A method for purifying and concentrating plutonium

A plutonium nitrate and extraction technology is applied in the field of purification and concentration of plutonium, which can solve the problems of serious solvent radiolysis effect, adverse effect of stripping effect, and reducing the plutonium stripping yield, and achieves short time consumption, small radiolysis effect, The effect of simplifying method steps

Active Publication Date: 2016-05-04
CHINA INSTITUTE OF ATOMIC ENERGY
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Problems solved by technology

Although this method can increase the concentration of plutonium by about ten times, it also has the following disadvantages: (1) although the supplementary extraction step of uranium can further reduce the uranium content in the plutonium product liquid, it will reduce the stripping yield of plutonium, and As an important nuclear material, plutonium needs to be fully recovered
(2) When purifying and concentrating the plutonium nitrate solution, the plutonium concentration is high, and the plutonium releases a large amount of α-rays that are easily absorbed by the solvent, and the solvent will have a radiolysis effect. The extraction effect will adversely affect the
The solvent extraction separation process is a multiple-phase two-phase mixing-phase separation process. Since the mixing and settling tank uses gravity to separate the two phases, the phase separation time is relatively long, so that the single-stage residence time of the mixing and settling tank is usually more than 1 minute. The radiolysis effect of the solvent is more serious

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  • A method for purifying and concentrating plutonium
  • A method for purifying and concentrating plutonium

Examples

Experimental program
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Effect test

Embodiment 1

[0030] The purification and concentration of plutonium is carried out in a centrifugal extractor. This method includes two steps of extraction and stripping. The process flow of the method is as follows: figure 1 shown.

[0031] (1) Extraction

[0032] The Pu(IV) in the plutonium nitrate solution composed of 3.3g / L plutonium-3.5mol / L nitric acid is extracted into the organic phase 30% TBP-kerosene solution, and the Zr is further purified while the Pu(IV) is concentrated. , Ru and other splinter elements; the volume of 30% TBP-kerosene is 1 / 4 of the plutonium nitrate solution. The number of extraction stages is 10. Then wash with 1mol / L nitric acid, the number of washing stages is 6.

[0033] (2) Stripping

[0034] Pu(Ⅳ) in 30% TBP-kerosene solution was reduced to Pu(Ⅲ) by using nitric acid solution containing dimethylhydroxylamine as a reducing agent, and Pu(Ⅲ) was back-extracted into the water phase, so that the plutonium nitrate solution was purified and concentrated. W...

Embodiment 2

[0039] The same method and steps as in Example 1, except that the volume of 30% TBP-kerosene in step (1) is 1 / 3 of the plutonium nitrate solution, and the number of extraction stages is 11. Then wash with 1.5mol / L nitric acid, the number of washing stages is 7.

[0040] The volume of the nitric acid solution containing dimethylhydroxylamine in step (2) is 1 / 3 of the 30% TBP-kerosene solution. The number of stripping stages is 13, and the concentration of dimethyl hydroxylamine is 0.8mol / L.

[0041] The bench test results are: under the given process conditions, the plutonium extraction yield is 99.93%, the plutonium back-extraction yield is 99.98%, and the plutonium concentration in the concentrated plutonium nitrate solution is 30.5g / L.

Embodiment 3

[0043] The same method and steps as in Example 1, except that the volume of 30% TBP-kerosene in step (1) is 1 / 4 of the plutonium nitrate solution, and the number of extraction stages is 12. Then wash with 1.5mol / L nitric acid, the number of washing stages is 8.

[0044] The volume of the nitric acid solution containing dimethylhydroxylamine in step (2) is 1 / 3 of the 30% TBP-kerosene solution. The number of stripping stages is 14, and the concentration of dimethyl hydroxylamine is 1mol / L.

[0045] Bench test results are: under the given process conditions, the plutonium extraction yield is 99.91%, the plutonium stripping yield is 99.99%, and the plutonium concentration in the concentrated plutonium nitrate solution is 40.2g / L.

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Abstract

The invention belongs to the technical field of fuel-short after-treatment and discloses a plutonium purification and concentration method. The method comprises the following steps: extracting tetravalent plutonium in a nitric acid solution into a 30% TBP (tributyl phosphate)-kerosene solution with relatively small volume for purification and concentration in a centrifugal extractor, reducing tetravalent plutonium into trivalent plutonium by using a dimethylhydroxylamine-containing nitric acid solution with relatively small volume, performing back extraction on trivalent plutonium, and further purifying and concentrating plutonium in a water phase. In the whole concentration process, a plutonium replenishment and extraction link is removed. The method is simple in step, short in time and small in solvent radiation effect; the plutonium back-extraction yield reaches up to 99.98% while the plutonium concentration is increased by more than 10 times.

Description

technical field [0001] The invention belongs to the technical field of spent fuel reprocessing, and in particular relates to a method for purifying and enriching plutonium. Background technique [0002] Plutonium products obtained from laboratory research or reprocessing plants are usually in the form of plutonium nitrate solutions. However, estimates of the final product storage price of plutonium show that it is more economical and safer to store plutonium dioxide than plutonium nitrate solution. Therefore, in order to facilitate storage, it is necessary to convert the plutonium nitrate solution into the solid form of plutonium dioxide. [0003] The conversion of plutonium nitrate solution into plutonium dioxide solid is usually carried out by plutonium nitrate precipitation with plutonium oxalate, and then filtering, drying and roasting the plutonium oxalate precipitate to obtain plutonium dioxide powder. In order to speed up the plutonium oxalate precipitation process,...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22B60/04C22B3/40
CPCY02P10/20
Inventor 晏太红左臣郑卫芳鲜亮李传博
Owner CHINA INSTITUTE OF ATOMIC ENERGY
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