Nuclear power generation system and nuclear power generation method

Abstract

To maintain a high shielding property to radiation and generate power.SOLUTION: The present invention includes: a nuclear reactor having a reactor core fuel and a nuclear reactor container for covering a region around the reactor core fuel and shielding the space in which the reactor core fuel is located and shielding radiation; a heat conduction part located in the nuclear reactor container, the heat conduction part propagating heat of the reactor core fuel by solid heat conduction; refrigerant circulation means inserted in the nuclear reactor container partially and located out of the nuclear reactor container partially, the refrigerant circulation means having a pipe in which a refrigerant flows and circulating a refrigerant which exchanges heat between the heat conduction part and the refrigerant; a turbine rotated by the refrigerant circulated by the refrigerant circulation means; and a generator integrally rotated with the turbine.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a nuclear power generation system and a nuclear power generation method. [Background technology]

[0002] In a nuclear power generation system that uses nuclear fuel and generates electricity using the heat of nuclear reactions, the heat generated in the reactor is recovered in a primary cooling system in which primary coolant circulates between the reactor and a secondary cooling system, heat is exchanged between the primary coolant and secondary coolant, and a turbine installed in the secondary cooling system is rotated using the energy of the secondary coolant to generate electricity.

[0003] In contrast, Patent Document 1 describes a power generation system having a reactor including a core fuel and a reactor vessel that surrounds the core fuel, shields the space where the core fuel is located, and shields from radiation, and a heat conduction part that is arranged in at least a part of the reactor vessel and transfers heat inside the reactor vessel to the outside by solid-state heat conduction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-165836 Summary of the Invention [Problem to be solved by the invention]

[0005] Nuclear power generation systems generate radiation in their nuclear reactors. By using solid-state thermal conduction as in Patent Document 1, it is possible to improve radiation shielding performance. Nuclear power generation systems are required to be able to generate power while maintaining high radiation shielding performance even with other configurations.

[0006] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a nuclear power generation system and a nuclear reactor power generation method that can generate power while maintaining high radiation shielding properties. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a nuclear power generation system according to one aspect of the present disclosure includes a reactor including a core fuel and a reactor vessel that surrounds the core fuel, shields the space where the core fuel is located, and shields from radiation; a heat conduction section that is disposed inside the reactor vessel and transfers heat from the core fuel by solid-state heat conduction; a refrigerant circulation means that is partially inserted inside the reactor vessel and partially disposed outside the reactor vessel and has piping through which a refrigerant flows, and that circulates the refrigerant that exchanges heat between the heat conduction section and the refrigerant; a turbine that is rotated by the refrigerant circulated by the refrigerant circulation means; and a generator that rotates integrally with the turbine.

[0008] In order to achieve the above-mentioned object, a nuclear power generation method according to one aspect of the present disclosure is a nuclear reactor including a core fuel and a reactor vessel that surrounds the core fuel, shields the space where the core fuel is located, and shields from radiation, in which a nuclear reaction is caused in the core fuel to generate heat, a heat conduction part located inside the reactor vessel transfers the heat of the core fuel by solid-state thermal conduction, and a refrigerant circulation means that is partly inserted inside the reactor vessel and partly located outside the reactor vessel and has piping through which a refrigerant flows exchanges heat between the heat conduction part and the refrigerant, heats the refrigerant with the heat of the reactor, and rotates it with the refrigerant circulating in the refrigerant circulation means, the refrigerant being carbon dioxide. [Effects of the Invention]

[0009] According to the disclosure, it is possible to obtain the effect of generating electricity while maintaining high radiation shielding properties. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing the general configuration of a nuclear power generation system according to this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a schematic configuration of a nuclear power generation system according to another embodiment. [Figure 3] FIG. 3 is an enlarged cross-sectional view showing a cross-sectional structure of a part of the nuclear reactor. [Figure 4] FIG. 4 is a schematic diagram showing the structure near the inner wall of the reactor vessel. [Figure 5] FIG. 5 is a schematic diagram showing the structure near the inner wall of another example of a reactor vessel. [Figure 6] FIG. 6 is a schematic diagram showing the structure near the inner wall of another example of a reactor vessel. [Figure 7] FIG. 7 is a schematic diagram showing the structure near the inner wall of another example of a reactor vessel. [Figure 8] FIG. 8 is a schematic diagram showing a schematic configuration of a nuclear power generation system according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to these embodiments. Furthermore, the components in the following embodiments include those that are easily replaceable by those skilled in the art, or those that are substantially identical.

[0012] Fig. 1 is a schematic diagram showing the general configuration of a nuclear power generation system according to this embodiment. As shown in Fig. 1, the nuclear power generation system 10 includes a reactor unit 12 and a power generation unit 13. The power generation unit 13 includes a heat exchanger 14, a refrigerant circulation means 16, a turbine 18, a generator 20, a cooler 22, a compressor 24, and a reheat exchanger 26.

[0013] The reactor unit 12 includes a reactor 30 and a heat conduction section 32. The reactor 30 includes a reactor vessel 40, a fuel core 42, and a control unit 44. The reactor vessel 40 stores the fuel core 42 therein. The reactor vessel 40 stores the fuel core 42 in a sealed state. The reactor vessel 40 has an opening / closing section so that the fuel core 42 placed therein can be inserted and removed. The opening / closing section is, for example, a lid. The reactor vessel 40 can maintain a sealed state even when a nuclear reaction occurs therein and the inside becomes hot and high pressure. The reactor vessel 40 is also formed of a material with neutron shielding properties and is formed with a thickness that prevents neutrons generated inside from leaking to the outside. The reactor vessel 40 is formed of, for example, concrete. The reactor vessel 40 may contain highly shielding elements such as boron.

[0014] The core fuel 42 includes a plurality of fuel holding plates 43. A plurality of nuclear fuels are arranged inside the fuel holding plates 43. The fuel holding plates 43 are made of a material that transfers heat generated by the nuclear fuel. Graphite, silicon carbide, etc. can be used for the fuel holding plates 43. The core fuel 42 generates reaction heat as the nuclear fuel undergoes a nuclear reaction.

[0015] The control unit 44 has movable shielding materials between the core fuel 42. The shielding materials are so-called control rods that have the function of blocking radiation and suppressing nuclear reactions. The reactor 30 controls the reaction of the core fuel 42 by moving the control unit 44 and adjusting the position of the shielding materials.

[0016] As shown in FIG. 1 , the heat conductive portion 32 is disposed inside the reactor vessel 40 and is in contact with the fuel holding plate 43. In this embodiment, the heat conductive portion 32 is in the form of a plurality of plates, which are alternately stacked with the fuel holding plate 43. The heat conductive portion 32 is a plate having an outer shape larger than the fuel holding plate 43, and protrudes into an area where the fuel holding plate 43 is not disposed. Here, the heat conductive portion 32 may be made of, for example, titanium, nickel, copper, graphite, or graphene. In order to increase the efficiency of heat transfer to the protruding portion, the heat conductive portion 32 preferably uses graphene oriented in a direction that facilitates heat conduction along the surface of the plate. The heat conductive portion 32 transfers heat by solid-state thermal conduction. In other words, the heat conductive portion 32 transfers heat without using a heat medium (fluid). Specifically, the heat conductive portion 32 transfers heat generated in the core fuel 42 to the power generation unit 13 by solid-state thermal conduction.

[0017] The reactor unit 12 has the above configuration, and a nuclear reaction occurs in the core fuel 42 inside the reactor 30, generating reaction heat. The generated heat is accumulated inside the reactor vessel 40, causing the interior to become hot. In the reactor unit 12, a portion of the heat generated in the reactor 30 is transferred to the heat conduction section 32. The heat conduction section 32 heats the refrigerant flowing in the refrigerant circulation means 16 of the power generation unit 13. Here, carbon dioxide (CO2) is preferably used as the refrigerant.

[0018] The coolant circulation means 16 includes a circulation path 34 that circulates the coolant outside the reactor vessel 40 and a heat exchanger 36 that circulates the coolant inside the reactor vessel 40. The circulation path 34 and the heat exchanger 36 form a closed loop. The circulation path 34 circulates the coolant outside the reactor vessel 40 and is connected to the turbine 18, the cooler 22, the compressor 24, and the reheat exchanger 26. The heat exchanger 36 is inserted into the reactor vessel 40 and disposed inside. Both ends of the heat exchanger 36 are exposed to the outside of the reactor vessel 40 and connected to the circulation path 34. The heat exchanger 36 is a pipe through which the coolant flows and is in contact with the region of the heat conduction portion 32 that is not in contact with the core fuel 42. In other words, the heat exchanger 36 is in contact with the portion of the heat conduction portion 32 that protrudes beyond the core fuel 42. The heat exchanger 36 exchanges heat with the heat conduction portion 32 to heat the coolant. In this embodiment, the heat exchange section 36 and the heat conduction section 32 form the heat exchanger 14 .

[0019] The refrigerant flowing through the refrigerant circulation means 16 is supplied to the heat exchange section 36. The nuclear reactor power generation system 10 exchanges heat between the heat conduction section 32 and the refrigerant supplied from the refrigerant circulation means 16. The heat exchanger of this embodiment is composed of the heat conduction section 32 and the heat exchange section 36 of the refrigerant circulation means 16. The heat exchanger recovers heat from the heat conduction section 32 using the refrigerant flowing through the refrigerant circulation means 16. In other words, the refrigerant is heated in the heat conduction section 32. The heat medium heated in the heat exchange section 36 flows through the turbine 18, the cooler 22, the compressor 24, and the reheat exchanger 26 in this order. The refrigerant that has passed through the reheat exchanger 26 is supplied to the heat exchange section 36 again. In this manner, the refrigerant is circulated through the refrigerant circulation means 16.

[0020] The refrigerant that has passed through the heat exchanger 14 flows into the turbine 18. The turbine 18 is rotated by the energy of the heated refrigerant. In other words, the turbine 18 converts the energy of the refrigerant into rotational energy and absorbs energy from the refrigerant. The generator 20 is connected to the turbine 18 and rotates integrally with the turbine 18. The generator 20 generates electricity by rotating together with the turbine 18.

[0021] The cooler 22 cools the refrigerant that has passed through the turbine 18. The cooler 22 is a chiller, or a condenser in the case of temporarily liquefying the refrigerant. The compressor 24 is a pump that pressurizes the refrigerant. reheat The exchanger 26 exchanges heat between the refrigerant that has passed through the turbine 18 and the refrigerant that has passed through the compressor 24 . reheat The exchanger 26 heats the refrigerant that has passed through the compressor 24 with the refrigerant that has passed through the turbine 18. reheat The exchanger 26 exchanges heat between the refrigerant before being cooled by the cooler 22 and the refrigerant after being cooled by the cooler 22, and recovers the heat discarded by the cooler 22 using the refrigerant before being supplied to the reactor unit 12.

[0022] In the nuclear power generation system 10, heat generated by the reaction of nuclear fuel in the nuclear reactor 12 is transferred to the refrigerant in the heat exchange unit 36 ​​via the heat transfer unit 32, and the heat from the heat transfer unit 32 heats the refrigerant flowing through the refrigerant circulation means 16. In other words, the refrigerant absorbs the heat transferred via the heat transfer unit 32. As a result, the heat generated in the nuclear reactor 12 is transferred via solid-state thermal conduction by the heat transfer unit 32 and recovered by the refrigerant. After being compressed by the compressor 24, the refrigerant is heated as it passes through the heat transfer unit 32, and the compressed energy is used to rotate the turbine 18. The refrigerant is then cooled to a reference state in the cooler 22 and supplied to the compressor 24 again.

[0023] As described above, the nuclear reactor power generation unit 10 transfers the heat of the nuclear reactor 30 to the coolant that serves as the medium for rotating the turbine 18 using the heat conduction section 32 that transfers heat by solid-state thermal conduction.

[0024] The nuclear reactor power generation unit 10 uses carbon dioxide as a refrigerant, thereby preventing contamination of the refrigerant even when the refrigerant is circulated inside the nuclear reactor 30. This reduces the risk of contamination of the medium that rotates the turbine 18. Furthermore, by providing a heat conduction section 32 that transfers heat by solid thermal conduction, the heat conduction section 32 can shield against neutron radiation.

[0025] Fig. 2 is a schematic diagram showing the general configuration of a nuclear power generation system according to another embodiment. Fig. 3 is an enlarged cross-sectional view showing the cross-sectional structure of a portion of a nuclear reactor. Fig. 4 is a schematic diagram showing the structure near the inner wall of a reactor vessel. The nuclear power generation system 10a shown in Fig. 2 includes a cooling mechanism 60 in addition to the configuration of the nuclear power generation system 10 shown in Fig. 1. Below, the cooling mechanism 60, which is a configuration unique to the nuclear power generation system 10a, will be described, and detailed description of the configuration similar to that of the nuclear power generation system 10 will be omitted.

[0026] The nuclear power generation system 10a includes a reactor unit 12a, a power generation unit 13, and a cooling mechanism 60. In the reactor unit 12a, an in-reactor piping 65 of a cooling piping 62 of the cooling mechanism 60 is arranged inside the reactor 30a.

[0027] The cooling mechanism 60 includes a cooling pipe (cooling flow path) 62 and a control valve 64. The cooling pipe 62 is a pipe connected at both ends to the refrigerant circulation means 16, and a portion thereof is inserted inside the reactor vessel 40. The in-reactor pipe 65 is a portion of the cooling pipe 62 that is disposed inside the reactor vessel 40. The cooling pipe 62 is located downstream of the compressor 24, reheat The cooling pipe 62 is connected to the refrigerant circulation means 16 at a branching point 66 located upstream of the exchanger 26. reheat The cooling pipe 62 is downstream of the heat exchanger 26 and is connected to the refrigerant circulation means 16 at a junction 68 located upstream of the position where it is inserted into the reactor vessel 40 (upstream of the heat exchanger 36). The refrigerant flows into the cooling pipe 62 from a branching point 66, passes through the in-reactor piping 65, reaches the junction 68, and flows into the refrigerant circulation means 16.

[0028] 3 and 4, the in-reactor piping 65 branches into a plurality of parallel pipes inside the reactor vessel 40. Each pipe of the in-reactor piping 65 is arranged in contact with the inner wall 70 of the reactor vessel. The in-reactor piping 65 is arranged closer to the reactor vessel 40 than the pipe 50 of the heat exchanger 36. In the example shown in FIG. 4, the in-reactor piping 65 is arranged at predetermined intervals in the circumferential direction.

[0029] The nuclear power generation system 10a is provided with a cooling mechanism 60 and configured so that the refrigerant (the refrigerant after passing through the compressor 24) in the in-reactor piping 65 passes near the inner wall 70 of the reactor vessel 40, thereby making it possible to suppress a rise in temperature of the inner wall 70 of the reactor vessel 40. This makes it possible to increase the durability of the reactor vessel 40 and further increase the safety of the nuclear power generation system 10a. Furthermore, by adopting a structure in which cooling is performed by the cooling mechanism 60, it is possible to increase the options for materials and structures that can be used for the reactor vessel 40.

[0030] Furthermore, the nuclear power generation system 10a uses a cooling mechanism 60 that uses a refrigerant used in the power generation unit 13 to recover heat from the reactor unit 12, thereby enabling the heat generated in the reactor unit 12 to be used for power generation, thereby increasing power generation efficiency.

[0031] The cooling mechanism 60 of this embodiment preferably detects the temperature of the reactor vessel and, based on the detected temperature, controls at least one of opening and closing and the degree of opening of the control valve 64. By controlling the control valve 64, for example, when the reactor vessel 40 is at or below a predetermined temperature, no coolant is circulated through the cooling mechanism 60, and when the temperature exceeds the predetermined temperature, the coolant is circulated through the cooling mechanism 60, thereby cooling the reactor vessel 40.

[0032] Although the cooling mechanism 60 of this embodiment is provided with a control valve 64, the refrigerant may be allowed to constantly flow through the cooling pipes 62 and the in-core pipes 65 without providing the control valve 64. This makes it possible to suppress a temperature rise in the reactor vessel 40 without performing control. In this case, it is preferable that the amount of refrigerant flowing into the cooling mechanism 60 be a small proportion of the total circulation amount, for example, about 2%. Cooling can be achieved by flowing 2% of the total refrigerant into the cooling mechanism 60.

[0033] Fig. 5 is a schematic diagram showing the structure of the vicinity of the inner wall of another example of a reactor vessel. In the reactor 30b shown in Fig. 5, the in-reactor piping 65a is arranged so that it is in contact with each other. As a result, the entire surface of the inner wall 70 is covered with the in-reactor piping 65a, and the temperature rise of the inner wall 70 of the reactor vessel 40 can be further suppressed.

[0034] Fig. 6 is a schematic diagram showing the structure near the inner wall of a reactor vessel in another example. In the reactor 30c shown in Fig. 6, the in-reactor piping 65c has a trapezoidal cross section, and adjacent surfaces are arranged in a position where they overlap when viewed from the center of the reactor vessel 30c. As a result, the entire surface of the inner wall 70 is covered with the in-reactor piping 65c, and the temperature rise of the inner wall 70 of the reactor vessel 40 can be further suppressed.

[0035] 7 is a schematic diagram showing the structure of the vicinity of the inner wall of a reactor vessel in another example. In a reactor 30b shown in FIG. 5, in-reactor pipes 65a are arranged in contact with each other. In a reactor 30d shown in FIG. 7, the cross section of the in-reactor pipes 65d is triangular, and the end of the side in contact with the inner wall 70 is arranged at a position overlapping with the adjacent in-reactor pipes 65d. As a result, the entire surface of the inner wall 70 is covered with the in-reactor pipes 65d, and the temperature rise of the inner wall 70 of the reactor vessel 40 can be further suppressed.

[0036] 5 to 7, the shape of the in-furnace piping can be various, and the cross section can be various shapes such as a circle, a perfect circle, an ellipse, a polygon (e.g., a triangle, a rectangle), etc. Furthermore, by making the in-furnace piping contact or overlap each other, the temperature rise of the inner wall 70 can be further suppressed.

[0037] Furthermore, in this embodiment, the in-reactor piping is configured to be in contact with the inner wall 70 of the reactor vessel 40, but the present invention is not limited to this. The in-reactor piping may be inserted inside the reactor vessel 40. In other words, the reactor vessel 40 may be cooled by the in-reactor piping, thereby suppressing a temperature rise in the inner wall 70 of the reactor vessel 40.

[0038] Fig. 8 is a schematic diagram showing the general configuration of a nuclear power generation system according to another embodiment. In the nuclear power generation system 10e shown in Fig. 8, the refrigerant circulating means 16 is configured such that the confluence 69 of the cooling pipes 62 of the cooling mechanism 60a is located downstream of the turbine 18 and upstream of the reheat exchanger 26.

[0039] In the cooling mechanism 60a, by locating the confluence 69 downstream of the turbine 18, the pressure difference between the refrigerant at the branching point 66 and the confluence 69 increases, and the flow rate in the in-core piping 65 can be increased. This makes it possible to more efficiently reduce the temperature of the inner wall 70 of the reactor vessel 40.

[0040] The cooling mechanism 60a cannot use the recovered energy for power generation because it joins after passing through the turbine 18. Therefore, it is preferable that the cooling mechanism 60a be operated in an emergency or when an abnormality occurs, in which the temperature of the inner wall of the reactor vessel 40 exceeds a predetermined temperature.

[0041] The cooling mechanism may also be provided with pipes connected to each of the confluence portions 68 and 69, and a control valve may be provided in the pipes to switch the position where the refrigerants confluence.

[0042] Furthermore, the positions of the branching portion and the merging portion of the cooling mechanism are not limited to those in the above embodiment. The branching portion may be located downstream of the compressor 24 and upstream of the heat exchange portion 32. The merging portion may be located downstream of the branching portion and upstream of the compressor 24 (or the cooler 22 if one is provided). For example, reheat When the exchanger 26 is arranged in two stages, the upstream reheat exchanger and downstream reheat A branching section and a junction section may be provided between the exchanger and the gas supply section. [Explanation of symbols]

[0043] 10 Nuclear Power Systems 12 Reactor Unit 13 Power Generation Unit 14 Heat exchanger 16 Refrigerant circulation means 18 Turbine 20. Generator 22 Chiller 24 Pump (compressor) 26 reheat exchanger 30 nuclear reactor 32 Heat conduction section 34 Circulation Route 36 Heat exchange section 40 Reactor vessel 42 Core fuel 43 Fuel holding plate 44 Control Unit 60 Cooling mechanism 62 Cooling piping 64 Control valve 65 Furnace piping 66 Branch 68, 69 Junction

Claims

1. a nuclear reactor including a fuel core and a reactor vessel that surrounds the fuel core, shields a space in which the fuel core is located, and shields against radiation; a heat conduction part disposed inside the reactor vessel and transmitting heat of the core fuel by solid heat conduction; a coolant circulation means, a part of which is inserted inside the reactor vessel and a part of which is arranged outside the reactor vessel, having a pipe through which a coolant flows, and circulating the coolant that exchanges heat between the heat conduction portion and the coolant; a turbine rotated by the refrigerant circulating in the refrigerant circulation means; a generator that rotates integrally with the turbine, a compressor disposed in the refrigerant circulation means for compressing the refrigerant that has passed through the turbine; A nuclear power generation system comprising a cooling mechanism having a cooling pipe that branches off from the refrigerant circulation means downstream of the compressor and upstream of the heat conduction unit, cools an inner wall of the reactor vessel inside the reactor vessel, and joins the refrigerant circulation means downstream of the branching position.

2. 2. The nuclear power generation system according to claim 1, wherein the refrigerant is carbon dioxide.

3. 3. The nuclear power generation system according to claim 1, wherein the cooling pipe joins the refrigerant circulating means at a position upstream of a heat exchanger.

4. 3. The nuclear power generation system according to claim 1, wherein the cooling pipe joins the coolant circulation means at a position downstream of the turbine.

5. a cooler disposed in the refrigerant circulation means downstream of the turbine and upstream of the compressor, for cooling the refrigerant; a reheat exchanger that exchanges heat between the refrigerant in the refrigerant circulation means downstream of the compressor and upstream of the heat conduction portion and the refrigerant in the refrigerant circulation means downstream of the turbine and upstream of the cooler, 5. The nuclear power generation system according to claim 1, wherein the cooling pipe branches off from the refrigerant circulation means between the compressor and the reheat exchanger.

6. 6. The nuclear power generation system according to claim 1, wherein the cooling pipe has a cross section that is one of a perfect circle, an ellipse, and a polygon.

7. 7. The nuclear power generation system according to claim 1, wherein the cooling pipe is in contact with an inner wall of the reactor vessel.

8. 7. The nuclear power generation system according to claim 1, wherein the cooling pipe is inserted inside the reactor vessel.

9. 9. The nuclear power generation system according to claim 1, wherein the cooling mechanism includes a flow rate adjusting valve disposed in a cooling pipe.

10. In a nuclear reactor including a fuel core and a reactor vessel that surrounds the fuel core, shields the space where the fuel core is located, and shields from radiation, a nuclear reaction is generated in the fuel core to generate heat, a heat conduction section disposed inside the reactor vessel, which transfers heat from the core fuel by solid-state heat conduction; a coolant circulation means, a part of which is inserted inside the reactor vessel and a part of which is arranged outside the reactor vessel, having a pipe through which a coolant flows, for heat exchange between the heat conduction portion and the coolant, and for heating the coolant with the heat of the reactor; The rotation is caused by the refrigerant circulating in the refrigerant circulation means, cooling an inner wall of the reactor vessel inside the reactor vessel with a cooling pipe that is arranged in the refrigerant circulation means, that branches off from the refrigerant circulation means downstream of a compressor that compresses the refrigerant that has passed through a turbine rotated by the refrigerant circulating in the refrigerant circulation means and upstream of the heat conduction section, and that joins the refrigerant circulation means downstream of the branching position; The nuclear power generation method, wherein the refrigerant is carbon dioxide.

Images