Re: Decay-In-Storage

["ruth_weiner" <ruth_weiner@email.msn.com>]

After 10 half-lives, a radionuclide has decayed to 0.001 (0.1%) of what you
started with, which makes 10 half-lives a convenient "figure of merit" to
use.  After 20 half-lives, the amount left is 1E-6 of what you start with,
so 20 half-lives is the "figure of merit" often used for waste disposal.

Ruth Weiner, Ph. D.
ruth_weiner@msn.com
-----Original Message-----
From: William Lorenzen <LORENZEN_W@A1.TCH.Harvard.edu>
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Date: Wednesday, April 19, 2000 8:27 AM
Subject: Decay-In-Storage


>          A related question I have asked before and not had answered is
why
>          is it 10 half-lives?  Why not 8 or 12?
>
>          Does anyone know how this "standard" decay time was determined?
>
>          William A. Lorenzen
>          Children's Hospital
>          Boston, MA 02115
>
>          lorenzen_w@a1.tch.harvard.edu
>
>
>
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