South Carolina Electric & Gas Co. will take Unit 1 at V.C. Summer Nuclear Station offline Friday to begin a scheduled refueling outage.

About one-third of the nuclear plant’s 157 fuel assemblies are replaced every 18 months.

The outage also allows the SCANA Corp. subsidiary to do maintenance that cannot be performed while the reactor in Jenkinsville north of Columbia is operating.

While the 966-megawatt unit is out of service, SCE&G’s other generating plants will provide electric power for its 669,000 customers throughout South Carolina. About half of those are in the Charleston area.