Some opponents think owners of the Diablo Canyon nuclear plant are trying to rush through a license extension before the risk of a newly-located earthquake fault can be evaluated:

Pacific Gas & Electric Co., the big California utility, is seeking a 20-year license extension for its two reactors at Diablo Canyon, a nuclear power plant near San Luis Obispo, on the state's central coast.

That application, controversial even before an earthquake and tsunami crippled Japan's Fukushima Daiichi plant last month, is now shaping up as a major test of Americans' tolerance of nuclear power, especially in areas at high risk for natural disasters.

Local politicians are lining up to fight the license extension, arguing that the process should be put on hold while PG&E studies the area's earthquake risk.

"The tragedy in Japan underscores the importance and critical evidence of the need for a pause in relicensing," said Rep. Lois Capps (D., Calif.), who last month asked regulators to delay renewing Diablo's license.

National anti-nuclear groups, too, are making the Diablo case a focal point of their broader fight against nuclear power. "Diablo Canyon is just a striking and scary example of playing with some seriously explosive fire," said Sean Garren of the activist group Environment America.

Dozens of nuclear reactors operate in earthquake-prone regions around the world. Among them, least 34 are in high-hazard areas.

Opponents may have trouble making much headway with the federal agency that oversees nuclear relicensing, the Nuclear Regulatory Commission. The NRC sets strict limits on what issues can be considered in the relicensing, and has consistently rebuffed efforts to use the process to conduct broad-based reviews of plants' operations.