HOUSTON, Oct 12 (Reuters) - The U.S. Nuclear Regulatory Commission said its latest analysis of seismic faults near PG&E Corp’s Diablo Canyon nuclear station in California showed the coastal plant could withstand an earthquake generated by an offshore fault identified in 2008, according to a statement on Friday.
The NRC’s report focuses on the latest identified earthquake source, called the “Shoreline fault,” just offshore from the plant in San Luis Obispo County, about 183 miles (294 km) northwest of Los Angeles.
“Both PG&E and the NRC are continuing to look at the seismic characteristics of the Shoreline fault,” said NRC spokesman Victor Dricks. “This research information letter represents the staff’s latest analysis and basically concludes that the plant, as designed, would withstand any earthquake the Shoreline fault would generate.”
Diablo Canyon operator Pacific Gas & Electric notified the NRC about the Shoreline fault in 2008. At 2,240 megawatts, Diablo Canyon is the largest of the state’s two nuclear power plants, supplying about 10 percent of the state’s power needs.
An NRC team visited the site in 2011, the agency said. Analysis from the visit and available information indicates that ground motion from earthquakes the Shoreline fault could potentially generate would fall within Diablo Canyon’s existing design limits, the agency said in its report.
The plant’s design limits are based on ground motion associated with an earthquake from the larger Hosgri fault near the plant, the NRC said.
Separately, PG&E is pursuing a $64 million seismic study to better understand the hazards posed by potential earthquakes near the plant.
In August, the California State Lands Commission voted to allow the utility to move forward with tests using powerful sonar devices despite concerns about the impact on marine life.
PG&E’s application to extend the Diablo Canyon reactors’ operating licenses beyond 2024 and 2025 will not be finalized until the seismic study is completed.
For the NRC, Diablo Canyon must perform additional earthquake evaluations, as well as a “walkdown” to identify any near-term actions for enhancing earthquake resistance as part of the agency’s ongoing response to the 2011 Fukushima Daiichi nuclear accident in Japan which was triggered by an earthquake and tsunami.