Control rod drive mechanism and its seal shell, manufacturing method of seal shell

Abstract

The embodiment of the present application discloses a control rod drive mechanism and a sealing shell thereof and a manufacturing method of the sealing shell, wherein the control rod drive mechanism comprises the sealing shell, a hook claw assembly and a coil assembly. The hook claw assembly is accommodated in a cavity of the sealing shell; the coil assembly is arranged outside the sealing shell and is used for generating a magnetic field to drive the hook claw assembly to act; wherein the sealing shell has a first part and a second part, the first part is located outside the magnetic field and the second part is located inside the magnetic field when the coil assembly generates the magnetic field, the material of the first part is austenitic stainless steel, and the magnetic conductivity of the material of the second part is better than that of the austenitic stainless steel. According to the present application, the magnetic resistance between the hook claw assembly and the coil assembly is reduced.

Description

Technical Field

[0001] This application relates to the field of nuclear engineering technology, and in particular to a control rod drive mechanism and its sealing shell, and a method for manufacturing the sealing shell. Background Technology

[0002] The CRDM (Control Rod Drive Mechanism) is a vertically stepping magnetic lifting device installed on the top cover of a reactor pressure vessel to control reactor startup, power regulation, and shutdown.

[0003] The CRDM (Crew Detector Die) mainly consists of a sealing shell, a claw assembly, a coil assembly, a drive rod, and a rod position detector. The sealing shell, mounted on the pressure vessel's top cover, is a crucial component of the CRDM. The interior of the sealing shell provides installation and operational space for the claw assembly and drive rod, while the exterior provides support for the coil assembly and rod position detector. As the primary pressure boundary, the sealing shell must maintain its integrity to ensure no coolant leakage. The coil assembly is the power source for the CRDM, and the claw assembly is its actuator. By applying current and discharging to the coil assembly, the corresponding magnetic pole armature in the claw assembly is magnetized / demagnetized, achieving the attraction / distraction of the magnetic pole armature and thus actuating the CRDM.

[0004] In existing technologies, the sealing shell is made of austenitic stainless steel. Due to the poor magnetic permeability of austenitic stainless steel, the magnetic resistance between the claw assemblies and coil assemblies installed on both the inner and outer sides of the sealing shell is relatively high. When the coil assembly is energized, the current flowing through it is relatively large, resulting in significant heat generation. Since the coil assembly has a specific temperature resistance rating, existing solutions employ a top-mounted forced ventilation system to remove the heat generated by the coil assembly and ensure the safe operation of the CRDM. However, top-mounted forced ventilation systems are complex and mostly welded structures, significantly increasing manufacturing, operation, and maintenance costs. Summary of the Invention

[0005] Embodiments of this application provide a control rod drive mechanism and its sealing shell, and a method for manufacturing the sealing shell, to reduce the magnetic resistance between the claw assembly and the coil assembly.

[0006] To address the aforementioned technical problems, embodiments of this application disclose the following technical solutions:

[0007] On one hand, a control rod driving mechanism is provided, which includes a sealed shell, a claw assembly, and a coil assembly. The claw assembly is housed in the cavity of the sealed shell; the coil assembly is disposed outside the sealed shell and is used to generate a magnetic field to drive the claw assembly to move; wherein, the sealed shell has a first part and a second part, and when the coil assembly generates a magnetic field, the first part is located outside the magnetic field and the second part is located inside the magnetic field, the first part is made of austenitic stainless steel, and the second part is made of a material with better magnetic permeability than austenitic stainless steel.

[0008] In addition to one or more of the features disclosed above, or as an alternative, the material of the second part is martensitic stainless steel.

[0009] In addition to one or more of the features disclosed above, or as an alternative, the first and second parts are welded together.

[0010] In addition to one or more of the features disclosed above, or as an alternative, the sealing shell is cylindrical, the coil assembly is sleeved outside the sealing shell, and the second part is arranged in a complete circle around the circumference of the sealing shell.

[0011] In addition to one or more of the features disclosed above, or as an alternative, the number of hook assemblies, coil assemblies and second parts are multiple and correspond one-to-one, with multiple hook assemblies spaced apart along the axial direction of the sealing shell, and the first part and the second part alternately arranged along the axial direction of the sealing shell.

[0012] On the other hand, a sealing shell for a control rod drive mechanism is further disclosed. The cavity of the sealing shell is used to accommodate the claw assembly of the control rod drive device, and the outer side of the sealing shell is used to install the coil assembly of the control rod drive device. The coil assembly is used to generate a magnetic field to drive the claw assembly to move. The sealing shell has a first part and a second part. When the coil assembly generates a magnetic field, the first part is located outside the magnetic field and the second part is located inside the magnetic field. The material of the first part is austenitic stainless steel, and the material of the second part has better magnetic permeability than austenitic stainless steel.

[0013] In addition to one or more of the features disclosed above, or as an alternative, the material of the second part is martensitic stainless steel.

[0014] In addition to one or more of the features disclosed above, or as an alternative, the first and second parts are welded together.

[0015] In addition to one or more of the features disclosed above, or as an alternative, the sealing shell is elongated cylindrical, with the second part forming a complete circumference around the sealing shell.

[0016] In addition to one or more of the features disclosed above, or as an alternative, there may be multiple second parts, with the first and second parts alternating along the axial direction of the sealing shell.

[0017] On the other hand, a method for manufacturing a sealing shell for a control rod drive mechanism is further disclosed. The cavity of the sealing shell is used to accommodate the claw assembly of the control rod drive device, and the outer side of the sealing shell is used to install the coil assembly of the control rod drive device. The coil assembly is used to generate a magnetic field to drive the claw assembly to move. The sealing shell has a first part and a second part welded together. When the coil assembly generates a magnetic field, the first part is located outside the magnetic field and the second part is located inside the magnetic field. The material of the first part is austenitic stainless steel, and the material of the second part is martensitic stainless steel. The method for manufacturing the sealing shell includes the following steps: providing the first part and the second part; depositing a layer of nickel-based welding material on the end face to be welded of the second part; and welding the first part and the second part together.

[0018] In addition to one or more of the features disclosed above, or as an alternative, after the step of depositing a layer of nickel-based welding material on the weldable end face of the second part and before the step of welding the first part and the second part together, the method further includes: processing a first bevel on the nickel-based welding material on the weldable end face of the second part, and processing a second bevel on the weldable end face of the first part.

[0019] One of the above technical solutions has the following advantages or beneficial effects: In this technical solution, the first part of the sealing shell located outside the magnetic field is still made of austenitic stainless steel, while only the second part of the sealing shell located inside the magnetic field is made of a material with better magnetic permeability than austenitic stainless steel, which generally ensures the stability of the sealing shell and reduces the magnetic resistance between the hook assembly and the coil assembly. Attached Figure Description

[0020] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0021] Figure 1 This is a cross-sectional structural schematic diagram of a control rod driving mechanism according to an embodiment of this application;

[0022] Figure 2 yes Figure 1 The front view of the sealing shell in the control rod drive mechanism shown;

[0023] Figure 3 This is a schematic diagram of the welding process of the first and second parts provided in the embodiments of this application;

[0024] Figure 4 This is a flowchart of the manufacturing method of the sealing shell provided in the embodiments of this application. Detailed Implementation

[0025] To make the objectives, technical solutions, and beneficial effects of this application clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, further clarifies this application. It should be understood that the specific embodiments described in this specification are merely for explaining this application and are not intended to limit it.

[0026] 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," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are 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, and therefore should not be construed as a limitation of this application. 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 indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" 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, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction 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.

[0028] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature.

[0029] This indicates that the level of the first feature is less than that of the second feature.

[0030] The CRDM (Control Rod Drive Mechanism) is a vertically stepping magnetic lifting device installed on the top cover of a reactor pressure vessel to control reactor startup, power regulation, and shutdown.

[0031] The CRDM mainly consists of a sealing shell, a claw assembly, a coil assembly, a drive rod, and a rod position detector. The sealing shell, mounted on the pressure vessel's top cover, is a crucial component of the CRDM. The interior of the sealing shell provides installation and operational space for the claw assembly and drive rod, while the exterior provides support for the coil assembly and rod position detector. As the primary pressure boundary, the sealing shell must maintain its integrity to ensure no coolant leakage. The coil assembly is the power source for the CRDM, and the claw assembly is its actuating mechanism. By applying current and discharge to the coil assembly, the corresponding magnetic pole armature in the claw assembly is magnetized / demagnetized, achieving the attraction / distraction of the magnetic pole armature and thus actuating the CRDM. The specific structure of the CRDM can be found in Chinese Patent Publication No. CN107945890A, and will not be described in detail here.

[0032] In the prior art, the sealing shell is made of austenitic stainless steel. Due to the poor magnetic permeability of austenitic stainless steel, the magnetic resistance between the hook assembly and the coil assembly installed on the inner and outer sides of the sealing shell is relatively large.

[0033] In this application, the first part of the sealing shell located outside the magnetic field is still made of austenitic stainless steel, while only the second part of the sealing shell located inside the magnetic field is made of a material with better magnetic permeability than austenitic stainless steel. This largely ensures the stability of the sealing shell and reduces the magnetic resistance between the claw assembly and the coil assembly.

[0034] Please see Figure 1 and Figure 2 , Figure 1 This is a cross-sectional structural schematic diagram of a control rod drive mechanism according to an embodiment of this application. Figure 2 yes Figure 1 The front view of the sealing shell 1 in the control rod drive mechanism shown.

[0035] The control rod drive mechanism includes a sealed housing 1, a hook assembly 2, and a coil assembly 3. Of course, the control rod drive mechanism also includes a drive rod and a rod position detector, etc., but since these are not related to the technical problem to be solved in this application, they will not be described in detail here.

[0036] The sealing shell 1 has a cavity 103. In the illustrated embodiment, the sealing shell 1 is elongated cylindrical, and the dotted line L in the figure represents the axis of the sealing shell 1. The sealing shell 1 is mainly used to enclose the claw assembly 2. This application does not limit the specific shape of the sealing shell 1. In addition to the elongated cylindrical shape, the sealing shell 1 can also adopt other shapes, such as a circular shell shape.

[0037] The hook assembly 2 is housed in the cavity 103 of the sealing shell 1. Specifically, there are multiple hook assemblies 2, which are spaced apart along the axial direction of the sealing shell 1. The structures of each hook assembly 2 can be the same or different. For ease of description, the multiple hook assemblies 2 are distinguished by different reference numerals. The multiple hook assemblies 2 are designated as hook assemblies 2a, 2b, and 2c. The number of hook assemblies 2 is not limited to three; it can be set as needed, such as two, four, etc.

[0038] A coil assembly 3 is disposed outside the sealing shell 1 and is used to generate a magnetic field to drive the claw assembly 2 to move. In the illustrated embodiment, the coil assembly 3 is sleeved outside the sealing shell 1, generating a magnetic field around the sealing shell 1. In other embodiments, the coil assembly 3 may not be sleeved outside the sealing shell 1 as needed, but may be disposed on one side of the sealing shell 1. There are multiple coil assemblies 3, and each coil assembly 3 corresponds one-to-one with a claw assembly 2. The structures of each coil assembly 3 may be the same or different. Each coil assembly 3 is used to generate a magnetic field to drive the corresponding claw assembly 2 to move. For ease of description, the multiple coil assemblies 3 are distinguished by different reference numerals. The multiple coil assemblies 3 are coil assemblies 3a, 3b, and 3c. Coil assembly 3a is used to generate a magnetic field to drive the claw assembly 2a to move. Coil assembly 3b is used to generate a magnetic field to drive the claw assembly 2b to move. Coil assembly 3c is used to generate a magnetic field to drive the claw assembly 2c to move.

[0039] The sealing shell 1 has a first portion 101 and a second portion 102. When the coil assembly 3 generates a magnetic field, the first portion 101 is located outside the magnetic field, and the second portion 102 is located inside the magnetic field. The first portion 101 is positioned relative to the coil assembly 3, while the second portion 102 is not positioned relative to the coil assembly 3. Viewed from the outside, the first portion 101 is obscured by the coil assembly 3, while the second portion 102 is exposed to the coil assembly 3. The magnetic field generated by the coil assembly 3 passes through the first portion 101 and acts on the claw assembly 2.

[0040] The number and position of the second part 102 are determined by the number and position of the coil assembly 3. Specifically, there are multiple second parts 102, and each second part 102 corresponds one-to-one with either the coil assembly 3 or the hook assembly 2.

[0041] Since the coil assembly 3 is sleeved outside the sealing shell 1, correspondingly, the second part 102 is arranged in a full circle around the sealing shell 1.

[0042] There are multiple first parts 101. First parts 101 and second parts 102 are alternately arranged along the axial direction of the sealing shell 1. The multiple first parts 101 are designated as first parts 101a, 101b, 101c, and 101d. The multiple second parts 102 are designated as second parts 102a, 102b, and 102c. Second part 102a is located between the coil assembly 3a and the hook assembly 2a. Second part 102b is located between the coil assembly 3b and the hook assembly 2b. Second part 102c is located between the coil assembly 3c and the hook assembly 2c.

[0043] The material of Part 101 is austenitic stainless steel (such as 06Cr18Ni11Nb). Austenitic stainless steel has good stability and is usually used in sealing shells 1.

[0044] The magnetic conductivity of the material in Part 2, 102, is superior to that of austenitic stainless steel. For example, the material in Part 2, 102, could be martensitic stainless steel.

[0045] In this embodiment, the first part 101 of the sealing shell 1 located outside the magnetic field is still made of austenitic stainless steel, while only the second part 102 of the sealing shell 1 located inside the magnetic field is made of a material with better magnetic permeability than austenitic stainless steel. This largely ensures the stability of the sealing shell 1, while reducing the magnetic resistance between the hook assembly 2 and the coil assembly 3.

[0046] The sealing shell 1 has strict sealing requirements. Therefore, in this embodiment, the first part 101 and the second part 102 are welded together. Of course, this application is not limited to this. In other embodiments, the first part 101 and the second part 102 can also be cast as a single piece.

[0047] Since the first part 101 and the second part 102 are dissimilar metals, and the sealing shell 1 has high requirements for sealing performance, this application also provides a method for manufacturing the sealing shell 1 in order to enable the first part 101 and the second part 102 to be welded together effectively. This manufacturing method is used to manufacture the sealing shell 1 of the above embodiments.

[0048] Please see Figure 3 and Figure 4 , Figure 3 This is a schematic diagram of the welding process in Part 101 and Part 102 of this application. Figure 4 This is a flowchart of the manufacturing method of the sealing shell 1 provided in the embodiments of this application.

[0049] The manufacturing method of the sealing shell 1 includes the following steps.

[0050] Step S101: Provide a first part 101 and a second part 102. The first part 101 is made of austenitic stainless steel, and the second part 102 is made of martensitic stainless steel.

[0051] Step S102: Deposit a layer of nickel-based welding material 104 onto the end face to be welded in the second part 102.

[0052] Step S103: A first bevel 105 is machined on the nickel-based welding material 104 on the welding end face of the second part 102, and a second bevel 106 is machined on the welding end face of the first part 101. This step is not mandatory. The shapes of the first bevel 105 and the second bevel 106 can be set as needed.

[0053] Step S104: Weld the first part 101 and the second part 102 together to form a welded connection layer 107.

[0054] Since the first part 101 and the second part 102 are made of different materials, this method first deposits nickel-based welding material 104 on the second part 102, which is beneficial to better bonding of the first part 101 and the second part 102.

[0055] Please see Figure 2 Specifically, using the manufacturing method described above, Figure 2 The manufacturing process of the sealing shell shown is as follows:

[0056] A. Parts preparation:

[0057] Process the first part 101a, the second part 102a, the first part 101b, the second part 102b, the first part 101c, the second part 101c and the first part 101d.

[0058] B. Welding:

[0059] According to the manufacturing method described above, the second part 102c and the first part 101d are welded together;

[0060] According to the manufacturing method described above, the first part 101c and the second part 102c are welded together;

[0061] According to the manufacturing method described above, the second part 102b and the first part 101c are welded together;

[0062] According to the manufacturing method described above, the first part 101b and the second part 102b are welded together;

[0063] According to the manufacturing method described above, the second part 102a and the first part 101b are welded together;

[0064] According to the manufacturing method described above, the first part 101a and the second part 102a are welded together.

[0065] C. Verification:

[0066] A hydrostatic test was conducted, and each weld was inspected for liquid penetration, requiring no defects.

[0067] In summary, the control rod drive mechanism, its sealing shell, and the manufacturing method of the sealing shell provided in this application can reduce the magnetic resistance between the claw assembly and the coil assembly.

[0068] The above steps are provided only to help understand the method, structure, and core ideas of this application. Those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A control rod drive mechanism, characterized in that, include: Sealed shell; A claw assembly, wherein the claw assembly is housed in the cavity of the sealed housing; A coil assembly, disposed outside the sealed housing, is used to generate a magnetic field to drive the claw assembly to move; The sealing shell has a first part and a second part. When the coil assembly generates the magnetic field, the first part is located outside the magnetic field and the second part is located inside the magnetic field. The first part is made of austenitic stainless steel, and the second part is made of a material with better magnetic permeability than austenitic stainless steel. There are multiple hook assemblies, coil assemblies, and second parts, and they correspond one-to-one. Multiple hook assemblies are spaced apart along the axial direction of the sealing shell. There are multiple first parts, and the first part and the second part are alternately arranged along the axial direction of the sealing shell.

2. The control rod drive mechanism as described in claim 1, characterized in that, The material of the second part is martensitic stainless steel.

3. The control rod drive mechanism as described in claim 1, characterized in that, The first part and the second part are welded together as one unit.

4. The control rod drive mechanism as described in claim 1, characterized in that, The sealing shell is long and cylindrical, the coil assembly is sleeved on the outside of the sealing shell, and the second part is arranged in a complete circle around the circumference of the sealing shell.

5. A sealing shell for a control rod drive mechanism, characterized in that, include: A sealed housing, the cavity of which is used to house the claw assembly of the control rod drive device, and the outer side of the sealed housing is used to mount the coil assembly of the control rod drive device, the coil assembly being used to generate a magnetic field to drive the claw assembly to move; The sealing shell has a first part and a second part, and there are multiple first parts and second parts. The first part and the second part are alternately arranged along the axial direction of the sealing shell. When the coil assembly generates the magnetic field, the first part is located outside the magnetic field and the second part is located inside the magnetic field. The material of the first part is austenitic stainless steel, and the magnetic permeability of the material of the second part is better than that of the austenitic stainless steel.

6. The sealing housing of the control rod drive mechanism as described in claim 5, characterized in that, The material of the second part is martensitic stainless steel.

7. The sealing housing of the control rod drive mechanism as described in claim 5, characterized in that, The first part and the second part are welded together as one unit.

8. The sealing housing of the control rod drive mechanism as described in claim 5, characterized in that, The sealing shell is long and cylindrical, and the second part is arranged in a complete circle around the circumference of the sealing shell.

9. A method for manufacturing a sealing shell for a control rod drive mechanism, wherein the cavity of the sealing shell is used to accommodate a claw assembly of a control rod drive device, and a coil assembly of the control rod drive device is mounted outside the sealing shell, the coil assembly being used to generate a magnetic field to drive the claw assembly to move, the sealing shell having a first part and a second part welded together, the number of the first part and the second part being multiple, the first part and the second part being alternately arranged along the axial direction of the sealing shell; when the coil assembly generates the magnetic field, the first part is located outside the magnetic field, and the second part is located inside the magnetic field, the first part being made of austenitic stainless steel, and the second part being made of martensitic stainless steel, characterized in that... The method for manufacturing the sealing shell includes the following steps: Provide the first part and the second part; A layer of nickel-based welding material is deposited on the end face to be welded in the second part; The first part and the second part are welded together.

10. The method for manufacturing the sealing shell of the control rod drive mechanism as described in claim 9, characterized in that, After the step of depositing a layer of nickel-based welding material on the end face to be welded in the second part, and before the step of welding the first part and the second part together, the method further includes: A first bevel is machined on the nickel-based welding material on the welding end face of the second part, and a second bevel is machined on the welding end face of the first part.

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