A study on the stem friction coefficient behavior of motor-operated valves

This paper describes how to calculate the stem friction coefficient of safety related motor operated valves (MOVs) that reflects potential degradation with time by using diagnostic signals acquired in static field tests that have been conducted more than two times per valve. Based on the calculated stem friction coefficients, their behaviors with time were analyzed considering various parameters that could cause potential degradation. Most friction coefficients change randomly rather than increasing or decreasing continuously over time. From those trends, a threshold coefficient, which represents the highest expected value of the friction coefficient, was calculated and provided.     

Application of signature analysis for determining the operational readiness of motor-operated valves under blowdown test conditions

In support of the NRC-funded Nuclear Plant Aging Research (NPAR) program, Oak Ridge National Laboratory (ORNL) has carried out a comprehensive aging assessment of motor-operated valves (MOVs).As part of this work, ORNL participated in the gate valve flow interruption blowdown (GVFJB) tests carried out in Huntsville, Alabama, The tests provided an excellent opportunity to evaluate signature analysis methods for determining the operability of MOVs under accident conditions.ORNL acquired motor current and torque switch shaft angular position signauresnon two test MOVs during several GVFIB tests. The reduction in operating “margin” of both MOVs due to the presence of additional value running loads imposed by high flow was clearly observed in motor current and troque switch angular signatures. In addition, the effects of differential pressure, fluid temperature, and line voltage on MOV operations were observed and more clearly understood as a result of utilizing the signature analysis techniques.     

在役核电厂人员闸门传动齿轮优化改进

采用ANSYS有限元分析程序,对国内某在役核电厂人员闸门断齿传动齿轮进行了应力分析,找出了传动齿轮断齿失效的根本原因:传递扭矩过大而引起齿轮过载,应力计算值超过了材料许用应力限值,致使传动齿轮产生根切断齿事故。结合传动齿轮断齿失效根本原因,从材料选择和结构设计2个方面对传动齿轮进行了优化改进。应力分析与评定结果显示,优化改进后的传动齿轮和与之配合的扇形齿轮应力计算值均小于材料许用应力限值,优化改进方案有效降低了传动齿轮的应力水平,有效提高了人员闸门齿轮传动操作的安全性和可靠性。      

在役核电厂人员闸门传动齿轮优化改进

ANSYS finite element analysis program was used to analyze the stresses of the transmission gear for an in-service nuclear power plant in China, and the causes for tooth rupture were found. The transmission torque was so large that the calculated stress exceeded the allowable stress limit of the material, which caused a root rupture accident of the transmission gear. Combined with the causes of tooth rupture for transmission gear, optimization was performed based on material selection and structural improving design. The optimized design scheme passed stress analysis and evaluation. The results show that the calculated stresses of the optimized transmission gear and the sector gear were smaller than the allowable stress limits of the material. The optimized scheme effectively reduced the stress level of the transmission gear, and obviously improved the safety and reliability of the transmission gear operation for personnel airlock.     

核电厂反应堆主泵推力轴承启动阻力矩测试方法

为了获得核电厂反应堆主泵推力轴承在寿期内的极限启动阻力矩,确保执行事故余热排出功能的辅助电机可以在极端工况启动主泵,提出了推力轴承启动阻力矩（指启动瞬间的阻力矩）的测试方法并设计了试验装置,采用正交试验法对影响推力轴承启动阻力矩的3个影响因素（粗糙度、比压、润滑油温）进行研究,采用单因素法测试不同停机时间（指静止加载时间）对推力轴承启动阻力矩的影响,研究表明3个影响因素在规定的控制范围内变化时,启动阻力矩变化较小,而停机时间对推力轴承启动阻力矩影响较大。基于试验确定的极限启动阻力矩开展辅助电机设计,通过了推力轴承样机与主泵样机的反复启停试验验证。本文研究可为辅助电机启动阻力矩的设计提供准确可靠的输入。      

启停对推力轴承可靠性与阻力矩的影响测试

为了测试反复启停对钠冷快堆（SFR）一回路主泵推力轴承可靠性和阻力矩的影响，采用适用于小样本的分散系数法设计了可靠性统计方案，制造了3套巴氏合金推力瓦和1台上部组合轴承样机，设计并搭建了试验台，测试了启动阻力矩随停机加载时间的变化情况，模拟推力轴承的真实情况并开展了反复启停试验。试验研究表明，启动阻力矩均会随着停机加载时间的延长而不断增大；反复启停对推力瓦的磨损寿命影响较小，置信度0.9时，推力轴承启停125次不发生失效的可靠度超过0.99996；反复启停会影响推力轴承的阻力矩，随着启动次数的增多，推力轴承的阻力矩呈缓慢上升趋势，证明开展主泵电机启动能力设计时，必须要考虑启停次数的影响。本文研究可为主泵电机启动能力设计提供参考。      

Seismic qualification of motor operated valves—alternate approach

This paper presents a potential alternate method for determining operating capacity of motor-operated valves subjected to seismic and other applicable loadings. As a result of programs at nuclear facilities to ensure the operational capability of MOVs (under NRC GL89-10), extensive analytical focus to develop the structural capability of valves has ensued. In the past, seismic qualification of valves typically addressed the strength of the topwork structure to resist inertial loading from excitation of the large valve actuator mass. These evaluations paid little or no consideration to the loading resulting from valve closing forces. The focus of the recent efforts is to develop the maximum operational capability of the valve, in terms of thrust, with consideration of seismic and other services loading as applicable. The alternate method outlined in this paper presents a series of thrust capacity curves, with reduction factors for seismic loading which can be applied and developed to determine safe thrust loadings without performing extensive analytical effort. A similar approach was put forward by the SQUG GIP approach to MOVs to ensure the safe operation of valves based on past earthquake experience. However, the GIP approach cannot be used to determine safe operational loads and thus has limited use in the necessary analysis required for GL89-10 programs at nuclear facilities.     

EAST ICRF天线驱动结构改进设计

针对ICRF天线原有的驱动结构由于无自锁而导致天线移动过程中无法精确定位的缺点,给出了两种新的驱动结构设计方案,两种方案主要由步进电机和涡轮蜗杆减速器组成,均具有启动速度慢,推、拉力大,能精确定位的特点。在设计过程中,对两种驱动结构的启动转矩、丝杠的强度和稳定性进行了校核,通过理论计算分析,两种驱动结构设计均满足设计要求。整个驱动结构改进设计方案和方法可为其他同类装置提供有益的借鉴。     

氡子体探测效率的测定

在放射性测量中,应该用待测核素的标准源测定其探测效率,然而,氡子体短半衰期衰变的特点无法制备其标准源,国内外至今还是个有待解决的问题。本文详细介绍了现场抽取氡子体样品测定其效率的新方法。假定源与探测器距离为零射,探测器对各种能量α粒子的效率均相同,则根据放射性衰变规律,由对标准源的效率就能计算出氡子体的探测效率。本文首次提出了解决这一难题的好办法,并已在实际工作中得到广泛应用。     

Incipient fault detection of motor-operated valves using wavelet transform analysis

The necessity of improvements in monitoring and diagnosis methods started to be of extreme relevance in the predictive maintenance field, establishing the reliability and readiness of system components as an achievable goal. Taking into account these reasons, this paper presents an approach for incipient fault detection of motor-operated valves (MOVs) using wavelet transforms. The technique applied in this paper is the wavelet transform analysis using wavelet toolbox, where the main goal is to obtain more detailed information contained in the measured data, identifying and characterizing the transient phenomena in the time and frequency domains, correlating them to failure situations in the incipient stage. The wavelet analysis has provided good results establishing a new qualitative methodology for monitoring and diagnostics of motor-operated valves.     

AP1000核电站海水循环泵可运行性分析

建立了AP1000立式循环泵机组的整机有限元模型，采用响应谱法针对循环泵在设计地震载荷工况下的强度及其动、静部件的变形位移进行了分析，并对该泵在设计地震载荷工况下的结构完整性和可运行性进行了评估。分析结果显示，该泵的1阶横向弯曲振动频率为14.4 Hz，在单位水平激励载荷下，其前4阶振型在模型中的有效质量分数达0.94。在设计地震载荷工况下，作为主承压部件的泵体最大组合应力为203 MPa，叶轮室段壳体最大变形位移不超过1.5 mm，转子部件最大组合应力为 1.7 MPa，最大变形位移为0.8 mm，该系列响应值均在循环泵设计允许范围内，分析结果显示该泵能满足结构完整性和可运行性的要求。     

秦山第二核电厂RIC系统探测器校刻因子算法研究

秦山第二核电厂堆芯功率分布测量试验使用堆芯仪表系统(RIC系统)的4个移动微型裂变电离室入堆进行测量。由于制造公差以及探测器辐照历史不同等原因,4个微型裂变电离室的探测效率各不相同。为计算探测器之间探测效率的校刻因子,一般使用参考通道校刻法和交叉通道互校法。本文给出了几种校刻因子计算方法,并将所计算的校刻因子结果与法国CARIN程序校刻因子的计算结果进行了比对。     

秦山第二核电厂RIC系统探测器校刻因子算法研究

秦山第二核电厂堆芯功率分布测量试验使用RIC系统的4个移动微型裂变电离室入堆进行测量。由于制造公差以及探测器辐照历史不同等原因,4个微型裂变电离室的探测效率各不相同。为了计算探测器之间探测效率的校刻因子,一般使用参考通道校刻法和交叉通道互校法。本文给出了几种校刻因子计算方法,并将所计算的校刻因子结果与法国CARIN程序...     

60Co辐照装置剂量场均匀性的优化设计

采用蒙特卡罗方法和MATLAB(Matrix Laboratory)程序对由576根钴源构成的辐照装置中剂量场均匀性进行优化设计.首先将程序计算结果与实验测量进行比较,接着对程序设置3200个计算点计算了辐照装置的剂量场分布;剂量场均匀性计算中,不断地改变钴源棒位置并不断计算空间平面剂量场.计算结果发现,程序计算值与实验测量值较为一致,经调整后装置的空间剂量均匀度显著提高,使得辐照装置的能量使用率大大提高.     

100 MeV质子降能材料的选择研究

降能器对于提升质子单粒子效应（SEE）地面模拟试验的效率具有重要意义,而降能材料的选择是降能器设计中的首要问题。计算了100 MeV质子在4种常见降能材料铍、石墨、铝、铜中产生的能量岐离、角度岐离、中子本底以及感生放射性等对质子SEE地面模拟试验有影响的4个方面,其中感生放射性的计算中包含了降能过程在材料中产生的放射性核素种类、活度及残余剂量率。根据以上计算结果,并结合质子SEE地面模拟试验的要求,在降低相同的能量这一情况下,对4种材料作为100 MeV质子降能材料的适用性进行了分析比较,最终选择铝作为100 MeV质子的降能材料,并将应用在中国原子能科学研究院100 MeV质子回旋加速器的质子SEE地面模拟试验装置的降能器设计中。     

Controlled magnetohydrodynamic mode sustainment in the reversed-field pinch: Theory, design and experiments

A novel control system design for magnetohydrodynamic (MHD) resistive-wall mode (RWM) stabilization is developed from the viewpoint of process control. The engineering approach assumed consists of system identification, selection of feedback interconnections, and subsequently, associated feedback gain tuning. A design for general output tracking is devised, implemented and experimentally verified to be capable of sustaining MHD modes in the reversed-field pinch (RFP) machine EXTRAP-T2R. In principle, by active feedback, the plasma column boundary is forced to ‘user-specified’ helicities of prescribed amplitudes and phases. Experimental success is mainly attributed to careful identification of local magnetic field diffusion time-constants, and individual actuator channel peripheral dynamics. Addition of functionality and key features of this new MHD feedback system software might provide a versatile tool for experimental plasma dynamics and innovative MHD stability research.     

Pinhole collimator design for nuclear survey system

A conventional knife-edge collimator, which is widely used in gamma camera for medical diagnosis, is not suitable for nuclear imaging system because many scattering radiations near the pinhole aperture happen and blur image. A new pinhole collimator, which shapes a channeled aperture for reducing image degradation induced by the scattering radiations, is introduced and its characteristics are analyzed by Monte Carlo simulation. Resolutions defined as the full-width at half-maximum (FWHM) of point spread function and efficiencies are calculated about several pinhole diameters from 4 to 8 mm and channel heights from 2 to 10 mm. For this calculation, we assumed that ¹³⁷Cs radiation sources with 662 keV mono-energies enter into our designed collimator at the 1 m distance from the detector plane. The efficiencies and resolutions of the channeled collimator are compared with those of the conventional collimator. By comparison results, it is verified that the new collimator takes advantage more than the conventional collimator. The optimum channel height and diameter of the pinhole collimator from simulation results are also proposed and designed. We finally acquired nuclear image mounting this collimator in the nuclear survey system.     

Rotor performance enhancement by alternating current dielectric barrier discharge plasma actuation

An experimental system was established to explore the plasma flow control effect for helicopter rotors in hover mode.With the plasma actuator applied at the leading edge of the rotor blades,alternating current dielectric barrier discharge(AC-DBD) plasma actuation was generated by a sinusoidal AC high-voltage generator.By direct force measurement,the influence of actuation parameters on the aerodynamic performance of the rotor was investigated at a tip Reynolds number of 1.7 × 10⁵.AC-D...     

CEFR 100%额定功率运行汽轮机发电能力分析

中国实验快堆(CEFR)首次100%额定功率发电运行中,实际电功率较设计值相差较多。为判断影响机组实际发电能力的主要原因,以现场采集的运行数据和汽轮机厂商提供的设计资料为基础,进行了相应的计算分析。对汽轮机内效率进行修正,绘制汽轮机近似热力过程曲线,并通过实测的各段抽汽压力,在热力过程曲线上获得抽汽焓值;利用换热器的能量守恒和流量守恒的基本方程进行除氧器和各加热器的热平衡计算,获得各段抽汽的流量;利用汽轮机的功率计算方程,得到汽轮机发电功率的计算值。通过计算值与实际值的比较分析,得出主蒸汽参数不达标是影响CEFR汽轮机发电能力的主要因素。     

An improved method for reactor coolant pump abnormality monitoring using power line signal analysis

An improved method to detect the reactor coolant pump (RCP) abnormality is suggested in this work. The monitoring parameters that are acquired from power line signal analysis are motor torque, motor speed and characteristic harmonic frequencies. The combination of Wigner–Ville Distribution (WVD) and feature area matrix comparison method is used for abnormality diagnosis. For validation of the proposed method, the test was performed during cool-down phase and heat-up phase in nuclear power plant (NPP) by cross-comparison with RCP vibration monitoring system (VMS). Using pump internal inspection results, the diagnosis prediction is verified.