Duke Energy Corp.'s Catawba 1 nuclear unit outside Rock Hill has begun to return to service after the plant shut down unexpectedly Sunday.
The 1,129-megawatt unit ramped up to 7% of capacity by early Tuesday, according to a Duke filing with the U.S. Nuclear Regulatory Commission.
Duke says plant personnel were performing maintenance duties when the unit automatically shut down.
Charlotte-based Duke (NYSE: DUK) says all safety systems operated as designed during the event.
Meanwhile, the adjacent Catawba 2 unit continued to operate at full power.
Unit 2 is owned by N.C. Municipal Power and the Piedmont Municipal Power Agency.
Unit 1 is owned by a partnership of Duke Power Co., the N.C. Electric Membership and Saluda River Electric Co-op.
Duke operates both units.