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Re: HOT PARTICLE DDE



Al Tschaeche's comment on EDE and weighting factors, I believe, is
based upon the dose being localized.  However, the original question
of how to calculate EDE is an interesting one if one has a significant
enough of a hot particle.  

I remember in my earlier days at Region I, of several hot particles that
could pose such a problem.  At one facility, they had stored old control
rod drive roller balls in a 5-gal. plastic bucket set upright on top of
the spent fuel rack.  As one would expect (they didn't), the plastic 
became extremely brittle and eventually spilled it's contents one day 
when moved.  A small piece of the plastic floated to the surface with a
Co-60 hot particle on it and was trapped at the skimmer filter.  The dose
rate a the railing of the spent fuel pool (@1 m) was over 1000 mr/hr.

Of more interest to the calculation of EDE was another situation where
a plant, which did periodic job-site surveys for hot particles, discovered
one on the side of a work boot (steam generator job).  The leather boot
prevented a large SDE, but the size of the particle was such that an 
extremety dose was calculated and, I believe, that his/her TLD also 
registered an increased dose due to the particle.

Unfortunately, I can't remember where these incidents took place, but I'm
sure if your contacted Region I (try Ron Nimitz, he likes hot particles),
they might be able to point one in the right direction.

If I was in this situation and the particle was not on an extremity and the
particle was hefty enough, I'd do a MCNP calculation to estimate the DDE,
use QUINCE for the SDE, and hope for the best.

Bob

========================================================================
      _/_/        _/_/      _/_/_/_/   Robert M. Loesch
     _/  _/    _/   _/     _/         US Department of Energy
    _/	  _/  _/      _/   _/         EH-52, GTN, 270CC
   _/	  _/ _/       _/  _/_/_/_/   19901 Germantown Road	
  _/    _/  _/      _/  _/         Germantown, MD  20874-1290
 _/    _/    _/   _/   _/         Tel: 301 903-4443;  Fax: -7773
_/_/_/       _/_/     _/_/_/_/   loesch@spok.eh.doe.gov
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 "The definition of a public health disaster is a catastrophe so large
     that an epidemiologic study can detect it."    David Ozonoff