View the SSHAC3 Process Project Plan for Technical Use


This project plan outlines the Central and Eastern United States Seismic Source Characterization for Nuclear Facilities (CEUS-SSC) Project, which will replace the Seismic Hazard Methodology for the Central and Eastern United States, EPRI report NP-4726, July 1986. The objective of the CEUS-SSC project is to develop an up-to-date assessment of probabilistic seismic hazard analysis (PSHA) SSC for CEUS. Input to a PSHA consists of both seismic source and ground motion characterization. These two components are used to calculate probabilistic hazard results (or seismic hazard curves) at a particular site.


Results & Findings

The product of this report is a vetted plan to develop a generic CEUS-SSC model. This model includes consideration of an updated database, full assessment and incorporation of uncertainties, and the range of diverse technical interpretations from the informed scientific community. The SSC model will be widely applicable to the entire CEUS, so this project will use a ground motion model that includes generic variations to allow for a range of representative site conditions (deep soil, shallow soil, hard rock). Hazard and sensitivity calculations will be conducted at six demonstration sites representative of different CEUS hazard environments.


Challenges & Objective(s)

The generic CEUS-SSC model will be of value to readers who are involved in PSHA work, and who wish to use an updated SSC model. This model will be based on a comprehensive and traceable process, in accordance with Senior Seismic Hazard Assessment Committee (SSHAC) guidelines in NUREG/CR-6372, Recommendations for Probabilistic Seismic Hazard Analysis: Guidance on Uncertainty and Use of Experts. The model will be used to assess the present-day composite distribution for seismic sources along with their characterization in the CEUS and uncertainty. In addition, this model will be in a form suitable for use in PSHA evaluations for regulatory activities, such as Early Site Permit (ESP) and Combined Operating License Applications (COLA).


Applications, Values & Use

Development of a generic CEUS seismic hazard model will provide value to members who 1) have submitted an ESP or COLA for Nuclear Regulatory Commission (NRC) review before 2010, 2) will submit an ESP or COLA for NRC review after 2010 and 3) must respond to safety issues resulting from NRC Generic Issue 199 (GI-199) for existing plants. This work replaces a previous study performed approximately 20 years ago. Since that study was completed, substantial work has been done to improve the understanding of seismic sources and their characterization in the CEUS. Thus, a new generic SSC model will provide a consistent, stable basis for computing PSHA for a future time span. Use of a new SSC model will reduce the risk of delays in new plant licensing due to more conservative interpretations in the existing and future literature.


EPRI Perspective

The purpose of this study, jointly sponsored by EPRI and the U.S. Department of Energy (DOE), is to develop a new CEUS-SSC model. The team assembled to accomplish this purpose is comprised of distinguished subject matter experts from industry, government, and academia. The informed scientific community, it is not likely to be repeated for a number of years.



The goal of this report was to present the work plan for developing a generic CEUS-SSC model.The work plan, formulated by a technical integration team, consists of a series of tasks designed to meet the project objectives. This report was reviewed by a participatory peer review panel (PPRP) and sponsor reviewers. Comments from the PPRP are reflected in the report. EPRI held a meeting on May 8, 2008, to facilitate resolution of comments received regarding the project plan. The SSC model is slated for completion in mid-2010.



Seismic Sources
Probabilistic Seismic Hazard Assessment (PSHA)
Seismic Source Characterization (SSC)
Seismic Source Characterization Model
Central and Eastern United States (CEUS)

CEUS-SSC Project Website