JP2020139900A - Cooling device of suppression pool and cooling method of suppression pool - Google Patents

Abstract

To provide a cooling technology of a suppression pool capable of cooling water of the suppression pool in a severe accident.SOLUTION: The cooling device 11 of a suppression pool 5 comprises: an evaporation part 12 storing therein liquid working fluid 16 to be evaporated by absorbing heat from water in the suppression pool 5; a condensation part 13 condensing gaseous working fluid 15 stored therein by heat radiation; a steam passage 19 where the gaseous working fluid 15 rises from the evaporation part 12 to the condensation part 13; a condensate passage 20 where the liquid working fluid 16 drops by the gravity from the condensation part 13 to the evaporation part 12; and a gas/liquid separation part 31 in which a space above a liquid level 32 of the liquid working fluid 16 stored in the evaporation part 12 is separated into a part communicated with the steam passage 19 and a part communicated with the condensate passage 20.SELECTED DRAWING: Figure 4

Description

Embodiments of the present invention relate to a suppression pool cooling device and a suppression pool cooling method.

Generally, in a commercial boiling water reactor, it is stored as a facility to maintain the pressure or temperature of the reactor containment vessel below a predetermined value even in the event of a severe accident involving core meltdown due to loss of reactor coolant. A suppression chamber with a suppression pool that stores a large amount of water is provided in the container. Immediately after the accident, steam or water is released into the dry well of the reactor containment vessel due to the breakage of the pipe connected to the pressure vessel. The released steam or water, as well as the non-condensable gas present in the dry well, is released into the water of the suppression pool via the vent pipe. Then, the increase in the internal pressure of the reactor containment vessel is suppressed by condensing only the steam. After that, a residual heat removal system having a dynamic pump and a heat exchanger is provided in order to suppress an increase in the water temperature of the suppression pool due to steam or water continuously released into the suppression pool.

On the other hand, in the next-generation boiling water reactor, from the viewpoint of defense in depth, it is considered to provide a static containment cooling system as backup equipment under conditions where dynamic equipment does not function. For example, the steam released into the dry well at the time of an accident is condensed via a steam condensing heat exchanger in a cooling pool installed outside the reactor containment vessel, and the condensed water is dropped into the dry well again by gravity. There is something to make. Further, in order to recover the deterioration of heat removal performance due to the non-condensable gas gradually accumulated in the steam condensing heat exchanger, the degassing line is guided from the outlet side of the steam condensing heat exchanger to the suppression chamber. Furthermore, after the accident, when the water temperature of the suppression pool gradually rises due to steam or water released through the vent pipe or the automatic decompression system that directly depressurizes the reactor, the non-condensable gas stored in the suppression pool The heat removal performance of the containment vessel cooling system deteriorates due to the suction of non-condensable gas as well as the reflux to the dry well side. A blast release valve connected to the pressure vessel is provided to ensure the introduction of steam from the reactor with low non-condensable gas into the static containment cooling system. By operating this blast release valve, steam is directly supplied from the reactor to the containment cooling system and heat is removed, the rise in the water temperature of the suppression pool is suppressed, and the temperature is kept below the design temperature in the long term. In addition, a technique of attaching a heat pipe to the outer surface of the suppression chamber to cool it is known.

JP-A-2017-125774

In the event of a severe accident involving core meltdown, in addition to the hydrogen gas generated by the water-metal reaction generated from the meltdown core, some of the fission products escape and are released to the suppression chamber via the safety valve. In addition, the water in the suppression pool is heated by heat transfer from the dry well to the suppression chamber through a metal access tunnel in the reactor containment vessel of the type called ABWR (advanced boiling water reactor) of the boiling water reactor. Continue to be done. When the water in the suppression pool is heated to a predetermined temperature or higher due to the transfer of fission products to the suppression chamber and heat transfer from the access tunnel, the partial pressure of steam rises due to this rise in water temperature. Then, the non-condensable gas once accumulated in the suppression chamber returns to the drywell side via the vacuum break valve. When the amount of non-condensable gas in the dry well increases, the heat removal performance of the steam condensing heat exchanger deteriorates significantly, and eventually the function of the containment cooling system is lost.

This containment vessel cooling system is mainly provided as a severe accident countermeasure facility, and it is desired that static cooling can be performed for a long period of time in the event of a severe accident. In order to ensure the heat removal function of the containment cooling system, it is necessary to statically cool the suppression chamber below the specified temperature to prevent the non-condensable gas from returning to the dry well through the vacuum break valve after the accident. There is. In order to cool the suppression chamber, it is necessary to dissipate the heat of the suppression chamber to the outside through the wall of the reactor containment vessel. However, from the viewpoint of preventing the expansion of the boundary of the reactor containment vessel in the event of an accident, it is desirable not to take the fluid inside the reactor containment vessel out of the reactor containment vessel.

An embodiment of the present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a suppression pool cooling technique capable of cooling the water in the suppression pool in the event of a severe accident.

The suppression pool cooling device according to the embodiment of the present invention is provided inside the suppression pool, and has an evaporation unit that internally stores a working fluid of a liquid that absorbs heat from the water inside the suppression pool and evaporates. A condensing part that is provided at a position higher than the evaporating part outside the reactor storage container and condenses the working fluid of the gas stored inside by heat dissipation, and the evaporating part and the condensing part are connected to form a gas. A condensate that connects a steam flow path in which the working fluid rises from the evaporating part to the condensing part and the condensing part and the evaporating part, and the working fluid of the liquid drops from the condensing part to the evaporating part by gravity. A gas-liquid separation section that separates the path and the space above the liquid level of the working fluid of the liquid stored in the evaporation section into a portion communicating with the steam flow path and a portion communicating with the condensing liquid passage. ,

An embodiment of the present invention provides a suppression pool cooling technique capable of cooling the suppression pool water in the event of a severe accident.

The cross-sectional view which shows the reactor building of 1st Embodiment. Top view showing the reactor building. The plan view which shows the evaporation part of a cooling device. FIG. 3 is a sectional view taken along line IV-IV showing an evaporation portion. The plan view which shows the condensing part of a cooling device. An enlarged plan view showing the funnel portion of the condensing portion. FIG. 6 is a cross-sectional view taken along the line VII-VII showing the condensed portion. FIG. 6 is a sectional view taken along line VIII-VIII of FIG. 6 showing a condensed portion. Sectional drawing which shows the heat transport piping. The cross-sectional view which shows the heat transport pipe of the modification 1. The cross-sectional view which shows the heat transport pipe of the modification 2. The cross-sectional view which shows the heat transport pipe of the modification 3. The enlarged plan view which shows the funnel part of the condensed part of the modification 3. The cross-sectional view which shows the evaporation part of the modification 4. The cross-sectional view which shows the evaporation part of the modification 5. A flowchart showing how to cool the suppression pool. The cross-sectional view which shows the reactor building of 2nd Embodiment. The cross-sectional view which shows the reactor building of 3rd Embodiment.

(First Embodiment)
Hereinafter, the present embodiment will be described with reference to the accompanying drawings. First, the cooling device and the cooling method of the suppression pool of the first embodiment will be described with reference to FIGS. 1 to 16.

Reference numeral 1 in FIG. 1 is the reactor building 1 of the first embodiment. The reactor building 1 includes a reactor 2, a pressure vessel 3 for accommodating the reactor 2, a reactor containment vessel 4 for accommodating the pressure vessel 3, and a suppression pool 5.

The pressure vessel 3 is a container for the nuclear reactor 2 (core), and is a stainless steel structure that allows cooling water and the like to flow between the inside and the outside while withstanding the high temperature and high pressure inside. Further, the pressure vessel 3 also has a function of blocking the radioactive substances and radiation generated in the reactor 2 from the outside so as not to leak.

FIG. 1 illustrates the reactor building 1 of the advanced boiling water reactor (ABWR). The reactor building 1 is a reinforced concrete building, and a reactor containment vessel 4 is formed inside the reactor building 1 by using a part of the reinforced concrete of the skeleton of the reactor building 1. A steel liner 6 (lining) is provided on the inner surface of the reactor containment vessel 4.

The reactor containment vessel 4 is a structure for forming a barrier against the emission of radioactive materials as well as serving as a pressure barrier in the event of a severe accident involving core meltdown caused by a reactor coolant loss accident or the like. Further, important equipment such as piping connected to the pressure vessel 3 is provided inside the reactor containment vessel 4. Further, a reinforced concrete bioshield wall 7 and other structures surrounding the pressure vessel 3 are provided. A lid 8 that is opened when nuclear fuel is taken in and out is provided on the upper part of the reactor containment vessel 4.

Further, inside the reactor containment vessel 4, a suppression pool 5 is provided in which a large amount of water for reducing the pressure inside the reactor containment vessel is stored in an emergency. The lower section in which the suppression pool 5 is provided is also called a wet well or a suppression chamber (pressure suppression chamber). The upper section of the reactor containment vessel 4 is called a dry well.

The suppression pool 5 is provided with a steam outlet 9 of a vent pipe (shown in the figure so that the path of the vent pipe can be seen) for guiding the steam released from the pressure vessel 3 in an emergency. For example, when an accident such as a pipe break occurs, the pipe penetrating the reactor containment vessel 4 is automatically separated by the isolation valve. Then, the steam released from the pressure vessel 3 is guided through the vent pipe and blown out from the steam outlet 9 into the water stored in the suppression pool 5, and is condensed by this water. In this way, the suppression pool 5 has a function of suppressing an increase in the internal pressure of the reactor containment vessel 4 by cooling the steam when the pressure rises due to the leakage of steam inside the reactor containment vessel 4. Have.

The lower part of the reactor building 1 is provided underground. The suppression pool 5 is provided at the lowest position of the reactor building 1. That is, the suppression pool 5 is provided at a position lower than the ground 10.

As shown in FIG. 1, the reactor building 1 is provided with the cooling device 11 of the suppression pool 5 of the first embodiment. The cooling device 11 is a device for suppressing an increase in the temperature of water in the suppression pool 5 in an emergency. The cooling device 11 of the present embodiment includes an evaporation unit 12, a condensing unit 13, and a heat transport pipe 14 connecting them. That is, the cooling device 11 is a heat pipe that transfers the heat of the water in the suppression pool 5 to the outside.

The cooling device 11 cools the water in the suppression pool 5 by utilizing the thermosiphon phenomenon. The thermosiphon phenomenon is a convection phenomenon that occurs based on the principle that the heated fluid becomes lighter and rises, and the cold fluid becomes heavier and falls. Thermosiphons are also called thermal convection.

The cooling device 11 transports the working fluid 15 of the gas evaporated by the evaporation unit 12 (see FIG. 4) to the condensing unit 13 through the heat transport pipe 14, and the working fluid 16 of the liquid condensed by the condensing unit 13 is transferred. It returns to the evaporation unit 12 again through the heat transport pipe 14. The cooling device 11 is a closed system, and a thermosiphon phenomenon occurs in which the flows of the working fluids 15 and 16 form a loop. That is, a cycle of evaporation of the working fluid 15 (absorption of latent heat) and condensation of the working fluid 16 (release of latent heat) occurs to transfer heat. As the working fluids 15 and 16 of the present embodiment, fluids such as CFC substitutes having high volatility are used.

As shown in FIGS. 4 and 9, the heat transport pipe 14 is a double pipe composed of an outer pipe 17 and an inner pipe 18. The heat transport pipe 14 extends from the evaporation section 12 to the condensing section 13 to the steam flow path 19 in which the working fluid 15 (steam) of the gas rises from the evaporation section to the condensing section 13, and extends from the condensing section 13 to the evaporating section 12. A condensate passage 20 is formed in which the working fluid 16 (condensate) of the liquid falls from the condensing portion 13 to the evaporating portion 12 by gravity.

In the present embodiment, the vapor flow path 19 is formed between the inner surface of the outer pipe 17 and the outer surface of the inner pipe 18, and the condensate passage 20 is formed inside the inner pipe 18. In this way, both the steam flow path 19 and the condensate passage 20 can be piped with one double pipe.

In the heat transport pipe 14 as the double pipe of the first embodiment, the inner pipe 18 is provided at the center position of the outer pipe 17 in the cross-sectional view thereof. That is, the central axis of the outer tube 17 and the central axis of the inner tube 18 coincide with each other. In particular, although not shown, a support member for supporting the inner pipe 18 is provided inside the outer pipe 17.

As shown in FIG. 1, the evaporation unit 12 is provided inside the suppression pool 5. That is, the evaporation unit 12 is provided in a state where it can directly contact the water stored in the suppression pool 5. For example, the evaporation unit 12 is fixed at a position where it is submerged in water in the suppression pool 5. The evaporation unit 12 stores the liquid working fluid 16 inside. The working fluid 16 of this liquid absorbs heat from the water in the suppression pool 5 and evaporates.

The cooling device 11 of the present embodiment includes an emergency cooling water tank 21 as a water storage unit provided inside the reactor building 1. The condensing portion 13 is provided inside the emergency cooling water tank 21. That is, the condensing portion 13 is provided in a state where it can directly contact the water stored in the emergency cooling water tank 21. For example, the condensing portion 13 is fixed at a position where the emergency cooling water tank 21 is submerged in water. The condensing unit 13 stores the working fluid 15 of the gas inside. The working fluid 15 of this gas is condensed by the water in the emergency cooling water tank 21, that is, by radiating heat to the outside.

The condensing unit 13 is provided at a position higher than the evaporation unit 12. Further, in the first embodiment, the working fluid 15 of the gas is condensed by the water in the emergency cooling water tank 21, but other cooling fluids may be used as the cooling medium. The cooling fluid may be a liquid or a gas.

The emergency cooling water tank 21 stores cooling water used in an emergency. The emergency cooling water tank 21 is provided at a position higher than the suppression pool 5. Further, the emergency cooling water tank 21 is provided with an exhaust pipe 22 for releasing the steam generated inside the tank 21 to the outside of the reactor building 1. Further, a water supply system 23 for supplying water to the emergency cooling water tank 21 from the outside is provided.

In this embodiment, the emergency cooling water tank 21 is illustrated as the water storage unit, but other embodiments may be used. The emergency cooling water tank 21 may be an emergency condensate storage tank or a cooling water tank (pool) of the steam condensing heat exchanger. In this way, a water storage unit such as emergency cooling water can be used as a cooling means for the condensing unit 13.

A plurality of cooling devices 11 are provided in the reactor building 1. Each cooling device 11 is provided with an evaporation unit 12 and a condensation unit 13. Each of these cooling devices 11 operates independently.

As shown in FIG. 2, the reactor containment vessel 4 has a circular shape in a plan view. The suppression pool 5 inside thereof has a donut shape (O-shape) in a plan view. When a plurality of cooling devices 11 are provided, the evaporating portions 12 are arranged at equal intervals in the circumferential direction of the suppression pool 5. By arranging the respective evaporation units 12 apart from each other, even if vibration occurs in the predetermined evaporation unit 12, it is not necessary to exert the influence on the other evaporation units 12.

Further, the evaporation portion 12 is fixed to the wall portion 24 of the reactor containment vessel 4. That is, the evaporation portion 12 is fixed to the wall portion (inner surface) of the suppression pool 5. In this way, the evaporation unit 12 can be prevented from interfering with the structure inside the reactor containment vessel 4 or the suppression pool 5 (pressure suppression chamber).

As shown in FIGS. 3 and 4, the evaporation unit 12 is provided at a position lower than the water surface 25 of the suppression pool 5. Further, the evaporation unit 12 includes a box-shaped box portion 26 for storing the liquid working fluid 16 inside, and a plurality of endothermic fins 27 protruding from one side surface of the box portion 26.

The box portion 26 includes a top plate 28 on the ceiling side, a bottom plate 29 on the floor side, and side plates 30 surrounding the four side surfaces. One of the side plates 30 is fixed to the wall portion 24 of the reactor containment vessel 4. Since the liner 6 is attached to the inner surface of the wall portion 24, the box portion 26 is fixed via the liner 6.

Further, the endothermic fins 27 have a fin-like shape or a flat plate shape, and are projected in the same direction with each other. In this way, the heat transfer area can be increased by forming the structure in which the endothermic fins 27 are connected. These heat absorbing fins 27 are provided on the side plate 30 arranged on the side opposite to the side plate 30 fixed to the wall portion 24. A cavity is formed inside each of the heat absorbing fins 27, and is communicated with the internal space of the heat absorbing fins 27 and the internal space of the box portion 26. The outer surface of these endothermic fins 27 comes into contact with the water in the suppression pool 5. In this way, the liquid working fluid 16 inside the evaporation unit 12 can efficiently absorb heat from the water in the suppression pool 5.

A gas-liquid separation plate 31 as a gas-liquid separation unit is provided inside the evaporation unit 12. The gas-liquid separation plate 31 is fixed to the upper surface plate 28 constituting the box portion 26 and extends downward from the upper surface plate 28. The lower end of the gas-liquid separation plate 31 is not in contact with the bottom plate 29 of the box portion 26, and the liquid working fluid 16 can flow between the lower end of the gas-liquid separation plate 31 and the bottom plate 29. There is a gap.

The liquid level 32 of the working fluid 16 of the liquid stored inside the evaporation unit 12 is preset. As the liquid level 32 to be set, the liquid level 32 when the cooling device 11 is operating is set. The gas-liquid separation plate 31 is formed so that its lower end is lower than the liquid level 32 of the liquid working fluid 16.

The gas-liquid separation plate 31 divides the internal space of the box portion 26 at the center. Here, the space around the gas-liquid separation plate 31 where the heat absorbing fins 27 are provided is the first compartment 33, and the space fixed to the wall portion 24 of the reactor containment vessel 4 is the second compartment 34. And.

The outer pipe 17 and the inner pipe 18 of the heat transport pipe 14 are connected to the central portion of the upper surface plate 28 of the box portion 26 of the evaporation portion 12 in the longitudinal direction. The heat transport pipe 14, which is a double pipe, is branched into an outer pipe 17 and an inner pipe 18 inside the reactor containment vessel 4. Then, each end is connected to the box portion 26. Here, the outer pipe 17 forming the vapor flow path 19 is connected to the first section 33 of the box portion 26, and the inner pipe 18 forming the condensate passage 20 is connected to the second section 34 of the box portion 26. To. That is, inside the evaporation unit 12, the gas-liquid separation plate 31 as the gas-liquid separation unit has the first section 33 that communicates the space above the liquid level 32 of the working fluid 16 with the vapor flow path 19, and the condensed liquid. It is separated into a second section 34 that communicates with the road 20.

The liquid working fluid 16 stored in the first section 33 of the evaporation unit 12 absorbs heat from the water in the suppression pool 5 by the endothermic fins 27 and evaporates. Then, the working fluid 15 which has become a gas flows into the outer pipe 17 and rises to the condensing portion 13.

The working fluid 16 of the liquid condensed in the condensing unit 13 flows down from the inner pipe 18 to the second section 34 of the evaporation unit 12. Then, the working fluid 16 of this liquid moves to the first section 33 through the gap between the lower end of the gas-liquid separation plate 31 and the bottom plate 29, and is evaporated again. In this way, the gas-liquid separation plate 31 causes a loop-type thermosiphon phenomenon in which the flow of the working fluid 15 of the gas and the flow of the working fluid 16 of the liquid are separated.

In this way, fluids such as air and gas in the internal space of the reactor containment vessel 4 are not taken out to the outside of the reactor containment vessel 4, and only heat is transferred from the water of the suppression pool 5 to the outside of the reactor containment vessel 4. It is possible to take it out statically.

In particular, the water in the suppression pool 5 becomes hot during a severe accident. Therefore, the working fluid 16 of the liquid inside the evaporation unit 12 that has received the thermal energy from the hot water may boil. In the present embodiment, the temperature of the second compartment 34 to which the condensate passage 20 is connected is lower than that of the first compartment 33 because it is in contact with the wall portion 24 of the reactor containment vessel 4. Therefore, it is possible to prevent the temperature of the working fluid 16 of the liquid returning from the condensate passage 20 from being raised. Therefore, it is possible to prevent the working fluid 16 of the boiling liquid from flowing back through the condensate passage 20.

The heat transport pipe 14, which is a double pipe, is provided so as to penetrate the wall portion 24 forming the reactor containment vessel 4 in which the suppression pool 5 is provided. In this way, only one through hole 35 is provided in the wall portion 24 forming the reactor containment vessel 4. In the present embodiment, since the four cooling devices 11 are provided, it is only necessary to provide the four through holes 35 in the wall portion 24 of the reactor containment vessel 4. In this way, since the size of the through holes 35 and the number of through holes 35 can be minimized, the strength of the reactor containment vessel 4 can be maintained in the event of a severe accident.

As shown in FIG. 1, the condensing portion 13 is provided at a position lower than the water surface of the emergency cooling water tank 21. When the amount of water in the emergency cooling water tank 21 becomes low, water is appropriately supplied from the water supply system 23.

As shown in FIGS. 5 and 8, the condensing portion 13 includes a box-shaped box portion 36 that is stored inside the working fluid 15 of the gas, and a plurality of heat radiating fins 37 that protrude from the two side surfaces of the box portion 36. And. The box portion 36 includes a top plate 38 on the ceiling side, a bottom plate 39 on the floor side, and a side plate 40 surrounding the four side surfaces. The condensing portion 13 is fixed to the bottom portion of the emergency cooling water tank 21 via a support leg 41 extending downward from the bottom plate 39.

Further, the heat radiation fins 37 are in the shape of fins or flat plates, and are projected in the same direction from each other. In this way, the heat transfer area can be increased by forming the structure in which the heat radiation fins 37 are connected. A cavity is formed inside each of the heat radiating fins 37, and is communicated with the internal space of the heat radiating fins 37 and the internal space of the box portion 36. The outer surface of these heat radiation fins 37 comes into contact with the water in the emergency cooling water tank 21. That is, the outer surface of the heat radiation fin 37 comes into contact with the cooling medium outside the reactor containment vessel 4. In this way, the working fluid 15 of the gas inside the condensing portion 13 can efficiently dissipate heat.

As shown in FIG. 7, the bottom surface 42 of the heat radiation fin 37 is inclined so as to be lowered toward the box portion 36. The working fluid 15 of the gas that has reached the condensing portion 13 is condensed inside the heat radiating fin 37. At this time, the thermal energy of the gaseous working fluid 15 is transferred to the water in the emergency cooling water tank 21. Then, the liquid working fluid 16 adhering to the inner surface of the heat radiation fin 37 drips onto the bottom surface 42 and flows toward the box portion 36 due to its inclination.

As shown in FIGS. 5 and 8, the outer pipe 17 and the inner pipe 18 of the heat transport pipe 14 are connected to the central portion of the bottom plate 39 of the box portion 36 of the condensing portion 13 in the longitudinal direction. The heat transport pipe 14, which is a double pipe, is branched into an outer pipe 17 and an inner pipe 18 inside the condensing portion 13.

As shown in FIGS. 6 and 8, the heat transport pipe 14 includes a funnel portion 43 provided in the condensing portion 13 and extending like a funnel around the inner pipe 18 in a plan view. The funnel portion 43 is provided at the central portion of the bottom plate 39 in the longitudinal direction. The bottom plate 39 of the box portion 36 is inclined so that the central portion is lowered. The working fluid 16 of the liquid that has flowed into the box portion 36 flows toward the funnel portion 43 due to the inclination of the bottom plate 39. Then, the funnel portion 43 collects the liquid working fluid 16 in the inner pipe 18 (condensate liquid passage 20).

In this embodiment, two funnel portions 43 are formed at the upper end of the inner tube 18. Each funnel portion 43 branches upward from the inner tube 18 and extends. The funnel portion 43 is connected to the bottom plate 39 of the box portion 36, and the condensed working fluid 16 flowing down the bottom plate 39 flows into the funnel portion 43. That is, the liquid working fluid 16 is guided by the downwardly inclined surface formed by the bottom plate 39 and the funnel portion 43 and gathers in the inner pipe 18.

As shown in FIGS. 7 and 8, the heat transport pipe 14 projects upward from the bottom plate 39 inside the condensing portion 13. Further, the heat transport pipe 14 includes an introduction port 44. The introduction port 44 is provided at a position higher than the funnel portion 43. That is, the introduction port 44 allows the working fluid 15 of the gas flowing through the steam flow path 19 formed between the outer pipe 17 and the inner pipe 18 to enter the inside of the condensing portion 13 from a position higher than the funnel portion 43. Introduce.

In the heat transport pipe 14, the upper end of the inner pipe 18 is connected to the funnel portion 43, and the upper side of the funnel portion 43 is composed of only the outer pipe 17. That is, the outer pipe 17 (steam flow path 19) is separated from the condensate passage 20 formed by the funnel portion 43 while intersecting with the funnel portion 43. An introduction port 44 is provided at the upper end of the outer pipe 17. In this way, the flow of the gas working fluid 15 and the flow of the liquid working fluid 16 are less likely to be mixed, and the flow of the gas working fluid 15 and the flow of the liquid working fluid 16 are separated even in the condensing portion 13. Can be done.

As shown in FIG. 6, in the heat transport pipe 14, the inner pipe 18 is provided at the center position of the outer pipe 17. Therefore, the funnel portion 43 has a shape that narrows toward the center position of the outer pipe 17. Further, the funnel portion 43 has a high portion connected to the bottom plate 39 and is inclined so as to be lowered toward the center position of the outer pipe 17. The liquid working fluid 16 guided and collected by the funnel portion 43 is bound to each other by its surface tension. Therefore, the flow of the working fluid 16 of the liquid can be promoted toward the inner pipe 18.

Next, the cooling method of the suppression pool 5 executed by the cooling device 11 will be described with reference to the flowchart of FIG. The action passively generated by the operation of the cooling device 11 will be described.

As shown in FIG. 16, first, in step S11, the working fluid 16 of the liquid stored in the evaporation unit 12 provided inside the suppression pool 5 absorbs heat from the water in the suppression pool 5 and evaporates. ..

In the next step S12, the working fluid 15 of the gas rises from the evaporation section 12 to the condensation section 13 in the steam flow path 19 formed by the heat transport pipe 14 and extending from the evaporation section 12 to the condensation section 13.

In the next step S13, the working fluid 15 of the gas stored inside the condensing portion 13 provided in the emergency cooling water tank 21 outside the reactor containment vessel 4 is cooled by the water in the emergency cooling water tank 21. To. Then, the working fluid 15 of the gas is condensed by heat dissipation.

In the next step S14, the working fluid 16 of the liquid falls from the condensing section 13 to the evaporating section 12 by gravity through the condensate passage 20 formed by the heat transport pipe 14 and extending from the condensing section 13 to the evaporating section 12.

In the next step S15, the gas-liquid separation plate 31 separates the flow of the working fluid 15 of the gas from the flow of the working fluid 16 of the liquid, and a loop-type thermosiphon phenomenon occurs.

In the event of a severe accident, steps S11 to S15 are continuously repeated, so that the water in the suppression pool 5 can be efficiently cooled. Further, since a power source such as a pump for transporting the working fluids 15 and 16 is not required and no control is required, static cooling can be performed for a long period of time in the event of a severe accident.

Further, as a conventional technique, there is a heat pipe that transfers heat using a working fluid. A high temperature portion and a low temperature portion are provided at one end and the other end of the heat pipe. The working fluid evaporated in the high temperature part is condensed in the low temperature part to become a liquid working fluid. Then, the working fluid of the liquid returns to the high temperature portion via the wick forming the capillary structure. In such a heat pipe, the working fluid of the liquid is transported through the wick, so that the transport efficiency is lowered. However, in the present embodiment, since the liquid working fluid 16 is dropped by gravity, the transportation efficiency is improved.

In the present embodiment, the capillary limit and the scattering limit generated in the heat pipe can be removed by separating the flow of the working fluid 15 of the gas and the flow of the working fluid 16 of the liquid without using a wick. And a large amount of energy can be transported in a small space. Further, unlike a normal thermosiphon, the space for the heat transport pipe 14 for transporting the working fluids 15 and 16 is sufficient for one, so the number of through holes 35 provided in the wall portion 24 of the reactor containment vessel 4 is minimized. Can be limited to.

Next, a modified example will be described. FIG. 10 is a cross-sectional view showing the heat transport pipe 14A of the modified example 1. The heat transport pipe 14A of the first modification is a double pipe in which the inner pipe 18 is provided at the center position of the outer pipe 17. The heat transport pipe 14A of the first modification 1 includes a heat insulating material 45 that covers the outer surface of the inner pipe 18. The heat insulating material 45 completely covers the surface of the inner pipe 18 inside the outer pipe 17.

In this way, heat exchange between the working fluid 15 of the gas and the working fluid 16 of the liquid can be suppressed. Therefore, heat is transferred from the working fluid 15 of the gas flowing inside the inner pipe 18 to the working fluid 16 of the liquid flowing between the inner surface of the outer pipe 17 and the outer surface of the inner pipe 18, and the working fluid of this gas. It is possible to prevent the 15 from being condensed. Then, by reducing the pressure loss, the heat transport amount can be improved, and the water in the suppression pool 5 can be efficiently cooled.

The heat insulating material 45 may be any material that can inhibit heat conduction between the working fluid 15 of the gas and the working fluid 16 of the liquid. For example, glass fiber or ceramic may be used to form the heat insulating material 45. Further, the heat insulating material 45 may be coated on the outer surface of the inner pipe 18.

FIG. 11 is a cross-sectional view showing the heat transport pipe 14B of the modified example 2. The heat transport pipe 14B of the second modification 2 is a triple pipe composed of an outer pipe 17, an inner pipe 18, and a protective pipe 46. The protective tube 46 completely covers the surface of the inner tube 18 inside the outer tube 17. In this way, heat exchange between the working fluid 15 of the gas and the working fluid 16 of the liquid can be suppressed. Further, the strength of the heat transport pipe 14B can be improved.

Further, a vacuum is formed between the outer surface of the inner tube 18 and the inner surface of the protective tube 46. In this way, a vacuum layer is formed between the outer pipe 17 and the inner pipe 18, so that the heat insulating property can be improved. A gas such as air, nitrogen, or argon may be sealed between the outer surface of the inner tube 18 and the inner surface of the protective tube 46.

FIG. 12 is a cross-sectional view showing the heat transport pipe 14C of the modified example 3. The heat transport pipe 14C of the third modification is a double pipe in which the inner pipe 18 is provided at a position displaced from the center of the outer pipe 17. The outer surface of the inner pipe 18 is provided in contact with the inner surface of the outer pipe 17. The inner pipe 18 is fixed to the outer pipe 17 without a support member. For example, the inner pipe 18 may be attached to the inner surface of the outer pipe 17 by welding. In the heat transport pipe 14C of the third modification, it is not necessary to provide a support member for supporting the inner pipe 18 inside the outer pipe 17, so that the structure of the heat transport pipe 14C can be simplified.

FIG. 13 is an enlarged plan view showing funnel portions 43A and 43B of the condensing portion 13 of the modified example 3. In the third modification, since the inner pipe 18 is provided at a position displaced from the center of the outer pipe 17, the funnel portions 43A and 43B have a shape that narrows toward the position displaced from the center of the outer pipe 17. There is. In this modification 3, of the two funnel portions 43A and 43B, the length of one funnel portion 43A is longer than that of the other funnel portion 43B. Therefore, the velocities of the working fluids 16 of the liquid flowing from the funnel portions 43A and 43B are different from each other. Since the faster flow controls the slower flow, turbulence is less likely to occur, and the flow of the working fluid 16 of the liquid can be promoted toward the inner pipe 18.

FIG. 14 is a cross-sectional view showing the evaporation portion 12 of the modified example 4. The heat transport pipe 14D, which is the double pipe of the modified example 4, is branched into an outer pipe 17 and an inner pipe 18 outside the reactor containment vessel 4. That is, the wall portion 24 of the reactor containment vessel 4 is provided with a first through hole 35A through which the outer pipe 17 is inserted and a second through hole 35B through which the inner pipe 18 is inserted.

Valves 47 and 48 are provided in the outer pipe 17 and the inner pipe 18 of the portion branched outside the reactor containment vessel 4, respectively. By closing the first valve 47 corresponding to the outer pipe 17 and the second valve 48 corresponding to the inner pipe 18, the heat transport pipe 14D can be closed. As described above, when the outer pipe 17 and the inner pipe 18 are branched inside the reactor containment vessel 4 (see FIG. 4), the outer pipe 17 and the inner pipe inside the reactor containment vessel 4 are formed. Valves 47 and 48 may be provided in 18, respectively.

FIG. 15 is a cross-sectional view showing the evaporation portion 12 of the modified example 5. The heat transport pipe 14E, which is the double pipe of the modified example 5, includes an outer pipe 17 and an inner pipe 18. The outer pipe 17 is fixed to the upper surface plate 28 of the box portion 26 of the evaporation portion 12. In this modification 5, the inner pipe 18 is provided over the entire outer pipe 17. That is, the inner pipe 18 extends to the end of the outer pipe 17 without branching from the outer pipe 17.

The inner pipe 18 extends downward from the lower end of the outer pipe 17. The inner pipe 18 is formed so that the lower end thereof is lower than the liquid level 32 of the working fluid 16 of the liquid stored inside the evaporation unit 12. Further, the lower end of the inner pipe 18 is not in contact with the bottom plate 29 of the box portion 26, and a gap through which the liquid working fluid 16 can flow is provided between the lower end of the inner pipe 18 and the bottom plate 29. Has been done.

The protrusion dimension L from the lower end of the outer pipe 17 to the lower end of the inner pipe 18 is preset according to the position of the liquid level 32 of the working fluid 16 of the liquid. The protruding portion L of the inner pipe 18 is the gas-liquid separation portion of the modified example 5. That is, due to the portion L of the inner pipe 18, in the internal space of the box portion 26 of the evaporation portion 12, the space above the liquid level 32 of the liquid working fluid 16 communicates with the vapor flow path 19 and the condensed liquid passage. It is separated into a part that communicates with 20. In the space above the liquid level 32 of the working fluid 16 of the liquid, a portion other than the inside of the inner pipe 18 may be a first compartment, and a portion inside the inner pipe 18 may be a second compartment.

In the modified example 5, it is only necessary to fix the outer tube 17 through the upper surface plate 28 of the box portion 26 of the evaporation portion 12 in a state of penetrating the outer tube 17, and separately form a hole in the upper surface plate 28 for penetrating the inner tube 18. Since it is not necessary, the structure of the evaporation unit 12 can be simplified and its strength can be improved. Further, since it is not necessary to form the inner pipe 18 to branch from the outer pipe 17, the shape of the heat transport pipe 14E can be simplified and its strength can be improved.

Further, the configuration applied in any one modification may be applied to another modification, or the configuration applied in each modification may be combined.

(Second Embodiment)
Next, the cooling device 11A and the cooling method of the suppression pool of the second embodiment will be described with reference to FIG. The same components as those shown in the above-described embodiment are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 17, in the second embodiment, the reactor building 1 is provided on the coast close to the ocean 49. The suppression pool 5 is provided at a position lower than the sea level 50. The position of the sea surface 50 at low tide is set. The condensing portion 13 is provided in the sea. In this way, almost inexhaustible seawater can be used as a cooling means for the condensing unit 13. Further, since the temperature difference between the evaporation unit 12 and the condensation unit 13 can be increased, the cooling efficiency of the water in the suppression pool 5 can be improved.

(Third Embodiment)
Next, the cooling device 11B and the cooling method of the suppression pool of the third embodiment will be described with reference to FIG. The same components as those shown in the above-described embodiment are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 18, in the third embodiment, the condensing portion 13 is provided on the roof of the reactor building 1. That is, the condensing portion 13 is provided at a position where it can come into contact with the atmosphere 51 outside the reactor building 1. In this way, the atmosphere 51 outside the reactor building 1 can be used as a cooling means for the condensing unit 13. The almost inexhaustible atmosphere 51 can be used as a cooling means for the condensing unit 13.

Further, each of the condensing portions 13 is provided with a cooling tower 52 that guides the flow of the atmosphere 51. The cooling tower 52 is a tubular member that surrounds the condensing portion 13. A gap is provided in the lower part of the cooling tower 52, and the atmosphere 51 flows into the inside through the gap. Then, the atmosphere 51 warmed by heat exchange with the condensing portion 13 inside the cooling tower 52 is blown out from the upper part of the cooling tower 52. In this way, the atmosphere 51 can be efficiently applied to the condensing portion 13 for cooling.

Although the suppression pool cooling device according to the present embodiment has been described based on the first to third embodiments, the configuration applied in any one embodiment may be applied to other embodiments. , The configurations applied in each embodiment may be combined.

Although the flowchart of the present embodiment illustrates a mode in which each step is executed in series, the context of each step is not necessarily fixed, and even if the context of some steps is exchanged. good. Also, some steps may be executed in parallel with other steps.

In this embodiment, an improved boiling water reactor (ABWR) in which the reactor containment vessel 4 and the suppression chamber are integrally provided is illustrated, but other embodiments may be used. For example, the present embodiment may be applied to a boiling water reactor (BWR) in which the reactor containment vessel 4 and the suppression chamber (torus chamber) are separately provided. That is, the heat transport pipe, which is a double pipe, may be provided so as to penetrate the wall portion forming the suppression chamber.

In the present embodiment, the vapor flow path 19 is formed between the inner surface of the outer pipe 17 and the outer surface of the inner pipe 18, and the condensate passage 20 is formed inside the inner pipe 18. It may be the aspect of. For example, the condensate passage 20 may be formed between the inner surface of the outer pipe 17 and the outer surface of the inner pipe 18, and the vapor flow path 19 may be formed inside the inner pipe 18.

In the present embodiment, the evaporation units 12 of the plurality of cooling devices 11 are arranged at equal intervals in the circumferential direction of the suppression pool 5, but other embodiments may be used. For example, a plurality of evaporation units 12 may be arranged together at one location in the circumferential direction of the suppression pool 5.

According to the embodiment described above, gas-liquid separation separates the space above the liquid level of the working fluid of the liquid stored in the evaporation part into a portion communicating with the vapor flow path and a portion communicating with the condensate liquid passage. By providing the part, the water in the suppression pool can be cooled in the event of a severe accident.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention as well as the invention described in the claims and the equivalent scope thereof.

1 ... Reactor building, 2 ... Reactor, 3 ... Pressure vessel, 4 ... Reactor storage vessel, 5 ... Suppression pool, 6 ... Liner, 7 ... Bioshield wall, 8 ... Lid, 9 ... Steam outlet, 10 ... ground, 11 ... cooling device, 12 ... evaporative part, 13 ... condensing part, 14 (14A, 14B, 14C, 14D, 14E) ... heat transport pipe, 15 ... gaseous working fluid, 16 ... liquid working fluid, 17 ... outer pipe, 18 ... inner pipe, 19 ... steam flow path, 20 ... condensate passage, 21 ... emergency cooling water tank, 22 ... exhaust pipe, 23 ... water supply system, 24 ... wall, 25 ... water surface, 26 ... Box, 27 ... heat absorbing fins, 28 ... top plate, 29 ... bottom plate, 30 ... side plate, 31 ... gas-liquid separation plate, 32 ... liquid level, 33 ... first compartment, 34 ... second compartment, 35 (35A) , 35B) ... through hole, 36 ... box part, 37 ... heat dissipation fin, 38 ... top plate, 39 ... bottom plate, 40 ... side plate, 41 ... support leg, 42 ... bottom surface, 43 (43A, 43B) ... funnel part , 44 ... inlet, 45 ... insulation, 46 ... protective pipe, 47, 48 ... valve, 49 ... ocean, 50 ... sea surface, 51 ... atmosphere, 52 ... cooling tower.

Claims (16)

An evaporative unit provided inside the suppression pool and internally storing a working fluid of a liquid that absorbs heat from the water inside the suppression pool and evaporates.
A condensing section that is provided at a position higher than the evaporation section outside the reactor containment vessel and in which the working fluid of the gas stored inside condenses by heat dissipation.
A steam flow path that connects the evaporation section and the condensation section and allows the working fluid of gas to rise from the evaporation section to the condensation section.
A condensate passage that connects the condensing portion and the evaporating portion, and the working fluid of the liquid drops from the condensing portion to the evaporating portion by gravity.
A gas-liquid separation section that separates the space above the liquid level of the working fluid of the liquid stored in the evaporation section into a portion that communicates with the vapor flow path and a portion that communicates with the condensate passage.
To prepare
Suppression pool cooling system. The evaporation section is provided on the inner surface of the suppression pool.
The cooling device for the suppression pool according to claim 1. The evaporation unit comprises endothermic fins that come into contact with the water in the suppression pool.
The suppression pool cooling device according to claim 1 or 2. The condensing unit includes heat radiation fins that come into contact with a cooling medium outside the reactor containment vessel.
The suppression pool cooling device according to any one of claims 1 to 3. Equipped with a double pipe consisting of an outer pipe and an inner pipe
One of the vapor flow path and the condensate passage is formed between the inner surface of the outer pipe and the outer surface of the inner pipe, and the other of the vapor flow path and the condensate passage is inside the inner pipe. It is formed,
The suppression pool cooling device according to any one of claims 1 to 4. A funnel portion provided in the condensing portion, which spreads in a funnel shape around the inner pipe and collects the working fluid of the liquid in the condensate passage.
The steam flow paths are separated from each other while intersecting the funnel portion, and the working fluid of the gas flowing from the steam flow path is introduced into the condensing portion from a position higher than the funnel portion. Introductory port and
To prepare
The cooling device for the suppression pool according to claim 5. The double pipe is provided so as to penetrate the wall portion forming the reactor containment vessel or suppression chamber in which the suppression pool is provided.
The suppression pool cooling device according to claim 5 or 6. A heat insulating material covering the outer surface of the inner pipe is provided.
The suppression pool cooling device according to any one of claims 5 to 7. A protective tube covering the outer surface of the inner tube is provided.
The suppression pool cooling device according to any one of claims 5 to 8. There is a vacuum between the outer surface of the inner tube and the inner surface of the protective tube.
The cooling device for the suppression pool according to claim 9. The condensing part is provided inside a water storage part inside the reactor building.
The suppression pool cooling device according to any one of claims 1 to 10. The condensing portion is provided in the sea.
The suppression pool cooling device according to any one of claims 1 to 10. The condensing portion is provided at a position where it can come into contact with the atmosphere outside the reactor building.
The suppression pool cooling device according to any one of claims 1 to 10. The condensing portion is provided with a cooling tower that guides the flow of the atmosphere.
The cooling device for a suppression pool according to claim 13. A cooling device as a heat pipe that cools the suppression pool.
An evaporating part that stores the working fluid of the liquid that absorbs heat from the water inside the suppression pool and evaporates inside.
A condensing section connected to the evaporating section, provided at a position higher than the evaporating section outside the reactor containment vessel, and condensing the working fluid of the gas stored inside by heat dissipation.
In the space above the liquid level of the working fluid of the liquid stored in the evaporating part, the portion where the working fluid of gas rises toward the condensing part and the working fluid of liquid descending from the condensing part. A gas-liquid separation part that separates into parts,
To prepare
Suppression pool cooling system. A step in which the working fluid of the liquid stored in the evaporating part provided inside the suppression pool absorbs heat from the water inside the suppression pool and evaporates.
A step in which the working fluid of the gas stored in the condensing portion provided at a position higher than the evaporating portion outside the reactor containment vessel is condensed by heat dissipation.
A step in which the working fluid of gas rises from the evaporation part to the condensation part in a steam flow path connecting the evaporation part and the condensation part.
A step in which the working fluid of a liquid descends from the condensing portion to the evaporating portion by gravity in a condensate passage connecting the condensing portion and the evaporating portion.
A step of separating the space of the liquid stored in the evaporation section above the liquid level of the working fluid into a portion communicating with the vapor flow path and a portion communicating with the condensate passage.
including,
How to cool the suppression pool.

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