Progress Energy's trouble-prone H.B. Robinson nuclear plant in South Carolina declared an emergency after a fire was reported at the facility.

The Robinson plant was in shutdown mode for a refueling outage Monday when the electrical fire occurred in a control cabinet of a polar crane. No injuries were reported.

The nuclear plant is coming off a period of troubled performance during which it experienced four unplanned shutdowns, two electrical fires and a power failure between 2009 and 2010.

In 2011, the Nuclear Regulatory Commission removed the Robinson plant from a list of the nation's worst-performing plants after a period of trouble-free performance.

The NRC said Progress had properly addressed the previous problems and had made changes in its safety culture.