[ RadSafe ] Skyshine measurements

[JPreisig at aol.com]

Dear Radsafe,
 
     Skyshine is discussed in Patterson and Thomas's  Accelerator Health 
Physics and/or
Cossairt's Course notes on Accelerator Health Physics.
 
     Guess other Radsafers have commented on the  meteorology of skyshine 
measurements.
 
     For field measurements of Skyshine, perhaps use a  portable MCA 
counting system with NaI or Ge
detector, or whatever you have available.  If there is a neutron  
component, you can make flux density
spectra measurements with a set of Bonner Spheres and one or two LiI(Eu)  
detectors.  Hopefully
reactor neutron and/or photon/gamma signals are not highly variable in  
time, so you don't need
7 LiI(Eu) detectors, just one or two.  Bonner Spheres (polyethylene)  are 
fairly expensive.  You can analyze Bonner data with BON4/BON5,  LOUHI???, 
MAXED??? or other unfolding codes available from 
RSICC (Radiation Shielding Information Center at ORNL).  If you end up  
using an Anderson-Braun
detector only, maybe you would want to make a set of measurements as a  
function of angle (measured 
from horizontal) pointed up towards the sky.
 
    Like the other guy said, you can mathematically model  the problem 
using MCNP (Monte Carlo
Neutral Particle Program).  MCNPX can be used for high energy  
neutron/hadron transport, but that may
not be necessary in this case.
 
    Have fun.    Regards,  Joseph R.  (Joe) Preisig
 
 
 
 
 
In a message dated 3/6/2013 10:34:03 A.M. Eastern Standard Time,  
mso at forsmark.vattenfall.se writes:

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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