ˌThree Mile ˈIsland BrE AmE
a place in Pennsylvania in the US, where there was a serious accident in 1979 in a NUCLEAR POWER station (=a place where electricity is produced using nuclear energy) . The people in charge managed to prevent a ↑ meltdown (= when the nuclear material melts and burns through its containers) , but the accident increased opposition to nuclear power in the US and prevented new power stations from being built.