SPH For Multiphase Flows Inside a HAL Storage Tank

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This project is to use Smoothed Particle Hydrodynamics (SPH), an innovative meshless computational technique ideal for potentially violent free-surface hydrodynamics where there is strong nonlinearity with highly complex moving geometries. The research developed here will be applicable to flows in nuclear decommissioning in hydraulic structures and the heat-generating flows in the nuclear industry. The project will address the important issues of identifying the best techniques for modelling complex mixtures in the context of predicting the resultant hydrodynamics, identify effects of different mechanisms, apply to test cases involving data on deposits available in the literature and for cases provided by National Nuclear Laboratory (NNL) in the UK. More specific detail: Highly active liquor (HAL) is generated during the reprocessing of spent nuclear fuel. The resulting waste stream is corrosive, chemically complex and heat-generating. It comprises two main phases: a liquid layer and a viscous sediment, the sediment contains the majority of the activity and generates heat via radioactive decay. Prior to vitrification, the waste stream is stored in large tanks; the waste is agitated regularly to avoid the formation of local hot-spots which would otherwise enhance corrosion and reduce the facility's operational lifetime. The PhD will focus on the simulation of the complex mixtures in the agitation systems within the storage tanks. This complex multi-phase problem is not amenable to traditional modern techniques, which struggle to capture the liquid/sediment interface. The work will build upon a previous PhD project, which was completed in 2014 (Fourtakas), developing new SPH formulations using the acceleration provided by graphics processing units (GPUs) in the open-source code DualSPHysics: http://www.dual.sphysics.org