Simulated tube fabrication and method of use for nuclear reactor steam generator heat transfer tube

Abstract

The application discloses a simulation sample pipe manufacturing method and use method of a nuclear reactor steam generator heat transfer pipe, and belongs to the technical field of nuclear reactors. The manufacturing method comprises the following steps: obtaining a combined sample pipe, wherein the combined sample pipe comprises at least one straight pipe with a weld, at least one bent pipe with a weld, and at least one spiral pipe with a weld; the pipe center line of the bent pipe is a planar curve; the pipe center line of the spiral pipe is a spatial spiral curve; any pipe in the combined sample pipe has the same diameter and wall thickness as the spiral heat transfer pipe; the length and bending diameter of the bent pipe and the spiral pipe are the same; and the combined sample pipe is subjected to defect processing to obtain a simulation sample pipe. Through a systematic defect processing process, the simulation sample pipe has the pipe size, defect type and defect size being correlated with each other, the requirement of improving the precision of eddy current detection of the spiral heat transfer pipe by a probe can be met, and the cost of manufacturing the simulation sample pipe is greatly reduced.

Description

Technical Field

[0001] This application relates to the field of steam generators for nuclear reactors, and more particularly to a method for fabricating and using a simulated prototype of a heat transfer tube for a nuclear reactor steam generator. Background Technology

[0002] The spiral heat transfer tube of the steam generator is an important component of the nuclear reactor. During its service, the spiral heat transfer tube must withstand high temperature, high pressure and corrosion and wear from the medium. Its integrity is the key to ensuring the safe and reliable operation of the steam generator.

[0003] Currently, eddy current probes are used to detect defects in spiral heat transfer tubes. In order to verify the accuracy of the probe's detection data for spiral heat transfer tubes, it is necessary to simulate the weld-related defects of spiral heat transfer tubes. However, the cost of producing a 1:1 scale spiral heat transfer tube prototype with butt welds is currently too high.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main objective of this application is to provide a method for fabricating a simulated prototype of a heat transfer tube for a nuclear reactor steam generator, including: A composite sample tube is obtained, comprising at least one straight pipe with a weld, at least one bent pipe with a weld, and at least one spiral pipe with a weld; the centerline of the bent pipe is a planar curve; the centerline of the spiral pipe is a spatial spiral curve; the straight pipe, the bent pipe, and the spiral pipe all have the same diameter and wall thickness as the spiral heat transfer tube; the length and bending diameter of the bent pipe and the spiral pipe are the same; the straight pipe, the bent pipe, and the spiral pipe each include the following regions: weld region, heat-affected zone, weld fusion line region, and base material region; The combined sample tube is subjected to defect processing to obtain a simulated sample tube for eddy current testing; The defect processing procedure includes the following steps: A flat-bottomed hole defect is provided in the weld area of ​​the straight pipe; Circumferential groove defects of the same size are respectively provided in the weld fusion line area and the base material area of ​​the bend. A circumferential crack defect is provided in the weld fusion line region of the spiral tube and one or more axial crack defects are provided in the base material region; or, circumferential crack defects of the same size are provided in the weld region and heat-affected region of the spiral tube respectively.

[0006] Through the above systematic defect processing, a simulated tube with interrelationships between pipe size, defect type, and defect size is obtained, which can meet the requirements of probe for eddy current detection of spiral heat transfer tubes and greatly reduce the cost of manufacturing simulated tubes.

[0007] Preferably, the combined sample tube includes at least two spiral tubes with welds. The defect processing further includes: setting a circumferential crack defect in the weld fusion line region of the first spiral tube and setting one or more axial crack defects in the base material region; and setting a circumferential crack defect of the same size in both the weld region and the heat-affected zone of the second spiral tube. Through these settings, the differences in eddy current detection signals caused by circumferential crack defects of the same size but different weld-related regions (weld fusion line region, weld region, and heat-affected zone) can be better compared for spiral tubes, thus more accurately improving the detection accuracy of the eddy current probe for welds.

[0008] Preferably, the circumferential groove defect and the circumferential crack defect have the same length, and the width of the circumferential groove defect is greater than the width of the circumferential crack defect. With this configuration, the eddy current probe can be calibrated first using the eddy current detection signal from the circumferential groove defect on the bend, and then recalibrated using the eddy current detection signal from the circumferential crack defect on the spiral tube, thereby improving the probe's defect assessment capability for welds.

[0009] Preferably, the combined sample tube further includes at least one straight pipe without welds, and the defect processing further includes: setting multiple thinning defects of the same length and different depths at equal intervals along the centerline of the straight pipe without welds. Through this arrangement, the impact of thinning defects of different depths on the eddy current probe's detection data can be effectively compared, thereby enabling preliminary calibration of the relatively simple straight pipe without welds for eddy current testing and preliminary evaluation of the probe's performance.

[0010] Preferably, the interval is not less than 50 mm, the distance between the thinning defect and the pipe end is not less than 70 mm, and the length of the thinning defect is 22.4 to 22.6 mm and the depth is 10% to 50% of the wall thickness. These settings effectively prevent mutual interference between different defects and eddy current detection signals caused by the pipe end, thereby further improving the defect characterization accuracy of the probe.

[0011] Preferably, the flat-bottomed hole defect on the straight pipe includes a first flat-bottomed hole, the depth of which is 16% to 24% of the wall thickness, and the diameter of which is 1.52 to 1.68 mm. With the above configuration, preliminary calibration for eddy current testing can be performed on relatively simple straight pipes with welds, allowing for a preliminary evaluation of probe performance.

[0012] Preferably, the circumferential groove defect includes: A first circumferential groove is provided in the weld fusion line region of the bend, and a second circumferential groove is provided in the base material region of the bend. The depth of both the first and second circumferential grooves is 16% to 24% of the wall thickness, the length is 4.92 to 5.08 mm, and the width is 0.17 to 0.33 mm. The distance between the first and second circumferential grooves is greater than 70 mm, and both grooves are located on the same bend. With this configuration, eddy current detection signals of circumferential groove defects in the base material region and the weld fusion line region can be effectively compared for the bend.

[0013] Preferably, the circumferential crack defect located in the weld fusion line region of the spiral pipe is a first circumferential crack, with a depth of 26% to 34% of the wall thickness, a length of 4.92 to 5.08 mm, and a width of 0.04 to 0.2 mm; and, The axial crack defects set in the base material region include a first axial crack with a depth of 16% to 24% of the wall thickness, a second axial crack with a depth of 26% to 34% of the wall thickness, and a third axial crack with a depth of 36% to 44% of the wall thickness. Through this setup, on the one hand, for spiral pipes, the differences in eddy current detection signals caused by axial crack defects of the same type (i.e., axial crack defects), in the same region (i.e., the base material region), and at different depths can be compared; on the other hand, the differences in eddy current detection signals caused by defects of the same depth (meaning depth errors are all within a reasonable range, such as 30% ± 4%), in different regions (i.e., the weld fusion line region and the base material region), and of different types (i.e., circumferential crack defects and axial crack defects) can also be compared. By comparing these two methods, the eddy current probe detection signals for weld defects in spiral pipes can be utilized more comprehensively and efficiently.

[0014] Preferably, the circumferential crack defect in the weld area of ​​the spiral tube is a second circumferential crack, and the circumferential crack defect in the heat-affected zone is a third circumferential crack. The depth of both the second and third circumferential cracks is 36% to 44% of the wall thickness, and the circumferential angle interval is 160 to 200 degrees. This configuration helps to obtain the difference in eddy current detection signals between the weld area and the heat-affected zone, thus more accurately improving the detection accuracy of the eddy current probe.

[0015] Preferably, the combined sample tube further includes a third spiral tube with a weld, and the defect processing further includes: A second flat-bottomed hole, identical in size to the first flat-bottomed hole, is provided in the heat-affected zone of the third spiral tube. This arrangement allows for a better comparison of the differences in eddy current detection signals caused by defects in flat-bottomed holes of the same size in different areas of straight and spiral tubes. Furthermore, providing a second flat-bottomed hole in the heat-affected zone of the third spiral tube can more realistically simulate actual defects in spiral heat transfer tubes after a certain number of years of operation.

[0016] This application also provides a method for using a simulated prototype tube of a nuclear reactor steam generator heat transfer tube, including: Obtain a simulated sample tube prepared by any of the above-mentioned manufacturing methods; The simulated sample tube was subjected to the following testing steps using an eddy current probe: The probe is used to perform eddy current detection on the flat-bottom hole defect of the straight tube in the simulated sample tube to obtain the first calibration data; the probe is then corrected for the first time using the first calibration data. The probe is used to perform eddy current detection on the circumferential groove defect of the bend in the simulated sample tube to obtain second calibration data; the second calibration data is used to perform a second data correction on the probe. The probe is used to perform eddy current detection on the circumferential and axial crack defects of the spiral tube in the simulated sample tube to obtain third calibration data; the probe is then corrected for the third time using the third calibration data.

[0017] This application embodiment obtains a simulated sample tube with interrelated pipe size, defect type, and defect size through the above-described systematic defect processing process. This facilitates the sequential eddy current testing and probe calibration of the straight pipe, bend, and spiral pipe in the simulated sample tube, and progressively improves the weld defect detection performance of the probe to meet the requirement of improving the accuracy of the probe for eddy current testing of the spiral heat transfer tube, thereby greatly reducing the cost of manufacturing the simulated sample tube. Attached Figure Description

[0018] Figure 1 This application provides an example of a spiral heat transfer tube for a nuclear power steam generator used in actual engineering applications. Figure 2 This application provides a method for fabricating a simulated prototype of a heat transfer tube for a nuclear reactor steam generator. Figure 3 This is a simulated sample tube obtained by a method for setting a flat-bottomed hole defect in the weld area of ​​a straight pipe, as provided in the embodiments of this application. Figure 4 This is a simulated sample tube obtained by a method of setting thinning defects in the base material region of a straight tube, as provided in an embodiment of this application; Figure 5This is a simulated pipe obtained by a method provided in this application to set circumferential groove defects in the weld fusion line region and the base material region of a bend; Figure 6 This is a simulated sample tube obtained by a method provided in this application embodiment of setting a circumferential crack defect in the weld fusion line region of a spiral tube and setting one or more axial crack defects in the base material region; Figure 7 This is a simulated sample tube obtained by a method provided in this application embodiment of setting a circumferential crack defect in the weld fusion line region of a spiral tube and setting one or more axial crack defects in the base material region; Figure 8 This application provides a method for using a simulated prototype tube of a heat transfer tube in a nuclear reactor steam generator. The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0020] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0021] The reactor coolant system of a nuclear power plant uses a main pump to drive the circulation of the primary coolant, carrying the heat generated by the fission of nuclear fuel in the reactor core outside the reactor. This heat is then transferred to the secondary coolant in the secondary loop via heat transfer tubes in the steam generator, generating steam to drive the turbine. The steam generator heat transfer tubes thus form the pressure boundary connecting the primary and secondary loop systems of the nuclear power plant. Any damage to these tubes would allow radioactive materials from the primary loop to directly enter the secondary loop, causing radioactive material diffusion. Therefore, periodic inspections of the steam generator heat transfer tubes to ensure their integrity are of paramount importance.

[0022] Eddy current testing is a non-destructive testing method that utilizes the principle of electromagnetic induction to non-destructively evaluate certain properties of conductive materials and workpieces, or to detect defects, by measuring changes in induced eddy currents within the inspected workpiece. Currently, the inspection of needle-type spiral heat transfer tubes in engineering mainly uses the traditional internal Bobbin eddy current probe, with full-length inspection using motor-driven crawling. To verify the accuracy of the probe's inspection data for the spiral heat transfer tube, it is necessary to simulate weld-related defects in the spiral heat transfer tube. However, the cost of currently fabricating a 1:1 scale spiral heat transfer tube sample with butt welds is too high.

[0023] For example, such as Figure 1 As shown, the heat transfer tube of a nuclear power plant steam generator has a spiral coil structure, with a total length of approximately 45m, a spiral diameter of approximately 1m, an outer diameter of approximately 19mm, and a wall thickness of approximately 2.5mm. Due to the inward convexity of the weld seam in the middle of the spiral, a diameter of approximately 13.2mm can pass through the weld seam. There are two butt weld seams along the entire length of the spiral tube, one located in the middle section of the spiral and the other located at the transition joint at the tail, with a weld seam width of approximately 3mm. Because the heat transfer tube of the steam generator is large and the materials are expensive, the cost of fabricating a 1:1 simulated sample tube is too high. Existing technologies do not propose a systematic method for fabricating simulated samples of spiral heat transfer tubes, thus failing to effectively meet the requirement of improving the accuracy of eddy current detection of spiral heat transfer tubes by probes.

[0024] The following, in conjunction with the accompanying drawings, provides a detailed description of the fabrication and usage method of the simulated prototype tube of the heat transfer tube for the nuclear reactor steam generator provided in this application, through specific embodiments and application scenarios.

[0025] This application provides a method for fabricating a simulated prototype of a heat transfer tube for a nuclear reactor steam generator, such as... Figure 2 As shown, the method for fabricating a simulated sample tube according to an embodiment of this application may include the following steps: Step 101: Obtain the combined sample tube.

[0026] The combined sample tube includes at least one straight pipe 301 with a weld, at least one bend pipe 401 with a weld, and at least one spiral pipe 501 with a weld; the centerline of the bend pipe 401 is a planar curve; the centerline of the spiral pipe 501 is a spatial spiral curve; any one of the sample tubes in the combined sample tube has the same diameter and wall thickness as the spiral heat transfer tube; the bend pipe 401 and the spiral pipe 501 have the same length and bending diameter; the straight pipe 301, the bend pipe 401, and the spiral pipe 501 each include the following regions: weld region A, heat-affected region B, weld fusion line region C, and base material region D.

[0027] Step 102: Perform defect processing on the combined sample tube to obtain a simulated sample tube for eddy current testing.

[0028] The defect repair process includes the following steps: A flat-bottomed hole defect is provided in weld area A of the straight pipe 301; Circular groove defects of the same size are respectively set in the weld fusion line region C and the base material region D of the bend 401; A circumferential crack defect is provided in the weld fusion line region C of the spiral tube 501 and one or more axial crack defects are provided in the base material region D. Alternatively, circumferential crack defects of the same size are provided in the weld region A and the heat-affected region B of the spiral tube 501, respectively.

[0029] The embodiments of this application, through the above-described systematic defect processing, obtain a simulated sample tube with interrelated pipe size, defect type, and defect size, which can meet the requirement of improving the accuracy of eddy current detection of spiral heat transfer tubes by probes, thereby greatly reducing the cost of manufacturing simulated sample tubes.

[0030] In some embodiments, in step 101 above, since the spiral heat transfer tubes used in actual engineering have straight sections, planar curved sections, and spatial spiral curved sections, the combined sample tube may include at least one straight tube with a weld, at least one bent tube with a weld, and at least one spiral tube with a weld. Any of the sample tubes in the combined sample tube has the same diameter and wall thickness as the spiral heat transfer tube, and the bent tube has the same length and bending diameter as the spiral tube, which can better simulate the spiral heat transfer tube used in actual engineering. For example, the length of the straight tube with a weld is 300 mm; the length of the bent tube with a weld is 1000 mm, and the bending diameter is 750 mm; the length of the spiral tube with a weld is 1000 mm, and the bending diameter is 750 mm. It should be noted that the dimensions of the sample tube in this embodiment may have some error during processing, for example, an error of ±10 mm.

[0031] In this embodiment, the sample tube with weld seam includes the following areas: weld seam area A, heat-affected zone B, weld fusion line area C, and base material area D. For example, the weld seam area is 3 mm wide, and there are 5 mm wide heat-affected zones on each side of the weld seam.

[0032] In some embodiments, in step 102 above, the combined sample tube is subjected to defect processing to obtain a simulated sample tube, in order to use a probe for eddy current detection, thereby improving the defect characterization accuracy of the probe.

[0033] In this embodiment, it should be noted that the defect processing includes the following steps: setting a flat-bottomed hole defect in the weld area A of the straight pipe.

[0034] In some embodiments, the flat-bottomed hole defect on the straight pipe 301 includes a first flat-bottomed hole, the depth of which is 16% to 24% of the wall thickness, and the diameter of which is 1.52 to 1.68 mm. Exemplarily, the first flat-bottomed hole Q1 has a diameter of 1.6 mm, a depth of 20% (i.e., a depth of 20% of the pipe wall thickness), and a volume of 1 mm. 3 Volumetric defects, such as Figure 3 As shown.

[0035] It should be noted that when actually processing defects, the depth of the center of the defect can be accurate to within ±20% or ±0.08mm of the specified depth, and the smaller of the two shall be taken. The size of other defects can be accurate to within ±0.08mm, and the axial distance between each defect along the sample tube shall not be less than 50mm, and the distance between each defect and both sides of the tube end shall not be less than 70mm.

[0036] In this embodiment, by setting a flat-bottomed hole defect in the weld area of ​​a straight pipe, a preliminary calibration of the eddy current test can be performed on a relatively simple straight pipe with a weld, and a preliminary evaluation of the probe performance can be conducted.

[0037] In some embodiments, the combined sample tube may further include at least one straight tube 302 without weld seams, and the defect processing further includes: Multiple thinning defects of the same length and different depths are set at equal intervals along the center line of the straight pipe 302 without welds.

[0038] In this embodiment, by setting multiple thinning defects of the same length along the center line of the pipe at equal intervals on the straight pipe 302 without welds, the influence of thinning defects of different depths on the detection data of the eddy current probe can be effectively compared. This allows for the preliminary calibration of the relatively simple straight pipe 302 without welds for eddy current inspection and a preliminary evaluation of the probe performance.

[0039] In some embodiments, the interval is not less than 50 mm, the distance between the thinning defect and the pipe end is not less than 70 mm, and the length of the thinning defect is 22.4 to 22.6 mm and the depth is 10% to 50% of the wall thickness. For example, as... Figure 4 As shown, the thinning defect Q2 has a length of 22.5 mm. The thinning defect may include five rectangular thinning defects with a depth of 10% to 50% of the wall thickness. The center lines of the thinning defects are spaced 80 mm apart. The center line of the outermost rectangular thinning defect is 90 mm away from the pipe end. The straight pipe 302 without welds has a length of 500 mm, which is less than the length of the bend or spiral pipe.

[0040] In this embodiment, by setting the interval between defects at least 50 mm and ensuring that the thinning defect Q2 is at least 70 mm from the pipe end, the mutual influence between different defects and the eddy current detection signals caused by the pipe end can be effectively prevented, thereby further improving the defect characterization accuracy of the probe. Generally, to prevent the mutual influence between different defects, flat-bottomed holes and thinning defects are not simultaneously set on the same straight pipe; instead, the same type of defect is set on the same straight pipe.

[0041] In some embodiments, the circumferential groove defect includes: A first circumferential groove is provided in the weld fusion line region C of the bend, and a second circumferential groove is provided in the base material region D of the bend; the depth of the first circumferential groove and the second circumferential groove are both set to 16% to 24% of the wall thickness, the length is 4.92 to 5.08 mm, and the width is 0.17 to 0.33 mm; the distance between the first circumferential groove and the second circumferential groove is greater than 70 mm, and the first circumferential groove and the second circumferential groove are located on the same bend.

[0042] In this embodiment, exemplarily, such as Figure 5 As shown, a first circumferential groove Q3 is provided in the weld fusion line area C of the same bend pipe 401, and a second circumferential groove Q4 is provided in the base material area D; the depth of the first circumferential groove Q3 and the second circumferential groove Q4 are both set to 20% of the wall thickness, the length is 5 mm, the width is 0.25 mm, and the two circumferential grooves are machined on the same pipe with a distance of more than 70 mm between them.

[0043] In this embodiment, the distance between the first annular groove and the second annular groove cannot be too close, for example, it needs to be above 70 mm; otherwise, the eddy current detection data related to the two annular grooves will interfere with each other. In practice, when setting the annular grooves, the distance between the two annular grooves is related to the resolution of the probe and is not limited to above 70 mm. If the resolution of the probe is low, the distance between the first annular groove and the second annular groove needs to be increased.

[0044] In this embodiment, by setting circumferential grooves of the same size in the weld fusion line region C and the base material region D, the eddy current detection signals of circumferential groove defects in the base material region D and the weld fusion line region C can be effectively compared for bends. Furthermore, after performing eddy current detection on the bend in the simulated sample tube, the eddy current probe can be calibrated. Using the calibrated probe, eddy current detection can be performed on relevant weld defects in the spiral tube, thereby further calibration and improving the probe's performance.

[0045] In some embodiments, the circumferential crack defect located in the weld fusion region C of the spiral pipe is a first circumferential crack, with a depth of 26% to 34% of the wall thickness, a length of 4.92 to 5.08 mm, and a width of 0.04 to 0.2 mm; and, The axial crack defects set in the base material region D include a first axial crack with a depth of 16% to 24% of the wall thickness, a second axial crack with a depth of 26% to 34% of the wall thickness, and a third axial crack with a depth of 36% to 44% of the wall thickness.

[0046] In this embodiment, as Figure 6 As shown, exemplarily, a first circumferential crack Q5 with a depth of 30% (also expressed as OD30%), a length of 5 mm, and a width of 0.12 mm is provided in the weld fusion line region C of the spiral tube 501; a first axial crack Q6 with a depth of 20% (OD20%), a second axial crack Q7 with a depth of 30% (OD30%), and a third axial crack Q8 with a depth of 40% (OD40%) are provided in the base material region D of the spiral tube.

[0047] In this embodiment, on the one hand, the differences in eddy current detection signals caused by axial crack defects of the same type (i.e., axial crack defects), the same region (i.e., base material region D), and different depths can be compared for spiral pipes; on the other hand, the differences in eddy current detection signals caused by defects of the same depth (meaning that the depth error is within a reasonable range, such as 30%±4%), different regions (i.e., weld fusion line region C and base material region D), and different types of defects (i.e., circumferential crack defects and axial crack defects) can also be compared. By comparing the two methods, the eddy current probe detection signals for weld defects of spiral pipes can be utilized more comprehensively and efficiently.

[0048] In some embodiments, the circumferential crack defect set in the weld region A of the spiral pipe is a second circumferential crack, and the circumferential crack defect set in the heat-affected region B is a third circumferential crack. The depth of the second circumferential crack and the third circumferential crack are both 36% to 44% of the wall thickness, and the circumferential angle interval is 160 to 200 degrees.

[0049] In this embodiment, as Figure 7 As shown, for the spiral tube 502, the depth of the second circumferential crack Q9 and the third circumferential crack Q10 are both 40% of the wall thickness (i.e., OD40%), and the circumferential angle is 180 degrees apart, that is, they are set opposite each other in the radial direction.

[0050] In this embodiment, since the weld area A and the heat-affected area B are close to each other, by setting circumferential cracks of the same size and spaced apart by circumferential angle, it is possible to obtain the difference in eddy current detection signals brought about by the weld area A and the heat-affected area B, and to more accurately improve the detection accuracy of the eddy current probe.

[0051] In some embodiments, the combined sample tube includes at least two spiral tubes with welds, and the defect processing further includes: setting a circumferential crack defect in the weld fusion line region C of the first spiral tube and setting one or more axial crack defects in the base material region D, and setting a circumferential crack defect of the same size in the weld region A and the heat-affected region B of the second spiral tube respectively.

[0052] In this embodiment, by performing defect processing on two spiral tubes with welds respectively, it is possible to better compare the differences in eddy current detection signals caused by circumferential crack defects in the same but different weld-related areas (weld fusion line area C, weld area A, and heat-affected area B) of the spiral tubes, thereby more accurately improving the detection accuracy of the eddy current probe for the weld.

[0053] In some embodiments, the circumferential groove defect provided on the bend and the circumferential crack defect provided on the spiral pipe have the same length, and the width of the circumferential groove defect is greater than the width of the circumferential crack defect.

[0054] In this embodiment, the width of the circumferential groove defect is greater than the width of the circumferential crack defect, so the detection difficulty of the circumferential groove defect is lower than that of the circumferential crack defect. The circumferential groove defect on the bend and the circumferential crack defect on the spiral pipe have the same length. This allows for better initial calibration of the eddy current probe using the eddy current detection signal from the circumferential groove defect on the bend, followed by recalibration using the eddy current detection signal from the circumferential crack defect on the spiral pipe. This significantly improves the probe's defect assessment capability for welds.

[0055] In some embodiments, the composite sample tube further includes a third spiral tube with a weld, and the defect processing further includes: providing a second flat-bottomed hole in the heat-affected zone B of the third spiral tube, the second flat-bottomed hole having the same size as the first flat-bottomed hole provided in the weld zone A of the straight tube.

[0056] In this embodiment, by machining a second flat-bottomed hole in the heat-affected zone B of the third spiral tube, and the second flat-bottomed hole being the same size as the first flat-bottomed hole in the weld zone A of the straight tube, the differences in eddy current detection signals caused by flat-bottomed hole defects of the same size in different areas of the straight tube and the spiral tube can be better compared. Moreover, setting a second flat-bottomed hole in the heat-affected zone B of the third spiral tube can more realistically simulate the actual defects of the spiral heat transfer tube after a certain number of years of operation.

[0057] This application also provides a method for using a simulated prototype tube of a nuclear reactor steam generator heat transfer tube, such as... Figure 8 As shown, the method of using the simulated sample tube in this application embodiment may include the following steps: Step 201: Obtain the simulated sample tube obtained by any of the above manufacturing methods; Step 202: Use a probe to perform eddy current testing on the flat-bottom hole defect of the straight tube in the simulated sample tube to obtain the first calibration data; use the first calibration data to perform the first data correction on the probe; Step 203: Use the probe to perform eddy current testing on the circumferential groove defect of the bend in the simulated sample tube to obtain the second calibration data; use the second calibration data to perform a second data correction on the probe; Step 204: Use the probe to perform eddy current detection on the circumferential and axial crack defects of the spiral tube in the simulated sample tube to obtain the third calibration data; use the third calibration data to perform the third data correction on the probe.

[0058] In this embodiment, by obtaining a simulated sample tube prepared by any of the above-mentioned manufacturing methods, eddy current testing and probe calibration are performed sequentially on the straight tube, bent tube, and spiral tube in the simulated sample tube. The simulated sample tube can be used to progressively improve the weld defect detection performance of the probe.

[0059] In this embodiment, it should be noted that the various embodiments, implementation methods and methods provided in this application can be implemented independently or in combination without conflict with each other. The specific implementation can be determined according to actual needs, and this application does not limit this.

[0060] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0061] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0062] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for fabricating a simulated prototype of a heat transfer tube for a nuclear reactor steam generator, characterized in that, include: A composite sample tube is obtained, comprising at least one straight pipe with a weld, at least one bent pipe with a weld, and at least one spiral pipe with a weld; the centerline of the bent pipe is a planar curve; the centerline of the spiral pipe is a spatial spiral curve; the straight pipe, the bent pipe, and the spiral pipe all have the same diameter and wall thickness as the spiral heat transfer tube; the length and bending diameter of the bent pipe and the spiral pipe are the same; the straight pipe, the bent pipe, and the spiral pipe each include the following regions: weld region, heat-affected zone, weld fusion line region, and base material region; The combined sample tube is subjected to defect processing to obtain a simulated sample tube for eddy current testing; The defect processing procedure includes the following steps: A flat-bottomed hole defect is provided in the weld area of ​​the straight pipe; Circumferential groove defects of the same size are respectively provided in the weld fusion line area and the base material area of ​​the bend. A circumferential crack defect is provided in the weld fusion line region of the spiral tube and one or more axial crack defects are provided in the base material region; or, circumferential crack defects of the same size are provided in the weld region and heat-affected region of the spiral tube respectively.

2. The method for fabricating a simulated sample tube as described in claim 1, characterized in that, The combined sample tube includes at least two spiral tubes with welds. The defect processing process further includes: setting a circumferential crack defect in the weld fusion line region of the first spiral tube and setting one or more axial crack defects in the base material region, and setting a circumferential crack defect of the same size in the weld region and heat-affected region of the second spiral tube respectively.

3. The method for fabricating a simulated sample tube as described in claim 1 or 2, characterized in that, The circumferential groove defect and the circumferential crack defect have the same length, and the width of the circumferential groove defect is greater than the width of the circumferential crack defect.

4. The method for fabricating a simulated sample tube as described in claim 1, characterized in that, The combined sample tube also includes at least one straight tube without weld seams, and the defect processing further includes: Multiple thinning defects of the same length and different depths are set at equal intervals along the center line of the straight pipe without welds.

5. The method for fabricating a simulated sample tube as described in claim 4, characterized in that, The interval between the specified intervals shall be no less than 50 mm, the distance between the thinning defect and the pipe end shall be no less than 70 mm, and the length of the thinning defect shall be 22.4 to 22.6 mm and the depth shall be 10% to 50% of the wall thickness.

6. The method for fabricating a simulated sample tube as described in claim 1, characterized in that, The flat-bottom hole defect on the straight pipe includes a first flat-bottom hole, the depth of which is 16% to 24% of the wall thickness, and the diameter of which is 1.52 to 1.68 mm.

7. The method for fabricating a simulated sample tube as described in claim 1, characterized in that, The circumferential groove defect includes: A first circumferential groove is provided in the weld fusion line area of ​​the bend, and a second circumferential groove is provided in the base material area of ​​the bend; the depth of the first circumferential groove and the second circumferential groove are both 16% to 24% of the wall thickness, the length is both 4.92 to 5.08 mm, and the width is both 0.17 to 0.33 mm; the distance between the first circumferential groove and the second circumferential groove is greater than 70 mm, and the first circumferential groove and the second circumferential groove are located on the same bend.

8. The method for fabricating a simulated sample tube as described in claim 1 or 2, characterized in that, The circumferential crack defect located in the weld fusion line region of the spiral pipe is a first circumferential crack, with a depth of 26% to 34% of the wall thickness, a length of 4.92 to 5.08 mm, and a width of 0.04 to 0.2 mm; and, Axial crack defects located in the parent material region include a first axial crack with a depth of 16% to 24% of the wall thickness, a second axial crack with a depth of 26% to 34% of the wall thickness, and a third axial crack with a depth of 36% to 44% of the wall thickness.

9. The method for fabricating a simulated sample tube as described in claim 1 or 2, characterized in that, The circumferential crack defect in the weld area of ​​the spiral pipe is a second circumferential crack, and the circumferential crack defect in the heat-affected zone is a third circumferential crack. The depth of the second circumferential crack and the third circumferential crack are both 36% to 44% of the wall thickness, and the circumferential angle interval is 160 to 200 degrees.

10. The method for fabricating a simulated sample tube as described in claim 6, characterized in that, The combined sample tube also includes a third spiral tube with a weld, and the defect processing process further includes: A second flat-bottomed hole is provided in the heat-affected zone of the third spiral tube, and the second flat-bottomed hole has the same size as the first flat-bottomed hole.

11. A method for using a simulated prototype tube of a heat transfer tube in a nuclear reactor steam generator, characterized in that, include: Obtain a simulated sample tube obtained by any one of the manufacturing methods of claims 1 to 10; The simulated sample tube was subjected to the following testing steps using an eddy current probe: The probe is used to perform eddy current detection on the flat-bottom hole defect of the straight tube in the simulated sample tube to obtain the first calibration data; the probe is then corrected for the first time using the first calibration data. The probe was used to perform eddy current detection on the circumferential groove defect of the bend in the simulated sample tube to obtain the second calibration data; The probe is then corrected a second time using the second calibration data. The probe is used to perform eddy current detection on the circumferential and axial crack defects of the spiral tube in the simulated sample tube to obtain third calibration data; the probe is then corrected for the third time using the third calibration data.

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