Nuclear energy is making a comeback, and a new exchange-traded fund from Van Eck Global, the Market Vectors Nuclear Energy ETF ( NLR), provides one of the purest plays on this sector available to U.S. investors.

Americans have long been suspicious about the safety of nuclear power plants. In the three decades since the 1979 meltdown at Pennsylvania's Three Mile Island, not one new nuclear power plant has been built in the U.S.

But concerns about global warming produced by fossil fuels are fueling demand for cleaner sources of energy. Nuclear power plants emit no greenhouse gases, while coal, the largest source of electric power generation, is a primary offender.

Nuclear energy also appeals to those who decry the U.S.'s dependence on foreign oil, since all of our uranium needs are mined here in the U.S. or in Canada, providing a secure supply and a form of energy independence.

Soaring demand for electricity and rising natural-gas prices aren't hurting the nuclear industry, either. According to the International Energy Agency, renewable energy sources -- including wind, sun, biomass and geothermal -- will only provide 6% of the world's electricity by 2030.

Giving an additional push to the industry is the Energy Policy Act of 2005, which gives generous subsidies, such as tax credits and loan guarantees, to fossil fuel alternatives, including nuclear power.

Market Vectors Nuclear Energy debuted on the American Stock Exchange last week. It tracks the DAXglobal Nuclear Energy Index. The ETF fund has an expense ratio of 0.65%.

More than half the ETF's assets are in uranium-related stocks, with uranium mining comprising about 47%, uranium enrichment is around 5% and uranium storage 1%. The remainder are in companies involved in nuclear power plant infrastructure, 37%, equipment, 10% and fuel transport and generation, at less than 1%.

With the U.S. comprising just 3.4% of its benchmark index, NLR is really an international ETF. Japanese companies account for 41% of the index, with Canada comprising 29% and Australia another 14%. In fact, USEC ( USU) is the only U.S. company in the ETF, and only a few others, such Canada's Denison Mines ( DNN), Cameco ( CCJ) and Frontier Development Group ( FRG), trade here. Japan's Mitsubishi Heavy Industries is the fund's largest holding at 9.7%.

Uranium is one of the word's hottest commodities -- over the past decade, its price has risen three times faster than that of oil. From a low of around $7 a pound in 2000, yellowcake soared more than 1800% to its recent high of $135 in June.

"The world consumes 180 million pounds of uranium a year," says David Miller, president and chief operating officer of Strathmore Minerals, a uranium mine developer. "But the world only produces 105 million pounds a year. The rest comes out of the inventory built up in the 1980s after the industry stopped growing. But, now that inventory is (down to) around 500 million pounds. If mining ceased right now, we would run out in three years."

Mining, enrichment and storage stocks are just about the only way to play the mineral. Uranium futures only started trading on the Nymex in May, and activity is still somewhat anemic, while transactions on the spot market are private and infrequent.

The price of uranium can only benefit as more nuclear power plants come online. The 435 nuclear power plants already online worldwide provide 16% of the globe's electricity, according to the World Nuclear Association. Van Eck says 30 power reactors are currently being constructed in 11 countries and that 70 more are planned.

The 104 commercial reactors in the U.S. produce 20% of the nation's electricity, leaving plenty of room to catch up with Europe and Japan, which get 30% of their electricity from nuclear power. France alone relies on it for 75% of its electricity.

While the price of uranium has fallen to $105 since its June high, Miller, of Strathmore Minerals, predicts higher prices as uranium demand grows 1% to 3% a year. However, after the huge run-up, he thinks a large number of companies in the ETF are fully valued, and few, if any are undervalued.

There are other potential drawbacks, such as safety and waste disposal. Last month, after an earthquake hit Japan, a nuclear-power complex spilled radioactive water from a pool storing spent nuclear-fuel rods. And in 2002, an Ohio plant owned by Davis-Besse nearly suffered a meltdown that could have been much worse that Three Mile Island. This was after it had been warned two years earlier to fix the problem.

Meanwhile, the problem of disposing hazardous nuclear waste hasn't been solved. And let's not even talk about the possibility of a terrorist attack.

The ETF closed at $36.89 Monday, down 7.8% from its launch at $40 a share. Of course, with the stock market's recent volatility, it wasn't the best time to launch a new security.