THE GND IS TOO CAUTIOUS:

In a light-water reactor, uranium-235 fuel powers a fission reaction, where the nucleus of an atom splits into smaller nuclei and releases energy. The energy heats water, creating steam which is used to power a generator and produce electricity.

The nuclear fission reaction leaves waste, which is radioactive and has to be maintained carefully. There are about 80,000 metric tonnes of used fuel from light-water nuclear reactors in the United States and the existing nuclear fleet produces approximately an additional 2,000 tons of used fuel each year, Gehin told CNBC.

But after a light-water reactor has run its reactor powered by uranium-235, there is still tremendous amount of energy potential still available in what is left.

"Fundamentally, in light-water reactors, out of the uranium we dig out of the ground, we use a half a percent of the energy that's in the uranium that's dug out of the ground," Gehin told CNBC in a phone interview. "You can get a large fraction of that energy if you were to recycle the fuel through fast reactors."

Fast reactors don't slow down the neutrons that are released in the fission reaction, and faster neutrons beget more efficient fission reactions, Gehin told CNBC.

"Fast neutron reactors can more effectively convert uranium-238, which is predominantly what's in spent fuel, to plutonium, so you can fission it," Gehin said.

The technology for fast nuclear reactors has exited for more than fifty years. A fast reactor plant called the Experimental Breeder Reactor-II (EBR-II), began construction in 1958 and operated from 1964 to 1994, until Congress shut down funding.

"We ran the EBR II reactor out at the site for 30 years, recovered uranium, put it back in the reactor," Gehin told CNBC. "It's been proven that it can be done. The trick would be going to commercial scale to ensure that it is done economically. It's very safe technology. All the basis for the technology has been proven."

While a fast reactor will reduce the amount of nuclear waste, it does not eliminate it entirely.

"There would still be waste that would have to be disposed, but the amount of long-lived waste can be significantly reduced," Gehin said.

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