Nuclear risksCritics: PG&E downplays quake risk to Diablo Canyon nuclear plant

Since the Diablo Canyon nuclear power plant in California was opened by Pacific Gas and Electric Co. (PG&E) in 1985, geologists have discovered three fault lines nearby, which could threaten the plant.

SFGatereports that the three faults are said to be capable of quakes even stronger than the one which ravaged the Napa Valley last year. Critics of PG&E say the company has been minimizing the risks the three faults pose.

“The company has been claiming that the plant is stronger and stronger as more faults have been discovered,” said former state Senator Sam Blakeslee, who also has a doctorate in geophysics. “The utility has been moving the goal posts.”

The company argues that years of seismic studies and fault data at another plan near San Luis Obispo have given them a better picture of the fault risks than ever before. Company officials claim that the Hosgri, the largest nearby fault under the ocean, cannot shake the plant as much as previously feared. They also argue that their methods for assessing seismic threats to the plant are far more advanced than they were in 1985.

“It is a gold standard of how to look at seismicity and the geology surrounding any infrastructure, not just nuclear power plants,” said Ed Halpin, the senior vice president of PG&E. “In my opinion it should be held up and applauded.”

Friends of the Earth, and environmentalist group, is suing for the company to seek a renewed license, arguing that the Nuclear Regulatory Commission (NRC) illegally allowed PG&E to amend the seismic safety aspects of the Diablo plant’s operating license without a public hearing. The suit came after former NRC inspector Michael Peck revealed that the illegal action was taking place.

“I’ve been an inspector twenty-five years,” said Peck. “I compare what PG&E does against the license, and I can tell you that it’s not allowed. I can’t tell you it’s unsafe, because I’m not a seismologist. But I can tell you it’s not allowed.”

The commission has countered Peck’s argument, saying that the plant still qualifies under the updated rules.

“The older analytical techniques were overly conservative and no longer technically justified,” said NRC spokeswoman Lara Uselding. “The NRC remains satisfied that PG&E’s past submittals have appropriately analyzed emerging information regarding the seismic makeup of the area surrounding Diablo Canyon.” Additionally, the plant remains built to a .75g ground shaking standard, even though the original license only called for .4g.

A leaked internal PG&E memo states, however, that if the company had to assess one of the recently discovered faults by the old methodologies, the plant would have to request a waiver from the NRC to continue operating.

Some geologists support PG&E’s position. William Lettis, a member of a separate geological team assembled by the NRC, has come up with his own models of the Diablo fault, and says that PG&E’s retrofit of the plant is in fact in accordance with much of the current data.

“Where earthquake science is moving is to use site-specific information where it’s available,” he said. “To ignore site-specific information where it’s available would be flat-out wrong.”

There were no further details regarding the specifics of the lawsuit.