Is Diablo Canyon prepared for possible earthquake?

Posted: Mar 14, 2011 6:48 PM by Nancy Chen
Updated: Mar 14, 2011 11:13 PM

It seems almost too disastrous to even imagine--a possible meltdown at a nuclear power plant. But in the wake of what's hit Japan, people on the Central Coast are asking if the same could happen here.

Diablo Canyon Nuclear Power Plant in San Luis Obispo County is about a mile from the Hosgri Fault, which seismologists say is capable of generating a 6.5 earthquake.

Several legislators have argued for better studies of the seismic risks.

Just today, State Senator Sam Blakeslee issued a statement, saying, "We need independent, third-party studies to determine the true risk presented by these large, dangerous faults in such close proximity to California's aging reactors."

Here on the Central Coast, Diablo Canyon sits near four fault lines.

"The plant sits on a very seismically active area, and there are identified earthquake faults nearby," said Adam Hill, the chairman of the San Luis Obispo County Board of Supervisors.

The two most significant are the Hosgri and Shoreline; the Hosgri is about a mile offshore at its closest point and could bring an earthquake up to a 6.5 magnitude.

PG&E, which operates the plant, says Diablo Canyon was specifically designed with a possible earthquake in mind and can take one up to 7.5 magnitude.

"All of our systems, components, structures--they've been tested to a certain level of ground shaking," said Kory Raftery, a spokesperson for PG&E. "Then the plan is designed over and above that level of ground shaking."

PG&E is now seeking to extend the life of the plant by twenty years to the year 2045.

Last year, the County Board of Supervisors sent a letter to the Nuclear Regulatory Committee, urging it to delay re-licensing until all seismic studies were done.

"What the scenarios might be, what the effect on the plant might be, and how the plant would respond and whether, in fact, it was constructed in a way and is currently constructed in a way that would protect it and therefore protect all the citizens," Hill said.

In the end, he says the NRC decided to allow the re-licensing process to run concurrently with the studies.

"But the plant is safe, and if it were ever deemed not to be safe or something needed to be changed, the licensing would be required to make those changes or not operate," said Lara Uselding, a spokesperson for the NRC.

However, both she and Hill said they were confident the proper procedures are in place at Diablo to withstand the biggest earthquake they estimate coming here at 6.5 magnitude.