With great interest, I recently read in The Tribune a guest opinion prepared by Ms. Rochelle Becker of the Alliance for Nuclear Responsibility regarding PG&E’s seismic studies for the Diablo Canyon nuclear power plant.
For this study, I oversaw a highly qualified team of consultants and scientists that worked to characterize the earthquake sources in the Diablo Canyon area. In my opinion, the seismic study performed for Diablo Canyon is the most thorough, comprehensive seismic study ever performed for a nuclear facility anywhere in the world.
In the guest opinion, Ms. Becker references my correspondence with Dr. Stephen Thompson and “PG&E’s chief internal seismology engineer.” Unfortunately, Ms. Becker uses this correspondence completely out of context to conjure her own story and to disparage the high-quality science performed by PG&E and its consulting team regarding the seismic hazard at Diablo Canyon. I fully understand that people can have different perspectives on matters concerning Diablo Canyon, and want to share their viewpoints with others. But it is important to ensure those perspectives are rooted in the facts.
Let me explain what actually transpired in the time frame questioned by Ms. Becker from July to September 2014.
As reported repeatedly by The Tribune, during 2014, PG&E was performing two independent studies for Diablo Canyon: one study called the Central Coastal California Seismic Imaging Project, which collected new seismic reflection data to better identify and characterize faults near Diablo Canyon, and a second study called the Senior Seismic Hazard Analysis Committee, which incorporated results from the CCCSIP study into an updated seismic hazard evaluation for submittal to the Nuclear Regulatory Commission.
The two studies had different due dates, with the CCCSIP due in 2014 and the SSHAC in 2015.
Both studies required a substantial amount of time and effort to complete, with expert input and peer review. The email exchange between myself and Dr. Thompson, in which he wrote, “things are going horribly” and “these reports are in bad shape,” simply reflected his opinion to me that in July 2014, the CCCSIP report still required further peer review, analysis and editing. Thus, more time was taken to complete the report, and it was issued in September.
I should point out that all scientific studies undergo thorough, critical technical review. This is one of the founding principles of scientific inquiry.
PG&E and independent seismic experts fulfilled this requirement of critical technical review and adhered to good scientific practice in performing the seismic research, which assured highquality results. As such, the CCCSIP report provided a peer-reviewed scientific basis for identifying and characterizing earthquake fault sources near Diablo Canyon.
Because results from the CCCSIP report were used, in turn, in the SSHAC study (along with many other studies), the concern expressed in my email to a PG&E colleague was that the additional work needed to finalize the CCCSIP report could, in turn, result in a slippage in the SSHAC study schedule, which was due to the NRC in March 2015.
I advised PG&E at the time that perhaps we should alert the NRC to this possibility.
However, both reports were ultimately completed, and the SSHAC study was submitted on time to the NRC.
In terms of earthquake scenarios, the SSHAC study fully characterized and implemented in the seismic hazards analysis all four of the earthquake scenarios identified by Ms. Becker (and many more), including (1) the Hosgri Fault linked to faults up to the Mendocino Triple junction, the Hosgri Fault linked to (2) the Los Osos Fault, (3) the San Luis Bay Fault and (4) the Shoreline Fault. In addition, the SSHAC study explicitly defined an earthquake source beneath the Irish Hills that matches the geometry and size of the 2003 San Simeon Earthquake.
Unfortunately, Ms. Becker and the A4NR chose to deliberately mischaracterize the context of brief email exchanges between colleagues to mislead the public and disparage what is actually the most thorough, comprehensive seismic hazard study ever performed for a nuclear facility anywhere in the world.
Both the CCCSIP and the SSHAC studies fulfilled their objectives of developing the most scientifically sound characterization of faults and earthquake sources in the vicinity of Diablo Canyon, with a high level of confidence that the models developed capture the full range of alternative interpretations in the professional community.