The U.S. is set to become the first nation to decide whether it is safe to operate nuclear power plants for 80 years, twice as long as initially allowed.

The majority of the nation’s 99 reactors have already received 20-year extensions to their original 40-year operating licenses.

Now, operators led by Dominion Resources Inc. want to expand the time frame further, potentially creating a precedent for an aging global fleet at a time when the economics of the industry are undergoing dramatic change.

Dominion said earlier this month it will request an extension from the U.S. Nuclear Regulatory Commission, which oversees the industry. The plan has already raised the ire of anti-nuclear campaigners who cite decades of wear and tear on the nation’s reactors, as well as the 2011 Fukushima disaster. The NRC will release a draft report next month outlining safety measures needed to extend the time line.

“The reality of life is the risks go up” as plants age, said Dave Lochbaum, director of the nuclear safety project at the Union of Concerned Scientists, a Cambridge, Massachusetts- based advocacy group. “If you don’t respond with more aggressive risk management, then you’re inviting disaster.”

An approval may determine the fate of the world’s oldest nuclear fleet, one that’s being battered by high operating costs, expensive safety upgrades and an abundance of cheap natural gas that is squeezing profits.

If allowed, Dominion’s Surry plant in Virginia will be the first to outlive the average human being in the U.S. with a life span of 78.8 years. A final decision will not come before the early part of the next decade.

“We are at the forefront,” Tina Taylor, a director at the Electric Power Research Institute Inc., said on Nov. 19. “As we demonstrate extending the licenses of plants and continue operating them, it sets a model for how people will do that around the world.”

Global nuclear retirements of as much as 144 gigawatts are expected by 2030, about 38 percent of current capacity, according to the International Atomic Energy Agency.

“We are probably ahead in terms of the renewal process just because of the age of the fleet in the U.S.,” Stephen Burns, chairman of the NRC, said last month in Washington.

Utilities are seeking extensions as some reactors shut early, unable to compete with the shale boom that has flooded the market with cheap and abundant supplies of natural gas. About 10 percent of U.S. nuclear output may be retired early, according to Moody’s Investors Service. Five reactors have been closed in the last three years, and three more are due to shut down by 2019.

The U.S. is the first country to set out a path for reactors to run to 80 years, Tom Kauffman, a spokesman for the Washington-based Nuclear Energy Institute, an industry advocate, said by e-mail.

“There are a number of safety issues with pushing these technologies twice beyond their original projected life span,” Tyson Slocum, Washington-based director of energy at Public Citizen, said by phone on Nov. 18. “You’ve seen a number of issues from Davis-Besse to Vermont Yankee where aging components triggered a variety of leaks.”

FirstEnergy Corp. found that corrosion nearly penetrated a steel reactor cap in its Davis-Besse nuclear station in Ohio in March 2002, while Entergy Corp. reported a small radioactive leak from pipes at its Vermont Yankee plant in January 2010. The company and the NRC said at the time that the leak did not pose a health risk.

The thinning of the U.S. nuclear fleet will hamper government efforts to tackle climate change, industry supporters say, since atomic power provided 63 percent of all carbon-free electricity in the U.S. in 2014.

“From a national policy standpoint, we’re going to be hard pressed to decarbonize at a meaningful rate if we take 1,000 megawatts a clip out of the stack,” Peter Keller, New York-based managing director at Berkeley Research Group LLC, said Nov. 3.

Lingering questions surround the durability of certain reactor materials and components, particularly the concrete and electric cables. There’s also the lack of a permanent home for spent nuclear fuel, currently stored on site in cooling pools or in dry casks.

“Just like a car and plane, power reactors get old year by year,” Yoshiaki Himeno, a professor at the Tokyo Institute of Technology, said by email. While owners refurbish parts and renew the systems, “the question is how long they can continue those repairs and renewals from economical and safety points of view.”