California lawmakers kept up the pressure Thursday for a harder look at earthquake safety at the two nuclear power plants in the state, questioning why federal regulators won't halt relicensing work until new seismic maps are completed.
"The seismic safety of our plants cannot be an afterthought," said Sen. Alex Padilla, D-Los Angeles, chairman of the Senate energy committee.
It's the second time a state Senate committee has addressed nuclear safety since a massive earthquake and tsunami on March 11 damaged several nuclear reactors in Japan.
Given that California's nuclear plants _ Diablo Canyon near San Luis Obispo and San Onofre north of San Diego _ face the highest seismic risk of any in the United States, continued scrutiny is needed to make the plants as safe as possible, Padilla said.
Pacific Gas and Electric Co., which operates Diablo Canyon, has applied to renew licenses that expire in 2024 and 2025.
This month, after pressure from state lawmakers and California's U.S. senators, PG&E asked the U.S. Nuclear Regulatory Commission to delay issuing the licenses until it completes three-dimensional seismic maps of a newly discovered offshore fault less than a half-mile from Diablo Canyon.
The NRC has not responded but was moving forward with other parts of the license review, according to Troy Pruett, deputy director for reactor projects for an NRC division in Dallas.
The NRC staff has spent thousands of hours preparing an environmental and safety review and wants to get that information to the public for review even if the seismic mapping work continues, Pruett said.
State Sen. Sam Blakeslee, R-San Luis Obispo, said the newly discovered Shoreline fault presents a threat to Diablo Canyon, and the mapping work is crucial to understanding that threat.
"How can you possibly make an assertion about the safety ... if you have not yet reviewed the data?" he asked.
"We're reviewing the data we have in hand," Pruett replied.
"The data you have in hand is not adequate," Blakeslee replied.
Pruett said the licensing work and seismic safety studies are related but independent.
"If NRC became aware of a seismic or safety concern that threatened safe operation, we would take action immediately," he said.
Blakeslee, a geophysicist who has been a frequent critic of Diablo Canyon and PG&E, pointed out the NRC signed off on the original license based on seismic studies by the utility indicating there were no faults nearby, but since then two faults have been discovered.
"I'm very concerned that the NRC is looking at this issue with rose-colored glasses," he said.
Pruett said available evidence, including reports from NRC inspectors working on site, indicates both California plants are being operated safely.
PG&E and Southern California Edison, which operates San Onofre, have said their reactors are different from those damaged in Japan.
The California facilities have been designed to withstand earthquakes and tsunamis and have redundant safety systems if a disaster or malfunction jeopardizes the reactors, the utilities contend.
Critics say those designs date back decades and engineering assumptions can be wrong.
A realistic assessment of risk has to be part of the discussion on nuclear power, said Rochelle Becker, executive director of the Alliance for Nuclear Responsibility.
"Ratepayers shouldn't be paying a penny for license renewal until seismic studies are completed," she said.