Strong earthquake rocks California; nuclear plants operating normally

Unusual event declared

SAN LUIS OBISPO, Calif., Dec. 22, 2003 — Pacific Gas and Electric Co. said its Diablo Canyon Power Plant in California operated normally through an earthquake occurring Monday north of the plant.

Duke Energy did not have substantial damage at its two coastal plants, Morro Bay and Moss Landing, area TV station KATU reported.

The quake struck at 11:16 am local time, according to the U.S. Geological Survey, which gave it a preliminary magnitude of 6.5 and said it was centered north of the tiny coastal town of Cambria. Although the quake was one of the largest to strike the state in recent years, officials said it caused only “modest” damage.

An Unusual Event was declared at 11:22 AM because the earthquake was felt by control room personnel and because it also registered on plant seismic monitors. Both units are still operating normally as operators are inspecting the rest of the plant to assure there is no damage.

Two deaths have been reported in the town of Paso Robles, which sustained the worst of the damage. The main shock was immediately followed by at least five aftershocks of magnitude larger than 3.3. The largest was estimated at 4.7.

About 40,000 people in the area lost electric power, but California’s grid operator reported no damage to high-voltage lines.

Pacific Gas and Electric Company (PG&E) notified county, state and federal authorities of the declaration of the Unusual Event.

As required by the Nuclear Regulatory Commission (NRC), an Unusual Event is declared for an other-than-normal plant condition that does not require any emergency action by the general public or any government authorities.