Application of an integrated power line signal analysis methodology to the detection of major rotating machine abnormalities in nuclear power plants

An integrated and improved method to detect and identify the abnormality of motor driven rotating machinery in nuclear power plants (NPPs) using power line signal analysis is suggested in this work. The primary goal of this work is to improve the motor current signature analysis (MCSA) method that has been used as an alternative or supplement of the conventional vibration monitoring system (VMS). Through this work, the integrated system using both modulated flux density model (MFDM) and rotating flux model (RFM) is proposed. The MFDM is based on the fact that the major mechanical vibration of rotating machines can be normalized to the motor air-gap eccentricity and the modulation of air-gap flux density. Therefore, if the major defect such as bearing defect or the shaft deformation is present, it is identifiable through the power line signal resulting from the modulated magnetic density. Moreover, the broken rotor bar state or rotor eccentricity due to electrical imbalance can be analyzed using the RFM. The other important feature of this system is an automated abnormality detection and diagnosis algorithm. It is possible to diagnose the abnormality without relying on experts in NPPs. The verification is done through varying load/torque test experiment as well as via computer simulation in this work. The experimental results show that they are in good agreement with the simulated results.     

在役AP1000主泵锁紧杯断裂故障原因分析

三门核电厂2号机组首循环连续运行期间,发生了大型屏蔽电机主泵故障事件,导致机组停运。为分析主泵故障发生的原因,基于故障特点和原因分析方法论,制定了主泵故障排查的根本原因分析方法;通过排查主泵制造记录、评估现场运行数据、拆检取证、设计分析与试验验证、根本原因分析评估,最终确认主泵故障原因是下推力盘锁紧杯受周围流场流体激励作用发生局部共振,初始缺陷在共振作用下持续扩展并最终导致锁紧杯断裂,进而磨穿主泵屏蔽套并导致主泵故障。本研究建立的根本原因分析方法可为同类问题的原因分析和问题处理提供参考。      

核电厂主泵倒流工况转子动态特性分析与研究

为防止核电厂主泵在反应堆冷却剂倒流产生的冲击载荷作用下发生反转,在电机上设置了由恢复弹簧和液压缓冲器组成的棘爪式防倒转装置。根据防倒转装置的结构特点及其工作原理,建立了防倒转装置的理论模型和主泵转子的运动学方程,分析了主泵倒流工况转子运动的动态特性,得到了转子的速度-位移运动轨迹。结果表明,由于反应堆冷却剂倒流产生的冲击载荷小于防倒转装置的设计载荷,主泵转子在倒流工况下经历包含6个运动状态的往复运动后,转速逐渐降低直至停止,实现了防止主泵反转的功能。      

基于ARIMA和LSTM组合模型的核电厂主泵状态预测

为了对核电厂主泵的运行过程进行监测和追踪,进而提高主泵的预警能力,提出了基于差分自回归移动平均（ARIMA）和长短期记忆（LSTM）神经网络组合模型的主泵状态预测方法,并用该方法对某核电厂主泵止推轴承温度和可控泄漏流量进行单步和多步预测,以根均方误差（RMSE）为指标对预测精度进行评估。结果表明,所建立的ARIMA和LSTM神经网络组合模型能够对主泵的状态进行准确的预测和追踪,并且组合模型的预测精度要优于ARIMA和LSTM单一模型,尤其在多步预测中,组合模型的优势更加明显。      

压水堆核电站主泵的装配技术和管理

反应堆冷却剂泵（简称主泵）是核电站的关键设备。本文介绍了压水堆核电站主泵的装配结构、装配流程及装配的技术关键点，通过对装配中问题的总结分析，找出了影响主泵装配进度和质量的主要因素，并采取加强装配计划管理、合理安排组织分工、做好装配前技术准备、建立应急处理渠道等措施，有效地提高了装配质量和效率，可为其他核电项目主泵装配管理提供经验参考。      

核电厂主泵密封系统的安装与调试

研究CPR1000堆型核电厂反应堆冷却剂泵(RCP)密封安装工艺流程及方法,对RCP密封系统安装和调试过程中的各种情况进行分析,制定各种情况下核回路冲洗采取的特殊处理方案,为后续CPR1000项目RCP密封系统安装调试提供参考.     

Seismic analysis of a reactor coolant pump by the response spectrum method

Current nuclear steam supply systems (NSSS) are designed to remove the heat of fission by circulating coolant in closed loops from the reactor. For water reactors, this prime function is designated to the reactor coolant pump (RCP). The Westinghouse Type 93A RCP is analyzed for seismic response. Briefly described, this RCP is a vertical, single-stage, centrifugal pump designed to move 90 000 gpm (568 m³/sec) of water and driven by a 6000 hp motor for use in the PWR primary system. The RCP assembly is generally axisymmetric and is modeled using three-dimensional finite elements of the types normally found in general-purpose computer programs such as ANSYS or NASTRAN. The structural frame and the rotating shaft are the principal branches of the model. Each consists of a series of pipe elements complemented by mass elements. Orthogonal sets of linear spring elements connect the branches at the bearings and possibly at each labyrinth. Fluid elements are added to include the interaction between the shaft and the pump case through the intervening water mass. Beam elements are used to account for unsymmetry of the motor stand. To complete the model, stiffness matrix elements representing the support structure and the neighboring loop piping are attached. It is impractical to idealize faithfully each geometric irregularity. Several adjacent sections are combined into one suitable element with total stiffness and equivalence. The number of elements in the model is thus minimized. Shear deflection of the pipe elements is considered; mass and mass inertia are lumped at nodal points, as needed to compensate for the actual material distribution. The RCP model contains 82 nodes, 155 elements and 140 master dynamic degrees of freedom. A modal frequency analysis is first run to identify the mode shapes.The seismic analysis is performed by the response spectrum method in ANSYS, with seismic velocity as the input excitation parameter. The model is excited by a set of three orthogonal spectra. For each load excitation, the modal displacements, forces and moments are computed at each node. A post-run subroutine calculates the absolute sum of nodal response quantities at each mode for one horizontal and the vertical seismic excitations. The resultant modal values are then combined using the square root of the sum of the squares (RSS) to record the final values: SSE X-Y and SSE Y-Z. Nodal stresses are computed; absolute displacements are reviewed for selected nodes along the model branches. The relative displacements at bearings and labyrinths are determined. Finally, the accelerations of nodes previously chosen are found.This paper assesses the effects of a given seismic excitation on the overall structural integrity of an RCP. The in-depth analysis has found the RCP adequate to withstand the imposed seismic loading. All component stresses are within the applicable faulted criteria and the relative movements between closely mated parts fall inside their nominal clearance limits.     

反应堆冷却剂泵动压机械密封的工程开发与应用

反应堆冷却剂泵（以下简称主泵）轴密封由3级相同的动压机械密封串联组成，是主泵的心脏，其泄漏量直接决定主泵能否正常运行。本文提出了一种新型的挤压变形研磨法完成动压机械密封的制造，应用挤压变形工装和金属垫片使静环产生变形，在密封端面研磨出9个波形槽。功能实验表明，新型的机械密封在考核压力下的低压泄漏量满足主泵轴密封的设计要求；压力突变工况下的冲击考核实验表明，新型的动压机械密封摩擦副之间的液膜刚度未发生破坏，未出现密封失效。本文研发的动压机械密封在核电厂的运行状况与实验结果完全吻合，充分证明了该新型动压机械密封具有极高的工程应用可靠性。      

基于核主元分析法的核电厂设备状态监测技术研究

为解决核电厂传统监测手段的局限性，提出将核主元分析法（KPCA）引入核电厂设备在线监测领域中，并设计了监测模型建设方法以及在线监测策略。为验证算法的有效性，将其应用在国内某核电机组电动主给水泵的真实监测案例中。仿真结果表明，KPCA算法可适应核电厂设备监测的要求，能比现有阈值监测手段提供更为早期的故障预警。同时，相比于常规的主元分析法（PCA），KPCA算法能够提取各变量之间的非线性关系，识别出设备不同的运行模式，有效减少误报警。      

主泵电机润滑油损失异常的分析和处理

主泵是核电站的心脏,是反应堆冷却剂系统的主要设备和压力边界之一,承担着确保堆芯传热所需的冷却剂流量的重要功能,运行期间必须保证主泵运行的安全可靠。在第11个燃料循环周期中,主泵A电机出现了润滑油损失异常的状况。为了保证电机正常运行,在功率运行期间进行了5次补油的应急处理。针对这个问题,对主泵电机润滑油损失异常的原因和油气散失通道作出了具体分析,在换料检修过程中对主泵电机进行了解体工作。对解决润滑油损失异常的具体解决方案做出了论述。通过具体检修方案的实施,最终使润滑油异常损失得到了很好的控制。     

基于额定参数的核主泵惰转工况计算模型

针对突发断电事故下的核主泵惰转工况,基于额定参数提出惰转转速与惰转流量特性曲线计算模型,并通过100D型核主泵惰转试验数据对推导的模型予以验证。结果表明,该计算模型可用于核主泵初步设计计算和验证分析。基于该模型进一步得到了核主泵惰转设计准则,并验证了AP1000核主泵设计转动惯量。     

基于核主元分析法的核电厂设备状态监测技术研究

In order to solve the limitations of the traditional monitoring methods for nuclear power plants, this paper proposes to introduce Kernel Principal Component Analysis (KPCA) into the online monitoring field of nuclear power plant equipment, and design the monitoring method and online monitoring strategy. In order to verify the effectiveness of the algorithm, it has been applied in the real monitoring case of the motor driven main feed water pump a nuclear power plant in China. The simulation results show that the KPCA algorithm can adapt to the requirements of nuclear power plant equipment monitoring, and can provide earlier warnings of failure than the existing threshold monitoring methods. At the same time, compared with the conventional PCA algorithm, the KPCA algorithm can extract the nonlinear relationship between variables, identify different operating modes of the device, and effectively reduce false alarms.     

主泵3号密封泄漏流流量计研发

反应堆主泵3号密封泄漏流是监视主泵运行的重要参数之一,核电站正常运行期间,这一泄漏流量很小,且流体是带有放射性的含硼水。目前市场比较成熟的流量计很难满足测量要求。本文针对主泵3号密封泄漏流的这些特点,介绍了一种新型的流量测量方法,新流量计采用容积式测量原理,克服了低流量测量的稳定性差、响应速度慢、精度低、现场液体易产生硼结晶等问题,已在线稳定运行两年时间,对小流量测量有一定的参考价值。     

反应堆主泵压水室出口收缩角对水力性能的影响

针对国内某百万千瓦核反应堆主泵的水力性能要求,完成主泵叶轮和导叶的设计;为研究出口收缩角对水力性能的影响,设计了13种压水室出口收缩角,采用三维软件Pro/E完成了三维造型;利用计算流体力学(CFD)软件Fluent进行定常与非定常三维数值模拟,得到内部流场特性及计算点的压力脉动情况,并对其进行分析。结果表明:收缩角对压水室与出口交接处的前后区域影响显著,收缩角在12°~16°范围内,主泵效率均在70%以上,=15°时效率达最大值74.2%;在=15°且其他结构参数不变的情况下,随着流量的降低,主泵叶轮进口前和导叶出口处回流区域逐渐扩大;随着流量的增加,叶轮进口前回流区域逐渐向叶轮进口偏移;回流是引起压水室与出口交接处压力脉动的主要原因;偏离工况越大,压水室出口处的压力脉动波动越严重。     

核电厂用变频泵振动故障分析及治理

某核电厂在调试过程中一台变频泵发生了某一频率范围内振动大的故障。振动大不利于该泵的长期运行，为此进行敲击试验得出该泵固有频率，并由振动频谱分析确定该泵为结构共振。利用结构共振理论给出了改变电机支架刚度或质量并通过有限元分析计算后调整固有频率的方法，使得变频泵在振动故障治理后振动明显变小且最终符合要求，为转动设备的故障诊断提供了重要参考。      

秦山第二核电厂阀门类设备弱贯穿辐射调查

在秦山第二核电厂8次大修期间,对反应堆冷却剂系统(RCP)、余热排出系统(RRA)、化学和容积控制系统(RCV)、反应堆换料水池和乏燃料水池冷却和处理系统(PTR)4个系统主要阀门的辐射源项和弱贯穿辐射进行了监测。测得RCV系统阀门沉积的放射性核素主要是^110mAg,RCP、RRA和PTR系统阀门内沉积的主要是⁵⁸Co、⁶⁰Co、⁵¹Cr、⁹⁵Nb、⁹⁵Zr等放射性核素,伴随的β射线能量主要在500 keV范围内。测量给出了4类阀门的公式′(0.07)和H·′(3)值,测得H·′(3) /H·^*(10)值在1.24左右,H·′(0.07) /H·^*(10)值在14左右。结合测量结果,给出了部分阀门需要对检修人员开展眼晶体剂量和皮肤剂量监测的建议。     

主泵试验台架振动原因分析与修改方案

反应堆冷却剂泵（简称主泵）在试验台架进行试验时出现振动偏大的现象，振幅超出样机规范书的要求，振动数据的频谱显示为低频振动。通过转子动力学的有限元方法分析了主泵的振动特性，对比振动频谱排除了主泵转子振动和轴承等自身振动的原因。提出了主泵振动特性分析应包括试验台架整体。将主泵、试验回路和试验台架作为整体，分析了整体的振动特性。结合敲击试验推断振动的原因是试验回路中流体压力脉动的宽频激励引发了主泵和试验台架整体振动，并在低速运行试验中进行验证。在此基础上提出了修改方案，包括增加吸能阻尼器、提前投入缓冲罐和滤波等，重启试验后主泵振动明显减小。     

Vibration Cause Analysis and Modification of Prototype Reactor Coolant Pump

When the reactor coolant pump (RCP) was tested on test bench, the vibration amplitude was too large. The vibration exceeded the limit of specification. The frequency in spectrum of RCP vibration was mainly in low frequency range. The vibration characteristics of RCP were analyzed by finite element method. The cause of vibration from bearing and rotor was excluded by comparing the vibration characteristics and the spectrum. It was proposed that the whole test bench should be included in the vibration analysis of RCP. Considering RCP, test loop and test bench as a whole, the vibration characteristics were analyzed. By combining the data from knock test, it is concluded that the wide-band of pressure fluctuation in test loop excites the natural frequency of test bench. This conclusion was verified by low-speed operation test. On this basis modifications were proposed such as adding energy absorption damper, starting buffer tank in advance and adding vibration filter. The vibration of RCP was attenuated obviously after test restarting.     

核电厂立式泵电机多故障耦合振动问题的处理

某核电厂立式水泵配套电机存在两径向方向振动差异大、启机后振动缓慢上升的振动现象，为解决该问题，本文利用频谱分析、固有频率分析、相位分析等方法进行故障诊断，判断出该配套电机存在结构共振、转子热弯曲、动不平衡的耦合问题，并最终通过调整螺栓及现场动平衡方法成功解决了振动问题。      

核电厂主泵轴振异常分析

为解决某核电厂主泵轴振报警问题，对异常现象进行了原因诊断和现场验证。采用对比分析、频谱分析、轴心轨迹分析方法对主泵轴振异常进行研究。分析表明:泵轴振动大于电机轴振动，相同位置测点在水平面内2个不同方向振动基本相当。电机轴Y向振动异常为电缆屏蔽层损坏导致，振动传感器线缆安装宜使用如麻绳等较为软质的材料进行绑扎固定。泵轴振动异常为泵轴存在较大涡动和较高基频成分引起。在泵轴出现较明显的涡动现象时，可提高轴封水抑制泵轴的涡动，以降低泵轴振动。