For only the second time in its history, the US Navy is beginning the slow, tricky process of taking apart a nuclear-powered aircraft carrier

• In April, the Navy published a notice announcing the beginning of planning to scrap the USS Nimitz.
• USS Nimitz entered service in 1975 and has spent nearly 50 years operating all over the world.

For the US Navy, the tiny atom has been a big friend. Nuclear power allows the Navy's aircraft carriers and submarines to stay at sea for extended periods, limited only by the endurance of their crews.

But there's a downside to nuclear-powered vessels: How do you dispose of them when they're no longer needed? While most ships eventually end up in the scrapyard, breaking up a radioactive power plant is a different matter — specially when it's in a giant aircraft carrier.

In early April, the Navy published a pre-solicitation notice announcing that Huntington Ingalls' Newport News Shipbuilding division would formulate requirements for scrapping the USS Nimitz. The Nimitz was commissioned in 1975 as the first of the 10 Nimitz-class vessels that comprise most of the current US carrier fleet.

The Nimitz would only be the second American nuclear-powered carrier scheduled to be scrapped. The first is the USS Enterprise, which was commissioned in 1961 and was also the world's first nuclear-powered carrier. Though the Enterprise was decommissioned in 2017, the Navy is just beginning a years-long process to safely dispose of it.

"The bulk of the Navy's past dismantlement and disposal work is comprised of comparatively low-cost projects—particularly submarines—with limited resource demands compared to a nuclear-powered aircraft carrier like CVN 65 [USS Enterprise], a multi-year project with a cost that will potentially exceed $1 billion," noted a 2018 Government Accountability Office report. A nuclear sub cost about $26 million to scrap, GAO estimated.

The problem isn't that the Navy doesn't have experience dismantling nuclear-powered ships. The US Navy launched the first atomic submarine — the USS Nautilus — in 1954. (The first nuclear-powered surface ship was the Soviet icebreaker Lenin, launched in 1957.)

Since 1990, the Navy has inactivated — which entails removing the nuclear fuel and reactor compartment — more than 130 nuclear-powered ships, according to the GAO. In addition to carriers and subs, the Navy also built nine nuclear-powered cruisers in the 1960s and 1970s. The last of them, USS Arkansas, left service in 1998.

But scrapping a 100,000-ton aircraft carrier is a much more ambitious project. To say the process is complicated — both technically and bureaucratically — would be an understatement.

The Environmental Protection Agency has an entire webpage describing how the process should work.

The Department of Defense "maintains and monitors the radioactive parts," according to the EPA. The parts are shipped by barge — under Navy or Coast Guard escort — to a disposal site, while complying with Department of Transportation regulations. Some reactor parts will be stored in special vaults by the Department of Energy at its facility in Hanford, Washington.

"There is no reason civilians should ever encounter any exposure risk from nuclear submarines or the disposal sites that store the dismantled reactor compartments," the EPA says reassuringly.

As ships built almost two decades apart, the Enterprise and Nimitz are different designs. Their disposal requirements will be different, a Navy spokesman told Breaking Defense. But how the US government handles their demise will serve as a template for other nuclear-powered warships. The Navy has nine other Nimitz-class and one newer Ford-class carrier in service, and they will have to be scrapped eventually.

Yet six years after decommissioning the Enterprise, the Navy can't even decide who will scrap it. Navy shipyards are so overworked that they can't provide required maintenance for active warships, let alone take apart obsolete ones.

In 2022, the Navy announced that the Enterprise would be scrapped in a private shipyard rather than at the Puget Sound Naval Shipyard. The private shipyard will probably be in Alabama, Texas, or Virginia, according to a draft environmental impact statement posted on a special Navy carrier disposal website.

However onerous or complicated it is, the Navy will have to devise a workable process for scrapping giant nuclear-powered aircraft carriers. In addition to its 11 active carriers — six of which, including Nimitz, have been in service for more than 30 years — the Navy plans to build at least four more Ford-class ships, one of which will be also be called Enterprise.

Whichever way the scrapping process for Enterprise and Nimitz goes, it will be a goodbye for two of the most storied warships in American history.

Enterprise symbolized US technological prowess as the Cold War heated up in the 1960s. The USS Nimitz was an icon of the 1980s and the first of a class of carriers that has served all over the world in the post-Cold War era. Their passing will mark the end of an era.

Michael Peck is a defense writer whose work has appeared in Forbes, Defense News, Foreign Policy magazine, and other publications. He holds a master's in political science. Follow him on Twitter and LinkedIn.