Unit 1 at South Carolina's Oconee nuclear plant powered down Sunday night to fix a small pressure boundary leak in its reactor coolant system.
Operators dropped the reactor to 20 percent power after a visual inspection turned up a leak in a high-pressure injection line measured at 0.13 gallons per minute, according to a report filed with the Nuclear Regulatory Commission. The unit was shut down completely on Tuesday.
The leak, confined within the reactor's containment structure, posed no threat to employees or the public. Unit 2 was offline for a scheduled maintenance outage, while unit 3 continued to run at full power. Operated by Duke Energy, all of the units near Greenville, S.C., are Babcock & Wilcox lowered-loop pressurized water reactors generating roughly 850 megawatts each.