The Tennessee Valley Authority said its Watts Bar Unit 2 has achieved its first sustained nuclear fission reaction and is operating in a stable condition at low power levels.
TVA officials said the reaction was achieved at 2:16 a.m. Monday.
TVA said the unit was expected eventually to provide a sustained 1,150 megawatts of electricity. Together with Unit 1, the plant is projected to supply power to some 1.3 million homes in TVA's service area.
The Knoxville News Sentinel reported TVA officials will address the Nuclear Regulatory Commission on Tuesday in Atlanta over an NRC letter raising concerns in March that control room operators at Watts Bar may not feel free to raise safety concerns.
TVA is the nation's largest public utility, serving more than 9 million people in Alabama, Georgia, Kentucky, Mississippi, North Carolina, Tennessee and Virginia.