A latch fixed type heat shrink tube structure

Abstract

The application belongs to the technical field of control rod drive mechanism thermal sleeve pipe and aims to solve the problem of installing the thermal sleeve pipe from the bottom of the top cover, discloses a bolt fixed type thermal sleeve pipe structure, which comprises a sleeve pipe assembly, a pipe seat assembly and a connecting piece, the connecting piece is installed at the lower pipe opening of the CRDM pipe seat, the sleeve pipe assembly has an upper end head, the pipe seat assembly is installed outside the upper end head and connected with the connecting piece, the pipe seat assembly has a pipe seat and an anti-rotation pin assembly, the anti-rotation pin assembly is provided with a limiting nut, an anti-rotation positioning pin and a spring, the limiting nut is screwed into the pipe seat, the anti-rotation positioning pin is inserted into the center hole of the limiting nut, and the spring is installed in the bolt hole of the pipe seat. The application is a bolt fixed type novel sleeve pipe structure used when the thermal sleeve pipe is replaced from the bottom of the top cover, and is a novel structure form installed from the bottom of the top cover without damaging the primary loop pressure boundary.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of control rod drive mechanism hot sleeve pipe, and particularly relates to a bolt fixed type hot sleeve pipe structure. BACKGROUND

[0002] The control rod drive mechanism hot sleeve pipe is a component of a control rod drive mechanism (hereinafter referred to as CRDM), is installed in a CRDM pipe seat on a pressure vessel top cover, and is installed in a radial gap fit and axial unconstrained manner, and belongs to an in-pile floating component. The CRDM hot sleeve pipe is composed of three parts, the upper part is a flange, the middle section is a straight pipe section, and the lower part is a trumpet mouth, and the material is stainless steel. The normal state is that the hot sleeve pipe is hung on the CRDM pipe seat and is installed in a non-fixed suspension type.

[0003] If the defects of the CRDM hot sleeve pipe exceed the standard, the defects cannot be alleviated or repaired, and the CRDM hot sleeve pipe needs to be replaced. The replacement of the hot sleeve pipe involves the removal of the old hot sleeve pipe and the installation of the new hot sleeve pipe, and there are usually two process routes for replacing the hot sleeve pipe: replacement from above the top cover and replacement from below the top cover.

[0004] The replacement of the hot sleeve pipe from above the top cover of the in-service unit involves the following process steps: cutting of the CRDM assembly at the top of the reactor, cutting of the lower sealing weld, bevel shaping, cutting of the old hot sleeve pipe, repair of the profile of the CRDM pipe seat, design and installation of the new hot sleeve pipe structure, welding of the trumpet cover, welding of the CRDM assembly, nondestructive testing of the weld, and single-body hydraulic testing. Although the technology is relatively mature, the process is complex, the procedures are many, the construction period is long, and the economy is poor. At the same time, for the in-service unit, due to high doses and personnel unavailability, a large number of special equipment need to be developed, and a long maintenance window is needed for on-site implementation. Therefore, a process technical route for replacing the hot sleeve pipe from below the top cover needs to be developed. SUMMARY

[0005] The application aims to provide a bolt fixed type hot sleeve pipe structure, which is a novel hot sleeve pipe structure installed from below the top cover, avoids the operation of removing the upper drive mechanism to damage the pressure boundary of the primary loop during replacement of the hot sleeve pipe, and solves the problem of installing the hot sleeve pipe from below the top cover.

[0006] In order to achieve the above-mentioned purpose, the application provides the following technical scheme:

[0007] The application discloses a latch-fixed hot sleeve pipe structure, which comprises a sleeve assembly, a pipe seat assembly and a connecting piece, the connecting piece is installed at the lower pipe opening of a CRDM pipe seat, the sleeve assembly is provided with an upper end head, the pipe seat assembly is installed outside the upper end head and connected with the connecting piece, the pipe seat assembly is provided with a pipe seat and a plurality of anti-rotation pin assemblies arranged on the periphery of the pipe seat, the anti-rotation pin assembly is provided with a limiting nut, an anti-rotation positioning pin and a spring, the limiting nut is screwed into the pipe seat, the anti-rotation positioning pin is inserted into the central hole of the limiting nut, and the spring is installed in the latch hole of the pipe seat.

[0008] In some embodiments, the limiting nut is a hollow structure, and is provided with a deep key groove, a shallow key groove and a thread.

[0009] In some embodiments, the upper part of the anti-rotation positioning pin is a round rod structure, the middle part is provided with a spline matched with the deep key groove or the shallow key groove, and the bottom part is a block structure.

[0010] In some embodiments, the spring is sleeved on the anti-rotation positioning pin.

[0011] In some embodiments, the pipe seat is a hollow structure, and is provided with an inner tapered surface, and the upper end head abuts against the inner tapered surface.

[0012] In some embodiments, the upper end of the pipe seat is uniformly provided with a plurality of screw-in hanging pieces, the screw-in hanging piece is provided with a through hole, and the through hole is matched with the ear arranged in the circumferential direction of the connecting piece.

[0013] In some embodiments, the ear is provided with a through hole matched with the anti-rotation positioning pin to prevent the pipe seat from rotating.

[0014] In some embodiments, the through hole of the screw-in hanging piece is coincided with the through hole of the ear, and the through holes jointly form an insertion channel of the anti-rotation positioning pin.

[0015] In some embodiments, the lower end of the connecting piece is provided with a section of a stop opening matched with the pipe seat.

[0016] In some embodiments, the upper end head is installed on a sleeve, and the lower end of the sleeve is provided with a horn cover.

[0017] Compared with the prior art, the latch-fixed hot sleeve pipe structure has the following beneficial effects:

[0018] The application discloses a new sleeve structure of a latch-fixed type when replacing a hot sleeve pipe from below a top cover, and is a new structure type installed from below the top cover without damaging a pressure boundary of a primary loop, and is a first creation in the nuclear power industry at home and abroad.

[0019] The application adopts the method of adding a new pipe seat and moving the upper end of the hot sleeve downward, realizes the technical effect of installing the CRDM hot sleeve from below the top cover, and avoids damaging the primary loop pressure boundary when replacing the hot sleeve from above the top cover.

[0020] The application adopts the method of installing a new hot sleeve connecting piece at the lower end of the CRDM pipe seat, provides convenience for on-site construction, provides an interface for the installation of the new pipe seat, is the key link of application, realizes the convenient and reliable technical effect.

[0021] The application adopts the method of adding a latch to prevent loosening on the new pipe seat, realizes the anti-loosening between the new pipe seat and the connecting piece, and through the operation of the latch structure, the disassembly and replacement of the new pipe seat and the new sleeve can also be realized, which provides the possibility for the subsequent maintenance and replacement of the new sleeve. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the application, the following will briefly introduce the drawings needed to be used in the technical description.

[0023] Figure 1 The latch fixed hot sleeve structure installation drawing provided by the application;

[0024] Figure 2 The latch fixed hot sleeve structure installation cross-sectional view provided by the application;

[0025] Figure 3 The latch fixed hot sleeve structure provided by the application;

[0026] Figure 4 The sleeve assembly installation drawing provided by the application;

[0027] Figure 5 The sleeve assembly structure drawing provided by the application;

[0028] Figure 6 The anti-rotation pin assembly retracted state structure drawing provided by the application;

[0029] Figure 7 The anti-rotation pin assembly extended state structure drawing provided by the application;

[0030] Figure 8 The pipe seat installation without anti-loosening state provided by the application;

[0031] Figure 9 The pipe seat installation with anti-loosening state provided by the application;

[0032] Figure 10 The hot sleeve installation schematic drawing provided by the application.

[0033] BRIEF DESCRIPTION OF DRAWINGS

[0034] 1. CRDM nozzle; 2. sleeve assembly; 3. nozzle assembly; 4. connecting piece;

[0035] 21. sleeve; 22. upper end; 23. bell cover;

[0036] 31. nozzle; 32. anti-rotation pin assembly;

[0037] 321. limiting nut; 322. anti-rotation positioning pin; 323. spring. DETAILED DESCRIPTION

[0038] Further details will be described in detail below through specific embodiments.

[0039] For the convenience of understanding, first of all, a brief introduction to the hot sleeve is made. Since the upper end of the hot sleeve is a hanging end, the middle part is a sleeve, and the lower part is a bell cover, the diameter of the end is larger than that of the sleeve, and the overall size is large at the top and small at the bottom. If the original structure type is used for installation from below, the end will not be able to pass through the nozzle from below, therefore, the structure and installation method need to be customized and designed according to the scene requirements.

[0040] Therefore, the present application provides a latch fixed hot sleeve structure, when the CRDM hot sleeve is severely worn or has cracks and needs to be replaced, the defective CRDM hot sleeve is replaced from below the top cover. As shown in Figures 1 to 10 , the hot sleeve structure includes a sleeve assembly 2, a nozzle assembly 3, and a connecting piece 4.

[0041] The sleeve assembly 2 includes a sleeve 21, an upper end 22, and a bell cover 23. The sleeve 21 is inserted into the CRDM nozzle 1, the position height of the upper end 22 on the sleeve 21 is related to the position of the hot sleeve, the closer to the middle position of the pressure vessel top cover, the higher the position of the upper end 22 of the sleeve assembly 2, and the closer to the edge position, the lower the position of the upper end 22 of the sleeve assembly 2. The bell cover 23 is located at the lower part of the sleeve 21, and is used for component centering and guiding during assembly of the pressure vessel top cover.

[0042] In order to realize the insertion and support of the sleeve 21 of the sleeve assembly 2 into the CRDM nozzle 1, the present application installs a connecting piece 4 at the lower nozzle (lower end) of the CRDM nozzle 1. For example, the connecting piece 4 is fixed to the lower nozzle of the CRDM nozzle 1 by screwing.

[0043] The overall shape of the connecting piece 4 is a circular ring shape, and a section of the stop is provided at the lower end, and three ears are uniformly distributed in the circumferential direction. The stop is used for positioning cooperation with the nozzle 31, and the three ears are used for bearing hanging connection of the nozzle 31. A through hole is provided on each ear, which is used for cooperation with the anti-rotation positioning pin 322 of the anti-rotation pin assembly 32, and plays a role of preventing the nozzle 31 from rotating.

[0044] As shown in Figure 4 ,Figure 5 , Figure 8 and Figure 9 As shown, the tube seat assembly 3 includes a tube seat 31 and three anti-rotation pin assemblies 32. The tube seat 31 is cup-shaped with a conical through-hole inside. The inner conical surface is located at the lower part of the interior, and the upper end 22 of the sleeve assembly 2 is inserted into it, contacting the inner conical surface of the tube seat 31. Three screw-in hooks with through holes are evenly distributed at the upper end of the tube seat 31. When screwed in, they engage with the three ears of the connector 4. When screwed in, the through holes of the three screw-in hooks of the tube seat 31 coincide with the through holes of the three ears of the connector 4, forming the insertion channel for the anti-rotation positioning pins 322. The tube seat 31 has pin holes, the number of which is the same as the number of anti-rotation pin assemblies 32 and they are arranged accordingly. The anti-rotation pin assemblies 32 are installed on the lower periphery of the tube seat 31 through the pin holes.

[0045] like Figure 6 and Figure 7 As shown, the anti-rotation pin assembly 32 includes a limiting nut 321, an anti-rotation positioning pin 322, and a spring 323. The anti-rotation positioning pin 322 is a rod-shaped structure, with a round rod structure at the top, a spline in the middle, and a block-shaped structure at the bottom. The spring 323 is fitted onto the upper round rod structure. The limiting nut 321 is hollow in the middle, with deep and shallow keyways on the top and threads on the outside, and is screwed onto the tube seat 31.

[0046] Spring 323 is inserted into the pin hole of tube seat 31, limit nut 321 is screwed into tube seat 31, and anti-rotation positioning pin 322 is inserted into the center hole of limit nut 321, which can move up and down.

[0047] like Figure 7 As shown, the spring 323 is installed in the pin hole of the mounting tube 31, with its upper end contacting the mounting tube 31 and its lower end contacting the upper surface of the anti-rotation positioning pin 322, thus pressing the anti-rotation positioning pin 322. The anti-rotation positioning pin 322 is a long rod with a cylindrical section protruding in the middle and having a spline, which mates with the deep and shallow keyways of the limit nut 321.

[0048] The limiting nut 321 has both deep and shallow spline grooves, while the anti-rotation positioning pin 322 has one spline. When the anti-rotation positioning pin 322 is lifted and screwed down to make the spline fall into the deep keyway, the anti-rotation positioning pin 322 is in a low position and is not inserted into the positioning pin hole of the connector 4; when the anti-rotation positioning pin 322 is lifted and screwed down to make the spline fall into the shallow keyway, the anti-rotation positioning pin 322 is in a high position and is inserted into the positioning pin hole of the connector 4, thus preventing the tube seat assembly 3 from rotating.

[0049] This heat jacket structure is detachable, which allows for the replacement and maintenance of internal reactor components.

[0050] The hot sleeve structure is used for replacing the defective sleeve when the sleeve of the CRDM is seriously worn and reaches the replacement standard. The replacement is performed from the bottom of the top cover, thereby avoiding cutting and removing the control rod drive mechanism, reducing the workload and improving the economy of the power plant overhaul.

[0051] Meanwhile, the sleeve design changes the original sleeve mounting support position, under the premise of ensuring the original design function unchanged and not reducing the sleeve structure strength, the sleeve support position is moved down to the lower pipe opening of the CRDM pipe seat, the new pipe seat and the connecting piece adopt the latch fixed structure, the repeated disassembly and assembly of the hot sleeve structure can be realized, and it is a permanent solution for the M310 and Hualong No.1 reactor type hot sleeve defects.

[0052] The above merely describes the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which shall be covered within the protection scope of the present application.

Claims

1. A pin-fixed heat sleeve structure, characterized in that, The device includes a sleeve assembly (2), a pipe seat assembly (3), and a connector (4). The connector (4) is installed at the lower end of the CRDM pipe seat (1). The sleeve assembly (2) has an upper end (22). The pipe seat assembly (3) is installed outside the upper end (22) and connected to the connector (4). The pipe seat assembly (3) has a pipe seat (31) and several anti-rotation pin assemblies (32) arranged around the pipe seat (31). Each anti-rotation pin assembly (32) has a limiting nut (321), an anti-rotation positioning pin (322), and a spring (323). The limiting nut (321) is screwed into the pipe seat. In the seat (31), the anti-rotation positioning pin (322) is inserted into the center hole of the limiting nut (321), and the spring (323) is installed in the pin hole of the tube seat (31); a number of screw-in hooks are evenly distributed on the upper end of the tube seat (31), the screw-in hooks have through holes, the through holes are adapted to the ears arranged circumferentially on the connector (4), the ears are provided with through holes to cooperate with the anti-rotation positioning pin (322) to prevent the tube seat (31) from rotating, the through holes of the screw-in hooks coincide with the through holes of the ears, and together they form the insertion channel of the anti-rotation positioning pin (322).

2. The pin-fixed heat sleeve structure according to claim 1, characterized in that, The limiting nut (321) has a hollow structure and is provided with a deep keyway, a shallow keyway and threads.

3. The pin-fixed heat sleeve structure according to claim 2, characterized in that, The anti-rotation positioning pin (322) has a round rod structure at the top, a spline in the middle that mates with the deep keyway or the shallow keyway, and a block structure at the bottom.

4. The pin-fixed heat sleeve structure according to claim 3, characterized in that, The spring (323) is sleeved on the anti-rotation positioning pin (322).

5. The pin-fixed heat sleeve structure according to claim 1, characterized in that, The tube seat (31) is a hollow structure with an inner conical surface, and the upper end (22) abuts against the inner conical surface.

6. The pin-fixed heat sleeve structure according to claim 1, characterized in that, The lower end of the connector (4) has a stop for positioning and engaging with the tube seat (31).

7. The pin-fixed heat sleeve structure according to claim 1, characterized in that, The upper end (22) is installed on the sleeve (21), and the lower end of the sleeve (21) is provided with a horn cover (23).

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