Nuclear Engineering Division

Nuclear Chemical Engineering

Closing the Nuclear Fuel Cycle: Recycling Long-lived Fissile Materials as Fuel

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Nuclear Chemical Engineering Dept.
Dept. Manager: Mark Williamson
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Mark Williamson's Executive Bio

Used fuel contains essentially all of the elements in the periodic table. However, nearly all of the risk associated with the disposal of spent fuel comes from approximately 1 percent of its content—primarily the transuranic elements: plutonium, neptunium, americium, and curium, and the long-lived isotopes of iodine and technetium. The very high short-term radioactivity comes primarily from two elements, cesium and strontium. In a recycle approach, the transuranics will be separated from spent fuel and destroyed in advanced reactors, while the technicium and iodine will be placed into waste forms specifically tailored to retain these elements. With the key elements removed, the toxicity of the remaining 99 percent of the waste drops below that of natural uranium ore in about 1,000 years.

Used Fuel Assembly
Uranium accounts for the bulk of used fuel. The fissile component comprises less than 1 percent of the uranium, near the fraction found in the natural ore. This uranium may be disposable as low-level waste or stored for eventual re-enrichment for reactor fuel.