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:
estimated using assumptions that are as realistic as practicable. Because the events under consideration are of such low probability, valid statistical data are often not available to permit accurate quantitative calculation of probabilities. Accordingly, a conservative calculation showing that the annual frequency of occurrence of doses above the value specified in 10 CFR 50.34(a)(1), 10 CFR 52.17(a)(1), and 10 CFR 52.79 (a)(1) is approximately 1x10-6 per year is acceptable if, through reasonable qualitative arguments, the realistic frequency can be shown to be lower. Because it is difficult to assign precise numerical values to the frequency of occurrence of the relevant types of hazards, judgment should be used as to whether each event presents an acceptable overall risk. NUREG-0800, section 2.2.3, describes the staff’s evaluation procedures and criteria for potential accidents in the site vicinity. The hazards described there should be evaluated in detail to determine site suitability with respect to potential accidents at nearby industrial and military facilities, and transportation routes. Design-basis events have been appropriately considered if analyses have been performed of the effects of such events on the safety-related features of a proposed nuclear station, and if appropriate measures (e.g., hardening, fire protection) have been proposed to mitigate the consequences of such events, if necessary. If there are unusual site characteristics, plant design features, or other factors, then different assumptions may be made on a case-by-case basis. In such cases, analyses should conform to the recommendations in RG 1.183 for alternative radiological source terms for evaluating design-basis accidents. RG 1.78 describes assumptions acceptable to the NRC staff for use in assessing the habitability of the control room during and after a postulated external release of hazardous chemicals. It also describes criteria acceptable to the staff for the protection of