JPH06109666A - X-ray diffraction probe - Google Patents

Abstract

PURPOSE:To make X-ray diffraction measurement possible even in a spatially small place by integrating an X-ray source, an X-ray guide means and an X-ray detector into a radioactive ray shielding hollow container equipped with an X-ray transmitting window at an intermediate part in a lengthwise direction. CONSTITUTION:An X-ray source 3 for emitting X-rays which are incident to a region to be measured at a predetermined incident angle is provided at an end of a lengthwise direction of a probe body 1, while an X-ray detector 8 is provided on the other end so that they are integrated into a hollow container. The X-ray source 3 emits electrons from an electron gun 6 connected to a high voltage cable 6 in a vacuum chamber 4, and the electrons are made to collide against a predetermined target 7 to have X-rays generated. The X-rays pass through a Be window 9 and while being led by a glass-made X-ray guide tube 10 pass through a window 2 to be emitted to a region to be measured, and diffraction X-rays which have been diffracted are detected by the X-ray detector 8. Thus an X-ray diffraction probe with the X-ray source 3 and the X-ray detector 8 integrated allows X-ray diffraction to be performed even in a spatially small place such as an inner face of a thin tube.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray diffraction probe, and in particular, the physical properties associated with fatigue of a measurement material in a narrow space such as the inside of a metal circular tube are detected by X-ray diffraction measurement to determine fatigue damage. The present invention relates to an X-ray diffraction probe for performing evaluation.

[0002]

2. Description of the Related Art Nondestructive inspection is an inspection method for evaluating the soundness of materials and structures such as material, strength, and shape without destroying them by utilizing their physical properties. Has been converted. For example, there are the following inspection methods.

1. Radiation flaw detection: When a crack like a cavity exists in an object, the radiation (X
Rays, γ rays, etc.) and the radiation that has passed through the sound area have a difference in intensity, so a radiation sensitive film is placed behind the inspection body and the shape of the crack is photographed on a video photographic film. And examine the soundness of the test material.

2. Ultrasonic flaw detection (a) Pulse reflection method: An extremely short ultrasonic pulse is injected into the test material, and the echo reflected by a crack in the test material is received to know the position, size, etc. (b) Transmission method: A continuous wave or pulsed high frequency drive voltage is applied to the transmitting probe, and the ultrasonic wave transmitted through the test material is converted into a high frequency voltage again by the receiving probe and observed. (c) Resonance method: A driving voltage whose frequency changes continuously is applied to the ultrasonic probe, and a standing wave resonating with the thickness of the test material is measured to measure the thickness of the test material.

3. Eddy current flaw detection: Detects cracks based on the relationship between the strength of the AC magnetic field generated from the coil and the eddy current generation distribution state. Incidentally, the detection sensitivity is generally lower than the ultrasonic method, but since it is good for specific cracks,
Used as an auxiliary means for ultrasonic examination.

4. Penetrant flaw detection: A defect is detected using a penetrant that has high transparency and emits color or fluorescence. Generally, it is effective for inspecting surface cracks of materials.

By the way, because of the flaw detection of a thin tube of a steam generator of a nuclear power plant, there is a conventional inspection probe using eddy current or ultrasonic waves as a means for inspecting the damage after the generation. It was not perfect because it did not reach well and eddy currents were difficult to flow depending on the shape of the scratch. Further, these are only for inspecting the scratches that have occurred, and it was not possible to detect changes in the physical properties leading to the scratches before they occurred.

Generally, most of the period until the material undergoes fatigue fracture is occupied by a microscopic relationship at the crystal lattice level before crack initiation.

[0009]

Therefore, the test material is irradiated with X-rays to obtain the X-ray diffraction intensity at a predetermined diffraction angle, and the similar X-ray diffraction intensity and the predetermined stress action time which are previously determined separately. An evaluation method for evaluating fatigue damage of a test material such as a metal before cracking was proposed by collating it with comparison data with the X-ray diffraction intensity of the diffraction angle of the test material later (Japanese Patent Application No. 4-47710).

However, since the conventional X-ray diffractometer is mainly used at the laboratory level, its size and weight are large and it is difficult to apply it to an actual plant. In addition, the X-ray generator and the diffracted X-ray detector are separately prepared, and the X-ray diffractometer of the field application type is also partially commercialized. It is quite large and cannot be measured in a narrow space, and it is also unsuitable for measurement in an environment where radiation is present, such as plant equipment of a nuclear power plant.

That is, although X-ray diffraction is widely used for analyzing substances, evaluating the strength of materials, etc., the conventional X-ray diffraction measuring system has a large size, so it is impossible to measure in a narrow space of the actual machine structure. It was also unsuitable for measurements in the presence of radiation.

Therefore, an object of the present invention is to obtain an X-ray diffraction probe that enables X-ray diffraction measurement in a space-constrained place such as in a narrow tube even in the presence of radiation.

[0013]

In an X-ray diffraction probe according to the present invention, there is provided a radiation shielding hollow container having an X-ray transmission window at an intermediate portion in the longitudinal direction for defining an area to be measured, and the hollow container. X provided at one longitudinal end in the container
A radiation source, X-ray guide means for guiding the X-rays from the X-ray source to the window from the X-ray source so that the X-rays from the X-ray source are incident on the measured region at a predetermined incident angle; And an X-ray detector for detecting diffracted X-rays generated from the measured region through the window.

[0014]

According to the present invention, there is provided a radiation shielding hollow container having an X-ray transmission window provided at an intermediate portion in the longitudinal direction for defining an area to be measured, and the radiation shielding hollow container is provided at one end in the longitudinal direction in the hollow container. An X-ray source; an X-ray guide means for guiding the X-rays from the X-ray source to the measurement area at a predetermined incident angle from the X-ray source to the window; An X-ray detector which is provided at the other end in the longitudinal direction and detects diffracted X-rays generated from the measured region through the window.

That is, an X-ray inspection is conventionally performed by an X-ray diffraction probe in which an X-ray source and an X-ray detector are integrated in a radiation shielding hollow container provided with an X-ray transmission window at an intermediate portion in the longitudinal direction. Even in a narrow space, such as the inner surface of a thin tube, which was impossible.
X-ray diffraction measurement can be performed even in the presence of radiation.

Therefore, the test material was irradiated with X-rays to obtain the X-ray diffraction intensity at a predetermined diffraction angle, and the similar X-ray diffraction intensity previously determined separately and the test material after the predetermined stress action time were obtained. By comparing with the comparison data of the diffraction angle with the X-ray diffraction intensity, it is possible to evaluate the fatigue damage of the test material such as metal before the crack is generated.

Therefore, it is possible to grasp the strain state of the metal lattice from the diffracted X-rays and perform an early soundness inspection before the material cracks. Moreover, it is effective for inspecting thin tubes of steam generators of nuclear power plants where radiation is present, and other parts that can be inspected only by a small probe.

Since the X-ray diffraction probe of the present invention uses the radiation shielding hollow container, it can be used not only under radiation but also as a shield against X-rays generated from the X-ray source. Become.

Further, in the X-ray diffraction probe of the present invention, X
X-ray guide means for guiding the X-rays from the X-ray source to the window so that the X-rays are incident on the measured region at a predetermined incident angle.

Specifically, this may be a simple space (passage) in which no obstacle is present between the X-ray source and the transmission window of the hollow container, and more preferably, this space (passage) is made of glass or metal. You may cover with a tube made from. In this case, the divergence of incident X-rays can be suppressed and the S / N ratio of the X-ray diffraction profile can be improved. Further, depending on the case, a desired incident angle may be obtained with an X-ray reflection mirror or the like.

As an X-ray source used, an electron beam emitted from an electron gun placed in a vacuum chamber collides with a target also placed in the vacuum chamber to generate X-rays. Any X-ray source can be used.
At this time, various characteristic X-rays or white X-rays can be obtained by selecting the target material.

X-rays generated from this target are Be
The diffracted X-rays passing through the window, reaching the surface of the sample to be measured from the hole, and generated in the sample to be measured are detected from the window to the detector. At this time, an X-ray guide means for guiding from the window to the detector may be provided in the passage from the window to the detector as described above. Thereby, the divergence of diffracted X-rays can be suppressed and the S / N ratio of the X-ray diffraction profile can be improved.

The diffraction angle θ is determined at the time of designing the probe in accordance with the diffraction surface to be measured. For example, in the case of a thin tube of a steam generator, it is advisable to capture diffracted X-rays reflected at a diffraction angle of about 20 ° in order to make the probe elongated. Diffracted X-rays have various wavelengths and diffraction angles depending on the lattice constant of the crystal lattice and the crystal plane.

Further, if the detector detects the diffracted X-rays and compares the X-ray diffraction intensity with the X-ray diffraction intensity at the diffraction angle of the test material after a predetermined stress action time. Good. In this case, a position-sensitive (one-dimensional) type detector, a point type detector, or the like may be used depending on the purpose.

This position-sensitive detector has a large number of detecting elements arranged in a one-dimensional (or two-dimensional) form and can detect diffracted X-rays in a wide range of angles at once. For this reason,
If a position-sensitive detector is used as the X-ray detector, it becomes possible to rapidly perform X-ray diffraction. As the position sensitive detector, an existing one having a size of 3 × 12 mm □ is used.

On the other hand, since the point type detector has a point shape, a rotating mechanism is required to detect an angle in a certain range. In order to reduce the size of the present X-ray diffraction probe, it is better not to provide an auxiliary mechanism such as a rotation mechanism if possible. However, the point type may be used if the material can be evaluated by detecting the diffracted X-rays at a certain angle.

[0027]

1 is a front view schematically showing the construction of an embodiment of an X-ray diffraction probe of the present invention, and FIG. 2 is a plan view of FIG. In the figure, an X-ray diffraction probe used for a thin tube T of a steam generator of a nuclear power plant is shown.

As shown in the figure, the probe main body 1 is a hollow container made of a lead tube whose both ends are closed, and a thin tube T of a steam generator.
15mmφ x 150m for the inner diameter of 20mm
It has a contour of m length. A window 2 that defines an external measured region is formed in the middle of the main body 1 in the longitudinal direction. As for the shape of the window 2, various shapes such as a round window or a square window can be used as long as the incident X-ray hits the surface of the measurement area.

An X-ray source 3 is provided at one longitudinal end of the main body 1 for generating X-rays which are incident on the measured region through the window 2 at a predetermined incident angle. The X-ray source 3 emits electrons from an electron gun 6 connected to a high-voltage cable 5 in a vacuum chamber 4, hits a predetermined target 7 and generates X-rays.

The vacuum chamber 4 can be made of glass, lead, ceramics or the like, and the inside X is most preferable for the material to be inspected.
A target 7 for generating a line is provided. The cooling water for cooling the target 7 is of a circulation type. The high voltage cable 5 is several kV to several tens of kV between the electron gun 6 and the target 7.
The voltage is applied.

Furthermore, at the other longitudinal end of the main body 1,
An X-ray detector 8 is provided. Therefore, the X-ray generated from the X-ray source 3 passes through the Be window 9 and is emitted to the measurement area through the window 2. Diffracted X-rays diffracted from the measured region pass through the window 2 and are detected by the X-ray detector 8.

The X-rays generated from the X-ray source 3 are converted into the X-ray source 3
A glass X-ray guide tube 10 that guides the X-rays diffracted from the measured region to the X-ray detector 8 is provided. Further, the lead wire 11 of the X-ray detector 8 is pulled along the side surface of the probe so as to avoid the measurement region and the like and pulled toward the operator.

A probe-like inserter 12 is provided at the tip of the probe main body 1, and a brush 13 is provided around the main body 1 to improve the insertability of the steam generator into the thin tube T and the center positioning. ing.

FIG. 3 is a front view schematically showing the construction of another embodiment of the present invention of the X-ray diffraction probe. In the drawings, the same symbols as those in the above drawings indicate the same or corresponding parts. As shown in the figure, in order to improve the X-ray generation efficiency, the X-ray source 3 ′ uses the electron gun 6 ′ connected to the high voltage cable 5 ′ in the vacuum chamber 4 ′ as the axial direction, and the excitation electron The flow is made to collide with the target 7'at a right angle.

Further, FIG. 4 is a front view schematically showing the constitution of still another embodiment of the present invention of the X-ray diffraction probe. Similarly to FIG. 3, FIG. 4 also shows the electron gun 6 ″ colliding with the target 7 ″ at a right angle in order to improve the X-ray generation efficiency.

As shown in the drawing, the direction of the electron gun 6 "connected to the high voltage cable 5" in the vacuum chamber 4 "is the axial direction,
The excited electron flow is made to collide with the target 7 ″ at a right angle. At this time, in order to make the incident angle on the measured region a desired incident angle, the X-ray mirror 14 makes a desired incident angle.

As a result, the arrangement around the electron gun 6 "is easier than that of the probe shown in Fig. 3. The X-ray mirror 14 and the X-ray detector 8 are movable and the object to be measured. It is also possible to set a predetermined incident angle and a predetermined diffraction angle according to the diffractive surface.

Using the X-ray diffraction probe as described above,
The test material is irradiated with X-rays to obtain the X-ray diffraction intensity at a predetermined diffraction angle, and the X-ray diffraction intensity of the test material after the predetermined X-ray diffraction intensity and the predetermined stress action time are obtained separately. By comparing with the comparison data with the line diffraction intensity, it is possible to evaluate the fatigue damage of the test material such as metal before the crack is generated.

The specific operation is as follows. 1. An X-ray diffraction peak having a predetermined diffraction angle at a certain stress application time (number of times of fatigue, usage time, etc.) is measured for a test material to be subjected to fatigue damage evaluation.

2. The intensity (peak height or peak area) of the obtained X-ray diffraction peak is measured, and the value is plotted against the stress action time.

3. By repeating the above 1 and 2,
A curve (fatigue damage curve) representing the relationship between the stress action time and the X-ray diffraction intensity is obtained, and the fatigue damage degree can be grasped based on this fatigue damage curve.

4. For example, the following methods can be used to evaluate the degree of fatigue damage. (a) As the fatigue damage degree evaluation, the X-ray diffraction intensities measured at the stress action time (for example, the number of times of fatigue) N _A , N _B are I _A , I
_{Let's call} it _B. (b) Here, the change rate (ΔI / ΔN) of the X-ray diffraction intensity with respect to the stress action time is as follows. Regarding the interval (ΔN) at which the fatigue damage evaluation is performed, the necessary interval is determined from the fatigue damage curve obtained in advance. (ΔI / ΔN) = (I B -I A) / (N B -N A) (c) The change rate, duration of action showing the example minimum strength N _C
Negative Previously, 0 the action time N _C indicating the minimum intensity becomes positive in action time N _C after showing the minimum intensity. (d) Therefore, by judging whether the rate of change (ΔI / ΔN) is positive or negative, it is possible to know which region of the fatigue damage curve is present, and from this fatigue damage curve, the remaining life until the stress action time N _f at fatigue fracture is reached. (Fatigue damage degree) can be obtained.

5. This fatigue damage curve is
Although it depends on the workability and fatigue conditions, if the fatigue damage curve is standardized in advance under the required fatigue conditions, the material, workability, fatigue condition, etc. of the test material will be based on this standardized fatigue damage curve. The fatigue damage degree and fatigue life expectancy at the time of the test may be required for different cases. That is, for example, if necessary, by using a ratio obtained by dividing the stress action time by the stress action time at the time of fatigue failure or a ratio obtained by dividing the X-ray diffraction intensity on the vertical axis by the initial value of the X-ray diffraction intensity, The fatigue damage curve can be represented by a single curve even when the values are different.

As described above, with the X-ray diffraction probe in which the X-ray source and the X-ray detector are integrated, the X-ray diffraction can be performed even in a spatially narrow place such as the inner surface of a thin tube where the conventional X-ray inspection was impossible. Can be carried out.

[0045]

As described above, the present invention is an X-ray diffraction probe in which an X-ray source and an X-ray detector are integrated in a radiation shielding hollow container provided with an X-ray transmission window at an intermediate portion in the longitudinal direction. Therefore, even in a spatially narrow place such as the inner surface of a thin tube where X-ray inspection has not been possible conventionally, or even in the presence of radiation, X
It becomes possible to carry out a line diffraction measurement.

Therefore, the test material was irradiated with X-rays to obtain the X-ray diffraction intensity at a predetermined diffraction angle, and the similar X-ray diffraction intensity previously determined separately and the test material after the predetermined stress action time were obtained. By comparing with the comparison data of the diffraction angle with the X-ray diffraction intensity, it is possible to evaluate the fatigue damage of the test material such as metal before the crack is generated.

Therefore, the strain state of the metal lattice can be grasped from the diffracted X-rays, and an early soundness inspection can be performed before the material cracks. Moreover, it is effective for inspecting thin tubes of steam generators of nuclear power plants where radiation is present, and other parts that can be inspected only by a small probe.

[Brief description of drawings]

FIG. 1 is a front view schematically showing the configuration of an example of an X-ray diffraction probe of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a front view schematically showing the configuration of another embodiment of the X-ray diffraction probe of the present invention.

FIG. 4 is a front view schematically showing the configuration of still another embodiment of the X-ray diffraction probe of the present invention.

[Explanation of symbols]

 1 ... Probe body, 2 ... Window, 3, 3 ', 3 "... X-ray source, 4, 4', 4" ... Vacuum chamber, 5, 5 ', 5 "... High-voltage cable, 6, 6', 6" ... Electron gun, 7, 7 ', 7 "... Target, 8 ... X-ray detector, 9 ... Be window, 10 ... X-ray guide tube, 11 ... Lead wire, 12 ... Insertor, 13 ... Brush, 14 ... X Line mirror,

Claims (1)

[Claims] 1. A radiation shielding hollow container provided with an X-ray transmission window at an intermediate portion in the longitudinal direction for defining an area to be measured to the outside, and an X-ray provided at one longitudinal end in the hollow container. Source and X for guiding the X-ray from the X-ray source from the X-ray source to the window so that the X-ray from the X-ray source is incident on the measured region at a predetermined incident angle.
An X-ray, comprising: a ray guide means; and an X-ray detector which is provided at the other end of the hollow container in the longitudinal direction and detects the diffracted X-ray generated from the measured region through the window. Diffraction probe.