JPH02181693A - Control rod driving mechanism - Google Patents

Abstract

PURPOSE:To latch a control rod speedily even when the control rod is unlatched by arranging a magnet in a collet piston and arranging an electromagnetic switch for collet piston position detection in an outer tube. CONSTITUTION:If pressure is applied to the upper side of the collet piston 20 and a collet finger 30 comes out although no control rod operation is performed, the collet finger 30 separates from the magnet 21 incorporated in the collet piston 20 and the electromagnetic switch 23 incorporated in the outer tube 22 and a control rod operation decision circuit 26 in a nuclear reactor manual operation board 25 decides whether that is caused by control rod operation through the electromagnetic switch 23. Then when no control rod operation is performed, an opening command is sent to a drawing line discharge valve 28 in a control rod hydraulic pressure control unit 27. Thus the valve is opened and the pressure on the lower side of the collet piston 20 drops, so the collet piston 20 is pushed up with the force of a coil spring 8, so that the collet finger 30 is latched again.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a control rod drive mechanism for driving control rods used for power control of a boiling water nuclear reactor.

(Prior Art) Hereinafter, a conventional example of a control rod drive mechanism will be described with reference to FIG.

In FIG. 3, reference numeral 1 denotes a bottomed cylinder of a control rod drive mechanism 19 provided at the lower part of a pressure vessel 2 in a nuclear reactor, and the lower part of this cylinder 1 has a pressure fluid supply port. 3
and a discharge port 4 are provided, and a guide cap 5 is attached to the upper part of the cylindrical body 1. Further, an outer tube 18 is disposed within the cylinder 1, and an inner tube (hereinafter referred to as an inner tube) is disposed within the outer tube 18.
6 is placed. A collet piston 7 having a collet finger 7a is slidably fitted into the upper part of the inner cylinder 6, and an extensible coil spring 8 is interposed between the collet piston 7 and the guide cap 5. has been done. This coil spring 8 is configured to push down the collet piston 7, and is regulated by a stopper 6a of the inner cylinder 6. The collet finger 7a is adapted to engage with a latch 14 of an index tube 15, which will be described later, and the collet finger 7a is released from the latch 14 by coming into contact with the guide cap 5 against the elasticity of the coil spring 8. It is designed to come off.

On the other hand, a guide tube 9 is installed in the middle of the cylinder 1, and the upper part of the guide tube 9 is provided with each pressure fluid outlet hole 1O. A tube body (also referred to as a PIF probe) in which a plurality of reed switches 11 are built in the guide tube 9 1
2 is fitted with a flow path 13, and the pressure fluid from the discharge port 4 flows through the flow path 13 of the pipe body 12 and the outflow hole lO.
It flows out to the outside of the tube body 12 through the tube body 12. An index tube 15 having a plurality of latches 14 is watertightly fitted on the outside of the guide tube 9 via an O-ring, and a coupling spud 18a of the control rod IB can be connected to the upper part of the index tube 15. It looks like this. Moreover, the index tube 15
A magnet 17 is built into the lower part of the index tube 15, and when the index tube 15 goes up and down, the magnet 17 turns each reed switch 11 onlofTL, thereby providing an indicator light that allows the raised position of the index tube 15 to be provided externally. can be detected by.

Therefore, when pressure fluid is supplied into the cylinder 1 from the supply port 3, the index tube 15 rises together with the control rod 1B. At this time, since an extensible coil spring 8 is interposed between the collet finger 7a and the guide cap 5, the collet piston 7 is pushed downward. Then, as the index tube 15 rises, the collet finger 7a separates from the latch 14. Next, when the supply of pressure fluid from the supply port 3 is stopped and pressure fluid is supplied into the cylinder body 1 from the other discharge port 4, water pressure is applied to the lower part of the collet piston 7, so that the collet piston 7 The collet fingers 7a are lifted up, and the collet fingers 7a are pushed outward by the guide cap 5 and separated from the latch 14. At the same time, this pressure fluid passes through the flow path 13 and the outlet hole 10 of the tube 12 to the tube 1.
2 and lowers the control rod 16 together with the index tube 15.

As a result, the collet finger 7a is separated from the guide cap 5 by the stored elasticity of the coil spring 8 of the pressurized fluid from the discharge port 4, and the collet finger 7a engages with the latch 14, and the lowering of the control rod 16 together with the index tube 15 is also stopped. Further, this engagement position can be detected from the outside by the cooperative action of the magnet 17 and the reed switch 11.

(R Notification to be Solved by the Invention) In the above-described configuration, the control rod drive mechanism and the control rod hydraulic control unit that supplies drive water to the control rod drive mechanism are subject to periodic inspections, etc. Safety measures are taken during work by closing the valve. In this case, due to a mistake in the recovery procedure or forgetting to perform the recovery operation, pressure is applied to the lower side of the collet piston, causing the collet finger to come off and the control rod to be in the asilatch state.
There was a risk that the control rod would be pulled out even though the control rod was not operated.

The present invention has been made in view of the above circumstances, and its purpose is to detect when the collet finger comes off and becomes unlatched at a time other than when inserting or withdrawing the ins rod, and to make it possible to latch it again. The object of the present invention is to obtain a control rod drive mechanism that can do the following.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, in the present invention, an index tube that can be raised and lowered by hydraulic pressure is fitted in an outer tube constituting the outer circumferential side, and the latch of this index tube is A control rod drive mechanism comprising a collet piston having a collet finger disposed in the outer tube so as to be able to be fitted and removed by a spring,
A control rod drive mechanism is provided, characterized in that a magnet is disposed on the collet piston, and an electromagnetic switch for detecting the position of the collet piston is disposed on the outer tube.

(Function) In the control rod drive mechanism configured in this way, if pressure is applied to the lower side of the collet piston and the collet finger comes off even though the control rod is not operated, the outer An electromagnetic switch built into the tube is activated to detect this condition. Therefore, the withdrawal line drain valve in the control rod hydraulic control unit opens.
The pressure under the collet piston can be lowered.

As a result, the collet piston is a coil spring (Embodiment) Next, an embodiment of the control rod drive mechanism according to the present invention will be described below with reference to FIGS. 1 and 2.

1 and 2, when the distance between the magnet 21 built in the collet piston 20 and the electromagnetic switch 23 built in the outer tube 22 increases, the electromagnetic switch 2
8 works.

The signal 24 of this electromagnetic switch is transmitted to the reactor manual operation panel 25.
The control rod operation determination circuit 26 in the control rod operation determination circuit 26 determines whether or not a control rod operation is being performed. When the control rods are not operated, the withdrawal line drain valve 28 connected to the withdrawal line 27 in the control rod hydraulic control unit 27 can be opened.

FIG. 2 is an enlarged view of the control rod drive mechanism 19 to which an electromagnetic switch and a magnet are attached.

When pressure is applied to the lower side of the collet piston 20, it overcomes the force of the coil spring 8, the collet piston 2° moves upward, and the collet fingers 30 are pushed apart and brought into an unlatched state. When this state is reached, the magnet 21 built into the collet piston 20 separates from the electromagnetic switch 23 built into the outer tube 22, and this electromagnetic switch 23 operates.

In the above configuration, if pressure is applied to the lower side of the collet piston 2o and the collet finger 30 comes off even though the control rod is not operated, the magnet 21 built in the collet piston 2a and the outer tube It is determined whether this is caused by the electromagnetic switch 23 built into 22.

If the control rod is not operated, an opening command is issued to the withdrawal line drain valve 28 in the control rod hydraulic control unit 27.

When the drawing line drain valve 28 is opened, the pressure below the collet piston 20 decreases, so the collet piston 20 is pushed down by the force of the coil spring 8, and the collet finger 30 is latched again.

〔Effect of the invention〕

As mentioned above, by installing an electromagnetic switch on the outer tube in the control rod drive mechanism and a magnet on the collet piston, the position of the collet piston can be detected, so even if the control rod becomes unlatched, it can be quickly reactivated. Can be latched.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing the overall configuration including a control rod drive mechanism according to an embodiment of the present invention, FIG. 2 is an enlarged vertical sectional view showing the main parts of the present invention, and FIG. 3 is a control rod drive mechanism. FIG. 2 is a longitudinal sectional view showing a conventional example of a rod drive mechanism. 8... Coil spring 15... Index tube 19... Control rod drive mechanism 20... Collet piston 21... Magnet 22... Outer tube 23... Electromagnetic switch 30... Collet finger substitute Person Patent Attorney Nori Ken Chika Yudo Ken Daishimaru Figure Figure

Claims (1)

[Claims] An index tube that can be raised and lowered by hydraulic pressure is fitted into the outer tube that forms the outer circumferential side, and a collet piston having a collet finger is disposed within the outer tube so that it can be fitted into and removed from the latch of this index tube by the use of water pressure and a spring. 1. A control rod drive mechanism comprising: a magnet disposed on the collet piston; and an electromagnetic switch for detecting the position of the collet piston disposed on the outer tube.