[ RadSafe ] Air samples on west coast
sjd at swcp.com
Thu Jun 23 19:12:48 CDT 2011
Chris: Pay attention. Here is some real science.
At 02:15 PM 6/23/2011, you wrote:
>How about some real data?
>UC Berkeley (I refuse to call it "California") has been operating an
>interesting air sampling setup (Air Filtration Experiment B)
>involving a HEPA-filter from a commercial HEPA vacuum system. Turns
>out the filter fits conveniently over one of their high-purity
>germanium (HpGe) gamma spectrometers. Looks to me like they're
>sampling for 24 hours (sample volume ~3,500,000 liters in ~24 hours)
>and then counting for 24 hours. It's not clear how long the filter
>is allowed to decay (to allow radon / thoron daughters to decay
>away) before analysis, but as you can see by looking at the
>individual spectra, radon / thoron daughters and K-40 account for
>the bulk of the activity on these filters, even in late March --
>when the concentration of Fukushima-related radioactive materials
>was at its peak.
>I would note that many of these radon daughters are alpha-emitters
>as well, and would be expected to light up an autoradiograph --
>particularly in a "fresh" automobile air filter.
>Jim Hardeman, Manager
>Environmental Radiation Program
>Environmental Protection Division
>Georgia Department of Natural Resources
>4220 International Parkway, Suite 100
>Atlanta, GA 30354
>Fax: (404) 362-2653
>Personal fax: (404) 521-4485
>E-mail: Jim.Hardeman at dnr.state.ga.us
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