In this March 1, 2010 file photo, the San Onofre nuclear power plant, seen here in north San Diego County, Calif. In an effort to ease local concerns about a possible nuclear disaster on the West Coast, operators of Southern California's San Onofre and Diablo Canyon nuclear plants say their plants can withstand a higher magnitude earthquake than scientists predict could ever strike the region. The Nuclear Regulatory Commission also say harmful levels of radioactivity from Japan are unlikely to reach the United States..