(WCAU) -- One of the reactors at Three Mile Island shut down Thursday afternoon. The Nuclear Regulatory Commission issued a statement saying that one of TMI's reactor cooler pumps tripped.
The plant responded as designed, which is to automatically shut down at any sign of possible trouble, according to the NRC.
An NRC inspector is on site and in the plant's control room, according to officials.
The reactor that shut down was Unit One, which also shut down automatically in August while it was being shut down manually for repairs.
People in the area, which is just outside of Harrisburg in Dauphin County, Pa., reported hearing a loud noise just after 2 p.m. Officials say that was caused from steam being released during the shutdown.
Plant spokesman Ralph DeSantis told WGAL-TV that there is no health risk and the public is not in danger. DeSantis said radiation levels in the steam were "below detectable levels," according to WHTM-TV. A spokewoman from the NRC echoed that there is no impact on public health and safety, and said there was no evacuation at the plant.
Officials at the plant released this statement: "Three Mile Island Generating Station automatically shut down at 2:20 p.m. EDT today. The plant responded as designed and remains in normal shutdown condition while operators investigate the cause of the shutdown."