JPS6148329B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cable insertion device for flaw detection of a tube body, and more particularly to a cable insertion device suitable for flaw detection of a multilayer helical coil used in a heat exchanger of a nuclear reactor.

Heat exchangers used in nuclear reactors often have heat exchanger tubes bent into complex shapes to improve heat transfer efficiency, especially multilayer helical coils. In this case, if the heat transfer tube is damaged and the internal fluid comes into contact with the heat transfer medium, a serious accident may occur. In particular, if the fluid in the heat transfer tube is water and the heat transfer medium is sodium, there is a risk that if the two come into contact, they will react explosively and cause a catastrophic accident such as destruction of the heat exchanger. For this reason, it is necessary to periodically perform flaw detection on the heat exchanger tube, but flaw detection from the outside of the heat exchanger tube is not necessarily sufficient, and there is a demand for flaw detection from the inside of the heat exchanger tube. The inventors have developed and put into practical use a flaw detection cable in which a flaw detection device is attached to the tip of the cable and floats are attached at equal intervals for flaw detection from inside the heat transfer tube. FIG. 1 shows this cable insertion device for flaw detection.

In the figure, water W is injected and filled into the main body 26 of the apparatus, and a cable 25 for deep wounds wound around a drum 22 is sent out by rotating a handle 23. The sent-out cable 25 enters the heat exchanger tube 27 to be inspected from the nozzle 28 along the flow of water inside the device, moves forward with the flow of water,
Flaw detection is performed from the inner surface of the tube using a flaw detection device (not shown) attached to the tip. In the case of this device, if the rotation speed of the handle 23 is too fast, the cable 25 will become slack, and the cable will float up inside the device due to the buoyancy of the float 29, and in severe cases, it will get tangled in the device and become impossible to send out. . In this case, the repair must be carried out by removing the bolts 38, removing the top cover 21, and draining the water inside the device, which is inconvenient to handle. In addition, in the case of this type of device, there is a problem in that since the state of the cable being extended cannot be observed from the outside, an accident may not be noticed until the device becomes inoperable.

In addition, the length of the tube to be tested can reach approximately 100 mm in the case of multilayer helical coils, but when a cable is inserted into such a long tube, the resistance inside the tube increases as the cable moves forward. Water flow becomes poor. If the water pressure is increased to advance the cable further, the water will tend to flow backwards and eventually the cable will no longer be able to advance.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems, and to provide a device that allows the cable to be checked to see how it is being fed out and to freely move the cable forward even if it is a long tube.

In short, the present invention is a device consisting of a sprocket for sending out a deeply flawed cable, and a cable feeding tube for advancing the flaw detection cable using pressurized water, and a mechanism for preventing water from flowing back into the cable feeding tube.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, reference numeral 1 denotes a main body of the insertion device, and at the upper part of the main body 1 there is a main sprocket 5a supported by a spring 6, and a main sprocket 5a which is also supported by a spring (not shown) and is located opposite to the main sprocket 5a. The sub sprocket 5b is arranged so as to Recesses 5a' and 5b' are formed in the sprockets 5a and 5b, respectively, and each float 29 of the cable 25 to be fed is engaged with the recess, respectively, so that the cable 25
It is constructed so as to prevent it from advancing freely due to water pressure. Reference numeral 2 denotes a cable feed pipe arranged within the main body 1 of the apparatus. A water supply injection part 7 is formed at the lower part of the cable feed pipe 2. An annular water supply distribution passage 7a is formed in this cable injection part 7, and a plurality of water supply injection passages 7b branch from this water supply distribution passage 7a, and the cable passage 2a opens in the traveling direction of the cable 25. It is open to

Next, reference numeral A indicates a water supply backflow prevention part formed at the upper part of the cable feed pipe 2. FIG. 3 shows the details of the water supply backflow prevention part, 30 is a backflow prevention body, and there are a plurality of them (for example, 4 pieces) in the circumferential direction of the cable passage 2a.
arranged to form a set of backflow prevention parts. In the illustrated example, two sets (two stages) of this backflow prevention section are arranged. 33 is an adjustment body screwed into the cable feed pipe;
Reference numeral 1 denotes a spring interposed between the adjustment body 33 and the backflow prevention body 30. This spring 31 is the backflow prevention body 30
The engaging pin 33a is connected to the adjusting body 33 by a method such as welding, and the adjusting body 33 side is connected to the adjusting body 33.
It is in contact with the rotation of the connecting body independently through.
A ring 19 is fitted into the float 29 of the cable 25 to engage with the backflow preventer 30 to improve water sealing.

The operating state of the above device is shown below.

First, when inserting the cable 25 into a pipe body to which a deep wound is to be made, pressurized water W is supplied from the water supply nozzle 4. The water supply W is violently injected into the cable passage 2a in the cable traveling direction through the water supply distribution passage 7a and the water supply injection passage 7b, and the cable 25 moves forward along the flow of this water supply. in this case,
Since each float 29 of the cable 25 is held between the main sprocket 5a and the sub sprocket 5b, the cable does not move forward automatically due to the water flow, and the speed of movement of the cable 25 can be adjusted by adjusting the rotation of each sprocket. Further, in this case, the tensile force of the cable 25 is absorbed by the spring 6, so there is no risk of the cable breaking.

Also, a part of the injected water supply W flows backward and rises inside the cable passage 2a, but most of it is blocked by the backflow prevention part formed at the upper part of the cable feed pipe 2. That is, as shown in FIG. 3, when the cable 25 moves forward and the float 29 passes, each backflow prevention body 30 retreats to allow the float 29 to pass and prevent water from flowing back. In this case, the pressing force of the spring 31 can be adjusted by rotating the adjustment body 33. Note that since the spring 31 is arranged independently of the rotation of the adjustment body 33, the backflow prevention body 30 does not rotate via the spring 31.

Next, when pulling back the cable 25, the supply of water W is stopped, and each sprocket 5a, 5b is rotated in the opposite direction to that described above to be pulled back. in this case,
In the backflow prevention section, the adjustment body 33 is rotated to prevent the backflow prevention body 30 from getting caught on the float 29. That is, by rotating the adjustment body 33 and moving it to the outside of the cable feed pipe 2, the spring 3
The engagement pin 33a, which is rotatably engaged with the spring 31, pulls the spring 31 in the moving direction of the adjustment body 33, and the backflow prevention body 30 fixed to the spring 31 is drawn into the space in which the spring 31 is arranged.

By implementing this invention, there is no need to worry about the flaw detection cable getting tangled, and the reliability of the device is greatly improved.Also, even when using high-pressure water supply, there is only a slight backflow of the water supply, so it can be used even with long pipes. Deeply damaged cables can be advanced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional deep flaw cable insertion device, FIG. 2 is a sectional view of a flaw detection cable insertion device according to the present invention, and FIG. 3 is an enlarged sectional view of a backflow prevention section. 2... Cable feed pipe, 2a... Cable passage, 5a... Main sprocket, 5b... Sub sprocket, 5a, 5b... Float engagement recess, 6
... Spring, 7b ... Water supply injection passage, 25 ... Flaw detection cable, 29 ... Float, 30 ... Backflow prevention body, 31 ... Spring, 33 ... ... Adjustment body.

Claims (1)

[Scope of Claims] 1. A sprocket having a recess that engages with a float of a flaw detection cable, a cable feed pipe having a cable passage in the center, a backflow prevention part formed at the upper part of the cable feed pipe, and a backflow prevention part formed at the top of the cable feed pipe. A flaw detection cable insertion device consisting of a water supply jet passage that opens in the cable traveling direction with respect to the cable passage below the prevention part. 2. A plurality of backflow prevention bodies arranged in the circumferential direction of the cable passage, and an adjustment body screwed into the cable feed pipe;
The flaw detection cable insertion device according to claim 1, characterized in that a set of backflow prevention parts each consisting of a backflow prevention body and a spring interposed between the adjustment body are arranged in one or more stages in the cable traveling direction. . 3. The flaw detection cable insertion device according to claim 1 or 2, wherein the sprocket is supported by a spring.