[ RadSafe ] Skyshine measurements

[JOHN.RICH at sargentlundy.com]

As a first approximation it doesn't seem like it should be a large effect. 
 The N-16 gammas scatter off electrons so the density of electrons is what 
matters.  Clouds have small water droplets which have a higher electron 
density than air.  But, is there enough water in the clouds to make a real 
difference? (I don't have a clue on this one.  Perhaps a meteorologist 
could calculate the difference in electron density to see if it makes 
enough difference to matter).   Also it depends on the height of the cloud 
cover.  If the clouds are at 1000 meters it might affect the skyshine.  If 
the clouds are at 10,000 meters, it probably won't.   Calculating the 
effect of various cloud covers would be a good master's thesis

Anybody else have any ideas. 

 --jmr

John Rich
312-269-3768



From:   "Olsson Mattias :MSO" <mso at forsmark.vattenfall.se>
To:     "The International Radiation Protection \(Health Physics\) 
MailingList" <radsafe at health.phys.iit.edu>
Date:   03/06/2013 09:34 AM
Subject:        [ RadSafe ] Skyshine measurements
Sent by:        radsafe-bounces at health.phys.iit.edu



Hi all,

One BWR plant is to do a power uprate to 120% of the original effect.
During the testing period there will be dose rate measurements in
selected places around  the plant to observe changes in skyshine from
the steam lines in the turbine building. In the documentation it says
that the measurements should be done during weather with "low clouds".
This is supposedly because low clouds will give you a conservative
measurement. There is no source given and I don't have the necessary
software to make a model of it. So what I want to ask is if any of you
could say if it is obviously conservative to measure skyshine with low
clouds (compared to high clouds or sunny weather) and if there is some
standard practice for skyshine measurements around nuclear plants. Being
a humble chemist, it's not obvious to me, although it seems reasonable
that clouds could cause more scattering.

All the best,

Mattias Olsson
Forsmark, Sweden 

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