Re: Gaussian Plumes - how far out can you be?

[Ruth Weiner <rfweine@sandia.gov>]

What we usually do is calculate out to 50 miles (80 km) along the plume 
centerline, unless we know that the air basin is bounded by some geographical 
feature before that (like a mountain range or pass, or foothills, or a body of 
water.  Trinity Consultants in Dallas, TX has done a lot of work on specialized 
air basins (offshore breezes, cliffs, etc.  If they are still around, they 
probably have a web page.

Clearly only my own opinion

Ruth F. Weiner
Transportation Systems Department
Sandia National Laboratories
505-844-4791
fax 505-844-0244
rfweine@sandia.gov

 

______________________________ Reply Separator _________________________________
Subject: Gaussian Plumes - how far out can you be?
Author:  tuckerd@aecl.ca at hubsmtp
Date:    3/10/98 6:31 PM


Radsafers:
     
Some coworkers and I are doing some analysis of accident consequences at 
our site.  One aspect we were looking at is the width of area 
contaminated at or above a given level after the plume has passed over.
     
Has anyone done some analysis (or found a good reference) that indicates 
how far out from centerline the Gaussian plume model is valid?  I 
realize it is only an approximation, and it seems to me that I remember 
one of the problems being "edge effects" - the Gaussian plume never goes 
to 0 but the real plume does.  Is it OK to be several sigma out  - or is 
there some limit.
     
To illustrate the problem - we wanted to identify the area contaminated 
above 1E4 Bq/m^2.  At 500m from the stack in Class B weather, the area 
was 800m wide.  This seems wrong.
     
If anyone has useful info or insight - please advise. 
Thanks
Dave Tucker
     
_____________
     
Dave Tucker, CHP
Health Physicist
Radiation Protection Branch
AECL - Chalk River Labs
Chalk River, Ontario
Canada
KOJ 1JO
Ph (613) 584-8811 X4505
tuckerd@aecl.ca
Tucker