by Amanda Witherell
photo by Jim Zim
Ahh, a Friday afternoon toast to science. PG&E announced today that its Diablo Canyon Nuclear Power plant is actually situated on two seismically sensitive faults, not just the one previously identified in the 1970s when the plant was sited and built.
“The new fault is thought to be smaller than the other fault off the plant’s coastline, the Hosgri fault, but it is closer to shore. The new fault is less than a mile offshore while the Hosgri fault is about three miles offshore,” according to a story in the San Luis Obispo Tribune.
The geologists are calling it a vertical strike-slip fault with a potential magnitude of 6.5. The California Energy Commission has recommended more seismic mapping and studies and may require them before PG&E can apply for a license to renew the plant in 2025.
“The first fault was discovered before the nuclear plant was licensed, and retrofitting resulted in billions of dollars in cost overruns,” said Rochelle Becker in an Alliance for Nuclear Responsibility newsletter. “While the utility downplayed the significance of the fault on safe plant operations, the new fault is not good news for PG&E and may not be good news for San Onofre.”
In 2006 state legislators passed AB 1632, authored by Rep. Sam Blakeslee, that directs the CEC to assess the potential vulnerability of Diablo Canyon and the San Onofre Nuclear Generating Station in Riverside to a major disruption due to a seismic event, as well as the role these older plants play in the state’s overall energy portfolio.
Diablo Canyon serves a key role in what PG&E calls its “emissions free” power mix, a statistic it routinely cites as it tries to kill more progressive renewable energy proposals like Community Choice Aggregation in Marin County and San Francisco. PG&E uses 24 percent nuclear power, which is not renewable, but nattily names it “emissions free.” It doesn’t routinely mention the thousands of pounds of nuclear waste that are also housed at the power plant.