Nuclear fuel rod, nuclear reactor and preparation method

Abstract

The invention discloses a nuclear fuel rod, a nuclear reactor and a preparation method, the nuclear fuel rod comprises a reactor core, the nuclear fuel rod comprises at least one nuclear fuel rod assembly, each nuclear fuel rod assembly comprises a metal tube, the inner wall of the metal tube is provided with a fuel coating, the two ends of the metal tube are provided with vacuum plugging heads, and the metal tube is provided with a metal coating. A fixing piece is arranged on the outer side of the vacuum plugging head, and the nuclear fuel rod assembly is installed in the reactor core through the fixing piece. The reactor is good in heat dissipation performance, high in mechanical strength, not prone to deformation and breakage, capable of bearing external high pressure, high in nuclear reaction efficiency, less in nuclear fuel and small in heat capacity, heat is quickly dissipated after shutdown, troubles caused by heat accumulation are prevented, a space is reserved for proliferation, and thermal neutrons can collide with uranium 238 and thorium 232 in vacuum for multiple times and proliferate into nuclear fuel.

Description

Technical Field

[0001] The invention relates to a nuclear fuel rod, a nuclear reactor and a preparation method thereof. Background Art

[0002] Nuclear reactors are used to control and maintain nuclear fission chain reactions to generate energy. Nuclear fission is the process by which an atomic nucleus splits after absorbing a neutron, releasing energy, more neutrons, and radiation. Nuclear reactors can be used for purposes such as power generation, research, and the manufacture of nuclear weapons materials.

[0003] Modern reactor fuel rods have three structures: cylindrical, flat, and spherical.

[0004] Cylindrical nuclear fuel: UO2 is made into a cylindrical solid and loaded into a zirconium alloy cladding, leaving gaps at both ends, filled with 3Mpa helium, and welded and sealed at both ends to form a fuel rod, such as a pressurized water reactor fuel rod, which is 3.3m long. The zirconium alloy tube has an outer diameter of 10mm and a wall thickness of 0.7mm. The inner diameter is 8.6mm, and the cylindrical fuel inside is 8.4mm, and the length is 13mm. Pressurized water reactors, boiling water reactors, and heavy water reactors all use cylindrical solid bodies, and the cladding diameters vary, and the lengths are also different.

[0005] Flat fuel, cladding material 1Cr18Ni9Ti, cladding thickness 1.5mm, UO2 made with a thickness of 1mm, uranium enrichment of 10%, used in marine reactors.

[0006] Spherical fuel, used in high gas-cooled reactors, is made of 10% enriched UO2 with a diameter of 0.6mm, and coated with three to four layers of pyrolytic carbon and silicon carbide (SiC) coating. The innermost layer of the particle is a loose layer, which is used to provide storage space for gas fission products and buffer humidity stress. The diameter of the particle is close to 1mm. 12,000 particles are placed in a graphite ball with a diameter of 60mm to become a fuel ball, which is used in the gas-cooled reactor designed by Tsinghua University.

[0007] All of the above fuel rods have disadvantages. The cylindrical shape has poor heat dissipation and no proliferation space. The gas produced by the flat-plate fuel has nowhere to be stored and has no proliferation space. The spherical structure has complex processing and the heat dissipation is greatly affected by the loose layer. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the defects of nuclear fuel rods in the prior art, such as poor heat dissipation, no proliferation space, nowhere to store the generated gas, complex structure and process, and great influence of heat dissipation on the loose layer. The present invention provides a nuclear fuel rod, a nuclear reactor and a preparation method with good heat dissipation, high mechanical strength, not easy to deform and crack, able to withstand high external pressure and high nuclear reaction efficiency.

[0009] The present invention solves the above technical problems through the following technical solutions:

[0010] A nuclear fuel rod is used in a nuclear reactor, and the nuclear reactor includes a core. The nuclear fuel rod includes at least one nuclear fuel rod assembly, and each nuclear fuel rod assembly includes a metal tube. The inner wall of the metal tube is provided with a fuel coating, and vacuum sealing heads are provided at both ends of the metal tube. The outer side of the vacuum sealing head is provided with a fixing part, and the nuclear fuel rod assembly is installed inside the core using the fixing part.

[0011] Preferably, the fuel coating is prepared using UO2 powder, water and a binder.

[0012] Preferably, the metal tube is cylindrical in shape, the outer diameter of the metal tube is 7 mm to 15 mm, the wall thickness of the metal tube is 0.5 mm to 1.2 mm, and the thickness of the fuel coating is 0.4 mm to 0.9 mm.

[0013] Preferably, the two fixing members in a nuclear fuel rod assembly are respectively a fixing bolt and a fixing nut, and the fixing bolt and the fixing nut are respectively connected to the vacuum sealing head.

[0014] Preferably, the core includes an upper core plate arranged at the top and a lower core plate arranged at the bottom, the nuclear fuel rod assembly at the top is connected to the upper core plate by fixings, adjacent nuclear fuel rod assemblies are connected by fixings, and the nuclear fuel rod assembly at the bottom is connected to the lower core plate by fixings.

[0015] Preferably, the vacuum sealing head and the fixing member are integrally formed, and the length of the nuclear fuel rod assemblies is the same and is 0.8 m to 1.5 m.

[0016] Preferably, the core includes a plurality of control chain mounting holes and a core shell, the nuclear reactor includes a control chain device, the control chain device includes a plurality of control chains, a driving wheel and a driving motor, each control chain includes a mounting rope and a plurality of absorbers of preset lengths,

[0017] The absorbers are all arranged outside the installation ropes, and the driving wheels are arranged above the core through supporting members;

[0018] One end of the control chain is aligned with a control chain mounting hole, and the other end of the control chain is arranged between the core shell and the nuclear reactor shell;

[0019] The driving motor drives the driving wheel to rotate, and the driving wheel drives the control chain to reciprocate.

[0020] Preferably, the absorber is in the shape of a capsule, the drive wheel is a gear, the tooth surface shape of the gear matches the shape of the absorber, a first guide cylinder is provided above the control chain mounting hole, a second guide cylinder is provided between the core shell and the nuclear reactor shell, and the drive wheel drives the control chain to reciprocate in the first guide cylinder and the second guide cylinder.

[0021] A nuclear fuel rod securing member is provided between the core upper plate and the core lower plate, and the nuclear fuel rod securing member is used for radially positioning the nuclear fuel rod.

[0022] The present invention also provides a nuclear reactor, characterized in that the nuclear reactor comprises the nuclear fuel rods as described above.

[0023] The present invention also provides a preparation method, characterized in that the preparation method is used to prepare the nuclear fuel rod as described above, and the preparation method comprises:

[0024] The UO2 powder is mixed with water and a binder to obtain a blending agent;

[0025] Evenly apply the blending agent on the inner wall of the metal pipe;

[0026] Heating and drying the metal tube to obtain a fuel metal tube;

[0027] After vacuum treatment is performed inside the fuel metal pipe, a vacuum plugging head is installed.

[0028] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0029] The positive and progressive effects of the present invention are:

[0030] The present invention has good heat dissipation, high mechanical strength, is not easy to deform and break, can withstand high external pressure, has high nuclear reaction efficiency, uses less nuclear fuel, has small heat capacity, and quickly dissipates heat after shutdown, preventing troubles caused by heat accumulation and leaving space for proliferation. Thermal neutrons can collide with uranium 238 and thorium 232 multiple times in a vacuum and proliferate into nuclear fuel, providing a technical basis for the miniaturization of nuclear reactors and making micro reactors possible.

[0031] Specifically, the positive progress effect lies in

[0032] 1. Good heat dissipation.

[0033] 2. High mechanical strength, not easy to deform and break, and can withstand high external pressure.

[0034] 3. The nuclear fuel is small and the heat capacity is small. After the reactor is shut down, the heat dissipates quickly to prevent the trouble caused by heat accumulation.

[0035] 4. Leave room for proliferation. Thermal neutrons can collide with uranium 238 and thorium 232 multiple times in a vacuum and proliferate into nuclear fuel.

[0036] 5. To achieve the goal of using uranium 238 and thorium 232 (realized in one reactor).

[0037] 6. In general, the center of a breeder fast reactor is the reaction zone, and the surrounding is the breeding zone. In the structure of a sodium-cooled fast reactor, the breeder fuel must be taken out, processed, and then put into the reactor. The present invention can directly utilize uranium 238 and thorium 232, saving time and cost.

[0038] 7. Nuclear safety is fully guaranteed.

[0039] 8. Make full use of the fuel rods after the reaction. There is no need to bury them deeply. They can be used as radioactive sources, such as rod-shaped nuclear batteries and radioactive nuclear batteries. They are covered with lead pipes to prevent the emission of radiation, and are very safe to use.

[0040] 9. The manufacturing process is simple, the cost is low, and it is conducive to promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the structure of the nuclear fuel rod of Invention Example 1.

[0042] Figure 2 This is a schematic diagram of the structure of the nuclear reactor of embodiment 1 of the invention.

[0043] Figure 3 Another structural schematic diagram of the nuclear reactor of embodiment 1 of the invention.

[0044] Figure 4 This is a schematic structural diagram of a control chain device according to Embodiment 1 of the invention.

[0045] Figure 5 This is a schematic diagram of the structure of the control chain of embodiment 1 of the invention.

[0046] Figure 6 This is a schematic diagram of the top view of the core structure of embodiment 1 of the invention.

[0047] Figure 7 This is a schematic diagram of the structure of the neutron source core block of Invention Example 1.

[0048] Figure 8 Another schematic diagram of the structure of the neutron source core block of Invention Example 1.

[0049] Fig. 9 This is a schematic structural diagram of a control chain device according to Embodiment 1 of the invention.

[0050] Fig.10 This is a schematic diagram of the structure of the guide tube of embodiment 1 of the invention. DETAILED DESCRIPTION

[0051] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0052] Example 1

[0053] In this embodiment, the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0054] See also Figures 1 to 10 , this embodiment provides a nuclear reactor.

[0055] The nuclear reactor comprises a core 11 .

[0056] The nuclear fuel rod comprises at least one nuclear fuel rod assembly 41 . Each nuclear fuel rod assembly comprises a metal tube 411 . The inner wall of the metal tube is provided with a fuel coating 412 .

[0057] Vacuum sealing heads 413 are provided at both ends of the metal tube, and fixing pieces are provided on the outside of the vacuum sealing heads. The nuclear fuel rod assembly 41 is installed inside the core by using the fixing pieces.

[0058] The fuel coating is prepared by using UO2 powder, water and a binder.

[0059] The metal tube is cylindrical in shape.

[0060] The outer diameter of the metal tube is 7 mm to 15 mm, the wall thickness of the metal tube is 0.5 mm to 1.2 mm, and the thickness of the fuel coating is 0.4 mm to 0.9 mm.

[0061] In this embodiment, the outer diameter of the metal tube is preferably 10 mm, the wall thickness is 0.7 mm, and the thickness of the fuel coating is 0.6 mm.

[0062] The two fixing parts in a nuclear fuel rod assembly are a fixing bolt 4141 and a fixing nut 4142, and the fixing bolt 4141 and the fixing nut 4142 are connected to the vacuum sealing head respectively.

[0063] The above structure can connect the nuclear fuel rod assemblies to each other, and can also fix the fuel rod assemblies in the core.

[0064] The core includes an upper core plate 14 disposed at the top and a lower core plate disposed at the bottom.

[0065] The nuclear fuel rod assembly at the top is connected to the upper plate of the core through fixings, and adjacent nuclear fuel rod assemblies are connected through fixings.

[0066] A nuclear fuel rod securing member is provided between the core upper plate and the core lower plate, and the nuclear fuel rod securing member is used for radially positioning the nuclear fuel rod.

[0067] In this embodiment, the nuclear fuel rod fixing member is a horizontal plate, which is provided with a fixing hole matching the outer diameter of the nuclear fuel rod. The nuclear fuel rod is inserted into the fixing hole to prevent radial shaking of the nuclear fuel rod. In addition, the horizontal plate is also provided with a water hole, which is used to conduct water channels above and below the horizontal plate to maintain the thermal balance of the core.

[0068] The nuclear fuel rod assembly at the bottom is connected to the lower plate of the core through fixings.

[0069] The vacuum plugging head and the fixing piece are integrally formed, the length of the nuclear fuel rod assembly is the same and is 1000 mm, and the overall length of the vacuum plugging head and the fixing piece is 8 mm.

[0070] The core 11 further includes a plurality of control chain mounting holes 111 and a core shell 112 , and each control chain mounting hole 111 is correspondingly mounted with a control chain.

[0071] The nuclear reactor includes a control chain device 21 , which includes a plurality of control chains 211 , a driving wheel 212 and a driving motor 213 .

[0072] Each control chain 211 includes a mounting rope 214 and a plurality of absorbers 215 of a predetermined length. In this embodiment, the number of the control chain and the number of the control chain mounting holes are both 6.

[0073] The absorbers 215 are all arranged outside the installation ropes 214 , and the driving wheels 212 are arranged above the core through the support members 216 .

[0074] One end of the control chain 211 is aligned with a control chain mounting hole 111 , and the other end of the control chain 211 is disposed between the core shell 112 and the nuclear reactor shell 113 .

[0075] The driving motor 213 drives the driving wheel 212 to rotate, and the driving wheel 212 drives the control chain 211 to reciprocate.

[0076] The material of the absorber is cadmium indium silver alloy, the outside of the absorber is provided with a stainless steel shell 218, and the installation rope 214 is a steel wire rope. The cadmium indium silver content of the absorber is 5%, 15%, and 80% respectively.

[0077] The absorbent body is in a capsule shape, the driving wheel is a gear, and the tooth surface shape of the gear matches the shape of the absorbent body.

[0078] A spacer 217 is provided between two adjacent absorbent bodies.

[0079] A first guide cylinder 31 is provided above the control chain installation hole, a second guide cylinder 32 is provided between the core shell 112 and the nuclear reactor shell 113, and the driving wheel 212 drives the control chain to reciprocate in the first guide cylinder and the second guide cylinder.

[0080] The first guide cylinder and the second guide cylinder are integrally formed, a connecting guide cylinder 33 is provided between the first guide cylinder and the second guide cylinder, a control window 34 is provided at the bottom of the connecting guide cylinder, the driving wheel passes through the control window and engages with the control chain, and the second guide cylinder is fixed to the inner side of the nuclear reactor shell.

[0081] The control chain device also includes guide wheels 35, each of which corresponds to a driving wheel, and the guide wheels are arranged on the inner side of the driving wheel or the driving wheel is arranged on the inner side of the guide wheels. In the present embodiment, the driving wheel is arranged on the inner side of the guide wheels.

[0082] Each control chain installation hole in the core corresponds to a control chain installation hole in the same group, and the control chain installation holes and the control chain installation holes in the same group are axially symmetrical.

[0083] The control chain device 21 includes a connecting rod 219, both ends of which are connected to two driving wheels respectively. The control chains driven by the two driving wheels connected to the same connecting rod are installed in the same group of control chain installation holes, and the connecting rod is connected to the driving motor through a gear.

[0084] This embodiment also provides a preparation method, which is used to prepare the nuclear fuel rod, and the preparation method comprises:

[0085] The UO2 powder is mixed with water and a binder to obtain a blending agent;

[0086] Evenly apply the blending agent on the inner wall of the metal pipe;

[0087] Heating and drying the metal tube to obtain a fuel metal tube;

[0088] After vacuum treatment is performed inside the fuel metal pipe, a vacuum plugging head is installed.

[0089] Using the above-mentioned nuclear reactor and control chain device, this embodiment further provides a control method, including:

[0090] Neutron irradiation activation of the antimony core;

[0091] Install the antimony core in the beryllium sleeve;

[0092] Install the beryllium sleeve containing the antimony core into the neutron source installation hole;

[0093] Get the core temperature;

[0094] The driving motor is controlled according to the core temperature to adjust the number and depth of the control chain entering the control chain installation hole.

[0095] The core further includes a neutron source installation hole 12 .

[0096] The ignition neutron source device includes a neutron source core block 13 , and the neutron source core block includes an antimony core 131 and a beryllium sleeve 132 .

[0097] The antimony core is arranged in the beryllium sleeve, and the neutron source core block is used to be installed in the neutron source installation hole.

[0098] The antimony core and the beryllium sleeve are both cylindrical, the diameter of the antimony core is 1 mm to 2 mm, the inner diameter of the beryllium sleeve matches the diameter of the antimony core, and the wall thickness of the beryllium sleeve is 0.5 mm to 2 mm.

[0099] The antimony core and the beryllium sleeve have the same length, and the length of the beryllium sleeve is 15 mm to 40 mm.

[0100] Specifically, the control method includes:

[0101] Neutron irradiation activation of the antimony core;

[0102] Install the antimony core in the beryllium sleeve;

[0103] Installing a fixing member above the beryllium sleeve;

[0104] Pulling the pulling chain to place the beryllium sleeve equipped with the antimony core into the sub-source guide cylinder;

[0105] The beryllium sleeve is placed in the neutron source installation hole along the neutron source guide tube by using the traction chain.

[0106] Get the core temperature;

[0107] The driving motor is controlled according to the core temperature to adjust the number and depth of the control chain entering the control chain installation hole.

[0108] Nuclear reactors have a large number of neutron sources for ignition, but they cannot use radium-beryllium sources, polonium-beryllium sources, and certainly not californium sources.

[0109] This embodiment designs an antimony-beryllium source.

[0110] Antimony is abundant, easily available, and cheap.

[0111] Antimony is made into a wire with a diameter of 1.5 mm (preferably), and a section is activated by neutron irradiation.

[0112] Antimony release ray, When the radiation hits beryllium, neutrons are produced.

[0113] ,

[0114] .

[0115] Beryllium is made into a sleeve and put on the antimony wire. After activation, it produces neutrons with higher efficiency than the mixture.

[0116] An absorption shell 17 with a length greater than or equal to the length of the beryllium sleeve is disposed outside the beryllium sleeve, and the absorption shell is made of cadmium indium silver alloy.

[0117] The cadmium, indium and silver contents of the absorption shell are 5%, 15% and 80% respectively.

[0118] A core upper plate 14 is provided on the top of the core 11, a neutron source guide tube 15 is provided above the core upper plate, a guide tube fixing plate 16 is provided on the top of the neutron source guide tube, the absorption shell 17 is installed above the guide tube fixing plate, and the absorption shell, the neutron source guide tube and the neutron source installation hole are located on the same axis.

[0119] The ignition neutron source device includes a fixing part 18 and a traction chain 19. The fixing part fixes the antimony core and the beryllium sleeve from the top. The traction chain is connected to the fixing part and is used to place the antimony core and the beryllium sleeve along the neutron source guide tube into the neutron source installation hole.

[0120] A support plate 20 is provided at the bottom of the beryllium sleeve, an external thread is provided at the top of the beryllium sleeve, an internal thread matching the external thread is provided at the bottom of the fixing part, and a connecting part connected to the traction chain is provided at the top, and the fixing part is made of beryllium.

[0121] Although the specific embodiments of the present invention are described above, those skilled in the art should understand that these are only examples, and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A nuclear fuel rod for a nuclear reactor, the nuclear reactor comprising a core, characterized in that: The nuclear fuel rod includes at least one nuclear fuel rod assembly, each nuclear fuel rod assembly includes a metal tube, the inner wall of the metal tube is provided with a fuel coating, both ends of the metal tube are provided with vacuum sealing heads, the outer side of the vacuum sealing head is provided with fixings, and the nuclear fuel rod assembly is installed inside the core using the fixings.

2. The nuclear fuel rod according to claim 1, characterized in that: The fuel coating is prepared by using UO2 powder, water and a binder.

3. The nuclear fuel rod according to claim 1, characterized in that: The metal tube is cylindrical in shape, the outer diameter of the metal tube is 7 mm to 15 mm, the wall thickness of the metal tube is 0.5 mm to 1.2 mm, and the thickness of the fuel coating is 0.4 mm to 0.9 mm.

4. The nuclear fuel rod according to claim 1, characterized in that: The two fixing parts in a nuclear fuel rod assembly are respectively a fixing bolt and a fixing nut, and the fixing bolt and the fixing nut are respectively connected to the vacuum sealing head.

5. The nuclear fuel rod according to claim 4, characterized in that: The core comprises an upper core plate arranged at the top and a lower core plate arranged at the bottom. The nuclear fuel rod assembly at the top is connected to the upper core plate via fixings, adjacent nuclear fuel rod assemblies are connected via fixings, and the nuclear fuel rod assembly at the bottom is connected to the lower core plate via fixings.

6. The nuclear fuel rod according to claim 1, characterized in that: The vacuum plugging head and the fixing member are integrally formed, and the length of the nuclear fuel rod assembly is the same and the length is 0.8m to 1.5m; and / or, A nuclear fuel rod securing member is provided between the core upper plate and the core lower plate, and the nuclear fuel rod securing member is used for radially positioning the nuclear fuel rod.

7. The nuclear fuel rod according to claim 1, characterized in that: The core includes a plurality of control chain mounting holes and a core shell, the nuclear reactor includes a control chain device, the control chain device includes a plurality of control chains, a driving wheel and a driving motor, each control chain includes a mounting rope and a plurality of absorbers of preset lengths, The absorbers are all arranged outside the installation ropes, and the driving wheels are arranged above the core through supporting members; One end of the control chain is aligned with a control chain mounting hole, and the other end of the control chain is arranged between the core shell and the nuclear reactor shell; The driving motor drives the driving wheel to rotate, and the driving wheel drives the control chain to reciprocate.

8. The nuclear fuel rod according to claim 7, characterized in that: The absorber is in the shape of a capsule, the drive wheel is a gear, the tooth surface shape of the gear matches the shape of the absorber, a first guide cylinder is provided above the control chain mounting hole, a second guide cylinder is provided between the core shell and the nuclear reactor shell, and the drive wheel drives the control chain to reciprocate in the first guide cylinder and the second guide cylinder.

9. A nuclear reactor, characterized in that: The nuclear reactor comprises the nuclear fuel rod according to any one of claims 1 to 8.

10. A preparation method, characterized in that: The preparation method is used to prepare the nuclear fuel rod according to any one of claims 1 to 8, and the preparation method comprises: The UO2 powder is mixed with water and a binder to obtain a blending agent; Evenly apply the blending agent on the inner wall of the metal pipe; Heating and drying the metal tube to obtain a fuel metal tube; After vacuum treatment is performed inside the fuel metal pipe, a vacuum plugging head is installed.

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