Document: NRC Regulatory Guide
Document ID: 2459a562-8984-421c-8058-d096dbb9617c
Document Type: regulatory_guide
Title: Guidelines for Categorizing Structures, Systems, and Components in Nuclear Power Plants According to Their Safety Significance
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0314/ML031430373.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.201
CFR Part: 
CFR Title: 

Content:
r qualitative information should be used only when no PRA information exists. The NRC believes that the integrated decision-making process must systematically consider the quantitative and qualitative information available regarding the various modes of operation and initiating events, including: PRA, quantitative risk results and insights; deterministic, traditional engineering factors and insights; and any other pertinent information in the categorization of the SSCs. The fifth guiding principle uses the term “original categorization.” The NRC staff interpretation of this phrase is that it is a reference to the original default categorization of each SSC. The NRC concludes that the original categorization of safety-related SSCs is RISC-1, non-safety-related important-to-safety SSCs are RISC-2, and other non-safety-related SSCs are RISC-4 and that a risk-informed basis must be provided through an integrated decision-making process for any other risk category to be assigned to these SSCs. The sixth guiding principle indicates that the attributes that make SSCs safety-significant should be documented. While the NRC staff agrees that the safety-significant attributes need to be documented, the licensee must also document the justification for SSCs determined to be LSS. In other words, documentation must be available and maintained by the licensee supporting the categorization of every SSC addressed by the licensee under 10 CFR 50.69. 3. Section 1.4 The third paragraph of this section states that the licensee can determine the appropriate set of equipment to recategorize under 10 CFR 50.69. The NRC staff agrees that categorization under 10 CFR 50.69 can be partially implemented by a licensee and the implementation can be phased in over a period of time. However, since the categorization process described in 10 CFR 50.69 and in NEI 00-04 is primarily based on system/structure functions, the categorization process must be implemented on a system/structure-basis; not