JP2013185992A - Cooling system for spent fuel storage pool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow semi-permanent cooling of pool water in a spent fuel storage pool even when all power supply is lost.SOLUTION: A cooling system 15 for spent fuel storage pool cools pool water of a spent fuel storage pool 10 which stores spent fuel 12 by submerging it in the pool water 11. It comprises: a cooling piping 16 which has a vertical part 19 disposed outside the spent fuel storage pool in a vertical direction and is provided with an upper end part 20 and a lower end part 21, respectively connected to the upper end and the lower end of the vertical part and communicating with the inside of the spent fuel storage pool 10; and a duct 17 which is disposed extending in a vertical direction outside the spent fuel storage pool 10, accommodates the cooling piping 16 therein and has an upper end opening 22 and a lower end opening 23 which are open to the atmosphere. It is configured in such a manner that the pool water 11 flowing into the cooling piping 16 from the upper end part 20 exchanges heat with air rising in the duct 17 and is cooled down.

Description

  The present invention relates to a spent fuel storage pool cooling system that cools pool water in a spent fuel storage pool installed in a nuclear reactor facility such as a nuclear power plant.

  When an emergency such as an earthquake or tsunami occurs and the reactor equipment needs to be cooled, for example, a safety system that exchanges heat with the low-temperature fluid to dissipate heat in the reactor containment vessel, or a reactor A system for cooling a nuclear reactor by injecting water into a pressure vessel with a cooling water injection spray has been proposed.

  For example, in Patent Document 1, a pool that holds cooling water (pool water) is installed outside the reactor containment vessel, and a tubular heat exchanger is installed in the pool, and the reactor is stored in the heat exchanger. A system has been proposed in which steam generated in the vessel is led to condense the steam in the reactor containment vessel with the pool water and cool it, thereby reducing the pressure in the reactor containment vessel.

JP 2007-170832 A

  An emergency such as an earthquake or tsunami occurs in the reactor equipment, especially the reactor equipment loses the external power supply, and the emergency reactor cooling system and the spent fuel storage pool cooling system that operate using an electric pump etc. operate In preparation for such a case, a cooling system that does not require power is desired.

  In this case, in the system described in Patent Document 1, the steam in the reactor containment vessel is condensed and cooled by circulating naturally through a heat exchanger using finite cooling water (pool water) as a cold source. As the temperature of water rises, the performance of heat exchange gradually decreases, and there is a possibility that the cooling effect cannot be sustained semipermanently.

  An object of the present invention is to provide a spent fuel storage pool cooling system capable of semi-permanently cooling the pool water of the spent fuel storage pool even when the entire power source is lost. It is in.

  The present invention is a spent fuel storage pool cooling system for cooling the pool water of a spent fuel storage pool that stores the spent fuel immersed in the pool water, wherein a vertical portion is outside the spent fuel storage pool. And an upper end and a lower end connected to the upper end and the lower end of the vertical portion, respectively, and a cooling pipe provided in communication with the spent fuel storage pool. And a duct that extends vertically outside the spent fuel storage pool, accommodates the cooling pipe therein, and has an upper end opening and a lower end opening opened to the atmosphere, The pool water flowing from the upper end into the cooling pipe is configured to be able to cool by exchanging heat with the air rising in the duct.

  According to the present invention, the pool water flows into the cooling pipe disposed outside the spent fuel storage pool from the upper end thereof, so that the air has a density difference in the duct housing the cooling pipe. It rises by. The pool water in the cooling pipe is cooled by this upward flow of air, and the pool water in the cooling pipe circulates between the spent fuel storage pool due to the density difference, so even when the entire power supply is lost. The pool water in the spent fuel storage pool can be cooled semipermanently.

The block diagram which shows 1st Embodiment of the spent fuel storage pool cooling system which concerns on this invention. FIG. 2 is an enlarged longitudinal sectional view showing the cooling pipe and duct of FIG. 1 in an enlarged manner. Sectional drawing which follows the III-III line | wire of FIG. The IV arrow line view of FIG. (A) is a cross-sectional view showing a modified form of the cooling pipe in FIG. 2, and (B) is a cross-sectional view showing another modified form of the cooling pipe in FIG. The block diagram which shows 2nd Embodiment of the spent fuel storage pool cooling system which concerns on this invention. The block diagram which shows 3rd Embodiment of the spent fuel storage pool cooling system which concerns on this invention.

Embodiments for carrying out the present invention will be described below with reference to the drawings.
[A] First embodiment (FIGS. 1 to 5)
FIG. 1 is a configuration diagram showing a first embodiment of a spent fuel storage pool cooling system according to the present invention. The spent fuel storage pool 10 shown in FIG. 1 is located outside a reactor containment vessel (not shown) for storing a reactor pressure vessel in a reactor building (not shown) in a nuclear reactor facility such as a nuclear power plant. is set up. The spent fuel storage pool 10 has a rectangular shape and is filled with pool water (cooling water) 11. The spent fuel 12 used in the reactor pressure vessel is submerged in the pool water 11 and cooled. Store in condition. The spent fuel 12 is installed on the bottom surface 13 of the spent fuel storage pool 10.

  The spent fuel storage pool cooling system 15 of the present embodiment cools the pool water 11 of the spent fuel storage pool 10 without using dynamic equipment such as an electric motor, and includes a cooling pipe 16 and a duct 17. And a baffle plate 18 as a partition wall.

  A plurality of cooling pipes 16 are provided, each of which has a vertical portion 19 extending in the vertical direction, an upper end portion 20 connected to the upper end of the vertical portion 19, and a lower end connected to the lower end of the vertical portion 19. Part 21. The vertical portion 19 of each cooling pipe 16 is disposed in the vertical direction outside the side wall of the spent fuel storage pool 10. Further, the upper end 20 and the lower end 21 of each cooling pipe 16 are communicated with the inside of the spent fuel storage pool 10, and the upper end 20 of these is the pool water 11 in the spent fuel storage pool 10. The lower end 21 is provided near the bottom surface 13 of the spent fuel storage pool 10.

  As shown in FIGS. 2 and 3, the duct 17 has, for example, a rectangular tube shape, and is arranged to extend in the vertical direction outside the side wall of the spent fuel storage pool 10. The cooling pipe 16 is accommodated. The duct 17 has an upper end opening 22 and a lower end opening 23 open to the atmosphere. The pool water 11 having a high temperature flowing into the cooling pipe 16 from the upper end portion 20 dissipates heat in the duct 17, so that the air in the duct 17 generates a density difference due to a temperature change. An upward flow of air is generated. The pool water 11 flowing into the cooling pipe 16 and descending the vertical portion 19 is cooled by exchanging heat with the air rising in the duct 11.

  At this time, the length L of the duct 17 is set to be longer than the length N of the vertical portion 19 of the cooling pipe 16 by about 1.3 times or more, preferably about 2 times or more. As a result, in the duct 17, due to heat radiation of the pool water 11 flowing into the cooling pipe 16, an air density difference between the upper end opening 22 and the lower end opening 23 increases, and from the lower end opening 23 to the inside of the duct 17. A lot of air is inhaled, and the flow rate of the air rising in this duct 17 can be increased.

  A plurality of the baffle plates 18 are arranged in the duct 17 at a predetermined interval in the longitudinal direction of the duct 17. These adjacent baffle plates 18 are formed with airflow openings 24 at positions opposite to each other with respect to the axis O of the duct 17. As a result, the air rising in the duct 17 rises by meandering through the air flow opening 24 of the baffle plate 18 as shown by the arrow A, and collides with the vertical portion 19 of the cooling pipe 16 in the vertical direction. Thus, the efficiency of heat exchange with the pool water 11 flowing in the vertical portion 19 is increased.

Next, the operation will be described.
In the spent fuel storage pool cooling system 15, the pool water 11 in the spent fuel storage pool 10 heated by the spent fuel 12 flows upward due to the density difference caused by the temperature change, and the spent fuel storage pool 10. In the vicinity of the water surface 11 </ b> A of the pool water 11, the water flows toward the upper end 20 of the cooling pipe 16 and is sucked into the upper end 20. The sucked pool water 11 having a high temperature is subjected to heat exchange with the air in the duct 17 in the cooling pipe 16 and the temperature is lowered, and flows downward in the vertical portion 19.

  On the other hand, the air in the duct 17 heated by the heat radiation of the pool water 11 in the cooling pipe 16 rises due to the density difference due to the temperature change, and sucks air (atmosphere) from the lower end opening 23. The sucked air rises while meandering through the air flow opening 24 of the baffle plate 18 as indicated by an arrow A in the duct 17 and collides with the vertical portion 19 of the cooling pipe 16 in the vertical direction. Then, the pool water 11 in the cooling pipe 16 is cooled.

  The cooled pool water 11 returns to the spent fuel storage pool 10 from the lower end 21 of the cooling pipe 16 and cools the spent fuel 12. In this manner, the pool water 11 naturally circulates between the spent fuel storage pool 10 and the cooling pipe 16 due to the density difference due to the temperature change.

With the configuration as described above, the following effects (1) to (3) are achieved according to the present embodiment.
(1) The inside of the duct 17 that accommodates the cooling pipe 16 by the pool water 11 flowing into the plurality of cooling pipes 16 disposed outside the spent fuel storage pool 10 from the upper end 20 thereof. This air is heated by the pool water 11 having a high temperature in the cooling pipe 16 and rises in the duct 17 due to the density difference. Pool water 11 in the cooling pipe 16 is cooled by the upward flow of air in the duct 17, and the pool water 11 in the cooling pipe 16 circulates between the spent fuel storage pool 10 due to the density difference. To do. As a result, the pool water 11 of the spent fuel storage pool 10 can be semi-permanently cooled even when the entire power source is lost, and the decay heat of the spent fuel 12 in the spent fuel storage pool 10 can be removed.

  (2) Since the length L of the duct 17 is set to be about 1.3 times longer than the length N of the vertical portion 19 of the cooling pipe 16, the pool water 11 in the cooling pipe 16 is set in the duct 17. Due to the heat radiation, the difference in the air density between the vicinity of the upper end opening 22 and the vicinity of the lower end opening 23 becomes large, and a large amount of air (atmosphere) is sucked into the duct 17 from the lower end opening 23 by the upward flow of air generated in the duct 17 be able to. For this reason, the air flow rate rising in the duct 17 increases, and the heat exchange efficiency between the pool water 11 in the cooling pipe 16 and the air in the duct 17 can be improved.

  (3) In the duct 17, a plurality of baffle plates 18 are arranged at a predetermined interval in the longitudinal direction of the duct 17, and the adjacent baffle plates 18 are located at positions opposite to each other on the axis O of the duct 17. A flow opening 24 is formed. Therefore, the air rising in the duct 17 meanders and rises through the air flow opening 24 of the baffle plate 18, and thus collides with the vertical portion 19 of the cooling pipe 16 in the vertical direction. . Therefore, also from this configuration, the heat exchange efficiency between the pool water 11 flowing in the cooling pipe 16 and the air flowing in the duct 17 can be improved.

  In the duct 17 in the first embodiment, as shown in FIG. 2 and FIG. 4, the upper section (for example, the section 25 in FIG. 2) among the plurality of sections partitioned by the plurality of baffle plates 18. An air introduction opening 26 for directly introducing the air (atmosphere) outside the duct 17 into the duct 17 may be formed on the side surface of the duct 17 constituting the above. Since the pool water 11 flowing in the cooling pipe 16 has a high temperature on the side close to the upper end 20 of the vertical portion 19, the pool water 11 is more efficiently pooled by the air introduced into the duct 17 from the air introduction opening 26. The water 11 can be cooled.

  Further, in the vertical portion 19 of the cooling pipe 16 in the first embodiment, as shown in FIG. 5 (A), heat radiating fins 27 are fixed to the outside, and the pool water 11 in the vertical portion 19 and the duct 17 Heat transfer efficiency with air may be improved. Alternatively, as shown in FIG. 5B, the vertical portion 28 of the cooling pipe 16 is configured by a flat plate-like tube, and increases the contact area with the air flowing in the direction of arrow A in the duct 17. The heat transfer efficiency between the pool water 11 in the vertical portion 19 and the air in the duct 17 may be improved.

[B] Second Embodiment (FIG. 6)
FIG. 6 is a block diagram showing a second embodiment of the spent fuel storage pool cooling system according to the present invention. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The spent fuel storage pool cooling system 30 of the second embodiment is different from the first embodiment in the configuration of a plurality of baffle plates 31 as partition walls. That is, the plurality of baffle plates 31 are arranged obliquely at an angle θ with respect to the horizontal so that the flow path area of the air formed between the adjacent baffle plates 31 gradually increases toward the downstream side.

  Therefore, according to the second embodiment, in addition to the same effects as the effects (1) to (3) of the first embodiment, the following effect (4) is achieved.

  (4) The plurality of baffle plates 31 arranged in the duct 17 have an angle θ with respect to the horizontal so that the flow area of the air formed between the adjacent baffle plates 31 gradually increases toward the downstream side. Only installed diagonally. For this reason, the flow of the air which meanders in the duct 17 and rises becomes smooth. As described above, since air easily flows in the duct 17, the heat exchange efficiency between the pool water 11 in the cooling pipe 16 and the air in the duct 17 can be further improved.

[C] Third embodiment (FIG. 7)
FIG. 7 is a block diagram showing a third embodiment of the spent fuel storage pool cooling system according to the present invention. In the third embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The spent fuel storage pool cooling system 40 of the third embodiment is different from the first embodiment in that the first guide plate 41 is located above the spent fuel storage pool 10 in the spent fuel storage pool 10. The second guide plate 42 is installed at a substantially central position in the vertical direction.

  The first guide plate 41 is disposed above the upper end 20 of the cooling pipe 16 inside the spent fuel storage pool 10, and the spent fuel 12 and the cooling pipe 16 installed in the spent fuel storage pool 10. It is formed in a curved shape so as to cover the upper end portion 20. The pool water 11 heated by the spent fuel 12 in the spent fuel storage pool 10 flows upward due to the density difference due to the temperature change, and is cooled along the first guide plate 41 as indicated by an arrow B. It is smoothly guided to the upper end 20 of the pipe 16.

  The second guide plate 42 is disposed between the upper end 20 and the lower end 21 of the cooling pipe 16 inside the spent fuel storage pool 10, and is used in the spent fuel storage pool 10. It is positioned in a horizontal state slightly above the fuel 12. The pool water 11 that has flowed through the cooling pipe 16 and cooled by the air in the duct 17 flows out from the lower end portion 21 of the cooling pipe 16 into the spent fuel storage pool 10. Guided by the plate 42, as indicated by an arrow C, it flows from the lower end 21 toward the spent fuel 12 in the spent fuel storage pool 10, and the spent fuel 12 is efficiently cooled.

  Therefore, according to this embodiment, in addition to the same effects as the effects (1) to (3) of the first embodiment, the following effect (5) is achieved.

  (5) In the spent fuel storage pool 10, a curved first guide plate 41 is installed so as to cover the upper end 20 of the cooling pipe 16 and the spent fuel 12, and the spent fuel 12 The second guide plate 42 is installed in a horizontal state slightly above. Therefore, the pool water 11 heated in the spent fuel storage pool 10 can be guided to the upper end 20 of the cooling pipe 16 by the first guide plate 41, and the pool water 11 cooled in the cooling pipe 16 is used. Can be guided from the lower end 21 of the cooling pipe 16 to the spent fuel 12 in the spent fuel storage pool 10 by the second guide plate 42. As a result, the flow of the pool water 11 in the spent fuel storage pool 10 can be smoothly performed, and the pool water 11 can be smoothly circulated between the spent fuel storage pool 10 and the cooling pipe 16.

  As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this, A component may be variously deformed in the range which does not deviate from the summary, and it covers different embodiment. You may combine a component suitably.

10 spent fuel storage pool 11 pool water 12 spent fuel 15 spent fuel storage pool cooling system 16 cooling pipe 17 duct 18 baffle plate (partition wall)
DESCRIPTION OF SYMBOLS 19 Vertical part 20 Upper end part 21 Lower end part 22 Upper end opening 23 Lower end opening 24 Air flow opening 25 Compartment 26 Air introduction opening 27 Radiation fin 28 Vertical part 30 Spent fuel storage pool cooling system 31 Baffle plate 40 Spent fuel storage pool cooling system 41 First guide plate 42 Second guide plate L, N Length O Axis θ Angle

Claims (7)

A spent fuel storage pool cooling system that cools the pool water of a spent fuel storage pool that stores the spent fuel immersed in pool water,
A vertical portion is vertically disposed outside the spent fuel storage pool, and an upper end and a lower end connected to the upper end and the lower end of the vertical portion are the interior of the spent fuel storage pool. Cooling piping provided in communication with
A duct extending in the vertical direction outside the spent fuel storage pool, accommodating the cooling pipe therein, and having a top opening and a bottom opening opened to the atmosphere;
The spent fuel storage pool cooling system, wherein the pool water flowing into the cooling pipe from the upper end portion can be cooled by exchanging heat with the air rising in the duct. In the duct, a plurality of partition walls are arranged at predetermined intervals in the longitudinal direction, and an air flow opening is formed at a position opposite to the duct axis in these adjacent partition walls, The spent fuel storage pool cooling system according to claim 1, wherein the air in the duct is configured to meander and rise through the air flow opening. 3. The used partition according to claim 2, wherein the partition wall is installed obliquely with respect to the horizontal so that an air flow path area formed between these adjacent partition walls gradually increases toward the downstream. Fuel storage pool cooling system. In the spent fuel storage pool, the upper end and the spent fuel are covered above the upper end of the cooling pipe, and the pool water heated by the spent fuel is guided to the upper end. The spent fuel storage pool cooling system according to any one of claims 1 to 3, wherein a first guide plate is provided. In the spent fuel storage pool, the cooled pool water flowing out from the lower end is guided between the upper end and the lower end of the cooling pipe toward the spent fuel. The spent fuel storage pool cooling system according to any one of claims 1 to 4, wherein two guide plates are installed. In the duct, air for introducing air outside the duct into the duct is formed on a side surface of the duct that constitutes an upper section of the plurality of sections partitioned by a plurality of partition walls. The spent fuel storage pool cooling system according to any one of claims 2 to 5, wherein an opening is formed. The spent fuel storage pool according to any one of claims 1 to 5, wherein the cooling pipe is configured by a fin tube or a flat plate-like tube provided with heat radiation fins on the outside. Cooling system.

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