JPH0254507B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a running track for a device for monitoring or inspecting a lower mirror of a nuclear reactor pressure vessel.

This track is installed in correspondence with the lower mirror part and circumferential weld line 4 in the reactor pressure vessel support part 3, as shown in Figure 1, and is used for running automatic ultrasonic flaw detection equipment, etc. It is something that will be done.

However, the ambient temperature of this orbit changes from about 300°C to room temperature as the plant starts and stops. For this reason, it is necessary to absorb the thermal expansion of the track and to securely fix it so that it does not sway due to external forces for running purposes or as a countermeasure against earthquakes and the like.

Conventionally, a circular track is supported by a plurality of support pins 7 and guide tools 6 arranged radially as shown in Fig. 2, and thermal expansion of the track is controlled by sliding the support pins with the guide tools. , absorption is being carried out.

However, since the support pins move linearly, this device suffers from galling and other problems, making it difficult to ensure smooth movement over a long period of time.As a result, it is difficult to securely fix the track during use, etc., making this device insufficiently reliable. There was a problem where sex was difficult to obtain.

An object of the present invention is to overcome the above-mentioned drawbacks by applying a rotary thermal expansion absorption mechanism to the track holding part.

The key point of the present invention is to support the track, which was supported by a conventional sliding track thermal expansion absorption mechanism, with a rotating thermal expansion absorption mechanism, thereby reducing backlash and stably maintaining thermal expansion over a long period of time. It is possible to absorb and securely fix against dynamic external forces in any situation.

FIG. 3 shows a specific embodiment of the present invention.

This example is an example in which the method is applied to a trajectory for ultrasonic deep damage to the circumferential weld line of the lower mirror part of a reactor pressure vessel. Therefore, the main track is installed in a circular shape along the lower mirror circumference weld line.

In FIG. 3 and FIG. 4 showing details of the holding part, 3 is a pressure vessel support, 5 is a track, and both are connected by a connecting rod 8 supported by rotatable pins 9 and 10. . It is assumed that the track is supported by the holding section having such a configuration.

FIG. 5 shows the principle of the orbital thermal expansion absorption mechanism. 16 is an orbit at room temperature, and 17 is an orbit in a thermally expanded state. Thermal expansion of the orbit is caused by the connecting rod 14, which rotates around the fixing pin 9 on the pressure vessel support side.
It is absorbed by the movement of 15. When returning, the opposite is true; the center of the orbit remains constant.

In addition, when running on a track, if the track has sufficient rigidity and has three or more holding parts, the connecting rod only rotates around the pressure vessel support side pin, so the track can be Due to the rigidity, the holding parts other than the holding part that is about to move act in a direction to cancel the movement. Therefore, the trajectory is generally fixed.

In order to make the moving directions of the connecting rods coincide with each other during orbital thermal expansion, all the connecting rods are preliminarily inclined at a predetermined angle from the radial direction. Any angle is allowed as long as it is within the rotational plane of the pin joint.

This support device can support the track at the same position if the ambient temperature is the same. However, when the ambient temperature changes, such as during pre-use inspections during construction and when the plant is shut down after it has started operation,
There is a possibility that the position on the orbit and the position on the object may deviate. Therefore, the origin of the travel is not provided on the track, but is placed on the pressure vessel support and extended to the track, so that the relationship between the track and the subject can be obtained regardless of the ambient temperature.

According to the present invention, even if the lower mirror track is made into a circular track that is easy to construct and support, the thermal expansion of the track can be stably absorbed for many years, and it is securely fixed at any time, including when traveling. This increases the strength against external forces such as earthquakes.

[Brief explanation of the drawing]

Fig. 1 is an overall view of the reactor pressure vessel, Fig. 2 is a diagram of a conventional track holding structure, Fig. 3 is a drawing of a track holding structure according to the present invention, Fig. 4 is a detailed view of a track holding part according to the present invention, and Fig. 5 is a diagram of the principle of orbit maintenance according to the present invention. 1... Reactor pressure vessel, 2... Reactor pressure vessel lower mirror, 3... Reactor pressure vessel support, 4... Circumferential welding line, 5... Circumferential orbit, 8... Connecting rod, 9, 10
...Rotating pin.

Claims (1)

[Claims] 1 A circumferential orbit installed near the surface of the lower mirror corresponding to the circumferential welding line of the lower mirror of the reactor pressure vessel, with a predetermined interval and a predetermined inclination with respect to the radial direction of the circumferential orbit. A track for a monitoring or inspection device for a lower mirror of a nuclear reactor pressure vessel, characterized in that it is pin-connected to a reactor pressure vessel support body by a plurality of connecting rods arranged in a holding manner.