DELTA, Pa. — The beige consoles and pale walls of the Peach Bottom Atomic Power Station control room are festooned with knobs, dials, and lights from a different era. The operators joke that they still consult paper manuals in three-ring binders.

No digital help screens here.

The system that controls the two giant Peach Bottom reactors in York County is largely analog, installed when the company then known as Philadelphia Electric Co. — now Peco Energy — launched the units in 1974. The current owner, Exelon Generation, says it expects to fully digitize the control room in the next decade, part of an ongoing effort to modernize a plant that supplies electricity to 2.7 million homes.

The Peach Bottom plant, 60 miles west of Philadelphia near the Maryland border, is operating under a 20-year extension from its original 40-year license, like many of America’s aging fleet of nuclear reactors. Last year it became one of the first plants to apply for what the Nuclear Regulatory Commission calls a “Subsequent License Renewal” — that would permit the reactors to run through 2053 and 2054, when they turn 80 years old.

As the construction of new nuclear power plants fell off after the Three Mile Island accident in 1979 — the average age of a U.S. reactor is nearly 40 years old — older units like Peach Bottom are being pressed into longer service, and some worry that safety will suffer.

A lot of life left

“There’s still decades more carbon-free generation than we can get from today’s nuclear facilities, and these facilities can serve as a bridge to the next generation of carbon-free nuclear generation in the U.S.,” said John Kotek, vice president of policy development and public affairs for the Nuclear Energy Institute.

But skeptics say that nuclear plant owners, ever alert to degradation from a harsh operating environment, will be challenged to keep geriatric power plants operating into their seventh and eighth decades. Market forces, driven by competition from inexpensive natural gas plants and renewable power, are not working in nuclear energy’s favor.

“There is this rush of license-renewal applications for the 60-to-80-year period that are pushing beyond our knowledge of the impact of aging,” said Paul Gunter, director of the reactor oversight project for Beyond Nuclear, an antinuclear group that has challenged Peach Bottom’s license extension.

Edwin Lyman, senior scientist with the Union of Concerned Scientists, which is wary of nuclear power, said reactor owners will be required to conduct more frequent inspections, maintenance, and repairs of aging reactors while facing increasing pressure to keep costs low. “It’s not clear to me that can be done at the same time compatibly,” he said.

Profitability of U.S. Nuclear Power Plants

More than a third of existing nuclear power plants in the U.S. are unprofitable or are scheduled to close, according to a recent report, accounting for 22 percent of the country's total nuclear capacity. In the Mid-Atlantic states, 25 percent of the plants that are part of the PJM Interconnection grid are marginally profitable. In the map below, circle sizes are proportional to a plant's operating capacity.

SOURCE: Union of Concerned Scientists

The nuclear industry has invested billions of dollars in new safety and security features after the devastating Fukushima nuclear disaster of 2011 and the accident 40 years ago this month at Three Mile Island Unit 2, just 36 miles up the Susquehanna River from Peach Bottom. It has invested billions more to improve efficiency and output. Most nuclear plants now operate year-round, near full capacity — there is not much more juice that can be squeezed out of existing designs.

With just two new U.S. reactors under construction, the industry increasingly must rely on keeping its 98 existing plants operating into the middle of the century.

Coexisting with climate activists

As producers of 60 percent of the nation’s carbon-free energy, the industry is seeking common ground with climate activists, who are pressuring lawmakers to set aggressive targets to reduce emissions of greenhouse gases. It’s not always a warm embrace. The Democratic authors of the New Green Deal initially excluded nuclear power from the equation, saying they wanted to transition to renewable energy alone.

But nuclear-power advocates say all sources of zero-carbon energy will be needed if the nation transitions away from fossil fuels. Peach Bottom’s reactors produce nearly six times as much carbon-free energy as all of Pennsylvania’s wind and solar generators combined, and there are no new wind farms planned in Pennsylvania.

“If you really believe in climate change, this is the solution, at least an intermediate solution,” said Patrick D. Navin, Exelon’s site vice president at Peach Bottom. “You can’t get there if you start shutting these things down.”

The Nature Conservancy, in a 2018 report on sustainability, endorsed an increase in the share of nuclear power, along with a bigger build-out of renewable power, to dramatically reduce the dependence on fossil fuels by 2050. The transition not only reduces carbon dioxide, it said, but emissions of other pollutants and particulates that affect public health.

Peach Bottom currently is profitable, which differs remarkably from Exelon’s Three Mile Island Unit 1, the aging reactor near Harrisburg. Exelon is threatening to close Unit 1 this year, without some kind of ratepayer subsidy. Exelon’s Three Mile Island reactor is next to the infamous Unit 2, dormant since the 1979 accident, which is owned by First Energy Corp.

The General Assembly is expected to take up legislation soon to add nuclear power to the state’s Alternative Energy Portfolio Standard, which mandates a portion of all power consumed in the state be derived from renewable and alternative energy sources. But until details of the proposed subsidy are clarified, the potential cost to ratepayers is unclear.

The TMI effect

If the state does not come to its rescue, Exelon says, it will shut down Three Mile Island Unit 1 in September, an irrevocable decision. The Exelon reactor would then be permanently decommissioned, along with Unit 2.

The Three Mile Island accident, though it caused only a small radiation leak and no documented health issues, dramatically reshaped the landscape for nuclear energy. The partial meltdown of Unit 2 destroyed a new nuclear reactor, and shook public confidence in nuclear energy.

The accident exposed weaknesses in reactor design and oversight, resulting in new regulations and safety features that added time and expense to building plants. In the decade after the 1979 Three Mile Island accident, operators canceled plans for 62 reactors, though the industry blames high borrowing costs and flattening electricity demand for the cancellations. Only one new reactor has begun commercial operations in the last 20 years. Two Georgia reactors are the only units under construction, and they have been plagued by cost overruns.

The nation’s 98 operating reactors include nine in Pennsylvania and three in New Jersey. Exelon, the nation’s largest producer of nuclear power, has ownership stakes in 22 reactors. It co-owns the Peach Bottom facility with New Jersey’s Public Service Enterprise Group.

With each passing year, more reactors retire, sometimes prematurely. Exelon in September retired its Oyster Creek Generating Station in Forked River, N.J., after 49 years of operation. Like Three Mile Island, Oyster Creek was a single-unit plant with higher operating costs than multi-unit sites such as Peach Bottom, or Exelon’s Limerick Generating Station in Montgomery County.

Old, but more efficient

Despite the closures, the nuclear industry has maintained about a 20 percent share of the nation’s power supply — 39 percent in Pennsylvania and 45 percent in New Jersey -- by squeezing more power out of existing plants, and, it says, by operating them more safely and efficiently.

“In the ’70s, you might have seen capacity factors of around 60 percent for nuclear power plants,” said Kotek of the Nuclear Energy Institute. “This past year they exceeded 93 percent. Operators have proven year in and year out that running a plant safely is in their economic best interests.”

Exelon has poured $800 million in recent years into upgrading Peach Bottom Units 2 and 3 (Unit 1 was a small experimental reactor that shut down in 1974). The two units now produce 2,770 megawatts, about 24 percent more than when they started. Peach Bottom units often exceed 100 percent of their capacity — they essentially run nonstop the entire year — during years when they are not shut down temporarily for refueling.

Exelon says some of Peach Bottom’s older systems function perfectly well. The analog control room, for instance, still has one significant advantage over modern digital systems — it can’t be hacked. Exelon will include cybersecurity measures when it installs the new digital control systems “to make sure the system cannot be tampered with or unauthorized access into any of those systems," said Navin. The new controls should be in place before the current licenses expire in 2033 and 2034.

Is it safe?

Critics say they’re particularly worried about cracking, embrittlement, and corrosion of critical plant components in place for 60 years that can’t be inspected, such as hidden electric cables, structural concrete, and the reactor vessel itself, which contains the uranium fuel that creates heat that is converted into electricity.

The NRC rejected a suggestion that it should order a closer post-mortem of older nuclear power plants that are being decommissioned to measure the effect of prolonged operations, said Gunter of Beyond Nuclear. He suggested that Exelon should be forced to conduct an “autopsy” on the decommissioned reactor vessel at Oyster Creek, which is the same make and design as the Peach Bottom units.

“It would behoove the public health and safety for the cost of doing the autopsy to be borne by the operator that wants to extend the operation of a plant with the same design,” Gunter said. “We’re questioning the licensing process as if it’s some kind of crystal ball that they can manage aging.”

Exelon said that the Department of Energy and the Electric Power Research Institute have conducted research that supports extended plant operation.

“Exelon Generation regularly uses industry research, including analysis of materials from operating and decommissioned reactors, technical guidance and operating experience to develop and implement effective asset management programs,” spokesperson Liz Williamson said.

The NRC will also not consider changes in conditions since the plants were originally licensed, such as an increase in population density, or the effects of climate change, said Lyman of the Union of Concerned Scientists.

“All you can look at is whether there is an appropriate aging management program for those components that can’t be replaced, and you have to justify why they aren’t going to fall apart by the end of the extended period," he said.

Lyman also questioned Peach Bottom’s method of storing spent fuel in a water pool, citing a 2016 study he coauthored that estimated if a catastrophic earthquake caused the pool to drain, the densely packed fuel assemblies could overheat and catch fire, spreading radioactive material into the atmosphere.

“A spent fuel fire at Peach Bottom could force Boston to relocate, not to mention Philadelphia -- that’s how bad it could be,” said Lyman.

Post-Fukushima precautions

The NRC rejected the arguments, saying that the chances of such an accident were extremely remote and that the post-Fukushima improvements at the plant provide an added measure of security, including the ability to add more water to the spent fuel pool even if there is a loss of onsite power.

“Used nuclear fuel is safely stored at plants around the country, and post-Fukushima, all reactors have put measures in place to quickly add water to the pool and assure sufficient cooling, should that become necessary,” said Matthew Wald, a Nuclear Energy Institute spokesperson.

Exelon says it spent $700 million across its fleet, including $45 million at Peach Bottom, to build massive steel-reinforced bunkers called FLEX buildings on their sites to store emergency pumps and other equipment that can be quickly deployed during an accident. The industry also built two warehouses near airfields from which emergency equipment can be airlifted to any reactor in the country.