Nuclear power's future: Reprocessing returns?

POSTED 28 FEBRUARY 2008

Nuclear power's future: Reprocessing returns? 
Is nuclear back? The growing energy shortage, combined with the fact of greenhouse warming, have sparked a flurry of interest in non-carbon energy sources, including nuclear energy. After all, according to the Nuclear Energy Institute, nuclear is "Clean air energy."

The result is a sudden end to a 30-year drought in U.S. nuclear-plantapplications. By February, 2008, the U.S. Nuclear Regulatory Commission (NRC) has received applications for six new reactors.

The long drought had several causes. Cost was one -- the last U.S. nuclear plants came in way late and way over budget, partly due to safety and regulatory changes following the 1979 meltdown at Three Mile Island. "One reason you saw the stall in nuclear building was that the uncertainty made investors much more cautious about getting involved," says Todd Allen, an assistant professor of nuclear engineering at the University of Wisconsin-Madison. "There was a lack of certainty from the time of taking out a loan to selling electricity." Regulatory delays and design changes can eat up profits on such an expensive plant, he adds.

Reactor operators are now trying to control costs by standardizing their designs, and the NRC has promised faster regulatory decisions. Nuclear power makes about 20 percent of U.S. electricity, and about 16 percent globally.

But we see little cause for optimism about a second key source of the nuclear willies -- safe disposal of the intensely radioactive spent fuel that must be removed from reactors. The giant, federal nuclear-waste warehouse at Yucca Mountain, Nev. was supposed to solve the spent-fuel problem. But Yucca was scheduled to open 10 years ago, and it is unlikely to open for another 10 years -- if ever.

When a neutron hits a uranium-235 atom and causes it to split ("fission") in a nuclear reactor, we get fission products and "transuranics" (heavy elements like plutonium), along with more neutrons and a gob of energy.

With Yucca in limbo (some scientists say it cannot contain radwaste for 1 million years), the high-level waste problem remains unsolved.

So in the year that Yucca was supposed to celebrate its 10th birthday, here's our question: Who's got some good ideas for safely storing high-level nuclear waste?

These "dry casks" are an increasingly popular, but temporary, solution to radioactive waste storage at reactor sites. Photo: NRC

Radwaste: The original Mr. Yuck 
High-level radwaste -- the yuck Yucca is slated to receive -- is spent fuel from nuclear reactors, and it's roughly one million times more radioactive than fresh uranium fuel. High-level waste is extremely carcinogenic, even lethal, and must be handled by remote control or under heavy shielding.

Spent fuel can also provide the basis for good ol' explosive nuclear bombs and dirty bombs (which spew radiation without that familiar mushroom cloud). So to prevent nuclear proliferation, nuclear terrorism, and a cancer epidemic, spent fuel must be contained virtually forever.

The goal at Yucca is to safely store 70,000 tons of radwaste for 1 million years. Over those 10,000 centuries, the radioactive isotopes will gradually cool and be converted into stable, non-radioactive isotopes. (Isotopes are versions of an element with a different number of neutrons. Different isotopes decay at different rates; with many elements, some isotopes are stable, others will decay and release radiation.)

For the repository at Yucca, about 100 miles northwest of Las Vegas, the U.S. Department of Energy (DOE) would love to follow GambleVille's marketing mantra ("What radiates near Vegas stays near Vegas"). But the giant repository is unlikely to open for at least another 10 years, and in the meantime, spent fuel will continue stacking up at reactors across the country, making a splendid target for terrorists eager to release a deadly cloud of radiation or even trigger a nuclear meltdown.

As electric generating plants spew out millions of tons of the greenhouse gas carbon dioxide, interest in nuclear energy is rising. But new plans to reprocess nuclear fuel have raised old fears. Photo ©David Tenenbaum

Reprocessing redux? 
The slipping schedule at Yucca has refocused attention on nuclear fuel reprocessing. When uranium fuel is first used in a reactor, it releases only about 1 percent of its nuclear energy (the fuel must then be replaced because a buildup of uranium breakdown products interferes with the chain reaction).

Unfortunately, many of these "fission products," such as cesium 137 and strontium 90, are remarkably radioactive. Still, about 99 percent of the nuclear energy remains in the spent fuel, mainly in the uranium 235 and plutonium 239. During reprocessing, these isotopes are separated out and blended into new fuel rods that go into another reactor. The fission products, however, become high-level radwaste.

Recycling uranium makes more sense than one-time use to many experts, including radiochemist Peter Burns of Notre Dame University. "Why are we calling this stuff waste? Why do we have a policy of sending this stuff to a nuclear waste repository?"

Indeed. Does reprocessing make sense?