Mysterious case of coolant in the diesel generator oil system. How did it get there? The plant operator suspects a sabotage.
From Huffington Post (11/29/2012; emphasis is mine):
San Onofre Nuclear Plant Investigating Possible Sabotage Of Safety System
by Tom Zeller Jr.
A California utility said Thursday it has notified the Nuclear Regulatory Commission of potential sabotage, possibly by an employee, of a crucial piece of safety equipment attached to one of its nuclear power reactors.
Southern California Edison said the incident did not pose an immediate safety threat because the plant involved, the San Onofre Nuclear Generating Station near San Clemente, is currently offline. But the plant operator found engine coolant had been poured into an oil reservoir on an emergency backup generator, which would have likely caused the generator to malfunction if needed to help cool the reactor during a power failure. The tampering is being taken seriously and security at the plant has been tightened, SCE said.
"The comprehensive investigation has included rigorous tests, a review of station logs and employee interviews to determine the cause of the presence of the residual engine coolant," the company said in a statement late Thursday. "Based on the unexpected discovery of the coolant in the diesel oil system and the ongoing investigation, security at the plant has been enhanced."
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 first discovered in late October and was reported to an on-site NRC 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.
(Full article at the link)
Voice of Orange County reported on November 9, 2012, quoting John Reynoso, NRC inspector at San Onofre Plant:
San Onofre’s diesel generator was taken offline on Oct. 21 for two weeks of maintenance when about two cups of coolant was found in the oil for its governor, Reynoso said.
If the coolant had been left in place and the generators activated, Edison believes the governor, which controls the generator’s speed and prevents it from running too fast, would have failed, Reynoso said.