Document: NRC Regulatory Guide
Document ID: f0baf50b-5bb7-4783-b2f9-9586e09c97e1
Document Type: regulatory_guide
Title: Preparation of Environmental Reports for Nuclear Power Stations + HISTORY - HISTORY 02/2017 – DG-4026 , Proposed Revision 3 09/2014 – Periodic Review of Revision 2 – Revise (Rev. 3)
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML1611/ML16116A068.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.2
CFR Part: 
CFR Title: 

Content:
adiological impacts from normal operations. The applicant should provide meteorological data from at least two consecutive annual cycles (and preferably three or more entire years), including the most recent one-year period, at the time of application submittal. If two years of onsite data are not available at the time the application is submitted, the applicant should provide at least one annual cycle of meteorological data collected onsite with the application. Hourly averages of onsite meteorological parameters should be provided using the recommended electronic data format described in Appendix A of the most current revision of RG 1.23. Sufficient input data should be included to permit independent evaluations and assessments of atmospheric diffusion characteristics and station impacts on the environment as outlined in NUREG-1555. Short-Term Dispersion Estimates The applicant should provide estimates of atmospheric dispersion factors (χ/Q values) at the site exclusion area boundary (EAB) and at the outer boundary of the low-population zone (LPZ) for appropriate time periods using realistic (50th percentile) meteorology. For the EAB, provide the 2-hour 50th percentile χ/Q estimate. For the LPZ, provide the 50th percentile χ/Q estimate for: (1) the 8-hour time period from 0 to 8 hours; (2) the 16-hour period from 8 to 24 hours; (3) the 3-day period from 1 to 4 days; and (4) the 26-day period from 4 to 30 days. Regulatory Guide 1.145, “Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Plants” (Ref. 46), provides guidance for calculating EAB and LPZ atmospheric dispersion factors. The applicant should adequately describe the methods for generating these distributions. Discussion of the effects of topography and nearby bodies of water on short-term dispersion estimates should be provided. The meteorological data used as input to the models should be provided. Long-Term Dispersion Estimates The applicant should