JPH03225202A - Position specifying device - Google Patents

Abstract

PURPOSE:To simply and easily replace only a failed magnetic sensor and to prevent a detector body to be destructed due to thermal expansion by fixing a magnetic sensor and a mold case to the detector body after forming them into a module for each magnetic sensor. CONSTITUTION:The magnetic sensor 36 and the mold case 35 are fixed to the body 33 as a module in each sensor 36. When a trouble is generated in a specific sensor 36, a protector tube 44 is detached from the body 33 of the detector 32 and the case 35 is removed, so that only the sensor 36 generating the trouble can be simply and easily replaced. Although the sensor 36 formed into the module is replaced in each case 35, the positioning of the case 35 is unnecessary for the replacement because it is automatically positioned by a positioning fitting part 34. Since the sensor 36 is protected by a mold in the case 35, the sensor 36 can resist vibration, shock and external environment, and because the mold may be used only for the sensor part 36, and the sensor 36 and the case 35 are formed into a module, the quantity of module can be reduced.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a control rod drive mechanism incorporated in a boiling water nuclear reactor, and in particular to a control rod drive mechanism incorporated in a boiling water nuclear reactor, and in particular to The present invention relates to a position indicating device that detects a positional relationship.

(Prior Art) The schematic structure of a boiling water reactor as a light water reactor is shown in the partial cross-sectional view shown in FIG. ing. A large number of control rods 3 are inserted between the fuel assemblies from below at predetermined intervals. This control rod 3 is connected to a control rod drive mechanism (hereinafter referred to as CRD).
) 4 into or out of the reactor core 2,
The output of the nuclear reactor is controlled by appropriately adjusting its setting position.

The CRDs 4 are inserted from below into control rod drive mechanism housings (hereinafter referred to as CRD housings) 5, which are provided in plural numbers on the lower head plate of the reactor pressure vessel 1, and are fixed therein.

The details of the CRD 4 are as shown in FIG. 7. A hollow piston 6 is housed in the CRD housing 5 so as to be able to rise and fall freely, and the control rod 3 and the hollow piston 6 are integrally connected by a connecting member provided at the top of the hollow piston 6. be done.

The CRD 4 performs a relatively slow insertion/extraction operation (shim operation) of the control rods 3 to adjust and maintain the reactor output at a predetermined state in normal times, and a control rod 3 to perform an emergency shutdown of the reactor in an emergency. rapid insertion (scrum operation). - In boat fishing, the shim operation is performed by the drive of the electric motor 7, and the scram operation is performed by the water pressure drive.

During the shim operation, the electric motor 7 is driven and its rotational motion is transmitted to the ball screw shaft 8 via the drive shaft 7a, causing the ball nut 9 screwed to the ball screw shaft 8 to move up and down. As a result, the control rod 3 supported and connected to the hollow piston 6 is inserted into or withdrawn from the reactor core 2.

On the other hand, during scram operation, the water pressure control unit (HCU)
) 10 via the insertion pipe 11 and further through the insertion flow path 13 formed in the CRD flange 5a, high pressure water is injected into the CRD 4, and the high pressure water pressurizes the lower surface of the hollow piston 6 and rapidly pushes it up. This allows the control rods 3 to be inserted into the reactor core 2 at high speed.

In order to know the insertion amount of the control rod 3 during this scram operation,
A magnet 15 is attached to the lower end of the hollow piston 6, and a position detector 16 (hereinafter referred to as position PIP) has reed switches arranged at regular intervals on the outside of the CRD housing 5.
) is provided to detect the opening/closing status of the reed switch which is sequentially energized by the magnet 15 as the hollow piston 10 moves, thereby detecting the moving speed of the magnet and, by extension, the moving speed of the control rod 3. .

Furthermore, the CRD 4 is provided with a separation detector 17 (hereinafter referred to as separation PIP) that detects a separation state when the control rod 3 sticks to the reactor core 2 and separates from the hollow piston 6. The separation detector 17 detects the movement of the magnet 18 at this time when the control rod 3 is separated and the weight of the control rod is removed from the drive unit, so the magnet 18 is lifted by the force of the spring 19, and the movement of the magnet 18 at this time is detected by the separation PIP 17. .

(Problems to be Solved by the Invention) As shown in FIGS. 8 and 9, the conventional PIPs 16 and 17 are fixed by engaging the lock nut 21 in the motor bracket 20 of the electric motor 7, so that installation is difficult. Sometimes height adjustment was required. The adjustment work is sometimes carried out inside the pedestal, which poses problems in reducing radiation exposure and also causes a large positional error after adjustment.

Furthermore, the reed switch 22 shown as a magnetic sensor in FIGS. 8 and 9 is fixed by a mold 23. Therefore, if the reed switch 22 breaks down, the entire mold 23 must be removed, making repair extremely difficult. Further, since the PIPs 16 and 17 are entirely filled with the molding material 23, there is a risk that the PIPs 16 and 17 will be punctured and destroyed due to thermal expansion of the molding material at high temperatures.

In addition, the moving speed of the magnets 15 and 18 is measured by the operating time between ON and OFF of the reed switch 22.
The operating width of the reed switch 22 has large variations in the OFF point, and this variation has been a cause of large measurement errors.

The present invention has been made in consideration of the above-mentioned circumstances, and makes it possible to simply and easily replace only a malfunctioning magnetic sensor, and also effectively prevents damage to the detector body due to thermal expansion of the molding material. The main purpose is to provide a position support device.

Another object of the present invention is to prevent the occurrence of positional errors by eliminating the need for position adjustment in the height direction when installing the PIF, and to
F. To provide a position support device that can be easily repaired in the event of a malfunction.

Still another object of the present invention is to reduce P due to thermal expansion of the mold.
An object of the present invention is to provide a position pointing device that can prevent destruction of an IF and accurately measure the moving speed of a magnet.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above-mentioned problems, in the position pointing device according to the present invention, a detector main body is detachably provided on the control rod drive mechanism by an attachment mechanism, and the detector main body is removably attached to the control rod drive mechanism. , a main body in which a plurality of positioning mounting parts are formed at intervals in the axial direction, a molded case provided for each positioning mounting part of this body, and a modularized magnetic sensor housed in the molded case. , a cable clamp mechanism for fixing a cable connected to the magnetic sensor to the main body, and a protector tube for protecting the magnetic sensor attached to the main body.

In addition, in order to solve the above-mentioned problems, the position pointing device according to the present invention is provided with a relay box on the main body, and this relay box connects the wiring from each magnetic sensor to the cable, and also connects the wiring from each magnetic sensor to the cable. The mechanism is a bayonet mechanism, and this bayonet mechanism fixes the detector body to the motor bracket of the control rod drive mechanism, and also
The magnetic sensor is connected to the data processing device via a cable, and is a reed switch that measures the moving speed of the magnet at the ON point of the switch.

(Function) With the above-described configuration, the position pointing device of the present invention allows the magnetic sensor and the molded case to be modularized for each magnetic sensor and attached to the main body. For this reason,
If a malfunction occurs in a particular magnetic sensor, by removing the protector tube from the main body of the detector and removing the molded case, only the malfunctioning magnetic sensor can be easily and easily replaced.

At that time, the modularized magnetic sensor is replaced for each mold case, but when replacing the mold case, the mold case is automatically positioned by the positioning mounting part on the main body, so no position adjustment is necessary. .

In addition, the magnetic sensor is protected by a mold inside the molded case, and is protected against vibrations, shocks, and external environments (temperature, humidity, etc.).
In addition to being strong against pressure), only the magnetic sensor part is required as a mold, and the magnetic sensor and mold case are modularized, so the amount of molding is small and the amount of thermal expansion is not a problem.

Also, in order to fix the detector body to the control rod drive mechanism,
By using a bayonet mechanism, the height direction and rotation direction can always be kept at a constant position and fixed, making attachment and detachment work very easy and eliminating the need for adjustment work. Therefore, the installation, removal, disassembly, and assembly of the position pointing device becomes extremely easy, and it is possible to reduce the exposure of workers to radiation.

Furthermore, if a reed switch is used as a magnetic sensor and the moving speed of the magnet is measured by detecting the transit time between the ON points of multiple reed switches, the transit time of the conventional reed switch operating width can be measured. Compared to the case where the moving speed of the magnet is measured by using the method, the measurement accuracy can be improved, the moving speed of the magnet can be measured more accurately, and the measurement interval can be arbitrarily set.

(Embodiment) Hereinafter, an embodiment of the position pointing device according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an example of a position pointing device of the present invention provided in a control rod drive mechanism (CRD) 4. As shown in FIG. This position indicating device 30 is applied to a position detector (position PIF) for detecting the insertion position and speed of a control rod, a separation detector (separation PIP) for detecting a separation state between a control rod and a hollow piston, etc. Ru. Since the CRD 4 does not differ from the conventional structure shown in FIGS. 6 and 7, reference is made to these figures and numerals.

This position pointing device 30 is the motor bracket 2 of CRD4.
It has a detector main body (PIF main body) 32 that is fixed to the main body of the PIF via a bayonet mechanism 31 that is an attachment mechanism. The detector main body 32 includes an elongated main body 33 whose cross section has a ■-shaped beam shape, and this main body 33 is shown in FIG. 2(A),
As shown in (B)! Mold beam part 33a and FIG. 2(C)
It consists of a lower cylindrical base 33b shown in FIG. The type 1 beam part 33a of the body body 33 has a plurality of notches (holes) 3 at appropriate intervals in the axial direction as mounting parts for positioning.
4 is formed, and a molded case 35 is removably inserted into this positioning notch 34 and attached thereto.

The mold case 35 accommodates and protects the reed switch 36 as a magnetic sensor by molding as shown in FIG. 2(A), and each reed switch 36 has an independent module structure as shown in FIG. 3. is formed. Wiring 37 from each modularized reed switch 36
is connected to the relay box 38. This relay box 3
Reference numeral 8 connects the wiring 37 from each magnetic sensor 36 to the cable 40, and is attached to a positioning notch 34 formed at the bottom of the main body 33. When connecting the core wire 41 of the cable 40 directly to the reed switch 36,
The relay box 38 is not necessarily required.

The main body 33 to which the molded case 35 is attached is covered with a protector tube 44. This protector tube 44 is a reed switch 3 attached to the main body 33.
6 and wiring 37 from the outside to protect them.

Further, the cable 40 is fixed to the main body 33 by a cable clamp mechanism 45, and the cable 40 is prevented from being pulled out or dropped. The cable clamp mechanism 45 is attached to the main body 3
It is attached to the end side of the base 33b of No. 3 by screw connection, and is formed of a rubber connector. The cable clamp mechanism may be of a type in which the cable 40 is directly sandwiched between two plates and tightened with a tightening screw, or any mechanism that can fix the cable 40 may be used. The cable 40 fixed by the cable clamp mechanism 45 is led out through the insertion guide hole 46 of the main body base 33b, and is connected to the data processing device 47.
connected to. The data processing device 47 is the reed switch 3
The detection signal from 6 is input and processed to measure the insertion position of the control rod, its speed, etc.

On the other hand, the bayonet mechanism 31 that fixes the detector main body 32 supports the detector main body 32 by a spring 50 interposed between a flange-shaped spring receiver 48 and a washer 49 provided at the base 33b of the main body 33. are doing. This detector main body 32 is inserted through the guide/1It51 (see FIG. 2 (C)) of the mounting hole 55 formed in the motor bracket 20 of the CRD 4, and in this inserted state, it is rotated 90 degrees and the rotation stopper pin 52 is inserted. CRD4 motor tab kerato 2
By engaging with the stopper groove 53 formed at 0, rotation is prevented and stably held.

Next, the operation of the position pointing device 30 will be explained.

In this position pointing device 30, the main body 33 of the detector main body 32 serves as a framework into which the parts of each modularized reed switch 36 are assembled. Main body 3
A positioning mounting portion is formed in the I-shaped beam portion 33a of No. 3, and a reed switch 36 is molded into the notch 34, which is the positioning mounting portion, and a modular molded case 35 is fitted therein. The cutout 34 is formed in advance at a position where the molded case 35 and the relay box 38 are fitted, a position where the wiring 37 is intersected, and the like.

A molded case 35 and a relay box 3 are attached to the main body 33.
The detector main body 32 with the detector 8 attached is inserted from below into the mounting hole 55 of the motor bracket 20 of the CRD 4, and after this insertion, the detector main body 32 is pressed upward in a floating state.
By rotating around the degree axis, the bayonet pin 52 of the detector main body 32 engages with the engagement groove 53 and is prevented from rotating, and is pressed and held in a predetermined position by the spring 50 of the bayonet mechanism 31.

The bayonet mechanism 31 always keeps the detector main body 32 at the same elevation, thereby simplifying the installation work. Further, the rotational direction of the detector body 32 can be kept constant by the bayonet mechanism 31, and the detector body 32 is positioned in the height direction and rotational direction, and no adjustment is required. Furthermore, this bayonet mechanism 31
2 is constantly biased by a spring 50 so that it does not lift up due to vibration, rotate incorrectly, or fall. At this time, a washer 49 is provided to minimize twisting of the spring 50 when it rotates. This washer 49 is attached to the detector main body 32.
When it is removed, it is engaged with and supported by the bayonet pin 52, thus preventing the parts from being lost.

By the way, if the reed switch 36, which is the magnetic sensor of the position pointing device 30, breaks down, the detector body 32 can be disconnected from the CRD.
4 from the motor bracket 20. Thereafter, the protector tube 44 is pulled out from the main body 33 and the wiring 37 of the failed reed switch 36 is removed.

After disconnecting the wiring 37 from the reed switch 36, the modularized reed switch 36 is placed in the mold case 3.
Replace with a new one every 5 minutes. Thereafter, the new molded case 35 is fitted into the positioning notch 34 of the main body 33, and the wiring 37 is connected again, thereby completing the replacement work of the reed switch 36.

When the mold case 35 is attached to the main body body 33 and the protector tube 44 is inserted, the mold case 35
is constructed so that the puller does not fall out from the main body 33.

At this time, since the reed switch 36 is housed in the molded case 35 and protected by the mold, its soundness against vibrations, shocks, temperature, pressure, humidity, etc. is improved.

Furthermore, by incorporating a simple circuit 57 in the molded case 35 side by side with the reed switch 36, the wiring 37
The routing can be simplified, simplified, or omitted. Moreover, if a notch (hole) 58 is provided in the middle of the molded case 35 to guide the wiring 37, this notch 58
Ventilation can be provided through the detector body 32, and the pressure inside the detector main body 32 can be kept constant at high temperatures. Note that even if the circuit 57 is not built into the molded case 35, the wiring 3
7 is possible, and furthermore, a gap is secured between the mold case 35 and the protector tube 44, and the circuit 57 is
If the position support circuit is configured only by this, the cutout 58 in the middle may be deleted. Also, in this case,
Wiring passing through the mold case 35 becomes unnecessary.

On the other hand, this position pointing device 30 allows the reed switch 36 to be placed in the axial center of the detector body 33. When the reed switch 36 is provided in the center of the detector body 33, no matter which direction the position indicating device 30 faces, the CR
The distance from the magnet 15, 18 (see FIG. 7) incorporated in D4 can be kept constant. As a result, the magnetic force from the magnets 15, 18 becomes constant, and the operating width of the reed switch 36 can be kept constant.

At that time, the main body 33, protector tube 44 and wiring 37 are made of non-magnetic material, and the magnet 1
The magnetic force of 5.18 is determined by the distance from the magnet 15°18.

Furthermore, the relay box 38 is connected to the core wire 41 of the cable 40.
It is recommended to use it when it is not possible to use it directly as wiring. For example, it is used when the cable core is a braided wire and cannot be attached by welding, or when the cable core is made of different materials and cannot be attached by welding.

In that case, the cable core is fixed to the terminal of the relay box 38 by clamping, brazing, etc., and the wiring 37 and the terminal of the relay box 38 are fixed by welding. cable 4
If the zero core wire 41 can be directly used as the wiring 37, the core wire 41 may be directly connected to the terminal of the molded case 35 without the relay box 38.

On the other hand, this position pointing device 30 has a function of detecting the moving speed of the magnet 15 (18) incorporated in the CRD 4, and for this moving speed detection, as shown in FIG. A method of measuring the time ΔT between ON points is adopted.

Conventional moving speed detection is based on one reed switch's 0N-
Magnet 15 (18
), but the reed switch is OFF.
Since the points vary widely from switch to switch, it is not suitable for accurate measurements. Moreover, when measuring the ON-OFF time Δt, which is the operating width, with one reed switch, it is not possible to measure a distance shorter than the operating width of the reed switch.

In contrast, this position pointing device 30 detects the moving speed of the magnet 15 (18) by measuring the transit time ΔT between the ON points of the plurality of reed switches 36, 36.

Since the ON point of the reed switch 36 is constant without variation, the moving speed of the magnet 15 can be measured accurately and accurately.

Furthermore, by measuring the transit time T between ON points, the measurement interval can be set arbitrarily, and the reed switch 3
It is also possible to measure distances shorter than the operating width (ON-OFI; 'time) of 6.

FIG. 5 shows another embodiment of the position pointing device.

In this embodiment, a molded case 35A containing a reed switch is fixed to a notch (hole) 34A, which is a positioning attachment part of a main body 33A, with a set screw 60. The set screw 60 fixes the mold case 35A to the main body 33A to prevent it from falling.

In this case as well, the mold case 35A is attached to the main body 33.
It can be easily attached to and detached from A.

In addition, in one embodiment of the present invention, an example was shown in which a circuit was provided inside the molded case, but this circuit may be provided as necessary, and the provided circuit may be standardized and configured to be of the same type. good. By routing the parts that cannot be completely wired using this standardized circuit, incorrect assembly can be prevented.

Furthermore, the number of reed switches as magnetic sensors housed in the molded case is not limited to one. A module structure may be used in which a plurality of sensors are packaged and housed in one molded case. This is effective when the distance between sensors is narrow.

Furthermore, the magnetic sensor is not limited to a reed switch, and may be any sensor that senses magnetism, such as a semiconductor sensor. Further, a connector may be used instead of the relay box, and each wire may be connected individually using pins and sockets (splices) or the like instead of the connector.

〔Effect of the invention〕

As described above, in the position indicating device according to the present invention, the detector body is detachably attached to the control rod drive mechanism by the attachment mechanism, and the detector body is provided with a molded case at each positioning attachment part of the main body. Since a modularized magnetic sensor is housed in the molded case, even if a problem occurs in a particular magnetic sensor, only the defective magnetic sensor can be easily and easily replaced.

In addition, since the magnetic sensor is modularized and housed in a molded case, it is resistant to vibrations, shocks, and external environments (temperature, humidity, pressure), and there is no need to mold the entire inside of the detector body. Therefore, the amount of molding is small, and damage to the detector body due to thermal expansion of the molding material can be effectively prevented.

On the other hand, since the molded case is attached to the main body and covered by the protector tube, the magnetic sensor and wiring modularized and housed in the molded case are sufficiently protected from the outside.

In addition, since the detector body is removably attached to the control rod drive mechanism using an attachment mechanism, maintenance and inspection of the detector body can be performed easily and easily. , there is no need to adjust the height or rotational position when installing the detector body.
Since no adjustment work is required, installation, removal, disassembly, and assembly work are simplified, reducing the work burden on workers and reducing exposure to radiation.

Furthermore, by using a reed switch as a magnetic sensor and measuring the transit time between the ON points of multiple reed switches, the moving speed of the magnet can be measured accurately and accurately, and the measurement interval can be set arbitrarily. can be measured.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the position pointing device according to the present invention, and FIGS. 2 (A), (B), and (C) are lines AA, BB, and 3 is a perspective view showing the combination of the main body and molded case provided in the position pointing device, and FIG. 4 is a detection diagram for detecting the moving speed of the magnet by this position pointing device. Figure 5 is a diagram illustrating the principle of the invention, and Figure 5 is a perspective view showing a combination of the main body and molded case, and Figure 6 is a simplified diagram of a general boiling water reactor. Figure, 7th
The figure is a vertical cross-sectional view showing the control rod drive mechanism installed in the reactor, Figure 8 is a diagram showing a position detector provided in the control rod drive mechanism, and Figure 9 is a separate detection device provided in the control rod drive mechanism. FIG. 4... Control rod drive mechanism, 6... Hollow piston, 15
．． 18... Magnet, 20... Motor bracket, 30... Position indicating device, 31... Bayonet mechanism (mounting mechanism), 32... Detector body, 33.33A.
...Main body, 34.34A...Mounting part for positioning (notch, hole), 35.35A...Mold case,
36... Reed switch (magnetic sensor), 37...
Wiring, 38... Relay box, 40... Cable,
41... Core wire, 44... Protector tube, 45
... Cable clamp mechanism, 47 ... Data processing device, 55 ... Mounting hole.

Claims (1)

[Claims] 1. A detector body is detachably attached to the control rod drive mechanism by an attachment mechanism, and the detector body has a main body in which a plurality of positioning attachment parts are formed at intervals in the axial direction. , a molded case provided at each positioning attachment part of the body, a modularized magnetic sensor housed in the molded case, and a cable clamp mechanism for fixing a cable connected to the magnetic sensor to the main body; A position pointing device comprising: a protector tube that protects a magnetic sensor attached to the main body. 2. The position pointing device according to claim 1, wherein the main body is provided with a relay box, and the relay box connects wiring from each magnetic sensor to a cable. 3. The position pointing device according to claim 1, wherein the mounting mechanism is a bayonet mechanism, and the detector body is fixed to the motor bracket of the control rod drive mechanism by the bayonet mechanism. 4. The position pointing device according to claim 1, wherein the magnetic sensor is connected to the data processing device via a cable, and the magnetic sensor is a reed switch that measures the moving speed of the magnet at the ON point of the switch.