A device for cutting foreign objects between the secondary side heat transfer tubes of a steam generator in a nuclear power plant

Abstract

The present invention specifically relates to a device for cutting foreign objects between the secondary-side heat transfer tubes of a steam generator, which is characterized by comprising a guide rail mechanism (20), a guiding mechanism (21) and a flexible cutting tool; the guide rail mechanism (20) is installed between the 0° manhole and the 180° manhole of the steam generator, the guiding mechanism (21) is slidably installed on the guide rail mechanism (20), and the guiding mechanism (21) can move back and forth along the central pipe gallery of the steam generator on the guide rail mechanism (20); the guiding mechanism (21) is connected to the flexible cutting tool, and the flexible cutting tool is driven to extend to any position between the heat transfer tubes of the steam generator by sliding the guiding mechanism (21) on the guide rail mechanism (20). The device for cutting foreign objects between the secondary-side heat transfer tubes of the steam generator according to the present invention realizes the cutting of foreign objects between the secondary-side heat transfer tubes of the steam generator.

Description

Technical Field

[0001] The present invention relates to the technical field of maintenance of steam generators in nuclear power plants, and particularly to a device for cutting foreign objects between secondary-side heat transfer tubes of a steam generator. Background Art

[0002] As one of the important devices in a nuclear power plant, the main function of a steam generator is to act as a heat exchanger, transferring the heat in the primary coolant from the nuclear reactor to the main feed water of the secondary circuit to generate saturated steam and drive a steam turbine to generate electricity. The steam generator occupies more than 80% of the area of the primary circuit, and the wall thickness of the heat transfer tubes is about 1 mm. Some foreign objects on the secondary side of the steam generator, under the action of high-temperature, high-pressure and high-flow-rate water, impact the heat transfer tubes, which may cause pits in the heat transfer tubes, leading to stress corrosion cracks, and may cause leakage of the heat transfer tubes and pollution of the secondary side. Therefore, once foreign objects are found on the secondary side of the steam generator, they should be removed in time. Some foreign objects are filamentous, such as iron wires, welding rods, etc., spanning several tube spaces or winding around the heat transfer tubes. Sometimes it is very difficult to directly remove the filamentous foreign objects, and it is necessary to cut the filamentous foreign objects into several sections to facilitate the removal with tools such as foreign object forceps. The internal space on the secondary side of the steam generator is very narrow, and the gap between the heat transfer tubes is sometimes only about 4 mm. Moreover, it is necessary to pass through a manhole and then turn 90° or 30° to reach the tube space. Therefore, it is required that the body of the cutting tool must be soft and easy to guide, and at the same time, it must have a certain rigidity and maintain straightness in the normal state. In addition, it is required that the cutting tool head be flat and smaller than the width of the gap between the heat transfer tubes of the steam generator. Currently, there is a lack of a cutting tool for foreign objects between the secondary-side heat transfer tubes of a steam generator. Summary of the Invention

[0003] The purpose of the present invention is to provide a device for cutting foreign objects between secondary-side heat transfer tubes of a steam generator to achieve the cutting of foreign objects between secondary-side heat transfer tubes of a steam generator.

[0004] To achieve the above purpose, the present invention provides the following technical solutions:

[0005] A device for cutting foreign objects between secondary-side heat transfer tubes of a steam generator includes a guide rail mechanism, a guiding mechanism, and a flexible cutting tool; the guide rail mechanism is installed between the 0° manhole and the 180° manhole of the steam generator, the guiding mechanism is slidably installed on the guide rail mechanism, and the guiding mechanism can move back and forth along the central pipe gallery of the steam generator on the guide rail mechanism; the guiding mechanism is connected to the flexible cutting tool, and the flexible cutting tool is driven to extend to any position between the heat transfer tubes of the steam generator by the sliding of the guiding mechanism on the guide rail mechanism.

[0006] Further, the flexible cutting tool includes a motor, a reducer, a driving flexible shaft, a flexible shaft interface, and a cutting tool tail installed inside the guiding mechanism, and a flexible metal flat belt, a cutting tool head, a grinding file, and an actuating flexible shaft installed outside the guiding mechanism; the output end of the motor is connected to the input end of the reducer, and the output end of the reducer is connected to one end of the driving flexible shaft close to the reducer; one end of the flexible metal flat belt away from the driving flexible shaft is connected to the cutting tool head, and one end close to the driving flexible shaft is connected to the cutting tool tail; the grinding file is installed on the cutting tool head; the actuating flexible shaft is clamped inside the flexible metal flat belt, one end away from the driving flexible shaft extends outside the flexible metal flat belt and is connected to the grinding file, and one end close to the driving flexible shaft extends outside the flexible metal flat belt and passes through the cutting tool tail and is connected to the end of the driving flexible shaft away from the reducer through the flexible shaft interface. The rotation of the motor is decelerated by the reducer and then transmitted to the grinding file through the driving flexible shaft and the actuating flexible shaft, and the grinding file rotates to perform grinding and cutting on the foreign matter entering the inside of the cutting tool head.

[0007] Further, the cutting tool head is a fork-shaped structure in the form of an alligator's mouth, which is easy for foreign matter between the heat transfer tubes of the steam generator to enter; the grinding file is installed at the upper end of the fork-shaped structure.

[0008] Further, the flexible cutting tool further includes a cable interface installed inside the guiding mechanism, and a first camera and a second camera installed on the cutting tool head; the first camera is installed at the front end of the cutting tool head, and the probe faces forward of the cutting tool head, and is used to find foreign matter between the heat transfer tubes of the steam generator; the second camera is installed on the fork-shaped structure of the cutting tool head, and the probe faces the fork-shaped structure, and is used to observe the process of the grinding file grinding and cutting the foreign matter entering the fork-shaped structure, so as to realize the visualization of the cutting of foreign matter between the heat transfer tubes of the steam generator; the cables of the first camera and the second camera are both installed inside the cutting tool head, and the free ends sequentially pass through the cutting tool head and the flexible metal flat belt and are connected to an external power supply through the cable interface; the cables of the first camera and the second camera are both clamped inside the flexible metal flat belt.

[0009] Further, the guiding mechanism includes a trolley installed on the rail mechanism, a multi-section square-hole straight pipe section connected to the trolley, and a square-hole elbow connected to the multi-section square-hole straight pipe section; the motor, the reducer, the driving flexible shaft, the flexible shaft interface, the cable interface, and the cutting tool tail are all installed inside the square-hole elbow of the guiding mechanism.

[0010] Further, the square-hole elbow of the guiding mechanism is determined according to the arrangement of the secondary-side heat transfer tubes of the steam generator, and the bending angle of the square-hole elbow of the guiding mechanism is between 0° and 90°.

[0011] Further, a first LED lamp is installed on the first camera, and a second LED lamp is installed on the second camera; the cables of the first camera and the first LED lamp and the cables of the second camera and the second LED lamp are all installed in the cutting tool head, and the free ends sequentially pass through the cutting tool head and the flexible metal flat belt and are connected to an external power supply through a cable interface; the cables of the first camera and the first LED lamp and the cables of the second camera and the second LED lamp are all clamped in the flexible metal flat belt.

[0012] Further, the cutting tool head includes a first stainless steel sheet and a second stainless steel sheet; the first stainless steel sheet is in a right-angle structure, and the second stainless steel sheet is in a right-angled triangle structure; the flat angle end of the first stainless steel sheet and the right-angle end of the second stainless steel sheet are butt-jointed by riveting or screws to form a fork-shaped structure in the form of an alligator's mouth, which is easy for foreign objects between the heat transfer tubes of the steam generator to enter;

[0013] On the outer surface of the right-angle end of the first stainless steel sheet, there is a first camera mounting groove, and inside the first stainless steel sheet, there is a cable mounting groove for the first camera and the first LED lamp. The cable mounting grooves for the first camera and the first LED lamp are respectively communicated with the first camera mounting groove and the inside of the flexible metal flat belt; the first camera is installed in the first camera mounting groove, and the probe faces the front of the first stainless steel sheet; the cables of the first camera and the first LED lamp are installed in the cable mounting groove for the first camera and the first LED lamp, and the free ends sequentially pass through the first stainless steel sheet and the flexible metal flat belt and are connected to an external power supply through a cable interface; the cables of the first camera and the first LED lamp are clamped in the flexible metal flat belt;

[0014] On the inner surface of the right-angle end of the first stainless steel sheet, there is a second camera mounting groove, and inside the first stainless steel sheet, there is a cable mounting groove for the second camera and the second LED lamp. The cable mounting grooves for the second camera and the second LED lamp are respectively communicated with the second camera mounting groove and the inside of the flexible metal flat belt; the second camera is installed in the second camera mounting groove, and the probe faces the fork-shaped structure; the cables of the second camera and the second LED lamp are installed in the cable mounting groove for the second camera and the second LED lamp, and the free ends sequentially pass through the first stainless steel sheet and the flexible metal flat belt and are connected to an external power supply through a cable interface; the cables of the second camera and the second LED lamp are clamped in the flexible metal flat belt;

[0015] A grinding file mounting groove is provided on the first stainless steel sheet at the upper end of the fork-shaped structure. An actuating flexible shaft mounting groove is provided inside the first stainless steel sheet. The actuating flexible shaft mounting groove is internally connected to the grinding file mounting groove and the flexible metal flat belt respectively. The grinding file is mounted in the grinding file mounting groove and extends out of the first stainless steel sheet into the fork-shaped structure. The actuating flexible shaft is mounted in the actuating flexible shaft mounting groove and clamped inside the flexible metal flat belt. The end away from the driving flexible shaft is connected to the grinding file, and the end close to the driving flexible shaft passes through the flexible metal flat belt and the tail of the cutting tool and is connected to the end of the driving flexible shaft away from the reducer through a flexible shaft interface.

[0016] Further, the motor is an electric motor or a pneumatic motor.

[0017] Further, the flexible metal flat belt is formed by riveting two stainless steel thin sheets together. The flexible metal flat belt has both a certain flexibility and a certain rigidity, and can be bent into the tube space between the heat transfer tubes of the steam generator through a guiding mechanism.

[0018] Further, the actuating flexible shaft is wound by multiple strands of steel wires and is sleeved with a plastic tube. The end of the actuating flexible shaft connected to the driving flexible shaft is pressed into a square structure and is connected to the driving flexible shaft through a flexible shaft interface.

[0019] Further, the grinding file is made of cemented carbide or tungsten steel. The grinding file is provided with a notch, and the notch is a one-way notch or a cross two-way notch. The two ends of the grinding file are respectively provided with a first short rotating shaft and a second short rotating shaft. The first short rotating shaft is connected to the actuating flexible shaft, and the second short rotating shaft is connected to the cutting tool head.

[0020] In one embodiment, the steam generator is a vertical steam generator, the foreign object is a filamentous foreign object, and the filamentous foreign object includes iron wire and welding rod.

[0021] The beneficial technical effects of the present invention:

[0022] For the foreign object cutting device for the secondary side heat transfer tube space of the steam generator of the present invention, the flexible metal flat belt has both a certain flexibility and a certain rigidity, and can be bent into the tube space between the heat transfer tubes of the steam generator through a guiding mechanism mounted on the guide rail mechanism. Then, the grinding file on the cutting tool head is driven by the motor through the driving flexible shaft and the actuating flexible shaft to rotate at a high speed to cut the foreign object in the tube space between the heat transfer tubes of the steam generator, realizing the cutting of the foreign object in the tube space between the secondary side heat transfer tubes of the steam generator, which is beneficial to quickly removing the foreign object in the tube space between the heat transfer tubes of the steam generator, and has important significance for ensuring the safe and reliable operation of the nuclear power plant. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of a flexible cutting tool;

[0024] Figure 2Schematic diagram of the cutting tool head structure;

[0025] Figure 3 Schematic diagram of the grinding file structure;

[0026] Figure 4 Schematic diagram of the use of the foreign object cutting device for the secondary side heat transfer tubes of the steam generator of the present invention.

[0027] In the figure, 1, motor; 2, speed reducer; 3, drive flexible shaft; 4, flexible shaft interface; 5, cable interface; 6, cutting tool tail; 7, flexible metal flat belt; 8, cutting tool head; 9, cable of the first camera and the first LED lamp; 10, first camera; 11, cable of the second camera and the second LED lamp; 12, second camera; 13, execution flexible shaft; 14, grinding file; 16, first short rotating shaft; 17, notch; 18, second short rotating shaft; 20, guide rail mechanism; 21, guide mechanism member. Specific embodiments

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0029] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "left end", "right end", "front", "rear", "outside", "inside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0030] In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0031] See Figure 4 , this embodiment provides a foreign object cutting device for the secondary side heat transfer tubes of a steam generator, including a guide rail mechanism 20, a guide mechanism 21 and a flexible cutting tool; the guide rail mechanism 20 is installed between the 0° manhole and the 180° manhole of the steam generator, the guide mechanism 21 is slidably installed on the guide rail mechanism 20, and the guide mechanism 21 can move back and forth along the central pipe gallery of the steam generator on the guide rail mechanism 20; the guide mechanism 21 is connected to the flexible cutting tool, and the flexible cutting tool is driven to extend to any position between the heat transfer tubes of the steam generator by sliding the guide mechanism 21 on the guide rail mechanism 20.

[0032] In this embodiment, the steam generator is a vertical steam generator, the foreign object is a filamentous foreign object, and the filamentous foreign object includes iron wire and welding rods.

[0033] See Figure 1 , 2 and 4. In this embodiment, the flexible cutting tool includes a motor 1, a speed reducer 2, a driving flexible shaft 3, a flexible shaft interface 4, and a cutting tool tail 6 installed inside the guiding mechanism 21, and a flexible metal flat belt 7, a cutting tool head 8, a grinding file 14, and an actuating flexible shaft 13 installed outside the guiding mechanism 21. The output end of the motor 1 is connected to the input end of the speed reducer 2, and the output end of the speed reducer 2 is connected to one end of the driving flexible shaft 3 close to the speed reducer 2. One end of the flexible metal flat belt 7 far from the driving flexible shaft 3 is connected to the cutting tool head 8, and one end close to the driving flexible shaft 3 is connected to the cutting tool tail 6. The grinding file 14 is installed on the cutting tool head 8. The actuating flexible shaft 13 is clamped inside the flexible metal flat belt 7, and one end far from the driving flexible shaft 3 extends outside the flexible metal flat belt 7 and is connected to the grinding file 14, and one end close to the driving flexible shaft 3 extends outside the flexible metal flat belt 7 and passes through the cutting tool tail 6 and is connected to the end of the driving flexible shaft 3 far from the speed reducer 2 through the flexible shaft interface 4. The rotation of the motor 1 is decelerated by the speed reducer 2 and then transmitted to the grinding file 14 through the driving flexible shaft 3 and the actuating flexible shaft 13, and the grinding file 14 rotates to perform grinding and cutting on the foreign object entering the inside of the cutting tool head 8.

[0034] See Figure 1 and 2 , in this embodiment, the cutting tool head 8 is a fork-shaped structure in the form of an alligator mouth, which is easy for foreign objects between the heat transfer tubes of the steam generator to enter; the grinding file 14 is installed at the upper end of the fork-shaped structure.

[0035] See Figure 1 , 2 and 4. In this embodiment, the flexible cutting tool further includes a cable interface 5 installed inside the guiding mechanism 21, and a first camera 10 and a second camera 12 installed on the cutting tool head 8. The first camera 10 is installed at the front end of the cutting tool head 8, and the probe faces the front of the cutting tool head 8 for finding foreign objects between the heat transfer tubes of the steam generator. The second camera 12 is installed on the fork-shaped structure of the cutting tool head 8, and the probe faces the fork-shaped structure for observing the process of the grinding file 14 grinding and cutting the foreign object entering the fork-shaped structure, realizing the visualization of the cutting of foreign objects between the heat transfer tubes of the steam generator. The cables of the first camera and the second camera are both installed inside the cutting tool head 8, and the free ends sequentially pass through the cutting tool head 8 and the flexible metal flat belt 7 and are connected to an external power supply through the cable interface 5. The cables of the first camera and the second camera are both clamped inside the flexible metal flat belt 7.

[0036] In this embodiment, the cable interface 5 is installed in the square hole elbow of the guiding mechanism 21.

[0037] See Figure 1 、 2 and 4. In this embodiment, the guiding mechanism 21 includes a pulley mounted on the guide rail mechanism 20, a multi-section square-hole straight pipe section connected to the pulley, and a square-hole elbow connected to the multi-section square-hole straight pipe section; the motor 1, the reducer 2, the driving flexible shaft 3, the flexible shaft interface 4, the cable interface 5, and the cutting tool tail 6 are all installed in the square-hole elbow of the guiding mechanism 21.

[0038] See Figure 4 . In this embodiment, the square-hole elbow of the guiding mechanism 21 is determined according to the arrangement of the secondary-side heat transfer tubes of the steam generator, and the bending angle of the square-hole elbow of the guiding mechanism 21 is between 0° and 90°.

[0039] See Figure 1 and 2 . In this embodiment, a first LED light is installed on the first camera 10, and a second LED light is installed on the second camera 12; the cables 9 of the first camera and the first LED light and the cables 11 of the second camera and the second LED light are all installed in the cutting tool head 8, and the free ends sequentially pass through the cutting tool head 8 and the flexible metal flat belt 7 and are connected to an external power supply through the cable interface 5; the cables 9 of the first camera and the first LED light and the cables 11 of the second camera and the second LED light are all clamped in the flexible metal flat belt 7.

[0040] See Figure 1 and 2 . In this embodiment, the cutting tool head 8 includes a first stainless steel sheet and a second stainless steel sheet; the first stainless steel sheet is in a right-angle structure, and the second stainless steel sheet is in a right-angled triangle structure; the flat-angle end of the first stainless steel sheet and the right-angle end of the second stainless steel sheet are butt-jointed by riveting or screws to form a fork-shaped structure in the form of an alligator's mouth, which is easy for foreign objects between the heat transfer tubes of the steam generator to enter;

[0041] A first camera mounting groove is provided on the outer surface of the right-angle end of the first stainless steel sheet, and a cable mounting groove for the first camera and the first LED light is provided inside the first stainless steel sheet. The cable mounting grooves for the first camera and the first LED light are respectively communicated with the first camera mounting groove and the inside of the flexible metal flat belt 7; the first camera 10 is installed in the first camera mounting groove, and the probe faces the front of the first stainless steel sheet; the cables 9 of the first camera and the first LED light are installed in the cable mounting grooves for the first camera and the first LED light, and the free ends sequentially pass through the first stainless steel sheet and the flexible metal flat belt 7 and are connected to an external power supply through the cable interface 5; the cables 9 of the first camera and the first LED light are clamped in the flexible metal flat belt 7;

[0042] On the inner surface of the right-angled end of the first stainless steel sheet, there is a second camera mounting groove. Inside the first stainless steel sheet, there are cable mounting grooves for the second camera and the second LED lamp. The cable mounting grooves for the second camera and the second LED lamp are respectively internally connected to the second camera mounting groove and the flexible metal flat belt 7. The second camera 12 is installed in the second camera mounting groove, with the probe facing the fork-shaped structure. The cables 12 of the second camera and the second LED lamp are installed in the cable mounting grooves for the second camera and the second LED lamp, and the free ends sequentially pass through the first stainless steel sheet and the flexible metal flat belt 7 and are connected to an external power supply through a cable interface 5. The cables 12 of the second camera and the second LED lamp are clamped inside the flexible metal flat belt 7.

[0043] On the first stainless steel sheet at the upper end of the fork-shaped structure, there is a grinding file mounting groove. Inside the first stainless steel sheet, there is a flexible shaft mounting groove. The flexible shaft mounting groove is respectively internally connected to the grinding file mounting groove and the flexible metal flat belt 7. The grinding file 14 is installed in the grinding file mounting groove and extends out of the first stainless steel sheet into the fork-shaped structure. The flexible shaft is installed in the flexible shaft mounting groove and clamped inside the flexible metal flat belt 7. The end far from the drive flexible shaft 3 is connected to the grinding file 14, and the end close to the drive flexible shaft 3 passes through the flexible metal flat belt 7 and the cutting tool tail 6 and is connected to the end of the drive flexible shaft 3 far from the speed reducer 2 through a flexible shaft interface 4.

[0044] In this embodiment, the motor 1 is an electric motor or a pneumatic motor.

[0045] In this embodiment, the flexible metal flat belt 7 is formed by riveting two stainless steel thin sheets together. The flexible metal flat belt 7 has both a certain flexibility and a certain rigidity, and can be bent into the inter-tube space of the steam generator heat transfer tube through the guiding mechanism 21.

[0046] In this embodiment, the flexible shaft 13 is made of multiple strands of steel wires wound around and has a plastic tube sleeved outside. The end of the flexible shaft 13 connected to the drive flexible shaft 3 is pressed into a square structure and connected to the drive flexible shaft 3 through a flexible shaft interface 4.

[0047] See Figure 3 , in this embodiment, the grinding file 14 is made of hard alloy or tungsten steel. The grinding file 14 is provided with a notch 17, and the notch is a one-way notch or a cross two-way notch. Both ends of the grinding file 14 are respectively provided with a first short rotating shaft 16 and a second short rotating shaft 18. The first short rotating shaft 16 is connected to the flexible shaft 13, and the second short rotating shaft 18 is connected to the cutting tool head 8.

[0048] See Figure 4 , when using the foreign object cutting device for the secondary side heat transfer tube of the steam generator in this embodiment to cut the filamentous foreign objects in the inter-tube space of the secondary side heat transfer tube of the vertical steam generator, the following steps are included:

[0049] This embodiment provides a foreign object cutting device between the secondary side heat transfer tubes of a steam generator, including a guide rail mechanism 20, a guiding mechanism 21, and a flexible cutting tool.

[0050] Step 1: Install the guide rail mechanism 20 between the 0° manhole and the 180° manhole of the steam generator, and install the guiding mechanism 21 on the guide rail mechanism 20. The square hole elbow of the guiding mechanism 21 is determined according to the arrangement of the secondary side heat transfer tubes of the steam generator.

[0051] Step 2: Insert the flexible cutting tool into the square hole elbow of the guiding mechanism 21, with the flexible metal flat belt 7 and the cutting tool head 8 outside the guiding mechanism 21.

[0052] Step 3: Move the flexible metal flat belt 7 and the cutting tool head 8 back and forth along the central pipe gallery of the steam generator on the guide rail mechanism 20 through the guiding mechanism 21, and insert them between the heat transfer tubes of the secondary side of the steam generator where foreign objects need to be cut.

[0053] Step 4: Search for foreign objects between the heat transfer tubes of the steam generator through the first camera 10, and adjust the position of the cutting tool head 8 so that the foreign object enters the inside of the cutting tool head 8.

[0054] Step 5: Start the motor 1. After the motor 1 rotates and is decelerated by the reducer 2, it is transmitted to the grinding file 14 through the drive soft shaft 3 and the execution soft shaft 13. The grinding file 14 rotates to perform grinding and cutting on the foreign object that enters the inside of the cutting tool head 8 until the foreign object that enters the inside of the cutting tool head 8 is cut off. Observe the process of the grinding file 14 grinding and cutting the foreign object that enters the inside of the cutting tool head 8 through the second camera 12 to realize the visualization of foreign object cutting between the heat transfer tubes of the steam generator.

[0055] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. A foreign object cutting device between the secondary side heat transfer tubes of a steam generator, characterized in that, It includes a guide rail mechanism (20), a guiding mechanism (21) and a flexible cutting tool; the guide rail mechanism (20) is installed between the 0° manhole and the 180° manhole of the steam generator, the guiding mechanism (21) is slidably installed on the guide rail mechanism (20), and the guiding mechanism (21) can move back and forth along the central pipe gallery of the steam generator on the guide rail mechanism (20); the guiding mechanism (21) is connected to the flexible cutting tool, and the flexible cutting tool is driven by the guiding mechanism (21) sliding on the guide rail mechanism (20) to extend to any position between the heat transfer tubes of the steam generator. The flexible cutting tool includes a motor (1), a reducer (2), a driving flexible shaft (3), a flexible shaft interface (4) and a cutting tool tail (6) installed inside the guiding mechanism (21), and a flexible metal flat belt (7), a cutting tool head (8), a grinding file (14) and an actuating flexible shaft (13) installed outside the guiding mechanism (21); the output end of the motor (1) is connected to the input end of the reducer (2), and the output end of the reducer (2) is connected to one end of the driving flexible shaft (3) close to the reducer (2); one end of the flexible metal flat belt (7) far from the driving flexible shaft (3) is connected to the cutting tool head (8), and one end close to the driving flexible shaft (3) is connected to the cutting tool tail (6); the grinding file (14) is installed on the cutting tool head (8); the actuating flexible shaft (13) is clamped inside the flexible metal flat belt (7), one end far from the driving flexible shaft (3) extends outside the flexible metal flat belt (7) and is connected to the grinding file (14), and one end close to the driving flexible shaft (3) extends outside the flexible metal flat belt (7) and passes through the cutting tool tail (6) and is connected to the end of the driving flexible shaft (3) far from the reducer (2) through the flexible shaft interface (4). The guiding mechanism (21) includes a trolley installed on the guide rail mechanism (20), multiple sections of square-hole straight pipe segments connected to the trolley, and a square-hole elbow connected to the multiple sections of square-hole straight pipe segments; the motor (1), the reducer (2), the driving flexible shaft (3), the flexible shaft interface (4), the cable interface (5) and the cutting tool tail (6) are all installed inside the square-hole elbow of the guiding mechanism (21).

2. The foreign object cutting device between the secondary side heat transfer tubes of the steam generator according to claim 1, characterized in that, The cutting tool head (8) is a fork-shaped structure in the form of an alligator mouth; the grinding file (14) is installed at the upper end of the fork-shaped structure.

3. The foreign object cutting device between the secondary side heat transfer tubes of the steam generator according to claim 1, characterized in that, The flexible cutting tool further includes a cable interface (5) installed inside the guiding mechanism (21), a first camera (10) and a second camera (12) installed on the cutting tool head (8); the first camera (10) is installed at the front end of the cutting tool head (8), and the probe faces forward of the cutting tool head (8) for searching for foreign objects between the heat transfer tubes of the steam generator; the second camera (12) is installed on the fork-shaped structure of the cutting tool head (8), and the probe faces the fork-shaped structure for observing the process of the grinding file (14) grinding and cutting the foreign objects entering the fork-shaped structure, realizing the visualization of the cutting of foreign objects between the heat transfer tubes of the steam generator; the cables of the first camera and the second camera are both installed inside the cutting tool head (8), and the free ends sequentially pass through the cutting tool head (8) and the flexible metal flat belt (7) and are connected to an external power supply through the cable interface (5); the cables of the first camera and the second camera are both clamped inside the flexible metal flat belt (7).

4. The foreign object cutting device between the secondary side heat transfer tubes of the steam generator according to claim 1, characterized in that, The square-hole elbow of the guiding mechanism (21) is determined according to the arrangement of the secondary-side heat transfer tubes of the steam generator, and the bending angle of the square-hole elbow of the guiding mechanism (21) is between 0° and 90°.

5. The foreign object cutting device between the secondary side heat transfer tubes of the steam generator according to claim 3, characterized in that, A first LED lamp is installed on the first camera (10), and a second LED lamp is installed on the second camera (12); the cables (9) of the first camera and the first LED lamp and the cables (11) of the second camera and the second LED lamp are both installed inside the cutting tool head (8), and the free ends sequentially pass through the cutting tool head (8) and the flexible metal flat belt (7) and are connected to an external power supply through the cable interface (5); the cables (9) of the first camera and the first LED lamp and the cables (11) of the second camera and the second LED lamp are both clamped inside the flexible metal flat belt (7).

6. The foreign object cutting device between the secondary side heat transfer tubes of the steam generator according to claim 5, wherein The cutting tool head (8) includes a first stainless steel sheet and a second stainless steel sheet; the first stainless steel sheet is a right-angle structure, and the second stainless steel sheet is a right-angled triangle structure; the flat-angle end of the first stainless steel sheet and the right-angle end of the second stainless steel sheet are butt-jointed by riveting or screws to form a fork-shaped structure in the form of an alligator's mouth; a first camera installation groove is provided on the outer surface of the right-angle end of the first stainless steel sheet, and a cable installation groove for the first camera and the first LED lamp is provided inside the first stainless steel sheet, and the cable installation grooves for the first camera and the first LED lamp are respectively communicated with the first camera installation groove and the inside of the flexible metal flat belt (7); the first camera (10) is installed in the first camera installation groove, and the probe faces forward of the first stainless steel sheet; The cable (9) of the first camera and the first LED lamp is installed in the cable installation groove of the first camera and the first LED lamp. The free end sequentially passes through the first stainless steel sheet and the flexible metal flat belt (7) and is connected to an external power supply through the cable interface (5); the cable (9) of the first camera and the first LED lamp is clamped within the flexible metal flat belt (7); on the inner surface of the right-angle end of the first stainless steel sheet, there is a second camera installation groove, and within the first stainless steel sheet, there is a cable installation groove for the second camera and the second LED lamp. The cable installation grooves for the second camera and the second LED lamp are respectively in internal communication with the second camera installation groove and the flexible metal flat belt (7); the second camera (12) is installed in the second camera installation groove with its probe facing the fork-shaped structure; the cable (12) of the second camera and the second LED lamp is installed in the cable installation groove for the second camera and the second LED lamp. The free end sequentially passes through the first stainless steel sheet and the flexible metal flat belt (7) and is connected to an external power supply through the cable interface (5); the cable (12) of the second camera and the second LED lamp is clamped within the flexible metal flat belt (7); on the first stainless steel sheet at the upper end of the fork-shaped structure, there is a grinding file installation groove, and within the first stainless steel sheet, there is an actuating flexible shaft installation groove. The actuating flexible shaft installation groove is respectively in internal communication with the grinding file installation groove and the flexible metal flat belt (7); the grinding file (14) is installed in the grinding file installation groove and extends out of the first stainless steel sheet within the fork-shaped structure; the actuating flexible shaft is installed in the actuating flexible shaft installation groove and is clamped within the flexible metal flat belt (7). The end far from the driving flexible shaft (3) is connected to the grinding file (14), and the end close to the driving flexible shaft (3) passes through the flexible metal flat belt (7) and the cutting tool tail (6) and is connected to the end of the driving flexible shaft (3) far from the speed reducer (2) through the flexible shaft interface (4).

7. The foreign object cutting device between the secondary side heat transfer tubes of the steam generator according to claim 1, characterized in that, The flexible metal flat belt (7) is formed by riveting two stainless steel thin sheets together face to face.

8. The foreign object cutting device between the secondary side heat transfer tubes of the steam generator according to claim 1, characterized in that The actuating flexible shaft (13) is wound by multiple strands of steel wires and is sleeved with a plastic tube on the outside; the end of the actuating flexible shaft (13) connected to the driving flexible shaft (3) is pressed into a square structure and is connected to the driving flexible shaft (3) through the flexible shaft interface (4); the grinding file (14) is made of hard alloy or tungsten steel. There is a notch (17) on the grinding file (14), and the notch is a one-way notch or a cross two-way notch; there are respectively a first short rotating shaft (16) and a second short rotating shaft (18) at both ends of the grinding file (14); the first short rotating shaft (16) is connected to the actuating flexible shaft (13), and the second short rotating shaft (18) is connected to the cutting tool head (8).

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