JPS62217188A - Drive mechanism of control rod for nuclear reactor - 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] <Industrial Application Field> The present invention relates to a control rod drive mechanism for inserting or pulling control rods into a nuclear reactor, and more specifically, to a control rod drive mechanism for inserting or pulling control rods into a nuclear reactor. This invention relates to a control rod drive mechanism that can be shorter in height than conventional ones.

<Prior Art> A control rod drive mechanism (hereinafter abbreviated as rCRDJ) is a device for controlling reactor output by inserting or withdrawing control rods into the reactor core during reactor operation. ]I1
Figure 5 shows an example of the structure and its operation.

This will be explained with reference to FIGS. 6 and 7.

Figure 5 shows the control rod 15 suspended at almost the lower limit position (inside the reactor core), with the gripper @ structure 1 at the lower end, an extension tube 4 extending to the right, and a gripper operating shaft housed within this extension tube. 2
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 the gripper operating shaft is moved up and down relative to the extension tube 4.

The upper drive device 5 has the following structure. A drive motor 7 is installed above the inside of the casing 6, and is capable of rotating a ball screw 9 via a gear 8. A pole nut 10 is screwed onto the ball screw, and an electromagnet 12 is suspended from the ball nut 1 through a rod 11.
An armature 13 is attracted to and detachably engaged with the lower part of the electromagnet, and a link device 1fIS 14 is provided at the lower part of the armature. FIG. 5 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 v1 1 consists of 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. chucking and engaging the handling head 15a on the upper part of the control rod 15 from the inside,
Control rod 15 can be gripped.

In order to move the control rod 15 up and down while gripping it with the gripper machine @1, as shown in FIG.
Through the electromagnet 12, armadure 13, link mechanism 1
4 may be moved up and down integrally, and the extension tube 4 may be moved up and down together with the gripper operating shaft 2.

When scramming the reactor, that is, when rapidly inserting the control rods 15 deep into the reactor core (not shown) to make an emergency shutdown of the reactor, the electromagnets 12 are demagnetized as shown in FIG. As a result, the armature 13 is dropped and the link mechanism 14 is opened. As a result, the holding by the flange 4a is released, and
The extension tube 4, together with the gripper operating shaft 2, will suddenly fall while still gripping the control rod 15.

In order to release the chucking between the handling head 15a of the control rod 15 and the gripper mechanism 1, only the gripper operating shaft 2 can be pulled up relative to the extension tube 4, and thereby the gripper at the lower end of the gripper operating shaft 2 Only the finger cam 1b is pulled up, the outward expansion of the gripper fingers 1a is released and the gripper fingers 1a are retracted inward, and the gripper mechanism 1 and control rod 1 are removed.
5 can be disengaged.

<Problems to be Solved by the Invention> However, the above-mentioned CRD upper drive device 5
In this case, the height at which the ball neck 1-4 moves up and down must be 1 m or more (because the drive range of the control rod is about 1 m), the vertical movement range of the extension tube 4 must be at least 1 m, and the electromagnet 1
If you add the lengths of parts such as 2 and armature 13, the total height reaches 5 to 6 III, which poses a problem in earthquake resistance, and it was necessary to provide a means to prevent photographing (not shown). In addition, the structure is complex and there are many parts, which increases the probability of failure and is disadvantageous in terms of maintenance.

Therefore, this invention aims to shorten the height of the CRD upper drive device to improve earthquake resistance, reduce the number of component parts, reduce the probability of failure, and improve maintainability.
This was done for the purpose of

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 includes an annular rotating body rotated in a predetermined horizontal plane by a drive motor, an annular member made of a ferromagnetic material that is magnetized and demagnetized by an electromagnet, and an annular member that is attracted to the annular member by magnetization and demagnetization of the annular member. .

and a detachable annular armature. These annular rotating body, annular member, and annular armature are stacked in this order from top to bottom along a common vertical axis to form an annular stack, and the upper part of the extension tube is fitted into the central through hole so as to be vertically movable. .

This stack can rotate integrally when the annular member attracts the armature. In addition, a plurality of balls are fitted into thread-shaped gaps with a substantially circular cross section created by thread-shaped grooves formed on the outer surface of the upper part of the extension tube and thread-shaped grooves formed on the inner circumferential surface of the armature. The extension tube is supported via the ball, and the rotation of the stack is transmitted to the extension tube via the ball. Furthermore, a screw-shaped pocket is formed above the grooves on the inner circumferential surface of the armature, continuous with the grooves, and deeper in the horizontal direction than the four grooves. In this case, the armature is one part from the annular member.
1B2 and falls, the ball rolls from the groove into the pocket, and the extension tube is no longer supported by the stack.

With this configuration, when the control rods are inserted or handled into the reactor core during normal operation of the reactor, the annular armature is attracted to the annular member that is magnetized by exciting the electromagnet of the upper drive unit. By rotating the annular rotating body with the drive motor in the state, the stack supports the extension tube via the ball fitted into the threaded gap between the extension tube and the armature, and the rotation of the stack causes the extension tube to rotate. It is possible to directly move the extension tube up and down. Therefore, the control rod gripped by the gripper operating shaft and the gripper mechanism at the lower end of the extension tube can be moved up and down.

In addition, when scramming a nuclear reactor, by demagnetizing the electromagnetic stone in the upper drive unit to demagnetize the annular member, and then detaching and dropping the annular armature, the ball can be prevented from threading on the outer surface of the extension tube. It comes off and is expelled into a pocket on the inner peripheral surface of the armadure, and as a result, the extension tube is no longer supported by the ball, and the it,+ control rod falls into the core while being gripped by the gripper mechanism.

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

FIG. 1 illustrates the entire CRD of the present invention, in which a gripper operating wheel 2 is housed inside an extension tube 4 that extends vertically through a furnace shielding plug 3, and a gripper operating wheel 2 is provided at the lower end of the extension tube 4. Gripper machine ((41) grips the control rod 15 and moves the extension tube up and down to insert the control rod,
The basic function of performing the pulling motion is the same as that of the conventional CRD - that of this invention! 18@ is in the configuration of the upper drive device 20 installed above the 71XM plug 3. That is, the second
As can be seen from the enlarged views in FIGS. 4 to 4, a drive motor 24 is placed on a support plate 23 protruding from a predetermined location on the inner wall of the casing 21 of the upper drive device 20, and extends circularly through the support plate 23. A gear 25 disposed at the lower end of the motor rotating shaft meshes with a tooth profile 26a formed on the outer periphery of the annular rotating body 26. The annular rotating body 26 is supported by a bearing 27 at a 7-run 9 portion 26b, and can be rotated in a predetermined horizontal plane by a drive motor 24. A first annular member 28, a second annular member 29, and an annular armature 30 made of a ferromagnetic metal material are arranged below the annular rotating body 26.
The first annular member 28 is fixed to the lower surface of the annular rotating body 26, and the second annular member 29 is fixed to the upper surface of the annular armature 30. An electromagnet 31 attached to the inner wall of the casing 2 is disposed outside the annular portion +J28.29 in the circumferential direction, and when the electromagnet 31 is excited, the annular member 28.29
When the electromagnet 31 is demagnetized, the annular members 28 and 29 are also demagnetized and separate from each other (Fig. 4).

The annular rotating body 26, the annular members 28, 29, and the annular armadure 30 are stacked in this order from top to bottom along a common vertical axis to form an annular stack 32 that rotates integrally with the annular rotating body. The upper part of the extension tube 4 is fitted into the central through hole so as to be movable up and down (Fig. 2). An annular armature 30 surrounding the extension tube 4 is carved in a threaded manner d3 on the outer surface of the upper part of the extension tube.
A threaded groove 30a corresponding to the threaded groove 33 is provided on the inner circumferential surface of the threaded groove 33.
is engraved, so the extension tube 4 and armature 30 are
A screw-shaped gap having a substantially circular cross section is formed between the two.

A plurality of balls 34 having a diameter substantially equal to the cross-sectional diameter of the threaded gap are fitted into the threaded gap. In the illustrated example, the threaded groove 30a is formed by one pitch of the threaded groove 33, and eight balls 34 of about 1 m are fitted in the threaded gap corresponding to one pitch. (3rd
figure). Thus, the extension tube 4 connects the stack 3 via the ball 34.
2, and the rotation of the stacked car body 32 is transmitted to the extension tube 4 via the balls. The inner peripheral surface of the armature 30 is further provided with grooves 1 to 30 along the threaded groove 30a.
b is formed. These blurs 1 to 30b are grooves 30
It is continuous with a and is deeper in the horizontal direction than the groove.

In the figure, reference numeral 35 indicates a guide rod, which extends downward from the first annular member 28 and passes through the second annular member 29 to reach the armature 30. Also, armature 30
An armature receiving plate 36 annularly protruding from the inner wall of the casing 21 is disposed below the armature at a distance from the armature, and a cylindrical ball holding plate 37 extends upward from the periphery of the central through hole of the armature receiving plate 36. It extends to the vicinity of the ball through the gap between the extension tube 4 and the armature 30.

The operation of the upper drive device having such a structure will be explained.

When moving the control rod 15 up and down while gripping the l+ control rod 15 with the gripper mechanism 1 as shown in FIG. 1, the electromagnet 31 is energized as shown in FIG.
428 and the second annular member 29, and by bringing them into close contact, the armature 30 is pulled up. At this time, the ball 34 fits into the thread-shaped gap formed by the groove 33 of the extension tube and the groove 30a on the inner peripheral surface of the armature,
Supports extension tube. If the drive motor 24 is rotated in this state, the stacked vehicle body 32 will rotate integrally via the gear 25. f? Since the single body 32 rotates on a predetermined horizontal plane and the vertical movement of the stacked vehicle body is prevented, this rotational movement is ultimately transmitted to the extension tube 4 via the ball 34, causing the extension tube 4 to move directly up and down. It will move like this.

In the scram Ih, as shown in FIG. The ball 34 is caught by the plate 36. As a result, the ball 34 rolls out of the groove 33 of the extension tube 4, fits into the pockets I to 30b of the armature 30, and is retracted.
The extension tube 4 is no longer supported by the armature 30, and the free extension tube 4 and gripper work shaft 2 fall while gripping the control rod 15. At this time, the guide rod 35 moves to guide the armature 30 that falls under its own weight, and the ball holding plate 37 moves to prevent the ball 34, which was once housed in the hole 1-30b, from rolling out again into the extension tube 30. It functions to prevent the extension tube 4 from being obstructed from falling.

After the scram, in order to return to the normal vertical motion state (FIG. 2), the armature 30 can be pulled up by energizing the electromagnet 31 again to magnetize the annular members 28, 29. As a result, the ball 34 is pulled upward from the pole retainer 37, rolls under its own weight, and fits within the extension tube 4, returning to the engagement state between the armature 30 and the extension tube 4.

<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 is used in which the extension lever is directly moved up and down. Whereas conventionally the height was required to be 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 structure is simplified and the number of component parts is reduced, there are also advantages in that the probability of occurrence of failure is reduced and maintainability is improved.

4. fy of the drawing! Literary Explanation Fig. 1 is an overall explanatory view showing an embodiment of the control rod drive mechanism of the present invention, Fig. 2 is an enlarged explanatory view of the inside of the upper drive device in Fig. 1, and Fig. 3 is an explanatory view of the inside of the upper drive device in Fig. 2. 4 is an explanatory diagram showing an operating state different from that in FIG. 2, and FIGS.
7 and 7 are explanatory diagrams without showing an example of a conventional control rod drive machine (14).

]... Gripper mechanism, 2... Gripper operating axis, 3...
...shielding plug, 4...extension pipe, 15...control rod,
20... Upper drive device, 24... Drive motor, 26
... Annular rotating body, 28.29... Annular part shrine, 30.
...Annular armature, 30a...concave line, 30b...
・Pocket, 31...Electromagnet, 32...Stack, 3
3... Threaded groove, 34... Ball.

Claims (1)

[Claims] 1. An extension tube that has a gripper mechanism at the lower end that detachably grips the control rod and extends vertically through the reactor shielding plug, a gripper operation shaft housed in the extension tube, and a gripper operation shaft that allows the extension tube to operate the gripper. It consists of an upper drive device that moves up and down along with the shaft or relative to the gripper operating shaft, and the upper drive device includes an annular rotating body that is rotated in a predetermined horizontal plane by a drive motor, and is magnetized and demagnetized by an electromagnet. A center penetration of an annular stack in which an annular member made of a ferromagnetic material and an annular armature that attracts and detaches from the annular member by magnetizing and demagnetizing the annular member are stacked in this order from top to bottom along a common vertical axis. The upper part of the extension pipe is inserted into the hole so as to be movable up and down, and when the annular member is adsorbing the armature, the stack can rotate integrally, and a screw is formed on the outer surface of the upper part of the extension pipe. By fitting a plurality of balls into a thread-shaped gap having a substantially circular cross section created by a thread-shaped groove and a thread-shaped groove formed on the inner circumferential surface of the armature, the stack supports the extension pipe through the balls. The rotation of the stack is transmitted to the extension tube via the ball, and a threaded pocket is formed above the groove on the inner peripheral surface of the armature, continuous with the groove and deeper in the horizontal direction than the groove. By doing so, when the armature separates from the annular member and falls, the ball rolls from the groove into the pocket and the extension tube is no longer supported by the stack. Reactor control rod drive mechanism.