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:
nt for performance shaping factors that are attributable to flooding, and (5) quantify internal flood accident sequence CDF and LERF/LRF. DG-1362, Page 20 Table 4. Summary of Technical Characteristics and Attributes of an Internal Flood PRA for the At-Power Operating Mode Element Technical Characteristics and Attributes Flood Area Partitioning • Flood areas defined based on plant features that can restrict flood • Verification of area definitions through plant walkdowns Flood Source Analysis • Sufficiently detailed identification and characterization of the following: – SSCs located within each area – flood sources and flood mechanisms – type of water release and capacity • Elimination of flood sources and areas uses well-defined and justified screening criteria • Verification of the information through plant walkdowns for as-built plants Flood Scenario Analysis • Identification and evaluation of the following: – flood propagation paths – flood mitigating plant design features (e.g., drains and sumps) and operator actions – the susceptibility of SSCs in each flood area to the different types of floods • Elimination of flood scenarios uses well-defined and justified screening criteria Flood Scenario Delineation and Quantification • Identification and grouping of flood-induced initiating events on the basis of a structured and systematic process • Estimation of flood initiating event frequencies • Modification of the Level 1 internal events PRA to account for flooding effects including uncertainties • Estimation of CDF and LERF/LRF for chosen flood sequences • Elimination of flood scenarios uses well-defined and justified screening criteria Technical Elements for Internal Fire, At-Power PRA This section identifies the technical elements for an internal fire, at-power PRA. The objective for each technical element is briefly described and the characteristics and attributes needed to achieve the objective are provided in Table 5. The