An underwater transfer system

Abstract

This invention discloses an underwater transfer system, including a transfer track, a transfer trolley, an emergency recovery mechanism, and a crane. The transfer track is laid in a transfer waterway, and the transfer trolley slides on the transfer track for transporting spent fuel between an unloading pool and a storage pool. The emergency recovery mechanism is located on a maintenance platform above the transfer waterway and connected to the transfer trolley, used to pull the transfer trolley along the transfer track towards the maintenance platform. The crane is located near the maintenance platform and is used to lift the transfer trolley from the transfer waterway to the maintenance platform for inspection and maintenance after the emergency recovery mechanism has pulled the transfer trolley to its limit position, and to lower the inspected and maintained transfer trolley back onto the transfer track. This invention enables the transport of spent fuel in the transfer waterway and features a simple structure, low failure rate, high reliability, and convenient inspection and maintenance.

Description

Technical Field

[0001] This invention belongs to the field of nuclear industry technology, and specifically relates to an underwater transfer system for transporting spent fuel in transfer waterways. Background Technology

[0002] Receiving and storing spent nuclear fuel is the first critical step in the spent fuel reprocessing plant. After the transport containers carrying spent fuel assemblies arrive at the reprocessing plant, they are decontaminated and then lifted by crane to the unloading pool. The spent fuel assemblies are then transferred via a transfer waterway to a storage pool for storage. Because the spent fuel assemblies still possess high levels of radioactivity, all transfer processes are conducted underwater.

[0003] The transfer channel is a crucial link between the unloading pool and the storage pool. It is typically long and narrow with a certain depth. Its bottom is either horizontal or has a slight slope (0°–20°). The spent fuel transfer system operates within the transfer channel, completing the transfer of spent fuel assemblies between the unloading pool and the storage pool.

[0004] Generally, due to the unique nature of underwater operations, current common spent fuel transfer systems utilize a wire rope traction system, consisting of drums and wire ropes installed above the water surface, to pull an underwater transfer vehicle in a reciprocating motion within the transfer channel, thus transporting spent fuel. However, due to the requirement for bidirectional movement of the transfer vehicle, the wire rope traction system has a complex structure, numerous potential failure points, a high failure rate, and poor reliability. If the transfer vehicle or traction system malfunctions (such as wire rope breakage, pulley damage, or bearing wear), repairs must be performed only after draining the water from the transfer channel and its connected pools. Given the large volume of water involved, this is neither costly nor efficient. Furthermore, the long, deep transfer channels, often containing residual radioactivity, present challenges for maintenance personnel in terms of both space and dosage, hindering repair and maintenance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an underwater transfer system that addresses the above-mentioned shortcomings of the existing technology. This system can realize the transportation of spent fuel in transfer waterways and has a simple structure, low failure rate, high reliability, and convenient maintenance.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is:

[0007] An underwater transfer system includes a transfer track, a transfer trolley, an emergency recovery mechanism, and a crane. The transfer track is laid in a transfer waterway, and the transfer trolley slides on the transfer track for transporting spent fuel between an unloading pool and a storage pool. The emergency recovery mechanism is located on a maintenance platform above the transfer waterway and is connected to the transfer trolley, used to pull the transfer trolley along the transfer track toward the maintenance platform. The crane is located near the maintenance platform and is used to lift the transfer trolley from the transfer waterway to the maintenance platform for inspection and maintenance after the emergency recovery mechanism has pulled the transfer trolley to its limit position, and to lower the inspected and maintained transfer trolley back onto the transfer track.

[0008] Preferably, the transfer trolley includes a body, support wheels, an underwater motor, and a sliding gear meshing assembly. The body is slidably mounted on the transfer track via the support wheels. Drive mounting seats are provided on both sides of the body. The underwater motor and the sliding gear meshing assembly are both mounted on the drive mounting seats. The output end of the underwater motor is connected to the sliding gear meshing assembly. A transmission rack is provided on the transfer track. The transmission rack and the sliding gear meshing assembly cooperate to form a meshing transmission structure. The underwater motor drives the sliding gear meshing assembly to mesh with the transmission rack on the transfer track, thereby driving the transfer trolley to move bidirectionally along the transfer track.

[0009] Preferably, the number of support wheels is two or more pairs, with a first wheel provided on the same side of each pair of support wheels and a second wheel provided on the other side of each pair of support wheels. The first wheel has a flared rim that can cooperate with the transfer track, and the second wheel is a cylindrical wheel.

[0010] Preferably, the sliding gear meshing assembly includes a mounting and fixing part, a bearing, a mounting and rotating part, a sliding transmission shaft, and a transmission gear. The mounting and fixing part is disposed on the drive mounting base, and the mounting and rotating part is movably embedded in the mounting and fixing part through the bearing. The mounting and rotating part has a sliding space. One end of the sliding transmission shaft is movably inserted into the sliding space and can rotate together with the mounting and rotating part. The transmission gear is disposed at the other end of the sliding transmission shaft and is adapted to the transmission rack to form the meshing transmission structure.

[0011] Preferably, the transmission rack is located on the outer side of the transfer track.

[0012] Preferably, the maximum length of the sliding space is greater than the width of the transmission rack.

[0013] Preferably, the crane is equipped with a special lifting device, which includes a hook, a main frame of the lifting device, and a guide beam. The shape of the main frame of the lifting device is adapted to the shape of the transfer trolley, and it covers the transfer trolley when it is lifted out. The hook is located at the bottom of the main frame of the lifting device and is used to connect the transfer trolley. The guide beam is located at the top of the main frame of the lifting device, and the crane's lifting rope is connected to the guide beam.

[0014] Preferably, the transfer trolley is equipped with a position monitoring sensor, which includes an encoder and a fixed-point induction sensor. The encoder is mounted on the underwater motor, and the fixed-point induction sensor is mounted on the trolley body, for real-time positioning and fixed-point stopping of the transfer trolley on the transfer track.

[0015] Preferably, the emergency recovery mechanism includes a winch, a pulley block, a counterweight, and a traction rope. The winch is mounted on the maintenance platform. The pulley block includes a redirecting pulley and a counterweight pulley. One end of the traction rope is fixed to the winch, and the other end passes around the counterweight pulley and the redirecting pulley before connecting to the transfer trolley to pull the transfer trolley below the maintenance platform. The counterweight pulley slides on the traction rope, and the counterweight is mounted on the counterweight pulley. When the transfer trolley moves on the transfer track, the counterweight pulley can drive the counterweight to move up and down together.

[0016] Preferably, the system further includes a guide groove, which is located on the path of the counterweight pulley's up-and-down movement. The counterweight block is located in the guide groove and can move up and down in the guide groove. An end limiting member is provided on the guide groove.

[0017] The underwater transfer system of the present invention has at least the following advantages compared with the prior art:

[0018] (1) By setting up a transfer trolley with its own power drive unit, it has a certain load capacity and movement capability. It can carry the spent fuel basket and load the spent fuel assembly and move on the transfer track, thereby realizing the transfer of the spent fuel assembly between the unloading pool and the storage pool connected by the transfer waterway.

[0019] (2) By setting up two sets of drive devices and sliding gear meshing components on the transfer trolley, it can mesh with the transmission rack on the transfer track to drive the transfer trolley. Compared with traditional technology, it has a simple structure, fewer fault points, lower failure rate, and less difficulty in inspection and maintenance.

[0020] (3) By setting up an emergency recovery mechanism and a crane, in the event of a malfunction, the operation can be carried out from the maintenance platform on the water. The malfunctioning and inoperable transfer trolley can be pulled back to the bottom of the maintenance platform and then lifted out to the maintenance platform for inspection and maintenance. After the inspection and maintenance work is completed, the crane can be used to return the transfer trolley to the transfer track. Compared with the existing technology, there is no need to drain water, which saves time and costs and increases the production line operating rate. There is also no need for staff to enter the transfer waterway or underwater for inspection and maintenance, which can protect staff from the dual threats of narrow space and ionizing radiation. It is both convenient and safe.

[0021] (4) By setting counterweight pulleys and counterweight blocks, the traction rope can always maintain a certain tension, and the traction rope can be prevented from becoming loose or stacked during the movement of the transfer trolley.

[0022] (5) By setting guide channels on both sides of the transfer waterway to limit the guide lifting beam, the positional deviation of the crane lifting device can be avoided, thereby improving the accuracy and stability of the lifting and lowering of the transfer trolley.

[0023] (6) By setting a sliding space, when the transmission gear and transmission rack of the transfer trolley are not in phase and are fully engaged, the transmission gear can be retracted under the reaction force of the transmission rack. This ensures that the transmission gear and transmission rack will not collide or obstruct each other before the transfer trolley is returned to the transfer track. After the transfer trolley is returned to the transfer track, the winch wire rope (i.e., traction rope) can be used to pull the transfer trolley to move slightly until the phase of the transmission rack and transmission gear is engaged. At this time, the transmission gear extends and meshes with the transmission rack, which can reduce the installation accuracy and failure rate.

[0024] (7) The components of this system, such as the transfer track, transfer trolley, and emergency recovery mechanism, are modularly designed. They are relatively independent in function, easy to combine and disassemble, highly reliable, and easy to install and disassemble. Attached Figure Description

[0025] Figure 1 This is a side view of the underwater transfer system in an embodiment of the present invention;

[0026] Figure 2 This is a front view of the underwater transfer system in an embodiment of the present invention;

[0027] Figure 3 This is a front view of the underwater transfer system in an embodiment of the present invention;

[0028] Figure 4 This is a front view of the transfer track in an embodiment of the present invention;

[0029] Figure 5 This is an end view of the transfer track in an embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of the maintenance platform in an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of the structure of the special lifting tool in an embodiment of the present invention;

[0032] Figure 8 for Figure 7 A magnified view of a portion of the image;

[0033] Figure 9 This is a side view of the transfer trolley in an embodiment of the present invention;

[0034] Figure 10 This is a front view of the transfer trolley in an embodiment of the present invention;

[0035] Figure 11 This is a left view of the transfer trolley in an embodiment of the present invention;

[0036] Figure 12 This is a schematic diagram of the sliding gear meshing assembly in an embodiment of the present invention;

[0037] Figure 13 This is a schematic diagram of the emergency recovery mechanism in an embodiment of the present invention.

[0038] In the diagram: 1-Transfer waterway, 2-Transfer track, 3-Transfer trolley, 4-Emergency recovery mechanism;

[0039] 21-Rail, 22-Transmission rack, 23-Rail tread, 24-Mechanical limiting component;

[0040] 31-Car body; 32-First wheel; 33-Second wheel; 34-Transmission gear system; 35-Lifting column; 36-Position monitoring sensor; 37-Drive mounting base; 38-Underwater motor; 39-Sliding gear meshing assembly; 301-Shackle; 302-Collision buffer; 303-Container;

[0041] 41-Windmill, 42-Top redirecting pulley, 43-Counterweight pulley, 44-Counterweight block, 45-Bottom redirecting pulley, 46-Traction rope;

[0042] 51-Maintenance walkway, 52-Guide groove, 53-Guide groove fixing part, 54-End limiting part;

[0043] 61-Mounting and fixing part, 62-Bearing, 63-Mounting rotating part, 64-Sliding drive shaft, 65-Drive gear, 66-End positioning part, 67-Sliding limiting plate, 68-Sliding space;

[0044] 71-Hook, 72-Lifting device main frame, 73-Guide lifting beam. Detailed Implementation

[0045] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0046] In the description of this invention, it should be noted that the terms "above" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience and simplification of the description and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0047] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0048] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection," "setting," "installation," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] To address the problems of complex structure, numerous failure points, high failure rate, poor reliability, and inconvenient maintenance in existing technologies, this invention provides an underwater transfer system, comprising a transfer track, a transfer trolley, an emergency recovery mechanism, and a crane, wherein:

[0050] The transfer track is laid in the transfer waterway, and the transfer trolley slides on the transfer track for transporting spent fuel between the unloading pool and the storage pool.

[0051] The emergency recovery mechanism is located on the maintenance platform above the transfer waterway and is connected to the transfer trolley, which is used to pull the transfer trolley along the transfer track toward the maintenance platform.

[0052] The crane is located near the maintenance platform and is used to lift the transfer trolley from the transfer waterway to the maintenance platform for inspection and maintenance after the emergency recovery mechanism has pulled the transfer trolley to its limit position, and to lower the inspected and maintained transfer trolley back onto the transfer track.

[0053] Example 1

[0054] like Figures 1-3 As shown, this embodiment discloses an underwater transfer system for transporting spent fuel in a transfer waterway 1 between an unloading pool and a spent fuel storage area, or in similar situations. The transfer system includes a transfer track 2, a transfer trolley 3, an emergency recovery mechanism 4, and a crane, wherein:

[0055] The transfer track 2 is laid in the transfer waterway 1, and the transfer trolley 3 slides on the transfer track 2 for loading spent fuel assemblies and for transporting spent fuel between the unloading pool and the storage pool.

[0056] The emergency recovery mechanism 4 is located on the maintenance platform above the transfer waterway 1 and is connected to the transfer trolley 3. It is used to pull the transfer trolley 3 along the transfer track toward the maintenance point in the event of a failure.

[0057] The crane is located near the maintenance platform and is used to lift the transfer trolley 3 from the transfer channel to the maintenance platform for inspection and maintenance after the emergency recovery mechanism 4 pulls the transfer trolley 3 to its limit position, and to lower the inspected and maintained transfer trolley 3 back onto the transfer track 2.

[0058] Specifically, transfer waterway 1 connects the unloading pool and storage pool in the spent fuel reprocessing plant. For example... Figure 4 , Figure 5 As shown, the transfer track 2 includes components such as track 21, track beam, and track fixing assembly. The track beam is located at the bottom of the transfer waterway 1. Track 21 generally consists of two tracks with a certain spacing. The specific spacing of the two tracks 21 can be selected according to factors such as the specifications of the required transfer trolley 3. In this embodiment, the preferred spacing of the two tracks 21 is 600-1000mm. This avoids both excessive width leading to low transport efficiency of spent fuel components and excessive width leading to difficulty in ensuring the center distance installation error of the two tracks. It also avoids excessive wear on the support wheels on both sides of the transfer trolley due to deformation and deflection, which would result in poor reliability and affect accuracy. Track 21 is installed on the track beam via the track fixing assembly, extending from the unloading pool to the storage pool. The upper surface of the two tracks 21 is the track tread 23, on which the transfer trolley 3 is mounted. Mechanical limiting components 24 are provided at both ends of the track tread 23 of track 21 to prevent the transfer trolley 3 from detaching from the track 21 after reaching its limit.

[0059] The maintenance platform can be installed at any end of the transfer water channel 1. For example, Figure 6 as shown, a maintenance walkway 51 is provided on the maintenance platform. The maintenance walkway 51 spans above the transfer water channel 1, and both ends of the maintenance walkway 51 can extend a certain distance along the two banks of the transfer water channel 1 to form a "C"-shaped maintenance walkway. The middle vacant position of the "C"-shaped maintenance walkway 51 is used for the transfer trolley 3. After the emergency recovery mechanism 4 pulls the transfer trolley 3 to the position below the middle vacant position, the transfer trolley 3 is then hoisted out of the water surface of the transfer water channel 1 by a crane.

[0060] The crane is installed above the maintenance platform, and a special lifting tool adapted to the transfer trolley 3 is configured on the crane.

[0061] In this embodiment, as Figure 7 、 8 shown, the special lifting tool includes a quick hook 71 (hereinafter referred to as the hook), a lifting tool main frame 72, and a guiding lifting beam 73. Among them: The hook 71 is installed at the bottom of the lifting tool main frame 72 and is used to connect the lifting hole of the transfer trolley 3. The width of the hook is smaller than the size of the lifting hole, and moreover, the shapes of the hook 71 and the lifting hole should ensure that the special lifting tool can be successfully positioned even without being supported underwater; The guiding lifting beam 73 is installed at the top of the lifting tool main frame 72, and the lifting rope of the crane is connected to the guiding lifting beam 73. Guide grooves (not shown in the figure) can be provided on both sides of the transfer water channel 1, and both ends of the guiding lifting beam 73 slide in the guide grooves and are restricted by the guide grooves, so as to avoid too large position deviation of the special lifting tool; The outer shape of the lifting tool main frame 72 is adapted to the outer shape of the transfer trolley 3, so that when lifting out the transfer trolley, the lifting tool main frame 72 can be covered on the transfer trolley 3, which is convenient for connecting the hook 71 to the lifting hole and can also prevent the frame of the transfer trolley from shaking to a certain extent.[[ID=第十三条]] [[ID=第十四条]]

[0062] In some embodiments, as Figure 9 、 Figure 10 、 Figure 11 shown, the transfer trolley includes a vehicle body 31, support wheels, an underwater motor 38, and a sliding gear meshing assembly 39.

[0063] Specifically, the vehicle body 31 is mounted on the transfer track 2 via support rollers. A container 303 for holding spent fuel assemblies is mounted on the vehicle body, preferably using bolts or other connection methods for easy installation and disassembly. Drive mounting seats 37 are located on both sides of the vehicle body 31. The underwater motor 38 and the sliding gear meshing assembly 39 are both mounted on the drive mounting seats 37. The underwater motor 38 is connected via cables and cable retraction components to a power supply from outside the transfer waterway 1 and a control system including a control console and control cabinet (e.g., a commercially available general-purpose control system) for power supply and remote control. In this embodiment, the transfer trolley has its own power drive unit. Compared to existing general spent fuel transfer systems that use a passive traction steel cable traction system for the transfer trolley, the structure is simpler, more reliable, and easier to operate. The output end of the underwater motor 38 is connected to the sliding gear meshing assembly 39. The transfer track 2 is equipped with a transmission rack 22. The transmission rack 22 and the sliding gear meshing assembly 39 cooperate to form a meshing transmission structure. The underwater motor 38 drives the sliding gear meshing assembly 39 to mesh with the transmission rack 22 on the transfer track 2, thereby driving the transfer trolley 3 to move bidirectionally (linearly) along the transfer track 2, thus realizing the transportation of spent fuel between the unloading pool and the spent fuel storage.

[0064] The vehicle body 31 is also equipped with a shackle 301 and a lifting column 35. The shackle 301 is located near the emergency recovery mechanism 4 for connection. The lifting column 35 can be located on the upper surface of the vehicle body 31 and has lifting holes that match the hooks 71 in the special lifting device. Preferably, there are multiple lifting columns 35, for example, four. These four lifting columns 35 are preferably located at the four corners of the vehicle body 31. Correspondingly, the special lifting device has multiple hooks 71 that match the lifting holes, for example, four hooks.

[0065] In this embodiment, a collision buffer 302 may also be provided on the vehicle body. It is preferably made of polyurethane material. When the transfer trolley moves to the extreme positions at both ends of the transfer track, the collision buffer abuts against the mechanical limiting member 24, which can effectively absorb the mechanical collision energy.

[0066] In some embodiments, there are two or more pairs of support wheels. A first wheel 32 is provided on the same side of each pair of support wheels, and a second wheel 33 is provided on the other side of each pair of support wheels. The first wheel 32 has a flared rim that can cooperate with the transfer track 2. The proximal end of the flared rim is smaller and the same as the width of the track. The two are fitted together by machining precision (interference fit). The distal end of the flared rim is larger, which facilitates the track entering the rim range of the first wheel 32. The inclined surface of the flared rim completes the fit guidance, and finally ensures that the track tread and the smaller proximal end of the flared rim are fitted together. This ensures that the first wheel 32 can be easily placed on the transfer track 2, and at the same time, it can effectively restrict the movement of the transfer trolley 3 in the vertical direction along the transfer track 2, avoid lateral movement of the support wheels when they travel on the track, and ensure the straightness of the transfer trolley. The second wheel 33 is a cylindrical wheel, which does not constrain the transfer trolley 3 in the vertical direction of the transfer track 2. With the above settings, the center distance between the two tracks of the transfer track 2 does not need to be exactly the same as the center of each support wheel, which can reduce the requirements for the installation accuracy of the transfer track and the processing accuracy of the support wheels.

[0067] In this embodiment, as Figure 9 As shown, the transfer trolley 3 has four support wheels, that is, there are two pairs of support wheels. Each pair of support wheels includes left and right wheels. The two wheels in each pair of support wheels are connected by a transmission wheel system 34 including bearings and transmission shafts and are installed on the body 31 of the transfer trolley 3. The two support wheels on one side of the body are the first wheels 32, and the two support wheels on the other side are the second wheels 33.

[0068] In some implementations, such as Figure 12 As shown, the sliding gear meshing assembly 39 includes a mounting and fixing part 61, a bearing 62, a mounting and rotating part 63, a sliding transmission shaft 64, and a transmission gear 65.

[0069] Specifically, the mounting and fixing part 61 is provided on the drive mounting seats 37 on both sides of the vehicle body 31. The mounting rotating part 63 is movably embedded in the mounting and fixing part 61 through the bearing 62. The mounting rotating part 63 is provided with a sliding space 68. One end of the sliding drive shaft 64 is movably inserted into the sliding space 68 and can rotate together with the mounting rotating part 63. A spring is provided in the sliding space 68, with one end of the spring abutting against the sliding drive shaft 64 and the other end abutting against the mounting rotating part 63. A sliding limiting plate 67 is sleeved on the sliding drive shaft 64 and is connected to the mounting rotating part 63 to prevent the sliding drive shaft 64 from dislodging from the sliding space 68. The transmission gear 65 is provided at the other end of the sliding drive shaft 64 and is adapted to the transmission rack 22 to form the meshing transmission structure. The sliding drive shaft 64 is also provided with an end positioning part 66 to prevent the transmission gear 65 from dislodging from the sliding drive shaft 64.

[0070] Under normal circumstances, the sliding drive shaft 64 maintains its maximum length L under the action of gravity or the spring force in the sliding space 68. At this time, the centers of the transmission rack 22 and the transmission gear 65 are basically coincident, and they are in the maximum overlap state. This allows the torque of the underwater motor to be fully converted into driving force, thereby driving the transmission gear 65 in the sliding gear meshing assembly 39 to rotate and mesh with the transmission rack 22 on the transfer track 2 to drive the transfer trolley 3 to move in both directions (straight line) along the transfer track 2, thus realizing the transportation of spent fuel.

[0071] In this embodiment, the sliding drive shaft 64 and the mounting rotating part 63 are preferably connected by a spline, flat key, or regular polygonal shaft and bushing, etc. That is, one end of the sliding drive shaft 64 is movably inserted into the sliding space 68 of the mounting rotating part 63 through the cooperation of components such as splines, flat keys, or regular polygonal shafts and bushings, so that the sliding drive shaft 64 and the mounting rotating part 63 can always rotate together. However, the distance between them, i.e., the sliding space L, can change according to the force conditions.

[0072] When the transfer trolley 3 is not fully placed on the track tread 23, the support wheel has a lateral degree of freedom of movement relative to the track. However, when the two engage, this lateral degree of freedom is eliminated and a positioning relationship is established. At this time, the meshing relationship between the transmission gear 65 and the transmission rack 22 is also formed accordingly. The setting of the sliding space allows for fine-tuning of the phase between the transmission gear 65 and the transmission rack 22 to achieve meshing when the transfer trolley is placed back on the track. The engagement relationship between the transmission gear 65 and the transmission rack 22 will not interfere with or affect its operation.

[0073] In this embodiment, the transmission rack 22 is preferably located on the side (outer side) of the track 21, that is, the transmission rack 22 on the transfer track 2 is side-mounted. This installation method can effectively prevent debris in the transfer waterway 1 from falling onto the transmission rack 22 and interfering with the meshing of the transmission gear 65 and the transmission rack 22. It can also ensure that the transmission gear 65 and the transmission rack 22 can be easily separated and meshed during the lifting and lowering of the transfer trolley 3 (for example, lifting it out of the transfer waterway 1 to the maintenance platform for maintenance and lifting the maintenance-repaired transfer trolley 3 back onto the transfer track 2), reducing the difficulty of disassembly and installation.

[0074] Furthermore, in order to further ensure that the transmission gear 65 and the transmission rack 22 can smoothly form a meshing relationship under the action of the sliding gear meshing assembly 39, conventional machining such as rounded corners and chamfers are used at the edges of the transmission gear 65 and the transmission rack 22 in this embodiment to minimize the difficulty of forming a meshing relationship between the two.

[0075] In some implementations, such as Figure 9 As shown, the transfer trolley 3 is equipped with a position monitoring sensor 36, which includes an encoder and a fixed-point induction sensor. The encoder is mounted on the underwater motor 38, and the fixed-point induction sensor is mounted on the trolley body 31. Both position monitoring sensors 36 are connected to the control system and work together to realize the real-time positioning and fixed-point stopping of the transfer trolley 3 on the transfer track 2. That is, the system in this embodiment has online position monitoring and fixed-point stopping functions.

[0076] To ensure the reliability of the transfer trolley 3, multiple drive units are installed on both sides of the transfer trolley 3 in this embodiment, preferably two drive units, i.e., two underwater motors 38 are installed on each side of the transfer trolley 3, with one drive unit in operation and the other as a backup. Under normal circumstances, one drive unit supplies power and the other is driven. When one drive unit fails, the other drive unit is activated. When both drive units fail, the transfer trolley 3 cannot continue transportation using external power supply. In this case, the transfer trolley 3 needs to be towed to the installation side of the emergency recovery mechanism 4 (i.e., below the maintenance platform) via the emergency recovery mechanism 4.

[0077] In some implementations, such as Figure 13 As shown, the emergency recovery mechanism 4 includes a winch 41, a pulley block, a counterweight block 44, and a traction rope 46. The winch 41 is located above the transfer waterway 1, for example, on a maintenance platform. The pulley block includes a redirecting pulley and a counterweight pulley 43. One end of the traction rope 46 is fixed to the winch 41, and the other end passes through the counterweight pulley 43 and the redirecting pulley and is connected to the shackle 301 on the transfer trolley 3 to pull the transfer trolley 3 to the area below the maintenance platform. The counterweight pulley 43 slides on the traction rope 46 and is a movable pulley. The counterweight block 44 is located on the counterweight pulley 43. When the transfer trolley 3 moves on the transfer track 2, the counterweight pulley 43 can drive the counterweight block 44 to move up and down together.

[0078] Specifically, the winch 41 is a bidirectional winch, fixed on the maintenance walkway 51 within the maintenance platform. The redirecting pulleys include a top redirecting pulley 42 and a bottom redirecting pulley 45. The top redirecting pulley 42 can be located on the maintenance walkway 51 within the maintenance platform above the transfer channel 1, while the bottom redirecting pulley 45 can be located within the transfer channel 1. The position height of the bottom redirecting pulley 45 is preferably the same as the position height of the shackle 301 on the transfer trolley 3. This allows the traction rope 46 to sequentially wrap around the counterweight pulley 43, the top redirecting pulley 42, and the bottom redirecting pulley 45, applying a force parallel to the transfer track 2 to the transfer trolley 3, preventing the transfer trolley 3 from detaching from the transfer track 2 under the action of the traction rope 46.

[0079] In this embodiment, the traction rope 46 is preferably made of steel wire rope, and more preferably of stainless steel wire rope, to prevent corrosion and failure that may easily occur underwater.

[0080] In some implementations, such as Figure 6 As shown, the system also includes a guide groove 52, which is located on the path of the counterweight pulley 43 as it moves up and down. For example, the upper end of the guide groove 52 can be fixed to the maintenance platform 51, and the lower end of the guide groove 52 is supported on the side wall of the transfer waterway 1 by the guide groove fixing part 53. The counterweight block 44 is located in the guide groove 52 and can move up and down in the guide groove 52, thereby limiting the movement trajectory of the counterweight pulley 43 and preventing its position from changing. Furthermore, when the counterweight pulley 43 reaches the upper or lower end limit of the guide groove 52, the guide groove 52 can effectively constrain the counterweight pulley 43, making it relatively fixed and improving the stability of the system operation. An end limit member 54 is provided at the bottom of the guide groove 52 to prevent the counterweight block 44 from falling out after descending to the limit position.

[0081] Under normal operating conditions, the winch 41 remains stationary. When the transfer trolley 3 moves on the transfer track 2, the counterweight pulley 43 drives the counterweight block 44 to move up and down together. The counterweight block 44 ensures that the traction rope 46 maintains a certain tension, preventing it from becoming slack or overlapping. Since the counterweight pulley 43 is a movable pulley, when the transfer trolley 3 travels a distance S, the vertical movement distance of the counterweight pulley 43 is S / 2. Given that the depth and length of the transfer channel 1 are approximately equal, the descent height of the counterweight pulley 43 will not reach the bottom of the transfer channel 1. The length of the guide groove 52 does not need to reach the bottom of the transfer channel 1. Even if a malfunction occurs and maintenance is required, it is not necessary to completely drain the water from the transfer channel 1 and its connected pool, making maintenance more convenient and faster.

[0082] When the transfer trolley malfunctions, firstly, the winch 41 is rotated to raise the counterweight pulley 43 and counterweight block 44 until they reach their maximum lifting position. Then, the winch 41 is rotated again, and the transfer trolley 3 will move towards the side where the emergency recovery mechanism 4 is installed under the tension of the traction rope 46 until the transfer trolley 3 is pulled to a suitable position below the maintenance platform (for example, to the maximum position at the end of the transfer track 2 near the maintenance platform). Then, the winch 41 is rotated in the opposite direction to lower the counterweight pulley 43 and counterweight block 44 until they reach the end limit member 54. Then, the winch 41 is rotated in the opposite direction again, and the traction rope 46 will disengage from the counterweight pulley 43 and hang from it. In the space below, a crane is used with a special lifting device to lower the special lifting device into the transfer channel 1. After the hook 71 in the special lifting device is connected to the lifting hole on the lifting column 35 of the transfer trolley 3, the transfer trolley 3 is lifted out of the transfer channel 1 to the surface. The staff approach the transfer trolley 3 through the maintenance walkway 51 set in the maintenance platform and carry out maintenance. The maintenance mainly targets vulnerable parts such as the underwater motor 38 and the position monitoring sensor 36 in the transfer trolley. During the process of lifting the transfer trolley 3, the winch 41 needs to be rotated at all times and the traction rope 46 needs to be kept in a slack state to ensure that the traction rope 46 has sufficient slack and avoids constraining the lifting of the transfer trolley 3.

[0083] After the inspection and maintenance are completed, use a crane with special lifting tools to lower the transfer trolley 3 again until the support wheel of the transfer trolley 3 is placed on the track tread 23 of the transfer track 2. During this process, the winch 41 needs to be rotated continuously to keep the traction rope 46 in a slack state.

[0084] In some embodiments, the rims of the counterweight pulley 43 and the redirecting pulleys (including the top redirecting pulley 42 and the bottom redirecting pulley 45) can be provided with a universal anti-derailment device or structure that can prevent the traction rope 46 from coming out of the rope groove even if it is slack, so as to prevent the traction rope from coming out of the rope groove of each pulley. Therefore, in this embodiment, during the winding and unwinding of the traction rope 46 (i.e., during the process of the winch 41 being rotated to make the traction rope 46 detach from the counterweight pulley 43 and hang in the space below the counterweight pulley 43), there is no need to worry about the traction rope coming out of the rope groove of each pulley.

[0085] In some embodiments, the maximum length L of the sliding space 68 is preferably greater than the width of the drive rack 22.

[0086] Specifically, during the process of returning the transfer trolley 3 to the transfer track 2 after installation or maintenance, the transmission gear 65 and the transmission rack 22 may not be perfectly aligned. In this case, the lower surface of the transmission gear 65 is likely to be on the upper surface of the transmission rack 22, and the transmission rack 22 will exert an upward force on the transmission gear 65 (e.g., ...). Figure 9The reaction force (shown) causes the sliding drive shaft 64 to move upward within the sliding space 68. Therefore, the maximum length L of the sliding space 68 is preferably greater than the width of the drive rack 22, which reduces the requirements for installation and machining accuracy and facilitates installation.

[0087] In actual operation, if the above situation is encountered, the winch 41 can be rotated to make the traction rope 46 pull on the transfer trolley 3. After the transfer trolley 3 is subjected to force, it will move slightly. When the phase of the transmission gear 65 and the transmission rack 22 is in the meshing state during the movement, the sliding transmission shaft 64 will descend to the lowest position under the action of gravity or spring force. At this time, the transmission gear 65 and the transmission rack 22 are already in the meshing state.

[0088] It should be noted that during the process of returning the transfer trolley 3 to the transfer track 2 after installation or maintenance, the placement position of the transfer trolley 3 should be further away from the side where the emergency recovery mechanism 4 is installed than the limit position to which the transfer trolley 3 can be pulled by the traction rope 46. That is, a certain distance should be reserved between the placement position of the transfer trolley 3 and the limit position at the end of the transfer track 2 closest to the emergency recovery mechanism 4, to ensure that the transfer trolley 3 can be pulled by the traction rope 46 and form the required meshing relationship if the transmission gear 65 and the transmission rack 22 are not in a properly meshed position. If, after the transfer trolley 3 is pulled to the limit position by the traction rope, the transmission gear 65 and the transmission rack 22 still do not form a meshing relationship, a crane with special lifting equipment needs to be used to lift the transfer trolley 3 again and place it back onto the transfer track 2, away from the limit position, until the transmission gear 65 and the transmission rack 22 form a meshing relationship.

[0089] The installation and use process of the underwater transfer system in this embodiment will be further described below:

[0090] For initial installation, it is preferable to complete the installation before water is added to the transfer channel 1. Specifically, first install the transfer track 2 in the transfer channel 1, then install the transfer trolley 3 and the emergency recovery mechanism 4, then connect the two with steel wire ropes, and finally, after the entire system has been debugged and tested and confirmed to be working properly, add water to the transfer channel 1.

[0091] During the transfer, the underwater motor 38 is connected to an external power supply and started by the external control system, so that the transfer trolley 3 moves back and forth between the unloading pool and the storage pool along the transfer track 2. During the reciprocating motion, the spent fuel assembly is transferred in the transfer waterway.

[0092] When both drive units of the transfer trolley 3 malfunction, the emergency recovery mechanism 4 is activated to pull the transfer trolley 3 along the transfer track 2 towards the maintenance point, returning it to the maintenance platform position. A crane above the maintenance position, in conjunction with specialized lifting equipment, then lifts the transfer trolley 3 out of the water for inspection and maintenance.

[0093] After the inspection and maintenance are completed, a crane is used again with special lifting equipment to put the transfer trolley 3 back onto the transfer track 2 in the transfer waterway 1 for reuse.

[0094] The underwater transfer system of this embodiment has at least the following advantages compared to the prior art:

[0095] (1) By setting up a transfer trolley with a certain load capacity and movement capability, it can carry the spent fuel basket and load the spent fuel assembly and move on the transfer track, thereby realizing the transfer of spent fuel assembly between the unloading pool and the storage pool connected by the transfer waterway.

[0096] (2) By setting up a working and standby drive device and a sliding gear meshing assembly on the transfer trolley, it can mesh with the transmission rack on the transfer track to drive the transfer trolley. Compared with traditional technology (that is, the drive devices of the transfer system are all installed on the water, and the drive devices are driven and controlled by cables from the water surface to the underwater via a drum and wire rope winding system), the structure is simple, there are fewer fault points, the failure rate is low, and the maintenance is less difficult.

[0097] (3) By setting up an emergency recovery mechanism and a crane, in the event of a malfunction, the operation can be carried out from the maintenance platform on the water. The malfunctioning and inoperable transfer trolley can be pulled back to the bottom of the maintenance platform and then lifted out to the maintenance platform for inspection and maintenance. After the inspection and maintenance work is completed, the crane can be used to return the transfer trolley to the transfer track. Compared with the existing technology, there is no need to drain water, which saves time and costs and increases the production line operating rate. There is also no need for staff to enter the transfer waterway or underwater for inspection and maintenance, which can protect staff from the dual threats of narrow space and ionizing radiation. It is both convenient and safe.

[0098] (4) By setting counterweight pulleys and counterweight blocks, the traction rope can always maintain a certain tension, and the traction rope can be prevented from becoming loose or stacked during the movement of the transfer trolley.

[0099] (5) By setting guide channels on both sides of the transfer waterway to limit the guide lifting beam, the positional deviation of the crane lifting device can be avoided, thereby improving the accuracy and stability of the lifting and lowering of the transfer trolley.

[0100] (6) By setting a sliding space, when the transmission gear and transmission rack of the transfer trolley are not in phase and are fully engaged, the transmission gear can be retracted under the reaction force of the transmission rack. This ensures that the transmission gear and transmission rack will not collide or obstruct each other before the transfer trolley is returned to the transfer track. After the transfer trolley is returned to the transfer track, the winch wire rope (i.e., traction rope) can be used to pull the transfer trolley to move slightly until the phase of the transmission rack and transmission gear is engaged. At this time, the transmission gear extends and meshes with the transmission rack, which can reduce the installation accuracy and failure rate.

[0101] (7) The components of this system, such as the transfer track, transfer trolley, and emergency recovery mechanism, are modularly designed. They are relatively independent in function, easy to combine and disassemble, highly reliable, and easy to install and disassemble.

[0102] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An underwater transfer system, characterized in that, Includes a transfer track (2), a transfer trolley (3), an emergency recovery mechanism (4), and a crane. The transfer track is laid in the transfer waterway (1), and the transfer trolley slides on the transfer track for transporting spent fuel between the unloading pool and the storage pool. The emergency recovery mechanism is located on the maintenance platform above the transfer waterway and is connected to the transfer trolley, which is used to pull the transfer trolley along the transfer track toward the maintenance platform. The crane is located near the maintenance platform and is used to lift the transfer trolley from the transfer waterway to the maintenance platform for inspection and maintenance after the emergency recovery mechanism pulls the transfer trolley to its limit position, and to lower the inspected and maintained transfer trolley back onto the transfer track. The transfer trolley includes a body (31), support wheels, an underwater motor (38), and a sliding gear meshing assembly (39). The body is slidably mounted on the transfer track via the support wheels. Drive mounting seats (37) are provided on both sides of the body. The underwater motor and the sliding gear meshing assembly are both mounted on the drive mounting seats. The output end of the underwater motor is connected to the sliding gear meshing assembly. A transmission rack (22) is provided on the transfer track. The transmission rack and the sliding gear meshing assembly cooperate to form a meshing transmission structure. The underwater motor drives the sliding gear meshing assembly to mesh with the transmission rack on the transfer track, thereby driving the transfer trolley to move bidirectionally along the transfer track. The number of support wheels is two or more pairs. A first wheel (32) is provided on the same side of each pair of support wheels, and a second wheel (33) is provided on the other side of each pair of support wheels. The first wheel has a flared rim that can cooperate with the transfer track, and the second wheel is a cylindrical wheel.

2. The underwater transfer system according to claim 1, characterized in that, The sliding gear meshing assembly includes a mounting and fixing part (61), a bearing (62), a mounting and rotating part (63), a sliding transmission shaft (64), and a transmission gear (65). The mounting and fixing part is provided on the drive mounting base, and the mounting and rotating part is movably embedded in the mounting and fixing part through the bearing. The mounting and rotating part is provided with a sliding space (68). One end of the sliding drive shaft is movably inserted into the sliding space and can rotate together with the mounting rotating part; The transmission gear is located at the other end of the sliding transmission shaft and is adapted to the transmission rack to form the meshing transmission structure.

3. The underwater transfer system according to claim 2, characterized in that, The transmission rack is located on the outer side of the transfer track.

4. The underwater transfer system according to claim 2, characterized in that, The maximum length of the sliding space is greater than the width of the transmission rack.

5. The underwater transfer system according to claim 1, characterized in that, The crane is equipped with a special lifting device, which includes a hook (71), a main frame of the lifting device (72), and a guide beam (73). The shape of the main frame of the lifting device is adapted to the shape of the transfer trolley, and it is placed on the transfer trolley when it is lifted out. The hook is located at the bottom of the main frame of the lifting device and is used to connect the transfer trolley; The guide beam is located on the top of the main frame of the lifting device, and the crane's lifting rope is connected to the guide beam.

6. The underwater transfer system according to claim 1, characterized in that, The transfer trolley is equipped with a position monitoring sensor (36). The position monitoring sensor includes an encoder and a fixed-point sensor. The encoder is mounted on the underwater motor, and the fixed-point sensor is mounted on the vehicle body. It is used for real-time positioning and fixed-point stopping of the transfer trolley on the transfer track.

7. The underwater transfer system according to any one of claims 1-6, characterized in that, The emergency recovery mechanism includes a winch (41), a pulley block, a counterweight (44), and a traction rope (46). The winch is located on the maintenance platform. The pulley block includes a redirecting pulley and a counterweight pulley (43). One end of the traction rope is fixed to the winch, and the other end passes through the counterweight pulley and the redirecting pulley and is connected to the transfer trolley to pull the transfer trolley to the bottom of the maintenance platform. The counterweight pulley is mounted on the traction rope, and the counterweight block is mounted on the counterweight pulley. When the transfer trolley moves on the transfer track, the counterweight pulley can drive the counterweight block to move up and down together.

8. The underwater transfer system according to claim 7, characterized in that, The system also includes a guide groove (52), The guide groove is located on the path of the counterweight pulley's up-and-down movement. The counterweight block is located in the guide groove and can move up and down in the guide groove. The guide groove is provided with an end limiting member.

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