中国实验快堆辐照容器组件流致振动实验

在水力实验台架上利用DASP-V10振动测量系统对中国实验快堆结构材料辐照容器组件进行流致振动实验。通过实验,得到组件前5阶固有振动特性(固有频率、振型)及额定流量工况(0.6m3/h)和120%额定流量工况下组件的振动响应及动态应变响应。实验以固有振动特性测量结果来指导开展组件在运行工况下的流致振动实验,并根据得到的流致振动结果结合组件固有振动特性从振动力学原理上阐述了辐照容器组件共振现象的产生及其对组件运行的影响。     

矩形通道中两端固定柔性单板湍流微振的研究

平行板燃料组件的流致振动特性研究对于保证核反应堆的安全可靠运行具有重要意义。本文将平行板燃料组件简化成一个在矩形通道中两端固定的柔性单板结构,研究其振动机理,为研究平行板燃料组件的流致振动特性奠定基础。利用加速度传感器等测得实验用铝板的固有频率和弹性模量,使用应变片和激光位移传感器测量平板在不同流速下的振动频率和位移。结果表明：在目前的实验条件下,平板的振动表现为一种由于湍流引起的复杂的随机振动;平板在水中的振动位移随流速的增大而变大;随着流速的增大,平板振动加剧,振动表现为低频成分减少,高频成分增加。     

反应堆堆内构件流致振动特性研究

以某新型工程试验堆为研究对象,采用试验分析与仿真计算相结合的手段探索该试验堆堆内构件流致振动特性。在流致振动试验中,根据相似准则建立了1/2的缩比试验模型,并在整体水力模拟台架上开展了100%额定流量工况下的堆内构件流致振动试验,测量了吊篮组件和二次支承组件在流体作用下的动力响应;根据吊篮组件和二次支承组件所受激励的不同,结合试验结果分别采用不同的计算方法得到了流体力作用下结构的动力响应,分别获得了100%额定流量工况下的最大应力值。     

用激光技术测量燃料组件间水隙及燃料组件中的流速(一维)分布

本实验采用一维前向散射激光多普勒测速仪测量了燃料组件间水隙中及燃料组件棒束间的流速分布。观察到在对应六个导向舌位置存在低速区,在靠近实验段壳体壁面个别部位存在更低的流速区。实验中还测得两个组件对应棒束间流道的无因次流速差不大于3%。最后,对实验结果进行了讨论。     

U3Si2-Al板状燃料组件冲刷试验后的解体研究

通过对U3Si2-Al板状燃料组件的解体试验研究,得到了110 ℃水温、7 m/s流速下50 d的水力冲刷试验和18 m/s流速下的流致振动试验对该新型燃料组件各项参数的影响,为板状燃料组件的设计、选材、加工、应用提供了实验数据.     

钴靶组件流致振动试验研究

采用数值分析与试验研究相结合的方法,通过模拟反应堆内真实边界与流速,获得了钴靶组件的振动频率、振型等振动特性参数以及0.75～2 kg/s不同冷却剂流速下的响应试验数据;利用综合数值计算与试验测试结果对结构进行了疲劳评价。分析结果表明,靶件在0.75～2 kg/s流速下的各种响应有效值较小,可满足10 a寿命期限。     

绕丝棒束组件低流速时摩擦阻力实验研究

钠冷快堆在事故停堆余热排放期间,堆芯组件内钠流为自然循环流动,流速很低,因此准确确定绕丝棒束组件低流速时的摩擦阻力系数对钠冷快堆非能动余热排出系统的设计具有重要意义。本文以水为流动介质,准确测量了37棒和19棒绕丝棒束组件在低流速（Re<1 000）时的摩擦阻力系数。实验结果表明,随着流速的降低,绕丝棒束组件的摩擦阻力系数迅速升高,流动从层流向过渡流转变时,摩擦阻力系数有明显跃升。将实验测量值与绕丝棒束摩擦阻力系数经验公式的计算结果进行比较,发现在低流速时,经验公式计算结果较实验测量值明显偏小,同时经验公式计算的绕丝棒束层流向过渡流转变的临界Re较实验值偏大。     

凸台约束对快堆组件流致振动特性影响的实验研究

流致振动引起的组件相互碰撞以及流体持续冲刷导致的结构疲劳损伤,会威胁堆芯安全,有必要对快堆组件开展流致振动行为的研究和评价。采用有无固定凸台约束两种方式都会给组件的振动特性带来一定的不确定度。为研究凸台约束对快堆组件流致振动特性的影响,定量评价有无固定凸台约束对组件振动特性带来的不确定度,本文采用实验方法研究了组件上端自由和有0.3 mm间隙的固定凸台约束两种条件下组件的流致振动特性。实验结果表明,组件在有无固定凸台约束条件下最大振幅均方根（RMS）间的相对偏差为6.1%,对于最靠近凸台处测点的幅值,有无凸台约束的最大振幅RMS间的相对偏差为17.4%。本文实验结果对该种复杂支撑条件下组件流致振动行为的分析与评价具有一定的参考价值。     

六边形组件流致振动响应数值分析

工程堆用六边形组件受到冷却剂的作用会发生流致振动,采用数值分析方法对六边形组件的振动特性和流致振动响应进行分析研究,通过数值仿真计算了六边形组件在空气中和静水中的一阶固有频率及相应振型,并结合试验结果运用流致振动响应计算方法研究了流体力作用下结构的动力响应,获得了响应的最大应变值。计算结果和试验结果精度在同量级,验证了本文数值分析方法在六边形组件流致振动响应研究的可行性。     

中国先进研究堆(CARR)工程燃料组件设计验证试验

中国先进研究堆(CARR)采用的燃料组件在国内尚属首次加工与使用。为了保证燃料组件的完整性和安全性,满足堆安全运行的需要,对燃料板和组件的结构稳定性、流致振动、临界流速、热循环、堆内辐照等进行了设计验证试验。结果表明,CARR燃料组件的设计和加工工艺是合理的,谈组件在反应堆实际运行条件下是稳定和安全的。     

压水堆燃料组件附加质量仿真研究

为了准确探究反应堆冷却剂与燃料组件间存在流固耦合行为对燃料组件振动特性的影响,本文采用计算流体动力学（CFD）软件Fluent平台,运用其中的动态网格技术,以压水堆燃料组件为研究对象,通过建立燃料组件模拟棒束、堆芯围板以及冷却剂模型,实现燃料组件与堆芯围板分别单独运动工况的燃料组件附加质量计算。结果显示：燃料组件运动工况下,燃料组件附加质量系数均值为2.4712;围板运动工况下,燃料组件附加质量系数均值为–3.4713,均与文献值偏差小于5%。叠加附加质量后,燃料组件振动频率计算值与水中振动试验测试结果偏差小于5%,验证了分析方法的合理性。本研究建立的仿真计算方法能够用于压水堆燃料组件附加质量计算。     

Chatter suppression methods of a robot machine for ITER vacuum vessel assembly and maintenance

In the process of assembly and maintenance of ITER vacuum vessel (ITER VV), various machining tasks including threading, milling, welding-defects cutting and flexible hose boring are required to be performed from inside of ITER VV by on-site machining tools. Robot machine is a promising option for these tasks, but great chatter (machine vibration) would happen in the machining process. The chatter vibration will deteriorate the robot accuracy and surface quality, and even cause some damages on the end-effector tools and the robot structure itself. This paper introduces two vibration control methods, one is passive and another is active vibration control. For the passive vibration control, a parallel mechanism is presented to increase the stiffness of robot machine; for the active vibration control, a hybrid control method combining feedforward controller and nonlinear feedback controller is introduced for chatter suppression. A dynamic model and its chatter vibration phenomena of a hybrid robot is demonstrated. Simulation results are given based on the proposed hybrid robot machine which is developed for the ITER VV assembly and maintenance.     

Flow Induced Vibrations in Gas Tube Assembly of Centrifuge

A centrifuge essentially consists of a rotor rotating at very high speed. Gas tube assembly, located at the center of the rotor, is used to introduce feed gas into the rotor and remove product and waste streams from it. The gas tube assembly is thus a static component, the product and waste scoops of which are lying in the high pressure region of a fluid rotating at very high speed. This can cause flow induced vibrations in the gas tube assembly. Such vibrations affect not only the mechanical stability of the gas tube assembly but may also reduce the separative power of the centrifuge. In a cascade, if some of the centrifuges have gas tube vibration, then cascade performance will be affected.

A theoretical analysis of the effect of waste tube vibrations on product and waste flow rates and pressures in the centrifuge is presented. A simple stage consisting of two centrifuges, in which one has tube vibration, is considered for this purpose. The results are compared with experiment. It is shown that waste tube vibration generates oscillations in waste and product flow rates that are observable outside the centrifuge.     

采用变化附加阻尼的快堆堆芯组件抗震分析方法的研究

对快堆堆芯组件进行的抗震分析需要考虑冷却剂与堆芯组件之间的流固耦合作用。在之前的分析中,大多数人将流体附加阻尼处理为定值。实际上冷却剂对组件的作用还随着组件间的间隙变化而变化,其带来的附加阻尼应为变量。为更准确地模拟堆芯组件的振动,本文采用变化附加阻尼对快堆堆芯组件的抗震分析方法进行了研究。建立了快堆堆芯单排（5根）堆芯组件的抗震分析计算模型,对该模型进行了附加阻尼为定值和随间隙变化两种情况下的抗震分析,结果显示了考虑变化附加阻尼的堆芯组件抗震分析方法的可行性与有效性。本文所使用的模拟方法更为贴近堆芯组件的振动情况,为更为真实地模拟快堆堆芯组件的地震响应打下基础,这也有助于减少结构设计的保守性,具有一定的工程价值。     

A study on mechanical properties and flow-induced vibrations of coil-shaped holddown spring

The fuel assemblies used in the OPR1000s in Korea employ four coil-shaped hold-down springs to exert compressive load at the top of fuel assembly so that the assemblies may not be damaged by preventing its hydraulic-induced lifting-off from its lower seating surface. However, the coolant flow generates the flow-induced vibration at the coil-shaped hold-down springs which may cause wear on the spring surfaces. A hold-own spring may be fractured if torsional stress acting on its worn area exceeds a stress limit, resulting in the loss of hold-down spring force of the fuel assembly. In this paper, flow-induced vibration tests were performed for standard and improved coil type hold-down springs to investigate the effects of these two hold-down spring designs on flow-induced vibration wear. In parallel, a wide spectrum of mechanical tests was performed to obtain vibration-related characteristics of these two hold-down springs, which can be used as input data for the fuel assembly static and dynamic analysis. It is found that the improved hold-down spring design is better against flow-induced vibration wear than the standard one. With the use of the three-dimensional Solidwork model, the stress-related design lifetime of the improved hold-down spring was estimated by extrapolating its wear data measured from the flow-induced vibration tests, which indicates that the improved HD spring design will maintain integrity during the fuel design lifetime in OPR1000s in Korea.     

压水堆燃料组件抗震试验研究

燃料组件属I类抗震物项,其抗震问题直接关系核电厂运行安全,通常需通过抗震试验验证反应堆燃料组件抗震分析方法的合理性。本文模拟反应堆实际堆芯燃料组件安装方式,设计压水堆燃料组件抗震试验件与试验装置,针对不同组件数量布置方案,在高性能地震模拟振动台上开展试验研究。结果表明,水介质中燃料组件的第一阶频率为2.96 Hz,最大冲击力出现在燃料组件偏中间位置处,试验获取了地震作用下燃料组件的格架冲击力、格架相对位移、模拟堆芯板与围板的加速度等响应。试验结果可用于设计基准事故工况中燃料组件抗震分析模型的建立与分析软件的验证。