At 2:32 p.m. Pacific Time on Nov. 1, workers at the San Onofre Nuclear Generating Station in California smelled ammonia in the south end of the Unit 3 turbine building. The leakage was traced to a storage tank adjacent to the turbine building. The leak was reported to the control room and announcements were made over the site’s public address system advising workers to stay clear of the turbine building.
NRC inspectors performing baseline radiation safety inspections responded to the Main Control Room and Technical Support Center. John Reynoso, the resident inspector, was offsite and responded to the site to monitor the scene of the leak near the Unit 3 turbine building. (Resident inspectors are assigned to all nuclear power plants so that the NRC has “ears and eyes” on the ground.) Within minutes, the station manager declared an “Alert,” because some vital areas within the turbine building had become inaccessible.
An Alert is the second of four emergency declaration levels and is declared, according to NRC regulations, when events could involve an actual or potential decline in the level of plant safety. Further investigation revealed the storage tank was leaking ammonia at the rate of about one gallon every ten minutes. Workers were able to stop the leak by 5 p.m.
The Alert was terminated shortly after 6 p.m. Both units remained stable and operating at full power. No radiation was released. There were no personnel injuries reported, and all leakage was contained onsite. But it was the first Alert declared at San Onofre since 1999, when a suspected pipe bomb was found on the freeway nearby.
As might be expected, it generated intense media interest, with coverage in 473 different venues overnight, according to a Google news search. The NRC resident inspectors will review the licensee’s response to the event, including the promptness of their efforts to stop the spill and corrective actions taken to prevent recurrence.Victor Dricks Region IV Public Affairs Officer