[ RadSafe ] Blogger with radiation measurement device claims Los Angeles gets radioactive rain
SAFarber at optonline.net
Fri Apr 6 11:27:37 CDT 2012
A bit of technical info is provided below for the anti-nuclear activists who we know are trolling radsafe to improve their understanding of radiation matters :-) :
When I first saw the note below posted by Roger Helbig about an increase of radioactivity recently reported in precipitation in LA, I immediately thought of the variation in Be-7 which comes to earth mainly in the Spring via exchange from the stratosphere to the troposphere. Be-7 levels in the lower atmosphere can easily vary by a factor of 2x to 10x from late spring and summer, from winter levels. The main mode of Be-7 leaving the lower atmosphere is precipitation vs. dry deposition. A google search, and 20 seconds, yielded the following about Be-7 [ Beryllium-7 ]. [See reference below, by Sugihara]
We don't know how this "anti-nuclear" activist measured the claimed increase in radioactivity in precipitation, and I doubt they were capable of doing proper gamma isotopic analyses to distinguish between Be-7 and potentially other gamma activity in precipitation. It is most likely that they were doing gross gamma measurements, at best. Be-7 decays by pure electron capture and can only be detected through the 0.477 MeV gamma-ray emitted - 12% of the time). We know there have been some unusual levels of cosmic ray acitivity recently which would have caused significant increases in Be-7 in the stratosphere. Now, with the turnover of the atmosphere in spring to summer, this increased level of Be-7 will be seen at ground level since precipitation is the main way Be-7 aerosols leave the lower atmosphere. Be-7 particulates are often seen, as the only gamma activity, in gamma analyses of air filters now that there is no activity in surface air from other nuclear activities.
Variation of Atmospheric 7Be and 210Pb Depositions at Fukuoka, Japan,
Sugihara, et. Al.
FROM THE ABOVE: Beryllium-7 (half-life 53.29 d) is one of the radionuclide produced by spallation reactions of cosmic
rays with light atmospheric nuclei, such as carbon, nitrogen and oxygen. Approximately 70% of 7Be produced in
the stratosphere, with the remaining 30% produced in the troposphere. A residence time is estimated about a year
in the stratosphere, and about six weeks in the troposphere. Most of the 7Be that are produced in the stratosphere
don’t reach the troposphere except during spring when seasonal thinning of the tropopause takes place at
midlatitudes, resulting in air exchange between stratosphere and troposphere. 7Be rapidly associates primarily
with submicron-sized aerosol particles. Gravitational settling and precipitation processes largely accomplish
transfer to the earth’s surface. 7Be associated with aerosol particles is an ideal tool with which to study
atmospheric transport processes.
Stewart Farber, MSPH
Farber Medical Solutions, LLC
Bridgeport, CT 06604
SAFarber at optonline.net
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of bobcherry at satx.rr.com
Sent: Friday, April 06, 2012 10:52 AM
To: The International Radiation Protection (Health Physics) Mailing List
Cc: Roger Helbig
Subject: Re: [ RadSafe ] Blogger with radiation measurement device claims Los Angeles gets radioactive rain
When I saw this article yesterday, I thought about posting a comment on his web site asking whether he had properly accounted for radon progeny. I decided not to because he obviously has already made up his mind.
---- Roger Helbig <rwhelbig at gmail.com> wrote:
> New post on nuclear-news
> Los Angeles gets radioactive rain
> by Christina MacPherson, Australian anti-nuclear activist who receives
> donations under the charitable exemption of Front Line Film Foundation
> (includes video) Radioactive Rain Detected in Los Angeles, LA Weekly ,
> 5 April 12, Rain and mist that fell in Los Angeles last weekend was
> five times as radioactive as normal, environmental journalist and LA
> Weekly contributor Michael Collins reported on his web site this week.
> Collins tests samples with his own equipment and says that, on
> Saturday, he measured the highest proportion of radioactivity in the
> local environment since he began monitoring the local fallout from the
> Japanese Fukushima nuclear power plant disaster in March of 2011:
> One misty rain sample collected in downtown Santa Monica was over five
> times normal background radiation, the highest level in Los Angeles
> Basin rain since this reporter began sampling and testing different
> media March 15, 2011, four days after the Fukushima Daiichi meltdowns begin.
> He called the findings "shocking" and said his readings would qualify
> that sample as a hazardous material under the California Highway
> Patrol's protocols.
> Even background radiation Saturday night, which had apparently
> diminished significantly since his earlier sample, was 30 percent
> "hotter" than normal, he says. Time for a good umbrella? Read more here.
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