JPH03211495A - Method and device for handling control rod driving mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

(Conventional technology) Boiling water reactor (hereinafter referred to as BWR) is a light water reactor.

), reactor operation (startup/shutdown) and reactor power control are performed by moving control rods in and out of the reactor core.
The control rods are 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, a large number of conventional CRD1 are provided in the lower part (lower mirror part) of the reactor pressure vessel 3 of the BWR 2. While the reactor pressure vessel 3 is filled with reactor water, a reactor core shroud 4 is provided inside the reactor pressure vessel 3, and a reactor core section 6 in which a large number of fuel assemblies 5 are mounted is configured within the shroud 4. The fuel assembly 5 is supported by a core support plate 7 and an upper lattice plate 8 and is erected. Core shroud 4 housing fuel assembly 5
is covered by a shroud head 9, while a steam separator 10 is provided above the shroud head 9, and the steam separated by the steam separator 10 is dried in a steam dryer (not shown). turned into steam.

Further, a control rod 11 is located in a gap formed by a set of four fuel assemblies 5 having a cross-shaped cross section.
This control rod 11 is driven and controlled by an electric CRD 1. This CRDI is a control rod drive mechanism housing (hereinafter referred to as a CRD housing) that is fixed through the bottom wall (lower mirror part) of the reactor pressure vessel 3.

) 13 and a control rod drive mechanism main body (hereinafter referred to as the CRD main body) 14 inserted and fixed into the CRD housing 13 from below, and the control rod 11 is inserted into the reactor core 6 or Extraction is carried out,
It is designed to control the furnace output.

As shown in FIG. 8, the electric CRD 1 has an outer tube 15 housed within the CRD housing 13, and a cylinder tube 16 is housed within the outer tube 15. A CRD main body flange 17 is integrally attached to the lower end of the outer tube 15, and the cylinder tube 16
A hollow piston 18 is housed on the inner peripheral side thereof so as to be movable up and down.

A coupling member 19 is attached to the upper end of the hollow piston 18, and is connected to the control rod 11 via the coupling member 19.

Furthermore, a plurality of magnets 20 are integrated into the lower end portion of the hollow piston 18 .

On the other hand, a ball screw shaft 21 is arranged to penetrate inside the hollow piston 18, and this ball screw shaft 21 is connected to a shaft 22.
Rotational driving force is transmitted from the electric motor 23 via the motor. This ball screw shaft 21 has a ball nut 2.
4 are screwed together.

The shaft 22 portion is accommodated in a spool piece 25 fixed to the CRD main body flange 17 from below, and the electric motor 23 is fixed below this spool piece 25. Further, a seal member 27 is installed between the shaft 22 and the spool piece 25 via a seal box 26.

By the way, the CRD1 has two functions: one for inserting or withdrawing the control rods 11 at a relatively low speed (hereinafter referred to as shim operation) in order to adjust and maintain the reactor output at a predetermined state, and the other to stop the reactor in an emergency. There is an operation of inserting the control rod 11 at high speed (hereinafter referred to as a scram operation). The shim operation drives the electric motor 23 to rotate the ball screw shaft 21 via the shaft 22. This rotation of the ball screw shaft 21 causes the pole nut 24 to rise, causing the hollow piston 18 to rise. As a result, the control rod 11 is inserted by a predetermined amount at a low speed. Conversely, when withdrawing the control rod 11, the electric motor 23 is rotated in the opposite direction. Due to the reverse rotation of the electric motor 23, the ball screw shaft 2
1 rotates in the opposite direction, the pole nut 24 descends, and at the same time the hollow piston 18 also descends. As a result, the control rod 11 is withdrawn by a predetermined amount at a low speed.

In addition, in the scram operation, high-pressure water is supplied from a high-pressure water injection mechanism (not shown) through the flange 13A of the CRD body 13 and the high-pressure water supply port 28 formed in the CRD body 17, and the high pressure acts on the hollow piston 18. do. Due to the action of this high pressure, the hollow piston 18 separates from the pole nut 24 and ascends at high speed, thereby inserting the control rod 11 into the reactor core at high speed. This will result in an emergency shutdown of the reactor.

Next, the operation of inserting and attaching the CRD main body 14 into the CRD housing 13 will be explained. First, as shown in FIG. 9, with the spool piece 25 and electric motor 23 separated from the CRD main body 14,
C using a CRD handling device (not shown) as a switch.
Insert into the RD housing 13 from below. and C.R.
The D body 1-4 is connected to the control rod 11 via a coupling member 19 at the upper end of the hollow piston]8. That is, the first
As shown in FIGS. 0 and 11, the coupling member 19
is provided with four engagement plates 19A.

On the other hand, a coupling hole 31 is formed at the lower end of the control rod 11, and four four portions 31A are formed on the inner peripheral surface of the coupling hole 31 to fit into the four engagement plates 19A. . The CRD main body 14 is inserted into the CRD housing 13 in a state in which the four engagement plates 19A are aligned so that they fit into the four engagement parts 31A.

Even after the four engaging plates 19A of the coupling member 19 are completely inserted into the coupling hole 31, the CRD main body 14 is held until the control rod 11 is slightly lifted to ensure the inserted state. CRD housing 13
Insert inside.

Due to the insertion of the CRD body 14, the control rod 1 is slightly separated from the seating surface of the control rod guide tube 12, so the sealing function for reactor water is lost, and reactor water flows out from between the control rod 11 and the control rod guide tube 12. . The outflowing reactor water passes through the upper surface side of the upper guide 33 and flows down between the outer tube 15 and the CRD housing 13 and is sealed by the sealing 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 attached to the annular groove.

In addition, when inserting the CRD main body 14, in order to protect the seal ring 29 of the CRD main body flange 17, the CRD
The insertion of the CRD body 4 is stopped with a gap provided between the flange 13A of the housing 13 and the CRD body flange 17. At this time, the upper guide 3 of the CRD main body 14
The upper surface of CRD housing 13 is in contact with the inner surface of the upper end of CRD housing 13, and buffer disc spring array 34 installed between upper guide 33 and cylinder tube 16 is in a slightly compressed state.

Next, as shown in FIGS. 12 and 13, the CRD main body 1
4 by 45 degrees to properly couple the coupling member 19 and the coupling hole 31.
4 and the control rod 11 are connected. After this connection, the CRD main body 14 is further inserted into the CRD housing 13, and the CRD housing flange 13 is attached with a mounting bolt (not shown).
A and the flange 17 of the CRD main body 14 are connected to fix the CRD main body 14 to the CRD housing 13. After that, the spool piece 25 and the electric motor 23 are attached in sequence.

Next, the operation of removing the CRD main body 14 from the housing 13 will be explained.When removing the CRD main body 14, the spool piece 25 and the electric motor 23 are first removed from the CRD 1. After that, loosen the mounting bolts (not shown) that fasten the CRD main body flange 17 to the CRD housing flange 13A,
The fixation of the CRD main body 14 to the CRD housing 13 is released. At this time, the CRD main body 14 is supported by a CRD handling device (not shown) serving as a CRD exchanger.

Next, by lowering the CRD handling device, the CR
Lower the D main body 14. At that time, the CRD body flange 17
In order to protect the seal ring 29, the lowering of the CRD body 14 is temporarily stopped with a slight gap formed between the CRD housing flange 13A and the CRD body flange 17. At this time of stopping, the upper surface of the upper guide 33 of the CRD main body 14 is in contact with the top wall surface of the CRD housing 13, and the buffer circumferential spring array 34 installed between the upper guide 33 and the cylinder tube 16 is slightly compressed. is in a state of

In the state shown in FIG. 9, the CRD main body 14 is rotated 45 degrees to connect the four engagement plates 19A of the coupling member 19 and the four engagement recesses 31 on the inner peripheral surface of the coupling hole 31 at the lower end of the control rod 11. As shown in FIGS. 10 and 11, the CRD main body 14 is lowered again in this phased state.

At this time, the control rod 11 descends together with the CRD body 14 and contacts the control rod guide tube 12 to form a reactor water sill structure, and the descending of the control rod 11 is stopped at this position.

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

(Problem to be Solved by the Invention) By the way, the CHD main body 14 is removed from the CRD housing 13 during periodic inspection. ) state to the uncoupling state, if the uncoupling becomes incomplete for some reason, the hollow piston 18 is attached to the control rod 11, and the CRD body 14 is connected to the CRD housing 1.
It becomes impossible to remove from 3.

Also, if the CRD body 14 is forcibly pulled out while connected to the control rod 11, the hollow piston 18 and pole nut 2
4 may separate and the connection may be broken due to vibration etc. even if it is pulled out considerably.

In this case, the hollow piston 18 falls due to its own weight, and a large impact load is applied to the pole nut 24 that receives the piston 18, potentially damaging the pole nut 24.

Therefore, when removing the CRD body 14 from the CRD housing 13, it is necessary to accurately confirm whether the connection between the hollow piston 18 and the control rod 11 has been released.

In conventional CRD handling equipment, a load meter such as a load cell is attached to the main body of the CRD handling equipment 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 compared to the overall load of the CRD main body 14, there have been problems such as difficulty in detecting the weight of the hollow piston 18 or inability to accurately detect it.

The present invention has been made in consideration of the above-mentioned circumstances, and is
To provide a method and device for handling a control rod drive mechanism that can accurately detect whether or not the connection between a D main body and a control rod is released and can stably and smoothly remove a CRD main body from a CRD housing. It is in.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above-mentioned problems, a method for handling a control rod drive mechanism according to the present invention includes a method for handling a control rod drive mechanism in which a control rod drive mechanism main body is removed from a control rod drive mechanism housing. In the method, the presence or absence of a connection between the control rod and the control rod drive mechanism body is detected by a disconnection detection means, and the control rod is driven while monitoring that the control rod and the control rod drive mechanism body are disconnected. A method for removing a mechanism body from a control rod drive mechanism housing is provided.

In addition, in order to solve the problems of the prior art, the control rod drive mechanism handling device of the present invention includes a control rod drive mechanism housing that is fixed through the bottom wall of a reactor pressure vessel, and a control rod drive mechanism that is attached to and removed from the housing. a control rod drive mechanism body that can be fixed to the control rod drive mechanism body; and a control rod drive mechanism handling device body that supports the control rod drive mechanism body so that it can be raised and lowered when the control rod drive mechanism body is attached to or removed from the control rod drive mechanism housing. A control rod drive mechanism handling device having: a connection release detection means for detecting a state of connection release between the control rod drive mechanism main body and the control rod;
When the control rod drive mechanism body is removed from the control rod drive mechanism housing, the connection release between the control rod and the control rod drive mechanism body can be monitored.

(Function) In the control rod drive mechanism handling method and the handling device of the present invention, the presence or absence of the coupling state between the control rod and the control rod drive mechanism main body is accurately determined by the coupling release detection means, and the control rod drive mechanism is controlled by When the rod and the control rod drive mechanism are accurately disconnected, the control rod drive mechanism main body can be stably and smoothly removed from the control rod drive mechanism housing.

(Example) Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

A control rod drive mechanism (CR
D) The configuration of 40 is not substantially different from the control rod drive mechanism 1- shown in FIGS. 7 to 9, so the same parts are given the same reference numerals and the explanation will be omitted.

This CRD40 control rod drive mechanism body (CRI) body)
41 into the CRD housing 13 and install it.
A control rod drive mechanism handling device (CRD handling device) 44, which is removed from the RD housing 13, is constructed as shown in FIG. This handling device 44 is connected to the CRD main body flange 17.
The spool piece 25 and the electric motor 2 are mounted on the CRD handling device body 45, which can be engaged with the CRD handling device body 45.
3 (see FIG. 8) is supported so that it can be freely lowered.

The CRD main body 41 includes an outer tube 15 housed within the CRD housing 13, a cylinder tube 16 housed within the outer tube 15, and a cylinder tube 1.
A hollow piston assembly 46 that is housed in the hollow piston assembly 46 and can be raised and lowered, a ball screw assembly 47 that drives the hollow piston assembly 46 up and down, and a ball screw assembly 47 that drives the hollow piston assembly 46 up and down;
7 via a drive shaft 22
3 (Fig. 8), etc. The hollow piston assembly 46 of the CRD main body 41 includes a coupling member 19 provided at the upper end of the hollow piston 18 and a plurality of magnets 48 incorporated at the lower end thereof. magnet 48
For example, two are installed in the lower end of the hollow piston 18 so as to be diametrically opposed to each other. Coupling member 19 and control rod 1
1 is the same as the conventional one shown in FIGS. 10 to 13, so a description thereof will be omitted.

Further, a sealing mechanism 50 is formed in the lower large diameter portion of the outer tube 15 of the CRD main body 41.

This sealing mechanism 50 is comprised of an annular groove 51 formed on the outer tube 15 side and a seal ring 52 mounted in this annular groove 51.

Further, when removing the CRD main body 41 from the CRD housing 13, the control rod 11 is attached to the outside of the CRD housing 13.
A coupling release detection means 55 is provided for detecting the presence or absence of a coupling state between the CRD body 41 and the CRD main body 41 . This disconnection detection means 55 is preferably installed during periodic inspection, but may be installed permanently.

The connection release detection means 55 is constituted by a magnetic detection means such as a reed switch, an induction coil, or a magnetic sensor such as a semiconductor sensor, and detects the connection release position (
(uncoupled position) to detect the disconnection state between the CRD main body 41 and the control rod 11.

Specifically, the connection release detection means 55 detects that the control rod 11 and C
In order to detect the disconnection state of the RD main body 41 with the coupling member 19, the RD main body 41 is opposed to the magnet 48 at a position rotated by 45 degrees from the coupling position (coupling position r!!,) shown in FIGS. 12 and 13. It is designed to work properly.

Further, a detection switch (not shown) for measuring the scrum time of the electric CRD is provided on the outside of the CRD housing 13 and is incorporated into a rod-shaped member. This detection switch measures the time during which the hollow piston 18 is inserted into the reactor during scram, and detects the presence of the CRD housing flange 13A, CRD body flange 17, and spool piece 2.
It is provided to penetrate through the flange of 5. However, this detection switch needs to be removed in advance because during periodic inspection of the CRD 40, the spool piece 25 is removed and the CRD main body 41 is rotated 45 degrees to uncouple it.

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

During regular inspection of the CRD 40, the CRD main body 41 is removed from the CRD housing 13, but during this removal work, as shown in FIG. 1, the spool piece 25 and electric motor 23 (see FIG. 8) are removed from the CHD main body 41. Then, loosen the mounting bolts that fasten the CRD housing flange 13A and the CRD main body flange 17, release the fixation of the CRD main body 41 to the CRD housing 13, and then remove the CRD main body 41 from the CRD housing 13.
The D main body 41 is supported on the CRD handling device 44.

Next, add a predetermined amount of CRD main body 41! , for example, several carp lowered (
(see FIG. 2), the CRD body 41 is rotated 45 degrees with a gap provided between the CRD housing 13 and the CRD body flange 17. The gap is provided to protect the seal ring 29 when the CRD main body 41 is rotated, and the lowering of the CRD main body 41 is temporarily stopped with a slight gap formed.

In this state, the control rod 11 and the CRD main body 41 are set at a position where they can be disconnected, and this disconnection state is detected by the disconnection detection means 55.

At this time, the upper surface of the upper guide 33 of the CRD main body 41 is C
The top guide 3 contacts the top inner surface of the RD housing 13.
3 and the cylinder tube 16 is in a slightly compressed state.

In this state, as shown in FIGS. 10 and 11, the four engagement plates 19A of the coupling member 19 are connected to the control rod 11.
The phases are matched so that they fit into the respective engagement recesses 31A of the coupling holes 31. If the CRD main body 41 is lowered from this phasing state, the control rod 1
The coupling member 19 of the hollow piston 18 is removed from the coupling hole 31 of the piston 1, resulting in an uncoupled state.

At this time, the magnet 48 at the lower end of the hollow piston 18 operates the connection release detection means 55, and it is possible to reliably detect that the CRD main body 41 has come off from the control rod 11.

Further, the work of inserting and attaching the CRD main body 4J into the CRD housing 13 is omitted since there is no difference from the conventional work.

Therefore, a coupling release detection means 55 is provided on the outside of the CRD housing 13, and this detection means 55 is connected to the hollow piston 18.
By operating the magnet 48 provided in the
When the CRD main body 41 is removed from the CRD housing 13, it is possible to detect that the hollow piston 18 is reliably removed from the control rod 11.

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

FIG. 3 shows a second embodiment of the CRD handling device ff144A. This CRD handling device 44A is provided with an elastic support mechanism 57 as a buffer support device that elastically supports the hollow piston assembly 46 and the ball screw assembly 47 independently in the CRD handling device main body 45. It is designed to absorb the impact of a fall of 18.

In the elastic support mechanism 57, a guide shaft 59 is provided upright in a central recess 58 of the CRD handling device main body 45.

The guide shaft 59 is interposed with a support spring 60 such as a coil spring and a catch seat 61 that can engage with the lower end coupling portion 21a of the ball screw shaft 21. The catch seat 61 protrudes from the top of the guide shaft 59. It is regulated by the head 59a. The support spring 60 and seat 61 elastically support the ball spring assembly 47 and the hollow piston assembly 46.

When the CRD handling device main body 45 supports the lower part of the CRD main body 4, the elastic support mechanism 5 provided on the handling device main body 45
7 supports the hollow piston assembly section 46 and the ball screw assembly section 47, and the elastic support mechanism 57 supports the hollow piston assembly section 4
6 or the ball screw assembly 47, the support spring 60 hardly undergoes elastic deformation and is rigidly supported, and when the load of the control rod 11 is applied, the support spring 60 receives a large load. It is elastically deformed and elastically supported.

By detecting this support state, the coupling member 1
It is possible to accurately judge whether or not the connection between the control rod 9 and the control rod 11 is performed reliably.

In this way, the elastic support mechanism 57 as a buffer support device is incorporated into the CHD handling device main body 45, and its support spring 60
By setting the spring strength of
6 and the ball screw assembly 47, and forcefully push the coupling member 19 onto the control rod 11 to ensure that the coupling member 19 and the control rod 11 are coupled, and check whether the coupling is performed correctly. It can be seen that the reference numeral 62 is the spring seat of the support spring 6o.

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

The CRD 40 handling device 44B shown in this embodiment is
A fluid cylinder device 63 is provided as a buffer support mechanism in the CRD handling device main body 45, and a catch 65 is provided at the tip of a piston rod 64 protruding from the fluid cylinder device 63. The assembly portion 47 may be supported.

Furthermore, as shown in FIGS. 5 and 6, a load detection means 66 such as a load cell is incorporated into the elastic support mechanism 57 as a buffer support device and the fluid cylinder device 63, and this load detection means 66 is used to cylinder equipment r11
CR of the CRD main body 41 while detecting the load acting on the CRD 63
The attachment/detachment work to the D housing 13 may proceed.

In this case, the load detection means 66 has the function of a connection release detection means and can detect the loads of the hollow piston assembly 46 and the ball nut assembly 47, so whether the hollow piston 18 is acting accurately on the load detection means 66 or not. This load detection means 66 can detect whether the control rod 11 and the CRD main body 4
1 can be detected.

〔Effect of the invention〕

As described above, in the method and device for handling a control rod drive mechanism according to the present invention, the connection release detection means accurately determines whether or not the control rod is connected to the control rod drive mechanism main body, and the control rod drive mechanism is The CRD body can be taken out from the CHD housing after confirming that the rod and control rod drive mechanism are accurately disconnected, so the CRD body can be taken out stably and smoothly. (Uncoupling) It is possible to prevent troubles such as the hollow piston of the CRD body remaining stuck in the control rod due to a defect, and to prevent delays in periodic inspection work due to troubleshooting, and to proceed with work efficiently. .

[Brief explanation of drawings]

1 and 2 are views showing one embodiment of the control rod drive mechanism handling device according to the present invention, and FIGS. 3 to 6 are views showing a second embodiment of the control rod drive mechanism handling device according to the present invention. FIG. 7 is a vertical cross-sectional view showing the schematic configuration of a conventional general boiling water reactor; FIG. 8 is a vertical cross-sectional view of a conventional control rod drive mechanism. , FIG. 9 is a vertical sectional view showing a conventional control rod drive mechanism handling device, FIG. 10 is a sectional view showing a state in which the coupling member is inserted into the control rod lower coupling hole, and FIG. 11 is FIG. 12 is a cross-sectional view showing a state in which the coupling member is inserted into the lower hole of the control rod and then rotated by 45 degrees to engage the two; FIG. It is a sectional view along the store-store line. 1... Control rod drive mechanism, 3... Reactor pressure vessel, 6
... Reactor 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 River coupling hole, 40...Control rod drive mechanism (CRD), 41
...Control rod drive mechanism body, 44.44A, 44B...
・Control rod drive mechanism handling device, 45... Control rod drive mechanism handling device main body, 46... Hollow piston assembly section, 47.
...Ball screw assembly, 48...Magnet, 5o.
...Seal mechanism, 52...Seal ring, 55...
Connection release detection means, 57... elastic support mechanism, 60...
- Support spring, 63...Fluid cylinder device, 66...
Load detection means.

Claims (1)

[Claims] 1. In a method for handling a control rod drive mechanism in which a control rod drive mechanism body is removed from a control rod drive mechanism housing, the presence or absence of a coupling state between a control rod and a control rod drive mechanism body is detected using a coupling release detection means. A method for handling a control rod drive mechanism, comprising: detecting that the control rod and the control rod drive mechanism body are disconnected from each other, and removing the control rod drive mechanism body from the control rod drive mechanism housing. 2. A control rod drive mechanism housing that is fixed through the bottom wall of the reactor pressure vessel, a control rod drive mechanism main body that is attached to this housing and removably fixed, and a control rod drive mechanism main body that is fixed to the bottom wall of the reactor pressure vessel. In a control rod drive mechanism handling device that has a control rod drive mechanism handling device body that supports the control rod drive mechanism body so as to be able to move up and down when it is attached to or removed from a housing, the control rod drive mechanism body and the control rod are A disconnection detection means for detecting a disconnection state is provided,
A control rod drive mechanism characterized in that the disconnection detection means is configured to be able to monitor disconnection between the control rod and the control rod drive mechanism body when the control rod drive mechanism body is removed from the control rod drive mechanism housing. handling equipment.