Three Mile Island turned the nation against nuclear energy. Now the notorious complex is closing just as some say it still has a role to play. //

the complex, which sits 100 miles west of Philadelphia along the Susquehanna River, the other unit is one of the region’s biggest power sources, churning out electricity for 45 years without incident. Next month, that too will come to an end. Plant owner Exelon Corp. is scheduled to shutter the entire facility, 15 years before its license is set to expire. //

Compared with the release of radiation at Chernobyl, which the United Nations estimated in 2005 may eventually kill 4,000 people, the accident at Three Mile Island was minor. Only a small amount of radioactive material was released, and it was later determined that the 2 million people in the surrounding area were exposed to less radiation than they would have received from a chest X-ray. //

Today, nuclear energy in the U.S. is at the center of a complicated debate. While cheap gas has upended the economics of operating reactors, whether to shut one down involves more than the bottom line.

U.S. President Donald Trump has taken steps to support unprofitable nuclear and coal power plants, citing national security issues because they generate electricity around the clock. Some of his efforts have been rejected by federal energy regulators.

Meanwhile, environmental groups have mixed feeling about reactors. Some are concerned about the accumulating nuclear waste that will remain deadly for thousands of years, as well as the potential for mishaps. Still, others are alarmed by the intensifying threat of climate change tied to the burning of fossil fuels—even cheap kinds such as natural gas.

Either way, Three Mile Island won’t be part of the future of American energy. Exelon will be switching off Unit 1 in a few weeks, and a decommissioning company is in talks to begin dismantling Unit 2. //

shuttering reactors for purely financial reasons ignores their ability to produce clean energy. New plants are hugely expensive to build; once shut, old plants cannot be brought back on line.