JP2020176911A - Fuel assembly - Google Patents

Abstract

To provide a fuel assembly capable of simplifying an installation work and preventing jumping.SOLUTION: A fuel assembly 10 includes a channel box 21, fuel rods 8, an upper tie plate 22, and a jumping prevention mechanism 30. The upper tie plate 22 is arranged below a lower surface part 4b of an upper grid plate 4. An opening part 21a is formed in the channel box 21. The jumping prevention mechanism 30 includes an operation plate 33, a support part 35, and a stopper part 32. The operation plate 33 is arranged projectingly toward a flow channel 22a and is pressed by a fluid. The stopper part 32 is supported by the support part 35 in a detachable insertion manner into the opening part 21a. Then, the stopper part 32 projects to an outside of the channel box 21 from the opening part 21a to face the lower surface part 4b of the upper grid plate 4 when the operation plate 33 is moved upward.SELECTED DRAWING: Figure 5

Description

The present invention relates to a fuel assembly installed in a nuclear reactor.

A fuel assembly containing a plurality of fuel rods is installed in the pressure vessel of a boiling water reactor. In addition, as a safety measure, the fuel assembly is provided with a mechanism for preventing the fuel assembly from jumping from the installation location due to vertical vibration during an earthquake.

Conventional fuel assemblies of this type include, for example, those described in Patent Document 1. In Patent Document 1, a plurality of fuel rods are provided in a square tubular channel box, an upper tie plate with a handle is provided on the upper part of the fuel rods, and the upper part is horizontally supported by an upper lattice plate of a nuclear reactor. Fuel assemblies are listed. Further, in Patent Document 1, a linear motion guide fixed to the upper tie plate, a locking slider guided by the linear motion guide to move in the horizontal direction, and a locking slider are provided on the side surface of the upper lattice plate. It is described that the slider moving mechanism for inserting and removing the locking hole is provided.

Japanese Unexamined Patent Publication No. 2007-171020

However, in the technique described in Patent Document 1, it is necessary to process the upper lattice plate in order to provide a locking hole into which the locking slider is inserted on the side surface of the upper lattice plate. Further, in the technique described in Patent Document 1, in order to move the locking slider, it is necessary to operate a vertical moving member provided on the handle of the upper tie plate. As a result, in the technique described in Patent Document 1, the work of installing the fuel assembly has become very complicated.

An object of the present invention is to consider the above problems and to provide a fuel assembly capable of simplifying the installation work and preventing jumping.

In order to solve the above problems and achieve the purpose, the fuel assembly includes a hollow tubular channel box, fuel rods, an upper tie plate, and a jump prevention mechanism. The channel box is inserted into the lattice hole of the upper lattice plate installed in the pressure vessel, and the upper end portion in the vertical direction is supported by the upper lattice plate. The fuel rods are housed in the tube holes of the channel box. The upper tie plate is arranged in the tubular hole of the channel box below the lower surface portion in the vertical direction of the upper lattice plate, and has a flow path through which a fluid can pass. The jump-up prevention mechanism is installed in the tube hole of the channel box. An opening is formed between the upper tie plate and the lower surface of the channel box.
Further, the jump-up prevention mechanism has an operating plate, a support portion, and a stopper portion. The actuating plate is arranged overhanging towards the upper tie plate flow path and is pressed by the fluid passing through the flow path. The support portion movably supports the operating plate. The stopper portion faces the opening portion and is detachably supported by the support portion in the opening portion. Then, when the operating plate is pushed upward by the fluid in the vertical direction and moves, the stopper portion projects from the opening to the outside of the channel box and faces the lower surface portion of the upper lattice plate in the vertical direction.

According to the fuel assembly having the above configuration, it is possible to simplify the installation work and prevent jumping.

It is a schematic block diagram which shows the pressure vessel of the nuclear reactor provided with the fuel assembly which concerns on the 1st Embodiment example. It is a top view which shows the installation state of the fuel assembly in the nuclear reactor which concerns on the 1st Embodiment example. It is sectional drawing which shows the fuel assembly which concerns on the example of 1st Embodiment. It is explanatory drawing which shows the lower part of the fuel assembly which concerns on the 1st Embodiment example. It is sectional drawing which shows the upper part of the fuel assembly which concerns on the 1st Embodiment example. It is a top view which shows the fuel assembly which concerns on the 1st Embodiment example. It is a perspective view which shows the jumping prevention mechanism in the fuel assembly which concerns on the 1st Embodiment example. It is a top view which shows the jumping prevention mechanism of the fuel assembly which concerns on the 1st Embodiment example. FIG. 9A shows a cross-sectional view taken along the line CC of FIG. 8, FIG. 9B is a cross-sectional view taken along the line DD of FIG. 8, and FIG. 9C shows a jump-up prevention mechanism of the fuel assembly according to the first embodiment. 8 is a cross-sectional view taken along the line EE of FIG. It is explanatory drawing which shows the operation example of the jump-up prevention mechanism of the fuel assembly which concerns on the 1st Embodiment example from the released state to the locked state. It is sectional drawing which shows the fuel assembly in which the jumping prevention mechanism which concerns on the 1st Embodiment example is locked. It is a top view which shows the fuel assembly in which the jumping prevention mechanism which concerns on the 1st Embodiment example is locked. FIG. 5 is a cross-sectional view showing a state in which the fuel assembly has moved upward in the vertical direction when the jump prevention mechanism according to the first embodiment is locked. It is explanatory drawing which shows the operation example of the jumping prevention mechanism in the fuel assembly which concerns on the 1st Embodiment example from the locked state to the released state. It is explanatory drawing which shows the installation work of the fuel assembly which concerns on the 1st Embodiment example. It is a perspective view which shows the rotating member of the jumping prevention mechanism in the fuel assembly which concerns on 2nd Embodiment example. It is a perspective view which shows the bearing part of the jumping prevention mechanism of the fuel assembly which concerns on the 3rd Embodiment example. It is a top view which shows the jumping prevention mechanism of the fuel assembly which concerns on 4th Embodiment example. The jump-up prevention mechanism of the fuel assembly according to the fourth embodiment is shown, FIG. 19A is a sectional view taken along line I-I of FIG. 18, FIG. 19B is a sectional view taken along line JJ of FIG. 18, and FIG. 19C is a sectional view taken along line JJ. FIG. 8 is a cross-sectional view taken along the line KK of FIG. An operation example of the fuel assembly jump prevention mechanism according to the fourth embodiment is shown. FIG. 20A shows the operation from the unlocked state to the locked state, and FIG. 20B shows the operation from the locked state to the unlocked state. Shown. FIG. 21A is a cross-sectional view showing a jump-up prevention mechanism of the fuel assembly according to the fifth embodiment, FIG. 21A is a cross-sectional view showing a release state of the jump-up prevention mechanism, and FIG. 21B shows a locked state of the jump-up prevention mechanism. It is a sectional view. The jump-up prevention mechanism of the fuel assembly according to the fifth embodiment is shown, FIG. 22A is a sectional view taken along line LL of FIG. 21A, and FIG. 22B is a sectional view taken along line MM of FIG. 21A.

Hereinafter, the fuel assembly according to the embodiment will be described with reference to FIGS. 1 to 22. The common members in each figure are designated by the same reference numerals.

1. 1. First Embodiment Example First, the configuration of the fuel assembly according to the first embodiment (hereinafter referred to as “this example”) will be described with reference to FIGS. 1 to 15.
FIG. 1 is a cross-sectional view showing a pressure vessel provided with a fuel assembly, and FIG. 2 is a plan view showing an installed state of the fuel assembly.

1-1. Configuration Example of Pressure Vessel The fuel assembly shown in FIG. 1 is installed in the pressure vessel of a nuclear reactor composed of a boiling water reactor. As shown in FIG. 1, the pressure vessel is formed in a cylindrical shape such as stainless steel. The pressure vessel 1 is filled with reactor water such as a reactor coolant and a water reducing material. The core 2 is immersed in this reactor water. The core 2 is located below the central portion of the pressure vessel 1 in the height direction.

In the core 2 in the pressure vessel 1, a plurality of fuel assemblies 10, a cross-shaped control rod 3, an upper lattice plate 4 and a core support plate 5 for supporting the fuel assembly 10, and a neutron instrumentation pipe 6 are provided. Have. The upper lattice plate 4 is arranged in the upper part in the vertical direction in the core 2, and the core support plate 5 is arranged in the lower part in the vertical direction in the core 2. The upper grid plate 4 supports the upper part of the fuel assembly 10 in the vertical direction, and the core support plate 5 supports the lower part of the fuel assembly 10 in the vertical direction.

As shown in FIG. 2, the upper lattice plate 4 has a plurality of lattice holes 4a opened in a rectangular shape and is formed in a lattice shape. In this example, four fuel assemblies 10 are installed in one lattice hole 4a of the upper lattice plate 4. The upper lattice plate 4 has a role of guiding and positioning when the fuel assembly 10 is loaded into the core 2.

A clip 14 for fixing the channel box 21 and the upper tie plate 22, which will be described later, is attached to the upper part of the fuel assembly 10 in the vertical direction. A cross-shaped control rod 3 is arranged in the center of the four fuel assemblies 10 arranged on the upper grid plate 4.

Further, a channel fastener 15 and a spring 16 are provided at a corner portion on the center side of the cross-shaped control rod 3 in the fuel assembly 10. The channel fastener 15 and the spring 16 are arranged so as to be stacked above the clip 14 attached to the fuel assembly 10 in the vertical direction. Further, a channel spacer 17 is provided between the upper part of the fuel assembly 10 and the adjacent fuel assembly 10. The channel fastener 15 and the spring 16 urge the four fuel assemblies 10 so as to be separated from each other in the horizontal direction. The channel fastener 15, the spring 16, and the channel spacer 17 prevent the fuel assemblies 10 from coming into contact with each other.

FIG. 3 is a cross-sectional view showing the fuel assembly 10, and FIG. 4 is an explanatory view showing a lower portion of the fuel assembly 10.
As shown in FIGS. 3 and 4, the core support plate 5 is provided with the fuel support metal fitting 18. A plurality of (four in this example) mounting holes 18a and control rod moving holes 18b are formed in the fuel support metal fitting 18. The mounting portion 24a of the lower tie plate 24 described later in the fuel assembly 10 is fitted into the mounting hole 18a. Then, the fuel support metal fitting 18 supports the lower portion of the fuel assembly 10.

The control rod moving holes 18b are formed in the center of the plurality of mounting holes 18a. A cross-shaped control rod 3 (see FIG. 2) is movably inserted into the control rod moving hole 18b in the vertical direction.

The upper end of the neutron instrumentation pipe 6 is fixed to the upper grid plate 4, and extends downward from the upper grid plate 4 in the vertical direction. The neutron instrumentation pipe 6 penetrates the core support plate 5.

1-2. Configuration Example of Fuel Assembly Next, a configuration example of the fuel assembly 10 will be described with reference to FIGS. 2 to 6.
FIG. 5 is a cross-sectional view showing the upper part of the fuel assembly 10, and FIG. 6 is a plan view showing the fuel assembly 10. Note that FIG. 5 is a cross-sectional view taken along the line BB shown in FIG.

As shown in FIGS. 2 and 3, the fuel assembly 10 includes a plurality of fuel rods 8, a channel box 21 accommodating the fuel rods 8, an upper tie plate 22, a lower tie plate 24, and a handle 23. It includes a spacer 25 and a support rod 27. Further, the fuel assembly 10 includes two jump-up prevention mechanisms 30 and 30.

The channel box 21 is formed in a hollow square cylinder shape in which the upper end and the lower end in the vertical direction are open. A plurality of fuel rods 8, an upper tie plate 22, a spacer 25, a support rod 27, and a jump prevention mechanism 30 are arranged in the channel box 21. Further, as shown in FIGS. 3 and 4, a lower tie plate 24 is attached to the lower end of the channel box 21.

A mounting portion 24a is formed at the lower end portion of the lower tie plate 24 in the vertical direction. The mounting portion 24a projects downward in the vertical direction. The mounting portion 24a is fitted into the mounting hole 18a formed in the fuel support metal fitting 18. Then, the channel box 21 is erected from the fuel support metal fitting 18 in the vertical direction. Therefore, the channel box 21 is arranged so that its axial direction is parallel to the vertical direction.

In addition, two support rods 27 integrated with fuel rods are arranged at each of the four corners of the channel box 21. As shown in FIG. 3, the lower end of the support rod 27 is fixed to the lower tie plate 24 and stands substantially parallel to the vertical direction. An upper tie plate 22 and a plurality of spacers 25 are fixed to the support rod 27. The plurality of spacers 25 are arranged at predetermined intervals in the axial direction of the support rod 27.

The upper tie plate 22 is fixed to the upper end portion of the support rod 27 in the vertical direction. The upper tie plate 22 is installed at the upper end of the channel box 21 in the vertical direction. Further, when the fuel assembly 10 is installed on the core support plate 5 and the upper grid plate 4, the upper tie plate 22 is arranged below the lower surface portion 4b of the upper grid plate 4 in the vertical direction. An opening 21a is formed between the upper tie plate 22 in the channel box 21 and the lower surface portion 4b of the upper lattice plate 4. The opening 21a is formed on the surface of the channel box 21 facing the wall surface of the lattice hole 4a of the upper lattice plate 4.

As shown in FIGS. 5 and 6, the upper tie plate 22 is formed in a substantially flat rectangular shape. Further, the upper tie plate 22 is formed with a flow path 22a having a rectangular opening. A fluid such as furnace water or steam passes through the flow path 22a. A handle 23 and a jump-up prevention mechanism 30 are installed on the upper surface of the upper tie plate 22 in the vertical direction.

The handle 23 has a leg portion 23a and a grip portion 23b. The leg portion 23a is fixed to the upper surface of the upper tie plate 22 and is erected upward in the vertical direction. A grip portion 23b is continuously provided at the upper end portion of the leg portion 23a in the vertical direction. When the fuel assembly 10 is installed on the core support plate 5 and the upper grid plate 4, the grip portion 23b is located above the upper grid plate 4 in the vertical direction.

As described above, in this example, the upper tie plate 22 is arranged below the upper lattice plate 4, but by extending the length of the leg portion 23a of the handle 23, the position of the grip portion 23b is moved upward. It can be arranged above the lattice plate 4 in the vertical direction. As a result, even when the fuel assembly 10 of this example is replaced with an existing fuel assembly whose upper tie plate is arranged above the upper lattice plate 4, the height of the handle 23 is changed to the existing fuel assembly. It can be as high as the height of the handle. As a result, it becomes possible to use the refueling machine used in the existing nuclear reactor.

1-3. Jump-up prevention mechanism Next, a configuration example of the jump-up prevention mechanism 30 will be described with reference to FIGS. 5 to 9.
As shown in FIGS. 5 and 6, the jump-up prevention mechanism 30 is arranged at the edge of the flow path 22a on the upper surface of the upper tie plate 22. Further, the jump-up prevention mechanism 30 is arranged at a position facing the opening 21a provided in the channel box 21. That is, the jump-up prevention mechanism 30 is arranged at a position facing the wall surface of the lattice hole 4a of the upper lattice plate 4 in the channel box 21.

7 is a perspective view showing the jump-up prevention mechanism 30, FIG. 8 is a plan view showing the jump-up prevention mechanism 30, FIG. 9A is a sectional view taken along line CC of FIG. 8, and FIG. 9B is a sectional view taken along line DD of FIG. FIG. 9C is a sectional view taken along line EE of FIG.

As shown in FIGS. 7 to 9C, the jump-up prevention mechanism 30 includes a rotating member 31, two rotating shafts 34 and 34, two support portions 35 and 35, a first stopper 36, and a second stopper. It has 38 and.

The rotating member 31 showing an example of the movable member is formed in a substantially L shape. The rotating member 31 has a stopper portion 32 and an operating plate 33. The operating plate 33 is formed in a substantially flat plate shape. The stopper portion 32 is substantially vertically continuous from the end portion of the operating plate 33. The operating plate 33 is designed to be thicker than the stopper portion 32 and to have a heavier mass than the stopper portion 32. A rotating shaft 34 is provided at a corner of the rotating member 31 where the operating plate 33 and the stopper 32 are connected.

The rotating shaft 34 has both ends in a direction (hereinafter referred to as a width direction) orthogonal to each of a direction in which the operating plate 33 of the rotating member 31 protrudes from the stopper portion 32 and a direction in which the stopper portion 32 protrudes from the operating plate 33. It is provided in.

The two support portions 35, 35 showing an example of the support portion are arranged on both sides of the rotating member 31 in the width direction. Then, the two support portions 35, 35 are installed on the upper surface of the upper tie plate 22. Further, the two support portions 35, 35 are arranged in the vicinity of the opening 21a of the channel box 21. A rotation shaft 34 provided on the rotation member 31 is inserted into the bearing portion 39 (see FIGS. 8 and 9D) of the support portion 35. Then, the support portion 35 rotatably supports the rotating member 31 via the rotating shaft 34 and the bearing portion 39.

As shown in FIGS. 8, 9A, 9B, and 9C, when the rotating member 31 is supported by the support portion 35, the operating plate 33 projects from the upper surface of the upper tie plate 22 toward the flow path 22a. ing. The operating plate 33 is pressed by a fluid such as furnace water or steam that passes through the flow path 22a. At this time, the stopper portion 32 is erected upward in the vertical direction and faces the opening portion 21a of the channel box 21. Then, the stopper portion 32 is removably arranged in the opening portion 21a by the support portion 35.

The first stopper 36 is arranged between the support portion 35 and the inner wall surface of the channel box 21. When the rotating member 31 rotates, the rotating member 31 comes into contact with the first stopper 36.

Further, the second stopper 38 is arranged between the two support portions 35, 35. Then, in the state before the rotating member 31 rotates, the rotating member 31 supported by the two supporting portions 35, 35 comes into contact with the second stopper 38. As a result, the second stopper 38 regulates the rotational operation of the operating plate 33 of the rotating member 31 in the direction in which the operating plate 33 hangs down in the vertical direction.

1-4. Example of operation from the released state to the locked state in the jump prevention mechanism Next, an operation example from the released state to the locked state in the jump prevention mechanism 30 having the above-described configuration will be described with reference to FIG.
FIG. 10 is an explanatory diagram showing an operation example of the jump-up prevention mechanism 30 from the released state to the locked state.
The state shown in FIGS. 9A to 9D in the jump-up prevention mechanism 30 is referred to as a release state.

During operation of the nuclear reactor, as shown in FIG. 10, fluids such as furnace water and steam flow upward in the vertical direction in the tubular hole of the channel box 21. This fluid passes through the flow path 22a of the upper tie plate 22 provided above the channel box 21. Then, the fluid passing through the flow path 22a comes into contact with the operating plate 33 of the rotating member 31 overhanging the flow path 22a, and then flows into the space at the upper end of the channel box 21 in the vertical direction. Therefore, the operating plate 33 is pressed upward by the fluid in the vertical direction.

At this time, the fluid force (hereinafter, fluid force) Fa that presses the operating plate 33 is the flow velocity Va of the fluid calculated from the flow rate and the flow path area in the tubular hole of the channel box 21, and the density ρa of the fluid. It can be calculated from the area S of the lower surface of the plate 33. Then, due to the fluid force Fa and the distance La from the rotating shaft 34 to the center of gravity Ca on the operating plate 33 side of the rotating member 31, a rotational moment centered on the rotating shaft 34 acts on the rotating member 31. As a result, as shown by the arrow shown in FIG. 10, the rotating member 31 rotates in the direction in which the operating plate 33 stands upward in the vertical direction.

Further, the rotating member 31 rotates in the direction in which the operating plate 33 stands upward in the vertical direction, so that the stopper portion 32 rotates in the direction approaching the opening 21a of the channel box 21. Then, when the stopper portion 32 comes into contact with the first stopper 36, the rotation operation of the rotating member 31 is stopped. As a result, the operation of the jump-up prevention mechanism 30 from the released state shown in FIGS. 9A to 9D to the locked state is completed.

According to the jump-up prevention mechanism 30 of this example, the rotating member 31 can be rotated by the fluid flowing in the channel box 21, and the jump-up prevention mechanism 30 can be easily operated from the released state to the locked state.

1-5. Locked state of the jump-up prevention mechanism Next, the locked state of the jump-up prevention mechanism 30 having the above-described configuration will be described with reference to FIGS. 11 to 13.
FIG. 11 is a cross-sectional view showing the fuel assembly 10 in which the jump-up prevention mechanism 30 is in the locked state, and FIG. 12 is a plan view showing the fuel assembly 10 in which the jump-up prevention mechanism 30 is in the locked state. Note that FIG. 11 is a cross-sectional view taken along the line HH shown in FIG.

As shown in FIGS. 11 and 12, when the rotating member 31 rotates and the jump-up prevention mechanism 30 operates in the locked state, the stopper portion 32 is inserted into the opening 21a provided in the channel box 21. Further, the stopper portion 32 projects from the opening 21a toward the outside of the outer wall of the channel box 21. Then, the stopper portion 32 faces the lower surface portion 4b of the upper lattice plate 4 in the vertical direction. On the horizontal projection surface, the stopper portion 32 overlaps with the lower surface portion 4b of the upper grid plate 4.

Further, the rotating member 31 is rotated by the moment generated by the fluid force Fa, and the operating plate 33 is erected upward in the vertical direction. Therefore, in the locked state, the operating plate 33 does not project toward the flow path 22a of the upper tie plate 22.

FIG. 13 is a cross-sectional view showing a state in which the fuel assembly 10 has moved upward in the vertical direction when the jump-up prevention mechanism 30 is in the locked state.
As shown in FIG. 13, when the fuel assembly 10 moves upward in the vertical direction due to an earthquake, the stopper portion 32 protruding from the opening 21a of the channel box 21 comes into contact with the lower surface portion 4b of the upper lattice plate 4. As a result, the upward movement of the fuel assembly 10 in the vertical direction is stopped, and further movement is restricted. As a result, it is possible to prevent the upper lattice plate 4 from jumping out of the lattice holes 4a in the fuel assembly 10.

Further, as shown in FIG. 11, in the locked state, the length L from the stopper portion 32 to the lower surface portion 4b of the upper lattice plate 4 is the length L to the mounting hole 18a in the mounting portion 24a of the lower tie plate 24 shown in FIG. It is set shorter than the fitting length H. As a result, even when the fuel assembly 10 moves upward, it is possible to prevent the mounting portion 24a from completely coming out of the mounting hole 18a.

When the earthquake has converged and the movement of the fuel assembly 10 in the vertical direction is stopped, the mounting portion 24a is automatically fitted into the mounting hole 18a due to the weight of the fuel assembly 10. As a result, the support state of the fuel assembly 10 in the fuel support metal fitting 18 can be maintained. As a result, it is possible to shorten the time required for the inspection work of the fuel assembly 10 during the restoration work of the nuclear reactor after the occurrence of the earthquake.

1-6. Example of operation from the locked state to the released state in the jump prevention mechanism Next, an operation example from the locked state to the released state in the jump prevention mechanism 30 having the above-described configuration will be described with reference to FIG.
FIG. 14 is an explanatory diagram showing an operation example of the jump-up prevention mechanism 30 from the locked state to the released state.

When the operation of the reactor is stopped, the vertical upward flow of fluids such as reactor water and steam also stops. Then, the fluid force that presses the operating plate 33 of the jump-up prevention mechanism 30 is also reduced or eliminated. Therefore, as shown in FIG. 14, the rotating member 31 rotates about the rotating shaft 34 due to the weight of the operating plate 33. Then, the rotating member 31 returns to the released state shown in FIGS. 9A to 9C and the like.

Further, the first distance La from the rotating shaft 34 to the center of gravity Ca of the operating plate 33 is set longer than the second distance Lb from the rotating shaft 34 to the center of gravity Cb of the stopper portion 32. Further, the mass of the operating plate 33 is set to be heavier than the mass of the stopper portion 32. Therefore, the magnitude of the moment around the rotation shaft 34 generated by the own weight of the operating plate 33 and the first distance La (hereinafter, referred to as "actuating plate side moment") is the own weight of the stopper portion 32 and the second It is larger than the magnitude of the moment (hereinafter, referred to as “stopper side moment”) around the rotation shaft 34 generated by the distance Lb.

Due to this difference in moment, the rotating member 31 rotates in the direction in which the stopper portion 32 separates from the opening 21a as shown by the arrow shown in FIG. That is, the rotating member 31 rotates in the direction in which the operating plate 33 hangs down in the vertical direction. Then, when the operating plate 33 comes into contact with the second stopper 38 (FIGS. 9B and 9C), the rotating operation of the rotating member 31 is stopped. As a result, the operating plate 33 again projects toward the flow path 22a of the upper tie plate 22. As a result, the operation of the jump-up prevention mechanism 30 from the locked state to the released state is completed.

As described above, according to the jump-up prevention mechanism 30 of this example, the rotating member 31 is formed by the difference between the own weight of the operating plate 33 and the stopper portion 32 and the moment obtained by the distance to the center of gravity without any human operation. It can be automatically returned to the released state.

In the jump-up prevention mechanism 30 of this example, in order to make the operating plate side moment larger than the stopper portion side moment, the first distance La is set longer than the second distance Lb, and the operating plate 33 is set to the stopper portion. An example in which the setting is heavier than 32 has been described, but the present invention is not limited to this. That is, if the operating plate side moment is larger than the stopper portion side moment, the first distance La may be set shorter than the second distance Lb, or the mass of the operating plate 33 may be set to be smaller than the mass of the stopper portion 32. You may set it lightly.

Further, an elastic member such as a torsion coil spring may be provided on the rotating shaft 34, and the locked state may be returned to the released state by the elastic force of the elastic member.

1-7. Example of Installation Work of Fuel Assembly Next, an example of installation work of the fuel assembly 10 having the above-described configuration will be described with reference to FIGS. 15A to 15C.
15A to 15C are explanatory views showing an example of installation work of the fuel assembly 10.

First, the handle 23 is gripped by a refueling machine (not shown), and the fuel assembly 10 is suspended. Then, as shown in FIG. 15A, the fuel assembly 10 is inserted into the lattice hole 4a of the upper lattice plate 4 from above in the vertical direction. Then, the fuel assembly 10 is lowered in the vertical direction.

At this time, the fluid comes into contact with the operating plate 33 of the jump-up prevention mechanism 30 from below in the vertical direction and presses against it. Therefore, as in the operation of the nuclear reactor, a force acting relatively upward from the fluid in the vertical direction acts on the operating plate 33. As a result, the rotating member 31 rotates around the rotating shaft 34 in the direction in which the operating plate 33 is erected, and the stopper portion 32 is inserted into the opening 21a of the channel box 21. Then, the stopper portion 32 projects from the opening 21a to the outside of the channel box 21.

When the fuel assembly 10 is further moved downward, as shown in FIG. 15B, the stopper portion 32 protruding from the opening 21a of the channel box 21 comes into contact with the upper surface portion 4c of the upper lattice plate 4. Then, when the fuel assembly 10 is further moved downward, the stopper portion 32 is pressed by the upper surface portion 4c of the upper lattice plate 4. Therefore, the rotating member 31 rotates around the rotating shaft 34 in the direction in which the stopper portion 32 separates from the opening 21a.

Then, as shown in FIGS. 3 and 4, the mounting portion 24a of the lower tie plate 24 is fitted into the mounting hole 18a of the fuel support metal fitting 18. As a result, the installation work of the fuel assembly 10 is completed.

As described above, according to the fuel assembly 10 of this example, the rotating member 31 of the jump-up prevention mechanism 30 automatically rotates when it comes into contact with the fluid or the upper lattice plate 4. Therefore, the jump-up prevention mechanism 30 does not affect the installation work of the fuel assembly 10, and the installation work of the fuel assembly 10 can be easily performed.

Further, it is not necessary to process a member other than the fuel assembly 10 such as the upper lattice plate 4 and the fuel support metal fitting 18. Then, as described above, the fuel assembly 10 can be installed simply by inserting the fuel assembly 10 into the lattice hole 4a of the upper lattice plate 4. Therefore, the installation work of the fuel assembly 10 can be simplified. In addition, it is possible to easily prevent the fuel assembly 10 from jumping up by simply installing the fuel assembly 10 of this example in an existing nuclear reactor.

Further, by checking the rotational operation of the rotating member 31 in the jump-up prevention mechanism 30 before installing the fuel assembly 10, it is possible to prevent the jump-up prevention mechanism 30 from malfunctioning after the fuel assembly 10 is installed. be able to.

When the fuel assembly 10 is pulled up from the upper lattice plate 4 and the fuel support fitting during the replacement or inspection work of the fuel assembly 10, the upper surface of the operating plate 33 is pressed downward by the fluid in the vertical direction. .. Therefore, the stopper portion 32 does not protrude outward from the opening 21a of the channel box 21. That is, the fuel assembly 10 can be pulled up with the jump-up prevention mechanism 30 released, and the stopper portion 32 can be prevented from being caught by the upper lattice plate 4 or other members. As a result, the fuel assembly 10 can be easily replaced and inspected.

2. Second Embodiment Example Next, the fuel assembly according to the second embodiment will be described with reference to FIG.
FIG. 16 is a perspective view showing a rotating member of the jump-up prevention mechanism in the fuel assembly according to the second embodiment.

The difference between the fuel assembly according to the second embodiment and the fuel assembly 10 according to the first embodiment is the configuration of the rotating member of the jump prevention mechanism. Therefore, the rotating member will be described here, and the same reference numerals are given to the parts common to the fuel assembly according to the first embodiment, and duplicate description will be omitted.

As shown in FIG. 16, the rotating member 41 is formed in a substantially L shape. The rotating member 41 has a stopper portion 42 and an operating plate 43. Further, rotating shafts 44 are provided at both ends of the rotating member 41 in the width direction. Since the configurations of the stopper portion 42 and the rotating shaft 44 are the same as those of the stopper portion 32 and the rotating shaft 34 according to the first embodiment, the description thereof will be omitted.

The operating plate 43 is formed in a substantially flat plate shape. A partition wall 43a is formed on the lower surface of the operating plate 43 in the vertical direction. The partition wall 43a projects downward from the lower surface of the operating plate 43 in the vertical direction. The partition wall 43a is formed continuously from the four sides of the lower surface portion of the operating plate 43.

A fluid such as furnace water or steam that has passed through the tubular hole of the channel box 21 and the flow path 22a of the upper tie plate 22 comes into contact with the space surrounded by the partition wall 43a. By receiving the fluid by the partition wall 43a in this way, the rotating member 41 can be reliably rotated.

Since other configurations are the same as those of the fuel assembly 10 according to the first embodiment, the description thereof will be omitted. A fuel assembly provided with a jump-up prevention mechanism having such a rotating member 41 can also obtain the same effect as the fuel assembly 10 according to the first embodiment described above.

In the rotating member 41 according to the second embodiment, an example in which the partition wall 43a is provided so as to surround the lower surface portion of the operating plate 43 has been described, but the present invention is not limited to this. The partition wall 43a may be provided only at one place on the lower surface portion of the operating plate 43, or only a part of the lower surface portion may be opened.

3. 3. Example of Third Embodiment Next, the fuel assembly according to the third embodiment will be described with reference to FIGS. 17A to 17C.
17A to 17C are perspective views showing a bearing portion of the jump-up prevention mechanism in the fuel assembly according to the third embodiment.

As shown in FIGS. 17A to 17C, the jump-up prevention mechanism according to the third embodiment is applied with a rolling bearing portion 39A having a plurality of rolling elements 39b as the bearing portion. As shown in FIG. 17A, the rolling bearing portion 39A is attached to the support portion 35A. Then, as shown in FIGS. 17B and 17C, the rotating shaft 34 is rotatably supported by the rolling bearing portion 39A.

Since other configurations are the same as those of the fuel assembly 10 according to the first embodiment, the description thereof will be omitted. A fuel assembly provided with a jump-up prevention mechanism having such a rolling bearing portion 39A can also obtain the same action and effect as the fuel assembly 10 according to the above-described first embodiment.

According to the jump-up prevention mechanism according to the third embodiment, by using the rolling bearing portion 39A as the bearing portion, the friction generated between the rolling shaft and the rotating shaft 34 can be reduced. As a result, the rotating shaft 34 can be easily rotated, the rotating member can be reliably rotated, and the stopper portion can be reliably moved.

4. Example of Fourth Embodiment Next, the fuel assembly according to the fourth embodiment will be described with reference to FIGS. 18 to 20B.
FIG. 18 is a plan view showing a jump-up prevention mechanism of the fuel assembly according to the fourth embodiment. 19A is a sectional view taken along line II of FIG. 18, FIG. 19B is a sectional view taken along line JJ of FIG. 18, and FIG. 19C is a sectional view taken along line KK of FIG. 20A and 20B are explanatory views showing an operation example of the jump-up prevention mechanism.

The difference between the fuel assembly according to the fourth embodiment and the fuel assembly 10 according to the first embodiment is the configuration of the jump prevention mechanism. Therefore, the jump-up prevention mechanism will be described here, and the same reference numerals are given to the parts common to the fuel assembly according to the first embodiment, and duplicate description will be omitted.

As shown in FIGS. 18 to 19C, the jump-up prevention mechanism 50 is installed on the upper surface of the upper tie plate 22. The jump-up prevention mechanism 50 has a movable member 51, a pair of first sliding portions 54a and 54a, a pair of second sliding portions 54b and 54b, and two support portions 55 and 55.

The movable member 51 is formed in a substantially L shape, similarly to the rotating member 31 according to the first embodiment. The movable member 51 has a stopper portion 52 and an operating plate 53. Since the other configuration of the movable member 51 is the same as that of the rotating member 31 according to the first embodiment, the description thereof will be omitted.

Further, a first sliding portion 54a and a second sliding portion 54b are provided at both ends of the movable member 51 in the width direction. The first sliding portion 54a is provided at the end portion of the movable member 51 on the stopper portion 52 side. The second sliding portion 54b is provided on the operating plate 33 side of the movable member 51 with respect to the first sliding portion 54a.

The two support portions 55, 55 are arranged on both sides of the movable member 51 in the width direction. The two support portions 55 are installed on the upper surface portion of the upper tie plate 22. A first sliding groove 55a and a second sliding groove 55b are formed in the support portion 55.

The first sliding groove 55a and the second sliding groove 55b are grooves in which the support portion 55 is cut out in an arc shape, respectively. One end of the first sliding groove 55a and the second sliding groove 55b is formed close to the flow path 22a and the upper surface portion of the upper tie plate 22, and is formed of the first sliding groove 55a and the second sliding groove 55b. The other end is formed close to the opening 21a of the channel box 21. Further, the first sliding groove 55a and the second sliding groove 55b are formed on concentric circles. The second sliding groove 55b is formed on the outer side in the radial direction of the first sliding groove 55a.

The first sliding groove 55a slidably supports the first sliding portion 54a, and the second sliding groove 55b slidably supports the second sliding portion 54b. As a result, the movable member 51 is movably supported by the two support portions 55. At this time, the entire operating plate 53 overhangs the flow path 22a of the upper tie plate 22. Therefore, the fluid that has passed through the flow path 22a comes into contact with the entire lower surface of the operating plate 53.

As shown in FIG. 20A, when the operating plate 53 is pressed upward in the vertical direction by the fluid passing through the flow path 22a, the first sliding portion 54a slides along the first sliding groove 55a. , The second sliding portion 54b slides along the second sliding groove 55b. Therefore, as shown by the arrow shown in FIG. 20A, the movable member 51 moves in the direction in which the operating plate 53 is separated from the upper surface of the upper tie plate 22 and the stopper portion 52 is inserted into the opening 21a.

When the first sliding portion 54a and the second sliding portion 54b come into contact with the other ends of the first sliding groove 55a and the second sliding groove 55b, the movement of the movable member 51 is stopped. Then, the operating plate 53 is erected upward in the vertical direction. Further, the stopper portion 52 projects from the opening 21a toward the outside of the channel box 21. As a result, the jump-up prevention mechanism 50 shifts from the released state to the locked state.

In addition, when the operation of the reactor is stopped, the upward flow of the fluid in the vertical direction also stops. Therefore, the fluid force that presses the operating plate 53 is also reduced or eliminated. Therefore, as shown in FIG. 20B, the movable member 51 moves in a direction in which the stopper portion 52 separates from the opening 21a due to the difference in mass between the operating plate 53 and the stopper portion 52. That is, the first sliding portion 54a and the second sliding portion 54b slide from the other end of the first sliding groove 55a and the second sliding groove 55b toward one end.

When the first sliding portion 54a and the second sliding portion 54b come into contact with one end of the first sliding groove 55a and the second sliding groove 55b, the movement of the movable member 51 is stopped. As a result, the movable member 51 returns from the locked state to the released state.

Since other configurations are the same as those of the fuel assembly 10 according to the first embodiment, the description thereof will be omitted. A fuel assembly provided with such a jump-up prevention mechanism 50 can also obtain the same effect as the fuel assembly 10 according to the first embodiment described above.

According to the jump-up prevention mechanism 50 according to the fourth embodiment, the movable member 51 can be easily designed in the moving direction according to the shapes of the first sliding groove 55a and the second sliding groove 55b. Can be done. Therefore, not only the lower surface of the operating plate 53 but also the entire lower surface of the movable member 51 in the vertical direction can be projected to the flow path 22a of the upper tie plate 22. As a result, the force with which the fluid presses the movable member 51 can be increased, and the movable member 51 can be reliably moved.

5. Example of Fifth Embodiment Next, the fuel assembly according to the fifth embodiment will be described with reference to FIGS. 21A to 22B.
21A and 21B are cross-sectional views showing a jump-up prevention mechanism of the fuel assembly according to the fifth embodiment, FIG. 21A shows a released state, and FIG. 21B shows a locked state. 22A is a sectional view taken along line LL of FIG. 21A, and FIG. 22B is a sectional view taken along line MM of FIG. 21B.

The difference between the fuel assembly according to the fifth embodiment and the fuel assembly 10 according to the first embodiment is the configuration of the jump prevention mechanism. Therefore, the jump-up prevention mechanism will be described here, and the same reference numerals are given to the parts common to the fuel assembly according to the first embodiment, and duplicate description will be omitted.

As shown in FIGS. 21A, 22A and 22B, the jump-up prevention mechanism 70 is installed on the upper surface of the upper tie plate 22. The jump-up prevention mechanism 70 includes an operating plate 71, an operating support portion 72, a stopper support portion 74, a stopper portion 75, a rotation support portion 76, a transmission member 77, and an elastic member 78. ..

The operating plate 71 is formed in a substantially flat plate shape. The operating plate 71 is placed on the upper surface of the upper tie plate 22 in a state where a part thereof projects into the flow path 22 a of the upper tie plate 22. Further, two actuating protrusions 73, 73 are provided on the upper surface of the actuating plate 71. The actuating protrusions 73 are formed on both sides of the actuating plate 71 in the width direction. The actuating protrusion 73 projects upward from the upper surface portion in the vertical direction. A plurality of sliding holes 71a are formed in the operating plate 71. The sliding hole 71a penetrates from the upper surface portion to the lower surface portion of the operating plate 71.

The actuating support portion 72 is formed in a substantially flat plate shape, and a plurality of leg portions 72a are provided on the lower surface portion of the actuating support portion 72. The plurality of leg portions 72a project downward from the lower surface portion of the operation support portion 72 in the vertical direction. The plurality of legs 72a are installed on the upper surface of the upper tie plate 22. Therefore, the actuating support portions 72 are arranged at intervals above the upper surface portion of the upper tie plate 22 via the plurality of leg portions 72a.

Further, the leg portion 72a is inserted with the sliding hole 71a of the operating plate 71. Therefore, the actuating plate 71 is arranged between the upper surface portion of the upper tie plate 22 and the actuating support portion 72. Then, the actuating plate 71 is movably supported in the vertical direction by the leg portions 72a of the actuating support portion 72.

Two through holes 72b and 72b are formed in the operation support portion 72. Through holes 72b are formed on both sides of the operating support portion 72 in the width direction. The through hole 72b penetrates from the upper surface portion to the lower surface portion of the operation support portion 72. An actuating protrusion 73 provided on the actuating plate 71 is inserted into the through hole 72b.

Further, a rotation support portion 76 is installed on the upper surface portion of the operation support portion 72. The rotation support portion 76 is arranged between the two through holes 72b and 72b formed in the operation support portion 72 on the inner wall surface side of the channel box 21 with respect to the through holes 72b. The rotation support portion 76 rotatably supports the rotation shaft 80 provided on the transmission member 77 described later. Further, a stopper support portion 74 is installed on the upper surface portion of the rotation support portion 76.

The stopper support portion 74 is supported by the rotation support portion 76 and the operation support portion 72, and is arranged at a position facing the opening 21a of the channel box 21. A guide hole 74a and two insertion holes 74b and 74b are formed in the stopper support portion 74. The guide hole 74a penetrates from one surface portion of the stopper support portion 74 facing the opening 21a to the other surface portion on the opposite side. A stopper portion 75 is slidably inserted into the guide hole 74a. Then, the stopper support portion 74 linearly supports the stopper portion 75 toward the opening 21a so that it can be inserted and removed.

The two insertion holes 74b and 74b are formed on both sides of the guide hole 74a in the width direction. A support pin 78a that supports an elastic member 78, which will be described later, is inserted into the insertion hole 74b.

The stopper portion 75 is formed in a substantially flat plate shape. One end of the stopper portion 75 is inserted into the guide hole 74a and is slidably supported by the stopper support portion 74 in a straight line. One end of the stopper 75 is inserted into or faces the opening 21a of the channel box 21.

Further, two cam pins 79 and 79 are provided at the other end of the stopper portion 75 on the opposite side to one end. The cam pins 79 are formed on both sides of the stopper portion 75 in the width direction. A transmission member 77 is connected to the cam pin 79.

The transmission member 77 is formed in a rectangular shape. The transmission member 77 transmits the operation of the operating plate 71 to the stopper portion 75. A rotation shaft 80 is provided at one end of the transmission member 77 in the longitudinal direction. The transmission member 77 is rotatably supported by the rotation support portion 76 via the rotation shaft 80. The transmission member 77 is supported by the rotation support portion 76 and is arranged on both sides of the other end portion of the stopper portion 75 in the width direction. Further, the transmission member 77 is arranged above the working projection 73 provided on the working plate 71 in the vertical direction.

Further, a cam hole 77a is formed at the other end of the transmission member 77 in the longitudinal direction. The cam hole 77a is an elongated hole opened with a predetermined length along the longitudinal direction of the transmission member 77. A cam pin 79 provided in the stopper portion 75 is slidably inserted into the cam hole 77a. The rotation operation of the transmission member 77 is converted into a linear operation by the stopper portion 75 by the cam hole 77a and the cam pin 79.

Further, an elastic member 78 is arranged between the other end of the transmission member 77 in the longitudinal direction and the stopper support portion 74. A compression coil spring is used as the elastic member 78. The elastic member 78 is not limited to the compression coil spring, and various other elastic members such as rubber and leaf springs may be applied. The elastic member 78 is supported by the support pin 78a.

One end of the support pin 78a is inserted into the insertion hole 74b of the stopper support 74, and the other end of the support pin 78a is in contact with the other end of the transmission member 77.

The transmission member 77 is urged by the elastic member 78 in a direction in which the other end of the transmission member 77 separates from the stopper support portion 74. Then, the stopper portion 75 is urged toward the inside of the channel box 21 by the transmission member 77. Therefore, as shown in FIG. 21A, the stopper portion 75 does not protrude outward from the opening 21a of the channel box 21 in the released state of the jump-up prevention mechanism 70.

During the operation of the nuclear reactor, the fluid flows upward in the vertical direction in the tubular hole of the channel box 21. Then, the operating plate 71, which is partially overhanging from the flow path 22a of the upper tie plate 22, is pressed upward by the fluid in the vertical direction. Therefore, as shown in FIG. 21B, the actuating plate 71 moves upward along the leg portion 72a of the actuating support portion 72 in the vertical direction.

When the operating plate 71 moves upward, the operating projection 73 provided on the operating plate 71 projects upward in the vertical direction from the through hole 72b of the operating support portion 72. Then, the actuating protrusion 73 presses the transmission member 77 against the elastic force of the elastic member 78. Therefore, the transmission member 77 rotates around the rotation shaft 80 in a direction in which the other end portion approaches the stopper support portion 74.

As the transmission member 77 rotates, the cam pin 79 inserted into the cam hole 77a of the transmission member 77 slides in the cam hole 77a and is pressed by the transmission member 77. As a result, the rotational movement of the transmission member 77 is converted into a linear movement. Then, the stopper portion 75 provided with the cam pin 79 moves along the guide hole 74a of the stopper support portion 74 in the direction of projecting from the opening 21a.

As a result, the stopper portion 75 projects from the opening 21a toward the outside of the channel box 21. As a result, the jump-up prevention mechanism 70 shifts from the released state to the locked state.

In addition, when the operation of the reactor is stopped, the upward flow of the fluid in the vertical direction also stops. Therefore, the fluid force that presses the operating plate 71 is also reduced or eliminated. Therefore, the operating plate 71 moves downward in the vertical direction due to its own weight. Therefore, the actuating protrusion 73 provided on the actuating plate 71 also moves downward in the vertical direction and is accommodated in the through hole 72b of the actuating support portion 72.

Further, the transmission member 77 is urged by the elastic member 78, and the other end portion rotates in a direction away from the stopper support portion 74. Then, the stopper portion 75 connected to the transmission member 77 via the cam pin 79 moves toward the inside of the channel box 21. As a result, the movable member 51 returns from the locked state to the released state.

Since other configurations are the same as those of the fuel assembly 10 according to the first embodiment, the description thereof will be omitted. Even with a fuel assembly provided with such a jump-up prevention mechanism 70, the same effect as that of the fuel assembly 10 according to the first embodiment described above can be obtained.

According to the jump-up prevention mechanism 70 according to the fifth embodiment, since the stopper portion 75 moves linearly, the opening area of the opening portion 21a provided in the channel box 21 can be reduced. Further, the stopper portion 75 can be reliably arranged below the lower surface portion 4b of the upper grid plate 4, and when the stopper portion 75 moves, the stopper portion 75 reliably hits the lower surface portion 4b of the upper grid plate 4. Can be touched.

The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the gist of the invention described in the claims.

Further, in the above-described embodiment, the example in which the channel box 21 is formed into a square cylinder shape in accordance with the opening shape of the lattice hole of the upper lattice plate has been described, but the present invention is not limited to this. .. The channel box may be formed in various other shapes such as a hexagonal cylinder and a cylinder according to the opening shape of the lattice holes of the upper lattice plate, for example.

Further, in the above-described embodiment, an example in which two jump-up prevention mechanisms are provided in the fuel assembly has been described, but the present invention is not limited to this, and only one jump-up prevention mechanism may be installed. , Or three or more may be provided. Further, two or more jump-up prevention mechanisms may be installed on one side of the channel box.

Further, an example in which the jump-up prevention mechanism is installed on the upper surface of the upper tie plate has been described, but the present invention is not limited to this, and for example, the support portion of the jump-up prevention mechanism may be installed on the inner wall surface of the channel box. ..

Although words such as "parallel" and "orthogonal" have been used in the present specification, these do not mean only strict "parallel" and "orthogonal", but include "parallel" and "orthogonal". Further, it may be in a "substantially parallel" or "substantially orthogonal" state within a range in which the function can be exhibited.

1 ... Pressure vessel, 2 ... Core, 3 ... Cross control rod, 4 ... Upper lattice plate, 4a ... Lattice hole, 4b ... Lower surface, 4c ... Upper surface, 5 ... Core support plate, 8 ... Fuel rod, 10 ... Fuel assembly, 18 ... Fuel support bracket, 18a ... Mounting hole, 18b ... Control rod movement hole, 21 ... Channel box, 21a ... Opening, 22 ... Upper tie plate, 22a ... Flow path, 23 ... Handle, 23a ... Leg, 23b ... Grip, 24 ... Lower tie plate, 24a ... Mounting, 30, 50, 70 ... Jump prevention mechanism, 31, 41, 51 ... Rotating member (movable member), 32, 42, 52, 75 ... Stopper, 33, 43, 53, 71 ... Actuating plate, 34, 44 ... Rotating shaft, 35, 35A, 55 ... Support, 36 ... First stopper, 38 ... Second stopper, 39 ... Bearing, 39A ... Rolling bearing, 39b ... Rolling body, 43a ... Partition wall, 54a, 54b ... Sliding part, 55a, 55b ... Sliding groove, 72 ... Acting support, 73 ... Acting protrusion, 74 ... Stopper support, 74a ... Guide hole, 76 ... Rotation support, 77 ... Transmission member, 77a ... Cam hole, 78 ... Elastic member, 79 ... Cam pin, 80 ... Rotation shaft

Claims (14)

A hollow tubular channel box that is inserted into the lattice hole of the upper lattice plate installed in the pressure vessel and whose upper end in the vertical direction is supported by the upper lattice plate.
The fuel rods housed in the cylinder holes of the channel box and
In the tubular hole of the channel box, an upper tie plate which is arranged below the lower surface portion in the vertical direction of the upper lattice plate and has a flow path through which a fluid can pass, and
A jump-up prevention mechanism installed in the tubular hole of the channel box is provided.
An opening is formed between the upper tie plate and the lower surface portion of the channel box.
The jump prevention mechanism is
An actuating plate that is placed overhanging the flow path of the upper tie plate and pressed by a fluid passing through the flow path
A support portion that movably supports the operating plate and
It has a stopper portion that faces the opening portion and is detachably supported by the support portion in the opening portion.
When the operating plate is pushed upward by the fluid in the vertical direction and moves, the stopper portion projects from the opening to the outside of the channel box and faces the lower surface portion of the upper lattice plate in the vertical direction. Fuel assembly. The fuel assembly according to claim 1, wherein the support portion is installed on an upper surface portion in the vertical direction of the upper tie plate. The jump-up prevention mechanism has a movable member in which the operating plate and the stopper portion are integrally formed.
The fuel assembly according to claim 1, wherein the support portion movably supports the movable member. The jump prevention mechanism has a rotation shaft provided on the movable member, and has a rotation shaft.
The fuel assembly according to claim 3, wherein the rotating shaft is rotatably supported by a bearing portion provided on the supporting portion. The fuel assembly according to claim 4, wherein the moment generated on the rotating shaft by the own weight of the operating plate is set to be larger than the moment generated on the rotating shaft by the own weight of the stopper portion. The fuel assembly according to claim 5, wherein the mass of the operating plate is set to be heavier than the mass of the stopper portion. The fuel assembly according to claim 5, wherein the distance from the center of gravity of the operating plate to the rotating shaft is set longer than the distance from the center of gravity of the stopper portion to the rotating shaft. The fuel assembly according to claim 4, wherein a rolling bearing portion is used as the bearing portion. The movable member is provided with a sliding portion.
The fuel assembly according to claim 3, wherein a sliding groove that slidably supports the sliding portion is formed in the support portion. The fuel assembly according to claim 1, wherein the jump-up prevention mechanism includes a transmission member that transmits the operation of the operating plate to the stopper portion. The support portion
An actuating support portion that supports the actuating plate so as to be movable in the vertical direction,
A stopper support portion that linearly and detachably supports the stopper portion toward the opening, and a stopper support portion.
The fuel assembly according to claim 10, further comprising a rotatably supporting portion that rotatably supports the transmission member. The fuel assembly according to claim 1, wherein a partition wall projecting downward in the vertical direction is provided on the lower surface portion of the operating plate in the vertical direction. It has a lower tie plate attached to the lower end of the channel box in the vertical direction.
The lower tie plate has a mounting portion that is fitted into a mounting hole of the fuel support fitting installed in the pressure vessel.
The fuel assembly according to claim 1, wherein the length from the stopper portion protruding from the opening to the lower surface portion of the upper lattice plate is set shorter than the fitting length of the mounting portion into the mounting hole. body. A handle is provided on the upper surface of the upper tie plate in the vertical direction.
The fuel assembly according to claim 1, wherein the upper end portion of the handle in the vertical direction is arranged above the upper lattice plate in the vertical direction.

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