Transport Phenomena in Nuclear Applications

Student projects

Projects in red are currently occupied. Note that those projects may become available soon. If you are interested in one of those projects, please contact me.

You can also find projects at the Pick Your Project website https://pyp.tnw.tudelft.nl/pyp

Nuclear reactor physics with the lattice-Boltzmann method

Msc

LBM is mostly used for fluid flow and scalar transport (heat, species). A lesser known feature, however, is the fact that the method can also be used for neutron transport and be coupled to momentum and energy transport. Recently, researchers have extended the method for neutronics. In this project, the method will be applied to either a molten-salt reactor case or the DIPR, a reactor in which radio-isotopes can be produced. If you are interested, we can start a discussion on the exact topic to be done.

Free

Melting and freezing in a nuclear molten salt reactor's heat exchanger under turbulent conditions: understanding channel flow and ice layer development

MSc/BSc

The molten salt reactor is a very safe and sustainable nuclear reactor. The reactor fuel is liquid instead of solid, making this type of reactor very safe. Freezing may occur in the heat exchanger, risking blockage of the cooling channels. To understand freezing under turbulent conditions, one needs either perform experiments or simulations. This project deals with LES simulations under turbulent conditions, thereby using the lattice-Boltzmann method. This method can easily be implemented on GPU's, so that large calculations speeds can be accomplished. Challenges in this project are the development of such an efficient code in the Julia language, in conjunction with Large Eddy Simulations (to model the turbulence).

Free

Modelling the freeze plug in a nuclear molten salt reactor: investigating the angle dependendy

Msc

The molten salt reactor is a very safe and sustainable nuclear reactor. One of the key safety features is the freeze plug, which can be used in case of an emergency situation. The plug is kept frozen actively and melts as soon as the active freezing stops (e.g. by a station blackout). The plug needs to melt quickly to drain the reactor vessel as fast as possible. The angle of the freeze plug is important because the melting occurs partially by natural circulation. Hence, the orientation of gravity with respect to the plug is important.

Free

Characterization of Helium-Bubbling in a Molten Salt Reactor for the Removal of Fission Products

Msc

During the operation of molten salt reactors valuable fission products are formed. Due to the extreme working environment, a removal of those particles is challenging. One promising technology to remove fission products is the separation via helium bubbling. Here, the fission particles are adhering to the helium bubbles, from which they are getting transported to the liquid surface, from where they can get separated. Part of the research is building up a setup for experiments with molten salts, in which the flow characteristics and particle removal are determined by methods like the Laser-Doppler-Anemometry and Particle Image Velocimetry. In a first step, experiments will be conducted at room temperature in water and a model system consisting of water/glycerol, which is well established to mimic the characteristics of the molten salt. From these results, operating conditions will be determined, which will be used in a later step with the molten salt setup at elevated temperatures. Moreover, numerical work in the form of CFD-simulations can be included to obtain additional information about the phenomena inside the reactor.

Occupied

Natural convection in supercritical fluids - an LBM study

Msc

Supercritical fluids are being used in a wide range of applications such as chemical processes (e.g. extration) and energy processes (e.g. heat removal, nuclear reactors). In this study, the student is going to use and extend the lattice-Boltzmann Method for supercritical fluids and study the phenomenon of natural convection under laminar (and perhaps) turbulent conditions.

Occupied

Simulation of Microfluidic-Multiphase Flow in a Y-Y channel using a Modified Surface Tension Term

Msc

Microfluidic multiphase flow is a topic of increasing interest because of its applications and the possibilities it offers in various fields. The major advantages of operating in the microscale include the large surface-volume ratios, control of fluid flow and lower costs. Two common methods used for simulating such flows are Volume-of-Fluid (VOF) and the Lattice Boltzmann method. Both these methods have proven to effectively simulate flows at higher Capillary numbers (ratio of viscous and interfacial forces), where the influence of surface tension is less important. However, at lower Capillary numbers, both methods are not as effective. A major reason for this is related to the implementation of surface tension in both methods, where the Continuous Surface Force (CSF) method proposed by Brackbill et al (1992) is used. The CSF method is known to generate spurious (numerical) velocities, and these velocities are observed to have an impact on the simulation results at low Capillary numbers. Since many applications, including radioisotope transfer, involve flows at lower Capillary numbers, modifications are necessary to enhance the capabilities of the methods. Some modifications have been proposed for the CSF term in the VOF method which involve filtering these spurious velocities (Raeini et al 2014, Aboukhedr et al 2018). These modifications have proven to be successful when it comes to simulating simple cases such as a suspended droplet in another fluid. However, the aim is to extend this to simulate more complex scenarios, such as multiphase flow in a Y-Y channel. This thesis thus seeks to study the effectiveness of these modifications by comparing the simulations with experiments which have already been performed. The student will work with VOF using OpenFoam as it has the library containing the modified CSF term. All flow regimes observed in a Y-Y channel will be considered, and the student can study how effective the modifications are for each regime. Possible improvements to the model can also be proposed after the code has been tested.

Unavailable

Martin Rohde (2023)