Thirty years ago, the nuclear energy industry in the United States seemed all but headed for the scrapyard. Now it's poised for a rebirth.
The impetus is climate change. Nuclear power is touted as the one major electricity source that's emission-free and reliable, able to generate massive amounts of power night and day, in wind and calm.
But hovering over nuclear's new dawn is an incident that began at 4 a.m. on March 28, 1979.
Deep within Reactor 2 at the Three Mile Island nuclear power plant along the Susquehanna River near Harrisburg, main water pumps failed.
At the end of a cascade of disasters, the reactor core melted down, though the containment walls were not breached.
The accident and other factors set the industry reeling. Costs rose. Plants were canceled.
The industry learned from that massive mistake, its proponents say. Chief among the lessons: a sharper focus on safety.
The Nuclear Regulatory Commission has applications from 17 companies to build 26 reactors - including a PPL proposal to build a plant in Berwick, Pa., near its Susquehanna plant.
New Jersey's PSEG is laying the engineering groundwork for an application to build a fourth reactor at its Salem-Hope Creek facility.
Without a shovel going into the ground, the industry has spent $4 billion and created 15,000 jobs as part of a ramp-up over the last few years, said Tom Kauffman, spokesman for the Nuclear Energy Institute.
"It's an exciting time," reported Kauffman, who worked at TMI from before the accident through 2000.
The Obama administration is not as bullish on nuclear as was that of George W. Bush. But Energy Secretary Steven Chu said in his confirmation hearing that the country needed "a continued commitment to nuclear power."
The renaissance, if that's what it is, also was prompted by stimuli in the Energy Policy Act of 2005, including loan guarantees and production tax credits.
These were key, said Larry Foulke, director of the nuclear engineering program at the University of Pittsburgh.
The cost of building a nuclear plant is staggering. It has risen from a projected $4 billion to $5 billion just a year ago to $6 billion to $8 billion now.
Meanwhile, the estimated time from proposal to operation has stretched to 15 or 20 years, largely due to post-TMI regulations, Foulke said.
Hardly an enticing prospect for Wall Street.
Most in the industry figure an initial wave of six to eight plants will actually be built. If they come in on time and within budget, more will follow.
Edwin Lyman, a nuclear expert with the Union of Concerned Scientists, is among the doubters.
He points to a new plant in Finland, hailed as one of the first and best examples of the "next generation" designs.
Instead, he calls it "a poster child for the failed promise" of nuclear. "It's already significantly delayed and vastly over budget," he said.
While environmentalists grudgingly accept the low-carbon argument for nuclear, they say the field is hardly without environmental costs.
Christopher E. Paine, director of the National Resource Defense Council's nuclear program, said the plants consume vast quantities of freshwater for cooling.
Uranium mining contaminates the land and groundwater. At the other end of the cycle is the spent fuel, now being stored in casks at reactor sites since the national repository at Yucca Mountain is all but dead.
"So simply promoting nuclear power as a panacea for climate change is an irresponsible policy," Paine said.
Then there's the potential - all but nonexistent, the industry says - for another major accident.
The industry says that, not having started a plant for more than 30 years, the nation has skipped a generation of designs. The new ones are far safer, Foulke said, because they incorporate novel features.
One example, he said, is a water tank at the top of a containment building, governed by a pressure valve. If the reactor below starts to lose cooling water, the pressure drops and the valve opens.
The debate is set against epic energy questions for the nation. Some experts predict we'll need 25 percent more electricity by 2030. Others say that ignores the potential of energy efficiency.
At the moment, the nation's 104 reactors contribute 20 percent of electricity production.
The United States also has 400 coal plants contributing the bulk of the juice: 48 percent.
But many are three decades old and struggling to meet current emission controls. The big question is what will happen when the government devises a plan for controlling their carbon dioxide emissions. Will the cost of retooling force many into retirement?
If so, the nuclear industry has been lobbying hard to be their replacement. At a Senate hearing on March 18, Marvin S. Fertel, president of the Nuclear Energy Institute, highlighted the "dramatic improvements in every aspect of nuclear plant performance over the last two decades."
The number of "significant reactor events" has dropped "to nearly zero," he said.
The industry has launched a team of "young nuclear experts" to crisscross the country extolling nuclear's benefits.
Last week, Natalie Wood, a Louisiana nuclear design engineer, and Chuck Conlen, nuclear business development director for a Michigan utility, met with students at the University of Pennsylvania.
"The environmental decisions we're making now are very important," Wood said.
PPL, based in Allentown, has proposed a new nuclear plant - Bell Bend - beside another PPL plant south of Wilkes-Barre.
PPL spokesman Joe Scopelliti said the company had not made a final decision. Financing is still uncertain.
But construction could begin in 2013 if approvals are received. It could be operational by 2018, according to the company.
PSEG officials liken that company's future to a three-legged stool - conservation, renewables, and nuclear.
To address the latter, the company is developing initial paperwork for a fourth unit at the Salem-Hope Creek site.
Ironically, that unit was to have been built in the 1980s, but it was canceled - primarily because of its escalating cost, said William Levis, president of PSEG Power.
They expect to submit the application in 2010. The NRC has two years to respond. Then there's another permitting process of about four years. So officials say it's unlikely the plant would be built for 12 to 15 years.
Meanwhile, the company will seek to extend the licenses for the other three units, which expire in 2016, 2020 and 2026.
Clearly, the nation's reactors are aging. So far, 51 of 104 reactors have been approved for relicensing. Most were treated as routine.
One that remains contentious - and has extended more than a year beyond the 30-month typical timeline - is Oyster Creek in Ocean County, N.J.
Owned by Exelon, it is the longest-running plant in the nation, coming on line nearly 40 years ago, on Dec. 23, 1969.
The debate centers on a steel liner surrounding the reactor. Environment New Jersey says it has deteriorated to an unsafe level. The company says it is sound.
The Atomic Safety and Licensing Board ruled for the company, but a citizen's group has filed an appeal with a commission that oversees the NRC. It has no deadline for ruling.
Exelon operates 17 reactors at 10 stations - including Limerick in Montgomery County, Peach Bottom in York County and Oyster Creek. Combined, they represent 20 percent of the nation's nuclear power capacity. The company has applied to build a two-unit plant in Victoria, Texas.
It has spent $23 million to prepare the application, but still hasn't decided whether to go ahead.
Meanwhile, the industry has been ramping up in other ways. With new technologies, most plants can now produce more power than originally thought. The NRC, which sets limits on maximum power levels, has been granting power "uprates" of as much as 15 percent at many plants, including Limerick, Peach Bottom, Salem and Hope Creek.
Today, TMI-2 is shut down. Exelon owns TMI-1, which in 2008 had one of its best years for operations, with no safety "events," said spokeswoman Elizabeth Archer.
But memories endure.
Jan Jarrett lives within 10 miles of the plant. In 1979, her children were in grade school. Sure, a lot has changed, but "I remember the chaos. . . children being evacuated from school and parents didn't know where they were going."
Today, she's president of the environmental group Citizens for Pennsylvania's Future, which has no stand on nuclear power.
But speaking as a parent, and now a grandparent, "nobody's ever going to convince me that can't happen again," she said. "That experience leaves me with concerns that I'll take to my grave."
Before the plumes of radioactive material wafted over farms, homes, schools and parks around Three Mile Island, waves of fear and dread spread through the region.
Within three days after the March 28 accident, people reported classic symptoms of radiation sickness - they vomited, they felt nauseous, their hair fell out. Pets and farm animals died unexpectedly.
But no radiation escaped until the fourth day of the crisis, say independent physicists with the Union of Concerned Scientists. That's when plant operators were dealing with a bubble of hydrogen that had built up within the reactor.
Fearing that it would explode through its containment vessels and spew radioactive contaminants over Pennsylvania, they deliberately released some water.
What they didn't know at the time was that the 100-ton uranium core had melted - and the water engineers released was full of dissolved radioactive gases that blew through surrounding towns with the wind.
Thirty years later, scientists still can't reach a consensus on what that exposure did to people's bodies. For the first 20 years, epidemiologists combed hospital records and interviewed thousands of people seeking connections between exposure and subsequent cancers.
The University of Pittsburgh's Evelyn Talbott led the biggest study, tracking more than 30,000 people for the first 20 years. She found a slight rise in the number of cancers of the blood and lymph systems, but said it was at the edge of statistical significance.
That left local residents wondering if cancer deaths among friends and relatives were caused by the accident, and whether they were carrying invisible radiation-induced cancer time bombs.
Two thousand people living within 20 miles of the plant filed a lawsuit, claiming they got sick from the radiation. A federal judge threw out 10 of those cases in 1996. The remaining plaintiffs were dropped in 2002.
Epidemiologists never studied cancer among the workers who carried out the 10-year-long cleanup, said Eric Epstein, chairman of the activist group Three Mile Island Alert. "That's a shame," he said.
Cancer can appear years after an exposure, so the epidemiologists wanted to keep tracking people, but research money has run out.
"We requested funding to do the study for another 10 years but have not received this," Talbott said in an e-mail. "So I have nothing to report."