Document: NRC Regulatory Guide
Document ID: 687c884d-2807-4ca3-ac21-69b87c59f4ab
Document Type: regulatory_guide
Title: Use of ARCON Methodology For Calculation Of Accident-Related Offsite Atmospheric Dispersion Factors
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2116/ML21165A005.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.249
CFR Part: 
CFR Title: 

Content:
teorological Measurements,” Version 2.0, issued March 2008 (Ref. 16) (5) Interagency Council for Advancing Meteorological Services, Federal Meteorological Handbook(s) (Ref. 17) e. identification and explanation of any departures between the meteorological monitoring guidance used at each offsite location and the monitoring guidance in RG 1.23 with regard to data quality in general and to potential implications of the dispersion modeling in particular; f. representativeness of the offsite meteorological measurements with respect to the characteristics of the potential accident releases; g. representativeness of the offsite meteorological data to conditions at a given site; and h. for each monitoring location, the period of record to be used and the annual data recoveries for individual model input parameters, as well as the composite recovery of wind speed, wind direction, and atmospheric stability class by year and for the period of record. The values and assumptions associated with the technical issues listed above may be affected for a reactor design deployed in areas with persistent limited atmospheric transport and diffusion conditions. Meteorological monitoring programs that support the modeling analyses, using data acquired either through an alternate approach or a conventional onsite monitoring program, may also be affected by deployment in such areas. These issues include, but may not be limited to, the following: DG-4030, Page 10 a. applicability of the dispersion algorithms (curves or values, or both) in ARCON; b. characteristics of accident releases (e.g., buoyancy, momentum) depending on ambient conditions at the time of release; c. transport and diffusion conditions possibly being significantly different or more restrictive than assumed, including effects caused by variations in the duration of daylight and darkness (e.g., limited inversion depths, extended persistence of various conditions); d. seasonal variation of dispersion and meteorological