risk that an earthquake would cause a severe accident at a U.S. nuclear plant is greater than previously thought, 24 times as high in one case
first complete update to seismic risk in years for the nation's 104 existing reactors
NRC earthquake expert questioned releasing data to the public showing how strong an earthquake each plant was designed to withstand.
The worry about earthquakes is not so much direct damage to the reactor vessel, the hardened enclosure where the nuclear reaction takes place, but to water tanks and mechanical and electrical equipment needed when disaster strikes.
safety standards have been relaxed to keep aging reactors within the rules.