BATON ROUGE - A problem regarding the feedwater heating system led to an unplanned weekend shutdown of the River Bend nuclear power plant in St. Francisville.

Officials with the Nuclear Regulatory Commission said the incident began just before midnight on Friday. Operators were raising power following a prior shutdown when they noticed a concern with the plant's feedwater heating system.

That system preheats water that is then recirculated back into the reactor.

The NRC tells WBRZ News 2 that procedures require a manual shutdown as a safety precaution when such a problem develops.

"All control rods fully inserted with no complications and on Saturday the plant was completely shut down," the NRC said in a statement. "The licensee was able to correct the feedwater issue and restarted on Sunday."

Entergy -- which operates the plant -- provided the following explanation:

As the plant ascended in power, operators noted an issue related to the low-pressure feedwater system, which eventually changed the feedwater temperature until it was outside normal technical specifications. Operators responded appropriately and brought the plant offline to make corrections, which will include valve tuning to ensure the valves respond seamlessly to operator inputs.

River Bend Station has been in operation since 1986. Entergy said it generates 974 megawatts of electricity, which meets about 10 percent of the total demand in Louisiana.