The Oyster Creek nuclear plant in New Jersey was opened when the Beatles were still together, and since 1969 its single 645 MW boiling water reactor has provided enough energy to power 600,000 homes. But the oldest nuclear plant will be going out of commission a little early-last year owner Exelon Energy announced that it would close Oyster Creek in 2019, 10 years ahead of schedule. The reason: the aging plant cost too much to keep running safely.Most of the attention since the Fukushima Daiichi nuclear disaster has focused on the troubled future of the American atomic sector. But the U.S. nuclear industry was already facing a very old problem: its aging fleet of reactors. Nuclear plants were built with a 40-year license, with the option to theoretically expand to 60 or even 80 years. Half the country’s 104 reactors are at least 30 years old, and reaching middle age. So far 62 of those of those plants have been granted 20-year extensions, with 20 still pending. But the oldest plants-like the one in Fukushima-tend to have fewer safety measures. If regulators crack down, operators-like Exelon with Oyster Creek-could decide it’s not worth the cost and shut down the plants. If no new nuclear plants are built to replace them, nuclear could age into obsolescence. Ironically, that could have negative environmental effects-a report by the Breakthrough Institute, an energy think tank, found that replacing all U.S. nuclear with a mix of coal and gas would raise carbon emissions 9% by 2030. “We need to understand that there would be consequences to pulling back on nuclear,” says Michael Levi, a senior fellow for energy and the environment at the Council on Foreign Relations. Like a great athlete, we may miss nuclear power after it retires.