The San Onofre nuclear power plant has been closed for nearly four months while the Nuclear Regulatory Commission wants to know why steam tubes in the plant’s reactors have been showing signs of early wear. Now, plant officials have notified the NRC of a new problem: faulty motion sensors that might shut down the reactors in an earthquake.
As the Los Angeles Times reported this morning:
Officials at the San Onofre nuclear plant said it’s possible that vibration sensors in the plant’s backup diesel generators could be tripped by an earthquake, leading to shutdown of the generators.
Plant operator Southern California Edison reported the potential issue to the Nuclear Regulatory Commission and said it has disabled the sensors while it looks into the issue.
The diesel generators provide power to the plant and keep safety systems running in the event of a power outage. The generators have sensors that are set up to shut the generators down if they identify excessive vibration that could be caused by mechanical engine damage.