Method for installing a reactor vessel head

Abstract

The application discloses a reactor pressure vessel head installation method, which comprises the following steps: step S1, auxiliary tools are pre-installed on the head, wherein the auxiliary tools comprise head support devices for supporting the head on the pressure vessel and head waterproof covers for protecting the head from the influence of the pool decontamination work; step S2, after the reactor is completed with loading and starts to drain, the head is hoisted above the reactor pressure vessel, and the head is kept higher than the height of the pool water surface; step S3, the head support devices are positioned behind the reactor pressure vessel, foreign matter inspection is performed, and then the head is positioned on the reactor pressure vessel; and step S4, the lifting appliance is removed, and the head waterproof cover is debugged. The reactor pressure vessel head installation method is beneficial to the pool decontamination work after the head is positioned on the reactor core, can reduce the personnel dose to a certain extent, and makes the efficiency in safe production improved and the personnel risk reduced.

Description

Technical Field

[0001] The invention relates to the field of nuclear power plant maintenance equipment, and in particular to a method for installing the top cover of a reactor pressure vessel. Background Technology

[0002] In the post-fuel loading process of nuclear power plant overhauls, the process of closing the reactor core using a dummy head has been consistently used. This process has drawbacks such as high risk and long construction period. During fuel loading, the water level in the reactor core pool is +19.5m. After fuel loading, the upper components are reinstalled, and the control rod drive rods are engaged, the reactor core pool drainage work can begin. Since the internal components (upper components) are already in place and the control rod drive rods are connected before drainage, and the prerequisites for top cover installation, such as guide columns, are also in place, the top cover (which must not come into contact with the reactor core water) can actually be slowly lowered during the reactor core drainage process until it is in place in the reactor core. However, the above approach has not been adopted for the following reasons: During the period from the drainage of the reactor water pool to the installation of the top cover, there is still a small probability of foreign objects being introduced or damaged on the sealing surface of the reactor pressure vessel. If the top cover is installed directly during the drainage, there will be no opportunity to conduct a final inspection before the top cover is in place. If the top cover is installed directly during the drainage, it will be difficult to carry out the decontamination work of the reactor water pool after the top cover is in place of the reactor core without new special tools.

[0003] For the reasons mentioned above, the current post-fuel loading and drainage process does not involve directly installing the top cover as the drainage water level drops. Instead, a dummy top cover (dummy head) is introduced to replace the original top cover and is located in the reactor core. This process has a long lead time, high dosage, and significant personnel risks, indicating considerable room for improvement and an urgent need for improvement. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for installing the top cover of a reactor pressure vessel.

[0005] The technical solution adopted by this invention to solve its technical problem is: constructing a method for installing a reactor pressure vessel top cover, which includes the following steps:

[0006] Step S1: Pre-install auxiliary tools onto the top cover. The auxiliary tools include a top cover support device for supporting the top cover on the pressure vessel and a top cover waterproof cover for protecting the top cover from the decontamination work in the water tank.

[0007] Step S2: After the reactor has finished loading and started draining, use a lifting device to lift the top cover to the top of the reactor pressure vessel, so that the top cover is kept above the water level of the reactor pool.

[0008] Step S3: After positioning the top cover support device in the reactor pressure vessel, perform a foreign object inspection, and then position the top cover in the reactor pressure vessel.

[0009] Step S4: Remove the lifting equipment and test the top waterproof cover.

[0010] In some embodiments, the auxiliary tool further includes a top cover ladder for enabling workers to disconnect and reconnect the top cover hoist in the top cover storage room, and a top cover alignment device for real-time qualitative monitoring of the offset between the top cover aperture and the guide post.

[0011] Step S1 includes:

[0012] Step S11: Install the top cover ladder on the top cover so that workers can reach the top of the top cover via the top cover ladder, and then use a hoist to connect it to the top of the top cover;

[0013] Step S12: The worker leaves the top of the roof and removes the roof ladder;

[0014] Step S13: Install the top cover waterproof cover, the top cover support device, and the top cover centering device onto the top cover.

[0015] In some embodiments, the top cover support device includes a plurality of support mechanisms, each of the support mechanisms including a support rod, a hook assembly, and a top cover support column;

[0016] In step S13, the top cover support device is installed as follows: several support mechanisms are evenly arranged along the circumferential direction of the top cover, the hook assembly is sleeved on the first end of the support rod for hooking in the light hole of the top cover, and the top cover support column is rotatably connected to the second end of the support rod for supporting between the top cover and the reactor pressure vessel.

[0017] In some embodiments, step S2 includes:

[0018] Step S21: After the reactor begins to drain water, install the sluice gate when the water level reaches the first preset height;

[0019] Step S22: When the water level reaches the second preset level, inspect the sealing surface of the reactor pressure vessel for defects.

[0020] Step S23: Lift the top cover to above the reactor pressure vessel, and lower the top cover with the water level to above the guide column;

[0021] Step S24: Use the top cover alignment device to align the top cover with the guide post, determine the offset direction of the light hole corresponding to the top cover relative to the guide post, and then lower the top cover and let it enter the guide post.

[0022] In some embodiments, the top cover centering device includes an auxiliary centering mechanism, which includes a housing, a rotating assembly, a camera, and a lens assembly. The rotating assembly is disposed in the housing, and the lens assembly is disposed on the rotating assembly, so that the rotating assembly drives the lens assembly to move, thereby making the lens of the camera correspond to the lens assembly. The lens assembly includes a plurality of camera lenses.

[0023] In step S24, the method for determining the offset direction of the light hole corresponding to the top cover relative to the guide post is as follows: using several camera lenses to qualitatively monitor the offset between the light hole of the top cover and the guide post in real time, and comparing the offset distance between the guide post and the center of the light hole of the top cover through the image captured by the camera, thereby determining the offset direction of the light hole corresponding to the top cover relative to the guide post.

[0024] In some embodiments, the auxiliary centering mechanism further includes a plurality of laser line lights;

[0025] In step S24, the distance between the top cover and the guide post is determined by observing the position of the light emitted by the laser line lamps, so as to avoid the guide post from hitting the reactor if the alignment is not completed.

[0026] In some embodiments, the number of laser line lights is three, which are divided into a first laser light, a second laser light, and a third laser light;

[0027] In step S24, the installation method of the plurality of laser line lights is as follows:

[0028] The first laser lamp is mounted on the upper side of the flange surface of the top cover, and the horizontal light emitted by it represents the horizontal height of the upper side of the flange surface of the top cover;

[0029] The second laser lamp is installed on the lower side of the flange face of the top cover, and the horizontal light emitted by it represents the horizontal height of the lower side of the flange face of the top cover;

[0030] The third laser light is mounted on a telescopic rod located on the reactor. The position of the third laser light is adjusted by the telescopic rod, and the horizontal light emitted by it represents the height of the guide column.

[0031] In some embodiments, step S3 includes:

[0032] Step S31: Position the top cover support device in place to support the top cover;

[0033] Step S32: Conduct a foreign object inspection of the reactor core sealing surface;

[0034] Step S33: Use the lifting device to lift the top cover, then remove the top cover support device, then use the lifting device to lower the top cover until the top cover is located in the reactor pressure vessel, and then completely remove the top cover support device.

[0035] Step S34: Remove the plug from the reactor main threaded hole and use the reactor main threaded hole cleaning and lubrication tool to clean the leaking water and residue from the main threaded hole.

[0036] In some embodiments, the reactor main bore cleaning and lubrication tool includes a foreign object removal device, an oiling device, and a suction device.

[0037] Step S34 includes:

[0038] Step S341: Use the foreign object removal device to remove the foreign object from the main screw hole;

[0039] Step S342: Apply oil to the main threaded hole using the oiling device;

[0040] Step S343: Use the suction device to clean the residual water in the main screw hole.

[0041] In some embodiments, in step S4, while removing the lifting device, the ropes provided on the top cover waterproof cover are opened and the position of the ropes is adjusted so that the top cover waterproof cover unfolds downward under its own weight and wraps around the top cover.

[0042] After the top cover waterproof cover is fully opened, check that the top cover waterproof cover has covered the gap between the top cover and the reactor pressure vessel.

[0043] In some embodiments, the method further includes the following after step S4:

[0044] Step S5: Decontaminate the water pool;

[0045] Step S6: Remove the top cover waterproof cover;

[0046] Step S7: Inspect the screw hole and guide post, and remove the screw hole plug and guide post.

[0047] The implementation of this invention has the following beneficial effects: The reactor pressure vessel top cover installation method avoids the subsequent removal of the dummy head by first installing auxiliary tools in step S1, and lifts the top cover after the reactor has finished loading and started draining, followed by foreign object inspection and debugging of the top cover waterproof cover. This allows for a final foreign object inspection before the top cover is in place, solving the problems of high risk and long construction period in the existing top cover process. It is also beneficial for the decontamination work of the reactor core water pool after the top cover is in place. At the same time, by replacing the dummy head with the top cover, the personnel dosage can be reduced to a certain extent, thereby improving efficiency and reducing personnel risks in safe production. Attached Figure Description

[0048] To more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort. In the drawings:

[0049] Figure 1 This is a schematic diagram of the steps of the reactor pressure vessel top cover installation method in some embodiments of the present invention;

[0050] Figure 2 This is a three-dimensional structural diagram of the top cover in some embodiments of the present invention;

[0051] Figure 3 This is a three-dimensional structural schematic diagram of the top cover support device in some embodiments of the present invention;

[0052] Figure 4 This is a three-dimensional structural schematic diagram of the top cover ladder in some embodiments of the present invention;

[0053] Figure 5 This is a three-dimensional structural schematic diagram of the top cover centering device in some embodiments of the present invention;

[0054] Figure 6 This is a schematic diagram of the internal structure of the top cover centering device in some embodiments of the present invention;

[0055] Figure 7 This is a three-dimensional structural schematic diagram of the foreign object removal device in some embodiments of the present invention;

[0056] Figure 8 This is a cross-sectional structural schematic diagram of the foreign object removal device in some embodiments of the present invention;

[0057] Figure 9 This is a three-dimensional structural schematic diagram of the oiling device in some embodiments of the present invention;

[0058] Figure 10This is a cross-sectional structural schematic diagram of the oiling device in some embodiments of the present invention;

[0059] Figure 11 This is a three-dimensional structural schematic diagram of the suction device in some embodiments of the present invention. Detailed Implementation

[0060] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the orientations or positional relationships indicated by terms such as "front," "rear," "upper," "lower," "left," "right," "longitudinal," "horizontal," "vertical," "horizontal," "top," "bottom," "inner," "outer," "head," and "tail" are based on the orientations or positional relationships shown in the accompanying drawings, and are constructed and operated in a specific orientation. They are only for the convenience of describing this technical solution and do not indicate that the device or element referred to must have a specific orientation; therefore, they should not be construed as limitations on this invention.

[0061] It should also be noted that, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "linking," "fixing," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. When an component is referred to as being "on" or "below" another component, the component can be located "directly" or "indirectly" on the other component, or there may be one or more intermediary components. The terms "first," "second," "third," etc., are only for the convenience of describing this technical solution and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0062] Please see Figures 2 to 11 This is a reactor pressure vessel top cover installation device in some embodiments of the present invention, used for installing the reactor pressure vessel top cover after fuel loading in a pressurized water reactor nuclear power plant. The reactor has a reactor water pool and guide columns. The reactor pressure vessel top cover installation device includes auxiliary tools pre-installed on the top cover 1 and reactor main thread hole cleaning and lubrication tool 6 for cleaning the reactor main thread hole.

[0063] In this embodiment, as Figure 1As shown, a method for installing the reactor pressure vessel top cover was also constructed. This method selects the process flow from fuel loading and drainage to the placement of the reactor pressure vessel top cover in the reactor core, improving the existing process of installing a dummy head after fuel loading. In the old process, the dummy head was used only to seal the reactor pressure vessel and shield the dose to facilitate subsequent work, and ultimately it still needed to be replaced with the reactor top cover 1. Analysis of the structure and shielding effect of the top cover 1 shows that it can replace the dummy head to achieve the same function; therefore, the use of the dummy head is actually a transitional operation. Using a dummy head to place the reactor core, the dummy head needs to be removed after the core work is completed, but removing the dummy head takes a lot of time. If the top cover 1 is installed directly, the subsequent removal of the dummy head will be avoided, resulting in a direct benefit of shortening the construction period. Moreover, core work is mostly high-dose work; considering that the shielding effect of the dummy head is worse than that of the top cover 1, if the top cover 1 can be used instead of the dummy head for shielding, the personnel dose can be reduced to a certain extent. The method of using the reactor pressure vessel top cover installation improves efficiency, reduces dosage, and lowers personnel risk in safe production.

[0064] The method for installing the reactor pressure vessel top cover includes the following steps:

[0065] Step S1: Install the auxiliary tools onto the top cover 1. The auxiliary tools include a top cover support device 2 for supporting the top cover on the pressure vessel and a top cover waterproof cover for protecting the top cover from the decontamination work in the reactor water pool. The auxiliary tools are installed onto the top cover 1 before the fuel loading is completed, which is the loading of brand-new nuclear fuel assemblies into the reactor pressure vessel.

[0066] Furthermore, the auxiliary tool also includes a top cover ladder 4 for enabling workers to detach and reconnect the top cover hoist in the top cover storage room, and a top cover alignment device 5 for real-time qualitative monitoring of the offset between the top cover aperture and the guide post.

[0067] Step S1 specifically includes:

[0068] Step S11: Install the top cover ladder 4 on the top cover so that workers can reach the top of the top cover through the top cover ladder 4, and then use a hoist to connect it to the top of the top cover 1;

[0069] Step S12: Workers leave the top of the cover 1 and remove the cover ladder 4;

[0070] Step S13: Install the top cover waterproof cover, top cover support device 2 and top cover centering device 5 onto the top cover 1.

[0071] Specifically, such as Figure 4As shown, the top ladder 4 includes several slide components 41, fall arrestor rope components 42, and support components 43. Each slide component 41 is movably connected to each other. The fall arrestor rope component 42 is connected to the slide component 41 to prevent the top ladder 4 from falling. The support component 43 is connected to the slide component 41 to provide fixed support for the slide component 41. The slide components 41 are movably connected to each other. The fall arrestor rope component 42 is connected to one of the outermost slide components 41 to prevent the top ladder 4 from falling. The support component 43 is connected to the other outermost slide component 41 to provide fixed support for the slide component 41. The outermost slide components are positioned opposite each other.

[0072] Specifically, in this embodiment, the slide assembly 41 has three levels: a first slide assembly 411, a second slide assembly 412, and a third slide assembly 413. The second slide assembly 412 is retractable relative to the first slide assembly 411, and the third slide assembly 413 is retractable relative to the second slide assembly 412. A support assembly 43 is connected to one end of the first slide assembly 411, and a fall arrestor rope assembly 42 is connected to the end of the third slide assembly 413 opposite to the support assembly 43. This top cover ladder 4 can be used in the top cover storage room to allow workers to access the working platform of the top cover 1 lifting device when the top cover 1 lifting device is hooked to the ring crane.

[0073] The top cover ladder 4 is installed and removed within the top cover storage room, not within the water storage tank. The top cover ladder 4 is simple and lightweight, easy to install and remove, and its interface dimensions meet environmental requirements. The support component 43 ensures worker safety. The top cover ladder 4 is designed to attach to the guardrail of the top cover of the storage room and extends downwards to the top cover 1 lifting device, with a height difference of approximately 5 meters. The top cover ladder 4 also features a guardrail component for securing the top of the ladder to the guardrail, and a fall arrestor rope component 42 to ensure worker safety when ascending and descending. When the lifting device of the top cover 1 needs to be connected, workers must install the top cover ladder 4 in the top cover storage room beforehand. After workers reach the lifting device platform of the top cover 1, complete the hook connection, and withdraw from the lifting device platform, the top cover ladder 4 is then removed.

[0074] Furthermore, in step S13, the waterproof cover, the support device 2, and the centering device 5 are installed on the top cover 1 in advance while the top cover 1 is still in the top cover storage room. After the lifting device is connected to the top cover 1, the waterproof cover, the support device 2, and the centering device 5 are lifted together with the top cover 1 to the reactor core. The installation of these three special tools will not affect the lifting work of the top cover 1.

[0075] In this embodiment, in step S13, the top cover support device 2 is installed as follows: several support mechanisms are evenly arranged along the circumferential direction of the top cover 1, the hook assembly 22 is sleeved on the first end of the support rod 21 for hooking in the light hole of the top cover 1, and the top cover support column 23 is rotatably connected to the second end of the support rod 21 for supporting between the top cover 1 and the reactor pressure vessel.

[0076] Specifically, it should be like this Figure 3 As shown, the top cover support device 2 includes several support mechanisms, which are evenly arranged along the circumferential direction of the top cover 1. Each support mechanism includes a support rod 21, a hook assembly 22, and a top cover support column 23. The support rod 21 is arranged parallel to the axial direction of the top cover 1. The hook assembly 22 is sleeved on the first end of the support rod 21 and is used to hook into the light hole 11 of the top cover 1. The top cover support column 23 is rotatably connected to the second end of the support rod 21 and is used to support between the top cover 1 and the reactor pressure vessel.

[0077] Understandably, the top cover support column 23 can be rotated relative to the support rod 21 and inserted between the reactor pressure vessel and the top cover 1, or rotated out from between the reactor pressure vessel and the top cover 1 relative to the support rod 21 to the outside of the top cover 1. The support rod 21 is cylindrical. In this embodiment, the top cover support device 2 consists of three units evenly distributed around the top cover 1, according to the weight of the top cover 1 and the needs of on-site work. Each support rod 21 is installed between two adjacent light holes 11 of the top cover 1, and the height of the support rod 21 is approximately equal to the thickness of the top cover 1. The top cover support column 23 is cylindrical, can move up and down along the support rod 21, and can be manually locked.

[0078] Furthermore, the first end of the support rod 21 is provided with a first locking position and a second locking position. The hook assembly 22 moves along the axial direction of the support rod 21 between the first locking position and the second locking position. When the hook assembly 22 is in the first locking position, the top cover support column 23 is supported between the top cover 1 and the reactor pressure vessel. When the hook assembly 22 is in the second locking position, the top cover support column 23 rotates relative to the support rod 21 to the outside of the top cover 1. It can be understood that when the top cover support device 2 is not in the position, the top cover support column 23 rotates along the support rod 21 to the outside of the top cover 1, and the hook assembly 22 is in the second locking position and locked. When the top cover support device 2 needs to be in the position, the hook assembly 22 unlocks from the second locking position to the first locking position, so that the top cover support column 23 is supported between the top cover 1 and the reactor pressure vessel, and the hook assembly 22 is locked in the first locking position, so that the top cover support device 2 is in the position.

[0079] Step S2 of the reactor pressure vessel top cover installation method is as follows: after the reactor has finished loading and started draining, the top cover 1 is lifted to the top of the reactor pressure vessel using a lifting device, so that the top cover 1 is kept above the water surface of the reactor pool.

[0080] Step S2 specifically includes: Step S21: After the reactor begins to drain water, when the water level reaches the first preset water level, a sluice gate is installed. Specifically, step S21 is: after the reactor begins to drain water, when the water level reaches the first preset water level, a sluice gate is installed. In step S21, the first preset water level is the height of the water surface in the reactor pool, which is preferably 10.862 meters. The step of installing the sluice gate mainly refers to the fact that after the reactor pool drains water to a height of 10.862 meters, decontamination work needs to be carried out in the reactor pool to facilitate subsequent work. If decontamination is not carried out, there may be hot spots. At this time, the water in the reactor pool has not been completely drained. According to the technical specifications, a sluice gate needs to be installed.

[0081] Step S22: When the water level reaches the second preset level, a defect inspection of the reactor pressure vessel's sealing surface is performed. Specifically, step S22 involves: when the water level reaches the second preset level, a defect inspection of the reactor pressure vessel's sealing surface is performed. In step S22, since the core sealing surface is the most important and largest sealing surface of the reactor, a defect inspection of the sealing surface is necessary to ensure its normal operation before reloading the top cover 1 and the subsequent safe operation of the unit. This defect inspection and handling is performed during the low water level period before fuel loading, thus avoiding the use of critical path time and generating benefits. After the defect inspection of the sealing surface is completed during the low water level period, a dedicated protection device is installed on the core sealing surface. After the core sealing surface protection device is removed, the operation of draining the reactor water pool and lowering the top cover 1 begins.

[0082] Step S23: Lift the top cover 1 above the reactor pressure vessel, and lower the top cover 1 as the water level descends to above the guide column.

[0083] Step S24: Use the top cover centering device 5 to center the top cover 1 with the guide post, determine the offset direction of the light hole corresponding to the top cover 1 relative to the guide post, and then lower the top cover 1 and let it enter the guide post.

[0084] The top cover alignment device 5 has been manually installed onto the top cover 1 in step S13. The top cover alignment device 5 is used to allow the staff to remotely visually observe the alignment of the top cover 1 with the guide column when the water level of the top cover 1 drops with the water level of the water storage pool, and to guide the adjustment of the alignment between the top cover 1 and the guide column.

[0085] More specifically, in step S24, the method for determining the offset direction of the light hole corresponding to the top cover 1 relative to the guide post is as follows: using several camera lenses 5131 to qualitatively monitor the offset between the light hole of the top cover 1 and the guide post in real time, and comparing the offset distance between the guide post and the center of the light hole of the top cover 1 through the image captured by the camera, thereby determining the offset direction of the light hole corresponding to the top cover 1 relative to the guide post.

[0086] For example Figure 5 and Figure 6 As shown, the top cover alignment device 5 includes an auxiliary alignment mechanism 51 and a control mechanism communicatively connected to the auxiliary alignment mechanism 51. The auxiliary alignment mechanism 51 includes a housing 511, a rotating assembly 512, a camera, and a lens assembly 513. The housing 511 is detachably installed in the light hole 11 of the top cover 1 via a clamping mechanism 514. The rotating assembly 512 is disposed inside the housing 511 and rotatably connected to the housing 511. The lens assembly 513 is disposed on the rotating assembly 512. The rotating assembly 512 rotates relative to the housing 511 to drive the lens assembly 513 to rotate, thereby aligning the camera lens with the lens assembly 513. The clamping mechanism 514 is preferably a three-jaw chuck clamping mechanism. Specifically, when the top cover 1 needs to be installed on the reactor pressure vessel, two three-jaw chuck clamping mechanisms located at the bottom of the housing 511 are respectively installed above the light hole 11 of the top cover 1. The rotating assembly 512 is used to adjust the lens assembly 513 so that the camera lens aligns with the lens assembly 513.

[0087] Furthermore, since the top cover 1 will descend into the reactor core with the drainage, and because the core contains water throughout the process, crane personnel cannot descend into the core for visual alignment. Therefore, remote alignment tools must be used, and can only be used. Any malfunction of the alignment tools will directly affect the alignment work, and consequently, the critical path. Figure 6 As shown, the lens assembly 513 includes three camera lenses 5131, which can be divided into a reflector 51311, a first lens 51312, and a second lens 51313. All three camera lenses 5131 are mounted on a right-angle bracket 515 connected to the rotating assembly 512. The reflector 51311 is mounted on the hypotenuse of the right-angle bracket 515, the first lens 51312 is mounted on one right-angle side of the right-angle bracket 515, and the second lens 51313 is mounted on the other right-angle side of the right-angle bracket 515. The light emitted by the camera passes sequentially through the second lens 51313, the reflector 51311, and the first lens 51312 before illuminating the light hole 11 on the reactor top cover.

[0088] This setup allows the top cover alignment device 5 to simultaneously and qualitatively monitor the offset between the light aperture 11 on the top cover 1 and the guide post in real time using three camera lenses 5131. By comparing the offset distances between the three guide posts and the center of the light aperture 11 on the top cover 1 using images captured by the cameras, the device determines the offset direction of the corresponding light aperture 11 on the top cover 1 relative to the guide post, providing guidance for subsequent steps. Understandably, this top cover alignment device 5 uses three independent camera lenses 5131; a failure of one camera lens 5131 will not affect the other two, and it is easy to replace. The camera sends the captured images to the control mechanism, and the operator adjusts the position of the top cover 1 based on the captured images so that the light aperture 11 on the top cover 1 corresponds to the position of the guide post inside the reactor pressure vessel, ensuring that the guide post is inserted into the corresponding light aperture 11. This reduces industrial safety and radiation protection risks and improves work efficiency.

[0089] Meanwhile, the top cover alignment device 5 also features human-computer interaction functions such as image capture and video saving on a handheld terminal. This handheld terminal is a portable mobile device with multiple functions including data acquisition, data transmission, and data processing. Operators can use this handheld terminal to perform functions such as wireless signal reception, video monitoring, and alignment instruction. Specifically, the control mechanism includes a wireless transceiver and a display controller. The wireless transceiver receives image signals from the camera, and the display controller has a video display for video monitoring and indicating the alignment operation between the top cover 1 and the guide column. The control mechanism can also be equipped with a single shoulder strap to reduce hand strain and facilitate operation. The control mechanism and the auxiliary alignment mechanism 51 can communicate via both wireless and wired connections. Wireless communication is achieved through the wireless transceiver, while the wired communication uses a 25m long network cable with an aviation connector. The connection between the control mechanism and the auxiliary alignment mechanism 51 uses an aviation plug. The internal connections of each independent device are designed using bayonet or bolt connections.

[0090] In step S24, the distance between the top cover 1 and the guide post is determined by observing the position of the light emitted by the laser lights, so as to avoid the guide post from hitting the reactor before alignment is completed. More specifically, the auxiliary alignment mechanism 51 also includes a plurality of laser lights and a magnetic mechanism. The plurality of laser lights are set on the housing 511 by the magnetic mechanism, so that the distance between the top cover 1 and the guide post can be determined by observing the position of the light emitted by the laser lights, thus preventing the guide post from hitting the reactor before alignment is completed.

[0091] Preferably, there are three laser beam lights, namely a first laser light, a second laser light, and a third laser light. In step S24, the laser beam lights are installed as follows: the first laser light is installed on the upper side of the flange surface of the top cover 1, and the horizontal light emitted by it represents the horizontal height of the upper side of the flange surface of the top cover 1; the second laser light is installed on the lower side of the flange surface of the top cover 1, and the horizontal light emitted by it represents the horizontal height of the lower side of the flange surface of the top cover 1; the third laser light is installed on the telescopic rod located on the reactor, and the position of the third laser light is adjusted by the telescopic rod, and the horizontal light emitted by it represents the height of the guide column. Workers can judge the distance between the top cover 1 and the guide column by observing the position of the light beams, thus avoiding the guide column from hitting the flange surface of the top cover if alignment is not completed.

[0092] Specifically, step S3 involves: after positioning the top cover support device 2 in the reactor pressure vessel, performing a foreign object inspection, and then positioning the top cover 1 in the reactor pressure vessel. This step specifically includes:

[0093] Step S31: Position the top cover support device 2 to support the top cover 1. In step S31, since the diameter of the top cover 1 is larger than the dummy head, if the top cover 1 is directly placed into the reactor core, it will cover the core sealing surface, making core sealing surface inspection impossible. Therefore, a reliable top cover support needs to be developed when the top cover 1 approaches the core sealing surface before being placed into the core. Using the top cover support device 2 to support the top cover 1 allows personnel to quickly perform core sealing surface inspection. This top cover support device 2 is used to support the top cover 1 on the reactor pressure vessel to the specified height required for some of the work. After the work is completed, the top cover support device 2 is removed, and the top cover 1 can continue to fall onto the reactor pressure vessel.

[0094] Understandably, when the top cover 1 falls close to the reactor pressure vessel, since the top cover support device 2 is installed below the top cover 1, the top cover support device 2 will contact the reactor pressure vessel before the top cover 1. After the top cover support device 2 contacts the reactor pressure vessel, it will support the top cover 1, so that the top cover 1 is about 0.5m away from the reactor pressure vessel at a specified height. At this time, the ring crane is not removed.

[0095] Step S32: Perform foreign object prevention inspection on the reactor core sealing surface; In step S32, after the top cover 1 is supported by the top cover support device 2 on the reactor pressure vessel by about 0.5m, the personnel can begin the foreign object prevention inspection on the core sealing surface. The sealing surface defect inspection is performed during the low water level period before fuel loading, but is not performed in step S22. Only the foreign object prevention inspection is performed after fuel loading, saving process time and optimizing the workflow.

[0096] Step S33: Use a lifting device to lift the top cover 1, then remove the top cover support device 2, and then use the lifting device to lower the top cover 1 until it is located in the reactor pressure vessel. Then, completely remove the top cover support device 2. Specifically, after the foreign object inspection is completed, the lifting device will slowly lift the top cover 1 to a suitable distance, and the personnel can withdraw the top cover support device 2. At this time, only the top cover support device 2 is withdrawn from its current position so that it does not affect the top cover 1's continued descent into the reactor pressure vessel. The connection between the top cover 1 and the top cover support device 2 is not completely removed to prevent the top cover 1 from being supported by the top cover support device 2 in case of other accidents during the continued descent. While the top cover support device 2 is in the withdrawn state, the lifting device continues to lower the top cover 1 until it is located in the reactor pressure vessel. At this point, the connection between the top cover support device 2 and the top cover 1 can be completely removed.

[0097] Step S34: Remove the reactor main threaded hole plug and use the reactor main threaded hole cleaning and lubrication tool 6 to clean any leaking water and residue from the main threaded hole. In step S34, see... Figures 7 to 11 Since water leakage is found during subsequent bolt hole inspections after the top cover 1 is in place of the reactor pressure vessel, it is difficult to clean the accumulated water without special tools due to the thickness of the top cover 1 flange. Therefore, a special tool needs to be designed to clean and lubricate the bolt holes after the top cover 1 is in place. The reactor main bolt hole cleaning and lubrication tool 6 is used to clean water leakage or residual foreign matter in the main bolt holes after the top cover 1 is fully in place of the reactor pressure vessel and the reactor bolt hole plugs are removed. The reactor main bolt hole cleaning and lubrication tool 6 includes a foreign matter removal device 61, an oiling device 62, and a suction device 63.

[0098] Step S34 includes: Step S341: Remove foreign objects from the main threaded hole using the foreign object removal device 61; Step S342: Apply oil to the main threaded hole using the oiling device 62; Step S343: Clean the residual water in the main threaded hole using the suction device 63.

[0099] Specifically, after the reactor is in place on the reactor pressure vessel and the bolt hole plug is removed, due to the thickness of the reactor top cover flange 1, it is difficult to directly remove foreign objects if they are present in the main bolt hole. Therefore, a foreign object removal device 61 needs to be designed and developed. To facilitate the clamping operation, such as... Figure 7 and Figure 8As shown, the foreign object removal device 61 includes a connecting rod 611 extending into the main screw hole, a clamping assembly 612 on the first end of the connecting rod 611 for gripping residue in the hole, a driving part 613 on the second end of the connecting rod 611, a connecting piece 614 passing through the connecting rod 611 and connecting the clamping assembly 612 and the driving part 613, and a lighting lamp 615 on the connecting rod 611. The clamping assembly 612 includes a driven part 6121 connected to the connecting piece 614 and two grippers 6122 drivenly connected to the driven part 6121. The driving part 613 drives the driven part 6121 back and forth through the connecting piece 614 to open or close the two grippers 6122. The grippers 6122 and the driven part 6121 can engage through teeth or abut against each other through guide surfaces, so that the driven part 6121 moves while simultaneously driving the two grippers 6122 to rotate in opposite directions. Preferably, the gripper 6122 is made of magnetic material and can attract some metallic substances. The foreign object removal device 61 is also equipped with a light 615 to facilitate the search and positioning of foreign objects.

[0100] like Figure 9 and Figure 10 As shown, the oiling device 62 includes a positioning sleeve 621, an operating rod 622, an operating part 623, a brush head assembly 624, and a linkage 625. The operating rod 622 is rotatably connected to the positioning sleeve 621, and the end of the operating rod 622 away from the positioning sleeve 621 is fixedly connected to the operating part 623, so that the operating part 623 can drive the operating rod 622 to rotate. The brush head assembly 624 includes a brush head positioning rod and a brush connected to the brush head positioning rod. One end of the brush head positioning rod is located inside the positioning sleeve 621, and the linkage 625 is fixedly connected to the operating rod 622, so that when the operating rod 622 rotates in its circumferential direction, it drives the linkage 625 to move, thereby causing the brush head positioning rod to extend outward or retract inward. It can be understood that the oiling device 62 is used to re-oil the screw hole after the screw hole plug has failed. When the oiling device 62 is used to treat the screw hole, the brush head assembly 624 is inserted into the screw hole. Rotating the operating part 623 can drive the operating rod 622 to rotate, thereby driving the brush head assembly 624 to move. When it extends outward, it can apply oil to lubricate the screw hole. When it retracts inward, it can be removed from the screw hole.

[0101] like Figure 11 As shown, the suction device 63 includes a suction rod 631 for contacting residual water in the screw hole and a suction device 632 connected to the suction rod 631. The suction rod 631 can be inserted into the screw hole by an external mechanism or manually to suction the residual water in the screw hole. It can be understood that the suction device 63 is used to clean the residual water that has entered the screw hole after the screw hole plug fails. It is convenient and quick, and reduces the influence of dosage.

[0102] Furthermore, the reactor pressure vessel top cover installation method also includes step S4: dismantling the lifting equipment and adjusting the top cover waterproof cover. Specifically, in step S4, while dismantling the lifting equipment, the ropes on the top cover waterproof cover are opened and the position of the ropes is adjusted so that the top cover waterproof cover unfolds downwards under its own weight and wraps around the top cover 1. After the top cover waterproof cover is fully opened, it is checked that the top cover waterproof cover has covered the gap between the top cover 1 and the reactor pressure vessel. This top cover waterproof cover is a disposable special tool used to protect the top cover 1 from the decontamination work in the reactor water pool. It is installed starting from the top of the top cover 1 and fixed around the top cover 1 guardrail. The fixed and installed top cover waterproof cover will completely cover all parts of the top cover 1 from top to bottom and play a protective role for the top cover 1. The top cover waterproof cover is installed around the top guardrail of the top cover 1 in the top cover storage room. When in the top cover storage room, the waterproof cover is in a retracted state. When needed, it can be simply opened to cover the top cover 1 from top to bottom.

[0103] Specifically, the waterproof cover is used in step S4 as follows: the waterproof cover is opened and covers the top cover 1. While the lifting equipment for the top cover 1 is being removed, the rope used to retract the waterproof cover can be opened. After opening, the waterproof cover will unfold downwards under its own weight and wrap around the top cover 1. Since the outer surface of the top cover 1 is not flat, the waterproof cover may not cover the top cover 1 completely in one go during this process. A traction rope is set for the waterproof cover, and the staff adjusts it to ensure that the waterproof cover finally completely covers the top cover 1. After the waterproof cover is fully opened, it is important to check whether the waterproof cover has covered the gap between the top cover 1 and the reactor pressure vessel.

[0104] The process includes the following steps after step S4: step S5: cleaning the water tank; step S6: removing the top cover waterproof cover; step S7: inspecting the screw holes and guide posts, and removing the screw hole plugs, guide posts, and top cover centering device 5.

[0105] In step S5, the decontamination of the water storage tank is mainly to clean the water storage tank, reduce the dosage level and hot spots in the water storage tank, and ensure the safe operation of subsequent water storage tank work.

[0106] In step S6, after the cleaning is completed, the top waterproof cover can be removed directly to facilitate subsequent work.

[0107] In step S7, the inspection of the screw holes and guide posts is optimized and moved to the subsequent work after removing the top cover waterproof cover, and is carried out in parallel with the removal of the guide posts and screw hole plugs. If the screw holes do not leak, no additional processing time is required; if the screw holes leak, additional processing time is required. At the same time, the top cover centering device 5 is removed.

[0108] Understandably, this reactor pressure vessel top cover installation method solves the problems of high risk and long construction period in the existing cover-closing process. Based on the development of new tools, optimizations and improvements can be made to the use of special tools and procedures in the cover-closing process, thereby developing a complete new process. The optimized new process can achieve considerable benefits in terms of construction period and total dosage compared to the old process, and has great promotional value. It reduces personal risks while also bringing benefits to the power plant.

[0109] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for installing the top cover of a reactor pressure vessel, characterized in that, Including the following steps: Step S1: Pre-install auxiliary tools onto the top cover (1), the auxiliary tools including a top cover support device (2) for supporting the top cover on the pressure vessel and a top cover waterproof cover for protecting the top cover from the decontamination work of the water tank; Step S2: After the reactor has finished loading and started draining, use a lifting device to lift the top cover (1) to the top of the reactor pressure vessel, so that the top cover (1) is kept above the water surface of the reactor pool. Step S3: After the top cover support device (2) is positioned in the reactor pressure vessel, a foreign object prevention check is performed, and then the top cover (1) is positioned in the reactor pressure vessel. Step S4: Remove the lifting equipment and test the top waterproof cover; The auxiliary tools also include a top cover ladder (4) for enabling workers to detach and reconnect the top cover hoist in the top cover storage room, and a top cover alignment device (5) for real-time qualitative monitoring of the offset between the top cover aperture and the guide post. Step S1 includes: Step S11: Install the top cover ladder (4) on the top cover (1) so that workers can reach the top of the top cover (1) through the top cover ladder (4) and then use a hoist to connect to the top of the top cover (1); Step S12: The worker leaves the top of the cover (1) and removes the cover ladder (4). Step S13: Install the top cover waterproof cover, the top cover support device (2) and the top cover centering device (5) onto the top cover (1).

2. The reactor pressure vessel top cover installation method according to claim 1, characterized in that, The top cover support device (2) includes several support mechanisms, each of which includes a support rod (21), a hook assembly (22), and a top cover support column (23). In step S13, the top cover support device (2) is installed in the following manner: several support mechanisms are evenly arranged along the circumferential direction of the top cover (1), the hook assembly (22) is sleeved on the first end of the support rod (21) for hooking in the light hole of the top cover (1), and the top cover support column (23) is rotatably connected to the second end of the support rod (21) for supporting between the top cover (1) and the reactor pressure vessel.

3. The reactor pressure vessel top cover installation method according to claim 1, characterized in that, Step S2 includes: Step S21: After the reactor begins to drain water, install the sluice gate when the water level reaches the first preset height; Step S22: When the water level reaches the second preset level, inspect the sealing surface of the reactor pressure vessel for defects. Step S23: Lift the top cover (1) above the reactor pressure vessel, and lower the top cover (1) above the guide column as the water level drops; Step S24: Use the top cover centering device (5) to center the top cover (1) with the guide post, and determine the offset direction of the light hole corresponding to the top cover (1) relative to the guide post, and then lower the top cover (1) and enter the guide post.

4. The reactor pressure vessel top cover installation method according to claim 3, characterized in that, The top cover centering device (5) includes an auxiliary centering mechanism (51). The auxiliary centering mechanism (51) includes a housing (511), a rotating component (512), a camera, and a lens assembly (513). The rotating component (512) is disposed in the housing (511), and the lens assembly (513) is disposed on the rotating component (512) so that the rotating component (512) drives the lens assembly (513) to move, thereby making the lens of the camera correspond to the lens assembly (513). The lens assembly (513) includes a plurality of camera lenses (5131). In step S24, the method for determining the offset direction of the light hole corresponding to the top cover (1) relative to the guide post is as follows: the offset between the light hole of the top cover (1) and the guide post is qualitatively monitored in real time using several camera lenses (5131), and the offset distance between the guide post and the center of the light hole of the top cover (1) is compared with the image captured by the camera to determine the offset direction of the light hole corresponding to the top cover (1) relative to the guide post.

5. The reactor pressure vessel top cover installation method according to claim 4, characterized in that, The auxiliary centering mechanism (51) also includes several laser line lights; In step S24, the distance between the top cover (1) and the guide post is determined by observing the position of the light emitted by the laser line lamps, so as to avoid the guide post from hitting the reactor when the alignment is not completed.

6. The reactor pressure vessel top cover installation method according to claim 5, characterized in that, The number of laser line lights is three, which are divided into a first laser light, a second laser light, and a third laser light; In step S24, the installation method of the plurality of laser line lights is as follows: The first laser lamp is installed on the upper side of the flange surface of the top cover (1), and the horizontal light emitted by it represents the horizontal height of the upper side of the flange surface of the top cover (1); The second laser lamp is installed on the lower side of the flange face of the top cover (1), and the horizontal light emitted by it represents the horizontal height of the lower side of the flange face of the top cover (1); The third laser light is mounted on a telescopic rod located on the reactor. The position of the third laser light is adjusted by the telescopic rod, and the horizontal light emitted by it represents the height of the guide column.

7. The reactor pressure vessel top cover installation method according to claim 1, characterized in that, Step S3 includes: Step S31: Position the top cover support device (2) in place to support the top cover (1); Step S32: Conduct a foreign object inspection of the reactor core sealing surface; Step S33: Use the lifting device to lift the top cover (1), then remove the top cover support device (2), then use the lifting device to lower the top cover (1) until the top cover (1) is located in the reactor pressure vessel, and then remove the top cover support device (2). Step S34: Remove the plug from the reactor's main threaded hole and use the reactor main threaded hole cleaning and lubrication tool (6) to clean the leaking water and residue from the main threaded hole.

8. The reactor pressure vessel top cover installation method according to claim 7, characterized in that, The reactor main bore cleaning and lubrication tool (6) includes a foreign object removal device (61), an oiling device (62), and a suction device (63). Step S34 includes: Step S341: Use the foreign object removal device (61) to remove the foreign object from the main screw hole; Step S342: Apply oil to the main threaded hole using the oiling device (62); Step S343: Use the suction device (63) to clean the residual water in the main screw hole.

9. The reactor pressure vessel top cover installation method according to claim 1, characterized in that, In step S4, while removing the lifting device, the rope straps on the top cover waterproof cover are opened and the position of the rope straps is adjusted so that the top cover waterproof cover unfolds downward under its own weight and wraps around the top cover (1). After the top cover waterproof cover is fully opened, check that the top cover waterproof cover has covered the gap between the top cover (1) and the reactor pressure vessel.

10. The reactor pressure vessel top cover installation method according to claim 7, characterized in that, The process after step S4 also includes: Step S5: Decontaminate the water pool; Step S6: Remove the top cover waterproof cover; Step S7: Inspect the screw holes and guide posts, and remove the screw hole plugs, guide posts and top cover centering device (5).

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