Video inspection device and method for Ω weld seam at the lower part of control rod drive mechanism

Abstract

The present invention relates to the technical field of non-destructive testing of nuclear power plants, and specifically discloses a video inspection device and method for the Ω weld at the lower part of a control rod drive mechanism. The device includes a vehicle body, a multi-degree-of-freedom mechanical arm, and a pan-tilt camera, wherein the vehicle body can go straight, move backward, and turn, and a multi-degree-of-freedom mechanical arm is arranged on the vehicle body, and the multi-degree-of-freedom mechanical arm can be folded or the end thereof can be raised to a certain height; a pan-tilt camera is arranged at the end of the multi-degree-of-freedom mechanical arm; when the multi-degree-of-freedom mechanical arm is in a folded state, the inspection device can enter the insulation layer through the ventilation hole at the upper end of the pressure vessel as a whole. The device and method can solve the problem of video inspection of control rod drive mechanisms in high radiation environments, confined spaces, and densely distributed without removing the insulation layer, realize automatic collection, reduce the radiation dose of personnel, achieve the coverage rate of weld inspection, and shorten the inspection time.

Description

Technical Field

[0001] The invention belongs to the technical field of nondestructive testing of nuclear power plants, and in particular relates to a video inspection device and method for an Ω weld at the bottom of a control rod drive mechanism. Background Art

[0002] In a pressurized water reactor nuclear power plant, Figure 1 , Figure 2 The control rod drive mechanism (CRDM) is installed on the top cover of the reactor pressure vessel and is surrounded by an insulation layer. It is a key nuclear equipment for realizing reactor startup, power regulation, and shutdown, and is also an important part of the reactor primary circuit pressure boundary. The integrity of the control rod drive mechanism is directly related to the safe operation of the nuclear power plant. The control rod drive mechanism (CRDM) operates in a harsh environment of high temperature, high pressure, strong radiation and boric acid for a long time, and there is a risk of stress corrosion cracking. In particular, the Ω weld of the control rod drive mechanism may produce welding defects such as incomplete penetration, incomplete fusion, pores and slag inclusions during the welding process. In long-term operation, corrosion, cracks and other damages may occur. In addition, the radiation dose of the Ω weld of the control rod drive mechanism during the shutdown inspection is high, and the control rod drive mechanism is densely distributed, which increases the difficulty of inspection. Therefore, without removing the insulation layer, a set of robots carrying cameras are developed to enter the enclosed space through the ventilation holes for automated inspection, which can improve the coverage of the inspection and reduce the radiation dose of personnel. Summary of the invention

[0003] The purpose of the present invention is to provide a video inspection device and method for the Ω weld at the bottom of a control rod drive mechanism, which is suitable for high radiation environments and closed spaces.

[0004] The technical solution of the present invention is as follows: a video inspection device for the Ω weld at the lower part of a control rod drive mechanism, the device comprising a vehicle body, a multi-degree-of-freedom mechanical arm and a pan-tilt camera, wherein the vehicle body can move straight, move backward and turn, a multi-degree-of-freedom mechanical arm is arranged on the vehicle body, the multi-degree-of-freedom mechanical arm can be folded or the end thereof can be raised to a certain height; a pan-tilt camera is arranged at the end of the multi-degree-of-freedom mechanical arm; when the multi-degree-of-freedom mechanical arm is in a folded state, the inspection device can enter the insulation layer as a whole through the ventilation hole at the upper end of the pressure vessel.

[0005] The vehicle body includes a motor, a reduction box and a box body, wherein two sets of motors and matching reduction boxes are arranged inside the box body; the outputs of the two sets of reduction boxes are respectively connected to the tires on both sides of the box body, and the vehicle body is controlled to move forward, backward or turn through the independent power output of the two sets of motors.

[0006] The two reduction boxes are connected to two motors respectively; two groups of bevel gears are arranged on the box body at the output end of the reduction box through bearings, and the center holes of the bevel gears are connected to the reduction box rotor; the outer circles of the two groups of bevel gears are connected to the transmission shafts arranged at the left and right ends of the box body, and gears are arranged on the transmission shafts, which are connected to the rotating shafts arranged at the other end of the same side of the box body through a plurality of gear transmissions, and tires or tracks are arranged on the transmission shafts and the rotating shafts extending out of the box body, and two motors are used to provide independent power output for the tires or tracks on the left and right sides of the box body, respectively, so as to realize the forward, backward and turning of the vehicle body.

[0007] The multi-degree-of-freedom robotic arm includes a base, a primary joint and a secondary joint, wherein the lower end of the primary joint is connected to the base via a primary transmission shaft, so that the primary joint rotates relative to the base around the primary transmission shaft; the secondary joint of the secondary rod-like structure is connected to the upper end of the primary joint via the secondary transmission shaft, so that the secondary joint can rotate relative to the upper end of the primary joint around the secondary transmission shaft; the gimbal camera is fixed at the end of the secondary joint.

[0008] The pan-tilt camera comprises a camera base, a rotating ring and a pitch ball, wherein the rotating ring 18 is fixed on the camera base, and a pitch ball is installed on the end of the rotating ring. The rotating ring can rotate 360 ​​degrees around the camera base, and the pitch ball can pitch 180 degrees around the rotating ring; a camera and an LED light are fixedly installed on the pitch ball.

[0009] A method for video inspection of the Ω weld at the lower part of a control rod drive mechanism, the method specifically comprising the following steps:

[0010] Step 1: Place the video inspection device into the insulation layer;

[0011] Sending the video inspection device in the contracted state into the insulation layer through the ventilation hole on the top cover of the reactor pressure vessel;

[0012] Step 2: Control the video inspection device to move along a fixed route and inspect the Ω weld of the control rod drive mechanism;

[0013] The multi-freedom robot arm is used to raise the camera to a certain height to the vicinity of the Ω weld of the control rod drive mechanism. The video inspection device moves along the channel formed between the control rod drive mechanisms, and the camera is used to inspect the Ω weld of the control rod drive mechanism on the channel.

[0014] In step 1, the video inspection device enters the interior of the insulation layer from any one of the four ventilation holes evenly distributed around the insulation layer of the pressure vessel; in step 2, the walking route includes all area routes that can be reached by all video inspection devices moving forward, backward and turning.

[0015] The four ventilation holes include ventilation hole A, ventilation hole B, ventilation hole C and ventilation hole D, a total of 4 evenly distributed ventilation holes. There are 4 blank areas where there is no control rod drive mechanism near the right side of the above 4 ventilation holes, namely the first blank area, the second blank area, the third blank area and the fourth blank area; the video inspection device can turn in the first blank area, the second blank area, the third blank area and the fourth blank area respectively after entering ventilation hole A, ventilation hole B, ventilation hole C and ventilation hole D.

[0016] The video inspection device enters the interior of the insulation layer from the four ventilation holes in turn, and inspects the Ω welds of all control rod drive mechanisms that can be walked and covered.

[0017] The remarkable effect of the present invention is that: the device and method for video inspection of the Ω weld at the bottom of the control rod drive mechanism described in the present invention adopts a wheeled vehicle equipped with a mechanical arm and a pan-tilt camera to perform video inspection on the Ω weld of the control rod drive mechanism, which can solve the problem of video inspection of the control rod drive mechanism in a high radiation environment, a confined space and densely distributed without removing the insulation layer, realizes automatic collection, reduces the radiation dose of personnel, achieves the coverage rate of weld inspection, and shortens the inspection time. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A cross-sectional view of the installation of a control rod drive mechanism on an existing reactor pressure vessel top cover;

[0019] Figure 2 A top view of the distribution of control rod drive mechanisms on the top cover of an existing reactor pressure vessel;

[0020] Figure 3 It is a structural schematic diagram of a video inspection device for the Ω weld at the lower part of a control rod drive mechanism according to the present invention;

[0021] Figure 4 A side view of a video inspection device for the Ω weld at the lower portion of a control rod drive mechanism according to the present invention;

[0022] Figure 5 It is a schematic diagram of a folded state of a video inspection device for the Ω weld at the lower part of a control rod drive mechanism according to the present invention;

[0023] Figure 6 It is a schematic diagram of the structure of the vehicle body in the video inspection device for the Ω weld at the lower part of the control rod drive mechanism according to the present invention;

[0024] Figure 7 It is a schematic diagram of the structure of a multi-degree-of-freedom mechanical arm in a video inspection device for the Ω weld at the lower part of a control rod drive mechanism according to the present invention;

[0025] Figure 8It is a schematic diagram of the structure of a pan / tilt camera in a video inspection device for the Ω weld at the lower part of a control rod drive mechanism according to the present invention;

[0026] Fig. 9 for Figure 8 Side view of

[0027] Fig.10 It is a schematic diagram of the deployment of a video inspection device for the Ω weld at the lower part of a control rod drive mechanism according to the present invention in the thermal insulation layer on the top cover of a reactor pressure vessel;

[0028] Fig.11 It is a schematic diagram of the path of the video inspection device for the Ω weld at the lower part of the control rod drive mechanism according to the present invention in the thermal insulation layer on the top cover of the reactor pressure vessel;

[0029] In the figure: 1. Vehicle body; 2. Multi-DOF robotic arm; 3. PTZ camera; 4. Motor; 5. Reducer; 6. Bevel gear; 7. Bearing; 8. Box; 9. Transmission shaft; 10. Gear; 11. Tire; 12. Base; 13. Primary transmission shaft; 14. Primary joint; 15. Secondary transmission shaft; 16. Secondary joint; 17. Camera base; 18. Rotating ring; 19. Pitch ball; 20. Camera; 21. LED light; 22. First blank area; 23. Second blank area; 24. Third blank area; 25. Fourth blank area. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] like Figures 3 to 5 As shown, a video inspection device for the Ω weld at the lower part of a control rod drive mechanism comprises a vehicle body 1, a multi-degree-of-freedom mechanical arm 2 and a pan-tilt camera 3, wherein the multi-degree-of-freedom mechanical arm 2 is installed on the vehicle body 1, and the pan-tilt camera 3 is installed at the end of the multi-degree-of-freedom mechanical arm 2, the pan-tilt camera 3 can move with the degree-of-freedom mechanical arm 2 within a certain height and a certain range, and the multi-degree-of-freedom mechanical arm 2 can be retracted to the other end, so that the height of the entire video inspection device is reduced, so as to facilitate passing through the ventilation hole on the top cover of the reactor pressure vessel;

[0032] like Figure 6As shown, the vehicle body 1 includes a motor 4, a reduction box 5, a housing 8 and a tire 11, wherein two groups of motors 4 and reduction boxes 5 are installed inside the housing 8, and each reduction box 5 is connected to its own motor 4 to achieve independent power output of the two groups of motors 4; two groups of bevel gears 6 are fixed to the housing 8 at the output end of the reduction box 5 through bearings 7, and the center holes of the bevel gears are connected to the rotor of the reduction box 5; the outer circles of the two groups of bevel gears 6 are connected to the transmission shaft 9 installed at the left and right ends of the housing 8, and the transmission shaft 9 is provided with a gear 10, and is connected to the rotating shaft fixed at the other end of the same side of the housing 8 through a plurality of gear transmissions, and tires 11 or tracks are installed on the transmission shaft 9 and the rotating shaft protruding from the housing 8, and two motors 4 are used to provide independent power output for the tires on both sides of the housing 8, so as to achieve forward, backward and turning of the vehicle body 1.

[0033] like Figure 7 As shown, the multi-DOF robot arm 2 includes a base 12, a primary joint 14 and a secondary joint 16, wherein the lower end of the primary joint 14 of a rod-like structure is connected to the base 12 through a primary transmission shaft 13, so that the primary joint 14 rotates relative to the base 12 around the primary transmission shaft 13; the secondary joint 16 of a secondary rod-like structure is connected to the upper end of the primary joint 14 through a secondary transmission shaft 15, so that the secondary joint 16 can rotate relative to the upper end of the primary joint 14 around the secondary transmission shaft 15; the pan-tilt camera 3 is fixed at the end of the secondary joint 16;

[0034] like Figure 8 , Fig. 9 As shown, the pan-tilt camera 3 includes a camera base 17, a rotating ring 18 and a pitch ball 19, wherein the rotating ring 18 is fixed on the camera base 17, and the pitch ball 19 is installed on the end of the rotating ring 18, the rotating ring 18 can rotate 360 ​​degrees around the camera base, and the pitch ball 19 can pitch 180 degrees around the rotating ring; a camera 20 and an LED light 21 are fixedly installed on the pitch ball 19.

[0035] like Fig.10 , Fig.11 As shown, a video inspection method for the Ω weld at the lower part of a control rod drive mechanism is provided, and the method specifically comprises the following steps:

[0036] Step 1: Place the video inspection device into the insulation layer;

[0037] Sending the video inspection device in the contracted state into the insulation layer through the ventilation hole on the top cover of the reactor pressure vessel;

[0038] Step 2: Control the video inspection device to move along a fixed route and inspect the Ω weld of the control rod drive mechanism;

[0039] The video inspection device enters the insulation layer from any of the four ventilation holes evenly distributed around the insulation layer of the pressure vessel, and uses a multi-degree-of-freedom robotic arm to raise the camera to a certain height to the vicinity of the Ω weld of the control rod drive mechanism. The trolley inspects the Ω weld of the control rod drive mechanism involved in the four channels to the lower right of the ventilation hole along the straight channel formed by the two rows of control rod drive mechanisms opposite to the ventilation hole entered; for example, Fig.11 , there are 4 ventilation holes, namely ventilation hole A, ventilation hole B, ventilation hole C and ventilation hole D, evenly distributed around the insulation layer of the pressure vessel, and there are 4 blank areas without control rod drive mechanisms distributed on the right side near the above 4 ventilation holes, namely the first blank area 22, the second blank area 23, the third blank area 24 and the fourth blank area 25; wherein, the video inspection device entering the insulation layer from the ventilation hole A can move forward or backward along the straight channel between the two rows of control rod drive mechanisms communicating between the ventilation hole A and the ventilation hole C, and the multi-degree-of-freedom mechanical arm on the vehicle body 1 is used to raise the camera to the vicinity of the weld seam range of the control rod drive mechanism Ω, and the video inspection device on the straight channel can move forward or backward along the straight channel between the two rows of control rod drive mechanisms communicating between the ventilation hole A and the ventilation hole C, and the video inspection device can move forward or backward along the straight channel between the two rows of control rod drive mechanisms communicating between the ventilation hole A and the ventilation hole C, and the video inspection device can move forward or backward along the straight channel between the two rows of control rod drive mechanisms communicating with ... At the same time, the video inspection device entering the thermal insulation layer from the ventilation hole A can make use of the first blank area 22 to make the video inspection device turn and cover all the control rod drive mechanism channels that can be walked through the straight line and the first blank area 22, so as to realize the video inspection of the control rod drive mechanism Ω welds on the covered channels; similarly, the thermal insulation layer is entered from the ventilation hole B, the ventilation hole C, and the ventilation hole D in turn, and the blank area on the right side of each ventilation hole is used to realize the video inspection of the control rod drive mechanism Ω welds on all channels that can be covered by the video inspection device along the straight line and the blank area.

Claims

1. A video inspection device for the Ω weld at the lower part of a control rod drive mechanism, characterized in that: The device comprises a vehicle body (1), a multi-degree-of-freedom mechanical arm (2) and a pan-tilt camera (3), wherein the vehicle body (1) can move straight, move backward and turn, and a multi-degree-of-freedom mechanical arm (2) is arranged on the vehicle body (1), and the multi-degree-of-freedom mechanical arm (2) can be folded or the end thereof can be raised to a certain height; a pan-tilt camera is arranged at the end of the multi-degree-of-freedom mechanical arm (2); when the multi-degree-of-freedom mechanical arm (2) is in a folded state, the inspection device as a whole can enter the thermal insulation layer through the ventilation hole at the upper end of the pressure vessel; the vehicle body (1) comprises a motor (4), a reduction gear box (5) and a housing (8), wherein two groups of motors (4) and matching reduction gear boxes (5) are arranged inside the housing (8); the two groups The output of the reduction box (5) is respectively connected to the tires (11) on both sides of the box body (8) through transmission, and the two groups of motors (4) independently output power to control the vehicle body (1) to move forward, backward or turn; the multi-degree-of-freedom mechanical arm (2) comprises a base (12), a primary joint (14) and a secondary joint (16), wherein the lower end of the primary joint (14) is connected to the base (12) through a primary transmission shaft (13), so that the primary joint (14) rotates relative to the base (12) around the primary transmission shaft (13); the secondary joint (16) of the secondary rod-shaped structure is connected to the upper end of the primary joint (14) through the secondary transmission shaft (15), so that the secondary joint (16) can rotate around the primary transmission shaft (13). The secondary transmission shaft (15) rotates relative to the upper end of the primary joint (14); the pan-tilt camera (3) is fixed at the end of the secondary joint (16); the two groups of reduction boxes (5) are respectively connected to the two motors (4); the two groups of bevel gears (6) are arranged on the housing (8) at the output end of the reduction box (5) through bearings (7), and the center holes of the bevel gears (6) are connected to the rotor of the reduction box (5); the outer circles of the two groups of bevel gears (6) are connected to the transmission shafts (9) arranged at the left and right ends of the housing (8), and the transmission shafts (9) are provided with gears (10), which are connected to the rotating shafts arranged at the other end of the same side of the housing (8) through a plurality of gear transmissions, and are connected to the transmission shafts on the housing (8). Tires (11) or tracks are arranged on the shaft (9) and the rotating shaft, and two motors are used to provide independent power output for the tires or tracks on the left and right sides of the box body (8), so as to realize the forward, backward and turning movement of the vehicle body (1); the pan-tilt camera (3) comprises a camera base (17), a rotating ring (18) and a pitch ball (19), wherein the rotating ring (18) is fixed on the camera base (17), and the pitch ball (19) is installed on the end of the rotating ring (18), the rotating ring (18) can rotate 360 ​​degrees around the camera base, and the pitch ball (19) can pitch 180 degrees around the rotating ring; and a camera (20) and an LED light (21) are fixedly installed on the pitch ball (19).

2. A method for inspecting the Ω weld video device at the lower portion of the control rod drive mechanism according to claim 1, characterized in that: The method specifically comprises the following steps: Step 1: Place the video inspection device into the insulation layer; Sending the video inspection device in the contracted state into the insulation layer through the ventilation hole on the top cover of the reactor pressure vessel; Step 2: Control the video inspection device to move along a fixed route and inspect the Ω weld of the control rod drive mechanism; The multi-freedom robot arm is used to raise the camera to a certain height to the vicinity of the Ω weld of the control rod drive mechanism. The video inspection device moves along the channel formed between the control rod drive mechanisms, and the camera is used to inspect the Ω weld of the control rod drive mechanism on the channel.

3. The method for inspecting the Ω weld device at the lower part of the control rod drive mechanism according to claim 2, characterized in that: In step 1, the video inspection device enters the interior of the insulation layer from any one of the four ventilation holes evenly distributed around the insulation layer of the pressure vessel; in step 2, the walking route includes all area routes that can be reached by all video inspection devices moving forward, backward and turning.

4. The inspection method of the control rod drive mechanism lower Ω weld inspection device according to claim 3, characterized in that: The four ventilation holes include ventilation hole A, ventilation hole B, ventilation hole C and ventilation hole D, a total of four evenly distributed ventilation holes. There are four blank areas where no control rod drive mechanism exists near the right side of the above four ventilation holes, namely the first blank area, the second blank area, the third blank area and the fourth blank area; the video inspection device can turn in the first blank area, the second blank area, the third blank area and the fourth blank area respectively after entering ventilation hole A, ventilation hole B, ventilation hole C and ventilation hole D.

5. The inspection method of the control rod drive mechanism lower Ω weld inspection device according to claim 3 or 4, characterized in that: The video inspection device enters the interior of the insulation layer from the four ventilation holes in turn, and inspects the Ω welds of all control rod drive mechanisms that can be walked and covered.

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