JP2899337B2 - Control rod drive mechanism handling method and handling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a method and an apparatus for handling a control rod drive mechanism provided in a boiling water reactor.

(Conventional technology) In a boiling water reactor (hereinafter, referred to as BWR) as a light water reactor, operation (start / stop) of the reactor and power control of the reactor are performed by moving control rods into and out of the core. The control rod is controlled by a control rod drive mechanism (hereinafter referred to as CRD) disclosed in Japanese Patent Application Laid-Open No. 60-179690.

As shown in FIG. 7, many conventional CRDs 1 are provided in the lower part (lower mirror part) of the reactor pressure vessel 3 of the BWR 2. The reactor pressure vessel 3 is filled with reactor water, and a core shroud 4 is provided inside the reactor pressure vessel 3, and a core 6 in which a number of fuel assemblies 5 are mounted is formed in the shroud 4. Fuel assembly 5
Is supported by the core support plate 7 and the upper lattice plate 8 and is erected. The core shroud 4 containing the fuel assembly 5 is covered by a shroud head 9, and a steam separator 10 is provided above the shroud head 9. The steam separated by the steam separator 10 is separated by a steam dryer. (Not shown) to dry steam.

Further, the control rod 11 is provided in the lower part of the control rod guide tube 12 in the cross-shaped cross section formed by the four fuel assemblies 5.
The control rod 11 is driven and controlled by an electric CRD 1. The CRD 1 is a control rod drive mechanism housing (hereinafter referred to as a CRD housing) 13 fixed through the bottom wall (lower mirror) of the reactor pressure vessel 3.
And a control rod driving mechanism main body (hereinafter, referred to as CRD main body) 14 inserted and fixed from below into the CRD housing 13. By driving the CRD 1, the control rod 11 can be inserted into or pulled out of the core 6. This is done to control the furnace power.

The electric CRD 1 is, as shown in FIG.
The outer tube 15 is accommodated in the outer tube 3, and the cylinder tube 16 is accommodated in the outer tube 15. A CRD main body flange 17 is integrally attached to a lower end of the outer tube 15, and a hollow piston 18 is accommodated in an inner peripheral side of the cylinder tube 16 so as to be vertically movable. A coupling member 19 is attached to the upper end of the hollow piston 18,
The control rod 11 is connected to the control rod 11 via the coupling member 19. In addition, a plurality of magnets 20 are integrated into the lower end of the hollow piston 18.

On the other hand, a ball screw shaft 21 is disposed in the hollow piston 18 so as to penetrate therethrough. The ball screw shaft 21 receives a rotational driving force from an electric motor 23 via a shaft 22. A ball nut 24 is screwed onto the ball screw shaft 21. The shaft 22 is accommodated in a spool piece 25 fixed to the CRD body flange 17 from below, and the electric motor 23 is fixed below the spool piece 25. Further, a seal member 27 is mounted between the shaft 22 and the spool piece 25 via a seal box 26.

By the way, the CRD 1 has an operation of inserting or removing the control rod 11 at a relatively low speed in order to adjust and maintain the reactor power at a predetermined state (hereinafter referred to as a shim operation), and an emergency stop of the reactor in an emergency. There is an operation of inserting the control rod 11 at a high speed (hereinafter, referred to as a scrum operation). Shim operation, motor 23
To rotate the ball screw shaft 21 via the shaft 22. The rotation of the ball screw shaft 21 causes the ball nut to rotate.
24 rises to raise the hollow piston 18. Thus, the control rod 11 is inserted at a low speed by a predetermined amount. Conversely, when pulling out the control rod 11, the electric motor 23 is rotated in the reverse direction. The reverse rotation of the motor 23 also rotates the ball screw shaft 21 in the reverse
And the hollow piston 18 also moves down at the same time. As a result, the control rod 11 is pulled out by a predetermined amount at a low speed.

In the scrum operation, high-pressure water is supplied from a high-pressure water injection mechanism (not shown) through a flange 13A of the CRD housing 13 and a high-pressure water supply port 28 formed in the CRD main body 17, and the high pressure acts on the hollow piston 18. Due to the action of the high pressure, the hollow piston 18 separates from the ball nut 24 and rises at a high speed to insert the control rod 11 into the core at a high speed.
This causes an emergency shutdown of the reactor.

Next, an operation of inserting the CRD body 14 into the CRD housing 13 and mounting the same will be described. First, as shown in FIG.
With the spool piece 25 and the electric motor 23 separated from the D main body 14, the CRD main body 14 is inserted into the CRD housing 13 from below using a CRD handling device (not shown) as a CRD exchanger. Then, the CRD body 14 is connected to the control rod 11 via the coupling member 19 at the upper end of the hollow piston 18. That is, as shown in FIG. 10 and FIG.
Is provided with four engagement plates 19A. Meanwhile, control rod 1
A coupling hole 31 is formed at the lower end of the coupling hole 31. Four recesses 13A that fit into the four engagement plates 19A are formed on the inner peripheral surface of the coupling hole 31. The CRD main body 14 is inserted into the CRD housing 13 in a state where the phases are matched so that the four engagement plates 19A are fitted into the engagement recesses 31A, respectively.

After the four engagement plates 19A of the coupling member 19 have been completely inserted into the coupling hole 31, the CRD body 14 is slightly raised so that the control rod 11 is slightly raised in order to further ensure the insertion state. Into the CRD housing 13.

By inserting the CRD body 14, the control rod 11 becomes the control rod guide tube 12
A little away from the seating surface, the reactor water sealing function is lost, and the reactor water flows out between the control rod 11 and the control rod guide tube 12. The outflowing reactor water passes through the upper surface of the upper guide 33, flows down between the outer tube 15 and the CRD housing 13, and is sealed by the seal mechanism 35. The seal mechanism 35 is formed in the lower large-diameter portion of the outer tube 15, and includes an annular groove formed on the outer tube 15 side, and a seal ring mounted on the annular groove.

Also, when inserting the CRD body 14, the CRD body flange 17
CRD housing 13 to protect seal ring 29
The insertion of the CRD body 14 is temporarily stopped in a state where a gap is provided between the flange 13A and the CRD body flange 17. At this time, the upper surface of the upper guide 33 of the CRD body 14 is
The upper guide 33
The disc spring row 34 for buffers mounted between the cylinder tube 16 and the cylinder tube 16 is slightly compressed.

Next, as shown in FIG. 12 and FIG.
The CRD body 14 and the control rod 11 are connected by rotating the coupling member 19 and the coupling hole 31 correctly by rotating the CRD body 19 by the rotation. After this connection, the CRD body 14 is connected to the CRD housing 13
The CRD main body 14 is fixed to the CRD housing 13 by connecting the CRD housing flange 13A and the flange 17 of the CRD main body 14 with mounting bolts (not shown). Thereafter, the spool piece 25 and the electric motor 23 are sequentially mounted.

Next, an operation of removing the CRD main body 14 from the housing 13 will be described.

When removing the CRD body 14, first, the spool piece 25 and the electric motor 23 are removed from the CRD1. Thereafter, the fixing bolt (not shown) that fastens the CRD body flange 17 to the CRD housing flange 13A is loosened, and the fixation of the CRD body 14 to the CRD housing 13 is released. At this time, the CRD main unit 14 supports a CRD handling device (not shown) as a CRD exchange.

Subsequently, the CRD body 14 is lowered by lowering the CRD handling device. At this time, to protect the seal ring 29 of the CRD body flange 17, the CRD housing flange 13A and CR
The lowering of the CRD main body 14 is temporarily stopped with a slight gap formed between the CRD main body 14 and the D main body flange 17. During this stop, C
The upper surface of the upper guide 33 of the RD body 14 is in contact with the top wall of the CRD housing 13, and the upper guide 33 and the cylinder tube
The buffer disc spring row 34 mounted between the disc spring 16 and the disc spring 16 is slightly compressed.

In the state shown in FIG. 9, the CRD main body 14 is rotated by 45 degrees so that the four engagement plates 19A of the coupling member 19 and the four engagement recesses 31A of the inner peripheral surface of the coupling hole 31 at the lower end of the control rod 11 are aligned. , First
As shown in FIGS. 0 and 11, the phases are adjusted so as to fit each other, and the CRD body 14 is lowered again in this phase adjusted state.

At this time, the control rod 11 descends together with the CRD main body 14 and comes into contact with the control rod guide tube 12 to form a reactor water sealing structure, and the lowering of the control rod 11 is stopped at this position.

When the CRD body 14 is further lowered, the coupling member 1
The four engagement plates 19A are pulled out from the coupling holes 31 of the control rod 11, and the CRD body 14 can be completely removed from the CRD housing 13 by further lowering the CRD body 14.

(Problems to be Solved by the Invention) By the way, the CRD body 14 is attached to the CRD housing 13 during the periodic inspection.
However, when the CRD body 14 and the control rod 11 shift from the connected (coupling) state to the uncoupled (uncoupled) state in the work of removing the CRD body 14, the connection is released for some reason. Becomes incomplete, the hollow piston 18 is attached to the control rod 11, and the CRD body 14 cannot be removed from the CRD housing 13.

Further, if the CRD body 14 is forcibly pulled out while being connected to the control rod 11, the hollow piston 18 and the ball nut 24 may be separated, and the connection may be released due to vibration or the like when the CRD main body 14 is pulled out considerably. In this case, the hollow piston 18 falls by its own weight, and the ball nut 24 that receives the piston 18
A large impact load is applied to the ball nut 24, and the ball nut 24 may be damaged.

For this reason, when removing the CRD main body 14 from the CRD housing 13, it is necessary to accurately check whether or not the connection between the hollow piston 18 and the control rod 11 has been released.

In the conventional CRD handling device, a load cell such as a load cell is attached to the CRD handling device main body to monitor the weight of the CRD main body 14 and the hollow piston 18. However, since the load of the hollow piston 18 is very small with respect to the entire load of the CRD body 14, it is difficult to detect the weight of the hollow piston 18,
There was a problem that it could not be detected accurately.

The present invention has been made in consideration of the above circumstances, and has a CR
To provide a method and an apparatus for handling a control rod drive mechanism capable of accurately detecting whether or not the connection between a D main body and a control rod is released and removing the CRD main body from the CRD housing stably and smoothly. It is in.

[Structure of the Invention] (Means for Solving the Problems) The method of handling a control rod drive mechanism according to the present invention, as described in claim 1, has the following features. It comprises a control rod drive mechanism housing fixed through the bottom wall, and a control rod drive mechanism main body fixed to the housing and detachably fixed, and the control rod drive mechanism main body is driven by an electric motor provided at a lower portion. A ball screw shaft that is driven to rotate, a ball nut that is driven up and down by rotation of the ball screw shaft, a hollow piston whose lower part is held by the ball nut and that is driven up and down along the ball screw shaft, A coupling member provided at an upper portion of the piston, which is inserted into a coupling hole formed at a lower portion of the control rod, and then is rotated to engage the fixing member. In the method for handling a control rod driving mechanism for removing the electrically driven control rod driving mechanism, the disconnection between the control rod and the control rod driving mechanism main body is detected by movement detecting means for detecting the movement of the hollow piston. This is a handling method of removing the control rod drive mechanism main body from the control rod drive mechanism housing after confirming the disconnection by the detection means.

According to another aspect of the present invention, there is provided a control rod driving mechanism housing fixedly penetrated to a bottom wall of a reactor pressure vessel, as set forth in claim 2, in order to solve the above-mentioned problem. And a control rod drive mechanism main body fixed to the housing and detachably fixed, the control rod drive mechanism main body includes a ball screw shaft rotatably driven by an electric motor provided at a lower portion, and a ball screw shaft. A ball nut that is driven up and down by rotation of a shaft, a hollow piston whose lower portion is held by the ball nut and is driven up and down along the ball screw shaft, and a coupling member provided at an upper portion of the hollow piston. This coupling member is disassembled into an electrically driven control rod drive mechanism that is inserted into a coupling hole formed in the lower part of the control rod, then rotated and engaged and fixed. In the handling device of the control rod drive mechanism to be erected, disconnection detection means for detecting disconnection between the control rod drive mechanism body and the control rod is provided, and the disconnection detection means is means for detecting the movement of the hollow piston. It is composed.

In the handling device for a control rod drive mechanism according to claim 3, the disconnection detection means is provided at an outer lower portion of the control rod drive mechanism housing and detects magnetism of a magnet incorporated in a lower portion of the hollow piston. It is a thing.

In the handling device for a control rod drive mechanism according to claim 4, the disconnection detecting means includes an elastic supporting means for elastically supporting a load on the ball screw shaft and the hollow piston, and a load on the ball screw shaft and the hollow piston. And load detecting means for detecting the load.

In the handling device for a control rod drive mechanism according to claim 5, the connection detecting means includes a fluid cylinder means for vertically supporting a lower portion of the ball screw shaft and the hollow piston, and a load of the ball screw shaft and the hollow piston. And load detecting means for detecting the load.

(Operation) In the method and the apparatus for handling the control rod drive mechanism of the present invention, the presence / absence of the connection (coupling) state between the control rod and the control rod drive mechanism body is accurately determined by the connection release detection means, and the control is performed. When the rod and the control rod drive mechanism are correctly disconnected from each other, the control rod drive mechanism body can be stably and smoothly removed from the control rod drive mechanism housing.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

A control rod drive mechanism (CR) attached to the bottom (lower mirror) 3a of the reactor pressure vessel 3 of a boiling water reactor as a light water reactor
D) The structure of 40 is not substantially different from the control rod drive mechanism 1 shown in FIGS. 7 to 9, and the same parts are denoted by the same reference numerals and description thereof will be omitted.

The control rod drive mechanism body (CRD body) 41 of this CRD40 is CRD
It can be inserted into the housing 13 and mounted.
Control rod drive mechanism handling device (CRD handling device) 44
Are configured as shown in FIG. This handling equipment 44
Can be engaged with CRD body flange 17
The CRD main body 41 from which the spool piece 25 and the electric motor 23 (see FIG. 8) have been removed is supported on the handling device main body 45 so as to be able to move up and down.

The CRD body 41 includes an outer tube 15 housed in the CRD housing 13, a cylinder tube 16 housed in the outer tube 15, and a hollow piston assembly 46 housed in the cylinder tube 16 so as to be able to move up and down. And a ball screw assembly for driving the hollow piston assembly 46 up and down
And a motor 23 (FIG. 8) for driving the ball screw assembly 47 via the drive shaft 22. Hollow piston assembly 46 of CRD body 41 is hollow piston 1
It has a coupling member 19 provided at the upper end of 8, and a plurality of magnets 48 incorporated at the lower end thereof. For example, two magnets 48 are incorporated in the lower end of the hollow piston 18 so as to oppose each other in the diameter direction. The coupling relationship between the coupling member 19 and the control rod 11 is the same as the conventional one shown in FIGS.

In addition, a seal mechanism 50 is formed in a large-diameter portion below the outer tube 15 of the CRD main body 41. The sealing mechanism 50 includes an annular groove 51 formed on the outer tube 15 side and the annular groove 51.
And a seal ring 52 attached to the 51.

Further, when the CRD main body 41 is detached from the CRD housing 13, a connection release detecting means 55 is provided outside the CRD housing 13 for detecting whether or not the control rod 11 and the CRD main body 41 are connected (coupling). The disconnection detecting means 55 is preferably attached at the time of periodic inspection, but may be attached permanently.

The disconnection detecting means 55 is composed of magnetic detecting means such as a reed switch, an induction coil, or a magnetic sensor such as a semiconductor sensor, detects the magnetism of the magnet 48 incorporated in the hollow piston 18, and detects the magnetic force of the hollow piston 18. Detects movement. The magnetic detecting means serving as the disconnection detecting means 55 is a movement detecting means of the hollow piston 18 which is linked to the magnet 48 incorporated in the hollow piston 18 of the CRD main body 41 by the disconnecting means (uncoupled position). The magnetic detecting means detects the movement of the hollow piston 18 and detects the state of disconnection between the CRD main body 41 and the control rod 11.

Specifically, the disconnection detecting means 55 is configured to control the control rod 11 and the CRD.
In order to detect the disconnection state of the main body 41 from the coupling member 19, the main body 41 is opposed to the magnet 48 at a position rotated by 45 degrees from the coupling position (coupling position) shown in FIGS. 12 and 13. It has become.

A detection switch (not shown) for measuring the scrum time of the electric CRD is provided outside the CRD housing 13 by being incorporated in a rod-shaped member. This detection switch measures the time when the hollow piston 18 is inserted into the reactor during scram, and the CRD housing flange 13A, CRD
The main body flange 17 and the spool piece 25 are provided through the flanges. However, this detection switch is
At the time of regular inspection of 0, remove the spool piece 25 and
It is necessary to remove 41 in advance in order to rotate 41 by 45 degrees to uncouple.

Next, handling of the control rod drive mechanism during periodic inspection will be described.

At the time of periodic inspection of the CRD40, the CRD body 41 is
In this removal operation, as shown in FIG. 1, the spool piece 25 and the electric motor 23 (see FIG. 8) are removed from the CRD body 41, and then the CRD housing flange 13A and the CRD body flange are removed. Loosen the mounting bolts fastening 17 to release the fixation of the CRD main body 41 to the CRD housing 13 and support the CRD main body 41 on the CRD handling device 44.

Subsequently, the CRD main body 41 is lowered by a predetermined amount 1, for example, a few mm (see FIG. 2), and the CRD main body 41 is rotated 45 degrees with a gap provided between the CRD housing 13 and the CRD main body flange 17.
The gap is for protecting the seal ring 29 when the CRD body 41 is rotated.
The lowering of the main body 41 is temporarily stopped. In this state, control rod 11
The connection with the CRD main body 41 is set at a position where the connection can be released, and the connection release state is detected by the connection release detecting means 55.

At this time, the upper surface of the upper guide 33 of the CRD body 41 is in contact with the inner surface of the top of the CRD housing 13, and the buffer disc spring row 34 interposed between the upper guide 33 and the cylinder tube 16 is slightly compressed. It is in.

In this state, as shown in FIGS. 10 and 11, the phase is adjusted so that the four engagement plates 19A of the coupling member 19 are fitted into the respective engagement recesses 31A of the coupling hole 31 of the control rod 11. Are combined. From this phase matching state, CRD
When the main body 41 is lowered as it is, the coupling hole of the control rod 11
The coupling member 19 of the hollow piston 18 is disengaged from 31 and enters an uncoupling state. At this time, the hollow piston 18
The magnet 48 at the lower end operates the connection release detecting means 55,
It can be detected that the CRD body 41 has come off the control rod 11 without fail.

Further, the work of inserting and mounting the CRD main body 41 into the CRD housing 13 is omitted because there is no difference from the conventional one.

Thus, by providing the disconnection detecting means 55 outside the CRD housing 13 and operating the detecting means 55 by the magnet 48 provided on the hollow piston 18, the CRD main body 41 is provided.
Is removed from the CRD housing 13, it can be detected that the hollow piston 18 has come off the control rod 11 without fail.

 Next, another embodiment of the CRD handling device will be described.

FIG. 3 shows a second embodiment of the CRD handling device 44A. This CRD handling device 44A is provided with an elastic support mechanism 57 as a buffer support device for independently and elastically supporting the hollow piston assembly 46 and the ball screw assembly 47 in the CRD handling device main body 45. It is designed to absorb 18 drop impacts.

The elastic support mechanism 57 has a guide shaft 59 erected in a central recess 58 of the CRD handling device main body 45. The guide shaft 59 is provided with a support 61 such as a coil spring and a seat 61 which can be engaged with the lower end coupling portion 21a of the ball screw shaft 21. The seat 61 projects from the top head of the guide shaft 59. 59a
Regulated by The ball screw assembly 47 and the hollow piston assembly 46 are elastically supported by the support spring 60 and the seat 61.

When the lower end of the CRD body 41 is supported by the CRD handling device body 45, the elastic support mechanism 57 provided on the handling device body 45 supports the hollow piston assembly 46 and the ball screw assembly 47,
When the elastic support mechanism 57 supports only the hollow piston assembly 46 or the ball screw assembly 47, the support spring 60 hardly undergoes elastic deformation, is rigidly supported, and when the load of the control rod 11 is applied. The support spring 60 is elastically deformed by receiving a large load, and is elastically supported.

By detecting this support state, the coupling member is detected.
It can be accurately determined whether or not the connection between the control rod 19 and the control rod 11 has been securely performed.

As described above, the CRD main body 41 is incorporated into the CRD handling device main body 45 by setting the elastic strength of the support spring 60 to an appropriate value by incorporating the elastic support mechanism 57 as a buffer support device.
At the time of attachment / detachment work for attaching or detaching to / from the housing 13, the elastic support mechanism 57 supports the hollow piston assembly 46 and the ball screw assembly 47 and strongly presses the coupling member 19 on the control rod 11, so that the coupling member 19 and the control rod 11 is reliably coupled, and it can be determined whether or not the coupling is performed correctly. Reference numeral 62 denotes a spring seat for the support spring 60.

Next, the third control device of the control rod drive mechanism according to the present invention will be described.
An embodiment will be described with reference to FIG.

The handling device 44B of the CRD 40 shown in this embodiment includes a fluid cylinder device 63 as a buffer support mechanism on the CRD handling device main body 45.
And a receiving seat 65 may be provided at the tip of a piston rod 64 protruding from the fluid cylinder device 63, and the receiving seat 65 may support the hollow piston assembly 46 and the ball screw assembly 47.

Further, as shown in FIGS. 5 and 6, a load detecting means 66 such as a load cell is incorporated in the elastic support mechanism 57 as a buffer support device and the fluid cylinder device 63, and the elastic support mechanism 57 and the fluid The work of attaching and detaching the CRD body 41 to and from the CRD housing 13 may be performed while detecting the load acting on the cylinder device 63.

In this case, the load detecting means 66 has a function of a disconnection detecting means and can detect the load of the hollow piston assembly 46 and the ball nut assembly 47, so that the hollow piston 18 accurately acts on the load detecting means 66. And the load detecting means 66 can detect the coupling state between the control rod 11 and the CRD main body 41.

〔The invention's effect〕

As described above, in the method and the apparatus for handling the control rod drive mechanism according to the present invention, the presence or absence of the connection state between the control rod of the electric drive type control rod drive mechanism and the control rod drive mechanism body is determined by the hollow. The CRD body can be removed from the CRD housing by confirming the disconnection between the control rod and the control rod drive mechanism accurately by the disconnection detection means that detects the movement of the piston, so the CRD body removal work is stable Can be performed smoothly and smoothly, and disconnection (uncouple)
The trouble that the hollow piston of the CRD body remains without coming off from the control rod due to a defect can be prevented beforehand and surely, and the delay of the periodic inspection work due to the trouble countermeasures can be prevented, so that the work can proceed efficiently.

Further, since the disconnection detecting means, which is a handling device of the control rod drive mechanism of the present invention, is formed by magnetic detection means provided on the lower outside of the CRD housing, the control rod drive mechanism of the electric drive type is also incorporated in the hollow piston. It operates with the magnet and detects the movement of the hollow piston and can reliably detect that the hollow piston and thus the CRD main body have come off the control rod.

Further, the coupling release detecting means is constituted by the elastic support means and the load detecting means located at the lower part of the CRD main body, or is constituted by the fluid cylinder means and the load detecting means, so that the electric drive type control rod driving mechanism is hollow. It is possible to detect whether or not the piston is acting correctly on the load detecting means, and it is possible to detect the coupling state between the control rod and the CRD body by the load detecting means.

[Brief description of the drawings]

1 and 2 show an embodiment of a control rod driving mechanism handling device according to the present invention. FIGS. 3 to 6 show a control rod driving mechanism handling device according to a second embodiment of the present invention. FIG. 7 is a longitudinal sectional view showing a schematic configuration of a conventional general boiling water reactor, and FIG. 8 is a longitudinal sectional view of a conventional control rod driving mechanism. , FIG. 9 is a longitudinal sectional view showing a conventional control rod driving mechanism handling device, FIG. 10 is a sectional view showing a state where a coupling member is inserted into a control rod lower coupling hole, and FIG. 11 is FIG. FIG. 12 is a cross-sectional view taken along the line XI-XI of FIG. 12, FIG. 12 is a cross-sectional view showing a state where the coupling member is inserted into the lower hole of the control rod and then rotated by 45 ° to engage the both, and FIG. 13 is FIG. FIG. 3 is a sectional view taken along line XIII-XIII of FIG. DESCRIPTION OF SYMBOLS 1 ... Control rod drive mechanism, 3 ... Reactor pressure vessel, 6 ... Core part, 11 ... Control rod, 12 ... Control rod guide tube, 13 ... Control rod drive mechanism housing, 18 ... Hollow piston, 19 ... Coupling member , 21: Ball screw shaft, 23: Electric motor, 24: Ball nut, 25: Spool piece, 31: Coupling hole, 40: Control rod drive mechanism (CRD), 41: Control rod drive mechanism body, 44, 44
A, 44B: Control rod drive mechanism handling device, 45: Control rod drive mechanism handling device body, 46: Hollow piston assembly, 47: Ball screw assembly, 48: Magnet, 50: Seal mechanism, 52: Seal ring, 55 ... disconnection detecting means, 57 ... elastic support mechanism,
60 ... support spring, 63 ... fluid cylinder device, 66 ... load detecting means.

Claims (5)

(57) [Claims] 1. A control rod drive mechanism housing fixedly penetrated to a bottom wall of a reactor pressure vessel, and mounted on the housing.
A control rod drive mechanism body detachably fixed, the control rod drive mechanism body being driven up and down by rotation of a ball screw shaft that is rotationally driven by an electric motor provided at a lower portion, and the ball screw shaft. A ball nut, a lower part held by the ball nut, a hollow piston driven up and down along the ball screw axis, and a coupling member provided on the upper part of the hollow piston. In a method of handling a control rod drive mechanism for removing an electrically driven control rod drive mechanism which is inserted into a coupling hole formed at a lower portion of the control rod and then rotated and fixedly engaged, the control rod and the control rod drive mechanism main body are removed. The disconnection is detected by movement detection means for detecting the movement of the hollow piston, and after confirming the disconnection by the movement detection means, the control rod drive mechanism Handling of the control rod drive mechanism, characterized in that removal of the body from the control rod drive mechanism housing. 2. A control rod drive mechanism housing penetrating and fixed to a bottom wall of a reactor pressure vessel, and mounted on the housing.
A control rod drive mechanism body detachably fixed, the control rod drive mechanism body being driven up and down by rotation of a ball screw shaft that is rotationally driven by an electric motor provided at a lower portion, and the ball screw shaft. A ball nut, a lower part held by the ball nut, a hollow piston driven up and down along the ball screw axis, and a coupling member provided on the upper part of the hollow piston. A control rod drive mechanism handling device for disassembling and assembling an electrically driven control rod drive mechanism which is inserted into a coupling hole formed in a lower portion of the control rod, and then is rotated and fixedly engaged therewith. Disconnection detecting means for detecting disconnection with the control rod is provided, and the disconnection detecting means is means for detecting movement of the hollow piston. Handling apparatus control rod drive mechanism to symptoms. 3. The control rod according to claim 2, wherein said disconnection detection means is a magnetic detection means provided at a lower portion outside the control rod drive mechanism housing and configured to detect magnetism of a magnet incorporated in a lower portion of the hollow piston. Handling device for drive mechanism. 4. The uncoupling detecting means comprises elastic support means for elastically supporting the load on the ball screw shaft and the hollow piston, and load detecting means for detecting the load on the ball screw shaft and the hollow piston. An apparatus for handling a control rod drive mechanism according to claim 2. 5. The connection detecting means comprises fluid cylinder means for vertically supporting a lower portion of a ball screw shaft and a hollow piston, and load detecting means for detecting a load on the ball screw shaft and the hollow piston. An apparatus for handling a control rod drive mechanism according to claim 2.