Watts Bar is a meandering reservoir in east Tennessee, dotted with fishing resorts, church retreats, and a Boy Scout camp. It's also home to a nuclear power plant, one that is as representative of the American experience with nuclear energy as the lake is representative of American summer.

Reactor 1 at Watts Bar was the last American nuclear reactor to come online in the 20th century—it began producing power in 1996, 23 years after construction started in 1973. The second Watts Bar reactor is scheduled to come online soon, making it the first new U.S. reactor of the 21st century. 20 years have passed.

The Tennessee Valley Authority, which owns and operates Watts Bar, stopped construction on Reactor 2 in 1985, when energy prices fell too low and construction costs rose too high to justify continued investment. Construction finally resumed in 2007 with a plan for Watts Bar 2 to come online in 2013. Then the deadline shifted to November 2015. As of November 2015, Watts Bar 2 is expected to begin commercial operation in September 2016. Meanwhile, this re-start phase of the project alone has gone over budget by more than $2 billion. It is widely touted as a success story.

Tennessee Valley Authority

This is the face of nuclear development in the United States today: slow, over-budget, economically untenable. Yet the dream of a nuclear-powered society is still alive. Nationwide, we get about 20 percent of our electricity from nuclear. It produces the lion's share­ (64 percent) of our clean energy, provided that by "clean," you mean anything but fossil fuels. In addition to Watts Bar 2 there are four other reactors currently under construction in this country, signaling that perhaps America has a renewed interest in going nuclear.

Look abroad and there's even more reason for nuclear advocates to be hopeful. China is leading a renaissance in nuclear energy: Today that country gets only 2.5 percent of its electricity from nuclear, but it has 21 reactors under construction, more in the works, and a growing business selling reactors to countries like Pakistan, Argentina, and the United Kingdom. This vigor marks a level of nuclear investment the world has not seen since the heyday of American atomic enthusiasm, when 58 reactors came online between 1965 and 1980.

Watts Bar October 1978 Tennessee Valley Authority

Nuclear energy could make a comeback in this country, powering a future that's less dependent upon coal and natural gas. Or nuclear energy could fade into oblivion, one shuttered power plant at a time—after all, 43 percent of Americans still would say "good riddance" to nuclear. What happens next depends on whether nuclear boosters can solve the three key problems that have plagued American nuclear power, and left places like Watts Bar in perpetual limbo.

COST

"Let me just give you a bald fact," says J. Doyne Farmer, an Oxford University professor of math and complexity economics. "Nuclear power and solar photovoltaics both had their first recorded prices in 1956. Since then, the cost of nuclear power has gone up by a factor of three, and the cost of PV has dropped by a factor of 2,500."

It's really expensive to develop nuclear power plants, and first big reason why is sheer size. They are huge. The average generating capacity of coal plants in the United States is 547 megawatts. That's in the same ballpark as America's smallest nuclear reactor, at Fort Calhoun in Nebraska, which has a capacity of 479 megawatts. Meanwhile, the largest single nuclear reactor in the United States is the Grand Gulf Nuclear Generating Station, with 1,500 megawatts in generating capacity.

Simply put, nuclear power plants can generate tremendous amounts of energy. But while it's expensive to develop any kind of energy infrastructure, the cost of nuclear energy has not fallen over time. There is no Moore's Law in play here. The high cost of nuclear development—and the fact that it doesn't seem to get cheaper—is why it made sense to simply abandon Watts Bar 2 in 1985, even though it was 80 percent completed at the time. The high cost also explains why it's difficult to coax electric utilities into a new nuclear building boom, even though some new financial incentives and regulatory changes that have streamlined the licensing process.

The constant high costs is not a problem unique to nuclear energy. Most technologies don't actually get cheaper over time, Farmer said—we only think they do because whenever we are lucky enough to stumble across one that does, like computer processors, we restructure our entire economy around them. Coal-fired power plants haven't gotten much cheaper over time, either, Farmer said, despite their ubiquity. The cost of coal generation has fluctuated up and down for 150 years with no clear trend.

Nor is the nuclear cost problem unique to the United States, Farmer says. China appears to be lowering the cost of nuclear development, but it's hard to say whether that appearance reflects reality. The Chinese nuclear industry is not a free market, says Keith Florig, research scholar at the University of Florida's Warrington College of Business. The steel for their reactors comes from state-owned mills and is processed in state-owned machining operations. There are price controls and forced relationships at every level.

America can't build reactors that way. But there are some lessons the U.S. could learn from China that might reduce development costs here. Every nuclear power plant currently operating in the United States is a bespoke product, as unique and hand-detailed as a Frank Lloyd Wright house. China, meanwhile, is turning out something more akin to prefab housing—cheap to make, easy to modify, and quick to go up. Not only are China's reactors using a standardized design with some modular parts, but the entire construction process is performed by a dedicated crew that travels from reactor site to reactor site. "I call it the Barnum and Bailey traveling circus show," says Charles Forsberg, executive director of MIT's nuclear fuel cycle project. While American construction crews are almost always new to nuclear, the Chinese teams learn from past experience to get faster, and better.

For all these reasons, building a reactor in America is a colossal risk. "It's a bet-the-whole-company proposition," says M. Granger Morgan, professor of engineering and public policy at Carnegie Mellon. In 2014, the Energy Information Administration estimated that building a nuclear power plant could cost more than $12 billion, and it would be at least six years before it could start producing power and you could start making any money . The only reason that the Tennessee Valley Authority can finish Watts Bar 2 now is that it is a vertically integrated utility–a single entity that owns generation, transmission, and distribution—and can set a rate for the electricity it produces that guarantees it will make back its investments. Before the 1990s, almost all American utilities were fully vertically integrated. Today, they're most common in the Southeast and the Northwest. All five of the nuclear reactors under construction in the United States are being built by vertically integrated utilities.

INNOVATION

Every power plant now operating in America, every one under construction, every one currently in the pre-construction phase—they're all are based on the same design. Enriched uranium creates fission reactions, which produce heat, which boils water, which turns a steam turbine. The fission reactors are cooled with water. Stopping the reaction requires the command of an operator.

But there's more than one way to build a reactor. Nuclear reactors could be smaller. They could be safer. Some of the new designs are more efficient than light water reactors, enabling them to capture more energy from nuclear reactions and run on fuel that operators of a light water reactor would have to throw out as "spent". They could be built on an assembly line, which would make them cheaper. "We assumed like many others that all these technologies were perennially 30 years away," says Joshua Freed, vice president for clean energy with Third Way, a Washington think tank founded by former Clinton Administration staffers, which aims to promote the perspective of the moderate left. "But they're not only possible, they've been built before."

Charles Forsberg is part of a team working on a project that would pair a fluoride-salt-cooled reactor with a natural-gas-powered turbine in a combined-cycle system. The project has its origins in 1950s-era plans for a nuclear-powered jet engine, one meant to power a plane with unlimited range that could fly across the ocean and bomb Moscow. "They spent $3 billion on it and then the ICBM came along and killed it off," Forsberg said.

In a salt-cooled reactor, nuclear fuel sits in a reactor core filled with molten salt. This salt absorbs the heat of the nuclear reactions and circulates through a heat exchanger, where the heat is transferred to the electricity generating system. These reactors operate safely at a much higher temperature than water-cooled reactors can, which means that you can get more heat to the generator with less nuclear fuel.

Because of that, the fluoride-salt-cooled design could be smaller and cheaper than standard light-water-cooled reactors. It could also be safer, because most designs don't require electric pumps to circulate coolant, and, unlike water, the coolant can't boil away. (In a typical light-water reactor, If the pumps break or the water is lost, the nuclear fuel could overheat and melt down as it did at Fukushima Daiichi in 2011.) And as part of a combined cycle, the reactor could provide constant baseload electricity as nuclear power plants do today while also preheating air for a natural gas turbine, providing fluctuating power to match the highs and lows of solar and wind generation. That means you could make more money off this kind of power plant, further lowering the cost per kilowatt hour of electricity generated.

The Asahi Shimbun/Getty Images

Maybe Forsberg's project is the future of nuclear energy. Maybe it's not. The point is that there are dozens of new reactor designs out there, most of which remain untested while the U.S. builds and operates only old-fashioned reactors.

"We don't know the answer today," says Per Petersen, professor of nuclear engineering at the Universtity of California, Berkeley. While the federal government has created financial incentives for utility companies that want to build new light-water reactors, it isn't investing heavily in new designs. Instead, he'd like to see a private competition to build a better reactor, sort of like what happened when NASA tapped private companies to repace the space shuttle and sparked a space race between the likes of Boeing and SpaceX. "The administration and Congress made a bet that if we create an environment where startups and entrepreneurs are given access to resources, required to have skin in game, there's some possibility that substantially better tech could emerge."

Opening up the nuclear industry means making it easier to test and license new reactor designs, Petersen said. It's been difficult for start-ups to get access to the technical expertise and facilities of the national laboratories, for instance. In November 2015, the Obama Administration announced a new program that would allow companies to apply for small-business vouchers. The vouchers are sort of like a company store scrip. Each one is worth between $50,000 and $300,000. They can only be spent at national labs, where companies can exchange them for services like prototyping, materials testing, and modeling. The government has set aside $20 million to fund the program.

But, overall, the entire licensing and regulatory process is tied to the needs of existing light-water designs. Historically, that made sense. But, Petersen and Freed say, it's now making it almost impossible to earn a license for anything else.

For example: Ordinary light-water reactors operate under high pressure, and thus must be built inside a containment structure for safety reasons. However, the government's rules require an expensive containment structure for all nuclear reactors—even designs that would operate at normal atmospheric pressure and wouldn't need one. Some companies have turned to China in response. TerraPower, a start-up partially funded by Bill Gates, just signed a deal to develop and test a new kind of reactor in that country.

THE PR PROBLEM

New, better reactor designs and cheaper-to-build nuclear plants won't mean much if nuclear power in America can't solve it's image crisis.

"It's hard to imagine an industry that has been more elitist, and that has done such a lousy job of engaging with the public," Granger Morgan says. "Implicit in the message [has] always been 'Accept it, you dumb schmuck.' That goes over like a lead balloon."

Let's start with this fact: In some ways, the nuclear critics are indisputably correct. There is still no real plan for what to do with nuclear waste, for instance. Officially, we're supposed to be transferring spent nuclear fuel to a long-term storage facility at Yucca Mountain, Nevada. In reality, funding for that project was cut off in 2011, the facility left incomplete. As a result of this NIMBY battle, spent nuclear fuel sits in ostensibly temporary casks on site at all 61 operating nuclear power plants, as well as another 13 locations that include decommissioned power plants. Each of those sites requires its own expensive security to protect the nuclear materials, which means paying guards even if the power plant is no longer working.

John Locher/AP

"It's just a dumb thing," Morgan says. "We should be doing above-ground storage. But we shouldn't be doing it at 100 different nuclear reactor sites." Nuclear boosters like Third Way see new reactor designs, some of which could run on spent fuel, as the best way out of this problem. But those still only exist on paper.

And then there is the risk of catastrophe. After all, the best-known nuclear power plants are the ones that melted down: Three Mile Island, Chernobyl, Fukushima. It's hard to argue with the sense that when plants aren't well regulated and things go bad, they go very bad. Here, the industry hasn't done itself any favors with its resistance to oversight, which fuels nuclear anxiety in the public. That fear, in turn, raises the cost of nuclear development, as activists and lawsuits stall construction.

"There was an adversarial attitude taken in terms of all interaction to the NRC [Nuclear Regulatory Commission]," Per Petersen says. "To minimize transfer of information. Essentially to not cooperate with regulatory process." That attitude, Petersen said, contributed to the high cost of nuclear power. The plants that fought regulation weren't very reliable. Through the 1980s, many were operating at capacity factors of 65 percent–meaning they were only producing about 65 percent of the electricity they were capable of making.

Nuclear power's PR problem is yet another way it's different for China. One of the reasons that country has been so successful in its nuclear development plan is that it has effectively ignored the prospect of public opposition. Keith Florig, a risk management researcher with the University of Florida's Warrington College of Business, interviewed Chinese energy officials and found that they seemed to be unaware of the problems the West has had with negative public opinion. Even today, he says, they really haven't started dealing with it. This despite the fact that protests forced China to scrap plans for a uranium processing plant in July of 2015, a first for China.

ATOMS OF HOPE

Other countries have found ways to change the conversation and get nuclear unstuck. Sweden, for instance, is one of the few places moving forward with plans for long-term geologic storage of nuclear waste, thanks to a decades-long process that brought in communities to decide the site rather than trying to force a proposal. The towns near the potential sites even had opportunities to veto. Officials from the Swedish Nuclear Fuel and Waste Management Company visited the locals one-on-one in their homes to have conversations about fears, risks, and technology. In 2009, 79 percent of the people who live in Osthammar, where the facility will be built, supported the project .

Changing the culture of nuclear is as vital as changing the technology. If that seems unlikely in the United States, then consider what happened to the relationship between nuclear power plant operators and the NRC. Over the course of the 1990s, Petersen said, companies began to realize that the most economically stable plants were also the ones most cooperative with regulation. The realization that stringent safety standards might have a positive impact on operating efficiency—and, thus, the bottom line—shifted the entire industry. For example, take unplanned automatic scrams, which are shutdowns caused by operational problems. In 1980, the U.S. saw 7.3 of these per nuclear power plant. By 1997 there were almost none. Industrial safety accidents also fell by 80 percent during the same period of time.

By the early 2000s, compliance was up and outages were down. The fleet of nuclear reactors in the U.S. now operates at capacity factors of 90 percent or more. When Watts Bar 2 finally comes online, it will owe its existence to this change. "It's assumed you can operate with similar levels of reliability," Petersen said. "That's the only reason people think about expanding nuclear energy today."

What's more, Americans' opinion on nuclear remains complex. According to Gallup polling, American opinion on nuclear has fluctuated over time. The high point was in 2010, when 62 percent favored its use. Support has fallen since the 2011 Fukushima accident, but in 2015 a slim majority – 51 percent – were still in favor. Those numbers change when you ask about future nuclear development, though. The 2015 Gallup poll found only 35 percent want an increased emphasis on nuclear power in our energy mix, with an additional 28 percent who wanted to keep the emphasis the same. By contrast, 79 percent of Americans want more emphasis on solar power.

Mark Zaleski/AP

If you look at national polls of all Americans, younger generations tend to have less support for building new nuclear power than their elders. The Pew Center found that fewer 18-29 year olds want to build new reactors than 30-49 year olds. And fewer of them support new development than 50-64 year olds.

But younger people are also more likely to accept that climate change is happening and be more concerned about doing something to stop it. Joshua Freed and Third Way think they will be able to harness that and turn it into support for nuclear energy. In their own research, he says, Third Way found that young environmentalists—those under 45—were more supportive of nuclear power than their older peers. He is hoping that's a sign younger Americans may be convinced that a nuclear renaissance is one of the few options to keep the lights on without heating our rapidly warming Earth even further. "The urgency around climate change is increasingly overtaking and subsuming any concern they might have about nuclear," Freed says. "They're much more open to the idea of nuclear being part of the solution."