Ultrasonic flaw detection method for fuel rod cladding of heat pipe micro-reactor

Abstract

The invention discloses an ultrasonic flaw detection method for a heat pipe micro-reactor fuel rod cladding and belongs to the field of nuclear power. The method comprises the following steps that a rotating head ultrasonic flaw detection device is provided, guide sleeves with inner guide ends are arranged at a workpiece inlet and a workpiece outlet of a rotating water cavity respectively, the inner guide ends of the two guide sleeves are oppositely arranged, and the interval between the inner guide ends is a detection area of an ultrasonic probe; the inner diameter of the guide sleeve is matched with that of a cladding tube to be detected; and a cladding tube to be detected penetrates through the guide sleeve in the axial direction, penetrates in from one end of the workpiece inlet and penetrates out from one end of the workpiece outlet until the cladding tube completely penetrates through the rotating head ultrasonic flaw detection device, and flaw detection is completed. The method can effectively reduce the scratch risk of the surface of the cladding tube and improve the flaw detection efficiency and precision.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of nuclear power, in particular to a heat pipe micro- reactor fuel rod cladding ultrasonic detection method. BACKGROUND

[0002] The heat pipe micro-reactor is a new type of full solid reactor, which adopts a solid matrix to export the heat of the fuel rod. Since the complex primary circuit is omitted, it has the advantages of simple structure, small size and high inherent safety. The fuel rod cladding tube used in the heat pipe micro-reactor has a small diameter, high precision and long length. In the current production process, the cladding tube is not cut to size before ultrasonic detection. The existing ultrasonic detection method is to use a rotating head ultrasonic detection device to perform water immersion ultrasonic detection on the cladding tube. During the detection process, the cladding tube is in contact with the ultrasonic detection equipment, which can easily cause surface scratches. Moreover, since the tube is long and thin, when the straightness of the tube body is out of tolerance, the rotating ultrasonic probe can easily collide with the curved tube body, causing damage. At the same time, the straightness deviation can also cause the coupling water pressure to fluctuate, which can cause false detection and affect the detection accuracy. Therefore, it is of positive significance to provide a more reliable heat pipe micro-reactor fuel rod cladding ultrasonic detection method to improve the detection efficiency and accuracy. SUMMARY

[0003] The purpose of the present application is to provide a heat pipe micro-reactor fuel rod cladding ultrasonic detection method to improve the efficiency and accuracy of ultrasonic detection.

[0004] According to an embodiment of the present application, a heat pipe micro-reactor fuel rod cladding ultrasonic detection method is provided, which comprises the following steps:

[0005] Step a): providing a rotating head ultrasonic detection device, fixed guide sleeves are arranged at the workpiece inlet and workpiece outlet of the rotating water cavity of the rotating head ultrasonic detection device, the guide sleeves are made of self-lubricating material and have inner guide ends, the inner guide ends of the guide sleeves are coaxially arranged towards each other, and a spacing area is formed between the ends of the two inner guide ends, which serves as a detection area for the ultrasonic probe; the inner diameter of the guide sleeve matches the cladding tube to be detected;

[0006] Step b): starting the rotating head ultrasonic detection device, and inserting the cladding tube to be detected into the guide sleeve at the workpiece inlet and out of the guide sleeve at the workpiece outlet;

[0007] Step c): driving the cladding tube to be detected in the axial direction until it completely passes through the rotating head ultrasonic detection device.

[0008] The method effectively avoids the scratch of the cladding tube surface in the ultrasonic detection process by setting the guide sleeve with self-lubricating properties; at the same time, since the guide ends extend towards each other, the span of the cladding tube in the detection process is reduced, and the radial limit is provided for the cladding tube, which effectively prevents the ultrasonic probe from being damaged due to the bending of the cladding tube in the detection process; thereby, the continuous non-destructive detection for the cladding of the heat pipe micro-rod fuel rod can be efficiently and reliably realized.

[0009] Further, in some embodiments, in step a), the guide sleeve further comprises an outer guide end, and the outer guide ends of the two guide sleeves are arranged away from each other to provide limiting and guiding for the cladding tube to be detected outside the rotating water cavity.

[0010] Further, in some embodiments, in step a), the guide sleeve further comprises a fixing flange, and the guide sleeve is positioned circumferentially with the rotating head ultrasonic detection device by installing a plurality of fastening bolts on the fixing flange.

[0011] Further, in some embodiments, in step a), the locking torque provided by the fastening bolt is not less than 20 N·m.

[0012] Further, in some embodiments, in step a), the guide sleeve is made of PA66 nylon.

[0013] Further, in some embodiments, the surface roughness Ra of the guide sleeve is ≤0.2 μm.

[0014] Further, in some embodiments, the concentricity of the two guide sleeves is ≤0.02 mm.

[0015] Further, in some embodiments, in step b), the dynamic coupling water pressure in the rotating water cavity is controlled to be maintained at 0.5±0.02 MPa; and in step c), the feeding speed of the cladding tube to be detected is 1.5 m / s-2.5 m / s.

[0016] Further, in some embodiments, during the process that the cladding tube to be detected passes through the rotating head ultrasonic detection device, the signal fluctuation is not more than 3%. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a schematic diagram of the ultrasonic detection process for the cladding of the heat pipe micro-rod fuel rod in an embodiment;

[0018] Figure 2 FIG. 2 is a schematic diagram of the guide sleeve structure in an embodiment.

[0019] Meaning of reference signs:

[0020] 1-cladding tube; 2-rotary head ultrasonic flaw detection device; 3-rotary water cavity; 4-ultrasonic probe; 5-guide sleeve; 6-inner guide end; 7-outer guide end; 8-fixing flange; 9-mounting hole.

[0021] The purpose of the above-mentioned drawings is to make a detailed description of the present application so that those skilled in the art can understand the technical concept of the present application, and is not intended to limit the present application. In order to express concisely, the above-mentioned drawings only schematically draw the structures related to the technical features of the present application, and do not strictly draw the complete structures and all details according to the actual proportion. DETAILED DESCRIPTION

[0022] The present application will be further described in detail below by specific examples in combination with the drawings.

[0023] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment. The appearances of the phrase that the phrase in various places in the specification are not necessarily referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of one another. Those skilled in the art will recognize that an embodiment described herein can be combined with another embodiment in so far as the structures are not mutually inconsistent.

[0024] In the description herein, the meaning of "a plurality of" is at least two.

[0025] The fuel rod cladding used by the heat pipe micro reactor has a small specification, an outer diameter of only about 19 mm, a wall thickness of about 0.8 mm, and a high production precision requirement, and at the same time, the cladding length is usually more than 20 m, and the processing and manufacturing are difficult. The fuel rod cladding is directly related to the safety performance of the reactor, and therefore strict quality detection needs to be carried out during the production process.

[0026] At present, there are many difficulties in using the rotary head ultrasonic flaw detection device to detect the heat pipe micro reactor fuel rod cladding. Since the length is not fixed before ultrasonic detection and flaw detection in the production process, the specification is frequently adjusted during the flaw detection process, the disassembly and adjustment of the conventional metal clamp takes more than 30 minutes for a single time, and the detection efficiency is low; during the flaw detection process, the cladding passes through the rotary head ultrasonic flaw detection device and directly contacts the metal part, and the scratch rate is more than 5%, which seriously affects the surface quality; since the pipe length is long, when the straightness deviation reaches 0.1 mm / m, the coupling water pressure fluctuation is easily caused, the head and tail detection false positive rate is more than 15%, and the accuracy of the detection result is affected; since the ultrasonic probe rotates at high speed around the cladding tube and the distance is very close (only a few millimeters in some working conditions), when the straightness deviation is large, the ultrasonic probe has the risk of collision and damage.

[0027] In order to solve the above-mentioned problems, the embodiment of the present application provides a heat pipe micro reactor fuel rod cladding ultrasonic flaw detection method, which combines Figure 1 and Figure 2The method comprises the following steps:

[0028] Step a): providing a rotary head ultrasonic flaw detection device 2, fixed guide sleeves 5 are arranged at the workpiece inlet and the workpiece outlet of the rotary water cavity 3 of the rotary head ultrasonic flaw detection device 2. The guide sleeves 5 are made of self-lubricating material, in the preferred embodiment, high-density nylon material which is not easy to expand and shrink is used, and in the further preferred embodiment, PA66 nylon material with a density of 1.3 g / cm 3 and a friction coefficient of not more than 0.15 is used. The guide sleeve 5 has an inner guide end 6 extending into the rotary water cavity 3, and the inner guide ends 6 of the two guide sleeves 5 at both ends of the rotary water cavity 3 are coaxially arranged towards each other, and the inner guide ends 6 form a spacing area between them, which is the detection area of the ultrasonic probe 4. In different embodiments, the width of the spacing area is controlled according to the specifications and detection requirements of the ultrasonic probe 4, and in some embodiments, it can be set to 10-20 mm.

[0029] The guide sleeve 5 is provided with a fixed flange 8, and the outer edge of the fixed flange 8 is provided with threads for screwing and fixing the guide sleeve 5 to the workpiece inlet or workpiece outlet position of the rotary water cavity 3, and forming a seal to prevent the deionized water in the rotary water cavity 3 from leaking during work and affecting the stability of the coupling water pressure. In the preferred embodiment, the fixed flange 8 is provided with four mounting holes 9 at intervals of 90° in the circumferential direction, and the fastening bolts pass through the mounting holes 9 to fasten the fixed flange 8 and the base body of the rotary head ultrasonic flaw detection device together, further improving the stability of the guide sleeve 5 while enabling circumferential positioning of the guide sleeve 5 to prevent the guide sleeve 5 from rotating circumferentially during work, causing the threads on the outer edge of the flange 8 to loosen. The fastening bolt fixing torque is 20 N·m, and after fastening is completed, the concentricity of the guide sleeve 5 is ≤0.02 mm.

[0030] The inner diameter of the guide sleeve 5 matches the outer diameter of the cladding tube 1 to be detected, and in the preferred embodiment, the gap is controlled to be ≤0.006 mm, and corresponding guide sleeves 5 can be selected for cladding tubes 1 of different diameters to omit the working hours of adjusting the movable clamp. In one embodiment, the outer diameter of the cladding tube 1 is 19±0.05 mm, and the inner diameter of the corresponding guide sleeve 5 is 19.005±0.003 mm. The inner surface of the guide sleeve 5 is polished to control the roughness RA to be ≤0.2 μm to ensure that the cladding tube 1 does not jam or scratch when passing through.

[0031] In the preferred embodiment, the guide sleeve 5 is also provided with an outer guide end 7, which extends outwardly of the rotary water cavity 3 in the installed state, and the outer guide ends 7 of the two guide sleeves 5 are arranged away from each other. The length of the outer guide end 7 is set to 150 mm to further suppress the radial jitter of the cladding tube 1 and improve the stability of the ultrasonic echo signal during detection.

[0032] Step b): start the rotating head ultrasonic flaw detection device, control the dynamic coupling water pressure in the rotating water cavity 3 to maintain at 0.5±0.02 MPa, pass the cladding tube 1 from the workpiece inlet of the rotating water cavity 3 through the guide sleeve 5, and pass out from the other guide sleeve 5 fixed at the workpiece outlet.

[0033] Step c): drive the cladding tube 1 in the axial direction to pass through the rotating head ultrasonic flaw detection device at a feeding speed of 2 m / s, complete the flaw detection, and the ultrasonic echo signal fluctuation in the 2m range at the head and tail is less than 3% due to the guiding and limiting effect of the outer guide end.

[0034] The above-mentioned heat pipe micro-rod cladding ultrasonic flaw detection method provided in the embodiment utilizes the guide sleeve 5 made of self-lubricating material to effectively reduce the risk of scratching the outer surface of the cladding tube 1. In actual detection tests, compared with the existing scheme using metal clamps, the pipe scratching rate is reduced from 5.2% to 0. The nylon material has low cost and is easy to process and form, and can be adapted to different specifications of the cladding tube 1. The installation and disassembly are simple and fast. Compared with the scheme using traditional metal clamps, the specification changing time is shortened from 30 minutes to 5 minutes, effectively improving the detection efficiency. Since the cladding tube 1 is radially limited and guided in the rotating water cavity 3 by the inner guide end 6, the span of the cladding tube 1 in the rotating water cavity 3 is reduced, effectively preventing the collision and damage of the ultrasonic probe 4 with the surface of the cladding tube 1 during the rotation detection when the straightness of the cladding tube 1 is out of tolerance. Further, by setting the outer guide end 7, the radial shaking of the cladding tube 1 during feeding is further suppressed, improving the stability of the coupling water environment. Especially, the detection data of the head and tail sections is more accurate, reducing the noise interference, reducing the false alarm rate of the head and tail sections from 15% to 2.1%, effectively improving the detection accuracy; the detection data stability is further optimized from ±8% to ±1.5%, and the reliability of the measurement data is significantly improved.

[0035] The purpose of the above-mentioned embodiment is to make a further detailed description of the present application in combination with the drawings, so that those skilled in the art can understand the technical concept of the present application. Within the scope of the present application, the technical features involved are optimized or equivalently replaced, and the embodiments in different embodiments are combined without structural and principle conflicts, which all fall within the protection scope of the present application.

Claims

1. A method for ultrasonic flaw detection of heat pipe micro-reactor fuel rod cladding, characterized in that: The following steps are involved: Step a): Providing a rotating head ultrasonic flaw detection device, and disposing fixed guide sleeves at the workpiece inlet and workpiece outlet of a rotating water chamber of the rotating head ultrasonic flaw detection device, respectively. The guide sleeves are made of a self-lubricating material and have inner guide ends. The inner guide ends of the guide sleeves are coaxially arranged facing each other, and a spacing area is formed between the distal ends of the two inner guide ends. The spacing area serves as the detection area of ​​the ultrasonic probe; the inner diameter of the guide sleeves matches the cladding tube to be inspected; Step b): starting the rotary head ultrasonic flaw detection device, passing the cladding tube to be inspected through the guide sleeve at the workpiece inlet and out of the guide sleeve at the workpiece outlet; Step c): driving the cladding tube to be inspected in the axial direction until it completely passes through the rotary head ultrasonic flaw detection device.

2. The ultrasonic flaw detection method for heat pipe micro-reactor fuel rod cladding according to claim 1 is characterized in that: In step a), the guide sleeve further includes an outer guide end, and the outer guide ends of the two guide sleeves are arranged to be separated from each other to provide positioning and guidance for the cladding tube to be inspected outside the rotating water cavity.

3. The ultrasonic flaw detection method for heat pipe micro-reactor fuel rod cladding according to claim 2 is characterized in that: In the step a), the guide sleeve further comprises a fixing flange, and a plurality of fastening bolts are installed on the fixing flange to circumferentially position the guide sleeve and the rotating head ultrasonic flaw detection device.

4. The ultrasonic flaw detection method for heat pipe micro-reactor fuel rod cladding according to claim 3 is characterized in that: In step a), the tightening torque provided by the fastening bolt is not less than 20 N·m.

5. The ultrasonic flaw detection method for heat pipe micro-reactor fuel rod cladding according to any one of claims 1 to 4, characterized in that: In the step a), the guide sleeve is made of PA66 nylon.

6. The ultrasonic flaw detection method for heat pipe micro-reactor fuel rod cladding according to any one of claims 1 to 4, characterized in that: The surface roughness of the guide sleeve is Ra≤0.2 μm.

7. The ultrasonic flaw detection method for heat pipe micro-reactor fuel rod cladding according to any one of claims 1 to 4, characterized in that: The concentricity of the two guide sleeves is ≤0.02mm.

8. The ultrasonic flaw detection method for heat pipe micro-reactor fuel rod cladding according to any one of claims 1 to 4, characterized in that: In the step b), the coupling water pressure in the rotating water chamber is dynamically controlled to be maintained at 0.5±0.02 MPa; in the step c), the feeding speed of the cladding tube to be inspected is 1.5 m / s-2.5 m / s.

9. The ultrasonic flaw detection method for heat pipe micro-reactor fuel rod cladding according to any one of claims 1 to 4, characterized in that: During the process of the cladding tube to be inspected passing through the rotary head ultrasonic flaw detection device, the signal fluctuation does not exceed 3%.

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