LOS ANGELES (AP) -- Federal regulators say an ammonia leak that caused an emergency alert at Southern California's San Onofre nuclear plant was caused by employees who failed to recognize degraded equipment and fix it.
A Nuclear Regulatory Commission report Friday faults plant operator Southern California Edison for failing to follow its own procedures at the twin-reactor site north of San Diego.
The report says the problem had "very low safety significance."
But watchdog groups have criticized the company for not alerting the public for more than an hour after the Nov. 1 leak started in a storage tank.
Some workers were evacuated but there was no public danger.
Meanwhile, the company is investigating a leak in a steam generator tube, as well as unusual wear in hundreds of tubes in the second plant.