"When an earthquake launched a tsunami that devastated a Japanese nuclear complex in March, U.S. regulators quickly reassured the public that American reactors were built to withstand the expected severity of earthquakes in their areas.

Privately, though, internal emails from March show staffers at the federal Nuclear Regulatory Commission fretted about the public attention on the potential earthquake vulnerability of some U.S. plants. Since 2005, the agency had been working on a study of seismic hazards that is far from complete but showed good reason to worry about two dozen reactors."

Rebecca Smith and Mark Maremont report for the Wall St. Journal (partial access) July 19, 2011. [2]