This fall, Exelon plans to retire the Dresden nuclear power plant in Illinois after more than 51 years in operation, one of the longest life spans any commercial nuclear power reactor has ever achieved. The only older operating power reactor in the country, unit 1 at Exelon's Nine Mile Point plant, came online in 1969, a few months before the older of the two units at Dresden. 

Now, nuclear regulators, industry groups and power plant owners have begun talking about the possibility of doubling these record run times and operating some U.S. nuclear plants for up to 100 years. 

The discussions cut quickly followed the 2019 and 2020 Nuclear Regulatory Commission approvals of the first licenses for reactors in Florida and Pennsylvania to operate for 80 years, which would themselves be unprecedented milestones. According to industry experts, with state governments, utilities and corporations setting emissions reductions targets 20 to 30 years out into in the future, the nuclear industry is experiencing pressure to tackle the technical challenges around long life extensions sooner rather than later.

Many of the net zero emissions goals "go to 2050 and beyond. The reality is, some of the reactors today will shut down in 2050 if they don't go beyond 80 years," nuclear industry consultant and UxC President Jonathan Hinze said. "Keeping what you've got is always the first option, rather than replacing it."

For example, Duke Energy has committed to a goal of net zero emissions by 2050. Duke's three-reactor Oconee nuclear plant in South Carolina, at 2,500 MW, is the largest single power plant in Duke's generation portfolio and makes up over 12% of Duke Energy Carolinas' self-owned power capacity. Duke has declared its intent to ask the NRC to extend the plant's 60-year licenses so it can operate for 80 years, but if granted, those new licenses would expire in 2053 for two of Oconee's reactors and in 2054 for the third.

Replacing nuclear plants before their licenses expire may not be on the table at all, due to high costs and competitive pressures from other power sources. The new units under construction at Southern Co.'s Vogtle plant in Georgia, which would be the first new nuclear generation constructed in the U.S. in three decades, are still incomplete after eight years of construction, numerous delays and billions of dollars in cost overruns. 

Those challenges create urgency to keep existing nuclear plants running despite the long timelines for some of the corporate and government carbon reduction goals, experts say.

It is important sooner rather than later to figure out if existing plants can be licensed to operate beyond the 2050s, according to Brett Rampal, director of nuclear innovation for the Clean Air Task Force. "To decarbonize our electric grid in the next 15 years is a huge lift. Existing nuclear power is more than half of U.S. clean electricity and I don't want to ask questions about a clean electricity grid without these existing nuclear assets," he said.

The Nuclear Regulatory Commission first publicly addressed the possibility of licensing nuclear plants for 100 years of operation at a meeting in January. The staff asked in a request for comments if it should "begin to consider the potential technical issues and the development of guidance documents to support license renewal to authorize operation for up to 100 years, and if so, when." The staff is still reviewing feedback from the meeting and has not made any decisions, NRC spokesperson Scott Burnell said.

From 80 to 100?

The NRC has been tackling technical questions and research around the long-term aging of nuclear reactor components as part of its review of requests from plants to operate for 80 years. If any nuclear plants attempt to operate for 100 years, "I think it would be some subset" of these plants that have received or are requesting approval for 80-year licenses, according to Doug True, the chief nuclear officer at the Nuclear Energy Institute (NEI), the main U.S. advocacy organization for the industry.

Four reactors — two at NextEra Energy subsidiary Florida Power & Light's Turkey Point plant and two at Exelon's Peach Bottom plant in Pennsylvania — have already received approval from the NRC to operate for up to 80 years, while six more — four at Dominion Energy's North Anna and Surry plants in Virginia and two at NextEra Energy's Point Beach plant in Wisconsin — have asked for license extensions to 80 years.

But all of these nuclear plants, like Oconee, would have to retire in the early 2050s if the NRC does not allow operation beyond 80 years. These reactors, including Oconee, add up to about 11.4 GW, which is over 11% of total U.S. nuclear capacity, based on U.S. Energy Information Administration data.

Another way to replace retiring nuclear capacity is by building new types of reactors, like small modular reactors, molten salt reactors or other technologies lumped under the "advanced reactors" label, that have the potential to be cheaper and easier to build than conventional large nuclear units, like those at the Vogtle plant.

But none of the proposed advanced designs has yet been licensed, and "first-of-a-kind" plants based on these technologies are years away, with fully commercial "nth-of-a-kind" designs down the road further still.

"Unknown unknowns"

If the NRC decides to push forward with developing guidance for 100-year licenses, some of the most complicated questions that will have to be tackled are around how nuclear plants can safely operate at advanced ages. The Electric Power Research Institute (EPRI) has been studying how everything that goes into a nuclear plant, including cables, pipes, concrete and myriad other components, can hold up under exposure to prolonged radiation, and how plant operators can know when a component needs to be replaced.

The question of safety at 100 years is not substantively different from the question of safety at 80 years of operation, according to Heather Feldman, director for innovation at EPRI, and in fact, EPRI has "removed that artificial constraint of time" in its research into nuclear plant aging, she said.

Feldman compared it to a car oil change: instead of getting the oil changed every three months, many drivers will instead get their oil replaced when a parameter has changed, like the condition of the oil has degraded because a certain amount of miles was put on the car. To apply that example to a nuclear plant component, instead of recommending that a cable in a nuclear plant be replaced on a specific schedule, the cable might be replaced only when certain signs of degradation appear.

Others are skeptical, however, about how certain regulators can be about safety if they are looking so far out into the future. "Would you get on a 747 that is 100 years old?" asked Allison Macfarlane, who served as chairman of the NRC from 2012 to 2014 and now directs the School of Public Policy and Global Affairs at the University of British Columbia. Her concerns are with the number of "unknown unknowns" — safety issues that regulators and plant operators are not even aware could pose problems — that may surface as parts of a nuclear plant are exposed to radiation at lengths of time never before observed. For example, a nuclear plant typically has miles of buried cables and piping, and inspecting them can be difficult due to the costs of digging to access them, Macfarlane said.

NEI's Doug True said that the NRC is considering relicensing plants beyond 80 years because the regulators "recognize that these plants are robust and can operate for that long. There is no reason that 80 years is the end." But whether or not plant owners will choose to seek 100-year licenses is still unclear and will primarily come down to economic reasons, not safety or technical concerns, he said.

Even though these decisions to relicense or not may take years to happen, the potential climate benefits are too big to ignore now, according to Josh Freed, senior vice president for the climate and energy program at Third Way, a centrist think tank. "It's too early to speculate what the end of existing life is for nuclear reactors," he said. "Let's have the options. We will find out when the time comes what works and what doesn't. It's too much of a risk to the climate to rule anything out."