NEW YORK (Reuters) - Thorium - a little known metal more plentiful than uranium - could help power the so-called nuclear renaissance, without producing weapons-grade material with its waste, according to Virginia-based Lightbridge Corp.

Fuel rods based on the metal won’t be ready for commercial use for another 8 years or so, but the material would be cheaper, more efficient and less harmful than uranium, Lightbridge Chief Executive Seth Grae told Reuters.

“Thorium-based fuel would produce less waste and that waste would have longer-term lower radiation than uranium-based fuels,” Grae said in an interview. He added that waste from Lightbridge’s thorium “cannot be used to make a nuclear bomb.”

Lightbridge Corp, which listed on the NASDAQ in October advises on existing and emerging nuclear programs and develops nuclear fuel technology based on thorium.

The naturally occurring slightly radioactive element, first identified in 1828, is about four times more abundant than uranium, which fuels most reactors, Grae said.

With demand for power growing and concerns over climate change pushing countries to seek alternatives to carbon-emitting fossil fuels, countries are again looking at nuclear power despite its proliferation and waste disposal problems.

Thorium was used as an alternative nuclear fuel to uranium in small reactors and research reactors in the 1960s-1980s. But the U.S. government did not pursue thorium-based fuel in the early days of nuclear research in part because uranium was enriched for both reactor fuel and nuclear weapons production during the Cold War.

“Lightbridge’s designs of thorium-based fuel would be about 5 percent to 15 percent cheaper than uranium-based nuclear fuels. It can replace uranium fuel in existing reactors without modification,” Grae said.

And though the process would run at cooler temperatures than uranium fuel, Grae said: “It would last longer than uranium fuel while producing the same amount of power.”

There were about 50 reactors under construction in 13 countries in September, with most reactors on order in Asia, according to the World Nuclear Association.

Europe, Russia and the United States also have major plans for new units. The U.S. Nuclear Regulatory Commission, which regulates the nation’s nuclear power industry, received more than 25 applications for new reactors since 2007.

NOT URANIUM-FREE

The company was formed in 1992 as Thorium Power to develop nuclear fuel designs developed by Dr. Alvin Radkowsky, a founding father of the U.S. nuclear industry who sought to sever the link between nuclear weapons and nuclear power.

Thorium-based power generation does still require some uranium to start off the initial chain reaction, however, and prospective thorium-based fuels would require clearance from the NRC before being used in a commercial power reactor, NRC spokesman Scott Burnell said.

“Thorium - which has pluses and minuses - has a lot of potential but it must complete its development, licensing, and commercial application before it is used as an alternative to the current uranium-based fuel,” said Felix Killar, senior director fuel supply and material licensees, at the Nuclear Energy Institute, the nuclear industry’s trade group.

Lightbridge this year started working with French nuclear company Areva SA in the United States and Russian Limited Liability Research and Development Co (SOSNY) in Russia to see how thorium-based fuel would work in Areva’s new Evolutionary Power Reactor and the Russian VVER-1000.

Lightbridge expects its thorium-based rods to be ready for large scale use in commercial reactors in 2017. The company plans to produce full-size fuel rods in Russia in 2010 and test those rods in research reactors and other facilities before testing them in full- sized commercial reactors in 2012-2013.

Several nations - some with large deposits - are looking into thorium-based nuclear programs, including the United States, France, Japan, Norway and Russia.

India, which is actively pursuing a thorium program, and Australia each have about 25 percent of the world’s reserves at about 300,000 metric tons each, the U.S. Geological Survey said.