Calif. Quake Felt at Diablo Canyon Over Weekend, Reactors Remain Online

Operators at the Diablo Canyon nuclear plant felt a 5.3 magnitude earthquake in central California over the weekend, but it did not trip the reactors or cause any damage at the plant.

Nonetheless, the shaking prompted an unusual event notification to the Nuclear Regulatory Commission while crews conducted walkdowns to check equipment. According to an NRC filing, the quake occurred at about midnight while both Westinghouse pressurized water reactors were at full power. No damage was identified at either unit, and the unusual event ended at 11:42 a.m. Sunday.

Since 2010, plant owner Pacific Gas and Electric has been conducting detailed studies of the region's geology and its potential for earthquakes. According to the company, the on-shore research is almost complete, as are low-energy studies offshore. PG&E is in the process of producing further 3D and high-energy off-shore studies, which are pending regulatory approval.