Method of quality control of welded joints of heat-generating element

 

Method of quality control of welded joints of heat-generating element is intended for use in the field of nuclear energy. The method consists in the emission of the ultrasonic signal. Ultrasonic signal piezoelectrically falls normally to the outer surface of the fuel element and the surface of the weld when moving along its generatrix. Complete the registration of the echo signals from the inner and outer surface of the shell and weld in the area of line continuation of the inner surface of the shell over time. It provides detection of penetration, pores, micropores, the length of the zone of the integrity and reliability of their detection. 1 Il.

The invention relates to non-destructive methods for quality control of welds, namely, ultrasonic testing sealing welds fuel element for nuclear reactors VVER-1000, VVER-440, in which the welds are made pin-butt welding (CSS-2) and the electron-beam welding (ELS).

There is a method of ultrasonic inspection of the weld pin-butt welding stub to the fuel cladding, including testing in demetropoulou during the rotation of the fuel element and the movement of the transmitter and receiver of ultrasonic pulses in the axial direction of the weld joint area of the fuel element, recording the results of the control and determination section length fusion in the direction of the axis of fuel element (“Development, production and operation of fuel cell power reactors”. /Ed. by F. G. Reshetnikov, kN.2, M.: Energoatomizdat, 1995, S. 274-276, and Fig.21.12. Schematic of ultrasonic inspection of welded joints made contact butt welding KCC-2).

The disadvantage of this method is the lack of detection of pores in the region of the line of continuation of the inner surface and penetration, determined by the length of the continuation of the inner surface.

The closest in technical essence and the achieved result is a prototype method of ultrasonic testing of the weld by the RF patent №2158031 “Method of ultrasonic testing of the weld pin-butt welding stub to the fuel cladding”, IPC G 21 17/07, 21/00, 2000, including the testing of the ultrasonic beam welded joint, receiving ultrasonic pulses at discrete rotation of the fuel element and line-by-line reciprocating movement of the radiating and receiving piezoelectric transducers in the axial zone of the ia in the direction of the axis of the fuel element.

The disadvantage of this method is the lack of detection of pores in the region of the line of continuation of the inner surface and penetration, determined by the length of the continuation of the inner surface.

Object of the invention is the identification of poor penetration, pores, micropores, the length of the zone of the integrity and reliability of detection.

The task is solved in that a method of quality control of welded seams fuel element consists in the emission of the ultrasonic signal, its reception and analysis, according to the formula of the invention the ultrasonic signal transducer impinges normal to the outer surface of the fuel element and the surface of the weld while moving it along the surface and record the echo signals from the inner and outer surface of the membranes and in the line of continuation of the inner surface of the shell at the time, duration and extent of an observation.

This set of features is new and involves an inventive step, because the method allows to evaluate the quality of sealing of welded joints shell plugs fuel elements made of electron-beam welding and contact-butt welding (KCC - through ultrasonic signal normal to the surface of the shell and weld and additional use of the echo signals from the undercut stubs for electron beam welding and bottom signal for pin-butt welding (CSS-2).

The drawing shows a diagram of the method for quality control of the weld heat-generating element, in which an I - diagram of the scanning of the weld of the first stub made of electron-beam welding II - diagram of the scanning of the weld of the second stub made contact butt welding (CSS-2).

The method is implemented as follows.

TVEL is served in the immersion bath of the rotation mechanism. After installation of a fuel rod at the position of the control and signal source status command to the personal computer starts the reciprocating movement of piezoelectrically (PEP) along the axis of the fuel rod and subsequent rotation of the fuel rod at a given angle after each move, and personal computer remembers the current position of the moving probe and the angle of rotation of the fuel rod.

At the same time starts the pulse generator, connected to the probe, and the ultrasonic signals generated by the transducers, prosvechivayut membrane of a fuel rod and welded connection. Echo signals reflected from the surfaces of the fuel elements and discontinuities, accepted the probe and amplified in the amplifier for further processing in a personal computer and surveillance on the screen of the cathode-radiology is m piezoelectric, for example, the focusing, the inverter 1 via the immersion liquid falling normal to the outer surface 2 of the casing of a fuel rod. Reflected from the outer surface 2 of the echo signals of 3 are recorded ultrasonic flaw detector 4 and the screen of the cathode ray tube (CRT) 5 see echoes 3. The ultrasonic vibration is held in the sheath material, reflect from the inner surface 6. The reflected echo signals from the inner surface 6 register ultrasonic flaw detector 4 and the CRT screen see echoes 7.

The duration of strobe 12 detector 4 is installed between the signals 3 and 7. When moving the piezoelectric transducer 1 along the generatrix of TVEL recorded echo signals 3 and 7 ultrasonic flaw detector 4 and remember synchronously with the movement in the PC memory 16.

When switching on weld continued registration of echoes 3, set the duration of strobe 12 provides registration of defects in welded joints 9 or 10 above the line 11 continuation of the inner surface. The amplitude and width of the echo signals caught in the strobe-pulse 12 detects faults: pores, lack of penetration, and the length of the observation time of the signal determines edenia probes produce again this is repeated until a complete rotation of the fuel rod at the angle of 360C. Echo each line remember. After the disappearance of the echo signal 7 from the inner surface 6 begins extent of continuity, as in the weld and in the absence of incomplete fusion is receiving echo signals from the second strobe pulse 19, installed in a specific location. For a welded joint 9 ELS in place of the 3rd reflection echo signal 7, you receive an echo signal 13 that is reflected from the surface 14 of the undercut, which carries additional information about the quality of a welded joint: it informs about the lack of lack of fusion, and interrupt - on the presence of pores, for a welded joint 10 KCC-2 - echoes 15 reflected from the opposite surface of the blank. Its presence informs about the quality of a welded joint and its length, and interrupt - on penetration and micropores.

Thus, the application of this method allows to increase quality control and, consequently, the reliability of the fuel element.

Claims

Method of quality control of welded joints of heat-generating element, consisting in the emission of the ultrasonic signal, its reception and Ana is poverhnosti fuel element and the surface of the weld while moving it along the surface and record the echoes from the outer and inner surface of the shell and weld in the area of line continuation of the inner surface of the shell at a time the duration and the extent of the surveillance.

 

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