Re: use of neutron sources

[stephane_jeanfrancois@Merck.Com (Stephane Jeanfrancois)]

Simply to note that Ra-226/Be neutron sources are almost "historical
artefact" and are no longer in use (at least in Canada) because, of
course, of the Ra-226 source.  Modern equipment like TROXLER 3440 (and
other series), Humboldt or  CPN portable density and moisture gauges all
use 30-40 mCi of Am-241/Be. Shielding within these gauges is excellent
and most of the doses received are during annual (winter) maintenance
(some companies have 20 to 30 of these gauges under one roof during
wintertime). If I remember well, a study was made on that topic
(dosimetry, portable gauges) and might be available with the Atomic
Energy Control Board (web site:http://ulysses.srv.gc.ca/aecb/).This site
is also a good source on Canadian regulatory requirements.


Stephane Jean-Francois Phys, Eng.
RSO
Merck Frosst Canada
stephane_jeanfrancois@merck.com
 ----------

It probably will be used for moisture measurements in locating leaks.
Neutrons are scattered by hydrogen in water under the roofing.  This
is a common industrial application for Am-241/Be or Ra-226/Be sources.
Approved designs produce low to unmeasurable dose rates at distances
farther away than ~1-2 m.

ELI A.PORT, CHP, CIH, P.E.
RSSI
eport@nwu.edu
VOICE:847.965.1999, 24X7
FAX:  847.965.1991