JP2017058178A - Cooling system and nuclear power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling system which can intermittently supply a prescribed amount of cooling liquid into a reactor or a containment without requiring an external power or a special operation.SOLUTION: According to an embodiment, the cooling system includes: a tank 12 which can receive a cooling liquid generated by condensation of steam produced in a reactor or a containment and accumulates therein the cooling liquid; and a trap outflow tube 20 which causes the cooling liquid to flow out downward when the amount of the cooling liquid accumulated in the tank 12 reaches a prescribed amount. The trap outflow tube 20 includes: a first trap passage 21 which together with the tank 12, can accumulate the cooling liquid in the upstream side of a first dam 22; a second trap passage 26 which can accumulate the cooling liquid between a second dam 27 provided downstream of the first dam 22 and the first dam 22; and a downward extending passage 29 which extends downward in the downstream side of the second dam 27 and guides the cooling liquid into the nuclear reactor or the containment.SELECTED DRAWING: Figure 2

Description

  Embodiments of the present invention relate to a cooling system for supplying a cooling liquid into a nuclear reactor or a containment vessel.

  In a nuclear power plant or the like, a system for cooling a nuclear reactor or the like has been conventionally proposed without using external power or an external power source. For example, there is a so-called emergency core cooling system (ECCS) for cooling a nuclear reactor in order to prevent overheating of the core due to decay heat when an accident occurs in the nuclear reactor. The emergency core cooling system removes residual heat from the core by supplying a coolant to the core when normal reactor cooling becomes impossible, for example, in the event of a loss of primary coolant.

  In such a cooling system, it is required to operate and cool the nuclear reactor without supplying mechanical power or electric power from the outside. For example, in the reactor cooling system described in Patent Document 1 below, a steam turbine is driven by steam generated in a reactor pressure vessel, and a pump is operated by power obtained from the steam turbine. A technique has been proposed in which the coolant generated by condensing after driving the turbine is supplied again into the reactor pressure vessel.

JP 2012-255660 A

  By the way, in the system for supplying the coolant to the reactor without using external power, the steam generated in the reactor pressure vessel is condensed in the containment vessel, collected in the tank, and the cooling stored in the tank. A technique for supplying the liquid to the nuclear reactor by natural circulation using the density difference of the cooling liquid is being studied.

  However, if the coolant stored in the tank is simply supplied to the reactor pressure vessel or the like by the action of gravity, the flow rate and flow rate of the supplied coolant are small, and it is expected that it will be difficult to cool the entire core. Is done. In order to increase the flow rate and speed of the coolant, a predetermined amount of coolant is stored in a tank or the like and then the coolant is supplied to the reactor. A valve for controlling the supply of the coolant and means for operating the valve are required. In an emergency, it is difficult to open and close such a valve according to the amount of stored coolant.

  The embodiment of the present invention has been made in view of the above circumstances, and a predetermined amount of coolant is intermittently introduced into a nuclear reactor or a containment vessel without requiring external power or special operation. It aims at providing the cooling system which can be supplied.

  A cooling system according to an embodiment of the present invention includes a tank capable of receiving a coolant generated by condensation of steam generated in a nuclear reactor or a containment vessel storing the reactor, and storing the coolant. A trap outflow pipe for allowing the coolant stored in the tank to flow downward when the coolant reaches a predetermined amount, and the trap outflow pipe allows the coolant to flow with the tank upstream from the first weir. A first trap passage capable of storing, a second weir provided downstream from the first weir, a second trap passage capable of storing coolant between the first weir, a second weir A lower extension passage extending downward from the weir and guiding the coolant into the nuclear reactor or the containment vessel.

  Further, the nuclear power plant according to the embodiment of the present invention is produced by condensing a nuclear reactor that houses a reactor core, a containment vessel that houses the reactor, and steam generated in the reactor or the containment vessel. A tank that can receive the coolant and store the coolant, and a trap outlet pipe that flows downward when the coolant stored in the tank reaches a predetermined amount. The pipe includes a first trap passage capable of storing a coolant together with the tank upstream from the first weir, a second weir provided downstream from the first weir, and the first weir. A second trap passage capable of storing the cooling liquid therebetween, and a lower extending passage extending downward from the second weir and leading the cooling liquid into the reactor or the containment vessel. It is characterized by having.

  According to the embodiment of the present invention, a predetermined amount of coolant can be intermittently supplied into a nuclear reactor or a containment vessel without requiring external power or special operation.

It is a section elevation showing typically the cooling system of a 1st embodiment, and its peripheral composition. It is a section elevation showing typically the cooling system of a 1st embodiment. It is a figure explaining operation of the cooling system of a 1st embodiment, and is a section elevation showing the state where the liquid level of the cooling fluid of the 1st trap passage reached the 1st weir. It is a figure explaining operation | movement of the cooling system of 1st Embodiment, and has shown the state which the liquid level of the cooling fluid of the 2nd trap channel | path rose, and reached the 2nd weir, and the air siphon operates FIG. It is a figure explaining operation | movement of the cooling system of 1st Embodiment, the cooling fluid in a 1st trap channel | path and the cooling fluid in a 2nd trap channel | path are connected, and the cooling fluid in a tank passes an outflow pipe | tube. It is a section elevation showing the state which has flowed out. It is a section elevation showing typically the cooling system of a 2nd embodiment. It is sectional elevation which shows typically the cooling system of a 3rd embodiment, and its peripheral composition. It is a section elevation showing typically the cooling system of a 3rd embodiment. It is sectional elevation which shows typically the cooling system of 4th Embodiment, and its periphery structure. It is sectional elevation which shows typically the cooling system of a 5th embodiment, and its peripheral composition. It is a section elevation showing typically the cooling system of a 6th embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the embodiments described below, and various modifications can be made without departing from the scope of the invention.

[First Embodiment]
The cooling system of 1st Embodiment is demonstrated using FIGS. 1-5. FIG. 1 is a sectional elevation view schematically showing the cooling system of the present embodiment and its peripheral configuration. FIG. 2 is a sectional elevation view schematically showing the cooling system of the present embodiment.

  FIG. 3 is a diagram for explaining the operation of the cooling system of the present embodiment, and is a sectional elevation view showing a state in which the liquid level of the cooling liquid in the first trap passage reaches the first weir. FIG. 4 is a diagram for explaining the operation of the cooling system of the present embodiment, showing a state in which the liquid level of the cooling liquid in the second trap passage has risen to reach the second weir, and an air vent siphon It is a sectional elevation view which shows the state which acted. FIG. 5 is a diagram for explaining the operation of the cooling system of the present embodiment, in which the coolant in the first trap passage and the coolant in the second trap passage are connected, and the coolant in the tank passes through the outflow pipe. It is sectional elevation which shows the state which has flowed out through.

  In each figure, the upper side of the vertical direction is indicated as “vertical upper side” and indicated by arrow U, and the lower side is indicated as “vertical lower side” and indicated by arrow D. The direction orthogonal to the vertical direction is simply referred to as “horizontal direction”.

(Schematic configuration of cooling system)
The cooling system 10 of the present embodiment is provided in the nuclear power plant 1. The nuclear power plant 1 has a nuclear reactor 5 and a containment vessel 2 for storing the nuclear reactor 5. The nuclear reactor 5 accommodates a core (not shown) inside. The containment vessel 2 contains a nuclear reactor 5 including a reactor pressure vessel and related equipment. The related facilities include, for example, a main steam system pipe 7 and a main steam relief safety valve (hereinafter simply referred to as “safety valve”) 8 provided in the pipe 7. Note that the safety valve 8 is controlled to open when a pressure rise occurs in the main steam system including the inside of the nuclear reactor 5.

  In the nuclear reactor 5, the coolant is vaporized by receiving heat from the core and becomes steam. When the pressure of the main steam system including the inside of the nuclear reactor 5 rises and exceeds a predetermined value due to an accident or the like, the safety valve 8 is opened. The coolant vapor in the nuclear reactor 5 is released to the dry well 2 c in the containment vessel 2 through the pipe 7 and the safety valve 8. For example, the vapor discharged to the dry well 2c is cooled and condensed on the inner wall 2a that defines the inner space of the container. In this way, the vapor of the coolant generated in the nuclear reactor 5 is condensed in the containment vessel 2 and becomes a coolant (so-called condensed water) again.

  The cooling system 10 includes a tank 12 that can store a coolant generated by condensing steam generated in the containment vessel 2. In the present embodiment, the tank 12 is disposed in the storage container 2, and is configured such that a coolant generated by condensation in the storage container 2 flows in. More specifically, the tank 12 is provided in the containment vessel 2 in the vicinity of the inner wall 2a extending in the vertical direction, and is disposed on the outer side in the horizontal direction from the top 5a of the reactor pressure vessel. The tank 12 has an opening not shown in the vertical upper side. The coolant that condenses on the inner wall 2a and flows vertically downward flows into the tank 12 as indicated by an arrow F1 in the figure. In other words, the tank 12 of the present embodiment is supplied with a coolant that is discharged as steam from the nuclear reactor 5 and condensed in the containment vessel 2.

  In addition to the tank 12 described above, the cooling system 10 according to the present embodiment has a pipe (hereinafter referred to as “pipe”) that causes the coolant to flow downward vertically when the coolant stored in the tank 12 reaches a predetermined amount. 20) (denoted simply as "trap outflow pipe"). The trap outflow pipe 20 has a passage (hereinafter referred to as an internal passage) through which coolant can flow. The wall surface defining the internal passage in the trap outflow pipe 20 is hereinafter referred to as “inner wall”.

  The internal passage of the trap outflow pipe 20 alternately has portions 21 and 26 that are curved so that the vertical lower side is convex, and portions 23 and 28 that are curved so that the vertical upper side is convex. The trap outflow pipe 20 is configured as a so-called siphon, and has two passage portions (hereinafter referred to as “trap passages”) 21 and 26 capable of storing the coolant. The two trap passages 21, 26 are substantially U-shaped in the cross section (elevation surface) shown in FIG.

  Of the two trap passages 21, 26, the one on the upstream side, that is, the tank 12 side, is hereinafter referred to as “first trap passage 21”, and on the downstream side, that is, the reactor 5 side to which the coolant is supplied. Some will be referred to as “second trap passage 26” below. A coolant is stored in the first trap passage 21 and the second trap passage 26. The trap outflow pipe 20 is configured as a so-called double trap pipe.

  The first trap passage 21 is provided on the downstream side of the tank 12. The first trap passage 21 is connected to the bottom 12 a of the tank 12. The first trap passage 21 communicates with the inside of the tank 12 and is configured to be able to store a predetermined amount of coolant flowing into the tank 12 together with the tank 12 as indicated by an arrow F1 in the figure.

  The downstream side of the first trap passage 21 extends vertically upward. The inner wall that defines the downstream side of the first trap passage 21 is hereinafter referred to as a “first weir” and denoted by reference numeral 22. That is, the first trap passage 21 stores the coolant on the upstream side of the first weir 22. When the liquid level 31 rises vertically upward, the coolant stored in the first trap passage 21 passes through the first weir 22 and flows into the second trap passage 26.

  Of the internal passages of the trap outflow pipe 20, a passage provided between the first trap passage 21 and the second trap passage 26 and connecting the trap passages 21 and 26 will be described below as “first connection passage”. ”And the reference numeral 23 is attached.

  The second trap passage 26 is provided on the downstream side of the first weir 22 and communicates with the first trap passage 21 via the first connection passage 23. The second trap passage 26 is configured to receive the coolant flowing from the first trap passage 21 beyond the first weir 22 and store the coolant.

  The downstream side of the second trap passage 26 extends vertically upward. The inner wall provided downstream of the first weir 22 and demarcating the downstream side of the second trap passage 26 is hereinafter referred to as a “second weir” and denoted by reference numeral 27. That is, the second trap passage 26 stores the coolant upstream from the second weir 27, specifically, between the first weir 22 and the second weir 27. When the downstream liquid level 33 rises vertically upward, the coolant stored in the second trap passage 26 passes over the second weir 27 and flows into a lower extending passage 29 described later.

  The trap outflow pipe 20 is a passage (hereinafter referred to as a lower extending passage) 29 extending downstream from the second weir 27 so as to be positioned vertically downward toward the coolant supply target, that is, toward the reactor 5. have. The coolant that has passed through the first trap passage 21 and the second trap passage 26 and passed through the second weir 27 and into the lower extension passage 29 flows vertically downward through the lower extension passage 29 by the action of gravity. To the nuclear reactor 5.

  Of the internal passages of the trap outflow pipe 20, a passage connecting the second trap passage 26 and the lower extension passage 29 between the second trap passage 26 and the lower extension passage 29 will be described below. Reference numeral 28 denotes a “second connecting passage”.

  The internal passage of the trap outflow pipe 20 configured as described above communicates with the bottom 12a in which the coolant in the tank 12 is stored. When the tank 12 receives the cooling liquid (condensed water) as shown by the arrow F1, the cooling liquid is stored in the first trap passage 21 in addition to the inside of the tank 12.

  In the second trap passage 26, when the trap outflow pipe 20 was operated as a siphon last time, the second weir 27 could not be exceeded and the coolant that was not supplied to the reactor 5 remains. ing.

  As shown in FIGS. 2 to 4, the first connection passage 23 in the trap outflow pipe 20 has a coolant stored in the first trap passage 21 and a coolant stored in the second trap passage 26. Thus, a space 30 in which air is sandwiched (hereinafter referred to as a water sealed space) 30 is formed.

  As the amount of the coolant stored in the tank 12 increases, the liquid level 31 (see FIG. 2) of the coolant stored in the first trap passage 21 rises. As the liquid level 31 rises, the air in the water-sealed space 30 is compressed. That is, the volume of the water sealed space 30 decreases and the air pressure in the water sealed space 30 increases. The air in the water-sealed space 30 blocks the coolant in the first trap passage 21 and the coolant in the second trap passage 26, and thus prevents the trap outflow pipe 20 from functioning as a siphon.

(Configuration of siphon for air venting)
Therefore, the cooling system 10 of the present embodiment includes a siphon (hereinafter simply referred to as “air venting siphon”) 40 for extracting air from the water-sealed space 30. The air vent siphon 40 is configured as a so-called “auxiliary siphon” that assists the operation of the trap outflow pipe 20 that is also configured as a siphon, and will be described in detail below.

  As shown in FIG. 2, the air vent siphon 40 of the present embodiment is configured as a tube having three openings 41, 44, and 48. Specifically, the air siphon 40 includes an opening (hereinafter referred to as an air inlet) 41 for sucking air from the water-sealed space 30, and an opening (hereinafter simply referred to as an air outlet) for discharging the sucked air and the coolant. 48 (denoted as “discharge port”).

  In addition, the air vent siphon 40 includes an opening (hereinafter referred to as an intermediate port) 44 that is provided between the air suction port 41 and the discharge port 48 and into which the coolant in the second trap passage 26 flows. . The air inlet 41, the intermediate port 44, and the outlet 48 are in communication with each other. In the present embodiment, the air vent siphon 40 is provided in the internal passage of the trap outflow pipe 20.

  The air inlet 41 is disposed in the first connection passage 23, and more specifically, is disposed vertically above the first weir 22. That is, the air inlet 41 is disposed at a position facing the water seal space 30 when the water seal space 30 is formed in the first connection passage 23. In addition, it is preferable that the air inlet 41 is disposed as vertically as possible in the first connection passage 23.

  The intermediate port 44 is disposed in the second trap passage 26, and more specifically, is disposed vertically below the lowest portion 25 of the inner wall on the vertical upper side of the second trap passage 26. That is, the intermediate port 44 is disposed so as to face the coolant when the coolant is accumulated in the second trap passage 26.

  The junction 43 where the coolant from the intermediate port 44 and the air from the air inlet 41 merge is provided vertically above the intermediate port 44. As a result, the air that has flowed into the air vent siphon 40 from the air suction port 41 flows toward the discharge port 48 through the junction portion 43.

  The discharge port 48 is disposed in the lower extension passage 29, and more specifically, is disposed vertically below the intermediate port 44. When the coolant is filled between the discharge port 48 and the intermediate port 44 in the air vent siphon 40, a siphon action occurs in the coolant, and the coolant flowing in from the intermediate port 44 is further lowered. It is discharged from a certain outlet 48.

  At this time, air in the water-sealed space 30 is sucked from the air suction port 41. The air merges with the coolant from the intermediate port 44 at the junction 43 and is discharged into the lower extension passage 29 from the discharge port 48 together with the coolant.

(Cooling system operation)
Operation | movement of the cooling system of this embodiment demonstrated above is demonstrated using FIGS.

  As shown by arrows F1 in FIGS. 1 and 2, the cooling system 10 of the present embodiment is discharged as a vapor from the nuclear reactor 5 to the dry well 2c, and the cooling liquid ( Condensed water) is received in the tank 12. Coolant is stored in the tank 12 and in the first trap passage 21 of the trap outlet pipe 20 communicating with the tank 12.

  The second trap passage 26 stores the coolant that could not exceed the second weir 27 when the coolant was supplied to the nuclear reactor 5 last time. There is a water-sealed space 30 filled with air between the coolant stored in the second trap passage 26 and the coolant stored in the first trap passage 21.

  When the coolant is not so much stored in the tank 12 and the air pressure in the water-sealed space 30 is relatively low, as shown in FIG. 2, the liquid level 11 of the coolant stored in the tank 12 There is almost no difference in height between the coolant level 31 and the coolant level 31 downstream of the first trap passage 21. Similarly, there is almost no difference in height between the upstream liquid level 32 and the downstream liquid level 33 of the second trap passage 26.

  As the amount of the coolant stored in the tank 12 increases, the coolant level 31 on the downstream side of the first trap passage 21 rises. As the liquid level 31 rises, the air in the water seal space 30 is compressed. As shown in FIGS. 2 and 3, in response to the pressure of the air, in the second trap passage 26, the upstream liquid level 32 is lowered and the downstream liquid level 33 is raised.

  As shown in FIG. 3, when the coolant level 31 stored in the first trap passage 21 reaches slightly above the first weir 22 vertically, the coolant in the first trap passage 21 It flows into the second trap passage 26 beyond the one weir 22. Thereby, the amount of the coolant stored in the second trap passage 26 increases.

  As the coolant from the first trap passage 21 flows into the second trap passage 26, the liquid level 32 on the upstream side of the second trap passage 26 and the liquid level 33 on the downstream side both rise while maintaining a height difference. To do. At this time, the coolant in the air vent siphon 40 also rises to the same height as the liquid level 33 on the downstream side. As the liquid level 32 upstream of the second trap passage 26 rises, the air in the water-sealed space 30 is compressed and the pressure rises.

  As shown in FIG. 4, the liquid level 33 on the downstream side of the second trap passage 26 reaches slightly above the second weir 27, and the coolant in the second trap passage 26 passes through the second weir 27. When the refrigerant flows out into the lower extending passage 29, the cooling liquid in the air vent siphon 40 also flows out from the discharge port 48. At this time, the cooling liquid flows from the intermediate port 44 of the air vent siphon 40. That is, the flow of the coolant from the intermediate port 44 toward the discharge port 48 is generated by the siphon action. With this flow, air in the water-sealed space 30 is sucked from the air suction port 41. The air sucked from the air suction port 41 flows toward the discharge port 48 together with the coolant from the intermediate port 44 through the junction 43, and is discharged from the discharge port 48 to the lower extension passage 29.

  As the air in the water-sealed space 30 decreases, as shown in FIG. 5, the coolant in the first trap passage 21 and the coolant in the second trap passage 26 are connected, and a siphon action occurs in the coolant. The coolant flows downstream of the second extending passage 29 beyond the second weir 27. Thus, a predetermined amount of the coolant stored in the tank 12 is supplied into the reactor 5 through the trap outflow pipe 20.

  When a predetermined amount of coolant is supplied into the nuclear reactor 5, as shown in FIG. 2, the positions of the liquid surface 11 in the tank 12 and the liquid surface 31 of the first trap passage 21 are lowered, and the tank 12 Stops the coolant from flowing out.

  After that, as indicated by an arrow F1 in FIG. 2, the tank 12 is supplied with the coolant, so that the liquid surfaces 11 and 31 are raised, and the coolant stored in the tank 12 reaches a predetermined amount. Sometimes, again, the air vent siphon 40 and the trap outflow pipe 20 operate as siphons, and supply the coolant into the nuclear reactor 5.

(Summary)
As described above, the cooling system of the present embodiment is provided in the containment vessel 2 as shown in FIG. 1 and intermittently supplies a predetermined amount of coolant into the nuclear reactor 5. is there. The cooling system 10 is supplied as a coolant (condensed water) that is discharged from the nuclear reactor 5 as steam and condensed in the containment vessel 2, and stores the coolant in the tank 12. It has a trap outflow pipe 20 that guides the stored coolant into the reactor 5 that is a supply target.

  As shown in FIG. 2, the trap outlet pipe 20 is provided on the upstream side of the first weir 22 and on the downstream side of the first weir 22 and the first trap passage 21 capable of storing the coolant together with the tank 12. The second trap passage 26 capable of storing the coolant between the second weir 27 and the first weir 22, and in the downstream side of the second weir 27, vertically toward the coolant supply target. The lower extending passage 29 extends so as to be positioned on the lower side.

  As the amount of the coolant stored in the tank 12 increases, the liquid level 31 of the coolant stored in the first trap passage 21 rises. When the coolant in the first trap passage 21 flows into the second trap passage 26 beyond the first weir 22, the coolant level 33 on the downstream side of the second trap passage 26 rises.

  When the coolant in the second trap passage 26 passes through the second weir 27 and flows out into the lower extending passage 29, the coolant in the first trap passage 21 and the coolant in the second trap passage 26 are If it connects, the siphon effect | action will arise in the said cooling fluid. The coolant stored in the tank 12 can be supplied from the lower extension passage 29 into the reactor 5 (supply target).

  According to the present embodiment, a siphon action is generated in the coolant in the trap outflow pipe 20 without requiring external power or special operation, and a predetermined amount of coolant is intermittently supplied to the reactor 5. Alternatively, it can be supplied into the containment vessel 2. By supplying intermittently, it becomes possible to increase the flow rate and speed of the coolant supplied at a time, and to cool the reactor 5 and the like satisfactorily.

  Further, the cooling system of the present embodiment is a water-sealed space sandwiched between the coolant stored in the first trap passage 21 and the coolant stored in the second trap passage 26 in the trap outflow pipe 20. From 30, the air vent siphon 40 was designed to inhale air. The water seal space 30 can be eliminated, and the coolant in the first trap passage 21 and the coolant in the second trap passage 26 can be reliably connected to cause siphon action on the coolant.

  The air vent siphon 40 of the present embodiment is disposed vertically above the first weir 22 and is disposed in the air inlet 41 through which the air can be sucked from the water-sealed space 30 and the second trap passage 26. The intermediate port 44 through which the coolant stored in the second trap passage 26 can flow and the lower extended passage 29 are disposed vertically below the intermediate port 44, and the coolant from the intermediate port 44 And a discharge port 48 through which air from the air suction port 41 can be discharged.

  When the coolant in the second trap passage 26 exceeds the second weir 27 in the trap outflow pipe 20, the coolant flowing in from the intermediate port 44 is discharged from the discharge port 48 and sucked from the air suction port 41. The discharged air is discharged from the discharge port 48. According to this aspect, when the coolant in the second trap passage 26 exceeds the second weir 27, the trap outflow pipe 20 can be automatically operated as a siphon.

  In the present embodiment, the trap outflow pipe 20 is provided with the air siphon 40 (see FIG. 2). However, the cooling system according to the present invention is not limited to this mode. Absent. The trap outflow pipe 20 only needs to have the first trap passage 21 and the second trap passage 26 that can store the coolant and the lower extending passage 29. If the coolant in the first trap passage 21 and the coolant in the second trap passage 26 can be connected by the fluid pressure of the coolant stored in the tank 12, the siphon 40 for venting air is not provided. The trap outflow pipe 20 can be operated as a siphon.

  In the present embodiment, the tank 12 is provided in the storage container 2 as shown in FIG. 1 and is supplied with a cooling liquid (condensed water) generated by condensation in the storage container 2. The mode of supplying the coolant to the tank 12 is not limited to this. The coolant supplied to the tank 12 only needs to be discharged from the reactor 5 as steam, and an example thereof will be described below.

[Second Embodiment]
A cooling system according to a second embodiment will be described with reference to FIG. FIG. 6 is a sectional elevation view schematically showing the cooling system of the present embodiment. In addition, about the structure substantially common to 1st Embodiment, the code | symbol same or corresponding is attached | subjected and description is abbreviate | omitted.

  The cooling system 10B of the present embodiment has an emergency condenser 14 that condenses steam generated in the nuclear reactor 5 when the nuclear reactor 5 is isolated from a main condenser (not shown). . The emergency condenser 14 constitutes a reactor isolation cooling system (RCIC) and is generated in the reactor 5 when the reactor 5 is isolated from the main condenser (not shown). Steam is led. The cooling system 10 </ b> B has a pipe 13 (hereinafter referred to as a steam pipe) 13 that guides the steam generated in the nuclear reactor 5 to the emergency condenser 14. The steam pipe 13 extends vertically upward from the nuclear reactor 5 and is connected to the emergency condenser 14. The emergency condenser 14 receives the steam from the nuclear reactor 5 through the steam pipe 13 and condenses the steam as indicated by an arrow F3 in the figure.

  The emergency condenser 14 is disposed vertically above the tank 12 that stores the coolant. The cooling system 10 </ b> B has a pipe 15 (hereinafter referred to as “condensed water pipe”) 15 that guides the cooling liquid condensed in the emergency condenser 14 to the tank 12. The condensed water pipe 15 extends vertically downward from the emergency condenser 14 and is connected to the tank 12. The tank 12 receives the coolant from the emergency condenser 14 via the condensed water pipe 15 and stores the coolant.

  According to the present embodiment, the steam generated in the nuclear reactor 5 can be efficiently stored as a coolant in the emergency condenser 14 and stored in the tank 12. In the cooling system 10B, when the coolant stored in the tank 12 reaches a predetermined amount, the trap outflow pipe 20 operates as a siphon and supplies the coolant from the tank 12 into the nuclear reactor 5. The cooling system 10B can cool the nuclear reactor 5 without requiring external power or special operation.

[Third Embodiment]
A cooling system according to a third embodiment will be described with reference to FIGS. 7 and 8. FIG. 7 is a sectional elevation view schematically showing the cooling system of the present embodiment and its peripheral configuration. FIG. 8 is a sectional elevation view schematically showing the cooling system of the present embodiment. In addition, about the structure substantially common to 1st Embodiment, the code | symbol same or corresponding is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 7, the cooling system 10C of the present embodiment extends vertically downward from the bottom 12a of the tank 12, and the coolant stored in the tank 12 is removed from the reactor 5 by the action of gravity. A pipe 16 (hereinafter, referred to as a constant outflow pipe) is provided to flow out toward the bottom. As long as the coolant is stored in the bottom 12a in the tank 12, the outflow pipe 16 always causes the coolant in the bottom 12a to flow vertically downward.

  In the present embodiment, a pedestal wall 18 extending in the vertical direction is provided outside the nuclear reactor 5 in the horizontal direction. A lower portion 5 c of the pressure vessel of the nuclear reactor 5 is disposed inside the pedestal wall 18 in the horizontal direction. A space 19 (hereinafter referred to as a lower space) 19 that faces at least the lower portion 5c of the pressure vessel and can store the coolant is formed inside the pedestal wall 18 in the containment vessel 2. Yes.

  The always outflow pipe 16 extends through the pedestal wall 18 to the lower space 19. The coolant that has always flowed out of the outflow pipe 16 is stored in the lower space 19. When a predetermined amount of coolant is stored in the lower space 19, the lower portion 5c of the pressure vessel is submerged in the coolant.

  As shown in FIG. 8, cooling liquid generated by condensation as shown by an arrow F <b> 1 is supplied into the tank 12. A coolant is stored in the bottom 12 a of the tank 12. The constant outflow pipe 16 communicates with the inside of the tank 12. The coolant stored in the bottom portion 12a always flows out vertically downward through the outflow pipe 16 by the action of gravity.

  As a result, the coolant is stored in the lower space 19 of the nuclear reactor 5, and the lower portion 5c of the pressure vessel can be flooded. The flow rate of the coolant flowing out through the constant outflow pipe 16 is adjusted by changing the inner diameter of the constant outflow pipe 16 and the flow path cross-sectional area of the connecting portion with the tank 12.

  When the flow rate that always flows out through the outflow pipe 16 is smaller than the flow rate supplied into the tank 12, the liquid level 11 of the coolant in the tank 12 rises. When the amount of the coolant stored in the tank 12 reaches a predetermined amount, the trap outflow pipe 20 operates as a siphon and supplies most of the coolant in the tank 12 into the nuclear reactor 5. . Also in this embodiment, the reactor 5 can be cooled by the coolant supplied into the tank 12 without requiring external power or special operation.

[Fourth Embodiment]
A cooling system according to a fourth embodiment will be described with reference to FIG. FIG. 9 is a sectional elevation view schematically showing the cooling system of the present embodiment and its peripheral configuration. In addition, about the structure substantially common to 1st, 2nd and 3rd embodiment, the code | symbol same or corresponding is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 9, the cooling system 10E of the present embodiment includes a tank 12 and a trap outflow pipe 20E, as in the first embodiment. Furthermore, the cooling system 10 </ b> E is arranged vertically above the tank 12 to condense the steam generated in the nuclear reactor 5 and guide the steam generated in the nuclear reactor 5 to the emergency condenser 14. It has a steam pipe 13 and a condensate pipe 15 that guides the cooling liquid generated by condensation in the emergency condenser 14 to the tank 12. The tank 12 is supplied with a coolant generated by condensation from the emergency condenser 14 through the condensed water pipe 15.

  The trap outflow pipe 20 </ b> E of the present embodiment extends through the pedestal wall 18 to the lower space 19. The trap outflow pipe 20 </ b> E causes a predetermined amount of coolant stored in the tank 12 to intermittently flow out to the lower space 19. On the other hand, the always outflow pipe 16E of the present embodiment connects the tank 12 and the reactor 5, and always guides the coolant stored in the tank 12 into the reactor 5 by the action of gravity.

  In the present embodiment, when the amount of the coolant stored in the tank 12 reaches a predetermined amount, the trap outlet pipe 20E operates as a siphon, and most of the coolant in the tank 12 is It is supplied to a lower space 19 that is vertically below the furnace 5. According to this embodiment, the inside of the nuclear reactor 5 and the inside of the containment vessel 2 can be cooled without requiring external power or special operation. This embodiment is suitable for cooling the core melt when the core melt of the nuclear reactor 5 passes through the lower part 5c of the pressure vessel and falls into the lower space 19.

[Fifth Embodiment]
A cooling system according to a fifth embodiment will be described with reference to FIG. FIG. 10 is a sectional elevation view schematically showing the cooling system of the present embodiment and its peripheral configuration. In addition, about the structure substantially common with the 1st-4th embodiment, the code | symbol same or corresponding is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 10, in the present embodiment, the above-described emergency condenser 14 is arranged vertically above the tank 12 and outside the storage container 2. On the other hand, a pressure suppression chamber 17 for reducing the pressure in the storage container 2 at the time of an accident is formed in the storage container 2.

  The cooling system 10G of the present embodiment includes a steam pipe 13G that guides the steam discharged from the nuclear reactor 5 to the dry well 2c to the emergency condenser 14 and the cooling water condensed in the emergency condenser 14 to the tank 12. A condensate pipe 15 for guiding the water; The tank 12 is supplied with the condensed coolant from the emergency condenser 14 through the condensed water pipe 15 extending through the containment vessel 2.

  In the cooling system 10G of the present embodiment, the always outflow pipe 16G extends from the bottom 12a of the tank 12 to the pressure suppression chamber 17 vertically downward. The constant outflow pipe 16 </ b> G causes the coolant stored in the tank 12 to flow out to the pressure suppression chamber 17.

  On the other hand, the trap outflow pipe 20E extends through the pedestal wall 18 vertically downward from the tank 12. The trap outflow pipe 20 </ b> E causes a predetermined amount of coolant stored in the tank 12 to intermittently flow out into the lower space 19. It is possible to cool the nuclear reactor 5 also by this aspect.

[Sixth Embodiment]
The cooling system of 6th Embodiment is demonstrated using FIG. FIG. 11 is a sectional elevation view schematically showing the cooling system of the present embodiment. In addition, about the structure substantially common to 1st Embodiment, the code | symbol same or corresponding is attached | subjected and description is abbreviate | omitted.

  The cooling system of the present embodiment includes an injector 60 that receives the cooling liquid flowing out from the lower extension passage 29 of the trap outflow pipe 20 and guides the cooling liquid vertically downward. The injector 60 is configured such that its upstream end is positioned on the radially outer side of the downstream end 29 c of the lower extending passage 29.

  Further, the cooling system includes an injector outlet pipe 50 that guides the coolant stored in the tank 12 to the radially outer side of the downstream end portion 29 c of the lower extending passage 29 in the injector 60. The injector outlet pipe 50 is disposed vertically below the upper surface 12 e of the tank 12.

  In the cooling system configured as described above, when the trap outflow pipe 20 operates as a siphon and the outflow of the cooling liquid starts from the downstream end portion 29c, the injector 60 is brought into the injector outflow pipe 50 by the flow of the cooling liquid. Inhale and exhaust some air. When the injector outflow pipe 50 operates as a siphon, the cooling water in the tank 12 flows to the injector 60 through the injector outflow pipe 50. Thereby, the flow rate of the coolant flowing out of the tank 12 can be increased.

  Further, even when the trap outflow pipe 20 is not operated as a siphon due to breakage or blockage, the liquid level 11 of the coolant in the tank 12 is stored in the tank 12 by being positioned vertically above the injector outflow pipe 50. Due to the gravity of the cooling liquid, the injector outflow pipe 50 operates as a siphon, and the cooling liquid in the tank 12 can flow out to the injector 60. Thereby, the overflow of the tank 12 can be prevented.

[Other Embodiments]
In each embodiment mentioned above, the tank 12 shall be arrange | positioned in the storage container 2 as shown in FIG. 1, However, The tank which concerns on this invention is not limited to this aspect. The tank 12 may be any tank as long as it can receive a coolant generated by condensation of steam generated in the nuclear reactor, and is disposed outside the containment vessel 2 through a pipe extending outside the containment vessel 2. A coolant can also be supplied.

  Further, in each of the above-described embodiments, the coolant received by the tank 12 is discharged as steam from the reactor 5 as shown in FIG. 1, and the steam is condensed into the coolant in the containment vessel 2. However, the present invention is not limited to this embodiment. The steam may be generated outside the reactor 5 and inside the containment vessel 2.

  Although several embodiments of the present invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1 nuclear power plant, 2 containment vessel, 2a inner wall, 2c dry well, 5 reactor, 5a top, 5c lower part, 7 piping, 8 safety valve, 10, 10B, 10C, 10E, 10G cooling system, 11 liquid level, 12 tank, 12a bottom, 12e top surface, 13,13G steam piping, 14 emergency condenser, 15 condensate piping, 16, 16E, 16G constant outflow pipe, 17 pressure suppression chamber, 18 pedestal wall, 19 lower space, 20, 20E trap outflow pipe, 21 first trap passage (trap passage, internal passage, part), 22 first weir, 23 first connection passage (internal passage, part), 25 part, 26 second trap passage (trap) Passage, internal passage, part), 27 second weir, 28 second connection passage (internal passage, part), 29 lower extension passage (internal passage, part) 29c Downstream end, 30 Water-sealed space, 31, 32, 33 Liquid level, 40 Air vent siphon, 41 Air suction port (opening), 43 Junction portion, 44 Middle port (opening), 48 Outlet port (opening), 50 injector outlet pipe, 60 injector.

Claims (8)

A tank capable of receiving the coolant generated by condensation of steam generated in the nuclear reactor or the containment vessel storing the reactor, and storing the coolant;
A trap outflow pipe that causes the coolant stored in the tank to flow downward when a predetermined amount is reached;
With
The trap outflow pipe is
A first trap passage capable of storing a coolant together with the tank upstream of the first weir;
A second weir provided downstream of the first weir, and a second trap passage capable of storing the coolant between the first weir,
A lower extending passage extending downstream from the second weir and guiding the coolant into the reactor or the containment vessel;
A cooling system comprising: An air vent siphon for sucking air from a water-sealed space sandwiched between the coolant stored in the first trap passage and the coolant stored in the second trap passage in the trap outflow pipe;
The cooling system according to claim 1, further comprising: The air vent siphon is:
An air intake port disposed above the first weir, and capable of drawing air from the water-sealed space;
An intermediate port that is disposed in the second trap passage and into which the coolant stored in the second trap passage can flow;
A discharge port that is disposed below the intermediate port in the lower extending passage, discharges the coolant from the intermediate port, and discharges air from the air inlet;
The cooling system according to claim 2, wherein: The said tank is arrange | positioned in the said storage container, It is comprised so that the cooling fluid produced by condensing in the said storage container may flow in. The cooling system according to item. An emergency condenser disposed above the tank and condensing steam generated in the nuclear reactor,
The cooling system according to any one of claims 1 to 4, wherein the tank is supplied with a coolant generated by condensation from the emergency condenser. A continuous outflow pipe that extends downward from the bottom of the tank and allows the coolant stored in the tank to flow out into the containment vessel,
The cooling system according to any one of claims 1 to 5, further comprising: An injector that receives the coolant flowing out from the lower extending passage and guides the coolant downward;
An injector outlet pipe for guiding the coolant stored in the tank to the radially outer side of the lower extension passage of the injector;
The cooling system according to claim 1, further comprising: A reactor that houses the reactor core;
A containment vessel for storing the reactor,
Receiving a coolant produced by condensation of steam generated in the nuclear reactor or the containment vessel, and a tank capable of storing the coolant;
A trap outflow pipe that causes the coolant stored in the tank to flow downward when a predetermined amount is reached;
With
The trap outflow pipe is
A first trap passage capable of storing a coolant together with the tank upstream of the first weir;
A second weir provided downstream of the first weir, and a second trap passage capable of storing the coolant between the first weir,
A lower extending passage extending downstream from the second weir and guiding the coolant into the reactor or the containment vessel;
A nuclear power plant characterized by comprising:

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