Reactor core and reactor

Abstract

To improve productivity and improve strength in a reactor core and a reactor.SOLUTION: In a reactor core, multiple rod-shaped fuel blocks are arranged adjacent to each other on their sides, and in each of the fuel blocks, multiple pellets storing TRISO fuel therein are arranged in series inside a first thermal conduction cylindrical body.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to nuclear reactor cores and nuclear reactors. [Background technology]

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

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

[0004] In conventional nuclear power generation systems, the fuel section that constitutes the core is composed of multiple stacked disk-shaped fuel layers. In this case, forming the fuel layers into a disk shape or stacking multiple disk-shaped fuel layers requires many manufacturing processes, and there is a demand for improving the manufacturability of the core. There is also a demand for increasing the strength of the fuel section that is composed of stacked fuel layers.

[0005] The present disclosure is intended to solve the above-mentioned problems, and has an object to provide a nuclear reactor core and a nuclear reactor that are capable of improving manufacturability and strength. [Means for solving the problem]

[0006] To achieve the above object, the reactor core of the present disclosure is a reactor core in which multiple rod-shaped fuel blocks are arranged adjacent to each other at their sides, and the fuel blocks are arranged inside a first heat conduction cylinder with multiple pellets containing TRISO fuel arranged in series inside.

[0007] The nuclear reactor of the present disclosure also includes the reactor core, a thermal conductor that conducts heat generated by the nuclear reaction of nuclear fuel in the reactor core to the outside, and a reactivity control device that is arranged outside the reactor core and has a plurality of control units that are provided with neutron reflecting units that reflect neutrons and neutron absorbing units that absorb neutrons. [Effects of the Invention]

[0008] According to the nuclear reactor core and nuclear reactor of the present disclosure, it is possible to improve manufacturability and strength. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a nuclear power generation system according to this embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the reactor unit of this embodiment. [Figure 3] FIG. 3 is a cross-sectional view of the reactor taken along line III-III of FIG. [Figure 4] FIG. 4 is a longitudinal cross-sectional view of the fuel block. [Figure 5] FIG. 5 is a cross-sectional view of the fuel block taken along line VV of FIG. [Figure 6] FIG. 6 is a vertical cross-sectional view showing the heat conduction block. [Figure 7] FIG. 7 is a vertical cross-sectional view showing the space block. [Figure 8] FIG. 8 is a schematic diagram showing details of the control drum. [Figure 9] FIG. 9 is a schematic diagram illustrating the operation of the control drum. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations that combine the embodiments. Furthermore, the components in the embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the so-called equivalent range.

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

[0012] As shown in FIG. 1, the nuclear power generation system 100 includes a reactor unit 101, 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 unit 101 has a reactor vessel 111, a reactor 112, and a heat transfer tube section 113. The reactor vessel 111 houses the reactor 112 inside. The reactor vessel 111 houses the reactor 112 in a sealed state. The reactor vessel 111 is provided with an opening and closing section, such as a lid, so that the reactor 112 placed inside can be stored or removed. The reactor vessel 111 can maintain a sealed state even when a nuclear reaction occurs in the reactor 112 and the inside becomes hot and high pressure. The reactor vessel 111 is made of a material with thermal insulation properties.

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

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

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

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

[0018] The cooler 107 cools the cooling medium that has been 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.

[0019] Heat generated by the reaction of nuclear fuel in the nuclear reactor 112 is extracted via the heat transfer tube section 113. That is, the heat transfer tube section 113 heats the cooling medium with the heat of the nuclear reactor 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.

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

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

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

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

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

[0025] <Reactor Unit> FIG. 2 is a cross-sectional view showing the reactor unit of this embodiment, and FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2 showing the reactor.

[0026] 2 and 3, the reactor unit 101 has a reactor vessel 111, a reactor 112, and a heat transfer tube section 113. The reactor 112 is housed inside the reactor vessel 111, and is provided with the heat transfer tube section 113. The heat transfer tube section 113 extracts heat generated in the reactor 112 to the outside.

[0027] <Reactor> The reactor 112 has a reactor core (reactor core) 11, and is provided with a reflector 12, a thermal conductor 13, and a reactivity control device 14. The reactor 112 has a hexagonal prism shape and is arranged horizontally. That is, the reactor 112 is arranged with its central axis O aligned horizontally. However, the reactor 112 is not limited to a hexagonal prism shape, and is preferably a polygonal prism shape, but may also be cylindrical. The reactor 112 may also be arranged vertically. That is, the reactor 112 may be arranged with its central axis O aligned vertically.

[0028] <Reactor Core> The core 11 is configured to have an overall hexagonal prism shape centered on a central axis O. The core 11 includes a plurality of fuel blocks 21. The plurality of fuel blocks 21 are arranged with their sides adjacent to each other. The fuel blocks 21 are rod-shaped. Specifically, the fuel blocks 21 are hexagonal prism shapes. However, the fuel blocks 21 are not limited to a hexagonal prism shape; they are preferably polygonal prism shapes, but may also be cylindrical. The fuel blocks 21 are hexagonal prism shapes (polygonal prism shapes) and are arranged so that adjacent fuel blocks 21 are in surface contact with each other. The core 11 has an overall hexagonal prism shape by arranging a plurality of hexagonal prism-shaped fuel blocks 21 adjacent to each other. Note that the uranium enrichment of the plurality of fuel blocks 21 may be changed, for example, depending on their positions. For example, the uranium enrichment may be lowered in a region where the fuel blocks 21 are arranged closely together and are prone to high temperatures, and higher in a region where the fuel blocks 21 are arranged close to a thermal conduction block 41 (described later) and are prone to low temperatures. This allows the power distribution in the core 11 to be flattened.

[0029] The fuel block 21 may be composed of one piece, but it is preferable to configure it by arranging a plurality of fuel blocks 21 in series in the longitudinal direction. In this case, the plurality of fuel blocks 21 arranged in series are arranged so that the end faces in the longitudinal direction contact each other.

[0030] FIG. 4 is a longitudinal cross-sectional view showing a fuel block, and FIG. 5 is a VV cross-sectional view of FIG. 4 showing the fuel block.

[0031] The fuel blocks 21 house nuclear fuel inside. The fuel blocks 21 are arranged radially outward from the central axis O in the radial direction.

[0032] As shown in FIGS. 4 and 5 , the fuel block 21 is configured by arranging multiple pellets 23, each containing a large number of TRISO (TR-structural ISOtropic) fuel particles 22, in series inside a first thermally conductive cylinder 24. The TRISO fuel particles 22 are ceramic fuel kernels with a diameter of several hundred microns coated with pyrolytic carbon to withstand high temperatures and burnups of approximately 1000°C or higher. The TRISO fuel particles 22 are spherical in shape, with a coating layer 22b made of carbon, silicon carbide, or the like, provided on the outside of the fuel kernels 22a. The fuel kernels 22a can contain fissile material such as uranium (e.g., uranium-235), plutonium (e.g., plutonium-239, plutonium-241), or thorium. The pellets 23 are fuel compacts formed by sintering a carbon (graphite) powder compact with the TRISO fuel particles 22 inside. Alternatively, the pellets 23 may be fuel compacts formed by sintering a silicon carbide powder compact with the TRISO fuel particles 22 inside. The pellet 23 has a cylindrical shape.

[0033] The first heat conducting cylinder 24 has a hexagonal prism shape with a cylindrical through-hole 24a formed in the center. The first heat conducting cylinder 24 is made of, but is not limited to, highly oriented graphite (graphite) including graphene. A plurality of pellets 23 are arranged in series inside the first heat conducting cylinder 24. The fuel block 21 has a predetermined length and is configured with a plurality of pellets arranged in series.

[0034] <Reflector> 2 and 3, the reflector 12 is arranged to surround the reactor core 11. The reflector 12 is made of a graphite block and has the ability to scatter and absorb neutrons of the radiation (neutrons) irradiated from the nuclear fuel that constitutes the reactor core 11.

[0035] The reflector 12 has a body 31 and a pair of wall portions 32, 33. The body 31 is cylindrical 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 portion 32 is disk-shaped and is disposed on one axial side of the body 31. That is, the wall portion covers and closes one end of the core 11. The wall portion 33 is disk-shaped and is disposed on the other axial side of the body 31. That is, the wall portion 33 covers and closes the other end of the core 11.

[0036] The reactor vessel 111 has a body 34, support plates 35 and 36, and lids 37 and 38. The body 34 is cylindrical and disposed radially outside the reflector 12. That is, the body 34 surrounds and covers the outer periphery of the reflector 12. The support plate 35 is disk-shaped and disposed on one axial side of the body 34. That is, the support plate 35 covers and closes one end of the reflector 12. The support plate 36 is disk-shaped and disposed on the other axial side of the body 34. That is, the support plate 36 covers and closes the other end of the reflector 12. The lid 37 is hemispherical and disposed on one axial side of the body 34. That is, the lid 37 is attached so as to cover the support plate 35. The lid 38 is hemispherical and disposed on the other axial side of the body 34. That is, the lid portion 38 is attached so as to cover the support plate 36 .

[0037] When the reactor vessel 111 contains the reactor core 11 inside, the inside of the reactor vessel 111 is preferably sealed and filled with an inert gas such as helium gas in order to prevent oxidation inside the reactor vessel 111.

[0038] <Thermal conductor> The heat transfer tube section 113 has a heat conductor 13. The heat conductor 13 has a heat conduction block 41. That is, the heat conductor 13 conducts heat generated by the nuclear reaction of the nuclear fuel in the reactor core 11 to the heat conduction block 41. The heat conductor 13 has an inlet side manifold 42, an outlet side manifold 43, an inlet pipe 44, and an outlet pipe 45 provided for the heat conduction block 41.

[0039] The heat conduction block 41 has a rod shape, similar to the fuel block 21. Specifically, the heat conduction block 41 has a hexagonal prism shape. However, the heat conduction block 41 is not limited to a hexagonal prism shape, and is preferably a polygonal prism shape, but may also be a cylinder shape, and is preferably the same shape as the fuel block 21. The heat conduction block 41 has a hexagonal prism shape (polygonal prism shape) and is arranged so that adjacent heat conduction blocks 41 and adjacent fuel blocks 21 are in surface contact with each other.

[0040] The core 11 has a hexagonal prism shape as a whole, with multiple hexagonal prism-shaped fuel blocks 21 arranged adjacent to each other. Heat conduction blocks 41 are arranged on the outer periphery and center of the multiple fuel blocks 21. Multiple heat conduction blocks 41 arranged on the outer periphery of the multiple fuel blocks 21 are arranged so as to surround the entire periphery of the multiple fuel blocks 21 from the outside. Multiple heat conduction blocks 41 arranged in the center of the multiple fuel blocks 21 are arranged so as to surround the entire periphery of the multiple fuel blocks 21 from the inside.

[0041] The thermally conductive block 41 may be disposed at least either on the outer periphery or the center of the plurality of fuel blocks 21. The thermally conductive block 41 may be disposed not only on the outer periphery or the center of the plurality of fuel blocks 21 but also between the plurality of fuel blocks 21.

[0042] FIG. 6 is a vertical cross-sectional view showing the heat conduction block.

[0043] The plurality of heat conduction blocks 41 are arranged to penetrate the reactor core 11 in the axial direction. One longitudinal end of each of the plurality of heat conduction blocks 41 is supported by the support plate 35, and the other longitudinal end is supported by the support plate 36. As shown in FIG. 6, the heat conduction block 41 is configured by disposing a heat transfer tube 47 inside a second heat conduction cylinder 46. The second heat conduction cylinder 46, like the first heat conduction cylinder 24, is configured from highly oriented graphite (graphite) containing graphene, but is not limited to these materials. The heat conduction tube 47 is configured from SUS316FR steel, but is not limited to this material. The heat conduction block 41 has a flow path 48 for a cooling medium (e.g., carbon dioxide) inside the heat conduction tube 47.

[0044] The inlet-side manifold 42 is disposed outside the support plate 35. One end of each heat transfer tube 47 in the multiple heat conduction blocks 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 47 in the multiple heat conduction blocks 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. One end of the outlet pipe 45 is connected to the outlet-side manifold 43, and the other end passes through the lid 38 to extend to the outside.

[0045] The cooling medium is supplied from the inlet pipe 44 to the inlet manifold 42, and flows from the inlet manifold 42 to each heat transfer tube 47 in the multiple heat conduction blocks 41. The cooling medium flows through each heat transfer tube 47 and is discharged to the outlet manifold 43, and is then discharged from the outlet manifold 43 through the outlet pipe 45. At this time, the cooling medium is heated by the heat generated by the nuclear reaction of the nuclear fuel in the reactor core 11 as it flows through the flow passages 48 of the multiple heat transfer tubes 47, and the heat is taken out to the outside.

[0046] <Reactivity Control Device> The reactivity control device 14 is disposed in the reflector 12. The reactivity control device 14 is disposed so as to surround the periphery of the reactor core 11. The reactivity control device 14 has a plurality of control drums (control units) 51 (12 in this embodiment). However, the number of control drums 51 is not limited. The plurality of control drums 51 are disposed outside the reactor core 11 at intervals (preferably at equal intervals) in the circumferential direction. The plurality of control drums 51 are disposed outside and facing the plurality of fuel blocks 21 (thermal conduction blocks 41) that constitute the reactor core 11.

[0047] The control drum 51 has a cylindrical shape and is arranged along the axial direction of the core 11. The control drum 51 has approximately the same length as the core 11. The control drum 51 is rotatably supported by the reflector 12. A connecting part 52 is connected to one axial end of the control drum 51. The connecting part 52 penetrates the support plate 35 and the lid part 37 of the reflector 12, and one end is connected to one end of the control drum 51 and the other end extends outside the reflector 12. The driving part 53 is arranged outside the reactor 112. The other ends of the multiple connecting parts 52 are connected to the driving part 53. The driving part 53 can rotate the multiple control drums 51 via the multiple connecting parts 52.

[0048] 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 drum main body 54 may be made of, for example, graphite. The neutron absorbing section 55 may be made of, for example, boron carbide (B4C). The neutron reflecting section 56 may be made of, for example, beryllium oxide (BeO). However, the neutron reflecting section 56 is not limited to beryllium oxide, and may also be made of, for example, NgO. Here, the neutron absorbing section 55 has higher neutron absorption performance than the drum main body 54, the neutron reflecting section 56, and the reflector 12. The neutron reflecting section 56 has higher neutron reflection performance than the drum main body 54, the neutron absorbing section 55, and the reflector 12.

[0049] As the control drum 51 rotates, the circumferential positions of the neutron absorbing section 55 and the neutron reflecting section 56 on the drum body 54 change. That is, as the control drum 51 rotates, the neutron absorbing section 55 and the neutron reflecting section 56 can move closer to or away from the reactor core 11.

[0050] The reactivity control device 14 has a control device 57. The control device 57 is connected to a drive unit 53. The control device 57 can control the rotational positions of the multiple control drums 51 by controlling the drive unit 53. 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).

[0051] <Emergency stop device> The emergency shutdown device is activated when the temperature of the core 11 rises and reaches a predetermined temperature during operation of the reactor 112, thereby shutting down the reactor 112.

[0052] Although not shown, the emergency shutdown device has a neutron absorber supply device. The neutron absorber supply device is arranged on one side of the axial direction with respect to the reactor 112 and is capable of supplying neutron absorbers to the reactor core 11. The reactor core 11 has a plurality of space blocks 61.

[0053] The space block 61 has a rod shape, similar to the fuel block 21. Specifically, the space block 61 has a hexagonal prism shape. However, the space block 61 is not limited to a hexagonal prism shape, and is preferably a polygonal prism shape, but may also be a cylindrical shape, and is preferably the same shape as the fuel block 21. The space block 61 has a hexagonal prism shape (polygonal prism shape) and is arranged so as to be in surface contact with adjacent space blocks 61 and adjacent fuel blocks 21.

[0054] The core 11 has an overall hexagonal prism shape due to the adjacent arrangement of a plurality of hexagonal prism-shaped fuel blocks 21. The space blocks 61 are arranged radially outward from the center of the plurality of fuel blocks 21.

[0055] FIG. 7 is a vertical cross-sectional view showing the space block.

[0056] The plurality of space blocks 61 are arranged so as to penetrate the reactor core 11 in the axial direction. One longitudinal end of each of the plurality of space blocks 61 is supported by the support plate 35, and the other longitudinal end is supported by the support plate 36. As shown in FIG. 7 , the space block 61 is configured by forming a space 63 inside a third heat conducting cylinder 62. Like the first heat conducting cylinder 24, the third heat conducting cylinder 62 is configured from highly oriented graphite (graphite) containing graphene, but is not limited to these materials. The space 63 has a cylindrical shape that is long in the longitudinal direction of the space block 61. The space block 61 can accommodate a spherical neutron absorber in the space 63.

[0057] When the temperature of the reactor core 11 rises and reaches a predetermined temperature, the neutron absorber supply device fills the space 63 of the space block 61 with neutron absorbers. As a result, the reactivity of the nuclear fuel in the reactor core 11 decreases.

[0058] <Nuclear reactor control method> FIG. 8 is a schematic diagram showing the details of the control drum, and FIG. 9 is a schematic diagram showing the operation of the control drum.

[0059] As shown in FIGS. 1, 2 and 3, in the nuclear reactor 112, the control device 57 controls the rotational positions of a plurality of control drums 51 that constitute the reactivity control device 14 in accordance with the temperature of the reactor core 11.

[0060] 8, in the reactivity control device 14, the control drum 51 is disposed outside the reactor core 11, facing the radially outer flat surface 21a of the fuel block 21 (thermal conduction block 41). The control drum 51 has a cylindrical shape and is supported by the reflector 12 so as to be rotatable about an axis O1. The control drum 51 has a drum main body 54, a neutron absorbing section 55, and a neutron reflecting section 56. The neutron absorbing section 55 and the neutron reflecting section 56 are provided at different positions in the rotational direction of the drum main body 54.

[0061] The reactivity control device 14 can adjust the positions of the neutron absorbing section 55 and the neutron reflecting section 56 relative to the reactor core 11 using the control drum 51. The neutron absorbing section 55 and the neutron reflecting section 56 are provided in a crescent shape on the outer periphery of the control drum 51. That is, when the control drum 51 is viewed from one end in the axial direction, the neutron absorbing section 55 and the neutron reflecting section 56 form a crescent shape. The thickness of the crescent-shaped neutron reflecting section 56 is thicker than the thickness of the crescent-shaped neutron absorbing section 55. Here, the thickness refers to the length in the radial direction of the control drum 51. That is, the thicknesses of the neutron absorbing section 55 and the neutron reflecting section 56 vary in the circumferential direction of the control drum 51.

[0062] The control drum 51 is rotatable between a first position and a second position relative to the flat surface 21a of the fuel block 21 constituting the core 11. The first position (position shown in FIG. 4) is a position where the neutron reflecting portion 56 faces the flat surface 21a of the fuel block 21 (core 11) and the neutron absorbing portion 55 does not face the flat surface 21a of the fuel block 21 (core 11). The second position (position shown in FIG. 5) is a position where the neutron absorbing portion 55 faces the flat surface 21a of the fuel block 21 (core 11) and the neutron reflecting portion 56 does not face the flat surface 21a of the fuel block 21 (core 11). The reactivity control device 14 is capable of rotating the control drum 51 between the first position and the second position.

[0063] As shown in Fig. 8, at a first position where the neutron reflector 56 faces the fuel block 21 but the neutron absorber 55 does not face the fuel block 21, neutrons emitted to the outside from the fuel block 21 are reflected by the neutron reflector 56 and returned to the fuel block 21, contributing to nuclear fission. This increases the reactivity of the nuclear fuel that constitutes the core 11. On the other hand, as shown in Fig. 5, at a second position where the neutron absorber 55 faces the fuel block 21 but the neutron reflector 56 does not face the fuel block 21, neutrons emitted to the outside from the fuel block 21 are absorbed by the neutron absorber 55 and are not returned to the fuel block 21, so they do not contribute to nuclear fission. This decreases the reactivity of the nuclear fuel that constitutes the core 11. The reactivity control device 14 rotates the multiple control drums 51 to move the neutron absorbing section 55 and the neutron reflecting section 56 toward or away from the reactor core 11, thereby controlling the reactivity of the nuclear fuel in the reactor core 11 and the temperature of the reactor core 11. Here, the temperature of the reactor core 11 is the average core temperature that is taken out to the outside of the reflector 12 by the thermal conductor 13.

[0064] 2, the control device 57 can acquire the temperature of the core 11. The control device 57 controls the rotational positions of the multiple control drums 51 that make up the reactivity control device 14, moving the neutron absorbing unit 55 away from the core 11 and moving the neutron reflecting unit 56 closer to the core 11. This increases the reactivity of the core 11, and the reactor 112 starts operating. Meanwhile, the control device 57 controls the rotational position of the control drum 51, moving the neutron absorbing unit 55 closer to the core 11 and moving the neutron reflecting unit 56 closer to the core 11. This decreases the reactivity of the core 11, and the reactor 112 stops operating.

[0065] [Effects of this embodiment] The reactor core of the first embodiment is a reactor core (reactor core) 11 in which the sides of multiple rod-shaped fuel blocks 21 are arranged adjacent to each other, and the fuel blocks 21 are arranged inside a first heat conduction cylinder 24 with multiple pellets 23 containing TRISO fuel 22 arranged in series inside.

[0066] According to the reactor core of the first aspect, the fuel block 21 is formed by arranging multiple pellets 23 containing TRISO fuel 22 in series inside the first heat conduction cylinder 24, thereby improving manufacturability and strength.

[0067] The reactor core according to the second embodiment is the reactor core according to the first embodiment, and further, the fuel blocks 21 are polygonal prism-shaped, and adjacent fuel blocks 21 are in surface contact with each other. This makes it possible to improve the efficiency of heat transfer between the fuel blocks 21 and also to improve the strength of the reactor core 11.

[0068] The reactor core according to the third embodiment is the reactor core according to the second embodiment, and further comprises a plurality of fuel blocks 21 arranged adjacent to each other to form a polygonal prism shape as a whole. This allows the core 11 to have a polygonal shape, which can improve the strength.

[0069] The reactor core according to the fourth aspect is the reactor core according to the third aspect, and further, the fuel blocks 21 are arranged in series in the longitudinal direction, thereby making it possible to shorten the length of each fuel block 21 and improve manufacturability.

[0070] A nuclear reactor core according to a fifth aspect is the nuclear reactor core according to the second aspect, and further, the pellets 23 are cylindrical fuel compacts formed by sintering a graphite powder compact with the TRISO fuel 22 disposed therein, or cylindrical fuel compacts formed by sintering a silicon carbide powder compact with the TRISO fuel 22 disposed therein, thereby improving the uranium loading rate.

[0071] A nuclear reactor core according to a sixth aspect is the nuclear reactor core according to any one of the first to fifth aspects, and further, the first heat conducting cylinder 24 is made of graphite. This allows the heat generated by the nuclear reaction of the TRISO fuel 22 to be conducted to the first heat conducting cylinder 24 efficiently.

[0072] A reactor core according to a seventh aspect is a reactor core according to any one of the first to fifth aspects, and further includes a heat conduction block 41, in which a heat transfer tube 47 is arranged inside a second heat conduction cylinder 46, arranged on at least one of the outer periphery and the center of the plurality of fuel blocks 21. This allows heat conducted from the TRISO fuel 22 to the fuel block 21 to be conducted to the heat conduction block 41 and appropriately extracted to the outside by a cooling medium flowing through a flow passage 48 of the heat transfer tube 47.

[0073] The reactor core according to the eighth aspect is the reactor core according to any one of the first to fifth aspects, and further comprises space blocks 61 in which neutron absorber accommodating sections are provided in the space sections 63 of the third heat conducting cylinders 62, which are arranged at the center of the plurality of fuel blocks 21 and radially from the center. As a result, in the event of an emergency in the reactor 112, the reactor 112 can be properly shut down by supplying neutron absorbers to the space sections 63 of the third heat conducting cylinders 62.

[0074] The nuclear reactor according to the ninth aspect includes a core (reactor core) 11, a thermal conductor 13 that conducts heat generated by the nuclear reaction of nuclear fuel in the core 11 to the outside, and a reactivity control device 14 that has a plurality of control drums (controllers) 51 that are arranged outside the core 11 and are provided with neutron reflectors 56 that reflect neutrons and neutron absorbers 55 that absorb neutrons. Therefore, the neutron reaction and core temperature of the core 11 can be controlled. [Explanation of symbols]

[0075] 11 Core (nuclear reactor core) 12 Reflector 13 Thermal Conductors 14 Reactivity Control Device 21 Fuel Block 22 TRISO fuel 23 pellets 24 First heat conduction cylinder 31 Torso 32,33 wall 34 Torso 35,36 Support plate 37,38 Lid 41 Heat conduction block 42 Inlet manifold 43 Outlet manifold 44 Inlet pipe 45 Outlet pipe 46 Second heat conduction cylinder 47 Heat transfer tube 48 Distribution path 51 Control drum (control unit) 52 Connecting part 53 Drive unit 54 Drum body 55 Neutron absorber 56 Neutron reflector 57 Control Device 61 Space block 62 Third heat conduction cylinder 63 Space section 100 Nuclear Power Systems 101 Reactor Unit 102 Refrigerant circulation path 103 Turbine 104 Compressor 105 Generator 106 Heat exchanger 107 Cooler 108,109 Connecting shaft 111 Reactor Vessel 112 Nuclear reactor 113 Heat transfer tube section

Claims

1. In a nuclear reactor core in which a plurality of rod-shaped fuel blocks are arranged side by side, The fuel block includes: A plurality of pellets containing TRISO fuel are arranged in series inside the first heat conduction cylinder. Nuclear reactor core.

2. The fuel blocks are polygonal prism-shaped, and adjacent fuel blocks are in surface contact with each other. The nuclear reactor core of claim 1 .

3. A plurality of the fuel blocks are arranged adjacent to each other to form a polygonal prism shape as a whole. The nuclear reactor core of claim 2.

4. A plurality of the fuel blocks are arranged in series in the longitudinal direction. The nuclear reactor core of claim 1 .

5. The pellet is a cylindrical fuel compact obtained by sintering a graphite powder compact with the TRISO fuel disposed therein, or a cylindrical fuel compact obtained by sintering a silicon carbide powder compact with the TRISO fuel disposed therein. The nuclear reactor core of claim 1 .

6. The first heat conducting cylinder is made of graphite. The nuclear reactor core of claim 1 .

7. a heat conduction block having a heat transfer tube disposed inside a second heat conduction cylinder is disposed at least either on the outer periphery or the center of the plurality of fuel blocks; The nuclear reactor core of claim 1 .

8. a space block in which a neutron absorber housing portion is provided inside the third heat conducting cylinder, the space block being disposed at the center of the plurality of fuel blocks and radially arranged from the center; The nuclear reactor core of claim 1 .

9. A nuclear reactor core according to claim 1; a thermal conductor that conducts heat generated by a nuclear reaction of nuclear fuel in the reactor core to the outside; a reactivity control device having a plurality of control units each provided with a neutron reflector that reflects neutrons and a neutron absorber that absorbs neutrons, the control unit being disposed outside the reactor core; A nuclear reactor equipped with:

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