CN116525164A - Preparation method of nuclear fuel microsphere with core-shell structure - Google Patents

Preparation method of nuclear fuel microsphere with core-shell structure Download PDF

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Publication number
CN116525164A
CN116525164A CN202310248169.8A CN202310248169A CN116525164A CN 116525164 A CN116525164 A CN 116525164A CN 202310248169 A CN202310248169 A CN 202310248169A CN 116525164 A CN116525164 A CN 116525164A
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core
shell
phase
nuclear
shell structure
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常振旗
舒瀚东
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University of Science and Technology of China USTC
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University of Science and Technology of China USTC
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C21/00—Apparatus or processes specially adapted to the manufacture of reactors or parts thereof
    • G21C21/02—Manufacture of fuel elements or breeder elements contained in non-active casings
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/02—Fuel elements
    • G21C3/04—Constructional details
    • G21C3/045—Pellets
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/02—Fuel elements
    • G21C3/04—Constructional details
    • G21C3/06—Casings; Jackets
    • G21C3/07—Casings; Jackets characterised by their material, e.g. alloys
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/42—Selection of substances for use as reactor fuel
    • G21C3/58—Solid reactor fuel Pellets made of fissile material
    • G21C3/62—Ceramic fuel
    • G21C3/623—Oxide fuels
    • 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 invention provides a preparation method of a nuclear fuel microsphere with a core-shell structure, which comprises the following steps: forming core-shell structure droplets by the shell solution wrapped with the core-phase droplets under the shearing action of the continuous phase solution; solidifying and calcining the core-shell structure liquid drops to obtain U 3 O 8 The core-shell structure nuclear fuel microsphere is core and ZrN is shell. The method provided by the invention successfully prepares the nuclear fuel microsphere with the core-shell structure; the core phase of the microsphere is U 3 O 8 The shell phase is ZrN, the structure is stable, and the size is uniform; compared with the traditional dispersion type nuclear fuel, the U prepared by the fuel microsphere prepared by the invention 3 O 8 ZrN dispersed nuclear fuel can realize U as fuel 3 O 8 Uniformly distributed in ZrN as matrix, and can increase the ratio of fuel phase in dispersed fuel.

Description

Preparation method of nuclear fuel microsphere with core-shell structure
Technical Field
The invention belongs to a core (U) 3 O 8 ) The field of preparation of core-shell (ZrN) structure nuclear fuel microspheres, in particular to a preparation method of a core-shell structure nuclear fuel microsphere.
Background
Nuclear energy is a high-efficiency green energy source, and is important for energy development, but the safety problem is always focused. The united states department of energy first proposed the concept of accident tolerant fuels (Accident Tolerant Fuel, ATF for short): the accident tolerant fuel can maintain the original performance of the fuel or improve the performance of the fuel under the normal working condition, and can stably operate for a period of time under the accident working condition. At present, two main development routes of accident tolerant fuels are adopted, one is to improve the physical and mechanical properties of cladding materials, the other is to develop fuel pellets which remain safe in an accident state, and dispersion type nuclear fuels are important types of safer nuclear fuels.
The dispersion fuel is prepared by uniformly dispersing nuclear fuel microspheres as a fuel phase in a matrix phase material having high thermal conductivity, high neutrons and chemical inertness. In contrast to conventional nuclear fuels, each nuclear fuel microsphere in the dispersion fuel can be considered a tiny fuel element, and the matrix acts as an envelope. How to uniformly disperse the fuel phase in the matrix and avoid agglomeration of the fuel phase particles is an important problem to be solved in preparing the high-performance dispersion type nuclear fuel pellet.
Disclosure of Invention
Accordingly, the present invention is directed to a method for preparing a core-shell structure nuclear fuel microsphere, which successfully obtains a core (U) 3 O 8 ) -shell (ZrN) structured nuclear fuel microspheres.
The invention provides a preparation method of a nuclear fuel microsphere with a core-shell structure, which comprises the following steps:
forming core-shell structure droplets by the shell solution wrapped with the core-phase droplets under the shearing action of the continuous phase solution;
solidifying and calcining the core-shell structure liquid drops to obtain U 3 O 8 The core-shell structure nuclear fuel microsphere is core and ZrN is shell.
Preferably, the core phase solution comprises a core phase solution A and a core phase solution B, wherein the core phase solution A is prepared by the following components in percentage by mass of 3.57:3.74 a mixture of uranyl nitrate and water; the nuclear phase solution B is prepared from the following components in percentage by mass: 0.86:2.75 of a mixture of hexamethylenetetramine, urea and water.
Preferably, the shell phase solution is a suspension mixture of zirconium nitride powder, propylene glycol diacrylate and azobisisobutyronitrile.
Preferably, the mass ratio of the zirconium nitride powder to the propylene glycol diacrylate to the azodiisobutyronitrile is (18-22): (79-79.5): (0.78-0.82).
Preferably, the continuous phase solution is simethicone.
Preferably, the coagulation bath solution is a mixture of simethicone, toluene and azobisisobutyronitrile;
the mass ratio of the simethicone to the toluene to the azodiisobutyronitrile is 90: (9.2-9.7): (0.3-0.8).
In a specific embodiment, the mass ratio of the simethicone to the toluene to the azodiisobutyronitrile is 90:9.5:0.5.
preferably, the curing temperature is 88-93 ℃ and the curing time is 110-130 min.
Preferably, the calcining employs temperature programming;
the calcination specifically comprises: heating to 145-155 ℃ at a heating rate of 4.5-5.5 ℃/min under inert atmosphere, and staying for 1.5-2.5 hours; then heating to 390-410 ℃ at a heating rate of 1.5-2.5 ℃/min, and staying for 1.5-2.5 hours; then the temperature is raised to 780-820 ℃ at the temperature rising rate of 4.5-5.5 ℃/min, and the temperature is kept for 4.5-5.5 hours, thus obtaining U 3 O 8 The core-shell structure nuclear fuel microsphere is core and ZrN is shell.
The invention provides a preparation method of a nuclear fuel microsphere with a core-shell structure, which comprises the following steps: forming core-shell structure droplets by the shell solution wrapped with the core-phase droplets under the shearing action of the continuous phase solution; solidifying and calcining the core-shell structure liquid drops to obtain U 3 O 8 The core-shell structure nuclear fuel microsphere is core and ZrN is shell. The method provided by the invention successfully prepares the nuclear fuel microsphere with the core-shell structure; the core phase of the microsphere is U 3 O 8 The shell phase is ZrN, the structure is stable, and the size is uniform; compared with the traditional dispersion type nuclear fuel, the U prepared by the fuel microsphere prepared by the invention 3 O 8 ZrN dispersed nuclear fuel can realize U as fuel 3 O 8 Uniformly distributed in ZrN as matrix, and can increase the ratio of fuel phase in dispersed fuel.
Drawings
FIG. 1 shows a core (U) prepared in example 1 3 O 8 )-Optical microscopy pictures of the shell (ZrN) structure nuclear fuel gel microspheres are provided, and the scale is 500 mu m;
FIG. 2 shows the core (U) prepared in example 1 3 O 8 ) -optical microscopy pictures of shell (ZrN) structured nuclear fuel microspheres, scale 500 μm;
FIG. 3 shows a core (U) prepared in example 1 3 O 8 ) -a shell (ZrN) structure nuclear fuel microsphere structure;
FIG. 4 shows a core (U) prepared in example 1 3 O 8 ) -shell (ZrN) structured nuclear fuel microsphere shell layer elemental analysis map;
FIG. 5 shows a core (U) prepared in example 1 3 O 8 ) -a shell (ZrN) structured nuclear fuel microsphere inner core elemental analysis map;
FIG. 6 is a schematic diagram of a microfluidic control device according to the present invention;
FIG. 7 is an enlarged schematic view of the portion A of the microfluidic control device according to the present invention;
FIG. 8 is an enlarged schematic view of a portion B of a microfluidic control device according to the present invention;
in the figure, 1 is a shell phase injector; 2 is a shell phase conduit; 3 is a continuous phase injector; 4 is a continuous phase conduit; 5 is a nuclear phase injector; 6 is a shell phase syringe pump; 7 is a continuous phase syringe pump; 8 is a nuclear phase injection pump; 9 is a nuclear phase catheter; 10 is a T-shaped tee; 11 is a continuous phase conduit; 12 is a T-shaped tee; 13 is an output conduit; 14 is a collection container; 15 is a water bath kettle; 16 is a nuclear phase capillary; 17 is a nuclear phase droplet; 18 is a sealing sleeve; 19 is a shell phase capillary; 20 is core-shell structure liquid drop, 21 is cooling box.
Detailed Description
The invention provides a preparation method of a nuclear fuel microsphere with a core-shell structure, which comprises the following steps:
forming core-shell structure droplets by the shell phase solution wrapped with the core phase droplets under the shearing action of the continuous phase solution;
solidifying and calcining the core-shell structure liquid drops to obtain U 3 O 8 The core-shell structure nuclear fuel microsphere is core and ZrN is shell.
The method provided by the invention successfully prepares the nuclear fuel microsphere with the core-shell structure; core of microsphereThe phase being U 3 O 8 The shell phase is ZrN, the structure is stable, and the size is uniform; compared with the traditional dispersion type nuclear fuel, the U prepared by the fuel microsphere prepared by the invention 3 O 8 ZrN dispersed nuclear fuel can realize U as fuel 3 O 8 Uniformly distributed in ZrN as matrix, and can increase the ratio of fuel phase in dispersed fuel.
In the present invention, the ZrN shell has a high melting point, high thermal conductivity, low free energy of formation, low water vapor reactivity, and low neutron absorption cross section. U with ZrN as matrix prepared by using core-shell structure microsphere as material 3 O 8 The ZrN dispersed nuclear fuel pellet can effectively avoid the aggregation of fuel phase particles in the fuel pellet, and realize the uniform distribution of the fuel phase particles.
In the invention, the nuclear phase solution comprises a nuclear phase solution A and a nuclear phase solution B, wherein the nuclear phase solution A is prepared from the following components in percentage by mass (3.55-6.30): (3.72-3.76) a mixture of uranyl nitrate and water; the nuclear phase solution B is prepared from the following components in percentage by mass: (0.84-0.88): (2.73-2.78), a mixture of hexamethylenetetramine, urea and water. In a specific embodiment, the core phase solution a is a mass ratio of 3.57:3.74 a mixture of uranyl nitrate and water; the nuclear phase solution B is prepared from the following components in percentage by mass: 0.86:2.75 of a mixture of hexamethylenetetramine, urea and water. The volume ratio of the core phase solution A to the core phase solution B in the core phase solution is preferably 1:0.98-1.02, and more preferably 1:1. the nuclear phase solution needs to be stored in a low-temperature environment, so that the prepared nuclear phase solution A and the prepared nuclear phase solution B need to be placed in a refrigerator, and after the nuclear phase solution A and the nuclear phase solution B are sufficiently cooled, the two solutions are taken out and uniformly stirred on a magnetic stirrer to prepare the nuclear phase solution.
In the present invention, the shell phase solution is a suspension mixture of zirconium nitride powder, azobisisobutyronitrile (AIBN) and tripropylene glycol diacrylate (TPGDA); the mass ratio of the zirconium nitride powder to the tripropylene glycol diacrylate to the azodiisobutyronitrile is (18-22): (79-79.5): (0.78-0.82), and in a specific embodiment, the mass ratio of the zirconium nitride powder to the tripropylene glycol diacrylate to the azodiisobutyronitrile is 20:79.2:0.8.
In the present invention, the continuous phase solution is simethicone.
In the invention, the coagulating bath solution is a mixture of simethicone, toluene and azodiisobutyronitrile; the mass ratio of the simethicone to the toluene to the azodiisobutyronitrile is 90: (9.2-9.7): (0.3 to 0.8); in a specific embodiment, the mass ratio of the simethicone to the toluene to the azodiisobutyronitrile is 90:9.5:0.5.
in the present invention, the curing is achieved by thermal initiation. After the core-shell structure liquid drops are formed, the liquid drops are dripped into a coagulating bath solution at 88-93 ℃, and hexamethylenetetramine in the core phase is heated and decomposed to generate ammonia, so that the pH value of the raw material liquid is rapidly increased, and a gel reaction is carried out to solidify the core phase. AIBN is a thermal initiator of azo, when heated, AIBN can initiate TPGDA solution to generate polymerization reaction and solidify, AIBN in coagulating bath solution can solidify microsphere surface layer, prevent microsphere from adhesion, AIBN in shell layer solution fixes zirconium nitride powder on shell layer.
In the invention, the calcination adopts a program temperature control; the calcining comprises: heating to 145-155 ℃ at a heating rate of 4.5-5.5 ℃/min, and staying for 1.5-2.5 hours; then heating to 390-410 ℃ at a heating rate of 1.5-2.5 ℃/min, and staying for 1.5-2.5 hours; then the temperature is raised to 780-820 ℃ at the temperature rising rate of 4.5-5.5 ℃/min, and the temperature is kept for 4.5-5.5 hours, thus obtaining U 3 O 8 Core-shell structure nuclear fuel microsphere taking ZrN as core and ZrN as shell
In a specific embodiment, the calcining is: heating to 150 ℃ at a heating rate of 5 ℃/min under inert atmosphere, and staying for 2 hours to completely remove free water and bound water in the gel microspheres; then heating to 400 ℃ at a heating rate of 2 ℃/min, and staying for 2 hours to remove various organic matters such as urea, tripropylene glycol diacrylate (TPGDA) and the like; heating to 800 deg.C at a heating rate of 5 deg.C/min, and maintaining for 5 hr to obtain core (U) 3 O 8 ) -shell (ZrN) structured nuclear fuel microspheres.
In the invention, the preparation method adopts a micro-fluid control device, and comprises a core phase capillary and a shell phase capillary; a nuclear phase conduit, a shell phase conduit, a continuous phase conduit, and an output conduit; a nuclear phase injection pump, a shell phase injection pump, a continuous phase injection pump and a nuclear phase injector, a shell phase injector and a continuous phase injector corresponding to the nuclear phase injection pump and the shell phase injection pump; sealing the sleeve; a T-shaped tee and a T-shaped tee; a water bath kettle; a container; and a cooling box.
In the invention, the shell phase injector is communicated with a first port of the T-shaped tee through a shell phase conduit; the second port of the first T-shaped tee is communicated with the inflow port of the shell-phase capillary; the third port of the tee T is in the same straight line with the second port of the tee T; the outflow port of the nuclear phase capillary is inserted into the capsule wall phase capillary through the second port of the T-shaped tee, and the inflow port of the nuclear phase capillary is communicated with the nuclear phase injector through the third port of the T-shaped tee; the inflow port of the shell-phase capillary tube is communicated with the third port of the T-shaped tee through the third port of the T-shaped tee; the shell phase capillary outflow port is inserted into the output catheter through the second port of the second T-shaped tee; the core phase capillary outflow port is in the shell phase capillary and is close to the shell phase capillary outflow port; the continuous phase injector is communicated with a first port of the T-shaped tee joint through a continuous phase conduit; the second port of the T-shaped tee is communicated with an output conduit; the output port of the output conduit is provided with a recovery container and a water bath kettle. The interface of the core-phase capillary and the third port of the T-shaped tee, the interface of the shell-phase capillary and the second port of the T-shaped tee and the interface of the shell-phase capillary and the third port of the T-shaped tee are respectively provided with a sealing sleeve, and the sealing sleeves are in threaded connection with the corresponding T-shaped tee and the T-shaped tee; the T-shaped tee joint is connected with the shell phase conduit through threads; the T-shaped tee joint is connected with the continuous phase conduit through threads; the whole device is placed into a cooling box and is connected with a recoverer and a water bath kettle outside the box through an output conduit.
And the nuclear phase conduit, the shell phase conduit, the continuous phase conduit and the output conduit are polytetrafluoroethylene tubes. The nuclear phase capillary is a glass capillary; and the shell phase capillary tube is a polytetrafluoroethylene tube.
The size of the nuclear phase capillary is as follows: an inner diameter of 100 μm and an outer diameter of 163 μm; the shell phase capillary size is: an inner diameter of 255 μm and an outer diameter of 510 μm; the nuclear phase conduit, the shell phase conduit and the continuous phase conduit have the same size, the outer diameter is 1600 mu m, and the inner diameter is 800 mu m; the output catheter size was: the inner diameter is 1600 μm and the outer diameter is 3200 μm.
The device prepares the core (U) 3 O 8 ) The principle of the shell (ZrN) structure nuclear fuel microsphere is as follows: filling the core phase solution which is cooled in advance into a core phase injector, placing the core phase injector on a core phase injection pump, respectively filling the prepared shell phase solution and continuous phase solution into the shell phase injector and the continuous phase injector, and respectively placing the prepared shell phase solution and continuous phase solution on the shell phase injector and the continuous phase injector pump; sequentially starting continuous phase, shell phase and nuclear phase injection pumps, controlling the flow of the nuclear phase, shell phase and continuous phase by adjusting the propulsion speed of the injection pumps, and obtaining the core (U) after heating and solidifying the formed liquid drops with the nuclear shell structure 3 O 8 ) -shell (ZrN) structured nuclear fuel gel microspheres; washing and calcining the gel microspheres to obtain a core (U) 3 O 8 ) -shell (ZrN) structured nuclear fuel microspheres.
The invention adopts a micro-fluid control device to prepare the core (U) 3 O 8 ) -shell (ZrN) structured nuclear fuel microspheres. The nuclear phase flows into a nuclear phase capillary tube in the micro-fluid controller under the pushing of a syringe pump, and when the nuclear phase liquid flows out from an outflow port of the capillary tube, the viscous force of the flowing shell phase and the surface tension interaction between the liquid result in the shearing of the nuclear phase liquid into liquid drops at the outflow port; at the outflow port of the shell phase capillary, the shell phase solution containing spherical core phase droplets forms uniform core-shell droplets under the shearing action of the continuous phase solution, and the core-shell droplets are solidified in hot silicone oil at 90 ℃.
In order to further illustrate the present invention, the following examples are provided to illustrate the preparation of a core-shell structure nuclear fuel microsphere according to the present invention, but they should not be construed as limiting the scope of the present invention.
Example 1
3.74g of deionized water and 3.57g of uranyl nitrate are taken and uniformly mixed by a magnetic stirrer, and the mixture is placed into a refrigerator to be cooled to 5 ℃ to prepare a nuclear phase solution A.
2.75g of deionized water, 2g of hexamethylenetetramine and 0.86g of urea are taken and uniformly mixed by a magnetic stirrer, and the mixture is placed into a refrigerator to be cooled to 5 ℃ to prepare a nuclear phase solution B.
Taking the cooled nuclear phase solution A and the cooled nuclear phase solution B with equal volumes, and uniformly mixing the solution A and the solution B through a magnetic stirrer to prepare the nuclear phase solution.
1.49g of zirconium nitride, 8.41g of tripropylene glycol diacrylate (TPGDA) and 0.1g of Azobisisobutyronitrile (AIBN) were ground by a planetary ball mill for 48 hours at a rotational speed of 200 revolutions to prepare a shell phase solution.
Dimethyl silicone oil is taken as a continuous phase solution.
9.5g of toluene and 0.5g of azobisisobutyronitrile were uniformly mixed by a magnetic stirrer to prepare a solution C.
10g of solution C and 90g of simethicone are taken and evenly mixed by a magnetic stirrer to prepare a coagulating bath solution.
The core phase, shell phase and continuous phase solutions were filled into 1ml, 1ml and 20ml syringes, respectively, and placed on the corresponding syringe pumps, and connected to a microfluidic device. The flow rate of the core phase solution was set to 4. Mu.l/m, the flow rate of the shell phase solution was set to 5. Mu.l/m, and the flow rate of the continuous phase solution was set to 120. Mu.l/m. The size of the nuclear phase capillary is: the inner/outer diameter was 100 μm/163 μm, and the shell phase capillary size was: an inner/outer diameter of 255 μm/510 μm; the nuclear phase conduit, the shell phase conduit and the continuous phase conduit have the same size, the outer diameter is 1600 mu m, and the inner diameter is 800 mu m; the output catheter size was: the inner diameter is 1600 μm and the outer diameter is 3200 μm. And (3) starting a cooling box, reducing the temperature in the box to 5 ℃, starting a microfluidic device, preparing core-shell structure liquid drops, and solidifying the generated core-shell liquid drops in a coagulating bath solution. Collecting the solidified microsphere, cleaning silicone oil on the surface of the microsphere by using kerosene, cleaning residual kerosene by using petroleum ether, and naturally air-drying to obtain core (U) 3 O 8 ) -shell (ZrN) structured nuclear fuel gel microspheres. The morphology was observed under a microscope and photographed as shown in fig. 1. As can be seen, the core (U 3 O 8 ) -shell (ZrN) structured nuclear fuel gel microspheres with particle size range 625-681 μm and dispersion coefficient CV of 3.1%.
Taking the core (U) 3 O 8 ) -shell (ZrN) structured nuclear fuel gel microspheresPlacing into a sintering furnace, and calcining at high temperature to remove residual water and organic matters in the microspheres. Calcining adopts programmed heating, and under inert atmosphere, heating to 150 ℃ at a heating rate of 5 ℃/min, and staying for 2 hours; then heating to 400 ℃ at a heating rate of 2 ℃/min, and staying for 2 hours; heating to 800 deg.C at a heating rate of 5 deg.C/min, and maintaining for 5 hr to obtain core (U) 3 O 8 ) -shell (ZrN) structured nuclear fuel microspheres. The morphology was observed under a microscope and photographed as shown in fig. 2. As can be seen, the core (U 3 O 8 ) -shell (ZrN) structured nuclear fuel microspheres with a particle size range of 413-489 μm and a dispersion coefficient CV of 3.3%. The microspheres are destroyed, the internal morphology structure and elemental analysis are observed under an electron microscope, and the microspheres are photographed, as shown in fig. 3 to 5, the shell layer mainly comprises zirconium and nitrogen elements, and the core mainly comprises uranium and oxygen elements.
As shown in fig. 6, 7 and 8, the microfluidic control device used in the preparation method comprises a nuclear phase injection pump 8, a shell phase injection pump 6, a continuous phase injection pump 7, and a nuclear phase injector 5, a shell phase injector 1 and a continuous phase injector 3 which are correspondingly arranged; a T-shaped tee 10, a T-shaped tee 12, a recovery container 14, a water bath 15 and a cooling box 21;
the shell phase injector 1 is communicated with a first port of the nail T-shaped tee 10 through a shell phase conduit 2; the shell phase capillary tube 19 is inserted into the output conduit 13 through a second port of the T-shaped tee; the continuous phase injector 3 is communicated with a first section port of the T-shaped tee 12 through a continuous phase conduit 4; the output port of the output conduit 13 is provided with a recovery container 15 which is arranged in the water bath 14.
The three ports of the T-shaped tee 10 and the T-shaped tee 12 are internally provided with internal threads, and the nuclear phase conduit 9, the shell phase conduit 2, the continuous phase conduit 4 and the output conduit 13 are provided with external threads matched with the internal threads.
The interface of the core-phase capillary tube 16 and the third port of the tee 10, the interface of the shell-phase capillary tube 19 and the second port of the tee 10 and the interface of the core-phase capillary tube 16 and the third port of the shell-phase capillary tube 19 and the tee are respectively provided with a sealing sleeve 18 for sealing, and the sealing sleeves 18 are in threaded connection with the corresponding tee and tee.
The outer side of one end of the sealing sleeve 18 connected with the two T-shaped tee joints is provided with external threads matched with the internal threads of the T-shaped tee joints; the 2 bottom surfaces of the sealing sleeve 18 are sealing surfaces with through holes, the 2 through holes are on the same axis, and the corresponding capillaries are inserted into the corresponding positions through the corresponding through holes.
As can be seen from the above examples, the present invention provides a method for preparing a nuclear fuel microsphere with a core-shell structure, comprising the following steps: forming core-shell structure droplets by the shell solution wrapped with the core-phase droplets under the shearing action of the continuous phase solution; solidifying and calcining the core-shell structure liquid drops to obtain U 3 O 8 The core-shell structure nuclear fuel microsphere is core and ZrN is shell. The method provided by the invention successfully prepares the nuclear fuel microsphere with the core-shell structure; the core phase of the core is U 3 O 8 The shell phase is ZrN, the structure is stable, and the size is uniform; compared with the traditional dispersion type nuclear fuel, the U prepared by the fuel microsphere prepared by the invention 3 O 8 ZrN dispersed nuclear fuel can realize U as fuel 3 O 8 Uniformly distributed in ZrN as matrix, and can increase the ratio of fuel phase in dispersed fuel.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (8)

1. The preparation method of the nuclear fuel microsphere with the core-shell structure comprises the following steps:
forming core-shell structure droplets by the shell solution wrapped with the core-phase droplets under the shearing action of the continuous phase solution;
solidifying and calcining the core-shell structure liquid drops to obtain U 3 O 8 The core-shell structure nuclear fuel microsphere is core and ZrN is shell.
2. The preparation method according to claim 1, wherein the core phase solution comprises a core phase solution a and a core phase solution B, and the core phase solution a is a mixture of (3.55-6.30): (3.72-3.76) a mixture of uranyl nitrate and water; the nuclear phase solution B is prepared from the following components in percentage by mass: (0.84-0.88): (2.73-2.78), a mixture of hexamethylenetetramine, urea and water.
3. The method of claim 1, wherein the shell phase solution is a suspension mixture of zirconium nitride powder, propylene glycol diacrylate and azobisisobutyronitrile.
4. The preparation method according to claim 3, wherein the mass ratio of the zirconium nitride powder, the propylene glycol diacrylate and the azobisisobutyronitrile is (18-22): (79-79.5): (0.78-0.82).
5. The method of claim 1, wherein the continuous phase solution is simethicone.
6. The method of preparation according to claim 1, wherein the curing is performed in a coagulation bath solution;
the coagulating bath solution is a mixture of simethicone, toluene and azodiisobutyronitrile; the mass ratio of the simethicone to the toluene to the azodiisobutyronitrile is 90: (9.2-9.7): (0.3-0.8).
7. The preparation method according to claim 1, wherein the curing temperature is 88-93 ℃ and the reaction time is 110-130 min.
8. The method of claim 1, wherein the calcining is conducted using a temperature programmed process;
the calcination specifically comprises: heating to 145-155 ℃ at a heating rate of 4.5-5.5 ℃/min under inert atmosphere, and staying for 1.5-2.5 hours; then heating to 390-410 ℃ at a heating rate of 1.5-2.5 ℃/min, and staying for 1.5-2.5 hours; then the temperature is increased by 4.5 to 5.5 ℃/minHeating to 780-820 deg.C at a temperature rate for 4.5-5.5 hr to obtain U 3 O 8 The core-shell structure nuclear fuel microsphere is core and ZrN is shell.
CN202310248169.8A 2023-03-10 2023-03-10 Preparation method of nuclear fuel microsphere with core-shell structure Pending CN116525164A (en)

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