Nuclear reactor pressure vessel nozzle underwater radiographic full-automatic inspection apparatus and method

Abstract

The application discloses a nuclear reactor pressure vessel nozzle underwater ray full-automatic inspection equipment and method, which comprises an underwater inspection device, the underwater inspection device comprises a device body, buoyancy blocks are fixedly installed at the front end and the rear end of the device body, a ballast water tank is fixedly arranged at the bottom of the device body, and a sensor concentrator box is fixedly arranged at the rear part of the device body; an air bag assembly is installed on the front end face of the device body through an air bag movement mechanism, and a front screw propeller is fixedly installed on the upper connecting plate of the air bag movement mechanism. The device comprises a device body, a gas generating device, a propelling device, an independent power supply system, a ballast gas tank and related accessories, mainly plays a role of providing a fixed place for all other modules of the device, realizing zero gravity of the device, realizing full-automatic inspection without assistance of people, and greatly reducing the work load and the radiation dose equivalent of people.

Description

Technical Field

[0001] This invention specifically relates to the field of underwater inspection technology for nuclear reactor pressure vessel nozzles, and more specifically to fully automated underwater X-ray inspection equipment and method for nuclear reactor pressure vessel nozzles. Background Technology

[0002] Radiographic inspection of the safety end welds of reactor pressure vessel nozzles is a mandatory inspection item according to RSEM specifications; the inspection phase is divided into pre-service inspection and a ten-year cycle inspection during service.

[0003] During in-service inspections, the radiation dose around the reactor pool is high, making close-range radiographic testing impossible. Radiographic testing of the safety end welds of the reactor pressure vessel nozzles must be performed using long-range underwater inspection equipment.

[0004] The reactor pressure vessel has three inlet nozzles and three outlet nozzles. Each nozzle has one dissimilar metal weld and one homogeneous metal weld. The center-to-center distance between the two welds on the nozzle is 110-150 mm. The X-ray source inspection stroke needs to fully cover each weld.

[0005] Based on the weld geometry, the optimal method for radiographic inspection is to expose the center of the weld seam, so the X-ray source must always be located at the center of the circumferential weld.

[0006] Currently, during in-service inspections of nuclear power plants in China, most reactor pressure vessel (RPV) nozzle inspection equipment is semi-automatic. This equipment can be used by multiple units simultaneously, resulting in higher inspection efficiency than other existing fully automated radiographic inspection equipment. This semi-automatic inspection equipment typically performs inspections when the nozzle is full of water, requiring manual assistance for positioning to complete the inspection. The workflow for this type of RPV inspection equipment is as follows: First, the inspection equipment is hoisted into the reactor core pool using a hoist from the nuclear island. Personnel at the reactor core pool guide the equipment into the inspection nozzle, manually guiding it into the RPV nozzle for positioning, followed by semi-automatic radiographic inspection. Finally, the RPV inspection equipment is again manually guided to other nozzles for positioning and radiographic inspection. The inspection process requires a large number of personnel working together, including remote control system operators, cable handling personnel, personnel guiding the equipment into the nozzle, and communication personnel. Therefore, this type of RPV inspection equipment has the following problems: low degree of automation, requiring manual guidance for positioning each time; personnel working near the reactor core pool will inevitably be exposed to environmental radiation damage; the equipment has many structural accessories, requiring a large number of personnel to cooperate in the inspection work; when the equipment is working underwater, it is not in a zero-gravity state, requiring manual adjustment of the equipment's buoyancy state by applying force through the operating rod before it can be connected to the pipeline. Summary of the Invention

[0007] To address these issues, the present invention proposes a fully automated underwater X-ray inspection system and method for nuclear reactor pressure vessel nozzles to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: an automated underwater X-ray inspection system for nuclear reactor pressure vessel nozzles, comprising underwater inspection equipment, wherein the underwater inspection equipment includes...

[0009] The equipment body has buoyancy blocks fixedly installed at both the front and rear ends, a ballast water tank fixedly installed at the bottom of the equipment body, and a sensor hub box fixedly installed at the rear of the equipment body.

[0010] An airbag assembly is mounted on the front end face of the device body using an airbag motion mechanism. A front spiral propeller is fixedly mounted on the upper connecting plate of the airbag motion mechanism.

[0011] The first pneumatic adjustment support leg is provided in three parts, and the three first pneumatic adjustment support legs are fixed and arranged in a circumferential array on the side wall of the front part of the device body.

[0012] The second pneumatic adjustment support leg is provided in three parts, and the three second pneumatic adjustment support legs are fixed and arranged in a circumferential array on the side wall of the middle part of the device body.

[0013] And a proximity thrust mechanism, wherein four proximity thrust mechanisms are provided, the four proximity thrust mechanisms are fixed and arranged in a circumferential array on the side wall of the rear part of the equipment body, and a rear helical propeller is fixedly installed on the rear side wall of each proximity thrust mechanism.

[0014] Furthermore, as a preferred embodiment, an isolation plate is fixedly installed in the inner cavity of the device body, which divides the inner cavity of the device body into a front cavity and a rear cavity. The front cavity is equipped with a radiation source, a dose rate sensor, and a water pressure sensor, while the rear cavity is equipped with a power supply system, an underwater control system, and a gas generation and control module.

[0015] Furthermore, as a preferred embodiment, the approach thrust mechanism includes a proximity switch and a thrust mechanism. One end of the thrust mechanism is fixed to the equipment body, and the other end of the thrust mechanism is fixedly equipped with a proximity switch. When the thrust mechanism approaches the inner wall of the RPV core pool, the proximity switch transmits a signal to the underwater control system and the host computer.

[0016] Furthermore, as a preferred embodiment, an underwater signal receiving module and an emergency recovery device for radioactive sources are fixedly installed on the side wall at the rear of the device body.

[0017] Furthermore, as a preferred embodiment, an underwater camera is fixedly installed at the rear end of the device body.

[0018] Furthermore, as a preferred embodiment, a hoisting connection mechanism is fixedly installed on the upper cover plate of the device body.

[0019] A fully automated underwater X-ray inspection method for nuclear reactor pressure vessel nozzles includes the following steps:

[0020] S1: Place the underwater inspection equipment at the commissioning site, install the radiation source into the cavity of the underwater inspection equipment, and connect the various equipment components;

[0021] S2: Test the airtightness of the underwater inspection equipment, verify the functionality of each component, and release the residual pressure inside the airbag assembly;

[0022] S3: Connect the nuclear island hoist and install the hoisting connection mechanism;

[0023] S4: Hoist the underwater inspection equipment to the RPV core pool and automatically unhook it;

[0024] S5: Confirm the receiver to be tested;

[0025] S6: Personnel can access the temporary bridge over the RPV core pool, operate the host computer to move the tablet, or remotely operate the equipment from the workbench via the environmental monitoring camera.

[0026] S7: Adjust the pressure of the ballast water tank and adjust the attitude of the underwater inspection equipment to bring the underwater inspection equipment into a zero-gravity state.

[0027] S8: Open the rear propellers located on the left and right sides to slowly push the underwater inspection equipment into the pipe to be inspected;

[0028] S9: Extends three first pneumatic adjustable support legs and one second pneumatic adjustable support leg located below;

[0029] S10: Activate the rear propellers located on the upper and lower sides to increase propulsion;

[0030] S11: Observe the proximity thrust mechanism signal. When all four proximity switch signals are lit, quickly extend the other two second pneumatic adjustment support legs.

[0031] S12: Disconnect all propeller motors and enable the airbag motors in the airbag assembly;

[0032] S13: Input the coordinates of the weld to be inspected. The head of the airbag assembly moves forward to the center of the weld to be inspected and the airbag motor is disconnected.

[0033] S14: The airbag in the airbag assembly inflates, and the underwater camera observation equipment and airbag status are monitored.

[0034] S15: After the airbag is fully inflated, confirm with the personnel covering the outer panel whether they need to leave the flaw detection room;

[0035] S16: Turn on the source output switch of the radiation source machine;

[0036] S17: Enable the source motor, and the radiation source moves from the source tube to the collimator in the center of the airbag for circumferential exposure;

[0037] S18: Disconnect the power source motor and wait for the exposure time to end;

[0038] S19: Exposure ends. Enable the source motor and retrieve the radioactive source to the source machine.

[0039] S20: The airbag deflates and moves to the center of another weld seam. Repeat the process steps S14 to S19.

[0040] S21: Flaw detection of this connector is completed. Switch connectors, deflate the airbag, and start the system to the initial airbag position.

[0041] S22: Observe the parameters of the underwater inspection equipment, adjust the pressure of the ballast water tank, adjust the attitude of the underwater inspection equipment, and put the underwater inspection equipment in a zero-gravity state.

[0042] S23: Retract all first and second pneumatic adjustable support legs;

[0043] S24: Open the four rear propellers and reverse the operation to remove the underwater inspection equipment from the control unit;

[0044] S25: Repeat process actions S5~S24;

[0045] S26: After all the pipework inspections are completed, the underwater inspection equipment is removed from the pipework, and the hoisting connection mechanism is remotely connected to lift the underwater inspection equipment out of the RPV core.

[0046] S27: Transferred to the commissioning site, inspection completed.

[0047] The present invention adopts the above technology and has the following beneficial effects compared with the existing technology: The device of the present invention includes the equipment body, gas generating device, propulsion device, independent power supply system, ballast air tank and related accessories. Its main function is to provide a fixed place for all other modules of the equipment, realize zero gravity of the equipment, and perform unmanned assisted fully automatic inspection, which greatly reduces the workload of personnel and radiation dose equivalent. Attached Figure Description

[0048] Figure 1 A schematic diagram of a fully automated underwater X-ray inspection system for nuclear reactor pressure vessel connections.

[0049] Figure 2A side view of the fully automated underwater X-ray inspection equipment for the nozzles of a nuclear reactor pressure vessel;

[0050] Figure 3 A schematic diagram of the internal structure of an underwater X-ray fully automated inspection system for nuclear reactor pressure vessel connections.

[0051] Figure 4 Schematic diagram of the operation of the fully automated underwater X-ray inspection equipment for nuclear reactor pressure vessel connections. Figure 1 ;

[0052] Figure 5 Schematic diagram of the operation of the fully automated underwater X-ray inspection equipment for nuclear reactor pressure vessel connections. Figure 2 .

[0053] In the diagram: 1. Airbag assembly; 2. Front propeller; 3. First pneumatically adjustable support leg; 4. Approach thrust mechanism; 5. Lifting connection mechanism; 6. Buoyancy block; 7. Second pneumatically adjustable support leg; 9. Rear propeller; 11. Underwater signal receiving module; 12. Airbag movement mechanism; 15. Ballast water tank; 17. Sensor hub box; 21. Underwater camera; 22. Equipment body; 23. Emergency recovery radioactive source device; 24. Radioactive source machine; 25. Power supply system; 26. Gas generation and control module; 27. Water pressure sensor; 28. Isolation plate; 29. ​​Underwater control system; 30. Dose rate sensor; 31. RPV core pool; 32. Connector to be inspected; 33. Underwater inspection equipment; 34. Equipment environment camera; 35. Signal repeater; 36. Temporary bridge. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] Example: Please refer to the appendix Figure 1-5 This invention provides a technical solution: an underwater X-ray fully automated inspection equipment for nuclear reactor pressure vessel nozzles, comprising an underwater inspection device 33, which includes...

[0056] The equipment body 22 has buoyancy blocks 6 fixedly installed at both the front and rear ends, a ballast water tank 15 fixedly installed at the bottom of the equipment body 22, and a sensor hub box 17 fixedly installed at the rear of the equipment body 22.

[0057] Specifically, buoyancy block 6 is mainly used to increase the overall buoyancy of the equipment, so that the equipment can maintain a zero-gravity state;

[0058] It should be added that the ballast water tank 15 mainly consists of a cavity and a piston, and its main function is to adjust the zero-gravity state of the equipment. The zero-gravity state of the equipment is an important factor in the fully automated inspection of the equipment.

[0059] Airbag assembly 1, the airbag assembly 1 is installed on the front end face of the equipment body 22 by an airbag motion mechanism 12, and a front spiral propeller 2 is fixedly installed on the upper connecting plate of the airbag motion mechanism 12. The overall posture of the equipment is adjusted by the forward and reverse rotation of the front spiral propeller 2.

[0060] Specifically, the airbag movement mechanism 12 allows the airbag to have different strokes, enabling the inspection of welds with different strokes, including welds of the same type of steel and welds of different types of steel;

[0061] The first pneumatic adjustment support leg 3 is provided in three parts, and the three first pneumatic adjustment support legs 3 are fixed and arranged in a circular array on the side wall at the front of the device body 22.

[0062] The second pneumatic adjustment support leg 7, three of which are fixed and arranged in a circumferential array on the side wall of the middle part of the equipment body 22.

[0063] And a proximity thrust mechanism 4, there are four proximity thrust mechanisms 4, the four proximity thrust mechanisms 4 are fixed and arranged in a circumferential array on the side wall of the rear part of the equipment body 22, and a rear spiral propeller 9 is fixedly installed on the rear side wall of each proximity thrust mechanism 4.

[0064] Specifically, the rear spiral propeller 9 can operate in both forward and reverse directions. Forward rotation drives the equipment forward, and reverse rotation drives the equipment backward. In addition, the equipment's posture can be quickly adjusted through the rear spiral propeller 9 in the four directions of up, down, left, and right.

[0065] In this embodiment, an isolation plate 28 is fixedly installed in the inner cavity of the device body 22. The isolation plate 28 divides the inner cavity of the device body 22 into a front cavity and a rear cavity. The front cavity is equipped with a radiation source machine 24, a dose rate sensor 30 and a water pressure sensor 27. The rear cavity is equipped with a power supply system 25, an underwater control system 29 and a gas generation and control module 26.

[0066] Specifically, the isolation plate 28 can reduce the instantaneous dose rate when the source is receiving or releasing the source, thus protecting precision instruments;

[0067] The power supply system 25 includes a lithium battery and a voltage conversion module, whose main function is to provide all the power for the entire device;

[0068] The underwater control system 29 mainly includes a motor control module, a sensor module, and an instruction processing module. Its main function is to process signals and issue relevant instructions. The motor control module mainly controls the airbag forward motor and the radiation source receiver / discharge motor; the sensor module mainly receives and sends sensor signals.

[0069] In this embodiment, the proximity thrust mechanism 4 includes a proximity switch and a thrust mechanism. One end of the thrust mechanism is fixed to the equipment body 22, and the other end of the thrust mechanism is fixedly installed with a proximity switch. When the thrust mechanism approaches the inner wall of the RPV core pool 31, the proximity switch transmits a signal to the underwater control system 29 and the host computer.

[0070] In this embodiment, an underwater signal receiving module 11 and an emergency recovery device for radioactive sources 23 are fixedly installed on the side wall of the rear part of the device body 22.

[0071] Specifically, the emergency radioactive source recovery device 23 is normally driven by a motor to recover and release the source. In emergency situations such as motor failure, the radioactive source can be manually recovered through a connecting rod mechanism.

[0072] In this embodiment, an underwater camera 21 is fixedly installed at the rear end of the device body 22.

[0073] In this embodiment, a hoisting connection mechanism 5 is fixedly installed on the upper cover plate of the equipment body 22. The other half of the hoisting mechanism is connected to the hook of the ring. This mechanism is controlled by a pneumatic switch and can remotely release and lock the equipment.

[0074] A fully automated underwater X-ray inspection method for nuclear reactor pressure vessel nozzles includes the following steps:

[0075] S1: Place the underwater inspection equipment 33 in the commissioning site, install the radiation source machine 24 into the cavity of the underwater inspection equipment 33, and connect the various equipment components;

[0076] S2: Test the airtightness of the underwater inspection equipment 33, verify the functionality of each component of the equipment, and release the residual pressure inside the airbag assembly 1;

[0077] S3: Connect the nuclear island hoist and install the hoisting connection mechanism 5;

[0078] S4: Hoist the underwater inspection equipment 33 to the RPV core pool 31 and automatically unhook it;

[0079] S5: Confirm the connector 32 to be tested;

[0080] S6: Personnel can go to the temporary bridge 36 on the RPV core pool 31, operate the host computer moving tablet, or remotely operate the equipment through the environmental monitoring camera at the workbench;

[0081] S7: Adjust the pressure of the ballast water tank 15 and adjust the attitude of the underwater inspection equipment 33 so that the underwater inspection equipment 33 is in a zero-gravity state.

[0082] S8: Open the rear propellers 9 located on the left and right sides to slowly push the underwater inspection equipment 33 into the pipe 32 to be inspected;

[0083] S9: Extend three first pneumatic adjustable support legs 3 and one second pneumatic adjustable support leg 7 located below;

[0084] S10: Activate the rear propellers 9 located on the upper and lower sides to increase propulsion;

[0085] S11: Observe the proximity thrust mechanism 4 signal. When all 4 proximity switch signals are lit, quickly extend the other two second pneumatic adjustment support legs 7.

[0086] S12: Disconnect all propeller motors and enable the airbag motor in airbag assembly 1;

[0087] S13: Input the coordinates of the weld to be inspected. The head of the airbag assembly 1 moves forward to the center of the weld to be inspected and the airbag motor is disconnected.

[0088] S14: The airbag in airbag assembly 1 is inflated, and underwater camera 21 observes the equipment and airbag status;

[0089] S15: After the airbag is fully inflated, confirm with the personnel covering the outer panel whether they need to leave the flaw detection room;

[0090] S16: Turn on the source output switch 24 of the radiation source machine;

[0091] S17: Enable the source motor, and the radiation source moves from the source tube to the collimator in the center of the airbag for circumferential exposure;

[0092] S18: Disconnect the power source motor and wait for the exposure time to end;

[0093] S19: Exposure ends. Enable the source motor and recover the radioactive source to the radioactive source machine 24.

[0094] S20: The airbag deflates and moves to the center of another weld seam. Repeat the process steps S14 to S19.

[0095] S21: Flaw detection of this connector is completed. Switch connectors, deflate the airbag, and start the system to the initial airbag position.

[0096] S22: Observe the parameters of the underwater inspection equipment 33, adjust the pressure of the ballast water tank 15, adjust the attitude of the underwater inspection equipment 33, and put the underwater inspection equipment 33 into a zero-gravity state.

[0097] S23: Retract all first pneumatic adjustable support legs 3 and second pneumatic adjustable support legs 7;

[0098] S24: Open the four rear propellers 9 and reverse the operation to remove the underwater inspection equipment 33 from the control unit;

[0099] S25: Repeat process actions S5~S24;

[0100] S26: After all the pipework inspections are completed, the underwater inspection equipment 33 is removed from the pipework and the remote connection hoisting mechanism 5 is used to lift the underwater inspection equipment 33 out of the RPV core.

[0101] S27: Transferred to the commissioning site, inspection completed.

[0102] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fully automated underwater X-ray inspection system for nuclear reactor pressure vessel nozzles, comprising underwater inspection equipment (33), characterized in that: The underwater inspection equipment (33) includes: The equipment body (22) has buoyancy blocks (6) fixedly installed at both the front and rear ends, a ballast water tank (15) fixedly installed at the bottom of the equipment body (22), and a sensor hub box (17) fixedly installed at the rear of the equipment body (22). Airbag assembly (1), wherein the airbag assembly (1) is mounted on the front end face of the device body (22) by an airbag motion mechanism (12), and a front spiral propeller (2) is fixedly mounted on the upper connecting plate of the airbag motion mechanism (12); First pneumatic adjustment support leg (3), three first pneumatic adjustment support legs (3) are provided, and the three first pneumatic adjustment support legs (3) are fixed and arranged in a circular array on the side wall of the front part of the device body (22); The second pneumatic adjustment support leg (7) is provided in three parts, and the three second pneumatic adjustment support legs (7) are fixed and arranged in a circular array on the side wall of the middle part of the device body (22); And a proximity thrust mechanism (4), of which four are provided, the four proximity thrust mechanisms (4) are fixed and arranged in a circular array on the side wall of the rear part of the equipment body (22), and a rear spiral propeller (9) is fixedly installed on the rear side wall of each proximity thrust mechanism (4); An isolation plate (28) is fixedly installed in the inner cavity of the device body (22). The isolation plate (28) divides the inner cavity of the device body (22) into a front cavity and a rear cavity. The front cavity is equipped with a radiation source machine (24), a dose rate sensor (30) and a water pressure sensor (27). The rear cavity is equipped with a power supply system (25), an underwater control system (29) and a gas generation and control module (26). The proximity thrust mechanism (4) includes a proximity switch and a thrust mechanism. One end of the thrust mechanism is fixed to the equipment body (22), and the other end of the thrust mechanism is fixedly installed with a proximity switch. When the thrust mechanism approaches the inner wall of the RPV core pool (31), the proximity switch transmits a signal to the underwater control system (29) and the host computer.

2. The fully automated underwater X-ray inspection equipment for nuclear reactor pressure vessel nozzles according to claim 1, characterized in that: An underwater signal receiving module (11) and an emergency recovery device for radioactive sources (23) are fixedly installed on the side wall of the rear part of the device body (22).

3. The fully automated underwater X-ray inspection equipment for nuclear reactor pressure vessel nozzles according to claim 1, characterized in that: An underwater camera (21) is fixedly installed at the rear end of the device body (22).

4. The fully automated underwater X-ray inspection equipment for nuclear reactor pressure vessel nozzles according to claim 1, characterized in that: A hoisting connection mechanism (5) is fixedly installed on the upper cover plate of the equipment body (22).

5. A fully automated underwater X-ray inspection method for nuclear reactor pressure vessel nozzles, employing the fully automated underwater X-ray inspection equipment for nuclear reactor pressure vessel nozzles as described in any one of claims 1-4, characterized in that... Includes the following steps: S1: Place the underwater inspection equipment (33) in the debugging site, install the radiation source machine (24) into the cavity of the underwater inspection equipment (33), and connect the various equipment components; S2: Test the airtightness of the underwater inspection equipment (33), verify the functionality of each component of the equipment, and release the residual pressure inside the airbag assembly (1); S3: Connect the nuclear island hoist and install the hoisting connection mechanism (5); S4: Lift the underwater inspection equipment (33) to the RPV core pool (31) and automatically unhook it; S5: Confirm the connector to be tested (32); S6: Personnel go to the temporary bridge (36) on the RPV core pool (31), operate the host computer to move the tablet, or remotely operate the equipment through the environmental monitoring camera at the workbench; S7: Adjust the pressure of the ballast water tank (15), adjust the attitude of the underwater inspection equipment (33), and put the underwater inspection equipment (33) in a zero-gravity state; S8: Open the rear propellers (9) located on the left and right sides, and slowly push the underwater inspection equipment (33) into the inside of the pipe to be inspected (32); S9: Extend three first pneumatic adjustable support legs (3) and one second pneumatic adjustable support leg (7) located below; S10: Open the rear propellers (9) located on the upper and lower sides to increase the propulsion force; S11: Observe the signal of the proximity thrust mechanism (4). When all four proximity switch signals are lit, quickly extend the other two second pneumatic adjustment support legs (7). S12: Disconnect all propeller motors and enable the airbag motor in airbag assembly (1); S13: Input the coordinates of the weld to be inspected, the head of the airbag assembly (1) moves forward to the center of the weld to be inspected, and the airbag motor is disconnected; S14: The airbag in the airbag assembly (1) is inflated, and the underwater camera (21) observes the equipment and the status of the airbag; S15: After the airbag is fully inflated, confirm with personnel whether they need to leave the flaw detection room; S16: Turn on the source switch of the radiation source machine (24); S17: Enable the source motor, and the radiation source moves from the source tube to the collimator in the center of the airbag for circumferential exposure; S18: Disconnect the power source motor and wait for the exposure time to end; S19: Exposure ends, enable the source motor, and recover the radioactive source to the source machine (24); S20: The airbag deflates and moves to the center of another weld seam. Repeat the process steps S14 to S19. S21: Flaw detection of this connector is completed. Switch connectors, deflate the airbag, and start the system to the initial airbag position. S22: Observe the parameters of the underwater inspection equipment (33), adjust the pressure of the ballast water tank (15), adjust the attitude of the underwater inspection equipment (33) to make the underwater inspection equipment (33) in a zero-gravity state; S23: Retract all first pneumatic adjustable support legs (3) and second pneumatic adjustable support legs (7); S24: Open the four rear propellers (9) and reverse the operation to remove the underwater inspection equipment (33) from the control unit; S25: Repeat process actions S5~S24; S26: After all the pipe connections have been inspected, the underwater inspection equipment (33) is removed from the pipe connections and the hoisting connection mechanism (5) is remotely connected to lift the underwater inspection equipment (33) out of the RPV core pool (31). S27: Transferred to the commissioning site, inspection completed.

Images