Preparation method of reactor MOX fuel powder

Abstract

The invention relates to a reactor MOX fuel powder preparation method, which comprises: preparing a mixed actinide eutectic melt from a mixed actinide salt and a urea solid, and carrying out deamination, denitrification / decarbonization and reduction on the mixed actinide eutectic melt to directly obtain MOX fuel powder, when the mixed actinide salt is a uranyl nitrate hexahydrate solid and a thorium nitrate hexahydrate solid, the MOX fuel powder is (UxTh1-x) O2; when the mixed actinide salt is a uranyl nitrate hexahydrate solid and a plutonium nitrate pentahydrate solid, the MOX fuel powder is (UxPu1-x) O2. According to the method, uranyl nitrate solid and plutonium nitrate / thorium nitrate are directly adopted as raw materials, the preparation technological process for preparing the MOX fuel powder can be greatly simplified, use of process reagents is reduced, no process waste liquid is generated, the chemical composition uniformity of the obtained MOX fuel powder is good, and therefore the method which is simple, convenient and environmentally friendly is provided. The preparation method of the MOX fuel powder is simple in process, high in production efficiency, free of waste liquid and more economical and green.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear fuel preparation, and in particular relates to a method for preparing reactor MOX fuel powder. Background Art

[0002] MOX fuel is one of the most popular nuclear fuel types in recent years. It is one of the key links to achieve closed nuclear fuel cycle and sustainable development of nuclear energy. In the MOX fuel preparation process, powder preparation is a key link. The quality of the powder, including composition and uniformity (impurities, isotopes), and the performance of the powder (particle size, specific surface area, bulk density, etc.) directly affects the performance of the subsequent pellets. Therefore, MOX powder manufacturing has always been the focus of MOX fuel manufacturing research at home and abroad.

[0003] In order to obtain uniformly mixed MOX fuel powder, a lot of research has been carried out at home and abroad, and multiple process flows have been developed. According to the different powder mixing methods, they are mainly divided into two categories: mechanical mixing method (commonly known as dry method) and chemical co-precipitation method (commonly known as wet method). The wet method can obtain better product uniformity and form solid solution powder. The wet method includes the German uranium tricarbonate plutonium ammonium co-precipitation process

[0004] (AUPuC), Japan formed by microwave denitrification of a 1:1 mixed solution of plutonium nitrate and uranyl nitrate (U 0.5 Pu 0.5 )O2 solid solution powder. The dry method was first used for the production of fast reactor MOX fuel with a high PuO2 content. The two-step mixing method developed by France and Belgium, namely the micronized main mixing (MIMAS) process, replaced the original French one-step mixing (COCA) process and can be used for the production of LWR (light water reactor) MOX fuel with a low PuO2 content. The binderless process (SBR) developed by the United Kingdom has a better distribution uniformity of Pu than the MIMAS process. Russia relies on the ABC-150 high-efficiency magnetic mixer to prepare uniform MOX powder. The above-mentioned wet process has a long process flow and a lot of waste liquid, and it is difficult to adapt to the requirements of products with different abundances and contents; the dry grinding process is difficult to operate, has high requirements on equipment and process parameters, and inevitably has the problem of plutonium-rich particles. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing reactor MOX fuel powder, using a low eutectic formed by uranyl nitrate hexahydrate, plutonium nitrate pentahydrate (or thorium nitrate hexahydrate) and urea to prepare a microscopic (molecular level) uniformly mixed uranyl nitrate pentahydrate (or thorium nitrate hexahydrate) containing (U x Pu 1-x )O2 or (U x Th 1-x)O2, and the obtained MOX fuel powder can be used to produce MOX fuel for irradiation in LWR, FNR and other reactor types.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing reactor MOX fuel powder, the method comprising the following steps:

[0007] S1. Preparing a mixed actinide eutectic: mixing a dry mixed actinide salt with urea solid in a certain proportion until the mixture becomes a completely clear liquid, thereby obtaining a mixed actinide eutectic; the mixed actinide salt is a hexavalent actinide nitrate and a tetravalent actinide nitrate;

[0008] S2, deamination: the mixed actinide eutectic is heated to a specified temperature according to a specified procedure and kept at the temperature for a specified time to obtain a deamination powder, wherein the deamination powder comprises a mixed actinide salt and an actinide oxide;

[0009] S3, denitrification: the deamination powder is heated to a set temperature according to a set program and kept at the temperature for a set time to obtain a denitrification powder;

[0010] S4, reduction: the denitrified powder is heated to a certain temperature according to a certain procedure under an argon atmosphere, and then switched to a hydrogen-argon mixed gas or a hydrogen atmosphere and kept warm for a certain period of time to obtain MOX fuel powder.

[0011] Furthermore, the hexavalent actinide nitrate is a solid uranyl nitrate hexahydrate, and the tetravalent actinide nitrate is a solid thorium nitrate hexahydrate or a solid plutonium nitrate pentahydrate.

[0012] Furthermore, the molar ratio of the metal ions in the mixed actinide salt to the urea is 1:9.

[0013] Furthermore, the molar ratio of uranyl nitrate hexahydrate solid to thorium nitrate hexahydrate solid in the mixed actinide salt is any ratio, or the molar ratio of uranyl nitrate hexahydrate solid to plutonium nitrate pentahydrate solid in the mixed actinide salt is any ratio.

[0014] Furthermore, in the process of mixing the mixed actinide salt and the urea solid in step S1, the mixture is mixed by stirring and / or grinding the mixture.

[0015] Furthermore, in the process of mixing the mixed actinide salt and urea solid in step S1, the mixed actinide salt and urea mixture is heated to obtain a completely clarified mixed actinide eutectic.

[0016] Further, step S2 includes the following specific steps: sucking the mixed actinide eutectic into a crucible by a pipette, and heating the crucible to 150-160° C. according to a specified program and keeping the temperature for more than 30 minutes to obtain the deaminated powder.

[0017] Further, in step S2, the deamination process is carried out under air or argon atmosphere;

[0018] The specified procedure refers to a specified heating rate, and the specified heating rate is 5-10°C / min.

[0019] Furthermore, when the mixed actinide salt is a hexahydrated uranyl nitrate solid and a hexahydrated thorium nitrate solid, the denitrification powder is a U3O8 and ThO2 powder; when the mixed actinide salt is a hexahydrated uranyl nitrate solid and a pentahydrated plutonium nitrate solid, the denitrification powder is a U3O8 and PuO2 powder.

[0020] Furthermore, in step S3, the deaminated powder is heated to 500-800° C. according to a set program and kept warm for more than 30 minutes to obtain a denitrified powder.

[0021] Further, in step S3, the denitrification process is carried out under air or argon atmosphere;

[0022] The setting procedure refers to the setting heating rate, and the setting heating rate is 5-10°C / min.

[0023] Further, in step S4, the denitrified powder is heated to 680-900° C. at a heating rate of 5-10° C. / min under an argon atmosphere, and then switched to a hydrogen-argon mixed gas or hydrogen atmosphere and kept warm for 10-30 minutes to obtain MOX fuel powder.

[0024] Further, when the mixed actinide salt is solid uranyl nitrate hexahydrate and solid thorium nitrate hexahydrate, the MOX fuel powder is (U x Th 1-x )O2; when the mixed actinide salt is solid uranyl nitrate hexahydrate and solid plutonium nitrate pentahydrate, the MOX fuel powder is (U x Pu 1-x )O2;

[0025] Among them, 0.0<X<1.0.

[0026] The beneficial effects of the present invention are as follows: a method for preparing a reactor MOX fuel powder provided by the present invention is adopted, and the following steps are performed: preparing a mixed actinide eutectic from a mixed actinide salt and a urea solid, and directly obtaining the MOX fuel powder by deamination, denitrification / decarbonization, and reduction of the mixed actinide eutectic; when the mixed actinide salt is a hexahydrate uranyl nitrate solid and a hexahydrate thorium nitrate solid, the MOX fuel powder is (U x Th 1-x )O2; when the mixed actinide salt is solid uranyl nitrate hexahydrate and solid plutonium nitrate pentahydrate, the MOX fuel powder is (U x Pu 1-x )O2. The method provided by the present invention directly uses solid uranyl nitrate and plutonium nitrate / thorium nitrate as raw materials, which has the advantage of simple raw materials, can greatly simplify the preparation process of MOX fuel powder composed of UO2 and PuO2 (or ThO2), reduce the use of process reagents, and no process waste liquid is generated, thereby providing a simple, high-efficiency, waste-free, more economical and green MOX fuel powder preparation method. The specific beneficial effects of the present invention are mainly reflected in:

[0027] (1) A mixed actinide eutectic obtained by directly mixing three solids, uranyl nitrate hexahydrate, plutonium nitrate pentahydrate (or thorium nitrate hexahydrate) and urea in a certain proportion and being liquid at room temperature is used as the mother liquor for preparing MOX fuel powder. Compared with the wet method in which two actinides are first dissolved into solutions and then co-precipitated under certain conditions, the process is simple, with fewer steps, high efficiency and no waste liquid is generated; the mixed actinide eutectic can be decomposed at a certain temperature to obtain MOX fuel powder, and only a high-temperature sintering atmosphere furnace is required, which is an existing general equipment in conventional UO2 fuel production. No other special equipment is required. Compared with the dry method, it is simple to operate and does not require additional equipment. This method can greatly simplify the process flow, effectively reduce production costs, and has better economy and safety.

[0028] (2) The mixed actinide eutectic prepared by the present invention has very stable properties and requires only one additive, urea, which is easily available, low in cost, and can be completely removed by heating to around 160°C.

[0029] (3) The MOX fuel powder prepared by the present invention has good uniformity of chemical composition and is evenly mixed at the microscopic molecular level.

[0030] (4) The preparation method of MOX fuel powder provided by the present invention can prepare MOX powder particles of various sizes and shapes as needed. For example, by using vibration dispersion method, microfluidics method, two-phase dispersion method or aerosol spray method, monodisperse MOX microspheres with a controllable particle size range of 1 μm to 1 mm and a narrow particle size distribution range can be prepared, which can be applied to TRISO fuel and other purposes as a new, economical and green MOX microsphere preparation scheme. Moreover, the preparation scheme of MOX fuel powder can also be expanded to all hexavalent actinide nitrate and tetravalent actinide nitrate systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic flow chart of a method for preparing reactor MOX fuel powder according to an embodiment of the present invention;

[0032] Figure 2 It is a process flow chart comparing the method provided by this embodiment of the present invention with the dry method and the wet method for preparing MOX fuel powder;

[0033] Figure 3 This is a diagram showing the elemental surface distribution analysis result of the MOX fuel powder prepared in Example 1 of the present invention using a scanning electron microscope-energy spectrum method. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be further clearly and completely described below in conjunction with the drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] Deep eutectic solvents (DES) are generally composed of two or three components, often a mixture of metal salts and hydrogen bond donors. The components are connected to each other by hydrogen bonds and have a small lattice energy, which results in the melting point of the deep eutectic mixture being lower than the melting point of any component alone. Macroscopically, most deep eutectic mixtures are liquid at room temperature. In the article "Structure and properties of 'Type IV' lanthanide nitrate hydrate: urea eutectic solvents" published by Hammond et al. in Sustainable Chemistry & Engineering of ACS in 2019, the performance and structure of the deep eutectic mixture formed by the mixture of trivalent lanthanide metals such as cerium, protactinium and neodymium with urea were studied, and the hydrogen bonding between water and urea was confirmed. In the article "Electrochemical and thermodynamic insights on actinide type (IV) deep eutectic solvent" published in Journal of Molecular Liquids in 2021, Ruma Gupta et al. found that when uranyl nitrate hexahydrate (UNH) and urea are mixed in a certain proportion, a low eutectic will also be formed. By adjusting the ratio of uranyl nitrate hexahydrate to urea (molar ratio of 1:4), the melting point can be reduced to below 0°C, and UO2 nanocrystals are prepared by electrochemical reduction of the low eutectic.

[0036] In the previous study, the inventors found that when the molar ratio of uranyl nitrate hexahydrate to urea was 1:9, a low eutectic could also be formed, and it was stable for several months at room temperature, and its stability was better than that of the 1:4 type uranium-containing low eutectic. The 1:9 type uranium-containing low eutectic, combined with the microfluidics method or the vibration dispersion method, can be used to prepare UO2 fuel core microspheres with tristructural isotropic (TRISO) coated fuel particles for high temperature gas-cooled reactor fuel.

[0037] In an embodiment of the present invention, the inventors have discovered through research that a low eutectic can also be formed when the ratio of mixed actinide salts (uranyl nitrate hexahydrate + thorium nitrate hexahydrate / plutonium nitrate pentahydrate) to urea is a molar ratio of 1:9. Based on this, a method for preparing reactor MOX fuel powder is provided, and its technical concept is: after adding a small amount of co-solvent to uranyl nitrate powder and thorium nitrate (or plutonium nitrate) powder, a uniform liquid-low eutectic (DES) is obtained, and after heating, the co-solvent is removed and the nitrate is decomposed to obtain a mixed oxide powder with a uniformly mixed elemental composition at the microscopic level (molecular level). This method is an advanced anhydrous process with a simple process and easy operation, which can reduce the use of process reagents, does not generate waste liquid, simplifies the operation process, and does not require additional equipment, thereby reducing production costs and improving production efficiency. The process flow comparison of the method provided in this embodiment with the dry and wet methods for preparing MOX fuel powder is shown in the figure below. Figure 2 shown.

[0038] like Figures 1 to 3 As shown, this embodiment provides a method for preparing reactor MOX fuel powder, the method comprising the following steps:

[0039] S1. preparing a mixed actinide eutectic: mixing a dry mixed actinide salt with urea solid in a certain proportion until the mixture becomes a completely clear liquid to obtain a mixed actinide eutectic;

[0040] Optionally, the mixed actinide salt includes hexavalent actinide nitrate and tetravalent actinide nitrate.

[0041] Specifically, the hexavalent actinide nitrate is uranyl nitrate hexahydrate (UNH) solid, and the tetravalent actinide nitrate is thorium nitrate hexahydrate solid or plutonium nitrate pentahydrate solid; that is, the mixed actinide salt is uranyl nitrate hexahydrate solid and thorium nitrate hexahydrate solid, or the mixed actinide salt is uranyl nitrate hexahydrate solid and plutonium nitrate pentahydrate solid.

[0042] Specifically, the molar ratio of the metal ions in the mixed actinide salt to the urea is 1:9.

[0043] Optionally, the molar ratio of uranyl nitrate hexahydrate solid to thorium nitrate hexahydrate solid in the mixed actinide salt is any ratio, or the molar ratio of uranyl nitrate hexahydrate solid to plutonium nitrate pentahydrate solid in the mixed actinide salt is any ratio.

[0044] In a specific embodiment, the molar ratio of uranyl nitrate hexahydrate solid to thorium nitrate hexahydrate solid in the mixed actinide salt is 1:1, or the molar ratio of uranyl nitrate hexahydrate solid to plutonium nitrate pentahydrate solid in the mixed actinide salt is 1:1.

[0045] Optionally, during the mixing process of the mixed actinide salt and urea in step S1, the mixed actinide salt and urea are mixed uniformly by stirring the mixture.

[0046] In a specific embodiment, when the sample amount of the mixed actinide eutectic to be prepared is large, the mixed actinide salt and urea can be uniformly mixed by grinding and stirring in a mortar.

[0047] Optionally, in step S1, the mixture formed by the mixed actinide salt and urea is heated to mix the mixed actinide salt and urea uniformly to obtain a completely clarified mixed actinide eutectic.

[0048] In a specific embodiment, in step S1, the specific method of heating is: heating the mixture formed by the mixed actinide salt and urea on a hot plate, and the heating condition is heating at 80-100° C. for about 5-10 minutes.

[0049] S2, deamination: the mixed actinide eutectic is heated to 150-160° C. according to a specified procedure and kept at this temperature for more than 30 minutes to obtain a deamination powder, wherein the deamination powder comprises a mixed actinide salt and an actinide oxide;

[0050] Specifically, in step S2, the mixed actinide eutectic is sucked into a crucible by a pipette, and the crucible is heated to 150-160° C. according to a specified program and kept warm for more than 30 minutes to remove urea in the mixed actinide eutectic. The obtained deaminated powder includes a uniformly mixed mixed actinide salt and actinide oxides formed after thermal decomposition of a part of the mixed actinide salt to remove nitrate.

[0051] Optionally, in step S2, the deamination process is carried out in air or argon atmosphere, and the specified procedure refers to a specified heating rate, and the specified heating rate is 5-10°C / min.

[0052] S3, denitrification: the deamination powder is heated to 500-800°C according to a set program and kept warm for more than 30 minutes to obtain a denitrification powder;

[0053] Specifically, when the mixed actinide salt is a hexahydrated uranyl nitrate solid and a hexahydrated thorium nitrate solid, the denitrification powder is U3O8 and ThO2 powder; when the mixed actinide salt is a hexahydrated uranyl nitrate solid and a pentahydrated plutonium nitrate solid, the denitrification powder is U3O8 and PuO2 powder.

[0054] Specifically, in step S3, the denitrification process is carried out in air or argon atmosphere, the deaminated powder is heated to 500-800°C according to a set program and kept warm for more than 30 minutes, the mixed actinide nitrate in the deaminated powder undergoes thermal decomposition, and the obtained denitrification powder is the corresponding actinide metal oxide U3O8 and PuO2 powder, or U3O8 and ThO2 powder.

[0055] Optionally, in step S3, following a set program refers to following a set heating rate, and the set heating rate is 5-10° C. / min.

[0056] S4, reduction: the denitrified powder is heated to 680-900° C. in an argon atmosphere according to a certain procedure, and then switched to a hydrogen-argon mixed gas or hydrogen atmosphere and kept warm for 10-30 minutes to obtain MOX fuel powder.

[0057] Specifically, when the mixed actinide salt is solid uranyl nitrate hexahydrate and solid thorium nitrate hexahydrate, the MOX fuel powder is (U x Th 1-x )O2; when the mixed actinide salt is solid uranyl nitrate hexahydrate and solid plutonium nitrate pentahydrate, the MOX fuel powder is (U x Pu 1-x )O2; wherein, 0.0<X<1.0.

[0058] Optionally, in step S4, following a certain procedure refers to following a certain heating rate, and the certain heating rate is 5-10° C. / min.

[0059] The specific implementation modes of the present invention are further described below through examples.

[0060] Example 1: Eutectic Process (U x Th 1-x Preparation Example of O2 type (i.e., UO2 and ThO2 mixed type, where X = 0.5) MOX fuel powder

[0061] S11, preparing a mixed actinide eutectic: first, taking 0.312 g (0.5 mmol) of dry thorium nitrate hexahydrate solid, 0.251 g (0.5 mmol) of uranyl nitrate hexahydrate solid and 0.5405 g (9 mmol) of urea solid in a transparent glass bottle, the solid powder softens and gradually liquefies during the mixing process, gently shaking the glass bottle to mix the sample thoroughly, heating on a hot plate at 80-100° C. for about 5-10 minutes until the mixture becomes a completely clear liquid, thus obtaining a U(VI) / Th(IV) type mixed actinide eutectic containing 50 At% (atomic percentage) of Th(IV);

[0062] Optionally, when the sample amount of the mixed actinide eutectic to be prepared is large, the mixture may be ground in a mortar and mixed with stirring.

[0063] S12, deamination: use a pipette to draw 20 μl of 50At% U / Th type mixed actinide eutectic into a crucible, heat the liquid to 150-160°C at a heating rate of 10°C / min in an air / argon atmosphere for 30 min to remove urea therein, wherein the actinide nitrate also removes part of the nitrate, and the obtained deamination powder is a powder of mixed actinide salt + part of actinide oxide;

[0064] S13, denitrification / decarbonization: the deaminated powder is heated to 500-800°C at a heating rate of 10°C / min in an air / argon atmosphere and kept at this temperature for more than 30 minutes to fully decompose the nitrate of the mixed actinide salt in the deaminated powder, and the obtained denitrified powder is U3O8 and ThO2 powder;

[0065] S14, reduction: the U3O8 and ThO2 powders are heated to 680-900°C at a heating rate of 10°C / min in an argon atmosphere, and then switched to a 4% hydrogen-argon (V / V) mixed (or pure hydrogen) atmosphere for reduction for 10-15 minutes to obtain a MOX fuel powder (U 0.5 Th 0.5 )O2 type, namely UO2 and ThO2 powder.

[0066] The elemental distribution analysis results of the MOX fuel powder obtained in Example 1 by scanning electron microscope-energy spectrum method are shown in the figure below: Figure 3 shown. Figure 3 The analysis results show that UO2 and ThO2 powders are evenly distributed in the MOX fuel powder prepared in Example 1, which indicates that the chemical composition of the MOX fuel powder obtained in Example 1 is uniform and is evenly mixed at the microscopic molecular level.

[0067] The preparation method of MOX fuel powder provided in this embodiment can prepare MOX powder particles of various sizes and shapes as needed. For example, by using vibration dispersion method, microfluidics method, two-phase dispersion method or aerosol spray method, monodisperse MOX microspheres with a controllable particle size range of 1μm to 1mm and a narrow particle size distribution range can be prepared, which can be used in TRISO fuel and other purposes as a new, economical and green MOX microsphere preparation scheme. The preparation scheme of MOX fuel powder can also be expanded to all hexavalent actinide nitrate and tetravalent actinide nitrate systems.

[0068] The method described in the present invention is not limited to the specific embodiments described. The above embodiments are only examples of the present invention. The present invention can also be implemented in other specific ways or other specific forms without departing from the gist or essential features of the present invention. Therefore, the described embodiments should be regarded as illustrative rather than restrictive in any respect. The scope of the present invention should be described by the attached claims, and any changes equivalent to the intent and scope of the claims should also be included in the scope of the present invention.

Claims

1. A method for preparing reactor MOX fuel powder, characterized in that: The method comprises the following steps: S1. Preparing a mixed actinide eutectic: mixing a dry mixed actinide salt with urea solid in a certain proportion until the mixture becomes a completely clear liquid, thereby obtaining a mixed actinide eutectic; the mixed actinide salt is a hexavalent actinide nitrate and a tetravalent actinide nitrate; S2, deamination: the mixed actinide eutectic is heated to a specified temperature according to a specified procedure and kept at the temperature for a specified time to obtain a deamination powder, wherein the deamination powder comprises a mixed actinide salt and an actinide oxide; S3, denitrification: the deamination powder is heated to a set temperature according to a set program and kept at the temperature for a set time to obtain a denitrification powder; S4, reduction: the denitrified powder is heated to a certain temperature according to a certain procedure under an argon atmosphere, and then switched to a hydrogen-argon mixed gas or a hydrogen atmosphere and kept warm for a certain period of time to obtain MOX fuel powder.

2. The method for preparing reactor MOX fuel powder according to claim 1, characterized in that: The hexavalent actinide nitrate is solid uranyl nitrate hexahydrate, and the tetravalent actinide nitrate is solid thorium nitrate hexahydrate or solid plutonium nitrate pentahydrate.

3. The method for preparing reactor MOX fuel powder according to claim 2, characterized in that: The molar ratio of the metal ions in the mixed actinide salt to the urea is 1:

9.

4. The method for preparing reactor MOX fuel powder according to claim 2, characterized in that: The molar ratio of the uranyl nitrate hexahydrate solid to the thorium nitrate hexahydrate solid in the mixed actinide salt is any ratio, or the molar ratio of the uranyl nitrate hexahydrate solid to the plutonium nitrate pentahydrate solid in the mixed actinide salt is any ratio.

5. The method for preparing reactor MOX fuel powder according to claim 1, characterized in that: In step S1, during the mixing of the mixed actinide salt and the urea solid, the mixture is mixed by stirring and / or grinding the mixture.

6. The method for preparing reactor MOX fuel powder according to claim 5, characterized in that: In the process of mixing the mixed actinide salt and urea solid in step S1, the mixed actinide salt and urea mixture is heated to obtain a completely clarified mixed actinide eutectic.

7. The method for preparing reactor MOX fuel powder according to claim 1, characterized in that: Step S2 includes the following specific steps: sucking the mixed actinide eutectic into a crucible by a pipette, and heating the crucible to 150-160° C. according to a specified program and keeping the temperature for more than 30 minutes to obtain the deaminated powder.

8. The method for preparing reactor MOX fuel powder according to claim 1, characterized in that: In step S2, the deamination process is carried out under air or argon atmosphere; The specified procedure refers to a specified heating rate, and the specified heating rate is 5-10°C / min.

9. The method for preparing reactor MOX fuel powder according to claim 2, characterized in that: When the mixed actinide salt is a hexahydrated uranyl nitrate solid and a hexahydrated thorium nitrate solid, the denitrification powder is a U3O8 and ThO2 powder; when the mixed actinide salt is a hexahydrated uranyl nitrate solid and a pentahydrated plutonium nitrate solid, the denitrification powder is a U3O8 and PuO2 powder.

10. The method for preparing reactor MOX fuel powder according to claim 1, characterized in that: In step S3, the deaminated powder is heated to 500-800° C. according to a set program and kept at this temperature for more than 30 minutes to obtain a denitrified powder.

11. The method for preparing reactor MOX fuel powder according to claim 1, characterized in that: In step S3, the denitrification process is carried out under air or argon atmosphere; The setting procedure refers to the setting heating rate, and the setting heating rate is 5-10°C / min.

12. The method for preparing reactor MOX fuel powder according to claim 1, characterized in that: In step S4, the denitrified powder is heated to 680-900° C. at a heating rate of 5-10° C. / min under an argon atmosphere, and then switched to a hydrogen-argon mixed gas or hydrogen atmosphere and kept warm for 10-30 minutes to obtain MOX fuel powder.

13. The method for preparing reactor MOX fuel powder according to claim 2, characterized in that: When the mixed actinide salt is solid uranyl nitrate hexahydrate and solid thorium nitrate hexahydrate, the MOX fuel powder is (U x Th 1-x )O2; when the mixed actinide salt is solid uranyl nitrate hexahydrate and solid plutonium nitrate pentahydrate, the MOX fuel powder is (U x Pu 1-x )O2; Among them, 0.0<X<1.0.

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