[ RadSafe ] IBIS Sr-90 source construction

Tue May 31 13:22:22 CDT 2016

Hi Franz and all,

Just back from a lovely Memorial Day weekend here in the US, and a little behind in RadSafing :}  

While it is correct that you can’t electroplate Sr from a simple aqueous solution, methods to plate a cathodic surface with Sr have been invented over the years, and given the small mass involved with a half millicurie source (< 1 microgram) , this may be the most practical way to make a source even considering the need for a protective coating to prevent oxidation while attenuating the beta emissions minimally.   I did not find a direct reference to the IBIS source in question, unfortunately, so this is a reasonable possibility.  Most forms of Sr are easily oxidized and sensitive to water, so in the event of a fire contacting the source, it is likely to release the Sr/Y.  Strontium titanate is an exception here but seems that would be hard to make precisely in such small quantity, but perhaps there is a way to do this of which I an unaware (Anyone?).   Of course, it would be better to have a direct reference but it seems this is hard to find :}   I haven’t needed to look up a sealed source construction in a few years, but it seems these are much harder to find now than they used to be.

I agree there is far too much of the attitude that anyone who says anything different than I say is wrong, stupid, criminal, etc.   There is certainly no place for this kind of attitude here on RadSafe!  

Mit freundlichen Grüßen,

Brad

> On May 29, 2016, at 5:57 PM, Franz Schönhofer <franz.schoenhofer at chello.at> wrote:
> 
> Hi all,
> 
> A little chemistry for Radsafe.
> 
> Strontium is a silvery metal and a typical earthalkali element. It is produced by reducing strontium oxide with aluminium powder at high S. Because of its norm potential of -2,89 V it is not possible to electroplate it from an aqueous solution of strontium salts. It is rather reactive and reacts easily with water to form strontium hydroxide and hydrogen. It burns when ignited. Strontium salts show when heated in a flame a beautiful karmin-red colour, which is  used in fireworks.
> 
> Sr-90 is used in many technical applications, but it should be noticed that in many applications the much harder beta radiation of its shortlived daughter radionuclide Y-90 (in equilibrium) is actually the "active ingredient". The same is true for the health effects. As well it should not be forgotten that also bremsstrahlung (what a nice english word!) should not be neglected. Remember the Russian forest workers who unknowingly found a well shielded electricity generator based on a Sr-90 battery in winter and sat on it because it was warm.
> 
> After having read the message on Radsafe I thought that maybe we should not be so harsh with some anti-nuclear agitators because they simply have not the appropriate education. But I discarded this thought quickly, because these people believe really that they or their stars possess the truth and nothing but the truth and anyone who does not share their opinion is stupid, a massmurderer and a criminal. Contrary to this attitude Brad wrote "I believe"!
> 
> Best regards,
> 
> Franz
> 
> 
> -----Ursprüngliche Nachricht----- From: Ted de Castro  Sent: Wednesday, May 25, 2016 5:43 AM
> To: The International Radiation Protection (Health Physics) Mailing List - theSubject: Re: [ RadSafe ] IBIS Sr-90 source construction
> From what I read on a Google search - the material is a dispersible powder.
> 
> On 5/24/2016 6:26 PM, Brad Keck wrote:
>> Hi Brian,
>> 
>> I believe these are electroplated sources, so at the surface of the metal (stainless steel usually in sources) a thin coat of strontium will be reduced to it’s metallic form.
>> 
>> It is important of course that the strontium “plate” be very thin so that beta emissions are unshielded in the direction of the detector….
>> 
>> Hope this helps..
>> 
>> Brad
>> 
>> 
>> 
>> 
>>> On May 24, 2016, at 5:04 PM, Rees, Brian G<brees at lanl.gov>  wrote:
>>> 
>>> Does anybody on the list know the physical form of Sr-90 sources used in helicopter blade pressure indicators?
>>> 
>>> Specifically, is it strontium titanate, or some other material with a low solubility?
>>> 
>>> Thanks,
>>> Brian Rees
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