Energy company Dominion Resources Inc. has filed an application to build an additional nuclear reactor at its North Anna Power Station to keep up with consumer electricity needs.

The Richmond-based utility is the third company to file a complete application to the U.S. Nuclear Regulatory Commission. Federal regulators last week approved an early site permit for a third nuclear reactor at the power station in Louisa County, about 60 miles north of Richmond.

Several environmental groups oppose Dominion's application. They say another reactor is unnecessary at a time when utilities should be exploring alternative energy sources. They also say that a reactor would pose another target for terrorists.

Dominion is among the power companies nationwide that are wading back into the nuclear pool after virtually abandoning the power source following the Three Mile Island accident in Pennsylvania in 1979 and the huge cost increases for New Hampshire's Seabrook nuclear power plant.