Document: NRC Regulatory Guide
Document ID: 22ccfd5e-c5d8-4615-a02c-32369aa9f533
Document Type: regulatory_guide
Title: Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1930/ML19308B636.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.200
CFR Part: 
CFR Title: 

Content:
alue. Table 2 provides a summary of characteristics and attributes needed for the technical elements for a Level 1 PRA for internal events. The characteristics and attributes are provided for at-power conditions. Table 2. Summary of Technical Characteristics and Attributes of a Level 1, Internal Events PRA for the At-Power Operating Mode Element Technical Characteristics and Attributes Initiating Event Analysis • Sufficiently detailed identification and characterization of initiating events • Grouping of individual events according to plant response and mitigating requirements • Proper screening of any individual or grouped initiating events Note: It is recognized that for those new reactor designs with substantially lower risk profiles (e.g., internal events CDF below 10-6/year) that the quantitative screening value may need to be adjusted according to the corresponding baseline risk value. Success Criteria Analysis • Based on best-estimate engineering analyses applicable to the actual plant design and operation, as available • Codes developed in sufficient detail to: – analyze the phenomena of interest – be applicable in the pressure, temperature, and flow range of interest Accident Sequence Development Analysis • Defined in terms of hardware, operator action, and timing requirements and desired end states (e.g., core damage or plant damage states) • Includes necessary and sufficient equipment (safety and non-safety) reasonably expected to be used to mitigate initiators • Includes functional, phenomenological, and operational dependencies and interfaces Systems Analysis Models developed in sufficient detail to achieve the following purposes: • Reflect the as-designed, as-built and as-operated plant (as applicable) including how it has performed during the plant history for operating plants • Reflect the success criteria for the systems to mitigate each identified accident sequence • Capture impact of dependencies, including support