A top cover centering device suitable for a nuclear power plant

Abstract

The present application belongs to the technical field of operation, and particularly relates to a top cover centering device suitable for nuclear power plants. The device comprises successively connected lifting lugs, an upper cover, a cylinder and a cone. Before starting the lifting work, a hoisting personnel connects the centering device through a lifting rope. After the connection is completed, the centering device is automatically centered by being respectively placed into bolt holes of corresponding guide columns of the top cover, the top cover is lowered, and when the cone tip of the centering device is lowered to the top end of the guide column, the hoisting personnel clearly grasps the position difference and deviation between the top cover and the guide column due to the centering device as an extension part of the guide column and the staggered structure design. After fine adjustment by a commander, the centering device and the guide column top end lifting lug hole center are connected, and under the assistance of the centering device, the guide column is guided into the corresponding bolt hole of the top cover. The present application can eliminate human traps, ensure safe production on site, and improve the efficiency of lifting work on site.

Description

Technical Field

[0001] This invention belongs to the field of reactor operation technology, specifically relating to a top cover alignment device suitable for nuclear power plants. Background Technology

[0002] The reactor pressure vessel top cover is a critical piece of equipment in a nuclear power plant. Due to its large weight and size, and its location above the reactor core, the installation is challenging and carries significant risks. The installation of the pressure vessel top cover is a crucial part of the lifting work during refueling and major overhauls in nuclear power plants, and is situated within the critical path of such overhauls.

[0003] The most important step in the hoisting of the top cover is aligning the bolt holes of the top cover with the three guide columns. Due to the heavy load, high dosage and large size of the top cover equipment, the alignment is only fine-tuned by manual traction during the hoisting process. There is a human-caused trap of obstructed vision during the descent alignment process. During the descent, it is very likely that the equipment sealing surface will be scratched due to improper alignment, resulting in irreversible consequences. Summary of the Invention

[0004] The purpose of this invention is to provide a top cover alignment device suitable for nuclear power plants to eliminate human-caused traps, ensure safe production on site, and improve the efficiency of on-site hoisting work.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A top cover alignment device suitable for nuclear power plants includes a lifting lug, a top cover, a cylinder, and a cone connected in sequence.

[0007] The cylinder, top cover, and cone body adopt a hollow structure.

[0008] The lugs are made of 304 stainless steel.

[0009] The cylinder body is made of aluminum alloy.

[0010] The top cover and cone are made of nylon.

[0011] The cylinder is connected to the top cover via a lifting lug screw and secured with a nut. The cylinder is then screwed to the top cover and cone via its own thread.

[0012] Before the lifting operation begins, the hoisting personnel connect the centering device using hoisting ropes. After connection, the centering device is automatically aligned by inserting it into the bolt holes of the corresponding guide columns on the top cover. The top cover is then lowered. When the cone-shaped tip of the centering device reaches the top of the guide column, the hoisting personnel can clearly grasp the positional difference and deviation between the top cover and the guide column due to the centering device acting as an extension of the guide column and the staggered structural design. After fine-tuning by the commanding personnel, the centering device is aligned with the center of the lifting lug hole at the top of the guide column. With the assistance of the centering device, the guide column enters the corresponding bolt hole on the top cover. As the top cover descends, the centering device slowly exits the bolt hole. After the guide column is fully inserted into the bolt hole, the personnel pull out the hoisting ropes that were previously connected to the centering device, completing the top cover hoisting operation.

[0013] Before assembling the device, the operator must ensure that the parts are clean. During the assembly process, sealant is applied to the mating surfaces of the threaded joints. After the operator completes the assembly, a hoisting rope is used to pass through the lifting lugs on the top cover for fixation. The operator then loops the hoisting rope around the top cover lifting device and controls the movement of the centering device through the hoisting rope. The centering device is then inserted into the bolt hole of the top cover guide column and passes through the bolt hole. The top cover of the centering device is hung on the upper part of the bolt hole. Due to the cone-shaped structure of the centering device, the centering device falls naturally and automatically aligns with the lifting lug hole at the top of the guide column.

[0014] The beneficial effects achieved by this invention are as follows:

[0015] This invention features a simple structure, convenient and quick installation, robust construction, and ease of on-site operation. It allows for rapid docking with the guide column and alignment of the top cover, facilitating on-site top cover hoisting operations and significantly improving work efficiency. From a safety perspective, the extended length of the guide column eliminates blind spots for hoisting personnel, enhancing the inherent safety of the hoisting work. Attached Figure Description

[0016] Figure 1 A cross-sectional view of a top cover alignment device suitable for nuclear power plants;

[0017] Figure 2 This is a cross-sectional view of the upper cover component;

[0018] Figure 3 This is a cross-sectional view of the cylindrical component;

[0019] Figure 4 This is a cross-sectional view of the vertebral body component;

[0020] In the picture: 1. Hanging lug 2. Top cover 3. Cylinder body 4. Cone body. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0022] Considering the characteristics of the on-site work and the human factors that may cause problems, as well as the limited field of vision of personnel during the alignment process, and taking into account the structure of the three guide columns on site, a top cover alignment device that can be fitted into the guide columns was designed by utilizing the automatic splicing characteristic of the staggered structure after it falls. The top cover alignment device is made of a variety of materials, including nylon, aluminum alloy, and stainless steel.

[0023] Before the lifting operation begins, the hoisting personnel connect the alignment device using hoisting ropes. After connection, the alignment device is automatically aligned by inserting it into the bolt holes of the corresponding guide columns on the top cover. As the top cover is lowered, when the tip of the alignment device reaches the top of the guide column, the staggered structural design of the alignment device, which acts as an extension of the guide column, allows the hoisting personnel to clearly grasp the positional difference and deviation between the top cover and the guide column. After fine-tuning by the commanding personnel, the alignment device easily aligns with the center of the lifting lug hole at the top of the guide column. With the assistance of the alignment device, the guide column easily enters the corresponding bolt hole on the top cover, avoiding the risk of the top end face of the guide column scraping against the bottom flange face of the top cover and reducing the adjustment time of the top cover above the reactor core during the hoisting process. As the top cover descends, the alignment device slowly exits the bolt hole. After the guide column is fully inserted into the bolt hole, the personnel use the hoisting ropes previously connected to the alignment device to pull it out, safely and smoothly completing the top cover hoisting operation.

[0024] The key points and protected aspects of this invention are: based on actual on-site work, the centering device is used to extend the guide column, thereby avoiding traps caused by worker errors; the on-site guide column structure is utilized, combined with the automatic splicing characteristics of the staggered structure, to achieve rapid splicing of the centering device and the guide column; it is made of nylon material, and the cylinder uses a hollow design, which greatly reduces the weight of the centering device and the risk of metal friction, ensuring on-site work safety.

[0025] pass Figure 1 The overall design of the top cover alignment device is visible, and the connection relationships between its components are also apparent. The device connects to the top cover component via lifting lugs and bolts, and is then secured with nuts. The cylinder is connected to the top cover and cone components via its own threads, thus completing the assembly of the top cover alignment device. To ensure the overall structural integrity and reliability of the device, and to mitigate the risks of collision and friction during hoisting, while also reducing the overall weight, different materials are used for each component. Considering that the main load-bearing components are the lifting lugs and the cylinder, the lifting lugs and cylinder are made of 304 stainless steel and aluminum alloy respectively, while the top cover and cone are made of nylon. Structurally, to reduce the weight of the device, the cylinder, top cover, and cone adopt a hollow structure, resulting in an overall weight of only 11.5 kg, thus ensuring greater convenience for personnel during use.

[0026] Before assembling the device, operators must ensure the parts are clean. During assembly, sealant will be applied to the mating surfaces of threaded joints to prevent oil and other foreign matter from falling into the components. After assembly, operators will secure the device by passing a lifting rope through the lifting lugs on the top cover. The operator will then loop the rope around the top cover's lifting mechanism and control the movement of the centering device via the rope. The centering device will be inserted into the bolt holes of the top cover's guide column, and the top cover plate of the centering device will hang above the bolt holes. Due to the conical structure of the centering device, it will naturally fall and automatically align with the lifting lug holes at the top of the guide column, ultimately extending the guide column, eliminating human error, and improving work efficiency and safety.

[0027] Workers use a jacking crane to lift the pressure vessel top cover. With the assistance of the centering device, workers can pre-align the top cover with the guide column under conditions of sufficient visibility. This allows the guide column to easily enter the corresponding bolt holes on the top cover, avoiding the risk of the top end face of the guide column scraping against the bottom flange face of the top cover. This also reduces the adjustment time of the top cover above the reactor core during the lifting process. As the top cover descends, the centering device slowly exits the bolt holes. After the guide column is fully inserted into the bolt holes, the workers use the lifting rope previously connected to the centering device to pull it out, safely and smoothly completing the top cover lifting operation.

[0028] This invention provides a special tool for centering a pressure vessel top cover by extending the center with the aid of guide columns during the lifting process. Combining the characteristics of the on-site working environment and the potential human error pitfalls in on-site work, a special tool for centering a top cover in nuclear power plants has been designed. This tool is simple to manufacture and process, convenient and reliable to install and fix, and can eliminate the characteristics of blind spots on site. It not only improves on-site work efficiency, but also enhances the inherent safety of on-site production.

Claims

1. A top cover alignment device suitable for nuclear power plants, characterized in that: It includes the lifting lugs, the top cover, the cylinder, and the cone, which are connected in sequence.

2. The top cover alignment device for nuclear power plants according to claim 1, characterized in that: The cylinder, top cover, and cone body adopt a hollow structure.

3. The top cover alignment device for nuclear power plants according to claim 1, characterized in that: The lugs are made of 304 stainless steel.

4. The top cover alignment device for nuclear power plants according to claim 1, characterized in that: The cylinder body is made of aluminum alloy.

5. The top cover alignment device for nuclear power plants according to claim 1, characterized in that: The top cover and cone are made of nylon.

6. The top cover alignment device for nuclear power plants according to claim 1, characterized in that: The cylinder is connected to the top cover via a lifting lug screw and secured with a nut. The cylinder is then screwed to the top cover and cone via its own thread.

7. The top cover alignment device for nuclear power plants according to claim 1, characterized in that: Before the lifting operation begins, the hoisting personnel connect the centering device using hoisting ropes. After connection, the centering device is automatically aligned by inserting it into the bolt holes of the corresponding guide columns on the top cover. The top cover is then lowered. When the cone-shaped tip of the centering device reaches the top of the guide column, the hoisting personnel can clearly grasp the positional difference and deviation between the top cover and the guide column due to the centering device acting as an extension of the guide column and the staggered structural design. After fine-tuning by the commanding personnel, the centering device is aligned with the center of the lifting lug hole at the top of the guide column. With the assistance of the centering device, the guide column enters the corresponding bolt hole on the top cover. As the top cover descends, the centering device slowly exits the bolt hole. After the guide column is fully inserted into the bolt hole, the personnel pull out the hoisting ropes that were previously connected to the centering device, completing the top cover hoisting operation.

8. The top cover alignment device for nuclear power plants according to claim 1, characterized in that: Before assembling the device, the operator must ensure that the parts are clean. During the assembly process, sealant is applied to the mating surfaces of the threaded joints. After the operator completes the assembly, a hoisting rope is used to pass through the lifting lugs on the top cover for fixation. The operator then loops the hoisting rope around the top cover lifting device and controls the movement of the centering device through the hoisting rope. The centering device is then inserted into the bolt hole of the top cover guide column and passes through the bolt hole. The top cover of the centering device is hung on the upper part of the bolt hole. Due to the cone-shaped structure of the centering device, the centering device falls naturally and automatically aligns with the lifting lug hole at the top of the guide column.

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