Document: NRC Regulatory Guide
Document ID: 8a2332d3-66ca-40af-84e1-507db8b26559
Document Type: regulatory_guide
Title: TRIAL - Acceptability of Probabilistic Risk Assessment Results for Non-Light Water Reactor Risk-Informed Activities
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2123/ML21235A008.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.247
CFR Part: 
CFR Title: 

Content:
lement are as follows: • The estimation of parameters associated with basic event probability models and unavailability events uses generic, design-specific, plant-specific data, or a combination of the three as applicable. Each parameter is clearly defined in terms of the logic model and the model used to evaluate event probability. • Estimation is based on the relevant generic industry and technology- and design-/plant-specific evidence. • Estimation considers the design, environmental, and service conditions of the components in the as-designed, as-to-be-built, and as-to-be-operated plant. • Estimation is consistent with component boundaries. • Estimation includes identification and characterization of the uncertainty. C.1.3.8 Internal Flood Probabilistic Risk Assessment Element This section identifies the hazard group-specific PRA analysis elements, the objectives of those analysis elements, and the characteristics and attributes that are needed for an acceptable internal flood NLWR PRA that addresses all radiological sources, all POSs, and all levels of PRA analysis. The objectives of each internal flood-specific PRA analysis element are briefly described and the characteristics and attributes needed to achieve the objective are provided below. The internal flood-specific PRA analysis elements are evaluated for all POSs and may have different characteristics across POSs. The following internal flood-specific PRA analysis elements are applicable to all phases leading up to and including the as-built, as-operated plant: • internal flood area partitioning, • internal flood source analysis, • internal flood scenario analysis, and • internal flood scenario delineation and quantification. PRA models of internal floods are based on an internal events PRA model, which is modified to include the impact of the identified flood scenarios in terms of causing initiating events and failing equipment used to respond to initiating events. The quantification