JP2004020376A - Cooler for nuclear reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooler for reactor superior in cooling efficiency for efficiently removing decay heat in LOCA(loss-of-coolant accident) occurrence. <P>SOLUTION: Heat conduction pipe bundles 33a and 33b consisting of a multitude of heat conduction pipes 34 are arranged by turns and arranged obliquely toward the lower end 25a of a partition member 25 from near the bottom surface 37 so as to spatially block an air flow-out path 24 in a connection part 26. Tank water 38 is stored to the level almost covering the heat conduction pipes 34. The heat conduction pipes 34 of the heat conduction pipe bundles 33a and 33b in submerged state are cooled by the tank water 38. The heat conduction pipes 34 exposed over the upper surface of the tank water 38 because of the tank water 38 evaporation and water level lowering, are cooled by the air flow flowing in the air inlet 21 and flowing out of an air outlet 23. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reactor cooler, and more particularly to a cooling system integrated type reactor in which a primary coolant for cooling a reactor core and a cooling system for cooling the primary coolant are integrated into a reactor vessel. The present invention relates to a cooler that is used in a decay heat removal device and cools a primary coolant that is heated by decay heat and cools a secondary coolant that is heated.
[0002]
[Prior art]
Japanese Patent Application No. 2001-301980 filed by the present applicant as a cooler used for a decay heat removal device of a cooling system integrated reactor and for cooling secondary cooling water evaporated by a steam generator. -230042. As shown in FIGS. 5 and 6, the cooler 1 is composed of a bottomed cylindrical tank 3 through which a heat transfer tube 2 penetrates, and usually stores tank water 4 in the tank 3. The inside of the tank 3 is divided by a partition plate 5 into a region through which the heat transfer tube 2 penetrates and a region where the heat transfer tube 2 does not penetrate, and these regions communicate with each other on the tank bottom side.
[0003]
When a primary coolant loss accident (Loss of Coolant Accident, hereinafter referred to as “LOCA”) occurs in a nuclear reactor, the heat of the primary coolant is exchanged with the secondary coolant in a steam generator (not shown), and the primary coolant is exchanged. As the cooling water is cooled, the secondary cooling water becomes steam and is introduced from the steam generator to the heat transfer tube 2 in the cooler 1. The steam flowing inside the heat transfer tube 2 is cooled and condensed by the tank water 4 around the heat transfer tube 2 and returned to water. This water is supplied to the steam generator again by dropping in the heat transfer tube 2 by its own weight, and is used to cool the inside of the reactor vessel.
Further, the tank water 4 of the cooler 1 receives heat from the steam flowing inside the heat transfer tube 2, boils and evaporates, and the water level of the tank water 4 decreases. The air directly hits the heat transfer tube 2 exposed above the water surface of the tank water 4, and the entire heat transfer tube 2 is air-cooled by the flow of the air as shown in FIG.
[0004]
[Problems to be solved by the invention]
However, in the above-described cooler 1, when the secondary cooling water is water-cooled using the tank water 4, a large amount of the tank water 4 is required. Further, since the heat transfer tube 2 is not disposed to the bottom of the tank, it was not possible to effectively use all of the tank water 4 and perform water cooling. Furthermore, efficient cooling cannot be performed even by air cooling with air.
[0005]
The present invention has been made to solve such a problem, and an object of the present invention is to provide a reactor cooler having excellent cooling efficiency in order to efficiently remove decay heat when LOCA occurs. .
[0006]
[Means for Solving the Problems]
The reactor cooler according to the present invention is connected to a steam generator that cools the reactor core, performs heat exchange with the primary coolant heated by decay heat, and evaporates the secondary coolant, In a reactor cooler for cooling and condensing the evaporated secondary coolant and returning it to the steam generator to remove decay heat, a partition member and a communication portion defined by the partition member and below the partition member communicate with each other. A first and a second vertical passage communicating with each other, and a heat transfer tube group having a plurality of heat transfer tubes through which the secondary coolant flows, wherein the heat transfer tube group has a first vertical passage in a communication portion. It is characterized by being disposed obliquely from the vicinity of the bottom surface of the first vertical passage to the lower end of the partition member so as to spatially close.
[0007]
The uppermost heat exchanger tube of the heat exchanger tube group may be arranged near the lower end of the partition member, and the lowermost heat exchanger tube may be arranged near the bottom surface of the first vertical passage.
In the cooler, cooling water is stored in the first and second vertical passages to a height substantially covering the heat transfer tubes of the heat transfer tube group, and the evaporated secondary coolant is introduced into the heat transfer tubes of the heat transfer tube group. Then, while the secondary coolant is condensed by the cooling water in the first and second vertical passages, the cooling water evaporates, the water level decreases, and the heat transfer tube exposed from the upper surface of the cooling water is connected to the second vertical passage. May be cooled by an airflow flowing into the first vertical passage from the air passage.
The second vertical passage is provided with an air inlet for taking in air from the outside, and the first vertical passage is provided with an air outlet for taking in air from the air inlet and passing through the heat transfer tube group to the outside. The air outlet may be located higher than the air inlet.
An opening / closing door may be provided at each of the air inlet and the air outlet.
In the heat transfer tubes of the heat transfer tube group, the inlet side where the secondary coolant is introduced from the steam generator is provided above the outlet side where the secondary coolant cooled by the heat transfer tubes is discharged to the steam generator. The heat pipe may be arranged so as to be inclined downward from the inlet side to the outlet side throughout.
A part of the heat transfer tube may be provided with a thermal expansion absorbing part whose inclination is steeper than other parts.
A plurality of heat transfer tube groups of the cooler are provided and are divided into first and second heat transfer tube groups that can be connected to two steam generators, respectively. The first heat transfer tube group and the second heat transfer tube group , May be arranged alternately in the vertical direction and the horizontal direction.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a layout view showing a configuration of a decay heat removal device of a cooling system integrated reactor using a reactor cooler 10 according to an embodiment of the present invention.
In the reactor vessel 11, a reactor core 13 immersed in primary cooling water 12 and two steam generators 14 are provided. The steam generator 14 is composed of a plurality of heat transfer tubes, and heat is generated between the primary cooling water 12 heated by energy due to nuclear fission generated in the reactor core 13 and the secondary cooling water 15 flowing in the main steam pipe 7. Make a replacement.
[0009]
The main steam pipe 7 is provided with a turbine 20, a pump 16, and valves 17a and 17b.
In the middle of the main steam pipe 7, between the steam generator 14 and the valve 17 a and between the steam generator 14 and the valve 17 b, the secondary cooling water 15 branches off from the main steam pipe 7 when LOCA occurs. Introducing pipes 19a, 19b, 19c and 19d are provided to be introduced into the cooler 10 and return to the main steam pipe 7 again.
A valve 18a is provided in the middle of the introduction pipes 19a and 19b. A valve 18b is provided in the middle of the introduction pipes 19c and 19d. By opening and closing these valves 17a, 17b, 18a, 18b, the operating state during normal operation is switched to the operating state when LOCA occurs.
[0010]
The cooler 10 is disposed at a position higher than the steam generator 14, and as shown in FIG. 2, two rectangular parallelepipeds having different heights are adjacent to each other, and inside the short rectangular parallelepiped, An air inflow passage 22 into which the outside air flows in through an air inlet 21 located above is formed. In addition, an air outflow passage 24 through which air flows out through an air outflow port 23 located above is formed inside the tall rectangular parallelepiped.
Here, the air outflow passage 24 constitutes a first vertical passage, and the air inflow passage 22 constitutes a second vertical passage. These are defined by a partition member 25 and communicate with each other at a communication portion 26 below the partition member 25. are doing.
[0011]
As shown in FIGS. 2 to 4, the air outlets 23 are respectively provided on both side surfaces, the front surface, and the rear surface of the upper portion of the air outflow passage 24. Is provided. The air inlets 21 are provided on both side surfaces, the front surface, and the upper surface of the upper portion of the air inflow passage 22, respectively.
The air outlet on the side surface of the air outflow passage 24 so as to reduce the pressure loss of the air flowing through the cooler 10 and to provide a driving force suitable for increasing the speed at which the air passes through the heat transfer tube 34 described later. A height difference of about 5 m is provided between the air inlet 23 and the air inlet 21 on the side surface of the air inflow passage 22.
[0012]
As shown in FIGS. 2 and 3, a plurality of first inlet headers 31a, each of which is connected to the inlet pipe 19a, are provided on the rear surface of the cooler 10, and extend obliquely toward the front surface of the cooler 10. I have. Further, a plurality of first outlet headers 32a, each of which is connected to the introduction pipe 19c, are provided, and extend obliquely toward the front surface of the cooler 10. Similarly, on the rear surface of the cooler 10, a plurality of second inlet headers 31b each connected to the inlet pipe 19b and a plurality of second outlet headers 32b each connected to the inlet pipe 19d are provided. 10 extends obliquely toward the front surface.
[0013]
As shown in FIG. 3, between the first inlet header 31a and the first outlet header 32a, there is provided a first heat transfer tube 34 including a plurality of heat transfer tubes 34 extending in the left-right direction and through which the secondary cooling water 15 flows. A heat tube group 33a is arranged and connected to one of the steam generators 14 via a first inlet header 31a and a first outlet header 32a.
Between the second inlet header 31b and the second outlet header 32b, a second heat transfer tube group 33b composed of a large number of heat transfer tubes 34 extending in the left-right direction is arranged, and the second inlet header 31b and the second outlet are provided. It is connected to the other steam generator 14 via a header 32b. The heat transfer tube groups 33a and the heat transfer tube groups 33b connected to the different steam generators 14 are alternately arranged in the horizontal direction and the vertical direction.
[0014]
The heat transfer tubes 34 of the heat transfer tube groups 33a, 33b are inclined downward toward the outlet headers 32a, 32b from the inlet headers 31a, 31b side (IN side) to the outlet headers 32a, 32b side (OUT side). ing. In addition, near the center of each heat transfer tube 34, a thermal expansion absorbing portion 36 having a steeper slope than other portions is formed.
[0015]
On the other hand, as shown in FIG. 2, one heat transfer tube group 33a, 33b is composed of heat transfer tubes 34 in five stages and 50 rows, and a plate-shaped cooling member is provided around the heat transfer tubes 34 in order to increase heat exchange efficiency. A large number of fins 35 are provided so as to be stacked in the direction perpendicular to the plane of FIG.
The heat transfer tube groups 33a and 33b are arranged obliquely at an angle of 30 degrees with respect to the bottom surface 37 from the bottom surface 37 of the air outflow passage 24 toward the lower end 25a of the partition member 25.
These heat transfer tube groups 33a and 33b are arranged obliquely in the communication portion 26 so as to spatially close the air outflow passage 24, and almost all of the air flowing from the communication portion 26 to above the air outflow passage 24 is a heat transfer tube group. It is configured to pass through 33a and 33b.
Before the occurrence of LOCA, the tank water 38 as cooling water is filled up to the lower end 25 a of the partition member 25 so as to substantially cover all the heat transfer tubes 34.
[0016]
Next, the operation of the decay heat removing device of the cooling system integrated reactor using the reactor cooler 10 according to the embodiment of the present invention will be described.
As shown in FIG. 1, during normal operation of the nuclear reactor, the operation is performed with the valves 18a and 18b closed and the valves 17a and 17b opened.
The core 3 heated by the nuclear fission energy is cooled by the primary cooling water 12, and the primary cooling water 12 itself is heated and becomes high-temperature water. The primary cooling water 12 that has become high-temperature water exchanges heat with the secondary cooling water 15 supplied from the pump 6 in the steam generator 14, so that the primary cooling water 12 is cooled and the secondary cooling water 15 It becomes steam and is guided to the turbine 20 via the main steam pipe 7, and the turbine 20 is rotated to generate power.
[0017]
On the other hand, when LOCA occurs in the reactor, the decay heat removal operation is started, the valves 17a and 17b are closed, and the valves 18a and 18b are opened. In the cooler 10, the air inlet 21 and the air outlet 23, which are closed during normal operation to prevent evaporation of the tank water 38 and intrusion of foreign matter from the outside, move the opening and closing door 28 by the operation of the cylinder 27. The air inlet 21 and the air outlet 23 are open.
Although the temperature of the primary cooling water 12 in the reactor vessel 1 rises due to LOCA, the heat of the primary cooling water 12 is used for generating steam in the steam generator 14, so that the primary cooling water 12 is cooled. You.
[0018]
The steam generated by the two steam generators 14 rises to the cooler 10 through the inlet pipes 19a and 19b, and enters the heat transfer tubes 34 of the heat transfer tube groups 33a and 33b through the corresponding inlet headers 31a and 31b. be introduced. The steam in the heat transfer tube 34 is cooled by tank water 38 around the heat transfer tube 34, condensed, and falls into the heat transfer tube 34. Since the heat transfer tubes 34 are inclined toward the outlet headers 32a and 32b, the condensed and liquefied secondary cooling water 15 flows inside the heat transfer tubes 34 toward the outlet headers 32a and 32b by gravity, and the outlet headers 32a and 32b. It is discharged from 32b and returned to the respective steam generators 14 via the corresponding introduction pipes 19c and 19d, and is used again to cool the inside of the reactor vessel 1.
[0019]
On the other hand, as shown in FIG. 2, the tank water 38 used for cooling and condensing the steam in the heat transfer tube 34 receives heat from the steam, and gradually boils and evaporates.
As the tank water 38 evaporates, the water level of the tank water 38 decreases. However, since the heat transfer tube 34 is disposed close to the bottom surface 37, the heat transfer tube 34 is in direct contact with the heat transfer tube 34 until almost all of the tank water 38 is exhausted. Therefore, water cooling by the tank water 38 is maintained in a state of high cooling efficiency. . Therefore, the tank water 38 is effectively used, and the heat transfer tube 34 can be water-cooled efficiently with a minimum amount of the tank water 38.
When the water level of the tank water 38 decreases, most of the air flowing from the open air inlet 21 passes through the heat transfer tube groups 33a and 33b exposed from the water surface. When the tank water 38 almost boils and evaporates, the entire heat transfer tube group 33a, 33b is cooled by the air flowing from the air inlet 21.
[0020]
Since an appropriate height difference is provided between the air outlet 23 and the air inlet 21, the speed at which air passes through the heat transfer tube 34 is high, and the cooling efficiency by air cooling is enhanced. In addition, since most of the air passes through the heat transfer tube groups 33a and 33b, the cooling efficiency by air cooling is also improved. Further, since the heat transfer tube groups 33a and 33b are oriented in a direction almost perpendicular to the flow of air as shown by arrows, the cooling efficiency by air cooling is further enhanced.
Further, since the heat transfer tube groups 33a, 33b connected to the different steam generators 14 are alternately arranged in the vertical direction and the horizontal direction of the cooler, in the process of gradually lowering the water level of the tank water 38. The liquefied secondary cooling water 15 is returned to the two steam generators 14 at a substantially equal ratio, and the primary cooling water 12 can be cooled in each of the steam generators 14 in a well-balanced manner. Furthermore, even if the secondary cooling water 15 returned to one of the steam generators 14 leaks, the decay heat is appropriately removed by the secondary cooling water 15 returned to the remaining steam generators 14.
[0021]
Note that steam is introduced into each heat transfer tube 34 of the cooler 10, and the heat transfer tube 34 thermally expands while being sandwiched between the inlet headers 31a, 31b and the outlet headers 32a, 32b. However, due to the steep thermal expansion absorbing portions 36 formed in the heat transfer tubes 34, the straight portions of the heat transfer tubes 34 extending from the inlet headers 31a, 31b and the straight lines of the heat transfer tubes 34 extending from the outlet headers 32a, 32b. Since an offset is formed between the linear portions, the elongation due to thermal expansion is not hindered in each straight portion. Therefore, the compressive stress applied to the heat transfer tube 34 does not increase rapidly, and the heat transfer tube 34 does not buckle and break.
[0022]
【The invention's effect】
According to the present invention, the reactor cooler is connected to the steam generator that cools the reactor core, performs heat exchange with the primary coolant heated by the decay heat, and evaporates the secondary coolant. In the reactor cooler for cooling, condensing and returning the evaporated secondary coolant to the steam generator to remove the decay heat, the second coolant passage communicating with the second vertical passage at the communication portion below the partition member. Since the heat transfer tube groups are arranged diagonally from the vicinity of the bottom of the vertical passage to the lower end of the partition member, the cooling efficiency is excellent, so it is possible to efficiently remove decay heat when LOCA occurs. it can.
[0023]
Further, according to the present invention, the uppermost heat transfer tube of the heat transfer tube group is disposed near the lower end of the partition member, and the lowermost heat transfer tube is disposed near the bottom surface of the first vertical passage. Until almost all of the cooling water in the cooler is exhausted, the cooling water directly touches the heat transfer tubes, so that the heat transfer tubes can be efficiently water-cooled.
Further, according to the present invention, the cooler stores the cooling water in the first and second vertical passages to a height substantially covering the heat transfer tubes of the heat transfer tube group, and transfers the evaporated secondary coolant to the heat transfer tubes. When introduced into the heat transfer tubes of the heat tube group, the cooling water in the first and second vertical passages condenses the secondary coolant, and the cooling water evaporates to lower the water level and is exposed from the upper surface of the cooling water. Since the heat pipe is cooled by the airflow flowing from the second vertical passage into the first vertical passage, the heat transfer pipe is water-cooled with a minimum amount of cooling water, and the heat transfer pipe exposed from the upper surface of the cooling water is cooled. Air cooling can be performed efficiently.
[0024]
Further, according to the present invention, since the air outlet is disposed at a position higher than the air inlet, the speed at which air passes through the heat transfer tube can be increased, and the cooling efficiency by air cooling can be increased.
Furthermore, according to the present invention, since the opening and closing doors are provided at the air inlet and the air outlet, respectively, during normal operation of the nuclear reactor, evaporation of cooling water in the cooler, foreign matter from the outside, Intrusion can be prevented.
[0025]
Further, according to the present invention, since the heat transfer tube is disposed so as to be inclined downward from the inlet side to the outlet side, the secondary coolant, which is cooled and condensed by the steam, is disposed inside the heat transfer tube. Can flow toward the outlet side by gravity.
Further, according to the present invention, since a part of the heat transfer tube is provided with the thermal expansion absorbing portion whose inclination is steeper than other portions, the heat transfer tube is not damaged by thermal expansion.
Further, according to the present invention, a plurality of heat transfer tube groups are provided, divided into first and second heat transfer tube groups that can be respectively connected to two steam generators, and a first heat transfer tube group and a second heat transfer tube group are provided. Since the heat transfer tube groups are alternately arranged in the vertical direction and the horizontal direction, the primary coolant can be cooled in a well-balanced manner in the two steam generators.
[Brief description of the drawings]
FIG. 1 is a layout diagram showing a configuration of a decay heat removing device of a cooling system integrated type reactor using a reactor cooler according to an embodiment of the present invention.
FIG. 2 is a side sectional view of the reactor cooler according to the embodiment;
FIG. 3 is a front view of the reactor cooler according to the embodiment.
FIG. 4 is a plan view of the reactor cooler according to the embodiment.
FIG. 5 is a side view showing a structure of a conventional reactor cooler during water cooling.
FIG. 6 is a side view showing a structure of a conventional reactor cooler at the time of air cooling.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Cooler, 12 ... Primary cooling water, 13 ... Core, 14 ... Steam generator, 15 ... Secondary coolant, 21 ... Air inlet, 22 ... Air inflow passage (2nd vertical passage), 23 ... Air outlet, 24 ... Air outflow passage (first vertical passage), 25 ... Partition member, 25a ... Lower end of partition member, 26 ... Communication part, 28 ... Opening / closing door, 33a, 33b ... Heat transfer tube group, 34 ... Heat transfer tube, 36: thermal expansion absorbing part, 37: bottom surface, 38: tank water (cooling water).

Claims (8)

It is connected to a steam generator that cools the core of the nuclear reactor and exchanges heat with the primary coolant heated by the decay heat to evaporate the secondary coolant, thereby cooling and condensing the evaporated secondary coolant. In the reactor cooler to return to the steam generator and remove decay heat,
A partition member;
First and second vertical passages defined by the partition member and communicating with each other at a communication portion below the partition member;
A heat transfer tube group having a plurality of heat transfer tubes through which the secondary coolant flows,
This heat transfer tube group is characterized by being disposed obliquely from the vicinity of the bottom surface of the first vertical passage toward the lower end of the partition member so as to spatially block the first vertical passage in the communicating portion. Reactor cooler. 2. The reactor cooler according to claim 1, wherein the uppermost heat transfer tube of the heat transfer tube group is disposed near a lower end of the partition member, and the lowermost heat transfer tube is disposed near a bottom surface of the first vertical passage. . The cooler stores cooling water in the first and second vertical passages to a height substantially covering the heat transfer tubes of the heat transfer tube group,
When the evaporated secondary coolant is introduced into the heat transfer tubes of the heat transfer tube group, the secondary coolant is condensed by the cooling water in the first and second vertical passages, and the cooling water evaporates to lower the water level. 3. The reactor cooler according to claim 1, wherein the heat transfer tube exposed from the upper surface of the cooling water is cooled by an airflow flowing from the second vertical passage into the first vertical passage. 4. An air inlet for taking in air from the outside is provided in the second vertical passage,
The first vertical passage is provided with an air outlet for taking in air from the air inlet and passing through the heat transfer tube group to the outside,
The reactor cooler according to any one of claims 1 to 3, wherein the air outlet is located at a position higher than the air inlet. The reactor cooler according to claim 4, wherein an opening / closing door is provided at each of the air inlet and the air outlet. In the heat transfer tubes of the heat transfer tube group, the inlet side where the secondary coolant is introduced from the steam generator is provided above the outlet side where the secondary coolant cooled by the heat transfer tubes is discharged to the steam generator,
The reactor cooler according to any one of claims 1 to 5, wherein the heat transfer tubes are disposed to be inclined downward from the inlet side to the outlet side throughout. The reactor cooler according to claim 6, wherein a part of the heat transfer tube includes a thermal expansion absorbing part whose inclination is steeper than other parts. A plurality of heat transfer tube groups of the cooler are provided, and are divided into first and second heat transfer tube groups that can be connected to the two steam generators, respectively.
The reactor cooler according to any one of claims 1 to 7, wherein the first heat transfer tube group and the second heat transfer tube group are alternately arranged in a vertical direction and a horizontal direction, respectively.

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