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:
estimated. • Well defined and justified screening criteria are used for the elimination of flood scenarios. RG 1.247, Page 27 C.1.3.9 Internal Fire 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 fire NLWR PRA that addresses all radiological sources, all POSs, and all levels of PRA analysis. The objective for each technical hazard group-specific PRA analysis element is briefly described, and the characteristics and attributes needed to achieve the objective are given below. The internal fire-specific PRA analysis elements are evaluated for all POSs and may have different characteristics for different POSs. The internal fire-specific PRA analysis elements for an internal fire PRA at all phases leading up to and including the as-built, as-operated plant are as follows: • internal fire plant boundary definition and partitioning, • internal fire initiating event and equipment selection, • internal fire cable selection and location, • internal fire qualitative screening, • internal fire plant response model, • internal fire scenario selection and analysis, • internal fire ignition frequency, • internal fire circuit failure analysis, • internal fire HRA, and • internal fire event sequence quantification. Internal fire PRA models for at-power and LPSD types of POSs are similar in many ways, differing primarily in the relevant operating experience and plant configuration. The internal fire PRA model for a particular POS also relies on the corresponding internal events POS PRA model, which is modified to reflect fire-induced failure of equipment causing initiating events, to reflect fire-induced failure of equipment used to respond to initiating events, and to reflect the impact of fire on operator actions. Because of its dependence on the internal events model, the