JPS62217187A - Drive mechanism of control rod for nuclear reactor - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a control rod drive mechanism for inserting or igniting control rods into a nuclear reactor, and more specifically,
The present invention relates to a control rod drive mechanism that allows the height of the upper drive device to be shorter than that of conventional control rod drive mechanisms.

<Prior art> The ft1III4I drive mechanism (hereinafter abbreviated as rcRDJ) is a device for controlling reactor output by inserting or pulling control rods into the reactor core during reactor operation. Figure 7 shows an example of drawing and operation.

This will be explained with reference to FIGS. 8 and 9.

FIG. 7 shows a state where the control rod 15 is suspended almost at the lower limit (inside the reactor core), and shows an extension tube 4 having the gripper mechanism 1 at the lower end and a gripper operating shaft 2 housed in the extension tube.
extends vertically through the furnace shield plug 3. An upper drive device 5 installed above the shielding plug 3 moves the extension tube 4 up and down together with the gripper operating shaft 2, or moves the gripper operating shaft up and down relative to the extension tube 4.

The upper drive device 5 has the following structure. That is, a drive motor 7 is installed above the inside of the casing 6 and can rotate a ball screw 9 via a gear 8. A pole nut 10 is screwed onto the ball screw, and a power pole 11 and a stone 12 are suspended from the pole nut via a rod 11.
An armature 13 is attracted to and detachably engaged with the lower part of the electromagnet, and a link mechanism 14 is provided at the lower part of the armature. FIG. 7 shows a state in which the electromagnet 12 attracts the armature 13 to close the link mechanism 14, and the extension tube is held by the flange 4a formed on the outer periphery of the extension tube 4.

Furthermore, the gripper mechanism 1 includes a gripper finger 1a provided at the lower end of the extension tube 4 that expands and contracts in the radial direction, and a gripper finger cam 1b provided at the lower end of the gripper operating shaft 2.
It is possible to grip the control rod 15 by chucking and engaging the handling head 15a on the upper part of the control rod 15 from the inside by expanding outward by b.

In order to move the control rod 15 up and down while gripping the control rod 15 with the gripper mechanism 1, as shown in FIG.
Through electromagnet 12, armature 13, link special 1
4 can be moved up and down integrally, and the extension tube 4 can be operated as a gripper.
It is sufficient to move it up and down together with 11h2.

When scramming the reactor, when the Zunawara control rod 15 is quickly and deeply inserted into the reactor core (not shown) to make an emergency shutdown of the reactor, the electromagnet 12 is demagnetized as shown in FIG. By dropping the armature 13, the link [
Open 1414. As a result, the extension tube 4 is no longer held by the flange 4a, and the extension tube 4 suddenly falls together with the gripper operating shaft 2 while still gripping the control rod 15.

To release the chucking between the handling head 15a of the control rod 15 and the gripper mechanism 1, by holding and pulling up the flange 2a formed on the outside of the gripper operating shaft 2 with the link [@14, only the gripper operating shaft 2 can be released. can be pulled up relative to the extension tube 4, thereby only the gripper finger cam 1b at the lower end of the gripper operating shaft 2 is pulled up, and the outward expansion of the gripper fingers 1a is released and the gripper fingers 1a are retracted inward. Then, the gripper machine 1@1 and the control rod 15 can be disengaged.

<Problems to be Solved by the Invention> However, the above-mentioned CRD upper drive device 5
The height of the vertical movement of the pole nut 4 is 1 m or more (because the drive range of the control rod is about 1 m), and the extension tube 4
The vertical movement range of 1m or more is required, and the electromagnet 12
When the length of parts such as the armature 13 is added, the total height reaches 5 to 6 m, which poses a problem in earthquake resistance, and it is necessary to provide a means to prevent the vibration from swinging (not shown). Also,@
The structure is complex and there are many parts, which increases the probability of exaggeration, which is disadvantageous in terms of maintenance.

Therefore, this invention was made with the aim of shortening the height of the upper drive device of a CRD to improve earthquake resistance, as well as reducing the number of component parts to reduce the probability of failure and improve maintainability. be.

Means and operation for solving the problems> The CRD of the present invention has a gripper mechanism at the lower end that detachably grips the control rod, and an extension tube that extends vertically through the reactor shielding plug, and the extension tube. It consists of a gripper operating shaft housed within a tube and an upper drive device that moves the extension tube up and down together with or relative to the gripper operating shaft. The upper drive device is composed of a gear that meshes with the tooth profile formed on the outer surface of the upper part of the extension tube, and a drive motor that rotates the gear, and directly moves the extension tube up and down by the rotation of the gear. The armature is disposed through an electromagnet, and the armature is attracted by an electromagnet, and the gear and tooth profile engage with each other by falling.

Because of this configuration, when inserting a control rod into the reactor core or igniting it during normal operation of a nuclear reactor, the electromagnet in the upper drive unit is energized, the armature is attracted, and the gear is extended to fit the tooth profile on the outer surface of the tube. By rotating the gear with the drive motor while meshing with the gear, the extension tube can be directly moved up and down, and therefore the control rod gripped by the gripper mechanism can be moved up and down.

In addition, when scramming a nuclear reactor, by magnetizing the electromagnet in the upper drive unit and pulling the armature apart, the gear will separate from the tooth profile, and the control rod will remain in the reactor core while being held by the gripper mechanism. Fall.

In a preferred embodiment M of the present invention, a gripper operating shaft holding fitting that can be freely protruded and retracted by a second drive motor is disposed near the upper part of the gripper operating shaft that projects from the upper end of the extension tube, and this holding fitting is At the protruding position, it engages with the upper part of the gripper operating shaft to prevent vertical movement of the gripper operating shaft.

The gripper la
The control rod can be gripped and released by engaging and disengaging the side and the control rod.

<Embodiments> The present invention will be described in detail below with reference to embodiments shown in the drawings.

FIG. 1 explains the entire CRD of the present invention, in which a gripper operating shaft 2 is housed inside an extension tube 4 that extends vertically through a furnace shielding plug 3, and a gripper operating shaft 2 is provided at the lower end of the extension tube 4. The control rod 15 is gripped and released by engaging and disengaging the gripper mechanism 1 with the handling head 15a of the control rod 15, and the control rod is gripped by moving the extension tube up and down while gripping the control rod 15 with the gripper 1fltlfii1. The basic functions for inserting and handling operations are:
It is the same as the conventional CRD.

The feature of this invention lies in the configuration of the upper drive device 20 installed above the shielding plug 3. That is, the upper drive device 2
A drive motor 22 and an electromagnet 23 are located inside the casing 21 of 0.
A gear 24 is positioned at a fixed position and rotated by a drive motor 22.
and the tooth profile 25 formed on the outer surface of the upper part of the extension tube 4 mesh with each other. Also, electric f11 stone 23 is demachi 1a 26
and is linked to the gear 24 via a link mechanism 27. A roller 28 is fixed by a support plate 29 on the back side of the extension tube 4 where the tooth profile 25 of the extension tube and the gear 24 mesh.
It is in contact with the extension tube 4. This roller 28 is connected to the gear 24
In addition, as shown in Fig. 2 and Fig. 3, the extension tube 4 is fitted perfectly with the outer surface of the extension tube 4 to prevent misalignment when the extension tube is moved up and down. make a move.

As clearly shown in FIG.
0, and the gear 2 is fixed via the clutch 31.
Rotate 4. This clutch 31 not only transmits and interrupts the rotation of the drive motor 22 to the gear 24, but also allows the shaft of the drive motor 22 and the shaft of the gear 24 to be shifted relative to each other at the clutch 31 portion. The operation of the upper drive device for the ditch will be explained. When moving the control rod 15 up and down while gripping it with the gripper mechanism 1 as shown in FIG. 1, the electromagnet 23 is excited to attract the armature 26 as shown in FIG. Press the gear 24 against the extension tube 4 to form the tooth profile 25.
The drive motor 22 may be rotated by meshing with the drive motor 22.

By demagnetizing the electromagnet 23 as shown in FIG.
operates, and the gear 24 and tooth profile 25 are disengaged. At the same time, the clutch 31 between the drive motor 22 and the gear 24 is disengaged. In this way, the extension tube 4 is no longer held by the gear 24, and the free extension tube 4 and gripper operating shaft 2 fall while gripping the control rod 15.

If the electromagnet 23 is excited again from this state, the armature 26 will be attracted to the electromagnet 23 and at the same time the link mechanism 2
7 is activated, the gear 24 meshes with the tooth profile 25, and the clutch 31 is roughly connected, resulting in the states shown in FIGS. 2 and 3.

In the illustrated embodiment, a rack and pinion system consisting of a combination of a tooth profile 25 1 m outside the extension tube and a spur gear 24 is used as the extension tube driving means, but a worm gear using a threaded gear (worm) is used. method can also be adopted.

Further, in the illustrated embodiment, a driving means 24 is provided on one side of the extension tube 4.
25. Although the roller 28 is provided on the other side, driving means may be provided on both sides of the extension tube without providing the roller.

The gripping and separating operation of the control rod 15 by the gripper mechanism 1 can be performed by the relative vertical movement of the gripper operating shaft 2 and the extension tube 4, as in the conventional case. In the embodiment a3 shown in FIG. 1, the gripper operating shaft 2 and the extension tube 4 are moved up and down relative to each other by operating a gripper operating shaft holding fitting 40 disposed inside the casing 21. .

That is, as shown enlarged in FIGS. 5(A) and (13), a second drive motor 42 is fixed between two guides 41 protruding from the inner wall of the casing 21, and a spiral protrusion is formed on the surface. Screws 43 with 2 slits are arranged so as to be rotatable in forward and reverse directions by a second drive motor 42. On the other hand, the gripper operating shaft holding fitting 40 has a blind hole 40a, and a spiral groove corresponding to the spiral protrusion of the screw 43 is carved on the inner surface of the blind hole, so that the screw 43 and the blind hole 40a are screwed together. In this state, the presser metal fitting 40 is fitted freely between the two guides 41. Furthermore, a protrusion 40b is formed on the end surface of the presser fitting 40 on the opposite side from the second drive motor 42.

FIG. 5(^) shows the state in which the presser metal fitting 40 is pulled into the guide 41, and the presser metal fitting 40 is in gripper operation @h2.
does not prevent vertical movement. Therefore, the clipper operating shaft 2 also moves up and down together with the extension tube 4, and the control rod 15 is inserted or handled into the reactor core while being gripped by the gripper mechanism 1.

When separating the control rod 15 from the gripper mechanism 1, the sixth
As shown in the figure, drive the second drive motor 42 to drive the screw 4.
By rotating 3, the gripper operating shaft holding bracket 40
is made to protrude from the guide 41, and the protrusion 40b is fitted into the recess 44 formed on the upper part of the gripper operation l1112.

This prevents the gripper operating shaft 2 from moving up and down, and if the drive motor 22 and gear 24 are driven in this state to raise the extension tube 4, the gripper operating shaft 2 and extension shaft 4 will be relatively misaligned. As a result, the gripper fingers 1a and gripper finger cam 1b of the gripper mechanism 1 are similarly shifted relative to each other, and the control rod is unchucked from the handling head 15a, causing the control rod 15 to be separated from the gripper mechanism 1. Become. In order to raise the gripper actuator 1112 and the extension tube 4 with the control rod 15 separated, the second drive motor 42 is rotated in the opposite direction and the gripper actuator shaft holding bracket is moved again as shown in FIG. 5(A). 40 and gripper operating shaft 2
After disengaging the extension tube 4, the drive motor 22 and gear 24 are not driven, and the extension tube 4 is moved upward.

<Effects of the Invention> As explained above, according to the present invention, instead of the ball screw/ball nut method used in the conventional CRD upper drive device, a method in which the extension tube is directly moved up and down is used, so that the entire upper drive device is While conventionally the height required 5 to 6 m, it is now possible to shorten the height to 2 m or less. As a result, earthquake resistance is improved, and the steady resting means installed at the upper end of the upper drive device as in the past becomes unnecessary.

Furthermore, since the WI construction has been simplified and the number of component parts has been reduced, there is also the advantage that the probability of occurrence of failure is reduced and maintainability is improved.

[Brief explanation of drawings]

Fig. 1 is an overall explanatory diagram showing an embodiment of the control rod drive mechanism of the present invention, Fig. 2 is an enlarged explanatory diagram of the inside of the upper drive device in Fig. 1, and Fig. 3 is along the line ■-■ in Fig. 2. Cross-sectional view, Figure 4 is an explanatory diagram showing a different operating state from Figure 2, Figure 5 (8)
5([3) is an enlarged explanation of a preferred embodiment of the means for lifting the control rod upward, and FIG. 5([3)] is the ■-
■A sectional view taken along the line; Figure 6 is an explanatory diagram showing a different operating state from Figure 5 (8); Figures 7, 8, and 9 show an example of a conventional control rod drive mechanism. It is an explanatory diagram. 1... Gripper mechanism, 2... Gripper operating shaft, 3...
...shielding plug, 4...extension pipe, 15...control rod,
20... Upper drive device, 22... Drive motor, 23
...Electromagnet, 24...Gear, 25...Tooth profile, 26
... Armature, 27 ... Link mechanism, 31 ...
・Clutch, 40...Gripper operating shaft holding fitting, 42
...Second drive motor. 8rA Figure 9

Claims (1)

[Scope of Claims] 1. An extension tube having a gripper mechanism at the lower end that detachably grips the control rod and extending vertically through the furnace shielding plug, and a gripper operating shaft housed within the extension tube; an upper drive device that moves the extension tube up and down along with or relative to the gripper operation shaft; the upper drive device includes a gear that meshes with a tooth profile formed on the outer surface of the upper part of the extension tube; The extension tube is directly moved up and down by the rotation of the gear, and an armature is disposed on the gear via a link mechanism, and the armature is attracted by an electromagnet and dropped, thereby causing the gear and tooth profile to be connected to each other. A control rod drive mechanism 2 for a nuclear reactor, characterized in that it engages and disengages, a clutch mechanism is provided between the drive motor and the gear, and the clutch mechanism is configured to engage and disengage at the same time as the tooth profile on the outer surface of the extension tube and the gear disengage. The control rod drive mechanism according to claim 1, wherein the mechanism is in a disconnected state and the drive motor shaft and gear shaft are offset from each other at the clutch mechanism portion. 3. The control rod drive mechanism according to claim 1, wherein the gear is a spur gear. 4. The control rod drive mechanism according to claim 1, wherein the gear is a threaded gear. 5. A gripper operating shaft that has a gripper mechanism at the lower end that detachably grips the control rod and extends vertically through the reactor shielding plug, an extension tube that accommodates the gripper operating shaft therein, and the extension tube. an upper drive device that moves the gripper up and down along with or relative to the gripper operating shaft; the upper drive device includes a gear that meshes with a tooth profile formed on the outer surface of the upper part of the extension tube; and a drive that rotates the gear. The extension tube is directly moved up and down by the rotation of the gear, and an armature is attached to the gear via a link mechanism, and the armature is attracted by an electromagnet, and the tooth profile is engaged and disengaged by falling. Furthermore, a gripper operating shaft holding fitting that can be freely extended and retracted by a second drive motor is disposed near the upper part of the gripper operating shaft that protrudes from the upper end of the extension tube, and the holding fitting is held at its protruding position. A control rod drive mechanism for a nuclear reactor, characterized in that the gripper operating shaft is engaged with the upper part of the gripper operating shaft to prevent vertical movement of the gripper operating shaft.