Calvin Nolt (in mid flip) and Jonathen Whorf weren't born when one of the two reactors at Pennsylvania's Three Mile Island Generating Station partially melted down in 1979, resulting in America's worst nuclear accident. To the boys, the steam-spewing cooling tower that serves the plant's one active reactor is nothing more than "a giant cloud maker." While environmentalists don't hold quite as benign a view of nuclear reactors, some have been reconsidering their benefits. Because they emit virtually no greenhouse gases, nuclear power plants may offer a way to slow global warming. Today they generate one-fifth of America's electricity, even though no new plants have been ordered in a quarter century.

That would include building reactors such as those at Kaiga Generating Station in a clearing in the jungled Western Ghats mountains about 20 miles (32 kilometers) inland from southwest India's seacoast. Coming upon the two 220-megawatt, pressurized heavy-water reactors is like stumbling into a thumping big factory in the middle of Yellowstone National Park. The region gets more than 15 feet (4.6 meters) of rain yearly, and its forest is home to increasingly threatened species. "Tigers? Yes, they are near. Panthers and king cobra too," says Anwar Siddiqui, senior manager for the Nuclear Power Corporation of India.

A country with reactors in such places must really like them. Amid a jumble of construction cranes and heavy concrete walls, two similar reactors are rising next to the first two, and another pair, more than twice as powerful, will likely join them in coming years.

Back near the Indira Gandhi center a 500-megawatt breeder reactor is under construction and set to start up in 2010. Four more are to follow by 2020. They are very efficient at manufacturing plutonium fuel from their original uranium fuel load, which greatly increases the amount of energy they produce. But critics worry that the plutonium could possibly get in the wrong hands.

In part because of proliferation concerns, the U.S. has sworn off such breeder reactors for the time being. But outside powers have little leverage over India's nukes. With few exceptions they are entirely homegrown. India gave itself little choice about going it alone. In 1974, it set off an underground nuclear explosion using plutonium surreptitiously diverted from a test reactor that Canada helped it build in the 1950s.

India became a nuclear pariah. Other countries suspended technical assistance, and Canadian engineers walked off a job in Rajasthan. The Indians finished the plant themselves.

They are now enthusiastic masters of all things nuclear. The uranium fuel in Kaiga's reactors comes from mines west of Calcutta; workshops in the south provide the plant with gleaming, 65-foot (20-meter) high, 110-ton (100-metric ton) steam generators that drive electric dynamos. Control systems, zircaloy fuel tubes, and 22-ton (20 metric ton) reactor components arrive from Hyderabad.

"We can't go back, we can only go forward," said Swapnesh Malhotra, a spokesman for India's atomic energy department. "Life depends on energy, and I ask, where do we get it? We will get it somewhere."

Meanwhile, the U.S. tiptoes ahead. In the nation that gave it birth, nuclear power may get its second wind in a mowed field outside the quiet town of Port Gibson, Mississippi. The field, close by a reactor that has been operating since 1985, is part of the Grand Gulf Nuclear Station, owned by a subsidiary of Entergy Corporation, the fourth largest electricity producer in the U.S.

Entergy hopes to fire up a new nuke here by 2015. First, General Electric (GE) and Westinghouse, the nation's only reactor makers, must finish detailed designs for machines they've been promoting as more foolproof and easier to operate than those they built decades ago. Formal license applications could be filed by 2008. Federal regulators might chew on them until 2010.

To expedite the process, Entergy organized a consortium in 2004 of nine utility companies plus GE and Westinghouse. The consortium, named NuStart, hopes to test new Nuclear Regulatory Commission procedures that will grant a combined construction and operating license to avoid the interminable hearings of the 1960s and '70s.

Only then, if GE, Westinghouse, or both, get approval, will Entergy and other NuStart members decide on actual orders. Construction would take four to five years.

That's if there's money. Congress last year passed an energy bill that guarantees loans made by investors and includes a subsidy of up to six billion dollars for running the first new plants. But the industry insists that it can't get private financing for construction of the plants without government loan guarantees. Environmentalists like Speth consider the nuclear industry mature enough to sink or swim without federal assistance—and with vigilant regulation.