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Processing Methods: Separation of uranium or plutonium from fission 
products can be accomplished by many methods, the most versatile of which 
is solvent extraction. Uranium and plutonium can be selectively extracted 
from an aqueous solution by organic solvents such as diethyl ether and 
tributyl phosphate. Important steps in a typical solvent extraction process 
ares 
1. Dissolution of the irradiated reactor fuel element in a strong 
acid such as nitric acid. Cladding and alloying elements may be 
dissolved along with the fuel material, or the cladding dissolved 
separately and discarded as a slightly active waste solution. 
Alloying materials usually are dissolved along with the fissionable 
material, thus contributing materially to the total salt content of 
waste solutions. 
®. Feed clarification followed by feed adjustment to flowsheet con- 
centrations. If feed clarification is required, waste solutions 
containing varying quantities of fission products result from dis- 
charged filter or centrifuge flush solutions. Solids result from 
impurities in fissionable, fertile or cladding material. 
3. Solvent extraction of uranium and plutonium in highly oxidized, 
solvent soluble state into the organic solvent. Solvents are 
highly selective for uranium and plutonium, leaving fission products, 
cladding material, and alloying diluents behind in the aqueous phase. 
In solvent extraction from nitric acid solutions, plutonium and 
uranium extract as nitrate complexes into the organic phase so the 
aqueous phase must be "salted" with nitrates. In some processes 
HNO, is sufficient; others require "solid" salting agents such as 
dissolved aluminum nitrate. The organic stream bearing almost all 
uranium and plutonium originally in the aqueous phase is "scrubbed" 
with nitrate bearing aqueous phase, which removes additional fission 
DECLASSIFIED 
