JP5734830B2 - Fuel pool heat transport equipment - Google Patents

Description

  The present invention relates to a heat transport device for cooling a hot stored liquid, and more particularly to a heat transport device used in a fuel pool of a nuclear power plant that stores spent fuel.

The present invention relates to a heat transport device for cooling a hot stored liquid. Here, an example applied to a fuel pool of a nuclear power plant for storing spent fuel will be described.
A conventional cooling system for a fuel pool of a nuclear power plant for storing spent fuel will be described with reference to FIG. FIG. 7 is a schematic diagram of a fuel pool that is provided in the building 31 of the nuclear power plant and stores the spent nuclear fuel 33.

  The spent fuel 33 used in the nuclear reactor is stored in a fuel pool 32 installed in the nuclear reactor building 31. The temperature of the pool water 34 in the fuel pool 32 rises due to the heat generated from the spent fuel 33 (decay heat). This pool water 34 flows into the skimmer surge tank 35 and is generated in the heat exchanger 37 by the pump 36. After the heat is removed, it is returned to the storage pool 32 again. The generated heat removed by the heat exchanger 37 is released from the secondary system of the heat exchanger 37 into the sea or the like (not shown).

  As described above, the conventional spent fuel pool 32 is cooled by circulating the pool water 34 through the heat exchanger 37 by a dynamic device represented by the pump 36. Accordingly, when the power source is lost for some reason, the pool water 34 cannot be cooled, and the temperature of the pool water 34 rises due to decay heat. If the power supply cannot be restored, the water level of the fuel pool will decrease due to evaporation, and eventually the cooling water will be lost, increasing the possibility of damage to spent fuel.

  For this reason, even if all three functions of all AC power supply, seawater cooling function and spent fuel pool cooling function are lost due to tsunami etc., core damage and spent fuel damage are prevented, and radioactive materials are released. There is a demand for a cooling device that can recover the cooling function while suppressing the temperature. Among these, regarding the cooling of the spent fuel pool, assuming the loss of the existing cooling system, a device capable of cooling the pool water is required even in a situation where external power is not available.

  By the way, in the field of general consumer equipment or industrial equipment, as a cooling means that does not use external power, a heat transport device that uses heat convection generated by a density difference between a heat sink and a circulating fluid is conventionally known (Patent Document 1). . In addition, in a cooling device for high calorific value, a device combined with a heat pipe is also used.

JP 2005-283014 A

  By the way, when a heat transport device using a heat pipe is used as a heat transport device that does not use external power, one of the heat pipes is in direct contact with the pool water and the other is installed above the fuel pool. It is necessary to fix the pipe to the side wall of the fuel pool with a support or a fixture. However, there is a possibility that the support tool and the fixing tool may be damaged or dropped due to an earthquake or aged deterioration, and the heat pipe may be damaged accordingly. In this case, the cooling function by the heat pipe is lost.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel pool heat transport device that can cool fuel pool water stably over a long period of time without using external power. And

  In order to solve the above problems, a fuel pool heat transport device according to an embodiment of the present invention is disposed on the water surface of the fuel pool and a riser pipe that receives heat from the pool water of the fuel pool under the water surface. An upper communication pipe connected to the upper end of the riser, a lower communication pipe connected to the lower end of the riser, a downcomer connected to the upper communication pipe and the lower communication pipe, and A heat transport device for a fuel pool having an upper side and a heat insulation portion covering the lower side of the downcomer, wherein the specific gravity of the heat insulation portion is set to the pool water so that the heat transport device floats on the water surface of the fuel pool. It is characterized by being smaller than the specific gravity.

  Further, the fuel pool heat transport device according to the embodiment of the present invention includes a rising pipe that receives heat from the pool water of the fuel pool under the water surface, and an upper end portion of the rising pipe that is disposed on the water surface of the fuel pool. An upper communication pipe connected to the lower pipe, a lower communication pipe connected to the lower end of the riser pipe, a heat insulating part covering the upper side of the riser pipe and the upper communication pipe, and installed outside the fuel pool. A heat transport device for a fuel pool having an upper communication pipe and a cooler connected to the lower communication pipe, wherein the specific gravity of the heat insulating portion is set to the pool water so that the heat transport device floats on the water surface of the fuel pool. It is characterized by being smaller than the specific gravity.

  According to the present invention, the fuel pool water can be stably cooled over a long period of time without using external power.

Sectional drawing of the heat transport apparatus of the fuel pool which concerns on 1st Embodiment. The figure which shows the modification of the heat transport apparatus of the fuel pool which concerns on 1st Embodiment. Sectional drawing of the heat transport apparatus of the fuel pool which concerns on 2nd Embodiment. Sectional drawing of the heat transport apparatus of the fuel pool which concerns on 3rd Embodiment. Sectional drawing of the heat transport apparatus of the fuel pool which concerns on 4th Embodiment. Sectional drawing of the heat transport apparatus of the fuel pool which concerns on 5th Embodiment. The block diagram of the conventional cooling device of a fuel pool.

  Embodiments of a fuel pool heat transport device according to the present invention will be described below with reference to the drawings.

[First Embodiment]
A heat transport device according to a first embodiment will be described with reference to FIGS. 1 and 2.
(Constitution)
As shown in FIG. 1, the heat transport device 10 according to the first embodiment includes a rising pipe 1 that is below the water surface and receives heat from the pool water 6, and a rising pipe 1 that is exposed on the water surface. The upper communication pipe 3 connected to the upper end of the pipe and cooled by the ambient atmosphere, the lower communication pipe 4 connected to the lower end of the riser 1, and the condensed water that has become a liquid phase in the upper communication pipe 3 The down pipe 2 is guided to the pipe 4, and the heat insulating portion 5 covers the upper side of the up pipe 1 and the lower side of the down pipe 2. As each pipe, a pipe having a cross-sectional shape such as a rectangle, a circle, or an ellipse is used.

A member having a specific gravity smaller than that of the pool water is used for the heat insulating portion 5. For example, a heat insulating resin or porous ceramic (alumina, silica, etc.) having a small specific gravity, a hollow annular member made of a heat insulating material, or a hollow annular member coated with a heat insulating paint, or the like is used. Thereby, the heat insulation part 5 has a heat insulation function and a float function.
When the heat transport device 10 is arranged in the fuel pool 32, the heat transport device 10 floats on the water surface of the fuel pool 32 due to the buoyancy of the heat insulating portion 5.

In the ascending pipe 1, the heat insulating part 5 covers most of the ascending pipe 1 exposed on the water surface so as not to receive heat from the high temperature atmosphere immediately above the water surface, and does not hinder heat reception from the hot pool water 6 below the water surface. Thus, it arrange | positions so that the ascending pipe | tube 1 may be exposed as much as possible. In the downcomer 2, the heat insulating portion 5 is disposed so as to cover most of the downcomer 2 below the water surface in order to prevent re-evaporation of the liquid descending the downcomer 2.
Thus, the length and volume of the heat insulation part 5 installed in the riser 1 and the downfall 2 are appropriately adjusted so as to be in the heat receiving state and the floating state as described above.

In the present embodiment, water is used as a heat transport medium in the heat transport apparatus 10, and the saturated vapor pressure is adjusted to a desired pressure before the apparatus is operated. Water is easily available, and even if the piping is damaged, the influence on the surroundings is small. Further, by adjusting the saturated vapor pressure before the operation of the apparatus, it is possible to change the operation start temperature of the apparatus and optimally adjust the heat transport efficiency.
Of course, a medium other than water can be used as the heat transport medium.

  Further, in the example of FIG. 1, the example of one and two ascending pipes 1 and two descending pipes 2 has been described, but the present invention is not limited to this and can be increased or decreased as appropriate. For example, in the modification shown in FIG. 2, three downcomers 2 are provided, and the heat insulating portion 5 is integrated. Thereby, heat transport efficiency can further be improved.

(Function)
In the heat transport device 10 configured as described above, the lower part of the riser pipe 1 and the lower communication pipe 4 receive the heat of the pool water 6, and the liquid inside boils into a gas phase and rises in the riser pipe 1. To the upper communication pipe 3. The upper communication pipe 3 is cooled by the ambient temperature, and the steam is cooled and condensed to change into a liquid phase. Condensed water descends down the downcomer 2 and is guided to the lower communication tube 4 to receive the heat of the pool water 6 and boils again. In addition, 11 of FIG. 1 is a heat receiving condition, 12 is a heat flow which shows a thermal radiation condition.

  By repeating this cycle, the heat transport device 10 can cool the pool water 6 in the fuel pool 32 in a long-term and efficient manner using a passive device without using an active device. Further, since the heat transport device 10 is used in a state of floating in the fuel pool 32, it is not necessary to fix the heat transport device 10 to the fuel pool wall or the like by using a support or a fixture. Damage to the heat transport device will not cause malfunction.

(effect)
According to the first embodiment, since the heat transport device 10 is used while being floated on the water surface of the fuel pool 32, it is not necessary to use a support or a fixture. As a result, the heat transport device is not damaged due to dropping or breakage of the support member or the like due to an earthquake or aging deterioration, and thus the pool water 6 of the fuel pool 32 can be stably cooled over a long period of time.

In addition, although this heat transport apparatus 10 may be thrown into the fuel pool 32 at the time of the accident of a nuclear power plant, it can be used for cooling the pool water 6 also at the normal time.
Further, if the necessary heat buoyancy is obtained by the heat insulating portion 5 installed in the downcomer 2, it is not necessary to install the heat insulating portion in the ascending pipe 1.

[Second Embodiment]
A heat transport apparatus according to the second embodiment will be described with reference to FIG.
In the heat transport device 10 according to the second embodiment, the cross-sectional shape of the riser 1 is increased as it goes upward. Thereby, the volume expansion in the case where the liquid phase changes to the gas phase in the downcomer 2 can be absorbed, the upward flow of steam can be promoted, and the heat transport capability can be improved.

  In addition, in the example of FIG. 3, although it has set as the structure which expanded the upper part of the riser 1 on a water surface, it is not limited to this, It is good also as a structure which expands the whole riser 1 toward upper direction from the downward direction.

[Third Embodiment]
A heat transport device according to a third embodiment will be described with reference to FIG.
The heat transport apparatus 10 according to the third embodiment has a configuration in which a plurality of ascending pipes 1 and descending pipes 2 are annularly arranged.

  As shown in FIG. 4, the heat transport device 10 has a plurality of upper pipes 1 arranged annularly on the outside, a plurality of descending pipes 2 arranged annularly on the inside, and a circular shape at each upper and lower end portion. The annular upper communication pipes 3a and 3b and the lower communication pipes 4a and 4b are connected, and the upper communication pipes 3a and 3b and the lower communication pipes 4a and 4b are connected by radial communication pipes 3c and 4c. Each of the plurality of ascending pipes 1 and descending pipes 2 is provided with a heat insulating portion 5.

  According to the third embodiment, the plurality of ascending pipes 1 and descending pipes 2 are annularly arranged, so that the center of gravity of the heat transport device is near the center, and the heat transport device can float more stably. Therefore, it becomes possible to further improve the stability and thermal efficiency of the heat transport device.

[Fourth Embodiment]
A heat transport device according to a fourth embodiment will be described with reference to FIG.

(Constitution)
The heat transport device 10 according to the fourth embodiment covers the upper part and the upper communication pipe 3 exposed at least on the water surface of the plurality of rising pipes 1 with the heat insulating part 5, and is generated in the lower part of the rising pipe 1. The vapor is guided to the cooler 7 provided outside the fuel pool 32 through the upper communication pipe 3 and the pipe 21. Further, the condensed water that has become a liquid phase in the cooler 7 is guided to the lower communication pipe 4 via the pipe 22.

The length, width, and volume of the heat insulating portion 5 installed in the rising pipe 1 and the upper communication pipe 3 are set so that the rising pipe 1 can receive heat efficiently and the heat transport device can float stably. Is adjusted as appropriate.
Moreover, the cooler 7 is provided in a suitable place in a building such as an operation floor or outside the building. A plurality of coolers 7 may be provided.

  For the pipes 21 and 22, for example, it is desirable to use an extendable member such as a bellows or an elastic member for at least a part of the pipe so that the movement of the heat transport device due to the fluctuation of the water surface of the fuel pool 32 can be followed. (Not shown).

(Function)
In the heat transport device 10 configured as described above, the lower part of the riser pipe 1 and the lower communication pipe 4 receive the heat of the pool water, the liquid inside boils into a gas phase and rises in the riser pipe 1. It is led to the cooler 7 through the upper communication pipe 3 and the pipe 21. The cooler 7 is cooled by the ambient temperature, and the steam is cooled and condensed to change into a liquid phase. The condensed water is guided to the lower communication pipe 4 through the pipe 22 and again receives the heat of the pool water to boil.

  By repeating this cycle, the heat transport device 10 can cool the pool water 6 in the fuel pool 32 in a long-term and efficient manner using a passive device without using an active device.

  Further, since the heat transport device 10 is used in a state of floating in the fuel pool 6, it is not necessary to fix the heat transport device 10 to the fuel pool wall or the like using a support or a fixture. Damage does not cause the heat transport device to malfunction.

(effect)
According to the fourth embodiment, it is possible to further improve the cooling efficiency by installing the cooler outside the fuel pool, and to reduce the weight of the heat transport device that is put into the fuel pool. Become.
Note that the cooler according to the fourth embodiment may be applied to the heat transport apparatus of the first to third embodiments.

[Fifth Embodiment]
A heat transport device according to a fifth embodiment will be described with reference to FIG.
The heat transport apparatus 10 according to the fifth embodiment is constituted by a single pipe heat pipe 8 having functions of an ascending pipe and a descending pipe.

  The heat pipe 8 receives the heat of the pool water 6 at the lower part, and the liquid inside boiles to become vapor and rises to the upper part of the heat pipe 8, where it is cooled by the surrounding atmosphere, and the condensed water is heated by the gravity. , And receives the heat of the pool water 6 again to boil. The length, width, and volume of the heat insulating portion 5 provided in the heat pipe 8 are such that the heat pipe 8 can receive heat efficiently, and the heat transport device 10 including the heat pipe 8 can stably float. Is adjusted as appropriate.

Further, the number of heat pipes 8 charged into the fuel pool 6 is appropriately increased or decreased according to the heat generation state of the spent fuel.
According to the fifth embodiment, the use of the single pipe heat pipe 8 makes it possible to provide a compact and low-cost heat transport device 10.

  Although the embodiment of the present invention has been described above, the present heat transport device is not limited to the cooling of the fuel pool, and of course can be applied to the case of cooling the hot liquid in the container in various other fields. It is.

  The above-described embodiments are presented as examples, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, combinations, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Rising pipe, 2 ... Downcomer pipe, 3, 3a, 3b ... Upper communication pipe, 4, 4a, 4b ... Lower communication pipe, 3c, 4c ... Communication pipe, 5 ... Heat insulation part, 6 ... Pool water, 7 ... Cooling 8 ... Heat pipe, 10 ... Heat transport device, 21 ... Piping, 22 ... Piping, 31 ... Building, 32 ... Fuel pool, 33 ... Spent fuel, 34 ... Pool water, 35 ... Skimmer surge tank, 36 ... Pump 37 ... Heat exchanger.

Claims (7)

A riser pipe that receives heat from the pool water of the fuel pool under the water surface, an upper communication pipe that is disposed on the water surface of the fuel pool and connected to the upper end part of the riser pipe, and is connected to the lower end part of the riser pipe And a heat transfer device for a fuel pool, comprising: a lower communication pipe, a lower pipe connected to the upper communication pipe and the lower communication pipe, and a heat insulating portion covering an upper side of the rise pipe and a lower side of the down pipe Because
The heat transport device for a fuel pool, wherein the specific gravity of the heat insulating portion is made smaller than the specific gravity of the pool water so that the heat transport device floats on the water surface of the fuel pool.   2. The fuel pool heat transport device according to claim 1, wherein the heat insulating portion is formed of a hollow annular member coated with heat insulating resin or porous ceramic, or heat insulating or heat insulating paint.   The fuel pool heat transport device according to claim 1, wherein a plurality of the rising pipes and the down pipes are provided.   4. The heat transport device for a fuel pool according to claim 1, wherein a cross-sectional shape of the riser pipe is expanded upward. 5.   An annular upper communication pipe is connected to the upper ends of the ascending pipe and the down pipe, and the upper communication pipes are connected to each other by a communication pipe, and an annular upper communication pipe is connected to the lower ends of the ascending pipe and the down pipe, respectively. 5. The fuel pool heat transport device according to claim 1, wherein the lower communication pipes are connected to each other by a communication pipe. A riser pipe that receives heat from the pool water of the fuel pool under the water surface, an upper communication pipe that is disposed on the water surface of the fuel pool and connected to the upper end part of the riser pipe, and is connected to the lower end part of the riser pipe A lower communication pipe, a heat insulating portion covering the upper communication pipe and the upper communication pipe, and a cooler installed outside the fuel pool and connected to the upper communication pipe and the lower communication pipe. A fuel pool heat transport device,
The heat transport device for a fuel pool, wherein the specific gravity of the heat insulating portion is made smaller than the specific gravity of the pool water so that the heat transport device floats on the water surface of the fuel pool.   7. The fuel pool heat transport device according to claim 6, wherein at least a part of a pipe connecting the cooler and the upper communication pipe and the lower communication pipe is formed of an extendable member.

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