JPH01147313A - Method for measuring internal diameter and shape of tube - Google Patents

Abstract

PURPOSE:To measure the internal diameter and internal surface shape of the tube at the same time and at a high speed with high accuracy by rotating a measurement head where a radius measurement sensor is fitted in the tube to be measured and measuring the angle of rotation and the internal diameter of the tube at this time. CONSTITUTION:The measurement head 32 where the radius measurement sensor 34 is fitted is inserted into the tube 10 to be measured which is placed in radiation environment. The rotary shaft 30 of the measurement head 32 is held by a rotary bearing part 28 which is positioned in the center of the tube 10 to be measured. Then while this rotary bearing part 28 is held stationary, the measurement head 32 is rotated to measure the angle thetan of rotation and the detected value rn of the measurement sensor 34 at the time. The internal diameter size of the tube 10 to be measured and the circumferential internal shape are found according to the measured values.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention measures the radius of the tube and its time by rotating the measuring head while holding the rotation axis of the measuring head at the center of the tube to be measured (the tube to be measured). This invention relates to a method of measuring the inner diameter and circumferential inner surface shape of a tube by sequentially measuring the rotation angle of the tube.

Although the present invention is not particularly limited, it is an extremely effective method, for example, when measuring the inner diameter size and inner surface shape of a pressure tube in a pressure tube nuclear reactor by remote control.

[Prior Art] There are various technical fields in which it is desired to measure the inner diameter dimension and circumferential inner surface shape of a pipe. Typical examples include measurements of pressure tubes in pressure tube nuclear reactors, as well as measurements of heat exchanger tubes.

Hereinafter, a case of measuring the inner diameter dimension and circumferential inner surface shape of a pressure tube in a pressure tube nuclear reactor, which is a typical example, will be described.

The pressure tubes that make up the core of pressure tube reactors are extremely important equipment. This pressure tube is irradiated with neutrons during the operation of the nuclear reactor, and the cooling water flowing inside it is in a high temperature and high pressure state, so its inner diameter gradually changes over time. Therefore, during the operating period of the nuclear reactor, internal diameter measurements are carried out to measure the amount of creep under irradiation.

When measuring this inner diameter, it was important to note that the inside of the pressure tube is under a high radiation environment, and that the pressure tube has an inner diameter of approximately 118+m-, and is a long tube of approximately 10m including the extension tubes attached to both ends. Because of this, a remote-controlled measuring device is inserted into the pressure pipe.6 Normally, this measurement takes about two years to
The plan is to conduct this every four years when the reactor is shut down.

The conventional inner diameter measurement method uses a pair (two) radius measurement sensors installed 180 degrees symmetrically, two fixed guide balls spaced 120 degrees apart, and one guide ball movable using a spring or the like. Using a measuring head that is integrated with a three-point support holding mechanism that is designed to be pushed outward in the radial direction, the measuring head is inserted into the inside of the pressure tube and moved in the axial direction while rotating to measure the inner diameter dimension. were being measured. As the inner diameter measurement sensor, a non-contact type ultrasonic sensor, a contact type differential transformer, etc. are used.

[Problems to be Solved by the Invention] However, in such a measuring method, since the measuring head is supported by three balls protruding from its outer peripheral surface,
The measuring head follows changes in the inner diameter of the tube. For this reason, the rotational center position of the measuring head changes from moment to moment, and since the position cannot be known, the inner circumferential shape cannot be known. In particular, the inner circumferential shape of the pressure tube is considerably deformed from a perfect circle. In this case, not only the inner shape cannot be measured, but also the inner diameter cannot be measured accurately.

Furthermore, in the conventional technology described above, the inner diameter measurement sensor and the holding mechanism are integrated into the measuring head, so when the measuring head is rotated at high speed, the unevenness of the inner surface of the tube to be measured causes vibrations, resulting in measurement errors. There was also a downside to being large. For this reason, the rotational speed of the measurement head is limited to a certain value or less, and there is also the problem that high-speed measurement cannot be performed.

It is an object of the present invention to overcome the above-mentioned drawbacks of the prior art, to enable simultaneous measurement of the inner circumferential shape of the tube when measuring the inner diameter of the tube by remote control, and to perform this measurement at high speed and at the same time. An object of the present invention is to provide a method for accurately measuring the inner diameter and shape of a pipe.

[Means for Solving the Problems] The present invention, which can achieve the above-mentioned objects, is characterized in that the rotation axis of the measurement head to which the radius measurement sensor is attached is held by a rotation bearing section located at the center of the pipe to be measured. and rotating the measuring head with its rotation bearing stationary,
This is a method for measuring the inner diameter and shape of a tube in which the inner diameter and circumferential inner shape of the tube are determined by sequentially measuring the radius of the tube and the rotation angle at that time.

Only one radius measuring sensor needs to be attached to the measuring head, and a non-contact type capable of high-speed detection operation, such as an ultrasonic sensor, is preferable.

[Function] In the present invention, in the measurement of one circumferential inner surface shape, the central axis of the measuring head is held at the center of the tube to be measured by the rotary bearing, and does not wobble in the radial direction. In addition, in order to measure the radial dimension and rotation angle simultaneously, a large number of measurement data are taken within one measurement plane, and these values are plotted on a two-dimensional surface to accurately determine the inner diameter and circumferential inner shape of the tube. You can ask for it.

[Example] FIG. 1 is an explanatory view showing an example of the method for measuring the inner diameter and shape of a pipe according to the present invention, and FIG. 2 is an enlarged view of the main part thereof. This embodiment is an example in which the present invention is applied to measurement of the inner diameter and circumferential inner surface shape of a pressure tube in a pressure tube nuclear reactor.

To measure the inner diameter and circumferential inner surface shape of the pressure pipe 10, as shown in FIG.
4 and fixed with a seal plug 16. Such insertion and fixation of the inner diameter/shape measuring device 12 can be easily performed by using a fuel exchanger, for example, in the case of the new type converter "Fugen" power plant.

The inner diameter/shape measuring device 12 is connected to a control device 20 by a cable 18, and measurements are performed by remote control from the control device 20.

The schematic structure of the inner diameter/shape measuring device 12 is as follows.

This device has a main body portion 24 with a vertical movement mechanism 22 so that measurements can be made at any position within the pressure tube 10. A holding mechanism 2 includes three guide balls protruding from the outer peripheral surface at 120 degree intervals near the upper end of the main body portion 24.
6 are provided in a protruding manner, and the tip of each guide ball comes into contact with the inner wall of the pressure tube 1O, so that the main body portion 24 can move up and down while being guided to the center of the pressure tube 1O. This holding mechanism, like the conventional one, is a combination of two fixed guide balls and one movable guide ball that is repelled radially outward by a spring.
It may be a point support method or the like.

Furthermore, a rotation bearing portion 28 is located at the center of the upper end portion of the main body portion 24.
is included. A rotary shaft 30 is rotatably fitted and held in the rotary bearing portion 28, and the rotary shaft 30
The measuring head 32 is held above the upper end of the main body portion 24 by this. Furthermore, a rotating shaft 30 is disposed within the upper end of the main body portion 24.
A rotational drive mechanism (not shown) for rotating is incorporated. A radius measuring sensor 34 (for example, an ultrasonic sensor) is attached to the measuring blade 32, and a rotation angle detector 36 is attached to the rotating wheel 30.

In carrying out the present invention, since the inner diameter/shape measuring device 12 is used in a high radiation environment, the measuring sensor 3
4 and the internal diameter/shape measuring device 12, it is essential to use radiation-resistant electronic components, polymer materials, and the like.

The inner diameter and shape of the pressure tube are measured as follows. First, the measuring head 32 is moved to the desired height using the vertical movement mechanism 22 and then stopped. Next, with the operation of the vertical movement mechanism 22 stopped, the measurement head 32 is rotated by the rotation drive mechanism. At this time, as shown in FIG.
4, the radius '6+'++ +rn of the pressure pipe 10 is the rotation angle θ at the position where the radius is measured by the rotation angle detector 36.

, θ1. The measurement interval in the 0 circumferential direction, where . do.

When the measurement for one cross section is completed, the measurement is paused for a moment, and during that time, move the 7-d 32 to the height to be measured next as shown by arrow A in Fig. 2, and then continue that movement. After stopping, the measurement head 32 is rotated again as shown by arrow B, and the same measurement is repeated.

The reason for stopping the vertical movement during measurement is to improve measurement accuracy. In other words, when the measuring head 32 is moved up and down during measurement, the holding mechanism 26 also moves, and since the holding mechanism 26 moves following the inner surface shape of the pressure pipe IO, the rotation axis 30 of the measuring head 32 also moves in the lateral direction. This is to avoid such movement, which causes an error in the measured value.

Radius (rO+ r, +...) using the method above.

rR) and the angle (θ., θ1...., θ,), (re + θ・)・(r+・θ1)
By plotting a set of values of .

When the amount of measured data is large, the data can be processed using a computer, or when the amount of data is small, it can be processed manually.

In this measurement method, the accuracy of the inner diameter measurement sensor, the accuracy of the rotation angle detector, and the deflection of the measurement head when it rotates directly affect the measurement accuracy, so adjust these accuracies according to the required measurement accuracy. It is important to keep it within the allowable value.

[Effects of the Invention] As described above, the present invention holds the rotation bearing part so that the rotation axis of the measuring head does not swing at the center of the pipe to be measured, and rotates the measuring head in this state to determine the radius of the pipe and the current value. Since the configuration is configured to sequentially measure the rotation angle and the rotation angle, it is possible to know the position where the inner diameter was measured, and it is possible to measure the inner circumferential shape of the tube, which could not be measured with conventional techniques. Even if the shape is significantly deformed from a perfect circle, the inner diameter can be accurately measured.

In this way, in the present invention, for one circumferential inner surface,
Since it is possible to obtain the required number of measurement data for the pipe radius and its angle, it is now possible to measure the amount of pressure pipe creep under irradiation with much greater accuracy than conventional technology, improving reactor safety and It is possible to obtain a wealth of data for improving performance and predicting remaining life.

Furthermore, in the present invention, since the rotary bearing part is kept stationary during the measurement of one inner surface shape in the circumferential direction, the measurement head does not wobble, and in particular, the measurement sensor can perform high-speed measurement such as an ultrasonic sensor. By using a device that can do this, it is possible to perform measurements with high precision even when the measurement head is rotated at high speeds, making it possible to perform measurements several tens of times faster than conventional techniques. Therefore, especially when inspecting the pressure pipes of a pressure tube type nuclear reactor, there is an advantage that the period of periodic inspection of the reactor is shortened and the operating rate is improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the method for measuring the inner diameter and shape of a pipe according to the present invention, and FIG. 2 is an enlarged partially cutaway front view of the main part thereof.
FIG. 3 is an explanatory diagram showing the measurement state. 10... Pressure pipe, 12... Inner diameter/shape measuring device, 2
2... Vertical movement mechanism, 24;... Main body part, 26...
Holding mechanism, 28... Rotating bearing part, 30... Rotating shaft,
32...Measuring head, 34...Radius measurement sensor, 3
6...Rotation angle detector. Patent applicant: Power Reactor and Nuclear Fuel Development Corporation Representative: Shigeru Miyoshi Hito Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A method for measuring the inner diameter and shape of a tube to be measured placed in a radiation environment by remote control. The measuring head is held by a bearing, and the measuring head is rotated with the rotating bearing stationary, and the radius of the tube and the rotation angle at that time are sequentially measured to obtain the inner diameter and inner circumferential shape of the tube. A method for measuring the inner diameter and shape of a pipe.