On February 28, 2012, a watch group cited Duke Energy's Oconee plant, located near Seneca, South Carolina for several safety violations. According to the watch group's report, the plant operated with an inoperable backup emergency cooling system for a lengthy 28 year period.
The Oconee plant installed the cooling system in 1983 in response to a partial meltdown at Three Mile Island, a nuclear plant with a similar design located in Pennsylvania. The cooling system was designed to open if overheating in the reactor building occurred. However, the electrical breakers for the cooling system opened at low temperatures. This defect posed a devastating safety risk, as the backup system could potentially fail to operate and cool the plant if an accident occurred. Although installed in 1983, the system was never tested and was in fact inoperable until June, 2011.