Method for extracting and recovering plutonium from plutonium-containing nitric acid solution

Abstract

The invention belongs to the technical field of nuclear material extraction and recovery, and relates to a method for extracting and recovering plutonium from a plutonium-containing nitric acid solution. The method comprises the following steps: oxidizing plutonium in the spent fuel reprocessing plutonium-containing nitric acid solution to tetravalent with an oxidant, adding an organic solvent containing DMHMP, Di(1-methyl heptyl)methyl phosphonate for extraction under strong acidic conditions, collecting organic phase, adding a reducing agent, performing back extraction under dilute acidic conditions to selectively reduce the tetravalent plutonium in the organic phase to trivalent, and performing back extraction to form the aqueous phase. The method for extracting and recovering plutoniumfrom the plutonium-containing nitric acid solution can efficiently separate plutonium from other impurities, such as uranium, fission product elements of plutonium, strontium, and cesium, and concentrate plutonium to obtain the plutonium nitrate product solution with standard purity.

Description

technical field [0001] The invention belongs to the technical field of nuclear material extraction and recovery, and relates to a method for extracting and recovering plutonium from a plutonium-containing nitric acid solution. Background technique [0002] The principle of solvent extraction to extract plutonium is to separate and purify plutonium from the feed liquid by utilizing the difference in the extraction ability of organic extractants for plutonium in different valence states. Tributyl phosphate (TBP) is the commonly used extractant in spent fuel reprocessing plants. [0003] As a good extractant, TBP is widely used in the reprocessing of nuclear fuel elements. However, there are also some shortcomings in the application of TBP in post-processing, which is mainly manifested in the fact that chemical and radiation degradation will occur during the use of TBP, resulting in a series of degradation products, resulting in a series of adverse consequences: [0004] (1) ...

AI Technical Summary

Problems solved by technology

However, there are also some shortcomings in the application of TBP in post-processing, which is mainly manifested in the fact that chemical and radiation degradation will occur during the use of TBP, resulting in a series of degradation products, resulting in a series of adverse consequences:

[0004] (1) Influenced the reutilization of extractant, causing the waste of a large amount of extractant;

[0005] (2) Degradation products will cause "retention" of heavy metals;

[0006] (3) Interfacial dirt or even emulsified agglomeration is produced by the interaction between the radiolysis product and the feed liquid, resulting in the failure of the extraction process to proceed normally;

[0007] (4) Some fission products have strong radioactivity, high output, and long half-life. In this case, even if the cooling time of nuclear fuel is prolonged, the radiation damage to the extraction system is also quite serious.

[0008] These consequences reduce the decontamination efficiency, make the stripping of actinides incomplete, and cause losses

In addition, degradation products and high-valent metal ions can form insoluble complexes during the extraction process, which is prone to three phases and precipitates, which will affect the operation of the system

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