Three Mile Island
© Chris Knight/The Patriot-NewsThree Mile Island nuclear fa­cility along the Susquehanna River in Londonderry Township.
Pennsylvania, US - People who live near Three Mile Island in Londonderry Township may have heard a loud noise this morning when steam was released into the atmosphere during a shutdown of the nuclear power plant.

If there were traces of radiation in the steam, the amount was so low it was undetectable, Exelon Corp. spokesman Ralph DeSantis said.

The plant was being manually shut down today for repairs to a slight leak in a heater element when a pump in the non-nuclear section malfunctioned around 8 a.m., causing the plant to shut down immediately. When this happened, steam was released from valves, DeSantis said.

TMI will return to service after the repairs, inspections and testing on the heater element on the plant's pressurizer tank are complete, DeSantis said.

Electric customers were not affected by the plant being offline.