Avila Beach, CA

Diablo Canyon Power Plant


Diablo Canyon Power Plant, in operation since 1985, uses two Westinghouse Pressurized Water Reactor units to produce 18,000 gigawatt-hours of electricity. PG&E retained SGH to support the re-evaluation of their Long Term Seismic Program (LTSP) for Diablo Canyon, which is situated in a high-seismic hazard zone on the central coast of California. The re-evaluation is driven by PG&E’s commitment to periodically revisit the LTSP and to address the U.S. Nuclear Regulatory Commission’s industry-wide request for information in response to the 2011 Fukushima accident.

The re-evaluation of the LTSP includes updates to the seismic hazard analysis and the seismic probabilistic risk assessment. SGH supported the re-evaluation by updating the seismic fragilities of selected structures, systems, and components (SSCs). We developed new three-dimensional models, performed seismic walkdowns, analyzed seismic response with probabilistic soil-structure interaction (SSI), and performed seismic fragility evaluations.

Highlights of our work for this project include the following:

  • Seismic fragility evaluation of the Turbine Building using probabilistic nonlinear dynamic analysis
  • Development of detailed three-dimensional finite element models of the power block structures for seismic response analysis
  • Probabilistic SSI response analysis of the major Diablo Canyon structures to the new seismic hazard
  • Coordination of seismic walkdowns to support the fragility evaluation and the post-Fukushima NTTF 2.3 recommendations
  • Re-evaluation of seismic fragilities of risk significant SSCs
  • Seismic evaluation of additional SSCs to address post-Fukushima NTTF 2.1 recommendations

Project Summary

Repair & Rehabilitation
Structures | Advanced Analysis | Performance & Code Consulting
Pacific Gas and Electric Company (PG&E)
Specialized Capabilities
Seismic Engineering | Nuclear | Risk & Resilience Assessment

Key team members

Gregory Hardy
Gregory Hardy
Senior Principal