JP5456304B2 - Concrete cask heat removal device and concrete cask - Google Patents

Description

  The present invention relates to a heat removal device for a concrete cask and a concrete cask having the same. More specifically, the present invention relates to a heat removal device for a concrete cask that cools the inside of the concrete cask by the flow of air, and a concrete cask including the same.

  Spent nuclear fuel generated by nuclear power is stored in a concrete cask and stored under proper management. The concrete cask includes a canister for storing spent nuclear fuel and a concrete container for storing the canister. Since the fission product (FP) in the spent nuclear fuel continues to decay after removal from the reactor, the canister generates heat even during storage. For this reason, for example, in the concrete cask described in JP-A-8-43591, a number of heat pipes are provided in the heat insulating layer 103 between the metal canister 101 containing the FP and the concrete layer 102 as shown in FIG. 104 is buried, and heat of the canister 101 is removed by the heat pipe 104.

JP-A-8-43591

  However, in the above-described concrete cask, in order to inspect the internal canister 101, it is necessary to open the lid 105 of the concrete cask and expose the canister 101. For this reason, the inspection of the canister 101 becomes large. Here, in order to facilitate the inspection of the canister 101, it may be possible to provide a through-hole into which the inspection borehole camera is inserted in the lid 105 or the like. In that case, a dedicated inspection hole is provided. become.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a concrete cask that can easily inspect a canister without a dedicated inspection hole, and a heat removal device used for the concrete cask.

  In order to achieve this object, the invention according to claim 1 is directed to an exhaust gas which is provided at a position higher than the air supply port by taking in the primary side cooling air for cooling the canister accommodated in the concrete container from the air supply port. In the heat removal device for the concrete cask discharged from the mouth, the primary side cooling air, which is disposed outside the concrete container and communicates with the exhaust port and the air supply port, is circulated to the air supply port. A primary side passage capable of exchanging heat with an outer wall is provided, and the primary side passage is detachable from the concrete container.

  Therefore, after cooling the canister in the concrete cask, the primary side cooling air is discharged from the exhaust port, releases heat by heat exchange while passing through the primary side passage, and is circulated to the air supply port. Ascending force due to heating acts on the primary-side cooling air, and descending force due to cooling acts in the primary-side passage outside the concrete cask. For this reason, primary side cooling air circulates naturally. Since the primary side passage is detachable from the concrete container, the heat removal device can be attached to and detached from the concrete cask. By removing the heat removal device from the concrete cask, it is possible to expose the air supply and exhaust ports leading to the concrete container.

  The concrete cask heat removal device according to claim 2 includes a secondary side passage provided on the outer wall as a heat exchange portion of the primary side passage and through which the secondary side cooling air flows, and the secondary side cooling air is The secondary side air supply from the secondary side passage is heated by flowing in from the secondary side air supply port provided at the lower end of the secondary side passage and cooling the primary side cooling air to rise in the secondary side passage. It is discharged from the secondary side exhaust port provided at a position higher than the port. Therefore, the primary side cooling air is cooled by the secondary side cooling air. Since the secondary cooling air is subjected to heating by heat exchange with the primary cooling air, the secondary cooling air flows from the secondary air supply port to the secondary side passage to the secondary side exhaust port. It flows by the power of nature.

  A concrete cask heat removal apparatus according to a third aspect includes a tertiary side cooling liquid that evaporates and cools the secondary side cooling air using heat of vaporization. Therefore, the secondary side cooling air flowing through the secondary side passage is cooled by the heat of vaporization of the tertiary side cooling liquid. The tertiary cooling liquid may be stored in the storage tank in contact with the secondary side passage, or may be sprayed or flowed on the surface of the secondary side passage.

  Furthermore, the invention described in claim 4 is a concrete in which primary side cooling air for cooling a canister accommodated in a concrete container is taken in from an air supply port and discharged from an exhaust port provided at a position higher than the air supply port. The cask is provided with the heat removal device according to any one of claims 1 to 3. Accordingly, a concrete cask including the heat removal device is configured.

  In the heat removal apparatus for concrete cask according to claim 1, since the inside of the concrete container is cooled by circulating the primary side cooling air, the inside of the concrete container can be shut off from the external environment, and the outside air containing salt etc. is the concrete. Inflow into the container can be prevented. Therefore, the canister can be prevented from corroding due to salt and moisture contained in the outside air.

  Moreover, since the heat removal device can be attached to and detached from the concrete cask, the heat removal device can be removed to expose the air supply port and the exhaust port, and the canister and the like are inspected using the air supply port and the exhaust port. be able to. Therefore, it is not necessary to provide an inspection-dedicated hole in the concrete cask, and the inspection operation itself is facilitated because there is no operation such as opening the lid. Moreover, the heat removal apparatus can be easily maintained by removing the heat removal apparatus from the concrete cask. In addition, it is possible to retrofit the existing concrete cask with a heat removal device. Moreover, it becomes possible to attach the heat removal apparatus only when necessary. For example, corrosion such as stress corrosion cracking becomes a problem mainly at the end of storage, and it becomes possible to attach a heat removal device only at the end of storage where it is necessary to shut off from the external salinity environment. The heat removal device can be removed.

  In the concrete cask heat removal apparatus according to claim 2, the primary side cooling air can be cooled by external air. Therefore, the structure of the heat removal apparatus can be simplified. In addition, since the secondary side cooling air can be circulated using natural force, no dedicated power is required and maintenance is easy. Further, since the outside air is used, the loss of the secondary side cooling air can be prevented, and the reliability can be further improved.

  In the concrete cask heat removal apparatus according to the third aspect, since the secondary side cooling air can be cooled, the cooling performance of the primary side cooling air can be further improved.

  Furthermore, in invention of Claim 4, a concrete cask provided with said heat removal apparatus is comprised.

  Hereinafter, the configuration of the present invention will be described in detail based on the best mode shown in the drawings.

  1 to 3 show an embodiment of a concrete cask heat removal apparatus (hereinafter simply referred to as a heat removal apparatus) according to the present invention. The heat removal apparatus 1 takes in the primary side cooling air 5 for cooling the canister 4 accommodated in the concrete container 3 of the concrete cask 2 from the air supply port 6 and is provided at a position higher than the air supply port 6. The primary cooling air 5 is applied to the concrete cask 2 discharged from the port 7, is disposed outside the concrete container 3, communicates the exhaust port 7 and the air supply port 6, and is discharged from the exhaust port 7. Is circulated to the air supply port 6 and is provided with a primary side passage 8 that can exchange heat with the outer wall 14, and the primary side passage 8 is detachable from the concrete container 3. Moreover, this invention is grasped | ascertained also as the concrete cask 2 provided with the above-mentioned heat removal apparatus 1. FIG.

  A canister 4 for storing spent nuclear fuel is placed on a support leg 11 and stored in a concrete container 3. The upper opening of the concrete container 3 is closed by a lid 12. A cooling passage 13 through which the primary side cooling air 5 flows is provided between the canister 4 and the concrete container 3. An air supply port 6 that leads to the cooling passage 13 is provided at the bottom of the concrete container 3. An exhaust port 7 that leads to the cooling passage 13 is provided between the concrete container 3 and the lid 12. Since the air supply port 6 and the exhaust port 7 are communicated with each other by the primary side passage 8, it is preferable that the same number is provided at the same position as viewed from above, for example, as shown in FIG. However, if the primary side cooling air 5 can be circulated from the exhaust port 7 to the air supply port 6 by the primary side passage 8, the air supply port 6 and the exhaust port 7 are provided at the same position when viewed from above. It is not necessary, and the number of air supply ports 6 and exhaust ports 7 may be different. In addition, since the air supply port 6 and the exhaust port 7 are communicated with each other by the primary passage 8, it is preferable that the air supply port 6 and the exhaust port 7 are opened on the peripheral surface of the concrete cask 2. However, if the air supply port 6 and the exhaust port 7 can be communicated with each other by the primary passage 8, it is not necessary to open the air supply port 6 and the exhaust port 7 on the peripheral surface of the concrete cask 2. 6 may be opened on the bottom surface of the concrete cask 2, for example, and the exhaust port 7 may be opened on the top surface of the concrete cask 2, for example. In the present embodiment, air supply ports 6 and exhaust ports 7 are provided on the peripheral surface of the concrete cask 2 at, for example, four locations at equal intervals in the circumferential direction.

  One heat removal device 1 is provided for each set composed of one air supply port 6 and one exhaust port 7. Since the concrete cask 2 of this embodiment is provided with four sets of air supply ports 6 and exhaust ports 7, four heat removal apparatuses 1 are attached to the concrete cask 2.

  The heat removal apparatus 1 includes a secondary side passage 10 that is provided on the outer wall 14 as a heat exchange part of the primary side passage 8 and through which the secondary side cooling air 9 flows. That is, the primary side passage 8 and the secondary side passage 10 are provided so as to be able to exchange heat with the outer wall 14 therebetween. Each of the passages 8 and 10 is formed of a material that has excellent thermal conductivity and can secure rigidity as a passage, for example, a metal material such as copper, aluminum, and stainless steel. In the present embodiment, fins 15 are provided on the outer wall 14 in order to improve the heat exchange performance by increasing the contact area with the airs 5 and 9. The fin 15 has a shape that does not obstruct the flow of the airs 5 and 9. However, the fins 15 may not be provided when sufficient heat exchange performance can be ensured. In FIG. 1, the fins 15 are not shown.

  A primary side air supply port 16 connected to the exhaust port 7 of the cooling passage 13 is provided at the upper end of the primary side passage 8, and a primary side exhaust port 17 connected to the air supply port 6 of the cooling passage 13 is provided at the lower end. It has been. In the present embodiment, the primary side air supply port 16 and the primary side exhaust port 17 are formed in a cylindrical shape, and the tip of the cylindrical portion is inserted into the exhaust port 7 or the air supply port 6 of the cooling passage 13 so as to be connected. The primary side cooling air 5 is prevented from leaking out from the portion and from the outside air. Further, a secondary side air supply port 18 is provided at the lower end of the secondary side passage 10, and a secondary side exhaust port 19 is provided at the upper end. The secondary side air supply port 18 and the secondary side exhaust port 19 are open to the atmosphere.

The heat removal apparatus 1 of this embodiment includes a tertiary cooling liquid 20 that evaporates and cools the secondary cooling air 9 using heat of vaporization. The tertiary cooling liquid 20 is stored in a storage tank 21 provided on the opposite side of the primary side passage 8 with the secondary side passage 10 interposed therebetween. The tertiary-side cooling liquid 20 is in contact with the secondary-side passage 10 and cools the secondary-side cooling air 9 flowing in the secondary-side passage 10 with heat of vaporization during evaporation. In the present embodiment, in order to increase the contact area between the secondary side cooling air 9 and the tertiary side cooling liquid 20 and improve the heat exchange performance, the partition wall 22 between the secondary side passage 10 and the storage tank 21, that is, In the present embodiment, fins 23 are provided on the outer wall of the secondary side passage 10. The fins 23 have a shape that does not obstruct the flow of the secondary side cooling air 9 and the tertiary side cooling liquid 20. However, the fins 23 may not be provided if sufficient heat exchange performance can be ensured. The tertiary cooling liquid 20 is water, for example. However, a coolant other than water may be used. In FIG. 1, the fins 23 are not shown.

  The heat removal apparatus 1 is mounted on, for example, a carriage 24 and is movable. By placing the heat removal apparatus 1 on the carriage 24, the height of the air supply port 6 and the primary side exhaust port 17 and the height of the exhaust port 7 and the primary side air supply port 16 are matched. Therefore, by moving the heat removal apparatus 1 on the carriage 24, the primary side exhaust port 17 can be inserted into the air supply port 6 and the primary side air supply port 16 can be inserted into the exhaust port 7 as it is. After these are connected, the installation of the heat removal apparatus 1 is completed by fixing the carriage 24. When disconnecting the heat removal apparatus 1, the carriage 24 is unlocked and moved, and the primary air supply port 16 is pulled out from the exhaust port 7, and the primary exhaust port 17 is pulled out from the air supply port 6. It ’s fine.

  The heat removal device 1 may be attached to the concrete cask 2 from the start of use of the concrete cask 2 (the initial stage of radioactive waste storage) and removed when the canister 4 is inspected, or the use of the concrete cask 2 is started. Sometimes, the heat removal apparatus 1 is not attached, and the heat removal apparatus 1 may be attached to the concrete cask 2 after a certain period of time has elapsed after the start of use. For example, corrosion such as stress corrosion cracking (SCC) often becomes a problem at the end of storage where the canister 4 may be at a low temperature to cause condensation. Therefore, the heat removal device 1 is attached to the concrete cask 2 only at the end of storage when it is necessary to isolate the inside of the concrete container 3 from the external salt environment, and the heat removal device 1 is detached from the concrete cask 2 at an unnecessary time. You can keep it. Since the heat removal apparatus 1 is detachable, it can be used in various ways as described above.

  Next, the operation of the heat removal apparatus 1 will be described.

  When the heat removal device 1 is attached to the concrete cask 2 and the primary side air supply port 16 is connected to the exhaust port 7 and the primary side exhaust port 17 is connected to the air supply port 6, the cooling passage 13 and the primary side passage 8 are A loop for circulating the primary side cooling air 5 is formed. Since the primary side cooling air 5 is heated by cooling the canister 4 in the concrete container 3, a rising force acts on the primary side cooling air 5. On the other hand, since the primary side cooling air 5 is cooled by the secondary side cooling air 9 outside the heat removal apparatus 1, that is, in the primary side passage 8, a downward force acts on the primary side cooling air 5. Therefore, the primary side cooling air 5 naturally circulates in the cooling passage 13 → the exhaust port 7 → the primary side passage 8 → the air supply port 6 → the cooling passage 13 and conveys the heat of the canister 4 to the outside of the concrete container 3.

  Further, since the secondary side cooling air 9 is heated by cooling the primary side cooling air 5 in the secondary side passage 10, a rising force acts on the secondary side cooling air 9. Therefore, the secondary side cooling air 9 flows in from the secondary side air supply port 18 provided at the lower end of the secondary side passage 10 and rises in the secondary side passage 10. It is discharged from a secondary exhaust port 19 provided at a position higher than the air port 18. That is, the secondary side cooling air 9 naturally circulates from the outside to the secondary side air supply port 18 → the secondary side passage 10 → the secondary side exhaust port 19 → to the outside, and the primary side cooling air 5 causes the outside of the concrete container 3. Releases the heat transported to the environment. At this time, since the secondary side cooling air 9 is cooled more favorably by the heat of vaporization of the tertiary side cooling liquid 20, the temperature of the secondary side cooling air 9 decreases accordingly, and the primary side cooling air 5 is made better. Can be cooled.

  The canister 4 is inspected with the heat removal apparatus 1 removed from the concrete cask 2. When the heat removal device 1 is removed, the air supply port 6 and the exhaust port 7 leading to the concrete container 3 are exposed. For example, a borehole camera can be inserted from the air supply port 6 or the exhaust port 7 to inspect the canister 4. it can. For this reason, the inspection of the canister 4 can be easily performed. Further, since the air supply port 6 or the exhaust port 7 can be used for the inspection, it is not necessary to provide a dedicated inspection hole.

  In the present invention, the primary cooling air 5 is circulated to cool the canister 4, so that the inside of the concrete container 3 can be shut off from the external environment, and the outside air containing salt or the like is prevented from flowing into the concrete container 3. can do. Therefore, it is possible to prevent the canister 4 from being corroded due to salt or moisture contained in the outside air. In particular, radioactive waste storage facilities are often built on the seaside, and the outside air contains a lot of salt. In the present invention, since the outside air in such a state is not introduced into the concrete container 3, the salt content in the outside air does not adhere to the welded portion of the canister 4 and the stress corrosion is caused by the salt contained in the outside air. It is possible to reliably prevent cracks and the like from occurring and progressing.

  Moreover, since the primary side cooling air 5 and the secondary side cooling air 9 can be naturally circulated using the heat of the canister 4, the power for driving them becomes unnecessary, and the maintenance management of the apparatus 1 becomes easy. At the same time, the reliability and durability of the device 1 can be improved.

  Moreover, since the heat removal apparatus 1 can be detached from the concrete cask 2, the heat removal apparatus 1 can be easily maintained. Further, it becomes possible to retrofit the existing concrete cask 2.

  Further, since air is used as the secondary side cooling air 9, the secondary side cooling air 9 is not lost, the primary side cooling air 5 can be reliably cooled, and the reliability is excellent. Yes.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the above description, one heat removal device 1 is provided for one air supply port 6 and one exhaust port 7. However, the present invention is not necessarily limited to this configuration. One heat removal device 1 may be provided for the port 6 and the plurality of exhaust ports 7. For example, as shown in FIG. 4, one heat removal device 1 may be provided for all of the air supply ports 6 and all of the exhaust ports 7. In this case, it is preferable that the heat removal apparatus 1 is divided into a plurality of units so that the heat removal apparatus 1 can be attached to and detached from the concrete cask 2.

  Moreover, although the above-mentioned heat removal apparatus 1 was provided with the tertiary side cooling liquid 20, you may abbreviate | omit the tertiary side cooling liquid 20. FIG. In this case, the secondary side cooling air 9 is cooled by the surrounding air.

  Further, in the above description, the tertiary side cooling liquid 20 is stored in the storage tank 21, but it is not necessarily limited to this configuration. For example, the tertiary side cooling liquid 20 is sprayed on the surface of the secondary side passage 10. You may make it flow.

  In the above description, water is used as the tertiary side cooling liquid 20, but it is not necessarily limited to water, and a cooling fluid other than water may be used.

  In the above description, the air 9 is used as the cooling fluid on the secondary side. However, the air 9 is not necessarily limited to air, and other gases may be used.

  In the above description, the heat removal apparatus 1 is movable by being placed on the carriage 24. However, the means for moving the heat removal apparatus 1 is not necessarily limited to the carriage 24. For example, a forklift or crane It may be made to move using a conveying means such as, or the heat removal apparatus 1 may be made to move by providing wheels.

  In the above description, the primary air supply port 16 and the primary exhaust port 17 are formed in a cylindrical shape, and these are inserted into the exhaust port 7 or the air supply port 6 of the cooling passage 13 so that the passages 8 and 13 are formed. Although the connection is made, the means for connection is not limited to this, and other means may be used as long as leakage of the primary side cooling air 5 and inflow of outside air from the connection portion can be prevented.

It is sectional drawing which shows an example of embodiment of the heat removal apparatus of this invention. It is a top view which shows a mode that the heat removal apparatus was attached to the concrete cask. It is sectional drawing which follows the III-III line of FIG. It is a top view which shows other embodiment of the heat removal apparatus of this invention, and shows a mode that it attached to the concrete cask. It is a perspective view which cuts and shows the conventional concrete cask partially.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat removal apparatus 2 Concrete cask 3 Concrete container 4 Canister 5 Primary side cooling air 6 Supply port 7 Exhaust port 8 Primary side passage 9 Secondary side cooling air 10 Secondary side passage 18 Secondary side supply port 19 Secondary side Exhaust port 20 Tertiary side cooling liquid

Claims (4)

  In a concrete cask heat removal apparatus, a primary side cooling air for cooling a canister accommodated in a concrete container is taken in from an air supply port and discharged from an exhaust port provided at a position higher than the air supply port. A primary side that is disposed outside the container, communicates the exhaust port and the air supply port, circulates the primary cooling air discharged from the exhaust port to the air supply port, and exchanges heat with an outer wall A concrete cask heat removal apparatus comprising a passage, wherein the primary passage is detachable from the concrete container.   A secondary side passage provided as a heat exchange part of the primary side passage on the outer wall and through which secondary side cooling air flows is provided, and the secondary side cooling air is provided at a lower end of the secondary side passage. Heated by flowing in from the side air supply port and cooling the primary side cooling air to rise in the secondary side passage, provided at a position higher than the secondary side air supply port in the secondary side passage 2. The concrete cask heat removal device according to claim 1, wherein the heat removal device is discharged from the secondary side exhaust port. The heat removal apparatus for a concrete cask according to claim 2 , further comprising a tertiary cooling liquid that evaporates and cools the secondary cooling air by heat of vaporization.   In the concrete cask which takes in the primary side cooling air which cools the canister accommodated in the concrete container from an air supply port, and discharges it from an exhaust port provided in a position higher than the air supply port. A concrete cask comprising the heat removal apparatus described in any one of the above.

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