Nuclear risksMore proof needed that PG&E’s Diablo Canyon nuclear plant is safe from earthquakes: NRC

Despite repeated assertions by Pacific Gas & Electric Co. that the Diablo Canyon nuclear plant is safe from earthquakes, the U.S. Nuclear Regulatory Commission (NRC) has ordered PG&E to provide more proof. Friends of the Earth (FOE) says the order confirms concerns that faults surrounding Diablo Canyon are capable of more ground motion than the reactors were built to withstand and that the plant is in violation of its operating license and should be closed immediately.

Yesterday the NRC sent PG&E a letter requiring the utility to conduct further studies to show whether Diablo Canyon — California’s last nuclear plant, on the Pacific coast near San Luis Obispo — is operating within the bounds of its license. According to NRC criteria, nuclear plant operators must conduct further “seismic risk evaluation … if the design basis does not bound reevaluated hazard.”

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See also:

Critics: PG&E downplays quake risk to Diablo Canyon nuclear plant, 16 April 2015

Seismic faults make Diablo Canyon a nuclear catastrophe in waiting: Experts, 26 August 2014

Five U.S. nuclear plants in earthquake zones, 12 April 2011

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FOE notes that in 2011 the NRC ranked Diablo Canyon as the nation’s plant most vulnerable to earthquakes stronger than it was designed to withstand. For the new safety review, Diablo Canyon is one of only two nuclear plants the NRC classified as high priority. PG&E must complete its review by June 2017, but the NRC may take until 2020 to evaluate whether to take regulatory action, which could include closing the plant and holding public hearings to determine if it is safe.

“The NRC is ordering further risk evaluations only for nuclear plants with newly discovered seismic hazards that exceed the basis for safety design, and has put Diablo Canyon in the highest priority for further review,” said Damon Moglen of Friends of the Earth. “The NRC won’t come out and say it, but, they’re essentially saying that the reactors are operating outside of their license. Under the law, that means these outdated reactors should be shut down immediately.”

The NRC letter is in response to a controversial PG&E seismic study, submitted in March as part of a disaster review ordered after the 2011 Fukushima reactor meltdown. PG&E’s report confirmed that the faults surrounding Diablo Canyon are far larger and more powerful than previously assumed, and that the shaking the faults could generate is much greater than that considered during design, construction and licensing more than forty years ago. Despite the report’s alarming conclusions, PG&E said the plant is safe, and NRC publicly agreed.

The letter also confirms a key concern of the NRC’s former chief resident inspector at Diablo Canyon, Dr. Michael Peck. Nearly two years ago, Peck filed a formal dissent arguing that the newly discovered faults indicate the plant was operating in violation of its license and should be closed. The NRC rejected Peck’s appeal and later worked with PG&E to illegally, secretly and retroactively amend the terms of the license to make it appear that the plant is safe.

“Instead of enforcing the law and shutting Diablo Canyon down, the NRC is giving PG&E as much as five more years to re-evaluate the risk,” said Moglen. “That’s small comfort to the millions of Californians who would be in danger if Diablo Canyon is struck by an earthquake of the force that scientists know is possible at that location. Once again the NRC shows more interest in helping PG&E cover its assets than in protecting the public, and once again PG&E is putting profits before safety.”

At a 28 April public meeting the NRC and PG&E presented about the seismic risk evaluation at Diablo Canyon.