Three Mile Islan Nuclear Generating Station is a civilian nuclear power plant located on an island (Three Mile Island) in the Susquehanna River near Harrisburg, Pennsylvania, United States. Its name is derived not from the size of the island, but from the fact that TMI is three miles downriver from Middletown, Pennsylvania. It was built with two pressurized water reactors, TMI-1 and TMI-2. The plant is most well known for being the site of the worst civilian nuclear accident in United States history when in 1979 TMI-2 suffered a partial meltdown. The core of TMI-2 has since been removed from the site.