JPH0682593A - Control rod driving position detector - Google Patents

Abstract

PURPOSE:To make compaction of a nuclear reactor compact by realizing making a control rod driving position detector compact. CONSTITUTION:In the detector for detecting the driving position of a control rod 21 fixed to a movable part 23 guided through a control rod guide pipe 22, a reflector 26 immersed into reactor water A is fixed to the movable part 23 and an ultrasonic probe 27 for detecting the driving position of the control rod 21 is provided oppositely to the reflector 26 in the control rod guide pipe 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control rod drive position detecting device, and more particularly to a control rod drive position detecting device which can be made compact in a nuclear reactor.

[0002]

2. Description of the Related Art Generally, a nuclear reactor is provided with a drive position detecting device for detecting the drive position of a control rod. For example, in a light water reactor, an electromagnetic induction type displacement meter that detects the drive position of the control rod by changing the magnetic field is used.

[0003]

By the way, if the electromagnetic induction type displacement gauge is adopted, there is a problem that the detector becomes complicated and a large number of instrumentation parts are attached to the outside of the furnace, resulting in a large size of the equipment. Particularly, in recent nuclear reactors, downsizing of the reactor is being promoted, and in order to downsize the reactor, it is required to downsize the control rod drive position detecting device.

The present invention was devised to effectively solve the above problems.

The present invention achieves a compact detector system,
It is an object of the present invention to provide a control rod drive position detection device that can cope with a compact furnace.

[0006]

SUMMARY OF THE INVENTION The present invention is an apparatus for detecting the drive position of a control rod mounted on a movable part guided by a control rod guide tube, wherein the movable part is a reflector immersed in reactor water. A plate is attached, and an ultrasonic probe for detecting the drive position of the control rod is provided inside the control rod guide tube so as to face the reflection plate.

[0007]

As described above, since the drive position of the control rod is detected by the ultrasonic probe, the detector can be made compact and the reactor can be made compact.

[0008]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 3 shows an example of an integrated pressurized water reactor. A reactor vessel 2 is installed in a containment vessel 1 in which water W is immersed, and a turbine 3 is installed above the reactor vessel 2. ,
The generator 4 etc. are installed. A pump 6 for circulating the reactor water A is provided below the reactor core 5 in the reactor vessel 2, and a steam generator 7 for exchanging heat of the reactor water A and the like are also provided. Therefore, the reactor water A circulated by the pump 6 passes through the furnace core 5, undergoes heat exchange when passing through the steam generator 7, and then returns to the pump 6 again. After exchanging heat with the reactor water A in the steam generator 7, the steam is transferred to the turbine 3 through the steam pipe 8 to drive the generator 4. 9
Is a condenser, 11 is an exhaust duct, and 12 is a water supply pump.

A control rod drive device 1 is provided above the core 5.
3, a control rod 21 driven by the control rod driving device 13 to adjust the output of the core 5 is provided with a movable portion 3 which is guided in the axial direction along a control rod guide tube 22. It is attached to 23. The movable portion 23 has a control rod drive shaft 24 and a control rod cluster 25 having one end coupled to the drive shaft 24 and the other end holding the control rod 21.

In particular, in order to detect the drive position of the control rod 11, the control rod cluster 25 in the control rod guide tube 22 is provided with a reflector (SUS) 26 immersed in the reactor water A. 26 is provided on the upper part of the control rod cluster 25 so as to expand radially outward. Also, this reflector 2
6 in the control rod guide tube 22 so as to face 6
An ultrasonic probe 27 is provided for detecting the drive position of the. That is, the control rod guide tube 22 is formed with a reduced diameter portion 28 that is reduced in diameter in the radial direction in order to guide the movement of the control rod cluster 25, and the reduced diameter portion 28 has the reduced diameter portion 28.
And a pair of ultrasonic probes 27, 27 at opposite positions.
Is attached.

The ultrasonic probe 27 having the above-described structure transmits the ultrasonic wave 28 toward the reflecting plate 26 as shown in FIGS. 1 and 2, and the echo 2 reflected from the reflecting plate 26.
9, the distance from the ultrasonic probe 27 to the reflection plate 26 is measured by the propagation time of the ultrasonic waves 28 and 29, and the drive position of the control rod 21 is detected from the measured value.

Specifically, the ultrasonic probe 27 is made of an inorganic material in order to secure pressure resistance, heat resistance and radiation resistance.
For example, the constituent members of the ultrasonic probe 27 are all made of metal and ceramics. That is, as shown in FIG. 2, the ultrasonic probe 27 has a case 31 made of Inconel, and a pressure release hole 32 for introducing the reactor water A into the case 31 to release the pressure is formed in the case 31. ing. Further, a vibrator (LiNbO ₃ ) is attached to the brazing material layers 34 and 35 to which the seal cable 33 is connected to the upper wall of the case 31.
36 are in between. The brazing material layers 34 and 35 including these vibrators 36 are covered with a filler 37 made of ceramics for insulation.

As described above, in the present invention, since the ultrasonic probe 27 detects the drive position of the control rod 21, the drive position is substantially determined by the reflection plate 26, the ultrasonic probe 27 and the cable 33. A detector can be configured. Therefore, the detection device is compact, and it is possible to respond to the downsizing of the nuclear reactor. Further, since the ultrasonic probe 27 is made of an inorganic material, it is possible to detect the position in a high temperature, high pressure and high radiation atmosphere. Further, since the ultrasonic waves 28 and 29 have a high transmittance in water, it is possible to detect a minute driving position even in an underwater environment, and the reliability of detection accuracy can be improved.

[0015]

In summary, according to the present invention, since the drive position of the control rod is detected by using the ultrasonic probe, the drive position detecting device can be made compact and the reactor can be made compact.

[Brief description of drawings]

FIG. 1 is a sectional view showing a control rod drive position detection device of the present invention.

FIG. 2 is a cross-sectional view showing an ultrasonic probe.

FIG. 3 is a sectional view showing an example of an integrated pressurized water reactor.

[Explanation of symbols]

 21 control rod 22 control rod guide tube 23 movable part 26 reflector 27 ultrasonic probe 28, 29 ultrasonic A reactor water

Claims (1)

[Claims] 1. A device for detecting a drive position of a control rod attached to a movable part guided by a control rod guide tube, wherein a reflecting plate immersed in reactor water is attached to the movable part, A control rod drive position detecting device, characterized in that an ultrasonic probe for detecting the drive position of the control rod is provided inside the control rod guide tube so as to face the plate.