Nuclear containment vessel cooling system

Abstract

To efficiently cool a nuclear containment.SOLUTION: A reactor containment cooling system comprises a wall part and a flow path formation member. The wall part at least partially covers a reactor containment so as to form a pool part for storing a coolant between itself and the upper part of the reactor containment. The flow path formation member extends along a convex upper surface provided at the upper part to form a flow path between itself and the upper surface through which the coolant stored in the pool part can pass. The flow path has a first communication part communicating with the pool part, and a second communication part communicating with the pool part above the first communication part.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a nuclear containment vessel cooling system. [Background technology]

[0002] If the reactor containment vessel that houses the nuclear reactor becomes hot due to an accident or malfunction, for example, the fluid (such as water) inside will expand, causing the internal pressure to rise and, in some cases, causing damage such as rupture. To prevent such damage, conventional reactor containment vessels are equipped with cooling equipment in advance, which can cool the reactor containment vessel as needed and prevent damage.

[0003] However, because conventional cooling equipment installed in a reactor containment vessel operates using power supplied from an external source, if the supply of power from the outside is stopped, for example, as in the case of a station breakout (SBO), the reactor containment vessel becomes unable to be cooled. To avoid such a situation, for example, Patent Documents 1 to 3 disclose techniques for ensuring the cooling performance of the reactor containment vessel even when the cooling equipment requiring external power is unable to operate, by securing a space for storing cooling water in the upper part of the reactor containment vessel and cooling the upper side of the reactor containment vessel using the cooling water stored in that space. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-236572 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-198168 [Patent Document 3] Special Publication No. 2015-508486 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above Patent Documents 1 to 3, the reactor containment vessel is cooled using cooling water stored in the upper part of the reactor containment vessel. In an SBO situation, it is expected that the amount of cooling water available may be limited, so the performance to efficiently cool the reactor containment vessel with the limited cooling water is required.

[0006] At least one embodiment of the present disclosure has been made in consideration of the above circumstances, and has an object to provide a containment vessel cooling device that can efficiently cool a containment vessel. [Means for solving the problem]

[0007] In order to solve the above problems, a reactor containment vessel cooling device according to at least one embodiment of the present disclosure includes: a wall portion at least partially covering the containment vessel so as to form a pool portion for storing coolant between the wall portion and an upper portion of the containment vessel; a flow path forming member that extends along a convex upper surface provided on the upper portion, thereby forming a flow path between the upper surface and the flow path forming member, through which the coolant stored in the pool portion can pass; Equipped with The flow path has a first communication portion that communicates with the pool portion, and a second communication portion that communicates with the pool portion above the first communication portion. [Effects of the Invention]

[0008] At least one embodiment of the present disclosure has been made in consideration of the above circumstances, and can provide a containment vessel cooling device that can efficiently cool a containment vessel. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a nuclear power plant according to an embodiment; [Figure 2] FIG. 2 is a schematic diagram showing the configuration of a cooling device provided in the reactor containment vessel of FIG. [Figure 3] 3 is a view showing the flow path forming member of FIG. 2 alone from above. FIG. [Figure 4] 4 is a perspective view showing the flow path forming member of FIG. 3 from an obliquely upper side. FIG. [Figure 5] This is a first modification of FIG. [Figure 6] This is a second modification of FIG. [Figure 7] 3 is an example of a horizontal cross-sectional view of the wall portion of FIG. 2. [Figure 8] 3 is another example of a horizontal cross-sectional view of the wall portion of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments will be described with reference to the accompanying drawings. However, the configurations described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the invention.

[0011] First, the overall configuration of a nuclear power plant equipped with a containment vessel cooling system according to at least one embodiment of the present disclosure will be described. Fig. 1 is a schematic configuration diagram of a nuclear power plant 1 according to one embodiment.

[0012] The nuclear plant 1 includes a nuclear reactor 2 for generating steam using thermal energy generated by a nuclear fission reaction, a steam turbine 4 driven by the steam generated in the nuclear reactor 2, and a generator 6 driven by the rotation of a rotary shaft of the steam turbine 4. The nuclear reactor 2 shown in FIG. 1 is a pressurized water reactor (PWR). In other embodiments, the nuclear reactor 2 may be a boiling water reactor (BWR), or may be a type of nuclear reactor that uses a substance other than light water as a moderator or coolant, unlike light water reactors including pressurized water reactors and boiling water reactors.

[0013] The reactor 2 includes a primary cooling loop 10 through which primary cooling water (primary coolant) flows, and a reactor vessel (pressure vessel) 11, a pressurizer 14, a steam generator 16, and a primary coolant pump 18, which are provided in the primary cooling loop 10. The primary coolant pump 18 is configured to circulate the primary coolant in the primary cooling loop 10. The pressurizer 14 is configured to pressurize the primary coolant in the primary cooling loop 10 so that the primary coolant does not boil. The reactor pressure vessel 11, the pressurizer 14, the steam generator 16, and the primary coolant pump 18, which constitute the reactor 2, are housed in a reactor containment vessel 19.

[0014] The reactor pressure vessel 11 contains fuel rods 12 containing pellet-shaped nuclear fuel (e.g., uranium fuel, MOX fuel, etc.), and the thermal energy generated by the nuclear fission reaction of this fuel heats the primary coolant inside the reactor pressure vessel 11. The reactor pressure vessel 11 is provided with control rods 13 for absorbing and adjusting the number of neutrons generated in the core containing the nuclear fuel in order to control the reactor power. The primary coolant heated inside the reactor pressure vessel 11 is sent to a steam generator 16, where it heats the secondary coolant (secondary coolant) flowing through a secondary cooling loop 20 by heat exchange, generating steam.

[0015] The steam generated in the steam generator 16 is sent to the steam turbine 4, which includes a high-pressure turbine 21 and a low-pressure turbine 22, to rotate and drive the steam turbine 4. The steam turbine 4 is also connected to a generator 6 via a rotating shaft, and the generator 6 is driven by the rotation of the rotating shaft to generate electrical energy. A moisture separator heater 23 is provided between the high-pressure turbine 21 and the low-pressure turbine 22, so that the steam that has done work in the high-pressure turbine 21 is reheated before being sent to the low-pressure turbine 22.

[0016] The secondary cooling loop 20 is provided with a condenser 24, a low-pressure feedwater heater 26, a deaerator 27, and a high-pressure feedwater heater 29, and the steam that has done work in the low-pressure turbine 22 is condensed and heated as it passes through these devices, and then returns to the steam generator 16. The secondary cooling loop 20 is also provided with a condensate pump 25 and a feedwater pump 28, and these pumps circulate secondary cooling water in the secondary cooling loop 20. In addition, cooling water (e.g., seawater) for cooling the steam from the low-pressure turbine 22 by heat exchange is supplied to the condenser 24 via a pump 15.

[0017] Next, we will explain the containment vessel cooling system (hereinafter referred to as "cooling system") provided in the above-mentioned containment vessel 19. Fig. 2 is a schematic diagram showing the configuration of the cooling system 30 provided in the containment vessel 19 of Fig. 1. Note that Fig. 2 shows a simplified internal configuration of the above-mentioned containment vessel 19.

[0018] The reactor containment vessel 19 has a closed structure that houses reactor internals 32, including the reactor pressure vessel 11, pressurizer 14, steam generator 16, and primary coolant pump 18. The reactor containment vessel 19 is configured by combining an upper surface 36 and a lower surface 38 with a substantially cylindrical main body 34. The upper surface 36 is convex upward, and in this embodiment, is configured to have slopes 42 on both sides, with a central portion 40 corresponding to the central axis of the main body 34 as an apex. While FIG. 2 illustrates a case in which the slopes 42 are flat, they may also be curved.

[0019] The cooling system 30 has a wall 44 that at least partially covers the containment vessel 19. In this embodiment, the wall 44 is part of the building that houses the containment vessel 19, and surrounds the containment vessel 19 entirely.

[0020] The wall portion 44 forms a pool portion 50 for storing coolant 48 between itself and the upper surface 36 of the reactor containment vessel 19. The upper surface 36 can be identified as a relatively upper portion of the reactor containment vessel 19, but may also be identified as a portion above the position where the secondary cooling loop 20 (see FIG. 1 ) is taken out from the reactor containment vessel 19, for example.

[0021] In this embodiment, a partition 49 is provided in the reactor containment vessel 19, extending substantially horizontally from the boundary between the main body 34 and the upper surface 36 to the wall 44, and a pool 50 is configured as a space defined by the partition 49 and the wall 44 above the partition 49. A coolant 48 can be introduced into the pool 50 from the outside via a coolant supply unit (not shown). The coolant 48 is, for example, cooling water, and is introduced into the pool 50 from a cooling water reservoir (not shown) provided outside via a predetermined supply line.

[0022] Since the reactor containment vessel 19 is generally made of a heat-conductive material, the upper surface 36 exposed to the pool section 50 is cooled by the coolant 48 introduced into the pool section 50. The amount of coolant 48 introduced into the pool section 50 may be any amount, but for example, as shown in FIG. 2, the coolant 48 may be introduced up to above the central portion 40 of the upper surface 36 (the highest point of the convex upper surface 36).

[0023] The cooling device 30 also has a flow path forming member 56 that, between itself and the upper surface 36, forms a flow path 55 through which the coolant 48 stored in the pool portion 50 can pass. The flow path forming member 56 extends along the upper surface 36 and has a first communication portion 57 and a second communication portion 58. The second communication portion 58 communicates with the pool portion 50 above the first communication portion 57. In this embodiment, the first communication portion 57 is configured to communicate with the bottom portion of the flow path 55, and the second communication portion 58 is configured to communicate with the top portion (central portion 40) of the flow path 55. The first communicating portion 57 and the second communicating portion 58 may each be provided midway through the flow path 55 (that is, between the bottom and top).

[0024] 3 is a diagram showing the flow path forming member 56 of Fig. 2 alone from above, and Fig. 4 is a perspective view showing the flow path forming member 56 of Fig. 3 from an obliquely upward direction. When the containment vessel 19 is viewed from above, the first communication part 57 is provided at a position farther from the central part 40 than the second communication part 58, and particularly in this embodiment, the multiple flow paths 55 are provided so as to extend radially from the central part 40.

[0025] In the flow path 55 configured in this manner, when the coolant 48 stored in the pool section 50 is heated by the upper surface 36 of the containment vessel 19, a portion of the coolant 48 is introduced through the first communication section 57 and sent out through the second communication section 58 to the pool section 50. That is, at the upper surface 36, the coolant 48 in the flow path 55 is heated by decay heat from the containment vessel 19, causing the heated coolant 48 to move upward along the flow path 55 and be sent out through the second communication section 58 to the pool section 50. In the pool section 50, the relatively high-temperature coolant 48 sent out through the second communication section 58 is guided to the surface side, causing the relatively low-temperature coolant 48 to move downward and be introduced into the flow path 55 through the first communication section 57. In this manner, forming the flow path 55 using the flow path forming member 56 generates natural convection in the coolant 48 in the pool section 50, promoting circulation and thereby effectively cooling the containment vessel 19.

[0026] The coolant 48 stored in the pool section 50 gradually rises in temperature due to decay heat from the reactor containment vessel 19, and when the temperature is below the boiling point, a cooling action utilizing sensible heat is obtained by generating natural convection as described above. On the other hand, when the temperature of the coolant 48 rises and exceeds the boiling point, a cooling action utilizing the latent heat of the coolant 48 is obtained, and since the coolant 48 becomes a gas-liquid mixture, a cooling action is obtained by boiling cooling by maintaining the temperature of the coolant 48 at its boiling point. In this way, the cooling device 30 configured as described above improves the cooling effect of the coolant 48, thereby obtaining a good cooling action.

[0027] Fig. 5 shows a first modified example of Fig. 2. In the first modified example, fins 60 are provided on the pool portion 50. The fins 60 are made of a material with excellent thermal conductivity, such as metal, and promote heat exchange between the coolant 48 and the wall portion 44, thereby improving the cooling performance of the cooling device 30.

[0028] When the reactor containment vessel 19 is viewed from above, the fins 60 are provided so as to extend along the wall portion with the center portion 40 of the reactor containment vessel 19 as the reference. This reduces the resistance of the fins 60 to the flow of the coolant 48 that undergoes natural convection in the pool portion 50, as described above. As a result, the fins 60 do not impede the flow of the coolant 48, and effectively improve the cooling performance of the cooling device 30.

[0029] 5, such fins 60 may be configured such that the length L1 in the vertical direction is greater than the length L2 in the horizontal direction. When the fins 60 are formed in a vertically elongated shape in this way, they may be installed on the wall 44 so that the longitudinal direction is the vertical direction. Because a flow of the coolant 48 is likely to occur in the pool 50 near the wall 44 in the vertical direction, providing the vertically elongated fins 60 along this flow can promote heat exchange between the fins 60 and the coolant 48 and effectively improve cooling performance.

[0030] The fins 60 may also be arranged so that at least a portion thereof is in contact with the coolant 48 stored in the pool portion 50. In Fig. 5, the fins 60 are arranged so that the entire fins 60 are in contact with (immersed in) the coolant 48 stored in the pool portion 50. This promotes heat exchange between the fins 60 and the coolant 48, and provides good cooling performance.

[0031] FIG. 6 shows a second modified example of FIG. 2. In the second modified example, fins 70 having the same shape as the fins 60 of the first modified example described above are installed on the wall portion 44. The fins 70 are arranged so that at least a portion thereof is exposed above the coolant 48 stored in the pool portion 50. In FIG. 6, the fins 70 are arranged so that the entire fins 70 are exposed above the coolant 48. In the pool portion 50, high-temperature gas resulting from evaporation of the coolant 48 exists in the space above the stored coolant 48. Therefore, by installing the fins 70 in such a position, it is possible to promote the cooling and condensation of this gas. This condenses the high-temperature gas and returns it to the coolant 48, thereby further improving cooling performance.

[0032] 7 is an example of a horizontal cross-sectional view of the wall portion 44 of FIG. 2. In this example, the wall portion 44, which is in contact with the coolant 48 stored in the pool portion 50 on the inside, has a hollow structure, thereby providing a cavity 72. The cavity 72 is configured as a closed space inside the wall portion 44, and a working fluid 74 is sealed therein. The working fluid 74 may include a material having a higher thermal conductivity than the coolant 48, or may include a material having a higher thermal conductivity than the constituent material of the wall portion 44. This improves the thermal conductivity of the wall portion 44, thereby efficiently transferring decay heat generated in the reactor containment vessel 19 inside the wall portion 44 to the outside, thereby improving cooling performance.

[0033] The working fluid 74 sealed in the cavity 72 may also contain a material that undergoes a phase change, such as vanadium dioxide, which is expected to provide a more effective cooling effect by utilizing the latent heat generated when the working fluid 74 undergoes a phase change.

[0034] 8 is another example of a horizontal cross-sectional view of the wall 44 of FIG. 2. In this example, a cavity 72 is provided in the wall 44 as in the example shown in FIG. 7, but ribs 76 are provided on the inner wall of this cavity 72. The ribs 76 are erected inward from the inner wall of the cavity 72 and have the function of increasing the contact area with the working fluid 74 sealed in the cavity 72 and promoting heat transfer. This allows decay heat generated in the reactor containment vessel 19 inside the wall 44 to be efficiently transferred to the outside, thereby improving cooling performance.

[0035] Furthermore, the provision of hollow portion 72 in wall portion 44 may reduce the strength of wall portion 44 to some extent, but providing ribs 76 in this manner can effectively prevent this reduction in strength. In Figure 8, the provision of multiple ribs 76 connecting two different points on the inner wall of hollow portion 72 effectively improves the strength of such upper surface 36.

[0036] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described embodiments may be combined as appropriate.

[0037] The contents described in each of the above embodiments can be understood, for example, as follows.

[0038] (1) A reactor containment vessel cooling device according to one aspect includes: a wall portion (44) at least partially covering the reactor containment vessel (19) so as to form a pool portion (50) for storing coolant (48) between the wall portion (44) and an upper portion of the reactor containment vessel (19); a flow path forming member (56) extending along a convex upper surface (36) provided on the upper portion, thereby forming a flow path (55) between the upper surface and the flow path forming member (56) through which the coolant stored in the pool portion can pass; Equipped with The flow path has a first communication part (57) communicating with the pool part, and a second communication part (58) communicating with the pool part above the first communication part.

[0039] According to the above aspect (1), at least a portion of the reactor containment vessel is covered with a wall portion, thereby forming a pool portion for storing coolant between the top of the reactor containment vessel and the wall portion. Furthermore, a flow path forming member is provided on the convex upper surface of the reactor containment vessel, thereby forming a flow path through which the coolant stored in the pool portion can pass. As a result, the coolant stored in the pool portion and in the flow path is heated primarily by the high-temperature reactor containment vessel, and the coolant in the flow path whose temperature has increased is guided to the pool portion from the second communication portion located above. Accordingly, the coolant in the pool portion, which has a relatively low temperature, is guided to the flow path from the first communication portion located below. As a result, the coolant stored in the pool portion circulates by natural convection while passing through the flow path, efficiently cooling the reactor containment vessel.

[0040] (2) In another embodiment, in the above embodiment (1), the upper surface is an inclined surface having an apex at the central portion (49) of the reactor containment vessel, The first communication portion is provided at a position farther from the central portion than the second communication portion when the containment vessel is viewed from above.

[0041] According to the above aspect (2), the upper surface of the containment vessel has a slope that slopes toward the center, and a flow path is formed along the slope. As a result, the coolant introduced from the pool section to the flow path via the first communication section rises along the slope while its temperature increases due to heat exchange with the upper surface of the containment vessel, and is returned to the pool section via the second communication section. This promotes natural convection of the coolant, resulting in a good cooling effect.

[0042] (3) In another aspect, in the above aspect (1) or (2), The wall portion is provided with fins (60, 70) that extend along the wall portion with the center of the reactor containment vessel as a reference when the reactor containment vessel is viewed from above.

[0043] According to the above aspect (3), the fins are provided on the wall covering the top of the containment vessel, thereby promoting the dissipation of heat from the coolant, including the heat received from the containment vessel. In addition, the fins extend along the wall from the center of the containment vessel, so that there is little resistance to the flow of coolant that undergoes natural convection in the pool. This results in better cooling performance.

[0044] (4) In another embodiment, in the above embodiment (3), The fin has a length (L1) along the vertical direction that is greater than its length (L2) along the horizontal direction.

[0045] According to the above aspect (4), the fins provided on the wall surrounding the containment vessel have a so-called vertically elongated shape, in which the length in the vertical direction is longer than the length in the horizontal direction. Since the coolant is likely to flow vertically in the pool near the wall, providing the vertically elongated fins along this flow can promote heat exchange between the fins and the coolant and effectively improve the cooling performance. In this specification, the term "horizontal direction" refers to the direction along the upper surface of the coolant stored in the pool, and typically refers to a direction approximately perpendicular to the vertical direction. The term "vertical direction" refers to a direction approximately perpendicular to the horizontal direction, and typically refers to the vertical direction.

[0046] (5) In another aspect, in the above aspect (3) or (4), The fins are arranged so that at least a portion of the fins contacts the coolant stored in the pool portion.

[0047] According to the above aspect (5), the fins are arranged so as to come into contact with the coolant, thereby promoting heat exchange with the coolant whose temperature has been increased by the containment vessel, and good cooling performance is obtained.

[0048] (6) In another embodiment, in any one of the above (3) to (5), The fins are arranged so that at least a portion of the fins is exposed above the coolant stored in the pool portion.

[0049] According to the above aspect (6), the fins are arranged so as to be exposed above the coolant, and the coolant that is heated by the reactor containment vessel and evaporated can be condensed, thereby achieving good cooling performance.

[0050] (7) In another embodiment, in any one of the above (1) to (6), At least a portion of the wall defines a cavity containing a working fluid (74) having a higher thermal conductivity than the coolant.

[0051] According to the above aspect (7), at least a part of the wall of the pool that comes into contact with the coolant has a cavity. By sealing a working fluid having a higher thermal conductivity than the coolant in the cavity, heat transfer to the coolant can be promoted, and cooling performance can be effectively improved.

[0052] (8) In another embodiment, in the above embodiment (7), The inner wall of the cavity is provided with a rib (76) extending along the radial direction.

[0053] According to the above aspect (8), ribs are provided on the inner wall of the cavity provided in at least a part of the wall, thereby promoting heat exchange between the working fluid sealed in the cavity and the cavity, thereby further improving the cooling performance and improving the mechanical strength of the wall.

[0054] (9) In another aspect, in the above aspect (7) or (8), The working fluid includes a material that has a phase change.

[0055] According to the above aspect (9), a material that changes phase is used as the working fluid sealed in the cavity, which is expected to provide a good cooling effect by utilizing the latent heat generated when the working fluid changes phase. [Explanation of symbols]

[0056] 1. Nuclear power plants 2 nuclear reactor 4. Steam turbine 6. Generator 10 Primary Cooling Loop 11 Reactor pressure vessel 12 fuel rods 13 Control rods 14 Pressurizer 15 Pump 16 Steam Generator 18 Primary coolant pump 19 Reactor containment vessel 20 Secondary cooling loop 21 High-pressure turbine 22 Low-pressure turbine 23 minute separate heater 24 Condenser 25 Condensate pump 26 Low pressure feedwater heater 27 Deaerator 28 Water Pump 29 High-pressure feedwater heater 30 Cooling device 32 Reactor internals 34 Main body 36 Top 38 Bottom side 40 Central part 42 Incline 44 Wall 48 Coolant 49 Partition 50 Pool Club 55 Flow path 56 Flow path forming member 57 1st communication part 58 2nd communication part 60,70 fins 72 Cavity 74 Working Fluid 76 Ribs

Claims

1. a wall portion at least partially covering the containment vessel so as to form a pool portion for storing coolant between the wall portion and an upper portion of the containment vessel; a flow path forming member that extends along a convex upper surface provided on the upper portion, thereby forming a flow path between the upper surface and the flow path forming member, through which the coolant stored in the pool portion can pass; Equipped with the flow path has a first communication portion that communicates with the pool portion, and a second communication portion that is above the first communication portion and above a top of the flow path forming member and communicates with the pool portion.

2. the upper surface is an inclined surface having an apex at the center of the reactor containment vessel, 2. The containment vessel cooling device according to claim 1, wherein the first communication portion is provided at a position farther from the central portion than the second communication portion when the containment vessel is viewed from above.

3. 3. The reactor containment vessel cooling device according to claim 1, wherein the wall portion is provided with fins extending along the wall portion with a center of the reactor containment vessel as a reference when the reactor containment vessel is viewed from above.

4. 4. The containment vessel cooling system according to claim 3, wherein the fins have a length in the vertical direction greater than a length in the horizontal direction.

5. 5. The containment vessel cooling device according to claim 3, wherein the fins are arranged so that at least a portion of the fins contacts the coolant stored in the pool portion.

6. 6. The containment vessel cooling device according to claim 3, wherein the fins are arranged so that at least a portion of the fins is exposed above the coolant stored in the pool portion.

7. 7. The reactor containment vessel cooling device according to claim 1, wherein at least a portion of the wall portion comprises a cavity portion in which a working fluid having a higher thermal conductivity than the coolant is sealed.

8. 8. The containment vessel cooling system according to claim 7, wherein an inner wall of the cavity is provided with ribs extending along a radial direction.

9. 9. The containment vessel cooling system according to claim 7, wherein the working fluid includes a material having a phase change.

10. A wall portion at least partially covering the reactor containment vessel so as to form a pool portion for storing coolant between the wall portion and an upper portion of the reactor containment vessel; a flow path forming member that extends along a convex upper surface provided on the upper portion, thereby forming a flow path between the upper surface and the flow path forming member, through which the coolant stored in the pool portion can pass; Equipped with the flow path has a first communication portion communicating with the pool portion and a second communication portion communicating with the pool portion above the first communication portion, when the reactor containment vessel is viewed from above, the wall portion is provided with fins extending along the wall portion with the center of the reactor containment vessel as a reference; The fins are arranged so that at least a portion of the fins is exposed above the coolant stored in the pool portion.

11. A wall portion at least partially covering the reactor containment vessel so as to form a pool portion for storing coolant between the wall portion and an upper portion of the reactor containment vessel; a flow path forming member that extends along a convex upper surface provided on the upper portion, thereby forming a flow path between the upper surface and the flow path forming member, through which the coolant stored in the pool portion can pass; Equipped with the flow path has a first communication portion communicating with the pool portion and a second communication portion communicating with the pool portion above the first communication portion, At least a portion of the wall portion has a cavity in which a working fluid having a higher thermal conductivity than the coolant is sealed.

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