JP2871024B2 - Function confirmation device for brake for control rod drive device and its confirmation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an apparatus and a method for checking the function of an electromagnetic brake for a control rod drive in a boiling water reactor.

(Prior Art) In a boiling water reactor, a control rod driving device is provided at a lower portion of a reactor pressure vessel, and the power of the reactor is controlled by inserting and removing a control rod into and from a reactor core.

FIG. 3 is a longitudinal sectional view schematically showing a boiling water reactor, in which a housing 4 of a control rod driving device 3 is mounted through a bottom of a reactor pressure vessel 2 containing a reactor core 1. Above the housing 4, a control rod guide tube 5 and a control rod 6 are mounted. An electric motor 7 is connected to the control rod driving device 3.

In the drawings, a is a steam separator, b is a steam dryer, c is a main steam outlet nozzle, d is a feed water inlet nozzle, and e is an internal pump.

FIG. 4 is a longitudinal sectional view showing the control rod driving device 3 shown in FIG. 3 in detail. In FIG. 4, a shaft 8 is connected to an output shaft of a motor 7 installed below the housing 4, and a first connecting member 9 is attached to the upper portion of the shaft 8 via a key 10. The second connecting member 11 is attached to the first connecting member 9 by key spline connection. A long screw shaft 12 is connected to an upper portion of the second connection member 11, and a bearing 13 is attached to an upper end of the screw shaft 12. Screw shaft
A nut 14 is engaged with 12. The lower end of a hollow piston 15 is in contact with the upper surface of the nut 14. Nut 14
The piston 15 is provided with four rollers 16 equally arranged in the circumferential direction, and the rollers 16 are in contact with the inner peripheral surface of the tube 17.

The inner peripheral surface of the tube 17 is brought into contact with two adjacent ones of the four rollers 16 on both sides to form a crescent-shaped section (not shown) having a length corresponding to the moving stroke of the nut 14 and the piston 15. Is installed.

When the power of the nuclear reactor is adjusted by the control rod driving device 3 having the above configuration, when the shaft 8 is rotated by the rotation of the electric motor 7, the nut 14 and the piston 15 are connected to a plate (not shown) on the inner peripheral surface of the tube 17. ) Prevents rotation, so that only axial movement is allowed, and the control rod 6 connected to the piston 15 moves up and down.

In order to raise the control rod rapidly to shut down the reactor urgently, a large amount of high-pressure water is supplied through the pipe 18 from the externally provided accumulator (not shown) pressurized with nitrogen through the control rod driving device 3. Introduce to. As a result, the piston 15 receives the pressure and separates from the nut 14, and the control rod 6 is rapidly raised into the core 1. Note that a seal portion 19 composed of a labyrinth for sealing high-pressure water is provided inside the control rod driving device 3.

The motor 7 is provided with an electromagnetic brake 20, whereby the position of the control rod 6 is fixed. Electromagnetic brake 20
Is a model in which the brake is operated when the power is not supplied. To change the position of the control rod 6, first use the electromagnetic brake 20
And the brake function is released, and then the motor 7 is energized and rotated.

Assuming that the pipe 18 is broken, a downward force generated by the differential pressure between the reactor pressure and the atmospheric pressure acts on the piston 15, and this force is applied to the nut 14 via the piston 15 to rotate the screw shaft 12. However, the electromagnetic brake 20 has a sufficient holding torque to prevent the rotation and keep the position of the control rod 6 fixed.

(Problem to be Solved by the Invention) In the control rod driving device 3 configured as described above, the electromagnetic brake 20 has a holding torque that exceeds the rotation torque generated on the screw shaft 12 when the pipe 18 is broken. Confirmation is important for reactor safety. However, it is difficult to check the holding torque while the electromagnetic brake 20 is mounted on the control rod driving device 3. Inevitably, at the time of periodic inspection of the nuclear reactor, the electromagnetic brake 20 is removed from each control rod driving device 3 and checked with a torque measuring device or the like, but this requires a great deal of time and effort,
There is an undesired problem because the radiation exposure due to this operation increases.

The present invention has been made to solve the above problems,
It is an object of the present invention to provide a brake function checking device for a control rod drive device and a checking method thereof, which can easily check a brake function without removing an electromagnetic brake.

[Configuration of the invention]

(Means for Solving the Problems) The present invention provides a housing provided through the bottom of a reactor pressure vessel, a control rod drive device driven by an electric motor mounted in the housing, and a control rod An electromagnetic brake that is provided in the drive device to prevent rotation of the control rod drive screw shaft and that releases the brake function when the control rod is driven; a motor drive control device that is connected to the motor and controls the motor during normal drive; An output torque limiter for limiting the output torque of the motor is provided, and the control device for driving the motor and the motor are provided with a switching device so as to be connectable via the output torque limiter.

Also, a housing provided through the bottom of the reactor pressure vessel, a control rod drive device driven by an electric motor mounted in the housing, and a control rod drive screw shaft that prevents rotation of the control rod drive screw shaft. An electromagnetic brake which is provided for the purpose of driving the control rod and releases the brake function when the control rod is driven; a motor drive control device connected to the motor for controlling the motor during normal driving; and an output torque limiter for limiting the output torque of the motor. In the brake function confirmation test of the electromagnetic brake, the control device for driving the electric motor and the electric motor are connected via the output torque limiter in a state where the brake function of the electromagnetic brake to be used for the test is exhibited. The output torque of the motor is set to a predetermined holding torque for preventing rotation, the motor is energized, and the motor is turned on. Characterized in that to check for confirming the function for preventing rotation of said electromagnetic brake.

(Operation) The output torque of the motor has a correlation with the current flowing through the motor, and the output torque increases as the current increases.
Therefore, a current limiter is used to limit the output torque. When a stepping motor is used as the electric motor, a low voltage pressure supply device in which the supply voltage is lower than usual is used. One of the outputs of the motor drive control device is directly connected to the motor, and the other is connected to the motor via the current limiter. At the time of the brake function test, it should be switched by a switch so as to be connected to the electric motor via a current limiter or a low voltage device. If the motor does not rotate, it can be seen that the brake function has a torque equal to or greater than the control rod drop torque. In addition, it can be seen that when the motor rotates, the brake function is deteriorated.

Therefore, according to the present invention, the brake function can be checked while the electromagnetic brake is attached to the control rod drive, and the reliability and safety of the control rod drive can be ensured.

(Embodiment) An embodiment of a device for checking the function of a control rod drive device brake and a method for checking the same according to the present invention will be described with reference to FIGS. 1 and 2. FIG.

The present invention resides in an apparatus and a method for checking the function of an electromagnetic brake of a control rod driving apparatus. Therefore, the control rod driving apparatus is the same as that shown in FIG. The same reference numerals are given to the same parts as those described above, and the description thereof is omitted.

The block in FIG. 1 shows a circuit for driving the electric motor. That is, one of the outputs of the motor drive control device 100 is directly connected to the motor 7, and the other is connected to the motor 7 via a current limiter 101 provided as an output torque limiter, and is operated by a switch (not shown). Be able to switch connections. During normal operation, the output of the motor drive control device 100 is directly connected to the motor 7.

During a function check test of the electromagnetic brake 20, a switch (not shown) is switched, and the output of the motor drive control device 100 is connected so as to be connected to the current limiter 101. At this time, a circuit is set up so as to prevent energization of the electromagnetic brake 20 for releasing the brake function. As a result, the electric motor 7 tries to rotate in a state where the brake function is not released and the output torque is limited to a certain value. Current limiter 101
The current limit value is set to be larger than the torque value acting on the screw shaft 12 when the pipe 18 is broken as the output torque of the electric motor 7 and smaller than the rated holding torque of the electromagnetic brake 20. In this way, the electric motor 7 is started, and if the electric motor 7 does not rotate at that time, the holding torque of the electromagnetic brake 20 may have a holding torque greater than the torque acting on the screw shaft 12 when the pipe is broken. Recognize. When the electric motor 7 rotates, it means that the holding torque of the electromagnetic brake 20 is lower than the rated value, and appropriate processing can be performed.

FIG. 2 is a circuit diagram when a stepping motor is used as the electric motor. Motor drive controller 10
One of the outputs 2 is directly connected to the motor 7, and the other is a low-voltage supply device such as a transformer provided as an output torque limiter.
Connect to motor 7 via 103, switch (not shown)
To switch the connection. During normal operation, the output of the motor drive control device 102 is directly connected to the motor 7.

At the time of the function check test of the electromagnetic brake 20, the output of the motor drive control device 102 is connected to the low voltage supply device 103 by a switch (not shown). At this time, a circuit is constructed so that the current for brake release is blocked. The stepping motor is a synchronous motor, and when the supply voltage decreases, the load torque that can be drawn into the synchronous rotation also decreases. If the load torque is large, synchronization cannot be pulled in (step-out phenomenon), and the stepping motor does not rotate. By setting the supply voltage set value of the low-voltage supply device 103 in the same manner as when the current limiter 101 is used, the brake function can be confirmed in the same manner as described above.

〔The invention's effect〕

According to the present invention, since the brake function can be arbitrarily checked without removing the electromagnetic brake, the reliability and safety of the control rod driving device can be ensured.

[Brief description of the drawings]

FIG. 1 is a drive circuit diagram of an electric motor for explaining an embodiment of a device for checking the function of a brake for a control rod drive device and a method for checking the function according to the present invention, and FIG. FIG. 3 is a longitudinal sectional view for explaining a schematic configuration of a boiling water reactor, and FIG. 4 is a longitudinal sectional view for explaining a configuration of a control rod driving device. DESCRIPTION OF SYMBOLS 1 ... Reactor core 2 ... Reactor pressure vessel 3 ... Control rod drive device 4 ... Housing 5 ... Control rod guide tube 6 ... Control rod 7 ... Electric motor 8 ... Axis 9 and 11 ... Connection member, 10 ... Key 12 ... Screw shaft, 13 ... Bearing 14 ... Nut, 15 ... Piston 16 ... Roller, 17 ... Tube 18 ... Piping, 19 ... Seal 20 ... Electromagnetic Brake 100,102 …… Control device for motor drive 101 …… Current limiter, 103 …… Low voltage supply device

Claims (2)

(57) [Claims] 1. A housing provided through the bottom of a reactor pressure vessel, a control rod drive driven by an electric motor mounted in the housing, and a control rod drive screw shaft attached to the control rod drive. An electromagnetic brake that is provided to prevent rotation of the motor and that releases the brake function when the control rod is driven; a motor drive control device that is connected to the motor and controls the motor during normal driving; and an output that limits the output torque of the motor. A brake function confirming device for a control rod drive device, comprising: a torque limiter; and a switching device so that the motor drive control device and the motor can be connected to each other via the output torque limiter. 2. A housing provided through the bottom of the reactor pressure vessel, a control rod drive driven by an electric motor mounted in the housing, and a control rod drive screw shaft attached to the control rod drive. An electromagnetic brake that is provided to prevent rotation of the motor and that releases the brake function when the control rod is driven; a motor drive control device that is connected to the motor and controls the motor during normal driving; and an output that limits the output torque of the motor. A torque limiter, and at the time of the brake function confirmation test of the electromagnetic brake, the motor drive control device and the electric motor are connected to the output torque limiter in a state where the brake function of the electromagnetic brake to be used for the test is exhibited. The output torque of the motor is set to a predetermined holding torque for preventing rotation, the motor is energized, and the Control rod drive brake function confirmation method characterized by check the presence or absence of rotation to check the function of prevent rotation of said electromagnetic brake.