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ROSEMEAD, Calif., November 1, 2011 —Southern California Edison (SCE) has declared an alert at the San Onofre Nuclear Generating Station as a result of an ammonia leak at the plant. The leak is in the non-nuclear section of the plant.

At approximately 3 p.m. PDT, SCE declared the alert based on identifying an ammonia leak in Unit 3’s make-up water treatment system.

As a precaution, the company evacuated employees in the area near where the leak was found.  Other employees remain in other areas of the plant.

There is no immediate danger to the public. Both units are operating normally.

The alert is required because fumes could prevent access to certain areas of the plant.  The control room is staffed and fully operational, and both Units are at full power.

An alert is the second lowest of four federal classifications for emergencies at commercial nuclear power plants. An alert is characterized by events that are in process or have occurred that involve an actual or potential impact on the level of safety of the plant.

SCE and offsite agencies have opened the San Onofre Joint Information Center, located at 14155 Bake Parkway, between Toledo Way and Trabuco Road in Irvine.  More details will be released as they become available.  News media are encouraged to go to the Joint Information Center for the most up to date information regarding events at the plant.

In accordance with pre-existing emergency plans, appropriate federal, state and local emergency organizations, including the Nuclear Regulatory Commission, are being notified.

Background Information

  • Nuclear plant emergency classifications are established by the Nuclear Regulatory Commission.
  • The San Onofre plant, located just south of San Clemente, Calif., consists of two pressurized water reactors, Units 2 and 3, similar in design to 69 of the 104 operating U.S. reactors. 
  • San Onofre is jointly owned by SCE (78.21%), San Diego Gas & Electric (20%), and the City of Riverside (1.79%).

About Southern California Edison
An Edison International (NYSE:EIX) company, Southern California Edison is one of the nation’s largest electric utilities, serving a population of nearly 14 million via 4.9 million customer accounts in a 50,000-square-mile service area within Central, Coastal and Southern California.


Southern California Edison Declares an Alert at the San Onofre Nuclear Generating Station