Document: NRC Regulatory Guide
Document ID: d1045e85-64b0-4a83-8450-067a4fcd130f
Document Type: regulatory_guide
Title: Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Plants + HISTORY –HISTORY 04/2014 – Periodic Review of Revision 1 – Reviewed with issues for future consideration 02/1983 – Reissued 02/1983 to correct page 1.145-7 (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740205.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.145
CFR Part: 
CFR Title: 

Content:
uclear Regulatory Commission, Washington, D.C. 20555, Attention: Docketing and Service Branch. The guides are issued in the following ten broad divisions: 1. Power Reactors 6. Products 2. Research and Test Reactors 7. Transportation 3. Fuels and Materials Facilities 8. Occupational Health 4. Environmental and Siting 9. Antitrust and Financial Review 5. Materials and Plant Protection 10. General Copies of Issued guides may be purchased at the current Government Printing Office price. A subscription service for future guides in spe- cific divisions is available through the Government Printing Office. Information on the subscription service and current GPO prices may be obtained by writing the U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, Attention: Publications Sales Manager. The procedures in this guide also recognize that atmos- pheric dispersion conditions and wind frequencies are usually directionally dependent; that is, certain airflow directions can exhibit substantially more or less favorable diffusion conditions than others, and the wind can trans- port effluents in certain directions more frequently than in others. The procedures also allow evaluations of atmos- pheric dispersion for directionally variable distances such as a noncircular exclusion area boundary. C. REGULATORY POSITION This section identifies acceptable methods for (1) calculating atmospheric relative concentration (xJQ) values, (2) determining X/Q values on a directional basis, (3) deter- mining XJQ values on an overall site basis, and (4) choosing X/Q values to be used in evaluations of the types of events described in Regulatory Guides 1.3 and 1.4. Selection of conservative, less detailed site parameters for the evaluation may be sufficient to establish compliance with regulatory guidelines. 1. CALCULATION OF ATMOSPHERIC RELATIVE CON- CENTRATION (X/Q) VALUES Equations and parameters presented in this section should be used unless unusual siting, meteorological, or terrain