Heat preservation structure for control rod driving mechanism

Abstract

The utility model discloses a heat preservation structure for a control rod driving mechanism. The control rod driving mechanism comprises a sealing shell and a driving coil, the sealing shell defines a first sealing cavity for the control rod to move, and the driving coil is arranged on the outer side of the sealing shell and can be electromagnetically coupled with an internal component of the control rod driving mechanism so as to drive the control rod to move; the first heat insulator is located between the drive coil and the seal housing. According to the heat preservation structure, by arranging the first heat insulation piece, a heat transfer path between the sealing shell and the driving coil is blocked, so that heat reaching the driving coil is greatly reduced, and the temperature rise speed of the driving coil is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of nuclear energy, in particular to a heat preservation structure for a control rod driving mechanism. Background Art

[0002] The control rod drive mechanism (CRDM) is a servo mechanism in the control and safety systems of nuclear power plants. Its specific functions are to raise, lower, hold, or rapidly insert control rods to enable reactor startup, power regulation, power maintenance, reactor shutdown, and rapid thrust reduction in the event of an accident. It is a key component that directly impacts the normal operation, safety, and reliability of nuclear reactors.

[0003] Control rod drive mechanisms typically use electromagnetic coupling to move the control rods. However, due to heating from the reactor and the coils themselves, the operating temperature of the electromagnetic coils rapidly rises to over 300°C. The organic materials in existing coil components quickly decompose at temperatures above 300°C, easily causing the coils to loosen and break, compromising the operational safety of the reactor and nuclear power plant. Utility Model Content

[0004] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, it proposes a thermal insulation structure for a control rod drive mechanism. By providing a first thermal insulator, the structure blocks the heat transfer path between the sealed housing and the drive coil, reducing the temperature rise of the drive coil and the probability of decomposition of the coil insulation material.

[0005] According to an insulation structure for a control rod drive mechanism according to an embodiment of the first aspect of the present invention, the control rod drive mechanism includes a sealed shell and a drive coil. The sealed shell defines a first sealed cavity for movement of a control rod. The drive coil is disposed outside the sealed shell and is capable of electromagnetically coupling with internal components of the control rod to drive the control rod to move. The insulation structure includes a first thermal insulation member located between the drive coil and the sealed shell.

[0006] The thermal insulation structure according to the embodiment of the present invention has at least the following beneficial effects:

[0007] The thermal insulation structure of the present application is provided with a first thermal insulation member, which is wound around the sealed shell and located between the drive coil and the sealed shell. As a result, the heat transfer path between the sealed shell and the drive coil is blocked by the first thermal insulation member, and the heat reaching the drive coil is greatly reduced, thereby reducing the temperature rise rate of the drive coil. In the present application, by adding the first thermal insulation member between the drive coil and the sealed shell, the heat transfer from the sealed shell to the drive coil is reduced, so that when the drive coil has a certain working time, the maximum temperature value of its working cycle will also decrease, and the temperature of the drive coil can be controlled within a reasonable range, thereby reducing the probability of decomposition of the organic material of the drive coil and ensuring the safe operation of the reactor and nuclear power plant.

[0008] According to some embodiments of the present invention, the first thermal insulation member is formed by coating a thermal insulation coating, and the thermal insulation coating is coated on the inner circumference of the driving coil and / or the outer circumference of the sealing shell;

[0009] Alternatively, the first thermal insulation member is formed by winding a heat-insulating material, and the first thermal insulation member is laid on the inner circumference of the driving coil and / or covered on the outer circumference of the sealing shell.

[0010] According to some embodiments of the present invention, the sealed shell has a first end for connecting to the reactor pressure vessel, and the thermal insulation structure further includes a first thermal insulation component, which is coated on the outer peripheral surface of the first end.

[0011] According to some embodiments of the present invention, the first insulation component includes an arc-shaped first insulation portion and an arc-shaped second insulation portion, the first insulation portion and the second insulation portion are assembled to form an annular structure, and the annular structure is enclosed on the outer circumference of the first end.

[0012] According to some embodiments of the present invention, the first thermal insulation component is formed by thermal insulation material covering the outer peripheral surface of the first end, and the thermal insulation structure further includes a fastening member, which is used to fix the first thermal insulation component to the first end.

[0013] According to some embodiments of the present invention, the control rod drive mechanism further includes a rod travel sleeve and a rod position detector, wherein the rod travel sleeve defines a second sealed cavity for movement of the control rod, the rod travel sleeve is connected to the sealed housing, and the second sealed cavity is in communication with the first sealed cavity;

[0014] Wherein, the rod position detector is sleeved on the rod travel sleeve, and the heat insulation structure further includes a second heat insulation member, which is located between the outer circumference of the rod travel sleeve and the inner circumference of the rod position detector.

[0015] According to some embodiments of the present invention, the rod position detector has an opening at one end away from the sealed shell, and the heat preservation structure further includes a second heat preservation component, which is connected to the rod position detector to close the opening of the rod position detector.

[0016] According to some embodiments of the present invention, the control rod drive mechanism further includes a cable interface, and the cable interface is arranged on a side of the second heat insulation component away from the rod position detector.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0019] Figure 1 This is a schematic structural diagram of the heat preservation structure and the control rod drive mechanism of an embodiment of the present utility model;

[0020] Figure 2 This is a schematic diagram of the assembly of the sealing shell according to an embodiment of the present utility model;

[0021] Figure 3 This is a schematic diagram of the connection between the first end of the sealing shell and the top cover of the pressure vessel according to an embodiment of the utility model;

[0022] Figure 4 This is a schematic diagram of the assembly of the rod position detector and the rod travel sleeve according to an embodiment of the present utility model;

[0023] Figure 5 This is an enlarged schematic diagram of the top of the thermal insulation structure of an embodiment of the present utility model.

[0024] Reference numerals:

[0025] Sealed housing 100; first end 110;

[0026] First thermal insulation member 200; Second thermal insulation member 250;

[0027] Driving coil 300;

[0028] First heat-insulating member 400; Second heat-insulating member 450;

[0029] Rod travel sleeve 500; rod position detector 550; rod position coil 551;

[0030] Cable interface 600;

[0031] Pressure vessel 700. DETAILED DESCRIPTION

[0032] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0033] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0034] In the description of this utility model, "several" means more than one, "plurality" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of the terms "first" and "second" is solely for the purpose of distinguishing technical features and is not to be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0035] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0036] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0037] The control rod drive mechanism (CRDM) is a servo mechanism in the control and safety systems of nuclear power plants. Its specific functions are to raise, lower, hold, or rapidly insert control rods to enable reactor startup, power regulation, power maintenance, reactor shutdown, and rapid thrust reduction in the event of an accident. It is a key component that directly impacts the normal operation, safety, and reliability of nuclear reactors.

[0038] Control rod drive mechanisms typically use electromagnetic coupling to move the control rods. However, due to heating from the reactor and the coils themselves, the operating temperature of the electromagnetic coils rapidly rises to over 300°C. The organic materials in existing coil components quickly decompose at temperatures above 300°C, easily causing the coils to loosen and break, compromising the operational safety of the reactor and nuclear power plant.

[0039] To solve the above problems, the present application proposes a thermal insulation structure for a control rod drive mechanism, where the control rod drive mechanism is used to drive the control rods to move, and the thermal insulation structure is used to prevent the coil temperature from being too high.

[0040] Specifically, the control rod drive mechanism includes a sealed shell 100 and a drive coil 300. The sealed shell 100 defines a first sealed cavity (not shown in the figure). It can be understood that the first sealed cavity is a space for the control rod to move. Figure 1 and Figure 2 As shown, the drive coil 300 is arranged outside the sealed shell 100. The magnetic field generated by the drive coil 300 can penetrate the sealed shell 100, so that the drive coil 300 is electromagnetically coupled with the internal components of the control rod drive mechanism, thereby driving the control rod to move relative to the sealed shell 100 through the change of the magnetic field, thereby realizing the raising or lowering of the control rod.

[0041] The lower end of the sealed shell 100 is fixedly connected to the top cover of the pressure vessel 700 of the nuclear reactor, together forming a pressure boundary. The first sealed cavity is connected to the chamber in the pressure vessel 700. The heat in the nuclear reactor is dissipated through the sealed shell 100, thereby causing the temperature of the drive coil 300 to rise.

[0042] For this reason, Figure 2 As shown, the insulation structure is provided with a first thermal insulation member 200, which is wound around the sealed shell 100 and located between the drive coil 300 and the sealed shell 100, so that the heat transfer path between the sealed shell 100 and the drive coil 300 is blocked by the first thermal insulation member 200, and the heat reaching the drive coil 300 is greatly reduced, thereby reducing the temperature rise rate of the drive coil 300.

[0043] It is understandable that in the prior art, the temperature rise rate is relatively high. Under the condition of a certain working time, the temperature of the drive coil 300 is relatively high during the working cycle, which can easily cause the decomposition of organic materials in the drive coil 300. In the present application, by adding a first thermal insulation member 200 between the drive coil 300 and the sealed shell 100, the heat transfer from the sealed shell 100 to the drive coil 300 is reduced. As a result, under the condition of a certain working time, the maximum temperature of the drive coil 300 during its working cycle will also decrease, and the temperature of the drive coil 300 can be controlled within a reasonable range, thereby reducing the probability of decomposition of organic materials in the drive coil 300 and ensuring the safe operation of the reactor and nuclear power plant.

[0044] In some embodiments, the first thermal insulation member 200 is formed by coating with a thermal insulation coating. The thermal insulation coating can be an inorganic high-temperature-resistant spray-type thermal insulation coating, which is sprayed on the outer circumference of the sealed shell 100 or the inner circumference of the drive coil 300, thereby significantly reducing the heat transfer from the sealed shell 100 to the drive coil 300. Preferably, the thermal insulation coating is applied to the outer circumference of the sealed shell 100. It will be understood that the first thermal insulation member 200 formed by coating is relatively thin, which has little impact on the assembly of the drive coil 300 and the electromagnetic coupling effect between the drive coil 300 and the control rod.

[0045] In other embodiments, the first thermal insulation member 200 is formed by winding a thermal insulation material. The thermal insulation material may be an ultra-thin nanoporous thermal insulation material or an ultra-thin aerogel thermal insulation material, and may be coated on the outer circumference of the sealed shell 100 or laid on the inner circumference of the drive coil 300. It will be appreciated that the first thermal insulation member 200 formed by winding can have good thermal insulation performance, and the thermal insulation performance of the first thermal insulation member 200 can be adjusted by adjusting parameters such as the thickness of the thermal insulation material or the number of windings of the thermal insulation material.

[0046] In some embodiments, for the convenience of subsequent description, the end of the sealed shell 100 used for connection to the reactor pressure container is named the first end 110. In the prior art, the first end 110 of the sealed shell 100 is exposed to the air, and heat easily diffuses from this end to the air, causing a large amount of heat loss, thereby resulting in a low economic efficiency of the nuclear power plant reactor. Figure 3 As shown, the thermal insulation structure of the present application further includes a first thermal insulation component 400 , which is coated on the outer peripheral surface of the first end 110 .

[0047] It should be noted that the material of the first thermal insulation member 400 can be thermal insulation materials such as glass wool, silica nanoparticles, and aerogels. The thermal insulation material is coated on the outer peripheral surface of the first end 110 to form the first thermal insulation member 400. The thermal insulation structure also includes a tight hoop, which can be a metal wire, a binding belt, etc. After the first thermal insulation member 400 coats the sealed shell 100, it is fixedly connected by a tight hoop, etc., so that the first thermal insulation member 400 is fixedly connected to the first end 110. Alternatively, in other embodiments, the first thermal insulation member 400 includes an arc-shaped first thermal insulation portion and an arc-shaped second thermal insulation portion (not shown in the figure), and the first thermal insulation portion and the second thermal insulation portion are both prefabricated metal thermal insulation modules. The first thermal insulation portion and the second thermal insulation portion can be assembled to form an annular structure, which can be enclosed on the outer peripheral surface of the sealed shell 100. It is then fixed by a clamp, a metal binding belt, etc., thereby achieving thermal insulation of the first end 110 of the sealed shell 100.

[0048] In some embodiments, as Figure 1 and Figure 4 As shown, the control rod drive mechanism also includes a rod travel sleeve 500 and a rod position detector 550. The rod travel sleeve 500 defines a second sealed cavity (not shown) for movement of the control rod. The rod travel sleeve 500 is disposed at an end of the sealed housing 100 away from the pressure vessel 700 and is connected to the sealed housing 100, thereby connecting the second sealed cavity to the first sealed cavity. The control rod moves within the second sealed cavity and the first sealed cavity.

[0049] The rod position detector 550 is mounted on the rod travel sleeve 500 and equipped with a rod position coil 551. It detects the position of the control rod within the rod travel sleeve 500, converting the rod's mechanical displacement into an electrical quantity using the principle of electromagnetic induction. As the control rod moves up and down, the magnetized stainless steel section on its drive rod closes or opens the magnetic circuit of the rod position coil 551, thereby changing the induced electromotive force of each coil. Each movement of the control rod closes or opens the magnetic circuit of several coils, creating a unique information code. This position information code can be used to determine the rod position. By monitoring the control rod's position, precise control of reactor power can be achieved, ensuring safe operation.

[0050] To prevent heat dissipation from the second sealed cavity, which could overheat the rod position coil 551 or other components in the rod position detector 550, the insulation structure also includes a second thermal insulator 250. The second thermal insulator 250 is wound around the rod travel sleeve 500 and located between the outer circumference of the rod travel sleeve 500 and the inner circumference of the rod position detector 550. This reduces the amount of heat transferred from the rod travel sleeve 500 to the rod position coil 551, thereby lowering the temperature of the rod position coil 551. The second thermal insulator 250 can be made of an ultrathin nanoporous material or an ultrathin aerogel insulation material. The second thermal insulator 250 can be attached to the inner circumference of the rod position detector 550 and mounted within the rod travel sleeve 500 along with the rod position detector 550. Alternatively, the second thermal insulator 250 can be attached to the outer circumference of the rod travel sleeve 500 and installed within the control rod drive mechanism along with the rod travel sleeve 500. Alternatively, the second heat insulating member 250 may also be a separate cylindrical component, which is first mounted on the rod travel sleeve 500 before the rod position detector 550 is installed.

[0051] The rod position detector 550 is a cylindrical structure. Figure 4 As shown, an opening is formed at its upper end, and heat can easily escape from the opening to the environment, causing heat loss. To this end, the heat insulation structure of the present application also includes a second heat insulation member 450, such as Figure 5 As shown, the second insulation member 450 is plate-shaped and extends horizontally at the end of the rod position detector 550 away from the sealed housing 100. The second insulation member 450 is connected to the rod travel sleeve 500 or to the anti-vibration plate, thereby sealing the opening of the rod position detector 550 and reducing heat dissipation from the insulation structure.

[0052] Further, such as Figure 5 As shown, a cable interface 600 for connecting to a control cable is further provided at the top of the control rod drive mechanism. To prevent the temperature of the control cable from being too high, the cable interface 600 is provided on the side of the second thermal insulation component 450 away from the rod position detector 550, that is, the second thermal insulation component 450 is provided below the cable interface 600. Thus, the second thermal insulation component 450 can block the rise of heat and prevent the cable temperature from being too high.

[0053] Based on the foregoing, the insulation structure of the first embodiment of the present application is provided with a first insulation member 400 at the bottom, a first insulation member 200 and a second insulation member 250 in the middle, and a second insulation member 450 at the top, so that the pressure boundary of the control rod drive mechanism is basically covered by the insulation material, thereby achieving overall insulation of the control rod drive mechanism and reducing the heat dissipation of the control rod drive mechanism.

[0054] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various modifications can be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. In addition, the embodiments of the present invention and the features of the embodiments can be combined with each other unless there is a conflict.

Claims

1. A thermal insulation structure for a control rod drive mechanism, the control rod drive mechanism comprising a sealed housing and a drive coil, the sealed housing defining a first sealed cavity for movement of a control rod, the drive coil being disposed outside the sealed housing and capable of electromagnetically coupling with internal components of the control rod drive mechanism to drive movement of the control rod, characterized in that: The heat-insulating structure includes a first heat-insulating member, which is located between the driving coil and the sealed shell.

2. The heat insulation structure for a control rod drive mechanism according to claim 1, characterized in that: The first heat insulating member is formed by coating a heat-insulating coating, and the heat-insulating coating is coated on the inner circumference of the driving coil and / or the outer circumference of the sealing shell; Alternatively, the first thermal insulation member is formed by winding a heat-insulating material, and the first thermal insulation member is laid on the inner circumference of the driving coil and / or covered on the outer circumference of the sealing shell.

3. The heat insulation structure for a control rod drive mechanism according to claim 1, characterized in that: The sealed shell has a first end for connecting to the reactor pressure vessel. The thermal insulation structure further includes a first thermal insulation component, which is coated on the outer peripheral surface of the first end.

4. The heat insulation structure for a control rod drive mechanism according to claim 3, characterized in that: The first heat-insulating component includes an arc-shaped first heat-insulating portion and an arc-shaped second heat-insulating portion. The first heat-insulating portion and the second heat-insulating portion are assembled to form an annular structure. The annular structure is surrounded by an outer circumferential surface of the first end.

5. The heat insulation structure for a control rod drive mechanism according to claim 3, characterized in that: The first thermal insulation component is formed by covering the outer peripheral surface of the first end with a thermal insulation material. The thermal insulation structure further includes a fastening member, which is used to fix the first thermal insulation component to the first end.

6. The heat insulation structure for a control rod drive mechanism according to any one of claims 1 to 5, characterized in that: The control rod drive mechanism further includes a rod travel sleeve and a rod position detector, wherein the rod travel sleeve defines a second sealed cavity for movement of the control rod, the rod travel sleeve is connected to the sealed housing, and the second sealed cavity is in communication with the first sealed cavity; Wherein, the rod position detector is sleeved on the rod travel sleeve, and the heat insulation structure further includes a second heat insulation member, which is located between the outer circumference of the rod travel sleeve and the inner circumference of the rod position detector.

7. The heat insulation structure for a control rod drive mechanism according to claim 6, characterized in that: The rod position detector has an opening at one end away from the sealing shell, and the heat preservation structure further includes a second heat preservation member, which is connected to the rod position detector to close the opening of the rod position detector.

8. The heat insulation structure for a control rod drive mechanism according to claim 7, characterized in that: The control rod drive mechanism further includes a cable interface, which is arranged on a side of the second heat insulation component away from the rod position detector.

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