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RE: 137Cs check sources
According to the info. in the Ludlum catalogue, 175 CPM/uR/hr for a 44-2
probe, this is 0.4 mR/hr. Move out about 1 ft. away, the exposure should
drop to about 0.004 mR/hr. I can't imagine this contributing greatly to
extremity exposure. I have to move a 8 uCi source within a few inches of an
ion chamber to detect it. The 44-2 is a scintillator and thus will sound
fierce at contact with a button. A cheaper method that I use is to glue a
small bit of uranyl acetate powder to the instrument and cover with a foil
sticker. As far as regulation, I can't say where to find it exactly. Iowa
(agreement state) included it in a state reg. guide and I've noticed FEMA
inspectors looking to see if instruments were checked during drills. I
don't believe the check source has to be traceable, just so long the
instrument can reproduce the reading.
-----Original Message-----
From: radsafe@romulus.ehs.uiuc.edu
[mailto:radsafe@romulus.ehs.uiuc.edu]On Behalf Of mdater@nexstar.com
Sent: Thursday, September 17, 1998 11:45 AM
To: Multiple recipients of list
Subject: 137Cs check sources
I have been installing the 1 uCi 137Cs check sources to our survey meters.
I have had an uproar over the fact that these sources are emmiting an
surveyable reading even 12 inches away from the checksource
I measured 65000cpm (using a ludlum 44-2 detector) on surface of one of
these checksources.
My questions:
Does anyone have data on the exposure rate of these sources to an
individual that is in proximity of the source for 8 hr?
Is there a better way to check meters for functionality, rather than have a
check source attached?
How have others tackled this protest (that the check source is irradiating
the individuals, hands, arms, benchpartner, etc.)
When was this regulation(and can you reference this regulation to me) put
in place that an individual has to be exposed to radiation for the reason
that a survey meter can be checked against radiation?
Mark Dater
NeXstar Pharmaceuticals, Inc.
2860 Wilderness Place
Boulder, CO. 80301
Work phone: (303) 546-7703
Fax: (303) 444-0672
E-mail mdater@Nexstar.com
These are my comments and questions and not those of my employer.
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