Reactor scram device and nuclear reactor

Abstract

To enable proper emergency shutdown of a nuclear reactor by rapidly supplying a neutron absorber into an interior of the nuclear reactor.SOLUTION: In a reactor scram device for performing an emergency shutdown of a nuclear reactor arranged in a horizontal orientation, the reactor scram device includes: a storage container; a neutron absorber stored in the storage container; a passage arranged along an inclined direction inclined with respect to a horizontal plane and configured to supply the neutron absorber stored in the storage container from an axial end portion of the nuclear reactor into an interior of the nuclear reactor; and an opening and closing body configured to be opened when the nuclear reactor transitions from a closed state of the passage to an abnormal state.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a nuclear reactor emergency shutdown device and a nuclear reactor. [Background technology]

[0002] A nuclear power generation system has a nuclear reactor that stores nuclear fuel. In the nuclear power generation system, a nuclear reaction occurs in the nuclear fuel in the reactor, and the generated heat is extracted to the outside to heat a cooling medium. The heated cooling medium drives a turbine to rotate, thereby generating electricity using a generator. An example of such a nuclear power generation system is described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-128324 Summary of the Invention [Problem to be solved by the invention]

[0004] A nuclear reactor is provided with an emergency shutdown device. In conventional nuclear reactors, nuclear fuel is annular, and the emergency shutdown device inserts neutron absorbing material into the nuclear fuel from one longitudinal end of the reactor. However, when the nuclear reactor is configured horizontally, the emergency shutdown device inserts the neutron absorbing material from the side of the reactor. Therefore, for example, if the neutron absorbing material is made up of multiple spheres, there is a problem in that it becomes difficult to supply the neutron absorbing material into the interior of the reactor due to its own weight.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a reactor emergency shutdown device and a reactor that can properly bring the reactor into emergency shutdown by quickly supplying neutron absorbers inside the reactor. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the reactor emergency shutdown device of the present disclosure is a reactor emergency shutdown device that brings a horizontally placed reactor to an emergency shutdown, and includes a storage container, a neutron absorber stored in the storage container, a passage that is arranged along an inclined direction inclined with respect to a horizontal plane and that can supply the neutron absorber stored in the storage container from the axial end of the reactor to the inside, and an opening / closing body that opens when the reactor transitions from a state in which the passage is closed to an abnormal state.

[0007] The nuclear reactor disclosed herein also includes a core formed by arranging a plurality of fuel blocks in a ring shape, a storage section disposed in a gap between the plurality of fuel blocks, and the reactor emergency shutdown device capable of supplying the neutron absorber of the storage container to the storage section. [Effects of the Invention]

[0008] According to the nuclear reactor emergency shutdown device and nuclear reactor of the present disclosure, the nuclear reactor can be properly brought to an emergency shutdown by quickly supplying neutron absorbers into the inside of the nuclear reactor. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a nuclear power generation system according to the first embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view showing the reactor unit of the first embodiment. [Figure 3] FIG. 3 is a vertical cross-sectional view of a reactor unit showing the reactor emergency shutdown device of the first embodiment. [Figure 4] FIG. 4 is a horizontal cross-sectional view of a nuclear reactor. [Figure 5] FIG. 5 is a vertical cross-sectional view of a nuclear reactor showing the operating state of the nuclear reactor emergency shutdown device. [Figure 6] FIG. 6 is a schematic diagram of a reactor unit showing a reactor emergency shutdown device according to the second embodiment. [Figure 7] FIG. 7 is a schematic diagram of a reactor unit showing a reactor emergency shutdown device according to the third embodiment. [Figure 8]FIG. 8 is a schematic diagram showing a first modified example of the neutron absorber. [Figure 9] FIG. 9 is a schematic diagram showing a second modified example of the neutron absorber. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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 configurations that combine the embodiments. Furthermore, the components in the embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the so-called equivalent range.

[0011] [First embodiment] <Nuclear power generation system> FIG. 1 is a schematic diagram showing a nuclear power generation system according to the first embodiment.

[0012] As shown in FIG. 1, the nuclear power generation system 100 includes a reactor unit 101, a coolant circulation path 102, a turbine 103, a compressor 104, a generator 105, a heat exchanger 106, and a cooler 107.

[0013] The reactor unit 101 has a reactor vessel 111, a reactor 112, and a heat conduction section 113. The reactor vessel 111 houses the reactor 112 inside. The reactor vessel 111 houses the reactor 112 in a sealed state. The reactor vessel 111 is provided with an opening and closing section, such as a lid, so that the reactor 112 placed inside can be stored or removed. The reactor vessel 111 can maintain a sealed state even when a nuclear reaction occurs in the reactor 112 and the inside becomes hot and high pressure. The reactor vessel 111 is made of a material with thermal insulation properties.

[0014] The reactor 112 stores nuclear fuel. The reactor 112 causes a nuclear reaction in the nuclear fuel, generating heat. The heat conduction unit 113 extracts the heat generated in the reactor 112 to the outside. Details of the reactor vessel 111, the reactor 112, and the heat conduction unit 113 will be described later.

[0015] The coolant circulation path 102 is a path for circulating the coolant. The coolant circulation path 102 connects the reactor unit 101 to the turbine 103, heat exchanger 106, cooler 107, compressor 104, and heat exchanger 106 in this order in the flow direction of the coolant, and is then connected back to the reactor unit 101. The high-temperature coolant extracted from the reactor unit 101 flows through the coolant circulation path 102, passes through the turbine 103, heat exchanger 106, cooler 107, compressor 104, and heat exchanger 106 in this order, and returns to the reactor unit 101.

[0016] The turbine 103 and the compressor 104 are connected by a connecting shaft 108 and are rotatable integrally. The compressor 104 is connected to a generator 105 by a connecting shaft 109, and the driving torque of the turbine 103 and the compressor 104 is transmitted to the generator 105. The turbine 103 is driven to rotate by the cooling medium heated by the reactor unit 101 and transmits the driving torque to the compressor 104. The compressor 104 is driven to rotate by the driving torque transmitted from the turbine 103 via the connecting shaft 108, and compresses the cooling medium cooled by the cooler 107. The generator 105 is driven by the driving torque transmitted from the compressor 104 via the connecting shaft 109 to generate electricity.

[0017] The heat exchanger 106 exchanges heat between the cooling medium that has been heated by the reactor unit 101 and then driven the turbine 103 and the cooling medium that has driven the compressor 104 .

[0018] The cooler 107 cools the cooling medium that has been heat exchanged by the heat exchanger 106 after driving the turbine 103. The cooler 107 cools the cooling medium by exchanging heat between the cooling medium flowing through the cooling medium circulation path 102 and a secondary cooling medium.

[0019] Heat generated by the reaction of nuclear fuel in the reactor 112 is extracted via the heat conduction unit 113. That is, the heat conduction unit 113 heats the cooling medium using the heat from the reactor 112 and causes the high-temperature cooling medium to flow through the cooling medium circulation path 102. The cooling medium flowing through the cooling medium circulation path 102 is supplied to the turbine 103.

[0020] The turbine 103 is driven to rotate by the cooling medium flowing through the cooling medium circulation path 102, and transmits the driving rotation force to the compressor 104. The cooling medium that has driven the turbine 103 flows through the heat exchanger 106 to the cooler 107 and is cooled. The cooling medium cooled by the cooler 107 is supplied to the compressor 104. The compressor 104 is driven to rotate by the driving rotation force transmitted from the turbine 103 via the connecting shaft 108, and compresses the cooling medium supplied from the cooler 107.

[0021] At this time, the generator 105 is driven by the driving torque transmitted from the compressor 104 via the connecting shaft 109 to generate electricity.

[0022] The cooling medium that has driven the compressor 104 is supplied to the heat exchanger 106. The heat exchanger 106 exchanges heat between the cooling medium that has driven the turbine 103 and the cooling medium that has driven the compressor 104. That is, the heat exchanger 106 heats the low-temperature cooling medium that has driven the compressor 104 with the high-temperature cooling medium that has driven the turbine 103.

[0023] The cooling medium heated by the heat exchanger 106 is then returned to the reactor 112 .

[0024] The nuclear power generation system 100 extracts heat from a nuclear reactor 112 using a cooling medium through a heat conduction section 113, drives a turbine 103 with the high-temperature, high-pressure cooling medium, and generates electricity using a generator 105.

[0025] <Reactor Unit> FIG. 2 is a vertical cross-sectional view showing the reactor unit of the first embodiment, FIG. 3 is a vertical cross-sectional view of the reactor unit showing the reactor emergency shutdown device of the first embodiment, and FIG. 4 is a horizontal cross-sectional view showing the reactor.

[0026] 2 to 4, the reactor unit 101 has a reactor vessel 111, a reactor 112, and a heat conduction section 113. The reactor 112 is housed inside the reactor vessel 111, and is provided with the heat conduction section 113. The heat conduction section 113 extracts heat generated in the reactor 112 to the outside.

[0027] <Reactor> The reactor 112 has a core 11, a reflector section 12, a heat conductor (heat conduction section 113) 13, a reactivity control device 14, and an emergency stop device 15. The reactor 112 has a cylindrical shape and is arranged horizontally. That is, the reactor 112 is arranged horizontally so that the central axis O is aligned horizontally.

[0028] <Reactor Core> As shown in FIGS. 2 and 4 , the core 11 is formed to have an overall polygonal prism shape (a hexagonal prism shape in this embodiment) centered on the central axis O. The core 11 has a plurality of fuel blocks 21 (six in this embodiment). Note that, although six or more fuel blocks 21 are preferred, the number is not limited. The fuel blocks 21 are nuclear fuel and have the same shape. The core 11 has a plurality of fuel blocks 21 arranged in the circumferential direction, forming a ring shape that is long in the axial direction (the direction along the central axis O). That is, the core 11 has a polygonal (hexagonal) outer shape, and the plurality of fuel blocks 21 each have a triangular outer shape. However, the shape of the core 11 is not limited to a hexagonal shape and may be a polygonal or circular shape.

[0029] The core 11 has a first space 22 in the center where the central axis O is located. The first space 22 has a cylindrical shape. The core 11 also has a plurality of (six in this embodiment) second spaces (gaps) 23a, 23b provided between the plurality of fuel blocks 21. The second spaces 23a, 23b each have the same rectangular parallelepiped shape. The second spaces 23a and the second spaces 23b may have the same shape or different shapes. The second spaces 23a, 23b are arranged radially from the outer periphery of the first space 22. That is, the second spaces 23a, 23b are arranged along the radial direction of the core 11 and are long in the axial and radial directions (directions perpendicular to the central axis O) and short in the circumferential direction (width direction).

[0030] Although not shown, the core 11 (fuel block 21) includes nuclear fuel (radioactive material) and a support body. The support body is disposed throughout the core 11. The support body has a plurality of holes formed along the axial direction. The holes have, for example, a cylindrical shape. The support body may include a moderator. Examples of the moderator that can be used include graphene, graphite, etc. The nuclear fuel body is disposed in the holes of the support body. The nuclear fuel body has a cylindrical shape corresponding to the shape of the holes of the support body. The nuclear fuel body may have a rod shape that is continuous in the axial direction, or a pellet shape that is discontinuous in the axial direction. The nuclear fuel body may use uranium (e.g., uranium-235), plutonium (e.g., plutonium-239, plutonium-241), thorium, etc. as a fissionable material.

[0031] <Reflector part> The reflector section 12 is arranged to surround the reactor core 11. The reflector section 12 is made of a metal block or graphite-based material, and prevents radiation from leaking to the outside by reflecting radiation (neutrons) emitted from the nuclear fuel that makes up the reactor core 11. The reflector section 12 is sometimes called a reflector depending on the neutron scattering and neutron absorption capabilities of the material used.

[0032] The reflector section 12 has a body 31, a bottom 32, and a lid 33. The body 31 is cylindrical and disposed radially outside the core 11. That is, the body 31 surrounds and covers the outer periphery of the core 11. The bottom 32 is disk-shaped and disposed on one axial side of the body 31. That is, the bottom 32 covers and closes the lower part of the core 11. The lid 33 is disk-shaped and disposed on the other axial side of the body 31. That is, the lid 33 covers and closes the upper part of the core 11. When the reflector section 12 accommodates the core 11 inside, it is preferable to fill the sealed interior with an inert gas such as nitriding gas in order to prevent oxidation inside.

[0033] <Thermal conductor> The thermal conductor 13 constitutes the thermal conduction section 113. That is, the thermal conductor 13 conducts heat generated in the reactor core 11 to the heat transfer tubes 41. The thermal conductor 13 is arranged so as to penetrate the reactor core 11 in the axial direction. One longitudinal end of the thermal conductor 13 penetrates the lid section 33 of the reflector section 12 and extends to the outside. The thermal conductor 13 conducts heat generated by the nuclear reaction of the nuclear fuel in the reactor core 11 to the outside of the reflector section 12.

[0034] The thermal conductor 13 has, for example, a heat transfer tube 41. The heat transfer tube 41 is filled with a cooling medium (for example, carbon dioxide) and allows the cooling medium to flow. The heat transfer tube 41 is, for example, U-shaped and is arranged inside the reactor core 11, with one end and the other end penetrating the reflector part 12 (lid part 33) and extending to the outside. The cooling medium is supplied from one end of the heat transfer tube 41, flows inside the reactor core 11, and is then discharged to the outside from the other end of the heat transfer tube 41. At this time, the cooling medium is heated by the heat generated by the nuclear reaction of the nuclear fuel in the reactor core 11 and extracts the heat to the outside.

[0035] The core 11 (fuel block 21) may be configured by stacking a plurality of plate-shaped fuel plates in the axial direction. The reflector section 12 may be configured by stacking a plurality of plate-shaped shield plates in the axial direction. In this case, a ring-shaped shield plate is arranged on the outer periphery of the ring-shaped fuel plate. A plurality of ring-shaped fuel plates and shield plates are then arranged in the plate thickness direction.

[0036] Furthermore, the heat conduction unit 113 may be provided by stacking multiple plate-shaped heat conduction plates in the axial direction. In this case, the ring-shaped fuel plates and shield plates are alternately stacked in the plate thickness direction with the ring-shaped heat conduction plates. The heat conduction plates have an outer diameter larger than that of the shield plates, and extract heat generated by the nuclear reaction of the nuclear fuel in the reactor core 11 radially outward. The heat conduction plates may be made of, for example, titanium, nickel, copper, or graphite. Graphene, in particular, may be used as graphite. Graphene has a structure consisting of a continuous hexagonal lattice made of carbon atoms and their bonds. By aligning the direction of heat transfer along the continuous hexagonal lattice, heat transfer efficiency can be improved.

[0037] <Reactivity Control Device> The reactivity control device 14 is disposed in the reflector section 12. The reactivity control device 14 is disposed so as to surround the periphery of the reactor core 11. The reactivity control device 14 has a plurality of control drums (control sections) 51 (12 in this embodiment). However, the number of control drums 51 is not limited. The plurality of control drums 51 are disposed outside the reactor core 11 at intervals (preferably at equal intervals) in the circumferential direction. The plurality of control drums 51 are disposed facing the outside of the plurality of fuel blocks 21 that constitute the reactor core 11.

[0038] The control drum 51 has a cylindrical shape and is arranged along the axial direction of the core 11. The control drum 51 has approximately the same length as the core 11. The control drum 51 is rotatably supported by the reflector section 12. A connecting section 52 is connected to one axial end of the control drum 51. The connecting section 52 penetrates the lid section 33 of the reflector section 12, with one end connected to one end of the control drum 51 and the other end extending outside the reflector section 12. The drive section 53 is arranged outside the reactor 112. The other ends of the multiple connecters 52 are connected to the drive section 53. The drive section 53 can rotate the multiple control drums 51 via the multiple connecters 52.

[0039] The control drum 51 has a drum main body 54 and a neutron absorbing section 55. The control drum 51 is configured such that the neutron absorbing section 55 is provided on a portion of the drum main body 54 in the circumferential direction. The drum main body 54 can be made of, for example, graphene, and the neutron absorbing section 55 can be made of, for example, boron carbide (B4C). As the control drum 51 rotates, the circumferential position of the neutron absorbing section 55 relative to the drum main body 54 changes. That is, as the control drum 51 rotates, the neutron absorbing section 55 can move closer to or away from the reactor core 11. When the neutron absorbing section 55 approaches the reactor core 11, the reactivity of the nuclear fuel constituting the reactor core 11 decreases, and when the neutron absorbing section 55 moves away from the reactor core 11, the reactivity of the nuclear fuel increases. The reactivity control device 14 rotates the multiple control drums 51 to move the neutron absorbing section 55 toward or away from the core 11, thereby controlling the reactivity of the nuclear fuel in the core 11 and the temperature of the core 11. Here, the temperature of the core 11 is the average core temperature that is taken out to the outside of the reflector section 12 by the thermal conductor 13.

[0040] The reactivity control device 14 has a control device 56. The control device 56 is connected to a drive unit 53. The control device 56 can control the rotational positions of the multiple control drums 51 by driving and controlling the drive unit 53. The control device 56 is, for example, a computer, and is realized by an arithmetic processing device including a microprocessor such as a CPU (Central Processing Unit). The control device 56 can acquire the temperature of the core 11. The control device 56 controls the rotational positions of the multiple control drums 51 that constitute the reactivity control device 14, and moves the neutron absorbing unit 55 away from the core 11. This increases the reactivity of the core 11, and the reactor 112 starts operating. Meanwhile, the control device 56 controls the rotational position of the control drum 51, and moves the neutron absorbing unit 55 closer to the core 11. This decreases the reactivity of the core 11, and the reactor 112 stops operating.

[0041] <Emergency stop device> 3 and 4, when the temperature of the core 11 rises and reaches a predetermined temperature during operation of the reactor 112, the emergency stop device 15 is activated to shut down the reactor 112. In this case, the emergency stop device 15 is for emergency shutdown of the reactor 112, which is placed horizontally.

[0042] The reactor 112 has a container 70. The container 70 is disposed in a gap between the plurality of fuel blocks 21 that constitute the reactor core 11. The emergency stop device 15 is disposed vertically above the reactor 112, and is capable of supplying a neutron absorber 84, which will be described later, to the container 70 from the outside.

[0043] The accommodation section 70 has a first accommodation section 71 and a second accommodation section 72. However, the accommodation section 70 is not limited to the first accommodation section 71 and the second accommodation section 72, and may be provided, for example, on the surface side of the core 11 and the reflector section 12. The first accommodation section 71 is disposed inside the cylindrical core 11, i.e., in the gap at the center. The first accommodation section 71 has a hollow cylindrical shape and is disposed axially at the center of the core 11. Note that the first accommodation section 71 is not limited to a hollow cylindrical shape and may have any shape, such as a rectangular prism shape. The first accommodation section 71 has approximately the same length as the core 11. The second accommodation section 72 is disposed radially from the first accommodation section 71 toward the gaps between the multiple fuel blocks 21. The second accommodation section 72 has a hollow rectangular parallelepiped shape and is disposed in the gaps between the multiple circumferentially adjacent fuel blocks 21. The second accommodation section 72 has approximately the same length as the core 11.

[0044] The first containment section 71 is disposed in a gap in the center of the core 11, and the second containment section 72 is disposed in a gap between adjacent fuel blocks 21. A plurality of second containment sections 72 (three in this embodiment) are provided. The one first containment section 71 and the three second containment sections 72 are connected to one another. The first containment section 71 and the second containment section 72 are formed of a material with low neutron absorption performance. That is, the first containment section 71 and the second containment section 72 are formed of a material with neutron absorption performance at least lower than that of the neutron absorber 84. The first containment section 71 and the second containment section 72 are formed of a material, such as graphite, whose structural viability can be confirmed under high temperature and high pressure.

[0045] The core 11 has a first space 22 provided in the center, that is, inside the six fuel blocks 21. The first accommodation section 71 is arranged in the first space 22. The core 11 has six second spaces 23a, 23b provided in the circumferential gaps between the six fuel blocks 21. The three second spaces 23a and the three second spaces 23b are arranged alternately in the circumferential direction of the core 11. The three second accommodation sections 72 are arranged in one of the three second spaces 23a. In the other three second spaces 23b, a large number of heat transfer tubes 41 constituting the thermal conductor 13 are arranged.

[0046] That is, the second accommodation sections 72 arranged in the second space section 23a and the large number of heat transfer tubes 41 arranged in the second space section 23b are arranged alternately in the circumferential direction of the core 11. Note that the heat transfer tubes 41 are arranged not only in the second space section 23b but also in the plurality of cutouts formed to communicate with the second space section 23a. The heat transfer tubes 41 are also arranged at intervals in the circumferential direction outside the plurality of fuel blocks 21. That is, the plurality of heat transfer tubes 41 are arranged so as to surround the periphery of each fuel block 21.

[0047] The emergency stop device 15 has a storage container 81, a passage 82, an opening / closing body 83, and a neutron absorber 84. The storage container 81 is disposed above one side (left side in FIG. 3 ) in the axial direction (direction of the central axis O) of the reactor 112. Note that the storage container 81 is not limited to being disposed above one side in the axial direction of the reactor 112, but may be disposed on the other side in the axial direction of the reactor 112 or on both sides in the axial direction of the reactor 112. The storage container 81 has a hollow shape and stores a large number of neutron absorbers 84 inside. However, the shape of the storage container 81 is not limited.

[0048] The passage 82 connects the storage vessel 81 and the accommodation section 70. The passage 82 can supply the neutron absorber 84 stored in the storage vessel 81 from the axial end of the reactor 112 to the inside. There may be only one passage 82, or multiple passages 82 may be provided. The passage 82 preferably connects the storage vessel 81 to the vertical upper end of the accommodation section 70. For example, the passage 82 axially penetrates the bottom 32 of the reactor 112, and connects the storage vessel 81 to the top of the second accommodation section 72.

[0049] Furthermore, the passage 82 is arranged along an inclined direction inclined with respect to a horizontal plane. Here, the horizontal plane is parallel to the central axis O. The passage 82 has a linear shape. However, the passage 82 is not limited to a linear shape, and may have a bent shape bent downward or a curved shape curved downward. Furthermore, when the storage vessel 81 is arranged from one side or the other of the axial direction of the reactor 112 to one side or the other of a horizontal direction intersecting the axial direction of the reactor 112, the passage 82 may be inclined and may have a bent shape bent horizontally or a curved shape curved horizontally. In other words, it is preferable that the passage 82 has a bent shape or a curved shape that avoids peripheral equipment of the reactor 112.

[0050] The opening and closing body 83 is provided in the passage 82. However, one or more opening and closing bodies 83 may be provided at the upper end of the passage 82 on the storage vessel 81 side, at an intermediate portion of the passage 82, or at the lower end of the passage 82 on the reactor 112 side. The opening and closing body 83 is capable of opening and closing the passage 82. The opening and closing body 83 is opened when the reactor 112 transitions from a state in which the passage 82 is closed to an abnormal state. The abnormal state of the reactor 112 is a state in which the temperature of the reactor 112 rises above a predetermined temperature or the pressure of the reactor 112 rises above a predetermined pressure.

[0051] Specifically, the opening and closing device 83 is opened when the temperature of the reactor 112 rises from a state in which the passage 82 is closed and reaches a predetermined temperature. In other words, the opening and closing device 83 is opened when the temperature of the reactor 112 reaches a predetermined temperature in an emergency operation state from a temperature range from room temperature to a normal operation state. In this case, the opening and closing device 83 is made of a material that melts at a predetermined temperature or higher, such as a lead-copper alloy or a lead alloy.

[0052] Furthermore, the opening / closing device 83 is opened when the pressure in the reactor 112 increases from a state in which the passage 82 is closed and reaches a predetermined pressure. In other words, the opening / closing device 83 is opened when the pressure in the reactor 112 reaches a predetermined pressure in an emergency operation state from a pressure range from a room temperature state to a normal operation state. In this case, the opening / closing device 83 is configured to rupture and open when the pressure in the reactor 112 reaches or exceeds the predetermined pressure, for example. The opening / closing device 83 may also be configured to be biased in the closing direction by a biasing member such as a spring, and to be opened when the pressure in the reactor 112 reaches or exceeds the predetermined pressure.

[0053] Although the opening and closing device 83 is configured to open when the temperature of the reactor 112 reaches a predetermined temperature or when the pressure of the reactor 112 reaches a predetermined pressure, the present invention is not limited to this configuration. The opening and closing device 83 may be configured to open when either the temperature of the reactor 112 reaches a predetermined temperature or the pressure of the reactor 112 reaches a predetermined pressure occurs. Furthermore, the opening and closing device 83 may be configured to open when both the temperature of the reactor 112 reaches a predetermined temperature and the pressure of the reactor 112 reaches a predetermined pressure occur. Furthermore, the opening and closing device 83 may be configured to open when an abnormal phenomenon other than the temperature or pressure of the reactor 112 occurs.

[0054] The neutron absorber 84 is made of a material with higher neutron absorption performance than the accommodation section 70. The neutron absorber 84 is a plurality of granular bodies. Specifically, the neutron absorber 84 is spherical. For example, boron carbide (B4C) can be used for the neutron absorber 84. The spherical neutron absorber 84 has an outer diameter smaller than the inner diameter of the passage 82, the inner diameter of the first accommodation section 71, and the width of the second accommodation section 72. The neutron absorber 84 is stored in the accommodation container 81, and when the opening / closing body 83 is opened, the neutron absorber 84 is supplied into the accommodation section 70 through the passage 82. As a result, the first accommodation section 71 and the second accommodation section 72 that constitute the accommodation section 70 are filled with the neutron absorber 84.

[0055] When the opening / closing body 83 is closed and the neutron absorber 84 remains stored in the storage vessel 81 and is not supplied to the first storage section 71 and the second storage section 72, the reactivity of the nuclear fuel in the core 11 increases. On the other hand, when the opening / closing body 83 is open and the neutron absorber 84 stored in the storage vessel 81 is supplied from the passage 82 to the first storage section 71 and the second storage section 72 and filled therein, the reactivity of the nuclear fuel in the core 11 decreases.

[0056] It should be noted that the neutron absorber 84 is not limited to a plurality of granular bodies. The neutron absorber 84 may have any shape as long as it can be stored in the storage container 81 and supplied to the storage section 70 through the passage 82. For example, the neutron absorber 84 may have a cylindrical shape corresponding to the shape of the first storage section 71 or a rectangular parallelepiped shape corresponding to the shape of the second storage section 72.

[0057] <Nuclear reactor control method> FIG. 5 is a vertical cross-sectional view of a nuclear reactor showing the operating state of the nuclear reactor emergency shutdown device.

[0058] 1, 2, and 4, in the nuclear reactor 112, the control device 56 controls the rotational positions of the multiple control drums 51 that make up the reactivity control device 14 in accordance with the temperature of the reactor core 11. That is, by rotating the control drum 51, the neutron absorbing section 55 is moved away from the reactor core 11 to increase the reactivity of the reactor core 11, or by moving the neutron absorbing section 55 closer to the reactor core 11 to decrease the reactivity of the reactor core 11. Heat generated by the nuclear reaction of the nuclear fuel in the reactor core 11 is extracted to the outside of the reflector section 12 by the thermal conductor 13 (heat transfer tubes 41). The heat extracted to the outside of the reflector section 2 is transferred to the cooling medium by the heat transfer tubes 41, and the cooling medium rotates the turbine 103, causing the generator 105 to generate electricity.

[0059] 3 and 4, during operation of the reactor 112, the temperature of the core 11 is below a predetermined temperature, and therefore the emergency stop device 15 is in an inactive state. That is, in the emergency stop device 15, the opening / closing body 83 is closed, and the neutron absorber 84 remains stored in the storage vessel 81 and is not supplied to the first storage section 71 and the second storage section 72.

[0060] On the other hand, when the reactor 112 enters an emergency operation state (abnormal reactor state), the temperature and pressure of the core 11 rise. Then, when the temperature of the core 11 reaches a predetermined temperature or the pressure of the core 11 reaches a predetermined pressure, the emergency stop device 15 enters an activated state. That is, as shown in FIGS. 3 and 5 , the emergency stop device 15 opens the opening / closing body 83, and the neutron absorber 84 stored in the storage vessel 81 is supplied to the storage section 70 (the first storage section 71 and the second storage section 72) through the passage 82. In addition, the control device 56 rotates the control drum 51 to bring the neutron absorber 55 closer to the core 11.

[0061] At this time, a passage 82 connecting the storage container 81 and the accommodation unit 70 is inclined downward from the storage container 81 toward the accommodation unit 70. Therefore, the neutron absorber 84 in the storage container 81 is appropriately supplied to the accommodation unit 70 through the inclined passage 82 due to its own weight, and can be filled into the accommodation unit 70.

[0062] As a result, the core 11 has the first accommodation section 71 filled with neutron absorbers 84 located inside, the second accommodation sections 72 filled with neutron absorbers 84 located between the fuel blocks 21, and the neutron absorbing section 55 of the control drum 51 located outside. As a result, the reactivity of the nuclear fuel in the core 11 decreases, and the nuclear reactor 112 is brought to an emergency shutdown.

[0063] [Second embodiment] 6 is a schematic diagram of a reactor unit showing a reactor emergency shutdown device according to the second embodiment. Note that members having the same functions as those in the first embodiment described above are given the same reference numerals and detailed descriptions thereof will be omitted.

[0064] As shown in FIG. 6, the reactor unit 101A has a reactor vessel 111, a reactor 112, and a heat conduction section 113 (see FIG. 2). The reactor 112 has a core 11, a reflector section 12, a heat conductor 13 (see FIG. 2), a reactivity control device 14 (see FIG. 2), and an emergency stop device 15A. The reactor 112A has a cylindrical shape and is arranged horizontally. Here, the core 11, the reflector section 12, the heat conductor 13, and the reactivity control device 14 are the same as those in the first embodiment, and therefore, description thereof will be omitted.

[0065] The emergency stop device 15A has a storage container 81, a passage 82A, an opening / closing body 83, and a neutron absorber 84. The storage container 81, the opening / closing body 83, and the neutron absorber 84 are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0066] The passage 82A communicates between the storage vessel 81 and the storage section 70. The passage 82A can supply the neutron absorber 84 stored in the storage vessel 81 from the axial end of the reactor 112 to the inside. The passage 82A is arranged along an inclined direction inclined with respect to the horizontal plane. The passage 82A has a zigzag shape. That is, the passage 82A is configured by multiple straight sections 82a inclined in the vertical direction connected by bent sections 82b. However, the straight sections 82a of the passage 82A are not limited to a straight shape, and may be bent in the horizontal direction or curved in the horizontal direction. The bent sections 82b of the passage 82A may be curved sections.

[0067] When the reactor 112 enters an emergency operation state (abnormal reactor state), the temperature and pressure of the core 11 rise, and the temperature of the core 11 reaches a predetermined temperature or the pressure of the core 11 reaches a predetermined pressure, the emergency stop device 15A is activated. That is, the emergency stop device 15A opens the opening / closing body 83, and the neutron absorber 84 stored in the storage vessel 81 is supplied to the storage section 70 (the first storage section 71 and the second storage section 72) through the passage 82A.

[0068] At this time, the passage 82A connecting the storage container 81 and the accommodation unit 70 is inclined downward in a zigzag shape from the storage container 81 toward the accommodation unit 70. Therefore, the neutron absorber 84 in the storage container 81 is appropriately supplied to the accommodation unit 70 through the inclined passage 82A due to its own weight, and can be filled into the accommodation unit 70.

[0069] [Third embodiment] 7 is a schematic diagram of a reactor unit showing a reactor emergency shutdown device according to the third embodiment. Note that members having the same functions as those in the first embodiment described above are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0070] As shown in FIG. 7, the reactor unit 101B has a reactor vessel 111, a reactor 112, and a heat conduction section 113 (see FIG. 2). The reactor 112 has a core 11, a reflector section 12, a heat conductor 13 (see FIG. 2), a reactivity control device 14 (see FIG. 2), and an emergency stop device 15B. The reactor 112B has a cylindrical shape and is arranged horizontally. Here, the core 11, the reflector section 12, the heat conductor 13, and the reactivity control device 14 are the same as those in the first embodiment, and therefore, description thereof will be omitted.

[0071] The emergency stop device 15B has a storage container 81, a passage 82B, an opening / closing body 83, and a neutron absorber 84. The storage container 81, the opening / closing body 83, and the neutron absorber 84 are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0072] The passage 82B connects the storage vessel 81 and the storage section 70. The passage 82B can supply the neutron absorber 84 stored in the storage vessel 81 from the axial end of the reactor 112 to the inside. The passage 82B is arranged along an inclined direction inclined with respect to the horizontal plane. The passage 82B has a spiral shape centered on the vertical axis. The number of revolutions of the passage 82B is set appropriately.

[0073] When the reactor 112 enters an emergency operation state (abnormal reactor state), the temperature and pressure of the core 11 rise, and the temperature of the core 11 reaches a predetermined temperature or the pressure of the core 11 reaches a predetermined pressure, the emergency stop device 15B is activated. That is, the emergency stop device 15B opens the opening / closing body 83, and the neutron absorber 84 stored in the storage vessel 81 is supplied to the storage section 70 (the first storage section 71 and the second storage section 72) through the passage 82B.

[0074] At this time, the passage 82B connecting the storage container 81 and the accommodation unit 70 is inclined downward in a spiral shape from the storage container 81 toward the accommodation unit 70. Therefore, the neutron absorber 84 in the storage container 81 is appropriately supplied to the accommodation unit 70 through the inclined passage 82B due to its own weight, and can be filled into the accommodation unit 70.

[0075] <Modifications of neutron absorbers> In each embodiment, the neutron absorber 84 is spherical and made of, for example, boron carbide, but is not limited to this composite. Fig. 8 is a schematic diagram showing a first modified example of the neutron absorber.

[0076] As shown in Fig. 8, the neutron absorber 84A is configured by connecting spheres 91 to each other with connectors 92. In this case, the spheres 91 and connectors 92 are rotatably connected by shafts 93. Any of the spheres 91, connectors 92, and shafts 93 uses a material having a neutron absorbing function (for example, boron carbide). Therefore, as shown in Figs. 3 and 8, the neutron absorber 84A is appropriately supplied from the storage vessel 81 to the reactor 112 by the spheres 91 rolling through the passages 82.

[0077] FIG. 9 is a schematic diagram showing a second modified example of the neutron absorber.

[0078] As shown in Fig. 9, the neutron absorber 84B is configured by connecting spheres 91 to each other with connectors 94. In this case, the spheres 91 are rotatably connected to the connectors 94 by spherical bearings. Either the spheres 91 or the connectors 94 use a material that has a neutron absorbing function (for example, boron carbide). Therefore, as shown in Figs. 3 and 9, the neutron absorber 84B is appropriately supplied from the storage vessel 81 to the reactor 112 by the spheres 91 rolling through the passage 82.

[0079] [Effects of this embodiment] The reactor emergency shutdown device of the first aspect is an emergency shutdown device 15, 15A, 15B that brings a horizontally arranged reactor 112 to an emergency shutdown, and comprises a storage container 81, neutron absorbers 84, 84A, 84B stored in the storage container 81, passages 82, 82A, 82B that are arranged along an inclined direction inclined with respect to the horizontal plane and that can supply the neutron absorbers 84, 84A, 84B stored in the storage container 81 to the inside from the axial end of the reactor 112, and an opening / closing body 83 that opens when the reactor 112 transitions from a state in which the passages 82, 82A, 82B are closed to an abnormal state.

[0080] According to the reactor of the first aspect, the passages 82, 82A, 82B that communicate between the storage vessel 81 and the inside of the reactor 112 are arranged along the inclined direction, so that in the event of an emergency in the reactor 112, the neutron absorbers 84, 84A, 84B can be appropriately supplied by their own weight into the inside of the reactor 112. Therefore, the reactor 112 can be appropriately brought to an emergency shutdown.

[0081] The reactor emergency shutdown device according to the second aspect is the reactor emergency shutdown device according to the first aspect, and further, the opening and closing device 83 is opened when the temperature of the reactor 112 rises from a state in which the passages 82, 82A, 82B are closed and reaches a predetermined temperature. As a result, the opening and closing device 83 is opened by the temperature rise of the reactor 112, and the neutron absorbers 84, 84A, 84B of the storage vessel 81 can be appropriately supplied into the reactor 112 by their own weight.

[0082] The reactor emergency shutdown device according to the third aspect is the reactor emergency shutdown device according to the first aspect, and further, the opening and closing device 83 is opened when the pressure in the reactor 112 increases from a state in which the passages 82, 82A, 82B are closed and reaches a predetermined pressure. As a result, the opening and closing device 83 is opened by the pressure increase in the reactor 112, and the neutron absorbers 84, 84A, 84B of the storage vessel 81 can be appropriately supplied into the reactor 112 by their own weight.

[0083] The reactor emergency shutdown device according to the fourth aspect is the reactor emergency shutdown device according to any one of the first to third aspects, further comprising: a storage vessel 81 disposed above at least one side in the axial direction of the reactor 112; and passages 82, 82A, 82B disposed along the inclined direction, with upper ends communicating with the storage vessel 81 and lower ends communicating with the core 11 of the reactor 112. This allows the neutron absorbers 84, 84A, 84B to be appropriately filled into the core 11 provided along the axial direction of the reactor 112.

[0084] A reactor emergency shutdown device according to a fifth aspect is the reactor emergency shutdown device according to any one of the first to fourth aspects, and further includes a reactor 112 having a core 11 configured by arranging a plurality of fuel blocks 21 in an annular shape, and a storage section 70 arranged in a gap between the plurality of fuel blocks 21, and the lower ends of the passages 82, 82A, 82B communicate with the storage section 70. This allows neutron absorbers 84, 83A, 84B to be appropriately supplied to the core 11 by the passages 82, 82A, 82B.

[0085] A reactor emergency shutdown device according to a sixth aspect is the reactor emergency shutdown device according to any one of the first to fifth aspects, and further, the passage 82 has a linear shape or a curved shape that curves downward in the vertical direction. This allows the neutron absorbers 84, 84A, 84B to be smoothly supplied into the reactor 112 through the passage 82 by their own weight.

[0086] A reactor emergency shutdown device according to a seventh aspect is the reactor emergency shutdown device according to any one of the first to sixth aspects, and further, the passage 82A has a zigzag shape that is bent or curved horizontally in a plan view. This allows the passage 82A to be appropriately positioned so as to avoid peripheral equipment of the reactor 112.

[0087] The reactor emergency shutdown device according to an eighth aspect is the reactor emergency shutdown device according to any one of the first to sixth aspects, and further, the passage 82B has a spiral shape centered on a vertical axis. This allows the passage 82B to be appropriately positioned so as to avoid peripheral equipment of the reactor 112.

[0088] The nuclear reactor according to the ninth aspect includes a core 11 configured by arranging a plurality of fuel blocks in an annular shape, a storage section 70 arranged in a gap between the plurality of fuel blocks, and emergency stop devices (reactor emergency stop devices) 15, 15A, 15B capable of supplying neutron absorbers 84, 83A, 54B of a storage container 81 to the storage section 70. As a result, by quickly supplying neutron absorbers 84, 84A, 84B into the nuclear reactor 112, the nuclear reactor 112 can be properly brought to an emergency shutdown. [Explanation of symbols]

[0089] 11 Reactor Core 12 Reflector section 13 Thermal Conductors 14 Reactivity Control Device 15,15A,15B Emergency stop device (reactor emergency stop device) 21 Fuel Block 22 First space part 23a, 23b Second space (gap) 31 Torso 32 Bottom 33 Lid 41 Heat transfer tube 51 Control drum 52 Connecting part 53 Drive unit 54 Drum body 55 Neutron absorber 56 Control device 70 Storage section 71 First storage section 72 Second storage section 81 Storage container 82,82A,82B aisle 83 Opening and closing body 84, 84A, 84B Neutron absorber 100 Nuclear Power Systems 101, 101A, 101B reactor units 102 Coolant circulation path 103 Turbine 104 Compressor 105 Generator 106 Heat exchanger 107 Cooler 108,109 Connecting shaft 111 Reactor Vessel 112 Nuclear reactor 113 Heat Conduction Section

Claims

1. In a nuclear reactor emergency shutdown device for emergency shutdown of a horizontally placed nuclear reactor, A storage container; a neutron absorber housed in the housing; a passage through which the neutron absorber, which is arranged along an inclined direction with respect to a horizontal plane and is housed in the container, can be supplied from an end portion in the axial direction of the reactor to the inside of the container; an opening / closing body that opens when the reactor transitions from a state in which the passage is closed to an abnormal state; A nuclear reactor emergency shutdown device.

2. the opening / closing body is opened when the temperature of the reactor rises from a state in which the passage is closed and reaches a predetermined temperature. The nuclear reactor emergency shutdown device according to claim 1.

3. the opening / closing body is opened when the pressure in the reactor increases from a state in which the passage is closed to a predetermined pressure. The nuclear reactor emergency shutdown device according to claim 1.

4. the storage vessel is disposed above at least one side of the reactor in the axial direction, the passage is disposed along the inclined direction, and an upper end of the passage is connected to the storage vessel and a lower end of the passage is connected to the core of the reactor. The nuclear reactor emergency shutdown device according to claim 1.

5. the reactor has a core formed by arranging a plurality of fuel blocks in an annular manner, and a storage section disposed in a gap between the plurality of fuel blocks, and a lower end of the passage is in communication with the storage section; 5. The nuclear reactor emergency shutdown device according to claim 4.

6. The passage has a straight shape or a curved shape that curves downward in the vertical direction. The nuclear reactor emergency shutdown device according to claim 1.

7. The passage has a zigzag shape that is bent or curved horizontally in a plan view. The nuclear reactor emergency shutdown device according to claim 1.

8. The passage has a spiral shape centered on a vertical axis. The nuclear reactor emergency shutdown device according to claim 1.

9. a reactor core configured by arranging a plurality of fuel blocks in an annular manner; a receiving portion disposed in a gap between the plurality of fuel blocks; the reactor emergency shutdown device according to claim 1, which is capable of supplying the neutron absorber of the storage container to the storage section; A nuclear reactor equipped with:

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