Document: NUREG-0800
Document ID: 4e1c316a-99c2-4fd3-9d9b-323791bd85f8
Document Type: srp
Title: SHORT-TERM ATMOSPHERIC DISPERSION ESTIMATES FOR ACCIDENT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070730398.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.3.4
CFR Part: 
CFR Title: 

Content:
ing the dispersion algorithms discussed in Regulatory Guide 1.145 for evaluating the consequences of airborne radiological releases to the EAB and LPZ. Use of the ARCON96 computer code (Ref. 18) is an acceptable approach for implementing some of the Regulatory Guide 1.194 criteria for evaluating the consequences of airborne radiological releases to the control room. In addition, use of the EXTRAN module (Ref. 19) of the HABIT computer code (Refs. 20-21) under certain circumstances (e.g., neutrally buoyant releases) is an acceptable approach for determining χ/Q values for evaluating the consequences of airborne hazardous releases to the control room. 2.3.4-8 Revision 3 - March 2007 The applicant’s use of dispersion models is reviewed for suitability to release characteristics, plant configuration, plume density, meteorological conditions, and site topography. The accidents and release characteristics to be considered are obtained from the reviews of safety analysis report (SAR) Chapter 2.2.1-2.2.2 and 2.2.3 for airborne hazardous material releases and Chapter 15 for radiological releases. When the Gaussian assumptions are not applicable (e.g., dense or buoyant hazardous material releases), other models and techniques used to make estimates are identified and evaluated. Each release should be characterized as either an elevated point source or a ground-level source. Generally the release is considered to be elevated if the release point is at least two-and-one-half times as high as nearby solid structures. Additional guidance on the criteria for classifying releases as either ground or elevated, which applies to both site boundary χ/Q calculations and control room χ/Q calculations, is provided in Position 3.2.2 of Regulatory Guide 1.194. Turbulent mixing of the effluent into the wake of plant structures is usually allowed for ground-level releases. Dispersion models used for radiological control room χ/Q estimates will be compared against ARCON96, which is