Diablo Canyon Power Plant Avila Beach
Diablo Canyon Power Plant Avila Beach

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.

Scope | Solutions

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 Contact(s)