Regulatory Use of the ISC3 Model for Dose Assessment

[Ebrahim_Esmaili@parsons.com]

     On 2/12/98 Daniel Chen Wrote:
     
     "We have project to determine the critical group affected by our 
     research reactor operation. The modeling domain is relative small and 
     complex in geometry......Now we are seeking the regulatory base to 
     support our decision to use ISC3"
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     The ISC3 is probably the only model that can simulate the aerodynamic 
     downwash effect of nearby buildings/structures on a point source. You 
     need to use EPA BPIPE model to generate the crosswind dimensions & 
     heights of the affected bldgs.  However, ISC3 is not recommended if 
     the receptors (i.e. bldg air intakes, platforms, etc.) of interest are 
     within the cavity region of the stack bldg (which extends to about 3 
     times the lesser of the height or projected width of the bldg).  You 
     may use EPA SCREEN model for receptors within the cavity (SCREEN can 
     only model a single bldg). The nuclear decay can be ignored if plume 
     travel time is much less than decay time (which usually is the case). 
     
     For complex geometry, 3-D fluid flow modeling for pollutant transport, 
     tracer gas experiments, or wind tunnel modeling are among other 
     options. If you have monitoring data, you may develop a predictive 
     tool that reasonably fits existing data and estimates airborne 
     concentrations.  We're in the process of developing a semi- empirical 
     model (Gaussian dispersion plus statistical analysis) that uses 
     existing radon monitoring data to predict on- and off-site airborne 
     concentrations for different release scenarios.  If you are 
     interested, I'll send you some info when I'm done.
     
     Ebrahim Esmaili, Ph.D.
     Parsons Infrastructure & Technology Group, Inc.
     ebrahim_esmaili@parsons.com