The Evolution of Nuclear Power
Caption

Argonne, INEEL lead U.S. role in planning the next generation of nuclear reactors

Over the next 20 years, electricity demand is expected to increase 40 percent in the United States and 70 percent globally. To ease the impact on global climate, much of this new electricity production is likely to come from nuclear energy, the only existing technology that can generate large amounts of electricity without also emitting greenhouse gases.

Ten nations—Argentina, Brazil, Canada, France, Japan, the Republic of Korea, the Republic of South Africa, Switzerland, the United Kingdom and the United States—are collaborating to develop a future generation of nuclear energy systems, known as Generation IV. This collaboration will share research and development costs and ensure that future reactors meet the needs of different nations.

"The first generation was the early prototype reactors of the 1950s and ‘60s," said Argonne nuclear engineer Hussein Khalil. "The second was the large commercial power plants built in the 1970s and still operating today. Generation III, developed in the 1990s with evolutionary advances in safety and economics, is being built today, primarily in eastern Asia. Until about 2030, new plants will mainly be Generation III designs."

The Generation IV nations, he said, plan to develop nuclear energy systems for construction and operation around 2030, when many of the world’s existing nuclear power plants will be at or near the end of their operating lives. "To succeed in the international marketplace," Khalil said, "Generation IV technologies will need to provide safe, reliable and economical electricity, while reducing the amount and toxicity of nuclear waste and minimizing the risk of nuclear proliferation."

Closed fuel cycle
An early finding of the Generation IV study is that, for the next 50 years, the main constraint on the growth of nuclear energy will be the worldwide availability of repository space to dispose of reactor wastes. "This finding suggests that Generation IV reactors will benefit from a closed fuel cycle," said John Sackett, Argonne associate laboratory director for engineering research.

A closed fuel cycle reprocesses spent reactor fuel to extract uranium and plutonium, the main elements that power the reactor. The alternative is to place spent fuel in repositories without reprocessing.

Some closed fuels cycles, such as Argonne’s pyroprocessing technology, extract minor actinides—waste elements such as neptunium and americium that take hundreds of thousands of years to decay—along with uranium and plutonium and recycle them all into new fuel. The reactor destroys the actinides by fission as it generates electricity.

With the actinides gone, the short-lived wastes need environmental isolation for less than 1,000 years. "In that time," said Sackett, "they decay until they are less radioactive than the natural ore the original fuel came from. You’d still need repositories, but you’d have less material to fill them, and they would be less costly to build and maintain."

One reactor system identified for further research and development under Generation IV is the sodium-cooled fast reactor. Argonne has decades of experience with this type of reactor.

Argonne’s advanced fast reactor
Argonne recently began work on the design for the Advanced Fast Reactor 300 (AFR-300), a sodium-cooled fast reactor system that uses a closed fuel cycle to consume plutonium and minor actinides taken from the spent fuel of light-water reactors (LWRs). Most of the world’s commercial reactors are LWRs. (see What is a Fast Reactor?)

AFR-300s could operate alongside Generation III LWRs to manage the spent fuel they discharge each year, as well as the spent fuel accumulated from prior operation of LWRs. Once the excess plutonium and minor actinides from LWRs have been consumed, AFR-300s could be configured to regenerate them to meet its own fueling needs and those of other reactors. Configured this way, AFR-300s make it possible to get the full energy benefit from the earth’s endowment of uranium.

"Some more research is needed," said Sackett, "but the AFR-300 appears well positioned to satisfy all the Generation IV goals. It uses the natural properties of its materials to achieve passive safety, and its pyroprocessing fuel treatment reduces the amount and toxicity of waste and keeps nuclear materials unsuitable for direct use in nuclear weapons."

Based largely on EBR-II, an experimental fast reactor that Argonne operated safely and reliably for 30 years at Argonne-West in southeastern Idaho, the AFR-300 is a simple reactor design that would produce 300 megawatts of electricity. Its relatively small electrical output—1,100 megawatts is the average for commercial reactors—is expected to make it economically competitive by allowing modular construction and deployment.

Pyroprocessing keeps nuclear materials in the fuel cycle from being used in weapons, because the technology does not separate plutonium in a pure enough form. Fast reactors, such as the AFR-300, could also help to eliminate weapons-grade plutonium; incorporating it into fast-reactor fuel would make it unsuitable for weapons and provide energy as well.

For more information, please contact David Baurac.

Next: Argonne’s spent-fuel recycling may reduce nuclear waste storage shortage

Back to top