Lapel CAM

["Morris, Robert" <robert.morris@rfets.gov>]

Tom Goff requested information on lapel CAMs


Merlin Gerin Model MCA 11 is an alarming personal air sampler designed to
alert workers to elevated airborne plutonium levels.  Originally developed
by the Commissariat a l'Energie Atomique of France, the monitor was (is?)
made in France by Merlin Gerin.

The unit looks like a softball cut in half and suspended on a lanyard.  It
weighs 420 g and is accompanied by a 600 g belt-mounted battery and
electronics package.  It was described in two English language publications:

		Perrin, M. L. "Plutonium aerosols size distributions in a
reprocessing plant and during decommissioning operations."  Proceedings of
the DOE Workshop on Workplace Aerosol Monitoring, Napa, CA Oct 28 - 30,
1985.

		Charuau, J.  "Design and assessment of a personal air
monitor to optimize the occupational monitoring in plutonium laboratories."
Proceedings of  the DOE Workshop on Workplace Aerosol Monitoring, Napa, CA
Oct 28 - 30, 1985.

While we were employed at Chem-Nuclear (later Rust) Geotech at DOE's Grand
Junction, Colorado, Project Office, Dr. Dowell Martz and I bought two of
these units, tested them in the radon research chamber, and published a
report.  The report, titled "Evaluation of a Personal Air Sampler Designed
to Provide an Early Warning of Plutonium Exposure" was presented at a DOE
Radiation Protection Conference in Knoxville, TN, August 27-29, 1991.
Unfortunately, DOE never published the proceedings of that workshop.  It did
get a pre-print number of GJPO-M-008-91.  There is some chance it is
available from DOE in Grand Junction.  Check the web for information on how
to contact that office.  www.doegjpo.com

The unit uses aerosol size separation and pulse height analysis as the keys
to minimizing radon interference.  When a spurious alarm does occur due to
radon progeny the short-lived Po-218 clears quickly and the alarm ceases
after being removed to a unaffected, well-ventilated area.  Our testing
revealed an intermittent leak past an o-ring seal.  Once the detector was
slightly modified to correct the leak, we found that when the unit was
operated in a 1 pCi/L, 50% equilibrium environment, the detection limit for
plutonium was approximately 21 DAC.

I no longer have the electronic file containing the report, but, if you are
not successful in getting a copy from DOE Grand Junction Office, you may
send me an e-mail and I will mail a copy of the 13 page report to you.


Robert Morris, CHP
Safe Sites of Colorado
Rocky Flats Environmental Technology Site
Building 750
PO Box 464
Golden, CO  80402-0464
303 966-6468

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