Decay heat removal system heat exchanger structure for fast reactors

Abstract

To provide a penetration type direct core cooling system heat exchanger structure capable of securing sealing performance between a heat exchanger and a partition plate and reducing occurrence of damage caused by thermal deformation of the heat exchanger.SOLUTION: A penetration type direct core cooling system heat-exchanger structure 70 includes: an inner shell 71 having an inlet window 71a and an outlet window 71b formed therein; an outer shell 73 surrounding part of the inner shell 71; a stand pipe 75 that is formed in a cylindrical shape and forms a first flow passage Pa and a second flow passage Pb by extending part of an upper end side to an annular space between the inner body 71 and the outer body 73; and a gas supply mechanism 77 for switching, by changing an amount of gas to be supplied, a shut-off state in which a liquid level L1 of a cooling material is located at a height lower than an upper end of the stand pipe 75 and higher than the lower end of the outer shell 73 and communication between the first flow passage Pa and the second flow passage Pb is shut off and a communication state in which a height of the liquid level L1 of the cooling material exceeds the upper end of the stand pipe 75 and the first flow passage Pa and the second flow passage Pb communicate with each other.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a heat exchanger structure for a decay heat removal system of a fast reactor. [Background technology]

[0002] A conventionally known penetration-type direct core cooling system heat exchanger structure in a decay heat removal system of a fast reactor includes an inner shell, an outer shell, and a gas supply means, and the gas supply means supplies inert gas between the inner shell and the outer shell to prevent coolant from flowing into the inner shell. The penetration-type direct core cooling system heat exchanger is arranged so as to penetrate a partition plate inside the main vessel of the fast reactor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 60-178391 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned Patent Document 1, the space between the inner body and the partition plate is sealed by a mechanical sealing structure, which makes it difficult to ensure sealing between the inner body and the partition plate, and there is also the problem that thermal deformation of the heat exchanger may cause interference between the heat exchanger and the partition plate, resulting in damage.

[0005] Therefore, the present invention has been made in consideration of these points, and its purpose is to provide a through-type direct core cooling system heat exchanger structure that ensures sealing between the heat exchanger and the partition plate and reduces the occurrence of damage caused by thermal deformation of the main vessel and the heat exchanger. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a through-type direct core cooling system heat exchanger structure, comprising: a cylindrical inner shell penetrating a partition plate that separates the interior of a main vessel into an upper plenum and a lower plenum, the inner shell having an entrance window that opens in the upper plenum and an exit window that opens in the lower plenum; an outer shell disposed in the upper plenum and surrounding a portion of the inner shell; and a cylindrical outer shell that penetrates the partition plate and surrounds the inner shell from the upper plenum to the lower plenum, with a portion of its upper end extending to an annular space between the inner shell and the outer shell, thereby forming an outer circumferential surface and a front surface. a standpipe that forms a first flow path through which coolant flows between the inner shell and the outer shell, and a second flow path that connects the upper plenum and the lower plenum between the inner circumferential surface and the inner shell; and a gas supply mechanism that changes the amount of gas supplied between the inner shell and the outer shell to switch between a blocked state in which the liquid level of the coolant is located below the upper end of the standpipe and above the lower end of the outer shell, thereby blocking communication between the first flow path and the second flow path, and a connected state in which the liquid level of the coolant exceeds the upper end of the standpipe, thereby connecting the first flow path and the second flow path.

[0007] The standpipe may be arranged so that an upper end of the standpipe is below the entrance window.

[0008] The outer peripheral surface of the standpipe may be fixed to the partition plate along the entire periphery, and the standpipe may not be in contact with the inner body.

[0009] The inner shell, the outer shell, and the standpipe may all be cylindrical members, and the first flow path and the second flow path may be formed in an annular shape. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a through-type direct core cooling system heat exchanger structure that ensures sealing between the heat exchanger and the partition plate and reduces the occurrence of damage caused by thermal deformation of the main vessel and the heat exchanger. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view showing the basic configuration of a fast reactor. [Figure 2] 1 is a schematic diagram showing an example of a fast reactor viewed from above. [Figure 3] 1 is a cross-sectional view schematically showing the peripheral structure of a penetration-type direct core cooling system heat exchanger structure of a fast reactor. FIG. [Figure 4] FIG. 2 is a cross-sectional view schematically showing a state in which a through-type direct core cooling system heat exchanger structure is in use. [Figure 5] FIG. 5 is an enlarged view showing a part of FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Configuration of fast reactor) The configuration of a fast reactor according to one embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view showing the basic configuration of the fast reactor 1. Fig. 2 is a schematic view showing an example of the fast reactor 1 as viewed from above. Fig. 3 is a cross-sectional view showing a schematic view of the peripheral structure of a through-type direct core cooling system heat exchanger structure 70 of the fast reactor 1. Fig. 1 is a cross-sectional view taken along line AA in Fig. 2, and Fig. 3 is a cross-sectional view taken along line BB. Arrows in Fig. 1 indicate the flow of sodium, which is a coolant.

[0013] The fast reactor 1 is, for example, a tank-type fast reactor, which extracts energy by controlling and sustaining a nuclear fission chain reaction using, for example, uranium or plutonium as fuel. The fast reactor 1 mainly comprises a main vessel 10, a core 20, a core barrel 30, a core upper structure 40, an intermediate heat exchanger 50, a pump 60, a through-type direct core cooling system heat exchanger structure 70, and a direct core cooling system heat exchanger 90.

[0014] The main vessel 10 is, for example, cylindrical with a bottom and has a diameter of, for example, about 15 m to 20 m. The main vessel 10 accommodates a reactor core 20, a core barrel 30, a reactor core upper structure 40, an intermediate heat exchanger 50, a pump 60, a through-type direct core cooling system heat exchanger structure 70, a direct core cooling system heat exchanger 90, and sodium or the like as a coolant for the primary system.

[0015] A roof slab 11, which functions as a lid, is provided on top of the main vessel 10. A partition plate 13 is provided inside the main vessel 10. The partition plate 13 is, for example, a circular member, and is arranged horizontally so as to divide the interior of the main vessel 10 into an upper plenum and a lower plenum. The upper plenum and the lower plenum are in communication with each other via the core barrel 30, the intermediate heat exchanger 50, the pump 60, and the like. As a result, by operating the pump 60 as described below, the coolant circulates between the upper plenum and the lower plenum.

[0016] Specifically, the partition plate 13 may be, for example, a member having a thickness of about 30 mm to 50 mm. The partition plate 13 may be formed by joining a plurality of plate-shaped members together.

[0017] The core 20 is a structural part having fuel assemblies and control rod assemblies (neither of which are shown), etc. The core barrel 30 is a vessel that houses the core 20, and is disposed in the center of the fast reactor 1. The core upper structure 40 is a structural part in which various measuring devices such as a control rod drive mechanism, a thermometer, and a fuel damage detector (neither of which are shown), are provided, and is disposed above the core 20, for example.

[0018] The intermediate heat exchanger 50 is formed in a cylindrical shape and is arranged vertically so as to penetrate the roof slab 11 and the partition plate 13. The intermediate heat exchanger 50 has an inlet window 51 located in the upper plenum and an outlet window 52 located in the lower plenum. The inlet window 51 is an opening through which high-temperature coolant in the upper plenum flows in. The outlet window 52 is an opening through which coolant that has passed through the interior of the intermediate heat exchanger 50 flows out into the lower plenum. The inlet window 51 is located below the liquid level L of the coolant.

[0019] The primary system coolant, whose temperature has risen due to the heat from the reactor core 20, is cooled inside the intermediate heat exchanger 50 by exchanging heat with the secondary system coolant (not shown).

[0020] 1, a cylindrical pipe member 55 is provided at the portion where the intermediate heat exchanger 50 penetrates the partition plate 13, and the intermediate heat exchanger 50 extends from the upper plenum to the lower plenum through the inside of the pipe member 55. As one example, a mechanical seal structure 55a is provided between the pipe member 55 and the intermediate heat exchanger 50 to separate the upper plenum from the lower plenum.

[0021] The pump 60 is a mechanism for circulating the coolant, and extends vertically so as to penetrate the roof slab 11 and the partition plate 13. The pump 60 pumps the coolant to the core barrel 30 through piping 61 provided in the lower plenum.

[0022] The coolant pumped into the core barrel 30 receives heat from the core 20 in the core barrel 30 and is heated to, for example, about 550°C. The coolant then flows upward inside the core barrel 30 and flows into the upper plenum. The coolant that has flowed into the upper plenum flows into the intermediate heat exchanger 50 through the inlet window 51 of the intermediate heat exchanger 50, is cooled inside the intermediate heat exchanger 50 to, for example, about 400°C, flows downward inside the intermediate heat exchanger 50, and flows out through the outlet window 52.

[0023] The coolant that flows out of the outlet window 52 and into the lower plenum is sucked in by the pump 60 and, as described above, is pumped back into the core barrel 30 by the action of the pump 60. In this way, the coolant cools the core 20 while circulating within the main vessel 10.

[0024] 2 shows a specific arrangement of the intermediate heat exchanger 50, the pump 60, the through-type direct core cooling system heat exchanger structure 70, and the direct core cooling system heat exchanger 90, but the number and arrangement positions of these components may be changed as appropriate depending on the specifications of the fast reactor 1. The direct core cooling system heat exchanger 90 is a conventionally known direct core cooling system heat exchanger, and therefore a detailed description thereof will be omitted.

[0025] (About the penetrating type direct core cooling system heat exchanger structure 70) The through-type direct core cooling system heat exchanger structure 70 is an auxiliary cooling structure of the thermal dissipation system, and does not operate during normal operation of the fast reactor 1, but operates to cool the core inside the main vessel 10 in the event of, for example, an abnormal transient change or some kind of accident.

[0026] 3, the through-type direct core cooling system heat exchanger structure 70 includes an inner shell 71, an outer shell 73, a standpipe 75, and a gas supply mechanism 77. Similar to the intermediate heat exchanger 50, the through-type direct core cooling system heat exchanger structure 70 cools the reactor core by exchanging heat between the coolant of the primary system inside the main vessel 10 and the coolant of the secondary system outside the main vessel 10.

[0027] The inner body 71 is a tubular member arranged vertically so as to penetrate the roof slab 11 and the partition plate 13. The inner body 71 is, for example, a cylinder whose upper and lower ends are closed. The inner body 71 is fixed to the main vessel 10, for example, by being joined to the roof slab 11. An inlet window 71a that opens into the upper plenum and an outlet window 71b that opens into the lower plenum are formed on the outer circumferential surface of the inner body 71. A flow path (not shown) through which the secondary system coolant flows is formed inside the inner body 71, and the primary system coolant that flows into the inner body 71 is cooled by heat exchange with the secondary system coolant.

[0028] The outer shell 73 is a member for forming a space between the inner shell 71 and the outer shell 73 to which gas is supplied from the gas supply mechanism 77. The outer shell 73 is arranged in the upper plenum and has a cylindrical shape that surrounds a part of the inner shell 71. As an example, the outer shell 73 is a cylindrical member having a diameter larger than that of the inner shell 71, and is connected to the roof slab 11. The outer shell 73 is arranged, for example, coaxially with the inner shell 71. The outer shell 73 extends vertically so that its lower end is located below the entrance window 71a of the inner shell 71.

[0029] The standpipe 75 has a cylindrical shape and surrounds a portion of the inner body 71. The standpipe 75 is a cylindrical member having, for example, a diameter larger than that of the inner body 71 and smaller than that of the outer body 73. As an example, the standpipe 75 is arranged coaxially with the inner body 71 and the outer body 73. Specifically, the standpipe 75 is arranged to penetrate the partition plate 13 and surrounds a portion of the inner body 71 from the upper plenum to the lower plenum of the main vessel 10.

[0030] As an example, the standpipe 75 is arranged so as not to contact the inner body 71. The diameter of the standpipe 75 is determined appropriately taking into consideration, for example, the amount of deformation of the inner body 71 due to thermal stress and the ease of operation when removing the through-type direct core cooling system heat exchanger from the main vessel 10.

[0031] It is preferable that the standpipe 75 is configured so as not to come into contact with the inner body 71, but the standpipe 75 and the inner body 71 may be partially connected while maintaining a gap between them.

[0032] As an example, the standpipe 75 is coupled to the partition plate 13. Specifically, the entire outer periphery of the standpipe 75 is fixed to the partition plate 13. More specifically, the outer periphery of the standpipe 75 is fixed to the partition plate 13 in such a manner that no gap through which the coolant passes is formed between the standpipe 75 and the partition plate 13. The outer periphery of the standpipe 75 and the partition plate 13 may be fixed by, for example, welding.

[0033] The entire outer periphery of the standpipe 75 is fixed to the partition plate 13, thereby preventing the coolant from flowing from the upper plenum to the lower plenum through the gap between the standpipe 75 and the partition plate 13. This means that the occurrence of a bypass flow in which the coolant flows from the upper plenum to the lower plenum is suppressed, other than through the intermediate heat exchanger 50. With this configuration, it is possible to suppress a reduction in cooling efficiency due to the bypass flow.

[0034] 3, the standpipe 75 is disposed so that a portion of its upper end extends into the annular space between the inner shell 71 and the outer shell 73. In other words, the standpipe 75 is disposed between the inner shell 71 and the outer shell 73 in a positional relationship such that its upper end is inserted between the inner shell 71 and the outer shell 73.

[0035] A first flow path Pa through which the coolant flows is formed between the outer peripheral surface of the standpipe 75 and the outer body 73. The first flow path Pa may be, for example, an annular flow path with a constant width in the circumferential direction. A second flow path Pb that connects the upper plenum and the lower plenum is formed between the inner peripheral surface of the standpipe 75 and the inner body 73. The second flow path Pb may be, for example, an annular flow path with a constant width in the circumferential direction, similar to the first flow path Pa.

[0036] The standpipe 75 is disposed so that its upper end is lower than the inlet window 71a of the inner body 71. Specifically, the upper end of the standpipe 75 is preferably located lower than the top of the inlet window 71a, and more preferably at the same height as or lower than the bottom of the inlet window 71a. The reason why such a configuration is preferable will be described later together with the explanation of the operation of the through-type direct core cooling system heat exchanger structure 70.

[0037] (Regarding gas supply mechanism 77) 3, the gas supply mechanism 77 includes a gas supply source 78, a gas flow path 79, a first valve 80a, a second valve 80b, a first gas supply member 81a, a second gas supply member 81b, and a control device 82. The first valve 80a and the second valve 80b may be manually operated by an operator to switch between open and closed states, but the following example illustrates a configuration in which the opening and closing are controlled by the control device 82.

[0038] The gas supply source 78 pumps an inert gas into the main container 10 at a predetermined pressure. The gas flow path 79 has a first flow path 79a extending from the gas supply source 78, a second flow path 79b branching off from the first flow path 79a, and a third flow path 79c branching off from the first flow path 79a. A first valve 80a is provided in the first flow path 79a. The second flow path 79b is a flow path connected to a first gas supply member 81a. The third flow path 79c is a flow path connected to a second gas supply member 81b, and a second valve 80b is provided in the third flow path 79c.

[0039] As an example, the first valve 80a and the second valve 80b are valves having a drive unit (not shown) that switches the open / closed state of the valve based on a control signal from the control device 82. Specifically, the first valve 80a and the second valve 80b may be valves in which the flow rate of gas passing through the valve is changed by changing the degree of opening of the valve.

[0040] The control device 82 controls the operations of the first valve 80a, the second valve 80b, and the gas supply source 78. The control device 82 is configured to receive a signal indicating an abnormality in the fast reactor 1 from a detection device (not shown) that detects an abnormality in the fast reactor 1. The control device 82 transmits a control signal to each of the first valve 80a and the second valve 80b to open or close the valve. The control device 82 also transmits a control signal to the gas supply source 78 to start or stop the supply of inert gas. The control signal may include a command value for the gas flow rate.

[0041] For example, while the control device 82 is not receiving a signal indicating an abnormality in the fast reactor 1, it opens the first valve 80a to open the gas flow path 79. On the other hand, the second valve 80b is closed. The control device 82 also operates the gas supply source 78 to supply inert gas from the gas supply source 78 into the main vessel 10. As a result, between the inner body 71 and the outer body 73, the inert gas supplied via the first gas supply member 81a presses the coolant liquid level L1 to below the inlet window 71a of the inner body 71. Outside the outer body 73, the coolant liquid level L is located above the inlet window 51 of the intermediate heat exchanger 50.

[0042] When the control device 82 receives a signal indicating an abnormality in the fast reactor 1, it, for example, closes the first valve 80a and stops the supply of inert gas from the gas supply source 78. This stops the supply of inert gas between the inner body 71 and the outer body 73. Furthermore, by opening the second valve 80b, the liquid level L1 of the coolant between the inner body 71 and the outer body 73 gradually rises to a height above the inlet window 71a of the inner body 71.

[0043] (Operation of the through-type direct core cooling system heat exchanger structure 70) The operation of the penetration-type direct core cooling system heat exchanger structure 70 configured as described above will be described below. Fig. 4 is a cross-sectional view showing the penetration-type direct core cooling system heat exchanger structure 70 in use. Fig. 4, like Fig. 3, is a cross-sectional view taken along line BB in Fig. 2. Fig. 5 is an enlarged view showing a part of Fig. 4.

[0044] During normal operation of the fast reactor 1, the through-type direct core cooling system heat exchanger structure 70 does not operate. The control device 82 sends control signals to the first valve 80a and the gas supply source 78 to open the first valve 80a to put the gas flow path 79 in a communicating state and to cause the gas supply source 78 to start supplying inert gas. The second valve 80b is in a closed state. The gas supply source 78 supplies inert gas between the inner body 71 and the outer body 73 so that the height of the coolant liquid level L1 in the space between the inner body 71 and the outer body 73 is located below the upper end of the standpipe 75 and above the lower end of the outer body 73, as shown in FIG. 3 .

[0045] This state is a blocked state in which communication between the first flow path Pa and the second flow path Pb is blocked by gas supplied from the gas supply mechanism 77. Specifically, communication between the first flow path Pa and the second flow path Pb is blocked by gas supplied between the inner body 71 and the outer body 73 pushing the liquid level L1 below the upper end of the standpipe 75. Because communication between the first flow path Pa and the second flow path Pb is blocked, the coolant in the upper plenum does not flow into the lower plenum as a bypass flow.

[0046] On the other hand, the standpipe 75 is fixed to the partition plate 13 by, for example, welding, so that the coolant in the upper plenum does not flow into the lower plenum as a bypass flow through the gap between the standpipe 75 and the partition plate 13.

[0047] When the through-type direct core cooling system heat exchanger structure 70 is operated, the amount of gas supplied from the gas supply mechanism 77 is reduced or the supply of gas from the gas supply mechanism 77 is stopped. In the present embodiment, for example, when the control device 82 receives a signal indicating an abnormality in the fast reactor 1 from a detection device (not shown), the control device 82 closes the first valve 80a to stop the supply of inert gas from the gas supply source 78. This stops the supply of inert gas between the inner shell 71 and the outer shell 73. Furthermore, by opening the second valve 80b, the height of the coolant liquid level L1 rises to a position above the upper end of the standpipe 75, as shown in FIG. 4. Specifically, for example, the height of the coolant liquid level L1 rises above the inlet window 71a.

[0048] In this state, the first flow path Pa and the second flow path Pb are connected to each other, and as shown by the arrows in Figure 5, the coolant from the upper blenum flows through the first flow path Pa into the space between the inner body 71 and the outer body 73, and then flows into the inner body 71 through the inlet window 71a, where it is cooled by the through-type direct core cooling system heat exchanger structure 70.

[0049] (Action and effect) As described above, in the through-type direct core cooling system heat exchanger structure 70 of this embodiment, the standpipe 75 is disposed between the inner body 71 and the outer body 73, the first flow path Pa is formed between the inner body 71 and the standpipe 75, and the second flow path Pb is formed between the standpipe 75 and the outer body 73. The gas supply mechanism 77 changes the amount of gas supplied between the inner body 71 and the outer body 73 to change the height of the coolant liquid surface L1 in the space between the inner body 71 and the outer body 73, and switches between a connected state and a disconnected state of the first flow path Pa and the second flow path Pb.

[0050] In a conventional configuration in which a standpipe 75 is not provided, in order to prevent a bypass flow from flowing from the upper plenum to the lower plenum around the inner body 71, it was necessary to provide a mechanical seal structure, for example, between the outer periphery of the inner body 71 and the inner periphery of a tubular member fixed to the partition plate 13.

[0051] However, in the fast reactor 1, the through-type direct core cooling system heat exchanger structure 70 is thermally deformed, and therefore the mechanical seal structure must be able to absorb the thermal deformation of the through-type direct core cooling system heat exchanger structure 70. If the thermal deformation cannot be absorbed, the through-type direct core cooling system heat exchanger structure 70 or the partition plate 13 may be damaged. Furthermore, since it is expected that the through-type direct core cooling system heat exchanger structure 70 will be removed from the roof slab 11 for maintenance, the mechanical seal structure must be able to withstand the removal of the through-type direct core cooling system heat exchanger structure 70. For these reasons, a mechanical seal structure has problems such as a complicated structure and difficulty in ensuring sufficient sealing due to thermal deformation of the through-type direct core cooling system heat exchanger structure 70.

[0052] In contrast, according to the configuration of this embodiment, no mechanical seal structure is provided between the standpipe 75 and the inner shell 71, and the liquid level L1 is pressed down by the inert gas supplied between the inner shell 71 and the outer shell 73, thereby blocking communication between the first flow path Pa and the second flow path Pb, i.e., the communication between the upper plenum and the lower plenum. Therefore, the coolant is effectively prevented from flowing from the upper plenum into the lower plenum.

[0053] Furthermore, when the upper end of the standpipe 75 is positioned below the inlet window 71a of the inner body 71, as shown in Figure 5, there is an advantage that the coolant can easily flow from the second flow path Pb toward the inlet window 71a when the through-type direct core cooling system heat exchanger structure 70 is in operation.

[0054] Furthermore, since the standpipe 75 is not in contact with the inner shell 71, even if the inner shell 71 is thermally deformed within a range where it does not come into contact with the standpipe 75, no force is applied from the inner shell 71 to the standpipe 75. Therefore, damage to the through-type direct core cooling system heat exchanger structure 70 or the partition plate 13 is prevented.

[0055] Furthermore, when the inner body 71, the outer body 73, and the standpipe 75 are all cylindrical components and the first flow path Pa and the second flow path Pb are formed in an annular shape, the flow of coolant becomes uniform in the circumferential direction of the through-type direct core cooling system heat exchanger structure 70, and the coolant flows smoothly.

[0056] It is not necessary that all of the through-type direct core cooling system heat exchanger structures 70 of the fast reactor 1 have the above-described configuration, but it is sufficient that at least one of the through-type direct core cooling system heat exchanger structures 70 has the above-described configuration. Although the through-type direct core cooling system heat exchanger structure 70 has been described above, the through-type direct core cooling system heat exchanger structure of the present invention may be applied to other types of heat exchangers.

[0057] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by functionally or physically distributing or integrating any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments. [Explanation of symbols]

[0058] 1 Fast reactor 10 Main vessel 11 Roof slab 13 Divider 20 Core 30 Core vessel 40 Core superstructure 50 Intermediate heat exchanger 51 Entrance window 52 Exit window 55 Pipe members 55a Seal structure 60 Pump 61 Piping 70 Penetrating direct core cooling system heat exchanger structure 71 Inner body 71a Entrance window 71b Exit window 73 Outer body 75 Standpipe 77 Gas supply mechanism 78 Gas Supply Source 79 Gas flow path 79a First flow path 79b Second flow path 79c Third Channel 80a First valve 80b Second valve 81a first gas supply member 81b second gas supply member 82 Control device 90 Direct core cooling system heat exchanger L liquid level L1 liquid level Pa 1st flow path Pb Second flow path

Claims

1. a cylindrical inner shell that penetrates a partition plate that divides the interior of the main vessel into an upper plenum and a lower plenum, the inner shell having an inlet window that opens into the upper plenum and an outlet window that opens into the lower plenum; an outer shell disposed in the upper plenum and surrounding a portion of the inner shell; a standpipe formed in a cylindrical shape, penetrating the partition plate and surrounding the inner shell from the upper plenum to the lower plenum, with a portion of its upper end extending to the annular space between the inner shell and the outer shell, thereby forming a first flow path through which coolant flows between the outer shell's outer peripheral surface and the standpipe, and a second flow path between the inner shell's inner peripheral surface and the inner shell, which connects the upper plenum and the lower plenum; a gas supply mechanism that switches between a blocking state in which the liquid level of the coolant is located below the upper end of the standpipe and above the lower end of the outer shell, thereby blocking communication between the first flow path and the second flow path, and a communicating state in which the liquid level of the coolant exceeds the upper end of the standpipe, thereby connecting the first flow path and the second flow path, by changing the amount of gas supplied between the inner shell and the outer shell; Equipped with the outer circumferential surface of the stand pipe is fixed to the partition plate along the entire periphery, and the stand pipe is not in contact with the inner shell; Penetrating type direct core cooling system heat exchanger structure.

2. The standpipe is arranged so that the upper end of the standpipe is lower than the entrance window. The through-type direct core cooling system heat exchanger structure according to claim 1 .

3. the inner shell, the outer shell, and the standpipe are all cylindrical members, and the first flow path and the second flow path are formed in an annular shape.

3. The through-type direct core cooling system heat exchanger structure according to claim 1 or 2.

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