Sirens sounded when an ammonia leak triggered a Level-Two emergency alert at San Onofre nuclear power plant Tuesday, according to authorities.
Employees discovered the leak in the Unit 3 steam system in a non-nuclear portion of the plant just before 3 p.m. and declared an alert, said SoCal Edison spokesman Gil Alexander in a statement.
The alert was canceled at 6:07 p.m. and evacuated workers to return to the site, the Associated Press reported.
The company evacuated around 50 employees in the area near where the leak was found, company officials said.
There was no imminent threat to public health or safety and no radiation was leaked, Alexander said.
But the alert was frightening to nearby residents.
"I was kind of scared," says surfer Karina Rozunko. "At first I was like, oh it's not that big of a deal. Stuff like that happens all the time and they don't really tell anybody, but this time it actually seemed like something serious was happening."
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According to federal regulations, a Level-Two alert involves any "potential substandard degradation in the level of safety of the plant." Officials are required to issue an alert in an event where they are unable to safely shutdown a system during an emergency.
The leak was isolated and plant officials made needed repairs for several hours.
Officials describe the ammonia container as a "day tank" which holds about 750 gallons of the gas—of which about 30 gallons leaked.
Ammonia is used routinely to purify the steam system and the plant continued to operate and generate electricity during the emergency, SoCal Edison spokesman Steve Conroy said.
The County of San Diego, in response to the alert, activated and staffed the Operational Area Emergency Operations Center with county agency representatives, in order that it would be prepared should the situation at the power plant deteriorate.
All resources and support personnel were identified and were on standby, ready to be mobilized, if needed.
Residents were encourage to call 211 for information and to avoid 911 unless there is a life threatening emergency, said San Diego County spokeswoman Holly Crawford.