Equal-gap precision assembling method for compactly-arranged fuel assemblies

Abstract

The invention provides a compactly-arranged fuel assembly equal-clearance precision assembling method which comprises the following steps: providing a plurality of fuel assemblies to be assembled, arranging leads of each fuel assembly and installing labels, uniformly binding the leads by using a binding belt, and transferring the leads to a vertical assembling platform, a left supporting plate of a reactor core supporting assembly is horizontally fixed on the vertical assembling platform; a special lifting tool is used for lifting the fuel assemblies in sequence, each fuel assembly is vertically moved to the position facing the corresponding connector position on the left supporting plate, then leads of the fuel assemblies penetrate into the corresponding hole positions of the connector positions, and finally the fuel assemblies and the left supporting plate are fixedly installed at the connector positions; after all the fuel assemblies are installed in place, a reactor core shroud of the reactor core supporting assembly and a left supporting plate are fixedly installed; a special guide device is used for guiding all the fuel assemblies, and a right supporting plate of the reactor core supporting assembly, all the fuel assemblies and the reactor core shroud are fixedly installed. The device is used for solving the problem of equal-gap installation of a plurality of fuel assemblies with power lines and sensor lines in a reactor core assembly.

Description

Technical Field

[0001] The present invention relates to the technical field of boilers and nuclear power pressure equipment, and in particular to a method for precisely assembling gaps between compactly arranged fuel assemblies. Background Art

[0002] The core assembly consists of a core support assembly and multiple fuel assemblies. Each fuel assembly has 36 electric heating rods with sensors (72 power lines) and 6 instrument measuring rods that need to be installed during the installation process. The fuel assemblies are installed at equal intervals, and the power lines and sensor lines of the fuel assemblies need to be led out of the core.

[0003] The fuel assemblies are installed in the core support assembly at equal intervals and without any structural support between the fuel assemblies. Traditional assembly methods make it difficult to control the accuracy of the equal-interval installation of the fuel assemblies. In addition, the average length of the power cord and sensor wire (hereinafter collectively referred to as the lead wire) of the fuel assembly is five meters, which causes operational inconvenience when leading out the left support plate of the core support assembly. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for precisely assembling the gaps between compactly arranged fuel assemblies, so as to solve the problem of installing the gaps between multiple fuel assemblies with power lines and sensor lines in a core assembly.

[0005] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A method for precise assembly of compactly arranged fuel assemblies with equal clearances, comprising:

[0007] Provide several fuel assemblies to be assembled, organize and label the leads of each fuel assembly, and tie them together with cable ties before transporting them to the vertical assembly platform where the left support plate of the core support assembly has been horizontally fixed.

[0008] Use a special lifting tool to lift each fuel assembly in sequence, move each fuel assembly vertically to the corresponding interface position on the left support plate, then insert the lead of the fuel assembly into the corresponding hole at the interface position, and finally fix the fuel assembly to the left support plate at the interface position;

[0009] After all fuel assemblies are installed in place, the core shroud of the core support assembly is fixedly installed to the left support plate;

[0010] A dedicated guide device is used to guide all fuel assemblies, and the right support plate of the core support assembly is fixedly installed with all fuel assemblies and the core shroud.

[0011] Optionally, the fuel assembly is hexagonal, and the left support plate and the right support plate are pre-arranged with hexagonal interfaces corresponding to each fuel assembly. The hexagonal interfaces are arranged in a honeycomb shape, and the gaps between adjacent hexagonal interfaces are the same.

[0012] Optionally, the fuel assemblies are installed from the inside out, and during the installation process, a special anti-dumping tool is used to prevent the installed fuel assemblies from tipping over.

[0013] Optionally, providing a plurality of fuel assemblies to be assembled includes:

[0014] The fuel assembly matrix is fixed using a coaxial variable diameter anti-deformation tool, positioned using a core rod, and the fuel assembly matrix is welded to the front and rear end cover plates.

[0015] Optionally, the dedicated lifting tool lifts the fuel assembly in a horizontal state to a certain height, and then converts the fuel assembly into a vertical state, with the end of the fuel assembly with the lead facing downward.

[0016] Optionally, the method further includes: after installing the right support plate, measuring the position of the tube hole for passing the heat pipe in the fuel assembly.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The present invention can complete the gap installation of multiple fuel assemblies of specific shapes (such as hexagons) without the use of supports; by lifting the fuel assembly to make it vertical, it can facilitate worker operation and on-site construction, and at the same time reserve operating space for the lead-out operation of sensor lines and power lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the description. Obviously, the drawings described below are one embodiment of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort:

[0020] Figure 1 is a structural schematic diagram of the core assembly;

[0021] Figure 2 It is a structural diagram of the left support plate;

[0022] Figure 3 Schematic diagram of the structure of the right support plate;

[0023] Figure 4 A flow chart of a method for precise assembly of compactly arranged fuel assemblies with equal clearances provided by one embodiment of the present invention;

[0024] Figure 5a and Figure 5b Schematic diagram of the vertical assembly platform

[0025] Figure 6 is a schematic diagram of a vertical assembly platform;

[0026] Figure 7 This is a photo of the fuel assembly installation site. DETAILED DESCRIPTION

[0027] The scheme proposed in the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the implementation methods of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the efficacy and purpose that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention.

[0028] like Figures 1 to 3 As shown, the core assembly includes a core support assembly and multiple fuel assemblies 200. The core support assembly includes a core shroud 110, a left support plate 120 and a right support plate 130. One end of the fuel assembly 200 with a lead is fixedly installed on the left support plate 120, and the lead is led out from the corresponding hole of the left support plate 120. The other end of the fuel assembly 200 is fixedly installed on the right support plate 130. The core shroud 110 is located between the left support plate 120 and the right support plate 130. It surrounds the fuel assembly 200, forms the boundary of the fuel assembly 200, and can also play a role in reducing neutron leakage.

[0029] Typically, the cross section of the fuel assembly 200 is a regular polygon and is arranged with equal spacing in the core, such as Figures 1 to 3As shown, the fuel assembly 200 is hexagonal. Hexagonal interfaces A are pre-installed on the left and right support plates 120, 130, corresponding to each fuel assembly 200. These interfaces A are arranged in a honeycomb pattern, with the spacing between adjacent interfaces A being uniform. The hexagonal interfaces A on the left support plate 120 are provided with multiple holes, through which different leads are threaded. In the prior art, the fuel assembly 200 is first fixed to the left support plate 120 in a horizontal position. However, this installation method cannot guarantee installation accuracy, and there is insufficient space for the leads to be routed through the holes in the left support plate 120.

[0030] The present invention provides a method for precise equal-gap assembly of compactly arranged fuel assemblies, which improves the equal-gap installation accuracy in a vertical state and also solves the problem of operating space for power lines and sensor lines passing through the left support plate.

[0031] like Figure 4 As shown, a method for precise assembly of compactly arranged fuel assemblies with equal clearances comprises the following steps:

[0032] S1: Provide several fuel assemblies to be assembled, organize the leads of each fuel assembly, install labels, and tie them together with cable ties before transporting them to a vertical assembly platform where the left support plate of the core support assembly has been horizontally fixed.

[0033] Specifically, the coaxial variable diameter anti-deformation fixture can be used to fix the base of the fuel assembly 200, and the core rod can be used for positioning to weld the base B of the fuel assembly 200 to the front and rear end covers. Figure 5a and Figure 5b As shown, the tooling a with adjusting bolts on both sides is used to adjust the alignment of the base B and the end cover and tighten the two workpieces to ensure their assembly dimensions and prevent welding deformation during welding. The two middle tooling b are designed in two halves to facilitate the flipping of the welding station during welding, and cooperate with the hole positioning tooling to ensure welding accuracy.

[0034] It is understood that the positioning and installation clearance between the front and rear end covers of the fuel assembly 200 and the left and right support plates 120 and 130 of the core support assembly is 0.125mm, with the minimum clearance even reaching 0.075mm. The front and rear end covers of the fuel assembly 200 are connected to the substrate via welded joints. Any deformation during the weld directly affects the subsequent positioning and installation of the fuel assembly 200 and the left and right support plates 120 and 130. Therefore, during the manufacturing stage of the fuel assembly 200, positioning is performed using a mandrel. To control welding deformation and achieve symmetrical welding, the assembly clearance between the mandrel and the product must be regularly checked during the welding process to reduce welding deformation between the front and rear end covers and the substrate.

[0035] Since each fuel assembly 200 has many and long leads, the leads need to be sorted to avoid damage during transportation, and each lead is labeled for identification. Finally, all the leads are tied with a cable tie before transportation.

[0036] S2. Use a special lifting tool to lift each fuel assembly in sequence, move each fuel assembly vertically to the corresponding interface position on the left support plate, then insert the lead of the fuel assembly into the corresponding hole at the interface position, and finally fix the fuel assembly to the left support plate at the interface position.

[0037] The vertical assembly platform is as follows Figure 6 As shown, the vertical assembly platform is first fixedly installed with a left support plate 120. After all fuel assemblies are transported to the core installation site, each fuel assembly is installed in an order from the inside out.

[0038] It should be noted that the fuel assembly 200 is first lifted to a certain height in a horizontal state using a special lifting tool, and then the fuel assembly 200 is converted to a vertical state, with the end of the fuel assembly 200 with the lead facing downward.

[0039] Specifically, a special lifting tool is used to lift the innermost fuel assembly 200. During assembly, the marked surface of the fuel assembly 200 faces the core support assembly to determine the angle for installation. During the installation process, each lead needs to be introduced into the corresponding hole. After the lead threading is completed, the fuel assembly 200 is installed in place and the installation gap is controlled. According to the same plan, the remaining fuel assemblies 200 are installed, and during the installation process, a special anti-dumping tool is used to prevent the installed fuel assemblies from tipping over. The assembly site of the fuel assembly 200 is as follows: Figure 7 shown.

[0040] It should be noted that there are many fuel assemblies 200 that need to be installed with equal spacing in the core assembly, for example, 30. After the installation plan is determined, it is also necessary to design a plan in advance for the protection and lifting of the 30 fuel assemblies 200 during the transportation process, and confirm the lifting range on site.

[0041] S3, after all fuel assemblies are installed in place, the core shroud of the core support assembly is fixedly installed to the left support plate.

[0042] S4, using a dedicated guide device to guide all fuel assemblies, and fixing the right support plate of the core support assembly to all fuel assemblies and the core shroud.

[0043] After all fuel assemblies 200 are installed, the core shroud 110 is installed. Once the core shroud 110 is in place, the ends of the end caps of the 30 fuel assemblies 200 are aligned on the same horizontal plane. A dedicated guide device is then used to install the right support plate 130, ensuring both the installation of the 30 fuel assemblies and the subsequent heat pipe threading requirements.

[0044] Furthermore, after installing the right support plate 130, the positions of the heat pipe holes in the fuel assembly 200 can also be measured. Precision equal-gap installation requires that all 30 hexagonal fuel assemblies 200 be installed with equal spacing. After installing the right support plate 130, since the heat pipe holes have already been machined in the fuel assembly 200, their arrangement must be ensured during assembly. Therefore, the positions of the heat pipe holes in the fuel assembly 200 must be measured to ensure smooth subsequent pipe installation.

[0045] There is currently no installation of a similar structure in China. The assembly method provided by the present invention not only successfully solves the problem of equal-gap installation of 30 fuel assemblies, but also meets the specific hole installation requirements of more than 2,200 sensors and power lines, which is of reference significance for subsequent similar projects.

[0046] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0047] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for precise assembly of compactly arranged fuel assemblies with equal clearances, characterized in that: include: Provide several fuel assemblies to be assembled, organize and label the leads of each fuel assembly, and tie them together with cable ties before transporting them to the vertical assembly platform where the left support plate of the core support assembly has been horizontally fixed. Use a special lifting tool to lift each fuel assembly in sequence, move each fuel assembly vertically to the corresponding interface position on the left support plate, then insert the lead of the fuel assembly into the corresponding hole at the interface position, and finally fix the fuel assembly to the left support plate at the interface position; After all fuel assemblies are installed in place, the core shroud of the core support assembly is fixedly installed to the left support plate; A dedicated guide device is used to guide all fuel assemblies, and the right support plate of the core support assembly is fixedly installed with all fuel assemblies and the core shroud.

2. The method for precise assembly of compactly arranged fuel assemblies according to claim 1, wherein: The fuel assembly is hexagonal, and the left support plate and the right support plate are pre-arranged with hexagonal interfaces corresponding to each fuel assembly. The hexagonal interfaces are arranged in a honeycomb shape, and the gaps between adjacent hexagonal interfaces are the same.

3. The method for precise assembly of compactly arranged fuel assemblies according to claim 2, wherein: The installation order of each fuel assembly is from the inside to the outside, and during the installation process, special anti-dumping tools are used to prevent the installed fuel assemblies from tipping over.

4. The method for precise assembly of compactly arranged fuel assemblies according to claim 1, wherein: The method provides a plurality of fuel assemblies to be assembled, including: The fuel assembly base is fixed using a coaxial variable diameter anti-deformation tool, positioned using a core rod, and the fuel assembly base is welded to the front and rear end cover plates.

5. The method for precise assembly of compactly arranged fuel assemblies according to claim 1, wherein: The special lifting tool lifts the fuel assembly in a horizontal state to a certain height, and then converts the fuel assembly into a vertical state, with the end of the fuel assembly with the lead facing downward.

6. The method for precise assembly of compactly arranged fuel assemblies according to claim 1, wherein: Also includes: After the right support plate is installed, the positions of the tube holes for passing the heat pipes in the fuel assembly are measured.

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