反应堆压力容器接管嘴马鞍面缺陷的断裂力学分析

某核电厂大修时发现反应堆压力容器均在出口接管嘴不锈钢堆焊层出现局部表面损伤痕迹,损伤最深处约为1.27 mm.本文采用ANSYS程序,依据相应规范,对反应堆压力容器出口接管嘴缺陷进行快速断裂力学分析和疲劳裂纹扩展分析.分析内容包含缺陷的包络和假设、应力计算、应力强度因子计算、疲劳裂纹扩展尺寸计算和Ⅱ、Ⅲ、Ⅳ工况及水压试验工况下的断裂力学分析评估.分析结果满足规范要求.     

随机载荷下含表面平面缺陷结构的安全评定

许多含有表面平面缺陷的金属结构都受到随机载荷的作用.以结构可靠度为基础探讨了随机载荷对结构安全评定的影响.通过统计结构所承受的载荷,得到随机载荷的统计参数(平均载荷、载荷标准差),并使用载荷的统计参数对实际载荷进行等效处理.通过蒙特卡罗方法计算结构的可靠度,研究一定可靠度下随机载荷的变异系数和分散性安全系数的关系.结果发现,不考虑载荷分散性的影响是偏于危险的.载荷分散性的影响可以分散性系数来衡量,使用分散性安全系数对载荷进行等效处理,最后采用处理后的等效载荷进行结构的安全评定.     

含缺陷Inconel 690蒸汽发生器传热管的强度及堵管准则研究

针对缺陷对传热管强度的影响以及传热管判废准则问题展开研究,研制了适用于小管径蒸汽发生器传热管极限载荷及爆破压测试的实验装置,对含体积型缺陷及面型缺陷的Inconel 690蒸汽发生器传热管进行了实验研究,并采用有限元法对极限载荷及爆破压进行了估算.在此基础上,研究了传热管的堵管准则,提出了两级评定方法.该评定方法可根据缺陷的深度、轴向及环向长度来综合评价.     

固体发动机ICT图像缺陷检测中的插值方法研究

固体发动机的缺陷主要有药柱内气孔、裂纹和多界面脱粘,这些缺陷在ICT检测生成的断层图像中,和整幅断层图像相比只占据少量像素,给缺陷分析带来困难.采用图像插值技术放大含有缺陷的局部断层图像,可获得更丰富的缺陷信息.文章将图像插值技术分为基于图像插值方法和基于对象插值方法两类,分别进行分析、比较,并给出含有典型缺陷的固体发动机断层局部图像放大4×4倍后的图像.经过对比,基于对象的插值方法效果明显优于基于图像的插值放大方法,但其计算量大、耗时多.在固体发动机断层缺陷图像放大分析中,今后研究重点应是简化现有的或提出新的基于对象的插值方法,保证插值精度基础上提高插值速度.     

SWD-1型涡流探伤仪

SWD-Ⅰ型涡流探伤仪及其配套设备包括:1.探伤仪主机;2.配套探头系列;3.探头插座;4.自动喷色标记系统。它运用涡流探伤原理,配用穿过式探头广泛,适用于核工业各工矿企业的生产流水线上对各种金属材料进行自动探伤。该套设备具有下述特点:(1)凡是金属丝材、管材、棒材均可用它来进行探伤;(2)被测材料直径从φ1～φ36mm,设计特殊探头可扩大到φ87以上,可对异型截面材料及板材探伤;(3)对不同直径的工件探伤时,只需更换探头,不必更换主机。操作简便,检测效率高;(4)机内配有多种显示缺陷的功能。特别是采用自动喷色标记器,可以直观、准确地将探出缺陷直接标记在工件上,便于分选使用;(5)本机体积小、重量轻、成本低、适用于生产规模的连续检测。     

液压下压力管线活动缺陷声发射信号研究

在液压试验装置上,对含预制裂纹的压力管开展了缺陷扩展声发射信号试验研究.全程不间断监测压力管道疲劳裂纹扩展的声发射信号,并对采集到的信号进行分析处理.结果表明:管道缺陷声发射信号的幅度和能量随加载时间逐步增大,可以用于鉴别管道是否存在活动缺陷;在缺陷贯穿前,声发射信号的幅度、能量和计数急剧增加,可以预报管道缺陷的贯穿泄漏.     

异种钢焊缝缺陷分析及安全性评定

本工作按照ASME BPVC第Ⅺ卷附录C和附录H对异种金属焊缝进行了分析和评定.同时,对附录C进行了工程应用开发,并选取典型管道建立外表面缺陷评定图,用该评定图对异种金属焊缝进行了评定.该评估方法可直接用于评定在役检查中发现的缺陷,而不需额外的断裂力学知识,为使用者提供了方便简捷的工程实用方法.     

异种金属焊缝超声爬波检测技术

为了有效解决核电厂异种金属焊缝表面、近表面缺陷的检测问题,开发了一种新型的超声爬波检测技术,并对其性能进行了试验验证.结果表明,采用超声爬波技术能有效检测出异种金属焊缝表面、近表面存在的类似液体渗透检测所发现的线性缺陷,能有效确定缺陷深度、长度和高度.超声爬波检测技术的有效覆盖深度达到0～9 mm,能有效检测出焊缝中存在的当量面积大于3 mm2以上的平面性缺陷,实现了对自身高度大于2 mm的平面性缺陷高度尺寸的精确测量.     

基于工业CT的工件缺陷识别方法

工业CT是一种有效的工件缺陷识别的方法,代表着无损检测技术的发展方向.首先概述工业CT技术在工件缺陷识别中的应用,并把其他和其他常用方法进行了简单比较;接着从工件缺陷识别的流程入手,对每个步骤都从处理思路和处理方法方面作了阐述;然后对一些在工件缺陷识别方面很有潜力的算法(Level set和Gabor小波)进行了介绍和分析;最后对工业CT在工件缺陷识别方面的应用前景进行了展望.     

雷达技术在混凝土结构无损检测中的应用

通过对常用无损检测技术的比较,结合岭澳核电站安全壳老化检测的工程实例研究雷达技术在混凝土无损检测中的应用效果,并针对实际问题,对雷达图像资料进行分析,研究了影响冒达成像的因素,以提高建筑物修复加固依据的科学性.     

田湾核电站2号机组波动管焊接的核安全监督

田湾核电站波动管的焊接过程中出现了超标缺陷。本文描述了北方监督站在2号机组波动管焊接及缺陷的处理过程中所进行的核安全监督。     

EPR核电厂CRDM耐压壳焊缝缺陷信号分析

核电厂控制棒驱动机构（CRDM）长期处于高温、高压和高辐射环境中,其耐压壳异种金属焊缝容易出现裂纹等缺陷,是大修期间在役检查的关注重点。针对该焊缝役前超声检查中发现的疑似缺陷显示,通过补充目视、射线、超声相控阵和破坏性试验,验证了此类显示信号为不完全再结晶的奥氏体硬化晶粒造成的冶金显示,不影响耐压壳焊缝的质量,并总结了核电厂核岛设备超声疑似缺陷信号分析验证的方法。      

Infrared thermography inspection for monoblock divertor target in JT-60SA

Carbon fiber composite (CFC) monoblock divertor target is required for power handling in JT-60SA. Quality of the targets depends on a joining technology in manufacturing process. To inspect the quality of more than 900 target pieces, efficient non-destructive inspection is needed. An infrared thermography inspection (IR inspection), has been proposed by ITER and IRFM, where the quality between CFC and a cooling tube is examined by a use of transient thermal response at a rapid switch from hot to cold water flow. In JT-60SA divertor target, a screw tube will be employed to obtain high heat transfer efficiency with simple structure. Since the time response of the screw tube is much faster than that of smooth tube, it is required to confirm the feasibility of this IR inspection. Thus, the effect of joining defects on transient thermal response of the targets has been investigated experimentally by using the mock-up targets containing defects which are artificially made. It was found that the IR inspection can detect the defects. Moreover, screening criteria of IR inspection for acceptable monoblock target is discussed.     

Development of probability of detection functions for evaluating integrity of axial outside diameter stress corrosion cracks in steam generator

The reliability of an eddy current testing (ECT) inspection system depends upon the inspection technique and quality of analyst. In evaluating the integrity of a steam generator (SG) tube, degradation detection and sizing accuracy are considered performance measures of the nondestructive evaluation (NDE) system. A probability of detection (POD) model serves as a functional measure of the ability of an NDE system to detect degradation. It is one of the inputs in the operational assessment, and it is used to estimate the degradation during service via ECT of the SG tube. In this study, the POD functions of the inspection technique and analyst were obtained to quantitatively analyze the ECT bobbin probe for axial outside diameter stress corrosion cracks in SG tubes. This should serve to evaluate the integrity of the SG tubes. The depth and amplitude of defects were used as parameters of the POD model. Hit (detection) and miss (no detection) binary data obtained from destructive and nondestructive inspection of cracked tubes were also used.     

Ultrasonic inspections of fuel alignment pins

As a remedy to the practical problem of defects in fuel alignment pins made of Inconel X750, an inspection technique has been developed which fully meets the requirements of detecting defects. The newly used fuel alignment pins made of austenite are easy to test and therefore satisfy the necessity of further inspections.For the fuel alignment pins of the upper core structure a safe and fast inspection technique was made available. The inspection sensitivity is high and it is possible to give quantitative directions concerning defect orientation and depth. After the required inspections had been concluded in 1989, a total of 18 inspections were carried out in various national and international nuclear power plants in the following years. During this time more than 6000 fuel alignment pines were examined.For the fuel alignment pins the inspection technique provided could increase the understanding of the defect process. This technique contributed to the development of an adaptive and economical repair strategy.     

A case study on detection and sizing of defects in steam generator tubes using eddy current testing

Eddy current testing (ECT) method is widely used to detect various types of defects occurring in nuclear steam generator tubes. Therefore, the reliability of its detection and sizing accuracy for defects should be validated. For this purpose, two tubes with defect signals were pulled from an operating steam generator and destructively examined. The defect type was a circumferential crack for one tube and an intergranular attack (IGA) for the other tube. The plus point coil probe showed a better capability to detect and size both a circumferential crack and a volumetric IGA than pancake and bobbin coil probe. The destructive results are correlated with the ECT results obtained during the in-service inspection.     

Swedish approach and experience with inspections of austenitic components in the primary circuit of BWR's

It is essential to know why an inspection is required and what type and size of flaw is expected to be detected. A very basic knowledge it seems. However, many national codes and standards are not fully adequate in this respect. The selection of inspection items as well as the acceptance criteria of detected defects are often defined in very general terms. Degradation processes are very little reflected in the standard ISI selection scope which creates demands on additional inspection programs. The swedish authority, the Swedish Nuclear Power Inspectorate (SKI) have issued a new code for in-service inspections which deals with this issues. This paper describes the basics of the new code, the implementation and the experience gained from in plant inspections at Barsebäck Nuclear Power plant.     

Requirements related to in-service inspection of reactor vessels

The in-service inspection of nuclear facilities should make it possible to detect all flaws capable of deterioration. The size of a flaw is not normally characteristic of its seriousness: a large, stable defect which is not developing is of no importance for the safety of the facility whereas a small but developing defect may be dangerous and hence of importance for safety. It is essential to detect all defects, so that any development they may be undergoing can be assessed, and to use, for that purpose, a technique with a maximum detection probability; but the main thing is to characterize all developing defects. For the in-service inspection of pressurized-water reactor vessels the “Commissariat à l'Energie Atomique” has conducted studies on inspection methods with a view to ensuring first the best possible detection and secondly the best possible characterization of flaws. Since 1973 many publications have appeared on the subject and this paper will only recall the essentials giving particular attention however to the characterization of defects, which is the principal purpose of the studies currently being conducted.     

The effect of inspection and repair on the size distributions of the weld imperfections in nuclear power plant pipes

The weld defects appearing in the pipes of the main steam system in a BWR power plant were studied. The effect of inspection rejection and repair on the imperfection size distribution was analysed. The size distributions before and after the inspection rejection as well as after the repair procedure were of the form a + b/x², where x is the imperfection size and a and b are coefficients. The portion of the rejected defects had the size dependence near to the form of the cumulative Gaussian function. The effect of repair on the initial size distribution had the form of the cumulative Poisson distribution.     

The evaluation of SCC defects of steel pipe using a high-energy X-ray CT sc anner

The X-ray computed CT scanner, capable of producing sharp tomograms, was expected to become a practical and revolutional means in nondestructive inspection in the industrial field.In Japan, the development of the Linac X-ray CT scanner is under way for the inspection of SCC in welds of a nuclear power plant. For development of the Linac-CT, the preliminary experiments for the inspection of SCC artificial defects were performed using a 420 kVp industrial X-ray CT scanner (TOSCANER 4200) which had been developed by Toshiba Corporation. This paper includes the background of this program and the summary of preliminary experiments for X-ray CT.