I-131 air sampling: filter vs. cartridge

Submitted by Anonymous on Mon, 2011-03-28 23:50

I see the reference to cartridge v. particulate filter on the System B page (i.e., actual activity in the air might be x10 higher than the HEPA filter data shows). There is a similar x10 filter vs. cartridge ratio in the EPA data.

Could you comment whether the air data for iodine needs to be corrected up or has this correction already been calibrated out?

Thanks.

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We have been assuming 100%

Submitted by bandstra on Tue, 2011-03-29 00:13.

We have been assuming 100% filter efficiency, as noted in the caveat posted on 3/24 (2:40pm). Could you please point us to a reference for the factor of 10 used by the EPA? We are currently trying to determine that efficiency.

Evaporating water reduces iodine content?

Submitted by Anonymous (not verified) on Tue, 2011-03-29 19:11.

Sorry -- at work all day, did not have a chance to follow up.

http://www.nuc.berkeley.edu/node/2172 already provided the same reference I did (apparent x10 difference for filter vs cartridge).

Along similar lines (volatility of atomic iodine), does your water concentration technique (x5 concentration by distillation) removes some of the iodine. If this has not been considered, I could probably run an estimate. If it has, and it is a minor effect, it would be good to know.

Early on we hypothesized

Submitted by dchivers on Tue, 2011-03-29 20:54.

Early on we hypothesized this effect during the reduction so we ran the same rain water with and without reduction and found, within error, that we had the same number of counts in the peak region. We conclude that within our error bars we are not seeing any iodine volatility.