核电厂应急柴油机动力单元组件损坏原因分析

某核电厂MTU956应急柴油机在月度定期试验中,突发A1-B1缸动力单元组件损坏故障,造成多个组件损伤。其中,主润滑油管道被击穿引起柴油机润滑油压力低,致使保护停机,使电厂遭受巨大经济损失。本文主要通过对损坏组件的材料学全面检测分析,综合分析结论确定A1-B1缸动力单元组件事件发生的根本原因为曲轴制造阶段残留金属异物导致连杆大端轴瓦烧毁,并提出了监测建议,对核电厂应急柴油机运维具有重要意义。     

切尔诺贝利核电站2号机组火灾事故

对１９９１年切尔诺贝利２号核电机组汽轮机厂房火灾原因的调查分析发现，发电机气动隔离断路器故障是由控制线路的短路引起的。很明显该线路早在１９７７年建造期间已经损坏。另外，发电机输出端上没有备用隔离断路器也是发生该事故的原因之一。最近的ＲＢＭＫ设计，如切尔诺贝利３号机组，具有这种部件。     

瑞典专家警告：伊格纳林纳2号机组的关闭可能引发安全问题

【路透社旧金山2001年12月11日电】 美国核管会(NRC)于2001年12月11日确定了13座已经出现或怀疑出现小裂纹(这些小裂纹可能严重损坏电厂设备并导致反应堆长时间停堆修理)的反应堆。 在这13座反应堆中,已在3座反应堆中发现裂纹并进行了修理,2座还有待于检查,并没有迹象表明另外8座有裂纹。在杜克能源公司所属的南卡罗莱纳州的奥科尼2号和3号机组上发现了毛细裂纹,电厂运营者为此更换了反应堆容器封头。 佛罗里达州的克里斯特尔里弗3号机组上也发现了裂纹,并进行了焊接修补。 将检查密歇根州的科克2号机组和俄亥俄州的戴维斯贝瑟机组是否有…     

巴西安格拉1号核电机组发生事故

【欧洲核学会《核新闻网》1992年2月13日报道】据国际核事件分级表(INES)情报系统刚公布的一份报告说,最近巴西的安格拉1号核电机组发生一起核事故,并被列为 INFS 中的2级事件。这一事件导致反应堆余热导出系统倾刻完全失效。这起事故发生在2月7日,当时安格拉1号机组正在进行例行维修和换料,反应堆处在冷停堆状态,而且新的核燃料元件已装入堆芯。空气压缩机的冷却丧失引起了压缩空气的减少,致使余热导出系统的一个阀门完全打开。这导致该系统的泵流量增加。随后,该机组操作人员将此泵关闭,从而避免了此泵的损坏。     

波克什2号机组的燃料破损事故突出了冷却的重要性

【美国《核燃料》2004年3月1日刊报道】 美国核管会(NRC)在2004年2月24日发布的信息通报中指出,2003年发生在波克什2号机组的严重的燃料破损事故突出了对反应堆卸料进行充分冷却的重要性。2004年4月,在化学清洗的过程中,由于冷却不充分,清洗罐中的30个燃料组件以240～270 kW的速度释放出衰变热。在几小时内,蒸汽取代了水环绕在燃料组件周围,燃料温度逐渐上升到将近1000℃。当清洗罐的进口盖密封发生损坏,水流入罐中,使处于高温的燃料组件及其活性段包套发生骤然冷却后,燃料组件发生了破损。操作人员估计,此次燃料破损事故向外界释放了约10…     

“华龙一号”设计中风险指引技术的应用

"华龙一号"作为我国自主研发的三代先进核电机组,在设计中提出了每堆年发生严重堆芯损坏事件的概率(CDF)低于十万分之一以及每堆年发生大量放射性物质释放事件的概率(LRF)低于百万分之一的安全目标,相比法规要求均降低一个量级。为有效提高"华龙一号"安全性,确保两个安全目标的实现,应用以概率安全分析(PSA)风险模型为主要工具的风险指引设计方法,从顶层方案的确定到具体的系统设计等各个环节,通过一系列的风险指引设计工作,识别了核电厂在安全上的薄弱环节,并提出相应的优化建议,为"华龙一号"安全水平的提高和安全目标的最终实现提供了保障。     

“华龙一号”堆型电气厂房冷冻水系统分析及改进

“华龙一号”是我国自主研发的三代核电机组,为降低严重堆芯损坏事件概率（CDF）和每堆年发生大量放射性物质释放事件概率（LRF）,提升核电厂安全水平,“华龙一号”堆型采取了诸多创新性的改进,电气厂房冷冻水系统就在为安全注入系统设置多样化热阱上做了尝试,由此也带来新的问题。文章基于特殊性分析和具体工作实践,对电气厂房冷冻水系统针对性提出若干建议,助力于系统可靠性提升。     

日本滨冈4号和5号机组在地震中自动停堆

【日本《朝日新闻》网站2009年8月11日报道】据日本经济产业省原子能安全保安院称,因受8月11日早晨地震的影响,中部电力公司滨冈核电厂（位于静冈县御前崎市）正在运行的4号机组（1137MW的沸水堆）与5号机组（1267MW的先进沸水堆）自动停堆。核电厂周围的辐射监测器没有测到异常数据,说明没有对外部环境造成放射性影响。     

堆芯过滤装置的设计改进

岭澳核电站3号机组在热态功能试验期间发现多组堆芯过滤装置损坏。本文通过对堆芯过滤装置的失效原因进行分析,针对性地提出了改进方案,并通过机械试验的方式模拟堆芯过滤装置滤网脱落或断裂的失效过程,从而验证了分析结果的准确性以及新型堆芯过滤装置性能的优越性。     

秦二厂2号机组氙振荡抑制方法研究

氙振荡是大型热中子反应堆不可忽视的问题,剧烈的氙振荡给轴向功率控制带来严峻的挑战.本文通过对秦二厂2号机组的氙振荡进行研究分析,发现振荡发散和收敛规律,即在氙振荡过程中,若动棒操作引起轴向功率偏差△I变化与当前△I的变化趋势相反,可以有效地抑制氙振荡,否则将加剧氙振荡.并以秦二厂3号机组的氙振荡中衰减和加剧过程进行验证...     

液态金属螺旋管式直流蒸汽发生器数值模拟研究

螺旋管式直流蒸汽发生器(HCOTSG)是一种蒸汽发生器常用形式。得益于其特殊的优势,HCOTSG被广泛用于各类反应堆动力系统中。本文提出了利用计算流体力学软件（FLUENT）对液态金属HCOTSG的壳侧液态铅铋、管侧两相流体进行耦合流动传热计算的CFD方法,并通过与相关实验研究结果的对比验证了数值模拟方法的正确性。在此基础上,本文对HCOTSG在典型工况下开展了数值模拟计算,得到蒸汽发生器内部的热工水力参数分布情况,并对其内部的流动换热特性进行分析。本研究为液态金属HCOTSG流动换热特性研究及结构设计优化提供新的思路方法。     

New design for multi-crystal data collection at SSRF

Data collection with microcrystals at synchrotron radiation facilities is challenging because it is difficult to harvest and locate microcrystals. Moreover,microcrystals are sensitive to radiation damage; thus, typically, a complete data set cannot be obtained with a single microcrystal. Herein, we report a new method for data collection with multiple microcrystals having a crystal size ranging from 1 to 30 lm. This method is suitable for not only low-temperature(100 K) data collection but also room-temperature data collection. Thin Kapton membranes were used to capture multiple crystals simultaneously. The microcrystals were visible under an optical microscope and easily located because the membrane was transparent and sufficiently thin. The film was fixed to a bracket that was prepared using a three-dimensional printer. The bracket was fixed on a magnetic base via screwing and employed by the goniometer system for data collection. Multiple data sets of fatty acid-binding protein 4(FABP4) and lysozyme microcrystals were collected using this novel designed device. Finally, the structures of protein FABP4 and lysozyme were obtained from these data via the molecule replacement method. The data statistics reveal that this method provides a comparable result to traditional methods such as a nylon loop.     

核电650MW机组励磁机轴颈晃度超标原因分析及处理

秦山二核的发电机与励磁机的连接为三支撑结构形式,即发电机转子有两个轴瓦,励磁机转子只有一个轴瓦支撑,这种结构致使励磁机的轴瓦的晃度在检修时难以达到标准要求的数值。在秦山二核2号机组的第5次检修中,检修完毕回装励磁机时其轴瓦晃度难以达标,影响励磁机晃度不能达标的因素很多,有发电机与励磁机联轴器的对中状态、发电机与励磁机联轴器的紧固螺栓的力矩、发电机联轴器和励磁机联轴器的端面状况、发电机联轴器和励磁机联轴器内孔中的剪切套筒与内孔的配合尺寸。通过对各个因素进行分析并一一排除,最终找出致使励磁机轴瓦晃度大的根本原因是发电机联轴器端面状况异常,对其进行机加工处理后,缺陷得以彻底处理。     

Mechanical properties of 9Cr–1W reduced activation ferritic martensitic steel weldment prepared by electron beam welding process

Microstructure and mechanical properties of the weldments prepared from 9Cr–1W reduced activation ferritic martensitic (RAFM) steel using electron beam welding (EBW) process were studied. Microstructure consists of tempered lath martensite where precipitates decorating the boundaries in post weld heat treated (PWHT) condition. Lath and precipitate sizes were found to be finer in the weld metal than in base metal. Accordingly, hardness of the weld metal was found to be higher than the base metal. Tensile strength of the cross weldment specimen was 684 MPa, which was comparable with the base metal tensile strength of 670 MPa. On the other hand, DBTT of 9Cr–1W weld metal in as-welded condition is similar to that reported for TIG weld metal in PWHT condition.     

Decrease in Power Density due to Finite Electrode Conductivity in Liquid Metal MHD Generator

In the liquid metal MHD power generator, the electric conductivity of the working fluid is so large as to be comparable with that of the electrode. Under such circumstances the perfect conductor approximation no longer holds for the electrode, because the electric potential loses its constancy and acquires a certain pattern of distribution in the electrode as well as in the fluid. The extent of distortion in the electric equipotential lines and lines of force depends on the ratio of conductivity between electrode and fluid, and on the load connection. The power density becomes non-uniform, and furthermore the average power density becomes smaller than in the case of a generator with the perfect conductor electrode.

The effect due to this finite conductivity of the electrode is contrary in trend to that due to end loss, as analyzed by Sutton with both aspect ratio and load factor as parameters.

The results obtained in our present experiments with a mercury blow-down facility have agreed very well with the analysis. A numerical analysis has also been made, with end loss taken into account.     

End Effects in Diagonal Type Nonequilibrium Plasma MHD Generators

The authors investigate the influence of the attenuation of magnetic induction on the current distribution etc. in the end regions of the diagonal type nonequilibrium plasma MHD generator by a two-dimensional analysis. The numerical calculations are made for an example of the cesium-seeded helium. As a result, a suitable attenuation of the magnetic induction can make the current distribution very uniform near the end region of generator duct and has little influence on the current distribution in the central part of generator, and the output electrodes can be used without large ballast resistors. Also the internal resistance of the end region and the current concentration at the output electrode edges decrease with the attenuation of magnetic flux density. By the author's investigation, it is made clear that the output electrodes of the diagonal type nonequilibrium plasma MHD generator should be arranged in the attenuation region of the magnetic induction, since arranging them in the attenuation region of magnetic flux density can become useful for the improvement of the electrical characteristics of generator.     

氡及其子体对大鼠肺组织和外周血的损伤作用

为研究氡及其子体对大鼠肺组织的病理损伤和外周血损伤的生物学效应,以多功能生态氡室对SD大鼠进行氡及其子体染毒,累积染毒剂量分别达60、90、120工作水平月(Working level month,WLM)后,收集外周血,观察外周血中白细胞计数和分类的变化.同时选取右肺及与其相连的支气管,观察大鼠肺及支气管的损伤程度....     

Behaviour of the steam generator tubing in water with different pH values

Steam generators are crucial components of pressurized water reactors. The failure of the steam generator as a result of tube degradation by corrosion has been a major cause of Pressurized Heavy Water Reactor (PHWR) plant unavailability. Steam generator problems have caused major economic losses in terms of lost electricity production through forced unit outages and, in cases of extreme damage, as additional direct cost for large-scale repair or replacement of steam generators.The excellent performance to date of CANDU steam generators can be attributed, in part, to their design and performance characteristics, which typically involve higher recirculation ratios and lower heat fluxes and temperatures. However, the steam generator tubes are susceptible to failure by a variety of mechanisms, the vast majority of which are related to corrosion.The generalized corrosion is an undesirable process because it is accompanied by deposition of the corrosion products which affect the steam generator performances. It is very important to understand the generalized corrosion mechanism with the purpose of evaluating the quantities of corrosion products which exist in the steam generator after a determined period of operation (IAEA, 1997).The purpose of the experimental research consists in the assessment of corrosion behaviour of the tubes material, Incoloy-800, at normal secondary circuit parameters (temperature—260 °C, pressure—5.1 MPa). The testing environment was the demineralised water without impurities, at different pH values regulated with morpholine and cyclohexylamine (all volatile treatment—AVT).The results are presented like micrographics and graphics representing weight loss of metal due to corrosion, corrosion rate, total corrosion products formed, the adherent corrosion products, released corrosion products, release rate of corrosion products and release rate of the metal.     

中子发生器产额稳定性

中子发生器的应用是很广泛的,这是因为中子发生器具有独特的优点:如可关断性和单能性.但是,中子发生器的产额稳定性和开机重复率差,达不到元素分析的领域的要求,电子学自动控制是一种简便易行效果显著的好方法.     

Creep-fatigue evaluation of normalized and tempered modified 9Cr---1Mo

Creep-fatigue is a fatal failure mode of the high temperature structural materials of liquid metal fast breeder reactors (LMFBRs). In this report, two important issues are discussed for creep-fatigue evaluation of normalized and tempered modified 9Cr---1Mo (modified 9Cr---1Mo(NT)) steel which is a promising structural material for the steam generator of large-scale LMFBRs in Japan. Several evaluation methods based on the ductility exhaustion concept are discussed for the prediction of tension strain hold creep-fatigue damage of this material. A time-fraction type of linear damage summation concept based on a new ductility exhaustion theory is proposed from the point of view of its appropriate conservatism for time extrapolation and its simplicity.Also, a life reduction mechanism of low cycle fatigue with strain hold at the compression side is discussed, based on the data observed by a scanning type electron microscope. Creep damage or the tension mean stress caused by compression strain hold hardly reduce the low cycle fatigue life of this material. A new concept based on the location of oxidation on the test specimen surface can explain the reduction in low cycle fatigue life of modified 9Cr-1Mo(NT) steel.