Re: Air Sampling

[Franz Schoenhofer <schoenho@via.at>]

At 15:25 13.01.1999 -0600, you wrote:
>Radsafers
>
>Tim Knapp, speaking of air sampling for radioiodine with successive
charcoal filters, wrote:  Over the past year I have run into 3 occasions
where the counts in the second filter are almost equal to those of the first.
>
>In a similar vein, does anyone have experience that they could share
concerning observed partitioning between a particulate pre-filter and a
silver zeolite or charcoal filter when sampling for radioiodine, or even a
three-part filter train with a pre-filter, silver zeolite, and charcoal?
>
>Thanks,
>Mike McCarty
>Health Physicist/Emergency Planner
>mccartmj@state.mi.us
>
--------------------------

Mike,

You did not mention, where you took the samples from - from a nuclear power
stations off-gas stack (which kind of nuclear reactor?), in the vicinity,
far a way from a nuclear power station etc. 

"Iodine" is emitted in different forms from nuclear power plants - iodide,
usually associated with aerosols (filtered by particulate filters),
molecular iodine (I2), which is gaseous and will deposit on a silver loaded
zeolithe filter or a charcoal filter (probably with different efficiency),
methyl iodide and other organic iodine compounds which behave similar to
molecular iodine. Depending on the ratio of the various chemical species a
behaviour like the one you described is possible. Different types of
nuclear reactors emit different ratios of the aforementioned compounds.
Temperature, humidity etc. play also a role. 

Regards, 

Franz


Franz Schoenhofer
Habicherg. 31/7
A-1160 Vienna
Austria
Tel.: +43-1-495 53 08
Fax.: same number
mobile phone: +43-664-338 0 333
e-mail: schoenho@via.at

Office:
Hofrat Dr. Franz Schönhofer
Federal Institute for Food Control and Research
Department of Radiochemistry
Kinderspitalg. 15
A-1095 Vienna
Austria
Tel.: +43-1-40 491 520
Fax.: +43-1-40 491 540
e-mail: schoenhofer@baluf.via.at
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