Three Mile Island Unit 1 closes for good, unable to run profitably

Three Mile Island Unit 1, the nuclear power station whose name has become synonymous with the nation's worst nuclear accident, was closed for good on Friday.

The 45-year-old nuclear reactor, located in Middletown, Pennsylvania, was losing money and the state legislature in nearby Harrisburg could not pass a $500 million bailout to keep the plant open. 

The plant's owner, Exelon Generation, bought it in 1999. The neighboring Three Mile Island Unit 2, owned by FirstEnergy, has been dormant since the 1979 accident that caused a partial nuclear meltdown — the worst commercial nuclear accident the U.S. has experienced.

Exelon also owns plants in Illinois, New York, New Jersey and Maryland. The first three of those states have all passed nuclear subsidy bills in recent years. But the Pennsylvania efforts failed amid opposition from consumer groups, some environmental activists and the state's natural gas industry.

Pennsylvania has the second-largest nuclear fleet in the country, after Illinois. Nearly 40% of the state's electricity comes from nuclear power — more than is generated there by wind, solar and hydroelectric resources combined, according to the Philadelphia Inquirer. 

But despite its carbon-free credentials, the nuclear energy industry has been in trouble because it's a relatively expensive form of power compared with competing natural gas. Pennsylvania's Beaver Valley Nuclear Power Station, which is owned by FirstEnergy and sits on the Ohio border, is scheduled to start shutting down next year.

Just under 700 people work at Three Mile Island's Unit 1, making it the biggest employer in its county. Exelon has said that it would reassign all affected workers to other positions in the company.