Public fear and suspicion about all things nuclear grew sharply after March 1979, when the cooling system at Three Mile Island Nuclear Generating Station failed and triggered a meltdown. In the end, actual releases of radiation were minimal, but the incident left behind a reputational mess in addition to the radiological one. On the day of the accident, the United States had 140 operating nuclear reactors, with 92 under construction and 28 more awaiting official approval. In the next five years, more than 50 orders for new nuclear reactors in America were canceled. New contracts entirely dried up.

Hanford has not produced plutonium for three decades. Nobody is making new material for bombs anymore. President Trump’s plans for more weapons can be met by recycling existing plutonium stocks. And even the civil nuclear industry, which still generates a fifth of America’s electricity, is in what looks like terminal decline. With cheap natural gas and renewable solar and wind energy increasingly available, the numbers no longer add up. Nuclear power plants across the nation are being closed with years of licensed operation unused.

No new nuclear power stations have come on line in the past two decades. The only new build underway, two additional reactors at Georgia Power’s Alvin W. Vogtle plant near Waynesboro, is five years behind schedule and has seen its costs double. Its planned completion in 2022 remains uncertain.

America’s 99 remaining operational nuclear power reactors, which still deliver power to the grid, are too important to be closed overnight. But nearly half are over 40 years old. The only question is how long the regulators and accountants will allow them to keep going.

Oyster Creek in New Jersey disconnects from the grid in October with 11 years left on its license. Indian Point in New York State is to shut by 2021 due to falling revenues and rising costs. In California, Diablo Canyon is being closed by state regulators in 2025. The reactor at Three Mile Island in Pennsylvania that survived the 1979 accident will finally shut in 2019.

Shutdown is only the beginning of the end. Final closure and clearance of the sites can take decades, and the waste crisis created by decommissioning cannot be dodged. Lethal radioactive material is accumulating at dozens of power plants, military facilities, and interim stores across the country.

Some, like the train cars buried at Hanford, is evidently in a precarious situation. Much more needs urgent attention. Cleaning up and safely disposing of the residues of the nuclear adventure—much of it waste with a half-life measured in tens of thousands of years—is turning into a trillion-dollar nightmare for the nation.

Rocky Flats Wildlife Refuge is an oasis of prairie biodiversity covering 5,000 acres, home to prairie dogs, elk, monarch butterflies, and rare xeric grasses. It also serves as a buffer zone around the site of the largest completed nuclear cleanup to date in the United States. And David Lucas of the U.S. Fish and Wildlife Service is preparing to open it for public access in summer 2018. He’s reckoning on 150,000 visitors a year.