Re: 137Cs check sources

["Warren Church" <Warren_Church@uml.edu>]

Sorry, I failed to mention that it was an ion chamber that we use as the final check
before entering the gamma cave. You are correct that there is a potential for GMs to
saturate in high dose rate fields.  I understand that there are some models that are
designed to "peg" at very high dose rates, however I still would not trust using any
GM survey meter for this particular use.
warren_church@uml.edu

Michael Kay wrote:

> Warren,
> If this is truly a high radiation area, how do you preclude a GM from saturating
> in a high field and indicating no dose? I have always emphasized that an ION
> CHAMBER is the only proper instrument to use when entering a potential High
> Radiation Area. Is there some new circuitry in these GMs that I am not aware of?
>
> Michael A. Kay, ScD, CHMM
> makay@teleport.com
>
> Warren Church wrote:
>
> > If these are GM survey meters.  You can go to the lowest range and use
> > background radiation for your check source.  For critical situations such as
> > checking before entering our gamma cave (potentially a "very high radiation
> > area" we have either mounted a check source on the wall or permanently mounted
> > a Beta check source on the Beta window and lived with a slightly higher
> > background reading.
> > Warren Church, UML RSO
> > warren_church@uml.edu
> >
> > mdater@nexstar.com wrote:
> >
> > > 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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