If you walk the halls of Westinghouse or GE Nuclear, the top U.S. builders of atomic power plants, you’ll notice a buzz in the air–the first stirring of excitement since the 1970s. With many experts endorsing nuclear power as a clean replacement for coal-burning plants linked with climate change, nuclear players are gearing up to build more than 20 reactors, the first new facilities on U.S. soil in decade.

But roaming the same hallways, something else seems odd: There are practically no young people. After years lying dormant, the industry faces a dire labor shortage, and it will get worse during the next 5 to 10 years as thousands of aging workers drift off to golf courses and retirement homes. So plant builders and utilities are frantically searching for fresh talent. If the industry is to have any future, “young workers are the key,” says Howard J. Bruschi, a retired chief technology officer at Westinghouse Electric Co. who helped design the company’s newest reactor, a model that has been selected for 10 projects in the U.S.

The dilemma dates from the late 1970s, when skyrocketing costs began to chill investor enthusiasm for new plants. In 1979 a partial meltdown at Pennsylvania’s Three Mile Island doomed the industry’s optimistic vision of 1,000 atomic plants. Hiring stalled, and nuclear engineering programs at universities stopped churning out graduates. In short, a whole generation of nuclear workers went missing.

Today, the average age in the nuclear power sector is 48–one of the oldest of any U.S. industry. By 2010 about 27% of these workers will be eligible to retire–some 15,600 men and women. A further 7,600 or so are expected to exit the industry through turnover. That entire head count will need to be replaced to keep today’s fleet of 104 reactors humming.

Factor in projected growth, and the situation is even more serious. A substantially larger workforce will be needed by 2010, when the first of two dozen proposed reactors enters the long design and construction process. Overseas, 27 plants are under way, 62 are on order or planned, and an additional 130 have been proposed.

Even if only a fraction of those plants are built, the industry faces a “severe shortage of qualified workers,” according to the American Nuclear Society. “We’re probably getting 80% to 90% of what we need,” says Andy White, president and CEO of GE Nuclear Energy Inc. (GE ), whose reactors have already been selected for seven new U.S. projects.

NO EMISSIONS

It’s easy to see why some industry executives have started to fret. It can take years for new hires to master the industry’s complex procedures and absorb its safety-obsessed culture. “Five years ago, we didn’t dream we’d be building on this scale again,” says Amir Shahkarami, senior vice-president for engineering and technical services at Exelon Corp. (EXC ), the nation’s largest nuclear utility. Exelon operates 17 reactors today and is considering one new facility. “The aging workforce will result in a substantial loss of experience,” Shahkarami says.

Just how quickly colleges can crank out such highly specialized engineers remains a question. Some 34 nuclear engineering departments have closed since 1980, leaving just 29 today. By the late 1990s, the number of undergraduate students enrolled in such programs had fallen to fewer than 500 a year. Yet in the past several years, enrollment has again begun to rise. In 2007, total nuclear engineering majors in the U.S. will approach 2,000, predicts John Gutteridge, director of university programs at the Energy Dept.

Several factors account for renewed interest on campuses. Starting salaries in nuclear power jumped 6.6% last year, to about $54,600. In addition, today’s students are far more worried about global warming than the risks of a nuclear meltdown or the problems of waste disposal. Coming of age long after the disasters at Three Mile Island and Chernobyl, new hires in the power sector tend to regard atomic energy as a plausible solution to America’s energy woes–as did the engineers who built the first generation of nukes. The fact that plants emit no greenhouse gases is a huge plus. “I want to be sure my kids can plug in their iPods someday, too,” says Michelle Yun, a recent grad who joined Exelon as a licensing engineer last year.

DeLeah Lockridge, a senior engineer in Westinghouse’s services unit, is thrilled by the prospect of new plant construction. When she entered the company in 1999–one of the first new hires following a long freeze–Lockridge worried that nuclear energy might be a dying industry. “I didn’t expect to have the opportunity my instructors had,” she says. “Now, I want to build a plant.”