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Uranium purification method for simultaneously removing neptunium and plutonium in nuclear fuel Purex post-treatment process

A purification method and nuclear fuel technology, applied in the purification of uranium from plutonium, and the removal of neptunium at the same time, can solve the problems that cannot be realized and the concentration requirements are harsh

Active Publication Date: 2017-09-05
CHINA INSTITUTE OF ATOMIC ENERGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] Due to the strict requirements on the concentration of Np and Pu in uranium products (the concentration of Pu in each gram of uranium product must be lower than 1×10 -8 g, Np concentration must be lower than 3.2×10 -6 g), in order to simultaneously remove Np and Pu in one uranium purification cycle and meet the requirement of high uranium yield, it cannot be realized by only one measure in the prior art

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  • Uranium purification method for simultaneously removing neptunium and plutonium in nuclear fuel Purex post-treatment process
  • Uranium purification method for simultaneously removing neptunium and plutonium in nuclear fuel Purex post-treatment process
  • Uranium purification method for simultaneously removing neptunium and plutonium in nuclear fuel Purex post-treatment process

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Experimental program
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Embodiment 1

[0040] Embodiment 1: Evaporation concentration test of simulated 1CU feed liquid

[0041] Will contain 60g / L uranium, 2.6×10 -2 The simulated 1CU feed solution of g / L Np(IV) and 0.1mol / L nitric acid was evaporated and concentrated at 100°C under normal pressure, and the evaporation process took a total of 2 hours. After evaporation and concentration, the uranium concentration in the 1CU concentrated solution is 350g / L, the total Np concentration is 0.150g / L, and the Np(IV) concentration is 2.83×10 -3 g / L, that is, more than 98% of Np(IV) in 1CU feed solution was oxidized to a high valence state, and the effect of evaporative concentration pretreatment on Np valence state was satisfactory.

Embodiment 2

[0042] Embodiment 2: Comparative test of hydroxylamine stripping and hydroxylamine reduction

[0043] The single-stage back-extraction method was used to investigate the effect of hydroxylamine back-extraction trace Pu(IV), and the results are shown in Table 1. In the experiment, the uranium concentration in the organic phase was 90g / L, the plutonium concentration was 34.5μg / L, and the nitric acid concentration was 0.1mol / L; . The single-stage back-extraction experiment was carried out with extraction tubes at room temperature, and the phase ratio during back-extraction was 6:1, shaken by hand for 2 minutes, and centrifuged to separate the phases. The experimental results show that the stripping rate of Pu(IV) in the organic phase is about 90% only relying on hydroxylamine to reduce the trace amount of Pu(IV) in the organic phase, and the stripping rate of plutonium does not increase significantly with the increase of stripping times. Relying only on hydroxylamine-hydrazine ...

Embodiment 3

[0049] Example 3: Test of the Effect of Feed Uranium Concentration on the Saturation of Organic Phase Uranium in the Extractor

[0050] Through process experiments, the distribution of uranium concentration in each stage is compared when 1CU feed liquid is evaporated or not (that is, the concentration of feed uranium is different), so as to compare the influence of feed uranium concentration on the uranium saturation of the organic phase in the extractor. Schematic diagram of uranium purification process figure 1 As shown, the experimental parameters are shown in Table 3, and the experimental results are shown in figure 2 , 3 shown. Through comparison, it can be found that even in the set dilute uranium feed process, 2DU (2DU is the organic phase with uranium extracted, 2DW is the nitric acid waste liquid containing residual reducing agent and trace uranium, neptunium and plutonium) has a higher concentration of uranium at the outlet (diluted uranium The measured value of ...

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Abstract

The invention belongs to the technical field of nuclear fuel post-treatment, and relates to a uranium purification method for simultaneously removing neptunium and plutonium in the nuclear fuel Purex post-treatment process. The uranium purification method sequentially comprises the following steps that firstly, evaporation and concentration pretreatment is conducted, a uranium rough product from the Purex post-treatment procedure uranium plutonium codecontamination separating cycle is subjected to evaporation and concentration pretreatment, accordingly, Np(IV) in the uranium rough product is adjusted to Np (V) and Np (VI); secondly, a reducing agent is adopted for reducing, a concentrated solution obtained in the first step is cooled to the room temperature, then the reducing agent is added, then Pu (IV) and Pu (VI) in the concentrated solution are reduced into Pu (III), and Np (VI) is reduced into Np (V); and thirdly, organic solvent extraction is conducted, the acidity of the solution obtained in the second step is adjusted, extraction is conducted in an extractor with an organic solvent containing tributyl phosphate in a multi-level manner, wherein the organic solvent containing the tributyl phosphate is divided into multiple parts to be added at different extraction levels. By utilization of the uranium purification method, the Np and the Pu can be removed at the same time through one uranium purification cycle, and qualified uranium products are obtained.

Description

technical field [0001] The invention belongs to the technical field of nuclear fuel reprocessing, and relates to a uranium purification method for simultaneously removing neptunium and plutonium in the nuclear fuel Purex reprocessing process flow. Background technique [0002] The industrial-scale reprocessing of spent radioactive fuel has a history of more than 70 years. There are 17 countries engaged in reprocessing, among which Britain, France, Russia, India, Japan and other countries have successively built and operated commercial reprocessing plants, with rich experience Operating experience. my country began research on power reactor reprocessing technology in the 1970s. Since the beginning of the new century, with the further development of my country's nuclear power, the development of my country's reprocessing technology is gradually entering the fast lane, and the commissioning of the power reactor reprocessing pilot plant has been completed. A commercial reprocess...

Claims

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Application Information

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IPC IPC(8): C22B60/02C22B7/00G21C19/46G21F9/12
CPCC22B7/006C22B60/026G21C19/46G21F9/125Y02E30/30Y02P10/20Y02W30/50
Inventor 左臣袁中伟晏太红何辉郑卫芳陈延鑫兰天吕洪彬
Owner CHINA INSTITUTE OF ATOMIC ENERGY
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