A nuclear power plant fuel assembly centering aid

Abstract

The present application relates to the technical field of centering auxiliary device, and discloses a nuclear power plant fuel assembly centering auxiliary device, which comprises a storage part, a supporting part and a guide part, the supporting part is arranged at one end of the storage part and can be connected with a tube seat on the fuel assembly, the guide part comprises two guide combs, each of the two guide combs is provided with a plurality of guide grooves, the two guide combs are stacked in a 90° staggered mode at the end of the storage part away from the supporting part, the staggered guide grooves of the two guide combs form a plurality of guide holes, and the guide holes can guide the rod bundles; the guide holes constrain each rod bundle by overlapping the two groups of guide grooves, so that deviation of the rod bundle during falling is avoided, the height of the storage part is raised by the guide part, the staff can support the rod bundle by inserting into the fuel basket, so that the staff can assemble outside the refueling pool, the working time of the staff in the high radiation area is shortened, and the radiation dose of the staff is reduced.

Description

Technical Field

[0001] This invention relates to the field of centering auxiliary device technology, and more specifically to a centering auxiliary device for fuel assemblies in a nuclear power plant. Background Technology

[0002] Before the initial fuel loading, pressurized water reactor nuclear power plants need to receive neutron sources. The neutron source has a high activity. The neutron source of a certain CAP series power plant has a radioactive dose that is 5 times the activity of the neutron source in the project it is based on, and it belongs to Class IV radioactive source according to the activity.

[0003] Because the neutron source and the combustible poison assembly arrived at the factory in batches, the combustible poison assembly needed to be removed during installation. After the neutron source assembly was installed, the combustible poison assembly was then docked with the neutron source assembly to form the complete primary neutron source assembly. During the installation of the primary neutron source assembly, docking the combustible poison assembly with the neutron source assembly was one of the most challenging steps. The combustible poison assembly is 4339.2 mm long and 9.677 mm in diameter, and its 23 rod bundles needed to be accurately inserted into a guide tube with a diameter of only 11.17 mm. The large number of rod bundles and their poor rigidity made alignment extremely difficult.

[0004] During the movement of the neutron source, the maximum neutron dose is 4610 microsieverts, and the neutron dose for personnel at the assembly insertion position is 135.8 microsieverts. This high radiation dose is detrimental to occupational health protection. Due to the 15-meter drop at the edge and the fact that the upper fuel assembly mount is located inside the fuel basket of the new fuel elevator, the alignment process requires at least two people and 20 minutes. Under such high radiation conditions, personnel may experience panic, hindering work quality. Furthermore, the risks are multiplied by the multiple environmental factors. Therefore, we propose a nuclear power plant fuel assembly alignment auxiliary device to address these issues. Summary of the Invention

[0005] The present invention aims to provide an auxiliary device for aligning fuel assemblies in nuclear power plants, in order to solve the problem that personnel may experience panic under high radiation doses, which is detrimental to improving work quality, and that the risk of operation is multiplied under the influence of multiple environmental factors.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a nuclear power plant fuel assembly alignment auxiliary device, comprising a storage component, a support component, and a guide component. The support component is located at one end of the storage component and can be connected to the upper tube seat of the fuel assembly. The guide component includes two guide combs, each of which has several guide grooves. The two guide combs are stacked at 90° staggered to the end of the storage component away from the support component, and the staggered guide grooves of the two guide combs form several guide holes, which can guide the fuel assembly.

[0007] Preferably, as an improvement, the guide grooves of the guide comb are parallel to each other.

[0008] Preferably, as an improvement, the guide comb sidewall is provided with a handle, and the handle has a through hole for preventing falls.

[0009] Preferably, as an improvement, the storage component includes two storage racks, both of which are configured as "U"-shaped and are connected to each other at both ends. Each end of the two storage racks is provided with an assembly slot, and an assembly pin is provided between two adjacent assembly slots.

[0010] Preferably, as an improvement, one end of the storage rack is provided with several blocks, and the side wall of the guide comb can abut against each block.

[0011] Preferably, as an improvement, both storage racks are perforated.

[0012] Preferably, as an improvement, the guide includes a positioning shaft, a positioning pin, and two guide posts. The two storage racks each have two threaded holes. One end of the positioning shaft, the positioning pin, and the two guide posts are threadedly connected to the corresponding threaded holes. The other end of the positioning pin and the two guide posts can be engaged with the positioning hole of the fuel assembly upper tube seat, and the other end of the positioning shaft can be in contact with the upper end of the fuel assembly upper tube seat.

[0013] The beneficial effects of this scheme are: (1) By staggering two guide combs, the overlapping part of the two guide slots forms a guide hole, which constrains each rod bundle and avoids deviation during the falling of the rod bundle; (2) By setting guides to raise the height of the storage components, workers are prevented from reaching into the fuel basket to support the rod bundles, allowing workers to assemble the components outside the refueling pool, thus shortening the working time of workers in high-radiation areas and reducing the radiation dose to workers. (3) Since a special funnel and fixing cable are required when the neutron source is installed inside the fuel assembly, the guide is set as two detachable guide combs, which can avoid the special funnel and fixing cable, and make it easier for the staff to quickly constrain the rod bundle. (4) By opening perforations in the storage rack, the weight of the storage rack is reduced, thereby achieving lightweighting of the auxiliary device; (5) The stop block can fix the guide comb and prevent the guide comb from shaking at the top of the storage rack during the descent of the bar bundle, which would cause the guide comb to fall off the installation position. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the guide comb structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of two stacked guide combs according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of two storage racks according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the assembly pin, positioning shaft, positioning pin, and guide post according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the storage rack and stop block according to an embodiment of the present invention. Detailed Implementation

[0015] The following detailed description illustrates the specific implementation method: The reference numerals in the accompanying drawings include: guide comb 1, guide groove 2, handle 3, storage rack 4, assembly groove 5, assembly hole 6, assembly pin 7, welding groove 8, stop block 9, hollow hole 10, threaded hole 11, positioning shaft 12, positioning pin 13, and guide post 14.

[0016] Example The basic implementation examples are as follows: Figures 1-5 As shown, a nuclear power plant fuel assembly alignment auxiliary device includes a storage component, a support component, and a guide component, such as... Figure 1 The guide component shown includes two guide combs 1. In this embodiment, the guide combs 1 are made of aluminum alloy. Each guide comb 1 has several guide grooves 2, and these grooves 2 are parallel to each other. In this embodiment, there are seven guide grooves 2. A handle 3 is integrally formed at the upper end of the guide comb 1. A fall arrestor hole is formed through the handle 3. Workers connect a fall arrestor rope to the fall arrestor hole to prevent the guide comb 1 from falling and colliding with other workpieces due to accidental drop. Figure 2 The two guide combs 1 shown are stacked in a 90° staggered manner, and the overlapping area of ​​the two staggered guide grooves 2 forms several guide holes, which can guide the rod bundle.

[0017] like Figure 3 The storage unit shown includes two storage racks 4. In this embodiment, the storage racks 4 are made of stainless steel. Both storage racks 4 are U-shaped and are connected to each other at both ends. Each end of the two storage racks 4 has an assembly groove 5. The inner wall of the upper assembly groove 5 has a through-hole 6, and the inner wall of the lower assembly groove 5 has two through-holes 6. An assembly pin 7 is slidably installed between the two oppositely arranged assembly holes 6. The assembly pin 7 is as follows: Figure 4 As shown, Figure 3 The two storage racks 4 shown have four welding grooves 8 on their outer walls. Specifically, one welding groove 8 is provided on the upper and lower outer walls of each storage rack 4, and two welding grooves 8 are provided at the ends of the two storage racks 4 that are far apart from each other. Figure 5The welding groove 8 shown is fixedly installed with blocks 9 by welding, and the side wall of the guide comb 1 can abut against each block 9, thereby preventing the guide comb 1 from shaking or shifting at the upper end of the storage rack 4. The distance between the upper end of the block 9 and the upper end of the storage rack 4 is greater than the stacked height of two guide combs 1. Figure 3 Both storage racks 4 shown have through holes 10.

[0018] like Figure 3 The two storage racks 4 shown each have two threaded holes 11 through them, as shown. Figure 4 The guide components shown include a positioning shaft 12, a positioning pin 13, and two guide posts 14. In this embodiment, the positioning shaft 12, the positioning pin 13, and the two guide posts 14 are all made of polytetrafluoroethylene. The left ends of the positioning shaft 12, the positioning pin 13, and the two guide posts 14 are all provided with external threads. The positioning shaft 12, the positioning pin 13, and the two guide posts 14 are threadedly connected to the corresponding threaded holes 11 through the external threads, and the two guide posts 14 are arranged diagonally. The right ends of the positioning pin 13 and the two guide posts 14 are integrally formed with positioning heads. The positioning pin 13 and the two guide posts 14 are inserted into the corresponding positioning holes of the fuel assembly upper tube seat through the positioning heads. The right end of the positioning shaft 12 is set as an abutment plane, and the positioning shaft 12 fits against the upper end of the fuel assembly upper tube seat through the abutment plane.

[0019] The specific implementation process is as follows: When docking the combustible poison assembly with the neutron source assembly, the operator first threads the positioning shaft 12, positioning pin 13, and two guide posts 14 to the two storage racks 4. Then, the two storage racks 4 are docked using the assembly pin 7 and assembly hole 6. Next, the docked storage racks 4 are placed into the fuel basket, and the positioning pin 13 and two guide posts 14 are docked with the positioning holes on the upper tube seat of the fuel assembly, ensuring that the storage racks 4 are not loose. Then, the operator docks one of the guide combs 1 with the combustible poison assembly, inserting each rod bundle into the guide groove 2 by moving the guide comb 1. Then, the other guide comb 1 is rotated 90° to the first guide comb 1, and the rod bundles are inserted into the guide groove 2 in a 90° staggered stacked state. At this point, the non-overlapping parts of the guide grooves 2 of the two guide combs 1 form guide holes, through which the rod bundles are inserted. The rod bundle is constrained to prevent deviation during descent, and each guide hole corresponds to a guide tube. Then, the operator lowers the combustible poison assembly synchronously with the handle 3 until the two guide combs 1 are placed on the upper end of the storage rack 4. The two guide combs 1 are then restricted by the stop block 9. The combustible poison rod bundle is then slowly lowered, sliding down along the constrained path of the guide holes. The rod bundle is aligned with the inlet of the fuel assembly guide tube by the guide holes, and each combustible poison rod bundle is smoothly inserted into the guide tube, completing the docking of the combustible poison assembly and the neutron source assembly. After confirming that the rod bundle assembly is in place, the operator lifts the two guide combs 1 and separates them from the rod bundle. Then, the two storage racks 4 are lifted, and the assembly pin 7 between the two storage racks 4 is removed, separating the two storage racks 4 from each other, thus completing the disassembly of the auxiliary device.

[0020] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A nuclear power plant fuel assembly alignment auxiliary device, characterized in that: It includes a storage component, a support component, and a guide component. The support component is located at one end of the storage component and can be connected to the upper tube seat of the fuel assembly. The guide component includes two guide combs, each of which has several guide grooves. The two guide combs are stacked at 90° staggered to the end of the storage component away from the support component, and the staggered guide grooves of the two guide combs form several guide holes, which can guide the rod bundle.

2. The nuclear power plant fuel assembly alignment auxiliary device according to claim 1, characterized in that: The guide comb has several guide grooves that are parallel to each other.

3. The nuclear power plant fuel assembly alignment auxiliary device according to claim 2, characterized in that: The guide comb has a handle on its side wall, and the handle has a drop prevention hole.

4. The nuclear power plant fuel assembly alignment auxiliary device according to claim 1, characterized in that: The storage unit includes two storage racks, both of which are "U" shaped and connected to each other at both ends. Each end of the two storage racks has an assembly slot, and an assembly pin is provided between two adjacent assembly slots.

5. The nuclear power plant fuel assembly alignment auxiliary device according to claim 4, characterized in that: One end of the storage rack is equipped with several blocks, and the side wall of the guide comb can abut against each block.

6. The nuclear power plant fuel assembly alignment auxiliary device according to claim 5, characterized in that: Both storage racks have through-holes.

7. The nuclear power plant fuel assembly alignment auxiliary device according to claim 1, characterized in that: The guide includes a positioning shaft, a positioning pin, and two guide posts. The two storage racks each have two threaded holes. One end of the positioning shaft, the positioning pin, and the two guide posts are threadedly connected to the corresponding threaded holes. The other end of the positioning pin and the two guide posts can be connected to the positioning hole of the fuel assembly upper tube seat. The other end of the positioning shaft can be in contact with the upper end of the fuel assembly upper tube seat.

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