Leaked earthquake safety document raises fresh concerns about Diablo Canyon, which activists want shut down
It was more than six years ago that Jeanne Hardebeck, a seismologist at the US Geological Survey's Menlo Park Earthquake Science Center, started to zero in on a pattern. "I was looking at small earthquakes," she explained. "I noticed them lining up."
She and other earthquake scientists also detected an anomaly in the alignment of the earth's magnetic field off the California coastline, near San Luis Obispo. It all added up to the discovery of an offshore fault line.
What made Hardebeck's discovery truly startling was that the sea floor fracture, now known as the Shoreline Fault, lies just about 300 meters from Diablo Canyon Nuclear Power Plant, California's last operational nuclear power plant. In the general vicinity of the facility, which is owned and operated by Pacific Gas & Electric Co., there are also three other fault lines.
These discoveries have raised safety concerns and fed arguments by activists who want the Diablo Canyon reactors shut down, at least until the danger can be properly assessed.
When the final construction permits for Diablo Canyon were issued more than 45 years ago, engineers assumed a lower seismic risk. PG&E's federal operating license to run Diablo Canyon is based on those assumptions. But the new information suggests that the ground is capable of shaking a great deal more in the event of a major earthquake than previously understood — leaving open the possibility that a temblor could spark sudden and disastrous equipment failure at Diablo Canyon.
The Nuclear Regulatory Commission, the federal agency charged with overseeing the safety of nuclear facilities, has determined that the plant's continued operation is safe. But Michael Peck, a senior NRC staff member, recommended that the reactors be shut down until a safety analysis could prove that the plant would successfully withstand a major earthquake. In the time since Peck began to sound the alarm about the potential seismic hazard, he's been transferred from Diablo Canyon to a NRC training facility in Chattanooga, Tenn.
As The Associated Press reported on Aug. 25, Peck, who served as a resident on-site safety inspector at Diablo Canyon for half a decade as part of his 33-year career with the NRC, called for the plant to be temporarily shut down in a Differing Professional Opinion (DPO) filed in June 2013. Such a filing signifies a formal challenge to an agency position, and the NRC standard is to rule on these findings within 120 days.
More than a year later, however, Peck's findings still haven't been addressed. Since the DPO is technically classified — someone leaked it, and Peck says he wasn't the source —the NRC hasn't even publicly acknowledged its existence. The NRC did not return calls seeking comment.
Meanwhile, the Bay Guardian has learned that the NRC's actions go beyond just foot-dragging on addressing Peck's findings. Following a series of exchanges in the years since the discovery of the Shoreline Fault, PG&E filed a request to the NRC for its license to be amended so that it could continue operating Diablo Canyon in spite of the outmoded design specifications. As part of its request, the company performed its own studies concluding that the continued operation of the plant was safe in light of the new seismic information.