PhD Studentship: Modelling of precipitation reactors in the reprocessing of spent nuclear fuel

Lead Supervisor’s full name & email address

Dr Tariq Mahmud - [email protected]

Co-supervisor name(s) & email address(s)

Professor Kevin J Roberts - [email protected]

Project summary

Nuclear power generation is expected to rise to meet increasing UK and global energy demand, whilst maintaining net-zero targets. In this context, reprocessing of waste from nuclear reactors in order to recover and reuse uranium (U) and plutonium (Pu) will play a critical role in the spent nuclear fuel (SNF) management. The proposed project focuses on the unit operation in SNF reprocessing, which involves precipitation of Pu(IV) oxalate or co-precipitation of U(IV)/Pu(III) oxalate crystals via the reactions between Pu and U nitrates and oxalic acid. The crystal morphology and size distribution influence the efficiency of downstream processing, such as filtration and calcination, and the performance of fuel. The precipitation reactions are performed in a continuous unbaffled vortex reactor agitated with a magnetic stirrer, which was initially developed by the UKAEA in the early 1950’s. A detailed understanding of the reactor hydrodynamic and mixing characteristics is needed and how it affects the precipitation process and resulting crystal properties.

This PhD project builds on our previous studies on the precipitation of Ca and Ce oxalates as simulants. It aims to address challenges associated with the development and application of digital process modelling tools to investigate the influence of reactor design and processing conditions on the crystal properties. In this project, precipitation process models, based on a population balance model, will be developed for the prediction of crystal size distribution, which will be integrated with a Computational Fluid Dynamics (CFD) software (e.g. ANSYS Fluent) for taking into account the effect of the reactor hydrodynamics and mixing. Experiments will be carried out to collect data as necessary for model development and refinement. The model can be used as an effective tool for providing an improved understanding of the underpinning science of precipitation processes and optimising the reactor design and safe operating conditions to produce crystals with a required size and shape distributions.

Candidates will have, or be due to obtain, a Master’s Degree or equivalent from a reputable university in an appropriate field of Engineering. Exceptional candidates with a First Class Bachelor’s Degree in an appropriate field will also be considered.

Subject Area

Applied Chemistry, Industrial Chemistry, Atomic Engineering, Chemical Engineering, Energy Technologies, Fluid Mechanics, Mechanical Engineering, Applied Mathematics, Engineering Mathematics, Mathematical Modelling, Nuclear Physics