Re: radioactivity in film developer

[Janzow1@aol.com]

Radsafers,

Thanks to all who responded to my inquiry, both on the list and privately.

Brief summary of responses:
1..What I have found is very likely K-40.  Possibility of uranium or thorium 
isotopes.  Uranyl nitrate was once used in some developers, but is no longer 
common.  Uranium and thorium were used in some film emulsions in the past, 
but are not believed to be used now.  (Uranium and thorium are unlikely 
candidates because my equipment is sensitive to alpha as well as beta/gamma, 
but no alpha was detected.)
2.  NRC and most, if not all, states specifically exempt photographic 
chemicals containing K-40 and uranium, and therefor their receipt, 
possession, and transfer are not regulated in most states.
3.  The 35 pCi/gm I found is below the 10CFR30.70 exempt quantity 
concentration for "everything except I-126, I-131, and unknown beta/gamma 
emitters with half-lives under 3 years".
4.  The level I found is consistant with what would be expected from 
compounds containing natural potassium.

Thanks to all.

Ed Janzow
janzow1@aol.com
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html