Southern California Edison, which operates the idled San Onofre nuclear power plant, reported to federal regulators that someone might have tried to sabotage an emergency backup generator, according to media reports.
An investigation "found evidence of potential tampering," leading managers to increase security at the plant, the utility announced in a statement.
The announcement comes three weeks after Voice of OC first reported the suspected sabotage, which involved coolant mixed with the oil system for Unit 3’s emergency diesel generator.
Diesel generators are considered a critical safety component at nuclear power plants. In the event of a power outage, the giant machines power the plant and keep nuclear fuel from overheating.
Edison says the suspected tampering posed no danger to the public because the plant is shut down.
As the Huffington Post reports, the FBI may be involved in the investigation:
An employee at the plant who asked not to be named because he feared reprisals from management said supervisors told employees on Thursday that the FBI would be taking over the investigation and that criminal charges were possible. A company spokeswoman declined to comment on whether the FBI was involved.
The incident was discovered in late October and was reported to an on-site NRC [Nuclear Regulatory Commission] inspector shortly thereafter. "The plant initiated a review of the incident, which is still ongoing, and subsequently reported the incident as a security-related incident on November 27," said Scott Burnell, a spokesman for the NRC. "Because the NRC’s review is ongoing and the incident is security related, we have no further information to share at this time."
The backup diesel generator, attached to Unit 3, one of the site's two nuclear reactors, would be needed to help keep the reactor cool if off-site power was somehow lost.
According to the Voice of Orange County, which first reported the incident in early November, NRC's on-site inspector said the coolant likely would have made the generator run unpredictably.
The failure of emergency generators at Japan’s Fukushima plant was cited as one of several factors in its meltdown last year.
At San Onofre, however, Unit 3 has been shut down since a small radiation leak in January prompted a federal review of the plant’s steam generators. Hundreds of steam generator tubes in Units 2 and 3 were later found to have rapidly deteriorated because of a faulty design.