Nuclear reactor and method of controlling the same

Abstract

To enable reactivity control using a simplified configuration.SOLUTION: A nuclear reactor 201 is provided, comprising: a core section 11 not including nuclear fuel; and a plurality of fuel drums (fuel units) 251 arranged so as to surround the core section 11, and each having a neutron absorbing part 55 for absorbing neutrons and a nuclear fuel part 56, where positions of the neutron absorbing part 55 and the nuclear fuel part 56 are adjustable relative to the core section 11.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to nuclear reactors and methods of controlling nuclear reactors. [Background technology]

[0002] For example, Patent Document 1 describes a nuclear reactor in which a control mechanism is arranged around a core containing fuel. The control mechanism has a neutron absorber attached to a part of the outer periphery formed in a drum shape, and by rotating the control mechanism, it brings the neutron absorber closer to the fuel to reduce the reactivity of the core, and by moving it away from the fuel, it increases the reactivity of the core. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7426323 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, in a configuration such as the nuclear reactor described in Patent Document 1, it is desired to control the reactivity with a simpler configuration.

[0005] The present disclosure is intended to solve the above-mentioned problems, and has an object to provide a nuclear reactor and a method for controlling a nuclear reactor that are capable of performing reactivity control with a simplified configuration. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a nuclear reactor according to one embodiment of the present disclosure includes a central portion that does not contain nuclear fuel, and a plurality of fuel portions that are arranged surrounding the central portion and have neutron absorbers that absorb neutrons and nuclear fuel portions, and are arranged so that the positions of the neutron absorbers and the nuclear fuel portions relative to the central portion can be adjusted.

[0007] In order to achieve the above-mentioned object, a method for controlling a nuclear reactor according to one aspect of the present disclosure controls the reactivity of nuclear fuel in a nuclear reactor including a plurality of fuel sections, each having a neutron absorbing section that absorbs neutrons and a nuclear fuel section that is arranged surrounding a central section that does not contain nuclear fuel, by adjusting the positions of the neutron absorbing section and the nuclear fuel section relative to the central section using the fuel section. [Effects of the Invention]

[0008] The present disclosure enables reactivity control with a simplified configuration. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a nuclear power generation system using a nuclear reactor according to an embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view of the nuclear reactor according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional plan view of the nuclear reactor according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional plan view showing the operation of the nuclear reactor according to the embodiment. [Figure 5] FIG. 5 is a flowchart of a method for controlling a nuclear reactor according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Note that 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.

[0011] FIG. 1 is a schematic diagram of a nuclear power generation system using a nuclear reactor according to an embodiment.

[0012] [Nuclear power generation system] As shown in FIG. 1, the nuclear power generation system 100 includes a nuclear reactor 201, a refrigerant circulation path 102, a turbine 103, a compressor 104, a generator 105, a heat exchanger 106, and a cooler 107.

[0013] The reactor 201 has a reactor vessel 111, a reactor core 112, and a heat conduction section 113. The reactor vessel 111 houses the reactor core 112 inside. The reactor vessel 111 houses the reactor core 112 in a sealed state. The reactor vessel 111 is provided with an opening / closing section, such as a lid, so that the reactor core 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 core 112 and the inside becomes hot and high pressure. The reactor vessel 111 is made of a material with thermal insulation properties. The reactor core 112 contains nuclear fuel, and generates heat by causing a nuclear reaction with the nuclear fuel. The heat conduction section 113 extracts the heat generated in the reactor core 112 to the outside. Details of the reactor 201 will be described later.

[0014] The refrigerant circulation path 102 is a path for circulating a cooling medium (also referred to as a refrigerant). The refrigerant circulation path 102 connects the reactor 201 to the turbine 103, heat exchanger 106, cooler 107, compressor 104, and heat exchanger 106 in this order in the flow direction of the cooling medium, and is then connected back to the reactor 201. The high-temperature cooling medium extracted from the reactor 201 flows through the refrigerant 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 201.

[0015] 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 201, 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.

[0016] The heat exchanger 106 exchanges heat between the cooling medium that has been heated by the nuclear reactor 201 and then driven the turbine 103 and the cooling medium that has driven the compressor 104 .

[0017] The cooler 107 cools the cooling medium that has been subjected to heat exchange in 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 refrigerant circulation path 102 and a secondary cooling medium.

[0018] In the nuclear reactor 201, heat generated by the nuclear reaction of the nuclear fuel in the core 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 core 112 and causes the high-temperature cooling medium to flow through the refrigerant circulation path 102. The cooling medium flowing through the refrigerant circulation path 102 is supplied to the turbine 103.

[0019] The turbine 103 is driven to rotate by the cooling medium flowing through the refrigerant 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.

[0020] 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.

[0021] 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.

[0022] The cooling medium heated by the heat exchanger 106 is then returned to the heat conducting portion 113 of the reactor 201 .

[0023] In this way, the nuclear power generation system 100 extracts heat from the reactor core 112 using a cooling medium through the heat conduction section 113, drives the turbine 103 with the high-temperature, high-pressure cooling medium, and generates electricity using the generator 105.

[0024] [Nuclear reactor] Fig. 2 is a vertical cross-sectional view of the nuclear reactor according to the embodiment. Fig. 3 is a plan cross-sectional view (BB cross-sectional view of Fig. 2) of the nuclear reactor according to the embodiment. Fig. 4 is a plan cross-sectional view showing the operation of the nuclear reactor according to the embodiment.

[0025] The nuclear reactor 201 includes a reactor vessel 111 , a reactor core 112 , and a heat conduction section 113 .

[0026] The reactor vessel 111 houses a reactor core 112 therein, the details of which will be described later.

[0027] The reactor core section 112 has a central portion 211, a reflector section 12, heat transfer tubes 41 constituting a heat conduction section 113, and a reactivity control device 14. The reactor core section 112 has a cylindrical outer shape and is arranged vertically with its central axis O aligned vertically.

[0028] In this embodiment, the central portion 211 is formed so that its overall outer shape forms a hexagonal prism centered on the central axis O. The central portion 211 is formed, for example, by arranging a plurality of (at least three or more) blocks 221 of the same shape along the circumferential direction around the central axis O, forming a hexagonal prism shape that is long in the axial direction along the central axis O. The shape of the central portion 211 is not limited to a hexagonal prism shape, and may be a polygonal prism shape or a cylindrical shape.

[0029] The block 221 is configured as a support containing a heat-transmitting moderator. The moderator may be, for example, highly oriented graphite containing graphene. In the nuclear reactor 201, the block 221 does not contain nuclear fuel.

[0030] The central portion 211 has a first accommodating portion 22 and a second accommodating portion 23. The first accommodating portion 22 and the second accommodating portion 23 accommodate the heat transfer tubes 41. The first accommodating portion 22 is formed in an annular shape around the central axis O in the central portion of the central portion 211. In the embodiment, the first accommodating portion 22 is formed in an annular shape having the same shape as the outer shape of the central portion 211, and is formed so as to penetrate the central portion 211 (block 221) in the axial direction. The second accommodating portion 23 is formed in an annular shape around the central axis O in the outer periphery of the central portion 211. In the embodiment, the second accommodating portion 23 is formed in an annular shape having the same shape as the outer shape of the central portion 211, and is formed continuously in the axial direction along the outer periphery of the central portion 211 (block 221) between the reflector portion 12.

[0031] The central portion 211 has a first space portion 24 and a second space portion 25. The first space portion 24 is formed in the center of the first containment portion 22, penetrating the central portion 211 (block 221) along the central axis O. The second space portion 25 is formed between each block 21 so as to extend in the radial direction centered on the central axis O, and is formed continuously along the axial direction. The first space portion 24 and the second space portion 25 constitute part of an emergency stop device. The emergency stop device is activated when the core temperature rises and reaches a predetermined temperature during operation of the reactor 201, and shuts down the reactor 201 by supplying neutron absorbers to the first space portion 24 and the second space portion 25 by a neutron absorber supply device (not shown).

[0032] The reflector section 12 is disposed to cover the periphery of the central section 211 and constitutes the outer periphery of the reactor core section 112. The reflector section 12 is made up of a graphite block and a metal block, and suppresses leakage of radiation to the outside of the reactor core section 112 by reflecting radiation (neutrons) irradiated from the nuclear fuel.

[0033] The reflector section 12 has a body 31 and wall bodies 32 and 33. The body 31 has a cylindrical shape that surrounds the central axis O and is continuous in the axial direction, and is disposed radially outside the center part 211. That is, the body 31 covers the outer periphery of the center part 211 so as to surround it. The wall body 32 has a disk shape centered on the central axis O, and is disposed on one axial side of the body 31. That is, the wall body 32 closes one axial side of the body 31 and covers one axial end of the center part 211. The wall body 33 has a disk shape centered on the central axis O, and is disposed on the other axial side of the body 31. That is, the wall body 33 closes the other axial side of the body 31 and covers the other axial end of the center part 211.

[0034] The reactor vessel 111 has a body section 34, support plates 35 and 36, and lids 37 and 38. The body section 34 has a cylindrical shape that surrounds the central axis O and is continuous in the axial direction, and is disposed radially outside the core section 112. That is, the body section 34 covers the outer periphery of the core section 112 so as to surround it. The support plate 35 has a disk shape centered on the central axis O and is disposed on one axial side of the body section 34. That is, the support plate 35 closes one axial side of the body section 34 and covers one end of the core section 112. The support plate 36 has a disk shape centered on the central axis O and is disposed on the other axial side of the body section 34. That is, the support plate 36 closes the other axial side and covers the other end of the core section 112. The lid 37 has a hemispherical shape and is disposed on one axial side of the body section 34. That is, the lid 37 is attached so as to cover the support plate 35. The lid 38 has a hemispherical shape and is disposed on the other axial side of the body 34. That is, the lid 38 is attached so as to cover the support plate 36. When the reactor vessel 111 accommodates the core 112 inside, it is preferable to fill the inside of the reactor vessel 111, which has a sealed structure, with an inert gas such as helium gas in order to prevent oxidation inside the vessel.

[0035] The heat conduction section 113 conducts heat generated in the core section 112 to the outside of the reactor vessel 111. The heat conduction section 113 includes a heat transfer tube 41, an inlet side manifold 42, an outlet side manifold 43, an inlet pipe 44, and an outlet pipe 45.

[0036] The heat transfer tubes 41 are made of a material such as copper, which has a relatively high heat transfer coefficient. As shown in FIG. 2, the heat transfer tubes 41 are arranged to penetrate the core section 112 in the axial direction. In this embodiment, a large number of the heat transfer tubes 41 are inserted into the first accommodation section 22 and the second accommodation section 23. That is, as shown in FIG. 2, a large number of the heat transfer tubes 41 are arranged in the core section 112 so as to surround the central axis O. A large number of the heat transfer tubes 41 are arranged in the central and outer peripheral sections of the center section 11 along the outer shape (e.g., hexagonal shape) of the center section 11, centered on the central axis O. One end of the heat transfer tube 41 penetrates the wall 32 and the support plate 35, and the other end penetrates the wall 33 and the support plate 36, extending axially to the outside of the core section 112. In this way, the heat transfer tubes 41 are arranged in the central and outer peripheral sections of the center section 211 so as to surround the central axis O in the core section 112.

[0037] The inlet-side manifold 42 is disposed outside the support plate 35. One end of each heat transfer tube 41 is connected to the inlet-side manifold 42. The outlet-side manifold 43 is disposed outside the support plate 36. The other end of each heat transfer tube 41 is connected to the outlet-side manifold 43. One end of the inlet pipe 44 is connected to the inlet-side manifold 42, and the other end passes through the lid 37 to extend to the outside and is connected to the refrigerant circulation path 102. The outlet pipe 45 has one end connected to the outlet-side manifold 43, and the other end passes through the lid 38 to extend to the outside and is connected to the refrigerant circulation path 102.

[0038] In the heat conduction section 113, the cooling medium is supplied from the inlet pipe 44 through the refrigerant circulation path 102 to the inlet side manifold 42, and flows from the inlet side manifold 42 to each heat transfer tube 41. In the heat conduction section 113, the cooling medium flows through each heat transfer tube 41 and is sent to the outlet side manifold 43, and from the outlet side manifold 43 through the outlet pipe 45 to the refrigerant circulation path 102. At this time, in the heat conduction section 113, the cooling medium is heated by the heat generated by the nuclear reaction of the nuclear fuel as it flows inside the multiple heat transfer tubes 41, and the heat is extracted to the outside.

[0039] The reactivity control device 14 includes a fuel drum (fuel section) 251 , a drive section 53 , and a control device 57 .

[0040] A plurality of fuel drums 251 (six in this embodiment) are arranged across the center 211 and the reflector section 12, centered around the central axis O, so as to surround the center 211. The number of fuel drums 251 is not limited. The fuel drums 251 are arranged so that a portion of each fuel drum 251 fits within the outer periphery of the center 211. When the outer shape of the center 211 is a polygonal column, the fuel drums 251 are arranged so that a portion of each fuel drum 251 fits within the flat portion that forms the outer periphery of the polygonal column. The plurality of fuel drums 251 are configured as cylindrical structures, and are formed in a cylindrical shape that extends along the axial direction of the center 211. The fuel drums 251 have approximately the same axial length as the center 211. The fuel drums 251 are supported rotatably about an axis 52 that extends along the central axis O relative to the center 211 and the reflector section 12.

[0041] The fuel drum 251 has a drum main body 54, a neutron absorbing section 55, and a nuclear fuel section 56. The fuel drum 251 is configured such that the neutron absorbing section 55 and the nuclear fuel section 56 are provided at a portion of the circumferential direction of the drum main body 54. The neutron absorbing section 55 and the nuclear fuel section 56 are provided at different positions in the rotation direction of the fuel drum 251.

[0042] The drum body 54 is disposed at the center within the circular area of ​​the cross section (see FIGS. 3 and 4) of the cylindrical fuel drum 251. The drum body 54 can be made of, for example, graphite.

[0043] The neutron absorbing section 55 is disposed in a relatively narrow crescent-shaped region offset to one side within the circular area of ​​the cross section of the cylindrical fuel drum 251 (see FIGS. 3 and 4). The neutron absorbing section 55 may be made of, for example, boron carbide (B4C), which absorbs neutrons. The neutron absorbing section 55 has higher neutron absorption performance than the drum main body 54 and the reflector section 12.

[0044] The nuclear fuel section 56 is arranged in a crescent-shaped region offset to the opposite side of the neutron absorbing section 55 within the circular area of ​​the cross section (see FIGS. 3 and 4) of the cylindrical fuel drum 251. The nuclear fuel section 56 is arranged in a region that is thicker in the radial direction and wider in the circumferential direction than the neutron absorbing section 55 within the circular area of ​​the cross section (see FIGS. 3 and 4) of the cylindrical fuel drum 251. The nuclear fuel section 56 can use, as a fissionable material, highly oriented graphite containing graphene or the like in addition to uranium (e.g., uranium-235), plutonium (e.g., plutonium-239, plutonium-241), thorium, or the like.

[0045] As the drum body 54 of the fuel drum 251 rotates, the circumferential positions of the neutron absorbing portion 55 and the nuclear fuel portion 56 change. That is, as the fuel drum 251 rotates, the neutron absorbing portion 55 and the nuclear fuel portion 56 move closer to or farther away from the center portion 211 (central axis O). As the fuel drum 251 rotates, as shown in FIG. 3, if the neutron absorbing portion 55 moves closer to the center portion 211 and the nuclear fuel portion 56 moves farther away from the center portion 211, the reactivity of the nuclear fuel portion 56 decreases. On the other hand, as the fuel drum 251 rotates, as shown in FIG. 4, if the neutron absorbing portion 55 moves farther away from the center portion 211 and the nuclear fuel portion 56 moves closer to the nuclear fuel in the center portion 211 and enters and gathers within the range of the center portion 211, the reactivity of the nuclear fuel portion 56 increases. In this way, the fuel drum 251 can control the reactivity of the nuclear fuel section 56 by rotating the neutron absorber section 55 and the nuclear fuel section 56, and can control the core temperature. The core temperature is the average core temperature that is extracted to the outside of the reflector section 12 by the heat transfer tubes 41.

[0046] The drive unit 53 is a rotation drive mechanism that is connected to the shaft 52 of the fuel drum 251 and rotates the fuel drum 251 via the shaft 52 .

[0047] The control device 57 controls the driving of the drive unit 53 to change the rotational positions of the multiple fuel drums 251. The control device 57 is, for example, a computer, and is realized by an arithmetic processing device including a microprocessor such as a CPU (Central Processing Unit).

[0048] FIG. 5 is a flowchart of a method for controlling a nuclear reactor according to an embodiment.

[0049] The controller 57 of the reactivity control device 14 controls the rotational position of the fuel drum 251 in accordance with the core temperature.

[0050] 5 shows a general operation procedure of the nuclear reactor 201. First, in step S1, the control device 57, based on an operation command for the nuclear reactor 201, rotates the fuel drum 251 within a range of less than 180° from the shutdown state shown in FIG. 3, moving the neutron absorbing section 55 away from the center (central axis O) and moving the nuclear fuel section 56 closer to the center. As a result, the reactivity of the nuclear fuel section 56 increases as described above, the core temperature rises, and the nuclear reactor 201 starts operation.

[0051] In step S2, the control device 57 proceeds to step S3 based on the command to add reactivity (step S2: Yes). In step S3, the control device 57 rotates the fuel drum 251 from the state in step S1, moving the neutron absorber 55 further away from the center (central axis O) and bringing the nuclear fuel section 56 closer to the center. This increases the reactivity of the nuclear fuel section 56. In step S2, the control device 57 maintains the rotational position of the fuel drum 251 until it receives a command to add reactivity (step S2: No). Note that FIG. 4 shows the rotational position of the fuel drum 251 at which the reactivity is highest (a 180° rotation position from FIG. 3).

[0052] In step S4, the control device 57 proceeds to step S5 based on the command for reactivity suppression (step S4: Yes). In step S5, the control device 57 rotates the fuel drum 251 from the state of step S3, for example, to move the neutron absorber 55 closer to the center (central axis O) and move the nuclear fuel section 56 away from the center. This reduces the reactivity of the nuclear fuel section 56. In step S4, the control device 57 maintains the rotational position of the fuel drum 251 until it receives a command for reactivity suppression (step S4: No). Note that in step S4, if it receives a command to shut down operation, which is one of the reactivity suppression methods, the control device 57 rotates the fuel drum 251 to the state of shut down operation shown in FIG. 3.

[0053] The nuclear reactor 201 of the above-described embodiment is characterized by including a central portion 211 that does not contain nuclear fuel, and a plurality of fuel drums (fuel portions) 251 that are arranged to surround the central portion 211 and have neutron absorbing portions 55 that absorb neutrons and nuclear fuel portions 56, and are arranged so that the positions of the neutron absorbing portions 55 and the nuclear fuel portions 56 relative to the central portion 211 can be adjusted.

[0054] According to this nuclear reactor 201, by disposing the neutron absorbing section 55 and the nuclear fuel section 56 in the fuel drum 251, the fuel drum 251 is configured as the reactor core, and reactivity control becomes possible with the core itself. Therefore, according to this nuclear reactor 201, since the fuel section is configured with the control drum 251, reactivity control can be performed with a simplified configuration.

[0055] In the nuclear reactor 201 of the embodiment, the fuel section is arranged so that a part of the fuel section is embedded in the outer periphery of the center section 211 .

[0056] According to this nuclear reactor 201, the nuclear fuel sections 56 are arranged in the fuel drum 251 and configured to be able to enter the center section 211, so that the size of the core system is not increased and each nuclear fuel section 56 can be brought closer to the center. Therefore, according to this nuclear reactor 201, efficient reactivity control can be performed.

[0057] In addition, in the embodiment of the reactor 201, the fuel section has a cylindrical fuel drum 251, and the neutron absorbing section 55 and the nuclear fuel section 56 are provided at different positions in the rotation direction of the fuel drum 251, and the fuel drum 251 is provided to be freely rotatable in such a manner that the positions of the neutron absorbing section 55 and the nuclear fuel section 56 relative to the center section 211 can be adjusted.

[0058] According to this nuclear reactor 201, by rotating the fuel drum 251, the positions of the neutron absorbing portion 55 and the nuclear fuel portion 56 relative to the center portion 211 can be adjusted, and the reactivity can be appropriately controlled.

[0059] In the nuclear reactor 201 of the embodiment, the central portion 211 has a polygonal prism shape, and the fuel drum (fuel portion) 251 is disposed on a flat portion of the polygonal prism shape of the central portion 211.

[0060] According to this nuclear reactor 201, by arranging the fuel drum 251 on the flat portion of the polygonal prism shape of the center portion 211, it is possible to bring the nuclear fuel closer to the center during operation for efficient reactivity control, and to move the nuclear fuel farther from the center portion 211 during shutdown for reliable shutdown. Note that in the nuclear reactor 201 of the embodiment, by arranging one fuel drum 251 on one flat portion of the polygonal prism shape, it is possible to increase the surface area of ​​the neutron absorbing portion 55 from the viewpoint of the neutron absorption effect.

[0061] In the nuclear reactor 201 of the embodiment, the central portion 211 includes a plurality of heat transfer tubes 41 arranged in an annular shape in the central portion and the outer periphery.

[0062] According to this reactor 201, the central and outer periphery of the core 211 are locations where the temperature rises in the core 211, and by arranging the heat transfer tubes 41 at these locations, heat can be extracted efficiently.

[0063] The control method for the nuclear reactor 201 of the above-described embodiment controls the reactivity of the nuclear fuel in the above-described nuclear reactor 201 by adjusting the positions of the neutron absorbing section 55 and the nuclear fuel section 56 relative to the center section 211 using the fuel drum (fuel section) 251.

[0064] According to this method for controlling the nuclear reactor 201, it is possible to efficiently control the reactivity in the nuclear reactor 201 in which the fuel weight in the reactor core system is increased.

[0065] The above-described reactor 201 may be configured so that the axial direction is vertical relative to the horizontal direction.

[0066] The present disclosure includes the following inventions. [Invention 1] A core that does not contain nuclear fuel, a plurality of fuel sections each having a neutron absorbing section that absorbs neutrons and a nuclear fuel section that are arranged to surround the central section, the positions of the neutron absorbing section and the nuclear fuel section being adjustable relative to the central section; Including, nuclear reactor. [Invention 2] The fuel portion is disposed so that a portion of the fuel portion extends into the outer periphery of the center portion. A nuclear reactor according to claim 1. [Invention 3] The fuel section has a cylindrical fuel drum, the neutron absorber and the nuclear fuel section are provided at different positions in the rotation direction of the fuel drum, and the fuel drum is rotatably provided in such a manner that the positions of the neutron absorber and the nuclear fuel section relative to the center can be adjusted. 3. The nuclear reactor according to claim 1 or 2. [Invention 4] the central portion has a polygonal prism shape, and the fuel portion is disposed on a flat portion of the polygonal prism shape of the central portion. A nuclear reactor according to any one of inventions 1 to 3. [Invention 5] The central portion includes a plurality of heat transfer tubes arranged annularly in a central portion and an outer circumferential portion. 5. A nuclear reactor according to any one of claims 1 to 4. [Invention 6] In any one of the nuclear reactors of inventions 1 to 5, The reactivity of the nuclear fuel is controlled by adjusting the positions of the neutron absorbing portion and the nuclear fuel portion relative to the center portion using the fuel portion. How to control a nuclear reactor. [Explanation of symbols]

[0067] 211 Center 41 Heat transfer tube 251 Fuel drum (fuel section) 55 Neutron absorber 56 Nuclear Fuel Department 201 Nuclear reactor

Claims

1. A core that does not contain nuclear fuel, a plurality of fuel sections each having a neutron absorbing section that absorbs neutrons and a nuclear fuel section that are arranged to surround the central section, the positions of the neutron absorbing section and the nuclear fuel section being adjustable relative to the central section; Including, nuclear reactor.

2. The fuel portion is disposed so that a portion of the fuel portion extends into the outer periphery of the center portion. The nuclear reactor of claim 1.

3. The fuel section has a cylindrical fuel drum, the neutron absorber and the nuclear fuel section are provided at different positions in the rotation direction of the fuel drum, and the fuel drum is rotatably provided in such a manner that the positions of the neutron absorber and the nuclear fuel section relative to the center can be adjusted. The nuclear reactor of claim 1.

4. the central portion has a polygonal prism shape, and the fuel portion is disposed on a flat portion of the polygonal prism shape of the central portion. The nuclear reactor of claim 1.

5. The central portion includes a plurality of heat transfer tubes arranged annularly in a central portion and an outer circumferential portion. The nuclear reactor of claim 1.

6. In a nuclear reactor including a plurality of fuel sections, each having a neutron absorbing section for absorbing neutrons and a nuclear fuel section, the fuel section being arranged so as to surround a central section not containing nuclear fuel, The reactivity of the nuclear fuel is controlled by adjusting the positions of the neutron absorbing portion and the nuclear fuel portion relative to the center portion using the fuel portion. How to control a nuclear reactor.

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