Qualitative analysis method for welding seam defects at safety end of reactor pressure vessel in nuclear power plant

Abstract

The invention provides a nuclear power plant reactor pressure vessel nozzle safety end weld defect qualitative analysis method. Upon defects with defect amplitude larger than or equal to 20% of the amplitude of the defect on a distance amplitude curve, the detections of the following five contents are carried out: detection of amplitude difference between two sides, detection of multi-angle amplitude difference, detection of whether the dynamic waveform is multi-peak, amplitude difference surround scanning, and detection of whether upper and lower endpoint signals are found. According to the detection results of the above five contents, whether the defect is non-planar defect or planar defect is determined. According to the nuclear power plant reactor pressure vessel nozzle safety end weld defect qualitative analysis method, a safety end weld defect qualitative analysis method with high operability and high accuracy through ultrasonic inspection and measurement is provided. With the method, the reliability of defect qualitative analysis during a nuclear power plant reactor pressure vessel safety end weld manufacturing period can be substantially improved; equipment with planar defect is prevented from entering a power plant; a repairing risk at the nuclear power plant site is reduced; and the guarantee for nuclear power plant safe operation is improved.

Description

technical field [0001] The invention relates to a method for qualitative analysis of welding seam defects at the safe end of a reactor pressure vessel of a nuclear power plant. Background technique [0002] The safety end of the reactor pressure vessel of a nuclear power plant is composed of low-alloy steel, nickel-based alloy pre-stacked edge, austenitic stainless steel weld seam, and surfacing layer. The structure and materials are relatively complicated, and welding is difficult. Permanent dangerous defects may have a relatively large impact on the manufacturing quality of reactor pressure vessels and the safe operation of nuclear power plants. [0003] Due to the coarse grains and many heterogeneous interfaces of the weld at the safety end, the sound attenuation and high noise level during ultrasonic testing are large, and the grain growth direction has a great influence on the penetration ability and propagation direction of ultrasonic waves. Therefore, ultrasonic testi...

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Problems solved by technology

[0004] The research on the qualitative method of weld defects in the publicly reported literature is mainly focused on the static waveform and dynamic waveform of the A-scan signal of the ferritic steel weld defect. , mainly rely on the experience of the on-site inspectors, the operation is often affected by the experience level of the inspectors, and there are many factors that interfere with the qualitative accuracy

At the same time, these documents do not propose a clear and systematic defect qualitative analysis process, especially for the safety end weld of the reactor pressure vessel of the nuclear power plant, and there is no patent document that specifically reports the qualitative analysis method for the safety end weld defect.

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