Re: H-3 in "EXIT" Signs

[LIPTONW@detroitedison.com]

NCRP Report No. 95, "Radiation Exposure of the U.S. Population From Consumer 
Products and Miscellaneous Sources," states that the tritium in these devices 
is in the form of gas contained in a sealed glass tube.  Each device may 
contain up to 25 Ci of tritium.  The report states that, "...Based on the 
assessment of timepieces, it is probable that the most significant doses 
resulting from this type of application will occur when such devices, after 
their use has been terminated, as sent for disposal with ordinary trash rather 
than being returned to the manufacturer for disposal as provided by the 
general license.  No estimates of the accompanying doses are currently 
available."   
 
I believe that this was the subject of a previous discussion on RADSAFE.  If I 
remember, correctly, the consensus was that the risk from the tritium gas is 
less than the risk from the rechargeable batteries that would be required for 
a nonradioactive sign.   
 
The opinions expressed are strictly mine. 
Here's to a risk free world, and other fantasies. 
 
Bill Lipton 
liptonw@detroitedison.com

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• To: Multiple,recipients,of,list,radsafe@romulus.ehs.uiuc.edu
• Subject: H-3 in "EXIT" Signs
• From: "radsafe@romulus.ehs.uiuc.edu" <radsafe@romulus.ehs.uiuc.edu>
• Date: 10 Feb 97 11:45:17
• Reply-to: radsafe@romulus.ehs.uiuc.edu

Can anyone tell me the form of H-3 used in these self-luminescent EXIT
signs.  I seem to remember someone saying (a long time ago) that the H-3
was in a "solid, non-dispersable form" so that it would pose no
contamination hazard if one of the signs were ever broken up.  But,
recently I thought someone on RADSAFE mentioned H-3 gas in connection
with the EXIT signs.  If it is H-3 gas, what reasoning is used to
justify general licensing for these devices (assuming that the signs
could be ruptured and the gas released).

Thanks,
Chris Hogan
chogan@colan.uams.edu
or 
cchogan@life.uams.edu
  

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