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Re: taking apart smoke detectors



I'd be interested to know which is the legal situation in the US (*no*
experiments with radioactive sources or that described below). Are gas lamp
mantles containing thorium still on sale in the US? Those one finds in
Europe are now marked "non-radioactive", but I bought one of the old kind in
South Africa recently.

Incidentally, the distinction between "radiation", "radioactive material"
and "radioactivity" is of vital pedagogical importance, and I hope that Prof
Edmiston is usually more careful about distinguishing between these terms!

Mark.

At 10:18 21-04-99 -0400, Michael Edmiston wrote:
To the best of my knowledge, there is no license-exempt quantity for
241-Am, so I believe it would be illegal to remove this source from a
smoke detector and use it experiments. For those people who will do it
anyway, I believe the radiation is harder to get off than others have
implied. The 241-Am would most likely be diffused into a metal surface
(such as stainless steel). The 214-Am is put on the metal, then heated
to a dull-red color. The radioactivity diffuses into the surface just
a slight bit. Upon cooling, sources made this way are fairly durable
and not easily rubbed off. When I worked in a national laboratory (Los
Alamos) we made many sources this way. I rubbed them with cotton swabs
to see how durable they were. I could never rub any radioactivity off
any sources I made in this manner.

I do not understand the persons who have said persons under 18 cannot
do radiation experiments. Although I do not have the federal rules
with me, I have the Ohio rules in my lap as I write this. Ohio rules
are supposed to be the same or more stringent than federal rules. It
says persons under 18 years old are limited to one-tenth the exposure
limits for adults. One-tenth the adult exposure is not a lot, but it's
a whole bunch more than zero, and it allows experiments.

We are required to have a Safe Operating Procedure for our x-ray
spectrometer. Our document, which has been approved by the Ohio
Department of Health (the agency acting on behalf of NRC in Ohio)
states "minors ... in no case will receive exposure in excess of two
millirems per hour."

I repeat, this statement (no more than two millirems per hour for
minors) has been approved as compliant with Ohio law. There is also a
statement limiting total exposure for one calendar quarter. But the
point here is that this number is not zero. Are you people telling me
the Ohio law is not compliant with the federal law? Ohio is one of the
states for which NRC has agreed to let Ohio Dept. of Health act in
their behalf.

Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail
edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817



Mark Sylvester
UWC of the Adriatic
34013 Duino TS
Italy
msylvest@spin.it