JPH0143280B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for inspecting pressure pipes in a pressure tube nuclear reactor, and more specifically, the present invention relates to a method for inspecting pressure pipes in a pressure tube nuclear reactor, and more specifically, using an inspection device having a shape and size that fits inside the pressure tube, and using the inspection device using a fuel exchange device. The present invention relates to a method for inspecting a nuclear reactor pressure pipe, in which the pressure pipe is remotely attached to and removed from the pressure pipe, and the inspection is also performed by remote control.

The pressure pipes that make up the core of pressure tube reactors are supposed to be inspected during their service life according to regulations, but because the inside and surroundings of the pressure pipes to be inspected are in a high radiation environment, it is difficult to inspect them during their service life. In order to avoid radiation exposure to inspectors during intermediate inspections, inspections are conducted using remote automated equipment.

In a pressure reactor, due to its structural limitations, it is not possible to install a rail or the like in advance to allow the inspection device to approach the pressure pipe. Therefore, according to the prior art, pressure pipe inspections have generally been carried out using one of the following two methods.

The first method, as shown in Figure 1, is
Before conducting the inspection, an inspection device consisting of a detector 2, its driving device 3, a holding member 4, a positioning device 6, etc. is assembled manually near the pressure pipe 1, and then
Detector 2 attached to the tip of support rod 5 by remote control
A method in which the device is inserted into the inside of the pressure pipe to be tested, and when the test is completed, the device is manually disassembled and removed (hereinafter referred to as the "external installation method").
It is.

However, although this method avoids radiation exposure to the inspector during the inspection, it cannot avoid radiation exposure during the assembly and disassembly of the equipment, and the work is very cumbersome as it must be assembled and disassembled each time an inspection is performed. Furthermore, when conducting an inspection, since reactor cooling water is contained in the pressure pipe, the water in the pressure pipe to be inspected must be drained unless the entire inspection apparatus is constructed to be watertight. In order to remove this water, since there are no valves at the inlet and outlet of each pressure pipe, it is necessary to freeze some of the water in the inlet and outlet pipes with liquid nitrogen (ice plug) and use it as a substitute for the valve. , this is also a tedious task. Furthermore, since it is difficult to install a plurality of inspection devices due to space constraints, there is a drawback that the inspection takes a long time when a large number of pressure pipes are to be inspected.

The second method, as shown in Figure 2,
The drive device 8 of the fuel exchange device 7, which is permanently installed in the reactor, is used to insert and take out fuel in the reactor core, and only the detector 2 is attached to the drive device 8 during inspection during the service period. This is a method (hereinafter referred to as a "combined fuel exchange system") in which the fuel exchanger is attached via a support rod 5 and inserted into the pressure pipe to be inspected by remote control to inspect the pressure pipe.

However, since this method uses a fuel exchange device, there is no need to assemble or disassemble the device.
The problem of radiation exposure for inspectors, which is a disadvantage of the "external installation method," has been solved, and since the fuel exchange device has a watertight structure, there is no need to drain water from the pressure pipes, but it is still necessary to inspect the pressure pipes. During this time, the fuel exchange equipment is occupied exclusively, so in this case as well, if there are a large number of pressure pipes to be inspected, the inspection will take a long time.

The purpose of the present invention is to eliminate the drawbacks of the prior art as described above, reduce the radiation exposure of inspectors when inspecting nuclear reactor pressure pipes during their service life, and at the same time,
An object of the present invention is to provide a pressure pipe inspection method that has good workability and can significantly shorten the time required for inspection.

The present invention, which can achieve the above object, employs an "external installation method" in which a vertical drive device, etc. exclusively for inspection is installed externally and only the detector is inserted into the pressure pipe, and a vertical drive device for fuel exchange equipment. Unlike the "combined fuel exchange system," which uses a fuel exchange system, the detector, its driving device, and fixing mechanism are integrated, and the entire system is miniaturized so that it can be inserted into the pressure pipe. This can be done using a fuel exchange device.

The present inventors analyzed the above-mentioned conventional technology from various angles and considered measures that could eliminate the shortcomings of the conventional technology.
Although the pressure tube was sufficiently contained inside the pressure pipe, we reached the conclusion that there was a problem with the large size of the drive device, holding members, etc., and we proceeded with further investigation. As a result, if the fuel exchange device 7 is used, the positioning device 6 in the external installation method becomes unnecessary.
If the device 6 can be omitted from the inspection device, and if the entire inspection device can be inserted and fixed inside the pressure pipe 1, the detector 2 will be close to the part to be inspected, so the drive stroke will be as long as the inspection range. In the external installation method, the holding member 4 of the device occupies a considerable amount of space, but if the device can be placed inside the pressure pipe, the pressure pipe will serve as the holding member for the device. The holding member can be simplified; in this way, the overall size and weight can be reduced, and the power source, which used to require a motor of several hundred watts, can be reduced to a motor of several tens of watts, making it compact enough to fit inside the pressure pipe. It can be replaced with that of , etc. The present invention was devised based on such analysis and study.

Hereinafter, one embodiment of the present invention will be described based on the drawings. 3A to 3D show an embodiment of the inspection method according to the present invention, and FIG. 4 shows the state during inspection. As shown in detail in FIG. 4, the inspection device 11 has a geometry that allows it to be completely housed inside the pressure tube 1. This inspection device 11 includes an ultrasonic flaw detector, a television camera,
A detector 15 such as an inner diameter measuring device, and a vertical drive device 16
and a rotation drive device 17, a fixing mechanism 18 for fixing the entire inspection device to the pressure pipe 1, and a sealing part 20 for sealing reactor cooling water. This fixing mechanism 18 is configured to be easily attachable and detachable, for example, by a combination of a ball and a latch, and a drive mechanism is fixed to the fixing mechanism 18 to movably support the detector 15.
The vertical drive device 16 is a pinion 2 in this embodiment.
5 and a rack 26, other configurations may be used, such as a wire-driven type. Three rotating ball guides 19 are provided on the outer periphery of the movable part of the inspection device 11, and these guides contact the inner surface of the pressure pipe 1 to always position the movable part in the center of the pressure pipe 1 and keep the pressure Guide so that smooth vertical movement and rotational movement can be performed inside the tube 1. More specifically, one of these three guides 19
The three guides 19 are pushed outward by a spring, so that even if the inner diameter of the pressure tube 1 changes somewhat, the three guides 19 can always come into contact with the inner surface of the pressure tube 1.

This inspection device 11 can be handled by a fuel exchange device 6 permanently installed in the nuclear reactor, and can thereby be remotely attached to or detached from the pressure pipe to be inspected. In addition, the connector 1 attached to the end of the signal transmission cable 13
4 is detachable from the inspection device 11 using the manipulator 22 of the fuel exchange device 6, and the inspection device 11 can be remotely operated from the outside by the control panel 12 connected to the signal transmission cable 13. It's becoming like that. The mechanism for attaching and detaching the connector 14 to and from the inspection device 11 can also be configured by, for example, a combination of a ball and a latch.

The present invention will be explained as follows with reference to FIGS. 3A to 3D according to the procedure for using the inspection device 11. First, the fuel 10 in the pressure pipe to be inspected is extracted using the fuel exchange device 7, and the seal plug 9 for sealing the reactor cooling water is attached. Then, the inspection device 11 is suspended by a crane 23 and installed in the fuel exchange device 7 (see A in the same figure).
Next, the fuel exchange device 7 is driven to the pressure pipe 1 to be inspected, and after positioning it (see B in the same figure), the upper end of the agricultural product exchange device 7 is connected to the pressure pipe 1 to prevent reactor cooling water from leaking. , and remove the seal plug 9 (the procedure for removing the seal plug 9 is not shown, but the function is included in the fuel exchange device 7). Furthermore, the inspection device 11 is inserted into the pressure tube 1 (see C in the same figure), and the inspection device 11 is fixed inside the pressure tube 1 by the fixing mechanism 18 of the inspection device 11. At this time, the reactor cooling water is sealed by the seat portion 20. After that, the fuel exchange device 7 is slightly shifted and the manipulator 22 is moved to the pressure pipe 1 to be inspected.
and connect the connector 14 to the inspection device 11 using the manipulator 22 (see D in the figure). All of these operations can be performed remotely using the movements of the fuel exchange device 7 and manipulator 22.

The preparation for the inspection is now complete, and as shown in FIG.
5 to the location to be inspected and conduct the inspection. At this time, the guide 19 serves to smoothly operate the inspection device 11 within the pressure pipe, as described above. When the inspection is completed, the inspection device 11 is taken out from the pressure pipe 1 to be inspected by reversing the above procedure, and the inspection is completed during the service period.

In this embodiment, the signal transmission between the inspection device 11 and the control panel 12 is performed via the signal transmission cable 13, but wireless transmission may also be used.

Since the present invention is a method for inspecting a nuclear reactor pressure pipe configured as described above, there is no need to assemble and remove an inspection device near the reactor core before or after inspection.
The radiation exposure for inspectors can be reduced to less than 1/10 compared to the conventional "external installation method," and there is no need to drain the cooling water from the pressure pipes being inspected, which saves time and effort in preparing for inspections. Furthermore, the fuel exchange device can be used freely after inserting the inspection device into the pressure pipe to be inspected.If you prepare multiple inspection devices, it is possible to test other pressure pipes in parallel while inspecting one pressure pipe. Since the pipes can be inspected, the inspection time can be shortened compared to the conventional "combined fuel exchange system", and many other excellent effects can be achieved.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the conventional "external installation method", Fig. 2 is an explanatory diagram of the conventional "combined fuel exchange system", and Figs. 3 A, B, C, and D are illustrations of an embodiment of the present invention. FIG. 4 is an explanatory diagram showing the situation during inspection of the inspection apparatus used in the present invention. 1... Pressure pipe, 7... Fuel exchange device, 11...
Inspection device, 15...detector, 16...vertical drive device, 17...rotary drive device, 18...fixing mechanism,
20...Seal part.

Claims (1)

[Claims] 1 A fixing mechanism that has a shape and size that fits within the pressure pipe of a pressure tube reactor and is fixed within the pressure pipe;
An inspection device comprising a detector for inspecting a pressure pipe, a drive device attached to the fixing mechanism to freely move the detector by remote control, and a sealing part for sealing reactor cooling water. The entire inspection device is remotely inserted into the pressure pipe to be inspected using a fuel exchange device, the inspection device is fixed in the pressure pipe with a fixing mechanism, and then the inspection device is remotely and automatically operated to reduce the pressure. 1. A method for inspecting a reactor pressure pipe, which comprises inspecting the pipe and, after the inspection is completed, remotely removing the inspection device from inside the pressure pipe using a fuel exchange device.