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:
as part of developing a source term for use in the siting analyses for non-LWRs is difficult to quantify and is somewhat narrower than the full defense in depth concept referred to elsewhere, such as in guidance from the International Atomic Energy Agency. For the purposes of the siting analysis, an accident is deemed to have occurred (so prevention and control of accident conditions are neglected once the release is established) and the regulatory requirements associated with this guidance are based on radiological consequences at a set boundary given the accident has occurred. NRC regulations, such as 10 CFR 50.47, “Emergency plans,” address other elements of defense in depth by requiring additional assessments and appropriate offsite mitigation capabilities. When considered together, the population density alternative approach described in this appendix, and the other layers of defense in depth provided by compliance with the NRC’s requirements for plant design and programmatic controls (e.g., 10 CFR 50.36), demonstrate adequate defense in depth. Defense in depth is adequate if the overall redundancy and diversity among the plant’s systems and barriers are sufficient, and the siting analysis demonstrates compliance with NRC requirements (e.g., 10 CFR 50.34(a)(1)) to justify a finding of reasonable assurance of adequate protection of public health and safety. Compliance with the NRC’s requirements for emergency preparedness (e.g., 10 CFR 50.47) provides additional defense in depth and reasonable assurance that protective actions can and will be taken to protect public health and safety but does not need to be demonstrated for the siting analysis.