Pacific Gas and Electric Company (PG&E) has asked the Nuclear Regulatory Commission (NRC) to delay final action on its on-going license renewal application for the Diablo Canyon Nuclear Power Plant in California until seismic studies can be completed.


Diablo Canyon’s operating licenses expire in 2024 and 2025.

The utility says it is planning to accelerate completion of advanced 3-D seismic studies related to Diablo Canyon in the wake of Japanese earthquake and tsunami.

PG&E’s senior vice president of energy supply and chief nuclear officer John Conway said: “Many of our customers and government partners are concerned and want to know more about the seismic characteristics surrounding the Diablo Canyon Nuclear Power Plant.”

“We are being responsive to this concern by seeking to expeditiously complete the 3-D seismic studies and provide those findings to the commission and other interested parties so that they may have added assurance of the plant’s seismic integrity.”

PG&E has asked the NRC to withhold issuance of PG&E’s renewed operating licenses, if approved, until after this research is completed and the findings are submitted to the commission.

In a statement PG&E said its staff are continually studying earthquake faults in the region of Diablo Canyon as part of the plant’s comprehensive safety programme.

In November 2008, the United States Geological Survey, working in partnership with PG&E’s geosciences department, discovered the new shoreline fault zone. PG&E evaluated whether that new feature presented a safety risk to the plant and submitted its evaluation to the NRC under the commitment of its current operating licenses. PG&E’s evaluation confirmed the plant has adequate safety margin to withstand maximum ground motions postulated to occur from faults in the region, including the shoreline fault.

The utility plans to undertake high-energy offshore 3-D studies of the shoreline fault’s deeper regions as soon as it obtains necessary permits from various regulatory agencies, including the State Lands Commission, California Coastal Commission and County of San Luis Obispo. To address public concern regarding the seismicity of the areas surrounding Diablo Canyon, the utility seeks to expedite this permitting process so it can begin this phase of studies as soon as possible. PG&E also plans to conduct significant research along the Los Osos Valley and in the Irish Hills. The company will share the results with local jurisdictions in order to enhance their knowledge of the seismic characteristics of the region for their emergency planning and building standards requirements.

“Even after we have completed these advanced studies, our geoscientists will continue their ongoing seismic research to give us, our regulators and the public confidence that the plant remains safe,” said Conway.

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