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Comparing Site-specific Seismic Hazard Analyses with the National Seismic Hazard Model for the Central and Eastern U.S.

Description: 

There are ongoing discussions on whether the site-specific hazard of the new generation of nuclear reactors can be evaluated and licensed through a scaled-back effort using the USGS National Seismic Hazard Model (NSHM). The objective of this analysis is to explore the feasibility of that idea. We have performed site-specific probabilistic seismic hazard analyses (PSHA) and site response analyses for 16 proposed and existing critical and important facilities distributed throughout the central and eastern U.S. (CEUS) including LNGs, bridges, mine tailing facilities, power plants, and petroleum and chemical storage sites. For each site, we have compared our site-specific results with the 2023 NSHM to understand potential differences. The inputs into the hard rock PSHA include the 2012 EPRI/DOE/NRC CEUS seismic source characterization model and the NGA-East ground motion models. To adjust the hard rock hazard to foundation/ground surface level, we performed 1D equivalent-linear site response analysis using a stochastic point-source model and random vibration theory. This approach has been used for most of the nuclear power plants in the CEUS.

The hard rock site-specific PGA and 1.0 sec SA hazard is about 33% lower on average (range of 4 to 83%) than the 2023 NSHM when the hazard is controlled by the gridded seismicity due to differences in the gridding parameters (CEUS-SSC versus NSHM). The CEUS-SSC parameters are defined for site-specific use. For sites near Quaternary faults e.g., New Madrid, Charleston, or Meers fault systems, the site-specific hard rock hazard is generally within 20% of the NSHM. The differences at the ground surface/foundation level can be even more significant due to the differences between the site-specific site response analyses and the USGS use of generic amplification factors. These differences are frequency-dependent and can range up to a factor of two with no systematic bias. Differences between a site-specific approach to site effects and generic amplification factors are to be expected as the goals of the NSHM for building design are different than those for a critical facility.

Session: Advancing Seismic Hazard Models [Poster]

Type: Poster

Date: 4/17/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Ivan

Student Presenter: No

Invited Presentation: 

Poster Number: 60

Authors