[ RadSafe ] Ra-226 Static Eliminator Bar

Tue Jul 12 22:05:31 CDT 2011

Mike is correct in saying that some of the radon might wander off. However, 
to get your numbers, you would need > 50% radon emanation and a completely 
open or unsealed source. Radon emanation for man-made radium compounds is 
usually pretty low (< 1%).

So, I think that, even a leaky source, would not explain your numbers. You 
could try the experiment again but put the bar in some sort of container for 
10 days (i.e. a few radon 1/2 lives to achieve equilibrium). Even with a 
fairly crude container, you should be able to contain more than 50% of 
radon.

My guess is that there is something wrong with the gamma spec library and 
its getting confused, identifying something as a Ra-226 gamma, that really 
isn't. Ra-226 isn't a very intense gamma emitter. So, even a little bit of 
cross talk from something else in the decay chain would create a large error 
in the Ra-226 reading.

Cheers,
Kai

----- Original Message ----- 
From: "BRISSON Nicolas" <nicolas.brisson at irsn.fr>
To: "The International Radiation Protection (Health Physics) MailingList" 
<radsafe at health.phys.iit.edu>
Sent: Tuesday, July 12, 2011 9:20 AM
Subject: Re: [ RadSafe ] Ra-226 Static Eliminator Bar

> Mike explained it all.
>
> Radium 226 has a half-life of 1600 years, radon 222 of 3,8 days, lead 214 
> of 26 min and bismuth 214 of 20 min.
>
> The only other nuclide you could find with gamma spectrometry is lead 210, 
> but its gamma rays are pretty weak in energy or intensity (13 keV, 22% - 
> 47 keV, 4%)
>
> Nicolas Brisson
> IRSN/DEI/SIAR
> route du Panorama
> 92262 FONTENAY AUX ROSES
> tel : +33 1-58-35-87-24
> por :  +33 6-08-76-55-32
>
>
> -----Message d'origine-----
> De : radsafe-bounces at health.phys.iit.edu 
> [mailto:radsafe-bounces at health.phys.iit.edu] De la part de Brennan, Mike 
> (DOH)
> Envoyé : samedi 9 juillet 2011 00:31
> À : The International Radiation Protection (Health Physics) MailingList
> Objet : Re: [ RadSafe ] Ra-226 Static Eliminator Bar
>
> I don't think you should expect the lead and bismuth to be in equilibrium 
> with the radium, as the decay product of radium is radon, and you should 
> expect a certain amount of it to wander off (how much depends on how well 
> sealed the radium source is).  On the other hand, you would expect the 
> lead and bismuth to be in equilibrium with each other, and they are.
>
> There are several other isotopes in the chain that are there, but I don't 
> recall how easy they are to find in gamma spec.  It probably depends in 
> part on your library.
>
> -----Original Message-----
> From: radsafe-bounces at health.phys.iit.edu 
> [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of 
> alstonchris at netscape.net
> Sent: Friday, July 08, 2011 3:02 PM
> To: radsafe at health.phys.iit.edu
> Subject: Re: [ RadSafe ] Ra-226 Static Eliminator Bar
>
> Nicolas
>
> I do not have a table of half-lives to hand, and I am ashamed to say that 
> I no longer remember the basic U-238 decay chain, but, should the Lead and 
> Bismuth be in equilibrium?  I mean to say, is the device leaking?
>
> I await the slings and arrows with equanimity.
>
>
>
> Cheers
> cja
>
>
>
>
> -----Original Message-----
> From: BRISSON Nicolas <nicolas.brisson at irsn.fr>
> To: The International Radiation Protection (Health Physics) MailingList 
> <radsafe at health.phys.iit.edu>
> Sent: Fri, Jul 8, 2011 8:24 am
> Subject: Re: [ RadSafe ] Ra-226 Static Eliminator Bar
>
>
> Hi all,
>
> For once, I won't for help but try to bring a bit of information regarding 
> the
> static eliminator bar I found.
>
> Some colleagues carried out à gamma spectrometry using HpGe detector (20%,
> p-type).
>
> Total activity results are given below :
> radium 226 : 75 Mbq +/- 25%
> lead 214 : 34 MBq +/- 15%
> bismuth 214 : 36 MBq +/- 15%
>
>
>
> Nicolas Brisson
> IRSN/DEI/SIAR
> route du Panorama
> 92262 FONTENAY AUX ROSES
> tel : +33 1-58-35-87-24
> por :  +33 6-08-76-55-32
>
>
>
> -------------------------------------------------------------------------------------------------------
>
> From:   "BRISSON Nicolas" <nicolas.brisson at irsn.fr>
> To:     "The International Radiation Protection \(Health Physics\)
> MailingList" <radsafe at health.phys.iit.edu>
> Date:   04/12/2011 10:06 AM
> Subject:        [ RadSafe ]  Ra-226 Static Eliminator Bar
> Sent by:        radsafe-bounces at health.phys.iit.edu
>
>
>
>
> Hi all,
>
>
>
> 2 years ago we had a short discussion about radium-226 static eliminator
> bar (excerpt below).
> At that time I could only find the article mentioned below.
>
>
> Last week I found a static eliminator bar from US Radium Corp.
>
>
> As the dose rate ranged from 1 mSv/h to 1,6 mSv/h between 5 and 0 cm from
> the bar, we didn’t spend too much time studying it at close range. So I
> would be interested in layouts or any information available about these
> bars
>
>
>
> Thanks,
>
>
> Nicolas Brisson
> IRSN/DEI/SIAR
> route du Panorama
> 92262 FONTENAY AUX ROSES
> tel : +33 1-58-35-87-24
> por :  +33 6-08-76-55-32
>
>
> --------------------------------------------------------------------------------
>
> From: BRISSON Nicolas <nicolas.brisson at irsn.fr>
> To: radsafe at radlab.nl
> Sent: Wed, 28 October, 2009 20:58:57
> Subject: TR: [ RadSafe ] Ra-226 Static eliminator bar
>
> Hello all,
>
>
> I don't have much information on this topic but you can find an article at
> the web address below.
> American Journal of Public Health (August 1950) :
>
>            http://www.ajph.org/cgi/reprint/40/8/943.pdf
>
>
>
> In this article you can read that these static eliminator bars contained
> 25 or 50 µg of radium 226 per linear inch.
> Some Ionotron with radium 226 were manufactured by US Radium Corps.
>
> In France, you could buy a ionotron t.200 for around 20€ in 1960.
> For a total length of 15 cm, the active part had a length of 5 cm. In the
> safety sheet given with the ionotron, it was said that you were at the
> safe distance from the ionotron at 25 cm. Remember though that it was in
> 1960...
>
>
>
>
>
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