Control rod assembly

Abstract

The utility model provides a control rod assembly, and belongs to the technical field of nuclear reactor core control rod assemblys.The control rod assembly comprises a cladding, a first end plug, a second end plug and an absorber, the first end plug and the second end plug block openings in the two ends of the cladding respectively, and the absorber is limited in the cladding through the first end plug and the second end plug; the variable-diameter section is arranged on the cladding, so that the wall thickness of the variable-diameter section is increased from the first end to the second end, the wear resistance of the cladding is improved under the condition that an external structure is not increased, and the control rod cladding is prevented from continuously abrading with a reactor internal component guide structure under the action of flow-induced vibration when the control rod stays at a fixed axial position for a long time; therefore, the control rod is prevented from wear-through damage and the structural integrity of the control rod is ensured.

Description

Technical Field

[0001] This application belongs to the technical field of nuclear reactor core control rod assembly, specifically relating to a control rod assembly. Background Technology

[0002] The reactor core mainly consists of fuel assemblies, control rod assemblies, fixed related assemblies, and structural and experimental components placed inside the reactor. The main function of the control rod assembly is to act as a neutron absorber, moving within the reactor core via a drive system to control core reactivity, enabling reactor startup, normal shutdown, regulation and maintenance of reactor power, and ensuring reactor safety under accident conditions. However, under flow-induced vibration, the control rod assembly is prone to wear against the internal structures, affecting its structural integrity and service life. Utility Model Content

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related technologies.

[0004] In view of this, a control rod assembly is provided according to an embodiment of this application. The control rod assembly includes a control rod, which includes:

[0005] The shell is a hollow cavity with openings at both ends. A variable diameter section is provided on the shell, and the wall thickness of the variable diameter section increases from the first end of the shell to the second end of the shell.

[0006] The first end plug is located at the first end of the casing;

[0007] The second end plug is disposed at the second end of the shell, and the second end plug, the first end plug, and the inner wall of the shell form a receiving cavity.

[0008] The absorber is disposed in the receiving cavity.

[0009] In one feasible implementation, the wall thickness of the variable diameter section increases uniformly from the first end of the cladding to the second end of the cladding.

[0010] In one feasible implementation, the casing is tubular, with a uniform outer diameter at all points, and the inner diameter of the variable-diameter section decreases from the first end of the casing to the second end.

[0011] In one feasible implementation, the control stick further includes:

[0012] An elastic element is disposed within the receiving cavity and is located between the absorber and the first end plug. The first end of the elastic element is in contact with the end face of the first end plug, and the second end of the elastic element is in contact with the end face of the absorber.

[0013] In one feasible implementation, the first end plug is welded to the first end of the shell for sealing, and the second end plug is welded to the second end of the shell for sealing, thereby sealing the receiving cavity.

[0014] In one feasible implementation, the absorber is made of boron carbide material.

[0015] In one feasible implementation, the absorber is manufactured by high-temperature isostatic pressing sintering.

[0016] In one feasible implementation, the absorber consists of several boron carbide core blocks.

[0017] In one feasible implementation, the control rod assembly further includes:

[0018] A connecting handle is connected to the first end of the control rod via a connector, and the connecting handle is set parallel to the axis of the control rod.

[0019] In one feasible implementation, the connecting handle is connected to the first end of the control rod via a star-shaped frame; the control rod assembly includes several control rods arranged in parallel to each other, with each control rod corresponding to a wing plate of the star-shaped frame, so that the control rods are distributed in a star shape.

[0020] The control rod assembly of this application has the following advantages compared with the prior art:

[0021] The control rod assembly provided in this application includes a cladding, a first end plug, a second end plug, and an absorber. The first end plug and the second end plug respectively seal the openings at both ends of the cladding to confine the absorber inside the cladding. By providing a variable diameter section on the cladding, the wall thickness of the variable diameter section increases from the first end to the second end. Without increasing the external structure, the wear resistance of the cladding is improved, preventing continuous erosion of the control rod cladding against the reactor internal component guide structure under the action of flow-induced vibration when the control rod remains in a fixed axial position for a long time. This prevents the control rod from being worn through and damaged, and ensures the structural integrity of the control rod. Attached Figure Description

[0022] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0023] Figure 1 A schematic structural diagram of a control rod assembly according to an embodiment of this application;

[0024] Figure 2 A schematic structural diagram of the variable diameter section of a control rod assembly according to one embodiment of this application;

[0025] Figure 3 A schematic structural diagram of a control rod assembly at a first angle according to an embodiment of this application;

[0026] Figure 4 A schematic structural diagram of a control rod assembly at a second angle according to an embodiment of this application;

[0027] in, Figures 1 to 4 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0028] 11. Control rod; 12. Connecting handle; 13. Connecting piece; 14. Variable diameter section;

[0029] 111. Shell; 112. First end plug; 113. Second end plug; 114. Absorbent body; 115. Elastic element. Detailed Implementation

[0030] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0032] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0033] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0034] like Figure 1 and Figure 2 As shown, according to an embodiment of this application, a control rod assembly is proposed. The control rod assembly includes a control rod 11, which includes a shell 111, a first end plug 112, a second end plug 113, and an absorber 114. The shell 111 is a hollow cavity with openings at both ends. A variable diameter section 14 is provided on the shell 111, and the wall thickness of the variable diameter section 14 increases from the first end of the shell 111 to the second end of the shell 111. The first end plug 112 is provided at the first end of the shell 111. The second end plug 113 is provided at the second end of the shell 111, and the second end plug 113, the first end plug 112, and the inner wall of the shell 111 form a receiving cavity. The absorber 114 is disposed in the receiving cavity.

[0035] The control rod assembly provided in this application includes a cladding 111, a first end plug 112, a second end plug 113, and an absorber 114. The first end plug 112 and the second end plug 113 respectively block the openings at both ends of the cladding 111, so as to confine the absorber 114 inside the cladding 111 through the first end plug 112 and the second end plug 113. By providing a variable diameter section 14 on the cladding 111, the wall thickness of the variable diameter section 14 increases from the first end to the second end, thereby improving the wear resistance of the cladding 111 without increasing the external structure. This prevents the control rod 11 from being continuously eroded by the cladding 111 under the action of flow-induced vibration when the control rod 11 is in a fixed axial position for a long time, thus preventing the control rod 11 from being worn through and damaged, and ensuring the structural integrity of the control rod 11.

[0036] It is understandable that the axial position of the second end of the casing 111 is fixed, that is... Figure 1 In the reactor, the lower end of the cladding 111 is subjected to the impact of the coolant flow for a long time, which causes the second end of the cladding 111 to undergo micro-vibration wear due to collision and / or tangential sliding with the guide mechanism. By increasing the thickness of the variable diameter section 14 at the second end of the cladding 111, the wear resistance of the cladding 111 is improved, and local wear through the cladding 111 is avoided.

[0037] Furthermore, a nitriding layer is provided on the outer wall of the cladding 111 to further improve the wear resistance of the cladding 111. As a preferred embodiment, the nitriding layer is formed by ion nitriding treatment of the cladding 111.

[0038] Specifically, the casing 111 is made of stainless steel.

[0039] like Figure 2As shown, in one feasible embodiment, the wall thickness of the variable diameter section 14 increases uniformly from the first end of the casing 111 to the second end of the casing 111.

[0040] In this technical solution, the wall thickness of the variable diameter section 14 increases uniformly from the first end of the casing 111 to the second end of the casing 111, so that the wall thickness of the variable diameter section 14 changes uniformly, and the wear resistance of the variable diameter section 14 is consistent in all circumferential directions at the same axial position, preventing local damage to the variable diameter section 14 and improving the overall wear resistance of the casing 111.

[0041] Furthermore, such as Figure 2 In the middle, the inner wall of the variable diameter section 14 is a conical surface.

[0042] like Figure 2 As shown, in one feasible embodiment, the casing 111 is tubular, with a consistent outer diameter at all points, and the inner diameter of the variable diameter section 14 decreases from the first end of the casing 111 to the second end of the casing 111.

[0043] In this technical solution, the outer diameter of the cladding 111 is consistent. By changing the inner diameter of the variable diameter section 14 of the cladding 111, the wall thickness of the cladding 111 is changed, that is, the outer diameter of the cladding 111 remains unchanged. Without changing the size of the fuel assembly guide tube, the control rod 11 can be smoothly guided into the hydraulic buffer section of the guide tube. There is no need to adjust other reactor structures, ensuring the compatibility of the control rod 11 with the original reactor structures and ensuring the smoothness of the control rod assembly installation.

[0044] like Figure 1 As shown, in one feasible embodiment, the control rod 11 further includes an elastic element 115, which is disposed in the receiving cavity and located between the absorber 114 and the first end plug 112. The first end of the elastic element 115 is in contact with the end face of the first end plug 112, and the second end of the elastic element 115 is in contact with the end face of the absorber 114.

[0045] In this technical solution, the elastic element 115 and the absorber 114 are arranged in the receiving cavity. The elastic element 115 is squeezed by the first end plug 112 and the absorber 114, and the restoring force of the elastic element 115 is used to press the absorber 114 tightly, preventing the absorber 114 from axially moving inside the shell 111 during transportation and operation, and reserving expansion space for the absorber 114 to ensure the reliability of the operation of the control rod 11.

[0046] Furthermore, the elastic element 115 provides a clamping force to the absorber 114.

[0047] Specifically, the elastic element 115 is a helical spring.

[0048] like Figure 1As shown, in one feasible embodiment, the first end plug 112 is welded to the first end of the shell 111 for sealing, and the second end plug 113 is welded to the second end of the shell 111 for sealing, so that the receiving cavity is sealed.

[0049] In this technical solution, the casing 111 is filled with an inert gas as a heat-conducting gas. The two ends of the casing 111 are sealed with a first end plug 112 and a second end plug 113, respectively, to seal the inert gas in the containment cavity and prevent gas leakage, so as to improve the thermal conductivity of the control rod 11 itself through the heat conduction of the inert gas.

[0050] In this technical solution, the control rod 11 absorbs neutrons through the absorber 114 to control the rate of nuclear reaction. The filling of inert gas helps to improve the thermal conductivity of the control rod 11 itself, thereby improving the thermal conductivity of the control rod 11. This ensures that the heat generated by the control rod 11 when absorbing neutrons can be quickly transferred to the coolant, preventing the control rod 11 from overheating, ensuring the safe operation of the reactor, and improving the thermal efficiency and safety of the entire system.

[0051] Understandably, the chemical inertness of inert gases makes them less likely to react with other substances, thus ensuring the stability and reliability of the control rod 11.

[0052] As a preferred option, helium is used as the heat-conducting gas.

[0053] In one feasible implementation, the absorber 114 is made of boron carbide material.

[0054] In this technical solution, boron carbide is used as the material for the absorber 114. Boron carbide has a wide neutron absorption energy spectrum and a large thermal neutron absorption cross section. Using it as the material for absorber 114 is beneficial to increasing the shutdown margin. In addition, the high melting point of boron carbide is beneficial to improving the accident resistance performance of control rod 11 and improving the reliability of control rod 11 operation.

[0055] In this technical solution, the boron carbide absorber 114 has 10 Boolean isotopes have advantages such as high absorption cross-section, low material cost, easy processing, and low radioactivity after irradiation.

[0056] In one feasible implementation, the absorber 114 is manufactured by high-temperature isostatic pressing sintering.

[0057] In this technical solution, the absorber 114 is sintered by high temperature isostatic pressing. High temperature isostatic pressing does not require the addition of sintering agent and can subject the material to isotropic pressure, resulting in a uniform microstructure of the boron carbide absorber 114 and a high density and good quality finished boron carbide absorber 114.

[0058] Understandably, condensed 10B can increase the absorption cross-section of natural boron. The boron carbide absorber 114 is sintered from boron carbide powder. In the boron carbide absorber 114... 10 The enrichment level of B is determined based on the requirements of the reactor core design.

[0059] In one feasible implementation, the absorber 114 is composed of a plurality of boron carbide core blocks.

[0060] In this technical solution, the absorber 114 is composed of sintered boron carbide core blocks. Dispersing the absorbent material in multiple core blocks allows for more uniform distribution of neutron absorption throughout the entire reactor core, improving control precision. Furthermore, the total amount of neutrons absorbed can be adjusted by changing the insertion depth of different core blocks, facilitating more precise control of the reactor's power and reactivity. When a core block is damaged or its performance degrades, the core block can be replaced individually without replacing the entire control rod 11, which helps reduce the manufacturing and processing costs of the absorber 114.

[0061] like Figure 3 As shown, in one feasible embodiment, the control rod assembly further includes a connecting handle 12, which is connected to the first end of the control rod 11 via a connector 13, and the connecting handle 12 is arranged parallel to the axis of the control rod 11.

[0062] In this technical solution, the control rod 11 and the connecting handle 12 are connected by the connector 13 to form a control rod assembly. The connecting handle 12 provides mechanical support for the control rod assembly. By making the connecting handle 12 parallel to the axis of the control rod 11, the movement of the entire control rod assembly is guided by controlling the connecting handle 12, so that the control rod assembly can move up and down precisely in the reactor, thereby enabling each control rod 11 to quickly reach the correct position in the reactor.

[0063] Understandably, by connecting the connecting handle 12 to the drive system, the position of the control rod assembly can be precisely controlled in normal operation and emergency situations, thereby ensuring the reliability of the control rod assembly and the safety of the reactor.

[0064] like Figure 3 and Figure 4 As shown, in one feasible embodiment, the connecting handle 12 is connected to the first end of the control rod 11 via a star-shaped frame; the control rod assembly includes a plurality of control rods 11 arranged in parallel with each other, and the control rods 11 correspond one-to-one with the wing plates of the star-shaped frame, so that the control rods 11 are distributed in a star shape.

[0065] In this technical solution, the control rod 11 is connected to the star frame, and the connecting handle 12 is connected to the star frame, so that the control rod 11, the star frame and the connecting handle 12 form an integral structure. The wing plates of the star frame correspond one-to-one with the control rod 11 to position the control rod 11 and provide cushioning when the control rod assembly falls, which is beneficial to the stable positioning of the control rod 11 and also helps to reduce the impact on the fuel assembly.

[0066] In this technical solution, the star-shaped frame structure design also helps to quickly insert the control rod 11 in an emergency to achieve rapid reactor shutdown. The elastic element 115 absorbs the impact energy when the control rod 11 falls, protecting the fuel assembly and the control rod assembly.

[0067] Furthermore, the first end plug 112 of the control rod 11 is provided with threads, and the first end plug 112 is threadedly connected to the star bracket to detachably connect the control rod 11 to the star bracket; the second end plug 113 of the control rod 11 is bullet-shaped to reduce the resistance when the control rod 11 falls, so that the control rod 11 can be smoothly introduced into the hydraulic buffer section of the fuel assembly guide tube.

[0068] Specifically, the control rod assembly consists of a connecting handle 12, a connector 13, and 24 control rods 11, ensuring that the control rod assembly as a whole has neutron absorption capability and efficiency.

[0069] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0070] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A control rod assembly, characterized in that, The control rod assembly includes a control rod, the control rod comprising: The shell is a hollow cavity with openings at both ends, and the shell is provided with a variable diameter section, the wall thickness of which increases from the first end of the shell to the second end of the shell; A first end plug is disposed at the first end of the casing; The second end plug is disposed at the second end of the shell, and the second end plug, the first end plug, and the inner wall of the shell form a receiving cavity; An absorber is disposed in the receiving cavity.

2. A control rod assembly according to claim 1, characterized in that, The wall thickness of the variable diameter section increases uniformly from the first end of the casing to the second end of the casing.

3. A control rod assembly according to claim 1, characterized in that, The casing is tubular, with a uniform outer diameter at all points, and the inner diameter of the variable-diameter section decreases from the first end of the casing to the second end.

4. A control rod assembly according to claim 1, characterized in that, The control rod also includes: An elastic element is disposed within the receiving cavity and is located between the absorbent and the first end plug. The first end of the elastic element is in contact with the end face of the first end plug, and the second end of the elastic element is in contact with the end face of the absorbent.

5. A control rod assembly according to claim 1, characterized in that, The first end plug is welded to the first end of the shell for sealing, and the second end plug is welded to the second end of the shell for sealing, thereby sealing the receiving cavity.

6. A control rod assembly according to claim 1, characterized in that, The absorber is made of boron carbide.

7. A control rod assembly according to claim 6, characterized in that, The absorber is manufactured by high-temperature isostatic pressing sintering.

8. A control rod assembly according to claim 6, characterized in that, The absorber is composed of several boron carbide core blocks.

9. A control rod assembly according to any one of claims 1 to 8, characterized in that, The control rod assembly also includes: A connecting handle is provided, which is connected to the first end of the control rod via a connector, and the connecting handle is arranged parallel to the axis of the control rod.

10. A control rod assembly according to claim 9, characterized in that, The connecting handle is connected to the first end of the control rod via a star-shaped bracket; The control rod assembly includes several control rods arranged in parallel to each other, and each control rod corresponds one-to-one with the wing plate of the star-shaped frame, so that the control rods are distributed in a star shape.

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