Development of a Method for Malfunction Detection of the Primary Cooling Loop in a Research Reactor

研究堆的一次冷却水通常由一个固定转速的单泵进行循环。因此，由泵的旋转运动引起的特征频率分量分别包含在冷却系统的振动、水压波动和冷却剂流量的变化中。当冷却循环回路发生异常时，由于泵的负荷波动，冷却系统的振动分量会脱离特征频率，因此，我们计划利用冷却系统振动数据的频谱分析，发展一种新的研究堆故障检测方法。为此，准备了一个带有循环泵、水槽和一些阀门的模拟冷却系统。利用数字式数据记录仪采集振动、水压和冷却剂流量等数据，利用FFT技术分析频率的功率谱，发现当冷却系统发生吸气、水回路堵塞等异常情况时，分析数据中的频率和幅值会发生谱移。我们得到了两个结论，在整个实验：本方法是有效的研究堆的主冷却回路的故障检测，并将使一些小型设备连接到个人计算机的实时诊断。

The primary cooling water of research reactor ia usually circulated by a single pump rotating at a fixed speed of revolution. Therefore, characteristic frequency components caused by the rotational motion of pump are contained in the vibration of the cooling system, the fluctuation of water-pressure and the variation of coolant flow rate, respectively. When an abnormal matter happens in the cooling circulation-loop, the vibration component of the cooling system breaks away from the characteristic frequency due to the load fluctuation of the pump.We have planned to develop a new method for malfunction detection of aresearch reactor using a spectrum analysis of vibration data in the cooling system. For this purpose, a mock-up cooling system was prepared with a circulation pump, a water thank and some valves. The data of vibration, water-pressure and coolant flow rate are sampled by a digital data logger, and the power spectra of frequency are analyzed by a FFT technique.Once abnormal matters such as the inhalation of air and the blockade of water loop have happened in the cooling system, the spectral shift of the frequency and amplitude appeared in analyzed date. We obtained two conclusions throughout this experiment : the present method is effective for malfunction detection of the primary cooling loop in a research reactor, and will enable a real-time diagnosis by means of some small-scale equipment connected to a personal computer.