新型控制棒可动线圈电磁驱动线落棒试验

为检验新型控制棒可动线圈电磁驱动线的综合性能,进行了该控制棒驱动线的落棒试验.测量了密封筒内的衔铁及筒外的可动电磁线圈之间的跟随特性、断交流和断直流状态下的快速落棒时间,并对控制棒导向管和控制棒组件之间摩擦方式变化时落棒时间的变化、球阀对控制棒驱动线落棒时间的影响等进行了研究,得到了该控制棒驱动线在不同状态下的落棒时间以及影响快速落棒时间的综合因素等试验数据.试验研究结果可为该驱动线的调试及安全运行提供借鉴.     

高温气冷堆控制棒驱动机构冷态落棒试验研究

高温气冷堆控制棒驱动机构是执行反应堆功率调节、紧急停堆的重要核安全设备,具有固有安全特性,当断电后,控制棒能够靠重力快速下落实现停堆。为验证控制棒驱动机构的可靠性,必须对其进行设计分析和试验验证。本文建立了全尺寸的冷态试验台架,并采用1:1的控制棒驱动机构样机,对高温气冷堆控制棒驱动机构的落棒功能进行了验证和分析。进行多次全行程及不同高度的落棒实验,验证落棒过程的稳定性,测定控制棒在冷态条件下的落棒时间、落棒速度,试验结果满足规定的限值。对落棒过程进行分析,建立落棒运动方程式,进而得到控制棒运行速度的解析解。理论及试验的结果符合较好,均表明本文研究的控制棒驱动机构落棒可靠具有固有安全特性,为商用高温气冷堆中的实践应用提供了理论依据。     

核反应堆控制棒驱动机构落棒历程计算

以控制棒驱动机构为研究对象,对其落棒历程进行运动学建模、落棒体受力分析及计算。同时,提出相关转动部件转动惯量的折算办法及电机随动过程中所产生制动力矩的处理办法,编制落棒计算的通用程序,实现了落棒历程中各影响因素时变规律的全程监控。计算结果显示:控制棒驱动机构的设计方案满足反应堆总体设计对其的时间、止动坐标方面的要求;电机最大制动力矩低于电机设计方案的额定制动力矩,验证了控制棒驱动机构现阶段总体方案设计的合理性。     

AP1000控制棒驱动线落棒试验研究

采用1组全尺寸AP1000控制棒驱动线进行落棒试验,研究不同纵向流和横向流以及错位和变形对落棒时间的影响,并用高速摄像图像处理技术获得落棒行程速度曲线。试验结果表明,纵向流量是影响驱动线落棒时间的主要因素;在本试验范围内横向流以及部件的错位变形对AP1000控制棒驱动线落棒时间的影响都较为有限。     

CF系列燃料组件落棒性能综合评价

核电压水堆燃料组件中导向管主要功能是为控制棒组件的快速下插提供通道,并且依靠导向管下部缓冲段结构减缓控制棒下落速度,减小冲击力,保证燃料组件结构完整。首先运用落棒时程分析程序(CIGAL)计算得到CF系列燃料组件落棒时间,再利用落棒缓冲分析程序(SAM)计算CF系列燃料组件中缓冲过程冲击力。结果表明:CF3相对于CF2,随着导向管内径减小以及轴肩螺钉孔长度增加,落棒时间变长;落棒过程中缓冲段内压强最大值增大;控制棒组件对燃料组件上管座冲击力最大值减小;控制棒组件撞击之前控制棒在缓冲段内运动时间变长。     

控制棒水压驱动系统冷态性能实验研究

控制棒水压驱动系统是清华大学为低温核供热堆NHR200发明的新型的内置式控制棒驱动技术,该驱动系统由水压驱动机构、组合阀、控制棒和缓冲器等组成。控制棒水压驱动系统冷态性能是控制棒步进时间和系统驱动压力选取的基础。本文分析了控制棒水压驱动系统的组成和工作原理,完成了全尺寸控制棒水压驱动系统冷态性能实验,包括水压缸最小落棒压力实验、提升缸带载步进实验和快速落棒实验等。在实验结果的基础上分析了关键特性参数的变化规律和机理。结果表明：最小落棒压力是保持驱动机构销爪正常工作所需的最小驱动压力,其对应于压力时程曲线上峰值波动过程的变化起点;步升和步降过程压力拐点分别对应位移到位点,随着驱动水压的增加,水压缸充压拐点压力逐渐增加,步升时间、充压拐点时间逐渐减少。实验研究成果为控制棒水压驱动系统的设计、优化和工程应用奠定基础。     

控制棒驱动机构电流响应特性分析

控制棒驱动机构的提升与下插动作需要钩爪部件与3个电磁线圈配合完成,对线圈电流的动态响应过程要求较为严格。采用Simulink软件搭建控制棒驱动机构棒控系统与线圈部件的等效回路,计算分析控制棒驱动机构线圈电阻、电感、端电压等因素对线圈电流响应时间的影响;采用电磁分析软件MAGNET对移动线圈中电流的变化过程进行仿真分析。最终得到控制棒驱动机构线圈电流响应时间与线圈端电压、线圈等效电感、电阻以及棒控回路形式的关系。     

研究堆控制棒通道冷却剂流动阻力特性实验研究

可移动线圈电磁驱动机构是一种新型的控制棒驱动机构,应用于研究堆.控制棒、跟随组件等在控制棒通道内上下移动,同时冷却剂冲刷控制棒和跟随组件.所以控制棒通道内的流体阻力特性直接关系到整个堆芯的流量分配和控制棒跟随组件是否能得到足够的冷却.在进行了控制棒通道的阻力特性实验后,得到了多种运行工况下阻力与流速、棒位等参数的关系,以及影响驱动线阻力特性的因素.     

基于动网格技术的超临界水冷堆控制棒落棒及缓冲分析

基于流体动力学(CFD)的动网格技术,对超临界水冷堆(SCWR)控制棒落棒行为进行动力学仿真分析,通过计算获得了控制棒落棒的特性参数及特性曲线。结果表明,控制棒落棒时间能满足反应堆安全分析的要求,但过大的落棒冲击会导致控制棒驱动线结构产生损坏。基于此结果,进一步对控制棒驱动线结构进行了优化设计研究,增设了水力缓冲结构,从而有效降低了控制棒落棒末速度。     

控制棒水压驱动系统落棒减速性能实验研究

控制棒水压驱动系统是清华大学为低温核供热堆发明的新型的内置式控制棒驱动技术,控制棒水力减速部件是水压驱动系统的关键部件之一,通过其对控制棒落棒过程进行减速,在保证落棒时间的前提下,降低控制棒快速落棒过程的冲击力。分析了水力减速部件组成和工作原理,确定了水力减速箱侧壁开孔方案,完成了不同开孔方案工况下控制棒水压驱动系统冷态落棒减速性能实验,在实验结果的基础上对比和分析了不同方案下的落棒减速机理和落棒过程特征参数随开孔方案的变化规律。分析结果表明:随开孔面积的增大,落棒时间逐渐减小,落棒峰值速度逐渐增大。在开孔面积大于0.004 m~2时,随开孔面积的增大,落棒峰值速度增大过程趋于平缓,落棒稳定速度和落棒延迟时间变化不大,控制棒触碰碟簧速度缓慢增大。实验研究成果为控制棒水压驱动系统落棒减速部件的理论建模和设计优化提供了基础。     

控制棒水压驱动系统落棒减速部件三维流场分析

控制棒水压驱动系统是清华大学为低温核供热堆研制的新型内置式控制棒驱动技术,控制棒水力减速部件是水压驱动系统的关键部件之一,在保证落棒时间的前提下,通过其对落棒过程进行减速,降低控制棒快速落棒过程的冲击力,避免控制棒十字翼的变形和损坏。本文分析了控制棒水压驱动系统落棒减速机理,利用CFD软件FLUENT对驱动系统水力减速箱流道进行了三维流场数值分析,并分析了对应不同落棒位置水力减速箱流道在不同边界条件下的流场分布特性。在流场分析结果的基础上计算得到了水力减速箱侧壁孔流道和底部缓冲腔流道流量系数随落棒位移的变化,将该结果与驱动系统落棒减速理论模型联立,获得了控制棒落棒位移曲线,理论计算结果同冷态落棒性能实验结果符合得很好,从而验证了流场分析结果的正确性,在此基础上分析了落棒过程减速箱内外差压和落棒速度与水力减速箱流量系数的关系,为控制棒水压驱动系统落棒减速部件的设计和优化提供了指导。     

空间核动力装置控制鼓系统试验样机快速复位时间测量方法研究

控制鼓系统是空间核动力装置上执行功率调节、紧急停堆的重要安全级设备,其能否正常运行直接关系到核动力装置的安全性。为测试控制鼓系统的快速复位时间,通过分析控制鼓系统的转动和传动过程,提出了快速复位零点判断、计算复位时间的方法。采用1∶1全尺寸控制鼓系统试验样机和综合测试平台,对快速复位时间进行了实测试验。试验结果表明,该测试方法是真实、有效、可靠的,可应用于控制鼓系统各阶段研发、使用过程中快速复位时间的测量。同时也验证了控制鼓系统的设计满足设计指标,机械快速复位时间小于1 s。     

Study on Scram Time Measurement Method of Control Drum System Experimental Prototype of Space Nuclear Power Device

The control drum system is important safety level device for power regulation and emergency shutdown of the space nuclear power device. The safety of the reactor directly depends on whether the control drum system can operate well or not. In order to test the scram time of the control drum system, a method of judging the zero position and calculating the scram time was proposed by analyzing the rotation and transmission process of the control drum system. The full-scale model of the control drum system experimental prototype and a comprehensive test platform were used to test the scram time. The test results show that the test method is real, effective and reliable, and can be applied to the measurement of scram time in the development and use of control drum system at all stages. At the same time, it is also verified that the design of the control drum system meets the design target that the mechanical scram time is less than 1 s.     

Scram and nonlinear reactor system seismic analysis for a liquid metal fast reactor

Earthquake vibrations cause large forces and stresses that can significantly increase the scram time required for safe shutdown of a nuclear reactor. The horizontal deflections of the reactor system components cause impact between the control rods and their guide tubes and ducts. The resulting frictional forces, in addition to other operational forces, delay the travel time of the control rods. To obtain seismic responses of the various reactor system components (for which a linear response spectrum analysis is considered inadequate) and to predict the control rod drop time, a non-linear seismic time history analysis is required. Nonlinearities occur due to the clearances or gaps between various components. When the relative motion of adjacent components is large enough to close the gaps, impact takes place with large impact accelerations and forces.This paper presents the analysis and results for a liquid metal fast rector system which was analyzed for both scram times and seismic responses such as bending moments, accelerations and forces. The reactor system was represented with a one-dimensional nonlinear mathematical model with two degrees of freedom per node (translational and rotational). The model was developed to incorporate as many reactor components as possible without exceeding computer limitations. It consists of 12 reactor components with a total of 71 nodes, 69 beam and pin-jointed elements and 27 gap elements. The gap elements were defined by their clearances, impact spring constants and impact damping constants based on a 50% co-efficient of restitution.The horizontal excitation input to the model was the response of the containment building at the location of the reactor vessel supports. It consists of a 10 sec safe shutdown eathquake (SSE) acceleration-time history at 0.005 sec intervals and with a maximum acceleration of 0.408 g. The analysis was performed with two Westinghouse special purpose computer programs. The first program calculated the reactor system seismic responses and stored the impact forces on tape. The impact forces on the control rod driveline were converted into vertical frictional forces by multiplying them by a coefficient of friction, and then these were used by the second program for the scram time determination.The results give time history plots of various seismic responses, and plots of scram times as a function of control rod travel distance for the most critical scram initiation times. The total scram time considering the effects of the earthquake was still acceptable but about four times longer than that calculated without the eathquake. The bending moment and shear force responses were used as input for the structural analysis (stresses, deflections, fatigue) of the various components, in combination with the other applicable loading conditions.     

In-vessel Type Control Rod Drive Mechanism Using Magnetic Force Latching for a Very Small Reactor

A highly reliable control rod drive mechanism driven by an electric motor installed inside the reactor vessel (INV- CRDM) for a very small reactor has been designed. The INV-CRDM contributes to the compactness and simplicity of the reactor system, and can eliminate the possibility of a rod ejection accident. In the design, a new type of latch mechanism using an electromagnetic force to directly connect both of the shafts, one of which was the motor driven shaft and the other the control rod driving shaft, was applied so as to make the INV-CRDM very compact. The cable supplying current remained stationary, even when both of the shafts was moving. The required functions of the latch mechanism are to maintain an adequate latching force for the control rod shaft to move within a stroke of 370 mm, and to release the shafts in a shorter time than 0.2 s after a scram signal is received. A functional test with a model that approximately simulated the design was conducted to test the latching force and de-latching at room temperature. The test showed that the latching force increased with the current of the magnet coil, as did the de-latch time. The post-test analysis with a finite element analysis code revealed that the clearance between the two shafts greatly affected the latching force. With the same analysis method, the design analysis of the latch mechanism at a high temperature condition of 300°C was conducted, and it was confirmed that the latch mechanism contained enough latching force.     

Estimation of break location and size for loss of coolant accidents using neural networks

In this work, a probabilistic neural network (PNN) that has been applied well to the classification problems is used in order to identify the break locations of loss of coolant accidents (LOCA) such as hot-leg, cold-leg and steam generator tubes. Also, a fuzzy neural network (FNN) is designed to estimate the break size. The inputs to PNN and FNN are time-integrated values obtained by integrating measurement signals during a short time interval after reactor scram. An automatic structure constructor for the fuzzy neural network automatically selects the input variables from the time-integrated values of many measured signals, and optimizes the number of rules and its related parameters. It is verified that the proposed algorithm identifies very well the break locations of LOCAs and also, estimate their break size accurately.     

控制棒驱动机构响应时间测试与数据分析

针对控制棒驱动机构（CRDM）机电响应时间快且测试环境存在噪声干扰等问题,搭建了一套集PXI数据采集硬件平台和MATLAB数据分析的快速机电响应时间测试系统,能够实现对高频控制棒棒位实时信号的快速采集。利用滑动平均滤波和分区间拟合方法对棒位位移信号进行滤波和拟合,并利用快速傅里叶变换（FFT）频谱分析法验证去噪效果。结果表明,本套测试系统能被成功应用于钍基熔盐液态堆（TMSR-LF1）第一停堆系统CRDM的机电响应时间测试中,在可行性、可靠性和可用性等方面均满足CRDM机电响应时间测试要求。      

Investigations of Tracking Phenomena in Silicone Rubber Using Moving Average Current Technique

In the present work, tracking phenomenon in Silicone rubber material has been studied under AC and DC voltage, with ammonium chloride as a contaminant. It is observed that the tracking is more severe under the DC voltages. The tracking time is less under negative DC compared to the positive DC voltage. The tracking mechanism is explained in detail. The leakage current during the tracking studies was as measured and the moving average technique was adopted to understand the trend in current flow. The leakage current magnitude is high with thermally aged specimens compared to the virgin specimen, irrespective of the type of applied voltage. It is realized that the tracking time and the leakage current magnitude shows an inverse relationship.