[ RadSafe ] A simple, down to earth beta dose rate question

[jjshonka at shonka.com]

Dear Mattias:


You could, in principle, calibrate with any nuclide, and provide correction factors for others.  This would be useful to understand the instrument response and provide guidance to the technicians or other users.  The instrument does fairly well for your nuclides.


At times, we have used a simple field beta shield to separate Sr90-Y90 from Cs-137 (Al from soda can wall attenuates Cs-137 by 50%).  This method can be extended to separate the nuclide mix in the field.  


I have some concern about the thin sidewall of the Ion Sense (250 mg/cm2).  If you have hard beta, (such as Sr90) the thin sidewall of the Ion Sense would allow beta in during the “closed” measurement when the beta slide is closed.  I published a paper or two on this issue for the predecessor (RO-2).  This would have more of an impact for area sources rather than point sources.


Joe Shonka   






Sent from Windows Mail





From: Olsson Mattias :MSO
Sent: ‎Wednesday‎, ‎May‎ ‎6‎, ‎2015 ‎11‎:‎56‎ ‎AM
To: The International Radiation Protection (Health Physics) Mailing List





Dear all,

I got a question that is a bit outside of my field since I'm not as much of an RP person as many others here (rather a radiochemist). The question was which type of beta source is most suitable to calibrate a Smart Ion beta dose rate meter. The alternatives are Sr-90/Y-90, Kr-85 and Pm-147. I realize that the nuclides vary in beta Emax more or less from high to low in the order written (500 keV+2.3 MeV; 700 keV; 200 keV).

The instrument will be used in an environment with mostly Co-60 but also some Co-58 and Ni-63 as beta contributors. Most of the beta radiation will then be about Emax 300 keV from Co-60, but Co-58 will contribute with some 1,3 MeV and Ni-63 with some 70 keV.

I would guess myself that Sr/Y would be the most appropriate to make sure that the dose rate response is not underestimated. I have no feeling of how much of a difference it would make, though. Any advice?

All the best,
Mattias Olsson, Sweden
_______________________________________________
You are currently subscribed to the RadSafe mailing list

Before posting a message to RadSafe be sure to have read and understood the RadSafe rules. These can be found at: http://health.phys.iit.edu/radsaferules.html

For information on how to subscribe or unsubscribe and other settings visit: http://health.phys.iit.edu