New Analyses Confirm Diablo Canyon Safe, PG&E Reports
"These updated findings are the culmination of years of study and analysis, and further confirm the safety of the plant's design," said Ed Halpin, PG&E's senior vice president and chief nuclear officer.
New analyses required by the Nuclear Regulatory Commission "re-confirm" that Pacific Gas and Electric Company's Diablo Canyon Power Plant can safely withstand extreme natural events, including potential earthquakes, tsunamis, and flooding, the utility announced March 9. These hazard re-evaluations will be submitted to NRC this week for independent review, according to PG&E's announcement, which said the regulator called on all U.S. commercial nuclear power plants to perform them after the 2011 crisis at the Fukushima Daiichi nuclear plant in Japan.
"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," said Ed Halpin, PG&E's senior vice president and chief nuclear officer.
PG&E's announcement said these analyses represent "a more extensive evaluation of the seismic hazard than previously performed. Prior evaluations determined the ground shaking from an earthquake on a particular fault in the region, based on historical records and geological evidence, and then compared this information against structures, systems and components at the facility to ensure they could withstand seismic ground shaking. Using the NRC's Senior Seismic Hazard Analysis Committee process, independent seismic experts publically re-evaluated existing and new seismic information, including data acquired during the advanced seismic studies recently performed near Diablo Canyon, to re-evaluate how earthquakes could potentially impact the facility. This process included examining the probability of earthquakes occurring on individual and multiple geologic faults. The result is a more thorough assessment of the seismic hazard, providing additional confirmation that the plant is seismically safe."
"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. 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. In my opinion, the model developed for Diablo Canyon will set the standard for how future earthquake source models are developed," said Bill Lettis, who serves as one the key technical leads for the SSHAC process.
"These important updates provide an in-depth look at the seismic, tsunami, and flooding hazards in our region, and most importantly, demonstrate the plant's design is safe. Our work in these areas, however, will never cease. Our commitment to safe operations and protecting public health and safety will continue to be reflected in our ongoing study and evaluation of the areas. Our customers expect no less," Halpin said.