Method for separating U (uranium) from Pu (plutonium) in Purex process

Abstract

The invention which belongs to the technical field of radioactive post-treatment concretely relates to a method for separating U from Pu in a Purex process. The method comprises the following steps: 1, removing nuclear reaction splinters except U and Pu; 2, coextracting codecontaminated U and Pu to a TBP (tributyl phosphate) / kerosene mixed liquor with a volume percentage of 30%; and 3, adding a reducing agent HSC (hydroxysemicarbazide) to the mixed liquor in step 2, and fully mixing to back-extract Pu (III) which is reduced from Pu (IV) in an organic phase to an aqueous solution of hydrogen nitrate, wherein the ratio of the molar concentration of the HSC in an aqueous phase solution to the molar concentration of Pu in an organic phase solution is 5-60, the volume ratio of the organic phase solution to the aqueous phase solution is 1:1-6:1, the temperature is 21-42.5DEG C, and the concentration of H<+> is 0.3-1mol / L. A technical scheme provided by the invention allows Pu (IV) in the organic phase to be rapidly reduced and back-extracted to the aqueous phase, the reaction time is two magnitudes shorter than the reaction time of the prior art, the technological process is simplified, and the separation efficiency is improved.

Description

technical field [0001] The invention belongs to the technical field of radioactive post-processing, and in particular relates to a method for separating uranium and plutonium in the Purex process. Background technique [0002] The separation of U and Pu in the Purex process is based on tributyl phosphate (abbreviated as TBP) for U ( ), Pu(Ⅳ) and Pu(Ⅲ) different extraction capabilities. The selection of reducing stripping agent, the determination of its concentration, and the elimination of various interfering factors are the key to realize the separation of U and Pu[1,2]. Usually, the valence conversion from Pu(Ⅳ) to Pu(Ⅲ) adopts reagent reduction and electrolytic reduction, and the most commonly used reducing agent is U( ) and hydroxylamine, where U ( ) can better reduce Pu(Ⅳ) to Pu(Ⅲ), but it has some disadvantages, such as: U( ) is much more than stoichiometric; U( ) and Pu(III) are autocatalytically oxidized; it requires an additional supporting reducing agent ...

AI Technical Summary

Problems solved by technology

Usually, the valence conversion from Pu(Ⅳ) to Pu(Ⅲ) adopts reagent reduction and electrolytic reduction, and the most commonly used reducing agent is U( ) and hydroxylamine, where U ( ) can better reduce Pu(Ⅳ) to Pu(Ⅲ), but it has some disadvantages, such as: U( ) is much more than stoichiometric; U( ) and Pu(III) are autocatalytically oxidized; it requires an additional supporting reducing agent - hydrazine generates NH3 which is explosive and NH4+ which is not conducive to the process

NH4OH is also a salt-free organic reagent widely used to reduce Pu(Ⅳ) to Pu(Ⅲ), but its reduction rate to Pu(Ⅳ) is slow, only at lower acidity and higher temperature (about 50°C) In the case of a large excess of reducing agent and reducing agent, the process requirements can be met

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