Some of Diablo Canyon’s buildings aren’t earthquake safe? Taxpayers deserve better | Opinion

Devastating images from the recent Turkish quakes of collapsed “non-ductile” concrete buildings with “soft” first floors — similar to those destroyed in our Sylmar and Northridge earthquakes — should be a wake-up call to Californians.

At Diablo Canyon, several key buildings are constructed in the same flawed manner. Assurances from the Nuclear Regulatory Commission that the plant is seismically safe only address whether the reactors or spent fuel pools will release radiation into the environment in an earthquake — not whether the plant can continue operating.

Safety is a necessary, but not sufficient, requirement for Diablo’s continued operation under SB 846. The law was enacted because Gavin Newsom believes running Diablo Canyon may be necessary for grid reliability between 2025 and 2030. But a $1.475 billion investment from state taxpayers merits a seismically resilient plant.

What could go wrong? The Japanese found out before Fukushima when an earthquake struck their largest reactor complex in 2007. There was no radioactive release from the reactors, but the shaking destroyed so much of the infrastructure needed for electric generation that five of seven units were still inoperative when Fukushima shut them all again in 2011.

In 2010, PG&E released a report mandated by former state legislator Sam Blakeslee’s AB 1632 to investigate these “non-safety” systems, structures and components (SSCs) after the California Energy Commission found that “Damage to non-safety related SSCs could pose risks of injury and loss of life to plant workers and occupants but damage would not pose a direct safety hazard to the public; however, it could result in extended outages for repairs lasting weeks or months.”

Outages of less than 120 days were considered acceptable — a far cry from SB 846’s reliability premise.

Evaluating the main generator turbine thrust bearings, the resulting Enercon report declared, “For an earthquake with an acceleration value higher than 0.2 g, the seismic load may exceed the allowable load of the thrust bearings … Thrust bearing failure could result in rotating-to-stationary blade contact and extensive turbine damage, taking one to two years to repair.”

Dr. Norman Abrahamson, one of PG&E’s top geoscientists, told the California Energy Commission that “… at Diablo Canyon we would be concerned with a magnitude say 6.25 earthquake on the Hosgri Fault that might give us .2 or .3 Gs of peak acceleration. Less than half of what our design basis is. But it is the non-safety-related systems that are potentially being damaged—would be damaged by those—and then would put us out of operation, even though all our safety systems performed properly.”

Like the collapsed non-ductile buildings in Turkey, Enercon noted the 6-story Diablo administration building “… is not ductile. Due to this and the tall first story, the first story is both a soft and weak story as defined by the current building code…” And of the simulator training building, “We believe the Simulator Building will most likely have a poorer performance as compared to other steel moment frame buildings of similar vintage.”

Days after the Turkish quake, the Los Angeles Times reported that structural engineer Kit Miyamoto “warned in an interview that the inaction to require retrofits of non-ductile concrete buildings will end up costing lives in California … said Miyamoto, who is also a California seismic safety commissioner and added that his comments were not on behalf of the commission. ‘They need to be retrofitted. Otherwise, you’re going to see some consequences.’”

Taxpayers deserve assurance that a seismic event won’t cripple the plant — even if not a millirem of radiation is released. SB 846’s mandated seismic update must include the Enercon study, which omitted any consideration of the Shoreline Fault. A seismic threat to the lives of PG&E employees — most of them SLO County residents — is a human safety issue.

County Supervisor Bruce Gibson, a member of the CPUC’s Independent Peer Review Committee, which has an important seismic oversight role, should remind his colleagues of this concern. Knowingly ignoring the seismic threat to Diablo’s electrical generation capability would nullify the purpose of SB 846 and make a costly mockery of Governor Newsom’s concerns.

David Weisman is the legislative director of the Alliance for Nuclear Responsibility, www.a4nr.org