- Pacific Gas and Electric (PG&E) invested $842 million in replacement steam generators and reactor vessel heads at the Diablo Canyon Nuclear Power Plant beginning in 2008 with potentially inadequate safety testing for an earthquake on the nearby Hosgri Fault and a simultaneous loss of cooling water within the reactors, according to the San Francisco Chronicle.
- PG&E evaluated the two events separately, though Diablo’s license from the Nuclear Regulatory Commission requires them to be considered together because a severe seismic event could rupture the system and lead to a meltdown.
- PG&E reportedly found the mistake a year after the equipment replacement in 2011, performed its own analysis, and found the new equipment met the simultaneous earthquake and loss of coolant conditions. Diablo Canyon opponents say this is the same kind of oversight failure that led to Japan’s Fukushima nuclear disaster
“Engineering and seismic experts performed a subsequent evaluation and confirmed there is sufficient margin in the components’ design to withstand a very rare event of a combined earthquake on the Hosgri Fault and a loss of coolant accident,” said PG&E spokesman Blair Jones.
PG&E relocated its nuclear facility to Diablo Canyon when another site proved to have a fault line running through it. Federal authorities approved construction in 1968 because PG&E said there were no active faults within 18.6 miles. Oil company geologists reported the Hosgri fault just offshore which the U.S. Geological Service estimates could produce a magnitude 7.5 quake. The Shoreline Fault, which is within 2,000 feet of the reactors, was found in 2008. Several other faults have been found nearby.
Opponents, who have challenged the facility’s seismic safety since 1971, have become more aggressive since the Fukushima events and now want Diablo Canyon shuttered like the San Onofre Nuclear Generating Station was.