RE: Decay-In-Storage

["Jean-Francois, Stephane" <stephane_jeanfrancois@merck.com>]

William,

I guess we use 10 HL because it is about 1000 times less activty (1024) then
initially. The 10 half-lives "rules" normally used in low level rad waste
from nuclear med or biotech facilities is a pratical way to assess a
situation and build forecast or allocate space. What will remain after 10 HL
?  A thousand time less then initial activity. Is it good ?  Depend on what
was there initially !!! So YOU decide when your waste meets the release
criteria fixed on your permit or licence.

Here to dispose (incineration), we go with the 10 HL rule + proper remaining
activity monitoring. I will not rely only on the info on a piece of paper.

Stephane Jean-Francois, Eng. CHP,

Specialiste en radioprotection/Radiation Safety Specialist,
Gestion des risques/Risk Management
Merck Frosst Canada & Co.
tel: 514.428.8695
FAX: 514.428.8670
email:stephane_jeanfrancois@merck.com





-----Original Message-----
From: William Lorenzen [mailto:LORENZEN_W@A1.TCH.Harvard.edu]
Sent: Wednesday, April 19, 2000 10:30 AM
To: Multiple recipients of list
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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