The infamous Three Mile Island nuclear power plant, which suffered a partial meltdown in 1979 was officially closed on Friday, a historic milestone in the checkered history of nuclear power in the United States. The owner cited lack of subsidies for its power as a reason for the closure. The plant lost money for the past five years and the state of Pennsylvania balked at further subsidies. Only one reactor of the facility was still in operation. The plant's owner, Excelon Corp., said clean up of the site will take an estimated $1.2 billion. All of the facility's nuclear material will not be removed until 2078. High decommissioning costs are one reason nuclear power finds it increasingly difficult to compete against cheaper, cleaner alternative energy and natural gas. The nation's fleet of 96 operating reactors are all nearing the end of their planned operating lives; their average age is 38.Although no one died from the nuclear fallout of the meltdown, the incident led directly to stricter federal regulation of nuclear power facilities. The number of new plant constructions has declined to zero since then. The last two nuclear plants built in the US are Watts Bar, begun in 1973, and River Bend, begun in 1977. More than a decade elapsed before these plants began producing power, once claimed to be "too cheap to meter".