A nuclear reactor fuel assembly fuel single rod eddy current and video integrated inspection device

Abstract

This patent is applicable to the field of non-destructive testing of damaged fuel rods in nuclear reactor fuel assemblies, and specifically relates to an eddy current and video integrated testing device for a single fuel rod in a nuclear reactor fuel assembly. At present, there are devices in China that implement eddy current testing on single fuel rods, but they cannot implement video testing. It is necessary to first use a special video testing device to implement video testing on the single fuel rod, and then implement eddy current testing on it. The upper cover of the box body is a rectangular plate with two countersunk holes of the same size and structure in the middle, which are used to fix the fuel rod bell mouth and the calibration rod bell mouth; there are three countersunk holes around it, which are used to fix three support columns. The present invention is used to realize eddy current and video integrated testing of single fuel rods in nuclear reactors, reducing the number of testing equipment and testing operation steps.

Description

Technical Field

[0001] This patent is applicable to the field of non-destructive testing of damaged fuel rods in nuclear reactor fuel assemblies, and specifically relates to an eddy current and video integrated testing device for a single fuel rod in a nuclear reactor fuel assembly. Background Art

[0002] Fuel assemblies are core components of nuclear power plants and nuclear power plant reactors. Their main functions are to release heat and serve as the first barrier of the three barriers of nuclear safety. The integrity of fuel assemblies and single rods is crucial to the safe operation of the reactor. Nuclear fuel assemblies are composed of hundreds of densely arranged single fuel rods. The cladding material of nuclear fuel single rods is generally zirconium alloy thin-walled tubes with a wall thickness of 0.38-0.70mm. The upper and lower end plugs have an annular weld 2-3mm from the end. The fuel cladding is used to protect the nuclear fuel from chemical corrosion and other mechanical damage of the coolant and prevent fission products from entering the cooling circuit.

[0003] There are currently two methods for testing the integrity of fuel assemblies: the leak sip system and the ultrasonic inspection system. Both the leak sip system and the ultrasonic inspection system can determine whether the fuel assembly is leaking. The ultrasonic inspection system can also determine which fuel rod in the fuel assembly is leaking, but it cannot determine the size of the defect in the leaking fuel rod and the axial position of the defect.

[0004] At present, there are devices in China that can perform eddy current inspection on single fuel rods, but they cannot perform video inspection. It is necessary to first use a special video inspection device to perform video inspection on the single fuel rod, and then perform eddy current inspection on it. As a result, both video and eddy current inspection equipment need to be installed on the single fuel rod at the same time, and the high-risk fuel operation steps are greatly increased, increasing operational risks. Summary of the invention

[0005] 1. Purpose:

[0006] The purpose of this patent is to design a nuclear reactor fuel assembly fuel single rod eddy current, video integrated inspection device to achieve eddy current, video integrated inspection of nuclear reactor fuel single rod, reduce the number of inspection equipment and inspection operation steps.

[0007] 2. Technical solution:

[0008] A nuclear reactor fuel assembly fuel single rod eddy current and video integrated inspection device comprises a box frame, a fuel rod inspection sleeve assembly, a calibration rod sleeve assembly, an emergency release bolt, a camera assembly, and an eddy current inspection probe assembly; the box frame is a cube, fixedly installed on a lifting elevator of a spent fuel pool, and is the installation base of the entire single rod eddy current and video integrated inspection device; the fuel rod inspection sleeve assembly and the calibration rod sleeve assembly are fixed to the lower end of the box frame by emergency release bolts; the camera assembly is fixed to the side of the box frame; and the eddy current inspection probe assembly is fixed inside the box frame.

[0009] The box frame is composed of a box upper cover, a fuel rod bell mouth, a calibration rod bell mouth, a bolt alignment sleeve, a supporting column, a box lower bracket, a supporting adjustment pad, an eddy current probe block, a cable pressure block, and a probe locking block; the box upper cover is a rectangular plate with two countersunk holes of the same size and structure in the middle to fix the fuel rod bell mouth and the calibration rod bell mouth; three countersunk holes are opened around the periphery to fix three supporting columns.

[0010] The fuel rod bell mouth is matched with the hole drilled in the upper cover plate of the box body through the outer circle of the lower end of the flange, and is connected to the upper cover plate of the box body through bolts; the upper part of the fuel rod bell mouth is in the shape of a bell mouth, and the lower part is a cylinder, and an observation port is opened near the bottom of the cylinder.

[0011] The calibration rod bell mouth is similar in structure to the fuel rod bell mouth, and is matched with the hole hinged on the upper cover plate of the box body through the outer circle of the lower end of the flange, and is connected to the upper cover plate of the box body through bolts; the upper part of the calibration rod bell mouth is in the shape of a bell mouth, and the lower part is a cylinder.

[0012] The bolt alignment sleeve is a hollow cylindrical structure, which is connected to the lower bracket of the box body by welding; the upper end of the central opening of the bolt alignment sleeve has a large chamfer.

[0013] The support column is used to connect the upper cover plate and the lower support of the box body into one body, and is a cylindrical structure; threaded holes are opened at the upper and lower ends to realize threaded connection with the upper cover plate and the lower support of the box body.

[0014] The lower support of the box body is a support formed by welding three plates.

[0015] The box bottom plate, box side plates and box rib plates are connected as a whole through welding.

[0016] The upper cover plate of the box body and the lower bracket of the box body are provided with reamed holes; there is an outer circle at the two end surfaces of the upper cover plate of the box body and the lower bracket of the box body, which is matched with the reamed holes to form a hole axis.

[0017] 3. Effect

[0018] This patent uses a cylinder-driven locking mechanism to achieve coaxial positioning of the ultrasonic and video inspection device of the guide hole of the control rod guide tube relative to the inspected guide tube, and realizes the up and down movement of the ultrasonic and video inspection probe on the guide plates of each layer of the guide tube through the axial movement of the probe guide rod assembly, and realizes full coverage of the inspection of 24 guide holes through the circumferential movement of the probe guide rod assembly;

[0019] The clamping double-acting cylinder is used to drive the upward and downward movement of the positioning locking cylinder, which causes the inner surface of the positioning locking cylinder to press the outer surfaces of the four positioning locking bevel blocks synchronously and with the same force, so as to realize the positioning of the inspection device and the probe guide rod assembly relative to the axis of the inspected guide cylinder, ensure that the probe guide rod assembly can pass through the center hole between the guide plates of each layer, and that the center of each inspection probe coincides with the guide clamp hole, thereby improving the inspection accuracy;

[0020] The probe guide rod assembly and the inspection probe are rotated relative to the inspected guide cylinder by kneading the rotating pinion with the gear of the circumferentially rotating large gear ring fixed on the inspection positioning and clamping assembly;

[0021] The axial lifting and lowering of the probe guide rod assembly and the inspection probe relative to the inspected guide cylinder is achieved by meshing the lifting drive gear on the lifting drive assembly with the lifting drive rack on the probe guide rod assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Front view of the integrated device for eddy current and video inspection of a single fuel rod

[0023] Figure 2 Left view of the integrated device for eddy current and video inspection of a single fuel rod

[0024] Figure 3 Top view of the integrated device for eddy current and video inspection of a single fuel rod

[0025] Figure 4 Main view of the box frame structure

[0026] Figure 5 Box frame structure right view

[0027] Figure 6 Top view of the box frame structure

[0028] Figure 7 Bottom view of the box frame structure

[0029] Figure 8 Main view of the lower support structure of the box

[0030] Fig. 9 Left view of the lower support structure of the box

[0031] In the figure: 1. Box frame; 2. Fuel rod inspection sleeve assembly; 3. Calibration rod sleeve assembly; 4. Emergency release bolt; 5. Camera assembly; 6. Eddy current inspection probe assembly; 7. Box upper cover; 8. Fuel rod bell mouth; 9. Calibration rod bell mouth; 10. Bolt alignment sleeve; 11. Support column; 12. Box lower bracket; 13. Support adjustment pad; 14. Eddy current probe block; 15. Cable pressure block; 16. Probe locking block; 17. Box bottom plate. DETAILED DESCRIPTION

[0032] The fuel single rod eddy current and video integrated inspection device is used for eddy current and video integrated inspection of damaged fuel single rods, and is mainly composed of a box frame 1, a fuel rod inspection sleeve assembly 2, a calibration rod sleeve assembly 3, an emergency release bolt 4, a camera assembly 5, an eddy current inspection probe assembly 6, etc. Its structure is as follows Figure 1 shown.

[0033] The box frame 1 is the installation base of the entire eddy current and video integrated inspection device. The fuel rod inspection sleeve assembly 2, the calibration rod sleeve assembly 3, the emergency release bolt 4, the camera assembly 5 and the eddy current inspection probe assembly 6 are connected together through the box frame.

[0034] The box frame 1 is installed on the new fuel elevator of the spent fuel pool by two bolts and a pin, and rises and falls together with the new fuel elevator. The box frame consists of a box upper cover 7, a fuel rod bell mouth 8, a calibration rod bell mouth 9, a bolt alignment sleeve 10, a support column 11, a box lower bracket 12, a support adjustment pad 13, an eddy current probe stopper 14, a cable pressure block 15, a probe locking block 16, etc. Its structure is as follows Figure 2 shown.

[0035] The upper cover plate 7 of the box body is a rectangular plate with two countersunk holes of the same size and structure in the middle for installing the fuel rod bell mouth 8 and the calibration rod bell mouth 9, and three countersunk holes around it for installing three supporting columns 11.

[0036] The fuel rod bell mouth 8 is used to interface with the lower end of the fuel rod gripper to guide the fuel rod gripper and the inspected fuel rod. It cooperates with the reamed hole of the upper cover plate 7 of the box body through the outer circle of the lower end of the flange to ensure its position and verticality, and is connected to the upper cover plate 7 of the box body by bolts. The upper part of the fuel rod bell mouth 8 is a bell mouth shape for guiding the fuel rod gripper, and the lower part is a cylinder for guiding the inspected fuel rod and containing protection during inspection. An observation port is opened near the bottom of the cylinder for video inspection of the appearance of the inspected fuel rod during video inspection.

[0037] The calibration rod bell mouth 9 is similar in structure to the fuel rod bell mouth 8, and is used to interface with the lower end of the fuel rod gripper, and to guide the fuel rod gripper and the eddy current and video calibration rods during inspection. It also cooperates with the reamed hole of the upper cover plate 7 of the box body through the outer circle of the lower end of the flange to ensure its position and verticality, and is connected to the upper cover plate 7 of the box body by bolts. The upper part of the calibration rod bell mouth 9 is a bell mouth shape for guiding the fuel rod gripper, and the lower part is a cylinder for guiding the calibration rod and containing protection during inspection.

[0038] The bolt alignment sleeve 10 is a hollow cylindrical structure, which is connected to the lower bracket 12 of the box body by welding. The central opening of the bolt alignment sleeve 10 is used for the bolt through hole and bolt pressure surface when the fuel single rod eddy current and video integrated inspection device is installed on the new fuel elevator by bolts. The upper end of the central opening has a large chamfer to facilitate the guidance of the long rod tool for tightening the bolt during remote installation.

[0039] The support column 11 is used to connect the upper cover plate 7 and the lower support plate 12 of the box body as a whole. It is a cylindrical structure with threaded holes at the upper and lower ends to achieve threaded connection with the upper cover plate 7 and the lower support plate 12 of the box body. In addition, there is an outer circle at the two end surfaces to form a hole axis match with the hinged holes on the upper cover plate 7 and the lower support plate 12 of the box body, thereby ensuring that the relative position of the upper cover plate 7 and the lower support plate 12 of the box body is accurate.

[0040] The lower support 12 of the box body is a support formed by welding three plates, and is used for the bolt alignment sleeve 10, the support adjustment pad 13, the eddy current probe block 14, the cable pressure block 15, and the probe locking block 16. The box body bottom plate 17, the box body side plate and the box body rib plate have a structure as shown in FIG. Figure 3 The box bottom plate 17, the box side plates and the box ribs are connected as one by welding.

[0041] When inspecting the guide holes of the control rod guide tubes, firstly, the ultrasonic and video inspection device is sent to the top of the first guide tube to be inspected through the ring hoist inside the nuclear power plant, and then slowly lowered until the top of the inspected guide tube is inserted into the inner hole of the upper positioning tube. Then, the positioning and locking tube moves downward under the action of the clamping cylinder, and the inner surface of the positioning and locking bevel block is pressed against the outer wall of the inspected guide tube, so as to keep the inspection device and the probe guide rod assembly in the center of the inspected guide tube. Then, the lifting drive assembly drives the probe guide rod assembly and each inspection probe to descend to the top of each layer of guide plates under the action of the driving motor, and the rotating pinion drives each inspection probe on the probe guide rod assembly to rotate to the coaxial position of the inspected guide hole under the action of the driving motor, and then the ultrasonic and video inspection begins.

[0042] The status of the probe positioning device after being installed on the heat exchanger tube sheet flange is as follows Figure 4 shown.

Claims

1. A nuclear reactor fuel assembly fuel single rod eddy current and video integrated inspection device, characterized in that: The invention comprises a box frame (1), a fuel rod inspection sleeve assembly (2), a calibration rod sleeve assembly (3), an emergency release bolt (4), a camera assembly (5), and an eddy current inspection probe assembly (6); the box frame (1) is a cube, fixedly mounted on a lifting elevator of a spent fuel pool, and is a mounting base of the entire single-rod eddy current and video integrated inspection device; the fuel rod inspection sleeve assembly (2) and the calibration rod sleeve assembly (3) are fixed to the lower end of the box frame (1) by means of the emergency release bolt (4); the camera assembly (5) is fixed to the side of the box frame (1); and the eddy current inspection probe assembly (6) is fixed inside the box frame (1); The box frame (1) comprises: a box upper cover plate (7), a fuel rod bell mouth (8), a calibration rod bell mouth (9), a bolt alignment sleeve (10), a support column (11), a box lower bracket (12), a support adjustment pad (13), an eddy current probe stopper (14), a cable pressure block (15), and a probe locking block (16); the box upper cover plate (7) is a rectangular plate, and has two countersunk holes of the same size and structure in the middle, for fixing the fuel rod bell mouth (8) and the calibration rod bell mouth (9); and has three countersunk holes on the periphery, for fixing three support columns (11); The fuel rod bell mouth (8) is matched with a hole drilled in the upper cover plate (7) of the box body through the outer circle of the lower end of the flange, and is connected to the upper cover plate (7) of the box body through bolts; the upper part of the fuel rod bell mouth (8) is in the shape of a bell mouth, and the lower part is a cylinder, and an observation port is opened near the bottom of the cylinder; The calibration rod bell mouth (9) is similar in structure to the fuel rod bell mouth (8), and is matched with a hole drilled in the upper cover plate (7) of the box body through the outer circle of the lower end of the flange, and is connected to the upper cover plate (7) of the box body through bolts; the upper part of the calibration rod bell mouth (9) is in the shape of a bell mouth, and the lower part is a cylinder; The bolt alignment sleeve (10) is a hollow cylindrical structure, connected to the lower bracket (12) of the box body by welding; the upper end of the central opening of the bolt alignment sleeve (10) has a large chamfer; The support column (11) is used to connect the upper cover plate (7) and the lower support plate (12) of the box body into one body, and is a cylindrical structure; threaded holes are provided at the upper and lower ends to achieve threaded connection with the upper cover plate (7) and the lower support plate (12) of the box body.

2. The nuclear reactor fuel assembly fuel single rod eddy current and video integrated inspection device according to claim 1, characterized in that: The box lower bracket (12) is a bracket formed by welding three plates.

3. The nuclear reactor fuel assembly fuel single rod eddy current and video integrated inspection device according to claim 1, characterized in that: The upper cover plate (7) and the lower support (12) of the box body are provided with a reamed hole; and there is an outer circle at both end surfaces of the upper cover plate (7) and the lower support (12) of the box body, which cooperates with the reamed hole to form a hole axis.

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