Document: NUREG-0800
Document ID: ac43f632-9db1-4857-9f56-bfba45965456
Document Type: srp
Title: * These are modifications to a plant’s design, operations, or other activities that require NRC approval. These modifica
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0232/ML023250195.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19
CFR Part: 
CFR Title: 

Content:
odes and all initiator types using PRA. • The licensee demonstrates that the application does not unacceptably degrade plant capability and does not introduce risk vulnerabilities or remove elements of the plant SRP 19-15 response capability from programmatic activities aimed at ensuring satisfactory safety performance for plant modes and initiator types not included in the PRA. • If the proposed change impacts unanalyzed plant modes or initiator types, the licensee demonstrates that a bounding analysis of the change in plant risk from the application (e.g., by qualitative arguments, or by use of sensitivity studies) meets guidelines that are equivalent to the acceptance guidelines specified in Section 2.2.4 of Regulatory Guide 1.174. III.2.2.3 Level of Detail The level of detail in a PRA required to support an application should be such that the proposed changes to the plant can be adequately characterized in the PRA model elements, as discussed in Section III.2.2.1 of this SRP chapter. In addition, the PRA should be detailed enough to account for important system and operator dependencies (functional, operational, and procedural), especially for those components affected by the application. A review of the licensee's failure modes and effects analysis and a review of plant operating and emergency procedures will be useful for this purpose. The usefulness of PRA results in risk-informed regulation is dependent on the level of resolution of the modeled SSCs. A component-level resolution provides insights at the component level. However, if a PRA is performed at a system or train level, the insights of the PRA will be limited to that level unless it can be demonstrated that component-level insights can be bounded by, or deduced from, system- or train-level effects. The direct application of PRA results will therefore be limited to those SSCs that are explicitly modeled as part of the PRA basic events. Insights for SSCs that are implicitly modeled (e.g., screened