The Unit 1 reactor at Plant Vogtle near Augusta is approaching full power after it unexpectedly shut down twice last week.
A spokesperson for Southern Company said the reactor has been generating electricity since Friday and is currently running at 94 percent power.
Equipment problems caused the first shutdown last Monday.
The second happened after technicians noticed high levels of vibrations on a turbine, a problem that has since been corrected.
Officials say they will perform routine maintenance on the reactor before returning it to full power.