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Method for coextracting uranium, plutonium and neptunium

A technology of extraction and co-extraction of neptunium, applied in the fields of co-extraction of neptunium, uranium, and plutonium, which can solve the problems of low neptunium extraction rate, increased salt content of radioactive waste, and increased difficulty and cost of nuclear waste disposal

Active Publication Date: 2013-10-30
CHINA INSTITUTE OF ATOMIC ENERGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In addition, because the above formula is a reversible reaction, there will still be some Np(V) that cannot be oxidized into Np(VI), making it difficult for the neptunium in the feed liquid to be completely extracted into the 1AP organic phase, and the extraction rate of neptunium is not high. For example, in The extraction rate of neptunium from the solution to the organic phase in the co-decontamination (1A) stage is about 82% in the French UP-3 factory, about 70% in the British Wenzkell factory, and about 88% in the Japanese dynamic combustion group
[0014] In order to oxidize neptunium in the solution to the hexavalent state, the Japan Institute of Atomic Energy developed the PARC process using NH 4 VO 3 Oxidize Np(V) to Np(VI), but this method can only extract 92% neptunium into the organic phase, and due to the excessive addition of NH 4 VO 3 , a large amount of NH 4 VO 3 After entering the high-level waste liquid, it will increase the salt content of radioactive waste, thereby increasing the difficulty and cost of nuclear waste disposal

Method used

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  • Method for coextracting uranium, plutonium and neptunium
  • Method for coextracting uranium, plutonium and neptunium
  • Method for coextracting uranium, plutonium and neptunium

Examples

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Embodiment 1

[0035] The co-extraction method of uranium, plutonium and neptunium, the method is to co-extract neptunium, uranium and plutonium in the co-decontamination section, so that it enters the organic phase 1AP, the key is to oxidize Np(V) into energy Np(VI) extracted by the extractor.

[0036] figure 1 Schematic diagram of the co-decontamination separation cycle. The total decontamination section is divided into two parts, 1AX to 1AF is the extraction section, and 1AF to 1AS is the washing section.

[0037] 1AF is a nuclear fuel solution, which is an aqueous solution of nitric acid containing uranium, plutonium, neptunium, minor actinides MA (neptunium, americium, curium), splinter elements, etc., 1AF is fed from the middle of the extractor; 1AX is an extraction agent, composed of 30% TBP / kerosene, the extractant is fed from the outlet stage of the aqueous phase raffinate of the extractor; 1AS is the detergent, which is an aqueous solution of nitric acid, fed from the outlet stag...

Embodiment 2

[0040] The co-extraction method of uranium, plutonium and neptunium, the method is to co-extract neptunium, uranium and plutonium in the co-decontamination section, so that it enters the organic phase 1AP, the key is to oxidize Np(V) into energy Np(VI) extracted by the extractor.

[0041] figure 1 It is a schematic diagram of the co-decontamination separation cycle, in which the concentration of nitric acid in 1AF is 3.50 mol / L, and the concentration of nitric acid in 1AS is 3.0 mol / L. The concentration of nitrous acid in the aqueous phase of the extraction section is 1×10 -4 mol / L. The flow ratio range of 1AX:1AS (organic phase: aqueous phase) is 3:1 and the uranium saturation is 60%. The operating temperatures of the extraction section and the washing section are 50°C and 20°C, respectively.

[0042] Using UV-ultraviolet-visible spectrophotometer to analyze the concentration of uranium and nitrous acid in the sample, the yield of uranium product is greater than 99.99%, an...

Embodiment 3

[0044] The same as the method used in Example 2, the difference is the process parameters, wherein the concentration of nitric acid in 1AF is 4.50mol / L, and the concentration of nitric acid in 1AS is 3.5mol / L. The concentration of nitrous acid in the aqueous phase of the extraction section is 8×10 -4 mol / L. 1AX:1AS flow ratio range is 5:1. The uranium saturation is 65%, and the operating temperatures of the extraction section and the washing section are 40°C and 25°C, respectively.

[0045] Using UV-ultraviolet-visible spectrophotometer to analyze the concentration of uranium and nitrous acid in the sample, the yield of uranium product is greater than 99.99%, and the concentration of plutonium and neptunium in the sample is analyzed by alpha energy spectrum, and the yield of plutonium is greater than 99.9%. , The yield of neptunium is greater than 99%.

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Abstract

The invention belongs to the technical field of nuclear fuel cycles, and discloses a method for coextracting uranium, plutonium and neptunium. The method is implemented in a way that: neptunium is coextracted with uranium and plutonium at the co-decontamination section, so that the neptunium enters an organic phase 1AP. The key point is to oxidate Np (V) in an extraction apparatus 1A into Np (VI) which can be extracted by the extraction apparatus. The method implements high yields of uraniumm, plutonium and neptunium, does not increase the salt content in the after-treatment process, and can implement quantitative extraction of the uranium, plutonium and neptunium.

Description

technical field [0001] The invention belongs to the technical field of nuclear fuel cycle, and in particular relates to a method for co-extracting uranium, plutonium and neptunium. Background technique [0002] 237 Np is a transuranium element, a fissile nuclear material, one of the by-products of reprocessing plants, and its half-life is as long as 2.14×10 6 year. In a typical light water reactor spent fuel, each ton of spent fuel contains about 500-700 grams 237 Np; in fast reactor spent fuel, about 200 g per ton of spent fuel 237 Np. [0003] because 237 Np is highly radioactive and toxic. If it is used as nuclear waste in the nuclear fuel cycle for geological disposal after vitrification, the disposal cost will be high and it will have an inestimable impact on the ecological environment. And if it will be greater than 99% 237 The separation of Np from spent fuel can greatly reduce the radiotoxicity of nuclear waste and the cost of geological disposal. In addition...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G21C19/46C22B60/02C22B60/04
CPCY02E30/30Y02W30/50
Inventor 张虎叶国安李丽
Owner CHINA INSTITUTE OF ATOMIC ENERGY