CN116835655B - A method for preparing UO2 from U3O8 - Google Patents

A method for preparing UO2 from U3O8

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Publication number
CN116835655B
CN116835655B CN202310268266.3A CN202310268266A CN116835655B CN 116835655 B CN116835655 B CN 116835655B CN 202310268266 A CN202310268266 A CN 202310268266A CN 116835655 B CN116835655 B CN 116835655B
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temperature
vacuum
preparing
activated carbon
sintering
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CN116835655A (en
Inventor
许恒斌
杨明帅
宋文臣
沈振芳
李斌
王长水
何辉
晏太红
叶国安
李保乐
姚本林
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China Institute of Atomic of Energy
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China Institute of Atomic of Energy
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G43/00—Compounds of uranium
    • C01G43/01—Oxides; Hydroxides
    • C01G43/025—Uranium dioxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)

Abstract

The invention discloses a method for preparing UO 2 by using U 3O8, which adopts activated carbon to reduce U 3O8, shortens the intermolecular distance between the activated carbon and U 3O8 by tabletting and forming, prevents gas from entraining powder in the reaction process, greatly increases the contact area with U 3O8 by the porous structure of the activated carbon, improves the reduction efficiency, removes the activated carbon from the final product UO 2, ensures the purity of the UO 2, has simple method, short period and high safety, and is suitable for preparing the UO 2 by reducing U 3O8 on a large scale.

Description

Method for preparing UO 2 by U 3O8
Technical Field
The invention belongs to the technical field of spent fuel aftertreatment, and particularly relates to a method for preparing UO 2 by using U 3O8.
Background
Uranium dioxide is an important component of fast reactor MOX fuel, and has important application prospect in fast neutron breeder reactor (FBR). The most stable oxide form of uranium is triuranium octoxide, and uranium dioxide can be spontaneously converted into triuranium octoxide at room temperature, so that the physical and chemical properties of the uranium octoxide are changed.
The common uranium dioxide production process is an Ammonium Diuranate (ADU) method, namely, the Ammonium Diuranate (ADU) is obtained by taking UF6 as a raw material through hydrolysis and precipitation, and then the Ammonium Diuranate (ADU) is decomposed and reduced into uranium dioxide powder under the atmosphere of H 2. However, the process for preparing uranium dioxide has long production period, complex working procedures and unstable O/U ratio of the obtained uranium dioxide powder.
Disclosure of Invention
Aiming at the technical problems existing in the prior art, the invention aims to provide a method for preparing UO 2 by using U 3O8, which has the advantages of stable O/U ratio, safe, simple and efficient operation process.
In order to achieve the aim of the invention, the technical scheme adopted by the invention is as follows, namely a method for preparing UO 2 by U 3O8, which comprises the following steps:
(1) Uniformly mixing activated carbon and triuranium octoxide in a proper proportion, and tabletting for molding;
(2) Carrying out low-temperature vacuum sintering on the pressed active carbon and triuranium octoxide;
(3) High-temperature vacuum heating to remove active carbon;
(4) And cooling to below 50 ℃ in vacuum to obtain the UO 2 core block.
Further, in the step (1), the amount of the activated carbon is more than 2.9% of the mass of the triuranium octoxide.
Further, in the step (2), the temperature of the low-temperature vacuum sintering is 500-1300 ℃, the vacuum degree is less than 100Pa, and the sintering time is 0-8 h.
Further, in the step (3), the high-temperature vacuum heating temperature is higher than 1300 ℃, the vacuum degree is less than 100Pa, and the heating time is 0-8 h.
Further, in the step (4), the vacuum cooling temperature is 20-30 ℃.
The method for preparing the UO 2 by adopting the technical scheme has the beneficial effects that the method for preparing the UO 2 by adopting the U 3O8 has the advantages that the active carbon is adopted to reduce U 3O8, the intermolecular distance of reactants is shortened by tabletting and forming, the entrainment of gas to powder in the reaction process is prevented, the porous structure of the active carbon greatly increases the contact area with U 3O8, the reduction efficiency is improved, the active carbon is removed from the final product UO 2, the purity of the UO 2 is ensured, and the method is simple, short in period and high in safety, and is suitable for preparing the UO 2 by reducing U 3O8 on a large scale.
Drawings
FIG. 1 is an XRD pattern of UO 2 prepared by the method of example two of the present invention;
FIG. 2 is an XRD pattern of UO 2 prepared by the method of example three of the present invention;
FIG. 3 is an XRD pattern for UO 2 prepared by the method of example four of the present invention.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings and examples.
Example 1
The embodiment of the invention provides a method for preparing UO 2 by U 3O8, which comprises the following steps:
(1) Mixing a proper amount of active carbon and triuranium octoxide uniformly, tabletting and forming, wherein the dosage of the active carbon is 2.9% of the mass of the triuranium octoxide, so that the excessive active carbon is ensured, the reduction rate of the triuranium octoxide is ensured, the intermolecular distance of reactants is shortened through tabletting and forming, the reaction is easier to occur, and the entrainment of gas to powder in the reaction process can be prevented;
(2) Carrying out low-temperature vacuum sintering on the pressed active carbon and triuranium octoxide, wherein the low-temperature vacuum sintering temperature is 500-1300 ℃, the vacuum degree is less than 100Pa, and the sintering time is 0-8 h
(3) High-temperature vacuum heating to remove active carbon, wherein the temperature of the high-temperature vacuum heating is more than 1300 ℃, the vacuum degree is less than 100Pa, and the heating time is 0-8 h;
(4) And cooling to below 50 ℃ in vacuum to obtain the UO 2 core block. In the cooling process, UO 2 pellets are prevented from being oxidized again due to contact with air, and the stable O/U ratio is maintained.
Preferably, in the step (1), the pressure range of tabletting and forming is 56-226 mpa, and under the pressure range, the formed activated carbon and triuranium octoxide block are not loose and are not easy to break.
Preferably, in the step (2), the vacuum temperature is 900 ℃, the vacuum degree is 0.1Pa, and the sintering time is 4 hours.
Preferably, in the step (3), the high-temperature sintering temperature is 1500 ℃, the vacuum degree is 0.1Pa, and the sintering time is 4 hours.
Preferably, in the step (4), the temperature is reduced to 20 ℃ to 30 ℃ in vacuum.
Example two
The preparation of UO 2 by the method U 3O8 of the first embodiment of the invention comprises the following steps:
(1) Weighing active carbon with the mass ratio of 0.12:1, uniformly mixing the active carbon with triuranium octoxide, and uniaxially pressing the mixture in a steel mould (8 mm) for 3min under the pressure of 113MPa for molding;
(2) Placing the sample into a vacuum furnace, and vacuum sintering for 4 hours at 900-0.1 Pa;
(3) Cooling to room temperature under vacuum of 0.1Pa, and taking out the sample.
The sample was weighed, the mass of the sample after the reaction was 1.053g, the mass loss of the sample was 0.067g, and the sample was completely and fully burned in an air atmosphere at 600 ℃ to obtain a powder mass of 0.99g.
Referring to FIG. 1, a sample prepared by the method of the present invention is shown with excess activated carbon doped therein
The rest is the same as the first embodiment.
Example III
The preparation of UO 2 by the method U 3O8 of the first embodiment of the invention comprises the following steps:
(1) Weighing active carbon with the mass ratio of 0.12:1, uniformly mixing the active carbon with triuranium octoxide, and uniaxially pressing the mixture in an 8mm steel mould for 3min under the pressure of 113MPa for molding;
(2) Placing the sample into a vacuum furnace, and vacuum sintering for 4 hours at 900-0.1 Pa;
(3) Vacuum sintering for 4h at 1500 ℃ to 0.1 Pa;
(4) Cooling to room temperature under vacuum of 0.1Pa, and taking out the sample.
Referring to fig. 2, the process of the present embodiment converts U 3O8 to UO 2 completely, weighs the sample, loses 0.159g of sample mass, and substantially removes excess activated carbon.
The rest is the same as the first embodiment.
Example IV
The preparation of UO 2 by the method U 3O8 of the first embodiment of the invention comprises the following steps:
(1) Weighing active carbon with the mass ratio of 0.12:1, uniformly mixing the active carbon with triuranium octoxide, and uniaxially pressing the mixture in an 8mm steel mould for 3min under the pressure of 113MPa for molding;
(2) Placing the sample into a vacuum furnace, and vacuum sintering for 4 hours at 900 ℃ and 0.1 Pa;
(3) Continuously sintering for 4 hours under the condition of 1500 ℃ and 0.1 Pa;
(4) The furnace cover is opened after the temperature is reduced to 300 ℃ under the vacuum condition of 0.1 Pa.
The columnar sample in the furnace burns rapidly in the process of uncovering, turns into powder in 1min, and is weighed after collection, and the mass is 0.98g.
Referring to FIG. 3, it is shown that the reduced U 3O8 was reoxidized again during the uncapping process, and that a mass loss of 0.02g was an operational error during the powder transfer process.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (4)

1. A method for preparing UO 2 from U 3O8, comprising the steps of:
(1) Uniformly mixing an appropriate amount of activated carbon and triuranium octoxide, and tabletting to form, wherein the amount of the activated carbon is 2.9% of the mass of the triuranium octoxide;
(2) Carrying out low-temperature vacuum sintering on the pressed active carbon and triuranium octoxide, wherein the temperature of the low-temperature vacuum sintering is 500-1300 ℃, the vacuum degree is less than 100Pa, and the sintering time is 4-8 hours;
(3) High-temperature vacuum heating to remove active carbon, wherein the temperature of the high-temperature vacuum heating is more than 1300 ℃, the vacuum degree is less than 100Pa, and the heating time is 4-8 hours;
(4) And cooling to below 50 ℃ in vacuum to obtain the UO 2 core block.
2. The method for preparing UO 2 from U 3O8 according to claim 1, wherein in step (2), the low-temperature vacuum sintering temperature is 900 ℃, the vacuum degree is 0.1Pa, and the sintering time is 4h.
3. The method for preparing UO 2 from U 3O8 according to claim 1, wherein in step (3), the high-temperature vacuum heating temperature is 1500 ℃, the vacuum degree is 0.1Pa, and the sintering time is 4 hours.
4. The method for preparing UO 2 from U 3O8 according to claim 1, wherein in the step (4), the temperature is reduced to 20-30 ℃ in vacuum.
CN202310268266.3A 2023-03-15 2023-03-15 A method for preparing UO2 from U3O8 Active CN116835655B (en)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3953556A (en) * 1973-01-12 1976-04-27 The United States Of America As Represented By The United States Energy Research And Development Administration Method of preparing uranium nitride or uranium carbonitride bodies

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2790548B2 (en) * 1991-03-29 1998-08-27 原子燃料工業株式会社 Manufacturing method of nuclear fuel sintered body
JP2813926B2 (en) * 1991-08-12 1998-10-22 原子燃料工業株式会社 Uranium dioxide powder for nuclear fuel and method for producing the same
CN1133176C (en) * 2001-03-30 2003-12-31 中国核动力研究设计院 Method for preparing Gd2O3-UO2 flammable poison fuel core block by using U3O8 powder
KR101252110B1 (en) * 2011-12-13 2013-04-12 한국수력원자력 주식회사 The method for producing porous uo2 sintered pellet for electroreduction process using discontinuous process, and the porous uo2 sintered pellet thereby
CN106297904B (en) * 2016-08-25 2018-04-17 中广核研究院有限公司 UO2The preparation method of SiC fuel pellets and using UO made of the preparation method2SiC fuel pellets

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3953556A (en) * 1973-01-12 1976-04-27 The United States Of America As Represented By The United States Energy Research And Development Administration Method of preparing uranium nitride or uranium carbonitride bodies

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