Reactor shutdown device and reactor

Abstract

The embodiment of the invention relates to the field of mechanical driving devices for controlling nuclear reactions, in particular to a reactor shutdown device and a reactor. According to the reactor shutdown device provided by the invention, the reflection part on the second reactor shutdown assembly can reflect neutrons together with the reflection part on the first reactor shutdown assembly when the reactor works normally; the second shut-down assembly moves relative to the first shut-down assembly, so that the absorption part on the second shut-down assembly can correspond to the cavity part on the first shut-down assembly under the reactor shut-down working condition of the reactor, neutron absorption is achieved, and the aim of shut-down is achieved. According to the arrangement, the shut-down assemblies are respectively divided into parts which have different effects on neutrons, so that the second shut-down assembly only needs to move a preset distance smaller than the height of the reactor core relative to the first shut-down assembly to realize shut-down, and the stroke and time required by shut-down operation are reduced. According to the reactor provided by the embodiment of the invention, excessive space does not need to be reserved for the shutdown device in the axial direction, and the compactness and the miniaturization level are high.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of mechanical drive devices for controlling nuclear reactions, and in particular to a shutdown device and a reactor. Background Art

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] During the operation of a nuclear power plant, when an event endangering the safety of the reactor occurs, a shutdown operation needs to be performed. When the reactor needs to be shut down, the control rods need to be fully inserted into the reactor core. The material inside the control rods can strongly absorb neutrons, resulting in insufficient neutrons to maintain the chain reaction, and the fission reaction of the reactor will weaken until it stops. Summary of the invention

[0004] A brief overview of the present application is provided below in order to provide a basic understanding of certain aspects of the present application. It should be understood that this overview is not an exhaustive overview of the present application. It is not intended to identify the key or important parts of the present application, nor is it intended to limit the scope of the present application. Its purpose is merely to present certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0005] One aspect of an embodiment of the present application provides a shutdown device for absorbing the reactivity of a core, comprising: an outer reflection layer, a first shutdown assembly and a second shutdown assembly, wherein the outer reflection layer, the first shutdown assembly and the second shutdown assembly are arranged in sequence from far to near the core, the first shutdown assembly forms a plurality of reflection parts and a plurality of cavity parts in sequence along the longitudinal direction of the core, the second shutdown assembly forms a plurality of reflection parts and a plurality of absorption parts in sequence along the longitudinal direction of the core, and the second shutdown assembly is configured to be movable along the longitudinal direction of the core and configured such that: when the reactor is in normal operating conditions, the plurality of reflection parts of the first shutdown assembly can shield the plurality of absorption parts of the second shutdown assembly in radial direction; in shutdown operating conditions, the plurality of cavity parts of the first shutdown assembly can correspond to the plurality of absorption parts of the second shutdown assembly in radial direction, so that the plurality of absorption parts can absorb neutrons of the core.

[0006] Another aspect of an embodiment of the present application provides a reactor, which includes a core and the aforementioned shutdown device, wherein the shutdown device is arranged to surround the core.

[0007] The shutdown device provided in the embodiment of the present application enables the reflector on the second shutdown assembly to reflect neutrons together with the reflector on the first shutdown assembly when the reactor is operating normally; at the same time, the second shutdown assembly moves relative to the first shutdown assembly, so that the absorption part on the second shutdown assembly can correspond to the cavity part on the first shutdown assembly when the reactor is in shutdown condition, so as to absorb neutrons and achieve the purpose of shutdown. This arrangement divides the first shutdown assembly and the second shutdown assembly into parts that play different roles in neutrons, so that the second shutdown assembly can achieve shutdown by moving a predetermined distance less than the core height relative to the first shutdown assembly, thereby reducing the travel and time required for the shutdown operation.

[0008] The core of the reactor provided in the embodiment of the present application is surrounded by the aforementioned shutdown device, and there is no need to reserve too much space for the shutdown device in the axial direction, thereby achieving technical effects of high compactness and high miniaturization level, and the shutdown response is rapid, and the reactor operation safety is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to further illustrate the above and other advantages and features of the present application, the specific embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. The accompanying drawings together with the following detailed description are included in this specification and form a part of this specification. Elements with the same function and structure are represented by the same reference numerals. It should be understood that these drawings only describe typical examples of the present application and should not be regarded as limiting the scope of the present application.

[0010] Figure 1 is a top schematic diagram of a reactor provided in an embodiment of the present application;

[0011] Figure 2 is a schematic axial cross-sectional view of a reactor provided in an embodiment of the present application;

[0012] Figure 3 is a schematic diagram of a partial structure of an elastic component provided in an embodiment of the present application;

[0013] Figure 4 is a bottom schematic diagram of a reactor provided in an embodiment of the present application;

[0014] Figure 5 It is a schematic diagram of the overall structure of the shutdown device provided in the embodiment of the present application;

[0015] Figure 6 It is a schematic structural diagram of a shutdown device provided in an embodiment of the present application in a shutdown condition;

[0016] Figure 7 is a schematic diagram of the core arrangement provided in an embodiment of the present application;

[0017] Figure 8It is a schematic diagram of the normal operation of a reactor with a 9-layer grid shutdown device provided in an embodiment of the present application;

[0018] Fig. 9 It is a schematic diagram of a reactor shutdown state with a 9-layer grid shutdown device provided in an embodiment of the present application;

[0019] Fig.10 It is a schematic diagram of the normal operation of a reactor with a 7-layer grid shutdown device provided in an embodiment of the present application;

[0020] Fig.11 It is a schematic diagram of the shutdown state of a reactor with a 7-layer grid shutdown device provided in an embodiment of the present application.

[0021] Description of reference numerals:

[0022] 1. Outer reflection layer; 100. Reactor; 2. First shutdown assembly; 200. Shutdown device; 21. Reflector; 22. Cavity; 23. Longitudinal support structure; 24. Transverse support structure; 3. Second shutdown assembly; 31. Absorber; 32. Sleeve; 33. Slide rail; 34. Elastic assembly; 341. First plate; 342. Second plate; 3420. Opening; 343. Elastic member; 35. Operating unit; 4. Core. DETAILED DESCRIPTION

[0023] Exemplary embodiments of the present application will be described below in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual implementation are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the process of developing any such actual implementation in order to achieve the developer's specific goals, such as meeting those constraints related to the system and business, and these constraints may vary from implementation to implementation. In addition, it should be understood that although the development work may be very complex and time-consuming, it is only a routine task for those skilled in the art who benefit from the content of this application.

[0024] It is also necessary to explain here that, in order to avoid obscuring the present application due to unnecessary details, only the device structure and / or processing steps closely related to the scheme according to the present application are shown in the accompanying drawings, while other details that are not very relevant to the present application are omitted.

[0025] The disclosure below provides a plurality of different embodiments or examples to implement the present application. In order to simplify the disclosure of the present application, the parts and methods of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the present application. In the description of the embodiments of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically limited.

[0026] At present, traditional axially moving control rods and their driving mechanisms usually require a large axial space, which is not easy to integrate into the miniaturized reactor. Therefore, in the design of micro-reactors, a rotating control drum is usually used to replace the traditional control rods. The axial stroke required for dropping the rods is not required, so the axial space can be saved and a compact control system design can be achieved. However, the resetting of the drum requires the participation of active components, and its reliability is not as good as that of gravity dropping the rods. Therefore, a control system that is both reliable and miniaturized is needed.

[0027] One aspect of an embodiment of the present application provides a shutdown device for absorbing the reactivity of a core. Figure 2 The axial cross-sectional schematic diagram of the reactor provided by the embodiment of the present application is shown. In some embodiments, as Figure 2 As shown, the shutdown device includes: an outer reflection layer 1, a first shutdown assembly 2 and a second shutdown assembly 3, the outer reflection layer 1, the first shutdown assembly 2 and the second shutdown assembly 3 are arranged in sequence from far to near the core 4, the first shutdown assembly 2 forms a plurality of reflection parts and a plurality of cavity parts 22 in sequence along the longitudinal direction of the core, the second shutdown assembly 3 forms a plurality of reflection parts and a plurality of absorption parts in sequence along the longitudinal direction of the core 4, and the second shutdown assembly 3 is arranged to be movable along the longitudinal direction of the core 4, and is arranged so that: when the reactor 100 is in a normal operating condition, the plurality of reflection parts of the first shutdown assembly 2 can shield the plurality of absorption parts of the second shutdown assembly 3 in the radial direction; in the shutdown operating condition, the plurality of cavity parts 22 of the first shutdown assembly 2 can correspond to the plurality of absorption parts of the second shutdown assembly 3 in the radial direction, so that the plurality of absorption parts can absorb neutrons of the core 4.

[0028] The shutdown device provided in the embodiment of the present application enables the reflector on the second shutdown assembly 3 to reflect neutrons together with the reflector on the first shutdown assembly 2 when the reactor 100 is operating normally; at the same time, the second shutdown assembly 3 moves relative to the first shutdown assembly 2, so that the absorption part on the second shutdown assembly 3 can correspond to the cavity part 22 on the first shutdown assembly 2 when the reactor 100 is in shutdown condition, so as to absorb neutrons and achieve the purpose of shutdown. This arrangement divides the first shutdown assembly 2 and the second shutdown assembly 3 into parts that play different roles in neutrons, so that the second shutdown assembly 3 can achieve shutdown by moving a predetermined distance less than the height of the core 4 relative to the first shutdown assembly 2, thereby reducing the travel and time required for the shutdown operation.

[0029] In some embodiments, Figure 2As shown, the multiple reflective parts and the multiple cavity parts 22 of the first shutdown assembly 2 are spaced apart from each other; and the multiple reflective parts and the multiple absorbing parts of the second shutdown assembly 3 are spaced apart from each other, and are arranged so that: when the reactor 100 is under normal operating conditions, the multiple reflective parts of the first shutdown assembly 2 can shield the multiple absorbing parts of the second shutdown assembly 3 in the radial direction.

[0030] In some embodiments, the reflector of the first shutdown assembly 2 corresponds to the absorber of the second shutdown assembly, and the cavity of the first shutdown assembly 2 corresponds to the reflector of the second shutdown assembly 3, so that the shutdown device under normal conditions is radially covered by the reflector. A portion of the neutrons escaping from the core 4 are directly reflected by the reflector of the first shutdown assembly 2 in the radial direction, and the other portion moves to the position of the second shutdown assembly 3 through the cavity 22 of the first shutdown assembly 2 and is reflected by the reflector of the second shutdown assembly 3 radially adjacent to the cavity 22, that is, the reflector of the first shutdown assembly 2 and the reflector of the second shutdown assembly 3 jointly realize the reflection of neutrons, prevent the neutrons from being absorbed in large quantities under normal conditions, and enable more neutrons to continue to participate in the reaction, thereby improving the neutron utilization rate and reactor efficiency.

[0031] Figure 6 The schematic diagram of the structure of the shutdown device provided in the embodiment of the present application in the shutdown state is shown. In some embodiments, for example, Figure 6 As shown, in shutdown condition, the plurality of cavity portions 22 of the first shutdown assembly 2 can correspond to the plurality of absorption portions of the second shutdown assembly 3 in radial direction, so that the plurality of absorption portions can absorb neutrons of the core 4 .

[0032] In some embodiments, Figure 2 and Figure 6 As shown, in the shutdown condition, the second shutdown assembly 3 moves relative to the first shutdown assembly 2 in the axial direction to generate displacement, the reflecting portion of the second shutdown assembly 3 corresponds to the reflecting portion of the first shutdown assembly 2, and the absorbing portion of the second shutdown assembly 3 corresponds to the cavity portion of the first shutdown assembly 2. In the shutdown condition, part of the neutrons escaping from the core 4 are directly reflected by the reflecting portion of the first shutdown assembly 2 in the radial direction, and the other part moves to the position of the second shutdown assembly 3 through the cavity portion 22 of the first shutdown assembly 2, and is absorbed by the absorbing portion of the second shutdown assembly 3 radially adjacent to the cavity portion 22, thereby reducing the neutron flux and lowering the reactivity of the reactor 100, so as to achieve the purpose of shutdown.

[0033] In some embodiments, Figure 2As shown, the first shutdown assembly 2 includes a longitudinal support structure 23, a transverse support structure 24 and a plurality of reflectors 21. The longitudinal support structure 23 and the transverse support structure 24 are arranged in a grid-like structure. The plurality of reflectors 21 are arranged at different positions of the grid-like structure. The positions where the reflectors 21 are arranged form reflective portions, and the positions where the reflectors 21 are not arranged form cavity portions 22.

[0034] In some embodiments, the number of grids in the grid-like structure is determined according to the actual height of the core 4, so that the upper and lower bottoms of the first shutdown assembly 2 are aligned with the upper and lower ends of the core to prevent neutron leakage. The top grid of the first shutdown assembly 2 needs to be set as a reflector 21 instead of a cavity 22 to ensure that neutrons do not escape from the top cavity 22 during shutdown conditions. The bottommost grid of the first shutdown assembly 2 can be set as a reflector 21 or as a cavity 22. The number of grids of the first shutdown assembly 2 should be an odd number to ensure that the impact of the shutdown device 200 on the axial distribution of the core power under normal conditions is symmetrical.

[0035] In some embodiments, the second shutdown assembly 3 includes a sleeve 32, a plurality of reflectors 21 and a plurality of absorbers 31. The sleeve 32 forms a grid-like structure. The plurality of reflectors 21 are arranged at different positions of the grid-like structure. The positions where the reflectors 21 are arranged form a reflecting portion, and the positions where the absorbers 31 are arranged form an absorbing portion. The sleeve 32 fixes the plurality of reflectors 21 and the plurality of absorbers 31 therein, and the relative positions between the reflectors 21 and the absorbers 31 are fixed. When the sleeve 32 moves, the reflectors 21 and the absorbers 31 can move as a whole and their relative positions to each other remain unchanged.

[0036] In some embodiments, the bottommost grid of the second shutdown assembly 3 can be configured as a reflector 21 or an absorber 31. Since the second shutdown assembly 3 moves a distance of one grid relative to the first shutdown assembly 2 in the shutdown condition, a space of a grid height needs to be reserved below the bottom grid of the second shutdown assembly for shutdown operation, that is, the number of grids of the second shutdown assembly 3 should be one less than the number of grids of the first shutdown assembly 2, that is, the number of grids of the second shutdown assembly 3 should be an even number.

[0037] In some embodiments, Figure 2 As shown, the second shutdown assembly 3 further includes a slide rail 33 , which is configured to be fixed to the reactor 100 , and the slide rail 33 is configured so that the sleeve 32 can move longitudinally to a predetermined position along the slide rail 33 .

[0038] In some embodiments, sliding the sleeve 32 along the slide rail 33 can reduce the resistance of the second shutdown assembly 3 when it falls, which is conducive to rapid shutdown.

[0039] Figure 1A top schematic diagram of a reactor provided by an embodiment of the present application is shown. In some embodiments, as Figure 1 As shown, the shutdown device 200 includes an operating part 35, which is arranged on the top of the second shutdown assembly 3 and is used to grab and operate the second shutdown assembly 3 as a whole. The triggering mode and driving mode of the operating part 35 are not specifically limited. The triggering mode can be a shutdown signal of the reactor protection system, plus an electromagnetic clutch, or a core outlet temperature rise, plus a support fuse or a gripper that works based on the Curie point; the driving mode can be gravity drop, buoyancy rise, auxiliary rod drop, etc. Different triggering modes and driving modes are compatible with the shutdown device 200.

[0040] Figure 3 FIG. 1 shows a schematic diagram of a partial structure of an elastic component provided in an embodiment of the present application. In some embodiments, as Figure 3 As shown, the second shutdown assembly 3 further includes an elastic assembly 34 . When the sleeve 32 moves from its position in a normal operating condition to a shutdown condition, the elastic assembly 34 is configured to interact with the sleeve 32 to buffer the force generated by the movement of the sleeve 32 .

[0041] The elastic component 34 is provided to provide a buffer for the sleeve 32 to prevent damage to the equipment due to excessive impact force of the sleeve 32 during shutdown operation, and to prevent rebound due to excessive impact force of the sleeve 32, thereby ensuring rapid and stable shutdown of the stack.

[0042] In some embodiments, Figure 3 As shown, the elastic component 34 includes a first plate 341, a second plate 342 and an elastic member 343. The elastic member 343 is arranged between the first plate 341 and the second plate 342. The first plate 341 is arranged to interact with the sleeve 32 when the sleeve 32 moves from its position in the normal operating condition to the shutdown condition.

[0043] In some embodiments, when the movement direction of the sleeve 32 is falling motion, the first plate 341 is in direct contact with the sleeve 32 to increase the contact area, so that the sleeve 32 is evenly stressed when contacting the first plate 341, thereby preventing uneven force from causing the sleeve 32 to be unable to fully contact the bottom of the container; setting a second plate 342 at the bottom of the container can enhance the strength of the bottom of the container, thereby preventing the sleeve from being damaged by excessive impact force on the bottom of the container when falling; at the same time, the elastic member 343 is set between the first plate 341 and the second plate 342, and provides elastic force to further provide a buffer for the falling of the sleeve 32.

[0044] Figure 4 The bottom schematic diagram of the reactor provided by the embodiment of the present application is shown. In some embodiments, as Figure 3 and Figure 4As shown, an opening 3420 is formed below the position where the second plate 342 is set, which is used for ventilation to prevent the resistance caused by the failure to discharge the gas in the space reserved for the second shutdown assembly 3 in time from affecting the rod dropping speed.

[0045] In some embodiments, the moving distance of the second shutdown assembly 3 is determined according to the expected value of the shutdown device 200 .

[0046] The relationship between the moving distance of the second shutdown assembly 3 and the expected value is verified below by comparing the effects of two specific implementation schemes provided in this application.

[0047] Figure 7 A schematic diagram of a core arrangement provided in an embodiment of the present application is shown. Figure 8 A schematic diagram showing the normal operation of a reactor with a 9-layer grid shutdown device provided by an embodiment of the present application is shown. Fig. 9 A schematic diagram showing the shutdown state of a reactor with a 9-layer grid shutdown device provided in an embodiment of the present application is shown as follows: Figure 7-Figure 9 As shown, the height of the core 4 is set to 54 cm, the first shutdown assembly 2 is set to have 9 grid layers, and the second shutdown assembly 3 is set to have 8 grid layers, each grid layer is 6 cm high. After calculation, the effective proliferation factors of normal operation and shutdown state are 1.00068 and 0.98309 respectively, and the value of the annular shutdown device with 9 grid layers is 1788pcm in total.

[0048] Fig.10 A schematic diagram showing the normal operation of a reactor with a seven-layer grid shutdown device provided by an embodiment of the present application is shown. Fig.11 A schematic diagram showing the shutdown state of a reactor with a 7-layer grid shutdown device provided in an embodiment of the present application is shown as follows: Fig.10 and Fig.11 As shown, the height of the core 4 is set to 54 cm, the first shutdown assembly 2 is set to have 7 layers of grids, and the second shutdown assembly 3 is set to have 6 layers of grids. The height of each grid layer is 7.71 cm. After calculation, the effective proliferation factors of normal operation and shutdown state are 1.00243 and 0.98328 respectively. The value of the annular shutdown device with 7 layers of grids is 1943pcm in total.

[0049] From the calculation results, it can be seen that the more grid layers there are, the shorter the moving distance of the second shutdown component 3 is, but the value of the shutdown device is lower; the fewer grid layers there are, the longer the moving distance of the second shutdown component 3 is, but the value of the shutdown device is greater. The above two types of shutdown devices can meet the shutdown requirements. In actual application, the number of grid layers can be adjusted on the premise of meeting the safety shutdown requirements.

[0050] Another aspect of an embodiment of the present application provides a reactor 100 , which includes a core 4 and the aforementioned shutdown device 200 , wherein the shutdown device 200 is disposed to surround the core 4 .

[0051] The core 4 of the reactor 100 provided in the embodiment of the present application is surrounded by the aforementioned shutdown device 200, and there is no need to reserve too much space for the shutdown device 200 in the axial direction, thereby achieving technical effects of high compactness and high miniaturization level, and the shutdown response is rapid, and the reactor operation safety is high.

[0052] In some embodiments, Figure 2 As shown, the shutdown device 200 is located inside the reactor container and surrounds the core 4. In this case, in order to achieve shutdown, the operating portion 35 needs to be exposed from the reactor container to facilitate the operation of the second shutdown assembly 3, such as Figure 1 As shown, the top of the shutdown device 200 needs to penetrate and be fixed to the stack top cover.

[0053] In some embodiments, the shutdown device 200 is arranged outside the stack body and close to the stack body. At this time, the shutdown device 200 is located outside the stack container, which can realize modular design and installation, while reducing penetration of the stack container to ensure its airtightness.

[0054] Figure 5 The overall structure diagram of the shutdown device provided in the embodiment of the present application is shown. In some embodiments, for example, Figure 5 As shown, the outer reflective layer 1 of the shutdown device 200 is made of a whole piece of reflective layer material, forming the outer structure of the shutdown device 200. Under shutdown conditions, neutrons escaping from the core 4 are absorbed by the absorption part of the second shutdown assembly 3, and the radially outermost outer reflective layer 1 is used to reflect part of the neutrons that are not absorbed, preventing the neutrons from continuing to diffuse outward, thereby ensuring shutdown safety.

[0055] In some embodiments, Figure 2 As shown, the cavity 22 and the reflector 21 in the first shutdown assembly 2 are of equal height, wherein the cavity 22 is filled with inert gas, and the overall height of the first shutdown assembly 2 is equal to the height of the core 4; the absorber 31 and the reflector 21 in the second shutdown assembly 3 are of equal height, so that before and after the second shutdown assembly 3 moves relative to the first shutdown assembly 2, the grids inside each can be aligned to prevent neutron leakage.

[0056] In some embodiments, the thickness of the first shutdown assembly 2 is equal to the sum of the thickness of the second shutdown assembly 3 and the outer reflective layer 1, ensuring that the thickness of the reflective layer at each axial height of the shutdown device 200 is nearly constant under normal operating conditions, thereby reducing local disturbances introduced into the axial distribution of core power.

[0057] In some embodiments, the reflective portion may be made of materials with good neutron reflection effects such as stainless steel or beryllium oxide, and the absorbing portion may be made of materials with good neutron absorption effects such as boron carbide.

[0058] In some embodiments, Figure 5 As shown, the shutdown device 200 has a predetermined curvature as a whole, and the predetermined curvature can be adjusted according to the number of shutdown devices 200 so that the predetermined number of shutdown devices 200 are evenly distributed around the core 4. For example, there are 3 shutdown devices 200, each with a curvature of 120°.

[0059] Regarding the embodiments of the present application, it should also be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other to obtain new embodiments.

[0060] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A shutdown device for absorbing the reactivity of a reactor core, characterized in that: It includes: an outer reflector, a first shutdown assembly, and a second shutdown assembly, The outer reflection layer, the first shutdown assembly and the second shutdown assembly are arranged in sequence from far to near the core, The first shutdown assembly forms a plurality of reflection parts and a plurality of cavity parts in sequence along the longitudinal direction of the core. The second shutdown assembly forms a plurality of reflecting parts and a plurality of absorbing parts in sequence along the longitudinal direction of the core. And the second shutdown assembly is configured to be movable along the longitudinal direction of the core, and is configured so that: when the reactor is in normal operating conditions, the multiple reflecting parts of the first shutdown assembly can radially shield the multiple absorbing parts of the second shutdown assembly; in shutdown conditions, the multiple cavity parts of the first shutdown assembly can correspond to the multiple absorbing parts of the second shutdown assembly in the radial direction, so that the multiple absorbing parts can absorb neutrons of the core.

2. The shutdown device according to claim 1, characterized in that: The plurality of reflection parts and the plurality of cavity parts of the first shutdown assembly are arranged spaced apart from each other; And the multiple reflecting parts and the multiple absorbing parts of the second shutdown assembly are spaced apart from each other, and are arranged so that: when the reactor is in normal operating conditions, the multiple reflecting parts of the first shutdown assembly can radially shield the multiple absorbing parts of the second shutdown assembly; in shutdown conditions, the multiple cavity parts of the first shutdown assembly can correspond to the multiple absorbing parts of the second shutdown assembly in the radial direction, so that the multiple absorbing parts can absorb neutrons of the core.

3. The shutdown device according to claim 1, characterized in that: The first shutdown assembly includes a longitudinal support structure, a transverse support structure and a plurality of reflectors. The longitudinal support structure and the transverse support structure are arranged in a grid-like structure. The plurality of reflectors are arranged at different positions of the grid-like structure. The positions where the reflectors are arranged form the reflective portions, and the positions where the reflectors are not arranged form the cavity portions.

4. The shutdown device according to any one of claims 1 to 3, characterized in that: The second shutdown assembly includes a sleeve, a plurality of reflectors and a plurality of absorbers, wherein the sleeve forms a grid-like structure, and the plurality of reflectors are arranged at different positions of the grid-like structure, wherein the positions where the reflectors are arranged form the reflective portion, and the positions where the absorbers are arranged form the absorbent portion. The sleeve fixes the multiple reflective elements and the multiple absorbent elements therein, and the relative positions between the reflective elements and the absorbent elements are fixed. When the sleeve moves, the reflective elements and the absorbent elements move as a whole while their relative positions remain unchanged.

5. The shutdown device according to claim 4, characterized in that: The second shutdown assembly further includes a slide rail, which is configured to be fixed to the reactor, and the slide rail is configured so that the sleeve can move longitudinally to a predetermined position along the slide rail.

6. The shutdown device according to claim 4, characterized in that: The second shutdown assembly further comprises an elastic assembly. When the sleeve moves from its position in the normal working condition to the shutdown working condition, the elastic assembly is configured to interact with the sleeve to buffer the force generated by the movement of the sleeve.

7. The shutdown device according to claim 6, characterized in that: The elastic component includes a first plate, a second plate and an elastic member, wherein the elastic member is arranged between the first plate and the second plate, and the first plate is arranged so that when the sleeve moves from its position in the normal operating condition to the shutdown operating condition, the first plate is arranged to interact with the sleeve.

8. The shutdown device according to claim 7, characterized in that: An opening is formed below the location where the second plate is disposed.

9. The shutdown device according to any one of claims 1 to 8, characterized in that: The moving distance of the second shutdown assembly is determined according to the expected value of the shutdown device.

10. A reactor, characterized in that: It includes: core, and The shutdown device according to any one of claims 1 to 9, wherein the shutdown device is arranged to surround the core.

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