[ RadSafe ] Fukushima - "Spewing" 200 million Bq/hr vs. Soil Release of natural Rn-222 from 2 km^2

[Witold Matysiak]

I agree with Dr. Busby, half lives are key here.
Since 222-Rn is in equilibrium with its predecessors in the chain,
alpha radiation due to 222-Rn, 218-Po etc will stay several log decade
years after all 137-Cs from Fukushima decays away.

W

On Fri, Aug 26, 2011 at 4:08 AM, Busby, Chris <C.Busby at ulster.ac.uk> wrote:
> Half lives
> Chris
>
>
> -----Original Message-----
> From: radsafe-bounces at agni.phys.iit.edu on behalf of Stewart Farber
> Sent: Fri 26/08/2011 01:19
> To: The International Radiation Protection (Health Physics) Mailing List
> Subject: [ RadSafe ] Fukushima - "Spewing" 200 million Bq/hr vs. Soil Release of natural Rn-222 from 2 km^2
>
> Hello all,
> I read an article recently: "Fewer Contaminants Seen Escaping From Japan
> Nuclear Plant", Aug. 18, Global Security Newswire. See:
>           <http://www.globalsecuritynewswire.org/gsn/nw_20110818_8989.php>
>
>
> This recent article  mentioned that the Fukushima complex was now
> releasing 200 million Bq per hour. Most members of the media and public
> don't know a Becquerel from a Pickerel, but 200 million of anything must
> be a very huge amount that poses a major risk. Right??  How do you make
> people understand that 200E6 Bq per se is not the end of the world? Of
> course the isotopes and exposure pathways are vital in assessing
> significance of any activity released, but let's not go there.
>
> 200E6 Bq got me thinking about natural background radiation, and what is
> released from soil to air.    Let me know how the following strikes you as
> a point of comparison.
>
> An average value for Rn-222 gas flux from the earth's surface [due to the
> average concentration of U-238 in soil leading to Rn-222 gas release] is
> roughly 30 milliBq/m^2/sec. Do the math and you'll see that give or take,
> any random 2  km^2 of the earth's surface will release 200 million Bq per
> hour of Rn-222, equal to the total amount of radioactivity being emitted
> recently by the nuclear reactors 1, 2, and 3 at Fukushima as it is brought
> to a cold shutdown. As the Global Security Newswire article noted the
> reactors were "previously hemorrhaging five times that amount" . As we all
> know radiation is not released from a facility -- it is either "spewed" or
> "hemorrhaged".
>
> Five times more than 200 million Bq would be equal to the routine Rn-222
> release by nature from about 10 km^2 - an area 3 km x 3 km - which will
> continue due to natural radioactivity for billions of years given the half
> life of U-238.
>
> Further, based on average wind farm capacity density  [ about 6.5 MWe per
> km^2 ], the 2 km^2 of land currently "spewing" 200 million Bq/hr will
> support the wind generation of only about 13 MW of electricity.
>
> An area of land necessary to site and generate 2,000 MW[e] of wind power
> [an area of 285 km^2  or 11 miles by 11 miles ] would be needed to equal
> the pre-accident combined output of Fukushima 1, 2, and 3. This 285 km^2
> of land to site 2,000 MW[e] of wind generation will release about 32
> billion Bq of  Rn-222 per hour.  32 billion Bq of Rn-222 per hour from
> nature being "spewed" from a windfarm generating 2,000 MWe vs. only about
> 200 million Bq from Fukushima 1, 2, 3. Do we need to evacuate the area
> around any large windfarm?
>
>
> Thoughts on the above comparisons?
>
>
> Stewart Farber, MS Public Health
> SAFarber at optonline.net
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