Two weeks after an earthquake and tsunami devastated northeastern Japan and emergency workers struggled to keep the Fukushima Daiichi nuclear power plant from melting down, California lawmakers convened the state’s own nuclear plant operators to demand more rigorous seismological risk research. 


State Senator Sam Blakeslee (R-San Luis Obisbpo) asked Pacific Gas & Electric Co. to withdraw its re-licensing application to the Nuclear Regulatory Commission for the Diablo Canyon Nuclear Power Plant until better seismology data is available. Its current 40-year licenses expire in 2024 and 2025. 


Blakeslee criticized the plant at a state Senate hearing he convened on March 21 for “putting my constituents in a place of great risk.” Citing PG&E’s reluctance to initiate sophisticated seismological mapping recommended by the California Energy Commission, Blakeslee says the plant has developed a “culture of disregard of risk. It’s a culture that’s become endemic at PG&E.” 


PG&E began the mapping in October of 2010; Blakeslee authored legislation pushing for such studies in 2006. 


Perched at 85 feet above sea level with sweeping coastal views, the 2300-megawatt Diablo Canyon plant is precariously positioned near two faults that thread into the larger San Andreas. 


It wasn’t until 1971, after Diablo Canyon was already permitted and construction underway, that the Hosgri Fault was discovered. In 2008, scientists from the U.S. Geological Survey and PG&E discovered another fault half a mile offshore. 


PG&E’s Geosciences Director Lloyd Cluff told Blakeslee, “We don’t see a concern about the uncertainty.” But what’s most troubling to Blakeslee, who holds a doctorate in seismology from U.C. Santa Barbara, is the unknown. “Unlike PG&E, I am quite concerned about the seismic uncertainty that exists at the facility,” he told the Weekly in an e-mail after the hearing.


Japan’s Fukushima Daiichi plant was equipped to withstand a 7.9 magnitude earthquake, but when a 9.0 struck and a major tsunami washed away its backup generators, the plant was left without a functioning cooling system. 


Diablo Canyon’s once-through cooling system uses seawater, and is powered by the plant’s turbine. For emergency operation, there are six back-up generators and seven days’ worth of diesel in underground storage nearly 100 feet above sea level, and 5 million gallons of water stored in reservoirs that would flow with the help of gravity to cool fuel in the event of a power outage. 


But the whole system could fail, argues Dan Hirsch, a lecturer on nuclear policy at U.C. Santa Cruz and president of the nonprofit Committee to Bridge the Gap. An event that could disrupt the reactors could also destroy the reservoirs and generators, as well as emergency evacuation routes along Highway 1. “It can happen at Diablo,” he says, “as easily as it happened at Fukushima.”