阅读说明：本技术 高熵陶瓷惰性基弥散燃料芯块及其制备方法 (High-entropy ceramic inert matrix dispersion fuel pellet and preparation method thereof ) 是由 薛佳祥 吴利翔 张显生 任啟森 廖业宏 张永栋 于 2021-07-22 设计创作，主要内容包括：本发明公开了一种高熵陶瓷惰性基弥散燃料芯块及其制备方法,制备方法包括：S1、将原料粉体分别制成浆料和混合粉体；S2、将浆料喷涂在滚动的燃料颗粒表面,烘干后形成粘附在燃料颗粒表面的包覆层；S3、制备核心素坯和核壳素坯；S4、将核心素坯装入核壳素坯内,热处理,得到陶瓷坯体；S5、固熔烧结,形成致密化的高熵陶瓷惰性基弥散燃料芯块。本发明通过原位反应-固熔烧结两步法制备获得高熵陶瓷惰性基弥散燃料芯块,实现燃料芯块的热导率高、肿胀低、易后处理和适合工业化生产等特点；提高核反应堆包壳破损情况下的核燃料包容性,阻止核燃料的泄漏,提高核电安全性；改善核燃料的耐高温性能,推动核燃料在高温堆的应用。(The invention discloses a high-entropy ceramic inert matrix dispersion fuel pellet and a preparation method thereof, wherein the preparation method comprises the following steps: s1, preparing the raw material powder into slurry and mixed powder respectively; s2, spraying the slurry on the surface of rolling fuel particles, and drying to form a coating layer adhered to the surface of the fuel particles; s3, preparing a core biscuit and a core-shell biscuit; s4, filling the core biscuit into the core-shell biscuit, and carrying out heat treatment to obtain a ceramic blank; and S5, solid melting and sintering to form the densified high-entropy ceramic inert matrix dispersed fuel pellet. The high-entropy ceramic inert matrix dispersion fuel pellet is prepared and obtained through an in-situ reaction-solid fusion sintering two-step method, and the characteristics of high thermal conductivity, low swelling, easiness in post-treatment, suitability for industrial production and the like of the fuel pellet are realized; the nuclear fuel containment under the condition of the nuclear reactor cladding damage is improved, the leakage of the nuclear fuel is prevented, and the nuclear power safety is improved; improve the high temperature resistance of the nuclear fuel and promote the application of the nuclear fuel in a high temperature reactor.)

1. A preparation method of a high-entropy ceramic inert matrix dispersion fuel pellet is characterized by comprising the following steps:

s1, preparing the raw material powder into slurry and mixed powder respectively;

the raw material powder comprises five or more than five metal powder, metal oxide powder or metal hydride powder;

s2, spraying the slurry on the surface of rolling fuel particles, and drying to form a coating layer adhered to the surface of the fuel particles;

s3, mixing a part of the mixed powder with fuel particles with coating layers in proportion, and pressing to form a columnar core biscuit; pressing the other part of the mixed powder to form a cylindrical core-shell biscuit;

s4, loading the core biscuit into the core-shell biscuit, and carrying out heat treatment under a first set atmosphere to carry out in-situ reaction on the core biscuit and the raw material powder in the core-shell biscuit to obtain a ceramic blank;

and S5, carrying out solid-melt sintering on the ceramic blank under a second set atmosphere to form a densified high-entropy ceramic inert matrix dispersed fuel pellet.

2. A method of producing high entropy ceramic inert matrix dispersed fuel pellets according to claim 1, wherein the metal in the metal powder, metal oxide powder and metal hydride powder includes at least five of Zr, Ti, Nb, Ta, V, Cr, Mo and W; the particle size of the raw material powder is 10 nm-200 mu m.

3. A method for producing high-entropy ceramic inert-based dispersed fuel pellets according to claim 1, wherein step S1 includes:

s1.1, mixing raw material powder with a dispersant and an organic solvent to form slurry;

s1.2, drying part of the mixed slurry to form mixed powder; alternatively, the raw material powder is mixed with a dispersant to form a mixed powder.

4. A method for producing high-entropy ceramic inert-based dispersed fuel pellets according to claim 3, wherein the mass ratio of the organic solvent to the raw material powder in the slurry is 1: 1-3: 1; the dispersant accounts for 0.5 to 4 percent of the mass of the raw material powder.

5. A method of producing high entropy ceramic inert matrix dispersed fuel pellets according to claim 3, wherein the dispersant is at least one of polyethyleneimine, tetramethylammonium hydroxide; the organic solvent is at least one of absolute ethyl alcohol and acetone.

6. A method for producing high entropy ceramic inert matrix dispersed fuel pellets as claimed in claim 1, wherein in step S2, the fuel particles include TRISO particles, UO₂、UC、UC₂、UN、UCN、UCO、U₃Si₂U alloy, PuO₂At least one of PuC, PuN and Pu alloy;

the core of the TRISO particles comprises UO₂、UC、UC₂、UN、UCN、UCO、U₃Si₂And at least one of U alloy.

7. A method of producing high entropy ceramic inert matrix dispersed fuel pellets according to claim 1, wherein in step S2, the fuel particles are heated to 50 ℃ to 100 ℃ while rolling; and spraying the slurry on the surface of the fuel particles by using an air pressure spraying device.

8. A method of producing high entropy ceramic inert matrix dispersed fuel pellets according to claim 1, wherein in step S3, the core biscuit is shaped under a pressure of 10MPa to 100 MPa; the core-shell biscuit is molded under the pressure of 30 MPa-400 MPa.

9. A method for producing high-entropy ceramic inert-based dispersed fuel pellets according to claim 1, wherein in step S4, the temperature of the heat treatment is 800 ℃ to 1200 ℃;

in step S5, the temperature of solid-solution sintering is 1300-1550 ℃.

10. A method for producing high-entropy ceramic inert matrix dispersed fuel pellets according to any one of claims 1 to 9, wherein when the raw material powder is a mixed powder of five or more metal powders, five or more metal oxide powders, or five or more metal hydride powders, in step S4, the first set atmosphere is nitrogen;

under the nitrogen atmosphere, each metal powder, metal oxide or metal hydride respectively carries out in-situ reaction with nitrogen to generate nitride ceramics;

in step S5, the second set atmosphere is vacuum, argon, helium, or nitrogen.

11. A method of producing high entropy ceramic inert matrix dispersed fuel pellets according to claim 10, wherein the molar ratio between each of the raw material powders is 1: 1.

12. A method for producing high-entropy ceramic inert-based dispersed fuel pellets according to any one of claims 1 to 9, wherein in step S1, the raw material powder further includes C powder or Si powder;

in step S4, the first set atmosphere is vacuum, argon, helium, or nitrogen;

under a first set atmosphere, carrying out in-situ reaction on each metal powder, metal oxide or metal hydride and C or Si respectively to generate carbide, nitride, carbonitride or silicide ceramic;

in step S5, the second set atmosphere is vacuum, argon, helium, or nitrogen.

13. A method for preparing high-entropy ceramic inert matrix dispersed fuel pellets according to claim 12, wherein in the raw material powder, the molar ratio of each metal powder is 1:1, the molar ratio of each metal oxide powder is 1:1, and the molar ratio of each metal hydride powder is 1: 1;

the molar ratio of the C powder to each metal powder or each metal hydride powder is 1:1, and the molar ratio of the C powder to each metal oxide powder is 3: 1;

the molar ratio of the Si powder to each metal powder, each metal oxide powder or each metal hydride powder is 1: 1.

14. A high-entropy ceramic inert matrix dispersed fuel pellet, characterized in that it is obtained by the method of any one of claims 1 to 13.

Technical Field

The invention relates to the technical field of nuclear fuels, in particular to a high-entropy ceramic inert matrix dispersion fuel pellet and a preparation method thereof.

Background

With the development of industry, the demand for energy is increasing, and nuclear energy is favored by various industries as clean energy. With the rapid increase of nuclear energy utilization rate, the safety problem caused by the rapid increase of nuclear energy utilization rate cannot be ignored. The reactor core fuel is not melted or leaked under the extreme accident environment, and the important guarantee of the safety of the nuclear reactor is provided. Cladding is currently used primarily to ensure that nuclear fuel does not leak, but the cladding still has the potential to break. The fully ceramic coated Fuel (FCM) proposed in the united states has greatly improved safety by using an inert matrix of SiC. However, the heat conductivity of the SiC inert matrix is lower than 10W/m.K after irradiation, so that the central temperature of the fuel is extremely easy to rise, and meanwhile, the SiC inert matrix of the FCM is corroded by fission products Pd, Ag, Cs and the like, so that the safe allowable temperature is below 1600 ℃.

Zirconium carbide (ZrC) as an ultrahigh-temperature ceramic has excellent high-temperature stability (the melting point is 3530 ℃ and high-temperature phase change does not occur), and has a great prospect as an inert matrix of novel reactor dispersion fuel due to small neutron absorption cross section, resistance to corrosion of nuclear fission products, high thermal conductivity after irradiation and resistance to corrosion of lead, bismuth and molten salt. However, the sintering temperature of ZrC is as high as about 2200 ℃, and the high-temperature sintering is easy to cause serious coarsening of the microstructure of the material. In addition, a sintering aid is usually required to be added in the ZrC sintering process, and the use of the sintering aid not only reduces the high-temperature performance of the ZrC, but also reduces the comprehensive performances of corrosion resistance, irradiation resistance and the like of the ZrC.

Disclosure of Invention

The invention aims to solve the technical problem of providing a high-entropy ceramic inert matrix dispersion fuel pellet with low sintering temperature, high thermal conductivity and low swelling rate and a preparation method thereof.

The technical scheme adopted by the invention for solving the technical problems is as follows: providing a high-entropy ceramic inert matrix dispersed fuel pellet, comprising the following steps:

s1, preparing the raw material powder into slurry and mixed powder respectively;

the raw material powder comprises five or more than five metal powder, metal oxide powder or metal hydride powder;

s2, spraying the slurry on the surface of rolling fuel particles, and drying to form a coating layer adhered to the surface of the fuel particles;

s3, mixing a part of the mixed powder with fuel particles with coating layers in proportion, and pressing to form a columnar core biscuit; pressing the other part of the mixed powder to form a cylindrical core-shell biscuit;

s4, loading the core biscuit into the core-shell biscuit, and carrying out heat treatment under a first set atmosphere to carry out in-situ reaction on the core biscuit and the raw material powder in the core-shell biscuit to obtain a ceramic blank;

and S5, carrying out solid-melt sintering on the ceramic blank under a second set atmosphere to form a densified high-entropy ceramic inert matrix dispersed fuel pellet.

Preferably, the metal in the metal powder, the metal oxide powder and the metal hydride powder includes at least five of Zr, Ti, Nb, Ta, V, Cr, Mo and W; the particle size of the raw material powder is 10 nm-200 mu m.

Preferably, step S1 includes:

s1.1, mixing raw material powder with a dispersant and an organic solvent to form slurry;

s1.2, drying part of the mixed slurry to form mixed powder; alternatively, the raw material powder is mixed with a dispersant to form a mixed powder.

Preferably, in the slurry, the mass ratio of the organic solvent to the raw material powder is 1: 1-3: 1; the dispersant accounts for 0.5 to 4 percent of the mass of the raw material powder.

Preferably, the dispersant is at least one of polyethyleneimine and tetramethylammonium hydroxide; the organic solvent is at least one of absolute ethyl alcohol and acetone.

Preferably, in step S2, the fuel particles include TRISO particles, UO₂、UC、UC₂、UN、UCN、UCO、U₃Si₂U alloy, PuO₂At least one of PuC, PuN and Pu alloy;

the core of the TRISO particles comprises UO₂、UC、UC₂、UN、UCN、UCO、U₃Si₂And at least one of U alloy.

Preferably, in step S2, the fuel pellets are heated to 50 to 100 ℃ while rolling; and spraying the slurry on the surface of the fuel particles by using an air pressure spraying device.

Preferably, in step S3, the core biscuit is molded under a pressure of 10MPa to 100 MPa; the core-shell biscuit is molded under the pressure of 30 MPa-400 MPa.

Preferably, in step S4, the temperature of the heat treatment is 800 ℃ to 1200 ℃;

in step S5, the temperature of solid-solution sintering is 1300-1550 ℃.

Preferably, when the raw material powder is a mixed powder of five or more metal powders, five or more metal oxide powders, or five or more metal hydride powders, in step S4, the first set atmosphere is nitrogen;

under the nitrogen atmosphere, each metal powder, metal oxide or metal hydride respectively carries out in-situ reaction with nitrogen to generate nitride ceramics;

in step S5, the second set atmosphere is vacuum, argon, helium, or nitrogen.

Preferably, the molar ratio between the raw material powders is 1: 1.

Preferably, in step S1, the raw material powder further includes C powder or Si powder;

in step S4, the first set atmosphere is vacuum, argon, helium, or nitrogen;

under a first set atmosphere, carrying out in-situ reaction on each metal powder, metal oxide or metal hydride and C or Si respectively to generate carbide, nitride, carbonitride or silicide ceramic;

in step S5, the second set atmosphere is vacuum, argon, helium, or nitrogen.

Preferably, in the raw material powder, the molar ratio of the metal powder to the metal oxide powder is 1:1, the molar ratio of the metal oxide powder to the metal oxide powder is 1:1, and the molar ratio of the metal hydride powder to the metal hydride powder is 1: 1;

the molar ratio of the C powder to each metal powder or each metal hydride powder is 1:1, and the molar ratio of the C powder to each metal oxide powder is 3: 1;

the molar ratio of the Si powder to each metal powder, each metal oxide powder or each metal hydride powder is 1: 1.

The invention also provides a high-entropy ceramic inert matrix dispersion fuel pellet which is prepared by adopting any one of the preparation methods.

The invention has the beneficial effects that: the high-entropy ceramic inert base dispersion fuel pellet is prepared and obtained through an in-situ reaction-solid fusion sintering two-step method, the high-entropy ceramic inert base is used as a matrix of the fuel pellet, and compared with a SiC inert base fuel pellet, the high-entropy ceramic inert base dispersion fuel pellet has higher high temperature resistance, corrosion resistance and irradiation resistance, and has the characteristics of high thermal conductivity, low swelling, easiness in post-treatment, suitability for industrial production and the like; the nuclear fuel containment under the condition of the nuclear reactor cladding damage is improved, the leakage of the nuclear fuel is prevented, and the nuclear power safety is improved; improve the high temperature resistance of the nuclear fuel and promote the application of the nuclear fuel in a high temperature reactor.

The high-entropy ceramic inert matrix dispersion fuel pellet is suitable for fuel pellets in nuclear reactors such as light water reactors, gas cooling reactors (high-temperature gas reactors or ultrahigh-temperature gas reactors), molten metal cooling reactors or fast neutron breeder reactors.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic cross-sectional structure of a high entropy ceramic inert matrix dispersed fuel pellet of the present invention.

Detailed Description

The preparation method of the high-entropy ceramic inert matrix dispersion fuel pellet can comprise the following steps:

and S1, preparing the raw material powder into slurry and mixed powder respectively.

The step S1 may further include:

s1.1, mixing the raw material powder with a dispersant and an organic solvent to form slurry.

Specifically, the raw material powder, the dispersant and the organic solvent are ball-milled and mixed on a roller ball mill for 1 to 10 hours at a rotating speed of 50 to 200r/min, the adopted grinding ball is silicon nitride, and the ball-to-material ratio (the mass ratio of the grinding ball to the mixed material) is 1: 1-4: 1.

in the slurry, the mass ratio of the organic solvent to the raw material powder is 1: 1-3: 1.

the dispersant is at least one of polyethyleneimine and tetramethylammonium hydroxide. The organic solvent is at least one of absolute ethyl alcohol and acetone.

S1.2, drying part of the mixed slurry to form mixed powder; alternatively, the raw material powder is mixed with a dispersant to form a mixed powder.

In the slurry and the mixed powder, the dispersant accounts for 0.5 to 4 percent of the mass of the raw material powder.

Wherein, the raw material powder comprises five or more than five metal powder, metal oxide powder or metal hydride powder; alternatively, the raw material powder includes C powder (carbon powder) or Si powder (silicon powder), and five or more kinds of metal powder, metal oxide powder, or metal hydride powder. The particle size of the raw material powder is 10 nm-200 μm.

In the raw material powder, the metal in the metal powder, the metal oxide powder and the metal hydride powder comprises at least five of Zr, Ti, Nb, Ta, V, Cr, Mo and W. Therefore, when the raw material powder comprises at least five metal powders, namely at least five of Zr powder, Ti powder, Nb powder, Ta powder, V powder, Cr powder, Mo powder and W powder, the molar ratio of the metal powders is 1: 1; when the raw material powder comprises at least five metal oxide powders, namely oxides corresponding to at least five metals, wherein the molar ratio of the metal oxide powders is 1: 1; when the raw material powder comprises at least five metal hydride powders, namely hydrides corresponding to at least five metals, the molar ratio of the metal hydride powders is 1: 1.

When the raw material powder further includes C powder, the molar ratio between the C powder and each metal powder or each metal hydride powder is 1:1, and the molar ratio between the C powder and each metal oxide powder is 3: 1.

When the raw material powder further includes Si powder, the molar ratio of the Si powder to each metal powder, each metal oxide powder, or each metal hydride powder is 1: 1.

And S2, spraying the slurry on the surface of the rolling fuel particles by using an air pressure spraying device, and drying to form a coating layer adhered to the surface of the fuel particles.

Heating the fuel particles to 50-100 ℃ while rolling; due to the heating action, the organic solvent in the slurry is volatilized and removed.

Wherein the fuel particles may include TRISO particles, UO₂、UC、UC₂、UN、UCN、UCO、U₃Si₂U alloy, PuO₂At least one of PuC, PuN and Pu alloy. The core of the TRISO particles comprises UO₂、UC、UC₂、UN、UCN、UCO、U₃Si₂And at least one of U alloy.

S3, mixing a part of mixed powder with fuel particles with coating layers in proportion, and pressing to form a columnar core biscuit; and pressing the other part of the mixed powder to form a cylindrical core-shell biscuit.

The core biscuit is molded under the pressure of 10 MPa-100 MPa. The core biscuit may have a diameter of 6-8 mm and a height of 8-24 mm.

The core-shell biscuit is molded under the pressure of 30MPa to 400 MPa. The inner diameter of the core-shell biscuit can be 6.2 mm-8.2 mm, the outer diameter can be 8.5 mm-10 mm, and the height can be 8 mm-24 mm.

S4, the core biscuit is placed into the core-shell biscuit, and heat treatment is carried out under a first set atmosphere, so that the core biscuit and the raw material powder in the core-shell biscuit carry out in-situ reaction, and the ceramic blank is obtained.

The temperature of the heat treatment is 800 ℃ to 1200 ℃, preferably 1000 ℃ to 1200 ℃. After the heat treatment temperature reaches the required temperature, the temperature is kept for 0.5h-10h, preferably 0.5h-2 h.

And S5, carrying out solid-melt sintering on the ceramic blank under a second set atmosphere to form the densified high-entropy ceramic inert matrix dispersed fuel pellet.

The solid-melt sintering may be carried out pressureless. The temperature of solid-melt sintering is 1300-1550 ℃, preferably 1400-1550 ℃. After the temperature of the solid-melt sintering reaches the required temperature, preserving the heat for 0.5h-10h, preferably 0.5h-2 h.

Alternatively, when the raw material powder is a mixed powder of five or more kinds of metal powder, five or more kinds of metal oxide powder, or five or more kinds of metal hydride powder, the first set atmosphere is nitrogen in step S4. Under the nitrogen atmosphere, each metal powder, metal oxide or metal hydride respectively and nitrogen undergo in-situ reaction to generate nitride ceramics.

Metal powder (M) and nitrogen (N)₂) The in-situ reaction to form nitride is carried out according to the following formula:

2M+xN₂＝2MN_X

metal hydride powder (MH)_X) With nitrogen (N)₂) The in-situ reaction to form nitride is carried out according to the following formula:

3MH_X+(x/2+3y/2)N₂＝3MN_y+xNH₃

in each of the above reaction formulae, x is 1 to 4, usually 1 or 2; y is 1 to 2, typically 1.

In the solid-solution sintering in step S5, the second set atmosphere is vacuum, argon, helium, or nitrogen, and the nitride ceramics are solid-solution-integrated in the second set atmosphere.

When the raw material powder includes five or more metal powders, metal oxide powders, or metal hydride powders, and further includes C powder or Si powder, in step S4, the first set atmosphere is vacuum, argon, helium, or nitrogen. Under a first set atmosphere, each metal powder, metal oxide or metal hydride respectively reacts with C or Si in situ to generate carbide, nitride, carbonitride or silicide ceramics.

The reaction formula of the metal powder (M) and C for in-situ reaction to generate carbide is as follows:

M+xC＝MC_X

metal oxide powder (MO)_X) The reaction formula for generating carbide by in-situ reaction with C is as follows:

MO_X+(x+y)C＝MC_y+xCO

metal hydride powder (MH)_X) The reaction formula for generating carbide by in-situ reaction with C is as follows:

2MH_X+2yC＝2MC_y+xH₂

metal hydride powder (MH)_X) The reaction formula for in situ reaction with C to form carbonitride is as follows:

MO_X+(x+y/2)C+(x/2+y/4)N₂＝M(C_0.5N_0.5)_y+xCO

the reaction formula of the metal powder (M) and Si for in-situ reaction to generate silicide is as follows:

2M+xSi＝2MSi_X

metal hydride powder (MH)_X) The reaction formula for generating silicide by in-situ reaction with Si is as follows:

2MH_X+2ySi＝2MSi_y+xH₂

in each of the above reaction formulae, x is 1 to 4, usually 1 or 2; y is 1 to 2, typically 1.

After the in-situ reaction, in the solid-solution sintering of step S5, the second set atmosphere is vacuum, argon, helium or nitrogen.

In the preparation method, the in-situ reaction in the raw material powder reduces the impurity content of the high-entropy powder, improves the purity of the high-entropy ceramic inert matrix and reduces the preparation cost.

The density of the prepared densified high-entropy ceramic inert matrix dispersion fuel pellet is higher than 95%, and the content of impurity oxygen is lower than 0.1 wt%.

Referring to fig. 1, the high-entropy ceramic inert matrix dispersed fuel pellet prepared by the preparation method of the invention comprises a columnar fuel area 10 and a cylindrical fuel-free area 20. The fuel region 10 is disposed in the fuel-free region 20 and is closely coupled thereto. Wherein the fuel region 10 is formed from a core biscuit and the fuel-free region 20 is formed from a core-shell biscuit. The fuel zone 10 comprises a high entropy ceramic inert matrix 11 and fuel particles 12 dispersed in the high entropy ceramic inert matrix 11. The high-entropy ceramic inert matrix 11 and the fuel-free area 20 are formed by in-situ reaction and solid-melt sintering of raw material powder.

Compared with a SiC inert base, the high-entropy ceramic inert base 11 has higher high-temperature resistance, corrosion resistance and irradiation resistance, can improve the high-temperature stability of nuclear fuel and the thermal conductivity after irradiation, reduces the risk of reactor core melting, and improves the safety. With the increase of irradiation dose and temperature, the swelling rate of the high-entropy ceramic inert matrix 11 of the fuel can be kept below 0.3%. In the post-treatment of the spent fuel, a strong acid or a fluorine salt can be adopted for wet or dry separation.

The invention is further illustrated by the following specific examples.

Example 1

With ZrO₂、TiO₂、NbO₂、TaO₂、MoO₂And C is raw material powder, the purity of the powder is 99.9%, the particle size is 20nm, the molar ratio of the metal oxide powder is 1:1, the molar ratio of each metal oxide powder to C is 1: 3; the polyethylene imine is used as a dispersant, the content of the polyethylene imine accounts for 2 wt% of the raw material powder, the absolute ethyl alcohol is used as an organic solvent, and the mass of the organic solvent and the comprehensive proportion of the raw material powder and the dispersant are 2: 1. mixing the materials in a roller ball mill according to the proportion, wherein the grinding ball is silicon nitride, the revolution is 100r/min, the ball milling time is 12h, preparing slurry after ball milling, and preparing mixed powder by performing rotary evaporation and drying on part of the slurry.

By loading UO₂The method comprises the following steps of taking TRISO particles of uranium fuel as fuel particles, sequentially forming a loose pyrolytic carbon layer, an inner compact pyrolytic carbon layer, a silicon carbide layer and an outer compact pyrolytic carbon layer from inside to outside, heating the TRISO particles to 90 ℃ in a rolling state, coating the slurry on the TRISO particles through spray deposition, removing an organic solvent from the coated TRISO particles at 90 ℃ to obtain coated TRISO particles, and then performing dry pressing on the coated TRISO particles and the prepared mixed powder according to the proportion content of 40 wt%, wherein the mechanical pressing pressure is 100MPa, and cylindrical core biscuit with the diameter of 8mm and the height of 8mm is obtained through pressing.

And then pressing the mixed powder without fuel particles into a core-shell biscuit with the inner diameter of 8.2mm, the outer diameter of 10mm and the height of 8mm under the pressure of 80MPa, loading the core biscuit into the core-shell biscuit, heating to 1000 ℃ at the speed of 20 ℃/min in a pressureless furnace, keeping the temperature for 2 hours, heating to 1500 ℃, keeping the temperature for 1 hour, and keeping the sintering atmosphere at argon. Through the operation, the high-entropy ceramic inert matrix dispersion fuel pellet ((Zr)_0.2Ti_0.2Nb_0.2Ta_0.2Mo_0.2) C) high entropy ceramic inert matrix densificationThe degree reaches 96 percent.

Obtained (Zr)_0.2Ti_0.2Nb_0.2Ta_0.2Mo_0.2) In the C high-entropy ceramic inert base dispersed fuel pellet, TRISO particles are dispersed and distributed in the inert base nuclear fuel core, and the fuel-free area at the edge can further prevent the nuclear fuel from leaking due to the damage of the TRISO particles.

The fuel pellets are loaded into the cladding tube to complete the assembly, and the cladding after the assembly and the sealing can be used for stacking types such as light water reactor, high-temperature gas cooled reactor, molten rock reactor and the like.

Example 2

Taking Zr, Cr, Nb, Ta, Mo and C as raw material powder, wherein the purity of the powder is 99.99%, and the particle size is 100 nm; the molar ratio of the metal powder is 1:1, the molar ratio of each metal powder to C is 1: 1. core shell and core biscuits were prepared separately according to the method of example 1, the core biscuit was shaped under 50MPa pressure, the dimensions were 7mm diameter and 10mm height; the core-shell biscuit is pressed and molded under the pressure of 200MPa, and the inner diameter is 7.2mm, the outer diameter is 9mm and the height is 10 mm. Loading the core biscuit into a core-shell biscuit, sintering in a pressureless furnace, heating to 1200 ℃ at a heating rate of 15 ℃/min, preserving heat for 1.5h, then heating to 1550 ℃ again, preserving heat for 2h, and obtaining the high-entropy ceramic inert-based dispersion fuel pellet ((Zr) by using vacuum sintering atmosphere_0.2Cr_0.2Nb_0.2Ta_0.2Mo_0.2) C) the density of the high-entropy ceramic inert matrix is 98%.

Example 3

With ZrO₂、CrO₂、NbO₂、VO₂、TaO₂、MoO₂And C is raw material powder, the purity of the powder is 99.99 percent, and the particle size is 100 nm; the molar ratio of the metal oxide powders is 1:1, the molar ratio of each metal oxide powder to C is 1: 3.

core shell and core biscuits were prepared separately according to the method of example 1, the core biscuit was shaped under 100MPa pressure, the dimensions were 8mm diameter, 20mm height; the core-shell biscuit is pressed and molded under the pressure of 400MPa, and the inner diameter is 8.2mm, the outer diameter is 10mm, and the height is 20 mm. Mixing the above core biscuitLoading into core-shell biscuit, sintering in pressureless furnace, heating to 1100 deg.C at a rate of 5 deg.C/min, holding for 2 hr, heating to 1450 deg.C, holding for 4 hr in nitrogen atmosphere to obtain high-entropy ceramic inert-based dispersion fuel pellet ((Zr)_0.16Cr_0.16Nb_0.16Ta_0.16Mo_0.16)C_0.5N_0.5) The density of the high-entropy ceramic inert matrix is 97%.

Example 4

With ZrH₂、TiH₂、NbH₂、VH₂、TaH₂、MoH₂Si as raw material powder, wherein the purity of the powder is 99.99%, and the particle size is 50 nm; the molar ratio of the metal hydride powders is 1:1, the molar ratio of each metal hydride powder to Si is 1: 1.

core shell and core biscuits are prepared respectively according to the method of example 1, the core biscuit is formed under the pressure of 10MPa, and the size is 8mm in diameter and 24mm in height; the core-shell biscuit is pressed and molded under the pressure of 300MPa, and the inner diameter is 8.2mm, the outer diameter is 10mm, and the height is 24 mm. Loading the core biscuit into a core-shell biscuit, sintering in a pressureless furnace, heating to 900 ℃ at a heating rate of 10 ℃/min, preserving heat for 4h, heating to 1500 ℃ again, preserving heat for 1h, and obtaining the high-entropy ceramic inert-based dispersion fuel pellet ((Zr) with vacuum sintering atmosphere_0.2Ti_0.2Nb_0.2Ta_0.2Mo_0.2) Si) with a density of 98% in the high-entropy ceramic inert matrix.

Example 5

Taking Zr, Cr, Nb, Ta, V and Si as raw material powder, wherein the purity of the powder is 99.99%, and the particle size is 200 mu m; the molar ratio of the metal powder is 1:1, the molar ratio of each metal powder to Si is 1: 1.

core shell and core biscuits are prepared respectively according to the method of example 1, the core biscuit is formed under the pressure of 100MPa, and the size is 6mm in diameter and 8mm in height; the core-shell biscuit is pressed and molded under the pressure of 400MPa, and the inner diameter is 6.2mm, the outer diameter is 8mm and the height is 8 mm. Loading the core biscuit into core-shell biscuit, sintering in a pressureless furnace, heating to 1000 deg.C at a heating rate of 10 deg.C/min, and keeping the temperatureHeating to 1550 ℃ after 3h, preserving heat for 5h, and obtaining the high-entropy ceramic inert matrix dispersion fuel pellet ((Zr) by vacuum sintering atmosphere_0.2Cr_0.2Nb_0.2Ta_0.2V_0.2) Si) with a density of 96% in the high-entropy ceramic inert matrix.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.