Document: NRC Regulatory Guide
Document ID: 239cc7c1-f2cb-46cc-945d-8009db28aa6c
Document Type: regulatory_guide
Title: General Site Suitability Criteria for Nuclear Power Stations + HISTORY - HISTORY 12/2023 – DG-4034 , Proposed Revision 4 12/2011 – DG-4021 , Proposed Revision 3 02/1995 – DG-4004, Second Proposed Revision 2 11/1992 – DG-4003, Proposed Revision 2 (Rev. 4)
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML2312/ML23123A090.pdf
Revision Date: 2023-10
Chapter: 
Section ID: RG-4.7
CFR Part: 
CFR Title: 

Content:
e limits are not exceeded. The atmospheric conditions at a site should provide sufficient dispersion of radioactive materials released during a postulated accident to reduce the radiation exposures of individuals at the exclusion area and LPZ boundaries to the values in 10 CFR 50.34, “Contents of applications; technical information;” 10 CFR 52.17, “Contents of applications; technical information;” and 10 CFR 52.79, “Contents of applications; technical information in final safety analysis report.” The atmospheric conditions at a site should also be characterized to appropriately model dispersion of radioactive materials from airborne release of fission products during routine operations and anticipated operational occurrences, to show compliance with the effluent concentration limits of Appendix B to 10 CFR Part 20 and with dose limits for members of the public under 10 CFR 20.1301 and 10 CFR 20.1302. The concentration of radioactive materials in the atmosphere downwind from a release source is determined using an atmospheric dispersion factor known as a χ/Q value or relative concentration factor. It is defined as the airborne concentration χ (in curies per cubic meter) at the downwind location of interest, divided by the rate of release of radioactive materials from the source, Q (in curies per second). A similar term, the atmospheric deposition factor or D/Q value, is used to determine the rate of ground-level deposition at a downwind location of interest. It is defined as the rate of ground-level deposition D (curies per square meter per second) at the downwind location of interest, divided by the rate of release of radioactive materials from the source, Q. The standard practice has been to evaluate χ/Q and D/Q values because they depend only on atmospheric variables, distance from the source, radionuclide chemical and physical characteristics, and whether airborne releases occur from a single plant stack or through multiple building vents or plant