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:
d in the NRC staff’s safety review of DBAs (see NURG-0800, Chapter 15). The applicant should provide the following information to support the NRC staff’s environmental review of DBAs: • list and description of each DBA being considered as having a potential for releases to the environment; the DBAs should be consistent with the DBAs listed in regulations (e.g., those described in RG 1.183, “Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Plants” (Ref. 73), in the DCD, and analyzed in the safety analysis report • time-dependent isotopic activities (i.e., the source term) released to the environment for each DBA • estimated doses for each DBA using realistic (i.e., 50th percentile) atmospheric dispersion factors (χ/Q values) for the site (see Chapter 2 of this RG), taking into account the following: – for the EAB, the dose should be calculated for a 2-hour period – for the low-population zone (LPZ), the dose should be calculated for the course of the accident (i.e., 30 days, composed of four time periods). • comparison of the DBA doses with review criteria given in regulations (i.e., 10 CFR 52.79(a)(1), and 10 CFR 100.21, “Non-Seismic Siting Criteria”) and standard review plans (i.e., SRP criteria, Table 1 in SRP Section 15.0.3 of NUREG-0800, Ref. 57). • conclusion on the degree of environmental impact caused by postulated DBAs at this site 5.11.2 Severe Accidents The applicant should evaluate the mean environmental (i.e., individual, population, economic, and contaminated land area) probability-weighted consequences, or risks, of severe accidents involving radioactive material within a 50 mi radius of the site. Severe accidents involve multiple failures of equipment or function and, therefore, the likelihood of occurrence is lower for severe accidents than for DBAs; however the consequences of such accidents may be higher. The risks for specific severe accident types are defined as the product of