[ RadSafe ] Radium

Wed Nov 14 13:18:34 CST 2007

Thank you to all who replied.

I agree that the blue luminescence referred to is almost certainly Cerenkov radiation.  As the article didn't specify the radium being in water I assume they were talking about the source being in air.  If the source was high enough activity that it was producing enough Cerenkov radiation to be visible with the unaided eye, I am not sure that being close enough to see the light would be in keeping with ALARA. 

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of Franz Schönhofer
Sent: Monday, November 12, 2007 2:36 PM
To: 'Bailly, Helen A'; Brennan, Mike (DOH); 'radsafe'
Subject: AW: [ RadSafe ] Radium

Helen, Mike,

I would not exclude that very high activity samples of radium (I suppose the question is certainly about Ra-226) might exhibit a bluish "luminescence" - but this might be Cerenkov-light and I would rather expect it in a Ra-226 solution, especially since radium (the metal) is extremely hygroscopic.
Please compare it to the Cerenkov-effect in nuclear research reactors like the TRIGA-Mark-X-ones. 

The old radium painted dials owe their luminescence to the interaction between the alpha's emitted by radium (and daughters) with zinc-sulfide - metallic zinc would not show any luminescence. In those times even the use of other natural alpha-emitters were considered for illumninating purposes - I know about a proposal to use a uranium-decay-product (sorry I do not remember which one) in combination with ZnS for illuminating rooms on a commercial basis - no joke! 

Later painted dials included several radionuclides like Sr-90, promethium, but all probably in combination with luminescing organic agents and not ZnS.
The most recent were the use of tritiated polystyrene, mixed with organic scintillation compounds. The polystyrene lost according to research about 5% of its tritium content per year by chemical decay and diffusion. I myself have done some research into the effect of tritium uptake from wrist watches and it showed that the uptake from a certain brand with plastic casing was quite enormous, about 3000 Bq/l urine showed up within a few days. The tritium uptake from other brands using steel casings or titanium casings was not either negligible, but slightly less. Titanium is well known to take up lots of hydrogen (and tritium) and was once a favourite for storing hydrogen for alternative cars fuel.  

This is a little excurse on the question of luminescence for watches. May I finally mention that I have an antique alarm clock with radium painting, obtained from a RADSAFE contributor, which shows a respactable dose rate on my dose-rate meter when approaching it, but does not glow in the dark any more..... 

I would appreciate to receive experience from other people!

Best wishes,

Franz

----------------------------------------------------------------------------
Franz Schoenhofer, PhD
MinRat i.R.
Habicherg. 31/7
A-1160 Wien/Vienna
AUSTRIA

-----Ursprüngliche Nachricht-----
Von: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] Im Auftrag von Bailly, Helen A
Gesendet: Montag, 12. November 2007 15:17
An: Brennan, Mike (DOH); radsafe
Betreff: RE: [ RadSafe ] Radium

I am not sure about the faint blue colored luminescence, most of the radium painted items I've ever seen have had a greenish or yellowish tint to their luminescence, and as I understand it the luminescence in most old radium paints actually came from the reaction between the radium and the zinc in the paint.  This is not to say that that there is no blue luminescence.

The main reason I reply however, is to caution against believing everything you read on Wikipedia.  Wikipedia is editable by anyone who looks at it and there is not a screening or verification process, so if it is edited by a knowledgeable person, as is often the case you are good, but there is no way of knowing if that is the case.

Read Wikipedia with a grain of salt.  

Life is short - Break the rules!  Forgive quickly!  Kiss slowly!  Love truly! Laugh uncontrollably!... And never regret anything that made you smile.

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helen Bailly

Radiation Dosimetry Records Unit

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Mail Stop 4147

(208) 526-5261

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-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of Brennan, Mike (DOH)
Sent: Thursday, November 08, 2007 12:34 PM
To: radsafe
Subject: [ RadSafe ] Radium

The Wikipedia entry on radium says that, "Radium is luminescent (giving

a faint blue color),..."  Does anyone here know if that is true?  I have

been under the impression that the luminescence in radium painted items

was from phosphorescent chemicals in the paint that absorbed energy from

ionizing radiation and re-radiate in the visible spectrum.  There are

other things in the article that I have questions about, too, but I

should be able to answer them with references I have here.

What do people here think of Wikipedia?  I have found it to be a useful

source for many topics, though I've also seen content that seems to have

an agenda, or that is "everyone knows" type stuff that is wrong. 

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