Reactor Burns Waste as Fuel in Nuclear Recycling Experiment

Long-Lived Waste from Nuclear reactors will be used as fuel to generate electricity if an Argonne experiment underway is successful. Experimental fuel, made partly from materials found in nuclear waste, is burning in Argonne's Prototype Integral Fast Reactor (IFR).

The IFR, considered by the National Academy of Sciences to be the nation's highest priority long term reactor option, runs on metal fuel, uses liquid-metal coolant and has passively safe design. It recycles its own nuclear waste as fuel.

The experimental fuel rods, placed in the IFR in February 1993, will help power the reactor for about a year. Then they will be removed to see how well the reactor burns americium and neptu- nium. These long-lived radioactive elements are considered atomic waste and must be isolated from the environment for thousands of years. If the IFR can burn them as fuel, a massive environmental problem can be converted into a vast energy resource.

Fuel rods power the nuclear reaction that produces the energy to generate electricity. The IFR metal fuel rods used in the reactor since 1986 have reached an atomic burnup - the percentage of fuel that is consumed - of 19.3 percent.

Conventional nuclear power plants use ceramic fuel and nor- mally only consume 3 or 4 percent of their fuel before it must be replaced. That fuel is stored as waste.

The IFR's uranium, plutonium and zirconium metal fuel was designed to reach 15 percent burnup, and researchers are predicting it may reach 22 percent. Fuel testing continues to provide data for future licensing reviews.

Efficient fuel performance means fuel can remain in the reactor longer thereby reducing the cost and environmental risks of fuel replacement. Research shows the fuel can be subjected to a wide range of operating conditions safely.

When IFR fuel rods reach their maximum burnup, the fuel will be reprocessed in the Fuel Cycle Facility (FCF) located next to the reactor. Fuel recycling at the reactor site is a key IFR feature. Completion of the FCF renovation will permit full demonstration of the IFR concept and is critical to future commercial development.

The IFR's fuel recycling recovers the fuel that is not burned in its first cycle in the reactor. That fuel is formed into new rods, placed in fuel cladding and returned to the reactor. This process is repeated until essentially all of the fuel is used to produce electricity.

Fuel recycling greatly reduces the amount of the radioactive wastes that must be buried in geologic repositories. After 300 to 400 years, IFR waste - the products of fissioning - are as safe as the natural ore the fuel came from.

The IFR uses a combination of metal fuel and a liquid sodium coolant rather than the ceramic oxide fuel and water coolant used in most existing reactors. The IFR combination uses the laws of nature and the basic properties of the materials to control the nuclear reactions and remove heat from the core.

IFR safety was demonstrated at the prototype facility in 1986 when researchers shut off power to the pumps that circulate coolant through the core. This would have caused a severe accident in most types of reactors. But the IFR prototype safely shut itself down in a few minutes without human or mechanical intervention.

As heat builds up in the core, IFR's metal fuel rods expand and move away from each other. This slows the fission reaction and shuts down the reactor. At the same time, the metal fuel gives off heat better than the ceramic fuel, making it more difficult for core heat to build up to dangerous levels.

The liquid sodium coolant carries away the heat. Even without pumps driving sodium through the core, natural convection current in the pool are sufficient to cool the reactor.

The IFR can be operated to burn fuel or to match fuel burning and production. New fuel need never be shipped in, nor waste shipped out, during the plant's operating life. This minimizes the risk of environmental damage or unauthorized diversion of radioactive materials. IFR technology can extract maximum electricity from world uranium supplies.

Unlike coal-burning power plants, nuclear power plants emit no carbon dioxide which could contribute to the greenhouse effect, and no oxides of sulfur or nitrogen which produce acid rain.

Additional funding for the project is being provided by a Japanese utility consortium ($46 million). Also, Southern California Edison is providing $2 million through the Electric Power Research lnstitute.

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