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

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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.****