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Re[2]: Sealed sources
- To: radsafe@romulus.ehs.uiuc.edu (IPM Return requested) (Receipt notification requested), antatnsu@pacbell.net (IPM Return requested) (Receipt notification requested)
- Subject: Re[2]: Sealed sources
- From: Ruth Weiner <rfweine@sandia.gov>
- Date: 10 Dec 1997 08:17:05 -0700
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After 10 half-lives, a source has decayed,to 0.001 of the original
activity. After 20 half-lives, the dacay is to 1E-6 of the original
activity. So it depends on the initial activity.
Ruth Weiner
Sandia National Labs
Usual disclaimers.
______________________________ Reply Separator _________________________________
Subject: Re: Sealed sources
Author: antatnsu@pacbell.net at hubsmtp
Date: 12/9/97 6:24 PM
Stacey Alderson wrote:
>
> Radsafers,
>
> At what time does a short lived sealed source cease being
> radioactive material. Especially if the source has documenation
> identifying it as radioactive material and it was allowed to decay in
> storage. If the source has decayed to undetectable levels can it
> then be disposed of as nonrad material.
>
> Stacey Alderson
If I were making policy, I'd say, "After 10 half lives for all nuclides
in the source (including those that are impurities in the primary
nuclide) and if radiation from the source were less than 0.5 mrem per
hour at two inches (I think that dose rate is what the FDA uses for TV
machines) from any surface. Al Tschaeche