Technology▼Solutions Reshaping nuclear fuel
WESTINGHOUSE CORP.
sue,” he stresses. “If you can’t make them in millions of pellets and load them into hundreds of thousands of By reconfiguring nuclear-fuel peland South Korea have expressed inrods, the concept is useless.” lets into “doughnuts”, scientists terest in his design. Westinghouse is interested in from the Massachusetts Institute of Reactors that use the new fuel commercializing the new design beTechnology (MIT) have found a way can operate at 700 °C—less than cause the greater efficiencies achievto boost the amount of energy that half of the 1800 °C required for conable with the annular fuel would nuclear reactors produce by 50%. ventional fuel. This takes the reacallow new light-water reactors to be The new design also helps diminish tor temperature much farther away significantly smaller, Lahoda says. the chance of meltdown by slashing from the 2840 °C at which melt“The biggest cost in a nuclear reacthe temperature at which retor is the building. . . . If you actors must be operated, and can reduce the size of these it renders the spent fuel more things—especially the containproliferation-resistant. ment building—or keep them The advance comes at a time the same size and get more of renewed interest in nuclear power out of them, then you’ve power around the world. U.S. made money,” he explains. utilities are planning to conHejzlar says that the spent struct more than a dozen plants annular fuel would be less atin the next decade, according tractive to terrorists because it to the Nuclear Energy Institute. has a lower concentration of fisAlthough many environmensile isotopes, such as 239Pu, than tal groups remain opposed to traditional fuel. Because the denuclear power, some, such as sign can generate more power the Natural Resources Defense from the fuel, it also decreases Council, are now rethinking its the volume of waste generated value, in part because it is an from nuclear power per megaWhen used as fuel for light-water nuclear reactors, the energy source free from greenwatt-hour by 50%. hollow 14-mm cylinders shown here can increase effihouse-gas emissions. “This technology is a promciency by 50%. Pavel Hejzlar of MIT’s nuising example of a very imporclear science and engineering dedowns can occur. The temperature tant direction for [nuclear power] partment first came up with the is so much lower because the doughresearch: development of new fuel idea of doughnut-shaped fuel in the nut shape enables heat to flow in designs that can improve perforspring of 2000. two directions and the surface-areamance,” says Edwin Lyman, seBy that summer, he and his colto-volume ratio is about 60% higher, nior staff scientist for the Union of league Mujid Kazimi were receiving Hejzlar explains. Concerned Scientists. However, he money from the U.S. Department “A traditional fuel rod looks like stresses that “many safety issues” of Energy (DOE) to investigate the a pencil, with the fuel pellets inside must be resolved. design. Hejzlar decided to forgo the the tube and water flow on the outAt least 10 years of work would be opportunity to patent his design side of the tube. Annular fuel is like a required to commercialize the new in favor of quickly obtaining DOE thick-walled straw . . . or a very thintechnology in the U.S., Lahoda prefunding, so the design is in the pubwalled doughnut,” explains Edward dicts. Light-water reactors that use lic domain. Lahoda, a nuclear engineer at Westhe new fuel do not fit the definition The new fuel, which is known tinghouse Corp., a major manufacof the “fourth-generation” nuclear within the industry as an annular turer of pressurized water reactors. power plants that DOE is currently fuel because of its ring shape, can be The new fuel is much more comfocusing on. Lahoda nonetheless preused with existing light-water reacplex to manufacture than convendicts that, when coupled with the tors, which account for two-thirds tional cylindrical pellets. But when new fuel design, the tried-and-true of the reactors in the U.S. The fuel is Westinghouse made a test run of light-water-reactor technology may especially well suited for pressurized producing the annular pellets, prove more appealing for generating water reactors, which make up 60% they achieved a “very good yield” electricity than some of the newer, of the world’s 443 reactors. Hejzlar of greater than 95%, Lahoda says. fourth-generation designs. says that utilities in the U.S., Japan, “Manufacturing is not a trivial is—KELLYN S. BETTS 676 ■ ENVIRONMENTAL SCIENCE & TECHNOLOGY / FEBRUARY 1, 2007
© 2007 American Chemical Society
