 so wouldn't one expect that those would be in equilibrium with
> the parent is a very short time (geologically speaking)?

My reference to "equilibrium rates" was to the activities of the daughter
products at equilbrium.  As Alex stated, secular equilibrium would be
reached in a geologically short period of time.  Thus the disintegration
rate of each chain member at equilibrium would be essentially the same as
the disintegration rate of the parent of that chain.  The exact
relationship can be determined using the Bateman equation.

Rick


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