Document: NRC Regulatory Guide
Document ID: cde52d5a-adf9-49be-9d1f-59449dfca895
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:
ould not be identified during the design phase. In addition, the actual current configuration of SSCs in the plant and its confirmation by a detailed physical walkdown of the plant may not be feasible during the design and construction phases. In such cases, assumptions used in seismic fragility analysis (e.g., seismic motion parameters, SSC configuration and design characteristics) should be clearly identified, documented, and tracked to ensure their continued validity across different stages. Such assumptions include those that are identified or included in virtual layouts of the plant. All POSs should be evaluated for differences in the seismic fragility analysis PRA analysis element. It is important that the walkdowns evaluate the differences between the different POSs that impact the fragility analysis. The fragility analysis may need to be modified for LPSD types of POSs to account for changes compared to configurations for at-power types of POSs including but not limited to changes in the location of SSCs, in the radioactive or hazardous material inventory in SSCs, or both, and the addition of temporary features. The characteristics and attributes needed to achieve the objectives of a seismic fragility analysis PRA analysis element are as follows: • The seismic fragility estimate— o is plant-specific, o is realistic, RG 1.247, Page 35 o includes all SSCs that are involved in event sequences for each POS modeled in the seismic PRA systems model, and o describes the basis for screening of high-capacity components. • Seismic fragility evaluation is performed for SSCs for each POS based on the following: o review of plant design documents, o plant configuration, o earthquake experience data, o fragility test data, o generic qualification test data (with justification), o analytical approaches using plant- and location-specific seismic demand information, and o walkdowns or the evaluation of available data and findings of investigations of the plant design