The worst nuclear accident in U.S. history took place on March 28, 1979 at the Three Mile Island plant in Pennsylvania. A cooling system failed, causing a partial meltdown, but a full meltdown was averted and there were no fatalities. However, despite the positive outcome and despite the passage of more than 30 years, the incident remains fresh in the minds of those who are old enough to remember it.
The effect of the accident on the U.S. nuclear power industry was major. The meltdown gave many Americans second thoughts about the risks of using nuclear power, and the construction of new reactors, which had been steadily increasing since the 1960s, slowed substantially. Over 50 nuclear plant construction projects were cancelled in just four years, and the number of ongoing projects declined from 1980 until 1998.