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years, it is considered to be one of the largest contributors to the long-term potential
threat of radioactivity from nuclear waste.
The two primary fissile isotopes are 235 U and the strategically important 239 Pu,
which has a low critical mass of < 2 Kg. The 239 Pu isotope is now produced by the ton in
nuclear reactors. Three grades of plutonium are commonly recognized: weapon-grade
240 Pu (< 7%), fuel-grade 240 Pu (7–18%) and reactor-grade 240 Pu (18%). High-level waste
from the isolation of 239 Pu also contains large quantities of 238 Pu, as well as heavier Pu
isotopes. Isotope 238 Pu is considered to be an important fuel source and is commonly used
as a source of energy in both earth and space borne satellites [2].
These and other radiotoxic actinides, found in nuclear fuel processing and waste
storage, pose an immediate and future environmental concern. Treatment often involves
either separation for reuse or immobilization for long-term storage. The waste solutions
from the processing of irradiated uranium fuel contain U, Np, and Pu isotopes but often
also contain other isotopes representative of as much as a third of the periodic table of
elements. U, Np, and Pu can often be isolated and purified by a combination of solvent
extraction, ion exchange, and precipitation/coprecipitation techniques.
The separation of the early actinides from their fission products and from each
other is generally accomplished by adjusting the oxidation state of the actinide ion in
aqueous solution to make the coordination chemistry substantially different from that of
the other species to be separated.
The radioactivity, toxicity, and chemical reactivity of the actinides make handling
them in atmosphere-controlled glove boxes a necessity. When high levels of penetrating
radiation are encountered, manipulation also needs to be done with remote controls. With
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