JPH0252293A - Fault diagnostic device for reverse rotation prevention device - Google Patents

Abstract

PURPOSE:To detect a function without detaching the reverse rotation prevention device by providing electrodes which are arranged equally in a peripheral direction while insulated electrically from a cylinder, and connecting one terminal to a slide electrode and the other terminal to independent current detectors. CONSTITUTION:Recessed parts are distributed and provided opposite the movable piece 25a of the cylinder 23 at two positions in the axial direction and at plural positions in the circumferential direction without overlapping each other in the circumferential direction. Electrodes 30 are mounted in the respective recessed parts through insulating spacers 29. Further, a water-proof insulating electrode 32 which penetrates the bottom surface of the cylinder 23 through a water-proof seal 31 is connected to each electrode 30. The upper end of a slide electrode 3 at at least on position which penetrates the bottom surface of the cylinder 23 watertightly is made to abut on the bottom surface of a rotary body 22. The lower end of the electrode 33 is connected directly to one terminal of the electrode 34 and an electric conductor 32 which is connected to each electrode 30 on the peripheral surface of the cylinder 23 is connected to the other terminal of a power source 34 through a current detector 35.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention relates to a failure diagnosis device for a reverse rotation preventer of an internal pump used for circulating coolant in a boiling water nuclear reactor. .

(Prior Art) FIG. 3 is a schematic cross-sectional view of a boiling water nuclear reactor equipped with an internal pump. In this figure, reactor pressure vessel 1
A reactor core 3 and a shroud 2 surrounding the reactor core 3 are provided inside the reactor pressure vessel 1, and around the bottom of the reactor pressure vessel 1, that is, in a portion corresponding to a downcomer 5 having an annular cross section between the reactor pressure vessel 1 and the shroud 2. , a plurality of cylinders, for example ten internal pumps 4, are provided.

The behavior of reactor water in the reactor pressure vessel 1 is as follows. The reactor water that has descended in the downcomer 5 is sent to the lower part of the reactor core 3 by the internal pump 4, and flows into the reactor core 3 from there. The reactor water that has flowed into the reactor core 3 is boiled by the heat generated by the nuclear reaction, and rises through the reactor core 3 as a two-phase flow of water and steam. This two-phase flow of water and steam is separated into water and steam in a steam separator 6 above the reactor core 3, and the separated steam is subjected to moisture removal in a steam dryer 7 and then to a turbine (not shown). sent to. Further, the separated water descends again through the downcomer 5 together with water from a sparger 8 provided above the core 3, and is fed into the core 3 by the internal pump 4. ” The cycle described in 1 will be repeated. In addition, at the bottom of the reactor pressure vessel 1, there is a control rod drive mechanism 9 with multiple cylinders (approximately 200 pieces), although only two pieces are shown in the figure.
These control rod drive mechanisms 9 control the reactivity of the reactor core 3 by inserting and removing corresponding control rods (not shown) from the reactor core 3.

The internal pump 4 is constructed as shown in FIG. In this figure, the internal pump 4 has a pump section 10 located inside the pressure vessel 1 and a drive section 11 located outside the pressure vessel 1. The pump section 10 includes an impeller 14 driven by a shaft 3 detachably connected to an output shaft of a motor 12 of a drive section 11, and a diffuser 15 concentrically surrounding the impeller 14. Further, the impeller 14 is positioned at the tip of a pump mounting nozzle 18 protruding from the bottom of the pressure vessel 1 by tightening a stretch tube nut 17 screwed onto the lower end of a stretch tube 16 that concentrically surrounds the shaft 13. has been done.

Further, the motor casing 19 of the drive unit 11 provided outside the pressure vessel 1 has a tip end 19a that tightly surrounds most of the lower part of the stretch tube "-6. It extends into the pump mounting nozzle 18 and is fixed to the bottom of the pressure vessel 1 by welding. Furthermore, a removable motor cover 12a is provided on the bottom surface of the motor casing 19.

Motor co-2 provided in the motor casing 19
is of the water immersion type, and is assumed to be operated despite the presence of reactor water that has entered from the pump attachment nozzle [8].

In the figure, reference numerals 20 and 21 designate a liquid-tight motor casing to which the motor cover 12a can be attached or removed.

The studs and nuts 1- attached to 9 are shown.

At the lower end of the shaft 13, a reverse rotation preventer 2, whose details are shown in FIGS. 5 and 6 (cross-sectional view taken along the line A-A in FIG. 5), is installed to prevent the shaft j-3 from rotating in the opposite direction. ing.

In FIGS. 5 and 6, a hollow cylindrical rotating body 22 is provided integrally with the lower end of the shaft 13, and a cylinder 23 protrudes concentrically into the rotating body 22 from the lower fixed side. Inside the rotating body 22, there are two ring plates 2 spaced apart in the axial direction.
4 are fixedly provided, and a jam block 25 is fixedly supported between the ring plates. jam block 25
The movable piece 25a is pivoted to a plurality of pins 26 provided on the ring plate 24 at positions close to the inner circumferential surface of the rotating body 22 and equally spaced in the circumferential direction, as described below, and the movable piece 25a. A cylindrical cage 2 provided with a cavity 25c for accommodating movable pieces such as
5b.

The movable piece 25a has a diameter equal to the inner diameter of the rotating body 22, and is formed by combining three circular arcs with an apex angle of 60', and has a cross section of an equilateral triangle with each side convex outward. Therefore, from the bisector of the apex angle of the − vertex, the rotating body 2
It is pivoted by the pin 26 at a position offset in the direction opposite to the direction of rotation of No. 2 (arrow 35). Further, a spring force directed toward the cylinder 23 is applied to the movable piece 25a by a spring 27.

When the internal pump 4 is rotating in the normal direction (arrow 35), the movable piece 25a resists the spring force of the spring 27 due to the centrifugal force caused by the rotation of the rotating body 22, and moves outward around the pin 26. The cylinder 23 rotates toward the cylinder 23 and moves away from the cylinder 23. That is, the jam block 25 does not impede the rotation of the rotating body 22 and hence the internal pump 4 in any way.

On the other hand, the rotating body 22 is in the opposite direction (opposite direction to the arrow 35).
When the movable piece 25a rotates to generates a large frictional force. This applies braking to the rotating body 22 and prevents it from reversing.

(Problem to be Solved by the Invention) When the reverse rotation preventer having the configuration described above is operated for about one year, dust etc. generated in the motor 12 will be transferred to the movable piece 25a.
If the movable piece 25a gets stuck in the gap between the pin 26 and the pin 26, the movable piece 25a may become unable to rotate. However, during normal operation of the internal pump, the movable piece 25a is in contact with the inner peripheral surface of the rotating body 22, so if the movable piece becomes unable to rotate as described in item 1, it will not function as a reverse rotation preventer. become. The internal pump whose anti-reverse device has become inoperable as described above will rotate in reverse several thousand times for seven minutes if other internal pumps are in operation due to the flow generated by those pumps. This rotational speed far exceeds the rated rotational speed of the internal pump, and since it rotates in the opposite direction, there is a risk that the pump will be destroyed.

If the above-mentioned reversal preventer malfunctions, the internal pump must be disassembled,
It can only be discovered during inspection.

However, disassembling and inspecting the internal pump is done once every few years.
This is done only once, and if the above-mentioned failure occurs during that time, it could cause a major accident.

In order to avoid this, it is obvious that the internal pump should be disassembled and inspected at least once a year. Procedures such as removing the reverse rotation preventer, inspecting it, reassembling it, and pouring water into the motor must be followed, which requires a considerable amount of time and effort.

The present invention has been made based on the above-mentioned circumstances, and it is an object of the present invention to provide a reverse rotation preventer failure diagnosis device that can detect whether or not the reverse rotation preventer is functioning without removing the reverse rotation preventer.

[Structure of the Invention (Means for Solving the Problems) The reversal preventer failure diagnosis device of the present invention comprises a hollow cylindrical rotating body integrally provided at the lower end of a shaft that drives an impeller of an internal pump, and A cylinder protrudes concentrically from a stationary side within the rotating body, and a movable piece interposed between the rotating body and the cylinder that exerts a reversal prevention action on the rotating body by a wedge action in the gap between the two when the rotating body reverses. and a jam block provided with a jam block, wherein electrodes are provided on the circumferential surface of the cylinder, electrically insulated from the cylinder and equally distributed in the circumferential direction, at least as many as the movable pieces, and electrodes protruding from the fixed side. a sliding electrode in contact with the bottom surface of the rotating body;
and a power source having one terminal connected to the sliding electrode and the other terminal connected to the electrode via each independent current detector.

(Function) In the anti-reverse failure diagnosis device of the present invention having the configuration described in item 1, when the internal pump and thus the rotating body are rotating in the normal direction, the movable piece is separated from the cylinder by the centrifugal force caused by the rotation. They are separated. At this time, each movable piece is separated from the electrode on the circumferential surface of the cylinder and rotates together with the rotating body, and each electrode and the rotating body are electrically disconnected. At this time, none of the current detectors shows a detection output.

When the internal pump is in reverse rotation, each movable piece is pressed against the circumferential surface of the cylinder by the applied spring force and the superimposed centrifugal force in the opposite direction to that during normal rotation, and rotates with each electrode via each movable piece. The object is electrically connected to the body, and a closed circuit consisting of the electrode, rotating body, sliding electrode, power source, and current detector is completed, and current flows through this circuit to produce a detection output from the current detector. However, if there is a movable piece that cannot rotate due to adhesion of dust, etc. and does not contribute to the reverse rotation prevention effect, the closed circuit including the electrode facing it will not be completed, and the current detector connected to that electrode will not be completed. shows no detection output.

Therefore, by monitoring the output of the current detector during reverse rotation, the health of the reverse rotation preventer can be diagnosed.

(Embodiment) Fig. 1, in which the same parts as in Figs. 5 and 6 are denoted by the same reference numerals, is a longitudinal sectional view of an embodiment of the present invention, and Fig. 2 is a perspective view showing a part thereof. be.

In these figures, the movable piece 25a of the cylinder 23
A plurality of cylindrical recesses 28 are provided at two locations in the axial direction and at multiple locations in the circumferential direction so that their positions in the circumferential direction do not overlap each other, and an insulating spacer 29 is provided in each recess. Electrodes 30 are attached to each via. Note that the number of recesses 28 arranged in each of the upper and lower rows is the same as that of the movable pieces 25a for each row. Furthermore, a waterproof insulated wire 32 is connected to each electrode 30, passing through the bottom surface of the cylinder 23 via a waterproof seal 31.

On the other hand, the cylinder 2 is placed on the bottom surface of the rotating body 22 in a liquid-tight manner as described above.
3. The upper end of at least one sliding electrode 33 that penetrates through the bottom surface is in contact with the upper end.

The lower end of the sliding electrode 33 is directly connected to one terminal of a power source 34, and the electric wires 32 connected to each electrode 30 on the circumferential surface of the cylinder 23 are connected to the power source 34 through a current detector 35.
is connected to the other terminal of the

The anti-reverse failure diagnosis device of the present invention having the above configuration operates as follows. That is, as described above, when the internal pump and thus the rotating body 22 are rotating in the normal direction, the movable piece 25a of the jam block is separated from the cylinder 23 due to the centrifugal force caused by the rotation of the rotating body 22. be. By the way, at this time, each movable piece 25a is spaced apart from the electrode 30 on the cylinder 23 side and is rotating together with the rotating body 22, and each electrode 30 and the rotating body 22 are in an electrically disconnected state. At this time, which current detector 35
also shows no detection output.

Suppose now that the internal pump starts rotating in reverse. In this case, as described above, each movable piece 25a is pressed against the circumferential surface of the cylinder 23 by the spring force applied by the spring 27 and the superimposed centrifugal force in the direction opposite to that during normal rotation.

Each electrode 30 and the rotating body 22 are electrically connected through these movable pieces 25a that are in suppressed contact, and the electrode 30, the rotating body 22, the sliding electrode 33, the power source 34, and the current detection A closed circuit consisting of the device 35 and the waterproof insulated wire 32 is completed, current flows through this circuit, and the current detector 35 detects this and produces a detection output. However, if there is a movable piece that cannot rotate due to the adhesion of dust, etc. and does not contribute to the reverse rotation prevention effect, the closed circuit including the electrode facing it is not completed, and the connection to that electrode is not completed. The current detector that has been removed will not show any detection output.

As is clear from the above, in the reverse rotation preventer failure diagnosis device of the present invention, if there is a detection output from the current detector 35 during reverse rotation, the movable piece passing through the electrode connected to that detector is operating normally. If there is no detection output, it can be known that a failure has occurred in the movable piece, and the failure of the reverse rotation preventer can be diagnosed without disassembling it.

Note that the present invention is not limited to the above embodiments.

For example, only one row of electrodes may be provided on the circumferential surface of the cylinder. Further, in order to further ensure operation, there may be three or more rows.

[Effects of the Invention] As is clear from the above, according to the reversal preventer failure diagnosis device of the present invention, it is possible to immediately detect when the movable piece of the reversal preventer jam block loses its function without disassembling the device. Can be done. Therefore, whereas conventionally the reverse preventer could be diagnosed by disassembly and inspection during periodic inspections, the reverse preventer failure diagnosis device of the present invention can perform the diagnosis simply and easily. It is extremely beneficial for maintaining health.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of an embodiment of the present invention, Fig. 2 is a perspective view showing the main parts thereof, Fig. 3 is a schematic longitudinal sectional view showing an outline of a boiling water reactor, and Fig. 4. is a vertical cross-sectional view showing the outline of the internal pump and the installation position of the reverse rotation preventer, FIG. 5 is a vertical cross-sectional view of a conventional reverse rotation preventer, and FIG.
It is a sectional view taken along the A line. 1...Reactor pressure vessel 2...Shroud 3...Reactor core 4...Internal pump 21...Return preventer 22...・・・
Rotating body 23...Cylinder 24...Ring plate 25...Jam block 25a...
...Movable piece 25b...Cage 26...
・Pin 27... Spring 28... Concave part
29... Insulating spacer 30... Electrode
32...Waterproof insulated wire 33...Sliding electrode 34...Power supply 35...Current detector

Claims (1)

[Claims] A hollow cylindrical rotating body integrally provided at the lower end of a shaft that drives the impeller of the internal pump, a cylinder concentrically protruding from the fixed side within the rotating body, and a cylinder interposed between the rotating body and the cylinder. and a jam block having a movable piece that prevents the rotating body from reversing by a wedge action in the gap between the two when the rotating body reverses. electrodes equally spaced in the circumferential direction and provided at least as many as the movable pieces; a sliding electrode that protrudes from the fixed side and contacts the bottom surface of the rotating body; and one terminal connected to the sliding electrode and the other electrode. A failure diagnosis device for a reverse rotation preventer, comprising: a power source whose terminals are connected to the electrodes via independent current detectors.