Nuclear reactor shutdown system

Abstract

The application discloses a nuclear reactor shutdown system, which comprises a first shutdown mechanism and a second shutdown mechanism. The second shutdown mechanism comprises a driving part, a supporting part, a storage part, a guiding part and a moving part. The supporting part is arranged outside a reactor core, the guiding part is arranged in the reactor core, the supporting part and the guiding part are provided with a moving channel which is communicated with each other, the moving part is slidably arranged in the moving channel, the driving part and the storage part are arranged on the supporting part, the driving part is used for driving the moving part to extend into or out of the guiding part along the moving channel, the storage part is provided with an inlet and an outlet, the storage part is provided with a storage material for absorbing neutrons, the moving part is provided with a containing cavity for containing the storage material. When the nuclear reactor is operated, the driving part drives the moving part to extend into the guiding part along the moving channel, and the bottom of the containing cavity is located below an active region of the reactor core. When the nuclear reactor is shut down, the outlet is opened, the storage material falls into the moving part, and the storage material is located below the active region of the reactor core.

Description

Technical Field

[0001] This invention relates to the field of nuclear reactor technology, and in particular to a nuclear reactor shutdown system. Background Technology

[0002] Nuclear energy, as a low-carbon, high-energy-density energy source, has always been developed and utilized with "safety and efficiency" as its core objectives. With the expansion of global nuclear power generation, nuclear safety has received increasing attention. Reactors may face various emergencies during operation, such as equipment failures and external disasters. To ensure the safety of personnel and the environment, a reliable shutdown system is needed to quickly stop the nuclear reaction.

[0003] As nuclear reactor technology has evolved, shutdown systems have progressed from simple control rod designs to complex safety systems incorporating multiple shutdown methods and redundancy. Control rod shutdown is the most common shutdown method. Control rods are typically made of materials with strong neutron absorption capabilities, such as boron and cadmium. Controlled by a top-mounted drive mechanism, they are inserted into or removed from the core as needed during normal operation to regulate neutron flux and reactor power. In an emergency shutdown, the drive mechanism loses power, and the control rods, under their own weight, rapidly insert into the core, absorbing a large number of neutrons and quickly terminating the nuclear reaction. Because of the critical safety implications for nuclear reactors, shutdown systems must possess high reliability. Control rod shutdown carries the risk of rod jamming; therefore, most reactors employ two shutdown systems with different mechanisms. In existing pressurized water reactors, chemical shutdown is typically used as the second system, achieved by injecting substances containing neutron absorbers into the reactor. Existing boiling water reactors, on the other hand, use boric acid solution injected into the core to assist in shutdown, addressing extreme conditions such as control rod failure.

[0004] Thorium-based molten salt reactors use liquid molten salt as nuclear fuel. Their fuel system is characterized by high fluidity, homogeneous composition, and the need for long-term recycling. If chemical shutdown is used as a redundant shutdown system for this type of reactor, neutron absorbers such as boric acid must be injected into the liquid fuel. Once added, these substances irreversibly mix with the molten salt fuel, making separation and purification difficult through simple processes, resulting in permanent contamination of the fuel system. Furthermore, they disrupt the original nuclide composition and reactivity of the fuel, rendering large amounts of unburned thorium, uranium, and other nuclear fuel unusable for further chain reactions, leading to significant fuel waste and a substantial increase in the technical difficulty and cost of subsequent fuel reprocessing. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art in chemical shutdown, which wastes nuclear fuel and has high costs and difficulties in the subsequent fuel treatment. The present invention provides a nuclear reactor shutdown system.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution:

[0007] A nuclear reactor shutdown system is provided on a nuclear reactor. The nuclear reactor shutdown system includes a first shutdown mechanism, which includes control rods for inserting or removing the reactor core. The nuclear reactor shutdown system further includes:

[0008] The second shutdown mechanism includes a drive unit, a support unit, a storage unit, a guide unit, and a moving unit. The support unit is located outside the reactor core, and the guide unit is inserted inside the reactor core. The support unit and the guide unit have interconnected movement channels, and the moving unit slides within these channels. The drive unit and the storage unit are mounted on the support unit. The drive unit drives the moving unit to extend into or out of the guide unit along the movement channels. The storage unit has an inlet and an outlet, both connected to the movement channels. The storage unit contains neutron-absorbing material, and the moving unit has a receiving cavity for accommodating the neutron-absorbing material. When the nuclear reactor is running, the drive unit drives the moving unit to extend into the guide unit along the movement channels, with the bottom of the receiving cavity located below the active zone of the reactor core. When the nuclear reactor is shut down, the outlet opens, and the neutron-absorbing material falls into the moving unit, located below the active zone of the reactor core.

[0009] When the nuclear reactor is restarted, the discharge port is closed and the inlet is opened. The moving part drives the stored material to extend out of the guide part along the moving channel and the receiving cavity is connected to the inlet. The stored material falls back into the storage part.

[0010] In this scheme, a driving section, a supporting section, a storage section, a guiding section, and a moving section are incorporated. The moving section extends into or out of the guiding section, allowing the neutron-absorbing fuel to fall into the moving section or back into the storage section. When the fuel falls into the moving section and extends into the guiding section, it absorbs neutrons from the active zone of the reactor core, achieving a safe shutdown. When the moving section extends out of the guiding section, the fuel falls back into the storage section. Compared to chemical shutdown, which requires injecting absorbent into the molten salt fuel in the core and causing irreversible mixing, the fuel is isolated from the molten salt fuel by the guiding section, preventing mixing. Furthermore, the moving section's movement allows the fuel to fall back into the storage section, effectively separating it from the molten salt fuel. This ensures that when the reactor needs to be restarted, the nuclide ratio and reactivity of the molten salt fuel are maintained, allowing large amounts of unburned thorium, uranium, and other nuclear fuels to continue participating in the chain reaction, significantly saving fuel and greatly reducing the technical difficulty and cost of subsequent fuel processing during reactor restart.

[0011] In addition, compared to using insert bars or control bars to insert or remove the core for shutdown, the storage material can move and fall into the moving part or back into the storage part, thereby avoiding the jamming of insert bars or control bars that occur when the size of the insert bars or control bars moves in a limited space, and ensuring the reliability of shutdown.

[0012] Preferably, the drive unit includes a stepper motor, a drive wheel, and a drive chain. The stepper motor has a brake unit for power-off braking. The stepper motor is disposed at the end of the support unit away from the guide unit. The drive wheel passes through the output shaft of the stepper motor. The drive chain is wound around the drive wheel, and the stepper motor and the moving unit are connected through the drive chain.

[0013] In this scheme, the above-mentioned settings ensure that the output shaft of the stepper motor remains stationary under extreme conditions of reactor shutdown and power outage, thereby maintaining the position of the transmission chain and moving parts connected to the output shaft. The unchanged position of the moving parts allows the fuel stock to effectively cover the active zone of the reactor core, ensuring the reliability of the shutdown.

[0014] Preferably, the drive unit further includes a position measuring component and a limit switch. The position measuring component is disposed at the end of the output shaft of the stepper motor and rotates synchronously with the transmission wheel. The limit switch is disposed in the motion channel of the support unit and is disposed close to the stepper motor.

[0015] In this solution, the above-mentioned settings are used to detect the position of the moving part within the motion channel in real time, and to place the moving part in a suitable position within the motion channel based on feedback. Additionally, a limit switch is provided to offer a limit indication when the moving part approaches the stepper motor and moves upwards, preventing the moving part from exceeding its travel range and coming into contact with the drive unit, thus avoiding damage to the transmission chain.

[0016] Preferably, the storage section is connected to the movement channel of the support section through the inlet and the outlet, and the bottom of the storage section has a first slope, which is inclined toward the outlet.

[0017] And / or, the storage unit further includes a connecting pipe, through which the inlet and the outlet are connected to the movement channel of the support unit. The connecting pipe connected to the inlet is inclined toward the storage unit, and the connecting pipe connected to the outlet is inclined toward the support unit.

[0018] In this scheme, the above-mentioned settings enable the stored material to enter the moving part in a timely manner, avoiding the situation where the stored material accumulates in the storage part and cannot fall into the moving part in time, thus failing to enter the active area of ​​the reactor core.

[0019] Preferably, the moving part includes an end, a base, and a connecting rod. The two ends of the connecting rod are connected to the end and the base, respectively. At least three connecting rods are provided, and at least three connecting rods are spaced apart along the circumferential direction of the end and the base to form the receiving cavity. The gap between two adjacent connecting rods is larger than the size of the storage material.

[0020] In this solution, the above-mentioned arrangement allows the gap between two adjacent connecting rods to allow the stored material to fall into the receiving cavity, and the at least three connecting rods can improve the stability of the moving part.

[0021] Preferably, the gap between the end or the base and the inner wall of the motion channel is no greater than 2 ± 0.5 mm.

[0022] In this solution, the above-mentioned arrangement ensures that there is sufficient space between the moving part and the inner wall of the moving channel, while preventing the gap from being too large and causing the stored material to fall directly into the guide part without being able to follow the moving part out of the guide part.

[0023] Preferably, the base has a second slope that is inclined toward the feed inlet.

[0024] In this scheme, the above-mentioned settings enable the second slope to guide the stored material back into the feed inlet and storage section when the moving part extends the guide part during nuclear reactor restart.

[0025] Preferably, the inclination angle between the first slope and the second slope is not less than 60±5°;

[0026] And / or, the tilt angle of the connecting pipe is not less than 60±5°.

[0027] In this solution, by setting the above-mentioned angles of the first slope, the second slope, and the connecting pipe, the stored material can be effectively guided, thus avoiding the accumulation of stored material and poor flowability.

[0028] Preferably, an electromagnetic gate is provided at the discharge port. When the nuclear reactor is shut down, the electromagnetic gate is de-energized and the discharge port remains open. When the nuclear reactor is restarted, the electromagnetic gate is energized and the discharge port is closed.

[0029] In this solution, the above settings ensure that the stored material can fall into the moving part or fall back to the storage part.

[0030] Preferably, the first shutdown mechanism and the second shutdown mechanism are disposed at an interval on the nuclear reactor and are independent of each other.

[0031] In this scheme, the above settings are used to avoid interference between the first shutdown mechanism and the second shutdown mechanism, thus ensuring the independence and reliability of the shutdown process.

[0032] The positive and progressive effects of this invention are as follows: By incorporating a driving section, a supporting section, a storage section, a guiding section, and a moving section, and by having the moving section extend into or out of the guiding section, the neutron-absorbing fuel can fall into the moving section or back into the storage section. When the fuel falls into the moving section and the moving section extends into the guiding section, it can absorb neutrons in the active region of the reactor core, thus achieving a safe shutdown. When the moving section extends out of the guiding section, the fuel in the moving section can fall back into the storage section. Compared to chemical shutdown, which requires injecting absorbent into the molten salt fuel in the reactor core and causing irreversible mixing, the fuel is isolated from the molten salt fuel by the guiding section, preventing mixing. Furthermore, the movement of the moving section allows the fuel to fall back into the storage section, effectively separating it from the molten salt fuel. This ensures that when the nuclear reactor needs to be restarted, the nuclide ratio and reactivity of the molten salt fuel are maintained, allowing a large amount of unburned thorium, uranium, and other nuclear fuels to continue participating in the chain reaction, significantly saving fuel and greatly reducing the technical difficulty and cost of subsequent fuel processing during nuclear reactor restart.

[0033] In addition, compared to using insert bars or control bars to insert or remove the core for shutdown, the storage material can move and fall into the moving part or back into the storage part, thereby avoiding the jamming of insert bars or control bars that occur when the size of the insert bars or control bars moves in a limited space, and ensuring the reliability of shutdown. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a nuclear reactor according to a preferred embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram of the structure of the second shutdown mechanism according to a preferred embodiment of the present invention.

[0036] Figure 3 This is a schematic diagram of the drive unit according to a preferred embodiment of the present invention.

[0037] Figure 4 This is a perspective view of the moving part of a preferred embodiment of the present invention.

[0038] Figure 5 This is a schematic diagram of the structure of the moving part extending into the guide part when the nuclear reactor is shut down, according to a preferred embodiment of the present invention.

[0039] Figure 6 This is a schematic diagram of the structure of the nuclear reactor during shutdown when the fuel falls into the moving part, according to a preferred embodiment of the present invention.

[0040] Figure 7This is a schematic diagram of the structure of the fuel fall-off storage section during nuclear reactor restart according to a preferred embodiment of the present invention.

[0041] Figure 8 This is a schematic diagram of the structure of the moving part extending from the guide part during nuclear reactor restart according to a preferred embodiment of the present invention.

[0042] Figure 9 This is a diagram showing the positional relationship between the connecting pipe and the storage section in a preferred embodiment of the present invention.

[0043] Explanation of reference numerals in the attached figures:

[0044] Nuclear reactor 100

[0045] Core 101

[0046] First shutdown mechanism 1

[0047] Control stick 11

[0048] Second shutdown mechanism 2

[0049] Drive Unit 21

[0050] Stepper motor 211

[0051] Brake unit 2111

[0052] Drive wheel 212

[0053] Transmission chain 213

[0054] Position measurement component 214

[0055] Limit switch 215

[0056] Support section 22

[0057] Support plate 221

[0058] Storage Department 23

[0059] Inlet 231

[0060] Discharge port 232

[0061] First slope 233

[0062] Electromagnetic gate 234

[0063] Material level detection device 235

[0064] Connecting pipe 236

[0065] Guiding section 24

[0066] Sports Department 25

[0067] Reception cavity 251

[0068] End cap 252

[0069] Base 253

[0070] Second slope 2531

[0071] Connecting rod 254

[0072] Exercise Channel 26

[0073] Storage 27 Detailed Implementation

[0074] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0075] This embodiment provides a nuclear reactor shutdown system, the specific structure of which is as follows: Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 and Figure 9 As shown, a nuclear reactor shutdown system is installed on the nuclear reactor 100. The nuclear reactor shutdown system includes a first shutdown mechanism 1, which includes control rods 11 for inserting or removing the reactor core 101 of the nuclear reactor 100. The nuclear reactor shutdown system also includes:

[0076] The second shutdown mechanism 2 includes a drive unit 21, a support unit 22, a storage unit 23, a guide unit 24, and a moving unit 25. The support unit 22 is located outside the reactor core 101, and the guide unit 24 is inserted inside the reactor core 101. The support unit 22 and the guide unit 24 have interconnected movement channels 26. The moving unit 25 slides within the movement channels 26. The drive unit 21 and the storage unit 23 are mounted on the support unit 22. The drive unit 21 drives the moving unit 25 to extend into or out of the guide unit 24 along the movement channels 26. The storage unit 23 is provided with an inlet 231 and an outlet 23. 2. Both the feed port 231 and the discharge port 232 are connected to the motion channel 26. The storage section 23 is provided with a neutron-absorbing material 27. The motion section 25 is provided with a receiving cavity 251 for accommodating the neutron-absorbing material 27. When the nuclear reactor 100 is running, the drive section 21 drives the motion section 25 to extend into the guide section 24 along the motion channel 26, and the bottom of the receiving cavity 251 is located below the active zone of the reactor core 101. When the nuclear reactor 100 is shut down, the discharge port 232 is opened, and the neutron-absorbing material 27 falls into the motion section 25. The neutron-absorbing material 27 is located below the active zone of the reactor core 101.

[0077] When the nuclear reactor 100 is restarted, the discharge port 232 is closed and the inlet port 231 is opened. The moving part 25 drives the storage 27 to extend out of the guide part 24 along the moving channel 26 and the receiving cavity 251 is connected to the inlet port 231. The storage 27 falls back into the storage part 23.

[0078] Specifically, the support portion 22 and the guide portion 24 are tubular and have an internal movement channel 26. The drive portion 21 is located at the end of the support portion 22 away from the guide portion 24. The support portion 22 is located outside the active region of the reactor core 101. Correspondingly, the storage portion 23 provided on the support portion 22 is also located outside the reactor core 101, i.e., in a region that does not participate in neutron absorption. The guide portion 24 is inserted into the active region of the reactor core 101, i.e., in a region that participates in neutron absorption. It can be understood that the movement channel 26 is not connected to the active region of the reactor core 101. The movement portion 25 has the same shape as the inner wall of the movement channel 26 and slides within the movement channel 26. The movement portion 25 is connected to the drive portion 21 so that the drive portion 21 drives the movement portion 25 to extend into or out of the guide portion 24 along the movement channel 26. The storage section 23 is located on the side of the support section 22. The storage section 23 has a cavity inside to accommodate the storage material 27. The storage material 27 can be a sphere or other solid structure of the shape that can roll into the moving section, made of boron carbide, gadolinium oxide, cadmium alloy, etc., used in the prior art for neutron absorption, such as irregular particles, ellipsoids, etc. When the nuclear reactor 100 is operating normally, the moving section 25 extends into the guide section 24 to the bottom of its receiving cavity 251, located below the active zone of the reactor core 101. When the nuclear reactor 100 needs to be shut down, the discharge port 232 of the storage section 23 opens, and the storage material 27 rolls into the receiving cavity 251 of the moving section 25, thereby positioning the storage material 27 below the active zone of the reactor core 101 and covering the active zone of the reactor core 101 in the height direction to participate in neutron absorption, thus achieving the shutdown of the nuclear reactor 100.

[0079] When the nuclear reactor 100 is restarted, the discharge port 232 closes and the feed port 231 opens. The moving part 25 drives the storage 27 along the moving channel 26 to extend out of the guide part 24, and the receiving cavity 251 is connected to the feed port 231, causing the storage 27 to fall back into the storage part 23. Compared with chemical shutdown, which requires injecting absorbent into the molten salt fuel in the reactor core 101 and causing irreversible mixing with the molten salt fuel, the storage 27 is isolated from the molten salt fuel by the guide part 24, avoiding mixing between the storage 27 and the molten salt fuel. Furthermore, the movement of the moving part 25 allows the storage 27 to fall back into the storage part 23, effectively separating it from the molten salt fuel. Thus, when the nuclear reactor 100 needs to be restarted, the nuclide ratio and reactivity of the molten salt fuel can be maintained, allowing a large amount of unburned thorium, uranium, and other nuclear fuels to continue to participate in the chain reaction, significantly saving fuel. At the same time, it greatly reduces the technical difficulty and cost of subsequent fuel processing when the nuclear reactor 100 is restarted.

[0080] In addition, compared to using insert rods or control rods 11 to insert or remove the reactor core 101 for shutdown, the fuel 27 can roll and fall into the moving part 25 or fall back to the storage part 23, thereby avoiding the jamming of the insert rods or control rods 11 due to their large size and movement in a limited space, ensuring the reliability of shutdown and that the fuel 27 used to absorb neutrons can be effectively removed from the active zone of the reactor core 101 when the nuclear reactor 100 is restarted.

[0081] Furthermore, in this embodiment, the drive unit 21 includes a stepper motor 211, a transmission wheel 212, and a transmission chain 213. The stepper motor 211 has a brake unit 2111 for power-off braking. The stepper motor 211 is disposed at the end of the support unit 22 away from the guide unit 24. The transmission wheel 212 passes through the output shaft of the stepper motor 211. The transmission chain 213 is wound around the transmission wheel 212, and the stepper motor 211 and the moving unit 25 are connected through the transmission chain 213.

[0082] Specifically, the transmission wheel 212 is coaxially connected to the output shaft of the stepper motor 211 to rotate synchronously with the output shaft. The transmission wheel 212 has a groove, and the transmission chain 213 is wound around the groove. One end of the transmission chain 213 is connected to the moving part 25 to realize the connection between the stepper motor 211 and the moving part 25, so that the stepper motor 211 can drive the moving part 25 to move up and down in the movement channel 26. The transmission chain 213 can be a flexible structure such as a steel wire rope or chain that is easy to wind, as in the prior art. A support plate 221 is provided at the end of the support part 22 away from the guide part 24. The support plate 221 has a through hole corresponding to the movement channel 26. The stepper motor 211 is mounted on the support plate 221. The stepper motor 211 has a brake part 2111 for power-off braking. The brake part 2111 is located at the end of the stepper motor 211. The brake part 2111 with power-off braking function is a structure in the prior art. This embodiment has not improved it, and will not be described in detail here. In the extreme condition of reactor 100 shutdown and power outage, stepper motor 211 ensures that the position of moving part 25 is not moved, that is, the position of moving part 25 within the movement channel 26 remains unchanged. The unchanged position of moving part 25 ensures that the fuel 27 can effectively cover the active area of ​​reactor core 101, ensuring the reliability of shutdown.

[0083] Of course, the stepper motor 211 can still stop when it is powered on, so as to ensure that the position of the moving part 25 remains unchanged in the movement channel 26.

[0084] In this embodiment, the drive unit 21 further includes a position measuring component 214 and a limit switch 215. The position measuring component 214 is disposed at the end of the output shaft of the stepper motor 211 and rotates synchronously with the transmission wheel 212. The limit switch 215 is disposed in the motion channel 26 of the support unit 22 and is disposed close to the stepper motor 211.

[0085] Specifically, both the position measurement component 214 and the limit switch 215 are electrically connected to the control board of the nuclear reactor 100. The position measurement component 214 consists of a rotary transformer and its support, as used in the prior art. The support is located on the side of the stepper motor 211, and the rotary transformer is mounted on the support and coaxially connected to the end of the output shaft of the stepper motor 211. When the output shaft rotates, the rotary transformer rotates synchronously, converting the linear displacement of the moving part 25 in the motion channel 26 into angular displacement, thereby outputting the position information of the moving part 25 in the motion channel 26 in real time. Based on the feedback position information, the stepper motor 211 is used to place the moving part 25 in the appropriate position in the motion channel 26. The limit switches 215 are installed in pairs at the bottom of the support plate 221 and located in the motion channel 26. The limit switches 215 can be distance sensors or pressure sensors, as used in the prior art, to indicate that the moving part 25 has moved into place by means of distance measurement or direct contact, avoiding the situation where the moving part 25 is pulled to contact the support plate 221 and damaged.

[0086] In this embodiment, the storage section 23 is connected to the movement channel 26 of the support section 22 through the inlet 231 and the outlet 232. The bottom of the storage section 23 has a first slope 233, which is inclined toward the outlet 232.

[0087] Specifically, the storage section 23 is a box with an internal cavity. The side of the box is connected to the support section 22. The box is provided with an inlet 231 and an outlet 232 that communicate with the movement channel 26. The inlet 231 is located above the outlet 232. The outlet 232 is located near the bottom of the box. The bottom of the box is inclined towards the outlet 232 and has a first slope 233 so that the stored material 27 can flow to the outlet 232 in time and enter the movement section 25. This avoids the stored material 27 accumulating in the storage section 23 and failing to fall into the movement section 25 in time, which would result in the stored material 27 not entering the active zone below the core 101.

[0088] In addition, a material level detection device 235 is also provided in the cavity corresponding to the top of the box. The material level detection device 235 can be a liquid level detector in the prior art. The spherical storage material 27 can be regarded as the "liquid" stored in the box. The height of the storage material 27 accumulated in the box is the "liquid level". The material level detection device 235 is electrically connected to the control board of the nuclear reactor 100 to effectively detect the release of the storage material 27. Then, the release of the storage material 27 can be used to effectively determine whether the nuclear reactor 100 is in an effective shutdown condition.

[0089] In another embodiment, the storage unit 23 further includes a connecting pipe 236, through which the inlet 231 and the outlet 232 are connected to the movement channel 26 of the support unit 22. The connecting pipe 236 connected to the inlet 231 is inclined toward the storage unit 23, and the connecting pipe 236 connected to the outlet 232 is inclined toward the support unit 22.

[0090] Specifically, the connecting pipe 236 is a tubing, and two connecting pipes 236 are provided. One connecting pipe 236 has one end connected to the movement channel 26 of the support part 22 and the other end connected to the feed port 231, and the connecting pipe 236 is inclined towards the feed port 231. The other connecting pipe 236 has one end connected to the movement channel 26 of the support part 22 and the other end connected to the discharge port 232, and the connecting pipe 236 is inclined towards the support part 22. The inclined connecting pipe 236 not only supports the storage part 23, but also allows the stored material 27 to flow from the discharge port 232 through the connecting pipe 236 and into the movement part 25 in a timely manner. At the same time, it also allows the stored material 27 to flow from the movement part 25 into the feed port 231 through the connecting pipe 236 in a timely manner, avoiding the situation where the stored material 27 accumulates in the storage part 23 and cannot fall into the movement part 25 in time, and the stored material 27 fails to enter the active zone below the core 101. This also avoids the situation where the stored material 27 accumulates in the moving part 25 and cannot fall into the storage part 23 in time, and the moving part 25 moves away from the guide part 24 and the inlet 231 is not connected to the receiving cavity 251, so that the stored material 27 cannot fall back into the storage part 23.

[0091] Preferably, the inclination angle of the connecting pipe 236 is not less than 60±5°. It can be understood that the two connecting pipes 236 have different inclination directions. By limiting the inclination angle of the connecting pipes 236, the storage material 27 can be effectively guided, avoiding the situation where the storage material 27 accumulates and has poor flowability.

[0092] In this embodiment, the moving part 25 includes an end 252, a base 253 and a connecting rod 254. The two ends of the connecting rod 254 are connected to the end 252 and the base 253 respectively. At least three connecting rods 254 are provided, and at least three connecting rods 254 are spaced apart along the circumferential direction of the end 252 and the base 253 and surround to form a receiving cavity 251. The gap between two adjacent connecting rods 254 is larger than the size of the storage 27.

[0093] Specifically, at least three connecting rods 254 are spaced apart between the end 252 and the base 253 and spaced apart in the circumferential direction of the end 252 and the base 253. The at least three connecting rods 254 surround to form a receiving cavity 251, and the gap between two adjacent connecting rods 254 is used for the passage of the storage material 27 so that the storage material 27 can enter the receiving cavity 251. The end 252, base 253, and connecting rod 254 form a hollow "cage" structure to facilitate the rapid falling of the storage material 27 into the moving part 25. At the same time, when the nuclear reactor 100 is restarted, the storage material 27 can also fall back to the feed port 231 through the gap between two adjacent connecting rods 254, thereby realizing that the storage material 27 is away from the active area of ​​the core 101 and effectively separated from the molten salt fuel. Since the storage material 27 is a sphere or other solid structure with a size smaller than the gap between two adjacent connecting rods 254, it has its own rolling ability. When the moving part 25 is extended out of the guide part 24, the storage material 27 can effectively follow the movement of the moving part 25. Compared with the method of inserting or removing the core 101 by inserting or removing the insert rod or control rod 11 to shut down the reactor, it can avoid the situation where the insert rod or control rod 11 gets stuck. There is no need to worry about the storage material 27 being too large and getting stuck in the guide part 24, which would prevent the nuclear reactor 100 from restarting effectively.

[0094] Furthermore, compared to having two connecting rods 254, having at least three connecting rods 254 can improve the stability of the moving part 25. The gap between adjacent connecting rods 254 is smaller among the at least three connecting rods 254. This smaller gap corresponds to a smaller size for the storage material 27 entering and exiting the receiving cavity 251, thus preventing the storage material 27, although spherical, from becoming too large and easily getting stuck in the guide part 24.

[0095] In this embodiment, the gap between the end 252 or the base 253 and the inner wall of the motion channel 26 is no greater than 2 ± 0.5 mm.

[0096] Specifically, by limiting the gap between the end 252 or the base 253 and the inner wall of the movement channel 26, the gap between the connecting rod 254 and the inner wall of the movement channel 26 is limited to less than or equal to 2 ± 0.5 mm. This ensures that while there is room for movement between the moving part 25 and the inner wall of the movement channel 26, it prevents the storage material 27 from falling directly into the guide part 24 through the gap and failing to extend out of the guide part 24 along with the moving part 25. It is understood that the size of the storage material 27 is larger than the gap size.

[0097] In this embodiment, the base 253 has a second slope 2531, which is inclined toward the feed inlet 231.

[0098] Specifically, the base 253 is a cylindrical structure. The surface of the base 253 corresponding to the receiving cavity 251 has a second slope 2531. The second slope 2531 is inclined toward the feed inlet 231. When the moving part 25 extends out of the guide part 24, the receiving cavity 251 is connected to the feed inlet 231. The storage material 27 is guided by the second slope 2531, so that the storage material 27 can quickly fall back to the storage part 23, so that the nuclear reactor 100 can be restarted and the storage material 27 can fall from the storage part 23 into the moving part 25 again during the next shutdown.

[0099] In this embodiment, the inclination angle of the first slope 233 and the second slope 2531 is not less than 60±5°. By limiting the inclination angle of the first slope 233 and the second slope 2531, the stored material 27 can be effectively guided, avoiding the accumulation of the stored material 27 and the resulting poor flowability.

[0100] Please refer to the following: Figure 5 , Figure 6 , Figure 7 and Figure 8 In this embodiment, an electromagnetic gate 234 is provided at the discharge port 232. When the nuclear reactor 100 is shut down, the electromagnetic gate 234 is de-energized and the discharge port 232 remains open. When the nuclear reactor 100 is restarted, the electromagnetic gate 234 is energized and the discharge port 232 is closed.

[0101] Specifically, the electromagnetic gate 234 is a gate structure in the prior art. The electromagnetic gate 234 is electrically connected to the control board of the nuclear reactor 100. This embodiment does not improve it. Taking the storage 27 as a sphere for explanation, when the nuclear reactor 100 is operating normally, the stepper motor 211 drives the moving part 25 to extend into the guide part 24 and be located in the active area of ​​the core 101 through the transmission chain 213. During the process of the moving part 25 falling towards the guide part 24, the position measurement component 214 outputs the position information of the moving part 25 in the reactor in real time. The position information fed back by the position measurement component 214 places the moving part 25 in a suitable position. At this time, the base 253 of the moving part 25 is located below the lower surface of the active area. The stepper motor 211 has a built-in power-off braking function, which can still keep the moving part 25 in the original position when the power is off. At this time, the electromagnetic gate 234 is energized and closes the discharge port 232. The spherical storage 27 is located in the storage part 23.

[0102] When the nuclear reactor 100 needs to be shut down, the electromagnetic gate 234 is de-energized and the discharge port 232 remains open. The spherical storage material 27 rolls into the moving part 25 and follows the moving part 25 to the lower surface of the active zone, so as to achieve reliable shutdown.

[0103] When the nuclear reactor 100 needs to be restarted, the electromagnetic gate 234 is energized and closes the discharge port 232. The stepper motor 211 is energized and its braking function is released. The stepper motor 211 drives the transmission wheel 212 to lift the moving part 25 upward in the direction away from the guide part 24 through the transmission chain 213 until the second slope 2531 of its base 253 is aligned with the feed port 231. The spherical storage 27 will slide back into the storage part 23 by its own weight through the second slope 2531, thereby realizing the restart of the nuclear reactor 100.

[0104] In this embodiment, the first shutdown mechanism 1 and the second shutdown mechanism 2 are disposed at intervals on the nuclear reactor 100 and are independent of each other.

[0105] It is understandable that the first shutdown mechanism 1 and the second shutdown mechanism 2 are set up in parallel and independently. When nuclear reactor 100 is shut down, the first shutdown mechanism 1 and the second shutdown mechanism 2 can be opened simultaneously or individually. In the event of a stick jamming in the first shutdown mechanism 1, the second shutdown mechanism 2 can be opened in place of the first shutdown mechanism 1. Users can set these according to their actual needs, thereby providing dual protection for the shutdown of nuclear reactor 100 to ensure the independence and reliability of the shutdown.

[0106] In this embodiment, the second shutdown mechanism 2 achieves a passively designed safe shutdown by relying on the moving part 25 and the fuel storage 27. On the other hand, it achieves fuel reuse by actively separating the fuel storage 27 from the active zone of the core 101. This significantly improves the convenience of mechanism operation, reactor safety and reliability, and fundamentally solves the technical pain point of common cause failures in rod-type shutdown systems, providing an efficient solution for improving the safety performance of nuclear reactors.

[0107] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A nuclear reactor shutdown system, wherein the nuclear reactor shutdown system is disposed on a nuclear reactor, the nuclear reactor shutdown system comprising a first shutdown mechanism, the first shutdown mechanism comprising control rods for inserting or removing the reactor core, characterized in that, The nuclear reactor shutdown system also includes: The second shutdown mechanism includes a drive unit, a support unit, a storage unit, a guide unit, and a moving unit. The support unit is located outside the reactor core, and the guide unit is inserted inside the reactor core. The support unit and the guide unit have interconnected movement channels, and the moving unit slides within these channels. The drive unit and the storage unit are mounted on the support unit. The drive unit drives the moving unit to extend into or out of the guide unit along the movement channels. The storage unit has an inlet and an outlet, both connected to the movement channels. The storage unit contains neutron-absorbing material, and the moving unit has a receiving cavity for accommodating the neutron-absorbing material. When the nuclear reactor is running, the drive unit drives the moving unit to extend into the guide unit along the movement channels, with the bottom of the receiving cavity located below the active zone of the reactor core. When the nuclear reactor is shut down, the outlet opens, and the neutron-absorbing material falls into the moving unit, located below the active zone of the reactor core. When the nuclear reactor is restarted, the discharge port is closed and the inlet is opened. The moving part drives the stored material to extend out of the guide part along the moving channel and the receiving cavity is connected to the inlet. The stored material falls back into the storage part.

2. The nuclear reactor shutdown system as described in claim 1, characterized in that, The drive unit includes a stepper motor, a drive wheel, and a drive chain. The stepper motor has a brake part for power-off braking. The stepper motor is disposed at the end of the support unit away from the guide unit. The drive wheel passes through the output shaft of the stepper motor. The drive chain is wound around the drive wheel, and the stepper motor and the moving unit are connected through the drive chain.

3. The nuclear reactor shutdown system as described in claim 2, characterized in that, The drive unit also includes a position measuring component and a limit switch. The position measuring component is disposed at the end of the output shaft of the stepper motor and rotates synchronously with the transmission wheel. The limit switch is disposed in the motion channel of the support unit and is disposed close to the stepper motor.

4. The nuclear reactor shutdown system as described in claim 1, characterized in that, The storage section is connected to the movement channel of the support section through the inlet and outlet. The bottom of the storage section has a first slope, which is inclined toward the outlet. And / or, the storage unit further includes a connecting pipe, through which the inlet and the outlet are connected to the movement channel of the support unit. The connecting pipe connected to the inlet is inclined toward the storage unit, and the connecting pipe connected to the outlet is inclined toward the support unit.

5. The nuclear reactor shutdown system as described in claim 4, characterized in that, The moving part includes an end, a base, and connecting rods. The two ends of the connecting rods are connected to the end and the base, respectively. At least three connecting rods are provided, and at least three connecting rods are spaced apart along the circumferential direction of the end and the base to form the receiving cavity. The gap between two adjacent connecting rods is larger than the size of the storage material.

6. The nuclear reactor shutdown system as described in claim 5, characterized in that, The gap between the end or the base and the inner wall of the motion channel is no greater than 2 ± 0.5 mm.

7. The nuclear reactor shutdown system as described in claim 5, characterized in that, The base has a second slope that is inclined toward the feed inlet.

8. The nuclear reactor shutdown system as described in claim 7, characterized in that, The inclination angle between the first slope and the second slope is not less than 60±5°; And / or, the tilt angle of the connecting pipe is not less than 60±5°.

9. The nuclear reactor shutdown system as described in claim 1, characterized in that, An electromagnetic gate is installed at the discharge port. When the nuclear reactor is shut down, the electromagnetic gate is de-energized and the discharge port remains open. When the nuclear reactor is restarted, the electromagnetic gate is energized and the discharge port is closed.

10. The nuclear reactor shutdown system as described in claim 1, characterized in that, The first shutdown mechanism and the second shutdown mechanism are disposed at intervals on the nuclear reactor and are independent of each other.

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