Correlation of Seismic Performance in Similar SSCs (Structures, Systems, and Components) (NUREG/CR-7237)

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* Appendix D refers to MATHCAD and PDF attachments with sample calculations.  Those desiring the files with those sample calculations can order the CD by contacting:

Publication Information

Manuscript Completed: March 2015
Date Published: December 2017

Prepared by:
Robert J. Budnitz1, Gregory S. Hardy2, David L. Moore3, and M. K. Ravindra4

1 Lawrence Berkeley National Laboratory
Energy Geosciences Division
University of California, Berkeley, CA 94720

2 Simpson Gumpertz & Heger
4695 MacArthur Court
Newport Beach, CA 92660

3 David L. Moore Consulting
9721 SE 43rd Street
Mercer Island, WA 98040

4 MK Ravindra Consulting
15 Fortuna West
Irvine, CA 92620

Jose Pires, NRC Project Manager

Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington DC 20555-0001

Availability Notice


This report describes an improved and more refined and insightful methodology for analysis of correlation or dependency as part of the overall methodology of seismic PRA (SPRA) for nuclear power plants. The focus is on those classes of structures, systems, or components (SSCs) for which the way correlations or dependencies are analyzed in SPRA makes an important difference to the SPRA results or to the safety insights derived from those results. The fundamental question is what is the joint probability of seismic-caused failure of two or more SSCs conditional on the occurrence of an earthquake of a given size, and how and why that joint probability may be different from the situation in which those failures are essentially independent. An improved and more refined and insightful methodology is identified and presented, its rationale is explained, and examples are provided to demonstrate how the methodology can be used in practice.

Page Last Reviewed/Updated Wednesday, March 24, 2021