Nuclear power plant control rod guide tube

Abstract

The application discloses a nuclear power plant control rod guide tube, which comprises a protective cover and a full-range guide assembly installed in the protective cover; the full-range guide assembly comprises at least one full-range continuous guide element, and a full-range continuous guide channel is arranged in the full-range continuous guide element; the full-range continuous guide channel continuously guides at least one control rod in a single control rod assembly in a full range of the guide tube stroke. Compared with the prior art, the nuclear power plant control rod guide tube changes the non-continuous guide segment structure of the interval arranged guide panel into the full-range continuous guide segment formed by the long double-pipe structure, optimizes the control rod stroke protection function, reduces the risk of the control rod bending deformation caused by the transverse impact of the upper chamber fluid on the control rod, and guarantees the integrity of the control rod structure; meanwhile, the wear resistance of the specific position of the control rod guide tube is improved, so that the service life of the control rod guide tube is greatly prolonged, and the later operation cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of control rod guide of pressurized water reactor nuclear power plant, and more particularly, the present application relates to a control rod guide thimble of nuclear power plant. BACKGROUND

[0002] The control rod drive line of pressurized water reactor is mainly composed of control rod drive mechanism, pressure vessel nozzle, hot sleeve, control rod guide thimble and fuel assembly. When the reactor is running, the control rod moves up and down along the drive line mainly between the head cavity, upper cavity and core cavity. Since the control rod is affected by fluid at different height positions, if there is no protection device for the control rod running channel, the control rod will be subjected to severe swing and deviate from the vertical direction, which cannot work normally. Therefore, the control rod guide thimble is arranged to guide and protect the control rod, when the control rod runs in the head cavity and upper cavity, the control rod and drive rod can move, insert and pull out along the vertical direction of the control rod guide thimble, which is protected and guided by the control rod guide thimble, so as to ensure that the control rod is not impacted by fluid and stably runs, and to reduce the influence of coolant transverse load on the rod drop time in transient and steady state operation. In order to ensure the smooth coupling of the drive rod and the control rod next time, the drive rod needs to be stored in a suitable position on the drive line, and the control rod guide thimble provides a convenient and feasible storage position. The continuous guide assembly arranged in the control rod guide thimble is a component for protecting the control rod, which ensures that the control rod is quickly inserted into the core when needed.

[0003] Please refer to Figure 1 The existing control rod guide thimble is composed of a lower guide section 10 and an upper guide section 11, which are connected back to back through flanges 110 and 103, and the flanges 110 and 103 are fixed on the support plate of the upper in-vessel component by bolts. The upper guide section 11 is a cylindrical structure, and four guide panels 111 are embedded in the inside. The lower guide section 10 is composed of a cladding 100, a continuous guide section 101 and a guide panel 102; the cladding 100 is a square cylinder which is spliced and welded by two half square cylinders, the upper end of which is welded with the middle flange 103, and the lower end of which is welded with the lower flange 104; the guide panel 102 is welded and embedded in the cladding 100; the continuous guide section 101 is a section of the cladding 100 close to the lower flange 104, which is composed of a C-shaped tube and a double-hole tube between the guide panel 102 at the lowermost end and the lower flange 104, so that the entire continuous guide section 101 is a continuous guide. After installation, the continuous guide section is a guide structure above the fuel assembly, which is at a sensitive position where the fluid changes from vertical to horizontal at the outlet of the core, and plays an important role in the control rod drop performance and the structural integrity of the control rod.

[0004] From the above description, it can be seen that the existing control rod guide tube can only continuously guide the control rod by the continuous guide section 101 at the lower end, and the rest of the control rod guide tube only relies on the guide panels 102, 111 arranged at intervals to guide the control rod, which is discontinuous guidance. This causes the wear speed of the guide panels 102, 111 at specific positions to be fast, thereby resulting in a short service life of the entire control rod guide tube, and the control rod guide tube often needs to be replaced during the service life of the reactor.

[0005] Therefore, it is necessary to provide a nuclear power plant control rod guide tube capable of solving the above problems. SUMMARY

[0006] The present application aims to provide a nuclear power plant control rod guide tube that is not easy to wear, thereby prolonging its service life.

[0007] In order to achieve the above-mentioned application purposes, the present application provides a nuclear power plant control rod guide tube, which comprises a protective cover and a full-range guide assembly installed in the protective cover; the full-range guide assembly comprises at least one full-range continuous guide element, a full-range continuous guide channel is arranged in the full-range continuous guide element, and the full-range continuous guide channel continuously guides at least one control rod in a single control rod assembly in the entire stroke range of the guide tube.

[0008] As an improvement of the nuclear power plant control rod guide tube of the present application, the full-range guide assembly further comprises a lower flange and a plurality of guide panels, which are arranged at intervals along the axial direction of the full-range continuous guide element and serve as the radial support of the full-range continuous guide element; the full-range continuous guide element penetrates through the lower flange and all the guide panels and is fixed in the lower flange and the guide panels, thereby providing the full-range continuous guide channel for the control rod.

[0009] As an improvement of the nuclear power plant control rod guide tube of the present application, the full-range continuous guide element is a long double pipe, two guide holes are arranged in each long double pipe, and the long double pipe can continuously guide two control rods; the number of the long double pipes is at least two, and one guide hole in each long double pipe continuously guides a control rod close to the center in a single control rod assembly.

[0010] As an improvement of the nuclear power plant control rod guide tube of the present application, the full-range guide assembly further comprises a short-range continuous guide element, the short-range continuous guide element penetrates through the lowermost guide panel and the lower flange and is fixed in the lowermost guide panel and the lower flange, and the long double pipe and the short-range continuous guide element jointly form a full-channel continuous guide section of the control rod bundle, which continuously guides all the control rods between the lowermost guide panel and the lower flange.

[0011] As an improvement of the nuclear power plant control rod guide tube, the short-range continuous guide element comprises short double pipes and C-shaped pipes; each short double pipe is provided with two guide holes, capable of guiding the lower sections of two control rods in a short range; the cross section of the C-shaped pipe is C-shaped, used for guiding the lower sections of other control rods in a short range except the short double pipes and long double pipes.

[0012] As an improvement of the nuclear power plant control rod guide tube, the number of long double pipes is four; the cross section of the guide grid plate is circular, the two guide holes of each long double pipe are located on the same radius of the cross section of the guide grid plate, and the four long double pipes form a center-unconnected "cross" shape on the circular cross section of the guide grid plate, capable of guiding the four control rods close to the center and the four peripheral control rods in a single control rod assembly in a full range.

[0013] As an improvement of the nuclear power plant control rod guide tube, the number of short double pipes is four, and the four short double pipes are arranged at intervals with the four long double pipes, forming a center-unconnected "Wen" shape on the circular cross section of the guide grid plate; each short double pipe guides the lower sections of two control rods in a single control rod assembly in a short range; the number of C-shaped pipes is eight, located between the short double pipes and the long double pipes, guiding the lower sections of the eight peripheral control rods in a short range.

[0014] As an improvement of the nuclear power plant control rod guide tube, the lower flange is welded to the lower end of the protective cover, and the other parts of the full-range guide assembly are inserted into the protective cover.

[0015] As an improvement of the nuclear power plant control rod guide tube, the nuclear power plant control rod guide tube further comprises a first centering structure and / or a second centering structure fixed to the protective cover, the first centering structure and the second centering structure are clamped into the corresponding guide grid plates of the full-range guide assembly, limiting the radial and circumferential movement of the full-range guide assembly.

[0016] As an improvement of the nuclear power plant control rod guide tube, the first centering structure is installed at the uppermost guide grid plate, comprising at least two equally spaced pins; the outer peripheral wall of the uppermost guide grid plate is provided with grooves corresponding to the pins, the first end of the pin is clamped into the corresponding groove of the uppermost guide grid plate through the upper protective sleeve, and the second end is welded and fixed to the upper protective sleeve.

[0017] As an improvement of the nuclear power plant control rod guide tube, the first end of the pin and the groove are gap-fitted in the radial and circumferential directions of the uppermost guide grid plate; in the axial direction of the uppermost guide grid plate, the groove penetrates the uppermost guide grid plate.

[0018] As an improvement of the nuclear power plant control rod guide tube, the protective cover comprises an upper protective sleeve and a lower protective sleeve, the lower end of the upper protective sleeve is provided with a first flange, the upper end of the lower protective sleeve is provided with a second flange, and the upper protective sleeve and the lower protective sleeve are connected back to back through the first flange and the second flange.

[0019] As an improvement of the nuclear power plant control rod guide tube, the second centering structure is installed at the middle guide panel at the connection position of the first flange and the second flange; the second centering structure comprises at least two limiting assemblies arranged at equal intervals, each limiting assembly comprises a positioning block and a positioning pin; the outer circumferential wall of the middle guide panel is provided with a groove corresponding to the positioning block, and the first end of the positioning block is fixed in the second flange and / or the first flange through the positioning pin, and the second end is clamped into the corresponding groove of the middle guide panel.

[0020] As an improvement of the nuclear power plant control rod guide tube, in the radial direction of the middle guide panel, the second end of the positioning block is clamped into the groove to press the middle guide panel, the second end of the positioning block is provided with an elastic groove, and the existence of the elastic groove enables the second end of the positioning block to appropriately retract when the positioning block is subjected to the radial pressure of the middle guide panel; in the circumferential direction of the middle guide panel, the second end of the positioning block is in clearance fit with the groove; and in the axial direction of the middle guide panel, the groove penetrates the middle guide panel.

[0021] As an improvement of the nuclear power plant control rod guide tube, the first flange and the second flange are fixedly connected to the upper support plate of the upper in-core structure through fasteners.

[0022] As an improvement of the nuclear power plant control rod guide tube, the nuclear power plant control rod guide tube further comprises an elastic split pin arranged below the lower flange, and the lower flange is in easy-to-disassemble tight fit connection with the upper core plate through the elastic split pin.

[0023] Compared with the prior art, the nuclear power plant control rod guide tube changes the non-continuous guide segment structure of the spaced guide panels into a full-range continuous guide segment formed by a long double-pipe structure, optimizes the control rod stroke protection function, reduces the risk of rod bending deformation caused by the transverse impact of the upper chamber fluid on the control rod, and ensures the integrity of the control rod structure; at the same time, the wear resistance of the control rod guide tube at a specific position is improved, thereby greatly prolonging the service life of the control rod guide tube and reducing the later operation cost. The first centering structure and the second centering structure are used to center and position the full-range guide assembly in the protective cover, so that the full-range guide assembly is limited in the radial direction and the circumferential direction while keeping axial freedom, eliminates the internal stress of the control rod guide tube caused by the temperature difference between the inside and outside of the cylinder, and reduces the stress level of the inner components of the control rod guide tube. BRIEF DESCRIPTION OF DRAWINGS

[0024] The present application nuclear power plant control rod guide tube and its beneficial effects are described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0025] Figure 1 is a structural schematic diagram of the prior control rod guide tube.

[0026] Figure 2 is a structural schematic diagram of the present application nuclear power plant control rod guide tube.

[0027] Figure 3 is a structural schematic diagram of the present application nuclear power plant control rod guide tube.

[0028] Figure 4 is Figure 3 is a bottom view of the A-A section.

[0029] Figure 5 is Figure 3 is a top view of the B-B section.

[0030] Figure 6 is Figure 2 is a top view of the C-C section.

[0031] Figure 7 is a structural schematic diagram of a pin of the first centering structure and the upper protective sleeve and the uppermost guide panel.

[0032] Figure 8 is Figure 2 is a top view of the D-D section.

[0033] Figure 9 is Figure 8 is an enlarged structural schematic diagram of a limiting component.

[0034] Figure 10 is a structural schematic diagram of the limiting component of the first centering structure and the first flange, the second flange and the middle guide panel.

[0035] Figure 11 is a structural schematic diagram of the elastic split pin below the lower flange.

[0036] Figure 12 is a structural schematic diagram of the present application nuclear power plant control rod guide tube. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and beneficial technical effects of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described in the present specification are only for the purpose of explaining the present application, and are not intended to limit the present application.

[0038] Please refer to Figures 2 to 5The nuclear power plant control rod guide tube comprises a protective cover 30 and a full-range guide assembly 40 installed in the protective cover 30; the full-range guide assembly 40 comprises at least one full-range continuous guide element, and a full-range continuous guide channel is arranged in the full-range continuous guide element; the full-range continuous guide channel continuously guides at least one control rod in a single control rod assembly in a full range of the guide tube.

[0039] The protective cover 30 comprises an upper protective sleeve 32 and a lower protective sleeve 34; a first flange 320 is arranged at the lower end of the upper protective sleeve 32, and a second flange 340 is arranged at the upper end of the lower protective sleeve 34; the upper protective sleeve 32 and the lower protective sleeve 34 are connected back to back through the first flange 320 and the second flange 340, and the first flange 320 and the second flange 340 are fixedly connected to the upper support plate 81 (as shown in Figure 12 The fastener can be a bolt.

[0040] The full-range guide assembly 40 further comprises a lower flange 440 and a plurality of guide panels 44 (the guide panels 44 comprise ordinary guide panels 441, a lowermost guide panel 442, an uppermost guide panel 444, and a middle guide panel 446 located at the connection position of the first flange 320 and the second flange 340); the lower flange 440 and the plurality of guide panels 44 are spaced apart along the axial direction of the full-range continuous guide element and serve as radial supports of the full-range continuous guide element; the full-range continuous guide element penetrates the entire full-range guide assembly from bottom to top and provides a full-range continuous guide channel for the control rod, thereby guiding and protecting the control rod in a full range of the guide tube. The full-range continuous guide element penetrates the lower flange 440 and all the guide panels 44 and is fixed in the lower flange 440 and the guide panels 44, and the fixing mode is preferably welding. The lower flange 440 is connected to the lower end of the lower protective sleeve 34 of the protective cover 30, and the other parts of the full-range guide assembly 40 are inserted into the protective cover 30. The guide panels 44 are distributed in the upper protective sleeve 32 and the lower protective sleeve 34, and one of the guide panels 44 is located at the connection position of the upper protective sleeve 32 and the lower protective sleeve 34, which is referred to as the middle guide panel 446 in this specification (the "middle" of the middle guide panel 446 means that the position of this guide panel is approximately in the middle region of the nuclear power plant control rod guide tube, but it is not specifically located in the middle of all the guide panels). The connection between the lower flange 440 and the lower end of the lower protective sleeve 34 is a welded connection.

[0041] Each of the full-length continuous guiding elements is provided with at least one continuous guiding channel, and each of the continuous guiding channels continuously guides one control rod in the single set of control rod assemblies in the whole stroke range of the guide cylinder. Specifically, the full-length continuous guiding elements are preferably long double pipes 42, which have good structural stability, and each of the long double pipes 42 is provided with two guiding holes, and can continuously guide two control rods in the whole stroke range. The number of the long double pipes 42 is at least two, and each of the long double pipes 42 has one guiding hole, which continuously guides one control rod close to the center in the single set of control rod assemblies in the whole stroke range.

[0042] In the single set of control rod assemblies, the four control rods close to the center are most prone to wear, and therefore, the number of the long double pipes 42 is preferably four. Please refer to FIG. 2. Figure 4 In the embodiment shown in FIG. 2, the cross section of the guiding lattice plate 44 is circular, the two guiding holes of each of the long double pipes 42 are located on the same radius of the cross section of the guiding lattice plate, and the four long double pipes 42 form a center-unconnected "cross" on the circular cross section of the guiding lattice plate 44, and the four long double pipes 42 continuously guide the four control rods close to the center and the four peripheral control rods in the single set of control rod assemblies in the whole stroke range. The long double pipes 42 have good structural stability, are evenly distributed on the guiding lattice plate 44, and can continuously guide and protect the four control rods close to the center in the whole stroke range of the guide cylinder, thereby reducing the failure probability of the guide cylinder of the control rods, and prolonging the service life of the guide cylinder of the control rods. The fixing mode of the long double pipes 42 and the guiding lattice plate 44 is welding.

[0043] In order to guide the other control rods except the long double pipes 42, the full-length guiding assembly 40 further comprises short-length continuous guiding elements. The short-length continuous guiding elements pass through and are fixed in the lowermost guiding lattice plate 442 and the lower flange 440, and the long double pipes 42 and the short-length continuous guiding elements together form a continuous guiding section of the whole channel of the control rod bundle, and continuously guide all the control rods between the lowermost guiding lattice plate 442 and the lower flange 440.

[0044] Specifically, the short-length continuous guiding elements comprise short double pipes 46 and C-shaped pipes 48. Each of the short double pipes 46 is provided with two guiding holes, and can continuously guide two control rods in a short stroke range; the cross section shape of the short double pipes 46 is similar to that of the long double pipes 42, but the distance between the two guiding holes is slightly smaller than that of the long double pipes 42. The cross section of the C-shaped pipe 48 is C-shaped, and is used to continuously guide the lower segments of the other control rods except the short double pipes 46 and the long double pipes 42 in a short stroke range.

[0045] Specifically, in the embodiment shown in FIG. 2, the short double pipes 46 are arranged in the lowermost guiding lattice plate 442 and the lower flange 440, and the C-shaped pipes 48 are arranged in the lowermost guiding lattice plate 442 and the lower flange 440. Figure 5In the shown embodiment, the number of short double pipes 46 is preferably four, which are arranged at intervals with the four long double pipes 42 to form a central unconnected "W" shape on the circular cross section of the guide grid 44. Each short double pipe 46 forms a short-range continuous guide for the lower segments of two control rods on the same radius in a single control rod assembly. The number of C-shaped pipes 48 is eight, which are arranged between the short double pipes 46 and the long double pipes 42 to form a short-range continuous guide for the lower segments of the eight peripheral control rods. The long double pipes 42, the short double pipes 46 and the C-shaped pipes 48 together form a continuous guide section for the entire passage of the control rod bundle, which forms a continuous guide for all the control rods between the lowermost guide grid 442 and the lower flange 440, effectively preventing the bending of the control rods and ensuring the falling rod performance and structural integrity of the control rods.

[0046] In order to realize the centering and positioning of the full-range guide assembly 40 in the protective cover 30, the nuclear power plant control rod guide tube further comprises a first centering structure and / or a second centering structure fixed to the protective cover 30, which are clamped into the corresponding guide grids 44 of the full-range guide assembly 40 to limit the radial and circumferential movement of the full-range guide assembly 40, but do not limit the axial movement.

[0047] Please refer to Figure 2 , Figure 6 and Figure 7 , the first centering structure is installed at the uppermost guide grid 444, which comprises at least two equally spaced pins 50. The outer peripheral wall of the uppermost guide grid 444 is provided with a corresponding groove 445 for each pin 50, the first end 52 of the pin 50 is clamped into the corresponding groove 445 of the uppermost guide grid 444 through the upper protective sleeve 32, and the second end 54 is welded and fixed to the upper protective sleeve 32. In the radial and circumferential direction of the uppermost guide grid 444, the first end 52 of the pin 50 and the groove 445 are both clearance fit, so that the radial and circumferential movement of the upper end position of the full-range guide assembly 40 can be limited by the pin 50; in the axial direction of the uppermost guide grid 444, the groove 445 penetrates the uppermost guide grid 444, so that the pin 50 does not limit the axial movement of the full-range guide assembly 40, keeping the axial relative freedom of the full-range guide assembly 40 to avoid the generation of internal stress of the full-range guide assembly 40 at the pin 50 due to the temperature difference between the inside and outside of the control rod guide tube. The number of pins 50 is preferably four.

[0048] Please refer to Figure 2 and Figures 8-10The second centering structure is installed at the middle guide panel 446 at the connection position of the first flange 320 and the second flange 340, and comprises at least two equally spaced limiting assemblies 60, each of which comprises a positioning block 62 and a positioning pin 64. The outer circumferential wall of the middle guide panel 446 is provided with a groove 447 corresponding to the positioning block 62, the first end 621 of the positioning block 62 is fixed in the second flange 340 and / or the first flange 320 through the positioning pin 64, and the second end 622 is clamped into the corresponding groove 447 of the middle guide panel 446; in the radial direction of the middle guide panel 446, the second end 622 of the positioning block 62 is clamped into the groove 447 to press the middle guide panel 446, and the radial movement of the middle position of the full-range guide assembly 40 can be limited through the positioning block 62, at the same time, the second end 622 of the positioning block 62 is provided with an elastic groove 624, so that the second end 622 can be appropriately retracted when the positioning block 62 is subjected to the radial pressure of the middle guide panel 446; in the circumferential direction of the middle guide panel 446, the second end 622 of the positioning block 62 is gap-fitted with the groove 447, and the circumferential movement of the middle position of the full-range guide assembly 40 can be limited through the positioning block 62. In the axial direction of the middle guide panel 446, the groove 447 penetrates the middle guide panel 446, so that the positioning block 62 does not limit the axial movement of the full-range guide assembly 40, and the full-range guide assembly 40 is kept relatively free in the axial direction, so as to avoid the generation of internal stress of the full-range guide assembly 40 at the positioning block 62 due to different temperature differences between the inner side and the outer side. The number of limiting assemblies 60 is preferably 4.

[0049] It is easy to understand that the nuclear power plant control rod guide tube of the present application can be provided with both the first centering structure and the second centering structure, or can be provided with only one of the first centering structure and the second centering structure, and the first centering structure can be installed not only at the uppermost guide panel 444, but also at the guide panel at other positions, such as the guide panel 441 at any position, or even at the lowermost guide panel 442 or the middle guide panel 446 if necessary.

[0050] Please refer to Figure 11 The nuclear power plant control rod guide tube of the present application further comprises an elastic split pin 70 arranged below the lower flange 440, and the lower flange 440 is in easy-to-disassemble tight fit connection with the upper core plate 82 (as shown in Figure 12 .

[0051] Please refer to Figure 12The upper in-core structure in the reactor pressure vessel 80 includes an upper support plate 81 and a core upper plate 82, and the nuclear power plant control rod guide tube is fixed on the upper support plate 81 and the core upper plate 82, and the specific installation mode is that the first flange 320 and the second flange 340 of the protective cover 30 are fixedly connected on the upper support plate 81 through fasteners, and the lower flange 440 of the full-range guide assembly 40 is in detachable tight fit connection with the core upper plate 82 through the elastic split pin 70, so that the replacement requirement of the control rod guide tube is met. After installation, the upper section of the control rod guide tube 88 is located in the reactor head cavity chamber 84, and the lower section of the control rod guide tube 88 is located in the reactor upper cavity chamber 85. The entire control rod guide tube 88 is located on the reactor control rod drive line, the lower end is centered with the fuel assembly 860 in the core cavity chamber 86, and a guide channel is provided for the control rod assembly to enter the fuel assembly 860. The nuclear power plant control rod guide tube of the present application provides guidance for the control rod assembly, allows the control rod and the drive rod to move, insert and extract in the vertical direction, protects the control rod, and reduces the influence of the transverse force of the coolant on the rod drop time during transient and steady-state operation. When the drive rod connecting joint is disconnected from the star-shaped frame, the drive rod is seated on the support of the double pipe and remains in a vertical position.

[0052] As known from the above description, the nuclear power plant control rod guide tube of the present application changes the non-continuous guide section structure of the spaced guide lattices into a full-range continuous guide section formed by the long double pipe structure, optimizes the control rod stroke protection function, reduces the risk of rod bending deformation caused by the transverse impact of the upper cavity chamber fluid on the control rod, and ensures the integrity of the control rod structure. At the same time, the wear resistance of the control rod guide tube at a specific position is improved, thereby greatly prolonging the service life of the control rod guide tube and reducing the later operation cost.

[0053] Compared with the prior art, the nuclear power plant control rod guide tube of the present application has at least the following advantages:

[0054] 1) At least one full-range continuous guide element is arranged, the guide and stroke protection functions of the control rod at a specific position are optimized, the risk of rod bending deformation caused by the fluid impact on the control rod is reduced, and the integrity of the control rod structure is ensured.

[0055] 2) At least one full-range continuous guide element is arranged at a specific position, the influence of the fluid transverse disturbance is reduced by optimizing the continuous guide function, the control rod operation and rod drop process are more stable, and the operation performance of the control rod drive line is improved.

[0056] 3) At least one full-range continuous guide element is arranged at a specific position, the wear resistance of the sensitive area of the control rod guide tube is greatly improved, the failure probability of the control rod guide tube is reduced, and the service life of the control rod guide tube is prolonged.

[0057] 4) Long double pipe 42, short double pipe 46, C-shaped pipe 48 together form the continuous guide section of the whole channel of the control rod bundle, and form continuous guide for all control rods between the lowermost guide grid plate 442 and the lower flange 440, which can effectively prevent the bending of the control rod and ensure the falling rod performance and structural integrity of the control rod.

[0058] 5) The long double pipe 42 is used to connect the lower flange and all guide grid plates 44, which simplifies the structure and is easy to manufacture.

[0059] 6) The first centering structure and the second centering structure are used to realize the centering and positioning of the whole guide assembly 40 in the protective cover 30, so that the whole guide assembly 40 is limited in the radial and circumferential directions while keeping axial freedom, eliminating the internal stress of the control rod guide cylinder caused by the temperature difference between the inside and outside of the cylinder, and reducing the stress level of the internal components of the control rod guide cylinder.

[0060] 7) The first centering structure, the second centering structure and the bottom welding connection structure are used to improve the structural rigidity of the whole guide assembly 40 and limit the amplitude and stress of flow-induced vibration.

[0061] According to the disclosure and teaching of the above description, those skilled in the art of the present application can also make appropriate changes and modifications to the above embodiments. Therefore, the present application is not limited to the specific embodiments disclosed and described above, and some modifications and changes of the present application should fall within the protection scope of the claims of the present application. In addition, although some specific terms are used in the specification, these terms are only for convenience of description and do not constitute any limitation on the present application.

Claims

1. A nuclear power plant control rod guide tube characterized by: The device comprises a protective cover and a full-range guiding assembly installed in the protective cover; the full-range guiding assembly comprises at least one full-range continuous guiding element which runs through the full-range guiding assembly from bottom to top, and a full-range continuous guiding channel is arranged in the full-range continuous guiding element to continuously guide at least one control rod in a single control rod assembly within the stroke range of the guiding cylinder; the full-range continuous guiding element is a long double pipe, two guiding holes are arranged in each long double pipe to continuously guide two control rods; the number of the long double pipes is at least two, and one guiding hole in each long double pipe continuously guides a control rod close to the center in a single control rod assembly; the protective cover comprises an upper protective sleeve and a lower protective sleeve; the full-range guiding assembly further comprises a plurality of guiding panels which are spaced along the axial direction of the full-range continuous guiding element. The nuclear power plant control rod guiding cylinder further comprises a first centering structure and a second centering structure fixed to the protective cover; the first centering structure and the second centering structure are clamped into the corresponding guiding panels of the full-range guiding assembly to limit the radial and circumferential movement of the full-range guiding assembly; the first centering structure is installed at the uppermost guiding panel and comprises at least two equally spaced pins; the outer peripheral wall of the uppermost guiding panel is provided with grooves corresponding to the pins; the first end of the pin is clamped into the corresponding groove of the uppermost guiding panel through the upper protective sleeve, and the second end is welded and fixed to the upper protective sleeve. The lower end of the upper protective sleeve is provided with a first flange, and the upper end of the lower protective sleeve is provided with a second flange; the upper protective sleeve and the lower protective sleeve are connected back to back through the first flange and the second flange; the second centering structure is installed at the middle guiding panel at the connection position of the first flange and the second flange; the second centering structure comprises at least two equally spaced limiting assemblies; each limiting assembly comprises a positioning block and a positioning pin; the outer peripheral wall of the middle guiding panel is provided with grooves corresponding to the positioning blocks; the first end of the positioning block is fixed to the second flange and / or the first flange through the positioning pin, and the second end is clamped into the corresponding groove of the middle guiding panel.

2. The nuclear power plant control rod guide tube of claim 1, wherein: The full-range guiding assembly further comprises a lower flange, and the lower flange and the plurality of guiding panels serve as the radial support of the full-range continuous guiding element; the full-range continuous guiding element runs through the lower flange and all the guiding panels and is fixed in the lower flange and the guiding panels to provide a full-range continuous guiding channel for the control rods.

3. The nuclear power plant control rod guide tube of claim 2, wherein: The full-range guiding assembly further comprises a short-range continuous guiding element, which penetrates and is fixed in the lowermost guiding grid plate and the lower flange, and the long double-pipe and the short-range continuous guiding element together form a continuous guiding section of the full channel of the control rod bundle, which continuously guides all the control rods between the lowermost guiding grid plate and the lower flange.

4. The nuclear power plant control rod guide tube of claim 3, wherein: The short-range continuous guiding element comprises short double-pipes and C-shaped pipes; each of the short double-pipes is provided with two guiding holes, which can continuously guide the lower sections of two control rods; the cross section of the C-shaped pipe is C-shaped, which is used to continuously guide the lower sections of the control rods other than the short double-pipes and the long double-pipes.

5. The nuclear power plant control rod guide tube of claim 4, wherein: The number of the long double-pipes is four; the cross section of the guiding grid plate is circular, and the two guiding holes of each long double-pipe are located on the same radius of the cross section of the guiding grid plate, and the four long double-pipes form a central unconnected "cross" on the circular cross section of the guiding grid plate, which continuously guides the four control rods close to the center and the four peripheral control rods in a single control rod assembly.

6. The nuclear power plant control rod guide tube of claim 5, wherein: The number of the short double-pipes is four, which are arranged at intervals with the four long double-pipes to form a central unconnected "Wen" on the circular cross section of the guiding grid plate, and each short double-pipe continuously guides the lower sections of two control rods on the same radius in a single control rod assembly; the number of the C-shaped pipes is eight, which are located between the short double-pipes and the long double-pipes to continuously guide the lower sections of the eight peripheral control rods.

7. The nuclear power plant control rod guide tube of claim 2, wherein: The lower flange is welded to the lower end of the protective cover, and the other parts of the full-range guiding assembly are inserted into the protective cover.

8. The nuclear power plant control rod guide tube of claim 1, wherein: In the radial direction and the circumferential direction of the uppermost guiding grid plate, the first end of the pin is in clearance fit with the groove; in the axial direction of the uppermost guiding grid plate, the groove penetrates the uppermost guiding grid plate.

9. The nuclear power plant control rod guide tube of claim 8, wherein: In the radial direction of the middle guiding grid plate, the second end of the positioning block is pressed against the middle guiding grid plate after being clamped into the groove, and the second end of the positioning block is provided with an elastic groove, which allows the second end to appropriately retract when the positioning block is pressed in the radial direction of the middle guiding grid plate; in the circumferential direction of the middle guiding grid plate, the second end of the positioning block is in clearance fit with the groove; in the axial direction of the middle guiding grid plate, the groove penetrates the middle guiding grid plate.

10. The nuclear power plant control rod guide tube of claim 9, wherein: The first flange and the second flange are fixedly connected to the upper support plate of the upper in-core structure by fasteners.

11. The nuclear power plant control rod guide tube of claim 2, wherein: The control rod guide tube of the nuclear power plant further comprises an elastic split pin arranged below the lower flange, and the lower flange is in easy-to-disassemble tight fit with the upper core plate through the elastic split pin.

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