Who Destroyed Three Mile Island? - Nickolas Means

On March 28, 1979, at exactly 4 o’clock in the morning, control rods slammed into the reactor core of Three Mile Island Unit #2, halting the nuclear reaction because of a fault in the reactor cooling system. At 4:02, the automated emergency cooling system activated as the reactor core temperature continued to rise. At 4:04, one of the plant operators made the befuddling decision to switch off the emergency cooling system, dooming the reactor to partial meltdown. Why?