Steam generator secondary side metal foreign object cutting tool and extraction method

Abstract

This invention specifically relates to a tool for cutting off metal foreign objects on the secondary side of a steam generator, comprising an electrical discharge machining (EDM) mechanism, a flexible conveying mechanism, and a clamping mechanism. The flexible conveying mechanism is used to transport the EDM mechanism and the clamping mechanism to the tube compartment where the metal foreign object is located on the secondary side of the steam generator. The flexible conveying mechanism is connected to both the EDM mechanism and the clamping mechanism. When the clamping mechanism clamps the metal foreign object on the secondary side of the steam generator, the EDM mechanism, the flexible conveying mechanism, and the clamping mechanism form a discharge circuit, and the EDM mechanism processes and cuts the metal foreign object on the secondary side of the steam generator. This invention also relates to a method for removing metal foreign objects from the secondary side of a steam generator. This cutting tool cuts the metal foreign object on the secondary side of the steam generator into several segments without damaging the tube sheet and heat transfer tubes, making the clamped foreign object loose and allowing for segment-by-segment removal.

Description

Technical Field

[0001] This invention relates to the field of foreign object inspection technology on the secondary side of steam generators, and in particular to a tool and method for cutting off and removing metal foreign objects on the secondary side of a steam generator. Background Technology

[0002] The steam generator is a heat exchange device between the primary and secondary loops of a nuclear power plant. It is a critical component of the primary loop pressure boundary, directly impacting the plant's economic efficiency and safety. During manufacturing, installation, commissioning, and operation, foreign objects, especially metallic objects, can enter the secondary side of the steam generator for various reasons and become scattered in the outer ring corridor, central tube corridor, and tube bundles. This poses a risk of tube rupture to the heat transfer tubes, affecting their safety and reliability. Given the potentially serious consequences of foreign objects on the secondary side of the steam generator, their removal is a crucial part of the maintenance and management of nuclear power plant steam generators.

[0003] Foreign objects on the secondary side of a steam generator can be categorized into two types: loose foreign objects and clamped foreign objects. Loose foreign objects can be removed using specialized foreign object removal tools such as alligator pliers, three-jaw tongs, magnets, thimble rings, and vacuum cleaners. Existing experience indicates that clamped foreign objects on the secondary side of a steam generator are generally wire-like metal objects wrapped around or stuck between heat transfer tubes. Because clamped foreign objects are wrapped around the heat transfer tubes, they cannot be removed using currently available foreign object removal tools. Summary of the Invention

[0004] Therefore, it is necessary to provide a cutting tool and removal method for metal foreign objects on the secondary side of a steam generator, which addresses the problem that existing foreign object removal tools cannot clamp foreign objects on the secondary side of the steam generator. This cutting tool can cut the metal foreign objects on the secondary side of the steam generator into several segments without damaging the tube sheet and heat transfer tubes, thus making the clamped foreign objects loose and removing them segment by segment.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A tool for cutting off metal foreign objects on the secondary side of a steam generator includes an electrical discharge machining (EDM) mechanism, a flexible conveying mechanism, and a clamping mechanism. The flexible conveying mechanism is used to convey the EDM mechanism and the clamping mechanism to the pipe compartment where the metal foreign object is located on the secondary side of the steam generator. The flexible conveying mechanism is connected to both the EDM mechanism and the clamping mechanism. When the clamping mechanism clamps the metal foreign object on the secondary side of the steam generator, the EDM mechanism, the flexible conveying mechanism, and the clamping mechanism form a discharge circuit, and the EDM mechanism processes and cuts the metal foreign object on the secondary side of the steam generator.

[0007] Furthermore, the flexible conveying mechanism includes a first flexible conveying mechanism and a second flexible conveying mechanism. The first flexible conveying mechanism is used to convey the EDM (Electrical Discharge Machining) mechanism to the pipe compartment where the metal foreign object is located on the secondary side of the steam generator. The second flexible conveying mechanism is used to convey the clamping mechanism to the pipe compartment where the metal foreign object is located on the secondary side of the steam generator. The first flexible conveying mechanism is connected to the EDM mechanism, and the second flexible conveying mechanism is connected to the clamping mechanism. When the clamping mechanism clamps the metal foreign object on the secondary side of the steam generator, the EDM mechanism, the first flexible conveying mechanism, the second flexible conveying mechanism, and the clamping mechanism form a discharge circuit, and the EDM mechanism processes and shears the metal foreign object on the secondary side of the steam generator.

[0008] Furthermore, the first flexible conveying mechanism includes a head conveying mechanism, a head insertion tube assembly, and a first handle. The head conveying mechanism is used to be fixedly connected to the hand hole of the steam generator. The head insertion tube assembly passes through the head conveying mechanism and extends out of both ends of the head conveying mechanism. The end of the head insertion tube assembly away from the steam generator is connected to the first handle.

[0009] Furthermore, the second flexible conveying mechanism includes a second handle and a workpiece insertion tube assembly, the second handle being connected to the workpiece insertion tube assembly, which is inserted into the tube space where the metal foreign object on the secondary side of the steam generator is located.

[0010] Furthermore, the electrical discharge machining mechanism includes a control cable, an electrical discharge machine, and a tool head with internal electrode plates. One end of the control cable is connected to the electrical discharge machine, and the other end of the control cable is connected to a control handle. The tool head is connected to the end of the head insertion tube assembly near the steam generator.

[0011] Furthermore, the EDM machine is equipped with a metal foreign object processing and shearing program, which controls the feeding and discharging of the electrode plates inside the tool head to complete the processing and shearing of metal foreign objects on the secondary side of the steam generator.

[0012] Furthermore, a tensioning mechanism is provided on the tool head. When the direction of the tool head insertion into the tube assembly is determined, the tensioning mechanism expands to fix the position of the tool head.

[0013] Furthermore, the clamping mechanism includes a clamp with internally arranged electrode plates and a negative cable. The clamp is connected to the end of the workpiece insertion tube assembly near the steam generator, one end of the negative cable is connected to the end of the workpiece insertion tube assembly away from the steam generator, and the other end of the negative cable is connected to an EDM machine.

[0014] Furthermore, the secondary side metal foreign object cutting tool of the steam generator also includes a high-pressure water flushing mechanism, which is connected to the end of the workpiece insertion tube assembly away from the steam generator.

[0015] Furthermore, the high-pressure water rinsing mechanism includes a water pipe and a water supply mechanism. One end of the water pipe is connected to the end of the workpiece insertion pipe assembly away from the steam generator, and the other end of the water pipe is connected to the water supply mechanism.

[0016] Furthermore, the metal foreign object processing shearing program controls the activation of the water supply mechanism. During the electrical discharge machining process, the metal foreign object processing shearing program activates the water supply mechanism, which sprays processing fluid into the processing area to rinse away the waste residue.

[0017] The present invention also provides a method for removing metal foreign objects from the secondary side of a steam generator, comprising the following steps: using a flexible conveying mechanism to send an electrical discharge machining (EDM) mechanism and a clamping mechanism into the steam generator; using an endoscope to observe that the electrodes in the EDM mechanism and the clamping mechanism reach the position of the metal foreign object on the secondary side of the steam generator; the clamping mechanism clamps the metal foreign object on the secondary side of the steam generator to form a discharge circuit; and the EDM mechanism is activated to process and cut off the metal foreign object on the secondary side of the steam generator.

[0018] Furthermore, the method for removing metallic foreign objects from the secondary side of the steam generator includes the following steps:

[0019] The head conveying mechanism is fixed on the hand hole of the steam generator. With the assistance of the head conveying mechanism, the head insertion tube assembly enters the tube space where the metal foreign object is located on the secondary side of the steam generator. The direction of the head insertion tube assembly is adjusted by the first handle so that the electrode inside the tool head is aligned with the metal foreign object on the secondary side of the steam generator. A processing gap is reserved. The tensioning mechanism on the tool head expands to fix the position of the tool head.

[0020] The workpiece insertion tube assembly extends into the tube space where the metal foreign object is located on the secondary side of the steam generator, and the front clamp clamps the metal foreign object on the secondary side of the steam generator.

[0021] The EDM machine is started, and the metal foreign object processing and shearing program installed on the EDM machine controls the feeding and discharging of the electrode plates inside the tool head to complete the processing and shearing of the metal foreign object on the secondary side of the steam generator.

[0022] During the processing and shearing of metal foreign objects on the secondary side of the steam generator, the metal foreign object processing and shearing program installed on the EDM machine controls the start of the water supply mechanism to spray processing fluid into the processing area and rinse the waste residue in the processing area.

[0023] Beneficial technical effects of the present invention:

[0024] The present invention provides a tool and method for cutting off and removing metal foreign objects on the secondary side of a steam generator, which enables the application of electric spark technology to cut off metal foreign objects on the secondary side of the steam generator in a confined area; the heat transfer tubes and tube sheets are not damaged during the cutting process; the cutting tool is small in size, and its size is not significantly related to the size of the metal foreign object on the secondary side of the steam generator, making it highly applicable to different metal foreign objects on the secondary side of the steam generator. Attached Figure Description

[0025] Figure 1 A schematic diagram of a metal foreign object cutting tool for the secondary side of a steam generator;

[0026] Wherein: 1-Steam generator, 2-Head conveying mechanism, 3-Head insertion tube assembly, 4-First handle, 5-Control cable, 6-EDM machine, 7-Tool head, 8-Clamping clamp, 9-Metallic foreign object, 10-Negative cable, 11-Second handle, 12-Water pipe, 13-Water supply mechanism, 14-Workpiece insertion tube assembly. Detailed Implementation

[0027] In the description of this invention, it should be understood that the terms "left end", "right end", "above", "below", "outer side", "inner side", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this invention 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 invention.

[0028] See Figure 1 This embodiment provides a tool for cutting off metal foreign objects on the secondary side of a steam generator, including an electrical discharge machining (EDM) mechanism, a flexible conveying mechanism, and a clamping mechanism. The flexible conveying mechanism is used to convey the EDM mechanism and the clamping mechanism to the pipe compartment where the metal foreign object 9 on the secondary side of the steam generator 1 is located. The flexible conveying mechanism is connected to the EDM mechanism and the clamping mechanism. When the clamping mechanism clamps the metal foreign object 9 on the secondary side of the steam generator 1, the EDM mechanism, the flexible conveying mechanism, and the clamping mechanism form a discharge circuit, and the EDM mechanism processes and cuts the metal foreign object 9 on the secondary side of the steam generator 1.

[0029] In this embodiment, the flexible conveying mechanism includes a first flexible conveying mechanism and a second flexible conveying mechanism. The first flexible conveying mechanism is used to convey the electrical discharge machining (EDM) mechanism to the pipe compartment where the metal foreign object 9 is located on the secondary side of the steam generator 1. The second flexible conveying mechanism is used to convey the clamping mechanism to the pipe compartment where the metal foreign object 9 is located on the secondary side of the steam generator 1. The first flexible conveying mechanism is connected to the EDM mechanism, and the second flexible conveying mechanism is connected to the clamping mechanism. When the clamping mechanism clamps the metal foreign object 9 on the secondary side of the steam generator 1, the EDM mechanism, the first flexible conveying mechanism, the second flexible conveying mechanism, and the clamping mechanism form a discharge circuit, and the EDM mechanism performs processing and shearing on the metal foreign object 9 on the secondary side of the steam generator 1.

[0030] In this embodiment, the first flexible conveying mechanism includes a head conveying mechanism 2, a head insertion tube assembly 3, and a first handle 4. The head conveying mechanism 2 is used to be fixedly connected to the hand hole of the steam generator 1. The head insertion tube assembly 3 passes through the head conveying mechanism 2 and extends out of both ends of the head conveying mechanism 2. The end of the head insertion tube assembly 3 away from the steam generator 1 is connected to the first handle 4.

[0031] In this embodiment, the second flexible conveying mechanism includes a second handle 11 and a workpiece insertion tube assembly 14. The second handle 11 is connected to the workpiece insertion tube assembly 14, and the workpiece insertion tube assembly 14 is inserted into the tube space where the metal foreign object 9 on the secondary side of the steam generator 1 is located.

[0032] In this embodiment, the electrical discharge machining mechanism includes a control cable 5, an electrical discharge machine 6, and a tool head 7 with internal electrode plates. One end of the control cable 5 is connected to the electrical discharge machine 6, and the other end of the control cable 5 is connected to the first handle 4. The tool head 7 is connected to the end of the head insertion tube assembly 3 near the steam generator 1.

[0033] In this embodiment, a metal foreign object processing and shearing program is installed on the EDM machine 6. The metal foreign object processing and shearing program completes the processing and shearing of the metal foreign object 9 on the secondary side of the steam generator 1 by controlling the feed and discharge of the electrode plate inside the tool head 7.

[0034] In this embodiment, a tensioning mechanism is provided on the tool head 7. When the direction of the insertion of the tool head into the tube assembly 3 is determined, the tensioning mechanism expands to fix the position of the tool head 7.

[0035] In this embodiment, the clamping mechanism includes a clamp 8 with an internal electrode plate and a negative cable 10. The clamp 8 is connected to the end of the workpiece insertion tube assembly 14 near the steam generator 1, and one end of the negative cable 10 is connected to the end of the workpiece insertion tube assembly 14 away from the steam generator 1. The other end of the negative cable 10 is connected to the EDM machine 6.

[0036] In this embodiment, the secondary side metal foreign object cutting tool of the steam generator further includes a high-pressure water flushing mechanism, which is connected to the end of the workpiece insertion tube assembly 14 away from the steam generator 1.

[0037] In this embodiment, the high-pressure water rinsing mechanism includes a water pipe 12 and a water supply mechanism 13. One end of the water pipe 12 is connected to the end of the workpiece insertion tube assembly 14 away from the steam generator 1, and the other end of the water pipe 12 is connected to the water supply mechanism 13.

[0038] In this embodiment, the metal foreign object processing shearing program controls the start of the water supply mechanism 13. During the electrical discharge machining process, the metal foreign object processing shearing program starts the water supply mechanism 13, and the water supply mechanism 13 sprays processing fluid into the processing area to rinse the waste residue in the processing area.

[0039] The following are the steps for using the above-mentioned secondary-side metal foreign object cutting tool for steam generators:

[0040] The head conveying mechanism 2 is fixed on the hand hole of the steam generator 1. With the assistance of the head conveying mechanism 2, the head insertion tube assembly 3 enters the tube space where the secondary metal foreign object 9 of the steam generator 1 is located. The direction of the head insertion tube assembly 3 is adjusted by the first handle 4 so that the electrode in the tool head 7 is aligned with the secondary metal foreign object 9 of the steam generator 1, leaving a processing gap. The tensioning mechanism on the tool head 7 expands to fix the position of the tool head.

[0041] The workpiece insertion tube assembly 14 extends into the tube space where the secondary metal foreign object 9 of the steam generator 1 is located, and the front clamp 8 clamps the secondary metal foreign object 9 of the steam generator 1.

[0042] Start the EDM machine 6. The metal foreign object processing and shearing program installed on the EDM machine 6 controls the feeding and discharge of the electrode plates inside the tool head 7 to complete the processing and shearing of the metal foreign object 9 on the secondary side of the steam generator 1.

[0043] During the processing and shearing of the metal foreign object 9 on the secondary side of the steam generator 1, the metal foreign object processing and shearing program installed on the EDM machine 6 controls the start of the water supply mechanism 13 to spray processing fluid into the processing area and rinse the waste residue in the processing area.

[0044] This embodiment also provides a method for removing metal foreign objects from the secondary side of a steam generator. The metal foreign object 9 on the secondary side of the steam generator 1 is cut into small pieces that are easy to remove using electrical discharge machining, and then removed piece by piece using a removal tool.

[0045] In this embodiment, the method for removing the secondary metal foreign object from the steam generator includes the following steps: using a flexible conveying mechanism to send the electrical discharge machining (EDM) mechanism and the clamping mechanism into the steam generator; using an endoscope to observe that the electrodes in the EDM mechanism and the clamping mechanism reach the position of the secondary metal foreign object 9 in the steam generator 1; the clamping mechanism clamps the secondary metal foreign object 9 in the steam generator 1 to form a discharge circuit; and the EDM mechanism starts processing to cut off the secondary metal foreign object 9 in the steam generator 1.

[0046] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A tool for cutting off metallic foreign objects on the secondary side of a steam generator, characterized in that, It includes an electrical discharge machining (EDM) mechanism, a flexible conveying mechanism, and a clamping mechanism. The flexible conveying mechanism is used to convey the EDM mechanism and the clamping mechanism to the pipe section where the metal foreign object (9) is located on the secondary side of the steam generator (1). The flexible conveying mechanism is connected to the EDM mechanism and the clamping mechanism respectively. When the clamping mechanism clamps the metal foreign object (9) on the secondary side of the steam generator (1), the EDM mechanism, the flexible conveying mechanism, and the clamping mechanism form a discharge circuit. The EDM mechanism processes and shears the metal foreign object (9) on the secondary side of the steam generator (1). The flexible conveying mechanism includes a first flexible conveying mechanism and a second flexible conveying mechanism. The first flexible conveying mechanism is used to convey the electrical discharge machining mechanism to the pipe space where the metal foreign object (9) is located on the secondary side of the steam generator (1). The second flexible conveying mechanism is used to convey the clamping mechanism to the pipe space where the metal foreign object (9) is located on the secondary side of the steam generator (1). The first flexible conveying mechanism is connected to the electrical discharge machining mechanism, and the second flexible conveying mechanism is connected to the clamping mechanism. When the clamping mechanism clamps the metal foreign object (9) on the secondary side of the steam generator (1), the electrical discharge machining mechanism, the first flexible conveying mechanism, the second flexible conveying mechanism and the clamping mechanism form a discharge circuit. The electrical discharge machining mechanism processes and shears the metal foreign object (9) on the secondary side of the steam generator (1). The first flexible conveying mechanism includes a head conveying mechanism (2), a head insertion tube assembly (3), and a first handle (4). The head conveying mechanism (2) is used to be fixedly connected to the hand hole of the steam generator (1). The head insertion tube assembly (3) passes through the head conveying mechanism (2) and extends out of both ends of the head conveying mechanism (2). The end of the head insertion tube assembly (3) away from the steam generator (1) is connected to the first handle (4). The second flexible conveying mechanism includes a second handle (11) and a workpiece insertion tube assembly (14). The second handle (11) is connected to the workpiece insertion tube assembly (14). The workpiece insertion tube assembly (14) is inserted into the tube space where the secondary side metal foreign object (9) of the steam generator (1) is located.

2. The steam generator secondary side metal foreign object cutting tool according to claim 1, characterized in that, The electrical discharge machining mechanism includes a control cable (5), an electrical discharge machine (6), and a tool head (7) with internal electrode plates. One end of the control cable (5) is connected to the electrical discharge machine (6), and the other end of the control cable (5) is connected to the control handle (4). The tool head (7) is connected to the end of the head insertion tube assembly (3) near the steam generator (1).

3. The steam generator secondary side metal foreign object cutting tool according to claim 2, characterized in that, The tool head (7) is provided with a tensioning mechanism. When the direction of the insertion of the tool head into the tube assembly (3) is determined, the tensioning mechanism expands to fix the position of the tool head (7).

4. The steam generator secondary side metal foreign object cutting tool according to claim 2, characterized in that, The clamping mechanism includes a clamp (8) with internal electrode plates and a negative cable (10). The clamp (8) is connected to one end of the workpiece insertion tube assembly (14) near the steam generator (1), one end of the negative cable (10) is connected to the other end of the workpiece insertion tube assembly (14) away from the steam generator (1), and the other end of the negative cable (10) is connected to the EDM machine (6).

5. The steam generator secondary side metal foreign object cutting tool according to claim 2, characterized in that, The EDM machine (6) is equipped with a metal foreign object processing and shearing program. The metal foreign object processing and shearing program completes the processing and shearing of the metal foreign object (9) on the secondary side of the steam generator (1) by controlling the feed and discharge of the electrode plate inside the tool head (7).

6. The secondary side metal foreign object cutting tool for a steam generator according to claim 5, characterized in that, The secondary side metal foreign object cutting tool of the steam generator also includes a high-pressure water flushing mechanism. The high-pressure water flushing mechanism includes a water pipe (12) and a water supply mechanism (13). One end of the water pipe (12) is connected to the end of the workpiece insertion tube assembly (14) away from the steam generator (1), and the other end of the water pipe (12) is connected to the water supply mechanism (13).

7. The steam generator secondary side metal foreign object cutting tool according to claim 6, characterized in that, The metal foreign object processing shearing program controls the start of the water supply mechanism (13). During the electrical discharge machining process, the metal foreign object processing shearing program starts the water supply mechanism (13), and the water supply mechanism (13) sprays processing fluid into the processing area to rinse the waste residue in the processing area.

8. A method for removing metallic foreign objects from the secondary side of a steam generator, characterized in that, The application of the steam generator secondary side metal foreign object cutting tool according to any one of claims 1-7 includes the following steps: using a flexible conveying mechanism to send the electrical discharge machining mechanism and the clamping mechanism into the steam generator; using an endoscope to observe that the electrodes in the electrical discharge machining mechanism and the clamping mechanism reach the position of the secondary side metal foreign object (9) of the steam generator (1); the clamping mechanism clamps the secondary side metal foreign object (9) of the steam generator (1) to form a discharge circuit; and the electrical discharge machining mechanism starts to process and cut off the secondary side metal foreign object (9) of the steam generator (1).

Images