Investigation of the acoustic pressure pulsations in piping system and their effect on the dynamic response of CANDU fuel bundles

在诸如发电站的工业应用中使用的管道系统易于产生压力脉动，这通常由往复泵的使用和/或阀的动态不稳定性引起，其可以充当不期望的噪声和振动的源。在这些脉动源的频率对应于管道系统的共振频率的情况下，可能导致非常危险的声学共振条件，这可能产生非常大的压力波动，通常是主管道中流动的动压头的几倍，以及管道系统和周围部件的显著振动。这些情况被称为声致振动（AIV），可能会导致垫圈和密封件破裂、阀门故障等泄漏问题，严重时还会导致管道系统、相关部件和仪表的疲劳和断裂。对安大略发电厂（OPG）生产产生重大影响的此类故障的一个例子与CANDU核燃料棒故障有关。1990年，达林顿核电站的一个燃料棒束由于燃料元件的过度振动而损坏。因此，本项目的主要目标是实验研究被动声阻尼装置对管道系统中声压脉动衰减的有效性，并数值模拟CANDU燃料棒束由于声压脉动的动态响应。从这项研究中获得的知识将提供实用的设计指导方针，实施新的被动声阻尼装置在管道系统中，以防止声压脉动的发生。此外，一个更现实的三维模型预测燃料棒束振动响应流体激励和声压脉动将开发。这不仅有助于提高核电厂管道系统的安全性和可靠性，这将直接有利于加拿大的经济，而且还可用于未来的CANDU反应堆，以避免由于上述激励机制而导致的燃料棒束故障。

Piping systems used in industrial applications such as power stations are liable to generation of pressure pulsations, often arising from the use of reciprocating pumps and/or dynamic instability of valves, which can act as sources of unwanted noise and vibration. In the event that the frequencies of these pulsating sources correspond to the resonant frequencies of the piping system, a very dangerous acoustic resonance condition can result, which can produce extremely large pressure fluctuations, often several times the dynamic head of the flow in the main pipe, as well as substantial vibration of the piping system and surrounding components. These conditions, referred to as Acoustic Induced Vibrations (AIV), can lead to issues with leakage due to gasket and seal ruptures, valve failure, and in serious cases, fatigue and fracture of the piping system, related components and instrumentation. An example of such failure which had a great impact to Ontario Power Generation's (OPG) production was related to CANDU nuclear fuel bundle failures. In 1990, one of the fuel bundles in the Darlington nuclear power plant was damaged as a result of excessive vibration of the fuel elements. Therefore, the main objectives of this project are to experimentally investigate the effectiveness of passive acoustic damping devices on the attenuation of acoustic pressure pulsations in piping system and to numerically simulate the dynamic response of CANDU fuel bundle due to acoustic pressure pulsations. The gained knowledge from this research will provide practical design guidelines for implementation of new passive acoustic damping devices in piping systems to prevent the occurrence of acoustic pressure pulsations. Moreover, a more realistic three dimensional model for predictions of the fuel bundle vibration response to fluid excitations and acoustic pressure pulsations will be developed. This will not only support the increased safety and reliability of piping systems in nuclear power plants which will directly benefit the Canadian economy, but also could be used in future CANDU reactors to avoid fuel bundle failure due to the aforementioned excitation mechanism.