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1. Decladding: One of several processes is used to open or dissolve the cladding to expose the contents of the irradiated uranium fuel and/or targets.1
2. Dissolution of irradiated fuel. The fuel rod contents are then dissolved in nitric acid and are now in solution as nitrates. Cladding which has been opened is left unreacted. Cladding which has been dissolved is separated and processed to be stored or discarded as nuclear waste. Both processes (decladding and dissolution) release radioactive gases. 3. Separation of plutonium and uranium. The solution is exposed to a solvent called tributyl phosphate (TBP) mixed with kerosene. The TBP selectively separates out the plutonium and uranium from the fission products.
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4. Separation of plutonium and uranium from each other. After the plutonium and uranium are separated by solvent extraction, the products are plutonium nitrate and uranium nitrate, both in solution. Each may be further processed before shipping to reduce risks from accidents. Plutonium in particular is generally converted to solid oxide or metal form before shipping or storage. Uranium is converted to uranium trioxide.
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1 In some military production reactors, as at the Savannah River Site in South Carolina, the special uranium-238 "target rods" are bombarded with neutrons to convert the uranium-238 into plutonium. The irradiated target rods as well as the fuel rods that create and maintain the chain reacton often go under the common rubric of "spent fuel." Source of diagram: Simplified diagram of the Purex process. Adapted from Benedict, M., T.H. Pigford, and H.W. Levi, Nuclear Chemical Engineering, 2nd ed. (New York: McGraw-Hill, 1981), p. 467. |
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Institute for Energy and Environmental Research
Comments to Outreach Coordinator: ieer@ieer.org
Posted November 1996
Updated September 11, 2001
Takoma Park, Maryland, USA