[ RadSafe ] RE: Airborne Monitoring for Cl-39

[Larry Addis]

Way back, if I remember correctly, think we used to stack charcoal 
cartridges and do gamma spec on the successive cartridges to determine 
filter efficiency.

LA, RSO
Clemson U.
----- Original Message ----- 
From: "Demopoulos, Paul" <pdemopoulos at af.umaryland.edu>
To: "Tracy, James W." <james.tracy at nist.gov>; <radsafe at radlab.nl>
Sent: Tuesday, November 17, 2009 11:54 AM
Subject: [ RadSafe ] RE: Airborne Monitoring for Cl-39


Dear Jim,

>From what you are saying about the irradiation, Argon will produce Cl39 by 
>the reaction A40(γ,p)Cl39. From an old reference off the internet: "the 
>threshold was found to be 14.2 Mev. The Cl39 activity was found to have two 
>beta-particles of energies 2.96 and 1.65 Mev, and two gamma-rays of 
>energies 1.31 and 0.35 Mev, the low energy gamma-ray having a conversion 
>coefficient of 0.05."

>From this information you could have several options if the Cl-39 in the 
>air is the only radionuclide.

One could be that you can sample the air through a bubbler system similar to 
C-14/H-3 samplers ran at Universities (with dilute NaOH for C-14) and run 
the sample through an LSC. The high energy Betas would be detected with 
about a 100% efficiency.

The modification to the usual C-14/H-3 type system would be for the Chlorine 
gas bubbler you may want to use the following OSHA method or a 0.1% sulfamic 
acid solution for the Chlorine gas:

http://www.osha.gov/dts/sltc/methods/inorganic/id101/id101.html

You could also try by setting up a NaI system to monitor for the gammas or 
if possible a HPGe.

Paul


Paul J Demopoulos
Radiation Safety Officer - EHS
University of Maryland at Baltimore
714 West Lombard Street
Baltimore, MD 21201
Phone: 410-706-6281
Fax: 410-706-1520
email: pdemopoulos at af.umaryland.edu


-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf 
Of Tracy, James W.
Sent: Tuesday, November 17, 2009 10:51 AM
To: radsafe at radlab.nl
Subject: [ RadSafe ] Airborne Monitoring for Cl-39

Hello,

I am looking for information for performing airborne monitoring for Cl-39. 
We are operating an accelerator and plan to irradiate liquid Argon for an 
experiment.  This will result in the production of Cl-39 via gamma 
activation.  I expect some of the Cl-39 to change from liquid to gas and 
become airborne.  We have local ventilation that will exhaust this out of 
the building via a stack.  I want to monitor the stack effluents during this 
operation.

My question is how do I sample this?  Normally, I would sample the stack 
with a filter paper and charcoal cartridge.  But with the chlorine being a 
gas, I'm not sure what collection efficiency I would have.

Thanks,

Jim Tracy
Health Physicist

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