JP2017106836A - Boiling-water reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiling-water reactor provided with: densely arranged hexagonal columnar fuel assemblies; and Y-shaped control rods inserted among three fuel assemblies arranged adjacently to one another, and capable of smoothly carrying out initial fuel loading work and fuel exchanging work by preventing interference of the fuel assemblies and the Y-shaped control rods with each other.SOLUTION: The boiling-water reactor is provided with: densely arranged hexagonal columnar fuel assemblies 14; and Y-shaped control rods 15 inserted among three fuel assemblies 14 arranged adjacently to one another. This boiling-water reactor has vertical guides 24 that vertically extend among the three fuel assemblies 14 and on each horizontal extensions of three blades constituting the Y-shaped control rods 15, and have widths T1 larger than thicknesses T2 of the blades of the Y-shaped control rods.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a boiling water nuclear reactor including a densely arranged hexagonal columnar fuel assembly and a Y-shaped control rod inserted between three fuel assemblies adjacent to each other.

  In the case of nuclear power generation, in view of the problem that long-lived superuranium elements generated as a by-product when burning uranium as fuel accumulates as nuclear waste, the conventional boiling water reactor (BWR) of a boiling water reactor (BWR) Based on the technology, a resource reusable BWR (RBWR: Resource-Renewable Boiling Water Reactor) capable of burning a transuranium element as a fuel has been developed.

  In this RBWR, the conversion ratio of transuranium nuclides is increased compared to the conventional BWR, and the amount of generation and extinction of superuranium nuclides during reactor operation can be made substantially the same, and the conversion ratio is about 1.0. Is possible.

  In order to achieve this core characteristic, in the RBWR described in Patent Document 1, fuel rods enriched with depleted uranium and enriched with super uranium nuclides are arranged in a triangular lattice pattern in a channel box having a hexagonal horizontal section. The fuel density is increased by using a hexagonal fuel assembly. In addition, the flow rate of light water, which serves both as a moderator and a coolant, is reduced to increase the void ratio (volume ratio of steam in the gas-liquid two-phase flow of water and steam) compared to the current BWR, and the fuel assembly The water-to-fuel volume ratio inside is reduced. If the volume ratio of water to fuel is reduced in this way, the neutron moderation effect by light water is suppressed, and fast neutrons and neutrons in the resonance region are increased, so that the conversion ratio of transuranium nuclides can be increased. And the Y-shaped control rod for controlling the reactor power is arranged in the nectar at a ratio of one to three fuel assemblies.

  In the RBWR, a dummy fuel assembly or a spent fuel assembly is replaced with an unused fuel assembly with the Y-shaped control rods fully inserted into the core at the time of construction or periodic inspection in the reactor. At this time, if even one fuel assembly adjacent to the Y-shaped control rod is taken out, the Y-shaped control rod may fall into the empty space. Therefore, before removing the fuel assembly, remove the Y-shaped control rod. It needs to be fixed. For example, Patent Document 2 has a hexagonal fuel assembly in which fuel rods are arranged in a triangular lattice shape, and a Y-shaped control rod having three blades inserted between them and having a blade interval of 120 degrees each. A fuel exchange jig used when replacing a fuel assembly in a core, wherein two hexagonal fuel assemblies located on an extension line of two blades of the Y-shaped control rod and the Y-shaped control rod There is disclosed a fuel exchange jig characterized in that it has a plurality of fitting portions for joining the two.

JP-A-8-220276 JP 2007-93475 A

  In the fuel replacement work, it is necessary to replace the fuel assemblies one by one from the viewpoint of work reliability. However, since several hundred fuel assemblies are loaded in the core, It takes a long time. As a method for shortening the working time, it is conceivable to increase the moving speed when the fuel assembly is inserted into or removed from the core. However, increasing the moving speed of the fuel assembly increases the vibration and shaking of the fuel assembly and the Y-shaped control rod, so that the fuel assembly interferes with the Y-shaped control rod, and the Y-shaped control rod May be damaged.

  The present invention has been made in view of the above circumstances, and the purpose thereof is Y inserted between a densely arranged hexagonal columnar fuel assembly and three fuel assemblies adjacent to each other. In a boiling water reactor equipped with a letter-shaped control rod, it is possible to smoothly perform the initial fuel loading operation or the fuel replacement work by preventing interference between the fuel assembly and the Y-shaped control rod. It is to provide a boiling water reactor.

  In order to solve the above-mentioned problems, the present invention includes a densely arranged hexagonal columnar fuel assembly and a Y-shaped control rod inserted between three fuel assemblies adjacent to each other. In a boiling water reactor, the Y-shaped control rod extends vertically between the three fuel assemblies and on the horizontal extension of each of the three blades constituting the Y-shaped control rod. It is assumed that a vertical guide having a width larger than the thickness of the blades can be installed.

  According to the present invention, in a boiling water reactor comprising a densely arranged hexagonal columnar fuel assembly and a Y-shaped control rod inserted between three fuel assemblies adjacent to each other The interference between the fuel assembly and the Y-shaped control rod can be prevented, and the initial fuel loading operation or the fuel replacement operation can be performed smoothly.

It is a whole block diagram of a boiling water reactor. It is a horizontal sectional view of the core shown in FIG. FIG. 3 is a horizontal sectional view of the vicinity of a Y-shaped control rod of the core shown in FIG. 2. It is a horizontal sectional view of the wing | blade which comprises the Y-shaped control rod shown in FIG. It is a bird's-eye view of Y-shaped control rod vicinity of the core which installed the vertical guide which concerns on 1st Example of this invention. It is a horizontal sectional view of the vicinity of the Y-shaped control rod of the core in which the vertical guide according to the first embodiment of the present invention is installed. It is a figure which shows the fuel exchange procedure in the case of installing the vertical guide which concerns on 1st Example of this invention in a reactor core permanently. It is a figure which shows the modification of the fuel replacement | exchange procedure in case the vertical guide which concerns on 1st Example of this invention is not permanently installed in a core. It is a horizontal sectional view of the vicinity of the Y-shaped control rod of the core in which the vertical guide according to the second embodiment of the present invention is installed. It is a horizontal sectional view of the vicinity of the Y-shaped control rod of the core in which the vertical guide according to the third embodiment of the present invention is installed. It is a horizontal sectional view of the vicinity of the Y-shaped control rod of the core in which the vertical guide according to the fourth embodiment of the present invention is installed. It is a horizontal sectional view of the vicinity of the Y-shaped control rod of the core in which the vertical guide according to the fifth embodiment of the present invention is installed. It is a horizontal sectional view of the vicinity of the Y-shaped control rod of the core in which the vertical guide according to the sixth embodiment of the present invention is installed. It is a bird's-eye view of Y-shaped control rod vicinity of the core which installed the vertical guide which concerns on the 7th Example of this invention. It is a horizontal sectional view of the vicinity of the Y-shaped control rod of the core in which the vertical guide according to the seventh embodiment of the present invention is installed. It is a horizontal sectional view of the vicinity of the Y-shaped control rod of the core in which the vertical guide according to the eighth embodiment of the present invention is installed. It is a horizontal sectional view of the vicinity of the Y-shaped control rod of the core in which the vertical guide according to the ninth embodiment of the present invention is installed. It is a horizontal sectional view of the vicinity of the Y-shaped control rod of the core in which the vertical guide according to the tenth embodiment of the present invention is installed. It is a horizontal sectional view of the vicinity of the Y-shaped control rod of the core in which the vertical guide according to the eleventh embodiment of the present invention is installed. It is a horizontal sectional view of the vicinity of the Y-shaped control rod of the core in which the vertical guide according to the twelfth embodiment of the present invention is installed.

  FIG. 1 shows the overall configuration of a boiling water reactor (RBWR). Although the boiling water reactor 1 includes the core 2 for an electric output of 1350 MW, the output scale is not limited to this. By changing the number of fuel assemblies loaded in the core 2, it is possible to realize the core 2 of another power scale.

  In the boiling water reactor 1, a reactor core 2, a steam separator 4, and a steam dryer 5 are disposed in a reactor pressure vessel 3. The core 2 is surrounded by a core shroud 6 in the reactor pressure vessel 3. The steam / water separator 4 is disposed above the core 2, and the steam dryer 5 is disposed above the steam / water separator 4. A plurality of internal pumps (coolant supply devices) 7 are installed at the bottom of the reactor pressure vessel 3, and an impeller (impeller) of the internal pump 7 is formed between the reactor pressure vessel 3 and the core shroud 6. Placed in the downcomer. A main steam pipe 9 and a water supply pipe 10 for supplying steam from the steam dryer 5 to the turbine 8 are connected to the reactor pressure vessel 3.

  During operation of the boiling water reactor 1, the coolant in the downcomer is pressurized by the rotation of the impeller of the internal pump 7 and supplied to the core 2. The coolant supplied into the core 2 is guided into each fuel assembly, which will be described later, and is heated by heat generated by the fission of the fissile material, and a part thereof becomes steam. The coolant in the gas-liquid two-phase flow state is guided from the core 2 to the steam separator 4 to separate the steam. Water is further removed from the separated steam by the steam dryer 5. The steam from which moisture has been removed flows through the main steam pipe 9 and is supplied to the turbine 8, and the turbine 8 rotates. A generator 11 connected to the turbine 8 rotates and generates electric power. The steam discharged from the turbine 8 is condensed in the condenser 12 to become condensed water. The condensed water is introduced into the reactor pressure vessel 3 through the water supply pipe 10 by the water supply pump 13. On the other hand, the liquid coolant separated by the steam separator 4 is mixed with the condensed water supplied through the water supply pipe 10 in the downcomer, pressurized by the internal pump 7 again, and supplied to the core 2. The Here, light water, a mixture of light water and heavy water is used as the coolant.

  FIG. 2 shows a horizontal cross section of the core 2. For example, 720 hexagonal columnar fuel assemblies 14 are densely loaded in the core 2. One Y-shaped control rod 15 is arranged in three fuel assemblies 14, and 223 Y-shaped control rods 15 are provided so as to be inserted into the core 2.

  FIG. 3 is a horizontal sectional view of the vicinity of the Y-shaped control rod 15 of the core 2, and shows a state in which the Y-shaped control rod 15 is inserted between three hexagonal columnar fuel assemblies 14 adjacent to each other. Show. In the fuel assembly 14, fuel rods 17 are arranged in a triangular lattice shape in a hexagonal tubular channel box 16. A plurality of pellets made of nuclear fuel material are arranged in a cladding tube (not shown) of the fuel rod 17 so as to be aligned in the axial direction (vertical direction) of the fuel rod 17. The fuel rod 17 includes a lower fuel region, an internal blanket region, an upper fuel region, and an upper blanket region from the lower end toward the upper end. The inner blanket region and the upper blanket region are filled with depleted uranium, which is a residue during uranium enrichment, and the lower fuel region and the upper fuel region are filled with uranium nuclides (TRU) extracted from spent nuclear fuel. ) Containing fuel pellets made of nuclear fuel material.

  Lower tie plates (not shown) of these fuel assemblies 14 are supported by a plurality of fuel support fittings provided on a core support plate (not shown) disposed at the lower end of the core 2. A coolant channel that guides the coolant to the fuel assembly 14 is formed in the fuel support bracket, and an orifice installed in the fuel support bracket is disposed at the inlet of the coolant channel.

  Further, as shown in FIG. 3, the Y-shaped control rod 15 has three wings 19 extending outward from a tie rod 18 located at the center, and these three wings 19 are spaced 120 degrees apart. They are arranged to form a Y-shape, and are arranged so as to be positioned between the three fuel assemblies 14 arranged in a triangular lattice shape.

Here, the structure of the blade 19 constituting the Y-shaped control rod 15 will be described. FIG. 4 shows a horizontal cross section of the blade 19 constituting the Y-shaped control rod 15. One end of a U-shaped sheath 20 is connected to the tie rod 18, and a plurality of neutron absorber tubes 21 are arranged in a row inside the sheath 20 formed of stainless steel. The neutron absorber tube 21 is filled with a neutron absorber 22 such as boron carbide (B ₄ C) to form a neutron absorption region. FIG. 4 shows a horizontal cross section in this neutron absorption region. The sheath 20 is provided with a plurality of holes (not shown), and the neutron absorber tube 21 can be cooled by circulating the coolant through the plurality of holes.

  The Y-shaped control rod 15 is connected to a control rod driving device 23 (see FIG. 1) provided individually at the bottom of the reactor pressure vessel 3. The control rod drive unit 23 performs each operation of inserting the Y-shaped control rod 15 into the core 2 and withdrawing it from the core 2. The control rod driving device 23 is motor driven, and can finely adjust the position of the Y-shaped control rod 15 in the vertical direction.

  In the boiling water reactor 1 according to the present invention, in order to prevent interference between the fuel assembly 14 and the Y-shaped control rod 15, the Y-shaped control rod is provided between the three fuel assemblies 14 adjacent to each other. The vertical guides extending in the vertical direction can be installed on the horizontal extensions of the three wings 19 constituting the blade 15.

  Hereinafter, embodiments of the vertical guide will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same component and the overlapping description is abbreviate | omitted suitably.

  FIG. 5 is a bird's-eye view of the vicinity of the Y-shaped control rod 15 of the core 2 in which the vertical guide according to the first embodiment of the present invention is installed, and FIG. 6 is a horizontal sectional view thereof.

  As shown in FIG. 5, the vertical guide 24 is formed of a quadrangular prism-shaped member, and an insertion portion 25 formed in a tapered shape is provided at the lower end thereof. By inserting the insertion portion 25 into a fitting portion 27 provided on the upper surface of the fuel support fitting 26, the vertical guide 24 can be installed on the fuel support fitting 26.

  The upper ends of the vertical guides 24 are connected to each other by a trifurcated guide arm 28. As a result, the three vertical guides 24 can be installed integrally with the fuel support fitting 26. The height of the vertical guide 24 is such that the upper end of the Y-shaped control rod 15 does not interfere with the guide arm 28 when the vertical guide 24 is installed on the fuel support bracket 26. It is set to a height protruding upward.

  As shown in FIG. 6, the width (T1) of the vertical guide 24 seen from the center of the Y-shaped control rod 15 is larger than the blade thickness (T2) of the Y-shaped control rod 15 and the fuel assembly 14. It is set smaller than the gap width (G1). As a result, it is possible to prevent the fuel assembly 14 and the Y-shaped control rod 15 from interfering with each other and to suppress the vibration and shaking of the fuel assembly 14 and the Y-shaped control rod 15.

  Next, the fuel exchange procedure of the core 2 according to the present embodiment will be described with reference to FIGS. FIG. 7 is a diagram showing a fuel replacement procedure when the vertical guide 24 is permanently installed in the core 2, and FIG. 8 is a diagram showing a fuel replacement procedure when the vertical guide 24 is not permanently installed in the core 2.

  First, the fuel exchange procedure when the vertical guide 24 is permanently installed in the core 2 will be described.

  (1) In order to prevent the criticality of nuclear fuel, the Y-shaped control rod 15 is fully inserted between the three fuel assemblies 14 adjacent to each other, and the operation of the boiling water reactor 1 is stopped (FIG. 7 ( a)).

  (2) The guide arm 28 is grasped by a fuel changer or a dedicated lifting tool (not shown), and the three vertical guides 24 are moved so that the center of the Y-shaped control rod 15 and the center of the guide arm 28 coincide with each other. To do. Thereafter, the vertical guide 24 is lowered vertically downward, and the insertion portion 25 of the vertical guide 24 is inserted into the fitting portion 27 of the fuel support fitting 26 and installed on the fuel support fitting 26 (see FIG. 7B).

  (3) After the spent fuel assembly 14a is pulled out along the vertical guide 24 by the refueling machine, the unused fuel assembly 14b is loaded along the vertical guide 24 in the empty space 29 (see FIG. 7C). ).

  (4) The fuel replacement operation when the vertical guide 24 is permanently installed in the core 2 is completed (see FIG. 3D).

  On the other hand, when the vertical guide 24 is not permanently installed, the following procedure is performed following (1) to (3).

  (5) The guide arm 28 is grasped by a fuel changer or a dedicated lifting tool, and is lifted vertically upward and removed from the fuel support fitting 26 (see FIG. 8D).

  (6) The fuel exchange operation when the vertical guide 24 is not permanently installed in the core 2 is completed (see FIG. 8E).

  According to the boiling water reactor 1 in which the vertical guide 24 according to the present embodiment is installed, the Y-shaped control rod 15 is configured between the fuel assemblies 14 adjacent to each other at the time of initial fuel loading or fuel replacement. By installing the vertical guide 24 on the horizontal extension of each of the three blades 19, interference between the fuel assembly 14 and the Y-shaped control rod 15 is prevented, and the fuel assembly 14 and the Y-shaped control are controlled. The vibration and shaking of the rod 15 can be suppressed. As a result, the Y-shaped control rod 15 can be protected, and the initial fuel loading operation or the fuel replacement operation can be performed smoothly.

  Further, the vertical cross section of the vertical guide 24 is a quadrangle, and the vertical guide 24 is disposed in a direction in which one of the side faces is parallel to the side face of the closest fuel assembly 14, whereby the fuel assembly 14 and the vertical guide are arranged. 24 can come into contact with the surface, and the vibration suppressing effect of the fuel assembly 14 can be improved.

  Further, when the vertical guide 24 is permanently installed in the reactor core 2, interference between the fuel assembly 14 and the Y-shaped control rod 15 is prevented even during operation of the boiling water reactor 1, and the fuel assembly 14 and The vibration and shaking of the Y-shaped control rod 15 can be suppressed.

  When the vertical guide 24 is permanently installed in the core 2, the flow path area of the coolant is reduced by the cross-sectional integral of the vertical guide 24, and the water-to-fuel volume ratio is reduced. As a result, the neutron moderation effect by the coolant is suppressed and fast neutrons and neutrons in the resonance region increase, so the conversion ratio of the superuranium nuclides can be increased, and the local heat generation can be increased. .

  A vertical guide 24 according to a second embodiment of the present invention will be described in comparison with the first embodiment. FIG. 9 is a horizontal sectional view of the vicinity of the Y-shaped control rod 15 of the core 2 in which the vertical guide 24 according to this embodiment is installed. In FIG. 9, the difference from the first embodiment (see FIG. 6) is that the horizontal section of the vertical guide 24 is circular.

  According to the boiling water reactor 1 in which the vertical guide 24 according to the present embodiment is installed, the following effects are obtained in addition to the same effects as the first embodiment.

  Since the horizontal cross section of the vertical guide 24 is circular, the vertical guide 24 can be easily manufactured. However, in the first embodiment, the side surface of the vertical guide 24 and the side surface of the fuel assembly 14 can come into surface contact, whereas in this embodiment, the side surface of the vertical guide 24 and the side surface of the fuel assembly 14 are in contact with each other. Since surface contact cannot be achieved, the vibration suppression effect of the fuel assembly 14 may be slightly inferior to that of the first embodiment.

  A boiling water reactor 1 according to a third embodiment of the present invention will be described in comparison with the first embodiment. FIG. 10 is a horizontal sectional view of the vicinity of the Y-shaped control rod 15 of the core 2 in which the vertical guide 24 according to the present embodiment is installed. 10, the difference from the first embodiment (see FIG. 6) is that the horizontal section of the vertical guide 24 is a hexagon.

  Also in the boiling water reactor 1 in which the vertical guide 24 according to the present embodiment is installed, the same effect as in the first embodiment can be obtained. The horizontal cross section of the vertical guide 24 is a quadrangle in the first embodiment and a hexagon in the present embodiment. However, from the viewpoint of improving the vibration suppression effect of the fuel assembly 14, the adjacent fuel assemblies 14 have a horizontal cross section. Any horizontal cross section may be used as long as it has a side surface facing in parallel with the side surface.

  A vertical guide 24 according to a fourth embodiment of the present invention will be described in comparison with the first embodiment. FIG. 11 is a horizontal sectional view of the vicinity of the Y-shaped control rod 15 of the core 2 in which the vertical guide 24 according to this embodiment is installed. In FIG. 11, the difference from the first embodiment (see FIG. 6) is that a groove 30 extending in the vertical direction is provided on each side surface of the vertical guide 24 having a square water surface cross section.

  According to the boiling water reactor 1 in which the vertical guide 24 according to the present embodiment is installed, the following effects are obtained in addition to the same effects as the first embodiment.

  The grooves 30 provided on each side surface of the vertical guide serve as a coolant flow path, and the flow rate of the coolant flowing in the vicinity of the vertical guide 24 is increased as compared with the first embodiment. As a result, the difference between the flow rate of the coolant flowing in the portion adjacent to the vertical guide 24 and the flow rate of the coolant flowing in the other portion in the outer peripheral portion of the fuel assembly 14 is reduced, and the outer edge portion of the fuel assembly 14 The imbalance of the cooling effect in can be improved. In this embodiment, one groove 30 is provided on each side surface of the vertical guide 24. However, the number, position, size, and the like of the groove 30 can be changed as appropriate.

  A vertical guide 24 according to a fifth embodiment of the present invention will be described focusing on differences from the second embodiment. FIG. 12 is a horizontal sectional view of the vicinity of the Y-shaped control rod 15 of the core 2 in which the vertical guide 24 according to this embodiment is installed. In FIG. 12, the difference from the second embodiment (see FIG. 9) is that a plurality of grooves 30 extending in the vertical direction are provided on the side surface of the vertical guide 24 having a circular horizontal section.

  According to the boiling water reactor 1 in which the vertical guide 24 according to this embodiment is installed, in addition to the same effects as those of the second embodiment, the following effects can be obtained.

  The plurality of grooves 30 provided on the side surface of the vertical guide serve as a coolant flow path, and the flow rate of the coolant flowing in the vicinity of the vertical guide 24 is increased as compared with the second embodiment. As a result, the difference between the flow rate of the coolant flowing in the portion adjacent to the vertical guide 24 and the flow rate of the coolant flowing in the other portion in the outer peripheral portion of the fuel assembly 14 is reduced, and the outer edge portion of the fuel assembly 14 The imbalance of the cooling effect in can be improved. In the present embodiment, four grooves 30 are provided on the side surface of the vertical guide 24. However, the number, position, and the like of the grooves 30 can be changed as appropriate.

  A vertical guide 24 according to a sixth embodiment of the present invention will be described in comparison with the third embodiment. FIG. 13 is a horizontal sectional view of the vicinity of the Y-shaped control rod 15 of the core 2 in which the vertical guide 24 according to the present embodiment is installed. In FIG. 13, the difference from the third embodiment (see FIG. 10) is that a groove 30 extending in the vertical direction is provided on each side surface of the vertical guide 24 having a hexagonal horizontal section.

  According to the boiling water reactor 1 in which the vertical guide 24 according to the present embodiment is installed, the following effects can be obtained in addition to the same effects as the third embodiment.

  The grooves 30 provided on the respective sides of the vertical guide serve as a coolant flow path, and the flow rate of the coolant flowing in the vicinity of the vertical guide 24 is increased as compared with the third embodiment. As a result, the difference between the flow rate of the coolant flowing in the portion adjacent to the vertical guide 24 and the flow rate of the coolant flowing in the other portion in the outer peripheral portion of the fuel assembly 14 is reduced, and the outer edge portion of the fuel assembly 14 The imbalance of the cooling effect in can be improved. In the present embodiment, one groove 30 is provided on each side surface of the vertical guide 24 having a hexagonal horizontal cross section, but the number, position, and the like of the grooves 30 can be changed as appropriate.

  A vertical guide 24 according to a seventh embodiment of the present invention will be described in comparison with the first embodiment. FIG. 14 is a bird's-eye view of the vicinity of the Y-shaped control rod 15 of the core 2 in which the vertical guide 24 according to the present embodiment is installed, and FIG. 15 is a horizontal sectional view thereof. 14 and 15, the difference from the first embodiment (see FIG. 6) is that a thin protective plate 31 that covers the outer periphery of the Y-shaped control rod 15 integrally with the three vertical guides 24. Is attached to the vertical guide 24. As shown in FIG. 14, the protective plate 31 is provided with a plurality of flow path holes 32, and the coolant is circulated through the plurality of flow path holes 32, so that the Y-shaped control rod 15 The wing 19 can be cooled. Note that the number, position, size, and the like of the flow path holes 32 can be changed as appropriate.

  According to the boiling water reactor 1 in which the vertical guide 24 according to the present embodiment is installed, the following effects are obtained in addition to the same effects as the first embodiment.

  When the fuel is initially loaded or when the fuel is changed, the vertical guide 24 and the protective plate 31 are integrated to cover the outer periphery of the Y-shaped control rod 15, so that the fuel assembly 14 moving along the vertical guide 24 is Y-shaped. Contact with the control rod 15 can be prevented, and the Y-shaped control rod 15 can be protected.

  Further, by providing the protective plate 31 between the vertical guides 24, the overall structural strength of the three vertical guides 24 connected by the guide arm 28 is improved. Thereby, the position shift between the insertion portions 25 of the three vertical guides 24 is suppressed, and the insertion portions 25 of the three vertical guides 24 are easily inserted into the three fitting portions 27 of the fuel support fitting 26, respectively. It becomes possible.

  A vertical guide 24 according to an eighth embodiment of the present invention will be described in comparison with the seventh embodiment. FIG. 16 is a horizontal sectional view of the vicinity of the Y-shaped control rod 15 of the core 2 in which the vertical guide 24 according to the present embodiment is installed. In FIG. 16, the difference from the seventh embodiment (see FIG. 15) is that the horizontal section of the vertical guide 24 is circular.

  According to the boiling water reactor 1 provided with the vertical guide 24 according to the present embodiment, in addition to the same effects as those of the seventh embodiment, the following effects can be obtained.

  Since the horizontal cross section of the vertical guide 24 is circular, the vertical guide 24 can be easily manufactured.

  A vertical guide 24 according to a ninth embodiment of the present invention will be described in comparison with the seventh embodiment. FIG. 17 is a horizontal sectional view of the vicinity of the Y-shaped control rod 15 of the core 2 in which the vertical guide 24 according to this embodiment is installed. In FIG. 17, the difference from the seventh embodiment (see FIG. 15) is that the horizontal section of the vertical guide 24 is a hexagon.

  In the boiling water reactor 1 in which the vertical guide 24 according to the present embodiment is installed, the same effect as in the seventh embodiment can be obtained.

  A vertical guide 24 according to a tenth embodiment of the present invention will be described in comparison with the seventh embodiment. FIG. 18 is a horizontal sectional view of the vicinity of the Y-shaped control rod 15 of the core 2 in which the vertical guide 24 according to the present embodiment is installed. In FIG. 18, the difference from the seventh embodiment (see FIG. 15) is that a groove 30 extending in the vertical direction is provided on each side surface of the vertical guide 24 having a square horizontal section.

  According to the boiling water reactor 1 provided with the vertical guide 24 according to the present embodiment, in addition to the same effects as those of the seventh embodiment, the following effects can be obtained.

  The grooves 30 provided on each side surface of the vertical guide serve as a coolant flow path, and the flow rate of the coolant flowing in the vicinity of the vertical guide 24 is increased as compared with the seventh embodiment. As a result, the difference between the flow rate of the coolant flowing in the portion adjacent to the vertical guide 24 and the flow rate of the coolant flowing in the other portion in the outer peripheral portion of the fuel assembly 14 is reduced, and the outer edge portion of the fuel assembly 14 The imbalance of the cooling effect in can be improved. In the present embodiment, one groove 30 is provided on each side surface of the vertical guide 24. However, the number, position, and the like of the grooves 30 can be changed as appropriate.

  A vertical guide 24 according to an eleventh embodiment of the present invention will be described in comparison with the eighth embodiment. FIG. 19 is a horizontal sectional view of the vicinity of the Y-shaped control rod 15 of the core 2 in which the vertical guide 24 according to this embodiment is installed. In FIG. 19, the difference from the eighth embodiment (see FIG. 16) is that a plurality of grooves 30 extending in the vertical direction are provided on the side surface of the vertical guide 24 having a circular horizontal section.

  According to the boiling water reactor 1 provided with the vertical guide 24 according to the present embodiment, in addition to the same effects as those of the eighth embodiment, the following effects can be obtained.

  Since the horizontal cross section of the vertical guide 24 is circular, the vertical guide 24 can be easily manufactured.

  The plurality of grooves 30 provided on the side surface of the vertical guide serve as a coolant flow path, and the flow rate of the coolant flowing in the vicinity of the vertical guide 24 is increased as compared with the eighth embodiment. As a result, the difference between the flow rate of the coolant flowing in the portion adjacent to the vertical guide 24 and the flow rate of the coolant flowing in the other portion in the outer peripheral portion of the fuel assembly 14 is reduced, and the outer edge portion of the fuel assembly 14 The imbalance of the cooling effect in can be improved. In the present embodiment, four grooves 30 are provided on the side surface of the vertical guide 24. However, the number, position, and the like of the grooves 30 can be changed as appropriate.

  A vertical guide 24 according to a twelfth embodiment of the present invention will be described in comparison with the ninth embodiment. FIG. 20 is a horizontal sectional view of the vicinity of the Y-shaped control rod 15 of the core 2 in which the vertical guide 24 according to the present embodiment is installed. 20, the difference from the ninth embodiment (see FIG. 17) is that a groove 30 extending in the vertical direction is provided on each side surface of a vertical guide 24 having a hexagonal horizontal section.

  According to the boiling water reactor 1 provided with the vertical guide 24 according to the present embodiment, in addition to the same effects as those of the ninth embodiment, the following effects can be obtained.

  The grooves 30 provided on each side surface of the vertical guide serve as a coolant flow path, and the flow rate of the coolant flowing in the vicinity of the vertical guide 24 is increased as compared with the ninth embodiment. As a result, the difference between the flow rate of the coolant flowing in the portion adjacent to the vertical guide 24 and the flow rate of the coolant flowing in the other portion in the outer peripheral portion of the fuel assembly 14 is reduced, and the outer edge portion of the fuel assembly 14 The imbalance of the cooling effect in can be improved. In the present embodiment, one groove 30 is provided on each side surface of the vertical guide 24. However, the number, position, and the like of the grooves 30 can be changed as appropriate.

  As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. It is also possible to add a part of the configuration of another embodiment to the configuration of a certain embodiment, and delete a part of the configuration of a certain embodiment or replace it with a part of another embodiment. Is possible.

  DESCRIPTION OF SYMBOLS 1 ... Boiling water reactor (RBWR), 2 ... Core, 3 ... Reactor pressure vessel, 4 ... Steam separator, 5 ... Steam dryer, 6 ... Core shroud, 7 ... Internal pump, 8 ... Turbine, DESCRIPTION OF SYMBOLS 9 ... Main steam piping, 10 ... Feed water piping, 11 ... Generator, 12 ... Condenser, 13 ... Feed water pump, 14 ... Fuel assembly, 15 ... Y-shaped control rod, 16 ... Channel box, 17 ... Fuel rod 18 ... Tie rods, 19 ... wings, 20 ... sheaths, 21 ... neutron absorber tubes, 22 ... neutron absorbers, 23 ... control rod drive devices, 24 ... vertical guides, 25 ... inserts, 26 ... fuel support fittings, 27 DESCRIPTION OF SYMBOLS ... Fitting part, 28 ... Guide arm, 29 ... Empty space, 30 ... Groove, 31 ... Protection plate, 32 ... Channel hole, G1 ... Gap width between fuel assemblies, T1 ... Width of vertical guide, T2 ... Blade Thickness of.

Claims (10)

In a boiling water reactor comprising a densely arranged hexagonal column-shaped fuel assembly and a Y-shaped control rod inserted between three fuel assemblies adjacent to each other,
It extends in the vertical direction between the three fuel assemblies and on the horizontal extension of each of the three blades constituting the Y-shaped control rod, and is larger than the thickness of the blade of the Y-shaped control rod. A boiling water reactor characterized in that a vertical guide having a width can be installed. The boiling water reactor according to claim 1,
The boiling water reactor according to claim 1, wherein the vertical guide has a side surface facing in parallel with a side surface of the closest fuel assembly among the three fuel assemblies. The boiling water reactor according to claim 2,
A boiling water reactor characterized in that a horizontal section of the vertical guide is a quadrangle. The boiling water reactor according to claim 2,
A boiling water reactor characterized in that a horizontal section of the vertical guide is hexagonal. The boiling water reactor according to claim 1,
A boiling water reactor characterized in that a horizontal section of the vertical guide is circular. The boiling water reactor according to claim 1,
A boiling water nuclear reactor comprising a groove extending in a vertical direction on at least one side surface of the vertical guide. The boiling water reactor according to claim 1,
A boiling water nuclear reactor in which a protective plate that is integrated with the vertical guide and covers the outer periphery of the Y-shaped control rod is attached to the vertical guide. The boiling water reactor according to claim 1,
The boiling water reactor according to claim 1, wherein the vertical guide is detachably installed on a fuel support fitting that supports the three fuel assemblies. The boiling water reactor according to claim 8,
The lower end of the vertical guide is provided with an insertion portion formed in a tapered shape,
A boiling water nuclear reactor in which a fitting portion for inserting the insertion portion is provided on an upper surface of the fuel support fitting. The boiling water reactor according to claim 8,
The upper ends of the vertical guides are connected to each other by a trifurcated guide arm,
The height of the vertical guide is set to a height at which the upper end of the vertical guide protrudes above the upper ends of the three fuel assemblies when the vertical guide is installed on the fuel support bracket. Boiling water reactor characterized by.

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