Nuclear reactor

Abstract

To extend operating period in accordance with loaded fuel.SOLUTION: A nuclear reactor 101 comprises: a reactor core 11 including nuclear fuel; a plurality of control drums 51 arranged around the reactor core 11 and provided with neutron absorbing parts 55 to absorb neutrons, the positions of the neutron absorbing parts 55 being adjustable relative to the reactor core 11; and a neutron breeder 26 disposed in a fuel region of the reactor core 11 that has high neutron energy.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to 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 fuel, and by moving it away, it increases the reactivity of the fuel. [Prior art documents] [Patent documents]

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

[0004] If the reactivity of the fuel is increased, the operating period of the reactor can be extended according to the amount of fuel loaded, so it is desirable to efficiently add reactivity to the reactor core.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a nuclear reactor that can efficiently add reactivity to the core and extend the operating period according to the loaded fuel. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a nuclear reactor according to one aspect of the present disclosure includes a core containing nuclear fuel, a plurality of control units arranged around the core and having neutron absorbing units that absorb neutrons and are configured to be able to adjust the position of the neutron absorbing units relative to the core, and a neutron breeding unit arranged in a fuel region in the core where neutron energy is high. [Effects of the Invention]

[0007] The present disclosure allows for extended operating periods depending on the fuel loaded. [Brief explanation of the drawings]

[0008] [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 cross-sectional plan view of another example of the configuration of the nuclear reactor according to the embodiment. [Figure 6] FIG. 6 is a partially enlarged perspective view of another example of the configuration of the nuclear reactor according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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.

[0010] FIG. 1 is a schematic diagram of a nuclear power generation system using a nuclear reactor according to an embodiment.

[0011] [Nuclear power generation system] As shown in FIG. 1, a nuclear power generation system 100 includes nuclear reactors 101, 201, and 301, a refrigerant circulation path 102, a turbine 103, a compressor 104, a generator 105, a heat exchanger 106, and a cooler 107.

[0012] The reactors 101, 201, and 301 each have a reactor vessel 111, a reactor core 112, and a heat conduction section 113. The reactor vessel 111 houses the reactor core 112 therein. 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 therein 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, causing the interior to become hot and pressurized. The reactor vessel 111 is made of a material with thermal insulation properties. The reactor core 112 contains nuclear fuel, which causes a nuclear reaction to occur and generates heat. The heat conduction section 113 extracts the heat generated in the reactor core 112 to the outside. Details of the reactors 101, 201, and 301 will be described later.

[0013] 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 reactors 101, 201, and 301 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 reactors 101, 201, and 301. The high-temperature cooling medium extracted from the reactors 101, 201, and 301 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 reactors 101, 201, and 301.

[0014] 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 reactors 101, 201, 301, 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.

[0015] The heat exchanger 106 exchanges heat between the cooling medium that has been heated by the reactors 101, 201, 301 and then driven the turbine 103 and the cooling medium that has driven the compressor 104.

[0016] 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.

[0017] In the nuclear reactors 101, 201, and 301, 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] The cooling medium heated by the heat exchanger 106 is then returned to the heat conducting portion 113 of the reactor 101, 201, 301.

[0022] 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.

[0023] [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 (cross-sectional view along AA in 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.

[0024] The nuclear reactor 101 includes a reactor vessel 111 , a reactor core 112 , and a heat transfer section 113 .

[0025] The reactor vessel 111 houses a reactor core 112 therein, the details of which will be described later.

[0026] The reactor core section 112 has the reactor core 11, the reflector section 12, the heat transfer tubes 41 that constitute the heat conduction section 113, and the 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.

[0027] In the embodiment, the core 11 is formed so that its overall outer shape is a hexagonal prism centered on the central axis O. For example, the core 11 has a plurality of blocks of the same shape arranged in a circumferential direction around the central axis O, and as a whole has a hexagonal prism shape that is long in the axial direction along the central axis O. Alternatively, the core 11 has a plurality of hexagonal plate-like blocks that are stacked widthwise along the axial direction, and thus has a hexagonal prism shape that is long in the axial direction. The shape of the core 11 is not limited to a hexagonal prism shape, and may be a polygonal prism shape or a cylindrical shape.

[0028] Although not shown in the figure, the core 11 includes nuclear fuel (radioactive material) and a support. The support forms the outer shape of the core 11. The support includes a moderator that transfers heat. The moderator can be, for example, highly oriented graphite (graphite) including graphene. The nuclear fuel is arranged, for example, by being inserted into holes formed in the support. The nuclear fuel may be in the form of a rod that is continuous in the axial direction, or in the form of pellets that are discontinuous in the axial direction. The nuclear fuel can use uranium (e.g., uranium-235), plutonium (e.g., plutonium-239, plutonium-241), thorium, or the like as a fissile material.

[0029] The core 11 further has a space 24. The space 24 is formed in the center of the core 11, penetrating the core 11 along the central axis O. Although not shown in the figure, the space 24 may include a portion that extends radially from the central axis O and penetrates the core 11 along the central axis O. The space 24 forms part of an emergency shutdown device. The emergency shutdown device is activated when the core temperature rises and reaches a predetermined temperature during operation of the reactor 101, and shuts down the reactor 101 by supplying neutron absorbers to the space 24 using a neutron absorber supply device (not shown).

[0030] The core 11 further includes a neutron multiplication section 26. The neutron multiplication section 26 is disposed in a fuel region in the core 11 where neutron energy is high. The high neutron energy refers to, for example, 2 MeV or more. The fuel region where neutron energy is high can also be referred to as a region where the contribution of the nuclear fuel to the reaction rate is high. In the nuclear reactor 101 of the embodiment, when the nuclear fuel is uniformly disposed in the core 11, the central portion of the core 11 in the range of the cross section (see FIGS. 3 and 4) is the fuel region where neutron energy is high. Therefore, in the embodiment, the neutron multiplication section 26 is disposed in the central portion of the core 11, as shown in FIGS. 2 and 3, and is disposed penetrating the core 11 along the central axis O. The neutron multiplication section 26 is formed in a cylindrical shape around the space portion 24 so that the space portion 24 is disposed in the center. In the embodiment, the neutron multiplication section 26 is formed in a cylindrical shape, but may be formed in a hexagonal or polygonal cylindrical shape to match the outer shape of the core 11. The neutron multiplication section 26 is disposed, for example, by being inserted into a hole formed in a support. The neutron multiplication section 26 may have a cylindrical shape that is continuous in the axial direction or a cylindrical shape that is discontinuous in the axial direction. Alternatively, like nuclear fuel, the neutron multiplication section 26 may have a rod shape that is continuous in the axial direction or a pellet shape that is discontinuous in the axial direction, and form a cylindrical outer shape as a whole. Beryllium oxide (BeO) can be used for the neutron multiplication section 26. Beryllium oxide's function changes depending on the energy range in which neutrons fly. When the energy of neutrons flying inside the core 11 is below a threshold, it functions as a neutron reflector, and when the energy of neutrons flying inside the core 11 is above the threshold, it functions as a neutron multiplication material. Therefore, in the nuclear reactor 101 of the embodiment, beryllium oxide (BeO) is disposed in the fuel region (center) of the core 11 where neutron energy is high, and thus functions as a neutron multiplication material. The neutron multiplication section 26 is not limited to beryllium oxide, and may be, for example, lead.

[0031] The reflector section 12 is disposed around the core 11 and constitutes the outer periphery of the core section 112. The reflector section 12 is made of a metal block and reflects radiation (neutrons) emitted from the nuclear fuel, thereby suppressing leakage of radiation outside the core section 112.

[0032] 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 core 11. That is, the body 31 covers the outer periphery of the core 11 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 core 11. 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 core 11.

[0033] 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.

[0034] 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.

[0035] 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. 1, the heat transfer tubes 41 are arranged so as to penetrate the core section 112 in the axial direction. The heat transfer tubes 41 are arranged, for example, by being inserted into holes formed in a support body of the core 11. Furthermore, 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, and extends axially outside the core section 112.

[0036] 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.

[0037] 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.

[0038] The reactivity control device 14 includes a control drum (control unit) 51 , a drive unit 53 , and a control device 57 .

[0039] A plurality of control drums 51 (12 in this embodiment) are arranged around the central axis O in the body section 34 of the reflector section 12 so as to surround the periphery of the core 11. The number of control drums 51 is not limited. When the outer shape of the core 11 is a polygonal column, the control drums 51 are arranged opposite to the flat portion forming the outer periphery of the polygonal column. The plurality of control drums 51 are formed in a cylindrical shape extending along the axial direction of the core 11. The control drums 51 have an axial length approximately equal to that of the core 11. The control drums 51 are supported rotatably around an axis 52 along the central axis O relative to the reflector section 12.

[0040] The control drum 51 has a drum main body 54, a neutron absorbing section 55, and a neutron reflecting section 56. The control drum 51 is configured such that the neutron absorbing section 55 and the neutron reflecting section 56 are provided on a portion of the drum main body 54 in the circumferential direction. The neutron absorbing section 55 and the neutron reflecting section 56 are provided at different positions in the rotation direction of the control drum 51.

[0041] 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 control drum 51. The drum body 54 can be made of, for example, graphite.

[0042] 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 control drum 51 (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.

[0043] The neutron reflector 56 is disposed in a relatively thick crescent-shaped region offset to the opposite side of the neutron absorber 55 within the circular region of the cross section of the cylindrical control drum 51 (see FIGS. 3 and 4). The neutron reflector 56 is disposed in a region that is thicker in the radial direction and wider in the circumferential direction than the neutron absorber 55 within the circular region of the cross section of the cylindrical control drum 51 (see FIGS. 3 and 4). The neutron reflector 56 may be made of beryllium oxide (BeO). However, the neutron reflector 56 is not limited to beryllium oxide, and may alternatively be made of, for example, NgO. The neutron reflector 56 may not be provided.

[0044] As the drum body 54 of the control drum 51 rotates, the circumferential positions of the neutron absorbing section 55 and the neutron reflecting section 56 change. That is, as the control drum 51 rotates, the neutron absorbing section 55 and the neutron reflecting section 56 move closer to or further away from the reactor core 11 (central axis O). During the rotation of the control drum 51, as shown in FIG. 3 , when the neutron absorbing section 55 moves closer to the reactor core 11, the neutron absorbing section 55 moves closer to the nuclear fuel in the reactor core 11, and the neutron reflecting section 56 moves further away from the nuclear fuel in the reactor core 11, resulting in a decrease in the reactivity of the nuclear fuel in the reactor core 11. On the other hand, when the neutron absorbing section 55 moves away from the reactor core 11 during rotation of the control drum 51 as shown in Fig. 4, the neutron absorbing section 55 moves away from the nuclear fuel in the reactor core 11 and the neutron reflecting section 56 moves closer to the nuclear fuel in the reactor core 11, increasing the reactivity of the nuclear fuel in the reactor core 11. In this way, the control drum 51 can control the reactivity of the nuclear fuel in the reactor core 11 and the core temperature by the rotational movement of the neutron absorbing section 55 and the neutron reflecting section 56. The core temperature is the average core temperature that is taken out to the outside of the reflector section 12 by the heat transfer tubes 41.

[0045] The drive unit 53 is a rotation drive mechanism that is connected to the shaft 52 of the control drum 51 and rotates the control drum 51 via the shaft 52 .

[0046] The control device 57 controls the driving of the drive unit 53 to change the rotational positions of the multiple control drums 51. 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).

[0047] [Other examples of reactor configurations] FIG. 5 is a cross-sectional plan view of another example of the configuration of the nuclear reactor according to the embodiment.

[0048] The reactor 201 shown in Fig. 5 differs from the reactor 101 shown in Fig. 2 to Fig. 4 in the arrangement of the neutron multiplication section 126, but is otherwise similar in configuration. Therefore, in the description of the reactor 201, parts equivalent to those in the reactor 101 are assigned the same reference numerals and description thereof will be omitted.

[0049] The core 11 has a neutron multiplication section 126. The neutron multiplication section 126 is arranged in a fuel region in the core 11 where neutron energy is high. The high neutron energy refers to, for example, 2 MeV or more. The fuel region with high neutron energy can also be referred to as a region where the contribution of the nuclear fuel to the reaction rate is high. In the nuclear reactor 201 of the embodiment, when the nuclear fuel is evenly arranged in the core 11 and when the control drum 51 includes the neutron reflector 56, the outer portion of the core 11 closest to the control drum 51 within the range of the cross section (see FIG. 5) is the fuel region with high neutron energy. Therefore, in the embodiment, the neutron multiplication section 126 is arranged in the outer portion of the core 11, as shown in FIG. 5, and is arranged to penetrate the core 11 along the central axis O. The neutron multiplication section 126 is formed in a cylindrical shape in the outer portion of the core 11. The neutron multiplication section 126 is formed to fit the outer shape of the core 11, and in the embodiment, is formed in a hexagonal cylindrical shape. When the outer shape of the core 11 is cylindrical or polygonal prism-shaped, the neutron multiplication section 126 is formed in a cylindrical or polygonal tubular shape to match the outer shape of the core 11. The neutron multiplication section 126 is arranged, for example, so as to cover the outer periphery of a support. The neutron multiplication section 126 may be a tubular shape that is continuous in the axial direction, or a tubular shape that is discontinuous in the axial direction. Alternatively, like nuclear fuel, the neutron multiplication section 126 may be a rod shape that is continuous in the axial direction, or a pellet shape that is discontinuous in the axial direction, and form a tubular outer shape as a whole. Beryllium oxide (BeO) can be used for the neutron multiplication section 126. The neutron multiplication section 126 is not limited to beryllium oxide, and may be, for example, lead.

[0050] The reactor 201 may have a neutron multiplication section 126 and a neutron multiplication section 26 of the reactor 101 .

[0051] FIG. 6 is a partially enlarged perspective view of another example of the configuration of the nuclear reactor according to the embodiment.

[0052] The reactor 301 shown in Fig. 6 differs from the reactor 101 shown in Fig. 2 to Fig. 4 in the arrangement of the neutron multiplication section 226, but is otherwise similar in configuration. Therefore, in the description of the reactor 301, the same parts as those in the reactor 101 are denoted by the same reference numerals, and the description thereof will be omitted.

[0053] The core 11 has a neutron breeding section 226. The neutron breeding section 226 is arranged in a fuel region in the core 11 with high neutron energy. High neutron energy refers to, for example, 2 MeV or more. The fuel region with high neutron energy can also be referred to as a region with a high nuclear fuel reaction rate. In the nuclear reactor 301 of the embodiment, for example, if the nuclear fuel is unevenly arranged in the core 11, the region where the nuclear fuel is densely arranged is the fuel region with high neutron energy. Alternatively, in the nuclear reactor 301 of the embodiment, even if the nuclear fuel is evenly arranged in the core 11, the fuel region with high nuclear fuel enrichment is the fuel region with high neutron energy. In the embodiment, the neutron breeding section 226 is arranged between a plurality of nuclear fuels 21 as shown in FIG. 6. In the embodiment, the nuclear fuels 21 are inserted into holes 20a that penetrate along the axial direction of a support 20 that constitutes the outer shape of the core 11 as shown in FIG. 6. The nuclear fuel 21 may be in the form of a rod that is continuous in the axial direction, or in the form of pellets that are discontinuous in the axial direction. The neutron multiplication section 226 is inserted, for example, into the hole 20a in place of the nuclear fuel 21 so as to be disposed between the nuclear fuel 21 in a direction perpendicular to the axial direction. The neutron multiplication section 226 may be inserted into a hole that is formed in the support 20 separately from the hole 20a and penetrates along the axial direction. The neutron multiplication section 226 may be in the form of a rod that is continuous in the axial direction, like the nuclear fuel 21, or in the form of pellets that are discontinuous in the axial direction. Beryllium oxide (BeO) can be used for the neutron multiplication section 226. The neutron multiplication section 226 is not limited to beryllium oxide, and may be, for example, lead.

[0054] In the case where the reactor 301 includes the neutron reflector 56 in the control drum 51, the reactor 301 may have the neutron multiplication unit 226 and the neutron multiplication unit 126 of the reactor 201.

[0055] The configuration in which the neutron multiplication section 226 is disposed among the plurality of nuclear fuels 21 in the nuclear reactor 301 can be applied to the arrangement of the neutron multiplication sections 26, 126 in the nuclear reactors 101, 201.

[0056] The nuclear reactors 101, 201, 301 of the above-mentioned embodiments are characterized by including a core 11 containing nuclear fuel, a plurality of control drums (control units) 51 arranged around the core 11 and having neutron absorption units 55 that absorb neutrons and are arranged so that the position of the neutron absorption units 55 relative to the core 11 can be adjusted, and a neutron multiplication unit 26, 126, 226 arranged in a fuel region in the core 11 where neutron energy is high.

[0057] According to the nuclear reactors 101, 201, and 301, by arranging the neutron multiplication sections 26, 126, and 226 in the fuel region with high neutron energy in the reactor core 11, the core reactivity can be efficiently increased by the neutron multiplication effect in the fuel region. This makes it possible for the nuclear reactors 101, 201, and 301 to extend the operating period according to the amount of fuel loaded, thereby extending the operating life.

[0058] In the nuclear reactor 101 of the embodiment, the neutron breeding section is disposed in the center of the core.

[0059] According to this nuclear reactor 101, when the nuclear fuel is evenly arranged in the core 11, the central part of the core 11 becomes a fuel region with high neutron energy, and therefore, by arranging the neutron breeding section 26 in the central part of the core 11, the above-mentioned effect can be obtained.

[0060] In addition, in the embodiment of the reactor 201 (201, 301), the control drum 51 further has a neutron reflecting section 56 and is configured so that the position of the neutron reflecting section 56 relative to the core 11 can be adjusted, and the neutron multiplication section 126 is arranged on the outer side of the core 11.

[0061] According to this reactor 201, the neutron reflecting section 56 of the control drum 51 makes the outer part of the core 11 a fuel region with high neutron energy, so by placing the neutron breeding section 126 on the outer part of the core 11, the above-mentioned effect can be obtained.

[0062] In the nuclear reactor 301 (101, 201) of the embodiment, the neutron breeding section 226 is arranged between the plurality of nuclear fuels 21 arranged therebetween.

[0063] According to this nuclear reactor 301 (101, 201), when arranging the neutron breeding section 226 in the fuel region with high neutron energy, it is preferable in terms of design and manufacturing to arrange it between the multiple nuclear fuels 21 arranged.

[0064] In the above-described reactors 101, 201, 301, the axial direction may be arranged vertically relative to the horizontal direction.

[0065] The present disclosure includes the following inventions. [Invention 1] a reactor core containing nuclear fuel; a plurality of control units each having a neutron absorbing unit arranged around the reactor core and configured to be able to adjust the position of the neutron absorbing unit relative to the reactor core; a neutron breeding section disposed in a fuel region having high neutron energy in the reactor core; Including, nuclear reactors. [Invention 2] The neutron breeding section is disposed in the center of the reactor core. A nuclear reactor according to claim 1. [Invention 3] the control unit further has a neutron reflector and is provided to be able to adjust the position of the neutron reflector with respect to the reactor core, The neutron breeding section is disposed in the outer part of the reactor core. 3. The nuclear reactor according to claim 1 or 2. [Invention 4] The neutron breeding section is disposed between the plurality of nuclear fuels. A nuclear reactor according to any one of inventions 1 to 3. [Explanation of symbols]

[0066] 11 Reactor Core 20a hole 21 Nuclear fuel 26,126,226 Neutron Breeding Unit 51 Control drum (control unit) 55 Neutron absorber 56 Neutron reflector 101,201,301 nuclear reactor

Claims

1. a reactor core containing nuclear fuel; a plurality of control units each having a neutron absorbing unit arranged around the reactor core and configured to be able to adjust the position of the neutron absorbing unit relative to the reactor core; a neutron breeding section disposed in a fuel region having high neutron energy in the reactor core; Including, nuclear reactors.

2. The neutron breeding section is disposed in the center of the reactor core.

10. The nuclear reactor of claim 1.

3. the control unit further has a neutron reflector and is provided to be able to adjust the position of the neutron reflector with respect to the reactor core, The neutron breeding section is disposed in the outer part of the reactor core.

10. The nuclear reactor of claim 1.

4. The neutron breeding section is disposed between the plurality of nuclear fuels.

10. The nuclear reactor of claim 1.

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