NRC confirms Diablo Canyon safe from natural events

The Nuclear Regulatory Commission (NRC) has re-confirmed the safety standards of Pacific Gas and Electric Company's (PG&E) Diablo Canyon Power Plant and its ability to resist extreme natural events such as earthquakes, tsunamis and flooding.

The NRC has called on all U.S. commercial nuclear power plants to perform such safety provisions following the catastrophic events that occurred in 2011 at the Fukushima Daiichi plant in Japan. Known as hazard re-evaluations, the examination report will be submitted to the agency this week for an independent review.

"Safety is and always will be the top priority for PG&E and Diablo Canyon. That's why seismic, flooding and tsunami safety was at the forefront in the design of the facility. These updated findings are the culmination of years of study and analysis, and further confirm the safety of the plant's design," PG&E's Senior Vice President and Chief Nuclear Officer Ed Halpin said.

Using the NRC's Senior Seismic Hazard Analysis Committee (SSHAC) process, independent seismic experts have re-evaluated the impact of potential earthquakes upon Diablo Canyon, including probability studies of future earthquakes occurring on individual and multiple geologic faults.

"The updated seismic source model for Diablo Canyon incorporates an extensive body of new onshore and offshore data and emerging new scientific concepts to characterize earthquake sources,” SSHAC technical lead Bill Lettis said. "For example, it is the first earthquake model developed for a nuclear site that allows for multi-fault linked ruptures to produce large maximum earthquakes. Through the extensive use of experts in the field of seismic geology and independent peer review, the model was developed to capture the full range of possibilities regarding the location, size and frequency of large magnitude earthquakes in the vicinity of Diablo Canyon."

The NRC will review the re-evaluation and provide PG&E with counsel regarding additional risk evaluations. The agency is asking that other U.S. commercial nuclear power facilities follow suit.

“In my opinion, the model developed for Diablo Canyon will set the standard for how future earthquake source models are developed,” Lettis said.