From: SRS <steve_schoner@...>
To: CDV700CLUB@yahoogroups.com
Sent: Friday, January 27, 2012 1:37 PM
Subject: [CDV700CLUB] Re: Holy COW!

 

I had the deck marker in that heat sealed poly bag for about 3 months.

When I decided to sell it last week I opened the bag to take the photos and make measurements.

That is when I tested the bag. Not much if any alpha outside the bag, but lots of beta and some gamma.

I don't think that any Radon escaped the bag. It was all contained within.

Six days later I tested the bag with my thin window GM tube on my NCA General Scaler Ratemeter Model RCR-1; very little radiation remains, probably due to radio lead.

I suspect that the poly does take up Radon and holds it, probably not as effective as activated carbon though.

I have some other disks also heat sealed in poly bags and when I get some time to do so, I will experiment with those bags as well.

So, to keep these disks safe, it is best to heat seal them in poly bags. Zip locks alone probably not good enough unless heat sealed.

Steve.

--- In CDV700CLUB@yahoogroups.com, "jsboggess@..." <jsboggess@...> wrote:
>
> Your discovery prompts many simple home experiments;
>
> 1. Looking for alphas with an PDR-56 alpha scintillator counter on the OUTSIDE of the plastic bag to see if Radon or Radon daughters have diffused thru the plastic...
>
> 2. Repeat the above alpha scintillator check on an unopened bag-encased deck marker. I;d expect that alphas would not make it thru plastic, but I'm not sure about Radon atoms...
>
> 3. Repeat the above alpha check on both sides of the bag, see the relative alpha count on either side of the plastic.
>
> How long did you have the deck marker sealed inside the bag? I can see all kinds of experimental fun here. Of course, if you have only 1 marker, there'll be lots of reseals and waiting for equilibrium again.
>
> I have a PDR-56 and a plastic-wand-encased Ra-226 check source. The -56 ONLY counts alphas, counts like a bansee on a WWII aircraft gauge if the glass is removed, hardly nothing if glass is in place or if a piece of paper is between -56 and the source. Hmmm, may have to investigate myself for creeping Rn daughters,,,
>
> Jay Boggess
>
> Steve wrote;
>
>
> I am selling a deck marker on Ebay:
>
> Item 190630224674
>
> I keep them in heat sealed plastic bags. Well I cut open the bag that this disk was in to test it. It measures ~16 mR/HR with a calibrated CDV700 standard configuration with beta shield closed.
>
> Then I tested the bag.
>
> HOLY COW !
>
> I could hardly believe my eyes. With the beta shield open on the X1 scale it pegged.
>
> On the X10 scale it registered ~1500-2000 CPM
>
> With the beta shield closed just barely on X1.
>
> I held it up to the light to see if there was any evidence of contamination. It was clear as ever.
>
> The most likely culprit is Radon (Ra-222) that saturated the plastic.
>
> So leaving the bag open for a while, the readings over the next couple of days decreased, at a rate that is consistent with Radon.
>
> I think that Radon had actually permeated the plastic poly bag to saturation, and an equilibrium was established over the months that I had the disk heat sealed in that bag.
>
> So, polyethene bags can serve as well if one whats to snag Ra-222 from a radium cow.
>
> And what remains as the Ra-222 decays are the daughters.
>
> Steve
>
>
>
>
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