RE: Unidentified device

["Conklin, Al" <Al.Conklin@DOH.WA.GOV>]

I don't know when thorium was last used in camera lenses, but about five

years ago, I was accompanying a photographer and reporter through a portal

monitor at Hanford and the lens of the camera set off the alarm and ended up

getting confiscated by the health physics technician because he never heard

of camera lenses with thorium in them. It took the photographer about 48

hours before they would give it back to him.



Going through a similar portal monitor a couple of years later was how I

found out my watch face had Promethium 147. Fortunately that HPT knew about

the use of Pr-147 in watch faces, so I didn't lose it.



-----Original Message-----

From: Flood, John [mailto:FloodJR@NV.DOE.GOV]

Sent: Thursday, September 25, 2003 1:42 PM

To: 'NIXON, Grant (Kanata)'; 'Todd Brautigam';

radsafe@list.vanderbilt.edu

Subject: RE: Unidentified device





>I have heard of old camera lenses being marginally

>radioactive (Th-232+decay products).



True.  At one time, thorium oxide was widely used in manufacturing glass to

change the index of refraction for microscope and camera lenses.  However,

it hasn't been used for this in decades.



Bob Flood

Nevada Test Site



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