On This Day: Nuclear Meltdown Occurs at Three Mile Island
Carolyn Kaster/AP The Three Mile Island nuclear power plant pictured in 2005. March 28, 2011 06:00 AM by findingDulcinea Staff On March 28, 1979, the Three Mile Island nuclear power plant experienced a partial meltdown. It was the worst-ever commercial nuclear accident in U.S. history. Meltdown in Pennsylvania The Unit Two reactor at the Three Mile Island nuclear facility near near Middletown, Pa., had a unstable operating history . Even during construction there were delays, and unscheduled shutdowns persisted after the reactor began operating in 1978. Operators compensated for these deficiencies by falsifying data to avoid reporting to the Nuclear Regulatory Commission . At about 4:00 a.m. on March 28, 1979, a pump failure in a secondary (non-nuclear) system of the reactor stopped steam generators from removing heat from the unit , increasing the pressure in the primary (nuclear) portion. A relief valve was opened to release the pressure, but the