An on-line non-destructive testing device for fuel rod seal weld tungsten inclusions

Abstract

The application discloses an online nondestructive testing device for a fuel rod sealing welding point tungsten inclusion, and at least comprises an X-ray tube, a detector and an analysis processing unit, X-rays emitted by the X-ray tube irradiate a fuel rod sealing welding point to be detected to excite tungsten elements in the sealing welding point; characteristic X-ray fluorescence is generated in a de-excitation process of the excited tungsten elements, and energy spectrum measurement of the characteristic X-ray fluorescence is completed by the detector; the energy spectrum of the characteristic X-ray fluorescence is processed by the analysis processing unit, tungsten atomic Kalpha characteristic X-ray fluorescence net peak count is extracted, and qualitative and quantitative analysis of tungsten element content in the fuel rod sealing welding point to be detected is realized based on standard rod database information. Through the online nondestructive testing device, nondestructive and efficient detection of the fuel rod sealing welding point inclusion tungsten is realized. Moreover, through measurement of Kalpha rays, since the energy is high, the detection depth can reach >0.5mm.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of non-destructive monitoring, and particularly relates to an online non-destructive detection device for tungsten inclusions in a fuel rod sealing weld point. BACKGROUND

[0002] Tungsten inclusion detection in a fuel rod sealing weld point is of great significance to nuclear safety of a fuel cladding. Since the reaction cross section of tungsten with neutrons is much larger than that of other elements in the weld point, tungsten inclusions in the weld point will form fuel rod end plug corrosion during reactor operation, leading to fuel leakage and affecting the safety of the reactor. Therefore, online non-destructive detection of tungsten inclusions in a fuel rod is a key process in the production process of the fuel rod. The detection of the fuel rod requires non-contact and non-destructive measurement to avoid new safety hazards to the fuel rod.

[0003] Energy dispersive X-ray fluorescence analysis technology (EDXRF) has the characteristics of on-site, rapid, non-destructive, multi-element, high accuracy, etc., and is therefore very suitable for application in the detection of tungsten inclusions in the fuel rod sealing weld point.

[0004] At present, researchers at home and abroad use EDXRF to quantitatively analyze heavy elements (atomic number greater than 50), and mostly use L-series characteristic X fluorescence for qualitative and quantitative analysis. Compared with K-series rays, the fluorescence yield of L-series rays is low, and the attenuation of L-series rays in the material is faster, so the detection depth of L-series rays is small, and there is no measurement capability for W elements dispersed in the plug, which reduces the detection capability of tungsten inclusions in the fuel rod sealing weld point.

[0005] Therefore, there is an urgent need for an efficient non-destructive detection device. SUMMARY

[0006] The purpose of the present application is to overcome the problem of tungsten near-surface tungsten impurity detection in a fuel plug, and a device for online non-destructive detection of tungsten inclusions in a fuel rod sealing weld point is disclosed, which realizes efficient non-destructive detection of tungsten inclusions in a fuel rod sealing weld point.

[0007] The purpose of the present application is achieved by the following technical solutions:

[0008] The device for online non-destructive detection of tungsten inclusions in a fuel rod sealing weld point comprises at least an X-ray tube, a detector and an analysis processing unit. The X-ray tube emits X-rays to irradiate the fuel rod sealing weld point to be detected, exciting the tungsten element in the sealing weld point. The excited tungsten element generates characteristic X-ray fluorescence during the de-excitation process, and the detector completes energy spectrum measurement of the characteristic X-ray fluorescence. The analysis processing unit processes the energy spectrum of the characteristic X fluorescence, extracts the net peak count of the tungsten atomic K α series characteristic X-ray fluorescence, and realizes qualitative and quantitative analysis of the tungsten element content in the fuel rod sealing weld point to be detected based on the standard rod database information.

[0009] According to a preferred embodiment, the standard rod database comprises: the data of the relationship between the characteristic X-ray fluorescence net peak count of the tungsten element and the tungsten element content, which is established by the measurement of the reference rod with known tungsten element content. α

[0010] According to a preferred embodiment, the detector comprises: an L series detector for measuring the L series ray of the tungsten element, and the characterization of the tungsten element content in the surface layer of the fuel rod sealing weld is completed by the measured L series ray count of the tungsten element; and a K series detector for measuring the K series ray of the tungsten element, and the characterization of the tungsten element content in the near-surface layer of the fuel rod sealing weld is completed by the measured K series ray count of the tungsten element.

[0011] According to a preferred embodiment, the L series detector also measures the energy spectrum of the K series characteristic X-ray of the zirconium element in the fuel rod sealing weld after the X-ray tube irradiation, and the X-ray tube beam stability evaluation is completed by the analysis processing unit through the measured net count rate of the K characteristic X-ray of the zirconium element.

[0012] According to a preferred embodiment, the L series detector is a Si-PIN detector; and the K series detector is a CdTe detector.

[0013] According to a preferred embodiment, the surface layer depth of the fuel rod sealing weld is ≤0.05mm; and the near-surface layer depth of the fuel rod sealing weld is ≤0.5mm.

[0014] According to a preferred embodiment, a collimator is arranged between the X-ray tube and the fuel rod to be measured; and an X-ray shutter is arranged on the X-ray passage path in the collimator.

[0015] According to a preferred embodiment, the collimator is provided with a first mounting slot hole and a second mounting slot hole for respectively mounting the L series detector and the K series detector, the L series detector and the K series detector are respectively mounted in the first mounting slot hole and the second mounting slot hole, and the first mounting slot hole and the second mounting slot hole are symmetrically arranged on both sides of the collimator, and the first mounting slot hole and / or the second mounting slot hole are arranged at a 45° angle with the light path of the X-ray tube in the collimator.

[0016] According to a preferred embodiment, an L series filter is arranged between the L series detector and the fuel rod to be measured, a K series filter is arranged between the K series detector and the fuel rod to be measured, and a primary ray filter is arranged between the X-ray tube and the fuel rod to be measured.

[0017] According to a preferred embodiment, the tube voltage of the X-ray tube is 80kV-160kV, and the target material is a rhodium target.

[0018] ​The foregoing main scheme of the present application and each further selected scheme thereof can be freely combined to form multiple schemes, all of which are the schemes that can be adopted and claimed by the present application. Those skilled in the art can understand that there are multiple combinations according to the prior art and common knowledge after understanding the schemes of the present application, all of which are the technical schemes claimed by the present application, and are not listed here.

[0019] Advantages of the present application:

[0020] Through the structural design of the online nondestructive testing device of the present application, the K series and L series characteristic fluorescence of the elements in the fuel rod weld point is detected by using the existing high-energy X-ray tube 130kV-160kV and semiconductor detector, and the detection capability of tungsten inclusions in the fuel rod weld point is improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic diagram of the principle structure of the online nondestructive testing device of the present application;

[0022] Figure 2 is a schematic diagram of the shutter structure of the online nondestructive testing device of the present application;

[0023] Figure 3 is a schematic diagram of the cross-sectional structure of the collimator of the online nondestructive testing device of the present application;

[0024] Figure 4 is a schematic diagram of the three-dimensional structure of the collimator of the online nondestructive testing device of the present application;

[0025] Among them, 1-collimator, 2-L series detector, 3-k series detector, 4-K series filter, 5-L series filter, 6-primary ray filter, 7-feeding channel, 8-collimator fixer, 9-X-ray tube, 10-fuel rod, 11-X-ray shutter, 12-shielding layer. DETAILED DESCRIPTION

[0026] The embodiments of the present application are described below through specific concrete examples, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the present specification. The present application can also be implemented or applied through other different specific embodiments, and each detail in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following examples and features in the examples can be combined with each other without conflict.

[0027] It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0028] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed during use, and are merely for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0029] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components must be absolutely horizontal or overhanging, but can be slightly inclined. For example, "horizontal" only means that it is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0030] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "arrangement", "installation", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0031] In addition, the present application points out that in the present application, if the specific structures, connection relationships, positional relationships, power source relationships and the like are not specifically written, the structures, connection relationships, positional relationships, power source relationships and the like involved in the present application can be known by those skilled in the art on the basis of the prior art without creative labor.

[0032] Reference Figure 1 As shown in the figure, the device for on-line nondestructive testing of tungsten inclusions in fuel rod sealing welds includes an X-ray tube 9, a detector, an analysis and processing unit and a shielding layer 12. The X-ray tube 9 and the detector are arranged inside the shielding layer 12, and the analysis and processing unit is arranged outside the shielding layer 12. The tube voltage of the X-ray tube 9 is 0kV-160kV, and the target material is rhodium target. The commonly used X-ray tube with a voltage of 80Kv or more commonly uses tungsten as the target material, and the characteristic X-rays generated by the target material enter the detector through sample coherent scattering, increasing the measurement interference of the tungsten element, and the selection of rhodium target avoids this interference.

[0033] The X-ray tube 9 emits X-rays to irradiate the sealed weld of the fuel rod 10 to be measured, and excite the tungsten element in the sealed weld; the excited tungsten element generates characteristic X-ray fluorescence during de-excitation, and the energy spectrum of the characteristic X-ray fluorescence is measured by the detector; the energy spectrum of the characteristic X-ray fluorescence is processed by the analysis processing unit, and the K α characteristic X-ray fluorescence net peak count of the tungsten atom is extracted, and the content of the tungsten element in the sealed weld of the fuel rod 10 to be measured is qualitatively and quantitatively analyzed based on the standard rod database information.

[0034] The standard rod database includes the relationship data between the K α characteristic X-ray fluorescence net peak count of the tungsten atom and the content of the tungsten element, which is established by measuring the reference rod with a known content of the tungsten element. Further, the standard rod database is composed of the detection results of standard rods with different contents of the tungsten element, and gives a count threshold for judging the presence of the tungsten element in the qualitative analysis, and gives a detection sensitivity in the quantitative analysis. For example, the standard rods are selected to be zirconium alloys with the contents of the tungsten element being 100 ppm, 320 ppm and 770 ppm.

[0035] Preferably, the detector includes an L-series detector 2 for measuring the L-series rays of the tungsten element, and a K-series detector 3 for measuring the K-series rays of the tungsten element.

[0036] The L-series detector 2 measures the content of the tungsten element in the surface layer (surface layer depth ≤ 0.05 mm) of the sealed weld of the fuel rod 10 by measuring the L-series ray count of the tungsten element. The K-series detector measures the content of the tungsten element in the near-surface layer (near-surface layer depth ≤ 0.5 mm) of the sealed weld of the fuel rod 10 by measuring the K-series ray count of the tungsten element.

[0037] Further, the L-series detector 2 also measures the energy spectrum of the K-series characteristic X-ray of the zirconium element in the sealed weld of the fuel rod 10 generated after de-excitation under the irradiation of the X-ray tube 9, and the analysis processing unit evaluates the beam stability of the X-ray tube 9 by measuring the net count rate of the K-series characteristic X-ray of the zirconium element. Thus, the L-series detector 2 and the K-series detector 3 can accurately measure the content of the tungsten element in the sealed weld of the fuel rod 10 to be measured.

[0038] Under the condition of high voltage stability, the beam intensity of the X-ray tube is affected by the fluctuation of the filament current of the X-ray tube. Assuming that the energy spectrum distribution of the X-ray tube is f(E), and the beam intensity of the X-ray tube is I0, the measurement count of the zirconium element is:

[0039]

[0040] For the same X-ray tube, f(E) is a certain stable energy spectrum distribution under the same high voltage, so the above The integral result is a constant, K iis a constant; Ω is the geometric solid angle of the detector, also a constant. Therefore N Zr is a function of I0 and C Zr . In the fuel rod cladding, the content of zirconium element is greater than 99%, which can be considered as a constant, so the count rate of W can be corrected by measuring the count. The working mode is as follows: in the instrument calibration stage, the count rate of the characteristic peak of zirconium element is counted to obtain the average value of the count rate N zr, , and the count rate correction formula of the characteristic peak of tungsten element is:

[0041]

[0042] N w,m and N zr, are the count rates of the characteristic peaks of tungsten element and zirconium element, respectively.

[0043] Preferably, the L-series detector 2 is a Si-PIN detector; and the K-series detector is a CdTe detector.

[0044] Preferably, a collimator 1 is arranged between the X-ray tube 9 and the fuel rod 10 to be measured; the collimator 1 is made of lead and used for collimating the primary X-rays and the secondary X-rays. The purpose of reducing the X-ray irradiation of the focus of the sealing weld of the fuel rod and reducing the X-ray scattering around is achieved.

[0045] An X-ray shutter 11 is arranged on the X-ray passage path in the collimator 1. The X-ray irradiation control is realized by the X-ray shutter 11.

[0046] Preferably, the collimator 1 is provided with a first mounting slot hole and a second mounting slot hole for mounting the L-series detector 2 and the K-series detector, respectively; the L-series detector 2 and the K-series detector are mounted in the first mounting slot hole and the second mounting slot hole, respectively, and face the fuel rod 10 to be measured; the first mounting slot hole and the second mounting slot hole are symmetrically arranged on both sides of the collimator 1, and the first mounting slot hole and / or the second mounting slot hole are arranged at an angle of 45° with the light path of the X-ray tube 9 in the collimator 1.

[0047] By arranging the detector mounting slot, the peripheral scattered rays can be prevented from entering the detector, and the influence of the peripheral scattering on the detection result is reduced.

[0048] Further, an L-series filter 5 is arranged between the L-series detector 2 and the fuel rod 10 to be measured; a K-series filter 4 is arranged between the K-series detector and the fuel rod 10 to be measured; and a primary ray filter 6 is arranged between the X-ray tube 9 and the fuel rod 10 to be measured. By arranging the filters, the low-energy photons are filtered out, so that the peak-to-background ratio when detecting the characteristic X-rays is improved, and the measurement accuracy is increased.

[0049] In a specific application case:

[0050] Reference Figures 1 to 3 The fuel rod 10 to be measured is sent into the inside of the shielding layer 12 through the feeding channel 7. The inner end face of the feeding channel 7 is provided with a large slope capable of abutting against the end plug of the fuel rod, so that the welding point of the fuel rod is kept in a fixed detection station during each detection.

[0051] The X-ray tube 9 is selected according to the production line transmission rate, the input count rate of the detector and other considerations, and the working parameters are as follows: the voltage of the X-ray tube is 150 kV, the current of the X-ray tube is 0.4 mA, and the measurement time is 25 s. The thickness of the shielding layer 12 is 2 mm.

[0052] The K filter 4 and the L filter 5 are respectively placed at the bottom of the first mounting slot hole and the second mounting slot hole. The K filter 4 is an Al sheet with a thickness of 0.2 mm; the L filter 5 is an Al sheet with a thickness of 0.4 mm; and the primary ray filter 6 is a Cu sheet with a thickness of 1 mm.

[0053] The X-ray shutter 11 closes the transmission of the primary X-ray under power-off and opens the transmission of the primary X-ray under power-on. The X-ray shutter is composed of an electromagnetic lock and a lead shielding rod. The shielding rod is inserted into the shielding slot of the collimator under power-off and is separated from the shielding slot under power-on, so as to ensure the safe use of the X-ray.

[0054] The X fluorescence spectrum is processed by the analysis processing unit, accurate characteristic X fluorescence information is extracted, and qualitative and quantitative analysis of the tungsten element in the welding point to be detected is realized based on the standard rod database.

[0055] The above only describes the preferred embodiments of the present application and should not be used to limit the present application. Any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An online non-destructive testing device for tungsten inclusions at fuel rod sealing weld points, characterized in that, The online non-destructive testing device includes at least: an X-ray tube (9), a detector, and an analysis and processing unit. The X-rays emitted by the X-ray tube (9) irradiate the sealing weld of the fuel rod under test, exciting the tungsten element in the sealing weld; The de-excitation process of excited tungsten generates characteristic X-ray fluorescence, and the energy spectrum measurement of the characteristic X-ray fluorescence is performed by the detector. The energy spectrum of the characteristic X-ray fluorescence is processed by the analysis and processing unit to extract tungsten atoms (K). α The system uses characteristic X-ray fluorescence net peak counting and, based on standard rod database information, enables qualitative and quantitative analysis of tungsten content in the weld joints of the fuel rods to be tested. The detector includes: An L-series detector is used to measure L-series rays of tungsten; the tungsten content on the surface of the sealing weld of the fuel rod (10) is characterized by counting the L-series rays of tungsten. A K-series detector is used to measure the K-series rays of tungsten. The tungsten content near the surface of the sealing weld of the fuel rod (10) is characterized by the K-series ray count of the tungsten element. The L-series detector also measures the energy spectrum of K-series characteristic X-rays generated by the de-excitation of zirconium in the sealed weld of the fuel rod (10) after irradiation by the X-ray tube (9). The analysis and processing unit then assesses the X-ray tube beam stability using the measured net count rate of the zirconium K-characteristic X-rays. The L-series detector is a Si-PIN detector; the K-series detector is a CdTe detector.

2. The online non-destructive testing device as described in claim 1, characterized in that, The standard rod database includes: a database of tungsten element K established by measuring reference rods with known tungsten element content. α Data on the relationship between the net peak count of characteristic X-ray fluorescence and the tungsten content.

3. The online non-destructive testing device as described in claim 1, characterized in that, The surface depth of the sealing weld point of the fuel rod (10) is ≤0.05mm; the near-surface depth of the sealing weld point of the fuel rod is ≤0.5mm.

4. The online non-destructive testing device as described in claim 1, characterized in that, A collimator (1) is provided between the X-ray tube (9) and the fuel rod (10) to be tested; an X-ray shutter (11) is provided on the X-ray path inside the collimator (1).

5. The online non-destructive testing device as described in claim 4, characterized in that, The collimator (1) is provided with a first mounting slot and a second mounting slot for mounting the L-series detector (2) and the K-series detector (3) respectively. The L-series detector (2) and the K-series detector (3) are respectively installed in the first mounting slot and the second mounting slot, and are oriented towards the fuel rod (10) to be tested. The first mounting slot and the second mounting slot are symmetrically arranged on both sides of the collimator (1), and the first mounting slot and / or the second mounting slot are arranged at a 45° angle with the optical path of the X-ray tube (9) in the collimator (1).

6. The online non-destructive testing device as described in claim 5, characterized in that, An L-series filter (5) is provided between the L-series detector (2) and the fuel rod (10) to be tested, a K-series filter (4) is provided between the K-series detector (3) and the fuel rod (10) to be tested, and a primary X-ray filter (6) is provided between the X-ray tube (9) and the fuel rod (10) to be tested.

7. The online non-destructive testing device as described in claim 1, characterized in that, The X-ray tube (9) has a tube voltage of 80kV-160kV and a target material of rhodium.

Images