Prismatic triso particle dispersed additive fuel elements, methods of making and using the same

Abstract

The application discloses a kind of prismatic TRISO particle dispersion additive fuel element and its preparation method and application, it is related to nuclear fuel technical field.The method includes using binder spray forming process or photocuring forming process to prepare SiC shell;SiC shell is treated by defatting;SiC shell after defatting is treated by chemical vapor infiltration method pretreatment;Fill simulated TRISO particle and SiC matrix powder in pretreated SiC shell, and using high solid content SiC slurry is encapsulated, then using enhanced chemical vapor infiltration method is densified to dry after additive SiC element, it is prismatic TRISO particle dispersion additive fuel element that obtains.The application combines the characteristics of TRISO fuel particle with higher inherent safety and nuclear grade SiC ceramic material with excellent high-temperature and radiation performance, and cooperates with additive manufacturing process, to improve the flexibility and expandability of design, and has great application potential in high-temperature gas cooled reactor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear fuel, in particular to a prismatic TRISO particle dispersion additive fuel element and a preparation method and application thereof. BACKGROUND

[0002] Advanced manufacturing (such as additive manufacturing) and artificial intelligence technology provide technical support for the development and deployment of advanced reactors. By integrating multiple disciplines, the design, manufacturing, evaluation and deployment of advanced nuclear energy systems are accelerated to achieve the goal of significantly reducing costs, improving the deployment efficiency of new reactors, accelerating nuclear energy innovation and modernization.

[0003] Advanced manufacturing combined with intelligent design creates basic conditions for revolutionary changes in reactor types. On the one hand, it allows high-performance SiC materials and three-structure isotropic particle fuel (TRISO) to be made into structural integration SiC-TRISO fuel components, which improves the efficiency of the reactor core construction and reduces the deployment cost on the basis of safety; on the other hand, using advanced additive manufacturing technology, the reactor core fuel components are given unlimited design space, and integrated fuel components that are not limited by the geometric size of traditional manufacturing can be prepared, which can manipulate geometric complexity to enhance the required performance characteristics, such as adding surface features on complex nuclear fuel elements, optimizing the topology of the assembly, achieving better neutron economy or heat transfer characteristics, and adjusting the power and coolant distribution, reducing temperature gradients and maintaining low stress levels for core components, which provides sufficient conditions for reactor power optimization.

[0004] Therefore, carrying out advanced additive manufacturing technology and intelligent design research for TCR reactor core fuel components, completing the evaluation of the core performance and service behavior of the components, and establishing the corresponding performance degradation mechanism and reliability evaluation of the components are the key to realizing this paradigm shift in reactor deployment, and also determine the design, manufacturing and safe service life of the reactor; in addition, the development of additive manufacturing technology suitable for various advanced nuclear energy systems is also an inevitable trend of advanced reactor design and development, which can effectively shorten the research and development, evaluation, verification and application cycle.

[0005] Currently, the Oak Ridge National Laboratory in the United States has completed the preliminary design, manufacturing and evaluation of the Transmutation Challenge Reactor, from the overall feature design of the reactor, the optimization design of the fuel component structure to the integrated additive manufacturing of SiC-TRISO fuel components, the evaluation of the key service performance (mechanical properties, thermophysical properties, and radiation resistance) of the components, all have been completed and have related public data support.

[0006] In the prior art, the combination of binder jet printing and chemical vapor infiltration can produce high-purity, fully crystalline ceramics in a process that is critical for achieving ideal performance in extremely high-temperature applications or in the presence of displacement damage.

[0007] The skilled in the art also obtains submicron silicon carbide powder with reduced light absorption and no silicon dioxide impurities on the surface by physical modification means under a specific heat treatment system to solve the problem of 3D printing silicon carbide forming precision in the prior art. Meanwhile, the skilled in the art also simulates the thermodynamic behavior of full ceramic micro-encapsulated dispersed (FCM) fuel with different fuel-free zone thicknesses by using a two-dimensional feature model, adjusts the distance between TRISO particles by optimizing the thickness of the fuel-free zone, and ensures that the fuel-free zone and the SiC layer have a low stress level at the same time. The structure optimization provides a basis for the application of FCM fuel.

[0008] In the prior art, the geometric shape flexibility of the traditional graphite-based fuel element is limited, and there are limitations in the volume utilization rate of the fuel phase, and the potential of the fuel cannot be fully utilized. In addition, the stability and performance of the graphite-based fuel element under high temperature and high radiation conditions are challenging, and cannot meet the reliability and safety requirements of new reactor types. SUMMARY

[0009] In view of the deficiencies in the above background art, the present application mainly solves the problems of geometric shape design flexibility, volume utilization rate of the fuel phase, and stability and performance under high temperature and high radiation conditions of the existing traditional graphite-based fuel element.

[0010] The present application provides a prismatic TRISO particle dispersed additive fuel element and its preparation method and application. The method is studied for four main process flows of additive manufacturing, shell pre-CVI, particle loading method and CVI densification, and an ideal densified simulated fuel element is obtained. The prismatic TRISO dispersed fuel element combines the characteristics of TRISO fuel particles with high inherent safety and nuclear-grade SiC ceramic materials with excellent high-temperature and radiation resistance, and cooperates with the additive manufacturing process to improve the flexibility and expandability of the design, and has great application potential in high-temperature gas cooled reactors.

[0011] The first object of the present application is to provide a preparation method of a prismatic TRISO particle dispersed additive fuel element, comprising the following steps:

[0012] The SiC shell is prepared by a binder jet molding process or a light curing molding process; wherein the SiC shell is a prismatic shell and the inside is a hollow structure;

[0013] The SiC shell is subjected to a debinding treatment;

[0014] The SiC shell after the debinding treatment is subjected to a chemical vapor infiltration method pretreatment to obtain a pretreated SiC shell;

[0015] The SiC shell is prepared by a binder jetting process, and the process comprises the following steps:

[0016] Preferably, the SiC shell is prepared by a binder jetting process, and the process comprises the following steps:

[0017] The SiC powder has a particle size of 30-40 μm, and the phase is α phase or β phase, and the mass ratio is 80-95%; the binder has a mass ratio of about 5-20%.

[0018] The printing speed is 30-80 mm / s, and the printing layer thickness is 0.03-0.06 mm.

[0019] Preferably, the binder is a mixed adhesive of water-based adhesive C6H 10 O5 and phenolic resin, and the mass ratio is 1:1-2.

[0020] Preferably, the SiC shell is prepared by a light curing forming process, and the process comprises the following steps:

[0021] The SiC powder, resin monomer, photoinitiator and dispersant are prepared to obtain SiC ceramic slurry;

[0022] The SiC ceramic slurry is ball milled for a period of time, and then the SiC shell is obtained by light curing printing;

[0023] The SiC powder has a particle size of 5-40 μm, and the phase is β phase silicon carbide, and the Si / C element atomic percentage is 1-1.05;

[0024] The resin monomer comprises HDDA and TMPTA, and the mass ratio of the HDDA to the total mass of the resin monomer is 40-55%;

[0025] The dispersant is a mixed dispersant of KOS110 and Solsperse 17000, and the mass ratio is 1:1-1:2, and the content is 4-6 wt%;

[0026] The ball milling time is 3-5 h, and the viscosity of the slurry is 2.6-2.8 Pa·s (≤3 Pa·s);

[0027] The light curing printing parameter is slice thickness 50 mu m, ultraviolet wavelength 405 nm; intensity: 7.5 mw / cm2; exposure time: 30 seconds.

[0028] The solid phase content of the SiC ceramic slurry is 40-45 vol%.

[0029] Preferably, the SiC shell prepared by the light curing molding process has a resin content of 50-60%, a wall thickness of 0.8-1 mm, a printing size accuracy of ≥0.08-0.1 mm, and a shell density of 40-50% after printing is completed.

[0030] Preferably, the debinding treatment comprises: a heating rate of 1-3℃ / min, holding at 500-600℃ for 1-3h, and a cooling rate of 3-5℃ / min.

[0031] Preferably, the SiC shell after debinding treatment is subjected to chemical vapor infiltration pretreatment, comprising:

[0032] Trichloromethylsilane is used as the source gas, hydrogen is used as the carrier gas, and hydrogen and argon are used as the dilution gas, wherein the molar ratio of hydrogen to trichloromethylsilane is 11-9:1, the deposition temperature is controlled at 900-1080℃, the flow rate of the carrier gas hydrogen is 2-4L / min, the flow rate of the dilution gas hydrogen is 1-2L / min, and the flow rate of the dilution gas argon is 3-4L / min. The deposition pressure is 2-5kPa, and the deposition time is 20-50h.

[0033] The prepared dense SiC shell has a density of 60-70%.

[0034] Preferably, when the SiC shell after pretreatment is filled with simulated TRISO particles and SiC matrix powder, the volume ratio of the simulated TRISO particles to the SiC matrix powder is 5.5:4.5.

[0035] A second object of the present application is to provide a prismatic TRISO particle dispersed additive fuel element.

[0036] A third object of the present application is to provide an application of the prismatic TRISO particle dispersed additive fuel element in the nuclear industry.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] The application provides a prismatic TRISO particle dispersion additive fuel element and a preparation method and application thereof, and the preparation technology combining 3D printing and a two-step chemical vapor deposition process can realize preparation of a complex structure of a silicon carbide shell, can break through the limitation of a traditional fuel forming mode of a reactor core and a flow channel design, and makes the thermal fluid characteristics and structural reliability of a reactor core better.

[0039] The application adopts a nuclear-grade SiC ceramic material with excellent high-temperature and radiation resistance as the shell and coolant channel of the fuel element, and improves the high-temperature resistance and radiation resistance.

[0040] The application realizes high fuel phase volume by adopting a TRISO particle dispersion design, improves the proportion of TRISO particles in the fuel element by loading, chemical vapor infiltration densification and packaging, and does not need high-temperature sintering, so that many disadvantages of the prior art are solved. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 Printing the SiC shell for the binder;

[0042] Figure 2 Processing the SiC shell for photocuring;

[0043] Figure 3 Densifying the shell for the pre-CVI part;

[0044] Figure 4 Schematic diagram after powder mixing and loading;

[0045] Figure 5 Densifying the fuel element for CVI;

[0046] Figure 6 Effect diagram of the additive SiC-based particle dispersion type simulation fuel;

[0047] Figure 7 Microstructure diagram of the densified SiC shell;

[0048] Figure 8 Fuel temperature distribution diagram at the end of the service life. DETAILED DESCRIPTION

[0049] In order for those skilled in the art to better understand the technical solutions of the application and implement the same, the application is further described below in combination with specific embodiments and drawings, but the embodiments are not used as limitations to the application.

[0050] The application aims to provide a prismatic TRISO particle dispersed additive manufacturing fuel element and a preparation method and application thereof, and researches five main technological processes of additive manufacturing, debinding treatment, shell pre-CVI, particle loading method and CVI densification, and ideal densified simulation fuel elements are obtained. The prismatic TRISO dispersed fuel element combines the characteristics of TRISO fuel particles with high inherent safety and nuclear-grade SiC ceramic materials with excellent high-temperature and irradiation performance, and is combined with the additive manufacturing process to improve the flexibility and expandability of the design, and has great application potential in high-temperature gas cooled reactors.

[0051] To achieve the above-mentioned purpose, the first aspect of the application provides a preparation method of a prismatic TRISO particle dispersed additive manufacturing fuel element, comprising the following steps:

[0052] The SiC shell is prepared by using a binder jetting forming process or a light-cured forming process; wherein the SiC shell is a prismatic shell and has an internal cavity structure;

[0053] The SiC shell is subjected to debinding treatment;

[0054] The SiC shell after debinding treatment is subjected to chemical vapor infiltration pretreatment;

[0055] The simulation TRISO particles and SiC matrix powder are filled into the pretreated SiC shell, and the SiC slurry with a high solid content of 80-90% (i.e. the mass ratio of silicon carbide powder to deionized water is 4:1-9:1) is used to seal the port, and then the additive SiC element after drying at 80℃ for 10-20h is subjected to densification by using enhanced chemical vapor infiltration, and the prismatic TRISO particle dispersed additive manufacturing fuel element is obtained in a deposition furnace at 1000-1200℃, a deposition pressure of 3-10kPa and a deposition time of 96-120h.

[0056] The SiC slurry is SiC slurry with a solid content of 80-90%, i.e. the mass ratio of silicon carbide powder to deionized water is 4-9:1.

[0057] Compared with the preparation process of the traditional rod type nuclear fuel element, the prismatic dispersion TRISO particle fuel element adopts light curing molding and binder jetting molding and other additive molding processes to realize the molding of the complex structure of the silicon carbide shell, and in order to maintain the purity and precision of the nuclear material element, the silicon carbide shell after debinding is subjected to multi-step chemical vapor deposition densification, wherein the first step of low-temperature short-time chemical vapor pre-deposition can make the silicon carbide shell have a certain strength to ensure the smooth loading of the TRISO fuel particles; the long-time chemical vapor pre-deposition in the second step after packaging and drying can obtain high-density additive fuel elements. The preparation process of the prismatic dispersion TRISO particle fuel element can better control the volume ratio of the fuel and the coolant, avoid the problems that the internal state of the spherical bed fuel is difficult to detect and control, and the utilization rate of the prismatic fuel is higher.

[0058] In the application, when the binder jetting molding process is used to prepare the SiC shell, the following steps are included:

[0059] 30-40 mu m SiC powder particle size is selected, the phase is alpha or beta phase, and the mass ratio is 80-95%; about 5-20% of the binder is selected;

[0060] The printing speed is 30-80 mm / s, and the printing layer thickness is 0.03-0.06 mm.

[0061] The binder is a mixed adhesive of water-based adhesive C6H 10 O5 and phenolic resin, and the mass ratio is 1:1-2.

[0062] The shell density after the binder jetting molding printing is completed is 40-50%.

[0063] Exemplarily, when the light curing molding process is used to prepare the SiC shell, the following steps are included:

[0064] SiC ceramic slurry is prepared by mixing SiC powder, resin monomer, photoinitiator and dispersant;

[0065] After the SiC ceramic slurry is ball milled for a period of time, the SiC shell is obtained by light curing printing;

[0066] The SiC powder selected is 5-40 mu m, the phase is beta silicon carbide, and the Si / C element atomic percentage is 1-1.05;

[0067] The resin monomer includes HDDA and TMPTA, and the HDDA accounts for 40-55% of the total mass of the resin monomer;

[0068] The dispersant is a double dispersant of KOS110 and Solsperse 17000 with a mass ratio of 1:1, and the content is 4-6wt%; the photoinitiator is TPO, and the content is 2wt%;

[0069] The ball milling time is 3-5h, and the viscosity of the slurry is 2.6-2.8Pa·s (≤3Pa·s) at this time;

[0070] The light curing printing parameters are that the slice thickness is 50μm, the ultraviolet wavelength is 405nm; the intensity is 7.5mw / cm2; and the exposure time is 30 seconds.

[0071] The solid content of the SiC ceramic slurry is 40-45vol%.

[0072] Specifically, the SiC shell prepared by the light curing forming process has a resin content of 50-60%, a wall thickness of 0.8-1mm, a printing size accuracy of ≥0.08-0.1mm, and a shell density of 40-50% after printing.

[0073] In the application, the debinding treatment comprises: a heating rate of 1-3℃ / min, holding at 500-600℃ for 1-3h, and a cooling rate of 3-5℃ / min.

[0074] The SiC shell after debinding treatment is pretreated by a chemical vapor infiltration method, comprising:

[0075] Trichloromethylsilane is used as a source gas, hydrogen is used as a carrier gas, and hydrogen and argon are used as dilution gases, wherein the molar ratio of hydrogen to trichloromethylsilane is 11-9:1, the deposition temperature is 900-1080℃, the deposition pressure is 2-5kPa, and the deposition time is 20-50h;

[0076] The prepared dense SiC shell has a density of 60-70%.

[0077] Exemplarily, the shell is pretreated by a chemical vapor infiltration (CVI) method: trichloromethylsilane is used as a source gas, hydrogen is used as a carrier gas, and hydrogen and argon are used as dilution gases, wherein the molar ratio of hydrogen to trichloromethylsilane is 11-9:1, the deposition temperature is controlled at 900-1080℃, the flow rate of the carrier gas hydrogen is 2-4L / min, the flow rate of the dilution gas hydrogen is 1-2L / min, and the flow rate of the dilution gas argon is 3-4L / min. The deposition pressure is 2-5kPa, the deposition time is 20-50h, and the shell density obtained after the preliminary CVI process is 60-70%.

[0078] In the present application, when filling the simulated TRISO particles and SiC matrix powder into the dense SiC shell, the volume ratio of the simulated TRISO particles to the SiC matrix powder is 5.5:4.5, and the SiC slurry with a solid content of 80-90% (i.e. the mass ratio of silicon carbide powder to deionized water is 4:1-9:1) is used to seal the port.

[0079] For example, the process of filling after particle mixing powder treatment is used to complete the filling of particles and SiC powder in the additive SiC shell. The particles and SiC powder are weighed according to the volume ratio of 5.5:4.5, and the mixing ratio of the particles and SiC powder needs to be slightly higher than the preset phase volume of 50%. The mixture of particles and SiC powder is continuously mixed in a rotary mixer for 72h, and the rotation speed of the ball mill is constant at 450 / min. The mixed particles and powder are poured into the shell in batches and are respectively vibrated, and the SiC slurry with a solid content of 80-90% (i.e. the mass ratio of silicon carbide powder to deionized water is 4:1-9:1) is used to seal the port, and then the dried additive SiC element is densified at 80℃ for 10-20h by using the enhanced chemical vapor infiltration method: trichloromethylsilane is used as the source gas, hydrogen is used as the carrier gas, and hydrogen and argon are used as the dilution gas, wherein the molar ratio of hydrogen to trichloromethylsilane is 11-8:1, the deposition temperature is controlled at 1000-1200℃, the flow rate of the carrier gas hydrogen is 3-5L / min, the flow rate of the dilution gas hydrogen is 1-3L / min, and the flow rate of the dilution gas argon is 3-6L / min. The deposition pressure is 3-10kPa, the deposition time is 96-120h, and the density of the fuel SiC matrix after deposition is higher than 85%.

[0080] The second aspect of the present application provides a prismatic TRISO particle dispersed additive fuel element.

[0081] The third aspect of the present application provides an application of the prismatic TRISO particle dispersed additive fuel element in the nuclear industry.

[0082] It should be noted that, in the present application, the experimental methods used are conventional methods unless otherwise specified; and the reagents and materials used are commercially available unless otherwise specified.

[0083] Example 1

[0084] In this example, the prismatic TRISO particle dispersed fuel element is manufactured by using the binder jet molding process.

[0085] Step one: select 30μm SiC powder particle size, phase is alpha phase, mass ratio is about 85%, and the binder used is a mixed binder of water-based adhesive C6H 10 O5 and phenolic resin, the mass ratio is 1:1.5, and the binder accounts for about 10% of the mass, for example Figure 1The image shows a SiC shell printed with adhesive.

[0086] Step Two: First, spread the dried β-SiC powder to fill the powder supply cylinder, then spread a layer of SiC powder on the worktable. Input the 3D model of the SiC shell to be printed into the computer. The printing speed is 40mm / s, and the layer thickness is 0.05mm. The printhead begins to spray binder according to the path sliced ​​by the computer. After the printhead completes one inkjet, the work cylinder lowers by one layer, and the powder supply cylinder rises by one layer. The powder spreading process is completed by the rotation and movement of the powder spreading roller. One round trip completes the printing process of the entire SiC shell. After printing, remove the sample, dry and cure it. The shell density is 46%.

[0087] Step 3: Degrease the shell: the heating rate is 2℃ / min, and after reaching 600℃, it is kept at 2h, and the cooling rate is 4℃ / min.

[0088] Step 4: Pretreatment of the shell using Chemical Vapor Infiltration (CVI): Trichloromethylsilane is used as the source gas, hydrogen as the carrier gas, and hydrogen and argon as dilution gases. The molar ratio of hydrogen to trichloromethylsilane is 11:1. The deposition temperature is controlled at 1000℃. The flow rate of the carrier gas hydrogen is 3 L / min, the flow rate of the dilution gas hydrogen is 1 L / min, and the flow rate of the dilution gas argon is 3 L / min. The deposition pressure is 2-5 kPa, and the deposition time is 40 h. The shell density obtained after the preliminary CVI process is 60%. The dimensional accuracy error is controlled within ±0.1 mm. The shell after pre-CVI is as follows: Figure 3 As shown.

[0089] Step 5: Fill the shell with simulated TRISO particles and SiC matrix powder. Simulated TRISO particles with a ZrO2 core were used in this study. Each coating layer of the simulated TRISO particles was obtained using chemical vapor deposition. The matrix was pure β-SiC powder. The mixing process was carried out in a rotary mixer. Before mixing, the simulated particles and SiC powder were weighed at a volume ratio of 5.5:4.5, with 120.9g of simulated particles and 52.8g of SiC powder weighed. To avoid the particle filling fraction being less than the target phase volume, the mixing ratio needed to be slightly higher than the preset phase volume by 50%. The mixture of simulated particles and SiC powder was continuously mixed in the rotary mixer for 72 hours, with the ball mill speed maintained at a constant 450 rpm. Large vibrations under external force were avoided during powder transfer and filling to prevent powder shedding. The mixed granules and powder were poured into the shell in batches and compacted separately. The ports were then sealed with SiC slurry containing 90% solids (i.e., a silicon carbide powder to deionized water mass ratio of 9:1) and dried at 80°C for 15 hours. The final filled sample is shown below. Figure 4 As shown.

[0090] Step six: after the shell sample is dried, the deposition temperature is controlled at 1150℃, the deposition environment is 5-6kPa, and the deposition time is 100h in the CVI deposition furnace. Trichloromethylsilane is used as the source gas, hydrogen is used as the carrier gas, and hydrogen and argon are used as the dilution gas. The molar ratio of hydrogen to trichloromethylsilane is 10:1, the flow rate of the carrier gas hydrogen is 4L / min, the flow rate of the dilution gas hydrogen is 2L / min, and the flow rate of the dilution gas argon is 5L / min. The density of the deposited fuel SiC matrix is about 85%, and the final deposition is completed to obtain a fuel sample as shown in Figure 5 , and the microstructure of the shell of the sample is as shown in Figure 7 .

[0091] Example 2

[0092] In this example, the prismatic TRISO particle dispersed fuel element is manufactured by using the light-cured molding process for additive manufacturing.

[0093] Step one: the selected SiC powder is 8μm, and the phase is β-phase silicon carbide, and the atomic percentage of Si / C elements is 1:1. The prepared SiC ceramic slurry uses HDDA-TMPTA double resin monomer system as the resin monomer, the mass ratio of HDDA / (HDDA+TMPTA) is 50%; the content of TPO photoinitiator is 2wt%(relative to the total mass of resin); the dispersing agent is a double dispersing agent with a mass ratio of 1:1 of KOS110+17000, and the optimal content is 5wt%; the solid phase content of the SiC ceramic slurry is 40vol%(≥30vol%); the ball milling time is 4h, at which time the viscosity of the slurry is 2.8Pa·s(≤3Pa·s), the printing parameters are slice thickness 50μm, ultraviolet wavelength 405nm; intensity: 7.5mw / cm 2 ; exposure time: 30 seconds. The light-cured SiC shell is as shown in Figure 2 .

[0094] Step two: for the light-cured molding sample, the resin content is 55%, the wall thickness is 0.8mm, the printing size accuracy is not less than 0.08mm, and after printing, the shell density is 45%.

[0095] Step three: the shell is subjected to a debinding treatment: the heating rate is 2℃ / min, the temperature is kept at 600℃ for 2h, and the cooling rate is 4℃ / min.

[0096] Step four: the shell is pre-processed by chemical vapor infiltration (CVI) method: trichloromethyl silane as source gas, hydrogen as carrier gas, hydrogen and argon as dilution gas, the molar ratio of hydrogen to trichloromethyl silane is 10:1, the deposition temperature is controlled at 1080℃, the flow rate of the carrier gas hydrogen is 4L / min, the flow rate of the dilution gas hydrogen is 2L / min, and the flow rate of the dilution gas argon is 4L / min. The deposition pressure is 2-5kPa, the deposition time is 50h, and the shell density after the preliminary CVI process is about 65%, and the dimensional accuracy error is controlled within ±0.1mm.

[0097] Step five: the shell is filled with simulated TRISO particles and SiC matrix powder. Simulated TRISO particles with ZrO2 core are used, and each coating layer of the simulated TRISO particles is obtained by chemical vapor deposition process, and the matrix is selected from pure β-SiC powder. The powder mixing process is carried out in a rotary mixer. Before mixing, the simulated particles and SiC powder are weighed according to the volume ratio of 5.5:4.5, 120.9g of simulated particles and 52.8g of SiC powder are weighed. In order to avoid the particle filling fraction being less than the target phase volume, the mixing ratio needs to be slightly higher than the preset phase volume of 50%. The mixture of simulated particles and SiC powder is continuously mixed in the rotary mixer for 72h, and the ball mill speed is constant at 450 / min. During the transfer and filling process of the powder, large amplitude vibration under external force should be avoided to prevent the powder from falling off. The mixed particles and powder are poured into the shell in batches and are respectively vibrated, and the SiC slurry with a solid content of 90% (i.e. the mass ratio of silicon carbide powder to deionized water is 9:1) is used to seal the port, and is dried at 80℃ for 15h.

[0098] Step six: after the shell sample is dried, it is placed in a CVI deposition furnace, and the deposition temperature is controlled at 1200℃ in a deposition environment with a pressure of 6-9kPa, and the deposition time is 120h. Trichloromethyl silane is used as the source gas, hydrogen is used as the carrier gas, and hydrogen and argon are used as the dilution gas. The molar ratio of hydrogen to trichloromethyl silane is 9:1, the flow rate of the carrier gas hydrogen is 5L / min, the flow rate of the dilution gas hydrogen is 3L / min, and the flow rate of the dilution gas argon is 6L / min. The fuel SiC matrix density after deposition is about 88%. As shown in Figure 6 The effect picture of the additive SiC-based particle dispersed type simulation fuel CT provided by Example 2 can be seen. Most of the particles identified have relatively consistent particle sizes, and a small part of the particles at the bottom have slightly higher particle sizes.

[0099] As shown in Figure 8 , the temperature field of the unit body provided by Example 2 at the end of the service life. From the perspective of overall temperature distribution, the highest temperature of the particles near the center region is about 1050K, which is lower than the peak fuel temperature of 1134K. The cooling effect of most of the fuel region is good, and the temperature is generally low.

[0100] The preferred embodiments are described herein, including the best mode known to the inventors of practicing the application. Of course, variations on the preferred embodiments will occur to those of ordinary skill in the art once advised of the application in general, and the best mode in particular, and it will be understood that such variations are encompassed by the application and the techniques disclosed herein. Accordingly, while the application is presented in terms of the preferred embodiments, it should be appreciated that the application is not limited to these embodiments, but rather the scope of the application is to be determined from the claims.

[0101] While the application has been illustrated and described in the best mode, it will be readily apparent to those of ordinary skill in the art that many changes, modifications, replacements and substitutions are possible in the concepts described and illustrated, without departing from the spirit and scope of the present application, which should be limited only by the scope of the claims and the equivalents thereof.

Claims

1. A method of making a prismatic TRISO particle dispersed additive fuel element, characterized in that, The method comprises the following steps: The SiC shell is prepared by a binder jetting process or a light curing molding process; wherein the SiC shell is a prismatic shell and has an internal cavity structure; The SiC shell is subjected to a debinding treatment; The SiC shell after the debinding treatment is subjected to a chemical vapor infiltration method pretreatment; Simulated TRISO particles and SiC matrix powder are filled into the pretreated SiC shell, and SiC slurry is used to seal the port, and then the dried additive SiC element is densified by enhanced chemical vapor infiltration method at 80 DEG C for 10-20 h, using trichloromethylsilane as a source gas, hydrogen as a carrier gas, and hydrogen and argon as dilution gases, wherein the molar ratio of hydrogen to trichloromethylsilane is 11-8:1, the deposition temperature is controlled at 1000-1200 DEG C, the flow rate of the carrier gas hydrogen is 3-5 L / min, the flow rate of the dilution gas hydrogen is 1-3 L / min, and the flow rate of the dilution gas argon is 3-6 L / min, the deposition pressure is 3-10 kPa, and the deposition time is 96-120 h, thereby obtaining a prismatic TRISO particle dispersed additive fuel element; During the debinding treatment, the heating rate is 1-3 DEG C / min, the temperature is kept at 500-600 DEG C for 1-3 h, and the cooling rate is 3-5 DEG C / min; The SiC shell after the debinding treatment is subjected to a chemical vapor infiltration method pretreatment, comprising: Using trichloromethylsilane as a source gas, hydrogen as a carrier gas, and hydrogen and argon as dilution gases, wherein the molar ratio of hydrogen to trichloromethylsilane is 11-9:1, the deposition temperature is controlled at 900-1080 DEG C, the flow rate of the carrier gas hydrogen is 2-4 L / min, the flow rate of the dilution gas hydrogen is 1-2 L / min, and the flow rate of the dilution gas argon is 3-4 L / min, the deposition pressure is 2-5 kPa, and the deposition time is 20-50 h; The prepared densified SiC shell has a density of 60-70%; When the simulated TRISO particles and SiC matrix powder are filled into the pretreated SiC shell, the volume ratio of the simulated TRISO particles to the SiC matrix powder is 5.5:4.5; The mass ratio of the silicon carbide powder in the SiC slurry to deionized water is 4-9:

1.

2. The method of claim 1, wherein the prismatic TRISO particle dispersed fuel element is prepared by the steps of: When the SiC shell is prepared by a binder jetting process, the process comprises: 30-40 mu m SiC powder particle size is selected, the phase is alpha or beta phase, and the mass ratio is 80-95%; a binder with a mass ratio of 5-20% is selected; The printing speed is 30-80 mm / s, and the printing layer thickness is 0.03-0.06 mm.

3. The method of claim 2, wherein the prismatic TRISO particle dispersed fuel element is prepared by the steps of: The binder is a water-based adhesive C6H 10 A mixed adhesive of O5 and phenol-formaldehyde resin in a mass ratio of 1:1-2.

4. The method of making a prismatic TRISO particle dispersed fuel element of claim 1, wherein, When the SiC shell is prepared by a light curing molding process, the process comprises: SiC ceramic slurry is prepared by mixing SiC powder, resin monomer, photoinitiator and dispersant; The SiC shell is obtained by light curing printing after ball milling the SiC ceramic slurry for a period of time, and then by light curing; The SiC powder used is 5-40 mu m, the phase is beta silicon carbide, and the Si / C element atomic percentage is 1-1.

05. The resin monomers include HDDA and TMPTA, and the HDDA accounts for 40-55% of the total mass of the resin monomers; The dispersant is a double dispersant of KOS110 and Solsperse 17000 with a mass ratio of 1:1, and the content is 4-6wt%; The ball milling time is 3-5h, and the viscosity of the slurry is 2.6-2.8Pa·s (≤3Pa·s) at this time; The light curing printing parameters are slice thickness 50 μm, ultraviolet wavelength 405 nm; intensity: 7.5 mw / cm 2 ; exposure time: 30 seconds; The solid content of the SiC ceramic slurry is 40-45vol%.

5. The method of claim 4, wherein the prismatic TRISO particle dispersed fuel element is prepared by the steps of: The SiC shell prepared by the light curing molding process has a resin content of 50-60%, a wall thickness of 0.8-1mm, a printing size accuracy of ≥0.08-0.1mm, and a shell density of 40-50% after printing.

6. A prismatic TRISO particle dispersed additive fuel element prepared by the method of any one of claims 1-5.

7. Use of the prismatic TRISO particle dispersed additive fuel element of claim 6 in the nuclear industry.

Images