NRC finds no immediate seismic safety issues at Diablo Canyon

The federal Nuclear Regulatory Commission has formally responded to safety concerns raised by former senior resident inspector Michael Peck at Diablo Canyon nuclear power plant and concluded that there are no immediate seismic safety issues at the plant.

Mark Satorius, the NRC’s executive director for operations, on Wednesday issued a response to the safety issues raised by Peck in an appeal that he filed with the agency. That appeal criticized a 2009 review of the safety implications of the Shoreline Fault that runs just offshore of the plant.

Peck filed the appeal, called a differing professional opinion, in July 2013. The agency convened an independent review panel to look at his allegations, and Satorius met with Peck to hear his concerns. His response is in the form of a memo to Peck.

“A compelling basis for my conclusion is drawn from our meeting on July 30, 2014, when you and I agreed that there is not now nor has there been an immediate or significant safety concern associated with this Diablo Canyon issue,” Satorius said in his

response to Peck.

Blair Jones, PG&E spokesman, said the NRC’s official response confirms the conclusion that the plant, owned by PG&E, is operated safely.

“NRC’s announcement reaffirms that Diablo Canyon has been and continues to be seismically safe and that PG&E acted appropriately in its evaluation of the Shoreline Fault as well as other new seismic information,” he said.

The appeal

“The new seismic information resulted in a condition outside the bounds of existing Diablo Canyon design basis and safety analysis,” Peck wrote in his report. “Continued reactor operation outside the bounds of the NRC-approved safety analyses challenges the presumption of nuclear safety.”

Satorius disagreed, saying the independent review committee concurred with PG&E and NRC findings that “an amendment to the license was not required because the Shoreline Fault zone ground motions do not exceed the levels evaluated in the DCPP design and licensing.”

The plant was designed to withstand a magnitude-7.5 quake on the Hosgri Fault, which was discovered as the plant was being built in the 1970s. The Hosgri Fault was considered the fault that posed the greatest threat to the power plant, and the plant was designed to those standards.

The NRC concluded that the plant can also withstand an earthquake from the Shoreline Fault, discovered in 2008, because the threat from the Shoreline Fault did not exceed the Hosgri Fault’s threat.

Seismic studies released this week by PG&E indicate that the Shoreline Fault actually poses a greater threat but is still within the safety design standards for the plant.

Peck was assigned to the plant from 2008 to 2012 before applying for and being accepted to the agency’s technical training center in Chattanooga, Tenn., where he is now a senior reactor technical instructor.

Peck’s appeal prompted the U.S. Senate Environment and Public Works Committee, chaired by Sen. Barbara Boxer, to call for hearings into earthquake risks at Diablo Canyon. Boxer said she was alarmed that it had taken PG&E more than a year to respond to Peck’s appeal.

The status of those hearings could not be learned Wednesday.

The appeal also prompted the environmental group Friends of the Earth to petition the NRC to shut the plant down until the license amendment requested by Peck could be conducted.

“Diablo Canyon could never be built on such an earthquake-prone site today,” said Damon Moglen, the group’s senior strategic adviser. “It should not be allowed to operate for another day without being closed and subjected to a full public safety review.”

This story was originally published September 10, 2014 at 1:21 PM with the headline "NRC finds no immediate seismic safety issues at Diablo Canyon."