CN115740463B - Method for producing fuel pellets - Google Patents
Method for producing fuel pellets Download PDFInfo
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- CN115740463B CN115740463B CN202211383644.4A CN202211383644A CN115740463B CN 115740463 B CN115740463 B CN 115740463B CN 202211383644 A CN202211383644 A CN 202211383644A CN 115740463 B CN115740463 B CN 115740463B
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- 239000000446 fuel Substances 0.000 title claims abstract description 89
- 239000008188 pellet Substances 0.000 title claims abstract description 77
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 239000000843 powder Substances 0.000 claims abstract description 203
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 72
- 238000000498 ball milling Methods 0.000 claims abstract description 69
- 229910052770 Uranium Inorganic materials 0.000 claims abstract description 56
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 53
- 239000011812 mixed powder Substances 0.000 claims abstract description 40
- 238000005245 sintering Methods 0.000 claims abstract description 37
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 claims abstract description 23
- 238000002156 mixing Methods 0.000 claims abstract description 19
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 claims abstract description 17
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 10
- 238000002360 preparation method Methods 0.000 claims abstract description 8
- 238000007731 hot pressing Methods 0.000 claims abstract description 7
- 238000000034 method Methods 0.000 claims description 40
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 21
- 239000002245 particle Substances 0.000 claims description 13
- 229910052739 hydrogen Inorganic materials 0.000 claims description 12
- 239000001257 hydrogen Substances 0.000 claims description 11
- 239000002105 nanoparticle Substances 0.000 claims description 11
- 150000002431 hydrogen Chemical class 0.000 claims description 4
- 229910003468 tantalcarbide Inorganic materials 0.000 description 44
- 239000012535 impurity Substances 0.000 description 15
- 230000008569 process Effects 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 10
- 229910052751 metal Inorganic materials 0.000 description 9
- 239000002184 metal Substances 0.000 description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 8
- 239000001301 oxygen Substances 0.000 description 8
- 230000006872 improvement Effects 0.000 description 6
- 238000004321 preservation Methods 0.000 description 6
- 239000002994 raw material Substances 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 229910002804 graphite Inorganic materials 0.000 description 3
- 239000010439 graphite Substances 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- CSJDCSCTVDEHRN-UHFFFAOYSA-N methane;molecular oxygen Chemical compound C.O=O CSJDCSCTVDEHRN-UHFFFAOYSA-N 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 2
- UNASZPQZIFZUSI-UHFFFAOYSA-N methylidyneniobium Chemical compound [Nb]#C UNASZPQZIFZUSI-UHFFFAOYSA-N 0.000 description 2
- NFFIWVVINABMKP-UHFFFAOYSA-N methylidynetantalum Chemical compound [Ta]#C NFFIWVVINABMKP-UHFFFAOYSA-N 0.000 description 2
- 239000010955 niobium Substances 0.000 description 2
- 239000003758 nuclear fuel Substances 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000009770 conventional sintering Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- QRKOGTOMYRGNOR-UHFFFAOYSA-N methane;uranium Chemical compound C.[U] QRKOGTOMYRGNOR-UHFFFAOYSA-N 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000009740 moulding (composite fabrication) Methods 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
Abstract
The application provides a preparation method of a fuel pellet, which comprises the following steps: mixing nanoscale TaC powder, nanoscale NbC powder, nanoscale UC powder, zinc stearate and uranium powder, and performing ball milling treatment to obtain UC-NbC-TaC-U mixed powder; performing hot-pressing sintering treatment on the UC-NbC-TaC-U mixed powder to obtain an initial fuel pellet; reacting the initial fuel pellets at a first temperature for a first period of time with flowing hydrogen gas in order to remove free carbon, to obtain (U, nb, ta) C quaternary fuel pellets, wherein the first temperature is greater than 1200 ℃.
Description
Technical Field
The application relates to the technical field of nuclear fuel, in particular to a preparation method of a fuel pellet.
Background
The quaternary (U, nb, ta) C fuel has the advantages of high specific impact and large thrust as a special carbide fuel, and the like, and can supply energy for a high-power nuclear propulsion reactor for deep space exploration and carrier transportation.
In the related art, the preparation method of the quaternary (U, nb, ta) C fuel comprises the following steps: to UO 2 Powder, nb 2 O 5 Powder, ta 2 O 5 Mixing with C powder, performing high-temperature reaction treatment to obtain quaternary (U, nb, ta) C raw material powder, and performing ball milling, pressing and sintering on the quaternary (U, nb, ta) C raw material powder to obtain the quaternary (U, nb, ta) C fuel pellet.
However, the quaternary (U, nb, ta) C fuel pellets prepared by the preparation method in the related art have problems of high free carbon and oxygen impurity contents and low pellet density.
Disclosure of Invention
In view of this, the present application proposes a method for preparing fuel pellets in order to reduce the content of free carbon and oxygen impurities in quaternary (U, nb, ta) C fuel pellets and to increase the density of the fuel pellets, so as to at least partially solve the above-mentioned technical problems.
In order to solve the technical problems, the application provides a preparation method of a fuel pellet, which comprises the following steps:
mixing nanoscale TaC powder, nanoscale NbC powder, nanoscale UC powder, zinc stearate and uranium powder, and performing ball milling treatment to obtain UC-NbC-TaC-U mixed powder;
performing hot-pressing sintering treatment on the UC-NbC-TaC-U mixed powder to obtain an initial fuel pellet;
reacting the initial fuel pellets at a first temperature for a first period of time with flowing hydrogen gas in order to remove free carbon, to obtain (U, nb, ta) C quaternary fuel pellets, wherein the first temperature is greater than 1200 ℃.
According to the embodiment of the application, the mass ratio of the nanoscale TaC powder to the nanoscale NbC powder to the nanoscale UC powder is 1 (3-5) (6-4); the addition amount of the zinc stearate is 0.3 to 0.5 percent of the total mass of the nanoscale TaC powder, the nanoscale NbC powder and the nanoscale UC powder; the addition amount of uranium powder is 1-3% of the total mass of nano-scale TaC powder, nano-scale NbC powder and nano-scale UC powder.
According to the embodiment of the application, the granularity range of the nanoscale UC powder is 500-900 nm; the granularity range of the nano NbC powder is 700-900 nm; the granularity range of the nano-scale TaC powder is 800-900 nm.
According to an embodiment of the present application, a method for preparing nanoscale UC powder includes:
u is set to 3 O 8 Mixing the powder and carbon powder, and performing ball milling to obtain U 3 O 8 And carbon, wherein U 3 O 8 The particle size range of the mixed powder of the carbon and the catalyst is 500-900 nm;
to U 3 O 8 And sintering the mixed powder with carbon to obtain the nanoscale UC powder.
According to an embodiment of the application, U 3 O 8 The mol ratio of the powder to the carbon powder is 1 (7-9).
According to an embodiment of the application, U 3 O 8 Mixing the powder and carbon powder, and performing ball milling to obtain U 3 O 8 And carbon, comprising: u is set to 3 O 8 Mixing the powder with carbon powder, and adopting BBall milling is carried out for 1-3 h by an alcohol wet method under the condition of ball milling rotating speed of 300-500 rpm, thus obtaining U 3 O 8 And carbon.
According to an embodiment of the application, for U 3 O 8 Sintering the mixed powder with carbon to obtain nanoscale UC powder, wherein the step of obtaining the nanoscale UC powder comprises the following steps: to U 3 O 8 And the mixed powder of carbon reacts for 2 to 4 hours at the temperature of 1500 to 1700 ℃ to obtain the nanoscale UC powder.
According to an embodiment of the present application, a method for preparing nano-sized NbC powder includes: performing ball milling treatment on NbC powder with the granularity of 10-20 mu m to obtain nano NbC powder.
According to an embodiment of the present application, a method for preparing nano-sized TaC powder includes: ball milling is carried out on TaC powder with the granularity of 20-40 mu m, thus obtaining nano-scale TaC powder.
According to an embodiment of the present application, after mixing nanoscale TaC powder, nanoscale NbC powder, nanoscale UC powder, zinc stearate and uranium powder, ball milling is performed to obtain UC-NbC-TaC-U mixed powder, where the conditions of the ball milling include: the ethanol wet method is adopted, the ball milling rotating speed is 400-600 rpm, and the ball milling time is 6-10 h.
According to an embodiment of the present application, in performing hot press sintering treatment on the UC-NbC-TaC-U mixed powder to obtain an initial fuel pellet, conditions of the hot press sintering treatment include: the pressure is 60-100 MPa, the temperature is 1550-1755 ℃, and the heat preservation time is 1-3 h.
According to an embodiment of the present application, reacting an initial fuel pellet at a first temperature for a first period of time to remove free carbon in the presence of flowing hydrogen to obtain a (U, nb, ta) C quaternary fuel pellet comprising: in vacuum degree of (1-3) x 10 - 3 Under Pa and flowing hydrogen, the initial fuel pellets are reacted for 1 to 3 hours at a first temperature of 1600 to 1755 ℃ to remove free carbon, and the (U, nb, ta) C quaternary fuel pellets are obtained.
According to an embodiment of the present application, a UC-NbC-TaC-U mixed powder is prepared by mixing nano-sized TaC powder, nbC powder, UC powder, zinc stearate and uranium powder, and then the mixed powder is hot pressed and sintered to obtain an initial fuel pellet, and then the initial fuel pellet is subjected to a decarbonizing treatment to obtain a quaternary (U, nb, ta) C pellet. The process can solve the problem that the carbon-thermal reaction can not reduce the C and O impurities, thereby reducing the content of the free C and O impurities in the quaternary (U, nb, ta) C fuel pellets and improving the density of the fuel pellets.
According to the embodiment of the application, the metal uranium powder is used as the sintering aid, so that the two beneficial effects on the sintering of the core block can be achieved: firstly, metal uranium powder can be melted into a liquid phase at the temperature of more than 1200 ℃, so that liquid phase sintering is formed, the improvement of the density of the core blocks can be promoted, meanwhile, the heat conductivity of the fuel can be improved by the metal uranium, and the improvement of the thermal performance of the fuel is positively influenced; secondly, the metal uranium can also increase the density of the (U, nb, ta) C fuel uranium, increase the burnup depth of the fuel, and play a double beneficial effect.
Drawings
FIG. 1 is a flow chart of the present application for preparing a fuel pellet.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely described below in connection with the embodiments of the present application. It will be apparent that the described embodiments are one embodiment, but not all embodiments, of the present application. All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present application fall within the protection scope of the present application.
It is to be noted that unless otherwise defined, technical or scientific terms used herein should be taken in a general sense as understood by one of ordinary skill in the art to which the present application belongs. If, throughout, reference is made to "first," "second," etc., the description of "first," "second," etc., is used merely for distinguishing between similar objects and not for understanding as indicating or implying a relative importance, order, or implicitly indicating the number of technical features indicated, it being understood that the data of "first," "second," etc., may be interchanged where appropriate. If "and/or" is present throughout, it is meant to include three side-by-side schemes, for example, "A and/or B" including the A scheme, or the B scheme, or the scheme where A and B are satisfied simultaneously.
The highest use temperature of nuclear propulsion reactor fuel is close to 3500K, the melting point of Uranium Carbide (UC) fuel is 2803K, the pure UC fuel can not meet the ultra-high temperature requirement of the nuclear propulsion reactor, and the UC fuel also faces the problem of thermochemical corrosion in a hot hydrogen environment. Therefore, there is a need for optimizing improvement of fuel performance by adding other elements (such as niobium Nb and tantalum Ta).
In the aspect of thermal performance, a second phase with high melting point and high heat conduction such as niobium carbide NbC, tantalum carbide TaC and the like is added, so that a net-shaped bridging structure can be formed, and the melting point and the heat conductivity of carbide fuel are improved; in the aspect of mechanical properties, second phases such as niobium carbide NbC, tantalum carbide TaC and the like are dispersed and precipitated at the grain boundary of the fuel, and the mechanical properties of the fuel are enhanced in the aspects of hardness and bending strength.
By doping and modifying the carbide (UC) fuel, the formed multi-carbide fuel is greatly improved in the aspects of thermal property and mechanical property. The quaternary (U, nb, ta) C fuel has the advantages of high specific impulse, high thrust and the like as a special carbide fuel, and can supply energy for a high-power nuclear propulsion reactor for deep space exploration and carrier transportation.
In the related art, the preparation method of the quaternary (U, nb, ta) C fuel pellets comprises the steps of 2 Powder, nb 2 O 5 Powder, ta 2 O 5 Mixing with C powder, performing high-temperature reaction treatment to obtain quaternary (U, nb, ta) C raw material powder, and performing ball milling, pressing and sintering on the quaternary (U, nb, ta) C raw material powder to obtain the quaternary (U, nb, ta) C fuel pellet. However, due to UO 2 Powder, nb 2 O 5 Powder, ta 2 O 5 The reaction temperature and reaction time are different from those of the C powder, so that the content of free carbon and oxygen impurities in the finally prepared (U, nb, ta) C quaternary fuel pellets is high (generally higher than 500 ppm), and the impurities reduce the thermal performance of the fuel; at the same time, the conventional sintering process is carried outThe density of the pellets is not high.
Fig. 1 schematically shows a flow chart of the present application for preparing a fuel pellet.
As shown in fig. 1, the present application proposes a method of manufacturing a fuel pellet, which includes operations S101 to S103.
In operation S101, mixing nanoscale TaC powder, nanoscale NbC powder, nanoscale UC powder, zinc stearate and uranium powder, and performing ball milling treatment to obtain UC-NbC-TaC-U mixed powder;
in operation S102, performing hot-pressing sintering treatment on UC-NbC-TaC-U mixed powder to obtain an initial fuel pellet;
in operation S103, the initial fuel pellets are reacted at a first temperature for a first period of time with flowing hydrogen gas in order to remove free carbon, resulting in (U, nb, ta) C quaternary fuel pellets, wherein the first temperature is greater than 1200 ℃.
According to the embodiment of the application, the nano-scale TaC powder, the nano-scale NbC powder and the nano-scale UC powder are respectively prepared and then mixed, so that oxygen impurities are effectively reduced, free carbon is removed by flowing hydrogen, carbon impurities are reduced, and the purity of the fuel pellets is improved.
According to the embodiment of the application, the metal uranium powder is used as the sintering aid, so that the increase of the pellet density can be promoted, the heat conductivity of the fuel can be improved, and the positive influence on the improvement of the thermal property of the fuel is achieved.
According to the embodiment of the application, the mass ratio of the nanoscale TaC powder to the nanoscale NbC powder to the nanoscale UC powder is 1 (3-5) (4-6); the addition amount of the zinc stearate is 0.3 to 0.5 percent of the total mass of the nanoscale TaC powder, the nanoscale NbC powder and the nanoscale UC powder; the addition amount of uranium powder is 1-3% of the total mass of nano-scale TaC powder, nano-scale NbC powder and nano-scale UC powder.
According to an embodiment of the application, the particle size range of the nanoscale UC powder is 500-900 nm.
According to an embodiment of the application, the particle size of the nanoscale UC powder may be selected from 500nm, 700nm, 900nm, etc.
According to an embodiment of the present application, the nanoscale NbC powder has a particle size in the range of 700 to 900nm.
According to an embodiment of the present application, the particle size of the nano-sized NbC powder may be selected to be 700nm, 800nm, 900nm, etc.
According to an embodiment of the application, the particle size of the nanoscale TaC powder ranges from 800 to 900nm.
According to an embodiment of the application, the particle size of the nanoscale TaC powder may be selected from 800nm, 850nm, 900nm, etc.
According to an embodiment of the application, the mass ratio of the nanoscale TaC powder, nanoscale NbC powder and nanoscale UC powder may be selected from 1:3:6, 1:4:5, 1:5:5, etc.
According to the embodiment of the application, the addition amount of zinc stearate can be selected from 0.3%, 0.4%, 0.5% and the like of the total mass of the nano-scale TaC powder, the nano-scale NbC powder and the nano-scale UC powder.
According to the embodiment of the application, the addition amount of uranium powder can be selected from 1%, 2%, 3% and the like of the total mass of nanoscale TaC powder, nanoscale NbC powder and nanoscale UC powder.
According to the embodiment of the application, the addition of the nanoscale TaC powder, the nanoscale NbC powder and the nanoscale UC powder can effectively reduce the content of oxygen impurities in the raw materials.
According to the embodiment of the application, the zinc stearate can increase the cohesiveness among different powders, and is beneficial to agglomeration, pressing and forming treatment among the powders.
According to the embodiment of the application, the metal uranium powder is used as a sintering aid, so that the improvement of the density and the thermal conductivity of the pellets can be promoted, and the improvement of the thermal performance of the fuel is positively influenced.
According to an embodiment of the present application, a method for preparing nanoscale UC powder includes: u is set to 3 O 8 Mixing the powder and carbon powder, and performing ball milling to obtain U 3 O 8 And carbon, for U 3 O 8 And sintering the mixed powder with carbon to obtain the nanoscale UC powder.
According to an embodiment of the application, U 3 O 8 And carbon in a particle size range of 500 to 900nm.
According to an embodiment of the application，U 3 O 8 The particle size of the mixed powder with carbon may be selected from 500nm, 700nm, 900nm, etc.
According to an embodiment of the application, U 3 O 8 The mol ratio of the powder to the carbon powder is 1 (7-9).
According to an embodiment of the application, U 3 O 8 The molar ratio of the powder to the carbon powder can be selected from 1:7, 1:8, 1:9, etc.
According to the embodiment of the application, the addition of excessive carbon powder can lead U to be 3 O 8 The O in the powder is completely removed by reaction, helping to reduce the O impurity of the fuel pellet.
According to an embodiment of the application, U 3 O 8 Mixing the powder and carbon powder, and performing ball milling to obtain U 3 O 8 And carbon, comprising: u is set to 3 O 8 Mixing the powder and carbon powder, ball milling the mixture for 1 to 3 hours by adopting an ethanol wet method under the condition of the ball milling rotating speed of 300 to 500rpm to obtain U 3 O 8 And carbon.
According to an embodiment of the application, U 3 O 8 When the powder and the carbon powder are mixed for ball milling treatment, the ball milling rotating speed can be selected to be 300nm, 400nm, 500nm and the like.
According to an embodiment of the application, U 3 O 8 When the powder and the carbon powder are mixed for ball milling treatment, the ball milling treatment time can be selected from 1h, 2h, 3h and the like.
According to an embodiment of the application, for U 3 O 8 Sintering the mixed powder with carbon to obtain nanoscale UC powder, wherein the step of obtaining the nanoscale UC powder comprises the following steps: to U 3 O 8 And the mixed powder of carbon reacts for 2 to 4 hours at the temperature of 1500 to 1700 ℃ to obtain the nanoscale UC powder.
According to an embodiment of the application, for U 3 O 8 The sintering temperature in the sintering treatment of the mixed powder with carbon may be 1500 ℃, 1600 ℃, 1700 ℃, or the like.
According to an embodiment of the application, for U 3 O 8 The sintering time when the mixed powder with carbon is subjected to the sintering treatment may be selected to be 2 hours, 3 hours, 4 hours, or the like.
According to an embodiment of the present application, a method for preparing nano-sized NbC powder includes: performing ball milling treatment on NbC powder with the granularity of 10-20 mu m to obtain nano NbC powder.
According to an embodiment of the present application, the particle size of the NbC powder may be selected from 10 μm, 15 μm, 20 μm, etc.
According to an embodiment of the present application, a method for preparing nano-sized TaC powder includes: ball milling is carried out on TaC powder with the granularity of 20-40 mu m, thus obtaining nano-scale TaC powder.
According to an embodiment of the application, the particle size of the TaC powder may be selected from 20 μm, 30 μm, 40 μm, etc.
According to an embodiment of the present application, after mixing nanoscale TaC powder, nanoscale NbC powder, nanoscale UC powder, zinc stearate and uranium powder, ball milling is performed to obtain UC-NbC-TaC-U mixed powder, where the conditions of the ball milling include: the ethanol wet method is adopted, the ball milling rotating speed is 400-600 rpm, and the ball milling time is 6-10 h.
According to an embodiment of the present application, when the ball milling process is performed after mixing the nano-sized TaC powder, the nano-sized NbC powder, the nano-sized UC powder, the zinc stearate and the uranium powder, the ball milling rotation speed may be selected to be 400rpm, 500rpm, 600rpm, etc.
According to the embodiment of the application, when the nano-scale TaC powder, the nano-scale NbC powder, the nano-scale UC powder, the zinc stearate and the uranium powder are mixed and then subjected to ball milling treatment, the ball milling time can be selected from 6 hours, 8 hours, 10 hours and the like.
According to the embodiment of the application, the nano-sized powder material has small particle size and higher reactivity, can effectively improve the reactivity and is beneficial to improving the density of the fuel pellets.
According to an embodiment of the present application, in performing hot press sintering treatment on the UC-NbC-TaC-U mixed powder to obtain an initial fuel pellet, conditions of the hot press sintering treatment include: the pressure is 60-100 MPa, the temperature is 1550-1755 ℃, and the heat preservation time is 1-3 h.
According to the embodiment of the application, when the UC-NbC-TaC-U mixed powder is subjected to hot press sintering treatment, the pressure is selected from 60MPa, 80MPa, 100MPa and the like.
According to an embodiment of the present application, when the UC-NbC-TaC-U mixed powder is subjected to the hot press sintering treatment, the temperature may be selected to 1550 ℃, 1650 ℃, 1750 ℃ and the like.
According to the embodiment of the application, when the UC-NbC-TaC-U mixed powder is subjected to hot-press sintering treatment, the heat preservation time can be selected from 1h, 2h, 3h and the like.
According to an embodiment of the present application, reacting an initial fuel pellet at a first temperature for a first period of time to remove free carbon in the presence of flowing hydrogen to obtain a (U, nb, ta) C quaternary fuel pellet comprising: in vacuum degree of (1-3) x 10 - 3 Under Pa and flowing hydrogen, the initial fuel pellets are reacted for 1 to 3 hours at a first temperature of 1600 to 1755 ℃ to remove free carbon, and the (U, nb, ta) C quaternary fuel pellets are obtained.
According to an embodiment of the present application, the vacuum level may be selected to be 1×10 -3 Pa、2×10 -3 Pa、3×10 -3 Pa, and the like.
According to an embodiment of the present application, the first temperature may be selected to be 1600 ℃, 1700 ℃, 1755 ℃, etc.
According to an embodiment of the present application, the first duration may be selected to be 1h, 2h, 3h, etc.
According to the embodiment of the application, the free carbon in the initial fuel pellets can be removed by introducing hydrogen at high temperature, wherein the mechanism of removing carbon by hydrogen is C and H 2 Reaction to generate CH 4 ，C+H 2 →CH 4 。
According to the embodiment of the application, the relative density of the pellets prepared by the preparation method of the (U, nb, ta) C quaternary fuel pellets can reach more than 92% TD, the content of C impurities is lower than 0.3wt%, the content of O impurities is lower than 0.1wt%, and the pellets have excellent thermophysical properties.
According to an embodiment of the application, the relative density is equal to the true density divided by the theoretical density.
The present application will be described in further detail with reference to specific embodiments in order to make the objects, technical solutions and advantages of the present application more apparent. It should be noted that the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments of the present application, other embodiments that may be obtained by those of ordinary skill in the art without making any inventive effort are within the scope of the present application.
Example 1
A method of making a fuel pellet comprising:
s1: u is measured according to the mol ratio of 1:7 3 O 8 Placing the powder and carbon powder into a ball mill for ball milling treatment to obtain nano U 3 O 8 And carbon. Nanoscale U 3 O 8 And placing the mixed powder of carbon and the powder into a vacuum sintering furnace, and carrying out heat preservation treatment for 2 hours at the temperature of 1500 ℃ to obtain the nanoscale UC powder.
And (3) taking NbC powder with the initial granularity of 10-20 mu m, and putting the NbC powder into a ball mill for ball milling treatment to obtain nano NbC powder with the granularity of 700-900 nm.
Taking TaC powder with the initial granularity of 20-40 mu m, and putting the TaC powder into a ball mill for ball milling treatment to obtain nano-scale TaC powder with the granularity of 800-900 nm.
S2: respectively measuring nanoscale TaC powder, nbC powder and UC powder according to the molar ratio of 1:3:6, respectively adding zinc stearate with the mass fraction of 0.3% and metal uranium powder with the mass fraction of 1%, and putting into a ball mill for ball milling treatment to obtain nanoscale UC-NbC-TaC-U mixed powder.
Wherein the ball milling process is an ethanol wet method, the ball milling rotating speed is preferably 300rpm, and the ball milling time is 1h.
S3: and (3) filling the nanoscale UC-NbC-TaC-U mixed powder prepared in the step (S2) into a graphite mold, and adopting a hot-pressing sintering process to perform heat preservation for 1 hour under the conditions of the pressure of 60MPa and the temperature of 1550 ℃ to prepare the initial fuel pellet.
Wherein the ball milling process is an ethanol wet method, the ball milling rotating speed is preferably 400rpm, and the ball milling time is 6 hours.
S4: placing the initial fuel pellets prepared in the step S3 into a high-temperature sintering furnace, and vacuumizing to a pressure of 1X 10 -3 After Pa, let in flowing H 2 The temperature of the gas is 1600 ℃ and the gas is kept at 1h, removing residual trace C to obtain the (U, nb, ta) C fuel pellets.
The (U, nb, ta) C fuel pellets prepared in the embodiment have the oxygen content of 50ppm, the carbon content of 85ppm and the density of 92.3%TD, and the relative density of the pellets prepared by the method provided by the application can reach more than 92%TD, and the carbon-oxygen impurity content is lower than 90ppm.
Example 2
A method of making a fuel pellet comprising:
s1: u is measured according to the mol ratio of 1:8 3 O 8 Placing the powder and carbon powder into a ball mill for ball milling treatment to obtain nano U 3 O 8 And carbon. Nanoscale U 3 O 8 And placing the mixed powder of carbon and the powder into a vacuum sintering furnace, and carrying out heat preservation treatment for 3 hours at the temperature of 1600 ℃ to obtain the nanoscale UC powder.
And (3) taking NbC powder with the initial granularity of 10-20 mu m, and putting the NbC powder into a ball mill for ball milling treatment to obtain nano NbC powder with the granularity of 700-900 nm.
Taking TaC powder with the initial granularity of 20-40 mu m, and putting the TaC powder into a ball mill for ball milling treatment to obtain nano-scale TaC powder with the granularity of 800-900 nm.
S2: respectively measuring nanoscale TaC powder, nbC powder and UC powder according to the mol ratio of 1:4:5, respectively adding zinc stearate with the mass fraction of 0.4% and metal uranium powder with the mass fraction of 2%, and putting into a ball mill for ball milling treatment to obtain nanoscale UC-NbC-TaC-U mixed powder.
Wherein the ball milling process is an ethanol wet method, the ball milling rotating speed is preferably 400rpm, and the ball milling time is 2 hours.
S3: and (3) filling the nanoscale UC-NbC-TaC-U mixed powder prepared in the step (S2) into a graphite mold, and adopting a hot-pressing sintering process to prepare the initial fuel pellet under the conditions of 80MPa of pressure and 1650 ℃ of temperature for 2 hours.
Wherein the ball milling process is an ethanol wet method, the ball milling rotating speed is preferably 500rpm, and the ball milling time is 8 hours.
S4: preparing the S3 stepThe initial fuel pellets of (2) are placed into a high temperature sintering furnace and vacuumized to a pressure of 2X 10 -3 After Pa, let in flowing H 2 And (3) preserving the temperature of the gas at 1700 ℃ for 2 hours, and removing residual trace C to obtain the (U, nb, ta) C fuel pellets.
The (U, nb, ta) C fuel pellets prepared in the embodiment have oxygen content of 48ppm, carbon content of 76ppm and density of 93.1%TD, and the relative density of the pellets prepared by the method provided by the application can reach more than 92%TD, and the carbon-oxygen impurity content is lower than 90ppm.
Example 3
A method of making a fuel pellet comprising:
s1: u is measured according to the mol ratio of 1:9 3 Placing O8 powder and carbon powder into a ball mill for ball milling treatment to obtain nano U 3 O 8 And carbon. And (3) placing the mixed powder into a vacuum sintering furnace, and preserving the heat for 4 hours at the temperature of 1700 ℃ to prepare the nanoscale UC powder.
And (3) taking NbC powder with the initial granularity of 10-20 mu m, and putting the NbC powder into a ball mill for ball milling treatment to obtain nano NbC powder with the granularity of 700-900 nm.
Taking TaC powder with the initial granularity of 20-40 mu m, and putting the TaC powder into a ball mill for ball milling treatment to obtain nano-scale TaC powder with the granularity of 800-900 nm.
S2: respectively measuring nanoscale TaC powder, nbC powder and UC powder according to the molar ratio of 1:5:5, respectively adding zinc stearate with the mass fraction of 0.5% and metal uranium powder with the mass fraction of 3%, and putting into a ball mill for ball milling treatment to obtain nanoscale UC-NbC-TaC-U mixed powder.
Wherein the ball milling process is an ethanol wet method, the ball milling rotating speed is preferably 500rpm, and the ball milling time is 3 hours.
S3: filling the nano UC-NbC-TaC-U mixed powder prepared in the step S2 into a graphite mold, adopting a hot-pressing sintering process, and preserving the temperature for 3 hours under the conditions of 100MPa of pressure and 1755 ℃ of temperature to prepare the initial fuel pellet.
Wherein the ball milling process is an ethanol wet method, the ball milling rotating speed is preferably 600rpm, and the ball milling time is 10 hours.
S4: placing the initial fuel pellets prepared in the step S3 into a high-temperature sintering furnace, and vacuumizing to a pressure of 3X 10 -3 After Pa, let in flowing H 2 And (3) preserving the temperature of the gas for 3 hours at the temperature of 1800 ℃ and removing residual trace C to obtain the (U, nb, ta) C fuel pellets.
The (U, nb, ta) C fuel pellets prepared in the embodiment have the oxygen content of 42ppm, the carbon content of 65ppm and the density of 93.5%TD, and the relative density of the pellets prepared by the method provided by the application can reach more than 92%TD, and the carbon-oxygen impurity content is lower than 90ppm.
The present application has been described in detail in the above embodiments, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application. The application may be practiced otherwise than as specifically described.
Claims (7)
1. A method of making a fuel pellet comprising:
mixing nanoscale TaC powder, nanoscale NbC powder, nanoscale UC powder, zinc stearate and uranium powder, and performing ball milling treatment to obtain UC-NbC-TaC-U mixed powder;
performing hot-pressing sintering treatment on the UC-NbC-TaC-U mixed powder to obtain an initial fuel pellet;
reacting the initial fuel pellets at a first temperature for a first period of time under the condition of flowing hydrogen to remove free carbon to obtain (U, nb, ta) C quaternary fuel pellets, wherein the first temperature is higher than 1200 ℃;
the mass ratio of the nanoscale TaC powder to the nanoscale NbC powder to the nanoscale UC powder is 1 (3-5) (4-6);
the addition amount of the zinc stearate is 0.3-0.5% of the total mass of the nanoscale TaC powder, the nanoscale NbC powder and the nanoscale UC powder;
the adding amount of the uranium powder is 1-3% of the total mass of the nanoscale TaC powder, the nanoscale NbC powder and the nanoscale UC powder;
the granularity range of the nanoscale UC powder is 500-900 nm;
the granularity range of the nano NbC powder is 700-900 nm;
the granularity range of the nano-scale TaC powder is 800-900 nm;
the preparation method of the nanoscale UC powder comprises the following steps:
u is set to 3 O 8 Mixing the powder and carbon powder, and performing ball milling to obtain U 3 O 8 And carbon, wherein the U 3 O 8 The particle size range of the mixed powder of the carbon and the carbon is 500-900 nm;
for the U 3 O 8 And sintering the mixed powder of the carbon to obtain the nanoscale UC powder.
2. The method of claim 1, wherein U 3 O 8 The molar ratio of the powder to the carbon powder is 1 (7-9).
3. The method according to claim 1, wherein said U is 3 O 8 Mixing the powder and carbon powder, and performing ball milling to obtain U 3 O 8 And carbon, comprising:
the U is set up 3 O 8 Mixing the powder with the carbon powder, and performing ball milling treatment for 1-3 hours by adopting an ethanol wet method under the condition of a ball milling rotating speed of 300-500 rpm to obtain the U 3 O 8 And carbon.
4. The method according to claim 1, wherein said pair of said U 3 O 8 Sintering the mixed powder of carbon to obtain the nanoscale UC powder, wherein the step of obtaining the nanoscale UC powder comprises the following steps:
for the U 3 O 8 And reacting the mixed powder with carbon for 2-4 hours at 1500-1700 ℃ to obtain the nanoscale UC powder.
5. The method of claim 1, wherein the method of preparing nano-sized NbC powder comprises:
and performing ball milling treatment on NbC powder with the granularity of 10-20 mu m to obtain the nano NbC powder.
6. The method of claim 1, wherein the method of preparing the nanoscale TaC powder comprises:
and performing ball milling treatment on TaC powder with the granularity of 20-40 mu m to obtain the nanoscale TaC powder.
7. The method of claim 1, wherein reacting the initial fuel pellets at a first temperature for a first period of time in the presence of flowing hydrogen to remove free carbon to produce (U, nb, ta) C quaternary fuel pellets comprises:
in the vacuum degree of (1-3) x 10 -3 And under the condition of Pa and flowing hydrogen, reacting the initial fuel pellets for 1-3 hours at the first temperature of 1600-1755 ℃ to remove free carbon, so as to obtain the (U, nb, ta) C quaternary fuel pellets.
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