JP2015075349A - Cooling device, and spent fuel storage pool including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device capable of cooling a stored cooling object even when the water storage function of a cooling pool becomes lost, and provide a spent fuel storage pool including the cooling device.SOLUTION: The cooling device includes water spray means for spraying cooling water, for cooling, to the partially or entirely exposed fuel rods (spent fuel) 54 stored in a spent fuel storage pool 61. The water spray means includes a sparger pipe 12 disposed along a side wall of the spent fuel storage pool 61, and continuously cools the fuel rods 54 by spraying cooling water to the stored fuel rods 54 using the sparger pipe 12.

Description

  The present invention relates to a cooling device that cools an object to be cooled when a water storage function of the cooling pool is lost, and a spent fuel storage pool including the cooling device.

  In cooling pools that cool the contents, especially spent fuel storage pools that contain and cool spent fuel generated in nuclear power plants, it is necessary to continue cooling the contained fuel even in the event of an abnormality such as an earthquake. Don't be. The spent fuel storage pool is usually based on submerged cooling, and the cooling water is circulated through a heat exchanger by a pump to keep the water temperature below a certain level.

  The nuclear power plant is equipped with an emergency diesel power generation facility in preparation for a power outage in the event of a disaster, and a cooling water circulation pump operates even during a power outage. In addition, even if one pump is stopped by connecting two pumps in parallel and connecting an emergency power source of another system to each pump, cooling water is circulated with the other pump to cool spent fuel. There is a method (for example, refer to Patent Document 1).

  In addition, as a method of cooling the spent fuel in the spent fuel storage pool in the event of an emergency, a method of installing a heat exchanger directly in the spent fuel storage pool, or a flow path around the spent fuel storage pool There is a method of providing and air cooling (for example, refer to Patent Documents 2 and 3).

  In addition, there is a method of supplying cooling water from a natural water source without using a pump in an emergency by installing a spent fuel storage pool below the tide level of the natural water source and connecting it to the natural water source (for example, a patent Reference 4).

JP-A-63-63955 JP 2012-230079 JP 2012-225870 A JP 2013-7727 A

  The techniques described in Patent Documents 1 to 3 are based on the premise that the water storage function of the spent fuel storage pool is maintained even in an emergency, and the spent fuel storage pool is damaged by an earthquake or the like, and cooling water leaks. It cannot be used in situations where

  In addition, the technique described in Patent Document 4 requires that the reactor building be installed in the basement, which is enormous in cost and difficult to apply to existing facilities.

  An object of the present invention is to provide a cooling device that can cool an object to be cooled even when the water storage function of the cooling pool is lost, and a spent fuel storage pool including the cooling device.

  The present invention comprises water sprinkling means for sprinkling and cooling cooling water stored in a cooling pool that cools a part to be cooled, with a part or all of the cooling target being exposed. A cooling apparatus comprising a sparger pipe disposed along a side wall.

  According to the present invention, since the sparger pipe for sprinkling the cooling water is provided to the object to be cooled that is partly or entirely exposed in the cooling pool, the cooling pool is damaged by a disaster such as an earthquake, and the water storage function is provided. Even when lost, the object to be cooled can be continuously cooled.

  Moreover, in this invention, the said sparger piping is arrange | positioned in the position higher than the said to-be-cooled object.

  According to the present invention, since the sparger pipe is arranged at a position higher than the object to be cooled, when the object to be cooled contains a radioactive substance, the radiation dose can be reduced by watering from above.

  In the present invention, the watering means further includes a watering pipe that can be expanded and contracted and / or bent and a driving device that expands and contracts and / or bends the watering pipe, and the driving device moves above the cooling pool. The sprinkling pipe is sent out, and the sprinkling pipe is stored outside the cooling pool.

  According to the present invention, since the water sprinkling pipe can be sent over the cooling pool at the time of watering, even if the object to be cooled is stored at a position where the cooling water does not reach by watering from the sparger pipe, can do. Further, since the water sprinkling pipe can be stored outside the cooling pool, it is possible to avoid interference with other devices that access the sky above the cooling pool. Such a cooling device can be suitably used for a spent fuel storage pool of an existing nuclear power plant.

  The present invention is also a spent fuel storage pool installed in a nuclear power plant for containing and cooling spent fuel, comprising the cooling device, wherein the watering means is disposed in the spent fuel storage pool. A spent fuel storage pool that is disposed at a position that does not interfere with a fuel replacement device that transports fuel and / or can be stored at a position that does not interfere with the fuel replacement device.

  According to the cooling device of the present invention, even if a part or all of the object to be cooled is exposed because the water storage function of the cooling pool is lost, the object to be cooled can be continuously cooled. Moreover, according to the spent fuel storage pool provided with the cooling device of the present invention, the spent fuel stored therein can be continuously cooled even when the water storage function is lost in the event of a disaster, so that the spent fuel is melted, etc. Can prevent fatal accidents. Further, the cooling device of the present invention and the spent fuel storage pool provided with the cooling device can be applied to an existing nuclear power plant at low cost.

It is a schematic block diagram of the cooling device 1 and the nuclear reactor 51 of 1st Embodiment of this invention. It is a figure for demonstrating the sparger piping 12 of the cooling device 1 of FIG. It is a figure for demonstrating the water source of the cooling device 1 of FIG.

  FIG. 1 is a schematic configuration diagram of a cooling device 1 and a nuclear reactor 51 according to a first embodiment of the present invention. FIG. 2 is a view for explaining the sparger pipe 12 of the cooling device 1 of FIG. FIG. 3 is a view for explaining a water source of the cooling device 1 of FIG.

  A nuclear power plant nuclear reactor 51 is provided with a spent fuel storage pool 61 that accommodates and cools fuel rods (spent fuel) 54 taken out from a reactor pressure vessel 53 installed in a reactor well 52. ing.

  The spent fuel storage pool 61 is provided with a fuel accommodating portion 62 for accommodating the fuel rod 54, and the fuel accommodating portion 62 is formed one step deep so that the accommodated fuel rod 54 is always submerged. A plurality of fuel storage racks 63 are arranged in the fuel storage portion 62 so as to store the fuel rods 54 aligned at regular intervals.

  At the boundary between the spent fuel storage pool 61 and the reactor well 52, a fuel passage 64 serving as a passage for transporting the fuel rods 54 is provided. The fuel passage 64 is watertightly closed by the partition wall 65 and the pool gate 66 when the nuclear reactor 51 is operated. When the fuel rod 54 is transported, the partition wall 65 and the pool gate 66 are opened and the reactor well 52 is filled with cooling water in order to transport the fuel rod 54 in a submerged state. FIG. 1 shows a state in which the reactor well 52 is also filled with cooling water.

  In addition, the spent fuel storage pool 61 includes a skimmer surge tank 67 that recovers the cooling water that has risen due to the rise in water temperature, and a water level drop in the spent fuel storage pool 61 to detect a central control room (not shown). ) And a water level detection means (not shown) for issuing an alarm.

  An example of the size of the spent fuel storage pool 61 is about 18 m in length, about 14 m in width, about 12 m in depth of the fuel storage portion 62, and a space 69 between the fuel storage portion 62 and the fuel passage 64. The depth of is about 8 m. The length of the fuel rod 54 is about 4 m. However, the size of the spent fuel storage pool 61 and the fuel rod 54 is not limited to this.

  Travel rails 55 are installed on both longitudinal edges of the reactor well 52 and the spent fuel storage pool 61, and the fuel changer 56 travels on the travel rails 55. The fuel replacement device 56 is installed so as to be able to traverse across the width direction of the reactor well 52 and the spent fuel storage pool 61, grips the fuel rod 54 with the fuel gripping portion 57 that expands and contracts, and the reactor pressure vessel 53. The fuel rod 54 is exchanged between the fuel storage rack 63 and the fuel storage rack 63.

  The cooling device 1 according to the first embodiment of the present invention basically includes the fuel rod 54 (fuel storage rack 63) of the fuel storage unit 62 when the water level of the spent fuel storage pool 61 is lowered due to leakage of cooling water. When part or all of the fuel rod 54 is exposed, the fuel rod 54 is sprayed with cooling water to cool the fuel rod 54. The cooling device 1 also exhibits an effect of reducing the radiation dose of the fuel rods 54 by sprinkling the cooling water.

  The cooling device 1 includes a sparger pipe 12 arranged around the spent fuel storage pool 61 as a watering means, and a watering pipe 13 arranged so that water can be sprinkled in the center of the spent fuel storage pool 61. A drive unit 21 that supports the pipe 13 and sends it to the center of the spent fuel storage pool 61, and a motor-operated valve 31 that switches between supply and shutoff of cooling water to the sparger pipe 12 and the sprinkling pipe 13 are provided.

  The sparger pipe 12 is disposed along the side wall of the spent fuel storage pool 61. The sparger pipe 12 is basically for sprinkling water to the fuel rod 54 of the fuel storage section 62, but the structure in the nuclear reactor 51 is located in the space 69 between the fuel storage section 62 and the fuel passage 64. Since it may be accommodated, it is arranged so that water can be sprinkled on the contents of the space 69. The sparger pipe 12 is provided with injection ports 14 for injecting cooling water at regular intervals, and the cooling water is sprayed radially from the injection ports 14.

  The sparger pipe 12 is preferably disposed so as to sprinkle water from a position higher than the accommodated fuel rod 54 (fuel storage rack 63), which is the object to be cooled, because the radiation dose of the fuel rod 54 can be reduced. Further, the sparger pipe 12 is arranged excluding the fuel passage 64 so as not to interfere with the fuel gripping portion 57 of the fuel changer 56 when the fuel changer 56 carries the fuel rod 54.

  The watering pipe 13 is a pipe that can be easily expanded and contracted and / or bent, for example, a flexible pipe, and a spray nozzle 15 that sprays cooling water radially is provided at the tip. The water sprinkling pipe 13 is supported by a drive device 21 to be described later, and is sent out above the center of the spent fuel storage pool 61 by the drive device 21 at the time of water sprinkling. So as not to interfere with the fuel, it is stored outside the spent fuel storage pool 61 by the drive device 21.

  The water sprinkling pipe 13 is basically used for sprinkling water to a position that cannot be reached by sprinkling with the sparger pipe 12.

  The drive device 21 includes a main body 22 in which a power source, a drive device, and the like are accommodated, and an arm 23 that supports the water sprinkling pipe 13. The water sprinkling pipe 13 is sent out and stored by bending and stretching the arm 23.

  The arm 23 has a pivotable joint 24 at the center, and is bent and stretched by pivoting the joint 24 as a fulcrum, and translates the spray nozzle 15 of the sprinkling pipe 13 in the longitudinal direction of the spent fuel storage pool 61. .

  The electric valve 31 is installed on the upstream side where the sparger pipe 12 and the water sprinkling pipe 13 merge. When the electric valve 31 is opened, cooling water is sprinkled from the sparger pipe 12 and the sprinkling pipe 13.

  In addition, it is preferable that the drive device 21 and the motor-operated valve 31 can be operated manually in preparation for power loss in an emergency.

  Next, the water source of the cooling device 1 of this embodiment will be described. Usually, as a system capable of supplying cooling water to the spent fuel storage pool 61 in the reactor 51, a fuel pool cooling system (FPC system) 71, a residual heat removal system (RHR system), a condensate transfer system (MUWC system) There is. In FIG. 3, pumps and motor-operated valves are omitted.

  The fuel pool cooling system 71 includes a filtered demineralizer 72 for purifying the cooling water and a heat exchanger 73 for cooling the cooling water, and the cooling water collected in the skimmer surge tank 67 of the spent fuel storage pool 61 is supplied. It is circulated to purify and cool, and is supplied to the bottom of the spent fuel storage pool 61.

  The residual heat removal system is a system for removing the decay heat of the fuel rod 54 in the reactor pressure vessel 53 after the reactor 51 is stopped. The residual heat removal system supplies cooling water to the fuel pool cooling system 71 when the thermal load of the fuel rods 54 accommodated in the spent fuel storage pool 61 is high.

  The condensate transfer system includes a condensate tank (not shown). When the heat load such as the fuel pool cooling system 71 or the residual heat removal system is high, or when these systems stop due to inspection, the condensate transfer system Condensate is supplied to the spent fuel storage pool 61 and the like.

  In addition, in case of an emergency such as a fire, there are a system including a filtered water tank (not shown) for storing water taken and filtered from a dam or the like, and an earthquake-resistant fireproof water tank (not shown) for storing seawater.

  The cooling device 1 of the present embodiment can draw cooling water from these fuel pool cooling system 71, residual heat removal system, condensate transfer system, filtered water tank, and earthquake-proof fire tank as a water source. Moreover, you may provide the system | strain which draws in seawater to the cooling device 1 directly from the sea via a filtration desalinator. Note that the amount of water that can be supplied to the cooling device 1 is to ensure the amount of water that can be continuously sprinkled until the water storage function of the spent fuel storage pool 61 is restored when the spent fuel storage pool 61 is damaged due to an earthquake or the like. It is necessary to keep.

  Next, the watering point by the cooling device 1 of this embodiment is demonstrated. If the spent fuel storage pool 61 is damaged due to a disaster such as an earthquake and the cooling water leaks more than the amount of cooling water supplied, the water level of the spent fuel storage pool 61 decreases and a part of the fuel rod 54 (fuel storage rack 63) Or everything is exposed. If the fuel rods 54 are exposed, the fuel rods 54 may be melted or radioactively contaminated, and it is necessary to cool the fuel rods 54 and reduce the radiation dose.

  When a water level drop is detected by the water level detection means of the spent fuel storage pool 61, an alarm is issued to the central control room. When an alarm is issued, an activation signal is transmitted from the central control room to the driving device 21. When the drive device 21 receives the activation signal, the drive device 21 sends the sprinkling pipe 13 upward to the fuel rod 54 (fuel storage rack 63). When the motor-operated valve 31 is opened by a signal from the central control room after the sprinkling pipe 13 is sent out, the sparger pipe 12 and the sprinkling pipe 13 spray water. It is safe to set the water level at which the water level detecting means operates to a level higher than the level at which a part of the fuel rod 54 (fuel storage rack 63) is exposed, and to spray water before the fuel rod 54 is exposed. Above, it is preferable.

  Further, when the drive device 21 sends out the sprinkling pipe 13, it interferes with the fuel replacement device 56 over the spent fuel storage pool 61, so the fuel replacement device 56 is over the spent fuel storage pool 61. If there is, the fuel replacement device 56 is moved out of the spent fuel storage pool 61 and then the sprinkling pipe 13 is sent out.

  Water spraying by the cooling device 1 is performed until the water storage function of the spent fuel storage pool 61 is restored by emergency measures or the like, and the fuel rod 54 can be flooded again. When the motor-operated valve 31 is closed by the signal from the central control chamber and the water spraying by the cooling device 1 is finished, the driving device 21 stores the water spray pipe 13 outside the spent fuel storage pool 61 by the signal from the central control chamber.

  As described above, when the cooling device 1 of the present embodiment is used, the fuel rod 54 can be cooled even when the water storage function of the spent fuel storage pool 61 is lost, and the radiation dose can be reduced by watering.

  Damage to the spent fuel storage pool 61 in the nuclear reactor 51 is fatal, and when the fuel rod 54 is exposed, it is necessary to cool it as soon as possible. The structure inside the reactor building including the spent fuel storage pool 61 is made of a special material and structure for protecting the reactor vessel and the like from radiation. When the spent fuel storage pool 61 is damaged, Repair is not easy. When the cooling device 1 of the present invention is not installed, when the spent fuel storage pool 61 is damaged, it may be possible to discharge water from a fire hydrant or the like until the first aid is completed, but it takes time to start discharging water. At the same time, the burden is great for continuous water discharge.

  If the cooling device 1 of the present invention is installed in advance, it is possible to spray water from the time when the fuel rod 54 is exposed, and it is easy to continuously cool the fuel rod 54, and a fatal accident occurs. Can be suppressed.

  As mentioned above, although the spent fuel storage pool provided with the cooling device of this invention and this cooling device was demonstrated using the cooling device 1 of 1st Embodiment, the spent fuel storage provided with the cooling device of this invention and this cooling device. A pool is not limited to the said embodiment, It can deform | transform and use in the range which does not change a summary. For example, a traverse rail for the drive device 21 may be laid in the width direction of the spent fuel storage pool 61, and the drive device 21 may be traversed in the width direction of the spent fuel storage pool 61 while sprinkling water.

  Moreover, for the water sprinkling pipe 13 and the driving device 21, for example, a known loading arm can be suitably used. Furthermore, instead of the arm 23 and the joint 24, the drive device 21 may send out and store the sprinkling pipe 13 using, for example, an extendable ladder (not shown).

  The water source of the cooling device of the present invention is not limited to that described above. For example, a tank (not shown) for receiving the leaked cooling water below the spent fuel storage pool 61 is installed in advance, and the cooling water is circulated from the tank to the cooling device through a filtration demineralizer and a heat exchanger. A system may be provided.

DESCRIPTION OF SYMBOLS 1 Cooling device 12 Sparger piping 13 Sprinkling piping 14 Injection port 15 Spray head 21 Drive device 51 Reactor 54 Fuel rod 56 Fuel replacement device 61 Spent fuel storage pool

Claims (4)

Water sprinkling means for sprinkling and cooling cooling water contained in a part or all of the object to be cooled, which is accommodated in a cooling pool for cooling the contents,
The said watering means is equipped with the sparger piping arrange | positioned along the side wall of the said cooling pool, The cooling device characterized by the above-mentioned.   The cooling device according to claim 1, wherein the sparger pipe is disposed at a position higher than the object to be cooled. The watering means further comprises a watering pipe that can be expanded and contracted and / or stretched, and a drive device that expands and contracts and / or stretches the watering pipe,
3. The cooling device according to claim 1, wherein the driving device sends out the watering pipe to the sky above the cooling pool, and stores the watering pipe outside the cooling pool. A spent fuel storage pool installed in a nuclear power plant to contain and cool spent fuel,
A cooling device according to any one of claims 1 to 3,
The sprinkling means is disposed at a position that does not interfere with the fuel replacement device that transports the spent fuel to the spent fuel storage pool and / or can be stored at a position that does not interfere with the fuel replacement device. A featured spent fuel storage pool.

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