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

[Busby, Chris]

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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