Experimental and computational investigation of cavitation phenomena in heavy liquid metals

This PhD project aims to investigate cavitation phenomena in heavy liquid metals, specifically lead and lead-bismuth alloys, which are utilized as coolants in Small Modular Reactors (SMRs) and advanced Generation IV nuclear reactors. Cavitation – the formation and collapse of vapor cavities in a liquid – is a significant challenge in these nuclear systems, particularly for the primary pump impeller. It can lead to increased material erosion, vibrations, and noise, potentially compromising the primary pump’s integrity and the longevity of nuclear energy systems.

The research focuses on the development of new methods to accurately predict cavitation in heavy liquid metals through a combination of computational and experimental approaches. The computational aspect involves developing advanced CFD models tailored to the unique properties of heavy liquid metals, such as high density, non-wetting behavior, and low vapor pressure. The new models should improve the accuracy of cavitation predictions in heavy liquid metal environments.

A dedicated ultrasonic cavitation facility will be used in the project to verify the computational models experimentally, by creating cavitation under controlled circumstances as a function of several key parameters, such as temperature, pressure, and the amplitude of ultrasonic vibrations. Since the set-up is designed in accordance with international standards, it facilitates a direct comparative analysis with results obtained in other laboratories across different liquids and materials.

An in-depth understanding of the parameters influencing cavitation and the integration of this knowledge into accurate CFD simulations, despite the differences in the cavitation formation mechanisms between ultrasonic and hydrodynamic cavitation, will enhance the accuracy of cavitation predictions in realistic applications, particularly in pump impellers. This will enable the optimization of the cavitation margin, improving pump reliability and lifespan without increasing the cost of the reactor system.