[ RadSafe ] hand held meters

Thu Jan 23 10:02:59 CST 2014

Further to what Philip says, marine black shales such as the Kolm Shale in
Sweden, Chattanooga Shale in the Eastern USA and the Pierre & Mancos Shales
around the Rocky Mountains & Eastern Plains are endowed with about 0.01%
uranium. Other rocks such as the marine phosphorites in Florida, Louisiana,
Pre-Caspian & Morocco also have relatively high uranium endowments
naturally.  Most shales are also relatively high in potassium

Dan ii

Dan W McCarn, Geologist
108 Sherwood Blvd
Los Alamos, NM 87544-3425
+1-505-672-2014 (Home – New Mexico)
+1-505-670-8123 (Mobile - New Mexico)
HotGreenChile at gmail.com (Private email) HotGreenChile at gmail dot com

On Thu, Jan 23, 2014 at 8:56 AM, KARAM, PHILIP <PHILIP.KARAM at nypd.org>wrote:

> One other thing to be aware of is that some rock and soils are
> potassium-rich, which can also mess with your interpretation of results.
> This happened to me once at a radium remediation in Illinois - until we
> realized what was happening we were "cleaning up" soil that was chock-full
> of high-potassium clay. When we were able to show this we changed our
> approach to doing gross measurements, followed by (for apparent hot spots)
> performing single-channel analysis at the K-40 peak. If we could show that
> the elevated counts were primarily due to K-40 then we didn't worry any
> further.
>
> The bottom line is that you should also consider that the rocks and soils
> might cause your readings to change in a way that has nothing to do with
> possible contamination. This might be the "second step" you mentioned.
>
> Andy
>
> -----Original Message-----
> From: radsafe-bounces at health.phys.iit.edu [mailto:
> radsafe-bounces at health.phys.iit.edu] On Behalf Of
> JOHN.RICH at sargentlundy.com
> Sent: Thursday, January 23, 2014 10:45 AM
> To: The International Radiation Protection (Health Physics) Mailing List
> Cc: radsafe-bounces at health.phys.iit.edu
> Subject: Re: [ RadSafe ] hand held meters
>
> Thx  for all the  help on the handheld meters.  It looks like we have an
> approach for our particular problem, but since this is for a client, the
> details aren't "available for publication."  However, the advice and
> feedback made it pretty clear that low dose rate measurement outdoors is
> an art not a science, so we're basically going with a two stage approach.
> First stage is a go/no go survey with a conservative decision level.  If
> the decision level is exceeded, the client will call in the experts for a
> second stage. There will probably be a fair number of false positives, but
> that seems to be acceptable.
>
> Again, thx.  RADSAFE has once again proven to be solid resource.  Hope to
> return the favor on questions where I think I might know something useful
> ;-)
>
>  - - jmr
>
> John Rich
> 312-269-3768
>
>
>
> From:   "KARAM, PHILIP" <PHILIP.KARAM at nypd.org>
> To:     "The International Radiation Protection (Health Physics) Mailing
> List" <radsafe at health.phys.iit.edu>
> Date:   01/23/2014 09:26 AM
> Subject:        Re: [ RadSafe ] hand held meters
> Sent by:        radsafe-bounces at health.phys.iit.edu
>
>
>
> John -
>
> Very good advice. It's also worth mentioning that many of the NaI-based
> microR meters are energy-dependent, so their readings can be off
> substantially. We did a test along with NYS DOH an USEPA, using a
> NaI-based detector side-by-side with a pressurized ion chamber at a site
> contaminated with thorium. The NaI detectors (we used two or three
> different brands) all came in with readings that were about half of what
> the PIC registered. The reason, of course, is that the NaI detectors
> over-responded to the low-energy gammas from the Th decay series.
>
> So I concur - a PIC is a far better way to measure low levels of radiation
> compared to either GM or NaI.
>
> Andy
>
> -----Original Message-----
> From: radsafe-bounces at health.phys.iit.edu [
> mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Dixon, John E.
> (CDC/ONDIEH/NCEH)
> Sent: Thursday, January 23, 2014 9:54 AM
> To: The International Radiation Protection (Health Physics) Mailing List
> Cc: EDWARD.L.MARTIN at sargentlundy.com
> Subject: Re: [ RadSafe ] hand held meters
>
> I have looked over most of the posts on this article on RADSAFE. If you
> are looking for low background gamma radiation, use a simple stable
> instrument. NaI probes are quite sensitive and can exhibit wide swings in
> their count rates and obtaining spectra does not seem to be your goal. I
> recommend the one instrument which has not received attention here: the
> pressurized ion chamber (PIC). There are several manufactures (Fluke,
> Thermo-Eberline, etc.). Fluke's can accommodate very low dose rate levels
> (uR/hr) and they are digital with slower response times; however, they
> give you pretty stable final readings without the count rate swings a NaI
> system might give you. If you are looking to rapidly identify a source of
> the dose rate level in question, use a NaI to find where the source is and
> then use a PIC to quantify the dose rate level. Wait times for this
> instrument vary, but I believe one minute should be sufficient for a
> reading. Averaging 3 readings might also be a good idea.
>
> Regards,
> John Dixon
>
> -----Original Message-----
> From: radsafe-bounces at health.phys.iit.edu [
> mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of
> JOHN.RICH at sargentlundy.com
> Sent: Tuesday, January 14, 2014 3:19 PM
> To: radsafe at health.phys.iit.edu
> Cc: EDWARD.L.MARTIN at sargentlundy.com
> Subject: [ RadSafe ] hand held meters
>
> radsafers
>
> We're looking for practical experience on using hand held monitors in an
> outdoor setting.
>
> The background gamma dose rates in the area are about 0.02 mR/hr.
> The expected change that we want to see is from about 0.02 mR/hr to 0.04
> mR/hr.
> So the dose rate goes from about 0.02 mR/hr to 0.04 - 0.06 mR/hr. (two x
> background to 3 x background)
>
> The questions are:
> (1) what kind of hand held monitor would be good to see this change (e.g.,
> PIC, GM tube, scintillation detector, etc.)?
> (2) since this is outdoors, how long should the surveyor wait for the
> readings to stabilize after a random spike?.
>
> I asked a similar question earlier,  and the consensus seemed to be that
> making these measurements with a hand held monitor was problematic. My
> personal experience in this area is very limited, but it seems like the
> spikes could reach about 0.01 mR/hr and lasted several seconds.
>
> thanx in advance  - -jmr
>
> John Rich
> 312-269-3768
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