Use of unsealed thorium

["497509@KP40" <jgreco@kodak.com>]

To: RADSAFE --EKSMTP

*** Reply to note of 05/13/96 05:34
From: J.M.Greco, OHSP, Radiation Safety Officer, 1/320/KP/2-6261
Subject: Use of unsealed thorium
Regarding unsealed thorium usage:

Our Hawk-Eye plant used thorium from the mid-40's to mid-80's for the
manufacture of optical lenses, which were placed in consumer, commercial,
and military products.  They contained 6 to 30% by weight thorium oxide.
Thorium was chosen because of its higher refractive index, and its
superior stain resistance and weathering ability.  Thorium was also used
in a coating agent for the lenses, called rouge.

We also used to manufacture a professional-grade photographic paper called
dye transfer paper which contained low levels (~1300 ppm) of thorium nitrate.
As I understand it, thorium was used because it enabled the paper to hold
images crisp and clear (esp.enlargements) for a very long time, and
resisted fading.

Our unsealed thorium is gone now (boo-hoo).  Decommissioning adventures
are a whole 'nother story...

 Joe Greco, RSO/LSO  x83324
 e-mail:  jgreco@kodak.com
   "Illegitimi non carborundum"