High-temperature gas reactor and high-temperature gas reactor system

Abstract

To provide a high-temperature gas reactor and a high-temperature gas reactor system, which can reduce a temperature difference between upper and lower surfaces of a support plate.SOLUTION: A high-temperature gas reactor is provided, comprising a hollow reactor vessel, a reactor core provided inside the reactor vessel, a lower support plate horizontally provided in a lower portion of the reactor vessel, a high-temperature coolant flow path for a high-temperature coolant to flow from the lower portion of the reactor vessel toward the reactor core through a space above the lower support plate, a low-temperature coolant flow path for a low-temperature coolant to flow from a side portion of the reactor vessel downward through a space below the lower support plate, and a heat absorbing structure provided on an upper surface portion of the lower support plate.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] TECHNICAL FIELD This disclosure relates to high temperature gas-cooled reactors and high temperature gas-cooled reactor systems. [Background technology]

[0002] A high-temperature gas-cooled reactor is a nuclear reactor capable of extracting high-temperature thermal energy of 900°C or more by using coated fuel particles in which fuel kernels such as uranium dioxide are coated with a ceramic material as the nuclear fuel, helium as the coolant, and graphite as the moderator and the main structural material inside the reactor. A high-temperature gas-cooled reactor contains a core inside a pressure vessel. The core is composed of reflector blocks arranged inside and outside a fuel block. A high-temperature gas-cooled reactor generates heat by emitting neutrons through nuclear fission of nuclear fuel. Helium gas is supplied from the bottom of the pressure vessel, rises through the outside of the core, and then descends through the fuel block of the core. The helium gas is heated to a high temperature by cooling the core, and is discharged to the outside to extract heat. An example of such a high-temperature gas-cooled reactor is that described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 61-068586 Summary of the Invention [Problem to be solved by the invention]

[0004] Since the core of a high-temperature gas-cooled reactor becomes hot, it requires a high-temperature coolant to cool the core and a low-temperature coolant to cool the pressure vessel. For example, as mentioned above, the high-temperature coolant (high-temperature helium gas) is supplied from the bottom of the pressure vessel, rises through the outside of the core, and then passes through the core and descends to cool the core. On the other hand, the low-temperature coolant (low-temperature helium gas) is supplied from the side of the pressure vessel, rises along the inner wall of the pressure vessel, and then descends to cool the pressure vessel. In this case, it is necessary to separate the flow paths so that the high-temperature coolant that is supplied from the bottom of the pressure vessel and rises and the low-temperature coolant that is supplied from the side of the pressure vessel and descends to be discharged to the outside do not mix.

[0005] The pressure vessel has a double tube consisting of an inner tube and an outer tube at the bottom, and a horizontal support plate is connected to the top of the inner tube. The high-temperature coolant rises through the inner tube and flows outward through the upper surface of the support plate. Meanwhile, the low-temperature coolant descends along the inner wall of the pressure vessel, flows inward through the lower surface of the support plate, and is discharged to the outside through the gap between the inner tube and the outer tube. That is, the support plate functions as a partition plate for separating the flow paths of the high-temperature coolant and the low-temperature coolant. However, since the high-temperature coolant and the low-temperature coolant directly contact each other on the support plate, the temperature difference between the upper and lower surfaces becomes large. As a result, the support plate is subjected to large stress due to thermal deformation, and it may be difficult to ensure sufficient structural strength.

[0006] The present disclosure is devised to solve the above-mentioned problems, and has an object to provide a high-temperature gas-cooled reactor and a high-temperature gas-cooled reactor system capable of reducing the temperature difference between the upper and lower surfaces of a support plate. [Means for solving the problem]

[0007] In order to achieve the above-mentioned objective, the high-temperature gas reactor of the present disclosure comprises a hollow reactor vessel, a core disposed inside the reactor vessel, a lower support plate disposed horizontally at the bottom of the reactor vessel, a high-temperature coolant flow passage through which high-temperature coolant flows from the bottom of the reactor vessel and above the lower support plate toward the core, a low-temperature coolant flow passage through which low-temperature coolant flows from the side of the reactor vessel and downwardly below the lower support plate, and a heat absorption structure disposed on an upper surface of the lower support plate.

[0008] In addition, the high-temperature gas reactor system disclosed herein includes a high-temperature gas reactor that extracts heat generated by nuclear fission to the outside using helium gas, an intermediate heat exchanger that exchanges heat between the high-temperature helium gas discharged from the high-temperature gas reactor and a heat medium, a gas turbine power generation system that generates electricity by driving a turbine with the high-temperature helium gas discharged from the intermediate heat exchanger, and a regenerative heat exchanger that exchanges heat between the high-temperature helium gas discharged from the gas turbine power generation system and low-temperature helium gas. Effect of the Invention

[0009] According to the high temperature gas-cooled reactor and high temperature gas-cooled reactor system disclosed herein, the temperature difference between the upper and lower surfaces of the support plate can be reduced. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing a high temperature gas reactor system according to this embodiment. [Diagram 2] FIG. 2 is a detailed view showing the lower part of the high temperature gas reactor of this embodiment. [Diagram 3] FIG. 3 is a schematic diagram showing details of the lower part of a high-temperature gas-cooled reactor. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3, showing a horizontal section of the lower part of the high-temperature gas-cooled reactor. [Diagram 5] FIG. 5 is a VV cross-sectional view of FIG. 3 showing a horizontal cross-section of the lower part of the high-temperature gas-cooled reactor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes a configuration in which each embodiment is combined. In addition, the components in the embodiments include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range.

[0012] <High-Temperature Gas-Cooled Reactor System> FIG. 1 is a schematic diagram showing a high temperature gas reactor system according to this embodiment.

[0013] As shown in FIG. 1, a high temperature gas reactor system 10 includes a high temperature gas reactor 11, an intermediate heat exchanger 12, a gas turbine power generation system 13, and a regenerative heat exchanger 14.

[0014] The high temperature gas reactor 11 is a nuclear reactor that uses helium gas as a coolant to extract heat generated by nuclear fission to the outside. The high temperature gas reactor 11 is configured by accommodating a reactor core (nuclear fuel) 22 inside a reactor vessel 21. The reactor vessel 21 is provided with an inlet section 23 and an outlet section 24. Helium gas is supplied to the reactor vessel 21 from the inlet section 23, rises along the inner wall of the reactor vessel 21, and descends through the reactor core 22. The helium gas is heated to a high temperature as it passes through the core 22, and is discharged to the outside of the reactor vessel 21 from the outlet section 24.

[0015] The intermediate heat exchanger 12 is configured by accommodating a heat exchange section 26 inside a pressure vessel 25. The pressure vessel 25 is provided with an inlet section 27 and an outlet section 28, and the inlet section 27 is connected to the outlet section 24 of the reactor vessel 21 in the high temperature gas reactor 11 via a pipe 29. The pressure vessel 25 is also provided with a supply section 30 that supplies a heat medium to the heat exchange section 26, and a discharge section 31 that discharges the heat medium from the heat exchange section 26. Helium gas is supplied to the pressure vessel 25 from the inlet section 27, and the heat medium is supplied to the heat exchange section 26 from the supply section 30. The heat exchange section 26 exchanges heat between the high-temperature helium gas and the heat medium. The helium gas whose temperature has been reduced by the heat exchange is discharged from the outlet section 28 to the outside of the pressure vessel 25. On the other hand, the heat medium whose temperature has been increased by the heat exchange is discharged from the discharge section 31 to the outside of the pressure vessel 25.

[0016] The gas turbine power generation system 13 has a gas turbine 32 and a generator 33. The gas turbine 32 has a turbine 34 and a compressor 35. The turbine 34 and the compressor 35 can rotate together by a rotating shaft 36. The generator 33 is connected to one end of the rotating shaft 36 in the axial direction. In the gas turbine power generation system 13, a pipe 37 from the intermediate heat exchanger 12 is connected to the gas turbine 32. Helium gas is supplied to the turbine 34 of the gas turbine 32. The turbine 34 is driven by the supplied helium gas to rotate the rotating shaft 36. The generator 33 obtains driving force from the rotating shaft 36 to generate electricity.

[0017] The regenerative heat exchanger 14 is configured by accommodating a heat exchange section 42 and a cooling section 43 inside a pressure vessel 41. The pressure vessel 41 has a vertical shape, with the heat exchange section 42 arranged at the top and the cooling section 43 arranged at the bottom. The pressure vessel 41 is provided with an inlet section 44 and an outlet section 45, the inlet section 44 is connected to the gas turbine power generation system 13 via a pipe 46, and the outlet section 45 is connected to the inlet section 23 of the reactor vessel 21 in the high temperature gas reactor 11 via a pipe 47. Helium gas is supplied from the inlet section 44 to the pressure vessel 41 and supplied to the heat exchange section 42. The helium gas is supplied to the cooling section 43 of the heat exchange section 42 and cooled, and then supplied to the heat exchange section 42 again. The heat exchange section 42 exchanges heat between the helium gas supplied from the gas turbine power generation system 13 and the helium cooled in the cooling section 43. The helium gas whose temperature has been reduced by the heat exchange is discharged to the outside of the pressure vessel 41 through the outlet 45 and returned to the high-temperature gas reactor 11 .

[0018] <Configuration of High Temperature Gas-cooled Reactor> FIG. 2 is a detailed view showing the lower part of the high temperature gas reactor of this embodiment.

[0019] As shown in FIG. 2, the high temperature gas reactor 11 is a nuclear reactor that uses coated fuel particles in which fuel kernels such as uranium dioxide are coated with a ceramic material as nuclear fuel, uses helium as a coolant, and uses graphite as a moderator.

[0020] In the high temperature gas reactor 11, the reactor vessel 21 is a pressure vessel in which reactor internals are arranged. The reactor vessel 21 has a reactor vessel main body 51 and a reactor vessel lid 52. The reactor vessel main body 51 is cylindrical in shape, and the lower part in the vertical direction is closed in a hemispherical shape. The reactor vessel main body 51 has a hemispherical reactor vessel lid 52 fixed thereto by bolts (not shown) so as to be able to be opened and closed.

[0021] A double tube 53 is disposed at the bottom of the reactor vessel 21. The double tube 53 has an inner tube 54 and an outer tube 55. The inner tube 54 penetrates the bottom of the reactor vessel body 51 in the vertical direction, and the upper part of the inner tube 54 extends vertically upward, that is, into the inside of the reactor vessel body 51. The outer tube 55 is disposed outside the inner tube 54 with a gap therebetween, and the upper part is connected to the bottom of the reactor vessel body 51. The inner tube 54 functions as an inlet 23 for high-temperature coolant (high-temperature helium gas), and the space between the inner tube 54 and the outer tube 55 functions as an outlet 56 for low-temperature coolant (low-temperature helium gas).

[0022] Further, a double tube 57 is disposed in the lower part of the reactor vessel 21. The double tube 57 has an inner tube 58 and an outer tube 59. The inner tube 58 penetrates the lower part of the reactor vessel body 51 in the horizontal direction, and an end part of the inner tube 58 extends into the inside of the reactor vessel body 51. The outer tube 59 is disposed outside the inner tube 58 with a gap therebetween, and an end part of the outer tube 59 is connected to the lower part of the reactor vessel body 51. The inner tube 58 functions as the outlet part 24 for the high-temperature coolant (high-temperature helium gas), and the space between the inner tube 58 and the outer tube 59 functions as the inlet part 60 for the low-temperature coolant (low-temperature helium gas).

[0023] In the reactor vessel 21, the core barrel 61 is disposed at an interval inside the reactor vessel body 51. The core barrel 61 has a cylindrical shape and is supported by the reactor vessel body 51. The core barrel 61 has an upper support plate 62 and a lower support plate 63 connected to its lower part. The upper support plate 62 and the lower support plate 63 have a disk shape. The lower support plate 63 is connected to the lower end of the core barrel 61, and the upper support plate 62 is connected to the core barrel 61 at a predetermined distance above the lower support plate 63. The inner cylinder 54 constituting the double pipe 53 has an upper end penetrating the lower support plate 63 and communicating with the space between the upper support plate 62 and the lower support plate 63. The outer cylinder 55 constituting the double pipe 53 has an upper end communicating with the space below the lower support plate 63. Moreover, an end of an inner cylinder 58 constituting the double pipe 57 penetrates the core barrel 61 and communicates with the space inside the core barrel 61. An end of an outer cylinder 59 constituting the double pipe 57 communicates with the space between the reactor vessel body 51 and the core barrel 61.

[0024] The reactor vessel 21 has a core 22 disposed therein. The core 22 has a fuel block 71, an inner reflector block 72, and an outer reflector block 73. The core 22 has a structure in which regular hexagonal prism blocks are stacked, and the inner reflector block 72 and the outer reflector block 73 are made of graphite. The fuel block 71 has a cylindrical shape, with the inner reflector block 72 disposed on the inside and the outer reflector block 73 disposed on the outside. The core 22 is disposed inside the core barrel 61, and is supported by the upper support plate 62.

[0025] That is, a lower block 74 is disposed on the upper part of the upper support plate 62, and a high-temperature plenum block 76 is supported via a support column 75. The core 22 is supported on the upper part of the high-temperature plenum block 76. The lower block 74, the support column 75, and the high-temperature plenum block 76 are formed of graphite. The fuel block 71 is provided with a number of flow passages along the vertical direction through which the high-temperature coolant can descend. Also, the outer reflector block 73 is provided with a flow passage on the outer periphery adjacent to the core barrel 61 through which the high-temperature coolant can ascend.

[0026] In the reactor vessel 21, a control rod drive mechanism 77 is disposed on the reactor vessel lid 52. The control rod drive mechanism 77 controls the reactor power by inserting and withdrawing a plurality of control rods (not shown) into and from the reactor core 22.

[0027] The reactor vessel 21 is provided therein with a high-temperature coolant flow passage 81 and a low-temperature coolant flow passage 82. As shown by a solid line in Fig. 2, the high-temperature coolant flow passage 81 is a flow passage through which the high-temperature coolant (high-temperature helium gas) flows from the lower part (inlet part 23) of the reactor vessel 21, passes above the lower support plate 63, flows outward in the radial direction, and then flows downward toward the core 22, and is discharged from the lower part (outlet part 24) of the reactor vessel 21 after descending from the core 22. On the other hand, the low-temperature coolant flow passage 82 is a flow passage through which the low-temperature coolant (low-temperature helium gas) flows from the lower part (inlet part 60) of the reactor vessel 21, rises in the flow passage between the reactor vessel main body 51 and the core barrel 61, and then flows downward through the lower part of the lower support plate 63, and is discharged from the lower part (outlet part 56) of the reactor vessel 21, as shown by a dotted line in Fig. 2.

[0028] <Operation of High Temperature Gas Reactor> In the high-temperature gas reactor 11, when a nuclear fission reaction occurs between neutrons and fissile nuclides of the atomic fuel constituting the fuel block 71, thermal energy is generated and neutrons (thermal neutrons) are generated at the same time, maintaining criticality. That is, the atomic fuel undergoes nuclear fission to release neutrons, and the graphite moderator reduces the kinetic energy of the released high-speed neutrons to turn them into thermal neutrons, making it easier for new nuclear fission to occur, while the high-temperature coolant (high-temperature helium gas) removes the generated heat to cool the core 22. In addition, the control rods are inserted and removed from the core 22 to control nuclear fission. That is, the number of neutrons generated in the core 22 is adjusted by inserting the control rods into the core 22.

[0029] The high-temperature coolant is supplied to the inside from the inlet 23 (inner cylinder 54) provided at the bottom of the reactor vessel 21. The high-temperature coolant rises in the inner cylinder 54, flows outward in the space between the upper support plate 62 and the lower support plate 63, and rises inside the reactor vessel 21 through a number of flow paths (not shown) along the vertical direction near the inner wall surface of the core barrel 61. The high-temperature coolant that has risen inside the reactor vessel 21 turns over at the top of the reactor vessel 21 and descends through a number of flow paths in the fuel block 71 that constitutes the core 22. At this time, the high-temperature coolant is heated by cooling the core 22. The heated high-temperature coolant flows from the high-temperature plenum block 76 to the support column 75 and is discharged to the outside of the reactor vessel 21 from the outlet 24 (inner cylinder 58).

[0030] Meanwhile, the low-temperature coolant is supplied to the inside from an inlet portion 60 (outer casing 59) provided on the lower side of the reactor vessel 21. A part of the low-temperature coolant rises in the flow path between the reactor vessel main body 51 and the core barrel 61, thereby cooling the reactor vessel 21. A part of the low-temperature coolant falls in the flow path between the reactor vessel main body 51 and the core barrel 61, thereby cooling the reactor vessel 21. The low-temperature coolant that has fallen in the flow path between the reactor vessel main body 51 and the core barrel 61 flows into the space below the lower support plate 63, and is discharged to the outside of the reactor vessel 21 from an outlet portion 56 (outer casing 55).

[0031] <High-Temperature Gas-Cooled Reactor Substructure> Figure 3 is a schematic diagram showing details of the lower part of the high-temperature gas-cooled reactor, Figure 4 is a cross-sectional view taken along line IV-IV of Figure 3 showing a horizontal cross-section of the lower part of the high-temperature gas-cooled reactor, and Figure 5 is a cross-sectional view taken along line VV of Figure 3 showing a horizontal cross-section of the lower part of the high-temperature gas-cooled reactor.

[0032] As shown in FIG. 3 to FIG. 5, in the reactor vessel 21, the core barrel 61 is arranged inside the reactor vessel main body 51 with a gap therebetween, and the upper support plate 62 and the lower support plate 63 are connected to the lower part of the core barrel 61. The upper support plate 62 and the lower support plate 63 are arranged at a predetermined distance in the vertical direction, and a high temperature space portion 83 is formed between them. The upper end of the inner cylinder 54 constituting the double pipe 53 penetrates the lower support plate 63 and communicates with the high temperature space portion 83. In addition, a low temperature space portion 84 is formed between the lower support plate 63 and the lower end of the reactor vessel main body 51. The upper end of the outer cylinder 55 constituting the double pipe 53 communicates with the low temperature space portion 84. The upper support plate 62, the lower support plate 63, and the double pipe 53 are formed of steel members.

[0033] As shown by solid lines in Fig. 3, the high-temperature coolant flow passage 81 is a flow passage that flows from the inner cylinder 54 (inlet section 23) above the lower support plate 63, i.e., through the high-temperature space section 83, radially outward, and then ascends through a flow passage inside the inner wall surface of the core barrel 61. As shown by dotted lines in Fig. 3, the low-temperature coolant flow passage 82 is a flow passage that flows downward through a flow passage between the reactor vessel body 51 and the core barrel 61, and then flows below the lower support plate 63, i.e., through the low-temperature space section 84, radially inward, and is discharged from the outer cylinder 55 (outlet section 56).

[0034] A support structure 64 is disposed between the upper support plate 62 and the lower support plate 63. The support structure 64 has a plurality of support structure parts 65. A high-temperature space part 83 formed between the upper support plate 62 and the lower support plate 63 has a cylindrical shape, and a reflector (graphite) 66 is disposed on the outer periphery. The reflector 66 has a cylindrical shape that conforms to the inner wall surface of the core barrel 61. A plurality of support structure parts (heat absorbing structure parts) 65 are disposed inside the reflector 66. The plurality of support structure parts 65 as the support structure 64 function as a structure that supports the upper support plate 62 with respect to the lower support plate 63.

[0035] The support structure 64 also functions as a heat absorbing structure. That is, the support structure 64 is formed of graphite, which is a member having a heat absorbing function. The support structure (heat absorbing structure) 64 is disposed at least on the upper surface of the lower support plate 63. The support structure 64 is disposed in the high-temperature space 83 between the upper support plate 62 and the lower support plate 63. The support structure 65 has an upper support part 65a, a lower support part 65b, and a support pillar 65c. The upper support part 65a is a block having a hexagonal column shape, and contacts and covers the lower surface of the upper support plate 62. The lower support part 65b is a block having a hexagonal column shape, and contacts and covers the upper surface of the lower support plate 63. The support pillar 65c is a pillar having a hexagonal column shape, and connects the upper support part 65a and the lower support part 65b. The outer diameter of the support pillar 65c is smaller than the outer diameter of the upper support portion 65a and the outer diameter of the lower support portion 65b.

[0036] The multiple support structures 65 are disposed in the high-temperature space 83 between the upper support plate 62 and the lower support plate 63. That is, the multiple support structures 65 are laid out closely together so that the multiple upper support parts 65a contact the lower surface part of the upper support plate 62, thereby covering the lower surface part of the upper support plate 62. Also, the multiple lower support parts 65b are laid out closely together so that they contact the upper surface part of the lower support plate 63, thereby covering the upper surface part of the lower support plate 63. Therefore, the upper support plate 62 is covered over almost the entire lower surface part with the multiple upper support parts 65a, and the lower support plate 63 is covered over almost the entire upper surface part with the multiple lower support parts 65b. In this case, since the upper end part of the inner tube 54 penetrates the lower support plate 63, the multiple lower support parts 65b are disposed on the upper surface part of the lower support plate 63 excluding the inner tube 54. Since the outer diameter of each of the support columns 65c is smaller than the outer diameter of the upper support portion 65a and the outer diameter of the lower support portion 65b, a flow passage is formed between the support columns 65c. This flow passage constitutes a part of the high-temperature coolant flow passage 81.

[0037] The support structure 64 as a heat absorbing structure is not limited to the above-mentioned configuration. The multiple support structure parts 65 constituting the support structure 64 may be composed of only the lower support part 65b and the support column 65c without the upper support part 65a. In this case, the lower support part 65b functions as a heat absorbing structure, but the support column 65c does not have to function as a heat absorbing structure. That is, it is sufficient that the heat absorbing structure covers at least the upper surface part of the lower support plate 63. The heat absorbing structure may be configured to cover a part of the upper surface part of the lower support plate 63.

[0038] In addition, in this embodiment, the support structure 64 also serves as the heat absorbing structure, but this is not limited to the configuration. The support structure and the heat absorbing structure may be provided separately. In other words, a plurality of pillars constituting the support structure 64 may be disposed between the upper support plate 62 and the lower support plate 63, and a heat absorbing structural plate constituting the heat absorbing structure may be disposed on the upper surface of the lower support plate 63.

[0039] The high-temperature coolant (solid line in FIG. 3) rises in the inner cylinder 54 (inlet section 23) and is supplied to a high-temperature space section 83 defined above the lower support plate 63. The high-temperature coolant supplied to the high-temperature space section 83 flows radially outward through the spaces between the support columns 65c of the multiple support structures 65, and rises through a flow path provided with the reflector 66, upper support plate 62, lower block 74, etc. At this time, since the lower surface of the upper support plate 62 and the upper surface of the lower support plate 63 are covered by the upper support section 65a and the lower support section 65b, the high-temperature coolant does not come into direct contact with them, and an increase in temperature is suppressed.

[0040] Meanwhile, the low-temperature coolant (dotted line in FIG. 3) flows down the flow path between the reactor vessel main body 51 and the core barrel 61, and is then supplied to a low-temperature space section 84 defined below the lower support plate 63. The low-temperature coolant supplied to the low-temperature space section 84 is discharged to the outside of the reactor vessel 21 from the outer casing 55 (outlet section 56). At this time, the lower surface of the lower support plate 63 is directly in contact with the low-temperature coolant, so that the lower support plate 63 is cooled and the increase in temperature is suppressed.

[0041] Therefore, the lower support plate 63 functions appropriately as a partition plate for separating the flow paths of the high-temperature coolant and the low-temperature coolant. The lower support plate 63 is prevented from coming into direct contact with the high-temperature coolant by the support structure 64, which also serves as a heat absorbing structure, so that the temperature difference between the upper and lower surfaces does not become large. As a result, the stress due to thermal deformation of the lower support plate 63 is reduced, and sufficient structural strength can be ensured. In other words, the lower support plate 63 can increase the allowable stress and increase the strength margin by reducing the heating temperature.

[0042] [Effects of this embodiment] The high-temperature gas reactor of the first embodiment comprises a hollow reactor vessel 21, a core 22 arranged inside the reactor vessel 21, a lower support plate 63 arranged horizontally at the bottom of the reactor vessel 21, a high-temperature coolant flow path 81 through which high-temperature coolant flows from the bottom of the reactor vessel 21 and above the lower support plate 63 toward the core 22, a low-temperature coolant flow path 82 through which low-temperature coolant flows downward from the side of the reactor vessel 21 and below the lower support plate 63, and a support structure (heat absorption structure) 64 arranged on the upper surface of the lower support plate 63.

[0043] In the high temperature gas reactor according to the first aspect, by arranging the support structure 64 functioning as a heat absorbing structure on the upper surface of the lower support plate 63, the high temperature coolant flowing through the high temperature coolant flow passage 81 is prevented from directly contacting the upper surface of the lower support plate 63, and the lower support plate 63 can reduce the temperature difference between the upper and lower surfaces. As a result, the lower support plate 63 is subjected to less stress due to thermal deformation, and sufficient structural strength can be ensured.

[0044] The high temperature gas reactor according to the second embodiment is the high temperature gas reactor according to the first embodiment, and further includes an upper support plate 62 arranged horizontally above the lower support plate 63 to support the core 22, and a support structure 64 arranged between the upper support plate 62 and the lower support plate 63. This prevents the high temperature coolant flowing through the high temperature coolant flow passage 81 from directly contacting the lower surface of the upper support plate 62, and reduces the temperature difference between the upper and lower surfaces of not only the lower support plate 63 but also the upper support plate 62.

[0045] The high temperature gas reactor according to the third embodiment is the high temperature gas reactor according to the second embodiment, and furthermore, the support structure 64 has an upper support part 65a covering the lower surface part of the upper support plate 62, a lower support part 65b covering the upper surface part of the lower support plate 63, and a support column 65c connecting the upper support part 65a and the lower support part 65b and forming a high temperature coolant flow path 81. With this, the upper support part 65a and the lower support part 65b function to reduce the temperature difference between the upper and lower surfaces of the upper support plate 62 and the lower support plate 63, and the high temperature coolant flow path 81 can be secured by the support column 65c.

[0046] The high temperature gas reactor according to the fourth aspect is the high temperature gas reactor according to any one of the first to third aspects, and further includes a double tube 53 consisting of an inner tube 54 and an outer tube 55 arranged at the bottom of the reactor vessel 21, and an upper end of the inner tube 54 penetrates a lower support plate 63 to form a high temperature coolant flow passage 81 inside the inner tube 54, and a low temperature coolant flow passage 82 between the inner tube 54 and the outer tube 55, and a support structure 64 is arranged on the upper surface of the lower support plate 63 excluding the inner tube 54. This allows the lower support plate 63 to properly separate the high temperature coolant flow passage 81 and the low temperature coolant flow passage 82.

[0047] The high temperature gas-cooled reactor according to the fifth aspect is the high temperature gas-cooled reactor according to any one of the first to fourth aspects, and further, the support structure 64 is made of graphite. This allows the graphite to effectively absorb the heat of the high temperature coolant.

[0048] The high temperature gas reactor system according to the sixth aspect includes a high temperature gas reactor 11 that extracts heat generated by nuclear fission to the outside by helium gas, an intermediate heat exchanger 12 that exchanges heat between the high temperature helium gas discharged from the high temperature gas reactor 11 and a heat medium, a gas turbine power generation system 13 that generates power by driving a turbine 34 with the high temperature helium gas discharged from the intermediate heat exchanger 12, and a regenerative heat exchanger 14 that exchanges heat between the high temperature helium gas discharged from the gas turbine power generation system 13 and low temperature helium gas. As a result, in the high temperature gas reactor 11, the lower support plate 63 can reduce the temperature difference between the upper and lower surfaces, and the lower support plate 63 is subjected to less stress due to thermal deformation, ensuring sufficient structural strength.

[0049] In the above embodiment, the inlet portion 23 for the high-temperature coolant with respect to the reactor vessel 21 is located at the lower part, and the outlet portion 24 for the high-temperature coolant with respect to the reactor vessel 21 is located at the lower part, but the inlet portion 23 and the outlet portion 24 are not limited to these positions. Also, the inlet portion 60 for the low-temperature coolant with respect to the reactor vessel 21 is located at the lower part, and the outlet portion 56 for the low-temperature coolant with respect to the reactor vessel 21 is located at the lower part, but the inlet portion 60 and the outlet portion 56 are not limited to these positions. That is, the positions of the inlet portions 23, 60 and the outlet portions 24, 56 may be any positions with respect to the reactor vessel 21 as long as the high-temperature coolant flow path 81 and the low-temperature coolant flow path 82 can be appropriately secured. [Explanation of symbols]

[0050] 10. High Temperature Gas-Cooled Reactor System 11 High-Temperature Gas-Cooled Reactors 12 Intermediate heat exchanger 13 Gas Turbine Power Generation System 14 Regenerative heat exchanger 21 Reactor vessel 22 Core 25 Pressure Vessels 26 Heat exchange section 32 Gas Turbine 33 Generator 34 Turbine 41 Pressure Vessels 42 Heat exchange section 43 Cooling section 51 Reactor vessel body 52 Reactor vessel lid 53 Double pipe 54 Inner cylinder 55 Outer cylinder 56 Exit section 57 Double pipe 58 Inner cylinder 59 Outer cylinder 60 Entrance 61 Core Barrel 62 Upper support plate 63 Lower support plate 64 Support structure (endothermic structure) 65 Support structure (heat absorption structure) 65a Upper support part 65b Lower support part 65c support column 66 Reflector 71 Fuel Block 72 Inner reflector block 73 Outer reflector block 74 Lower Block 75 Support Column 76 High Temperature Plenum Block 77 Control Rod Drive Mechanism 81 High temperature coolant flow path 82 Low temperature coolant flow path 83 High temperature space 84 Low temperature space section

Claims

1. A hollow reactor vessel; a reactor core disposed within the reactor vessel; a lower support plate horizontally disposed at a lower portion of the reactor vessel; a high-temperature coolant flow path through which high-temperature coolant flows from a lower portion of the reactor vessel toward the core, passing above the lower support plate; a cryogenic coolant flow passage through which cryogenic coolant flows downward from a side of the reactor vessel and below the lower support plate; a heat absorbing structure disposed on an upper surface of the lower support plate; A high-temperature gas reactor equipped with a

2. an upper support plate is disposed above the lower support plate and supports the core, the upper support plate being horizontally disposed, and the heat absorption structure is disposed between the upper support plate and the lower support plate; The high temperature gas reactor according to claim 1 .

3. the heat absorption structure includes an upper support portion covering a lower surface portion of the upper support plate, a lower support portion covering an upper surface portion of the lower support plate, and a support column connecting the upper support portion and the lower support portion and forming the high-temperature coolant flow path. The high temperature gas reactor according to claim 2.

4. A double tube consisting of an inner tube and an outer tube is disposed in the lower part of the reactor vessel, and an upper end of the inner tube penetrates the lower support plate, thereby forming the high-temperature coolant flow path inside the inner tube, and forming the low-temperature coolant flow path between the inner tube and the outer tube, and the heat absorption structure is disposed on the upper surface part of the lower support plate excluding the inner tube. The high temperature gas reactor according to claim 1 .

5. The heat absorbing structure is formed of graphite. The high temperature gas reactor according to claim 1 .

6. A high-temperature gas reactor uses helium gas to extract the heat generated by nuclear fission to the outside. an intermediate heat exchanger for exchanging heat between the high-temperature helium gas discharged from the high-temperature gas reactor and a heat medium; a gas turbine power generation system that generates power by driving a turbine with the high-temperature helium gas discharged from the intermediate heat exchanger; a regenerative heat exchanger for exchanging heat between high-temperature helium gas discharged from the gas turbine power generation system and low-temperature helium gas; A high-temperature gas-cooled reactor system comprising:

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