Thimble assembly and nuclear reactor

Abstract

To provide a thimble assembly and a nuclear reactor, which allow neutron flux detectors to be guided from an upper portion of a reactor vessel to a reactor core.SOLUTION: A thimble assembly comprises: a support column supported on an upper core support plate along a vertical direction; a support plate coupled to the support column and disposed above the upper core support plate; a plurality of guide thimbles capable of penetrating through a plurality of neutron flux detectors from a lower end of the support plate toward a reactor core; and a plurality of supports integrally provided on the support plate to support the plurality of neutron flux detectors.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a thimble assembly and a nuclear reactor. [Background technology]

[0002] A nuclear reactor is configured with a reactor core provided inside a reactor vessel. In a nuclear reactor, neutrons generated in the core are absorbed by control rods, and the number of neutrons is adjusted to control the output. For this reason, it is necessary to accurately measure the distribution of neutrons (neutron flux) in the core. A neutron flux detector can be inserted from the lid of the reactor vessel through a thimble assembly into the fuel assemblies that make up the core. Examples of thimble assemblies include those described in patent documents. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3153833 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional pressurized water reactors in Japan, a method is adopted in which a neutron flux detector in the reactor is inserted into the reactor from the bottom of the reactor vessel. If the neutron flux detector is inserted from the top of the reactor vessel, it is possible to eliminate the nozzle stand at the bottom of the reactor vessel, and the risk of coolant leakage from the bottom of the reactor vessel can be eliminated. In order to insert the neutron flux detector into the reactor from the top of the reactor vessel, a structure is required to guide the neutron detector to a specified core address while protecting it from the flow of coolant in the reactor. In addition, this structure must also take into consideration the ease of replacing the neutron flux detector. When adopting a method in which a neutron flux detector is inserted into the reactor from the top of the reactor vessel, it is preferable to take the above-mentioned functions into consideration.

[0005] The present disclosure is intended to solve the above-mentioned problems, and has an object to provide a thimble assembly and a nuclear reactor that enable a neutron flux detector to be guided from the top of the reactor vessel to the reactor core. [Means for solving the problem]

[0006] In order to achieve the above-mentioned objective, the thimble assembly of the present disclosure comprises a support column supported in the vertical direction on an upper core support plate, a support plate connected to the support column and positioned above the upper core support plate, a plurality of guide thimbles through which neutron flux detectors can be inserted from the lower end of the support plate toward the core, and a plurality of support portions integrally formed on the support plate and supporting the multiple neutron flux detectors.

[0007] The nuclear reactor of the present disclosure also includes a reactor vessel, a core composed of fuel, and the thimble assembly. Effect of the Invention

[0008] The thimble assembly and reactor of the present disclosure allow neutron flux detectors to be guided from the top of the reactor vessel to the core. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a vertical cross-sectional view showing a pressurized water reactor. [Diagram 2] FIG. 2 is a schematic diagram showing a thimble assembly according to the present disclosure of this embodiment. [Diagram 3] FIG. 3 is a horizontal cross-sectional view (cross-sectional view taken along line III-III in FIG. 2) showing the thimble assembly of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 a configuration in which each embodiment is combined. In addition, the components in the embodiments include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range.

[0011] <Pressurized water reactor> FIG. 1 is a vertical cross-sectional view showing a pressurized water reactor.

[0012] Although not shown, the nuclear power plant has a nuclear reactor and a steam generator arranged in a reactor containment vessel, and a steam turbine power generation facility. The nuclear reactor in this embodiment is a pressurized water reactor (PWR). However, the nuclear reactor may be any type of nuclear reactor, such as a boiling water reactor (BWR) or a fast breeder reactor (FBR).

[0013] As shown in FIG. 1, in a pressurized water reactor 10, a reactor vessel 11 is composed of a reactor vessel main body 12 and a reactor vessel lid 13 attached to the top of it so that reactor internals can be inserted inside, and the reactor vessel lid 13 is fixed to the reactor vessel main body 12 by a plurality of stud bolts 14 and nuts 15 so that it can be opened and closed.

[0014] The reactor vessel body 12 has a cylindrical shape that is open at the top and closed at the bottom in a hemispherical shape, and is provided with an inlet nozzle 16 for supplying light water as a primary coolant at the top, and an outlet nozzle 17 for discharging the light water. A core barrel 18 is disposed inside the reactor vessel body 12, and the top is supported by the inner wall surface of the reactor vessel body 12. An upper core support plate 19 is disposed inside the reactor vessel body 12, and the top is supported by the top of the core barrel 18. An upper core plate 20 is suspended and supported from the upper core support plate 19 by a plurality of upper core support columns 21.

[0015] A lower core support plate 22 is supported below the core barrel 18, and the outer periphery of the lower core support plate 22 is positioned and supported on the inner wall surface of the reactor vessel main body 12 by a positioning member 23. A lower core plate 24 is supported below the core barrel 18. A core 25 is configured by arranging a large number of fuel assemblies 26, and a large number of control rods 27 are arranged inside, and the control rods 27 can be inserted into the fuel assemblies 26. A large number of control rod cluster guide tubes 28 are fixed to the upper core support plate 19, and the control rods 27 can be inserted inside. The reactor vessel lid 13 has a hemispherical shape, and a control rod drive mechanism 29 is arranged therein, and a plurality of control rod cluster drive shafts 30 are inserted into the control rod cluster guide tubes 28, and the control rods 27 are connected to the lower end of the reactor vessel lid 13. The control rod drive mechanism 29 controls the reactor power by inserting and removing each control rod 27 into and from the core 25.

[0016] Additionally, a thimble assembly 31 of the present disclosure is disposed inside the reactor vessel 11. The thimble assembly 31 guides a neutron flux detector 45 (see FIG. 2) from the instrumentation nozzle 32 of the reactor vessel lid 13 to the core 25 (fuel assemblies 26). The neutron flux detector 45 can measure the neutron level and distribution (neutron flux).

[0017] <Thimble assembly> FIG. 2 is a schematic diagram showing a thimble assembly of the present disclosure in this embodiment, and FIG. 3 is a horizontal cross-sectional view (cross-sectional view taken along line III-III in FIG. 2) showing the thimble assembly of the present disclosure.

[0018] As shown in FIGS. 2 and 3, the thimble assembly 31 includes a support post 41, a support plate 42, a plurality of guide thimbles 43, and a plurality of support portions 44.

[0019] The instrumentation nozzle 32 has a cylindrical shape. The instrumentation nozzle 32 is supported by penetrating the reactor vessel lid 13 (see FIG. 1) in the vertical direction. The upper core support plate 19 has a disk shape. The upper core support plate 19 is arranged along the horizontal direction inside the reactor vessel body 12 (see FIG. 1). The outer periphery of the upper core support plate 19 is supported by the inner wall of the reactor vessel body 12. The upper end of the upper core support column 21 is connected to the lower surface of the upper core support plate 19. The upper core support plate 19 has a plurality of guide tubes 33 arranged at predetermined positions in the horizontal direction. The guide tubes 33 are supported within the upper core support column 21 and extend to the fuel assemblies 26 through the inside of the upper core support column 21. The guide thimbles 43 are guided to the fuel assemblies 26 by the guide tubes 33.

[0020] The support column 41 has a cylindrical shape. The support column 41 is arranged along the vertical direction, and a lower end portion is supported on the upper surface 19a of the upper core support plate 19 by the receiving seat 34. That is, the support column 41 has a lower end portion supported by the receiving seat 34, and a lower end portion of the receiving seat 34 is fitted into a support hole (not shown) formed in the upper surface 19a of the upper core support plate 19 for support. The support column 41 is arranged at the same position in the horizontal direction as the instrumentation nozzle 32. Therefore, the upper end portion of the support column 41 passes through the inside of the instrumentation nozzle 32 and extends to the outside of the reactor vessel lid 13.

[0021] The support plate 42 is connected to the support columns 41 and disposed above the upper core support plate 19. The support plate 42 has a trapezoidal plate shape and is disposed along the up-down direction. The support plate 42 is supported on the upper surface portion 19a of the upper core support plate 19 by a plurality of receiving seats 35. One horizontal end of the support plate 42 is fixed to the lower portion of the support columns 41 by a plurality of connecting members 51. A support leg (positioning portion) 52 is fixed to the lower portion of the other horizontal end of the support plate 42. The support plate 42 is supported by having a lower end of the support leg 52 fixed to the upper surface portion 19a of the upper core support plate 19 via the receiving seat 35. In this embodiment, the support plate 42 is positioned by fitting the lower end of the support leg 52 of the support plate 42 into the receiving seat 35 of the upper core support plate 19, but the present invention is not limited to this configuration. For example, the lower end of the support leg 52 may be formed into a recessed shape, and the shaft of the upper core support plate 19 may be fitted into the lower end of the support leg 52. The lower end of the support column 41 also functions as a positioning portion.

[0022] The multiple guide thimbles 43 allow the neutron flux detectors 45 to be inserted from the lower end of the support plate 42 toward the core 25 (fuel assemblies 26). That is, the multiple guide thimbles 43 are disposed inside the guide tube 33, with their upper ends connected to the lower end of the support plate 42 and their lower ends extending to the core 25. The multiple support parts 44 are provided integrally with the support plate 42. The multiple support parts 44 support the multiple neutron flux detectors 45 between the support column 41 and the multiple guide thimbles 43, respectively.

[0023] The guide thimble 43 has an inner diameter that allows the neutron flux detector 45 to be inserted therein. A plurality of neutron flux detectors 45 are inserted into the support column 41. The upper end of the neutron flux detector 45 passes through the support column 41 and extends to the outside of the reactor vessel 11 (see FIG. 1), and the lower end extends to the core 25 (fuel assemblies 26). The plurality of neutron flux detectors 45 are supported by a plurality of support portions 44 formed on the support plate 42 between the support column 41 and the guide thimble 43. The neutron flux detector 45 is covered by a cover (not shown) between the support column 41 and the support plate 42.

[0024] The number of support parts 44 provided is the same as the number of neutron flux detectors 45. The multiple support parts 44 are provided at intervals in the X direction, which is the in-plane direction of the support plate 42. The support parts 44 are hollow parts provided inside the support plate 42. Specifically, the support parts 44 are groove parts that open to the surface of the support plate 42 as hollow parts. The support pillar 41 and the multiple support parts 44 are positioned with a shift in the horizontal direction. That is, the support pillar 41 and the multiple support parts 44 are positioned with a shift in the X direction, which is the in-plane direction of the support plate 42, and are positioned with a shift in the Y direction, which is the thickness direction of the support plate 42. The X direction and the Y direction are horizontal directions and perpendicular to each other.

[0025] The groove portion as the support portion 44 has an opening 61 and a restraint portion 62. The opening 61 opens on the surface 43a of the support plate 42. Here, the surface 42a of the support plate 42 is a flat surface on the side where the support column 41 is located. The restraint portion 62 communicates with the opening 61 inside the support plate 42. The restraint portion 62 has a rectangular shape that is long along the X direction that is the in-plane direction of the support plate 42. The width of the opening 61 in the X direction, and the length of the restraint portion 62 in the X direction and the width of the restraint portion 62 in the Y direction are dimensions larger than the outer diameter of the neutron flux detector 45. The groove portion as the support portion 44 has a T-shaped cross section. That is, the opening 61 that opens on the surface 42a of the support plate 42 communicates with the middle position of the restraint portion 62 in the length direction (X direction).

[0026] It should be noted that the support portion 44 is not limited to a T-shaped cross-sectional shape. The support portion 44 may have, for example, an L-shaped cross-sectional shape or a Y-shaped cross-sectional shape. Furthermore, the support portion 44 is not limited to one having an opening 61 and a restraining portion 62. The support portion 44 may have, for example, only an opening 61, or only a restraining portion 62. In other words, the support portion 44 may be a groove or a hole. Furthermore, the shape is not limited.

[0027] Moreover, it is desirable to provide the support portion 44 in the entire region from the upper end to the lower end of the support plate 42. However, it is sufficient that the support portion 44 is provided in at least a portion of the region from the upper end to the lower end of the support plate 42. One support portion 44 may be provided in a portion of the region from the upper end to the lower end of the support plate 42, or multiple support portions may be provided intermittently.

[0028] The multiple neutron flux detectors 45 are inserted into the support column 41 and bent at a predetermined angle from an opening (not shown) of the support column 41 toward the support plate 42. The multiple neutron flux detectors 45 are then guided by the multiple supports 44, respectively, and then inserted into guide thimbles 43 connected to the support plate 42.

[0029] At this time, the multiple neutron flux detectors 45 are individually supported by the multiple support parts 44 between the support column 41 and the guide thimble 43. In this case, the neutron flux detector 45 is inserted into the restraint part 62 through the opening 61 and supported by the support part 55. The neutron flux detector 45 is supported by the restraint part 62 in a state bent in the horizontal direction (X direction or Y direction) between the support column 41 and the guide thimble 43. After being fitted into the support part 44, the neutron flux detector 45 deforms while trying to return to its original shape, so that it is caught by the restraint part 62 and prevented from coming out to the front of the support plate 42 from the opening 61. As a result, the neutron flux detector 45 is supported and held in the support part 44.

[0030] The neutron flux detector 45 supported on the support plate 42 of the thimble assembly 31 extends through the guide thimble 43 to the fuel assembly 26. Therefore, the neutron flux detector 45 can be inserted from outside the reactor vessel 11 to the fuel assembly 26 via the thimble assembly 31 and the guide thimble 43, and the neutron level and distribution (neutron flux) of the fuel assembly 26 can be measured by the neutron flux detector 45.

[0031] [Effects of this embodiment] The thimble assembly of the first embodiment comprises a support column 41 supported in the vertical direction on the upper core support plate 19, a support plate 42 connected to the support column 41 and positioned above the upper core support plate 19, a plurality of guide thimbles 43 through which neutron flux detectors 45 can be inserted from the lower end of the support plate 42 toward the core 25, and a plurality of support portions 44 integrally formed on the support plate 42 and supporting the multiple neutron flux detectors 45.

[0032] According to the thimble assembly of the first aspect, a plurality of support parts 44 supporting a plurality of neutron flux detectors 45 are integrally formed on the support plate 42, so that there is no need to provide the support parts 44 as separate members from the support plate 42, thereby simplifying the structure.

[0033] The thimble assembly according to the second embodiment is the thimble assembly according to the first embodiment, and further includes support legs 52 as positioning parts that position the support plate 42 relative to the upper core support plate 19. This allows the support plate 42 to be positioned with high accuracy.

[0034] The thimble assembly according to the third embodiment is the thimble assembly according to the first or second embodiment, and further, the support portion 44 is a hollow portion provided inside the support plate 42. This allows the neutron flux detector 45 to be supported inside the support plate 42 by the support portion 44, and the neutron flux detector 45 can be protected from the flow of the coolant inside the reactor vessel 11.

[0035] The thimble assembly according to the fourth embodiment is the thimble assembly according to the third embodiment, and further, the cavity is a groove portion that opens to the surface of the support plate 42. This makes it possible to easily support the neutron flux detector 45 on the support portion 44 which is the groove portion.

[0036] The thimble assembly according to the fifth embodiment is the thimble assembly according to the fourth embodiment, further comprising: the groove portion having an opening 61 that opens into the surface of the support plate 42, and a restraining portion 62 that communicates with the opening 61 inside the support plate 42. As a result, when the neutron flux detector 45 is inserted into the restraining portion 62 from the opening 61 and supported, the neutron flux detector 45 is restrained by the restraining portion 62, and deviation from the opening 61 can be suppressed.

[0037] The thimble assembly according to the sixth aspect is the thimble assembly according to the fifth aspect, further comprising a groove having a T-shaped cross section, which makes it possible to easily process the support portion 44.

[0038] The thimble assembly according to the seventh aspect is the thimble assembly according to any one of the first to sixth aspects, and further includes a support portion 44 provided on at least a portion in the up-down direction of the support plate 42. This allows the support portion 44 to support the neutron flux detector 45.

[0039] The nuclear reactor according to the eighth embodiment includes a reactor vessel 11, a core 25 composed of fuel, and a thimble assembly 31. This allows the neutron flux detector 45 to be guided from the top of the reactor vessel 11 to the core 25 using the thimble assembly 31. [Explanation of symbols]

[0040] 10 Pressurized Water Reactor 11 Reactor vessel 12 Reactor vessel body 13 Reactor vessel lid 18 Core tank 19 Upper core support plate 19a Top part 20 Upper core plate 21 Upper core support column 25 Core 26 Fuel assembly 31 Thimble Assembly 32 Instrumentation Pipe Stand 33 Guide tube 34,35 Receiver 41 Support column 42 Support plate 43 Guide Thimble 44 Support part (cavity part, groove part) 45 Neutron Flux Detector 51 Connecting member 52 Support leg (positioning part) 61 Opening 62 Restraint part

Claims

1. A support column supported on the upper core support plate along the vertical direction; a support plate connected to the support columns and disposed above the upper core support plate; A plurality of guide thimbles through which neutron flux detectors can be inserted from the lower end of the support plate toward the reactor core; a plurality of support portions provided integrally with the support plate and supporting the neutron flux detector; A thimble assembly comprising:

2. a positioning portion for positioning the support plate relative to the upper core support plate; 2. The thimble assembly of claim 1.

3. The support portion is a hollow portion provided inside the support plate.

2. The thimble assembly of claim 1.

4. The cavity is a groove opening on the surface of the support plate.

4. The thimble assembly according to claim 3.

5. The groove portion has an opening that opens to a surface of the support plate and a restraint portion that communicates with the opening inside the support plate.

5. The thimble assembly according to claim 4.

6. The groove has a T-shaped cross section.

6. The thimble assembly according to claim 5.

7. The support portion is provided on at least a portion of the support plate in the up-down direction. The thimble assembly according to any one of claims 1 to 6.

8. A reactor vessel; a reactor core composed of fuel; A thimble assembly according to claim 1; A nuclear reactor comprising:

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