By Scott DiSavino
(Reuters) - The Nuclear Regulatory Commission said Tuesday the agency wants nuclear plant operators in the central and eastern United States to use a new seismic model to reassess the potential for earthquakes in their area.
The study comes almost a year after the disaster in Japan in March when an earthquake and tsunami damaged the Fukushima Daiichi nuclear power plant, causing reactor fuel meltdowns and radiation releases.
It also follows a magnitude 5.8 earthquake in August in Virginia that shut the two reactors at the North Anna nuclear power plant for about three months and a much smaller magnitude 3.2 earthquake Monday night that had no impact on the Virginia plant.
The study focused on the eastern and central parts of the United States because that area is considered a "stable continental region" where big earthquakes are rare. The study sponsors said nuclear sites in the western part of the country, where earthquakes are more common, will need to continue developing site-specific seismic models for their use.
The study, which gathered historical earthquake and geological data from 1568 through 2008, determined the largest potential earthquakes in the eastern and central parts of the country could occur near New Madrid, Missouri, and also in Charleston, South Carolina, where large magnitude seismic activity has occurred in the past.
There are no nuclear power plants within 100 miles of either city.
The central and eastern United States however is home to 90 reactors, 22 potential new sites and five Department of Energy (DOE) nuclear facilities, the study said.
Some of the nation's biggest nuclear power operators include units of Exelon Corp, Entergy Corp, Duke Energy and Progress Energy.
Overall, there are 104 operating power reactors in the United States, providing about 20 percent of the nation's power, and proposals to build up to three dozen new reactors mostly in the eastern half of the country.
The four-year study cost about $7 million and was sponsored by the Electric Power Research Institute (EPRI), which conducts research on issues related to the electric power industry, the DOE and the NRC.
Although the project sponsors said they did not undertake the new seismic study in response to the Fukushima or Virginia earthquakes in 2011, the NRC said its call for nuclear operators to re-evaluate seismic hazards was part of the agency's implementation of lessons learned from the events at Fukushima.
The new seismic model will replace previous models used by industry and government since the late 1980s.
(Reporting By Scott DiSavino; Editing by Lisa Shumaker)