EMAT pipe inspection technique using higher mode torsional guided wave T(0,2)

We developed a pitch-catch system based on electromagnetic acoustic transducers (EMATs) for pipe inspection, which moves inside the pipe in the axial direction. The first higher mode, T(0,2), of the torsional guided wave is transmitted and detected, and variations of amplitude and phase are measured while moving the EMATs. Several aluminum pipes containing dish-shaped defects are inspected, and the amplitude and phase show enough detection sensitivity. It is found that the phase measurement has better potential as a tool for quantitative inspection. The applicability of the technique for steel pipe is also confirmed.     

蒸汽发生器管板与管孔密封焊缝的渗透检测

介绍了蒸汽发生器管板与管孔密封焊缝的渗透检测工艺及操作,对常见的密封焊缝渗透检测的缺陷进行了分析,可为国内核岛主设备管板与管孔密封焊缝的渗透检测及质量控制提供经验,供同行参考.     

核电主蒸汽超级管道管嘴成形有限元分析

针对核电主蒸汽超级管道管嘴的成形工艺难点:加热工艺、管嘴挤压成形工艺,采用有限元软件ABAQUS分析了影响核电主蒸汽超级管道管嘴成形的主要因素:凸模形状、凸模高度、接触摩擦力和材料温降等。分析结果表明,凸模轮廓直接影响材料的等效塑性应变和管嘴成形尺寸;凸模高度、表面摩擦条件影响管嘴壁厚和高度变化。优化这些影响因素后,进行管嘴一次挤压成形试验,试验结果表明,采用凸形凸模、调整凸模高度、增加润滑条件和降低坯料温降,可以成形出合格的管嘴零件。     

Circumferential higher order guided wave modes for the detection and sizing of cracks and pinholes in pipe support regions

The non-dispersive propagation of ultrasonic guided wave higher order modes cluster (HOMC) traveling along the circumferential direction in a hollow cylinder and its interaction with defects in pipe support regions is reported. These circumferential guided waves were generated in mild steel (MS) pipe specimens containing artificially created axial notches (simulating axial cracks) and pinholes (simulating pinhole-like defects) of different sizes in order to simulate conditions such as cracking and corrosion under pipe supports. The characteristics of these guided waves were also studied as a function of parameters related to how they were generated; namely, using: (a) 2.25 MHz linear phased array transducer, (b) 2.25 MHz conventional circular transducer and (c) 1 MHz conventional circular transducer. These higher frequency modes were explored for their ability to detect and size defects. Because of access limitations to the pipe support region in actual field testing, the transducer was always placed at a fixed circumferential position and moved axially along the length of the pipe. The defect position along the circumference was ascertained from the time of flight while the defect size was estimated using the amplitude data. The signals obtained for all three transducer configurations are compared for their ability to locate, detect and size the above-mentioned defects. It was shown that at these relatively higher frequencies, the guided wave modes exhibit small dispersion and have the ability to provide improved imaging of small size defects throughout the cross-section of the pipe.     

Localization of defects in steam generator tubes using a multi-coil eddy current probe dedicated to high speed inspection

Steam generator (SG) tubing of pressurized water reactor in nuclear plants must be rapidly and accurately checked in order to detect defects in their early stages. In this paper, the authors present a multi-coil eddy current (EC) probe allowing both high speed inspection and circumferential localization of defects in the tube wall. A method of multi-coil EC signal processing, based on a continuous wavelet transform combined with a maximum likelihood diagnosis, is elaborated in order to enhance the detection performances and to provide automatic localization of defects. The inspection of SG tube samples shows good localization performances for defects as small as 10% deep, 15 mm long and 100 μm wide outer diameter notches, of both circumferential and axial orientations.     

小型堆直流蒸汽发生器传热管工艺研究及质量控制

针对小型堆直流蒸汽发生器,分析了其传热管的工艺过程.冷轧时,优化了冷轧工模具孔型的开口设计、孔型曲线设计及与之匹配的顶头变形段及定径段设计;TT处理时,控制温度在715 ℃、保温时间为5h以上,以提高抗晶间腐蚀的能力;弯制时,采用反变形法和特殊的模具设计,确定模具的开槽高度为9.91 mm、反变形量为0.09 mm,以...     

The reflection of guided waves from notches in pipes: a guide for interpreting corrosion measurements

Ultrasonic guided waves are used for the rapid screening of pipelines in service and simple, standard testing procedures are already defined. The implementation of the method enables the localization of the defects along the length of the pipe and offers a rough estimate of defect size. In this article we present a systematic analysis of the effect of pipe size, defect size, guided wave mode and frequency on the reflection from notches. The maximum and minimum value of the reflection coefficient at varying axial extent are identified and used for the purpose of defect sizing. Maps of reflection coefficient as a function of the circumferential extent and depth of the defect are presented for a 3 in. schedule 40 steel pipe. An approximate formula, which allows these results to be extrapolated to other pipe sizes, is proposed and evaluated.     

Nondestructive technique for identification of the dished end of nuclear fuel pellets

Use of an infrared technique for identifying the dished/flat ends of nuclear fuel pellets for PHWR is suggested. The studies show that this method can be used for on-line checking of the orientation of the pellets.     

A novel feature extraction for eddy current testing of steam generator tubes

For defect characterization in steam generator tubes, feature extraction to interpret eddy current testing (ECT) signals has been recognized as an important step. In this paper, we propose a new feature extraction from ECT signals for defect classification and defect sizing. Using the extracted features as an input vector, a multi-layer perceptron (MLP) neural networks are used to classify defect types and to predict defect size. Although the proposed method requires relatively fewer features for the defect classification, it provides not only a high level of classification accuracy but also promising robustness to noise. Moreover, for the prediction of defect size, the proposed method yields a comparable prediction accuracy even though it needs fewer features than the previous result.     

A neural network-based technique for quantitative wire rope inspection

The possibility of solving the problems encountered in the quantitative inspection of broken wires with a neural network is discussed and a new algorithm is presented. In comparison with conventional methods, the performance of inspection is much improved with the neural network-based technique.     

岭澳核电汽轮发电机外机座冷却器罩装焊工艺

东方电机股份有限公司为确保岭澳核电发电机外机座关键部件冷却器罩的合格生产,从合同要求出发,结合企业实际情况,低成本、高质量地完成了冷却器罩制造.冷却器罩尺寸大,精度要求高,按合同要求一次成型难度大.通过几种备料成型方案的对比,最终选择较为有效且经济的方案.同时制定合理的装焊工艺,确保成型尺寸,最终控制了焊接变形,确保合...     

核电厂蒸汽发生器SA213T22传热管表面氧化膜的耐蚀性

人工研制了核电厂蒸汽发生器SA213T22传热管的高温氧化膜,采用SEM、XRD、热重分析法分别对氧化膜厚度、微观形貌、成分和稳定性进行了观察和分析。结果表明:氧化膜具有均匀、完整、无孔隙、稳定性好的特点;经高温氧化及矿物油封闭处理后,SA213T22传热管的耐蚀性得到了显著提高,在不同环境中挂片31个月后,试样均未发生腐蚀,完全满足工程应用的要求。     

A new technique for measuring the acoustic nonlinearity of materials using Rayleigh waves

This note presents a procedure to generate nonlinear Rayleigh surface waves without having to drive the transmitting piezoelectric transducer at high voltages; driving at low voltages limits the excitation of the intrinsic nonlinearity of the piezoelectric transducer element, and enables an efficient measurement procedure to isolate inherent material nonlinearity. The capabilities of this proposed technique are demonstrated by measuring the material nonlinearity of aluminum alloy 2024 and 6061 plates with Rayleigh surface waves.