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:
t and use of a quantitative PRA requires a systematic and integrated evaluation. Development of a technically defensible quantitative PRA also requires sufficient and structured documentation to allow investigations of all aspects of the evaluation. To meet the requirements of the proposed 10 CFR 50.69 for categorization of SSCs, licensees must use risk evaluations and insights that cover the full spectrum of potential events (i.e., internal and external initiating events) and the range of plant 5 operating modes (i.e., full power, low power, and shutdown operations). The NRC staff believes that current state-of-the-art PRA methods are available to quantitatively address the full spectrum of potential events and the full range of plant operating modes for this type of application, and thus it is desirable for licensees to use such broad-scope PRAs. However, Draft Revision C of NEI 00-04 allows the use of non-PRA type evaluations (e.g., FIVE, seismic margins analysis, NUMARC 91-06), when PRAs have not been performed. It should be recognized that the degree of relief that can be expected will be commensurate with the assurance provided by the evaluation. 6. Quality Attributes of Analyses Implementing Draft Revision C of NEI 00-04 Draft Revision C of NEI 00-04 states in Section 3.3 that the Option 2 categorization process is a Grade 3 application per the NEI 00-02 peer review process. Through NEI 00-02, as amended to incorporate NRC comments provided in the NRC letter to NEI, dated April 2, 2002, there is a mechanism for licensees to determine if their internal events PRA meets the attributes required for this application. A possible future alternative to NEI 00-02 may be the ASME Standard for Probabilistic Risk Assessment for Nuclear Power Plant Applications, if and when it is endorsed by the NRC staff. The NRC endorsement of this ASME standard is currently under development and will be published as a regulatory guide. These documents cover internal events at full