The change of fortune has come so fast that the Nuclear Regulatory Commission, which had almost forgotten how to accept an application, has gone into a frenzy of hiring, bringing on hundreds of new engineers to handle the crush of applications.

Many problems could derail the so-called nuclear revival, and virtually no one believes all 34 proposed plants will be built. It is still unclear how many billions they would cost, whether the expense can be financed in a troubled credit market, and how the cost might compare with other power sources.

But experts who follow the industry expect that at least some of the 34 will be built.

Given rising public concern about global warming and a recent history of reliable operation among nuclear plants, “the climate for introducing new plants is probably the best it’s been since the industry started canceling plants” 30 years ago, said Brian Balogh, a history professor at the University of Virginia. Unlike most types of power generation, nuclear plants do not emit the gases that cause global warming, once they are completed.

In the United States, orders for new reactors essentially ended in October 1973. That was also the month that the Arab oil embargo began, inaugurating an era of economic problems that drove up construction costs and suppressed demand for power. In the end, more than 100 nuclear reactors, some in advanced stages of construction, were canceled, and tens of billions of dollars were squandered.

On top of that, the Three Mile Island accident in 1979 and the Chernobyl explosion in 1986 made nuclear power a hard sell. And cheap turbines were developed to burn natural gas to generate electricity. By the 1990s, even some nuclear plants that had been running for a few years were deemed too costly and were closed.