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PUREX process for separating technetium

A process and flow ratio technology, applied in the field of PUREX process for separation of technetium, which can solve the problem of technetium diffusion into the natural environment with long waste supervision years

Active Publication Date: 2013-09-25
CHINA INSTITUTE OF ATOMIC ENERGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

As technetium is a long-lived nuclide with high natural mobility, it brings many troubles in the treatment and geological storage of high-level radioactive waste liquid, such as a long waste supervision period and the danger of technetium spreading into the natural environment, etc.

Method used

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  • PUREX process for separating technetium
  • PUREX process for separating technetium
  • PUREX process for separating technetium

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Since the main innovation of the present invention lies in the difference in the treatment process for 1AP, the example of the 1A tank is not listed in this embodiment. In order to ensure a more uniform trend of technetium in the process and to reduce the concentration of technetium in high-level radioactive waste liquid, process conditions that are favorable for technetium to enter 1AP are generally adopted. The composition list of 1AP in this embodiment is listed in Table 1.

[0039] Table 1

[0040] 1AP composition

concentration

U

92g / L

Pu

0.90g / L

Np

0.06g / L

Tc

0.20g / L

HNO 3

0.18M

[0041] The specific process of separating technetium:

[0042] Co-decontamination and co-extraction process: carried out in a co-decontamination extractor, the process is divided into a co-decontamination extraction section and a co-decontamination washing section, and the obtained 1AP enters the neptunium and ...

Embodiment 2

[0054] The composition of 1AP in this example is listed in Table 4.

[0055] Table 4

[0056] 1AP composition

concentration

U

90g / L

Pu

0.88g / L

Np

0.06g / L

Tc

0.18g / L

HNO 3

0.15M

[0057] The 1AP obtained through the joint decontamination and co-extraction process as shown in Table 4 enters the following process:

[0058] Neptunium and plutonium stripping process: carried out in the neptunium and plutonium stripping tank, using the process of 6-stage stripping + 6-stage supplementary extraction (see Table 5 for process conditions), and 1B is separated 1 W (containing neptunium, plutonium) and 1B 1 P (with uranium, technetium), 1B 1 P enters the technetium stripping process.

[0059] Technetium reduction and stripping process: carried out in the technetium stripping tank, using the process of 6-stage stripping + 6-stage supplementary extraction (see Table 5 for process conditions), and 1B is separate...

Embodiment 3

[0066] In this embodiment, the steps of co-decontamination and co-extraction and the steps of stripping neptunium and plutonium are omitted, and the bench experiment process in the technetium stripping tank is mainly described. Process such as figure 1 The technological conditions of the technetium stripping tank shown are shown in Table 7.

[0067]

[0068] In this example, the stripping agent S2 is composed of two reducing agents, and its dosage greatly exceeds the theoretical stoichiometric amount for reducing technetium. One of the reducing agents U(IV) is prepared by electrolytic reduction of U(VI). Sophisticated craftsmanship. Overall, the experiment adopted a relatively conservative process. Excess reductant U(IV) has a relatively high distribution in the organic phase, and uranium will not be lost to the technetium product stream. The excess hydrazine is mainly retained in the water phase, that is, the technetium product, and will not have adverse effects on subs...

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Abstract

The invention relates to a PUREX process for separating technetium. The PUREX process includes the steps: (1) co-decontamination and co-extraction: co-extracting uranium, plutonium, neptunium and the technetium in spent fuel nitric acid solution into an organic phase and washing co-extraction liquid; (2) plutonium and neptunium reverse extraction: reversely extracting the plutonium and the neptunium in the co-extraction liquid into a water phase by reverse extraction agents S1 containing AHA and then adding uranium supplement extraction agents for supplement extraction to obtain the water phase containing the plutonium and the neptunium and an oil phase containing the uranium and the technetium; (3) technetium reduction and reverse extraction: reducing and reversely extracting the technetium in the oil phase containing the uranium and the technetium into the water phase by reverse extraction agents S2 containing reducing agents and then adding uranium supplement extraction agents for supplement extraction to obtain a water phase containing the technetium and an oil phase containing the uranium, wherein the oil phase containing the uranium enters a subsequent uranium purification process. The neptunium, the plutonium and the technetium are reduced step by step through a step-by-step reduction method, the technetium can be separated out, the trend of elements is simpler and more uniform, all the reducing agents are salt-free reagents, remaining reagents are easily damaged, and the subsequent process is less affected.

Description

technical field [0001] The invention belongs to the technical field of spent fuel reprocessing flow, and in particular relates to a PUREX flow for separating technetium. Background technique [0002] Currently, the only commercial spent fuel reprocessing process in the world is the PUREX process. This process uses TBP as the extraction agent to extract elements such as uranium (U), plutonium (Pu), neptunium (Np) and technetium (Tc) from the nitric acid solution of spent fuel, and then use the reducing agent U(IV) to reduce and strip Pu(IV) realizes the separation of uranium and plutonium, and then obtains pure uranium and plutonium products through respective purification cycles. [0003] 99 Tc is a nuclide with long life, high yield and high natural mobility, and it is a nuclide that needs to be paid attention to in the spent fuel reprocessing process. [0004] The main recovery target elements in the PUREX process are uranium and plutonium, and some reprocessing plants ...

Claims

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Application Information

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IPC IPC(8): G21F9/06G21F9/20C22B61/00C22B60/02
Inventor 刘方郑卫芳王辉孙亚茹
Owner CHINA INSTITUTE OF ATOMIC ENERGY
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