Spent fuel storage device and spent fuel transfer method

Abstract

The invention discloses a spent fuel storage device and a spent fuel transfer method. The spent fuel storage device comprises a spent fuel storage tank, a shielding protection container, a sealing ring and a drainage assembly. The spent fuel storage tank is assembled in the shielding protection container; the sealing ring is arranged at the upper part of an annular cavity between the spent fuel storage tank and the shielding protection container; the top end face of the shielding protection container is provided with a pressing sealing face used for being tightly attached to the pool bottom penetrating piece. And the drainage assembly radially penetrates through the top of the shielding protection container and is communicated with the inner cavity of the spent fuel storage tank. The spent fuel storage device is used for being in direct butt joint with the pool bottom penetrating piece, the problems of sealing containing and water filling and draining operation are solved, a spent fuel assembly can conveniently enter the spent fuel storage device through the pool bottom penetrating piece in a spent fuel pool, the spent fuel assembly is received from the bottom of the pool, and the risk that a container falls off is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power spent fuel storage, and in particular to a spent fuel storage device and a spent fuel transfer method. Background Art

[0002] Spent fuel unloaded from a nuclear power plant away from the reactor usually needs to be stored in a pool for 8 - 10 years before being transported out. Due to the limited storage capacity of the spent fuel pool in the nuclear power plant and the insufficient spent fuel reprocessing capacity, currently internationally, intermediate spent fuel storage methods are considered to alleviate the problem of spent fuel storage away from the reactor. For the intermediate spent fuel storage method, the specific technical solution is to place the spent fuel storage container in the spent fuel pool, load the spent fuel underwater, and then use a crane to lift the container out of the pool. The main safety risk of this technical solution is that the container may fall during the container lifting process, and the spent fuel loaded inside the container may have structural damage, resulting in the release of a large amount of radioactive substances.

[0003] To substantially eliminate the risk of container dropping, in the design and construction of a new generation of nuclear power plants internationally, through - penetrations are considered to be set at the bottom of the pool, and then a special container is developed to dock with the through - penetrations before spent fuel is transferred. Limited by the technical difficulties of through - penetration sealing safety and filling and draining operation, existing spent fuel storage containers cannot directly dock with the through - penetrations at the bottom of the pool to complete spent fuel transfer. The problems are as follows:

[0004] 1) The interface with the through - penetration does not match, and the sealing and containment function cannot be achieved

[0005] After the container is docked with the through - penetration, a sealed containment boundary must be formed, otherwise, a water leakage safety accident in the pool is likely to occur. Existing storage containers all perform the loading operation inside the pool and then are lifted out of the water for dry - sealing operation. Based on the new process plan, existing storage containers all lack a sealing structure that matches the through - penetrations at the bottom of the pool structure, so they cannot meet the system's sealing and containment safety requirements.

[0006] 2) After the storage container is sealed and docked with the through - penetration, the isolation state cannot be filled or drained

[0007] After the existing storage container completes the loading of the spent fuel assembly, the operator connects the drainage pipeline in the top area at close range for drainage operation. Once an existing type of storage container is docked with the through - penetration, the top of the storage container is in an isolated and contained state, and the operator cannot perform filling and draining operations. This results in the inability to empty all the water bodies contained in the top of the storage container to the inside of the through - penetration, making it impossible for the storage container to be unlocked and separated from the through - penetration to perform subsequent process operations. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide an improved spent fuel storage device and a spent fuel transfer method implemented by the spent fuel storage device.

[0009] The technical solution adopted by the present invention to solve its technical problems is: to provide a spent fuel storage device for docking with a bottom penetration member. The spent fuel storage device includes a spent fuel storage tank, a shielding protection container, a sealing ring, and a drainage assembly;

[0010] The spent fuel storage tank is assembled inside the shielding protection container and is used to accommodate the spent fuel assembly. The sealing ring is arranged at the upper part of the annular cavity between the spent fuel storage tank and the shielding protection container, so that the annular cavity between the spent fuel storage tank and the shielding protection container forms a sealed annular cavity;

[0011] The top of the shielding protection container protrudes above the spent fuel storage tank, and the top end face of the shielding protection container is provided with a pressing sealing surface for closely fitting with the bottom penetration member; the drainage assembly is radially penetrated through the top of the shielding protection container and communicated with the inner cavity of the spent fuel storage tank.

[0012] In some embodiments, the spent fuel storage tank includes a bottom plate, a cylindrical wall connected to the bottom plate, a fuel basket located inside the cylindrical wall, and a drainage module arranged inside the cylindrical wall;

[0013] The drainage module includes a first seat body fixed inside the cylindrical wall and located above the fuel basket, a pore channel arranged inside the first seat body, a quick connector connected to the upper end of the pore channel, a transition drainage member connected to the quick connector, and a siphon tube connected to the lower end of the pore channel;

[0014] One end of the transition drainage member away from the quick connector faces the shielding protection container and is connected to the drainage assembly; the siphon tube extends towards the bottom plate inside the cylindrical wall.

[0015] In some embodiments, the fuel basket includes a receiving tube group for placing the spent fuel assembly, a plurality of partition plates, and a plurality of positioning rods; the receiving tube group includes a plurality of adjacent receiving tubes; a plurality of the partition plates are sleeved on the receiving tube group and are spaced along the axial direction of the receiving tube group; a plurality of the positioning rods are spaced along the circumferential direction of the partition plates, penetrate through all the partition plates and support on the bottom plate.

[0016] In some embodiments, in the fuel basket, there is a gap between the lowermost partition plate and the bottom plate, forming a bottom space; a notch is provided on the lower sidewall of each receiving pipe, and the depth of the notch is less than the height of the gap; at least one through hole is formed in the partition plate at a position outside the receiving pipe group, and the bottom space communicates with the notch and the through hole on the partition plate near the bottom plate; the through holes on all the partition plates are connected up and down and communicate with the notch through the bottom space, forming a gas up-and-down convection circulation channel on the fuel basket.

[0017] In some embodiments, the spent fuel storage tank further includes an inflation module; the inflation module includes a second seat body fixed inside the barrel wall and above the fuel basket, and an inflation channel penetrating through the second seat body is provided on the second seat body.

[0018] In some embodiments, the spent fuel storage tank further includes a first sealing cover plate and a second sealing cover plate; the first sealing cover plate is fitted on the top of the barrel wall, and a first notch and a second notch are further provided at the edge of the first sealing cover plate; the first notch corresponds above the drainage module, and the second notch corresponds above the inflation module; the second sealing cover plate is fitted on the first sealing cover plate.

[0019] In some embodiments, the shielding protection container includes a base, a first cylinder body, a second cylinder body, a third cylinder body, and a docking flange; the first cylinder body, the second cylinder body, and the third cylinder body are respectively connected to the base and sleeved from the inside to the outside in sequence; the docking flange is connected to the tops of the first cylinder body, the second cylinder body, and the third cylinder body; the annular cavity between the first cylinder body and the second cylinder body is used to fill a lead layer, and the annular cavity between the second cylinder body and the third cylinder body is used to fill demineralized water; the compression sealing surface is arranged on the top surface of the docking flange.

[0020] In some embodiments, the shielding protection container further includes a plurality of circumferential rib plates arranged in the annular cavity between the second cylinder body and the third cylinder body, and / or a lead layer filled in the annular cavity between the first cylinder body and the second cylinder body, and / or demineralized water filled in the annular cavity between the second cylinder body and the third cylinder body.

[0021] In some embodiments, a top cover sealing surface is further provided on the top surface of the docking flange; the top cover sealing surface is connected to the periphery of the compression sealing surface and is above the compression sealing surface.

[0022] In some embodiments, the shielding protection container further includes a top cover for fitting on the docking flange to seal the shielding protection container.

[0023] In some embodiments, the shielding protection container further includes at least one upper trunnion protruding outside the upper end of the third cylinder and at least one lower trunnion protruding outside the lower end of the third cylinder.

[0024] In some embodiments, the drainage assembly includes a drainage channel provided in the docking flange, a first drainage joint and a second drainage joint respectively connected to both ends of the drainage channel;

[0025] On the inner peripheral surface of the docking flange, there are drainage suction holes communicated with the drainage channel, and on the outer peripheral surface of the docking flange, there are drainage outlet holes communicated with the drainage channel;

[0026] The first drainage joint is arranged in the drainage suction hole, the second drainage joint is arranged in the drainage outlet hole, and the second drainage joint is used for externally connecting a drain pipe.

[0027] The present invention also provides a spent fuel transfer method, which adopts the above-mentioned spent fuel storage device. The spent fuel transfer method includes the following steps:

[0028] S1. Transport the spent fuel storage device below the bottom penetration piece, and lift the spent fuel storage device through a jacking device so that the compression sealing surface of its shielding protection container is closely attached to the compression flange surface of the bottom penetration piece; the top cover of the bottom penetration piece is in a horizontal sealing state;

[0029] S2. Fill water into the spent fuel storage tank through the drainage assembly until the water level rises to the elevation position at the top of the bottom penetration piece;

[0030] S3. Continue to fill water into the spent fuel storage tank until the pressures on both sides of the top cover of the bottom penetration piece are balanced;

[0031] S4. Open the top cover of the bottom penetration piece to a vertical state, and load the spent fuel assembly from the water pool into the spent fuel storage tank along the bottom penetration piece;

[0032] S5. After loading the spent fuel assembly, close the top cover of the bottom penetration piece;

[0033] S6. Drain the water in the spent fuel storage tank through the drainage assembly until the water level drops to the elevation position at the top of the spent fuel storage tank;

[0034] S7. After the spent fuel storage device with the spent fuel assembly is separated from the bottom penetration piece, seal the top of the spent fuel storage tank and inflate the inside of the spent fuel storage tank;

[0035] S8. Transfer the spent fuel storage device to the storage area, and take out the spent fuel storage tank with the spent fuel assemblies from the shielding protection container for storage.

[0036] In some embodiments, step S1 includes:

[0037] S1.1. Hang the spent fuel storage tank device inside the shielding protection container, and remove the first and second sealing covers of the spent fuel storage tank;

[0038] S1.2. Insert a sealing ring into the upper part of the annular cavity between the spent fuel storage tank and the shielding protection container to form a sealed annular cavity; inflate to make the sealed annular cavity in a tightly pressed sealing state.

[0039] The spent fuel storage device of the present invention is used to directly dock with the bottom penetration piece, solve the problems of sealed containment and filling and draining operations, facilitate the spent fuel assemblies to enter the spent fuel storage device through the bottom penetration piece in the spent fuel pool, and realize the reception of the spent fuel assemblies from the bottom of the pool to avoid the risk of container dropping. Description of the Drawings

[0040] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0041] Figure 1 is a schematic cross-sectional structure diagram of the spent fuel storage device according to an embodiment of the present invention below the spent fuel pool and docked below the bottom penetration piece;

[0042] Figure 2 is a schematic structure diagram (1 / 4 cross-section) of the spent fuel storage device according to an embodiment of the present invention docked below the bottom penetration piece (with the top cover in the vertical state);

[0043] Figure 3 is a schematic structure diagram (partial cross-section) of the spent fuel storage tank in the spent fuel storage device according to an embodiment of the present invention;

[0044] Figure 4 is Figure 3 a schematic structure diagram of the fuel basket in the spent fuel storage tank shown in ;

[0045] Figure 5 is Figure 4 a schematic structure diagram of the partition in the fuel basket shown in ;

[0046] Figure 6 is Figure 3 an enlarged schematic structure diagram of the drainage module in the spent fuel storage tank shown in ;

[0047] Figure 7 is a schematic structure diagram (partial cross-section) of the shielding protection container (with the top cover) in the spent fuel storage device according to an embodiment of the present invention;

[0048] Figure 8 is Figure 7 The structural schematic diagram of the drainage component on the docking flange in the shielding protection container shown;

[0049] Figure 9 is the sectional structural schematic diagram of the spent fuel storage device according to an embodiment of the present invention below the spent fuel pool and docked below the bottom penetration member (the top cover is in a horizontal sealed state);

[0050] Figure 10 is the sectional structural schematic diagram of the spent fuel storage device according to an embodiment of the present invention below the bottom penetration member and filled with spent fuel assemblies. Detailed implementation manners

[0051] For a clearer understanding of the technical features, objectives, and effects of the present invention, the detailed implementation manners of the present invention will now be described in detail with reference to the accompanying drawings.

[0052] The spent fuel storage device of the present invention is used to dock with the bottom penetration member, and transfer the spent fuel assemblies in the spent fuel pool to the spent fuel storage device through the bottom penetration member for transportation.

[0053] Refer to Figures 1 to 2 , in some embodiments, the spent fuel storage device includes a spent fuel storage tank 10, a shielding protection container 20, a sealing ring 30, and a drainage component 40.

[0054] The spent fuel storage tank 10 is assembled inside the shielding protection container 20 and is used to accommodate the spent fuel assemblies 100. The shielding protection container 20 is located outside the spent fuel storage tank 10 and undertakes the structural and shielding protection functions for the spent fuel storage tank 10. The sealing ring 30 is arranged at the upper part of the annular cavity between the spent fuel storage tank 10 and the shielding protection container 20, so that the annular cavity between the spent fuel storage tank 10 and the shielding protection container 20 forms a sealed annular cavity, which is used to ensure that the radioactive water in the spent fuel pool does not enter the annular cavity area between the spent fuel storage tank 10 and the shielding protection container 20 after docking with the bottom penetration member 200, thereby avoiding the outer surface of the spent fuel storage tank 10 and the inner cavity of the shielding protection container 20 from being contaminated.

[0055] The top of the shielding protection container 20 protrudes above the spent fuel storage tank 10 and can be closely attached to the bottom penetration member 200 to achieve sealed docking with the bottom penetration member 200. The drainage component 40 is radially penetrated through the top of the shielding protection container 20 and is communicated with the inner cavity of the spent fuel storage tank 10; the drainage component 40 is used to fill water into the spent fuel storage tank 10 and also to drain the water in the spent fuel storage tank 10.

[0056] Such as Figures 2 to 5As shown, the spent fuel storage tank 10 may include a bottom plate 11, a cylindrical wall 12 connected to the bottom plate 11, a fuel basket 13 located within the cylindrical wall 12, and a drainage module 14 disposed within the cylindrical wall 12. The bottom plate 11 and the cylindrical wall 12 constitute the main structure of the spent fuel storage tank 10, and the cylindrical wall 12 can be fixed to the bottom plate 11 by welding. In terms of shape, the cylindrical wall 12 can be, but is not limited to, a cylindrical barrel.

[0057] Specifically, the fuel basket 13 is used for the spent fuel assemblies to be inserted therein, so as to load and position the spent fuel assemblies within the spent fuel storage tank 10. In some embodiments, the fuel basket 13 includes a receiving tube group for placing the spent fuel assemblies, a plurality of partition plates 132, and a plurality of positioning rods 133. The receiving tube group includes a plurality of adjacent receiving tubes 131, and each receiving tube 131 is used for loading one spent fuel assembly. Corresponding to the outer peripheral shape of the spent fuel assembly, the receiving tube 131 is a square tube.

[0058] A plurality of partition plates 132 are sleeved on the receiving tube group and are spaced apart along the axial direction of the receiving tube group. A plurality of positioning rods 133 are spaced apart circumferentially along the partition plates 132, penetrate through all the partition plates 132 and are supported on the bottom plate 11 to position the axially spaced partition plates 132. Each partition plate 132 is provided with a plurality of through holes 130, and one through hole 130 is used for one receiving tube 131 to pass through; the number and arrangement of the through holes 130 on the partition plate 132 correspond to the number and arrangement of the receiving tubes 131.

[0059] In the fuel basket 13, a gap is left between the lowermost partition plate 132 and the bottom plate 11 to form a bottom space; the height of the gap can be 5 cm to 20 cm. Each receiving tube 131 is provided with a notch 1311 on the lower end side wall close to the bottom plate 11, and the depth of the notch 1311 is less than the height of the gap. At least one through hole 1321 is opened at a position on the partition plate 132 outside the receiving tube group, and the bottom space communicates with the notch 1311 and the through hole 1321 on the partition plate 132 adjacent to the bottom plate 131. The through holes 1321 on all the partition plates 132 are connected up and down and are connected to the notch 1311 through the bottom space, forming a gas up and down convection circulation channel on the fuel basket 13.

[0060] The through holes 1321 may have different shapes, numbers, and areas according to different positions on the partition plate.

[0061] Another example is Figure 3As shown, the fuel basket 13 may further include a shroud assembly 18 disposed at least between partitions 132 surrounding the lower end of the fuel basket 13. The shroud assembly 18 is disposed between two adjacent partitions 132 and is located on the periphery of the receiving tube group, capable of supporting the partitions 132 and strengthening the structural strength of the fuel basket 13. The shroud assembly 18 is also provided with channel holes (not shown) corresponding to the through holes, and the channel holes are directly opposite and communicated with the through holes to ensure the up-and-down convection and circulation of the air flow.

[0062] As Figure 6 shown, the drainage module 14 may include a first body 141, a duct 142, a quick connector 143, a transition drainage member 144, a siphon 145, etc. The first body 141 can be fixed within the cylinder wall 12 by welding or the like and is located above the fuel basket 13. The duct 142 is disposed inside the first body 141, extends along the height of the first body 141 within the first body 141, and penetrates through the upper and lower ends of the first body 141. The quick connector 143 is connected to the upper end of the duct 142 and is communicated with the duct 142. One end of the transition drainage member 144 is connected to the quick connector 143, and the end of the transition drainage member 144 away from the quick connector 143 faces the shielding protection container 20 and is connected to the drainage assembly 40. The siphon 145 is connected to the lower end of the duct 142, and the siphon 145 extends towards the bottom plate within the cylinder wall 12.

[0063] Preferably, the duct 142 may be arranged in a Z shape within the first body 141. A groove 140 may be formed in the upper part of the first body 141, the groove 140 communicates with the upper end of the duct 142 and is located on the periphery of the upper end, and the quick connector 143 is fitted within the groove 140 and is connected and communicated with the duct 142. The lower end of the duct 142 may be connected to the siphon 145 by means of a threaded fit.

[0064] The transition drainage member 144 may be a transition drainage pipe, with plugs installed at both ends respectively for connecting and adapting to the quick connector 143 and the drainage assembly 40. For example, the quick connector 143 is a female head, and the plug on the transition drainage member is a male head, and the two can achieve quick docking.

[0065] During drainage, the water inside the bottom penetration member 200 and inside the spent fuel storage tank 10 can be drained upward through the bottom of the siphon 145, enter the transition drainage member 144 and then enter the drainage assembly 40 for external discharge, capable of emptying the water stored between the high-position bottom penetration member 200 and the low-position spent fuel storage tank 10, so that the bottom penetration member 200 can be safely detached from the spent fuel storage tank 10, avoiding abnormal accident situations where radioactive liquid is not emptied and leaks to the external environment.

[0066] Corresponding to the inflation requirement, the spent fuel storage tank 10 may further include an inflation module 15. Through the inflation module 15, the inside of the spent fuel storage tank 10 can be inflated (such as with inert gases like helium). As an option, the inflation module 15 may include a second seat body; the second seat body can be fixed inside the cylinder wall 12 by welding or other means and is located above the fuel basket 13. An inflation channel penetrating through the upper and lower ends of the second seat body is provided on the second seat body. The inflation channel is used to connect to an external gas source and allow gas to enter the inside of the spent fuel storage tank 10.

[0067] In Figure 3 In the illustrated embodiment, the drainage module 14 and the inflation module 15 are respectively located on the opposite inner sides of the cylinder wall 12. Taking the cylinder wall 12 as a cylinder as an example, the connection line of the drainage module 14 and the inflation module 15 is a straight line passing through the center of the cylinder.

[0068] After loading the spent fuel assembly, the spent fuel storage tank 10 needs to form a closed storage tank to seal the spent fuel assembly inside. For this, the spent fuel storage tank 10 further includes a cover plate assembly for closing the top of the cylinder wall 12.

[0069] Referring to Figure 3 , the cover plate assembly includes a first sealing cover plate 16 and a second sealing cover plate 17. The first sealing cover plate 16 is fitted to the top of the cylinder wall 12, and the second sealing cover plate 17 is fitted on the first sealing cover plate 16. Among them, first notches 161 and 162 are further provided at the edge of the first sealing cover plate 16; the first notch 161 corresponds to being above the drainage module 14, and the second notch 162 corresponds to being above the inflation module 15, which is beneficial for clear and accurate centering and positioning when hoisting the first sealing cover plate 16. The second sealing cover plate 17 is a complete cover plate compared to the first sealing cover plate 16 and can be fitted to the first sealing cover plate 16 as a whole while covering the first notch 161 and the second notch 162.

[0070] In terms of thickness, the thickness of the first sealing cover plate 16 is greater than that of the second sealing cover plate 17, that is: the first sealing cover plate 16 is a thick-walled metal cover plate compared to the second sealing cover plate 17, and the second sealing cover plate 17 is a thin-walled metal cover plate in comparison.

[0071] After the spent fuel storage tank 10 loads the spent fuel assembly, it is closed by installing the cover plate assembly to the top of the cylinder wall 12. During installation, first, the first sealing cover plate 16 is centered and fitted to the top of the cylinder wall 12 and then welded and sealed. Then, the second sealing cover plate 17 is fitted to the first sealing cover plate 16 and welded and sealed to form a redundant sealing structure.

[0072] Such as Figure 1 and Figure 7As shown, the shielding protection container 20 is fitted outside the spent fuel storage tank 10, including being higher than the spent fuel storage tank 10 in terms of height, serving as the external shielding structure of the spent fuel storage tank 10. To achieve a tight fit and sealed docking with the bottom penetration piece, the top end face of the shielding protection container 20 protruding above the spent fuel storage tank 10 is provided with a pressing sealing surface 201 for tightly fitting with the bottom penetration piece 200, and at the same time connecting the bottom penetration piece 200 to the inner cavity of the spent fuel storage tank 10 located inside the shielding protection container 20.

[0073] The shielding protection container 20 may further include a base 21, a first cylinder 22, a second cylinder 23, a third cylinder 24, and a docking flange 25. The first cylinder 22, the second cylinder 23, and the third cylinder 24 are respectively connected to the base 21 and sleeved from the inside out in sequence, that is, the first cylinder 22 is in the innermost side, the third cylinder 24 is in the outermost side, and is sleeved around the second cylinder 23. The docking flange 25 is fixedly connected to the tops of the first cylinder 22, the second cylinder 23, and the third cylinder 24 by welding or other means; the annular cavity between the first cylinder 22 and the second cylinder 23 is used to fill a lead layer, and the lead layer is filled in the annular cavity between the first cylinder 22 and the second cylinder 23 to improve the shielding protection ability against the gamma rays generated by the spent fuel assemblies loaded in the built-in spent fuel storage tank 10. The annular cavity between the second cylinder 23 and the third cylinder 24 is used to fill demineralized water, and the demineralized water is used to undertake the shielding protection ability against the neutrons generated by the spent fuel assemblies loaded in the spent fuel storage tank 10.

[0074] The pressing sealing surface 201 is arranged on the top surface of the docking flange 25. The top surface of the docking flange 25 is also provided with a top cover sealing surface 202 for cooperating with the top cover 26 to close the top of the shielding protection container 20 through the top cover 26.

[0075] As Figure 8 shown in the embodiment, the top surface of the docking flange 25 is a stepped surface, the top cover sealing surface 202 is connected to the periphery of the pressing sealing surface 201 and is above the pressing sealing surface 201, so that the pressing sealing surface 201 is the lower annular surface relative to the top cover sealing surface 202. The pressing sealing surface 201 is a 100% smooth and flat annular horizontal plane. By tightly pressing and fitting with the pressing flange surface of the bottom penetration piece 200, it is ensured that during the entire hoisting and loading operation process of the spent fuel assembly from the inside of the water pool to the bottom penetration piece 200 and then to the inside of the shielding protection container 20, the entire boundary from the shielding protection container 20 to the bottom penetration piece 200 is in a sealed containment state, and there will be no leakage problems of the water pool water body or radioactive substances.

[0076] In some embodiments, the shielding protection container 20 further includes a plurality of circumferential stiffeners 27 disposed in the annular cavity between the second cylinder 23 and the third cylinder 24. The plurality of circumferential stiffeners 27 are arranged at intervals along the height direction of the shielding protection container 20 in the annular cavity. The arrangement of the circumferential stiffeners 27 improves the structural strength of the third cylinder 24 and the second cylinder 23. After filling with demineralized water, the demineralized water fills the chambers defined by the respective circumferential stiffeners 27.

[0077] The shielding protection container 20 may further include a top cover 26 for mating with the docking flange 25, fitting on the top cover sealing surface 202 to seal the shielding protection container 20. The top cover 26 can be fixedly installed on the docking flange 25 through a plurality of bolt assemblies. When the spent fuel assembly needs to be transported, the top cover 26 is removed from the docking flange 25.

[0078] To facilitate operations such as hoisting and flipping of the shielding protection container 20, the shielding protection container 20 further includes at least one upper trunnion 28 protruding outside the upper end of the third cylinder 24 and at least one lower trunnion 29 protruding outside the lower end of the third cylinder 24. Preferably, there are at least two upper trunnions 28 protruding on the opposite sides of the upper end of the third cylinder 24; there are at least two lower trunnions 29 protruding on the opposite sides of the lower end of the third cylinder 24.

[0079] In a preferred embodiment, the bottom of the upper trunnion 28 is embedded or fixed to the second cylinder 23 by welding or the like, and the top passes through the third cylinder 24 and protrudes on the outer surface of the third cylinder 24; the upper trunnion 28 is used to connect with a hoisting device to realize hoisting and lowering of the entire shielding protection container 20. The bottom of the lower trunnion 29 is embedded or fixed to the second cylinder 23 by welding or the like, and the top passes through the third cylinder 24 and protrudes on the outer surface of the third cylinder 24; the lower trunnion 29 can be used to support the shielding protection container 20 to be flipped from a vertical state to a horizontal state.

[0080] Reference Figure 7 and Figure 8, the drainage assembly 40 may include a drainage channel 43 disposed within the docking flange 25, a first drainage connector 41 and a second drainage connector 42 respectively connected to both ends of the drainage channel 43. The drainage channel 43 extends radially within the docking flange 25, and the extension form of the drainage channel 43 may be, but is not limited to, a Z shape. One end of the drainage channel 43 faces the inner circumferential direction of the docking flange 25, and the other end faces the outer circumferential direction of the docking flange 25. A drainage suction hole communicating with the drainage channel 43 is provided on the inner circumferential surface of the docking flange 25. The first drainage connector 41 is disposed within the drainage suction hole and connected to the drainage channel 43. A drainage outlet hole communicating with the drainage channel 43 is provided on the outer circumferential surface of the docking flange 25. The second drainage connector 42 is disposed within the drainage outlet hole and connected to the drainage channel 43. The second drainage connector 42 is exposed outside the outer circumference of the docking flange 25 through the drainage outlet hole for connecting an external drainage pipe 44.

[0081] The first drainage connector 41 is also used to connect to the transition drainage member 144 of the drainage module 14. The plug corresponding to the transition drainage member 144 is a male head, and the first drainage connector 41 is a female head adapted thereto to achieve quick docking. The second drainage connector 42 may also be a female head to achieve quick connection with the drainage pipe 44.

[0082] Further, according to the installation position of the drainage module 14 on the spent fuel storage tank 10 and the installation position of the drainage assembly 40 on the docking flange 25, the transition drainage member 144 may be, but is not limited to, bent at 90°, with one end facing the quick connector 143 to connect to the quick connector, and the other end facing the first drainage connector 41 to connect to the first drainage connector 41.

[0083] The spent fuel storage device of the present invention is used for the transfer of spent fuel assemblies. Therefore, the usage method of the spent fuel storage device also corresponds to a spent fuel transfer method. Combining the above spent fuel storage device and referring to Figure 1 , Figures 8 to 10 , the spent fuel transfer method may include the following steps:

[0084] S1. Transport the spent fuel storage device below the bottom penetration 200 of the pool, and lift the spent fuel storage device by a jacking device so that the pressing and sealing surface 201 of its shielding protection container 20 is closely attached to the pressing flange surface of the bottom penetration 200. The bottom penetration 200 is at the bottom of the spent fuel pool, and the top cover 210 of the bottom penetration 200 is in a horizontal sealed state, as shown in Figure 9 .

[0085] In some embodiments, step S1 includes:

[0086] S1.1. With the top of the shielding protection container 20 in an open state, hoist and place the spent fuel storage tank 10 into the shielding protection container 20, and remove the first sealing cover plate 16 and the second sealing cover plate 17 of the spent fuel storage tank 10.

[0087] Understandably, the first sealing cover plate 16 and the second sealing cover plate 17 can also be removed first, and then the spent fuel storage tank 10 can be hoisted and placed into the shielding protection container 20.

[0088] S1.2. Insert the sealing ring 30 into the upper part of the annular cavity between the spent fuel storage tank 10 and the shielding protection container 20 to form a sealed annular cavity; inflate to make the cavity of the sealing ring 30 in a compressed and sealed state.

[0089] The water level in the spent fuel pool is at a high level, or reaches a high level by filling with water.

[0090] S2. Fill the spent fuel storage tank 10 with water through the drainage component 40. After filling the spent fuel storage tank 10, continue to fill it into the bottom penetration member 200 until the water level rises to the top elevation position of the bottom penetration member 200.

[0091] Before filling with water, refer to Figure 6 and Figure 8 , connect the drainage component 40 to the drainage module 14, and the connection operation is as follows: Insert the lower end plug of the transition drainage member 144 into the quick connector 143, insert the upper end plug of the transition drainage member 144 into the first drainage connector 41, and the second drainage connector 42 is externally connected to the drainage pipe 44.

[0092] When filling with water, the water enters the drainage hole channel 43 from the drainage pipe 44, then enters the transition drainage member 144 and enters the siphon 145 through the hole channel 142 of the drainage module 14, and enters the spent fuel storage tank 10 from the siphon 145.

[0093] S3. Continue to fill the spent fuel storage tank 10 with water until the pressures on both sides of the top cover 210 of the bottom penetration member 200 (i.e., the inner side of the bottom penetration member 200 and the side where the spent fuel pool is located) are balanced.

[0094] S4. Open the top cover 210 of the bottom penetration member 200 to a vertical state, and load the spent fuel assembly 100 from the pool into the spent fuel storage tank 10 along the bottom penetration member 200, as Figure 1 shown.

[0095] The spent fuel assembly 100 enters the fuel basket 13 of the spent fuel storage tank 10 for positioning.

[0096] S5. After completing the loading of the spent fuel assembly 100, close the top cover 210 of the bottom penetration member 200, as Figure 10 shown.

[0097] The top cover 210 of the bottom-penetrating component 200 of the pool flips from a vertical state to a horizontal state, closing the bottom-penetrating component 200 of the pool. At this time, the connection between the spent fuel storage tank 10 and the spent fuel pool is also disconnected.

[0098] S6. Drain the water in the spent fuel storage tank 10 through the drainage assembly 40 until the water level drops to the elevation position at the top of the spent fuel storage tank 10.

[0099] Refer to Figure 6 and Figure 8 , the drainage flow is as follows: The water enters the channel 142 of the drainage module 14 through the siphon 145, and successively passes through the transition drainage component 144 and the drainage channel 43 into the drain pipe 44, continuously draining the water until the water level drops to the elevation at the top of the fuel basket 13 inside the spent fuel storage tank 10.

[0100] S7. After the spent fuel storage device with the spent fuel assembly is detached from the bottom-penetrating component 200 of the pool, close the top of the spent fuel storage tank 10 and inflate the inside of the spent fuel storage tank 10.

[0101] Refer to Figures 1 to 3 , as an option, a hydraulic device can be used to separate the compression sealing surface 201 of the shielding protection container 20 from the compression flange surface of the bottom-penetrating component 200 of the pool, and transfer the entire spent fuel storage device to the operation area outside the bottom-penetrating component 200 of the pool. Remove the sealing ring 30 in the annular cavity between the spent fuel storage tank 10 and the shielding protection container 20, hoist the first sealing cover plate 16 above the spent fuel storage tank 10, align it and place it on the top of the spent fuel storage tank 10 and weld it in place. Inflate the inside of the spent fuel storage tank 10 (such as helium) through the inflation module 15, hoist the second sealing cover plate 17 onto the first sealing cover plate 16 and weld it in place.

[0102] S8. Transport the spent fuel storage device to the storage area, and take out the spent fuel storage tank 10 with the spent fuel assembly from the shielding protection container 20 for storage.

[0103] The operation of this step S8 is as follows: After transporting the spent fuel storage device to the storage area, open the bottom of the shielding protection container 20, and take out the spent fuel storage tank 10 with the spent fuel assembly from the shielding protection container 20 for storage.

[0104] After completing the loading, transportation and storage of a spent fuel storage tank 10 with a spent fuel assembly, the shielding protection container 20 can continue to be placed into another spent fuel storage tank 10, and then transported below the bottom-penetrating component 200 of the pool for a new round of transfer of the spent fuel assembly, that is, repeat steps S1 - S8.

[0105] The above are only embodiments of the present invention, and do not thereby limit the patent scope of the present invention. Any equivalent structural or equivalent process transformations made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A spent fuel storage device, characterized in that: Used to dock with the pool bottom penetration piece, the spent fuel storage device includes a spent fuel storage tank, a shielding protection container, a sealing ring and a drainage assembly; The spent fuel storage tank is installed inside the shielding protection container and is used to accommodate the spent fuel assembly. The sealing ring is arranged at the upper part of the annular cavity between the spent fuel storage tank and the shielding protection container, so that the annular cavity between the spent fuel storage tank and the shielding protection container forms a closed annular cavity; The top of the shielding protection container protrudes above the spent fuel storage tank, and the top end surface of the shielding protection container is provided with a compression sealing cover for tightly fitting with the pool bottom penetration piece; the drainage assembly is radially penetrated through the top of the shielding protection container and communicated with the inner cavity of the spent fuel storage tank.

2. The spent fuel storage device according to claim 1, characterized in that: The spent fuel storage tank comprises a bottom plate, a cylinder wall connected to the bottom plate, a fuel basket located in the cylinder wall, and a drainage module arranged in the cylinder wall; The drainage module includes a first seat body fixed in the cylinder wall and located above the fuel basket, a hole arranged in the first seat body, a quick connector connected to the upper end of the hole, a transition guide connected to the quick connector, and a siphon connected to the lower end of the hole; One end of the transition guide piece away from the quick connector faces the shielding protection container and is connected to the drainage assembly; the siphon tube extends in the cylinder wall toward the bottom plate.

3. The spent fuel storage device according to claim 2, characterized in that: The fuel basket includes a receiving tube group for placing spent fuel assemblies, a plurality of partitions, and a plurality of positioning rods; The receiving tube group includes a plurality of receiving tubes arranged adjacent to each other; a plurality of partitions are sleeved on the receiving tube group and are distributed at intervals along the axial direction of the receiving tube group; a plurality of positioning rods are distributed at intervals along the circumference of the partitions, are inserted through all the partitions and are supported on the bottom plate.

4. The spent fuel storage device according to claim 3, characterized in that: In the fuel basket, a gap is left between the lowermost partition and the bottom plate to form a bottom space; a groove is provided on the lower side wall of each receiving tube, and the depth of the groove is less than the height of the gap; At least one through hole is formed on the partition at a position outside the receiving tube group, and the bottom space is connected to the notch and the through hole on the partition adjacent to the bottom plate; All the through holes on the partitions are connected vertically and are connected to the notches through the bottom space, so that a gas vertical convection circulation channel is formed on the fuel basket.

5. The spent fuel storage device according to claim 2, characterized in that: The spent fuel storage tank further comprises an inflation module; the inflation module comprises a second seat body fixed in the cylinder wall and located above the fuel basket, and the second seat body is provided with an inflation passage penetrating the second seat body.

6. The spent fuel storage device according to claim 5, characterized in that: The spent fuel storage tank also includes a first sealing cover plate and a second sealing cover plate; The first sealing cover plate is matched with the top of the cylinder wall, and a first notch and a second notch are also provided at the edge of the first sealing cover plate; the first notch corresponds to the top of the drainage module, and the second notch corresponds to the top of the inflation module; the second sealing cover plate is matched with the first sealing cover plate.

7. The spent fuel storage device according to claim 1, characterized in that: The shielding protection container comprises a base, a first cylinder, a second cylinder, a third cylinder and a docking flange; The first cylinder, the second cylinder and the third cylinder are respectively connected to the base and are sequentially sleeved from the inside to the outside; the docking flange is connected to the top of the first cylinder, the second cylinder and the third cylinder; The annular cavity between the first cylinder and the second cylinder is used to fill the lead layer, and the annular cavity between the second cylinder and the third cylinder is used to fill the desalted water; The compression sealing surface is arranged on the top surface of the butt flange.

8. The spent fuel storage device according to claim 7, characterized in that: The shielding protection container also includes a plurality of annular ribs arranged in the annular cavity between the second cylinder and the third cylinder, and / or a lead layer filled in the annular cavity between the first cylinder and the second cylinder, and / or desalted water filled in the annular cavity between the second cylinder and the third cylinder.

9. The spent fuel storage device according to claim 7, characterized in that: The top surface of the butt flange is also provided with a top cover sealing surface; the top cover sealing surface is connected to the periphery of the compression sealing surface and is located above the compression sealing surface.

10. The spent fuel storage device according to claim 7, characterized in that: The shielding protection container also includes a top cover used to fit on the docking flange to seal the shielding protection container.

11. The spent fuel storage device according to claim 7, characterized in that: The shielding protection container further includes at least one upper ear shaft protruding from the outer side of the upper end of the third cylinder and at least one lower ear shaft protruding from the outer side of the lower end of the third cylinder.

12. The spent fuel storage device according to any one of claims 7 to 11, characterized in that: The drainage assembly includes a drainage channel arranged in the docking flange, a first drainage joint and a second drainage joint respectively connected to both ends of the drainage channel; The inner circumferential surface of the docking flange is provided with a drainage suction hole connected to the drainage channel, and the outer circumferential surface of the docking flange is provided with a drainage outlet hole connected to the drainage channel; The first drainage joint is arranged in the drainage suction hole, the second drainage joint is arranged in the drainage outlet hole, and the second drainage joint is used for connecting to an external drainage pipe.

13. A spent fuel transfer method, characterized in that: Using the spent fuel storage device according to any one of claims 1 to 12, the spent fuel transfer method comprises the following steps: S1. Transport the spent fuel storage device to below the pool bottom penetration piece, and lift up the spent fuel storage device by a lifting device, so that the compression sealing surface of the shielding protection container is closely fitted with the compression flange surface of the pool bottom penetration piece; the top cover of the pool bottom penetration piece is in a horizontal sealing state; S2. Filling the spent fuel storage tank with water through the drainage assembly until the water level rises to the top elevation of the tank bottom penetration piece; S3, continue to fill the spent fuel storage tank with water until the pressure on both sides of the top cover of the pool bottom penetration is balanced; S4, opening the top cover of the pool bottom penetration piece to a vertical state, and loading the spent fuel assembly from the water pool down along the pool bottom penetration piece into the spent fuel storage tank; S5. After the loading of the spent fuel assembly is completed, the top cover of the pool bottom penetration is closed; S6, draining the water in the spent fuel storage tank through the drainage assembly until the water level drops to the elevation position of the top of the spent fuel storage tank; S7, after the spent fuel storage device with the spent fuel assembly is separated from the pool bottom penetration piece, the top of the spent fuel storage tank is closed and the spent fuel storage tank is inflated; S8. The spent fuel storage device is transferred to the storage area, and the spent fuel storage tank with the spent fuel assembly is taken out from the shielding protection container for storage.

14. The spent fuel transfer method according to claim 13, characterized in that: Step S1 includes: S1.

1. Place the spent fuel tank hoist in the shielding protection container, and remove the first sealing cover plate and the second sealing cover plate of the spent fuel tank; S1.

2. A sealing ring is embedded in the upper part of the annular cavity between the spent fuel storage tank and the shielding protection container to form a closed annular cavity; the closed annular cavity is inflated to put the sealed annular cavity in a compressed and sealed state.

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