CN115547521A - Nuclear reactor reactivity control device - Google Patents
Nuclear reactor reactivity control device Download PDFInfo
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- CN115547521A CN115547521A CN202211303226.XA CN202211303226A CN115547521A CN 115547521 A CN115547521 A CN 115547521A CN 202211303226 A CN202211303226 A CN 202211303226A CN 115547521 A CN115547521 A CN 115547521A
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C7/00—Control of nuclear reaction
- G21C7/32—Control of nuclear reaction by varying flow of coolant through the core by adjusting the coolant or moderator temperature
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C7/00—Control of nuclear reaction
- G21C7/06—Control of nuclear reaction by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section
- G21C7/08—Control of nuclear reaction by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section by displacement of solid control elements, e.g. control rods
- G21C7/12—Means for moving control elements to desired position
- G21C7/14—Mechanical drive arrangements
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C7/00—Control of nuclear reaction
- G21C7/28—Control of nuclear reaction by displacement of the reflector or parts thereof
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C7/00—Control of nuclear reaction
- G21C7/30—Control of nuclear reaction by displacement of the reactor fuel or fuel elements
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Abstract
The application discloses a nuclear reactor reactivity control device, which comprises a reactor vessel, a reactor core assembly and an action control module; the reactor core assembly comprises a reactor core and a reactor core cladding wound on the periphery of the reactor core; the reactor core comprises an inner layer fuel assembly, an outer layer fuel assembly and a reflecting layer, wherein the outer layer fuel assembly and the reflecting layer sequentially surround the periphery of the inner layer fuel assembly; a plurality of control drums are annularly distributed in the reflecting layer; the reactor core is divided into a plurality of reactor core regions which are mutually independent by a plurality of clapboards in the cross section direction; the action control module comprises a plurality of action control mechanisms, and the reactor core region is driven by the action control mechanisms to reciprocate along the radial direction of the reactor core, so that the outer fuel assemblies in the reactor core region are far away from or close to the inner fuel assemblies, and the leakage or absorption of neutrons in the reactor core is regulated and controlled. The nuclear reactor reactivity control device provided by the application has a plurality of space reactor reactivity control means, and solves the problems of insufficient control of residual reactivity at the initial life of a reactor core and lack of passive reactivity control means.
Description
Technical Field
The application relates to the technical field of reactors, in particular to a nuclear reactor reactivity control device which is used for spaceflight and provides electric power for a deep space shuttle unmanned or little spacecraft of a shuttle mars or other small planets.
Background
The space nuclear power is an ideal power and energy source for human beings to conduct deep space exploration, space track freight and building star table bases. The characteristics of high energy density, high environmental adaptability, extremely low fuel consumption and the like of the nuclear power system relative to the traditional chemical power system are mainly benefited. In the foreseeable future, chemical rocket engines will be an ideal power source for near-earth space load launching due to their strong thrust output in a short time. However, deep space activities that are performed with the ground-near orbit as the starting point will depend more on the space power system. The space nuclear power system is used as one kind of space power system, the core module of the space nuclear power system is a space fission reactor, the reactor can be launched to a near-earth orbit by a chemical power rocket, and the on-orbit modular construction of the power system can be carried out according to the task requirement.
The reactivity control is a key control means for controlling the start and stop of the reactor, adjusting the power output and maintaining the normal running state, and is a basic guarantee for safely and smoothly implementing a space task. In order to ensure safe and reliable operation of a nuclear reactor, a corresponding system must be provided to perform reactive control and protection functions. The important function of the reactor reactivity control system is to ensure the safety of the reactor, and the control protection system can rapidly act to ensure the safe shutdown of the reactor in case of accidents or emergencies.
Space nuclear reactors typically use control drums arranged within a reflector for core reactivity control due to compactness considerations. Typically, 12 control drums are uniformly arranged around the core, each drum body being made of a reflective material (beryllium) and provided with a neutron absorber (B) over a 120 ° sector of the side of the drum 4 C) In that respect The control drum can freely rotate along the axis of the control drum, and when the reactor runs, the angle of the neutron absorber sector facing the reactor core is adjusted through rotation, so that the reactor reactivity is adjusted. However, such control methods are ubiquitousThe problems of insufficient control of residual reactivity at the initial stage of the service life of the reactor core, uneven radial heating, easy occurrence of blocking and the like. And the control drum is used as an active reactivity adjusting mechanism, and can cause complete loss of reactivity control capability under the condition of power failure or failure of control driving equipment of the control drum, so that the operation safety of the reactor and the spacecraft is greatly threatened. To compensate for the deficiencies of the control drum approach, it is necessary to introduce a reactivity control mechanism that has strong residual reactivity control capability and can act passively.
Therefore, the existing space reactor has a single reactivity control means, and a new technical scheme is urgently needed to solve the problems in the prior art.
Disclosure of Invention
The application provides a nuclear reactor reactivity control device, which is used for solving the problem that the passive safety of a reactor is insufficient due to the fact that the existing space reactor has a single reactivity control means.
In order to achieve the above object, the present application provides the following technical solutions:
the application provides a nuclear reactor reactivity control device, which comprises a reactor vessel, a reactor core assembly and an action control module, wherein the reactor core assembly is arranged in the reactor vessel;
the reactor core assembly comprises a reactor core and a reactor core cladding wound on the periphery of the reactor core; the reactor core comprises an inner layer fuel assembly, an outer layer fuel assembly and a reflecting layer, wherein the outer layer fuel assembly and the reflecting layer sequentially surround the periphery of the inner layer fuel assembly; a plurality of control drums are annularly distributed in the reflecting layer; a plurality of coolant channels are formed between the outer fuel assembly and the reflecting layer; the core is divided into a plurality of core regions independent of each other by a plurality of partition plates in the cross-sectional direction;
the action control module comprises a plurality of action control mechanisms, one action control mechanism is connected with one reactor core region, and the reactor core region is driven by the action control mechanisms to reciprocate along the radial direction of the reactor core, so that outer layer fuel assemblies in the reactor core region are far away from or close to inner layer fuel assemblies, and the leakage or absorption of neutrons in the reactor core is regulated and controlled.
Preferably, 12 control drums are uniformly distributed in the reflecting layer, the control drums are of a rod-shaped structure, the central axis of each control drum is parallel to the central axis of the reactor vessel, a neutron absorber is arranged on one side of the outer wall of each control drum and is distributed in one-third area of the outer wall of each control drum in a concentrated mode, when the control drums rotate along the central axis of the control drums, the neutron absorbers on the control drums gradually face the reactor core in a rotating mode, the control drums continue to rotate, the neutron absorbers on the control drums gradually deviate from the reactor core in a rotating mode, and the reactor core reactivity can be adjusted by adjusting the area of the neutron absorbers facing the reactor core.
Preferably, the inner fuel assembly comprises six inner fuel units distributed annularly, the outer fuel assembly comprises twelve outer fuel units distributed annularly, the cross sections of the inner fuel units and the outer fuel units are respectively in a hexagonal shape, and the inner fuel assembly and the outer fuel assembly are distributed in a honeycomb shape.
Preferably, the core is divided into four core regions independent of each other by four partition plates in the cross section direction, the cross section of each core region is a sector shape, and each core region comprises 3 outer fuel units, 3 control drums and a partial reflecting layer positioned between two adjacent partition plates; when the reactor core is geometrically changed due to thermal expansion, the four reactor core regions are respectively driven by the action control mechanisms connected with the reactor core regions to move outwards in the radial direction.
Preferably, the reactor vessel has a cylindrical structure, the core assembly has a cylindrical structure, and an active space of the operation control mechanism is formed between an outer wall of the core assembly and an inner wall of the reactor vessel.
Preferably, the action control mechanism comprises a thermal expansion cadmium rod, a stainless steel conducting rod, a wedge-shaped sliding block and a return spring, the thermal expansion cadmium rod is arranged along the axial direction of the reactor core and is close to the inner wall of the reactor vessel, one end of the stainless steel conducting rod is connected with the thermal expansion cadmium rod, the other end of the stainless steel conducting rod is connected with the wedge-shaped sliding block, and the return spring is arranged between the wedge-shaped sliding block and the inner wall of the reactor vessel.
Preferably, the wedge-shaped sliding block is provided with a slope-shaped connecting surface, and one end of the stainless steel conducting rod is connected to the slope-shaped connecting surface.
Preferably, in a cold reactor state, the outer fuel assemblies of the core region are pressed against the corresponding inner fuel assemblies under the action of the return springs; in the operation process of the reactor, the temperature of the reactor core rises, the thermal expansion cadmium rod expands when heated, the axial linear expansion of the thermal expansion cadmium rod is conducted to the wedge-shaped sliding block through the stainless steel conducting rod, the wedge-shaped sliding block moves outwards along the radial direction of the reactor core under the linear expansion action of the thermal expansion cadmium rod, the return spring is compressed, the wedge-shaped sliding block drives the reactor core area connected with the wedge-shaped sliding block to move outwards, the outer fuel assembly and the inner fuel assembly on the reactor core area are separated, the leakage of neutrons is increased, a coolant channel is formed among the fuel assemblies, and the absorption and slowing of neutrons by the coolant are enhanced.
Preferably, a slide rail matched with the wedge-shaped slide block is arranged on the bottom surface of the reactor container.
Preferably, one end of the core is provided with a plurality of control rods, and one control rod is connected with one inner fuel unit or one outer fuel unit in a plug-in mode.
Preferably, the control rod is of a columnar structure, a cladding is wound on the outer wall of the control rod, a first rack is arranged on the cladding, a second rack corresponding to the first rack is arranged on the inner layer fuel unit or the outer layer fuel unit which is connected with the control rod in an inserting and connecting mode, and the first rack and the second rack are both meshed with the gear; when the control rod is driven by external force to move downwards and inserted into the reactor core, the first rack on the control rod is meshed with the gear, the gear drives the second rack to move towards the direction opposite to the movement direction of the first rack after rotating, and the inner layer fuel unit or the outer layer fuel unit which is connected with the control rod in an inserting mode moves upwards under the driving of the second rack.
Preferably, the core cladding is a radiation shielding structure.
Preferably, the coolant channels are helioxenon coolant channels for conducting heat away from the core.
Compared with the prior art, the method has the following beneficial effects:
1. the nuclear reactor reactivity control device can be used for controlling the start and stop of a reactor in the operation process, controlling the critical state and adjusting the power. The reactor reactivity control device is provided with a reactor vessel, a reactor core assembly and an action control module, wherein the reactor core assembly and the action control module are arranged in the reactor vessel, the reactor core comprises inner layer fuel assemblies, and outer layer fuel assemblies and a reflecting layer which surround the inner layer fuel assemblies in sequence, the reactor core is divided into a plurality of mutually independent reactor core regions by a plurality of partition plates in the cross section direction, and the reactor core regions are driven by the action control mechanism to move back and forth along the radial direction of the reactor core so that the outer layer fuel assemblies in the reactor core regions are far away from or close to the inner layer fuel assemblies. When the outer fuel assembly in the reactor core area is far away from the inner fuel assembly, the gap between the outer fuel assembly and the inner fuel assembly in the reactor core area is increased, the coolant (helium xenon gas) is increased, the reactor reactivity is reduced, negative feedback is formed with the power and the temperature, and the negative feedback mechanism does not depend on an active mechanism, so that the important guarantee of the passive safety of the reactor is formed. Furthermore, a plurality of control drums are annularly distributed in the reflecting layer, the control drums can freely rotate along the axis of the control drums, and when the reactor runs, the reactor reactivity is adjusted by rotating the angle of the sector of the neutron absorber on the control drums towards the reactor core, so that the power of the reactor core is adjusted. Therefore, the nuclear reactor reactivity control device provided by the application has multiple space reactor reactivity control means, enhances the passive safety of the reactor, and improves the overall reliability of the reactor operation.
2. In addition to the two spatial reactor reactivity control means, the nuclear reactor reactivity control device provided by the application also provides another spatial reactor reactivity control means, the spatial reactor reactivity control means realizes the reactor core burnup compensation by arranging a plug-in control rod at one end of the reactor core, a first rack is arranged on the control rod, a second rack corresponding to the first rack is arranged on a fuel unit in the reactor core, and the first rack and the second rack are both meshed with a gear. When the reactivity inhibition is needed, the control rod is inserted downwards, the first rack on the control rod is meshed with the gear, the gear rotates to drive the second rack to move towards the direction opposite to the movement direction of the first rack, and the fuel unit connected with the control rod in an inserting mode moves upwards. The reactivity control scheme skillfully utilizes a gear structure to enable the control rod and the fuel assembly to move reversely at the same time, increases the control efficiency of the burnup effect, achieves the superposition of a dual reactivity control mode, realizes the burnup compensation of the reactor core, and solves the problem of insufficient control of the residual reactivity at the initial stage of the service life of the reactor core.
3. The utility model provides a diversified reactivity control scheme, this scheme is as the means of reactor normalized power regulation with the control drum, introduces extra surplus reactivity control system on this basis and aims at compensating the reactivity decline in the consumption process to and passive reactivity control system is as the reactor safety guarantee means under the condition that active reactivity control system became invalid. Residual reactivity control is achieved by an axially movable control rod scheme and passive reactivity control is achieved by a variable core geometry scheme driven by thermal expansion of the material. The three sets of independent control technologies are used for realizing the quick, safe and reliable adjustment of the basic control function of the space reactor.
4. The application provides a nuclear reactor reactivity control device, complements each other through three kinds of reactivity control methods, has formed the reliable control under the full life of reactor core reactivity, the full operating mode. Under the normal operation condition of the reactor, the control drum is used for carrying out normalized adjustment on the reactivity. Under normal operating conditions, the control rods are partially inserted into the core. When the fuel reaches a certain burnup depth, the control rod is lifted, and meanwhile, the inner-layer fuel assembly around the control rod is inserted into the reactor core downwards, so that the reactivity loss of the reactor core caused by burnup is compensated by introducing the positive reactivity; under the emergency working condition, the control rods are inserted into the reactor core downwards, and meanwhile, the surrounding inner-layer fuel assemblies are lifted upwards, so that the reactor core enters a deep subcritical state due to the large negative reactivity. Under the accident condition that the power rises sharply, even if the control drum and the control rods are all failed, the control mode of the variable reactor core geometry can still be driven by thermal expansion, the absorption rate and the leakage rate of neutrons are improved, the reactor core reactivity is effectively inhibited, and the safety of the reactor is ensured.
5. The reactor core power change of the nuclear reactor reactivity control device provided by the application is controlled by a control drum; the burnup effect is compensated by an axial control system, i.e. a reactivity control scheme in which the control rods and the fuel assemblies act in reverse through gears; the temperature change control is used as a part of inherent safety, when the temperature rises, an outer fuel assembly and an inner fuel assembly in a reactor core region are separated by a thermal expansion action mechanism consisting of a thermal expansion cadmium rod, a stainless steel conduction rod, a wedge-shaped sliding block and a return spring, so that negative reactivity is provided, and the reactivity is reduced. Therefore, the nuclear reactor reactivity control device provided by the application utilizes the thermal expansion effect brought by temperature change to form negative feedback between the reactor core reactivity and the power, the safety of the reactor is greatly improved by a passive regulation mode, and the efficiency and the reliability of reactivity control can be effectively improved by superposing integral triple reactivity control schemes.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required to be used in the embodiments will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts. It should be understood that the specific shapes, configurations and illustrations in the drawings are not to be construed as limiting, in general, the practice of the present application; for example, it is within the ability of those skilled in the art to make routine adjustments or further optimization of the add/drop/attribute division, specific shapes, positional relationships, connection manners, size ratios, etc. of certain elements (components) based on the technical concepts disclosed in the present application and the exemplary drawings.
Fig. 1 is a schematic structural diagram of a nuclear reactor reactivity control apparatus according to an embodiment of the present invention in a structurally disassembled state, in which a dotted line in a lower half of the diagram is used to assist in explaining a positional correspondence relationship between a core and a reactor vessel when the reactor vessel is installed, and a dotted line in an upper half of the diagram is used to assist in explaining a positional correspondence relationship between a control rod and one fuel unit in the core.
Fig. 2 is a schematic structural diagram illustrating a control rod of a nuclear reactor reactivity control apparatus and a fuel unit in a core of the nuclear reactor reactivity control apparatus, which are connected through a rack and pinion according to an embodiment.
Description of reference numerals:
1. an outer fuel assembly; 2. a coolant passage; 3. a control drum; 4. a reflective layer; 5. a partition plate; 6. a central control rod; 7. an inner fuel assembly; 8. a reactor vessel; 9. a thermally expanding cadmium rod; 10. a stainless steel conductive rod; 11. a wedge-shaped slider; 12. a return spring; 13. a core cladding; 14. an axial control rod; 15. a fuel unit; 16. a first rack; 17. a second rack; 18. a gear.
Detailed Description
The present application will be described in further detail below with reference to specific embodiments thereof, with reference to the accompanying drawings.
In the description of the present application: "plurality" means two or more unless otherwise specified. The terms "first", "second", "third", and the like in this application are intended to distinguish one referenced item from another without having a special meaning in technical connotation (e.g., should not be construed as emphasizing a degree or order of importance, etc.). The terms "comprising," "including," "having," and the like, are intended to be inclusive and mean "not limited to" (some elements, components, materials, steps, etc.).
In the present application, terms such as "upper", "lower", "left", "right", "middle", and the like are generally used for easy visual understanding with reference to the drawings, and are not intended to absolutely limit the positional relationship in an actual product. Changes in these relative positional relationships are also considered to be within the scope of the present disclosure without departing from the technical concepts disclosed in the present disclosure.
Example one
In the design of the reactor, a control rod can be adopted to realize a reactivity control method, namely, a material with a large neutron absorption cross section is adopted to prepare an absorption rod, and then the absorption rod is inserted into the reactor core through a transmission mechanism to absorb neutrons in the reactor core, so that the reactivity of the reactor core is reduced, and the function of safe shutdown is realized.
In order to allow the control rods to be reliably inserted into the core in the event of an accident, the control rod drive device is required to be able to insert the control rods into the core even in the event of a power loss, thereby ensuring the safety of the core. The traditional reactor mainly depends on the action of gravity, and when a control rod driving mechanism loses power, the control rods fall into a reactor core by utilizing the gravity of the control rods, so that the purpose of stopping the reactor passively (without depending on the external driving force of a system) is achieved.
For a conventional vertically arranged reactor, the drop of control rods into the core may be affected by the flow of coolant inside the core, buoyancy, etc., causing uncertainty in the insertion rate. For some special purpose reactors, the reactor core may not be in a vertical state under the normal operation condition, so that a control rod depending on the action of gravity cannot be smoothly inserted into the reactor core under the accident condition, the passive shutdown cannot be realized, and the reactivity safety cannot be met. Other passive principles are required to achieve control rod insertion and safety shutdown functions.
The embodiment of the application provides a nuclear reactor reactivity control device, and the nuclear reactor reactivity control device adopts a control rod to realize a reactivity control method. The following is a detailed description of the structure and the operation principle of the reactor reactivity control device.
The nuclear reactor reactivity control apparatus provided by the embodiment of the present application includes a reactor vessel 8 and a core assembly disposed in the reactor vessel 8. The reactor core assembly comprises a reactor core and a reactor core cladding 13 wound on the periphery of the reactor core; the reactor core comprises a central control rod 6, and an inner fuel assembly 7, an outer fuel assembly 1 and a reflecting layer 4 which are sequentially wound around the periphery of the central control rod 6; a plurality of control drums 3 are annularly distributed in the reflecting layer 4; a plurality of coolant passages 2 are formed between the outer fuel assembly 1 and the reflective layer 4.
12 control drums 3 are uniformly distributed in a reflecting layer 4 (neutron reflecting layer), the control drums 3 are of a rod-shaped structure, the central axis of each control drum 3 is parallel to the central axis of a central control rod 6, a neutron absorber is arranged on one side of the outer wall of each control drum 3, the neutron absorber is distributed in one-third area of the outer wall of each control drum 3 in a concentrated mode, when the control drums 3 rotate along the central axis of the control drums, the neutron absorber on each control drum is gradually rotated towards a reactor core, the control drums 3 continue to rotate, the neutron absorber on each control drum is gradually rotated away from the reactor core, and the reactivity of the reactor core is adjusted by adjusting the area of the neutron absorber facing the reactor core.
The inner fuel assembly 7 comprises six inner fuel units which are distributed annularly, the outer fuel assembly 1 comprises twelve outer fuel units which are distributed annularly, the cross sections of the inner fuel units and the outer fuel units are respectively hexagonal, and the inner fuel assembly 7 and the outer fuel assembly 1 are distributed in a honeycomb shape.
In one embodiment, one end of the core is provided with a plurality of control rods, and one control rod is in plug-in connection with one inner fuel unit or one outer fuel unit. Referring to fig. 1, a control rod is inserted into a fuel unit 15. The control rods are cylindrical in structure and are referred to as axial control rods 14 because they move axially along the core. Referring to fig. 2, a cladding is wound on the outer wall of the axial control rod 14, a first rack 16 is arranged on the cladding, a second rack 17 corresponding to the first rack 16 is arranged on the fuel unit 15 connected with the axial control rod 14 in an inserting manner, and both the first rack 16 and the second rack 17 are meshed with a gear 18; when the axial control rod 14 moves downwards and is inserted into the reactor core under the driving of external force, the first rack 16 on the axial control rod is meshed with the gear 18, the gear 18 rotates to drive the second rack 17 to move in the direction opposite to the movement direction of the first rack 16, and the fuel unit 15 connected with the axial control rod 14 in a plugging mode moves upwards under the driving of the second rack 17. When the reactivity inhibition is needed, the control rod is inserted downwards, the first rack on the control rod is meshed with the gear, the gear rotates to drive the second rack to move towards the direction opposite to the movement direction of the first rack, and the fuel unit 15 connected with the control rod in an inserting mode moves upwards.
According to the reactivity control scheme, the control rods and the fuel assemblies are linked through the gear structure, so that when the control rods at the top of the reactor core move, the fuel assemblies at corresponding positions can automatically move upwards without overlapping other control modes, and the probability of control strategy failure is reduced. The reactivity control scheme skillfully utilizes a gear structure to enable the control rod and the fuel assembly to move reversely at the same time, increases the control efficiency of the burnup effect, achieves the superposition of a dual reactivity control mode, is a residual reactivity control system, can compensate reactivity reduction in the burning process, and realizes the reactor core burnup compensation.
Example two
In an embodiment of the present invention, compared with the first embodiment of the nuclear reactor reactivity control apparatus, another reactivity control scheme is added to the first embodiment of the nuclear reactor reactivity control apparatus.
The nuclear reactor reactivity control apparatus according to the present embodiment further includes an operation control module, which is actually a thermal expansion operation mechanism. The reactor core of the reactor reactivity control device is divided into a plurality of independent core regions by a plurality of partition plates 5 in the cross-sectional direction. The action control module comprises a plurality of action control mechanisms, one action control mechanism is connected with one reactor core region, and the reactor core region is driven by the action control mechanisms to reciprocate along the radial direction of the reactor core, so that the outer fuel assemblies 1 in the reactor core region are far away from or close to the inner fuel assemblies 7, and the leakage or absorption of neutrons is realized. The structure of the reactor reactivity control apparatus will be described in detail with reference to fig. 1.
Referring to fig. 1, the core is divided into four core regions independent from each other by four partition plates 5 in the cross-sectional direction, each core region has a sector-shaped cross section and comprises 3 outer fuel units, 3 control drums 3 and a partial reflection layer 4 located between two adjacent partition plates 5; when the reactor core is geometrically changed due to thermal expansion, the four reactor core regions are respectively driven by the action control mechanisms connected with the reactor core regions to move outwards in the radial direction.
In one embodiment, the reactor vessel 8 is a cylindrical structure and the core assembly is a cylindrical structure, the central axis of the central control rod 6 coincides with the central axis of the reactor vessel 8, and a movable space of the motion control mechanism is formed between the outer wall of the core assembly and the inner wall of the reactor vessel 8.
In one embodiment, the action control mechanism comprises a thermal expansion cadmium rod 9, a stainless steel conductive rod 10, a wedge-shaped sliding block 11 and a return spring 12, wherein the thermal expansion cadmium rod 9 is arranged along the axial direction of the reactor core and close to the inner wall of the reactor vessel 8, one end of the stainless steel conductive rod 10 is connected with the thermal expansion cadmium rod 9, the other end of the stainless steel conductive rod is connected with the wedge-shaped sliding block 11, and the return spring 12 is arranged between the wedge-shaped sliding block 11 and the inner wall of the reactor vessel 8. During a particular installation, the return spring 12 may be placed laterally between the reactor vessel 8 and the wedge shoes 11. A slope-shaped connecting surface is arranged on the wedge-shaped sliding block 11, and one end of the stainless steel conducting rod 10 is connected to the slope-shaped connecting surface; the bottom surface of the reactor vessel 8 is provided with a slide rail adapted to the wedge-shaped slide block 11.
In a cold reactor state, the outer fuel assemblies 1 in the core region are tightly pressed on the corresponding inner fuel assemblies 7 under the action of the return springs 12; in the operation process of a reactor, the temperature of a reactor core rises, the thermal expansion cadmium rod 9 is heated to expand, the axial linear expansion of the thermal expansion cadmium rod is conducted to the wedge-shaped slide block 11 through the stainless steel conducting rod 10, the wedge-shaped slide block 11 moves outwards in the radial direction of the reactor core under the linear expansion action of the thermal expansion cadmium rod 9, the return spring 12 is compressed, the wedge-shaped slide block 11 drives a reactor core region connected with the wedge-shaped slide block to move outwards, an outer layer fuel assembly 1 and an inner layer fuel assembly 7 on the reactor core region are separated, the leakage of neutrons is increased, a coolant channel 2 is additionally arranged between the fuel assemblies, and the absorption and slowing of the neutrons by a coolant are enhanced.
In one embodiment, the core cladding 13 is a radiation shielding structure; the coolant channels 2 are helium xenon coolant channels, and the coolant channels 2 are used for conducting heat out of the core.
The nuclear reactor using the nuclear reactor reactivity control device can be used as a power source and a power source, the reactor is a fast neutron reactor, the reactor core is cooled by helium xenon gas, the heat of the reactor core is taken out by a coolant, and the thermoelectric conversion device is driven by a Brayton cycle to generate electricity.
In order to control the initial residual reactivity of the core and compensate for the reactivity of the fuel burnup, an axially movable control rod reactivity control system is provided centrally in the core, see fig. 1. In order to passively tune the reactor following power conditions, the core is designed to be of variable geometry, i.e. the core structure is altered by thermal expansion effects (outer 1 and inner 7 fuel assemblies are separated or packed in the core region), which in turn alters the leakage and absorption of neutrons in the core.
In general, the reactor core reactivity control system is composed of three sets of control schemes in total, and the specific working principle is described as follows:
1. the control drum is used as a means for regulating the normalized power of the reactor:
12 rod-shaped control drums are uniformly arranged in the reflecting layer on the periphery of the reactor core along the annular direction, and the control drums can rotate along the axis. The control drum is made of a reflecting material (beryllium), and a neutron absorber (B) is arranged on the 120-degree side sector 4 C) .1. The The reactivity of the reactor core can be adjusted by adjusting the area (angle) of the part of the absorber facing the reactor core, and then the power of the reactor core can be adjusted.
2. Residual reactivity control scheme for compensation of reactivity drop during burn-up:
the top of the reactor comprises a plurality of control rod assemblies from top to bottom, the control rod assemblies are cylindrical, a cladding is attached to the outside of the control rod assemblies, and racks are arranged on the cladding; the reactor core is provided with a movable fuel assembly, namely, a corresponding rack and a corresponding gear are arranged on a fuel unit which is connected with a control rod assembly in an inserting way, and the fuel assembly is in a hexagonal cylinder structure; when the reactivity is required to be inhibited, the control rod is inserted downwards, and the fuel assembly at the corresponding position moves upwards under the driving of the gear and the rack, so that the superposition of a dual reactivity control mode is achieved, and the dual reactivity control mode is used for compensating the fuel consumption of the reactor core.
3. A variable core geometry passive reactivity control scheme driven by material thermal expansion:
when the core is geometrically changed due to thermal expansion, the four core regions are taken as independent structures and can simultaneously move in the radial direction, the extension caused by the linear expansion of the cadmium rods of the thermal expansion actuating mechanism is converted into outward sliding in the radial direction by the wedge-shaped slide block, and the slide block pulls the core regions connected with the slide block to slide outward together. This sliding causes separation of the outer fuel assemblies from the inner fuel assemblies of the core, increasing neutron leakage. Meanwhile, a circulation pore passage of the helium xenon coolant between the fuel assemblies is increased, so that the new internal coolant is increased, and the absorption and the moderation of the coolant to neutrons are enhanced. The comprehensive effect is that the size of the reactor core becomes larger along with the increase of the temperature, and the reactivity of the reactor core is reduced to achieve the effect of negative reactivity feedback. Meanwhile, the reactor core cladding has a certain shielding effect on reactor core neutrons, irradiation damage of the reactor core neutrons to the thermal expansion action mechanism is reduced as much as possible, and the service life of the thermal expansion action mechanism is prolonged.
All the technical features of the above embodiments can be arbitrarily combined (as long as there is no contradiction between the combinations of the technical features), and for brevity of description, all the possible combinations of the technical features in the above embodiments are not described; these examples, which are not explicitly described, should be considered to be within the scope of the present description.
The present application has been described in considerable detail with reference to the foregoing general description and specific examples. It should be understood that several general adaptations or further innovations of these specific embodiments can also be made based on the technical idea of the present application; however, such conventional modifications and further innovations may also fall within the scope of the claims of the present application as long as they do not depart from the technical idea of the present application.
Claims (9)
1. A nuclear reactor reactivity control device is characterized by comprising a reactor vessel, a reactor core assembly arranged in the reactor vessel and an action control module;
the reactor core assembly comprises a reactor core and a reactor core cladding wound on the periphery of the reactor core; the reactor core comprises an inner layer fuel assembly, an outer layer fuel assembly and a reflecting layer, wherein the outer layer fuel assembly and the reflecting layer sequentially surround the periphery of the inner layer fuel assembly; a plurality of control drums are annularly distributed in the reflecting layer; a plurality of coolant channels are formed between the outer fuel assembly and the reflecting layer; the core is divided into a plurality of core regions independent of each other by a plurality of partition plates in the cross-sectional direction;
the action control module comprises a plurality of action control mechanisms, one action control mechanism is connected with one reactor core region, and the reactor core region is driven by the action control mechanisms to reciprocate along the radial direction of the reactor core, so that outer layer fuel assemblies in the reactor core region are far away from or close to inner layer fuel assemblies, and the leakage or absorption of neutrons in the reactor core is regulated and controlled.
2. The nuclear reactor reactivity control device according to claim 1, wherein 12 control drums are uniformly distributed in the reflecting layer, the control drums are rod-shaped structures, the central axes of the control drums are parallel to the central axis of the reactor vessel, a neutron absorber is arranged on one side of the outer wall of each control drum, the neutron absorber is intensively distributed in one third area of the outer wall of each control drum, when the control drums rotate along the central axes of the control drums, the neutron absorbers on the control drums gradually face the reactor core in a rotating mode, the control drums continue to rotate, the neutron absorbers on the control drums gradually face away from the reactor core in a rotating mode, and the reactor reactivity is adjusted by adjusting the area of the neutron absorbers facing the reactor core.
3. A nuclear reactor reactivity control apparatus according to claim 2, wherein the inner fuel assembly includes six annularly arranged inner fuel cells and the outer fuel assembly includes twelve annularly arranged outer fuel cells, the inner and outer fuel cells each having a hexagonal cross-section, the inner and outer fuel assemblies being arranged in a honeycomb pattern.
4. The nuclear reactor reactivity control apparatus according to claim 1 or 3, wherein the core is divided into four core regions independent of each other in a cross-sectional direction by four partition plates, each core region having a sector-shaped cross section and including 3 outer fuel units, 3 control drums, and a partially reflective layer between adjacent two partition plates; when the reactor core is geometrically changed due to thermal expansion, the four reactor core regions are respectively driven by the action control mechanisms connected with the reactor core regions to move outwards in the radial direction.
5. The nuclear reactor reactivity control apparatus according to claim 1, wherein the reactor vessel is a cylindrical structure, the core assembly is a cylindrical structure, and a movable space of the motion control mechanism is formed between an outer wall of the core assembly and an inner wall of the reactor vessel;
the action control mechanism comprises a thermal expansion cadmium rod, a stainless steel conducting rod, a wedge-shaped sliding block and a return spring, the thermal expansion cadmium rod is arranged along the axial direction of the reactor core and is close to the inner wall of the reactor vessel, one end of the stainless steel conducting rod is connected with the thermal expansion cadmium rod, the other end of the stainless steel conducting rod is connected with the wedge-shaped sliding block, and the return spring is arranged between the wedge-shaped sliding block and the inner wall of the reactor vessel;
the wedge-shaped sliding block is provided with a slope-shaped connecting surface, and one end of the stainless steel conducting rod is connected to the slope-shaped connecting surface.
6. The nuclear reactor reactivity control apparatus of claim 5, wherein in a cold reactor condition, outer fuel assemblies of the core region are compressed against corresponding inner fuel assemblies by a return spring; in the operation process of the reactor, the temperature of the reactor core rises, the thermal expansion cadmium rod expands when heated, the axial linear expansion of the thermal expansion cadmium rod is conducted to the wedge-shaped sliding block through the stainless steel conducting rod, the wedge-shaped sliding block moves outwards along the radial direction of the reactor core under the linear expansion action of the thermal expansion cadmium rod, the return spring is compressed, the wedge-shaped sliding block drives the reactor core area connected with the wedge-shaped sliding block to move outwards, the outer fuel assembly and the inner fuel assembly on the reactor core area are separated, the leakage of neutrons is increased, a coolant channel is formed among the fuel assemblies, and the absorption and slowing of neutrons by the coolant are enhanced.
7. The nuclear reactor reactivity control apparatus of claim 5, wherein the bottom surface of the reactor vessel is provided with slide rails adapted to the wedge shoes.
8. A nuclear reactor reactivity control apparatus according to claim 3, wherein one end of the core is provided with a plurality of control rods, one of the control rods being in plug-in connection with one of the inner or outer fuel units;
the control rod is of a columnar structure, a cladding is wound on the outer wall of the control rod, a first rack is arranged on the cladding, a second rack corresponding to the first rack is arranged on an inner layer fuel unit or an outer layer fuel unit which is in plug-in connection with the control rod, and the first rack and the second rack are both meshed with a gear; when the control rod is driven by external force to move downwards and inserted into the reactor core, the first rack on the control rod is meshed with the gear, the gear drives the second rack to move towards the direction opposite to the movement direction of the first rack after rotating, and the inner layer fuel unit or the outer layer fuel unit which is connected with the control rod in an inserting mode moves upwards under the driving of the second rack.
9. The nuclear reactor reactivity control apparatus according to claim 1,
the reactor core cladding is a radiation shielding structure;
the coolant channel is a helium xenon coolant channel for conducting heat away from within the core.
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| CN202211303226.XA CN115547521A (en) | 2022-10-24 | 2022-10-24 | Nuclear reactor reactivity control device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116130122A (en) * | 2023-01-18 | 2023-05-16 | 哈尔滨工程大学 | Automatic power control system for heat pipe cooling reactor |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116130122A (en) * | 2023-01-18 | 2023-05-16 | 哈尔滨工程大学 | Automatic power control system for heat pipe cooling reactor |
| CN116130122B (en) * | 2023-01-18 | 2023-08-11 | 哈尔滨工程大学 | Automatic power control system for heat pipe cooling reactor |
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