JP2909805B2 - Fuel rod handling tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for extracting a damaged fuel rod from a fuel assembly used in a nuclear power plant or the like and inserting or transporting an alternative fuel rod as necessary. And a fuel rod handling tool that prevents the fuel rod from being damaged.

[0002]

2. Description of the Related Art As is well known, even in a fuel assembly, even if one fuel rod is damaged and a leak or the like occurs,
If the fuel assemblies are carried out in a unit, the fuel rods will be greatly damaged in terms of the life of the fuel assemblies, especially if the fuel rods are damaged in the initial stage of the fuel. For this reason, overseas, only the damaged fuel rod is taken out,
By inserting an alternative new fuel rod into this, the fuel assembly is reused. Also, in Japan, as part of the development of nuclear fuel assemblies, certain test fuel rods may be withdrawn from the fuel assembly, and these fuel rods must be withdrawn, inserted, and transported. There has been known a fuel rod handling tool suspended and used by a fuel handling crane installed on a spent fuel pit of a nuclear power plant.

[0003] Conventionally, this type of fuel rod handling tool is provided with a gripping mechanism for gripping an upper end plug of a fuel rod at a tip end of a long structure, which is provided at an upper portion of the long structure. The damaged fuel rods in the fuel assembly can be grasped and removed by remote control of the latch / unlatch operation section.

[0004]

Therefore, according to the above prior art, the fuel rod is pulled out of the fuel assembly and transported to a required location, or the alternative fuel rod is transported and inserted. The rod will be handled in a hanging state naked, so the gripped fuel rod may hit another object due to inadequate work, or may fall due to erroneous operation or failure of the gripping mechanism. And there was a risk that this would cause severe damage.

[0005] In view of the above-mentioned conventional deficiencies, the present invention relates to a fuel rod gripped and pulled out.
When the fuel rod is to be carried out in a suspended state, the fuel rod is configured to be wrapped and stored in the interior protection cylinder among the cylinders configured in the multiple cylinder state. It is trying to eliminate the inadvertent collision of fuel rods with other objects. Further, the fuel rods contained in the interior protection cylinder are completely prevented from dropping based on an appropriate opening / closing operation of a fuel rod fall prevention mechanism provided below and connected to the interior protection cylinder, It is possible to completely prevent unintentional dropping of fuel rods during transportation, thereby trying to solve all the problems of the conventional example.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the upper end of the fuel rod support cylinder, which is provided with a gripping chuck for gripping the fuel rod, is attached to the upper end of the fuel rod support cylinder. A fuel cell crane is used to connect and receive a load cell fixed to a suspension section suspended by a fuel handling crane, so that an excessive pressing force is applied to a fuel rod to be gripped, The force applied to the fuel rods can be prevented by monitoring the load cell display, and the fuel rods can be damaged by handling operations during the work. This is also to prevent this.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, there is provided a suspension portion which can be suspended by a fuel handling crane, and is fixed to the suspension portion. An exterior hanging tube, a fuel rod supporting tube fixed to the hanging portion and inserted through the axis of the exterior hanging tube, and a latch provided in the hanging portion on the fuel rod supporting tube. An operation shaft which can be moved up and down by operation of an unlatch operation portion, and an operation end of the operation shaft which is connected to a lower portion of the fuel rod support cylinder by an operation of a latch / unlatch operation portion, thereby closing an upper end plug of a fuel rod of a fuel assembly. A gripping chuck which can be freely gripped, and which extends in the exterior vertical hanging tube so as to be able to protrude and retract downward in a retaining state, cooperates in a rotating direction, and the operating shaft Rod support with gripping chuck And a fuel rod drop prevention mechanism provided at the lower end of the interior protection cylinder. When the suspension is suspended by the hanging portion, the interior protection cylinder is positioned below the exterior hanging cylinder. In the interior protection cylinder that is extended by a required length and is in a retaining state, a continuous gripping chuck is stored in a lower part of the fuel rod support cylinder and provided at a lower end of the interior protection cylinder. In the fuel rod drop prevention mechanism, the upper nozzle of the fuel assembly is removed, and an opening screw is provided just above the upper end plug of the predetermined fuel rod in the positioning plate loaded in the upper plug of the control rod guide tube. The opening / closing cylinder connected to the interior protection cylinder and the screwing of the threaded cylindrical part to the positioning screw hole are provided. An elevating cover moved up and down by the positioning plate, and the elevating cover With the upward movement, the drop prevention claw which is provided from the window hole of the opening / closing cylinder and changes from the extended state into the opening / closing cylinder to the detached state, and the threaded cylindrical portion from the alignment screw hole. First and second restoring springs are provided to move the elevating cover and the fall-preventing claws back by detaching, respectively. The interior is provided by an exterior vertical cylinder which is moved down by operation of the fuel handling crane. By setting the protection cylinder to the wrapping state, the latch-unlatching operation is performed on the gripping chuck that can extend downward from the interior protection cylinder via the opening / closing cylinder body in which the drop prevention claw is detached. An operating part connected to the operating shaft which moves up and down by operation of the part, and the fuel rod supporting cylinder which is closed so as to be openable and closable by the raising and lowering movement of the operating part and which can freely grip an upper end plug of the fuel rod. And a gripper pivoted at the lower end of the The gripped fuel rod is lifted up by the fuel handling crane through the opening / closing cylinder of the fuel rod fall prevention mechanism, so that the fuel rod is extended from the exterior vertical cylinder. As it can be stored freely in the protective cylinder,
The fuel rod drop prevention mechanism is released from screwing with the positioning plate, so that the fuel rod is prevented from falling by the drop prevention claw extended from the opening / closing cylinder. It is intended to provide a fuel rod handling tool characterized by the following.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the fuel rod support cylinder is attached to a load cell fixed to the suspension portion so that the load is transmitted. That is the content.

[0009]

According to the fuel rod handling tool of the first aspect, when the fuel rod handling tool is hung by the hanging portion using the fuel handling crane, the interior protection cylinder extends and hangs by a predetermined length from the exterior hanging cylinder. At this time, the gripping chuck provided at the lower end of the fuel rod support cylinder is located inside the interior protection cylinder. In this way, the fuel rod drop prevention mechanism provided at the lower end of the interior protection cylinder is lowered into the pool in which the fuel assembly is erected, and is positioned directly above the fuel assembly. .

At this time, a positioning plate prepared separately is fitted and attached to the upper plug of the control rod guide tube projecting from the fuel assembly from which the upper nozzle has been removed.
In this, a positioning screw hole is provided so as to correspond to the position immediately above the end plug of the fuel rod attached to the fuel assembly, so that the fuel rod is monitored while being monitored using an underwater television camera. By inserting the threaded tube portion of the opening / closing cylinder in the rod drop prevention mechanism and rotating the hanging portion, the exterior hanging tube and the interior protection tube are sequentially provided, and the opening / closing tube provided at the lower end thereof The rotation is transmitted to the body, and the threaded cylindrical portion can be screwed into the alignment screw hole.

Thus, the elevating cover of the fuel rod drop prevention mechanism is pushed up by the positioning plate against the elasticity of the first restoring spring. The drop prevention claw extending inward from the hole and closing the opening / closing cylinder is actuated and detached outward from the window hole against the elasticity of the second restoration spring. The opening / closing cylinder is opened.

[0012] Next, if the suspension portion is lowered by operating the fuel handling crane, the outer vertical tube moves down while covering the inner protective tube, and the fuel rod supporting tube and the fuel rod supporting tube are moved downward. Since the operating shaft for insertion is also lowered, the gripper for chuck also extends downward through the opening / closing cylinder which is in the open state, and is ready to be pulled out in the fuel assembly. The fuel rod is located just above the upper end plug.

Here, when the operation shaft is moved upward by operating the latch / unlatch operation section in the suspension section, the gripper in the gripper can be opened. By releasing the operation of the operation unit, the claws grip the upper end plug. here,
If the hanging part is lifted by the fuel handling crane, the exterior vertical cylinder moves upward, and the interior protection cylinder is exposed,
The fuel rod gripped by the gripping chuck and pulled out of the fuel assembly passes through the opening / closing cylinder in the open fuel rod fall prevention mechanism, and is stored in the interior protection cylinder.

Then, by removing the screw portion of the opening / closing cylinder in the fuel rod drop prevention mechanism from the positioning screw hole of the positioning plate, the elevating cover is restored by the first restoring spring. Move, which causes the second
The fall prevention claw is restored by the return movement of the restoring spring, and the opening / closing cylinder is closed, so that the fuel rod in the inner protective cylinder is prevented from falling to a predetermined position in a state where the fall is prevented. Transport can be performed. It should be noted that the insertion and attachment of a new fuel rod or the like to the fuel assembly can also be performed by the reverse procedure of the above-described pulling operation.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
The suspension unit 1 that can be suspended by a fuel handling crane (not shown) includes a horizontal mounting base 1a and an inverted U-shaped hanging ring 1c fixed to the horizontal mounting base 1a by a nut 1b. From below, the exterior vertical tube 2 extends long downward in an orthogonal shape. The fuel rod support tube 3 inserted through the shaft center of the exterior vertical tube 2 is also fixed to the suspension unit 1 according to the first embodiment. In the case of the second embodiment, the fuel rod support tube 3 is directly connected to the suspension unit 1. Instead of being fixed to the load cell 4, it is fixed through the load cell 4 attached to the horizontal mounting base 1a.

Here, 2a shown in FIGS. 1 and 5
Denotes a plurality of joints for a vertically extending cylinder provided at predetermined intervals, 3a denotes a joint for a fuel rod support cylinder provided at a predetermined interval, and the fuel rod support cylinder 3 is suspended from the fuel rod support cylinder 3. An operation shaft 6 that can move up and down by fitting a handle 5a of a latch / unlatch operation unit 5 provided on a lateral mounting base 1a of the unit 1 in a vertical direction is inserted. In the figure, reference numeral 5b denotes a handle pivot pin, and reference numeral 5c denotes a connection pin which pivotally supports the distal end of the handle 5a to the operation shaft 6.

The latch / unlatch operating section 5 of the operating shaft 6
The upper end plug N shown in FIG. 4 of the fuel rod M of the fuel assembly L shown in FIG. 5 is connected to the lower part of the fuel rod support cylinder 3 as described later in detail.
Is provided with a gripping chuck 7 configured so as to be able to be freely gripped. In addition, the exterior hanging tube 2 is extended downward so as to be able to protrude and retract with a predetermined length of retaining state by a mechanism (not shown) such as provided inside the exterior hanging tube joint 2a. An interior protection tube 8 that rotates together with the exterior vertical tube 2 is inserted into the housing. The operation shaft 6 is fitted and inserted into the interior protection tube 8, and the fuel rod support tube 3 having the gripping chuck 7 is inserted therethrough.

Further, at the lower end of the interior protection cylinder 8, a fuel rod fall prevention mechanism 9 which will be described in detail later is provided. In the figure, reference numeral 9a denotes a lower end joint connecting the lower end of the inner protective tube 8 and the fuel rod drop prevention mechanism 9, and when the above-mentioned hanging unit 1 is suspended by the fuel handling crane, the outer vertical tube is provided. As shown in FIG. 5 (A), the gripping chuck 7 at the lower part of the fuel rod supporting cylinder 3 is located inside the inner protective cylinder 8 extending downward by a required length from the inner rod 2 and in a retaining state. It is stored.

The fuel rod drop prevention mechanism 9 provided at the lower end of the interior protection cylinder 8 has a threaded cylinder 9b as shown in FIGS. 2 and 3 and is connected to the interior protection cylinder 8. The opening / closing cylinder 9c is provided.
The b and screwed into alignment screw holes P ₁ of the positioning plate P to be understood by FIG. 5 (B) so that the use.
Here, positioning plate P has been prepared separately in advance, the top nozzle of the fuel assembly L is removed, and loaded engagement pin P ₂ to the upper plug to Q ₁ the control rod guide tubes Q Yes held in a horizontal state, by screwing the Nishito portion 9b to the positioning screw hole P ₁ as described above, the fuel rods M is configured to be disposed to be pulled out immediately below.

[0020] In practice, the positioning plate P in which a plurality of aligned screw holes P ₁ in various patterns are formed through
If several types are prepared, it is possible to deal with any fuel rod M by selecting a positioning plate P suitable for the position of the fuel rod M to be withdrawn.

FIG. 2 shows that the fuel rod drop prevention mechanism 9 is provided in the positioning screw hole P ₁ selected in the positioning plate P.
Shows a state before screwing the screw portion 9b.
On the upper part of the opening / closing cylinder 9c connected to the interior protection cylinder 8 via the lower end joint 9a as described above, a drop prevention claw operating section 9 is provided.
d is provided, and the pressing ring 9e is sequentially contacted therebelow.
A first restoration spring 9f and a rotation bearing 9g are arranged in a stacked state, and a stopper 9h protruding from an opening / closing cylinder 9c is provided immediately above a screw cylinder 9b formed at the lower end.
Is provided. An elevating cover 9i fitted on the opening / closing cylinder 9c so as to be prevented from being pulled out by the stopper 9h resists the elasticity of the first restoring spring 9f via a rotating bearing 9g, and is configured to be able to move upward. And
The lower end of the opening / closing cylinder 9c protrudes downward from the lower end of the elevating cover 9i.

Next, the structure of the fall prevention claw operating portion 9d which receives the elasticity of the first restoration spring 9f through the interposition of the pushing ring 9e will be described.
This is mounted on the pushing ring 9e, and is
sliding contact rotating arm piece 9m pivotally attached to j by a fulcrum 9k
And a connecting piece 9p pivotally attached to the upper end thereof by a fulcrum 9n, and T connected to a tip of the connecting piece 9p by a fulcrum 9q.
And the fall prevention claw 9r.
Is pivotally supported by the operating portion base 9j by the fulcrum 9s, and between the fulcrum 9n and the upper portion of the operating portion base 9j.
A second restoration spring 9t is stretched.

The free end 9u of the fall prevention claw 9r is in a normal state and the second restoration spring 9r is in a normal state.
Due to the tension of t, the opening / closing cylinder 9c extends inward from a window hole 9v formed in the opening / closing cylinder 9c, thereby closing the opening / closing cylinder 9c.

[0024] Therefore, said hanging element 1 is lowered the like, after which the threaded cylindrical portion 9b of the opening and closing accommodating cylinder 9c, fitted into the aligned screw holes P ₁ of the positioning plate P, hanging element 1 Is rotated, the rotation of the exterior vertical tube 2 is changed to the interior protection tube 8.
It is transmitted to the open-close cylinder body 9c from can be screwed Nishito portion 9b to align screw holes P _1. At this time, as understood from FIG. 3, the lifting cover 9i of the fuel rod fall prevention mechanism 9 is pushed up by the upper surface of the positioning plate P, so that the lifting cover 9i is moved through the first restoration spring 9f. The push ring 9e is pushed up.

As a result, the sliding contact rotating arm 9m of the fall prevention claw operating portion 9d rotates around the fulcrum 9k and pushes the pivotally connecting piece 9p by the fulcrum 9n. 9r pivots about the fulcrum 9s, whereby the free end 9u of the fall prevention claw 9r pivots away from the window hole 9v of the opening / closing cylinder 9c to the outside.
3c is in an open state without the fall prevention claw 9r, and at this time, the second restoration spring 9t is of course
And the restoring force is accumulated.

Therefore, when the hanging portion 1 is lowered as shown in FIG. 5 (B), the exterior hanging tube 2 moves down so as to cover the interior protection tube 8, and until then the interior protection tube 8 The holding chuck 7 housed in the fuel rod fall prevention mechanism 9 also passes through the open / close cylinder 9c in the open state in the fuel rod fall prevention mechanism 9, extends downward from the threaded cylinder 9b, and should be pulled out. The fuel rod M extends to just above the upper end plug N. Here, the above-described latch / unlatch operation section 5 is operated by the gripping chuck 7, and the fuel rod M is gripped as described below.

First, the gripping chuck 7 will be described in detail with reference to the gripping chuck embodiment of FIG. 4. In FIG. 4, the gripping chuck 7 is provided at the lower end 3 b of the fuel rod support cylinder 3. Of the lower end 3b of the lower end 3b, a plurality of required claws 7b can be opened and closed in the left and right directions by a pivot pin 7c as shown by arrows. Being pivoted.

Further, a connecting pin 7d is provided at the lower end of the operating shaft 6 inserted through the fuel rod support cylinder 3 so as to protrude outward, and is connected to the operating portion 7a. The operating portion 7a is always pressed downward by the elastic force of the coil spring 7e wound around the rod support cylinder 3 and supporting the upper end. The connecting pin 7d penetrating the 7f is in contact with the lower edge of the elevating incision window 7f.
Since b is higher than the pivot pin 7c and is pushed, the grip 7b is held in a closed (gripped) state.

Then, if the operating shaft 6 is moved upward against the resilience of the coil spring 7e by operating the latch / unlatch operating portion 5 in the hanging portion 1, the operating projection 7g is moved from the grip 7b. Outward protruding part 7 formed outside the upper end
By pressing h inward, the grip 7b is configured to be opened (released), and 7i in the figure denotes a locking projection that protrudes inside the lower end of the grip 7b. .

Accordingly, first, the latch / unlatch operating section 5 is pulled up to open the grip 7b, and then the hanging section 1 is lowered as it is, and the upper end plug N of the fuel rod M is pulled by the grip 7b. When the operation of the latch / unlatch operation section 5 is released by monitoring with an underwater television camera or the like in the state of being wrapped, the operation section 7a is moved down by the restoring force of the coil spring 7e, and the claw 7b is closed. , The upper end plug N can be gripped.

When this gripping state is obtained, the hanging portion 1 is moved up to pull out the fuel rod M from the fuel rod assembly L, whereby the externally mounted vertical cylinder 2 is raised to protect the interior. While the cylinder 8 is exposed, the fuel rod M can be stored in the interior protection cylinder 8 by passing through the open / close cylinder 9c in the open state. If resulted in this state, by reverse rotation of the suspended portion 1, if leaving the screw cylinder portion 9b from the alignment screw hole P ₁ of the positioning plate P, the restoring force of the first restoration spring 9f Lifting cover 9i
Is lowered and the fall prevention claw 9r is also moved back by the restoring force of the second restoration spring 9t, and extends inward from the window hole 9v, whereby the opening / closing cylinder 9c is closed.

Therefore, if the transport operation is performed by the fuel handling crane in this state, the pulled-out fuel rods will be in the inner protective cylinder 8.
And the fuel rod drop prevention mechanism 9 provided at the lower end thereof is in a closed state.
It is possible to completely prevent the fuel rod from being directly and unintentionally subjected to an external force and from being accidentally dropped.

[0033]

According to the first aspect of the present invention, since the fuel rods pulled out from the fuel assembly are stored in the inner protective cylinder, the present invention is applied to the transporting apparatus. It can be opened by simply screwing it into the positioning screw hole of the positioning plate or by releasing the screw by setting the fuel rod fall prevention mechanism without damaging it. This makes it possible to safely and efficiently remove fuel rods without any trouble in grasping and pulling out or inserting fuel rods, and to eliminate the risk of fuel rods dropping during transportation. Work can be done.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the fuel rod support cylinder is connected to the load cell, so that not only the above-mentioned effect is exhibited but also the operation of pulling out and inserting the fuel rod. There is no need to apply excessive force to the fuel rods, and the soundness of the fuel rods can be further improved.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a partially cut-away view of a fuel rod handling tool according to a second embodiment of the present invention in a reduced state.

FIG. 2 is a partially cutaway front view showing a state before the fuel rod drop prevention mechanism provided at the lower end of the fuel rod handling tool is screwed to an alignment plate.

FIG. 3 is a partially cutaway front view showing a state in which a fuel rod fall prevention mechanism of the tool is screwed to the positioning plate.

FIG. 4 is a vertical sectional front view showing a state in which an upper end plug of the fuel rod is about to be gripped by a gripping chuck 7 provided at a lower end of a fuel rod support cylinder of the same tool.

5A and 5B illustrate a method of handling the fuel rod handling tool according to the present invention, wherein FIG. 5A is a front explanatory view showing an extended state suspended by a fuel handling crane, and FIG. FIG. 4C is a front view showing an operation state in which a required fuel rod is pulled out from the assembly, and FIG. 4C is a front view showing an extended state in which the drawn fuel rod is to be transported.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Suspension part 2 Exterior hanging cylinder 3 Fuel rod support cylinder 3b Lower end part 4 Load cell 5 Latch / unlatch operation part 6 Operation shaft 7 Grip chuck 7a Operating part 7b Nail 8 Inner protection cylinder 9 Fuel rod fall prevention mechanism part 9b threaded tubular portion 9c closing accommodating cylinder 9f first restoration spring 9i lifting cover 9r fall prevention claw 9t second restoration spring 9v windows L fuel assembly M fuel rods N upper end plug P positioning plate P ₁ aligned screw hole Q control rod guide tubes Q ₁ upper plug

Claims (2)

(57) [Claims] 1. A hanging part which can be hung freely by a fuel handling crane, an exterior hanging cylinder fixed to the hanging part, and a shaft in the exterior hanging cylinder fixed to the hanging part. A fuel rod supporting cylinder inserted into the core, an operating shaft that can be moved up and down by operating a latch / unlatch operating part provided in the hanging part in the fuel rod supporting cylinder, and a latch / unlatch operating part of the operating shaft The gripping chuck is connected to the lower portion of the fuel rod support cylinder and is capable of freely gripping the upper end plug of the fuel rod of the fuel assembly. Is extended so that it can come and go in the locked state, cooperates in the rotation direction, and
An inner protective cylinder having the operating shaft and a fuel rod support cylinder having a gripping chuck inserted therein, and a fuel rod drop prevention mechanism provided at a lower end of the inner protective cylinder; In the suspended state by the lowering portion, it is located in the interior protection cylinder which extends downward from the exterior vertical cylinder by a required length by a required length and is in a retaining state, and is provided below the fuel rod support cylinder. The take-off chuck is in the housed state, and the fuel rod drop prevention mechanism provided at the lower end of the inner protective cylinder is provided with the upper nozzle of the fuel assembly removed and loaded into the upper plug of the control rod guide tube. An opening / closing cylinder connected to the interior protection cylinder, wherein the positioning plate has a threaded portion which is screwed into an alignment screw hole which is opened directly above the upper end plug of the predetermined fuel rod; , By screwing the screw portion into the alignment screw hole, An elevating cover moved up and down by the plate, and a drop prevention claw that is installed from the window hole of the opening / closing cylinder and changes from the extended state into the opening / closing cylinder to the detached state by the upward movement of the elevating cover. And first and second restoring springs for retreating the elevating cover and the drop prevention claw respectively by detaching the threaded cylindrical portion from the positioning screw hole, and comprising the fuel handling crane. The interior protection cylinder is wrapped by the exterior vertical cylinder that moves down by operation, so that it can be extended downward from the interior protection cylinder via the opening / closing cylinder in which the drop prevention claw is detached. The gripping chuck has an operating portion connected to the operating shaft which moves up and down by operating the latch / unlatch operating portion, and an upper portion of the fuel rod which is closed so as to be openable and closable by raising and lowering the operating portion. The fuel wherein the end plug can be freely gripped. Lifting the gripped fuel rod through the opening / closing cylinder of the fuel rod fall prevention mechanism by lifting operation of the fuel handling crane, comprising a gripper pivotally supported at the lower end of the support cylinder. Then, the fuel rod can be housed in the interior protection cylinder in a state of being extended from the exterior vertical tube, and the fuel rod fall prevention mechanism is released from the screwing with the positioning plate, whereby the fuel rod is removed. A falling prevention claw extended from the opening / closing cylinder to prevent the falling movement of the fuel rod. 2. A hanging part which can be hung freely by a fuel handling crane, an outer vertical tube fixed to the hanging part, and a load cell fixed to the hanging part for transmitting a load. A fuel rod support cylinder inserted through the shaft center of the exterior vertically mounted cylinder, and an operation shaft that can be moved up and down by operation of a latch / unlatch operation section provided in the suspension section on the fuel rod support cylinder. The gripping chuck, which is connected to the lower part of the fuel rod support cylinder and is capable of gripping the upper end plug of the fuel rod of the fuel assembly by operating the latch / unlatch operation part of the operating shaft, A fuel rod support cylinder in the installation cylinder, which extends downward so as to be freely retractable and retractable, cooperates in the rotation direction, and has the above-mentioned operation shaft and has a gripping chuck. The interior protection tube through which is inserted And a fuel rod drop prevention mechanism provided at the lower end of the interior protection cylinder, and when suspended by the suspension portion, extends downward from the exterior vertical cylinder by a required length. In the interior protection cylinder in the retaining state, the grasping chuck connected continuously at the lower part of the fuel rod support cylinder is in the housed state, and the fuel rod fall prevention mechanism provided at the lower end of the interior protection cylinder is Is located on the positioning plate mounted on the upper plug of the control rod guide tube by removing the upper nozzle of the fuel assembly, and is screwed into a positioning screw hole which is opened directly above the upper end plug of the predetermined fuel rod. An opening / closing cylinder connected to the interior protection cylinder, and a screwing of the screwing part into a positioning screw hole, which is moved upward by the positioning plate. The elevating cover and the up-and-down movement of the elevating cover The drop prevention claw that is provided from the window hole and extends from the extended state into the opening / closing cylinder to the detached state, and the screw cover portion is detached from the alignment screw hole, thereby the elevating cover and First and second restoring springs for respectively returning the fall prevention claws and the fall prevention claws are provided, and the interior protection cylinder is wrapped by the exterior vertical cylinder which moves down by the operation of the fuel handling crane. The gripping chuck, which can extend downward from the interior protection cylinder via the opening / closing cylinder in which the drop prevention claw is detached, is provided with the above-described operation of moving up and down by operation of the latch / unlatch operation section. An operating part connected to the shaft, a gripper pivotally supported on a lower end of the fuel rod support cylinder, which is closed so as to be openable and closable by raising and lowering the operating part, so that an upper end plug of the fuel rod can be gripped freely; And holding the gripped fuel rods as described above. By lifting the crane through the opening / closing cylinder of the fuel rod drop prevention mechanism, the fuel rod can be stored in the interior protection cylinder which is in a state of being extended from the exterior vertical cylinder. By releasing the rod drop prevention mechanism from being screwed to the positioning plate, the drop of the fuel rod is prevented by the drop prevention claw extended from the opening / closing cylinder. Characteristic fuel rod handling tool.