A reactor in-vessel component outer surface video inspection apparatus and inspection method thereof

Abstract

This invention belongs to the field of in-service inspection technology for nuclear power plants, specifically relating to a video inspection device and method for the outer surface of reactor internal components, comprising: a junction box, a lifting ring, two camera assemblies, a frame, several pulley assemblies, and an axial drive assembly; the junction box and the lifting ring are respectively installed on the top of the frame; the several pulley assemblies are symmetrically installed on both sides of the frame; the axial drive assembly is fixed to the frame assembly by screws and nuts; one camera assembly is fixedly installed on the upper part of the frame, and the other camera assembly is installed on the axial drive assembly.

Description

Technical Field

[0001] This invention belongs to the field of in-service inspection technology of nuclear power plants, specifically relating to a video inspection device and method for the outer surface of reactor internal components. Background Technology

[0002] The reactor internals of a certain type of nuclear power unit include the core basket and the protective tube assembly. The core basket is a vertical cylindrical body with an elliptical bottom, housed within the reactor pressure vessel. It is a crucial piece of equipment for installing and securing the core cladding, placing nuclear fuel assemblies, and providing coolant flow channels within the reactor. The protective tube assembly is a welded metal cylinder, crucial for ensuring the precise vertical and horizontal positioning and isolation of the nuclear fuel assembly heads, as well as for placing control rod assemblies. The reactor internals are characterized by high manufacturing standards and significant technical complexity, and are also difficult to replace. Because the reactor internals are subjected to long-term neutron radiation after operation, they possess high radioactivity and high contamination levels. During service, inspections of these internals require remote and automated auxiliary tools.

[0003] During nuclear power unit refueling overhauls, automated inspection equipment is required to perform in-service inspections of the circumferential welds of reactor core assemblies, such as the reactor core basket and protective tubing assemblies, from the outside. The inspection method is automated video inspection. Existing inspection equipment is installed on dedicated guide rails in the reactor core inspection wells. A mechanical structure controls the vertical movement of the inspection camera along the guide rails; the circumferential relative movement between the camera and the reactor core is achieved by lifting the reactor core components with a large ring crane in the reactor building and rotating them. Using this inspection equipment, inspecting each circumferential weld requires rotating the reactor core component once, resulting in numerous rotations, long inspection times, and low efficiency. The time window for reactor core component inspection during reactor shutdown overhauls is a secondary critical path.

[0004] Therefore, the time required for automatic television inspection of the outer surface of reactor internal components should be minimized. In addition, a large number of critical path maintenance tasks of nuclear power units require the use of ring cranes, and prolonged occupation of ring cranes is not conducive to optimizing the maintenance schedule.

[0005] Therefore, there is an urgent need to develop a new type of inspection device to improve the efficiency of in-service inspection of the outer surface of in-core components, reduce the usage time of the ring crane, shorten the occupation of the inspection period on the critical path of the overhaul, and at the same time reduce the number of rotations of in-core components during the inspection process. Summary of the Invention

[0006] The purpose of this invention is to design a video inspection device and method for the outer surface of reactor internal components, which effectively solves the technical problems of excessive rotation of internal components and long inspection time during the inspection of existing video inspection devices for the outer surface of reactor internal components.

[0007] The technical solution of the present invention:

[0008] A video inspection device for the outer surface of reactor internal components includes: a junction box, a lifting ring, two camera assemblies, a frame, several pulley assemblies, and an axial drive assembly; the junction box and the lifting ring are respectively installed on the top of the frame; the several pulley assemblies are symmetrically installed on both sides of the frame; the axial drive assembly is fixed to the frame assembly by screws and nuts; one camera assembly is fixedly installed on the upper part of the frame, and the other camera assembly is installed on the axial drive assembly.

[0009] The frame includes two vertical beams and three horizontal beams, with three horizontal beams horizontally welded between the two vertical beams. Lifting rings are installed on the top of the frame for easy lifting, transportation, and assembly. The frame is made of stainless steel.

[0010] The axial drive assembly includes a collinear kinematic pair, a lead screw and nut pair, a slider, and a motor; the collinear kinematic pair is provided with a lead screw and nut pair; there is one slider, and the slider has a threaded through hole in the center; the slider is sleeved on the lead screw and nut pair through the threaded through hole, and the slider length is 200mm; the axial drive assembly is fixed to the frame assembly by screws and nuts.

[0011] The slider also has a camera mounting hole, and one of the camera components is threadedly fixed to the slider of the axial drive component.

[0012] The number of pulley assemblies is four, with two pulley assemblies forming a group. They are symmetrically welded and installed at the top and middle positions of the two vertical beams of the frame, respectively, to check the axial sliding of the inspection device along the guide rail in the inspection well of the in-core component equipment under the action of external force.

[0013] Each pulley assembly includes three pulleys arranged in a triangle. The three pulleys can rotate around the central axis of the triangle structure, which facilitates better engagement with the guide rail during installation.

[0014] Each camera assembly is equipped with a high-radiation-resistant camera. The two high-radiation-resistant cameras are arranged horizontally. One camera assembly is fixedly installed on the upper part of the frame, and the other camera assembly is installed on the axial drive assembly. The axial drive assembly moves up and down under the drive of the motor. Both high-radiation-resistant cameras can be tilted up and down. By moving the camera assemblies relative to each other and adjusting the tilt angle of the high-radiation-resistant cameras, video inspection of two objects can be performed simultaneously.

[0015] There are two junction box assemblies, which are installed at the top of the upper part of the frame via threaded connection and are used to install the drive motor and arrange the wires; the junction box assemblies are sealed with dynamic / static sealant.

[0016] A method for inspecting the outer surface of reactor internal components of a nuclear power unit using a video inspection device as described above includes the following steps:

[0017] Step 1: Conduct an underwater airtightness test on the inspection device, install the entire inspection device on the inspection base, and debug the mechanical functions of the inspection device;

[0018] Step 2: Use the ring crane in the reactor building to position and install the inspection base into the reactor shaft inspection equipment well, and transport the inspection device to the dedicated track in the equipment inspection well via pulleys;

[0019] Step 3: Use the stamped markings on the circumferential welds on the outer surface of the in-core components to locate the fixed camera in depth and circumference;

[0020] Step 4: Position the moving camera according to the relative position of the circumferential weld seam on the outer surface of the in-core components to complete the initial positioning of the dual-camera combination;

[0021] Step 5: Under the action of the reactor building's circumferential crane, the internal components of the reactor rotate circumferentially, and video is captured during the rotation until the internal components of the reactor rotate 360°;

[0022] Step Six: After completing a set of video acquisitions, under the mechanical force of the inspection base, control the inspection device to move along the guide rail to the next set of circumferential welds, and adjust the position of the moving camera through the circumferential drive component to perform the next set of video inspections until the inspection is completed.

[0023] The beneficial effects of this invention are:

[0024] The device of this invention has a simple and lightweight mechanical structure; it is easy to install and disassemble; it can be equipped with dual cameras, and two welds can be inspected simultaneously by adjusting the relative distance between the cameras and the pitch angle; operators can remotely operate the equipment to carry out inspections, reducing the risk of personnel being exposed to radiation.

[0025] The camera is designed to withstand high radiation and has a long service life; its overall structure is waterproof and suitable for underwater television inspection.

[0026] The technical solution of this invention has been successfully applied in the video inspection of the outer surface of reactor internals during the first refueling overhaul of Unit 4 of a nuclear power plant, and has passed technical verification. By using the inspection device designed in this invention, two circumferential welds can be inspected simultaneously, reducing the number of rotations of reactor internals and improving inspection efficiency by approximately 40%. Simultaneously, by improving inspection efficiency, the time occupied by the hoist during the inspection process is reduced, providing conditions for optimizing the unit's overhaul schedule. Attached Figure Description

[0027] Figure 1This is a schematic diagram of the structure of a video inspection device for the outer surface of reactor internal components according to the present invention;

[0028] Among them: 1-Distribution box; 2-Lifting ring; 3-Camera assembly; 4-Rack; 5-Pulley assembly; 6-Axial drive assembly. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0030] A video inspection device for the outer surface of reactor internal components includes: a junction box 1, a lifting ring 2, two camera assemblies 3, a frame 4, several pulley assemblies 5, and an axial drive assembly 6; the junction box 1 and the lifting ring 2 are respectively installed on the top of the frame 4; the several pulley assemblies 5 are symmetrically installed on both sides of the frame 4; the axial drive assembly 6 is fixed to the frame assembly 4 by screws and nuts; one camera assembly 3 is fixedly installed on the upper part of the frame 4, and the other camera assembly 3 is installed on the axial drive assembly 6.

[0031] The frame 4 includes two vertical beams and three horizontal beams. The three horizontal beams are horizontally welded between the two vertical beams. The top of the frame 4 is equipped with lifting rings 2 for easy lifting, transportation and assembly. The frame 4 is made of stainless steel, which is lightweight, rigid and strong, and low in cost.

[0032] The axial drive assembly 6 includes a collinear kinematic pair, a lead screw and nut pair, a slider, and a motor. The motor is located on the upper part of the axial drive assembly. There is one slider, and the slider has a threaded through hole in the center. The slider is sleeved on the lead screw and nut pair through the threaded through hole, and the slider length is 200mm. The collinear kinematic pair is provided with a lead screw and nut pair. The axial drive assembly 6 is fixed to the frame assembly 4 by screws and nuts.

[0033] The slider also has camera mounting holes, and one of the camera components 3 is threadedly fixed to the slider of the axial drive component 6.

[0034] There are four pulley assemblies 5. Two pulley assemblies 5 are grouped together and symmetrically welded and installed at the top and middle positions of the two vertical beams of the frame 4, respectively, to check the axial sliding of the device along the guide rail in the inspection well of the in-core component equipment under the action of external force.

[0035] Each pulley assembly 5 includes three pulleys arranged in a triangular configuration. The three pulleys can rotate around the central axis of the triangular structure, which facilitates better engagement with the guide rail during installation. In order to prevent the inspection device from getting stuck in the arc position of the guide rail in the inspection well of the core basket, the pulley assembly 5 is installed at the upper part of the frame 4.

[0036] Each camera assembly 3 is equipped with a high-radiation-resistant camera. The two high-radiation-resistant cameras are arranged horizontally. One camera assembly 3 is fixedly installed on the upper part of the frame 4, and the other camera assembly 3 is installed on the axial drive assembly 6. Driven by the motor of the axial drive assembly, it moves up and down. Both high-radiation-resistant cameras can be adjusted up and down. By moving the camera assemblies 3 relative to each other and adjusting the pitch angle of the high-radiation-resistant cameras, video inspection of two objects under inspection can be carried out simultaneously.

[0037] There are two junction box assemblies 1. The junction box assembly 1 is installed at the top of the upper part of the frame 4 by threaded connection and is used to install the drive motor and arrange the wires. The junction box assembly 1 is sealed with dynamic / static sealant.

[0038] A method for inspecting the outer surface of reactor internal components of a nuclear power unit using a video inspection device as described above includes the following steps:

[0039] Step 1: Conduct an underwater airtightness test on the inspection device, install the entire inspection device on the inspection base, and debug the mechanical functions of the inspection device;

[0040] Step 2: Use the ring crane in the reactor building to position and install the inspection base into the reactor shaft inspection equipment well, and transport the inspection device to the dedicated track in the equipment inspection well via pulleys;

[0041] Step 3: Use the stamped markings on the circumferential welds on the outer surface of the in-core components to locate the fixed camera in depth and circumference;

[0042] Step 4: Position the moving camera according to the relative position of the circumferential weld seam on the outer surface of the in-core components to complete the initial positioning of the dual-camera combination;

[0043] Step 5: Under the action of the reactor building's circumferential crane, the internal components of the reactor rotate circumferentially, and video is captured during the rotation until the internal components of the reactor rotate 360°;

[0044] Step Six: After completing a set of video acquisitions, under the mechanical force of the inspection base, control the inspection device to move along the guide rail to the next set of circumferential welds, and adjust the position of the moving camera through the circumferential drive component to perform the next set of video inspections until the inspection is completed.

[0045] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. All contents not described in detail in the present invention can be derived from existing technologies.

Claims

1. A reactor in-core component outer surface video inspection apparatus, characterized by, Include: The junction box assembly (1), the lifting ring (2), two camera assemblies (3), rack assembly (4), several pulley assemblies (5) and axial drive assembly (6); the top of the rack assembly (4) is respectively provided with the junction box assembly (1) and the lifting ring (2); the several pulley assemblies (5) are symmetrically installed on both sides of the rack assembly (4); the axial drive assembly (6) is fixed to the rack assembly (4) by screw nut; one of the camera assemblies (3) is fixedly installed on the upper part of the rack assembly (4), and the other camera assembly (3) is installed on the axial drive assembly (6); The rack assembly (4) includes two vertical beams and three horizontal beams, three horizontal beams are horizontally welded between the two vertical beams, the lifting ring (2) is installed on the top of the rack assembly (4), which is convenient for hoisting transportation and assembly; the number of the pulley assembly (5) is four, two pulley assemblies (5) are a group, which are symmetrically welded and installed at the top and middle positions of the two vertical beams of the rack assembly (4), used for checking the axial sliding of the device along the guide rail in the in-vessel component equipment inspection shaft under external force; each pulley assembly (5) includes three pulleys, the three pulleys are arranged in a triangular combination, and the three pulleys rotate around the central axis of the combined triangular structure, which is convenient for better meshing with the guide rail during installation; Each camera assembly (3) is provided with a high radiation resistant camera, and two high radiation resistant cameras are horizontally arranged, one of the camera assemblies (3) is fixedly installed on the upper position of the rack assembly (4), and the other camera assembly (3) is installed on the axial drive assembly (6) and moves up and down under the drive of the motor of the axial drive assembly, the two high radiation resistant cameras are adjusted up and down, and the two objects under inspection can be simultaneously video inspected by moving the camera assemblies (3) relative to each other and adjusting the pitch angle of the high radiation resistant cameras. A method for checking a nuclear power unit reactor in-vessel component outer surface video inspection device, comprising the following steps: Step one: the inspection device is subjected to underwater air tightness test, the whole inspection device is installed on the inspection base, and the mechanical function of the inspection device is debugged; Step two: use the ring crane in the reactor building to position and install the inspection base into the reactor shaft inspection equipment well, and use the pulley to transport the inspection device to the special track in the equipment inspection well; Step three: use the steel stamp mark of the in-vessel component outer surface circumferential weld to position the fixed camera in depth and circumference; Step four: position the movable camera according to the relative position of the in-vessel component outer surface circumferential weld, and complete the initial positioning of the double camera combination; Step five: under the action of the reactor building ring crane, the in-vessel component rotates in circumference, video acquisition is implemented in the process of rotation, and the in-vessel component rotates 360°; Step six: after completing a group of video acquisition, control the inspection device to move to the next group of circumferential weld along the guide rail under the mechanical external force of the inspection base, adjust the position of the movable camera through the circumferential drive assembly, and perform the next group of video inspection until the inspection is completed.

2. A reactor in-core component outer surface video inspection apparatus as claimed in claim 1, characterized in that: The material of the rack assembly (4) is stainless steel.

3. A reactor in-core component outer surface video inspection apparatus as claimed in claim 2, characterized in that: The axial driving assembly (6) comprises a common linear motion pair, a screw nut pair, a slider and a motor; the common linear motion pair is provided with a screw nut pair; the slider is one in number, and a threaded through hole is formed in the center of the slider; the slider is sleeved on the screw nut pair through the threaded through hole, and the length of the slider is 200 mm; the axial driving assembly (6) is fixed to the rack assembly (4) through screws and nuts.

4. A reactor in-core component outer surface video inspection apparatus as claimed in claim 3, characterized by: A camera mounting hole seat is further formed in the slider, and one of the camera assemblies (3) is threadedly fixed on the slider of the axial driving assembly (6).

5. A reactor in-core component outer surface video inspection apparatus as claimed in claim 1, characterized by: The number of the distribution box assemblies (1) is two, the distribution box assemblies (1) are arranged at the upper top end of the rack assembly (4) through threaded connection, and are used for mounting a driving motor and arranging electric wires; the distribution box assemblies (1) are sealed by dynamic / static sealing grease.

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