Re: Info on radium paint?

[Chris Davey <cdavey@med.phys.ualberta.ca>]

On Fri, 27 Jan 1995 CLEMENTC@crl.aecl.ca wrote:

> My office deals with the occasional radium painted dial.  The radionuclide
> is Ra-226.  I've never worked out the concentrations, but the most active
> dial I've seen reads about 1 mR/h on contact.  Interestingly, the dial
> is on a radiation detection instrument (but the scale is in R/h, so
> one mR/h would hardly show up).  As for manufacturing techniques, the
> radium paint was simply painted on by hand.
> 
> Hope this info is useful.
> 
> Chris Clement
> Low-Level Radioactive Waste Management Office
> Atomic Energy of Canada Limited
> CLEMENTC@CC4.CRL.AECL.CA

I used to be an inspector for the Atomic Energy Control Board (Canada's
equivalent of the U.S. NRC) and surveyed a lot of aircraft with
radium-painted dials.

Dose rates off one dial can be as much as 5 mR/h, with as many as 40 dials
in DC-6, Convair, and other, similar vintage planes.  With a large number
of dials facing the pilot, the dose rate in the pilot's seat can easily be
0.5 mR/h.  Some old signs, controls, and other components have radium
paint on exposed surfaces (i.e. not behind glass).

But the biggest hazard from these dials is to the instrument repair
companies, as it is not, repeat not possible to visually ascertain whether
a particular dial is radioactive or not, and these people take the dials
off during repairs.  Problem is, the activity has accelerated the aging of
the paint, and it is flaking off and floating around in the air in the
form of microscopic particles.

Of course, all things are relative, and the actual hazard in most cases is
probably not too great.  If young children were exposed to someone's
personal collection of antique instruments, and ate their lunch without
washing their hands, then some radium would certainly be ingested.

I have a lot more information on locations of aircraft (museums, personal
antique WW2 planes, short commercial routes, etc) and would be willing to
provide same if it would be useful.

Chris Davey, RSO
Cross Cancer Institute
Edmonton, Alberta
Canada, T6G 1Z2
(403) 492-7477
fax   492-8202