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RE: Determining activity of odd shaped parts
Clarification:
I should have expressed this as a two part question.
First, I need to come up with geometry corrections for odd part shapes being analyzed by gamma spectroscopy (HPGe). Small parts can be counted in a typical fixed system with a shielded cave. Larger parts could be counted with a portable HPGe. Beyond that, we don't have a lot of specialized equipment. Just the usual collection of portable contamination detectors and dose rate meters.
Second, our organization is trying to define the best method for us to determine the activity of parts activated by exposure to our accelerators. We are looking for suggestions from others.
Rick Edwards, Analyst
The Boeing Company
richard.w.edwards@boeing.com
> ----------
> From: Keith Welch[SMTP:welch@jlab.org]
> Reply To: radsafe@romulus.ehs.uiuc.edu
> Sent: Thursday, March 18, 1999 9:49 AM
> To: Multiple recipients of list
> Subject: Re: Determining activity of odd shaped parts
>
> <HTML>
> Richard,
>
> <P>If you have access to a gamma spec system (and the parts are small enough),
> you can try counting them directly. You'll need to calibrate a geometry
> that minimizes to the extent practical the problem of the size and shape
> of the item. Or you can get one of the fancy in-situ counting systems.
> Sometimes we do this with small parts. If you have a point calibration
> source, you could try calibrating with the source at some known distance
> from the detector, then when counting, place the object at that distance.
> It will get you a fair estimate. In some materials (Al for example)
> you'll often have a lot of positron emitters that you can't ID and therefore
> can't estimate activity for because all you'll get is a big 511 peak.
> But if you know what nuclides are present, you can estimate their activity
> by the count rate in that peak. But it sounded like you were looking
> for a way to calculate the induced activity rather than measure it.
> I'll pass your post along to our resident expert on that. But often,
> because of the assumptions you have to make when calculating this, the
> direct measurement method is probably just as good or better.
>
> <P>--
> <BR>Keith Welch
> <BR>Thomas Jefferson National Accelerator Facility
> <BR>Newport News VA
> <BR>welch@jlab.org
> <BR>Ph: (757)269-7212
> <BR>FAX:(757)269-5048
> <BR> </HTML>
>
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