RE: 137Cs check sources

["Fulmer, Philip" <philip.fulmer@cplc.com>]

Mark,

Exempt quantity sources strike again!!!  I'm sure there are others who
can tell lots of stories about similar situations, and it's an
understandable dilemma, particularly for those around you who may not
have had as much experience with check sources and radiation detection
instrumentation.  You're no doubt getting lots of questions, judging
from your post.

1.  Exposure rate from the source:  using a specific gamma ray constant
of 0.33 R/hr at 1 meter  per curie for Cs-137 and adjusting it to a
12-inch distance and for a 1microcurie activity shows that the exposure
rate is much less than 1 mR/hr and is actually in the microR/hr range.
An 8-hour exposure would give a person less than 50 microrem assuming
that they were at a 12 inch distance the whole time, which isn't too
realistic.  True dose to a person in the vicinity is probably in the
single digit microrem or less.  
2. Is there a better way to check meters for functionality?  In
principle, you could store the check sources separate from the
instrument (i.e., in a cabinet) and then take the meter to the source on
a daily basis, thus limiting the time that a person is exposed to the
check source.  Depending on the size of your facility, number of
sources, etc., that may be an option.    There is no way to verify
operation of the detector itself, however, apart from using a radiation
source.  On some instruments, you can check the electronic circuitry
using a pulser, but the radiation detector requires a source of
radiation.  Otherwise, it's kind of like trying to check a PA system
without having to use any sound input.
3.  As far as handling the protest, the best thing is acknowledging that
the questions are valid ones, but they can be answered.  And you'll
certainly want to identify through considerate questioning what the
issue really is.  Is there a concern about some specific biological
effect?  Radiation detection instrumentation is able to detect
relatively small amounts of Cs-137; so the fact that the Cs-137 is
detectable does not necessarily mean that there is a radiation exposure
hazard.   Yes, there is some minor amount of exposure.  However, you
could just as easily use a bottle of lite salt as a check source instead
of a commercial check source.  Your biggest challenge is to find out
what the fear is first instead of trying to address broad questions with
all the standard answers that we use (e.g., the dose is much less than
background, it's an exempt quantity source that is not regulated,
there's radiation all around you, etc., all of which are true and may be
used as reassurances).   After identifying the fear itself, then you can
begin to answer the questions more intelligently.


__________________________
Philip C. Fulmer, PhD, CHP 
Carolina Power & Light Company
Harris Energy and Environmental Center
3932 New Hill-Holleman Road
New Hill, NC 27562
philip.fulmer@cplc.com
(919) 362-3363      

>----------
>From: 	mdater@nexstar.com[SMTP:mdater@nexstar.com]
>Sent: 	Thursday, September 17, 1998 12:44 PM
>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.
>
>
>
>************************************************************************
>The RADSAFE Frequently Asked Questions list, archives and subscription
>information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html
>
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html