Spent fuel cooling system, spent fuel storage cooling system and method and spent fuel transportation cooling system

Abstract

The invention discloses a spent fuel cooling system, a spent fuel storage cooling system and method and a spent fuel transportation cooling system. The spent fuel cooling system comprises an external cooling device and an internal cooling device. The external cooling device comprises a cooling bag wrapping the spent fuel storage container, a water filling loop line and a water draining loop line, wherein the cooling bag is sleeved with the water filling loop line and the water draining loop line, and the water filling loop line and the water draining loop line are connected and communicated with the cooling bag. The internal cooling device comprises a first water filling pipeline connected with the gas filling hole in the spent fuel storage container and a first water discharging pipeline connected with the water discharging hole in the spent fuel storage container. According to the spent fuel cooling system, the spent fuel storage container is cooled through the external cooling device, the internal cooling device and the like, the temperature of water in the spent fuel storage container is controlled to be within a safety limit value with heat released by the spent fuel assembly, emergency cooling can be carried out under the condition that equipment breaks down and stops running, and the service life of the equipment is prolonged. And the thermal safety and the sealing containing safety of the spent fuel storage container are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear fuel storage, and particularly relates to a spent fuel cooling system, a spent fuel storage cooling system and method, and a spent fuel transportation cooling system. Background Art

[0002] After the nuclear reactor fuel goes through a certain cycle in the reactor core, due to its large heat release and high radioactivity level, it must be promptly removed and stored in a spent fuel pool for cooling. Since the capacity of the spent fuel pool is limited and the spent fuel reprocessing capacity of the reprocessing plant is insufficient, both at home and abroad, emphasis is placed on adopting the dry storage method for spent fuel to solve the problem of off-reactor storage of spent fuel.

[0003] The existing dry storage technology for spent fuel is as follows: in the fuel building of a nuclear power plant, first, an empty spent fuel storage tank is hoisted into the inner cavity of a transfer container, and then the assembly of the two is hoisted underwater for loading. After loading, it is hoisted into a cleaning well, the top cover plate is installed, and operations such as welding and sealing with an automatic welding machine, vacuum drying, and helium filling are carried out. Then, the spent fuel storage tank is transported to the storage area through the transfer container, and the spent fuel storage tank is taken out from the inner part of the transfer container and stored in a concrete module for long-term storage. Although the existing technology can complete the function of loading spent fuel in the fuel building, how to ensure the thermal safety and sealed containment safety of spent fuel under the long-term failure mode of the automatic welding machine and vacuum drying equipment has always been a bottleneck problem restricting the loading safety of dry storage of spent fuel, which is prominently manifested as follows:

[0004] (1) Under the long-term failure mode of the equipment, the fuel cladding continuously heats up and exceeds the thermal safety limit;

[0005] (2) The high-temperature steam in the annular cavity affects the automatic welding imaging operation of the remote HMI (human-machine interface);

[0006] (3) The high-temperature steam in the storage tank affects the quality of the welding molten pool and the sealed containment safety of the container. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a spent fuel cooling system, a spent fuel storage cooling system and method with this spent fuel cooling system, and a spent fuel transportation cooling system with this spent fuel cooling system.

[0008] The technical solution adopted by the present invention to solve its technical problems is: to provide a spent fuel cooling system, including an external cooling device for cooling the outside of the spent fuel storage container and an internal cooling device for cooling the inner cavity of the spent fuel storage container;

[0009] The external cooling device includes a cooling bladder wrapped around the outside of the spent fuel storage container, a water filling loop and a drainage loop respectively sleeved on the outside of the cooling bladder. The water filling loop and the drainage loop are respectively connected and communicated with the cooling bladder. The first cooling medium enters the cooling bladder through the water filling loop and then is discharged from the drainage loop, taking away the heat dissipated from the outside of the spent fuel storage container.

[0010] The internal cooling device includes a first water filling pipeline connected to the gas filling hole on the spent fuel storage container and a first drainage pipeline connected to the drainage hole on the spent fuel storage container. The second cooling medium enters the inner cavity of the spent fuel storage container through the first water filling pipeline and then is discharged from the first drainage pipeline to replace and cool the boron-containing water in the inner cavity of the spent fuel storage container.

[0011] In some embodiments, the cooling bladder includes a plurality of relatively independent cooling bladder monomers, and the plurality of cooling bladder monomers are arranged along the outer circumference of the spent fuel storage container and are attached to the outer surface of the spent fuel storage container.

[0012] In some embodiments, the water filling loop includes a water filling ring sleeved at the lower end of the cooling bladder, a plurality of water filling branch pipes, and a water filling pipe connected to the water filling ring and used for accessing the first cooling medium. The plurality of water filling branch pipes are arranged at intervals along the circumferential direction of the water filling ring and are connected between the water filling ring and the corresponding cooling bladder monomer.

[0013] In some embodiments, the drainage loop includes a drainage ring sleeved at the upper end of the cooling bladder, a plurality of drainage branch pipes, and a drainage pipe connected to the drainage ring and used for discharging the first cooling medium. The plurality of drainage branch pipes are arranged at intervals along the circumferential direction of the drainage ring and are connected between the drainage ring and the corresponding cooling bladder monomer.

[0014] In some embodiments, the external cooling device further includes a support collar. The support collar is used to be sleeved on the outer circumference of the spent fuel storage container, and the cooling bladder is connected around the support collar.

[0015] In some embodiments, the spent fuel cooling system further includes an annular cavity cooling device for cooling the annular cavity of the spent fuel storage container.

[0016] The annular cavity cooling device includes a second water filling pipeline and a second drainage pipeline respectively communicated with the annular cavity. The third cooling medium enters the annular cavity through the second water filling pipeline and then is discharged from the second drainage pipeline to replace and cool the high-temperature water in the annular cavity.

[0017] The present invention also provides a spent fuel storage cooling system, including a spent fuel storage tank for loading spent fuel assemblies, a transfer container, and a spent fuel cooling system.

[0018] The spent fuel storage tank is assembled inside the transfer container, and an annular cavity is formed between the outer periphery of the spent fuel storage tank and the inner periphery of the transfer container; the spent fuel cooling system includes an external cooling device, an internal cooling device, and an annular cavity cooling device;

[0019] The external cooling device includes a cooling bladder wrapped around the outside of the transfer container, a water filling loop and a water drainage loop respectively sleeved outside the cooling bladder, the water filling loop and the water drainage loop are respectively connected and communicated with the cooling bladder, and a first cooling medium enters the cooling bladder through the water filling loop and then is discharged from the water drainage loop, taking away the heat dissipated from the outside of the transfer container;

[0020] The internal cooling device includes a first water filling pipeline connected to the inflation hole on the spent fuel storage tank and a first water drainage pipeline connected to the drainage hole on the spent fuel storage tank; a second cooling medium enters the inner cavity of the spent fuel storage tank through the first water filling pipeline and then is discharged from the first water drainage pipeline to replace and cool the boron-containing water in the inner cavity of the spent fuel storage tank;

[0021] The annular cavity cooling device includes a second water filling pipeline and a second water drainage pipeline respectively communicated with the annular cavity; a third cooling medium enters the annular cavity through the second water filling pipeline and then is discharged from the second water drainage pipeline to replace and cool the high-temperature water in the annular cavity.

[0022] In some embodiments, an upper trunnion and a lower trunnion are respectively provided at the upper end and the lower end of the outer surface of the transfer container;

[0023] The external cooling device is located between the upper trunnion and the lower trunnion outside the transfer container.

[0024] The present invention also provides a cooling method for a spent fuel storage and cooling system, including the following steps:

[0025] S1. When the automatic welding system and the vacuum drying system of the spent fuel storage tank fail and stop operating, continuously monitor the temperature of the demineralized water in the annular cavity between the spent fuel storage tank and the transfer container;

[0026] S2. When the temperature of the demineralized water in the annular cavity exceeds the water temperature safety limit value, turn on the annular cavity cooling device to make the water inflow rate into the annular cavity through the second water filling pipeline equal to the water drainage rate out of the annular cavity through the second water drainage pipeline;

[0027] S3. Start the external cooling device, fill the cooling bladder with low-temperature demineralized water through the water filling loop and discharge it from the water drainage loop;

[0028] S4. The ring cavity cooling device and the external cooling device continue to operate, and continuously detect the temperature of the demineralized water in the ring cavity. When the temperature of the demineralized water does not meet the water temperature safety limit, the internal cooling device is started to replace and cool the boron-containing water in the inner cavity of the spent fuel storage tank until the temperature of the demineralized water meets the safety limit.

[0029] The present invention also provides a spent fuel transportation cooling system, which includes a transportation container for loading spent fuel assemblies and a spent fuel cooling system; the spent fuel cooling system includes an external cooling device and an internal cooling device.

[0030] The external cooling device includes a cooling bladder wrapped outside the transportation container, a water filling loop and a drainage loop respectively sleeved outside the cooling bladder. The water filling loop and the drainage loop are respectively connected and communicated with the cooling bladder. The first cooling medium enters the cooling bladder through the water filling loop and then discharges from the drainage loop, taking away the heat dissipated outside the transportation container.

[0031] The internal cooling device includes a first water filling pipeline connected to the inflation hole on the transportation container and a first drainage pipeline connected to the drainage hole on the transportation container; the second cooling medium enters the inner cavity of the transportation container through the first water filling pipeline and then discharges from the first drainage pipeline to replace and cool the boron-containing water in the inner cavity of the transportation container.

[0032] The beneficial effects of the present invention: Through the external cooling device and the internal cooling device, etc., the spent fuel storage container is cooled to take away the heat released by the spent fuel assemblies, and the water temperature in the spent fuel storage container is controlled within the safety limit. It can perform emergency cooling in case of equipment failure shutdown, ensuring the thermal safety and sealed containment safety of the spent fuel storage container. Description of the Drawings

[0033] The following will further illustrate the present invention in conjunction with the drawings. In the drawings:

[0034] Figure 1 is a schematic structural diagram of the spent fuel storage and cooling system according to an embodiment of the present invention in a cleaning well;

[0035] Figure 2 is Figure 1 a longitudinal sectional structural diagram of the shown system;

[0036] Figure 3 is Figure 1 a schematic structural diagram of the spent fuel storage container in ;

[0037] Figure 4 is Figure 3 a schematic structural diagram of the transfer container in ;

[0038] Figure 5 is Figure 1 a schematic structural view of the spent fuel cooling system in the middle;

[0039] Figure 6 is Figure 5 a schematic structural view of the cooling capsule in the middle;

[0040] Figure 7 is Figure 5 a schematic structural view of the water filling loop and the drainage loop in the middle;

[0041] Figure 8 is a schematic longitudinal sectional structure view of the spent fuel transportation cooling system according to an embodiment of the present invention. Detailed implementation manners

[0042] For a clearer understanding of the technical features, purposes, 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.

[0043] The spent fuel cooling system of the present invention is used to cooperate with a spent fuel storage container to cool the spent fuel storage container and drive the heat released by the spent fuel assembly to maintain the temperature within the safety limit. The spent fuel storage container can be a container for dry storage of spent fuel or a transportation container for loading spent fuel assemblies for transportation, etc.

[0044] As Figures 1 - 4 shown, the spent fuel cooling system according to an embodiment of the present invention includes an external cooling device 10 for cooling the outside of the spent fuel storage container, an internal cooling device 20 for cooling the inner cavity of the spent fuel storage container, and an annular cavity cooling device 30 for cooling the annular cavity of the spent fuel storage container.

[0045] In this embodiment, the spent fuel storage container may include a spent fuel storage tank 110 and a transfer container 120. The spent fuel storage tank 110 is assembled inside the transfer container 120, and an annular cavity 130 is formed between the outer periphery of the spent fuel storage tank 110 and the inner periphery of the transfer container 120. The arrangement of the spent fuel cooling system on the spent fuel storage container forms a spent fuel storage cooling system, which is applied to the dry storage technology of spent fuel. The spent fuel storage cooling system is arranged in the cleaning well 100 of the fuel building.

[0046] The spent fuel storage tank 110 is a thin-walled stainless steel cylinder structure for loading spent fuel assemblies. The spent fuel storage tank 110 is provided with structures such as an inflation hole 101, a drainage hole 102, and a drain pipe. The transfer container 120 is a thick-walled metal container that undertakes the functions of structure and shielding protection. The bottom of the transfer container 120 is provided with a drainage hole channel 105, the upper end of the outer surface of the transfer container 120 is provided with an upper trunnion 103, and the lower end of the outer surface of the transfer container 120 is provided with a lower trunnion 104.

[0047] The external cooling device 10 is assembled outside the transfer container 120 for cooling the outside of the transfer container 120 and taking away the heat dissipated from the outside of the transfer container 120. The external cooling device 10 is positioned between the upper trunnion 103 and the lower trunnion 104 outside the transfer container 120. While effectively cooling the outside of the transfer container 120, it does not cover the upper trunnion 103 and the lower trunnion 104 and does not affect the use of the upper trunnion 103 and the lower trunnion 104.

[0048] Specifically, in combination with Figure 1 、 Figure 2 and Figure 5 , the external cooling device 10 may include a cooling bladder 11, a water filling loop 12 and a drainage loop 13. The cooling bladder 11 is coated outside the transfer container 120, specifically on the outer surface of the transfer container 120; the water filling loop 12 and the drainage loop 13 are respectively sleeved outside the cooling bladder 11 and communicate with the cooling bladder 11. The first cooling medium enters the cooling bladder 11 through the water filling loop 12 and then discharges from the drainage loop 13. The first cooling medium can be demineralized water, which has the advantage of high water quality purity and can avoid corrosion and contamination of equipment components, pipelines, etc.

[0049] As Figure 2 、 Figures 5 - 7 shown, the cooling bladder 11 includes a number of relatively independent cooling bladder monomers 111; the number of cooling bladder monomers 111 are arranged along the outer circumference of the transfer container 120 and are attached to the outer surface of the transfer container 120. Each cooling bladder monomer 111 forms an independent cooling source and independently cools the attached outer surface. The cooling bladder monomer 111 is made of flexible non-metallic or metallic materials to form a flexible cooling module.

[0050] The water filling loop 12 includes a water filling ring 121, a number of water filling branch pipes 122 and a water filling pipe 123. The water filling ring 121 is sleeved outside the cooling bladder 11; the number of water filling branch pipes 122 are arranged at intervals along the circumference of the water filling ring 121 and are connected between the water filling ring 121 and the corresponding cooling bladder monomer 111 to connect the water filling loop 12 and the cooling bladder monomer 111. The water filling pipe 123 is connected to the water filling ring 121 for accessing the first cooling medium. The first cooling medium enters the water filling ring 121 through the water filling pipe 123, and then is distributed to each water filling branch pipe 122 along the water filling ring 121 and enters the cooling bladder monomer 111 along the water filling branch pipe 122.

[0051] The drainage loop 13 includes a drainage ring 131, a plurality of drainage branch pipes 132, and a drain pipe 133. The drainage ring 131 is sleeved outside the cooling bladder 11; the plurality of drainage branch pipes 132 are arranged at intervals along the circumference of the drainage ring 131 and are connected between the drainage ring 131 and the corresponding cooling bladder unit 111 to communicate the drainage ring 131 and the cooling bladder unit 111. The drain pipe 133 is connected to the drainage ring 131 and is used to discharge the first cooling medium. The first cooling medium in each cooling bladder unit 111 enters the drainage ring 131 through the respective connected drainage branch pipes 132, enters the drain pipe 133 along the drainage ring 131, and is discharged from the drain pipe 133.

[0052] To support and position the cooling bladder 11 outside the transfer container 120, the external cooling device 10 may further include at least one support collar 14. The support collar 14 is used to be sleeved on the outer circumference of the transfer container 120, and the cooling bladder 11 is circumferentially connected to the support collar 14. The support collar 14 plays a role in fixing the framework and positions the cooling bladder 11 and even the entire external cooling device 10 on the transfer container 120. To fit with the outer peripheral surface of the transfer container 120, one side of each cooling bladder unit 111 facing the transfer container 120 is an arc surface, and all the cooling bladder units 111 are concentrically and circumferentially fixed on the support collar 14.

[0053] It can be understood that a water filling valve may be provided on the water filling pipe 123 to control the water filling flow rate. One end of the water filling pipe 123 far from the water filling ring 121 may extend and be connected to the desalted water source of the nuclear power plant, and under the power provided by the water pump, the desalted water is pumped into the water filling ring 121. A drainage valve is provided on the drain pipe 133 to control the drainage flow rate; one end of the drain pipe 133 far from the drain pipe 133 may face or be placed in the cleaning well 100 to discharge the desalted water into the cleaning well 100.

[0054] Preferably, the water filling ring 121 is sleeved on the outer circumference of the lower end of the cooling bladder 11, and the drainage ring 131 is sleeved on the outer circumference of the upper end of the cooling bladder 11 to form a direct current circulating cooling form of low-position water filling and high-position drainage. The first cooling medium takes away the decay heat generated by the spent fuel assembly through the flow mode of lower filling and upper drainage (as shown by the arrows in the external cooling device 10 in Figure 2 ), and discharges it into the cleaning well 100 (the decay heat dissipation is as shown by the dotted arrow in Figure 2 ).

[0055] As Figure 2 , Figure 3 and Figure 5As shown, the internal cooling device 20 is connected to the spent fuel storage tank 110 and communicates with the inner cavity of the spent fuel storage tank 110 for cooling the inner cavity of the spent fuel storage tank 110. The internal cooling device 20 may specifically include a first water filling pipeline 21 and a first drainage pipeline 22; the first water filling pipeline 21 is connected to the gas filling hole 101 on the spent fuel storage tank 110, and the first drainage pipeline 22 is connected to the drainage hole 102 on the spent fuel storage tank 110. The second cooling medium enters the inner cavity of the spent fuel storage tank 110 through the first water filling pipeline 21 and then is discharged from the first drainage pipeline 22 to replace and cool the boron-containing water in the inner cavity of the spent fuel storage tank 110.

[0056] The second cooling medium is preferably boron-containing water used in a nuclear power plant, which is characterized by adding boric acid to water and undertakes the functions of absorbing and moderating neutrons generated by the fission of the spent fuel assembly.

[0057] It can be understood that valves are respectively provided on the first water filling pipeline 21 and the first drainage pipeline 22 to control the flow rate.

[0058] Generally, the gas filling hole 101 and the drainage hole 102 on the spent fuel storage tank 110 are both opened at the upper part (such as on the cover body), and the first drainage pipeline 22 can penetrate through the drainage hole 102 and extend into the lower part or the bottom of the spent fuel storage tank 110.

[0059] The internal cooling device 20 adopts the method of upper filling and upper discharging to drain the high-temperature boron-containing water inside the spent fuel storage tank 110 from the top of the spent fuel storage tank 110 at the same water filling flow rate (as shown by the arrow in the internal cooling device 20 in the figure), and the equal amount balance replacement and rapid cooling of the high-temperature boron-containing water ensure that the water body in the tank still has a relatively high boiling margin and will not be in the evaporation boiling state when entering the subsequent welding operation. At the same time, it also makes the water level inside the spent fuel storage tank 110 always in a stable water level state that submerges the spent fuel assembly, avoiding the increase of the radiation source intensity of the exposed spent fuel assembly due to the decrease of the water level and the increase of the collective dose of the operating personnel. At the same time, it can also avoid the large-area radioactive waste liquid contamination caused by the overflow of the water level from the top of the tank. Figure 2 As shown, the annular cavity cooling device 30 communicates with the annular cavity 130 between the spent fuel storage tank 110 and the transfer container 120 for cooling the annular cavity 130. The annular cavity cooling device 30 may further include a second water filling pipeline 31 and a second drainage pipeline 32 respectively communicating with the annular cavity 130; the third cooling medium enters the annular cavity 130 through the second water filling pipeline 31 and then is discharged from the second drainage pipeline 32 to replace and cool the high-temperature water in the annular cavity 130.

[0060] As Figure 2 and Figure 5 shown, the third cooling medium is preferably demineralized water, which is the same as the first cooling medium.

[0061] The third cooling medium is preferably demineralized water, which is the same as the first cooling medium.

[0062] One end of the second water filling pipeline 31 is connected to the upper part of the annular cavity 130, and the end far from the annular cavity 130 can extend and be connected to the desalted water source of the nuclear power plant. A valve may be provided on the second water filling pipeline 31 to control the water filling flow rate. The second drainage pipeline 32 is connected to the drainage hole 105 at the bottom of the transfer container 120, or the second drainage pipeline 32 is formed by the drainage hole 105 at the bottom of the transfer container 120. A valve may be provided on the second drainage pipeline 32 to control the drainage flow rate; the second drainage pipeline 32 discharges the third cooling medium into the cleaning well 100.

[0063] The annular cavity cooling device 30 injects low-temperature desalted water into the upper part of the annular cavity 130 in an upper-filling and lower-draining manner (as shown by the arrows in the annular cavity cooling device 30 Figure 2 shown), synchronously connects a drainage pipeline to the drainage hole 105 at the bottom of the transfer container 120, controls the discharge flow rate through a valve, discharges the accumulated high-temperature water body in the annular cavity 130 to the cleaning well 100, realizes the removal of the decay heat of the spent fuel, ensures that the water body in the annular cavity 130 is in a low-temperature state, and avoids the formation of high-temperature steam dispersion due to rapid evaporation and boiling, which affects the imaging of the camera of the automatic welding machine and the adjustment of the remote welding process operation.

[0064] In the aspect of dry storage of spent fuel in the spent fuel storage cooling system, first, the spent fuel storage tank 110 is hoisted and placed in the inner cavity of the supporting transfer container 120, and an annular cavity 130 is formed therebetween. An airtight seal is performed by using a sealing ring at the top of the annular cavity 130, and then the transfer container 120 is hoisted and placed in the spent fuel pool. Each spent fuel assembly is successively hoisted and placed inside the spent fuel storage tank 110 underwater, and then the top cover plate of the spent fuel storage tank 110 is hoisted and installed. Finally, the transfer container 120 is hoisted and placed in the cleaning well 100, and the annular cavity seal ring is removed. At this time, the inside of the spent fuel storage tank 110 is filled with boron-containing water from the spent fuel pool and completely immerses the spent fuel assemblies.

[0065] Reference Figure 1 、 Figure 2 and Figure 5 , in some embodiments, after loading the spent fuel assemblies, the cooling method of the spent fuel storage cooling system includes the following steps:

[0066] S1. During the failure of the loading operation equipment, continuously monitor the temperature of the desalted water in the annular cavity 130 between the spent fuel storage tank 110 and the transfer container 120.

[0067] Among them, the loading operation equipment includes the automatic welding system for spent fuel tanks and the vacuum drying system; these systems are existing systems in the nuclear power plant, and will not be elaborated here. During the failure of the loading operation equipment, that is, during the period when the automatic welding system for spent fuel tanks and the vacuum drying system malfunction and abort the operation.

[0068] For the water in the annular cavity, in the long-term fault interruption operation mode of the equipment, under the long-term heat release of the spent fuel assembly, it is extremely easy to boil and form a large amount of steam under continuous heating. A large amount of steam will interfere with the clear imaging of the camera of the automatic welding machine, making it difficult for the operator to adjust the welding process parameters in a timely manner according to the situation of the welding molten pool. Only frequent interruption of operations and close adjustment of the welding station are possible, increasing the welding operation time and the radiation dose of the personnel. Therefore, for the above-mentioned extremely likely situation, it is necessary to continuously and real-time detect the temperature in the annular cavity 130, that is, the temperature of the demineralized water in the annular cavity 130, so as to perform corresponding cooling treatment in a timely manner.

[0069] S2. When the temperature of the demineralized water in the annular cavity 130 exceeds the water temperature safety limit value (such as the 400 °C safety temperature limit value of the fuel cladding), turn on the annular cavity cooling device 30 to make the water inflow into the annular cavity 130 through the second water filling pipeline 31 equal to the water discharge amount discharged from the annular cavity 130 through the second drainage pipeline 32 (or the drainage hole 105).

[0070] S3. Start the external cooling device 10, fill the cooling bladder 11 with low-temperature demineralized water through the water filling loop 12, and discharge it from the drainage loop 13.

[0071] When starting the external cooling device 10, the specific operation is as follows: first, open the valve on the drainage loop 13 to connect the drainage loop 13 with the surrounding atmosphere; open the valve on the water filling loop 12 to make the water suction port of the water pump in a filled state; start the water pump, fill the cooling bladder 11 with low-temperature demineralized water through the water filling loop 12, and continuously discharge it from the drainage loop 13 to the floor drain in the cleaning well 100.

[0072] S4. The annular cavity cooling device 30 and the external cooling device 10 continue to operate, and continuously detect the temperature of the demineralized water in the annular cavity 130. When the remaining amount of the demineralized water temperature is insufficient or does not meet the water temperature safety limit value, start the internal cooling device 20 to replace and cool the boron-containing water in the inner cavity of the spent fuel storage tank 110 until the demineralized water temperature meets the water temperature safety limit value.

[0073] Reference Figure 8 , the spent fuel cooling system of another embodiment of the present invention includes an external cooling device 10 for cooling the outside of the spent fuel storage container and an internal cooling device 20 for cooling the inner cavity of the spent fuel storage container.

[0074] The spent fuel storage container includes a transport container 140, and the transport container 140 is used to load the spent fuel assembly.

[0075] In Figure 8In the present embodiment shown, the transport container 140 is a thick-walled metal container. The external cooling device 10 is arranged outside the transport container 140 and is used to cool the outer wall of the transport container 140. The internal cooling device 20 is connected to the inner cavity of the transport container 140 and is used to cool the inner cavity of the transport container 140, which can solve the problems of the increase in cladding temperature and water body boiling during the long-term interruption of the operation in the process of loading the transport container 140, which affect the operation of the operators.

[0076] The setting of the spent fuel cooling system on the transport container 140 forms a spent fuel transport cooling system with the transport container 140.

[0077] Specifically, referring to Figures 5 - 7 , the external cooling device 10 may include a cooling bladder 11, a water filling loop 12 and a drainage loop 13. The cooling bladder 11 is wrapped outside the transport container 140, specifically on the outer surface of the transport container 140; the water filling loop 12 and the drainage loop 13 are respectively sleeved outside the cooling bladder 11 and communicate with the cooling bladder 11. The first cooling medium enters the cooling bladder 11 through the water filling loop 12 and then discharges from the drainage loop 13. The first cooling medium may be demineralized water, and its advantage is high water quality purity, which can avoid corrosion and contamination of equipment parts, pipelines, etc.

[0078] The cooling bladder 11 includes a number of relatively independent cooling bladder monomers 111; the number of cooling bladder monomers 111 are arranged along the outer circumference of the transport container 140 and are attached to the outer surface of the transport container 140. Each cooling bladder monomer 111 forms an independent cold source and independently cools the attached outer surface. The cooling bladder monomer 111 is made of flexible non-metallic or metallic materials to form a flexible cooling module.

[0079] The water filling loop 12 includes a water filling ring 121, a number of water filling branch pipes 122 and a water filling pipe 123. The water filling ring 121 is sleeved outside the cooling bladder 11; the number of water filling branch pipes 122 are arranged at intervals along the circumference of the water filling ring 121 and are connected between the water filling ring 121 and the corresponding cooling bladder monomer 111 to communicate the water filling ring 12 and the cooling bladder monomer 111. The water filling pipe 123 is connected to the water filling ring 121 and is used to access the first cooling medium. The first cooling medium enters the water filling ring 121 through the water filling pipe 123, and then is distributed to each water filling branch pipe 122 along the water filling ring 121 and enters the cooling bladder monomer 111 along the water filling branch pipe 122.

[0080] The drainage loop 13 includes a drainage ring 131, a plurality of drainage branch pipes 132, and a drain pipe 133. The drainage ring 131 is sleeved outside the cooling bladder 11; the plurality of drainage branch pipes 132 are arranged at intervals along the circumference of the drainage ring 131 and are connected between the drainage ring 131 and the corresponding cooling bladder unit 111 to communicate the drainage ring 131 and the cooling bladder unit 111. The drain pipe 133 is connected to the drainage ring 131 and is used to discharge the first cooling medium. The first cooling medium in each cooling bladder unit 111 enters the drainage ring 131 through the respective connected drainage branch pipes 132, enters the drain pipe 133 along the drainage ring 131, and is discharged from the drain pipe 133.

[0081] To support and position the cooling bladder 11 outside the transport container 140, the external cooling device 10 may further include at least one support collar 14. The support collar 14 is used to be sleeved on the outer periphery of the transport container 140, and the cooling bladder 11 is circumferentially connected to the support collar 14. The support collar 14 plays a role of fixing the framework and positions the cooling bladder 11 and even the entire external cooling device 10 on the transport container 140. To fit with the outer peripheral surface of the transport container 140, one side of each cooling bladder unit 111 facing the transport container 140 is an arc surface, and all the cooling bladder units 111 are concentrically and circumferentially fixed on the support collar 14.

[0082] It can be understood that a water filling valve may be provided on the water filling pipe 123 to control the water filling flow rate. One end of the water filling pipe 123 far from the water filling ring 121 may extend and be connected to the desalted water source of the nuclear power plant, and under the power provided by the water pump, the desalted water is pumped into the water filling ring 121. A drain valve is provided on the drain pipe 133 to control the drainage flow rate.

[0083] Preferably, the water filling ring 121 is sleeved on the outer periphery of the lower end of the cooling bladder 11, and the drainage ring 131 is sleeved on the outer periphery of the upper end of the cooling bladder 11 to form a direct current circulating cooling form of low-position water filling and high-position drainage. The first cooling medium takes away the decay heat generated by the spent fuel assembly through the flow mode of filling water from the lower part and discharging water from the upper part.

[0084] As Figure 8 As shown, the internal cooling device 20 communicates with the inner cavity of the transport container 140 and is used to cool the inner cavity of the transport container 140. The internal cooling device 20 may specifically include a first water filling pipeline 21 and a first drainage pipeline 22; the first water filling pipeline 21 is connected to the inflation hole on the transport container 140, and the first drainage pipeline 22 is connected to the drainage hole on the transport container 140. The second cooling medium enters the inner cavity of the transport container 140 through the first water filling pipeline 21 and then is discharged from the first drainage pipeline 22 to replace and cool the boron-containing water in the inner cavity of the transport container 140. The first drainage pipeline 22 may pass through the drainage hole and extend into the lower part or the bottom of the transport container 140.

[0085] The second cooling medium is preferably boric acid-containing water for nuclear power plants, which is characterized in that boric acid is added to the water, and it undertakes the functions of absorbing and moderating neutrons generated by the fission of spent fuel assemblies.

[0086] It can be understood that valves are respectively provided on the first water filling pipeline 21 and the first drainage pipeline 22 to control the flow rate.

[0087] The internal cooling device 20 adopts the method of upper filling and upper drainage to drain the high-temperature boric acid-containing water inside the transport container 140 from the top of the transport container 140 at the same water filling flow rate.

[0088] Reference Figure 8 , after the spent fuel cooling system of this embodiment is filled with spent fuel assemblies, the cooling method includes the following steps: starting the internal cooling device 20 to replace and cool the boric acid-containing water in the inner cavity of the spent fuel storage tank 110; starting the external cooling device 10 to fill the cooling bladder 11 with low-temperature demineralized water through the water filling loop 12 and discharging it from the drainage loop 13. The above cooling method can solve the problems of the increase in cladding temperature and the boiling of the water body during the long-term interruption of operation during the loading process of the transport container, which affect the operation of the operators.

[0089] The above are only embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A spent fuel cooling system, characterized in that: It includes an external cooling device for cooling the outside of the spent fuel storage container and an internal cooling device for cooling the inner cavity of the spent fuel storage container; The external cooling device comprises a cooling bag covering the outside of the spent fuel storage container, and a water filling loop and a drainage loop respectively sleeved on the outside of the cooling bag, wherein the water filling loop and the drainage loop are respectively connected to the cooling bag, and a first cooling medium enters the cooling bag through the water filling loop and is then discharged from the drainage loop to take away the heat emitted from the outside of the spent fuel storage container; The internal cooling device comprises a first water filling pipeline connected to the air filling hole on the spent fuel storage container and a first drainage pipeline connected to the drainage hole on the spent fuel storage container; a second cooling medium enters the inner cavity of the spent fuel storage container through the first water filling pipeline and is then discharged from the first drainage pipeline to perform replacement cooling on the boron-containing water in the inner cavity of the spent fuel storage container.

2. The spent fuel cooling system according to claim 1, characterized in that: The cooling bag includes a plurality of relatively independent cooling bag monomers, and the plurality of cooling bag monomers are arranged along the outer circumference of the spent fuel storage container and adhere to the outer surface of the spent fuel storage container.

3. The spent fuel cooling system according to claim 2, characterized in that: The water filling loop line includes a water filling ring sleeved at the lower end of the cooling bag, a plurality of water filling branches, and a water filling pipe connected to the water filling ring and used to access the first cooling medium; the plurality of water filling branches are arranged at intervals along the circumference of the water filling ring and connected between the water filling ring and the corresponding cooling bag monomer.

4. The spent fuel cooling system according to claim 2, characterized in that: The drainage loop line includes a drainage ring mounted on the upper end of the cooling bag, a plurality of drainage branches, and a drainage pipe connected to the drainage ring and used to discharge the first cooling medium; the plurality of drainage branches are arranged at intervals along the circumference of the drainage ring and connected between the drainage ring and the corresponding cooling bag monomer.

5. The spent fuel cooling system according to claim 1, characterized in that: The external cooling device further comprises a supporting collar; the supporting collar is used to be sleeved on the outer periphery of the spent fuel storage container, and the cooling bag is connected around the supporting collar.

6. The spent fuel cooling system according to any one of claims 1 to 5, characterized in that: The spent fuel cooling system also includes an annular cavity cooling device for cooling the annular cavity of the spent fuel storage container; The annular cavity cooling device comprises a second water filling pipeline and a second water discharge pipeline respectively communicated with the annular cavity; The third cooling medium enters the annular cavity through the second water filling pipeline and is then discharged from the second water discharge pipeline to perform replacement cooling on the high-temperature water in the annular cavity.

7. A spent fuel storage cooling system, characterized in that: Includes spent fuel storage tanks, transfer containers and spent fuel cooling systems for loading spent fuel assemblies; The spent fuel storage tank is installed in the transport container, and an annular cavity is formed between the outer periphery of the spent fuel storage tank and the inner periphery of the transport container; the spent fuel cooling system includes an external cooling device, an internal cooling device and an annular cavity cooling device; The external cooling device includes a cooling bag covering the outside of the transport container, a water filling loop and a drainage loop respectively sleeved on the outside of the cooling bag, the water filling loop and the drainage loop are respectively connected to the cooling bag, the first cooling medium enters the cooling bag through the water filling loop, and then is discharged from the drainage loop to take away the heat dissipated from the outside of the transport container; The internal cooling device comprises a first water filling pipeline connected to the air filling hole on the spent fuel storage tank and a first drainage pipeline connected to the drainage hole on the spent fuel storage tank; a second cooling medium enters the inner cavity of the spent fuel storage tank through the first water filling pipeline and is then discharged from the first drainage pipeline to perform replacement cooling on the boron-containing water in the inner cavity of the spent fuel storage tank; The annular cavity cooling device comprises a second water filling pipeline and a second water discharge pipeline respectively communicated with the annular cavity; The third cooling medium enters the annular cavity through the second water filling pipeline and is then discharged from the second water discharge pipeline to perform replacement cooling on the high-temperature water in the annular cavity.

8. The spent fuel storage cooling system according to claim 7, characterized in that: The upper end and the lower end of the outer surface of the transport container are respectively provided with an upper trunnion and a lower trunnion; The external cooling device is located outside the transport container between the upper trunnion and the lower trunnion.

9. A cooling method for a spent fuel storage cooling system according to claim 7 or 8, characterized in that: The following steps are involved: S1. When the automatic welding system and vacuum drying system of the spent fuel tank malfunction and stop operating, continuously monitor the temperature of the desalted water in the annular cavity between the spent fuel tank and the transfer container; S2. When the temperature of the desalted water in the annular cavity exceeds the water temperature safety limit, the annular cavity cooling device is turned on to make the water flow entering the annular cavity through the second water filling pipeline equal to the water flow discharged from the annular cavity through the second water discharge pipeline; S3, start the external cooling device, fill the cooling bag with low-temperature desalted water through the water filling loop, and discharge it from the drainage loop; S4, the annular cavity cooling device and the external cooling device are continuously operated, and the temperature of the desalted water in the annular cavity is continuously detected. When the temperature of the desalted water does not meet the water temperature safety limit, the internal cooling device is started to perform displacement cooling on the boron-containing water in the inner cavity of the spent fuel storage tank until the temperature of the desalted water meets the safety limit.

10. A spent fuel transport cooling system, characterized in that: It comprises a transport container for loading spent fuel assemblies and a spent fuel cooling system; the spent fuel cooling system comprises an external cooling device and an internal cooling device; The external cooling device includes a cooling bag covering the outside of the transport container, a water filling loop and a drainage loop respectively sleeved on the outside of the cooling bag, the water filling loop and the drainage loop are respectively connected to the cooling bag, the first cooling medium enters the cooling bag through the water filling loop, and then is discharged from the drainage loop to take away the heat emitted from the outside of the transport container; The internal cooling device includes a first water filling pipeline connected to the inflation hole on the transport container and a first drainage pipeline connected to the drainage hole on the transport container; a second cooling medium enters the inner cavity of the transport container through the first water filling pipeline and is then discharged from the first drainage pipeline to perform replacement cooling on the boron-containing water in the inner cavity of the transport container.

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